We show how to combine in a natural way(i.e.,without any test nor switch)the conservative and non-conservative formulations of an hyperbolic system that has a conservative form.This is inspired from two different clas...We show how to combine in a natural way(i.e.,without any test nor switch)the conservative and non-conservative formulations of an hyperbolic system that has a conservative form.This is inspired from two different classes of schemes:the residual distribution one(Abgrall in Commun Appl Math Comput 2(3):341–368,2020),and the active flux formulations(Eyman and Roe in 49th AIAA Aerospace Science Meeting,2011;Eyman in active flux.PhD thesis,University of Michigan,2013;Helzel et al.in J Sci Comput 80(3):35–61,2019;Barsukow in J Sci Comput 86(1):paper No.3,34,2021;Roe in J Sci Comput 73:1094–1114,2017).The solution is globally continuous,and as in the active flux method,described by a combination of point values and average values.Unlike the“classical”active flux methods,the meaning of the point-wise and cell average degrees of freedom is different,and hence follow different forms of PDEs;it is a conservative version of the cell average,and a possibly non-conservative one for the points.This new class of scheme is proved to satisfy a Lax-Wendroff-like theorem.We also develop a method to perform nonlinear stability.We illustrate the behaviour on several benchmarks,some quite challenging.展开更多
In this paper,we discuss the notion of discrete conservation for hyperbolic conservation laws.We introduce what we call fluctuation splitting schemes(or residual distribution,also RDS)and show through several examples...In this paper,we discuss the notion of discrete conservation for hyperbolic conservation laws.We introduce what we call fluctuation splitting schemes(or residual distribution,also RDS)and show through several examples how these schemes lead to new developments.In particular,we show that most,if not all,known schemes can be rephrased in flux form and also how to satisfy additional conservation laws.This review paper is built on Abgrall et al.(Computers and Fluids 169:10-22,2018),Abgrall and Tokareva(SIAM SISC 39(5):A2345-A2364,2017),Abgrall(J Sci Comput 73:461-494,2017),Abgrall(Methods Appl Math 18(3):327-351,2018a)and Abgrall(J Comput Phys 372,640--666,2018b).This paper is also a direct consequence of the work of Roe,in particular Deconinck et al.(Comput Fluids 22(2/3):215-222,1993)and Roe(J Comput Phys 43:357-372,1981)where the notion of conservation was first introduced.In[26],Roe mentioned the Hermes project and the role of Dassault Aviation.Bruno Stoufflet,Vice President R&D and advanced business of this company,proposed me to have a detailed look at Deconinck et al.(Comput Fluids 22(2/3):215-222,1993).To be honest,at the time,I did not understand anything,and this was the case for several years.I was lucky to work with Katherine Mer,who at the time was a postdoc,and is now research engineer at CEA.She helped me a lot in understanding the notion of conservation.The present contribution can be seen as the result of my understanding after many years of playing around with the notion of residual distribution schemes(or fluctuation-splitting schemes)introduced by Roe.展开更多
Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results a...Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results are acquired. The truncation level adopted in probabilistic seismic hazard analysis （PSHA） should be determined by an aleatory uncertainty model （i.e., distribution model） of ground motions and the possible maximum and minimum ground motion values of a specific earthquake. However, at the present time, it is impossible to establish the upper bound model for ground motions based on the source characteristics and/or ground motion propagation. McGuire suggested a truncation level be fixed at a number of = 6, or the distribution of residuals be truncated in such a manner that site intensity cannot be greater than the epicenter intensity. This study aims to find a reasonable and feasible truncation level to be used in PSHA when the physical mechanism is not available to find the extreme ground motion. A mathematical analysis of the influence of the truncation level on PSHA, case studies of sites in different seismotectonic settings, and a distribution analysis of ground motion residuals are conducted in this study. It is concluded that = 4 is the minimum acceptable value for engineering applications for APEs within 0.002 to 10-4, and for low APEs, such as 10-5 and 10-6, the value of should be no less than 5 in most regions of China.展开更多
In this paper,we reformulate the piecewise linear discontinuous Galerkin(DG)method for solving two dimensional steady state scalar conservation laws in the framework of residual distribution(RD)schemes.This allows us ...In this paper,we reformulate the piecewise linear discontinuous Galerkin(DG)method for solving two dimensional steady state scalar conservation laws in the framework of residual distribution(RD)schemes.This allows us to propose a new class of nonlinear stabilization that does not destroy the formal accuracy of the schemes.Numerical results are shown to demonstrate the behavior of this approach.展开更多
