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1
Durlofsky, L. J., W. J. Milliken, and A. Bernath. "Scaleup in the Near-Well Region." SPE Journal 5, no. 01 (March 1, 2000): 110–17. http://dx.doi.org/10.2118/61855-pa.
2
Rotár-Szalkai, Á., I. Eper-Pápai, and Gy Mentes. "Well level data analysis in Hungary near a fault region." Journal of Geodynamics 41, no. 1-3 (January 2006): 183–89. http://dx.doi.org/10.1016/j.jog.2005.08.002.
3
Stamatakis, E., A. Stubos, T. Bjørnstad, and J. Muller. "Calcite scale prediction at the near-well region: A radiotracer approach." EPJ Web of Conferences 50 (2013): 03004. http://dx.doi.org/10.1051/epjconf/20135003004.
4
Dotlic, Milan, Boris Pokorni, Milenko Pusic, and Milan Dimkic. "Non-linear multi-point flux approximation in the near-well region." Filomat 32, no. 20 (2018): 6857–67. http://dx.doi.org/10.2298/fil1820857d.
Анотація:
We consider non-linear multi-point flux approximations (MPFA) scheme for flow simulations in a model of anisotropic porous medium that includes wells. The hydraulic head varies logarithmically and its gradient changes rapidly in the well vicinity. Due to this strong non-linearity of the near-well flow, use of the MPFA scheme in the near well region results in a completely wrong total well flux and an inaccurate hydraulic head distribution. In this article we propose correction of the MPFA scheme. The outcome is a scheme that is second-order accurate even in the well vicinity for anisotropic medium. Solution obtained with this scheme respects minimum and maximum principle, and also, it is non-oscillating.
5
Johansen, Thormod E., and Vitaly Khoriakov. "Iterative techniques in modeling of multi-phase flow in advanced wells and the near well region." Journal of Petroleum Science and Engineering 58, no. 1-2 (August 2007): 49–67. http://dx.doi.org/10.1016/j.petrol.2006.11.013.
6
Hwang, M. K. "Modeling Nonlinear Interactions Among Near-Well Flow Restrictions in Well-Deliverability Prediction and Simulation." SPE Reservoir Evaluation & Engineering 3, no. 04 (August 1, 2000): 360–68. http://dx.doi.org/10.2118/65407-pa.
Анотація:
Summary This work describes simulation of well productivity reduction due to near-well flow restrictions. The flow restrictions considered include: mechanical skin, partial completion, altered formation due to residual completion fluid or liquid dropout, and non-Darcy flow effects. It addresses two specific issues. The first is how to predict changes in well performance induced by changes in near-well parameters, as needed in history matching and well test analysis. A subset of this issue is how to estimate the impact of using well parameters to simplify simulation models such as partial completion skin and non-Darcy flow skin, instead of using more layers and solving the non-Darcy flow equation. The second issue is how to accurately preserve well productivity in a large grid block, as in the case of well productivity reduced by liquid dropout in a gas condensate reservoir model. To resolve these issues, this work uses direct simulation and heuristic total skin equations developed for one-dimensional and two-dimensional multilayered cases with crossflow. The equation correctly represents the effects of nonlinear interactions among near-well flow restrictions on well productivity, resulting in an effective total skin that is much larger than the conventional linear sum of individual skin components. Numerical examples show the total skin equation can be used to predict well performance and to accurately preserve well productivity in a field-scale gas condensate reservoir model. The latter use of the equation shows a feedback mechanism, wherein the total skin is used to adjust the coarse-grid well productivity. Introduction Accurate well representation is a most challenging task in reservoir simulation. It affects reservoir characterization, history matching, and in turn, the quality of well and reservoir performance simulation. Therefore, well modeling has been intensely researched. However, the task still depends very much on a simulation engineer's subjective judgment. This has several reasons. First, we often do not fully understand complex physical phenomena around a wellbore. Second, we cannot properly keep track of flow paths in the near-well region controlled by wellbore geometry, completion and stimulation practices, and well operations. Third, we do not have an accurate description on formation properties around a wellbore. Fourth, our reservoir simulators and engineering tools used have limitations. Therefore, a simulation engineer goes through a series of trade-off analyses before selecting proper well representation. The simplest way to calculate well deliverability is to use the well performance equation. We consider the pseudo-steady-state (PSS) gas flow. Then, the well deliverability and productivity index (J) can be represented by Eqs. 1 and 2 with pseudo-gas-potential m(p):1 q g = J [ m ( P ￣ R ) − m ( p w f ) ] , ( 1 ) where J = q g { m ( P ￣ R ) − m ( p w f ) } = C k g h { l n ( r e r w ) − 0.75 + S T } , ( 2 ) where h is total formation thickness, kg gas permeability, qg gas flow rate, P￣R average reservoir pressure, pwf flowing bottomhole pressure, rw wellbore radius, re reservoir radius, and C a conversion constant. For oil or water flow, pressure replaces the pseudopotential with proper changes in conversion constant and fluid properties. Eq. 2 relates J to flow potential difference, formation flow capacity (kgh) and near-well flow restrictions represented as the total skin (ST) Eq. 1 is the simplest reservoir simulator. Alternatively, a regular reservoir simulator can be used for well deliverability calculation, solving mass and momentum conservation equations. In this case, the deliverability calculation can be divided into two parts: from deep in reservoir to the near-well region, and from the near-well region into a wellbore. The well representation is more concerned with the second part. The corresponding flow equation is called the well equation. A typical well equation for a vertical well is given as2 q g = I W ( k r g ρ g / μ g ) [ m ( p r e f ) − m ( p w f ) ] , ( 3 ) I w = k Δ z / [ l n ( r r e f / r w ) + S ] , ( 4 ) where Iw is the well index, and rref the radial distance to the center of the first grid in a radial grid (or Peaceman's radius in a rectangular grid) where rref is defined. The well performance equation, Eq. 1, deals with the whole reservoir. Its parameters capture the effect of all well and reservoir properties distributed over the reservoir. Meanwhile, the well equation, Eq. 3, deals only with the fluid flow around a wellbore. Its parameters reflect the corresponding local properties. Thus, it is difficult to directly relate Eq. 3 to the well deliverability of Eq. 1. A good example is skin, the dimensionless pressure drop at the well-reservoir interface (sandface). The total skin in Eq. 2 represents the total pressure drop due to all flow restrictions in the near-well region, while the skin in Eq. 3 deals only with the pressure drop at the sandface caused by wellbore damage (mechanical skin). However, Eq. 1 and the reservoir simulator using Eq. 3 should give the same deliverability for the same reservoir. Near-Well Flow Restrictions. The near-well flow restrictions control well deliverability. The accuracy of the computed well deliverability depends on how the flow restrictions are represented. Those near-well flow restrictions are often called skin effects. There are several kinds of skin effects, and they are fluid-dynamically interacting with each other.
7
Mott, R. E., A. S. Cable, and M. C. Spearing. "Measurements of Relative Permeabilities for Calculating Gas-Condensate Well Deliverability." SPE Reservoir Evaluation & Engineering 3, no. 06 (December 1, 2000): 473–79. http://dx.doi.org/10.2118/68050-pa.
