To see the other types of publications on this topic, follow the link: Lois radiales.
Journal articles on the topic 'Lois radiales'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Lois radiales.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Schmitt, Denis P., Michel Bouchon, and Guy Bonnet. "Full‐wave synthetic acoustic logs in radially semiinfinite saturated porous media." GEOPHYSICS 53, no. 6 (June 1988): 807–23. http://dx.doi.org/10.1190/1.1442516.
Full textAbstract:
The wave field generated by a point source in an axisymmetric fluid‐filled borehole embedded in a saturated porous formation is studied in both the spectral domain and time domain. The formation is modeled following Biot theory modified in accordance with homogenization theory. When the borehole wall is permeable, guided waves can be significantly affected by the permeability of the formation. Whatever the formation, fast or slow, Stoneley‐wave phase velocity and energy decrease and attenuation (in the sense of [Formula: see text]) increases with increasing permeability. These effects are more important in the very low‐frequency range, where Darcy’s law governs the fluid motion and the wave energy at the interface is maximum, than at higher frequencies. The effects increase and persist over a larger frequency range with decreasing viscosity and increasing compressibility of the saturant fluid, with increasing pore‐fluid volume, and with decreasing borehole radius. In contrast, the effects decrease with decreasing stiffness of the formation because of more efficient coupling of the interface wave to the surrounding medium. When present, the first pseudo‐Rayleigh mode also carries useful information. Fluid flow affects only the attenuation of the pseudo‐Rayleigh mode’s Airy phase; an increase in attenuation may be used to detect permeable zones and to infer the saturant fluid properties. However, the most reliable types of information are the formation shear‐wave velocity and attenuation from the low‐frequency part of the mode. In the time domain, all the modes overlap. Any signal processing should then be performed in the frequency domain, where mode spectra are more easily separable. The frequency band of the actual logging tool has to be large enough to ensure significant amplitude for each mode. Finally, the larger the number of receivers and the offset range, the better.
2
Heidari, Zoya, Carlos Torres-Verdín, and William E. Preeg. "Improved estimation of mineral and fluid volumetric concentrations from well logs in thinly bedded and invaded formations." GEOPHYSICS 77, no. 3 (May 1, 2012): WA79—WA98. http://dx.doi.org/10.1190/geo2011-0454.1.
Full textAbstract:
Calculation of mineral and fluid volumetric concentrations from well logs is one of the most important outcomes of formation evaluation. Conventional estimation methods assume linear or quasi-linear relationships between volumetric concentrations of solid/fluid constituents and well logs. Experience shows, however, that the relationship between neutron porosity logs and mineral concentrations is generally nonlinear. More importantly, linear estimation methods do not explicitly account for shoulder-bed and/or invasion effects on well logs, nor do they account for differences in the volume of investigation of the measurements involved in the estimation. The latter deficiencies of linear estimation methods can cause appreciable errors in the calculation of porosity and hydrocarbon pore volume. We investigated three nonlinear inversion methods for assessment of volumetric concentrations of mineral and fluid constituents of rocks from multiple well logs. All three of these methods accounted for the general nonlinear relationship between well logs, mineral concentrations, and fluid saturations. The first method accounted for the combined effects of invasion and shoulder beds on well logs. The second method also accounted for shoulder-bed effects but was intended for cases where mud-filtrate invasion is negligible or radially deep. Finally, the third method was designed specifically for analysis of thick beds where mud-filtrate invasion is either negligible or radially deep. Numerical synthetic examples of application indicated that nonlinear inversion of multiple well logs is a reliable method to quantify complex mineral and fluid compositions in the presence of thin beds and invasion. Comparison of results against those obtained with conventional multimineral estimation methods confirmed the advantage of nonlinear inversion of multiple well logs in quantifying thinly bedded invaded formations with variable and complex lithology, such as those often encountered in carbonate formations.
3
Deliiski, Nencho, Veselin Brezin, and Natalia Tumbarkova. "Modelling of the 1D Convective Heat Exchange between Logs Subjected to Freezing and to Subsequent Defrosting and the Surrounding Environment/ Egydimenziós konvektív hővezetés modellezése fagyott és normál állapotú rönk és környezte között." Acta Silvatica et Lignaria Hungarica 11, no. 1 (June 1, 2015): 77–88. http://dx.doi.org/10.1515/aslh-2015-0006.
Full textAbstract:
Abstract A 1D mathematical model for the computation of the temperature on the surface of cylindrical logs, tsr, and the non-stationary temperature distribution along the radiuses of logs subjected to freezing and subsequent defrosting at convective exponentially changing boundary conditions has been suggested. The model includes mathematical descriptions of the thermal conductivity in radial direction, λr, the effective specific heat capacity, ce, and the density, ρ, of the non-frozen and frozen wood, and also of the heat transfer coefficient between the surrounding air environment and the radial direction of horizontally situated logs, αr. With the help of the model, computations have been carried out for the determination of αr, tsr, λsr, and 1D temperature distribution along the radiuses of beech logs with diameters of 0.24 m, initial temperature 20 °C, and moisture content 0.4 kg·kg-1, 0.8 kg·kg-1, and 1.2 kg·kg-1, during their freezing at -20 °C, and during subsequent thawing at 20 °C.
4
Ono, Sergio Eiji, Arnolfo de Carvalho Neto, Emerson Leandro Gasparetto, Luiz Otávio de Mattos Coelho, Dante Luiz Escuissato, Carmem Maria Sales Bonfim, and Lisandro Lima Ribeiro. "Adrenoleucodistrofia ligada ao X: correlação entre o escore de Loes e parâmetros do tensor de difusão." Radiologia Brasileira 47, no. 6 (December 2014): 342–49. http://dx.doi.org/10.1590/0100-3984.2013.1886.
Full textAbstract:
Objetivo: Avaliar a correlação dos parâmetros do tensor de difusão com o escore de Loes e se os parâmetros do tensor de difusão poderiam indicar alterações estruturais precoces. Materiais e Métodos: As medidas do tensor de difusão foram obtidas em 30 exames de 14 pacientes com adrenoleucodistrofia ligada ao X e foram correlacionadas com o escore de Loes. Um grupo controle de 28 pacientes masculinos foi avaliado para estabelecer medidas do tensor de difusão pareadas por idade. Análises estatísticas intra e interobservador foram feitas. Resultados: As medidas do tensor de difusão apresentam forte correlação com o escore de Loes segundo o coeficiente de Pearson (r), com valores de –0,86, 0,89, 0,89 e 0,84 para a fração de anisotropia e difusibilidades média, radial e axial (p < 0,01). A análise da mudança nas medidas do tensor de difusão no estágio inicial da doença indica que os valores de difusibilidades média e radial podem ajudar a predizer a progressão da doença. Conclusão: As medidas de parâmetros do tensor de difusão poderiam ser usadas como um adjunto ao escore de Loes, auxiliando no monitoramento da doença e alertando uma possível progressão do escore de Loes na faixa de interesse para decisões terapêuticas.
5
Kharrat, Wassim, Roger E. Hernández, Claudia B. Cáceres, and Carl Blais. "Ring debarking efficiency of frozen balsam fir logs is affected by the radial force but not by the log position on the stem." Canadian Journal of Forest Research 50, no. 12 (December 2020): 1323–32. http://dx.doi.org/10.1139/cjfr-2020-0116.
Full textAbstract:
The effect of the radial force applied by a ring debarker tip to frozen balsam fir (Abies balsamea (L.) Mill.) logs, obtained at three positions on the stem, was studied. A one-armed ring debarker prototype was built, which controlled the radial force, the rake angle, and cutting and feed speeds. Balsam fir logs at −19 °C were debarked at three levels of radial force. The rake angle, tip overlap, tip edge radius, and cutting and feed speeds were kept constant. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood fibres in bark residues. Log characteristics (dimensions, eccentricity, bark thickness, and knot features), bark–wood shear strength, and the basic densities of sapwood and bark were also measured. Results showed that the radial force had a significant effect on debarking quality. The proportion of bark remaining on log surfaces increased while the amount of wood fibres in bark residues decreased as radial force decreased. A radial force of 18.5 N·mm−1 is suggested for an optimal debarking quality. In contrast, log position on the stem did not affect the debarking quality indicators. Results also showed that the proportion of bark remaining on log surfaces increases as bark–wood shear strength and the proportion of knot surface increase, while the amount of wood fibres in bark residues increases as bark–wood shear strength decreases and logs are more eccentric. The results give useful information to improve the debarking process within the studied range of log diameters and debarking parameters.
6
Bonduelle, Ghislaine Miranda, Setsuo Iwakiri, Rosilani Trianoski, José Guilherme Prata, and Vinicius Yurk Rocha. "ANÁLISE DA MASSA ESPECÍFICA E DA RETRATIBILIDADE DA MADEIRA DE Tectona grandis NOS SENTIDOS AXIAL E RADIAL DO TRONCO." FLORESTA 45, no. 4 (March 29, 2015): 671. http://dx.doi.org/10.5380/rf.v45i4.31991.
Full textAbstract:
O objetivo deste trabalho foi avaliar a massa específica e a retratibilidade da madeira nos sentidos axial e radial do tronco. Foram coletadas cinco árvores com 18 anos, provenientes do município de Brasnorte, MT, as quais foram seccionadas nas posições da base, meio e topo, para avaliação das propriedades no sentido axial. Da parte diametral das toras foram obtidos pranchões onde foram controladas as posições radiais. A avaliação da massa específica e da retratibilidade da madeira seguiu as recomendações da norma panamericana. Os resultados demonstraram que a teca possui massa específica aparente a 12% de 0,606 g.cm-3, massa especifica básica de 0,524 g.cm-3 e fator anisotrópico de 2,271. Não foram observadas grandes variações de propriedades tanto no sentido axial quanto no radial. As propriedades físicas demonstram que a madeira possui média estabilidade dimensional, podendo ser indicada para aplicações em laminação, lambris, portas, decoração e movelaria. AbstractAnalysis of wood density and shrinkage of Tectona grandis wood in axial and radial direction of the tree trunk. This research aimed to evaluate density and shrinkage of wood in axial and radial directions of the tree. We collected five trees aged 18, from the city of Brasnorte, MT, which were cut at the base, middle and top, for evaluation of the properties in axial direction. We obtained planks from the diametric part of the logs, from which we controlled radial positions. The evaluation of density and shrinkage of wood followed the panamerican standard recommendations. The results revealed that teak has apparent density at 12% of 0.606 g.cm-3, basic density 0.524 g.cm-3, and anisotropic fator of 2,271. There were no major variations in properties both in axial and radial direction. The physical properties demonstrate that the timber has medium dimensional stability, and it could be used in peeling, sidings, doors, decorating and furniture industry.Keywords: Teak; anisotropy; dimensional stability; wood quality.