In this paper,we describe a residual distribution(RD)method where,contrarily to“standard”this type schemes,the mesh is not necessarily conformal.It also allows to use discontinuous elements,contrarily to the“stand...In this paper,we describe a residual distribution(RD)method where,contrarily to“standard”this type schemes,the mesh is not necessarily conformal.It also allows to use discontinuous elements,contrarily to the“standard”case where continuous elements are requested.Moreover,if continuity is forced,the scheme is similar to the standard RD case.Hence,the situation becomes comparable with the Discontinuous Galerkin(DG)method,but it is simpler to implement than DG and has guaranteed L^(∞)bounds.We focus on the second-order case,but the method can be easily generalized to higher degree polynomials.展开更多
Amulti-dimensionally upwind conservative ResidualDistribution algorithm for simulating viscous axisymmetric hypersonic flows in thermo-chemical nonequilibrium on unstructured grids is presented and validated in the ca...Amulti-dimensionally upwind conservative ResidualDistribution algorithm for simulating viscous axisymmetric hypersonic flows in thermo-chemical nonequilibrium on unstructured grids is presented and validated in the case of the complex flowfield over a double cone configuration.The resulting numerical discretization combines a state-of-the-art nonlinear quasi-monotone second order blended scheme for distributing the convective residual and a standard Galerkin formulation for the diffusive residual.The physical source terms are upwinded together with the convective fluxes.Numerical results show an excellent agreement with experimental measurements and available literature.展开更多
We describe and review non oscillatory residual distribution schemes that are rather natural extension of high order finite volume schemes when a special emphasis is put on the structure of the computational stencil.W...We describe and review non oscillatory residual distribution schemes that are rather natural extension of high order finite volume schemes when a special emphasis is put on the structure of the computational stencil.We provide their connections with standard stabilized finite element and discontinuous Galerkin schemes,show that their are really non oscillatory.We also discuss the extension to these methods to parabolic problems.We also draw some research perspectives.展开更多
Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide e...Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide enough range but its resolution is limited, particularly for reservoirs with complex oil and water distribution or complicated structure. In this study, we attempt to accurately locate the 3-D reservoir water and oil distribution by combining borehole-surface and crosswell electric potentials. First, the distributions of oil and water in both vertical and horizontal directions are detected by the borehole-surface and erosswell electric potential methods, respectively, and then the measured crosswell potential result is used to calibrate the measured borehole-surface electric potential data to improve vertical resolution so that the residual oil distribution is determined in a lower half-space with three dimensions. The evaluation of residual oil distribution is obtained by investigation of differences between the simulation results of the reservoir with and without water flooding. The finite difference numerical simulation results prove that the spatial residual oil distribution can be effectively determined by combining the crosswell and borehole-surface electric potentials.展开更多
A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal resi...A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal residual stresses in medium thickness plate weldment is calculated and analyzed. A new method of calculating inherent strains and longitudinal residual stresses is proposed.展开更多
Researching residual oil distribution not only is a difficulty in the world, but also is the pioneering research subject in different fields such as geology, physical geography and reservoir engineering. The modem geo...Researching residual oil distribution not only is a difficulty in the world, but also is the pioneering research subject in different fields such as geology, physical geography and reservoir engineering. The modem geology technique, well logging technology and reservoir engineering technique develops rapidly, which provides favorable conditions for researching residual oil distribution.展开更多
Based on the field survey in Dongxiang Autonomous County of Gansu Province in 2017 and 2018,we found and obtained rich effective Dongxiang folk story resources.These first-hand story resources remain in relatively rem...Based on the field survey in Dongxiang Autonomous County of Gansu Province in 2017 and 2018,we found and obtained rich effective Dongxiang folk story resources.These first-hand story resources remain in relatively remote areas of the county,with elderly women in the Dongxiang Language Reservation Area in the central and east of the county as the main oral inheritance group.The distribution characteristics of folk stories:few people preserve most stories,while most people could not narrate complete stories,and few traditional story resources are widespread.At present,due to various reasons,the oral environment and inheritance status of folk stories in Dongxiang County is not optimistic,the survey is difficult,and the story resources are scattered,and there is a tendency to gradually disappear.Therefore,it is necessary to actively protect the existing Dongxiang folk artists and folk story resources,and to conduct digital sorting of these resources in time.展开更多