Анотація:
Summary Well deliverability in many gas-condensate reservoirs is reduced by condensate banking when the bottomhole pressure falls below the dewpoint, although the impact of condensate banking may be reduced due to improved mobility at high capillary number in the near-well region. This paper presents the results of relative permeability measurements on a sandstone core from a North Sea gas-condensate reservoir, at velocities that are typical of the near-well region. The results show a clear increase in mobility with capillary number, and the paper describes how the data can be modeled with empirical correlations which can be used in reservoir simulators. Introduction Well deliverability is an important issue in the development of many gas-condensate reservoirs, especially where permeability is low. When the well bottomhole flowing pressure falls below the dewpoint, condensate liquid may build up around the wellbore, causing a reduction in gas permeability and well productivity. In extreme cases the liquid saturation may reach values as high as 50 or 60% and the well deliverability may be reduced by up to an order of magnitude. The loss in productivity due to this "condensate banking" effect may be significant, even in very lean gas-condensate reservoirs. For example, in the Arun reservoir,1 the productivity reduced by a factor of about 2 as the pressure fell below the dewpoint, even though the reservoir fluid was very lean with a maximum liquid drop out of only 1% away from the well. Most of the pressure drop from condensate blockage occurs within a few feet of the wellbore, where velocities are very high. There is a growing body of evidence from laboratory coreflood experiments to suggest that gas-condensate relative permeabilities increase at high velocities, and that these changes can be correlated against the capillary number.2–8 The capillary number is a dimensionless number that measures the relative strength of viscous and capillary forces. There are several gas-condensate fields where simulation with conventional relative permeability models has been found to underestimate well productivity.1,9,10 To obtain a good match between simulation results and well-test data, it was necessary to increase the mobility in the near-well region, either empirically or through a model of the increase in relative permeability at high velocity. This effect can increase well productivity significantly, and in some cases may eliminate most of the effect of condensate blockage. Experimental Data Requirements Fevang and Whitson11 have shown that the key parameter in determining well deliverability is the relationship between krg and the ratio krg/ kro. When high-velocity effects are significant, the most important information is the variation of krg with krg/k ro and the capillary number Nc. The relevant values of krg/kro are determined by the pressure/volume/temperature (PVT) properties of the reservoir fluids, but typical values might be 10 to 100 for lean condensates, 1 to 10 for rich condensates, and 0.1 to 10 for near-critical fluids. There are various ways of defining the capillary number, but in this paper we use the definition (1)Nc=vgμgσ, so that the capillary number is proportional to the gas velocity and inversely proportional to interfacial tension (IFT). The capillary numbers that are relevant for well deliverability depend on the flow rate, fluid type, and well bottomhole pressure, but as a general rule, values between 10?6 and 10?3 are most important. Experimental Methods In a gas-condensate reservoir, there are important differences between the flow regimes in the regions close to and far from the well. These different flow regimes are reflected in the requirements for relative permeability data for the deep reservoir and near-well regions. Far from the well, velocities are low, and liquid mobility is usually less important, except in reservoirs containing very rich fluids. In the near-well region, both liquid and gas phases are mobile, velocities are high, and the liquid mobility is important because of its effect on the relationship between krg and krg/kro. Depletion Method. Relative permeabilities for the deep reservoir region are often measured in a coreflood experiment, where the fluids in the core are obtained by a constant volume depletion (CVD) on a reservoir fluid sample. Relative permeabilities are measured at decreasing pressures from the fluid dewpoint, and increasing liquid saturation. In this type of experiment, the liquid saturation cannot exceed the critical condensate saturation or the maximum value in a CVD experiment, so that it is not possible to acquire data at the high liquid saturations that occur in the reservoir near to the well. The "depletion" experiment provides relative permeability data that are relevant to the deep reservoir, but there can be problems in interpreting the results due to the effects of IFT. Changes in liquid saturation are achieved by reducing pressure, which results in a change of IFT. The increase in IFT as pressure falls may cause a large reduction in mobility, and Chen et al.12 describe an example where the condensate liquid relative permeability decreases with increasing liquid saturation. Steady-State Method. The steady-state technique can be used to measure relative permeabilities at the higher liquid saturations that occur in the near-well region. Liquid and gas can be injected into the core from separate vessels, allowing relative permeabilities to be measured for a wide range of saturations. Results of gas-condensate relative permeabilities measured by this technique have been reported by Henderson et al.2,6 and Chen et al.12 .
8
Stamatakis, Emmanuel, Are Haugan, C. Chatzichristos, Athanassios K. Stubos, Jiri Muller, Oyvind Dugstad, and Ioannis Palyvos. "Study of Calcium Carbonate Precipitation in the Near-Well Region Using 47Ca as Tracer." SPE Production & Operations 21, no. 01 (February 1, 2006): 33–39. http://dx.doi.org/10.2118/87436-pa.
9
Zhang, Ji, and Huilin Xing. "Numerical modeling of non-Darcy flow in near-well region of a geothermal reservoir." Geothermics 42 (April 2012): 78–86. http://dx.doi.org/10.1016/j.geothermics.2011.11.002.
10
Abobaker, Ekhwaiter E. R., Abadelhalim Elsanoose, Faisal Khan, Mohammad Azizur Rahman, Amer Aborig, Khalid Noah, and Stephen Butt. "A new assessment of perforation skin factor for vertical perforated wells in near-wellbore region." Journal of Petroleum Exploration and Production Technology 12, no. 1 (October 25, 2021): 117–33. http://dx.doi.org/10.1007/s13202-021-01326-8.
Анотація:
AbstractThe perforating technique is one of the well completion methods and a final stage that helps connect reservoir formation to wellbore during hydrocarbon production. The present work aimed to determine the effect of the perforated casing completion on the pressure gradient and perforation skin factor in the vertical near-wellbore region. This work presented a novel experimental approach for studying the effect of perforation parameters on hydrocarbon production by creating a prototype representing the near-wellbore region. The study conducted extensive laboratory testing to create two prototype artificial samples for a cylindrical near-wellbore region, open hole, and perforated casing sample. An experimental test was carried out using a geotechnical radial flow setup to measure the differential pressure in the two samples; the single-phase (water) was radially injected into the core sample within the same flow boundary conditions. Numerical simulation and statistical analysis were used to expand the investigation of the effect of the dimensions and distribution of perforations on the perforation skin factor and the pressure gradient in the cylindrical near-wellbore region. The results showed a clear view of the effect of the perforations’ parameters on the pressure gradient in the vertical near-wellbore region. In addition, two novel correlations were produced from statistical analysis that simplified the estimation of the perforation skin factor in the perforated casing completion. This study will help to clarify and understand the effect of perforation parameters on well productivity.
11
Robert, P., M. F. Devaux, A. Qannari, and M. Safar. "Mid and near Infrared Study of Carbohydrates by Canonical Correlation Analysis." Journal of Near Infrared Spectroscopy 1, no. 2 (March 1993): 99–108. http://dx.doi.org/10.1255/jnirs.13.
Анотація:
Multivariate data treatments were applied to mid and near infrared spectra of glucose, fructose and sucrose solutions in order to specify near infrared frequencies that characterise each carbohydrate. As a first step, the mid and near infrared regions were separately studied by performing Principal Component Analyses. While glucose, fructose and sucrose could be clearly identified on the similarity maps derived from the mid infrared spectra, only the total sugar content of the solutions was observed when using the near infrared region. Characteristic wavelengths of the total sugar content were found at 2118, 2270 and 2324 nm. In a second step, the mid and near infrared regions were jointly studied by a Canonical Correlation Analysis. As the assignments of frequencies are generally well known in the mid infrared region, it should be useful to study the relationships between the two infrared regions. Thus, the canonical patterns obtained from the near infrared spectra revealed wavelengths that characterised each carbohydrate. The OH and CH combination bands were observed at: 2088 and 2332 nm for glucose, 2134 and 2252 nm for fructose, 2058 and 2278 nm for sucrose. Although a precise assignment of the near infrared bands to chemical groups within the molecules was not possible, the present work showed that near infrared spectra of carbohydrates presented specific features.