7
Heidari, Zoya, and Carlos Torres-Verdín. "Estimation of dynamic petrophysical properties of water-bearing sands invaded with oil-base mud from the interpretation of multiple borehole geophysical measurements." GEOPHYSICS 77, no. 6 (November 1, 2012): D209—D227. http://dx.doi.org/10.1190/geo2012-0006.1.
Full textAbstract:
Nonmiscible fluid displacement without salt exchange takes place when oil-base mud (OBM) invades connate water-saturated rocks. This is a favorable condition for the estimation of dynamic petrophysical properties, including saturation-dependent capillary pressure. We developed and successfully tested a new method to estimate porosity, fluid saturation, permeability, capillary pressure, and relative permeability of water-bearing sands invaded with OBM from multiple borehole geophysical measurements. The estimation method simulates the process of mud-filtrate invasion to calculate the corresponding radial distribution of water saturation. Porosity, permeability, capillary pressure, and relative permeability are iteratively adjusted in the simulation of invasion until density, photoelectric factor, neutron porosity, and apparent resistivity logs are accurately reproduced with numerical simulations that honor the postinvasion radial distribution of water saturation. Examples of application include oil- and gas-bearing reservoirs that exhibit a complete capillary fluid transition between water at the bottom and hydrocarbon at irreducible water saturation at the top. We show that the estimated dynamic petrophysical properties in the water-bearing portion of the reservoir are in agreement with vertical variations of water saturation above the free water-hydrocarbon contact, thereby validating our estimation method. Additionally, it is shown that the radial distribution of water saturation inferred from apparent resistivity and nuclear logs can be used for fluid-substitution analysis of acoustic compressional and shear logs.
8
Zúñiga Liñán, Luis Carlos. "Sensationalist radio reception in young people from Cartagena de Indias." Investigación & Desarrollo 22, no. 2 (July 1, 2014): 237–57. http://dx.doi.org/10.14482/indes.22.2.5114.
Full text
9
Siddique, Aamir, Rehan Riaz, and Imran Javaid. "CORONARY CATHETERIZATION." Professional Medical Journal 25, no. 05 (May 7, 2018): 735–39. http://dx.doi.org/10.29309/tpmj/18.4428.
Full text
10
Queiroz, Elvio Cardoso, Regina Helena Marino, and Augusto Ferreira da Eira. "Mineral supplementation and productivity of the Shiitake mushroom on eucalyptus logs." Scientia Agricola 61, no. 3 (June 2004): 260–65. http://dx.doi.org/10.1590/s0103-90162004000300003.
Full textAbstract:
Brazilian reports on Shiitake mushroom [Lentinula edodes (Berkeley) Pegler] productivity grown on Eucalyptus saligna (Sm.) logs are optimistic. The current production on this kind of wood is, however, low and variable. Aiming at increasing Shiitake mushroom productivity, the present work studied interactions among three concentrations of mineral supplement and three Shiitake strains (Le 95/01, 96/17 and 96/18) grown on seventh cut eucalyptus logs. Mineral fertilization was carried out when the logs were submerged in water to induce fruiting bodies, using the following saline concentrations: zero (no fertilizers added), 0.05% (equivalent to 0.35 g L-1 of ammonium sulfate with 18% nitrogen and 0.15 g L-1 of superphosphate with 34% phosphorus) and 0.50%. Fertilization of the Le 95/01 strain increased productivity, but logs inoculated with the Le 96/17 strain were more productive only at 0.05% concentration while in the Le 96/18 strain, mineral supplementation decreased in productivity. The radial growth of these Shiitake strains (in sawdust-agar medium and with the same saline concentrations used in the log experiment) showed that all strains reacted positively to fertilization and that positive results for the Le 95/01 strain and negative results for Le 96/18 on eucalyptus logs are due to the natural higher competitiveness of the first Le 95/01 in relation to the latter Le 96/18 strain. Mineral fertilization increases the productivity provided that the logs are well colonized by Shiitake mushrooms.
11
Naranjo, S. Solórzano, R. Moya, and S. Chauhan. "Early genetic evaluation of morphology and some wood properties of Tectona grandis L. clones." Silvae Genetica 61, no. 1-6 (December 1, 2012): 58–65. http://dx.doi.org/10.1515/sg-2012-0008.
Full textAbstract:
Abstract An early genetic evaluation of morphology and wood properties of Tectona grandis L. (teak) used two 4-yr-old trials with 36 clones x 3 blocks x 1 ramet (216 trees). Morphologic traits (breast height (DBH), heartwood (HWP), tree height) and some easily measured wood properties (specify gravity, tangential, radial and volumetric shrinkage; growth strain, and dynamic elastic modulus measured in standing tree, in logs, in green lumber and in dried lumber) were evaluated to establish clonal variations and their heritabilities. The broadsense heritability (Ĥ2 is greater than 0.3 for DBH, radial and volume shrinkage, growth strain and dynamic elastic modulus of standing trees and logs. DBH and tree height were not genetically correlated with any wood properties, although DBH was genetically correlated with tree height and the dynamic elastic modulus in dried-lumber. According with above results, the evaluation of heritability and genetic control of wood properties is limited when it is evaluated in the juvenile stage of T. grandis clones. However morphology (DBH and tree height), and two wood properties (radial and tangential shrinkage) and the dynamic elastic modulus of dried-lumber present opportunities in the heritability or genetic control values in juvenile and they can be introduced in the genetic program.
12
Alpak, Faruk O., Carlos Torres-Verdín, and Tarek M. Habashy. "Petrophysical inversion of borehole array-induction logs: Part I — Numerical examples." GEOPHYSICS 71, no. 4 (July 2006): F101—F119. http://dx.doi.org/10.1190/1.2213358.
Full textAbstract:
We have developed a new methodology for the quantitative petrophysical evaluation of borehole array-induction measurements. The methodology is based on the time evolution of the spatial distributions of fluid saturation and salt concentration attributed to mud-filtrate invasion. We use a rigorous formulation to account for the physics of fluid displacement in porous media resulting from water-base mud filtrate invading hydrocarbon-bearing rock formations. Borehole array-induction measurements are simulated in a coupled mode with the physics of fluid flow. We use inversion to estimate parametric 1D distributions of permeability and porosity that honor the measured array-induction logs. As a byproduct, the inversion yields 2D (axial-symmetric) spatial distributions of aqueous phase saturation, salt concentration, and electrical resistivity. We conduct numerical inversion experiments using noisy synthetic wireline logs. The inversion requires a priori knowledge of several mud, petrophys-ical, and fluid parameters. We perform a systematic study of the accuracy and reliability of the estimated values of porosity and permeability when knowledge of such parameters is uncertain. For the numerical cases considered in this paper, inversion results indicate that borehole electromagnetic-induction logs with multiple radial lengths of investigation (array-induction logs) enable the accurate and reliable estimation of layer-by-layer absolute permeability and porosity. The accuracy of the estimated values of porosity and permeability is higher than 95% in the presence of 5% measurement noise and 10% uncertainty in rock-fluid and mud parameters. However, for cases of deep invasion beyond the radial length of investigation of array-induction logging tools, the estimation of permeability becomes unreliable. We emphasize the importance of a sensitivity study prior to inversion to rule out potential biases in estimating permeability resulting from uncertain knowledge about rock-fluid and mud properties.
13
Ortega, Edwin, Mathilde Luycx, Carlos Torres-Verdín, and William E. Preeg. "Joint petrophysical interpretation of multidetector nuclear measurements in the presence of invasion, shoulder-bed, and well-deviation effects." GEOPHYSICS 82, no. 1 (January 1, 2017): D13—D30. http://dx.doi.org/10.1190/geo2016-0037.1.
Full textAbstract:
Recent advances in logging-while-drilling sigma measurements include three-detector thermal-neutron and gamma-ray decay measurements with different radial sensitivities to assess the presence of invasion. We have developed an inversion-based work flow for the joint interpretation of multidetector neutron, density, and sigma logs to reduce invasion, shoulder-bed, and well-deviation effects in the estimation of porosity, water saturation, and hydrocarbon type, whenever the invasion is shallow. The procedure begins with a correction for matrix and fluid effects on neutron and density-porosity logs to estimate porosity. Multidetector time decays are then used to assess the radial length of the invasion and estimate the virgin-zone sigma while simultaneously reducing shoulder-bed and well-deviation effects. Density and neutron porosity logs are corrected for invasion and shoulder-bed effects using two-detector density and neutron measurements with the output from the time-decay (sigma) inversion. The final step invokes a nuclear solver in which corrected sigma, inverse of migration length, and density in the virgin zone are used to estimate water saturation and fluid type. The fluid type is assessed with a flash calculation and Schlumberger’s Nuclear Parameter calculation code to account for the nuclear properties of different types of hydrocarbon and water as a function of pressure, temperature, and salinity. Results indicate that accounting for invasion effects is necessary when using density and neutron logs for petrophysical interpretation beyond the calculation of total porosity. Synthetic and field examples indicate that the mitigation of invasion effects becomes important in the case of salty mud filtrate invading gas-bearing formations. The advantage of the developed inversion-based interpretation method is its ability to estimate layer-by-layer petrophysical, compositional, and fluid properties that honor multiple nuclear measurements, their tool physics, and their associated borehole geometrical and environmental effects.
14
Holan, Jiří, and Vladimír Gryc. "The variability of pulp-wood basic specific gravity of softwood." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 52, no. 4 (2004): 73–82. http://dx.doi.org/10.11118/actaun200452040073.
