The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-pha...The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.展开更多
The surface plasmon polaritons of the topological insulator Bi2Se3 can be excited by using etched grating or grave structures to compensate the wave vector mismatch of the incident photon and plasmon. Here, we demonst...The surface plasmon polaritons of the topological insulator Bi2Se3 can be excited by using etched grating or grave structures to compensate the wave vector mismatch of the incident photon and plasmon. Here, we demonstrate novel gold grating/Bi2Se3 thin film/sapphire hybrid structures, which allow the excitation of surface plasmon polaritons propagating through nondestructive Bi2Se3 thin film with the help of gold diffractive gratings. Utilizing periodic Au surface structures,the momentum can be matched and the normal-incidence infrared reflectance spectra exhibit pronounced dips. When the width of the gold grating W(with a periodicity 2 W) increases from 400 nm to 1500 nm, the resonant frequencies are tuned from about 7000 cm-1 to 2500 cm-1. In contrast to the expected ■ dispersion for both massive and massless fermions,where q ~π/W is the wave vector, we observe a sound-like linear dispersion even at room temperature. This surface plasmon polaritons with linear dispersion are attributed to the unique noninvasive fabrication method and high mobility of topological surface electrons. This novel structure provides a promising application of Dirac plasmonics.展开更多
This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commi...This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commissioned in 2006 to perform continuous measurements of meteorological and PV operational parameters. The test site is appropriately equipped to undertake such evaluations at a very high resolution (1 measurement per second). The perfromance results obtained for the two year evaluation period clearly show how each PV technology has performed under the climatological conditions in Cyprus. Finally the high average energy yield of the fixed plate systems under test, 1580 kWh/kWp and 1609 kWh/kWp during the first and second year of evaluation respectively, also verifies that solar energy is a very promising renewable source of energy for countries with a high solar resource.展开更多
The Limski kanal, a semi-closed inlet (channel-like bay) located on the western coast of Istria (Croatia), is an extraordinary sponge habitat. Research on the marine ecosystem has been conducted there for more than 10...The Limski kanal, a semi-closed inlet (channel-like bay) located on the western coast of Istria (Croatia), is an extraordinary sponge habitat. Research on the marine ecosystem has been conducted there for more than 100 years. Today, 42 valid Porifera species are described. 139 species are listed for the area around Rovinj and 159 species for the northern Adriatic Sea. While several scientists described the sponge fauna, information on the abiotic situation or an explanation for the diversity differences is missing. This study interprets physicochemical and ecological parameters including depth profiles (temperature, salinity, pH-value, oxygen, water current velocity, photosynthetically active radiation [PAR], water transparency and nutrients). Their variances are linked with the distribution patterns of the prevailing sponge fauna. The channel is characterised as predominantly marine habitat. Although a shallow sediment barrier and a headland reduce the impact of the northern Adriatic Sea, differences between the channel and the open sea seem to be limited. Compared to the more homogenous water body of the Adriatic sampling locations, the channel shows variations and gradients of ecological parameters between different locations (e.g., due to freshwater influx: nutrients, temperature, oxygen content, salinity and water current velocity) – this offering habitat diversity. The sponge fauna changes along those ecological gradients. It is dominated by the photophilic species Aplysina aerophoba and Chondrilla nucula, but sciaphilic species such as Dysidea avara, Axinella polypoides and Aplysina cavernicola can be found, too. Some specialised species (e.g., Geodia cydonium, Tethya aurantium) even populate the muddy bottom of the channel.展开更多
The U-Pb isotope compositions of rutile, om-phacite and garnet in the eclogite from the Jinheqiao area in the Southern Dabie ultrahigh-pressure metamorphic zonewere analyzed. The consistent high precision U-Pb age (21...The U-Pb isotope compositions of rutile, om-phacite and garnet in the eclogite from the Jinheqiao area in the Southern Dabie ultrahigh-pressure metamorphic zonewere analyzed. The consistent high precision U-Pb age (218± 1.2) Ma of rutile in eclogite from the Dabie Mountains was obtained by two ways of isochron and common Pb correction based on the composition of omphacite. This proves that the omphacite in eclogite has a U/Pb ratio (μ = 2.8) low enough to be used for common Pb correction in the analyses of rutile. Under the rapid cooling condition (40℃/Ma) the closure temperature for U-Pb diffusion in rutile is about 470℃. Thus, this U-Pb age of rutile proves that 218 Ma should be the cooling age of eclogite at 470℃ instead of the peak meta-morphic age.展开更多