The spin distribution of the evaporation residue cross section of nuclei ^194pb, ^200Pb, ^206Pb, and ^200 Os are calculated via a Langevin equation coupled with a statistical decay model. It is shown that with increas...The spin distribution of the evaporation residue cross section of nuclei ^194pb, ^200Pb, ^206Pb, and ^200 Os are calculated via a Langevin equation coupled with a statistical decay model. It is shown that with increasing the neutronto-proton ratio （N/Z） of the system, the sensitivity of the significantly. Moreover, for ^200Os this spin distribution is no spin distribution to the nuclear dissipation is decreased longer sensitive to the nuclear dissipation. These results suggest that to obtain a more accurate pre-saddle viscosity coefficient through the measurement of the evaporation residue spin distribution, it is best to yield those compound systems with low N/Z.展开更多
The residual stress distribution was studied by an analytical model, due to shot peening on the welding carbon steel surface layer. The initial welding residual stresses before shot peening were taken into considerati...The residual stress distribution was studied by an analytical model, due to shot peening on the welding carbon steel surface layer. The initial welding residual stresses before shot peening were taken into consideration in this analytical model. The Hertzian elastic contact theory was used to get the elastic compression stress state after impact on the surface layer. The initial welding stress field and the shot peening stress field would superpose and the welding surface layer would yield based on the elastic-plastic evaluation, then the residual stress after shot peening can be achieved. The influence of initial welding residual stress on the stress distribution after shot peening was analyzed and discussed. A series of experiments were carried out and the residual stress on the welding surface was determined by X-ray diffractometer before and after shot peening. The calculation results of the analytical model are consistent with the experimental results. The critical shot velocities when welding surface layer yielded and reverse yielded were calculated. While the welded joint surface material reversely yielded, the maximum compressive residual stress would not obviously increase with the increase of shot velocity, the thickness of the compressive stress layer would be increased. Welding residual tensile stress can enlarge the thickness of the compressive stress layer at the same shot velocity when reverse yield appeared.展开更多
There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from th...There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.展开更多
In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research ...In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research about mathematical model for multi-strand tundish is few, and so far, there has been no acknowledged math model for multi- strand tundish to describe its flow characteristic. If Sahai＇s model, which is originally proposed for the case of single-strand tundish （proposed in reference, and this model is widely used in the world）, is applied to describe flow feature in multi-strand tundish, the calculation results would be unreasonable. Based on the data of watermodel experiment results, the sum of each strand＇s dead region＇s volume fraction is bigger than 100%, and this obviously doesn＇T agree with reality; and the value of dead region＇s volume fraction is calculated to be minus according to mathematical simulation results data in another case. What＇s more, Sahai＇s model does not propose the standard of plotting the RTD-curve, and this makes scholars around the world can＇t achieve consensus of views about plotting RTD-curve. And the model doesn＇t consider the bypass flow and can＇t calculate its volume fraction, but bypass flow is critical to tundish metallurgy. And through Sahai＇s model, the calculation result of plug flow region＇s volume fraction is also not reasonable, because the model doesn＇t well describe the essence of plug flow. So these suggest that it is not reliable to apply Sahai＇s single-strand tundish model to multi-strand tundish case. Then a new model is attempted to propose in this paper for your discussion. In the new model, the standard of plotting RTD curve is definitely proposed, and relative calculation method is also proposed; and the feature of dead region is carefully studied and the model proposes a new method to calculate its volume fraction, and the calculation formula about its volume fraction can be adjustable according the actual demand; what＇s more, the new model considers the bypass flow and proposes a method to calculate its volume fraction for the first time, and then volume fraction of plug flow region, backmix flow region, dead region and bypass flow can be calculated and obtained at the same time; and this new model can better capture the deviation of reality flow pattern from ideal plug flow pattern, and reflects the feature of plug flow.展开更多
Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different dis...Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state,oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency.Under bound water condition,crude oil mainly occurs in medium and large pores in the low-permeability sample,while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples.During the waterflooding,crude oil in the medium and large pores of the three types of samples are preferentially produced.With the decrease of permeability of the samples,the waterflooding front sequentially shows uniform displacement,network displacement and finger displacement,and correspondingly the oil recovery factors decrease successively.After waterflooding,the residual oil in low-permeability samples is mainly distributed in medium pores,and appears in membranous and angular dispersed phase;but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores,and appears in continuous phase formed by a bypass flow and dispersed phase.The low-permeability samples have higher and stable oil displacement efficiency,while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower,but increases to a certain extent with the increase of displacement pressure.展开更多
Using double eUipsoid heat source as inner heat source, a model of T-joint weldment of CLAW steel was established in order to analysis the temperature field, residual stress distribution and the angular deformation. A...Using double eUipsoid heat source as inner heat source, a model of T-joint weldment of CLAW steel was established in order to analysis the temperature field, residual stress distribution and the angular deformation. And the temperature- dependent properties of material were considered in this model. The results show that the temperature distribution changes with the movement of heat source, every node goes through two thermal cycles. And every curve has two peak values ; the first peak value is higher than the second one. The largest deformation appears at the weld toe.展开更多
This study investigated the bacterial regrowth in drinking water distribution systems receiving finished water from an advanced drinking water treatment plant in one city in southem China. Thirteen nodes in two water ...This study investigated the bacterial regrowth in drinking water distribution systems receiving finished water from an advanced drinking water treatment plant in one city in southem China. Thirteen nodes in two water supply zones with different aged pipelines were selected to monitor water temperature, dissolved oxygen （DO）, chloramine residual, assimilable organic carbon （AOC）, and heterotrophic plate counts （HPC）. Regression and principal component analyses indicated that HPC had a strong correlation with chloramine residual. Based on Chick-Watson＇s Law and the Monod equation, biostability curves under different conditions were developed to achieve the goal of HPC 100 CFU/mL. The biostability curves could interpret the scenario under various AOC concentrations and predict the required chloramine residual concentration under the condition of high AOC level. The simulation was also carded out to predict the scenario with a stricter HPC goal （≤50 CFU/mL） and determine the required chloramine residual. The biological regrowth control strategy was assessed using biostability curve analysis. The results indicated that maintaining high chloramine residual concentration was the most practical way to achieve the goal of HPC ≤ 100 CFU/mL. Biostability curves could be a very useful tool for biostability control in distribution systems. This work could provide some new insights towards biostability control in real distribution systems.展开更多
Impact of waste fuels（virgin/waste wood, mixed biofuel（peat, bark, wood chips） industrial,household, mixed waste fuel） and incineration technologies on partitioning and leaching behavior of trace elements has been...Impact of waste fuels（virgin/waste wood, mixed biofuel（peat, bark, wood chips） industrial,household, mixed waste fuel） and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr,As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature.Total concentration in ashes decreased in order of Zn 〉 Cu 〉 Pb 〉 Cr 〉 Sb 〉 As 〉 Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers（especially for biofuel incineration）. It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions.Concentration levels in ash and ash matrix properties（association of elements on ash particles）are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in 〉50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.展开更多
The Langevin equation including particle emission was used to reproduce the recently measured spin distribution of evaporation residue cross sections in the reaction ^16O＋^184W at beam energies of 84, 92, 100, 108, 1...The Langevin equation including particle emission was used to reproduce the recently measured spin distribution of evaporation residue cross sections in the reaction ^16O＋^184W at beam energies of 84, 92, 100, 108, 116 and 120 MeV. By comparing the theoretical calculations with the experimental data, the validity of the stochastic approach to dissipative fission is verified. Moreover, a pre-saddle nuclear viscosity coefficient of 5×10^21 s^-1 is extracted.展开更多
基金the author was partially funded by the SNF project 200020_175784.