12
Fu, Jianlin, Carl L. Axness, and J. Jaime Gomez-Hernandez. "Upscaling Transmissivity in the Near-Well Region for Numerical Simulation: A Comparison on Uncertainty Propagation." Engineering Applications of Computational Fluid Mechanics 5, no. 1 (January 2011): 49–66. http://dx.doi.org/10.1080/19942060.2011.11015352.
13
Jiang, Youshi, Jinzhou Zhao, Yongming Li, Hu Jia, and Liehui Zhang. "Extended Finite Element Method for Predicting Productivity of Multifractured Horizontal Wells." Mathematical Problems in Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/810493.
Анотація:
Based on the theory of the extended finite element method (XFEM), which was first proposed by Moës for dealing with the problem characterized by discontinuities, an extended finite element model for predicting productivity of multifractured horizontal well has been established. The model couples four main porous flow regimes, including fluid flow in the away-from-wellbore region of reservoir matrix, radial flow in the near-wellbore region of reservoir matrix, linear flow in the away-from-wellbore region of fracture, and radial flow in the near-wellbore region of fracture by considering mass transfer between fracture and matrix. The method to introduce the interior well boundary condition into the XFEM is proposed, and therefore the model can be highly adaptable to the complex and asymmetrical physical conditions. Case studies indicate that this kind of multiflow problems can be solved with high accuracy by the use of the XFEM.
14
Wang, Q., H. Zhan, and Z. Tang. "Forchheimer flow to a well considering time-dependent critical radius." Hydrology and Earth System Sciences Discussions 10, no. 11 (November 19, 2013): 14095–129. http://dx.doi.org/10.5194/hessd-10-14095-2013.
Анотація:
Abstract. Previous studies on the non-Darcian flow into a pumping well assumed that critical radius (RCD) was a constant or infinity, where RCD represents the location of the interface between the non-Darcian flow region and Darcian flow region. In this study, a two-region model considering time-dependent RCD was established, where the non-Darcian flow was described by the Forchheimer equation. A new iteration method was proposed to estimate RCD based on the finite-difference method. The results showed that RCD increased with time until reaching the quasi-steady state flow, and the asymptotic value of RCD only depended on the critical specific discharge beyond which flow became non-Darcian. A larger inertial force would reduce the change rate of RCD with time, and resulted in a smaller RCD at a specific time during the transient flow. The difference between the new solution and previous solutions were obvious in the early pumping stage. The new solution agreed very well with the solution of previous two-region model with a constant RCD under quasi-steady flow. It agreed with the solution of the fully Darcian flow model in the Darcian flow region, and with the solution of the fully non-Darcian flow model in the non-Darcian flow region near the well.
15
Song, Yong, Zhenlin Wang, Wei Wang, Peirong Yu, Gang Chen, Jiaying Lin, Bolong Zhu, and Xuyang Guo. "Coupled Thermal-Hydraulic-Mechanical Modeling of Near-Well Stress Evolution in Naturally Fractured Formations during Drilling." Processes 11, no. 6 (June 7, 2023): 1744. http://dx.doi.org/10.3390/pr11061744.
Анотація:
Naturally fractured formations usually have strong heterogeneities. Drilling and production operations in such formations can involve unwanted formation failure risks such as wellbore collapse and wellbore fracturing. This study presents a coupled thermal-hydraulic-mechanical numerical model for near-well stress evolutions during drilling in naturally fractured formations. The evolution of pressure, temperature, and geo-mechanical responses on the wellbore wall and in the near-well region is simulated. The effects of wellbore pressure, internal friction angle, and natural fracture length on formation rock risks are discussed. A failure index is used to quantify the formation rock failure risks. The existence of natural fractures magnifies the heterogeneous system response induced by drilling. Increasing the wellbore pressure from a relatively low value can improve the support for the wellbore wall, which reduces the failure risks caused by shearing. In mechanically weak formations, the effect of natural fractures on formation rock failure becomes more significant. When the natural fracture length is large, the near-well region tends to have greater failure risks as the formations become more mechanically weak. This study provides a quantitative understanding of the effects of drilling and formation parameters on failure risks.
16
Sathe, Sandip S., Kranti Patil, Rohit Chavan, Vaishnavi Jadhav, Shubham Kamble, and Uday Bhan. "Delineation of safe groundwater aquifers in a Fluoride contaminated region: Walwa Taluka, Maharashtra." E3S Web of Conferences 405 (2023): 04010. http://dx.doi.org/10.1051/e3sconf/202340504010.
Анотація:
Groundwater aquifer contamination has leads health problems in village areas of Maharashtra, India. In this study, groundwater analysis was carried out for different groundwater parameters along with fluoride to delineate the high and low contaminated fluoride region in the Walwa taluka, Maharashtra. A distinct contaminated regions for high and low F‒ contaminated regions were identified in the collected post monsoon groundwater samples (n = 144). In total 98% samples are unsuitable for consumption. Hydro-geochemistry of the region showed highest anion concentration for bicarbonate (1880 mg/L), whereas highest cation concentration for calcium was measured as 118 mg/L. It is main cause for alkaline groundwater condition in this region. The 2D ordinary kriging results are well corborated with the obtained hydrogeochemistry results. The low F‒ concentration region was found near the Krishna River, whereas high concentration regions were found near the agricultural and high land region. The primary hydrogeochemistry of the region suggests that the geogenic source of F‒ minerals in the region. The practice of fertiliser, herbicides and pesticides on agricultural field suggests that these are the secondary source for groundwater F‒ contamination. The applied numerical groundwater modelling software, provided technically viable and effective decision making-tool for identification of safe region in the study area.
17
Feng, Yan, Mingqiu Li, Qingyuan Deng, Peng Yu, Xiuqing Li, and Xi Yang. "Productivity Formula of Horizontal Well in Low-Permeability Gas Reservoir considering Multiple Factors." Geofluids 2023 (June 30, 2023): 1–13. http://dx.doi.org/10.1155/2023/9333441.
Анотація:
For horizontal well in low-permeability gas reservoir, the effects of threshold pressure gradient, stress sensitivity, and gas slippage have significant impacts on the well productivity. At present, there are few productivity formulas for horizontal gas well considering all these factors. In this paper, based on the flow analysis of horizontal well in low-permeability gas reservoir, the whole flow field was divided into two parts, namely, far wellbore region and near wellbore region, among which the far wellbore region is composed of plane linear flow region and plane radial flow region and the near wellbore region is composed of vertical plane radial flow region and spherical plane central flow region. Then, a new productivity formula is established based on the steady-state seepage theory and the equivalent seepage resistance method, with the consideration of threshold pressure gradient, stress sensitivity, and gas slippage effect. The accuracy of the formula in this paper is verified through comparing with other classical models, and the influence of various factors on the well productivity is analyzed. The analysis results show that stress sensitivity has the most significant effect on horizontal gas well production, followed by threshold pressure gradient, and the gas slippage has the least effect. With the consideration of all influencing factors, the higher the formation pressure and reservoir thickness, the higher the productivity, and the increase of productivity increases with the increase of flow pressure difference. The increasing trend of gas productivity index per meter with the increase of reservoir permeability is first fast and then slow. When the reservoir permeability is greater than 1.2 mD, the increment of gas productivity index per meter (MGPI) decreases. When the length of horizontal well is greater than 1400 m, the increment of gas productivity index per meter decreases with the increase of gas reservoir thickness. Therefore, it is recommended to control the horizontal well length within 1400 m in low-permeability gas reservoir. In addition, the absolute open flow charts corresponding to reservoir thickness and horizontal well length under different reservoir permeability conditions were also given, which can provide theoretical guidance for the selection of horizontal well length during the development of low-permeability gas reservoirs.