Full textAbstract:
In the present study, basic density of pulpwood of Norway spruce (Piceas abies /L./ Karst.) and Scots pine (Pinus sylvestris L.) was investigated. The variability of basic density and factors applied are out of concern. Factors are characterised by localization along the log, growing conditions defined by geographic area of Czech Republic, diameter of log, and the storing of logs within transport loading. Basic density was determined on cores taken by modified Pressler borer in the radial direction from bark to pith. The average basic density of Norway spruce is comparable to Scots pine, as well as the variation coefficient. Basic density of Norway spruce was found 443 kg.m-3 (Vx = 13.9%) where as the Scots pine base density was 450 kg.m-3 (Vx = 15.5%). Basic density was significantly influenced by all factors assessed except the localization of cores along logs. The investigation demonstrated that basic density can be affected by locality of supply in comparison to within logs variability that have much lower importance.
15
Chen, L., J. L. Hou, J. L. Zhao, and R. de Grijs. "Open clusters: their kinematics and metallicities." Proceedings of the International Astronomical Union 3, S248 (October 2007): 433–39. http://dx.doi.org/10.1017/s1743921308019765.
Full textAbstract:
AbstractWe review our work on Galactic open clusters in recent years, and introduce our proposed large program for the LOCS (LAMOST Open Cluster Survey). First, based on the most complete open clusters sample with metallicity, age and distance data as well as kinematic information, some preliminary statistical analysis regarding the spatial and metallicity distributions is presented. In particular, a radial abundance gradient of −0.058±0.006 dex kpc−1 is derived. By dividing clusters into the age groups we show that the disk abundance gradient was steeper in the past. Secondly, proper motions, membership probabilities, and velocity dispersions of stars in the regions of two very young open clusters are derived. Both clusters show clear evidence of mass segregation, which provides support for the “primordial” mass segregation scenario. Based on the advantages of the forthcoming LAMOST facility, we have proposed a detailed open cluster survey with LAMOST (the LOCS). The aim, feasibility, and the present development of the LOCS are briefly summarized.
16
Ramakrishnan, T. S., and D. J. Wilkinson. "Water-Cut and Fractional-Flow Logs From Array-Induction Measurements." SPE Reservoir Evaluation & Engineering 2, no. 01 (February 1, 1999): 85–94. http://dx.doi.org/10.2118/54673-pa.
Full textAbstract:
Summary Despite the importance of relative permeabilities in reservoir simulation, no information regarding them is available from current logs. In this paper, for the first time, we demonstrate a continuous log of multiphase flow properties. Mud filtrate invasion is usually regarded as a process that corrupts the true logs. In reality, the multiphase flow characteristics that influence filtrate flow also determine the subsequent reservoir performance. We propose the notion that invasion is an experiment, albeit uncontrolled, that may be used to invert for multiphase flow properties. Thus, in principle, inversion of array induction measurements in terms of the fractional flow curve is possible. The forward model for filtrate invasion is based on two-phase (aqueous and oleic), three-component (oil, water and salt) transport. Hysteretic behavior of relative permeability functions is included. The radial conductivity profiles calculated from the flow model are converted to induction logs using radial response functions. An algorithm for rapid calculations of the forward logs by combining the electromagnetic and flow models is developed. A nonlinear least squares method is used for parameter inversion from measurements. Additional data of near-wellbore resistivity, or logs obtained during drilling, may be included. Presentations for several output logs have been developed: a reserves estimate that partitions porosity into residual and movable saturations, initial water cut in the production stream, the fractional flow curve as a function of saturation, filtrate loss per unit depth, and a quality indicator. A field example of the processing, and its comparison with production data is also discussed. Introduction Drilling mud is usually weighted to maintain the wellbore hydrostatic pressure above that of the formation. This prevents the well from blowing out, but leads to invasion of borehole fluids into the formation, during which a mudcake is deposited on the borehole surface. The invasion process may consist of beneath-the-bit loss, dynamic filtration during mud circulation and finally static mud loss.1 While filtration beneath the bit may be important at the time of drilling, at the time of wireline logging most of the invasion is due to radial loss from the borehole wall. Except in tight formations, this loss is largely controlled by the mudcake, owing to its low permeability of about 1 nm2 [1 µD].2 One of the main objectives of logging is to determine the native formation resistivity in order to estimate oil reserves accurately. But the presence of an invaded region around the borehole distorts the electromagnetic logs and can make interpretation difficult. For understanding logs in the presence of invasion, a model based on a step resistivity change has been widely used, beginning with the work of Dumanoir et al.3 The step model consists of two zones of resistivity Rxo and Rt with the zone boundary at some distance ri Charts have been developed based on this model for various shoulder and mud resistivities to help the analyst deduce Rt For economic viability, in addition to knowing the reserves, it is important to know the recoverable amount. Here invasion has been regarded as representative of a waterflood. Thus, Rxo is a direct measure of the residual oil saturation Sor and tools to measure shallow resistivity have been built. Another unanticipated benefit of invasion has been discussed by Campbell and Martin 4 where a resistivity annulus is used as a pay zone indicator. The depth of invasion has also been believed to be related to permeability, although given the ultralow mudcake permeability, the correlation is probably weak. The motivation for the present work is provided by Ramakrishnan and Wilkinson,5 who developed the notion of interpreting conductivity profiles around the borehole by using fluid-flow physics. Based on these profiles, a rigorous and useful inversion result was proved. It was shown that with an ideal logging tool that could measure radial conductivity variation, the fractional flow curve could be exactly inverted provided the assumptions of the invasion model are met. This was true with just a single snapshot of the profile. The filtrate loss volume at every depth is also determined. A resistivity contrast between the mud filtrate and the connate water is required. Thus, for the first time in the history of logging, the possibility of obtaining multiphase flow properties was demonstrated. Although there is no ideal logging tool that measures conductivity profiles, tools that have multiple depths of investigation are becoming available. With the array induction imaging (AIT**) 28 raw measurements (not all independent), or more appropriately, five resolution matched channels are available. These may be combined with a shallow log and one which measures resistivity such as a log while drilling, e.g., MicroSFL** and compensated dual resistivity (CDR**). Then seven channels are obtained. The main purpose of this paper is to utilize such measurements that have different depths of investigation and demonstrate the practical utility of the inversion theorem 5,6 for obtaining fractional flow. From this, one is also able to obtain the initial water cut upon production, at any depth of interest. Rather than simply obtaining a resistivity profile based on one or two steps,7 the present work computes profiles that are constrained by the laws of fluid transport. Since the inverted flow parameters have restricted physical ranges, quality checks may be imposed. All of the familiar logs, such as Rt and Rxo can also be computed with little extra effort. Here we note that the work of Semmelbeck et al.8 done in parallel with ours, is an attempt to estimate single phase permeability (for low permeability gas sands) from array logs, quite different from the aim of this paper. Finally, it is important to point out that the principles behind the work presented here are applicable to any set of array logs that have multiple depths of investigation and are not restricted to the logging tools discussed in this paper.
17
Schmitt, Denis P., and Michel Bouchon. "Full‐wave acoustic logging: synthetic microseismograms and frequency‐wavenumber analysis." GEOPHYSICS 50, no. 11 (November 1985): 1756–78. http://dx.doi.org/10.1190/1.1441865.
Full textAbstract:
The discrete wavenumber method is used to compute synthetic full‐waveform acoustic logs in axisymmetric multilayered boreholes and to perform the frequency‐wavenumber analysis of the radiated wave field. The stress‐displacement vector is propagated through the layers using a numerically improved formulation of the Thomson‐Haskell method. In the time domain, all the trapped and interface modes overlap. On the contrary, the representations of the spectral energy density of the scattered wave field in the frequency axial‐wavenumber domain, for various radial positions of observation, allow the recognition and identification of the different wave types as well as their repartition of energy. In particular, these diagrams show the close relation between the resonance frequencies of the borehole and the significant low‐frequency energy of the pseudo‐Rayleigh modes. They also facilitate the interpretation of some of the physical phenomena which occur during the propagation in a complex borehole environment. We present the configurations of a well‐bonded and unbonded cased hole, an invaded zone, and a mudcake. For all of these models, we consider a “fast” formation in which the S-wave velocity is higher than the bore fluid velocity and a “slow” formation. The presence of an elastic tool at the center of the borehole is also investigated. The associated microseismograms, computed for a series of source‐receiver spacings, characterize in the time domain the observations previously made.
18
Jacob, Robin H., David T. Beatty, and Robyn D. Warner. "A preliminary study into the use of ‘heat pipes’ to prevent high rigor temperature in beef carcasses by increasing cooling rate." Animal Production Science 54, no. 4 (2014): 504. http://dx.doi.org/10.1071/an13001.
Full textAbstract:
Three experiments were conducted to investigate the use of a custom-made heat pipe to reduce muscle temperature in beef carcasses during the initial part of the refrigeration period post slaughter. The effects of muscle depth (Experiment 1) and radial distance from a heat pipe (Experiment 2) were investigated initially. Then the use of multiple heat pipes was compared with no heat pipes for the loin and hind leg regions of a carcass (Experiment 3). All three experiments were conducted at a commercial beef abattoir in Western Australia. Without heat pipes, the time taken for the temperature to fall to 35°C in the hind leg was 10, 90 and 300 min for depths of 25, 50 and 100 mm from the surface, respectively. Temperature increased with radial distance from a heat pipe and the relative differences in temperature between different positions increased with time. Temperatures 110 min after the commencement of cooling were 35.7, 36.8 and 38.3°C for 20, 40 and 80 mm from the heat pipe, compared with 39.8°C without the pipe. The loin cooled faster than the rump, which cooled faster than the leg. Heat pipes increased the rate of temperature loss in the leg but not the loin. The time taken for the leg temperature to reach 35°C, measured at a depth of 100 mm, reduced from 150 to 76 min. These experiments confirm that heat pipes containing methanol could be used to increase the rate of heat loss from leg muscles in beef carcasses. Further work is required to determine if the magnitude of these increases in cooling rate would improve eating quality for large carcasses.
19
Chen, Xiaofei, Youli Quan, and Jerry M. Harris. "Seismogram synthesis for radially layered media using the generalized reflection/transmission coefficients method: Theory and applications to acoustic logging." GEOPHYSICS 61, no. 4 (July 1996): 1150–59. http://dx.doi.org/10.1190/1.1444035.