文摘We show how to combine in a natural way(i.e.,without any test nor switch)the conservative and non-conservative formulations of an hyperbolic system that has a conservative form.This is inspired from two different classes of schemes:the residual distribution one(Abgrall in Commun Appl Math Comput 2(3):341–368,2020),and the active flux formulations(Eyman and Roe in 49th AIAA Aerospace Science Meeting,2011;Eyman in active flux.PhD thesis,University of Michigan,2013;Helzel et al.in J Sci Comput 80(3):35–61,2019;Barsukow in J Sci Comput 86(1):paper No.3,34,2021;Roe in J Sci Comput 73:1094–1114,2017).The solution is globally continuous,and as in the active flux method,described by a combination of point values and average values.Unlike the“classical”active flux methods,the meaning of the point-wise and cell average degrees of freedom is different,and hence follow different forms of PDEs;it is a conservative version of the cell average,and a possibly non-conservative one for the points.This new class of scheme is proved to satisfy a Lax-Wendroff-like theorem.We also develop a method to perform nonlinear stability.We illustrate the behaviour on several benchmarks,some quite challenging.
文摘In this paper,we discuss the notion of discrete conservation for hyperbolic conservation laws.We introduce what we call fluctuation splitting schemes(or residual distribution,also RDS)and show through several examples how these schemes lead to new developments.In particular,we show that most,if not all,known schemes can be rephrased in flux form and also how to satisfy additional conservation laws.This review paper is built on Abgrall et al.(Computers and Fluids 169:10-22,2018),Abgrall and Tokareva(SIAM SISC 39(5):A2345-A2364,2017),Abgrall(J Sci Comput 73:461-494,2017),Abgrall(Methods Appl Math 18(3):327-351,2018a)and Abgrall(J Comput Phys 372,640--666,2018b).This paper is also a direct consequence of the work of Roe,in particular Deconinck et al.(Comput Fluids 22(2/3):215-222,1993)and Roe(J Comput Phys 43:357-372,1981)where the notion of conservation was first introduced.In[26],Roe mentioned the Hermes project and the role of Dassault Aviation.Bruno Stoufflet,Vice President R&D and advanced business of this company,proposed me to have a detailed look at Deconinck et al.(Comput Fluids 22(2/3):215-222,1993).To be honest,at the time,I did not understand anything,and this was the case for several years.I was lucky to work with Katherine Mer,who at the time was a postdoc,and is now research engineer at CEA.She helped me a lot in understanding the notion of conservation.The present contribution can be seen as the result of my understanding after many years of playing around with the notion of residual distribution schemes(or fluctuation-splitting schemes)introduced by Roe.
基金Program of Seismic Ground Motion Parameter Zonation Map of Chinathe Basic Research Fund of the Institute of Geophysics Under Grant No.DQJB11C18the Special Funds for Science and Technology Research Under Grant No.200708003
文摘Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results are acquired. The truncation level adopted in probabilistic seismic hazard analysis （PSHA） should be determined by an aleatory uncertainty model （i.e., distribution model） of ground motions and the possible maximum and minimum ground motion values of a specific earthquake. However, at the present time, it is impossible to establish the upper bound model for ground motions based on the source characteristics and/or ground motion propagation. McGuire suggested a truncation level be fixed at a number of = 6, or the distribution of residuals be truncated in such a manner that site intensity cannot be greater than the epicenter intensity. This study aims to find a reasonable and feasible truncation level to be used in PSHA when the physical mechanism is not available to find the extreme ground motion. A mathematical analysis of the influence of the truncation level on PSHA, case studies of sites in different seismotectonic settings, and a distribution analysis of ground motion residuals are conducted in this study. It is concluded that = 4 is the minimum acceptable value for engineering applications for APEs within 0.002 to 10-4, and for low APEs, such as 10-5 and 10-6, the value of should be no less than 5 in most regions of China.