18
Tenge, Brad, B. R. Buchanan, and D. E. Honigs. "Calibration in the Fiber Optic Region of the Near-Infrared." Applied Spectroscopy 41, no. 5 (July 1987): 779–85. http://dx.doi.org/10.1366/0003702874448409.
Анотація:
Chemical sensing in remote, hostile environments is possible with optical fiber technology. Telecommunications optical fiber transmits light in the near-infrared region. The least amount of attenuation of transmitted power is between 1050 nm and 1600 nm. It is a natural step to apply near-infrared analysis techniques to data remotely collected over optical fibers. A feasibility study is conducted to see how well calibration techniques, Multiple Linear Regression with either Step-up search or All Possible Combinations search, perform in the fiber optic region of the near-infrared. Calibration in the 1131–1531 nm region is compared to calibration in the 1131–2531 nm region. The latter region is considered more information-rich than the former. In spite of this, examination of the predictive power of calibration models formed strictly from fiberoptic-region absorbance data indicates that this region contains useful analytical informaton.
19
Goodarzi Ardakani, Vahid, Xin Tu, Alberto M. Gambaruto, Iolanda Velho, Jorge Tiago, Adélia Sequeira, and Ricardo Pereira. "Near-Wall Flow in Cerebral Aneurysms." Fluids 4, no. 2 (May 16, 2019): 89. http://dx.doi.org/10.3390/fluids4020089.
Анотація:
The region where the vascular lumen meets the surrounding endothelium cell layer, hence the interface region between haemodynamics and cell tissue, is of primary importance in the physiological functions of the cardiovascular system. The functions include mass transport to/from the blood and tissue, and signalling via mechanotransduction, which are primary functions of the cardiovascular system and abnormalities in these functions are known to affect disease formation and vascular remodelling. This region is denoted by the near-wall region in the present work, and we outline simple yet effective numerical recipes to analyse the near-wall flow field. Computational haemodynamics solutions are presented for six patient specific cerebral aneurysms, at three instances in the cardiac cycle: peak systole, end systole (taken as dicrotic notch) and end diastole. A sensitivity study, based on Newtonian and non-Newtonian rheological models, and different flow rate profiles, is effected for a selection of aneurysm cases. The near-wall flow field is described by the wall shear stress (WSS) and the divergence of wall shear stress (WSSdiv), as descriptors of tangential and normal velocity components, respectively, as well as the wall shear stress critical points. Relations between near-wall and free-stream flow fields are discussed.
20
Martins, Lucimara, Alberto Ardila, Ruth Gruenwald, and Ronaldo de Souza. "Extended Near-IR Spectra of NGC 1068." Proceedings of the International Astronomical Union 5, S267 (August 2009): 120. http://dx.doi.org/10.1017/s1743921310005818.
Анотація:
AbstractNGC 1068 is a well-studied Seyfert type 2 AGN. Because of its proximity, it is one of the brightest Seyferts observed. Its nuclear region harbors a variety of astrophysical phenomena connected to physical conditions in the NLR and its emission lines. The relative importance of photoionization from the nucleus and shocks produced by jets has been long debated. To help resolve this controversy, we have carried out long-slit spectroscopy in the near-IR and present here for the first time spectroscopy of the whole range from 0.8 to 2.4 μm for this galaxy over 15″ in the nuclear region.
21
Liang, Zuoxiang, Dzianis Prakapenka, Paul M. VanRaden, Jicai Jiang, Li Ma, and Yang Da. "A Million-Cow Genome-Wide Association Study of Three Fertility Traits in U.S. Holstein Cows." International Journal of Molecular Sciences 24, no. 13 (June 22, 2023): 10496. http://dx.doi.org/10.3390/ijms241310496.
Анотація:
A genome-wide association study (GWAS) of the daughter pregnancy rate (DPR), cow conception rate (CCR), and heifer conception rate (HCR) using 1,001,374–1,194,736 first-lactation Holstein cows and 75,140–75,295 SNPs identified 7567, 3798, and 726 additive effects, as well as 22, 27, and 25 dominance effects for DPR, CCR, and HCR, respectively, with log10(1/p) > 8. Most of these effects were new effects, and some new effects were in or near genes known to affect reproduction including GNRHR, SHBG, and ESR1, and a gene cluster of pregnancy-associated glycoproteins. The confirmed effects included those in or near the SLC4A4-GC-NPFFR2 and AFF1 regions of Chr06 and the KALRN region of Chr01. Eleven SNPs in the CEBPG-PEPD-CHST8 region of Chr18, the AFF1-KLHL8 region of Chr06, and the CCDC14-KALRN region of Chr01 with sharply negative allelic effects and dominance values for the recessive homozygous genotypes were recommended for heifer culling. Two SNPs in and near the AGMO region of Chr04 that were sharply negative for HCR and age at first calving, but slightly positive for the yield traits could also be considered for heifer culling. The results from this study provided new evidence and understanding about the genetic variants and genome regions affecting the three fertility traits in U.S. Holstein cows.
22
Lira, Paulina, Patricia Arévalo, Phil Uttley, Ian McHardy, and Elme Breedt. "X-Ray, Optical, and Near-IR Long-Term Monitoring of AGN." Proceedings of the International Astronomical Union 5, S267 (August 2009): 90–95. http://dx.doi.org/10.1017/s1743921310005624.
Анотація:
AbstractWe are conducting long-term monitoring of several AGN with the aim of understanding the interplay between the emitting regions around the central black hole as well as the physics of the accreting flow. Here we present results for two of our sources, NGC 3783 and MR 2251–178, with strong evidence for disk-driven variability and the existence of cold accretion disks, where near-IR emission can be clearly detected from a region close to the black hole.
23
Elwardany, Michael D., Jean-Pascal Planche, and Jeramie J. Adams. "Determination of Binder Glass Transition and Crossover Temperatures using 4-mm Plates on a Dynamic Shear Rheometer." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 10 (May 16, 2019): 247–60. http://dx.doi.org/10.1177/0361198119849571.
Анотація:
The accurate rheological characterization of asphalt binder properties, as a function of pavement service life, is crucial to improving asphalt binder specifications, modifications, and formulation methods. Bitumen streams from refineries have experienced significant changes since the development of SHRP Superpave specifications as a result of economic, technical, and environmental reasons. Binder rheological behavior is divided into three regions: near glassy region, terminal region, and an intermediate “transition” region between them. At a reference frequency, these regions are separated by two characteristic temperatures: (1) the glass transition temperature (Tg), which is the temperature between the near glassy region and the intermediate region, and (2) the crossover temperature (TG’=G”), which is the temperature between the intermediate region and the terminal region. In this study, Tg and TG’=G” of 50 binders were obtained from a dynamic shear rheometer (DSR) using 4-mm parallel plates. Glass transition temperatures from DSR were compared with those obtained from modulated differential scanning calorimetry (DSC). Tg and TG’=G” were also compared with continuous low-PG temperatures and ΔTc parameter. Results indicate that critical temperatures based on the creep stiffness and the relaxation rate can be determined from Tg and TG’=G”, respectively. Furthermore, ΔTc parameter correlates well with the intermediate region temperature range (TIR).
24
Davletshin, F. F., R. Z. Akchurin, R. F. Sharafutdinov, and D. F. Islamov. "Nonisothermal Fluid Flow in a Well during Induction Heating of the Casing String." Известия Российской академии наук. Механика жидкости и газа, no. 4 (July 1, 2023): 81–92. http://dx.doi.org/10.31857/s1024708423600045.