Microlens array-based light-field imaging has been one of the most commonly used and effective technologies to record high-dimensional optical signals for developing various potential high-performance applications in ...Microlens array-based light-field imaging has been one of the most commonly used and effective technologies to record high-dimensional optical signals for developing various potential high-performance applications in many fields.However,the use of a microlens array generally suffers from an intrinsic trade-off between the spatial and angular resolutions.In this paper,we concentrate on exploiting a diffuser to explore a novel modality for light-field imaging.We demonstrate that the diffuser can efficiently angularly couple incident light rays into a detected image without needing any lens.To characterize and analyse this phenomenon,we establish a diffuser-encoding light-field transmission model,in which four-dimensional light fields are mapped into two-dimensional images via a transmission matrix describing the light propagation through the diffuser.Correspondingly,a calibration strategy is designed to flexibly determine the transmission matrix,so that light rays can be computationally decoupled from a detected image with adjustable spatio-angular resolutions,which are unshackled from the resolution limitation of the sensor.The proof-of-concept approach indicates the possibility of using scattering media for lensless four-dimensional light-field recording and processing,not just for two-or three-dimensional imaging.展开更多
A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The rel...A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The relevant optimization approach for hybrid elements andthe optimal parameter matching is suggested and applied to the 3-dimensional problem ofelasticity.展开更多
A numerical model for aluminum cloud combustion which includes the effects of interphase heat transfer,phase change,heterogeneous surface reactions,homogeneous combustion,oxide cap growth and radiation within the Eule...A numerical model for aluminum cloud combustion which includes the effects of interphase heat transfer,phase change,heterogeneous surface reactions,homogeneous combustion,oxide cap growth and radiation within the Euler–Lagrange framework is proposed.The model is validated in single particle configurations with varying particle diameters.The combustion process of a single aluminum particle is analyzed in detail and the particle consumption rates as well as the heat release rates due to the various physical/chemical sub-models are presented.The combustion time of single aluminum particles predicted by the model are in very good agreement with empirical correlations for particles with diameters larger than 10μm.The prediction error for smaller particles is noticeably reduced when using a heat transfer model that is capable of capturing the transition regime between continuum mechanics and molecular dynamics.The predictive capabilities of the proposed model framework are further evaluated by simulating the aluminum/air Bunsen flames of Mc Gill University for the first time.Results show that the predicted temperature distribution of the flame is consistent with the experimental data and the double-front structure of the Bunsen flame is reproduced well.The burning rates of aluminum in both single particle and particle cloud configurations are calculated and compared with empirical correlations.Results show that the burning rates obtained from the present model are more reasonable,while the correlations,when embedded in the Euler–Lagrange context,tend to underestimate the burning rate in the combustion stage,particularly for the considered fuel-rich flames.展开更多
In this work, the local fracture initiation behaviour of an Al2O3/6061Al composite is studied numerically. The damage behaviour of the microstructure is evaluated in consideration of the path and the amount of damage ...In this work, the local fracture initiation behaviour of an Al2O3/6061Al composite is studied numerically. The damage behaviour of the microstructure is evaluated in consideration of the path and the amount of damage as well as the stress-strain performance of the microstructure. The damage behaviour of the ductile matrix has been simulated using the damage parameter D. For the simulation of fracture of the ceramic particles, a normal stress criterion is applied. For the analysis of the damage behaviour of the transition zone between particulate and matrix, both damage models (D parameter and normal stress criteria) are applied in this region. Parameter studies of crack propagation prediction in the Al2O3/6061Al composite on the basis of an Element Elimination technique have been performed for two differently heat-treated variants resulting in different mechanical properties. In addition, residual stress effects on the damage behaviour are examined for various microstructural situations.展开更多