Full textAbstract:
A new method based on generalized reflection and transmission coefficients is proposed to calculate the synthetic seismograms in radially multilayered media. This method can be used to efficiently simulate full waveform acoustic logs and crosswell seismic profiles in situations where we need to consider borehole effects. The new formulation is tested by comparing our numerical results with previous available work and shows excellent agreement. Because of the use of the normalized Hankel functions and the normalization factors, this new algorithm for computing seismograms is stable numerically even for high‐frequency problems. To show the applicability of this new approach to full waveform sonic logging, we apply it to investigate the effects of complex invaded zones on the geometrical spreading and attenuation estimation for P‐waves. We find that a damaged zone (its velocity is slower than the unperturbed formation velocity) exhibits a convergence effect on the P‐waves, and a flushed zone (velocity is faster than the unperturbed formation velocity) exhibits a divergence effect on the P‐waves.
20
de Groot—Hedlin, Catherine D. "Smooth inversion of induction logs for conductivity models with mud filtrate invasion." GEOPHYSICS 65, no. 5 (September 2000): 1468–75. http://dx.doi.org/10.1190/1.1444835.
Full textAbstract:
A robust, efficient method of inversion of induction logging data for smooth 2-D models, appropriate to an environment in which mud filtrate invades flat‐lying layers, is described. An infinite number of solutions exist to the problem of determining a conductivity structure from a finite number of imprecise induction data. Therefore, the inverse problem is regularized such that the smoothest model is sought subject to the condition that the resulting computed log agrees with the field log to a given preset level. At each iteration, the Jacobian sensitivities are approximated using the distorted Born approximation. In most cases, the algorithm converges in 3 to 4 iterations. The resulting maximally smooth models reflect the resolution power of the induction data and are unlikely to result in overinterpretation of the data. Inversion of both synthetic and field data indicates that layer boundaries are well resolved but radial boundaries are poorly resolved by conventional induction logging data.
21
Leggate, William, Adam Redman, Jeff Wood, Henri Bailleres, and David J. Lee. "Radial permeability of the hybrid pine (Pinus elliottii × Pinus caribaea) in Australia." BioResources 14, no. 2 (April 17, 2019): 4358–72. http://dx.doi.org/10.15376/biores.14.2.4358-4372.
Full textAbstract:
The radial permeability (gas and liquid) of the hybrid pine (Pinus elliottii var. elliottii [PEE] × Pinus caribaea var. hondurensis [PCH]) was investigated for wood samples collected from 30 trees that were 19 years of age and represented various genotypes and stocking rates. The PEE × PCH hybrid is now a very important resource for the Australian forestry industry, producing logs used to manufacture a diverse array of wood products. The permeability of wood influences many important wood properties and industrial processes. For all data combined from all radial sampling positions, there was no significant effect of genotype and stocking rate on radial permeability. Both gas and liquid permeability increased from pith to bark positions within the tree. Conversely, resin content decreased from pith to bark positions. Gas and liquid permeability were significantly positively correlated, and a highly significant negative relationship was also found between permeability (gas and liquid) and resin content.
22
Bruce, A. G., P. M. Wong, Y. Zhang, H. A. Salisch, C. C. Fung, and T. D. Gedeon. "A STATE-OF-THE-ART REVIEW OF NEURAL NETWORKS FOR PERMEABILITY PREDICTION." APPEA Journal 40, no. 1 (2000): 341. http://dx.doi.org/10.1071/aj99019.
Full textAbstract:
This paper reviews the state-of-the-art of neural networks for permeability prediction from well logs. Good prediction of permeability is necessary for reservoir characterisation and is important for improving the reliability of the asset value of oil and gas companies. Two particular models, known as backpropagation and radial basis function networks, have been applied. From previous work, six innovative aspects are identified:choice of inputs;outlier detection and removal;data splitting;scaling;multiple networks; andprediction confidence.We have also provided a list of future research directions in the area, reflecting the current deficiencies of the use of neural networks. The topics are:the quality and quantity of core data;the maximum use of the logs;the compatibility of scales;the use of soft computing; andthe management of prediction confidence.The current applications are certainly the beginning of a new era. It is important for petrophysicists to take advantage of the advanced technologies.
23
Xu, Ping, Lloyd Donaldson, John Walker, Robert Evans, and Geoffrey Downes. "Effects of density and microfibril orientation on the vertical variation of low-stiffness wood in radiata pine butt logs." Holzforschung 58, no. 6 (October 1, 2004): 673–77. http://dx.doi.org/10.1515/hf.2004.122.
Full textAbstract:
Abstract The roles of density and microfibril angle in causing low stiffness in radiata pine butt logs were studied in detail on a 17-year-old tree. Distributions of these variables were compared with stiffness variations in the vertical direction. Results supported the hypothesis that cell ultrastructure is responsible for the vertical variation in stiffness. The microfibril orientation in tangential wall is considered to be an important factor contributing to wood stiffness because of the smaller microfibril angles compared with radial microfibril angles, and also because of the larger decrease of the microfibril angles with the rapid increase of wood stiffness in vertical direction especially in corewood zone. The microfibrils in the S3 layer fall from over 80° to angles of 54° and 51° for radial and tangential cell walls at the top of the butt log. Further study is needed for fully understanding the characteristics of S3 layers.
24
Arizabalo, Rubén Darío, Klavdia Oleschko, Gabor Korvin, Manuel Lozada, Ricardo Castrejón, and Gerardo Ronquillo. "Lacunarity of geophysical well logs in the Cantarell oil field, Gulf of Mexico." Geofísica Internacional 45, no. 2 (April 1, 2006): 99–113. http://dx.doi.org/10.22201/igeof.00167169p.2006.45.2.185.
Full textAbstract:
En este trabajo fueron analizadas las variaciones fractales y de lagunaridad de los registros geofísicos de pozo, con el fin de asociarlos con las propiedades estratigráficas y petrofísicas del yacimiento naturalmente fracturado de Cantarell, en el Golfo de México. Los registros considerados fueron: porosidad neutrón (NPHI), densidad (RHOB, DRHO, PEF), resistividad (LLD, LLS, MSFL), radiactividad natural (GR, CGR, URAN, POTA, THOR) y caliper (CALI). Los registros de resistividad produjeron valores de lagunaridad notablemente altos, especialmente en las rocas generadoras y almacenadoras, a diferencia de los demás registros, cuya homogeneidad de traza implicó una baja lagunaridad. Los resultados indican que la lagunaridad observada depende de la resolución y profundidad radial de penetración del método geofísico estudiado y aumenta sistemáticamente en el siguiente orden: (RHOB) < (CALI) < (PEF) < (URAN) < (GR) < (NPHI) < (POTA) < (CGR) < (THOR) < (MSFL) < (DRHO) < (LLS) < (LLD).
25
Ali, Mahmoud T., and Hisham A. Nasr-El-Din. "New Insights into Carbonate Matrix Acidizing Treatments: A Mathematical and Experimental Study." SPE Journal 25, no. 03 (March 5, 2020): 1272–84. http://dx.doi.org/10.2118/200472-pa.
Full textAbstract:
Summary The design process of carbonate matrix acidizing treatments requires coring and conducting linear, radial coreflood experiments. With the current environment revolving around cutting costs, it has become increasingly important to accurately design cost-effective acidizing treatments. This work aims to introduce a novel approach to predicting the performance of acid treatments in the field using log data only. A radial reactive flow simulator, using porosity distributed from logs, is used to provide accurate predictions without the need for experiments. Coreflood acidizing experiments at 150 and 200°F with two acid concentrations were studied. A reactive flow simulator was built using porosity distribution derived from computed-tomography (CT) scans and tuned to match experimental data. A new radial simulation model of 3.25-ft radius was used to study acid propagation under field conditions. For accurate predictions, porosity was distributed using values derived from cores’ CT scans. Simulation results were compared with traditional 1D models. Different porosity distributions, including gamma distributions, were used in the radial model. The reactive flow simulator was able to accurately capture wormhole propagation inside the linear core. A greater than 90% match between the experimental and the simulated acid pore volume (PV) to breakthrough (PVBT) was obtained using two acid concentrations’ different temperatures. The simulation results from the radial field-scale model show that the optimal velocity can be higher or lower than those predicted from laboratory experiments. Accordingly, caution must be taken when linear coreflood data are used to predict acid propagation in the field. The simulations showed that traditional upscaling models overpredict acid volumes; the predicted volumes are double at moderate to high injection rates. Models using statistically distributed porosity can provide accurate acid-propagation predictions, with a relative percentage error of less than 25% at extremely high injection rates. This work introduces an accurate model using porosity directly from logs to predict acid performance while avoiding expensive designs. The simulation results reveal that traditional designs overpredict acid volumes required for field treatments. The statistically distributed porosity can be used as a substitute for CT-scan-derived porosity with a low effect on model predictability. The reactive flow simulator can accurately match experimental data.
26
Maalouf, Elsa, and Carlos Torres-Verdín. "Interpretation of borehole flexural measurements in high-angle wells using 3D spatial sensitivity functions." GEOPHYSICS 83, no. 6 (November 1, 2018): D217—D229. http://dx.doi.org/10.1190/geo2017-0808.1.
Full textAbstract:
Undulating wells are routinely drilled to improve reservoir exposure across hydrocarbon-bearing zones. Although conventional acoustic-log interpretation methods are reliable in vertical wells, they often yield inaccurate results when applied to high-angle or horizontal wells due to azimuthal asymmetry, spatial averaging effects, and wave-mode interference. Three-dimensional finite-difference and finite-element algorithms are typically used to quantify the aforementioned effects on acoustic logs, but they are extremely demanding on the central processing unit’s (CPU) time and memory. We develop a fast algorithm to simulate flexural slownesses acquired in high-angle wells using 3D linear spatial sensitivity functions. Spatial sensitivity functions quantify the variation of phase slowness measured by the sonic tool due to spatial perturbations of elastic properties. First, we construct 3D frequency-dependent sensitivity functions of flexural modes using the product of 1D axial, radial, and azimuthal sensitivity functions obtained from first-order approximations. Then, we simulate frequency-domain flexural logs acquired with wireline tools and dipole sources in isotropic and vertical transversely isotropic (VTI) formations penetrated by high-angle wells. For the examined examples, simulated flexural logs exhibit root-mean-square errors less than [Formula: see text] when compared with those calculated with a 3D time-domain finite-difference (3D-TDFD) algorithm. We found that in isotropic formations with layers thinner than the length of the receiver array, flexural slownesses acquired separately with cross dipoles are different because of geometric asymmetry, whereas in VTI formations we observed differences between cross-dipole slownesses because of effective anisotropy. Furthermore, the flexural logs are affected by spatial averaging introduced by the acoustic wireline tool, especially in the vicinity of layer boundaries. Three-dimensional sensitivity functions reduce the computation time of the flexural logs from an average of 15 h of CPU time per depth (using 3D-TDFD methods) to less than 3 min. The fast simulation algorithm disregards wave reflections, wave-mode conversion, and wave-mode interference occurring at layer boundaries.