Анотація:
The distinctive features of the flow velocity and temperature fields of ascending fluid flow in a metal round pipe (round casing string installed in a production well) under the conditions of its local induction heating are studied. The results of investigation are based on numerical solution of the Navier–Stokes equations in the Boussinesq–Oberbeck approximation. The calculations were performed using the Ansys Fluent software package (license ANSYS Academic Research CFD under the agreement with the Bashkir State University dated June 15, 2020). The fluid flow rates of 10 and 50 m3 per day are considered. Such flow rates correspond to the laminar and transitional flow regimes in the casing pipe. It is found that local perturbations of the velocity and temperature fields are presented in the near-wall region of the heated casing. Fluid temperature perturbations reach several Kelvin degrees, the local flow velocity which increases due to natural thermal convection in the near-wall region of the casing string being several times higher than the cross-section-average flow velocity. The occurrence of areas of vortex flow motion over the interval of induction heating due to natural thermal convection is shown.
25
Wang, Qidong, Zhenya Wei, Jiaen Wang, Wuwei Chen, and Naihan Wang. "Curve recognition algorithm based on edge point curvature voting." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 4 (August 1, 2019): 1006–19. http://dx.doi.org/10.1177/0954407019866975.
Анотація:
In this paper, a new curve-lane recognition algorithm is proposed. The algorithm uses edge point curvature voting to determine the region of interest based on near-vision straight-lane information. First, information is detected in the near-vision area regarding the straight lines to the left and right of the current lane. Near-vision lane-line extraction includes lane image filtering, as well as edge detection of the region of interest below the vanishing line. The vanishing point is positioned by determining the position of the edge point and distribution of the direction angle. In addition, the straight line is extracted based on the position of the vanishing point. The straight lines that are constructed for the current lane in this way are selected and used as supplementation, in combination with the lane model. Next, the road curvature range isometry is divided into multiple subdivision regions. The near-vision lane straight-line curvature parameters extending from each edge point in the region of interest are computed by combining the straight-line near-vision lane information with the curve lane model in the pixel coordinate system. Subsequently, voting and counting are carried out for the curvature regions of each edge point to which the corresponding curvature computing values belong. Finally, the counting maximum from the corresponding curvature regions of the straight lines located to the left and right of the current lane are searched for, and the curvature region is converted, to obtain the lane line corresponding to the curvature parameter values. Experimental results indicate that the proposed curve-lane recognition algorithm can effectively detect the curve lanes of different curvatures. The results also indicate that the proposed curve detection method is highly accurate, and the algorithm is very robust in different environments.
26
Kampen, Jörg. "On American Derivatives and Related Obstacle Problems." International Journal of Theoretical and Applied Finance 06, no. 06 (September 2003): 565–91. http://dx.doi.org/10.1142/s0219024903002109.
Анотація:
We derive obstacle problems for pricing of American derivatives with multiple underlyings heuristically using only a few postulates such that classical (Brownian motion) models as well as models based on Levy processes can be considered in our frame. For the classical models we define a "signed measure" which allows to compute the exercise region near maturity and obtain a generic condition for continuity of the free boundary and prove some more general features of exercise regions for classical models. Especially, we investigate the exercise regions of the most important American derivatives with one and multiple underlyings where we include dependence of volatility and interest rates on time and the underlyings extending and recovering some classical results. Further applications include stochastic volatility models. It is shown that in classical stochastic volatility models where volatility is driven by an Ornstein-Uhlenbeck process an American compound call has a nonempty exercise region and compute the exercise region near expiration in a typical situation.
27
Capone, Alessandro, Fabio Di Felice, and Francisco Alves Pereira. "Particle Image Velocimetry measurements in a turbulent channel flow laden with elongated particles." Journal of Physics: Conference Series 2293, no. 1 (June 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2293/1/012005.
Анотація:
Abstract Particle Image Velocimetry is employed to investigate the turbulence modulation induced by dispersed elongated, rod-like particles in a turbulent channel flow. Particles with two different aspect ratios AR=40,80 are tested, at a volume fraction of 10-5. Carrier flow velocimetry data and distribution and orientation data of dispersed particles are obtained by an ad-hoc single-camera phase-discrimination technique. Carrier flow data shows that in the near-wall region turbulence modulation by particle occurrs as well as a decrease of average streamwise velocity. Analysis of conditional probability density function of particles location reveals that particles locations statistically match flow regions with instantaneous low vorticity and high streamwise velocity, in particular in the near-wall region.
28
Corbett, Patrick William Michael, and Gleyden Lucila Benítez Duarte. "Understanding subsurface fluvial architecture from a combination of geological well test models and well test data." Geological Society, London, Special Publications 488, no. 1 (December 14, 2018): 237–57. http://dx.doi.org/10.1144/sp488.7.
Анотація:
AbstractTwo decades of geological modelling have resulted in the ability to study single-well geological models at a sufficiently high resolution to generate synthetic well test responses from numerical simulations in realistic geological models covering a range of fluvial styles. These 3D subsurface models are useful in aiding our understanding and mapping of the geological variation (as quantified by porosity and permeability contrasts) in the near-wellbore region. The building and analysis of these models enables many workflow steps, from matching well test data to improving history-matching. Well testing also has a key potential role in reservoir characterization for an improved understanding of the near-wellbore subsurface architecture in fluvial systems. Developing an understanding of well test responses from simple through increasingly more complex geological scenarios leads to a realistic, real-life challenge: a well test in a small fluvial reservoir. The geological well testing approach explained here, through a recent fluvial case study in South America, is considered to be useful in improving our understanding of reservoir performance. This approach should lead to more geologically and petrophysically consistent models, and to geologically assisted models that are both more correct and quicker to match to history, and thus, ultimately, to more useful reservoir models. It also allows the testing of a more complex geological model through the well test response.
29
Chen, Pei-Yuan, Ching-Pin Tung, Jung-Hsuan Tsao, and Chia-Jeng Chen. "Assessing Future Rainfall Intensity–Duration–Frequency Characteristics across Taiwan Using the k-Nearest Neighbor Method." Water 13, no. 11 (May 28, 2021): 1521. http://dx.doi.org/10.3390/w13111521.
Анотація:
This study analyzes the changes in rainfall intensities across Taiwan using the k-Nearest Neighbor method. Biases are corrected according to the identified discrepancy between the probability distribution of the model run and that of the observed data in the historical period. The projections of 21 weather stations in Taiwan under 10 (2RCP × 5GCM) scenarios for the near-(2021–2040) and far-future (2081–2100) are derived. The frequently occurred short-duration storm events in some regions decrease, but they are still vulnerable to flood considering the existing drainage capacities. More specifically, the land-subsidence region in the central, the landslide-sensitive mountainous region in the north and central, the pluvial- and fluvial-flood prone region in the north, and the eastern regions with vulnerable infrastructures should be especially aware of long-duration extreme events. Associations of the rainfall intensity with the different return period as well as the duration are further analyzed. The short-duration extreme events will become stronger, especially for 1-h events in the northern region and 1 or 2-h events in both the southern and eastern regions. In addition, places without experiences of long-lasting events may experience rainfall amounts exceeding 500 mm should be alert. Adaptation measures such as establishing distributed drainage system or renewing hydrological infrastructures in the eastern region are suggested considering the near future projection, and in the central and the southern regions for far future as well. Our findings can assist adaptation-related decision-making for more detailed stormwater/water resource management.
30
Yan, Jie, Nan Gui, Gongnan Xie, and Jinsen Gao. "Direct Numerical Simulation of Particle-Laden Swirling Flows on Turbulence Modulation." Mathematical Problems in Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/257837.