A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based ...A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based on the textural relations and compositions of minerals,especially of zoned garnet and potassic white mica,a P-T path was reconstructed using contoured P-T pseudosections.The U-Th-Pb dating of monazite in the micaschist was undertaken with the electron microprobe.The micaschist experienced P-T conditions along a clockwise path between 16 kbar at 510℃and 5 kbar at 555℃followed by isobaric heating to about 600℃.Monazite ages range between 315 and 480 Ma with the most prominent maxima and side maxima at 346.0±1.1(2σ),357.3±2.3,and 368.3±1.7 Ma.Ages older than 380 Ma were related to detrital monazite pointing to a Devonian sedimentary protolith.Other ages around 325 Ma were assigned to the isobaric heating by nearby post-tectonic granites.The high-pressure event,being the result of the collision of Laurussia and Gondwana after closure of the Rheic Ocean,occurred in the Late Devonian.The exhumation to 15-20 km(5 kbar)ended probably in the Early Carboniferous.The high-pressure micaschists from the Fichtelgebirge to the Erzgebirge crystalline complexes are suggested to represent a single nappe within a metamorphic nappe pile.This nappe is composed of metasedimentary slices,which experienced different peak pressures rather than representing a coherent crustal section.展开更多
Local Discontinuous Galerkin(LDG)schemes in the sense of[5]are a flexible numerical tool to approximate solutions of nonlinear convection problems with complicated dissipative terms.Such terms frequently appear in evo...Local Discontinuous Galerkin(LDG)schemes in the sense of[5]are a flexible numerical tool to approximate solutions of nonlinear convection problems with complicated dissipative terms.Such terms frequently appear in evolution equations which describe the dynamics of phase changes in e.g.liquid-vapour mixtures or in elastic solids.We report on results for one-dimensional model problems with dissipative terms including third-order and convolution operators.Cell entropy inequalities and L2-stability results are proved for those model problems.As is common in phase transition theory the solution structure sensitively depends on the coupling parameter between viscosity and capillarity.To avoid spurious solutions due to the counteracting effect of artificial dissipation by the numerical flux and the actual dissipation terms we introduce Tadmors’entropy conservative fluxes.Various numerical experiments underline the reliability of our approach and also illustrate interesting and(partly)new phase transition phenomena.展开更多
The scaffold pore size influences many critical physical aspects of tissue engineering,including tissue infiltration,biodegradation rate,and mechanical properties.Manual measurements of pore sizes from scanning electr...The scaffold pore size influences many critical physical aspects of tissue engineering,including tissue infiltration,biodegradation rate,and mechanical properties.Manual measurements of pore sizes from scanning electron micrographs using ImageJ/FIJI are commonly used to characterize scaffolds,but these methods are both time-consuming and subject to user bias.Current semi-automated analysis tools are limited by a lack of accessibility or limited sample size in their verification process.The work here describes the development of a new MATLAB algorithm,PoreScript,to address these limitations.The algorithm was verified using three common scaffold fabrication methods(e.g.,salt leaching,gas foaming,emulsion templating)with varying pore sizes and shapes to demonstrate the versatility of this new tool.Our results demonstrate that the pore size characterization using PoreScript is comparable to manual pore size measurements.The PoreScript algorithm was further evaluated to determine the effect of user-input and image parameters(relative image magnification,pixel intensity threshold,and pore structure).Overall,this work validates the accuracy of the PoreScript algorithm across several fabrication methods and provides user-guidance for semi-automated image analysis and increased throughput of scaffold characterization.展开更多
Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky...Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky's construction of monomial linearisation in his thesis and apply this to CU yielding a generalisation of Yan's coadjoint cluster representations. Then we give a complete classification of the resulting supercharacters,by describing the resulting orbits and determining the Hom-spaces between orbit modules.展开更多
In this paper we present the modelling of elastic intra-species electron-electron and inter-species electron-ion scattering in a plasma on the basis of the FokkerPlanck collision operator.Taking into account the equiv...In this paper we present the modelling of elastic intra-species electron-electron and inter-species electron-ion scattering in a plasma on the basis of the FokkerPlanck collision operator.Taking into account the equivalence of this operator with a stochastic differential equation,we propose a Particle-in-Cell based approach for the numerical solution of the Fokker-Planck collision term.As we will see,the introduced numerical concept allows the simulation of the collisional relaxation process in a fully self-consistent fashion.展开更多
文摘The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.