基金The first author was supported in part by the EU STREP ADIGMA and a CNES grantThis research was conducted in part during the second author’s visit in the INRIA project ScAlApplix in May 2006as an invited professor.The research of the second author was also supported in part by NSF grant DMS-0510345。
文摘In this paper,we reformulate the piecewise linear discontinuous Galerkin(DG)method for solving two dimensional steady state scalar conservation laws in the framework of residual distribution(RD)schemes.This allows us to propose a new class of nonlinear stabilization that does not destroy the formal accuracy of the schemes.Numerical results are shown to demonstrate the behavior of this approach.
基金This research has been done under a CNES grant,a FP6 STREP(ADIGMA,Contrat 30719)a FP7 ERC Advanced Grant(ADDECCO,contract 226316).
文摘In this paper,we describe a residual distribution(RD)method where,contrarily to“standard”this type schemes,the mesh is not necessarily conformal.It also allows to use discontinuous elements,contrarily to the“standard”case where continuous elements are requested.Moreover,if continuity is forced,the scheme is similar to the standard RD case.Hence,the situation becomes comparable with the Discontinuous Galerkin(DG)method,but it is simpler to implement than DG and has guaranteed L^(∞)bounds.We focus on the second-order case,but the method can be easily generalized to higher degree polynomials.
文摘Amulti-dimensionally upwind conservative ResidualDistribution algorithm for simulating viscous axisymmetric hypersonic flows in thermo-chemical nonequilibrium on unstructured grids is presented and validated in the case of the complex flowfield over a double cone configuration.The resulting numerical discretization combines a state-of-the-art nonlinear quasi-monotone second order blended scheme for distributing the convective residual and a standard Galerkin formulation for the diffusive residual.The physical source terms are upwinded together with the convective fluxes.Numerical results show an excellent agreement with experimental measurements and available literature.
基金The author has been supported by the FP7 Advanced Grant#226316“ADDECCO”.The help of Mario Richiuto(INRIA)and A.Larat(now CNRS researcher at Ecole Centrale de Paris,France)are warmly acknowledged.
文摘We describe and review non oscillatory residual distribution schemes that are rather natural extension of high order finite volume schemes when a special emphasis is put on the structure of the computational stencil.We provide their connections with standard stabilized finite element and discontinuous Galerkin schemes,show that their are really non oscillatory.We also discuss the extension to these methods to parabolic problems.We also draw some research perspectives.
文摘Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide enough range but its resolution is limited, particularly for reservoirs with complex oil and water distribution or complicated structure. In this study, we attempt to accurately locate the 3-D reservoir water and oil distribution by combining borehole-surface and crosswell electric potentials. First, the distributions of oil and water in both vertical and horizontal directions are detected by the borehole-surface and erosswell electric potential methods, respectively, and then the measured crosswell potential result is used to calibrate the measured borehole-surface electric potential data to improve vertical resolution so that the residual oil distribution is determined in a lower half-space with three dimensions. The evaluation of residual oil distribution is obtained by investigation of differences between the simulation results of the reservoir with and without water flooding. The finite difference numerical simulation results prove that the spatial residual oil distribution can be effectively determined by combining the crosswell and borehole-surface electric potentials.
文摘A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal residual stresses in medium thickness plate weldment is calculated and analyzed. A new method of calculating inherent strains and longitudinal residual stresses is proposed.
文摘Researching residual oil distribution not only is a difficulty in the world, but also is the pioneering research subject in different fields such as geology, physical geography and reservoir engineering. The modem geology technique, well logging technology and reservoir engineering technique develops rapidly, which provides favorable conditions for researching residual oil distribution.
基金Key Project of National Social Science Foundation of China"Type Analysis and Digital Study of Mongolian Ethnic Folk Stories"(16ZDA204).