Анотація:
The modulation of turbulence by the laden particles in swirling flows is studied via direct numerical simulation. The statistical characteristics of turbulence modulation are investigated in detail under the effects of different mass loadings as well as Stokes numbers. It is found that the characteristics of turbulence modulation for different Stokes numbers are very similar to each other when the mass loading is light. As the mass loading increases, small particles seem to modulate turbulence more rapidly than large particles. The number concentration or the number flow rate of particles plays an important role in modulation of turbulence. It induces the preferential attenuation of turbulence for small particles in the near field region. Moreover, the trends of modulation of the axial/azimuthal fluctuations, the turbulent kinetic energy, and the Reynolds stress tenor as well as its invariants are similar in the near field region. However, when the turbulence is decayed sufficiently in the downstream region, the inverse turbulence modulation may occur especially for the regions with local intensive accumulation of small particles.
31
Ding, D. Y. Y. "Modeling Formation Damage for Flow Simulations at Reservoir Scale." SPE Journal 15, no. 03 (May 20, 2010): 737–50. http://dx.doi.org/10.2118/121805-pa.
Анотація:
Summary Formation damage generally is limited to the immediate nearwellbore region and needs a particular near-well-flow modeling using fine gridblocks. However, near-well models are usually developed as standalone models and are decoupled from reservoir models. Using a standalone near-well model that does not take into account production scenarios cannot predict well injectivity or productivity correctly. In this paper, we propose a new technique for the coupled modeling of a near-well-flow model and a reservoir model in a simple and consistent way. In this new approach, data are exchanged and updated through boundary conditions for the near-well model and through numerical productivity indices (PIs) (or skin factors) for the reservoir model. Examples show that this coupled modeling gives quite satisfactory results.
32
Lazareva, O. S., and I. N. Sovetov. "Reserves for reducing production costs in the region." Lizing (Leasing), no. 4 (August 2, 2023): 35–39. http://dx.doi.org/10.33920/vne-03-2304-06.
Анотація:
The paper considers the main reserves for reducing the cost price of bakery products of a bakery enterprise, as well as studies and performs calculations to reduce material costs. The reduction and preservation of the cost price of bread production for the near future is justified, and the financial results from saving raw material costs are determined.
33
Hoshi, Y., and M. Tamura. "Dynamic multichannel near-infrared optical imaging of human brain activity." Journal of Applied Physiology 75, no. 4 (October 1, 1993): 1842–46. http://dx.doi.org/10.1152/jappl.1993.75.4.1842.
Анотація:
The present paper demonstrates functional brain mapping with an optical imaging technique by using tissue-transparent near-infrared light. With a maximal five-channel optical monitoring system, we succeeded in detecting region-specific changes in both the hemoglobin oxygenation state and blood volume during various mental tasks, in addition to visual and auditory stimulation. The time course of increases in blood supply varied with each brain region and depended on the type of internal operations occurring during the mental tasks. Changes in the hemoglobin oxygenation state were also different from region to region. This showed that there were regional variations of the oxygen delivery-oxygen utilization relationship during activation of brain activity. The usefulness of multichannel near-infrared functional imaging was well documented.
34
Janssen, P. H., W. M. G. T. van den Broek, and C. K. Harris. "Laboratory Study Investigating Emulsion Formation in the Near-Wellbore Region of a High Water-Cut Oil Well." SPE Journal 6, no. 01 (March 1, 2001): 71–79. http://dx.doi.org/10.2118/69740-pa.
35
Li Jian-Jun. "Design of active region for GaAsP/AlGaAs tensile strain quantum well laser diodes near 800 nm wavelength." Acta Physica Sinica 67, no. 6 (2018): 067801. http://dx.doi.org/10.7498/aps.67.20171816.
36
Park, Yong-Chan, Seunghee Kim, Jang Hyun Lee, and Young Jae Shinn. "Effect of reducing irreducible water saturation in a near-well region on CO2 injectivity and storage capacity." International Journal of Greenhouse Gas Control 86 (July 2019): 134–45. http://dx.doi.org/10.1016/j.ijggc.2019.04.014.
37
Carpenter, Chris. "Completion Design Evaluated by Use of Field Offset Well-Pressure Measurements." Journal of Petroleum Technology 73, no. 04 (April 1, 2021): 46–47. http://dx.doi.org/10.2118/0421-0046-jpt.
Анотація:
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201346, “Are We Overstimulating Our Laterals? Evaluating Completion Design Practices Based on Field Offset Well-Pressure Measurements,” by Puneet Seth, SPE, The University of Texas at Austin, and Brendan Elliott, SPE, and Trevor Ingle, SPE, Devon Energy, et al., prepared for the 2020 SPE Annual Technical Conference and Exhibition, originally scheduled to be held in Denver, Colorado, 5–7 October. The paper has not been peer reviewed. Increased injection volumes coupled with a suboptimal completion design can lead to overstimulation at current well-spacing densities. In the complete paper, the authors analyze offset well-pressure measurements in the Permian Basin to evaluate if a fracturing job is overstimulated. Additionally, numerical modeling studies are performed to evaluate the extent of overstimulation in different scenarios and provide recommendations to maximize the capital efficiency of a fracturing job. In their analysis, the authors focus on the scenario in which fracturing hits occur when child-well fractures intersect with the parent well. Field Data Analysis Pumping for the full designed volume and time (typically 90 minutes) according to well-stimulation procedures is currently common in the industry. Often, the observation of hydraulic interactions is not coupled with a decision to alter or change the stimulation. The authors analyzed the offset well-pressure response monitored with a surface pressure gauge in multiple parent wells in the Permian Basin during stimulation in nearby child wells. The child wells were stimulated after roughly 1 year of production from the parent wells. The focus of this study was to identify fracture-driven interactions—specifically the timing of intersection of the child-well fractures with the offset parent wells, which are recorded as massive hydraulic pressure responses. The results of this analysis for different well pairs are presented in the complete paper. To better understand the factors that affect fracture propagation from the child wells toward the parent wells, fracture arrival times, and capital efficiency of a fracturing job, a series of numerical simulations was performed with a fully coupled hydraulic fracturing simulator. Simulation Results Numerical simulations were performed using an integrated hydraulic fracturing and reservoir simulator developed at The University of Texas at Austin. This simulator solves for flow and geomechanics in the reservoir, fracture, and wellbore domains in a tightly coupled manner. Hydraulic fractures are modeled as compliant discontinuities in the reservoir rather than high-permeability gridblocks. This is important in order to capture the stress alterations around a propagating fracture accurately. Effect of Parent-Well Production (Depleted Region). For this study, two scenarios were analyzed. In the first case, fracture propagation from a child well stimulated near a recently fractured unproduced parent well (no depletion) was considered. In this case, the fracture from the child well propagates away from the parent well because of elevated stresses near the parent well. In the second case, a child well is stimulated near a parent well that has been producing for 300 days before child-well stimulation. In this scenario, the child-well fracture propagates toward the parent well because of a depleted region that develops near the parent well (because of production) and relaxes the reservoir stresses around the parent well. This causes the child-well fracture to grow preferentially toward the parent well (toward the low-stress region). In fact, in this scenario, as the fracture reaches the depleted reservoir region, its growth accelerates toward the parent well and intersects with the parent well. Even minor depletion can induce asymmetric growth of infill child-well fractures toward the parent well.
38
Jovanovic, Jovan, and Rafaela Hillerbrand. "On peculiar property of the velocity fluctuations in wall-bounded flows." Thermal Science 9, no. 1 (2005): 3–12. http://dx.doi.org/10.2298/tsci0501003j.
Анотація:
Statistical analysis of the velocity fluctuations is performed for the near-wall region of wall-bounded flows. By demanding that the small-scale part of the fluctuations satisfies constraints imposed by local ax symmetry it was found that the small scales must be entirely suppressed in the near-wall region. This major conclusion is well supported by all available data from direct numerical simulations.