文摘The surface plasmon polaritons of the topological insulator Bi2Se3 can be excited by using etched grating or grave structures to compensate the wave vector mismatch of the incident photon and plasmon. Here, we demonstrate novel gold grating/Bi2Se3 thin film/sapphire hybrid structures, which allow the excitation of surface plasmon polaritons propagating through nondestructive Bi2Se3 thin film with the help of gold diffractive gratings. Utilizing periodic Au surface structures,the momentum can be matched and the normal-incidence infrared reflectance spectra exhibit pronounced dips. When the width of the gold grating W(with a periodicity 2 W) increases from 400 nm to 1500 nm, the resonant frequencies are tuned from about 7000 cm-1 to 2500 cm-1. In contrast to the expected ■ dispersion for both massive and massless fermions,where q ~π/W is the wave vector, we observe a sound-like linear dispersion even at room temperature. This surface plasmon polaritons with linear dispersion are attributed to the unique noninvasive fabrication method and high mobility of topological surface electrons. This novel structure provides a promising application of Dirac plasmonics.
文摘This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commissioned in 2006 to perform continuous measurements of meteorological and PV operational parameters. The test site is appropriately equipped to undertake such evaluations at a very high resolution (1 measurement per second). The perfromance results obtained for the two year evaluation period clearly show how each PV technology has performed under the climatological conditions in Cyprus. Finally the high average energy yield of the fixed plate systems under test, 1580 kWh/kWp and 1609 kWh/kWp during the first and second year of evaluation respectively, also verifies that solar energy is a very promising renewable source of energy for countries with a high solar resource.
基金part of the BIOTECmarin project supported by the Federal Ministry of Education and Research(BMBF,03F0414D)and the Universitat Stuttgart
文摘The Limski kanal, a semi-closed inlet (channel-like bay) located on the western coast of Istria (Croatia), is an extraordinary sponge habitat. Research on the marine ecosystem has been conducted there for more than 100 years. Today, 42 valid Porifera species are described. 139 species are listed for the area around Rovinj and 159 species for the northern Adriatic Sea. While several scientists described the sponge fauna, information on the abiotic situation or an explanation for the diversity differences is missing. This study interprets physicochemical and ecological parameters including depth profiles (temperature, salinity, pH-value, oxygen, water current velocity, photosynthetically active radiation [PAR], water transparency and nutrients). Their variances are linked with the distribution patterns of the prevailing sponge fauna. The channel is characterised as predominantly marine habitat. Although a shallow sediment barrier and a headland reduce the impact of the northern Adriatic Sea, differences between the channel and the open sea seem to be limited. Compared to the more homogenous water body of the Adriatic sampling locations, the channel shows variations and gradients of ecological parameters between different locations (e.g., due to freshwater influx: nutrients, temperature, oxygen content, salinity and water current velocity) – this offering habitat diversity. The sponge fauna changes along those ecological gradients. It is dominated by the photophilic species Aplysina aerophoba and Chondrilla nucula, but sciaphilic species such as Dysidea avara, Axinella polypoides and Aplysina cavernicola can be found, too. Some specialised species (e.g., Geodia cydonium, Tethya aurantium) even populate the muddy bottom of the channel.
基金This work was supportedby the State Key Basic Research Development Program (Grant No. G1999075503) the National Natural Science Foundation of China (Grant No. 49973020).
文摘The U-Pb isotope compositions of rutile, om-phacite and garnet in the eclogite from the Jinheqiao area in the Southern Dabie ultrahigh-pressure metamorphic zonewere analyzed. The consistent high precision U-Pb age (218± 1.2) Ma of rutile in eclogite from the Dabie Mountains was obtained by two ways of isochron and common Pb correction based on the composition of omphacite. This proves that the omphacite in eclogite has a U/Pb ratio (μ = 2.8) low enough to be used for common Pb correction in the analyses of rutile. Under the rapid cooling condition (40℃/Ma) the closure temperature for U-Pb diffusion in rutile is about 470℃. Thus, this U-Pb age of rutile proves that 218 Ma should be the cooling age of eclogite at 470℃ instead of the peak meta-morphic age.