文摘Based on the field survey in Dongxiang Autonomous County of Gansu Province in 2017 and 2018,we found and obtained rich effective Dongxiang folk story resources.These first-hand story resources remain in relatively remote areas of the county,with elderly women in the Dongxiang Language Reservation Area in the central and east of the county as the main oral inheritance group.The distribution characteristics of folk stories:few people preserve most stories,while most people could not narrate complete stories,and few traditional story resources are widespread.At present,due to various reasons,the oral environment and inheritance status of folk stories in Dongxiang County is not optimistic,the survey is difficult,and the story resources are scattered,and there is a tendency to gradually disappear.Therefore,it is necessary to actively protect the existing Dongxiang folk artists and folk story resources,and to conduct digital sorting of these resources in time.
基金National Natural Science Foundation of China under Grant No.10405007
文摘The spin distribution of the evaporation residue cross section of nuclei ^194pb, ^200Pb, ^206Pb, and ^200 Os are calculated via a Langevin equation coupled with a statistical decay model. It is shown that with increasing the neutronto-proton ratio （N/Z） of the system, the sensitivity of the significantly. Moreover, for ^200Os this spin distribution is no spin distribution to the nuclear dissipation is decreased longer sensitive to the nuclear dissipation. These results suggest that to obtain a more accurate pre-saddle viscosity coefficient through the measurement of the evaporation residue spin distribution, it is best to yield those compound systems with low N/Z.
基金Funded by the Fundamental Research Funds for the Central Universities(51271014)
文摘The residual stress distribution was studied by an analytical model, due to shot peening on the welding carbon steel surface layer. The initial welding residual stresses before shot peening were taken into consideration in this analytical model. The Hertzian elastic contact theory was used to get the elastic compression stress state after impact on the surface layer. The initial welding stress field and the shot peening stress field would superpose and the welding surface layer would yield based on the elastic-plastic evaluation, then the residual stress after shot peening can be achieved. The influence of initial welding residual stress on the stress distribution after shot peening was analyzed and discussed. A series of experiments were carried out and the residual stress on the welding surface was determined by X-ray diffractometer before and after shot peening. The calculation results of the analytical model are consistent with the experimental results. The critical shot velocities when welding surface layer yielded and reverse yielded were calculated. While the welded joint surface material reversely yielded, the maximum compressive residual stress would not obviously increase with the increase of shot velocity, the thickness of the compressive stress layer would be increased. Welding residual tensile stress can enlarge the thickness of the compressive stress layer at the same shot velocity when reverse yield appeared.
基金Project supported by the National Natural Science Foundation of China (No. 30472139)the Education Commission for the First Batch of Excellent Young Teachers in Universities of Chongqing City, China
文摘There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.
基金supported by the National Natural Science Foundation of China(No.60672145)
文摘In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research about mathematical model for multi-strand tundish is few, and so far, there has been no acknowledged math model for multi- strand tundish to describe its flow characteristic. If Sahai＇s model, which is originally proposed for the case of single-strand tundish （proposed in reference, and this model is widely used in the world）, is applied to describe flow feature in multi-strand tundish, the calculation results would be unreasonable. Based on the data of watermodel experiment results, the sum of each strand＇s dead region＇s volume fraction is bigger than 100%, and this obviously doesn＇T agree with reality; and the value of dead region＇s volume fraction is calculated to be minus according to mathematical simulation results data in another case. What＇s more, Sahai＇s model does not propose the standard of plotting the RTD-curve, and this makes scholars around the world can＇t achieve consensus of views about plotting RTD-curve. And the model doesn＇t consider the bypass flow and can＇t calculate its volume fraction, but bypass flow is critical to tundish metallurgy. And through Sahai＇s model, the calculation result of plug flow region＇s volume fraction is also not reasonable, because the model doesn＇t well describe the essence of plug flow. So these suggest that it is not reliable to apply Sahai＇s single-strand tundish model to multi-strand tundish case. Then a new model is attempted to propose in this paper for your discussion. In the new model, the standard of plotting RTD curve is definitely proposed, and relative calculation method is also proposed; and the feature of dead region is carefully studied and the model proposes a new method to calculate its volume fraction, and the calculation formula about its volume fraction can be adjustable according the actual demand; what＇s more, the new model considers the bypass flow and proposes a method to calculate its volume fraction for the first time, and then volume fraction of plug flow region, backmix flow region, dead region and bypass flow can be calculated and obtained at the same time; and this new model can better capture the deviation of reality flow pattern from ideal plug flow pattern, and reflects the feature of plug flow.