39
MORLAND, L. W. "Asymptotic analysis of flow near a glacier terminus." Journal of Glaciology 64, no. 246 (June 4, 2018): 536–42. http://dx.doi.org/10.1017/jog.2018.42.
Анотація:
AbstractThe non-linearly viscous ice flow in the vicinity of a glacier terminus, an observation region, depends crucially on the upstream flow as well as on the local surface and bed conditions. The former requires a likely complex solution of the balance laws and boundary conditions for the complete glacier. However, if the profile and downstream surface tangential velocity in the observation region are measured at an observation time t = 0, and a two-dimensional flow approximation is satisfactory, the complete stress and velocity fields satisfying local reduced model equations in the observation region at time t = 0 can be determined by asymptotic expansions in upstream distance from the (moving) terminus. Thus the full strain-rate and stress tensors are determined without prescribing the basal conditions. The terminus velocity is determined in terms of the net accumulation or melt flux and surface velocity at the terminus, with bounds for advance or retreat. The analysis and illustration are presented for a plane flow approximation.
40
ARONSON, DAG, ARNE V. JOHANSSON, and LENNART LÖFDAHL. "Shear-free turbulence near a wall." Journal of Fluid Mechanics 338 (May 10, 1997): 363–85. http://dx.doi.org/10.1017/s0022112097005065.
Анотація:
The mean shear has a major influence on near-wall turbulence but there are also other important physical processes at work in the turbulence/wall interaction. In order to isolate these, a shear-free boundary layer was studied experimentally. The desired flow conditions were realized by generating decaying grid turbulence with a uniform mean velocity and passing it over a wall moving with the stream speed. It is shown that the initial response of the turbulence field can be well described by the theory of Hunt & Graham (1978). Later, where this theory ceases to give an accurate description, terms of the Reynolds stress transport (RST) equations were measured or estimated by balancing the equations. An important finding is that two different length scales are associated with the near-wall damping of the Reynolds stresses. The wall-normal velocity component is damped over a region extending roughly one macroscale out from the wall. The pressure–strain redistribution that normally would result from the Reynolds stress anisotropy in this region was found to be completely inhibited by the near-wall influence. In a thin region close to the wall the pressure–reflection effects were found to give a pressure–strain that has an effect opposite to the normally expected isotropization. This behaviour is not captured by current models.
41
EIFF, OLIVIER S., and JAMES F. KEFFER. "On the structures in the near-wake region of an elevated turbulent jet in a crossflow." Journal of Fluid Mechanics 333 (February 25, 1997): 161–95. http://dx.doi.org/10.1017/s0022112096004314.
Анотація:
A pattern-recognition technique, applied to multi-point simultaneous velocity measurements obtained with 45° X-wire anemometer probes, is used to extract and characterize the underlying organized motions, i.e. coherent structures, within the near-wake region of a turbulent round jet discharged perpendicularly from a pipe into a crossflow. This flow has been found to be quite complex owing to its three-dimensional nature and the interactions between several flow regions. Analyses of the underlying coherent structures, which play an important role in the physics of the flow, are still rare and are mostly based on flow-visualization techniques. Using a pattern-recognition technique in conjunction with hot-wire measurements, we recently examined the wake regions of the pipe and jet at levels near the tip of the pipe, and found that Kármán-like vortex structures in the wake of the pipe are locked to similar structures in the jet-wake. In this paper we expand upon our previous work and characterize these structures throughout the wake of the jet up into the region of the bent-over jet – a region where they have not been identified previously. The complex geometry of these structures in the wake of the jet as well as their interaction with the bent-over jet are discussed. The results show that these structures split before they link to similar structures on the opposite side of the symmetry plane in the jet region. The results further suggest that the vorticity due to the structures in the wake of the jet contributes to the motion of the well-known counter-rotating vortex pair.
42
Bradley, Brendon A., Hoby N. T. Razafindrakoto, and M. Ahsan Nazer. "Strong ground motion observations of engineering interest from the 14 November 2016 Mw7.8 Kaikōura, New Zealand earthquake." Bulletin of the New Zealand Society for Earthquake Engineering 50, no. 2 (June 30, 2017): 85–93. http://dx.doi.org/10.5459/bnzsee.50.2.85-93.
Анотація:
This paper provides a brief discussion of observed strong ground motions from the 14 November 2016 Mw7.8 Kaikōura earthquake. Specific attention is given to examining observations in the near-source region where several ground motions exceeding 1.0g horizontal are recorded, as well as up to 2.7g in the vertical direction at one location. Ground motion response spectra in the near-source, North Canterbury, Marlborough and Wellington regions are also examined and compared with design levels. Observed spectral amplitudes are also compared with predictions from empirical and physics-based ground motion modelling.
43
Pressley, T. A. "Phylogenetic conservation of isoform-specific regions within alpha-subunit of Na(+)-K(+)-ATPase." American Journal of Physiology-Cell Physiology 262, no. 3 (March 1, 1992): C743—C751. http://dx.doi.org/10.1152/ajpcell.1992.262.3.c743.
Анотація:
Site-directed polyclonal antibodies were generated against four oligopeptides derived from the rat alpha-isoforms of Na(+)-K(+)-adenosinetriphosphatase (i.e., Na(+)-K+ pump) and were used to assess the phylogenetic conservation of the target regions. The first antibody was directed against a region near the phosphorylation site that is conserved among alpha-subunits from numerous species. The remaining antibodies were specific for the isoforms of alpha and recognized a region near the fluorescein isothiocyanate-reactive lysine of the adenine binding site. Immunoblots of protein from a number of species probed with these antibodies revealed dramatic differences in the conservation of the target sequences. The region derived from alpha 1 was found in four of the six mammals screened. In contrast, the analogous region derived from alpha 2 was found in all the screened mammals. Most conserved was the region derived from alpha 3, which was found in all the screened mammals as well as in chickens, catfish, dogfish, and sea slugs. Conservation of the region from alpha 3 suggests functional significance and implies that strong selective pressures have discouraged mutational change. Results from the immunoblots further suggest that isoforms are present in all vertebrates.
44
Biswas, Nilormi, Arjun Dey, Saugata Kundu, Himel Chakraborty, and Anoop K. Mukhopadhyay. "Mechanical Properties of Enamel Nanocomposite." ISRN Biomaterials 2013 (April 9, 2013): 1–15. http://dx.doi.org/10.5402/2013/253761.
Анотація:
For adult Indian premolar teeth, we report for the first time ever the simultaneous evaluations of nanohardness, Young's modulus, and fracture toughness of the enamel nanocomposite. The nanohardness and Young's moduli were evaluated from near the beginning of the middle enamel region to within ~10 μm of the dentino-enamel junction (DEJ) and in the dentin region using the nanoindentation technique. The fracture toughness from near the middle of the enamel region to near the DEJ zone was measured using the microindentation technique. The deformation was studied using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The relative differences in the extents of biomineralization in the enamel and dentin regions were studied by the energy dispersive X-ray (EDS) technique. The variations of the toughness of the enamel as a function of the toughness of the protein matrix phase have been analyzed which showed that the predicted value of the toughness of the protein present in the nanocomposite was comparable to that of other bioproteins reported in the literature. Further, the work of fracture estimated from the measured value of toughness of the enamel nanocomposite agreed well with the experimental data reported in the literature.
45
Gomes-Fernandes, R., B. Ganapathisubramani, and J. C. Vassilicos. "The energy cascade in near-field non-homogeneous non-isotropic turbulence." Journal of Fluid Mechanics 771 (April 23, 2015): 676–705. http://dx.doi.org/10.1017/jfm.2015.201.
