Ultrahigh-pressure metamorphism has recently been reported from various crustal rocks in the Seve Nappe Complex(SNC)in which microdiamonds were found.However,in gneiss from the Lower Seve Nappe(LSN),neither any direct...Ultrahigh-pressure metamorphism has recently been reported from various crustal rocks in the Seve Nappe Complex(SNC)in which microdiamonds were found.However,in gneiss from the Lower Seve Nappe(LSN),neither any direct petrographic indication for UHP was reported nor the metamorphic evolution was well constrained.We studied a mylonitic gneiss from the Handol area of the LSN and applied phase-diagram modeling and Ti-in-biotite thermometry.Based on the compositions of garnet and biotite and observed mineral assemblages,a path was reconstructed passing through about 8 kbar and 730℃at prograde metamorphism.Peak-pressure and initial retrograde stages occurred at 9.0–10.2 kbar at 745-775℃,and 7–9 kbar at<750℃,respectively.No ultrahigh-pressure evidence was recognized compatible with medium-pressure metamorphism deduced in earlier studies of gneiss from the SNC.As higher peak pressures were reported recently for metamorphic rocks of the LSN,a possible interpretation is that slices or erased blocks were subducted,metamorphosed at different depths,and exhumed in a subduction channel.However,the dominant gneiss of the SNC experienced only a medium-pressure metamorphism in the upper part of the downgoing Baltica Plate.Rocks from different depth levels were brought together in an exhumation channel located between Baltica and the overlying plate.展开更多
The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work D...The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work Directive (WFD).One of the tools supporting the development of sustainable river management is physi- cal habitat modeling,e.g.,for fish,because fish population are one of the most important indicators for the e- colngical integrity of rivers.Within physical habitat models hydromorphological ...展开更多
Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.Th...Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.This way,a density fluctuation spectrum is measured.However,the correspondence between fluctuation power and scattered microwave power is strongly nonlinear.Studying these processes numerically therefore requires fullwave simulations(IPF-FD3 D),with density fluctuations supplied by a separate plasma turbulence code(GENE).Earlier such attempts suffered from the low number of data points in the‘interesting’part of the spectrum,where a power law had to be fitted to 4 or 5 points.This has been overcome with recent simulations,which now show a much better agreement with experimental data.展开更多
As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of ...As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces. This mechanism operates in narrow, roughly half-filled superconducting bands of special symmetry and is evidently responsible for the formation of Cooper pairs in all superconductors. Here we consider this new mechanism within an outer magnetic field. We show that in the magnetic field the constraining forces produce Cooper pairs of non-vanishing total momentum with the consequence that an electric current flows within the superconductor. This current satisfies the London equations and, consequently, leads to the Meissner effect. This theoretical result is confirmed by the experimental observation that all superconductors, whether conventional or unconventional, exhibit the Meissner effect.展开更多
Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients duri...Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients during heat wave propagation,etc.A drawback of many present-day systems is that they use a fixed frequency difference between the probing frequencies.Hence,although the central probing frequency can be varied,the probing frequency difference is usually fixed.The new design presented in this work uses an advanced microwave generation and detection scheme,which allows for arbitrary probing frequencies and probing frequency separations.展开更多
In recent years, modelling crowd and evacuation dynamics has become very important, with increasing huge numbers of people gathering around the world for many reasons and events. The fact that our global population gr...In recent years, modelling crowd and evacuation dynamics has become very important, with increasing huge numbers of people gathering around the world for many reasons and events. The fact that our global population grows dramatically every year and the current public transport systems are able to transport large amounts of people heightens the risk of crowd panic or crush. Pedestrian models are based on macroscopic or microscopic behaviour. In this paper, we are interested in developing models that can be used for evacuation control strategies. This model will be based on microscopic pedestrian simulation models, and its evolution and design requires a lot of information and data. The people stream will be simulated, based on mathematical models derived from empirical data about pedestrian flows. This model is developed from image data bases, so called empirical data, taken from a video camera or data obtained using human detectors. We consider the individuals as autonomous particles interacting through social and physical forces, which is an approach that has been used to simulate crowd behaviour. The target of this work is to describe a comprehensive approach to model a huge number of pedestrians and to simulate high density crowd behaviour in overcrowding places, e.g. sport, concert and pilgrimage places, and to assist engineering in the resolution of complicated problems through integrating a number of models from different research domains.展开更多