27
Jaime Osorio, María Fernanda, Mabel Catalina Caicedo Muñoz, and Iván Camilo Trujillo Bohórquez. "A Radio Program: a Strategy to Develop Students’ Speaking and Citizenship Skills." HOW 26, no. 1 (February 28, 2019): 8–33. http://dx.doi.org/10.19183/how.26.1.510470.
Full text
28
Mendoza, Alberto, Carlos Torres-Verdín, and Bill Preeg. "Linear iterative refinement method for the rapid simulation of borehole nuclear measurements: Part I — Vertical wells." GEOPHYSICS 75, no. 1 (January 2010): E9—E29. http://dx.doi.org/10.1190/1.3267877.
Full textAbstract:
As a result of its high numerical accuracy and versatility to include complex tool configurations and arbitrary spatial distributions of material properties, the Monte Carlo method is the foremost numerical technique used to simulate borehole nuclear measurements. Although recent advances in computer technology have considerably reduced the computer time required by Monte Carlo simulations of borehole nuclear measurements, the efficiency of the method is still not sufficient for estimation of layer-by-layer properties or combined quantitative interpretation with other borehole measurements. We develop and successfully test a new linear iterative refinement method to simulate nuclear borehole measurements accurately and rapidly. The approximation stems from Monte Carlo-derived geometric response factors, referred to as flux sensitivity functions (FSFs), for specific density and neutron-tool configurations. Our procedure first invokes the integral representation of Boltzmann’s transport equation to describe the detector response from the flux of particles emitted by the radioactive source. Subsequently, we use theMonte Carlo N-particle (MCNP) code to calculate the associated detector response function and the particle flux included in the integral form of Boltzmann’s equation. The linear iterative refinement method accounts for variations of the response functions attributable to local perturbations when numerically simulating neutron and density porosity logs. We quantify variations in the FSFs of neutron and density measurements from borehole environmental effects and spatial variations of formation properties. Simulations performed with the new approximations yield errors in the simulated value of density of less than [Formula: see text] with respect to Monte Carlo-simulated logs. Moreover, for the case of radial geometric factor of density, we observe a maximum shift of [Formula: see text] at 90% of the total sensitivity as a result of realistic variations of formation density. For radial variation of neutron properties (migration length), the maximum change in the radial length of investigation is [Formula: see text]. Neutron porosity values simulated with the new approximation differ by less than 10% from Monte Carlo simulations. The approximations enable the simulation of borehole nuclear measurements in seconds of CPU time compared to several hours with MCNP.
29
Bouchon, Michel. "A numerical simulation of the acoustic and elastic wavefields radiated by a source on a fluid‐filled borehole embedded in a layered medium." GEOPHYSICS 58, no. 4 (April 1993): 475. http://dx.doi.org/10.1190/1.1443430.
Full textAbstract:
We present a method of calculation to simulate the propagation of acoustic and elastic waves generated by a borehole source embedded in a layered medium. The method is formulated as a boundary element technique where the Green’s functions are calculated by the discrete wavenumber method. The restrictive assumptions are that the borehole is cylindrical and that its axis runs normal to the layer interfaces. The physics of the method rely on Huygens’s principle that states that a diffracting boundary—the borehole wall in the present case—can be represented as a distribution of secondary sources. The borehole is discretized into small cylindrical elements and each element is represented by three sources: a volume source representing the wavefield diffracted in the fluid and two surface forces that give rise to the elastic wavefield radiated outside the borehole. The strength of each source is obtained by solving the linear system of equations that describes the boundary conditions at the borehole wall. The method is used to generate synthetic acoustic logs and to investigate the wavefield radiated into the formation. The simulations considered display the Stoneley wave reflections at the bed boundaries and show the importance of the diffraction that takes place where the borehole wall intersects the layer interfaces.
30
Gimenez, Ana María. "Gradiente radial de los elementos anatómicos del leño en Schinopsis quebracho-colorado (Schlecht.) Barkl. et Meyer, Anacardiaceae." Bosque 21, no. 2 (2000): 37–45. http://dx.doi.org/10.4206/bosque.2000.v21n2-04.
Full text
31
He, Jiahuan, Min Li, Keming Zhou, Li Zeng, Nong Li, Yu Yang, Dan Xiao, and Mei Huang. "Radial resistivity measurement method for cylindrical core samples." Interpretation 8, no. 4 (November 1, 2020): T1071—T1080. http://dx.doi.org/10.1190/int-2019-0213.1.
Full textAbstract:
Electrical resistivity is one of the fundamental physical properties of rocks, and its relationship with fluid saturation is widely used in reservoir evaluation. The interpretation of electrical logs usually relies on the results of rock resistivity tests of cores in the laboratory. In the laboratory, core samples are commonly cut into cylinders, and the resistivity is measured along the axial direction. To determine the rock resistivity along different directions, samples are cut into cubes and tested along three perpendicular directions to obtain resistivity data. The expensive and complicated preparation process of cubic samples and the custom holder requirements limit the use of these tests. We have analyzed the advantages and disadvantages of rock resistivity measurements of cylindrical and cubic samples. To overcome the abovementioned difficulties, we develop a core holder for radial resistivity measurements and a radial resistivity measurement method for cylindrical samples. Based on the conformal transformation of the complex variable function theory, we establish a mathematical model of radial resistivity. We develop a measurement method of radial resistivity according to the mathematical model and verify this approach with isotropic cores. The theoretical calculation results agree with the experimental results. With the radial resistivity measurement method, we effectively test the resistivity anisotropy of shale. This method has more advantages than existing methods in terms of the sample preparation and realization of various displacement levels and angles. Hence, the proposed method can be widely used.
32
Donaldson, Lloyd A. "ABNORMAL LIGNIN DISTRIBUTION IN WOOD FROM SEVERELY DROUGHT STRESSED PINUS RADIATA TREES." IAWA Journal 23, no. 2 (2002): 161–78. http://dx.doi.org/10.1163/22941932-90000295.
Full textAbstract:
Radiata pine logs exhibiting concentric shelling were examined for abnormal wood anatomy and cell wall characteristics. The trees from which the logs originated were growing on coastal sand dunes with a shallow impermeable iron pan subsoil, and the abnormal wood properties are assumed to be the result of frequent water stress and possible associated nutritional stress. The wood showed numerous false growth rings alternating with bands of poorly lignified tracheids. Examination of lignin distribution by confocal fluorescence microscopy and transmission electron microscopy revealed abnormal cell wall development associated with a poorly lignified middle lamella and outer secondary cell wall. Affected tracheids showed poor adhesion with development of intercellular checking, particularly on radial cell walls. Some tracheids showed concentric lamellation associated with areas of high and low lignification within the secondary wall. In many cases, the S3 layer was thicker and more heavily lignified than normal. Tracheids with the greatest reduction in lignification of the secondary wall showed evidence of collapse. The shelling behaviour of the wood was thus explained by poor or negligible adhesion between tracheids due to reduced lignification of middle lamellae. This investigation provides some insight into the effect of growth environment on lignification.
33
Newton, Peter. "Acoustic Velocity—Wood Fiber Attribute Relationships for Jack Pine Logs and Their Potential Utility." Forests 9, no. 12 (November 30, 2018): 749. http://dx.doi.org/10.3390/f9120749.
Full textAbstract:
This study presents an acoustic-based predictive modeling framework for estimating a suite of wood fiber attributes within jack pine (Pinus banksiana Lamb.) logs for informing in-forest log-segregation decision-making. Specifically, the relationships between acoustic velocity (longitudinal stress wave velocity; vl) and the dynamic modulus of elasticity (me), wood density (wd), microfibril angle (ma), tracheid wall thickness (wt), tracheid radial and tangential diameters (dr and dt, respectively), fiber coarseness (co), and specific surface area (sa), were parameterized deploying hierarchical mixed-effects model specifications and subsequently evaluated on their resultant goodness-of-fit, lack-of-fit, and predictive precision. Procedurally, the data acquisition phase involved: (1) randomly selecting 61 semi-mature sample trees within ten variable-sized plots established in unthinned and thinned compartments of four natural-origin stands situated in the central portion the Canadian Boreal Forest Region; (2) felling and sectioning each sample tree into four equal-length logs and obtaining twice-replicate vl measurements at the bottom and top cross-sectional faces of each log (n = 4) from which a log-specific mean vl value was calculated; and (3) sectioning each log at its midpoint and obtaining a cross-sectional sample disk from which a 2 × 2 cm bark-to-pith radial xylem sample was extracted and subsequently processed via SilviScan-3 to derive annual-ring-specific attribute values. The analytical phase involved: (1) stratifying the resultant attribute—acoustic velocity observational pairs for the 243 sample logs into approximately equal-sized calibration and validation data subsets; (2) parameterizing the attribute—acoustic relationships employing mixed-effects hierarchical linear regression specifications using the calibration data subset; and (3) evaluating the resultant models using the validation data subset via the deployment of suite of statistical-based metrics pertinent to the evaluation of the underlying assumptions and predictive performance. The results indicated that apart from tracheid diameters (dr and dt), the regression models were significant (p ≤ 0.05) and unbiased predictors which adhered to the underlying parameterization assumptions. However, the relationships varied widely in terms of explanatory power (index-of-fit ranking: wt (0.53) > me > sa > co > wd >> ma (0.08)) and predictive ability (sa > wt > wd > co >> me >>> ma). Likewise, based on simulations where an acoustic-based wd estimate is used as a surrogate measure for a Silviscan-equivalent value for a newly sampled log, predictive ability also varied by attribute: 95% of all future predictions for sa, wt, co, me, and ma would be within ±12%, ±14%, ±15%, ±27%, and ±55% and of the true values, respectively. Both the limitations and potential utility of these predictive relationships for use in log-segregation decision-making, are discussed. Future research initiatives, consisting of identifying and controlling extraneous sources of variation on acoustic velocity and establishing attribute-specific end-product-based design specifications, would be conducive to advancing the acoustic approach in boreal forest management.