基金supported by the National Natural Science Foundation of China under grants 11804231 and 61875137the Sino-German Center for Research Promotion under grants GZ 1391 and M-0044the Natural Science Foundation of Guangdong Province under grant 2018A030313831.
文摘Microlens array-based light-field imaging has been one of the most commonly used and effective technologies to record high-dimensional optical signals for developing various potential high-performance applications in many fields.However,the use of a microlens array generally suffers from an intrinsic trade-off between the spatial and angular resolutions.In this paper,we concentrate on exploiting a diffuser to explore a novel modality for light-field imaging.We demonstrate that the diffuser can efficiently angularly couple incident light rays into a detected image without needing any lens.To characterize and analyse this phenomenon,we establish a diffuser-encoding light-field transmission model,in which four-dimensional light fields are mapped into two-dimensional images via a transmission matrix describing the light propagation through the diffuser.Correspondingly,a calibration strategy is designed to flexibly determine the transmission matrix,so that light rays can be computationally decoupled from a detected image with adjustable spatio-angular resolutions,which are unshackled from the resolution limitation of the sensor.The proof-of-concept approach indicates the possibility of using scattering media for lensless four-dimensional light-field recording and processing,not just for two-or three-dimensional imaging.
基金The work was undertaken with the support of the Alexader von Humboldt Foundation.
文摘A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The relevant optimization approach for hybrid elements andthe optimal parameter matching is suggested and applied to the 3-dimensional problem ofelasticity.
基金supported by the National Natural Science Foundation of China(No.51706241)Hunan Provincial Natural Science Foundation of China(Nos.2020JJ4665 and 2021JJ30775)+1 种基金Hunan Provincial Innovation Foundation for Postgraduate,China(No.CX2019-0050)support provided by China Scholarship Council(No.201903170201)。
文摘A numerical model for aluminum cloud combustion which includes the effects of interphase heat transfer,phase change,heterogeneous surface reactions,homogeneous combustion,oxide cap growth and radiation within the Euler–Lagrange framework is proposed.The model is validated in single particle configurations with varying particle diameters.The combustion process of a single aluminum particle is analyzed in detail and the particle consumption rates as well as the heat release rates due to the various physical/chemical sub-models are presented.The combustion time of single aluminum particles predicted by the model are in very good agreement with empirical correlations for particles with diameters larger than 10μm.The prediction error for smaller particles is noticeably reduced when using a heat transfer model that is capable of capturing the transition regime between continuum mechanics and molecular dynamics.The predictive capabilities of the proposed model framework are further evaluated by simulating the aluminum/air Bunsen flames of Mc Gill University for the first time.Results show that the predicted temperature distribution of the flame is consistent with the experimental data and the double-front structure of the Bunsen flame is reproduced well.The burning rates of aluminum in both single particle and particle cloud configurations are calculated and compared with empirical correlations.Results show that the burning rates obtained from the present model are more reasonable,while the correlations,when embedded in the Euler–Lagrange context,tend to underestimate the burning rate in the combustion stage,particularly for the considered fuel-rich flames.
基金the financial support from German Research Foundation(DFG),under project Schm 746/55-1
文摘In this work, the local fracture initiation behaviour of an Al2O3/6061Al composite is studied numerically. The damage behaviour of the microstructure is evaluated in consideration of the path and the amount of damage as well as the stress-strain performance of the microstructure. The damage behaviour of the ductile matrix has been simulated using the damage parameter D. For the simulation of fracture of the ceramic particles, a normal stress criterion is applied. For the analysis of the damage behaviour of the transition zone between particulate and matrix, both damage models (D parameter and normal stress criteria) are applied in this region. Parameter studies of crack propagation prediction in the Al2O3/6061Al composite on the basis of an Element Elimination technique have been performed for two differently heat-treated variants resulting in different mechanical properties. In addition, residual stress effects on the damage behaviour are examined for various microstructural situations.