This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is t...This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is to comprehensively investigate prominent mechanisms’security features and vulnerabilities,emphasizing their security considerations,applications,challenges,and future directions.The existing literature offers valuable insights into various consensus mechanisms’strengths,limitations,and security vulnerabilities and their real-world applications.However,there remains a gap in synthesizing and analyzing this knowledge systematically.Addressing this gap would facilitate a structured approach to understanding consensus mechanisms’security and vulnerabilities comprehensively.The study adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and computer science standards and reviewed 3749 research papers from 2016 to 2024,excluding grey literature,resulting in 290 articles for descriptive analysis.The research highlights an increased focus on blockchain consensus security,energy efficiency,and hybrid mechanisms within 60%of research papers post-2019,identifying gaps in scalability,privacy,and interoperability for future exploration.By synthesizing the existing research and identifying the key trends,this SLR contributes to advancing the understanding of blockchain consensus mechanisms’security and guiding future research and structured innovation in blockchain systems and applications.展开更多
Most of the neural networks proposed so far for computational imaging(CI)in optics employ a supervised training strategy,and thus need a large training set to optimize their weights and biases.Setting aside the requir...Most of the neural networks proposed so far for computational imaging(CI)in optics employ a supervised training strategy,and thus need a large training set to optimize their weights and biases.Setting aside the requirements of environmental and system stability during many hours of data acquisition,in many practical applications,it is unlikely to be possible to obtain sufficient numbers of ground-truth images for training.Here,we propose to overcome this limitation by incorporating into a conventional deep neural network a complete physical model that represents the process of image formation.The most significant advantage of the resulting physics-enhanced deep neural network(PhysenNet)is that it can be used without training beforehand,thus eliminating the need for tens of thousands of labeled data.We take single-beam phase imaging as an example for demonstration.We experimentally show that one needs only to feed PhysenNet a single diffraction pattern of a phase object,and it can automatically optimize the network and eventually produce the object phase through the interplay between the neural network and the physical model.This opens up a new paradigm of neural network design,in which the concept of incorporating a physical model into a neural network can be generalized to solve many other CI problems.展开更多
Since the realization of Bose Einstein condensation(BEC)[1-3]and degenerate Fermi gases[4],ultracold quantum gases have become important platforms to study quantum phenomena and novel states of matter with precise con...Since the realization of Bose Einstein condensation(BEC)[1-3]and degenerate Fermi gases[4],ultracold quantum gases have become important platforms to study quantum phenomena and novel states of matter with precise control over both internal and external degrees of freedom.While quantum gases arc typically dilute and weakly interacting,the interactions intrinsically determine their essential properties,such as the superfluidity of a BEC.展开更多
When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this...When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this paper,we propose a scheme for spatial resolution enhancement of DHM by using the structured illumination but without phase shifting.The structured illuminations of different directions,which are generated by a spatial light modulator,illuminate the sample sequentially in the object plane.The formed object waves interfere with a reference wave in an off-axis configuration,and a CCD camera records the generated hologram.After the object waves are reconstructed numerically,a synthetic aperture is performed by an iterative algorithm to enhance the spatial resolution.The resolution improvement of the proposed method is proved and demonstrated by both simulation and experiment.展开更多
We propose an active learning scheme for automatically sampling a minimum number of uncorrelated configurations for fitting the Gaussian Approximation Potential(GAP).Our active learning scheme consists of an unsupervi...We propose an active learning scheme for automatically sampling a minimum number of uncorrelated configurations for fitting the Gaussian Approximation Potential(GAP).Our active learning scheme consists of an unsupervised machine learning(ML)scheme coupled with a Bayesian optimization technique that evaluates the GAP model.We apply this scheme to a Hafnium dioxide(HfO2)dataset generated from a“melt-quench”ab initio molecular dynamics(AIMD)protocol.Our results show that the active learning scheme,with no prior knowledge of the dataset,is able to extract a configuration that reaches the required energy fit tolerance.Further,molecular dynamics(MD)simulations performed using this active learned GAP model on 6144 atom systems of amorphous and liquid state elucidate the structural properties of HfO2 with near ab initio precision and quench rates(i.e.,1.0 K/ps)not accessible via AIMD.The melt and amorphous X-ray structural factors generated from our simulation are in good agreement with experiment.In addition,the calculated diffusion constants are in good agreement with previous ab initio studies.展开更多
Optical scatterometry is one of the most important metrology techniques for process monitoring in high-volume semiconductor manufacturing.By comparing measured signatures to modelled ones,scatterometry indirectly retr...Optical scatterometry is one of the most important metrology techniques for process monitoring in high-volume semiconductor manufacturing.By comparing measured signatures to modelled ones,scatterometry indirectly retrieves the dimensions of nanostructures and,hence,solves an inverse problem.However,the increasing design complexity of modern semiconductor devices makes modelling of the structures ever more difficult and requires a multitude of parameters.Such large parameter spaces typically cause ambiguities in the reconstruction process,thereby complicating the solution of the inherently ill-posed inverse problem further.An effective means of regularisation consists of systematically maximising the information content provided by the optical sensor.With this in mind,we combined the classical techniques of white-light interferometry,Mueller polarimetry,and Fourier scatterometry into one apparatus,allowing for the acquisition of fully angle-and wavelength-resolved Mueller matrices.The large amount of uncorrelated measurement data improve the robustness of the reconstruction in the case of complex multi-parameter problems by increasing the overall sensitivity and reducing cross-correlations.In this study,we discuss the sensor concept and introduce the measurement strategy,calibration routine,and numerical post-processing steps.We verify the practical feasibility of our method by reconstructing the profile parameters of a sub-wavelength silicon line grating.All necessary simulations are based on the rigorous coupledwave analysis method.Additional measurements performed using a scanning electron microscope and an atomic force microscope confirm the accuracy of the reconstruction results,and hence,the real-world applicability of the proposed sensor concept.展开更多