34
van de Gevel, Saskia L., Justin L. Hart, Mark D. Spond, Philip B. White, Megan N. Sutton, and Henri D. Grissino-Mayer. "American chestnut (Castanea dentata) to northern red oak (Quercus rubra): forest dynamics of an old-growth forest in the Blue Ridge Mountains, USA." Botany 90, no. 12 (December 2012): 1263–76. http://dx.doi.org/10.1139/b2012-100.
Full textAbstract:
We analyzed tree species composition and age structure in a rare, old-growth Quercus rubra L. (northern red oak) forest at Bluff Mountain Preserve, North Carolina, to assess potential changes associated with Cryphonectria parasitica (Murrill) M.E. Barr (chestnut blight), selective logging, livestock grazing, ice storms, wind events, and fire history. We established forest inventory plots to determine the forest composition, vertical structure, and age of the high-elevation Q. rubra dominated forest. We developed the longest Q. rubra dendroecological history (1671–2009) in North America. Several living Q. rubra individuals were more than 250 years old. The frequency, magnitude, and spatial extent of canopy disturbance events were shown in radial growth trends in Q. rubra samples. We also examined Q. rubra climate – radial growth relationships to compare high-elevation Q. rubra climate response patterns with results from lower elevation Quercus dendroclimatological studies. Stand-wide release events corresponded with the loss of Castanea dentata (Marsh.) Borkh. (American chestnut) during the 1930s and frequent ice storms or wind events. Although we observed fire scars on living hardwood trees, we did not find fire scars on the remnant logs. The lack of fire scars on the remnant logs indicates that the observed fires likely occurred during the second half of the 20th century. Quercus rubra were most climatically sensitive to cool March temperatures. Quercus rubra sampled at higher elevations were more sensitive to temperature than lower elevation Quercus spp. trees, which may indicate higher sensitivity to March frosts. Quercus rubra has been a dominant species at Bluff Mountain for the past 300 years; however, our data indicate that the forest will transition to support a much stronger Acer saccharum Marsh. (sugar maple) component during the next 50 years. This study provides a multicentury perspective to guide conservation efforts and forest management in high-elevation Quercus spp. forests in the southern Appalachian Mountains.
35
Bayestorff da Cunha, Alexsandro, Morgana Cristina França, Caio Cesar Faedo de Almeida, Luciane Gorski, Rodrigo Coelho da Cruz, and Dalton Dos Santos. "AVALIAÇÃO DO RENDIMENTO EM MADEIRA SERRADA DE Eucalyptus benthamii E DE Eucalyptus grandis POR MEIO DO DESDOBRO TANGENCIAL E RADIAL." FLORESTA 45, no. 2 (August 19, 2014): 241. http://dx.doi.org/10.5380/rf.v45i2.32570.
Full textAbstract:
O objetivo foi determinar o aproveitamento do Eucalyptus benthamii e do Eucalyptus grandis no processo de desdobro. A metodologia envolveu duas classes diamétricas (20-25 cm e 25,01-30 cm) e dois sistemas de desdobro (tangencial e radial). O rendimento do desdobro foi obtido pela relação entre o volume de toras e o de madeira serrada, sendo separado em bruto, sem rachaduras, sem destopo e líquido. Na análise do rendimento, adotou-se a Análise da Variância e o Teste de Tukey. Os resultados encontrados demonstraram que o sistema de desdobro tangencial apresentou melhor aproveitamento da matéria-prima. Os tratamentos compostos pelo E. benthamii e sistema tangencial foram os que apresentaram maior redução no rendimento em função da retirada das partes rachadas das peças, enquanto que, para a perda devida ao destopo, as porcentagens encontradas foram equivalentes para ambas as espécies. No rendimento final do processo, houve uma redução do rendimento em madeira serrada, com o aumento do diâmetro das toras para as duas espécies.Palavras-chave: Eucalipto; rachaduras de topo; aproveitamento da matéria-prima; serraria. AbstractEvaluation of the yield in sawnwood of Eucalyptus benthamii Maiden et Cambage and Eucalyptus grandis Hill ex Maiden by tangential and radial sawing. The aim was to determine the yield of Eucalyptus benthamii and Eucalyptus grandis in the process of the sawing. The methodology involved two diameter classes (20-25 cm and 25.1-30 cm) and two systems sawing (tangential and radial). The yield of sawing was obtained through the relationship between the volume of logs and lumber, being separated into gross yield, no splits, no trimming and liquid. The analysis yield was adopted the Analysis of Variance and Tukey test. The results demonstrated that the system of tangential sawing showed better utilization of raw-material. The treatments consisted of the E. benthamii and tangential system presented the greatest yield reduction due to the removal of parts of the split pieces, while for the loss due to destopo, the percentages found were similar for both species. In the final yield of the process, there was no reduction of yield in lumber with the increase of the diameter of the logs for both species.Keywords: Eucalypt; log end splits; utilization of raw material; sawmill.
36
Tan, Maojin, Qiong Liu, and Songyang Zhang. "A dynamic adaptive radial basis function approach for total organic carbon content prediction in organic shale." GEOPHYSICS 78, no. 6 (November 1, 2013): D445—D459. http://dx.doi.org/10.1190/geo2013-0154.1.
Full textAbstract:
Total organic carbon (TOC) is an important parameter for characterizing shale gas and oil reservoirs. Estimation of TOC from well logs has previously been achieved by an empirical model. The radial basis function (RBF) neural network is a new quantitative method that can generate a smooth and continuous function of several input variables to approximate the unknown forward model. We investigated the basic principles of the RBF including network structure, basis function, network training method, and its application in the TOC prediction. The nearest neighbor algorithm was selected for the network training. Then, the Gaussian width was investigated to improve the TOC prediction accuracy through leave-one-out cross-validation. Finally, field cases of organic shale were studied for the TOC prediction, and the prediction results using the RBF method were compared with those of the [Formula: see text] method. Furthermore, according to sensitive attribute ranking, the impacts of different input logs on the predicted results were also investigated through various experiments, and the best network model was finally chosen. The error analysis between the prediction results and lab-measured TOC in some examples indicated that the new approach is more accurate than a single empirical regression method and more flexible than the [Formula: see text] method.
37
Reyes-Cortés, Luz M., J. Jesús Vargas-Hernández, Arnulfo Aldrete, Armando Gómez-Guerrero, and J. Amador Honorato-Salazar. "Radial growth in Pinus patula Schltdl. & Cham. and its relationship with growing space and climatic factors." Revista Chapingo Serie Ciencias Forestales y del Ambiente 26, no. 2 (April 30, 2020): 157–72. http://dx.doi.org/10.5154/r.rchscfa.2019.04.036.
Full text
38
Gibson, Richard L. "Radiation from seismic sources in cased and cemented boreholes." GEOPHYSICS 59, no. 4 (April 1994): 518–33. http://dx.doi.org/10.1190/1.1443613.
Full textAbstract:
Far‐field, stationary phase approximations are often used to study the radiation of P‐ and S‐waves from seismic sources located in boreholes, usually with an assumption of low frequency and in application to uncased boreholes. These two assumptions allow explicit analytical results for the radiation patterns to be derived, as boundary condition equations can be solved analytically in fairly simple forms. Applying the same methodology to cased and cemented boreholes, however, is much more difficult because of the increased number of simultaneous boundary condition equations. I circumvent this difficulty by solving the boundary condition equations numerically using propagator matrices, as is generally done in the calculation of synthetic full‐waveform acoustic logs. In this way, the assumption of low frequency is also avoided, and a generalized stationary‐phase solution for sources in general, concentrically layered borehole models is easily obtained. Computation of the radiation patterns for cased and uncased boreholes in various formations shows that the amplitude reduction, because of the introduction of casing, is a function of both source type and of formation velocities. Axial stress sources are less affected by the casing than either radial stress or volume‐injection sources, and as formation velocity decreases, the effect of the casing becomes more significant as the impedance contrast between steel and the formation becomes larger. The new generalized stationary‐phase solution also shows that as frequency approaches 1000 Hz, the results obtained by low‐frequency approximations for stress sources can be inaccurate and that the energy radiated from the source becomes more highly directed in the horizontal directions. The radiation pattern begins to change relatively rapidly as a function of frequency, so that the resulting observations from broad‐band sources will show changes in waveforms that mimic the effects of attenuation. These changes occur because the length of the source becomes important as wavelength decreases, demonstrating the need to consider the influence of frequency, as well as casing and cement, on source radiation.
39
Nakada, R., Y. Fujisawa, and Y. Hirakawa. "Effects of Clonal Selection by Microfibril Angle on the Genetic Improvement of Stiffness in Cryptomeria japonica D. Don." Holzforschung 57, no. 5 (August 20, 2003): 553–60. http://dx.doi.org/10.1515/hf.2003.082.
Full textAbstract:
Summary The microfibril angle (MFA) of latewood tracheids and its radial variation at breast height in Cryptomeria japonica D. Don (sugi) were investigated with twelve clones collected from three sites in the Kyushu region, Japan. Large variations both between clones and between sites were observed. The MFAs were well correlated to the stiffness of the logs collected from the sample trees. A simulation of clonal selection according to the ranking of the clones in MFA demonstrated that the log stiffness of the selected population was much improved even when the selection relied on MFAs in the second ring from the pith. The improvement in log stiffness by MFA selection was not different from the selection by log stiffness itself. The results indicate that early selection by MFA is very effective in improving log stiffness in this species.
40
Bautista-Anguiano, Joshua, and Carlos Torres-Verdín. "Estimation of in situ hydrocarbon saturation of porous rocks from borehole measurements of spontaneous potential." GEOPHYSICS 85, no. 6 (November 1, 2020): D199—D217. http://dx.doi.org/10.1190/geo2019-0842.1.