文摘A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based on the textural relations and compositions of minerals,especially of zoned garnet and potassic white mica,a P-T path was reconstructed using contoured P-T pseudosections.The U-Th-Pb dating of monazite in the micaschist was undertaken with the electron microprobe.The micaschist experienced P-T conditions along a clockwise path between 16 kbar at 510℃and 5 kbar at 555℃followed by isobaric heating to about 600℃.Monazite ages range between 315 and 480 Ma with the most prominent maxima and side maxima at 346.0±1.1(2σ),357.3±2.3,and 368.3±1.7 Ma.Ages older than 380 Ma were related to detrital monazite pointing to a Devonian sedimentary protolith.Other ages around 325 Ma were assigned to the isobaric heating by nearby post-tectonic granites.The high-pressure event,being the result of the collision of Laurussia and Gondwana after closure of the Rheic Ocean,occurred in the Late Devonian.The exhumation to 15-20 km(5 kbar)ended probably in the Early Carboniferous.The high-pressure micaschists from the Fichtelgebirge to the Erzgebirge crystalline complexes are suggested to represent a single nappe within a metamorphic nappe pile.This nappe is composed of metasedimentary slices,which experienced different peak pressures rather than representing a coherent crustal section.
文摘Local Discontinuous Galerkin(LDG)schemes in the sense of[5]are a flexible numerical tool to approximate solutions of nonlinear convection problems with complicated dissipative terms.Such terms frequently appear in evolution equations which describe the dynamics of phase changes in e.g.liquid-vapour mixtures or in elastic solids.We report on results for one-dimensional model problems with dissipative terms including third-order and convolution operators.Cell entropy inequalities and L2-stability results are proved for those model problems.As is common in phase transition theory the solution structure sensitively depends on the coupling parameter between viscosity and capillarity.To avoid spurious solutions due to the counteracting effect of artificial dissipation by the numerical flux and the actual dissipation terms we introduce Tadmors’entropy conservative fluxes.Various numerical experiments underline the reliability of our approach and also illustrate interesting and(partly)new phase transition phenomena.
基金The authors would like to acknowledge the following funding support:National Institutes of Health[NIH-R21 AR076708]National Science Foundation[NSF-BSF 1822196,DGE-1610403].
文摘The scaffold pore size influences many critical physical aspects of tissue engineering,including tissue infiltration,biodegradation rate,and mechanical properties.Manual measurements of pore sizes from scanning electron micrographs using ImageJ/FIJI are commonly used to characterize scaffolds,but these methods are both time-consuming and subject to user bias.Current semi-automated analysis tools are limited by a lack of accessibility or limited sample size in their verification process.The work here describes the development of a new MATLAB algorithm,PoreScript,to address these limitations.The algorithm was verified using three common scaffold fabrication methods(e.g.,salt leaching,gas foaming,emulsion templating)with varying pore sizes and shapes to demonstrate the versatility of this new tool.Our results demonstrate that the pore size characterization using PoreScript is comparable to manual pore size measurements.The PoreScript algorithm was further evaluated to determine the effect of user-input and image parameters(relative image magnification,pixel intensity threshold,and pore structure).Overall,this work validates the accuracy of the PoreScript algorithm across several fabrication methods and provides user-guidance for semi-automated image analysis and increased throughput of scaffold characterization.
基金supported by National Natural Science Foundation of China(Grant No.11601338)the German Research Foundation,Priority Programme Deutsche ForschungsgemeinschaftSchwerpunktsprogramm Darstellungstheorie 1388 in Representation Theory(Grant No.99028426)
文摘Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky's construction of monomial linearisation in his thesis and apply this to CU yielding a generalisation of Yan's coadjoint cluster representations. Then we give a complete classification of the resulting supercharacters,by describing the resulting orbits and determining the Hom-spaces between orbit modules.
文摘In this paper we present the modelling of elastic intra-species electron-electron and inter-species electron-ion scattering in a plasma on the basis of the FokkerPlanck collision operator.Taking into account the equivalence of this operator with a stochastic differential equation,we propose a Particle-in-Cell based approach for the numerical solution of the Fokker-Planck collision term.As we will see,the introduced numerical concept allows the simulation of the collisional relaxation process in a fully self-consistent fashion.