A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO...A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.展开更多
In this paper,we propose a dual-wavelength digital holographic interferometry method based on a compact dual vertical-cavity surface-emitting laser(VCSEL)source.The source simultaneously emits light from two highly st...In this paper,we propose a dual-wavelength digital holographic interferometry method based on a compact dual vertical-cavity surface-emitting laser(VCSEL)source.The source simultaneously emits light from two highly stabilized coherent light sources with slightly different wavelengths.A highly stabilized and adjustable current source enables the application of digital holographic dual-wavelength techniques to measure the shape of an object with height steps of a few millimeters.The wavelength drift over 12 h over the entire measurement range,which was evaluated using a wavemeter,was smaller than 1 pm.In addition to the low measurement uncertainty at large height jumps,the dual-wavelength digital holographic system distinguishes itself by its robustness to environmental disturbances such as air turbulence,heat load,and/or mechanical vibrations.This is enabled via a fiber-based almost common-path single-shot digital holographic acquisition of the information of the two different wavelengths using angular multiplexing.The experimental setup and data evaluation are discussed,and we present measurements of non-cooperative objects with specular reflective and/or diffuse reflective surfaces having different colors.展开更多
Imaging through random media continues to be a challenging problem of crucial importance in a wide range of fields of science and technology,ranging from telescopic imaging through atmospheric turbulence in astronomy ...Imaging through random media continues to be a challenging problem of crucial importance in a wide range of fields of science and technology,ranging from telescopic imaging through atmospheric turbulence in astronomy to microscopic imaging through scattering tissues in biology.To meet the scope of this anniversary issue in holography,this review places a special focus on holographic techniques and their unique functionality,which play a pivotal role in imaging through random media.This review comprises two parts.The first part is intended to be a mini tutorial in which we first identify the true nature of the problems encountered in imaging through random media.We then explain through a methodological analysis how unique functions of holography can be exploited to provide practical solutions to problems.The second part introduces specific examples of experimental implementations for different principles of holographic techniques,along with their performance results,which were taken from some of our recent work.展开更多
White-light interferometry is one of today’s most precise tools for determining the properties of optical materials.Its achievable precision and accuracy are typically limited by systematic errors due to a high numbe...White-light interferometry is one of today’s most precise tools for determining the properties of optical materials.Its achievable precision and accuracy are typically limited by systematic errors due to a high number of interdependent data-fitting parameters.Here,we introduce spectrally resolved quantum white-light interferometry as a novel tool for optical property measurements,notably,chromatic dispersion in optical fibres.By exploiting both spectral and photon-number correlations of energy-time entangled photon pairs,the number of fitting parameters is significantly reduced,which eliminates systematic errors and leads to an absolute determination of the material parameter.By comparing the quantum method to state-of-the-art approaches,we demonstrate the quantum advantage of 2.4 times better measurement precision,despite requiring 62 times fewer photons.The improved results are due to conceptual advantages enabled by quantum optics,which are likely to define new standards in experimental methods for characterising optical materials.展开更多
基金partially financially supported by the National Natural Science Foundation of China(No.42002068)the MOST Special Fund from the State Key Laboratory of GPMR,China University of Geosciences(Wuhan)the 111 Project(No.BP0719022)。
文摘Ultrahigh-pressure metamorphism has recently been reported from various crustal rocks in the Seve Nappe Complex(SNC)in which microdiamonds were found.However,in gneiss from the Lower Seve Nappe(LSN),neither any direct petrographic indication for UHP was reported nor the metamorphic evolution was well constrained.We studied a mylonitic gneiss from the Handol area of the LSN and applied phase-diagram modeling and Ti-in-biotite thermometry.Based on the compositions of garnet and biotite and observed mineral assemblages,a path was reconstructed passing through about 8 kbar and 730℃at prograde metamorphism.Peak-pressure and initial retrograde stages occurred at 9.0–10.2 kbar at 745-775℃,and 7–9 kbar at<750℃,respectively.No ultrahigh-pressure evidence was recognized compatible with medium-pressure metamorphism deduced in earlier studies of gneiss from the SNC.As higher peak pressures were reported recently for metamorphic rocks of the LSN,a possible interpretation is that slices or erased blocks were subducted,metamorphosed at different depths,and exhumed in a subduction channel.However,the dominant gneiss of the SNC experienced only a medium-pressure metamorphism in the upper part of the downgoing Baltica Plate.Rocks from different depth levels were brought together in an exhumation channel located between Baltica and the overlying plate.