基金Supported by the National Natural Scienceof China(No.U19B2010)Youth Science and Technology Innovation Team of the Southwest Petroleum University(2018CXTD10)。
文摘Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state,oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency.Under bound water condition,crude oil mainly occurs in medium and large pores in the low-permeability sample,while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples.During the waterflooding,crude oil in the medium and large pores of the three types of samples are preferentially produced.With the decrease of permeability of the samples,the waterflooding front sequentially shows uniform displacement,network displacement and finger displacement,and correspondingly the oil recovery factors decrease successively.After waterflooding,the residual oil in low-permeability samples is mainly distributed in medium pores,and appears in membranous and angular dispersed phase;but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores,and appears in continuous phase formed by a bypass flow and dispersed phase.The low-permeability samples have higher and stable oil displacement efficiency,while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower,but increases to a certain extent with the increase of displacement pressure.
文摘Using double eUipsoid heat source as inner heat source, a model of T-joint weldment of CLAW steel was established in order to analysis the temperature field, residual stress distribution and the angular deformation. And the temperature- dependent properties of material were considered in this model. The results show that the temperature distribution changes with the movement of heat source, every node goes through two thermal cycles. And every curve has two peak values ; the first peak value is higher than the second one. The largest deformation appears at the weld toe.
基金supported by the National Water Special Program of China (No. 2009ZX07423-004)the High Technology Research and Development Program (863) of China (No. 2009AA06Z308)the International Science & Technology Cooperation Program of China (No. 2010DFA91830)
文摘This study investigated the bacterial regrowth in drinking water distribution systems receiving finished water from an advanced drinking water treatment plant in one city in southem China. Thirteen nodes in two water supply zones with different aged pipelines were selected to monitor water temperature, dissolved oxygen （DO）, chloramine residual, assimilable organic carbon （AOC）, and heterotrophic plate counts （HPC）. Regression and principal component analyses indicated that HPC had a strong correlation with chloramine residual. Based on Chick-Watson＇s Law and the Monod equation, biostability curves under different conditions were developed to achieve the goal of HPC 100 CFU/mL. The biostability curves could interpret the scenario under various AOC concentrations and predict the required chloramine residual concentration under the condition of high AOC level. The simulation was also carded out to predict the scenario with a stricter HPC goal （≤50 CFU/mL） and determine the required chloramine residual. The biological regrowth control strategy was assessed using biostability curve analysis. The results indicated that maintaining high chloramine residual concentration was the most practical way to achieve the goal of HPC ≤ 100 CFU/mL. Biostability curves could be a very useful tool for biostability control in distribution systems. This work could provide some new insights towards biostability control in real distribution systems.
基金Varmeforsk(Thermal Engineering Research Association)(Q4-251)is acknowledged for financial support to Mattias Backstrom.Anjali Bajwa is greatly acknowledged for assistance with grammatical and technical issues
文摘Impact of waste fuels（virgin/waste wood, mixed biofuel（peat, bark, wood chips） industrial,household, mixed waste fuel） and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr,As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature.Total concentration in ashes decreased in order of Zn 〉 Cu 〉 Pb 〉 Cr 〉 Sb 〉 As 〉 Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers（especially for biofuel incineration）. It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions.Concentration levels in ash and ash matrix properties（association of elements on ash particles）are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in 〉50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.
基金Supported by National Natural Science Foundation of China(10405007)
文摘The Langevin equation including particle emission was used to reproduce the recently measured spin distribution of evaporation residue cross sections in the reaction ^16O＋^184W at beam energies of 84, 92, 100, 108, 116 and 120 MeV. By comparing the theoretical calculations with the experimental data, the validity of the stochastic approach to dissipative fission is verified. Moreover, a pre-saddle nuclear viscosity coefficient of 5×10^21 s^-1 is extracted.