Анотація:
We perform particle image velocimetry (PIV) measurements of various terms of the non-homogeneous Kármán–Howarth–Monin equation in the most inhomogeneous and anisotropic region of grid-generated turbulence, the production region which lies between the grid and the peak of turbulence intensity. We use a well-documented fractal grid which is known to magnify the streamwise extent of the production region and abate its turbulence activity. On the centreline around the centre of that region the two-point advection and transport terms are dominant and the production is significant too. It is therefore impossible to apply usual Kolmogorov arguments based on the Kármán–Howarth–Monin equation and resulting dimensional considerations to deduce interscale flux and spectral properties. The interscale energy transfers at this location turn out to be highly anisotropic and consist of a combined forward and inverse cascade in different directions which, when averaged over directions, gives an interscale energy flux that is negative (hence forward cascade on average) and not too far from linear in $r$, the modulus of the separation vector $\boldsymbol{r}$ between two points. The energy spectrum of the streamwise fluctuating component exhibits a well-defined $-5/3$ power law over one decade, even though the streamwise direction is at a small angle to the inverse cascading direction.
46
Reeves, James B. "Near versus Mid-Infrared Spectroscopy for Quantitative Analysis of Chlorite Treated Forages and By-Products." Journal of Near Infrared Spectroscopy 2, no. 3 (June 1994): 153–62. http://dx.doi.org/10.1255/jnirs.42.
Анотація:
The objective of this work was to explore the relative merits of near and mid-infrared diffuse reflectance spectroscopy in determining the composition of sodium chlorite treated forages and by-products. Sixteen feed-stuffs (174 total samples treated at one of 11 levels of sodium chlorite, 0 to 0.394 g per gram of feedstuff) were examined in the near and mid-infrared spectral regions using diffuse reflectance on a Fourier transform spectrometer, and in the near infrared region using a grating monochromator. Samples were scanned as is and as 5% sample in KBr on the Fourier spectrometer and as is on the grating monochromator. Samples were analysed chemically and spectroscopically for neutral and acid detergent fibre, in vitro digestibility, permanganate lignin, crude protein and lignin nitrobenzene oxidation products. Results showed that diffuse mid-infrared reflectance spectroscopy can perform as well as, and sometimes better than, diffuse near infrared reflectance spectroscopy in determining the composition of chlorite-treated forages and by-products. In addition, Fourier near infrared spectroscopy did not perform as well as either near infrared using a grating monochromator or the Fourier mid-infrared spectrometer. Finally, diluting samples with KBr was often beneficial for mid-infrared based determinations.
47
Kaushik, Ajay, S. Indu, and Daya Gupta. "Adaptive Mobile Sink for Energy Efficient WSN Using Biogeography-Based Optimization." International Journal of Mobile Computing and Multimedia Communications 10, no. 3 (July 2019): 1–22. http://dx.doi.org/10.4018/ijmcmc.2019070101.
Анотація:
Early death of cluster heads (CHs) located near the sink due to excessive data relay load causes energy holes in wireless sensor networks (WSNs). A widely adopted solution to energy hole problem is to divide the deployment region into multiple sub regions and use mobile sink (MS) to aggregate data from each sub-region. However, inside a sub-region, CHs close to MS dissipate their energy quickly and die despite of the sink mobility. The authors map the problem of distributing data relay load optimally to multiple CHs and locating MS near these multiple CHs using metaheuristic algorithm biogeography-based optimization (BBO). Furthermore, there is a need of optimum routing of data to the MS inside each sub-region of a MS WSN. Proposed mobile sink distributed load routing algorithm (MSDR-BBO) selects the optimum routing CHs in MS WSN as per data transfer requirements of sensor nodes (SNs) and CHs. MSDR-BBO is validated using Matlab simulation as well as Netsim emulator, and it outperforms latest MS WSN algorithms like nested routing, SENMA, and CMS2TO by 4.6%, 11.7%, and 17.4%, respectively.
48
Gennari, Fulvia, Milica Sekulić, Tanja Barudžija, Željka Antić, Miroslav D. Dramićanin, and Alessandra Toncelli. "Infrared Photoluminescence of Nd-Doped Sesquioxide and Fluoride Nanocrystals: A Comparative Study." Crystals 12, no. 8 (July 31, 2022): 1071. http://dx.doi.org/10.3390/cryst12081071.
Анотація:
Lanthanide ions possess various emission channels in the near-infrared region that are well known in bulk crystals but are far less studied in samples with nanometric size. In this work, we present the infrared spectroscopic characterization of various Nd-doped fluoride and sesquioxide nanocrystals, namely Nd:Y2O3, Nd:Lu2O3, Nd:Sc2O3, Nd:YF3, and Nd:LuF3. Emissions from the three main emission bands in the near-infrared region have been observed and the emission cross-sections have been calculated. Moreover, another decay channel at around 2 μm has been observed and ascribed to the 4F3/2→4I15/2 transition. The lifetime of the 4F3/2 level has been measured under LED pumping. Emission cross-sections for the various compounds are calculated in the 1 μm, 900 nm, and 1.3 μm regions and are of the order of 10−20 cm2 in agreement with the literature results. Those in the 2 μm region are of the order of 10−21 cm2.
49
Chandra, V., P. W. M. W. M. Corbett, S. Geiger, and H. Hamdi. "Improving Reservoir Characterization and Simulation With Near-Wellbore Modeling." SPE Reservoir Evaluation & Engineering 16, no. 02 (April 3, 2013): 183–93. http://dx.doi.org/10.2118/148104-pa.
Анотація:
Summary New reservoir characterization methods are needed to integrate multiscale exploration and development data, particularly at the interface between well and field models. In this paper, we illustrate a novel workflow involving high-resolution near-wellbore modeling (NWM), which allows us to accurately include seismic, wireline data, image logs, and well core logs from highly heterogeneous reservoirs in field-scale reservoir simulations. We demonstrate that an NWM-enhanced geoengineering workflow has the potential to improve reservoir characterization by applying it to a realistic clastic reservoir with high variance at small scale. We have performed a number of sensitivities comparing conventional local grid refinement (LGR) in the near-wellbore region with that involving NWM, and we obtained a significant increase in the accuracy of reservoir characterization and the calibration of dynamic models. Centimeter-scale models, containing several million cells, representing the fine geological details of the near-wellbore region, were constructed with available data from core and openhole well-log suits. The resulting well models were upscaled into regular grids with the highest resolution possible through the NWM software and incorporated into a field-scale simulation model to evaluate the dynamic behavior of the reservoir with a static-model transient test. Our results show that the use of NWM tools for reservoir modeling yields more precise flow calculations and improves our fundamental understanding of the interactions between the reservoir and the wellbore.
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Bučík, R., U. Mall, A. Korth, and G. M. Mason. "On acceleration of <1 MeV/n He ions in the corotating compression regions near 1 AU: STEREO observations." Annales Geophysicae 27, no. 9 (September 30, 2009): 3677–90. http://dx.doi.org/10.5194/angeo-27-3677-2009.
Анотація:
Abstract. Observations of multi-MeV corotating interaction region (CIR) ions are in general consistent with models of CIR shock acceleration and transport. The presence of suprathermal particles near 1 AU in unshocked compression regions is not adequately explained. Nonetheless, more recent works demonstrate that unshocked compression regions associated with CIRs near 1 AU could energize particles. In the energy range from ~0.1 to ~1 MeV/n we investigate CIR events observed in 2007–2008 by the STEREO A and B spacecraft. We treat the predictions of compression acceleration by comparing the observed ion intensities with the model parameters. These observations show that the ion intensity in CIR events with in-situ reverse shock is well organized by the parameters which characterize the compression region itself, like compression width, solar wind speed gradients and the total pressure. In turn, for CIR events with the absence of the shocks the model predictions are not fulfilled.