Full textAbstract:
It has been previously shown that Nernst’s equation is not reliable for the interpretation of spontaneous potential (SP) measurements acquired in hydrocarbon-bearing rocks. We have examined whether the difference between borehole SP measurements and Nernst-equation predictions could be used to estimate in situ hydrocarbon saturation of porous rocks. For this purpose, a new petrophysical model and a mechanistic finite-difference algorithm for simulating SP borehole measurements in the presence of mud-filtrate invasion are used to establish the limits of detectability of hydrocarbon saturation using only SP logs. We find that the optimal conditions for the detection of hydrocarbon saturation from SP borehole measurements are when (1) capillary forces dominate the process of mud-filtrate invasion, (2) the matrix-pore interface region, known as the electrical double layer, has a relevant impact in the diffusion of counterions, and (3) the electrolyte concentration of drilling mud is greater than that of formation water. We also determine why high values of the endpoint of the water relative permeability favor the detection of hydrocarbon-saturated rocks with the SP log. Using measurements acquired in three key wells within a mature and active hydrocarbon field, three blind tests find that our petrophysical model together with the mechanistic SP simulation algorithm enable the estimation of hydrocarbon saturation from SP borehole measurements without the need for resistivity logs or porosity calculations. The estimation is reliable when the volumetric concentration of shale is negligible, the pore network structure is constant throughout the reservoir, and radial invasion profiles are similar to those observed in the calibration key wells.
41
Mendoza, Alberto, Carlos Torres-Verdín, and Bill Preeg. "Linear iterative refinement method for the rapid simulation of borehole nuclear measurements: Part 2 — High-angle and horizontal wells." GEOPHYSICS 75, no. 2 (March 2010): E79—E90. http://dx.doi.org/10.1190/1.3335953.
Full textAbstract:
Based on previous research, we developed and successfully tested a new linear iterative refinement method to rapidly simulate borehole nuclear measurements acquired in vertical wells. The approximation considers 2D spatial properties of Monte Carlo-derived flux-sensitivity functions (FSFs) to simulate neutron and density measurements. Based on new research, we implemented the linear iterative refinement method with explicit 3D spatial properties of FSFs to approximate nuclear borehole measurements acquired in high-angle and horizontal (HA/HZ) wells. We used generic neutron and density tools that are close to commercial tool designs to construct 3D FSFs in the proximity of a bed boundary between layers of contrasting petrophysical properties. Likewise, to benchmark the approximation, we consider adjacent layers of 5% and 30% porosity water-saturated sandstone. For the case of neutron measurements, variations of azimuthal geometric factors are as large as 20° and 57° for the near and far detectors, respectively. Variations in the radial length of investigation (J-factors) are as large as [Formula: see text] for near and far detectors. In the case of density measurements, radial and azimuthal geometric factors are approximately invariant. Linear iterative refinement approximations yield errors in the simulated neutron porosity ranging from 1.6% to 4.3% with respect to Monte Carlo-simulated logs in wells deviating from 60° to 85° from the vertical.
42
Zahid, D. M., and A. Majeed. "Extent of dimensional changes during staggered seasoning in Pakistan-grown eucalyptus wood." Australian Journal of Experimental Agriculture 45, no. 1 (2005): 121. http://dx.doi.org/10.1071/ea03094.
Full textAbstract:
Eucalyptus is an exotic species that has been grown in Pakistan for over 2 decades. It is fast growing and an alternative to indigenous hardwood species, but growers are facing problems regarding maximum utilisation, predominantly due to seasoning defects. Attempts are being made to assess the extent of dimensional changes during seasoning so that appropriate procedures can be developed and applied to reduce defects occurring during this time. Specimens were taken from farm grown eucalyptus wood at the Postgraduate Agricultural Research Station. Seasoning was applied in 2 stages. Changes in wood dimension measured were shrinkage (longitudinal, radial, tangential and volumetric) and warping (bending and twisting). From this study it can be concluded that intermediate sized samples that were symmetrically sawn were more stable than smaller samples sawn unevenly. The data indicated that specimens neither too large nor too small could be favoured for seasoning. Two-step seasoning is preferred over 1-step seasoning, and sawing of wood with rectangular specimens (boards) cut with the wide face radial relative to the growth rings is ideal, even though boards with lesser width were recovered. This is because internal stresses are disposed off symmetrically and counter balance each other, which reduces defects. Seasoning efficiency of these logs was enhanced and the stresses were set due to wood plasticity. Further degradation was unlikely when wood was re-sawn after partial seasoning.
43
Larsen, Finn, and Sigurdur Ormarsson. "Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs." Holzforschung 68, no. 1 (January 1, 2014): 133–40. http://dx.doi.org/10.1515/hf-2012-0149.
Full textAbstract:
Abstract Timber is normally dried by kiln drying, in the course of which moisture-induced stresses and fractures can occur. Cracks occur primarily in the radial direction due to tangential tensile strength (TSt) that exceeds the strength of the material. The present article reports on experiments and numerical simulations by finite element modeling (FEM) concerning the TSt and fracture behavior of Norway spruce under various climatic conditions. Thin log disc specimens were studied to simplify the description of the moisture flow in the samples. The specimens designed for TS were acclimatized to a moisture content (MC) of 18% before TSt tests at 20°C, 60°C, and 90°C were carried out. The maximum stress results of the disc simulations by FEM were compared with the experimental strength results at the same temperature levels. There is a rather good agreement between the results of modeling and experiments. The results also illustrate the strong decrease of TSt with increasing temperature at a constant MC level.
44
Głowacki, Oskar, Grant B. Deane, Mateusz Moskalik, Jarosław Tęgowski, and Philippe Blondel. "Two-element acoustic array gives insight into ice-ocean interactions in Hornsund Fjord, Spitsbergen." Polish Polar Research 36, no. 4 (December 1, 2015): 355–67. http://dx.doi.org/10.1515/popore-2015-0025.
Full textAbstract:
AbstractGlacierized fjords are dynamic regions, with variable oceanographic conditions and complex ice-ocean interactions, which are still poorly understood. Recent studies have shown that passive underwater acoustics offers new promising tools in this branch of polar research. Here, we present results from two field campaigns, conducted in summer 2013 and spring 2014. Several recordings with a bespoke two-hydrophone acoustic buoy were made in different parts of Hornsund Fjord, Spitsbergen in the vicinity of tidewater glaciers to study the directionality of underwater ambient noise. Representative segments of the data are used to illustrate the analyses, and determine the directions of sound sources by using the time differences of arrivals between two horizontally aligned, broadband hydrophones. The results reveal that low frequency noise (< 3 kHz) is radiated mostly from the ice cliffs, while high-frequency (> 3 kHz) noise directionality strongly depends on the distribution of floating glacial ice throughout the fjord. Changing rates of iceberg production as seen for example in field photographs and logs are, in turn, most likely linked to signal amplitudes for relevant directions. These findings demonstrate the potential offered by passive acoustics to study the dynamics of individual tidewater glaciers.
45
Metzler, B., and U. Hecht. "Three-dimensional structure of tubular air channels formed by Armillaria spp. in water-saturated logs of silver fir and Norway spruce." Canadian Journal of Botany 82, no. 9 (September 1, 2004): 1338–45. http://dx.doi.org/10.1139/b04-092.
Full textAbstract:
Water saturation of wood impedes the availability of oxygen necessary for wood decay. Storage of logs under water sprinkling is therefore used as an economic method in forestry. However, sapwood decay caused by Armillaria spp. was found in logs under water sprinkling, even at a wood moisture content of more than 150% (dry weight basis). Decay was associated with the formation of tubular air channels discernible as bright streaks extending from the cambial region into the sapwood. Their light colour results from different refraction of light in gas-filled versus water-filled wood structures. To examine the structure of the tubular air spaces in greater detail, we sampled wood of Norway spruce (Picea abies (L.) Karst. and silver fir (Abies alba (Mill.)). Radial, transverse, as well as tangential sections of affected timber were examined, and a structural model of tubular air channels is presented. These structures are formed around wood rays by a tubular sheath of pseudoparenchymatous mycelium, which in its cellular structure is reminiscent of pseudosclerotial plates. This structure allows the efficiently located extrusion of water from water-saturated wood. The power necessary for this process is suggested to be the generation of gaseous CO2. Since the air channels are in contact with the external surface, they evidently act as a conduit allowing oxygen to enter and penetrate to a depth of several centimetres. By this unique arrangement of the tubular air channels, Armillaria spp. appear able to metabolize wood cells in an aerobic microenvironment within water-saturated wood. This results in wood decay leading to significant economic loss in stored timber despite the application of regular sprinkling.Key words: Armillaria spp., Picea abies, Abies alba, wood moisture content, oxygen supply, wood anatomy, wood decay.
46
Swidinsky, Andrei, and Chester J. Weiss. "On coincident loop transient electromagnetic induction logging." GEOPHYSICS 82, no. 4 (July 1, 2017): E211—E220. http://dx.doi.org/10.1190/geo2017-0134.1.
Full textAbstract:
Coincident loop transient induction wireline logging is examined as the borehole analog of the well-known land and airborne time-domain electromagnetic (EM) method. The concept of whole-space late-time apparent resistivity is modified from the half-space version commonly used in land and airborne geophysics and applied to the coincident loop voltages produced from various formation, borehole, and invasion models. Given typical tool diameters, off-time measurements with such an instrument must be made on the order of nanoseconds to microseconds — much more rapidly than for surface methods. Departure curves of the apparent resistivity for thin beds, calculated using an algorithm developed to model the transient response of a loop in a multilayered earth, indicate that the depth of investigation scales with the bed thickness. Modeled resistivity logs are comparable in accuracy and resolution with standard frequency-domain focused induction logs. However, if measurement times are longer than a few microseconds, the thicknesses of conductors can be overestimated, whereas resistors are underestimated. Thin-bed resolution characteristics are explained by visualizing snapshots of the EM fields in the formation, where a conductor traps the electric field while two current maxima are produced in the shoulder beds surrounding a resistor. Radial profiling is studied using a concentric cylinder earth model. Results found that true formation resistivity can be determined in the presence of either oil- or water-based mud, although in the latter case, measurements must be taken several orders of magnitude later in time. The ability to determine true formation resistivity is governed by the degree that the EM field heals after being distorted by borehole fluid and invasion, a process visualized and particularly evident in the case of conductive water-based mud.
47
Salazar, Jesús M., and Carlos Torres-Verdín. "Quantitative comparison of processes of oil- and water-based mud-filtrate invasion and corresponding effects on borehole resistivity measurements." GEOPHYSICS 74, no. 1 (January 2009): E57—E73. http://dx.doi.org/10.1190/1.3033214.
Full textAbstract:
Some laboratory and qualitative studies have documented the influence of water-based mud(WBM)-filtrate invasion on borehole resistivity measurements. Negligible work, however, has been devoted to studying the effects of oil-based mud(OBM)-filtrate invasion on well logs and the corresponding impact on the estimation of petrophysical properties. We quantitatively compare the effects of WBM- and OBM-filtrate invasion on borehole resistivity measurements. We simulate the process of mud-filtrate invasion into a porous and permeable rock formation assuming 1D radial distributions of fluid saturation and fluid properties while other petrophysical properties remain constant. To simulate the process of mud-filtrate invasion, we calculate a time-dependent flow rate of OBM-filtrate invasion by adapting the available formulation of the physics of WBM-filtrate invasion. This approach includes the dynamically coupled effects of mud-cake growth and multiphase filtrate invasion. Simulations are performed with a commercial adaptive-implicit compositional formulation that enables the quantification of effects caused by additional components of mud-filtrate and native fluids. The formation under analysis is 100% water saturated (base case) andis invaded with a single-component OBM. Subsequently, we perform simulations of WBM filtrate invading the same formation assuming that it is hydrocarbon bearing, and compare the results to those obtained in the presence of OBM. At the end of this process, we invoke Archie’s equation to calculate the radial distribution of electrical resistivity from the simulated radial distributions of water saturation and salt concentration and compare the effects of invasion on borehole resistivity measurements acquired in the presence of OBM and WBM. Simulations confirm that the flow rate of OBM-filtrate invasion remains controlled by the initial mud-cake permeability and formation petrophysical properties, specifically capillary pressure and relative permeability. Moreover, WBM causes radial lengths of invasion 15%–40% larger than those associated with OBM as observed on the radial distributions of electrical resistivity. It is found also that, in general, flow rates of WBM-filtrate invasion are higher than those of OBM-filtrate invasion caused by viscosity contrasts between OBM filtrate and native fluids, which slow down the process of invasion. Such a conclusion is validated by the marginal variability of array-induction resistivity measurements observed in simulations of OBM invasion compared with those of WBM invasion.
48
Lakehal, Redha, Soumaya Bendjaballah, Farid Aimer, Chourouk Rakouk, and Abdelmallek Bouzid. "Total section of the humeral artery during an open dislocation of the left elbow after a fall of a tree: a case report." Batna Journal of Medical Sciences (BJMS) 4, no. 2 (December 31, 2017): 169–70. http://dx.doi.org/10.48087/bjmscr.2017.4210.
Full textAbstract:
Introduction : Les traumatismes vasculaires ouverts sont relativement fréquents. Ils peuvent engager le pronostic fonctionnel et vital des membres. Ils sont toujours associés à des lésions des parties molles ou des organes de voisinage. La présentation clinique est variable. Le but de ce travail est de monter une luxation ouverte du coude gauche associée à une section totale de l’artère humérale. Observation : Nous rapportons l’observation d’une jeune fille âgée de 16 ans victime d’une chute d’un arbre, présentant une luxation ouverte du coude gauche associée à une fracture de l’extrémité inférieure de l’avant-bras avec abolition du pouls radial gauche, une main et avant-bras gauches bien colorés sans troubles sensitivomoteurs. L’exploration per-opératoire avait objectivé une perte de substance artérielle humérale de 3 cm avec des bouts rétractés et thrombosés avec étirement du nerf médian et luxation complète du coude associé à une rupture de la capsule articulaire sans lésion veineuse. Le geste consistait en une suture de la capsule articulaire, rétablissement de la continuité artérielle humérale par la veine saphène après préparation des extrémités artérielles humérales et enfin réduction de la luxation du coude et de l’extrémité inférieure de l’avant-bras et immobilisation du membre supérieur par une attèle plâtrer. Les suites post opératoires étaient simples avec apparition après d’un syndrome de loge de l’avant-bras nécessitant une aponévrotomie de décharge de l’avant-bras avec une nette amélioration après. Conclusion : Les trauma-tismes vasculaires ouverts peuvent se révéler soit par une hémorragie soit par une ischémie. L’exploration de l’artère humérale doit être systématique après luxation ouverte du coude. La présence d’une lésion d’un vaisseau doit être suspectée et explorée devant une ouverture sur le trajet d’un axe vasculaire. Le traitement est adapté aux lésions vasculaires et éventuellement aux lésions associées. Il est chirurgical conventionnel ou endovasculaire. L'urgence de sa mise en oeuvre est fonction de l'intensité du choc hémorragique ou des répercussions ischémiques d'aval. Le syndrome de Walkman peut se voire en post opératoire.
49
Sechi, C., S. Seddaiu, B. T. Linaldeddu, A. Franceschini, and B. Scanu. "Dieback and Mortality of Pinus radiata Trees in Italy Associated with Phytophthora cryptogea." Plant Disease 98, no. 1 (January 2014): 159. http://dx.doi.org/10.1094/pdis-05-13-0572-pdn.
Full textAbstract:
Pinus radiata D. Don is a forest tree species native to the Monterey Baja in California. Due to its rapid growth and desirable lumber and pulp qualities, between 1960 and 1980, about 12,000 ha of P. radiata were planted in Sardinia, Italy. The only disease reported on this conifer species has been Diplodia pinea, which causes tip and branch dieback (3). In January 2012, dieback and mortality of 25-year-old radiata pine trees were observed in a reforestation area of about 20 ha located in northern Sardinia (40°43′N, 9°22′E, 600 m a.s.l.). Symptoms included chlorosis, reddish-brown discoloration of the whole crown or dieback starting in the upper crown and progressing downward through the crown, and necrotic bark tissues at root collar. Approximately 25% of the trees were affected. In a first attempt, a Phytophthora species was consistently isolated from the rhizosphere of 23 symptomatic trees, which included necrotic fine roots using oak leaves as bait (4). Afterwards, it was also isolated from phloem samples taken from the margins of fresh lesions at the stem base and upper roots of affected trees using synthetic mucor agar medium (1). Isolation from soil samples of six healthy pine trees randomly selected in the site did not yield any Phytophthora isolate. On carrot agar (CA), Phytophthora colonies were stellate to slightly radiate with limited aerial mycelium. Sporangia were obpiryform, non-papillate, and non-caducous, measuring 46.9 to 51.2 × 29.1 to 32.6 μm (l:b ratio 1.9). Hyphal swellings were formed in chains or clusters; chlamydospores were not observed. These isolates had cardinal temperatures of <5°C, 25°C, and 35°C, respectively. Their morphological and cultural features were typical of Phytophthora cryptogea Pethybridge & Lafferty. They were heterothallic and produced oogonia with amphyginous antheridia when paired with an A2 mating type tester strain of P. cryptogea. This identity was corroborated by sequence analysis of the internal transcribed spacer (ITS) region of the rDNA. BLAST searches showed 99% homology with sequences of P. cryptogea available in GenBank (DQ479410 and HQ697245). The ITS sequence of a representative isolate (PH101) was submitted to GenBank (Accession Nos. KC603895). The strain PH101 was stored in the culture collection of the Department of Agriculture at the University of Sassari. Pathogenicity of isolate PH101 was verified by inoculating five freshly cut logs of radiata pine (1 m long and 15 cm diam.) with a 5-mm agar plug taken from the margin of 4-day-old culture grown on CA (4). The plug was inserted in a 5-mm hole made through the bark with a cork borer. Five control logs were inoculated with sterile CA. All logs were incubated in a growth chamber at 20°C. Phloem lesion sizes were assessed after 1 month and measured 9.7 ± 5.5 cm2 (average ± standard deviation). Control logs had no lesions. The pathogen was re-isolated from the lesions, thus fulfilling Koch's postulates. P. cryptogea has been previously reported in Australia, causing decline of radiata pine trees in wet and flooded soils (2). To our knowledge, this is the first report of P. cryptogea on P. radiata trees in Europe. References: (1) C. M. Brasier and S. A. Kirk. Plant Pathol. 50:218, 2001. (2) M. Bumbieris. Aust. J. Bot. 24:703, 1976. (3) A. Franceschini et al. Informatore Fitopatologico 1:54, 2006. (4) B. Scanu et al. For. Pathol. 43:340, 2013.
50
Li, Hu, Jun Zhu, Yanchun Xiong, Gang Liu, Yuanshi Tian, Zunbo Geng, and John Zhou. "On the depth of detection of logging-while-drilling resistivity measurements for looking-around and looking-ahead applications." Interpretation 8, no. 3 (July 23, 2020): SL151—SL158. http://dx.doi.org/10.1190/int-2019-0291.1.
Full textAbstract:
The depth of detection (DOD), which is an important concept in logging data interpretation, describes the detection capability of the borehole measurements. We have extended the definition of DOD for azimuthal information, namely, the geosignal delivered by azimuthal resistivity tools, to resistivity logs in logging-while-drilling (LWD) applications. Instead of using the radial geometric factor, the detection thresholds in predicting a geologic boundary are used to describe the DOD of a measurement. This definition unifies the criteria to evaluate the detectability of different borehole measurements, such as LWD resistivity measurements and geosignals. It also can be generalized to other kinds of well logging methods in LWD applications. Using the proposed definition, we analyze the detection capability of the LWD resistivity measurements in looking-around and looking-ahead applications; they provide more tangible descriptions. In vertical or near-vertical wells, the definition provides an indicator to evaluate the capability and reliability of looking ahead of deep/ultradeep LWD resistivity tools. The investigations on the influence of the DOD on the distance-to-boundary inversion, which can help in developing a robust and accurate inversion scheme, also are presented and discussed.