文摘The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work Directive (WFD).One of the tools supporting the development of sustainable river management is physi- cal habitat modeling,e.g.,for fish,because fish population are one of the most important indicators for the e- colngical integrity of rivers.Within physical habitat models hydromorphological ...
基金support by the state of Baden-Württemberg through bw HPCfunding from the Euratom research and training program 2014-2018 and 2019-2020 under grant agreement No.633053。
文摘Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.This way,a density fluctuation spectrum is measured.However,the correspondence between fluctuation power and scattered microwave power is strongly nonlinear.Studying these processes numerically therefore requires fullwave simulations(IPF-FD3 D),with density fluctuations supplied by a separate plasma turbulence code(GENE).Earlier such attempts suffered from the low number of data points in the‘interesting’part of the spectrum,where a power law had to be fitted to 4 or 5 points.This has been overcome with recent simulations,which now show a much better agreement with experimental data.
文摘As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces. This mechanism operates in narrow, roughly half-filled superconducting bands of special symmetry and is evidently responsible for the formation of Cooper pairs in all superconductors. Here we consider this new mechanism within an outer magnetic field. We show that in the magnetic field the constraining forces produce Cooper pairs of non-vanishing total momentum with the consequence that an electric current flows within the superconductor. This current satisfies the London equations and, consequently, leads to the Meissner effect. This theoretical result is confirmed by the experimental observation that all superconductors, whether conventional or unconventional, exhibit the Meissner effect.
基金funding from the Euratom research and training programme 2014-2018 and2019-2020 under grant agreement No.633053。
文摘Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients during heat wave propagation,etc.A drawback of many present-day systems is that they use a fixed frequency difference between the probing frequencies.Hence,although the central probing frequency can be varied,the probing frequency difference is usually fixed.The new design presented in this work uses an advanced microwave generation and detection scheme,which allows for arbitrary probing frequencies and probing frequency separations.
文摘In recent years, modelling crowd and evacuation dynamics has become very important, with increasing huge numbers of people gathering around the world for many reasons and events. The fact that our global population grows dramatically every year and the current public transport systems are able to transport large amounts of people heightens the risk of crowd panic or crush. Pedestrian models are based on macroscopic or microscopic behaviour. In this paper, we are interested in developing models that can be used for evacuation control strategies. This model will be based on microscopic pedestrian simulation models, and its evolution and design requires a lot of information and data. The people stream will be simulated, based on mathematical models derived from empirical data about pedestrian flows. This model is developed from image data bases, so called empirical data, taken from a video camera or data obtained using human detectors. We consider the individuals as autonomous particles interacting through social and physical forces, which is an approach that has been used to simulate crowd behaviour. The target of this work is to describe a comprehensive approach to model a huge number of pedestrians and to simulate high density crowd behaviour in overcrowding places, e.g. sport, concert and pilgrimage places, and to assist engineering in the resolution of complicated problems through integrating a number of models from different research domains.
基金funded by Universiti Teknologi PETRONAS and grants(YUTP-PRG:015PBC-011).
文摘This study conducts a systematic literature review(SLR)of blockchain consensus mechanisms,an essential protocols that maintain the integrity,reliability,and decentralization of distributed ledger networks.The aim is to comprehensively investigate prominent mechanisms’security features and vulnerabilities,emphasizing their security considerations,applications,challenges,and future directions.The existing literature offers valuable insights into various consensus mechanisms’strengths,limitations,and security vulnerabilities and their real-world applications.However,there remains a gap in synthesizing and analyzing this knowledge systematically.Addressing this gap would facilitate a structured approach to understanding consensus mechanisms’security and vulnerabilities comprehensively.The study adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and computer science standards and reviewed 3749 research papers from 2016 to 2024,excluding grey literature,resulting in 290 articles for descriptive analysis.The research highlights an increased focus on blockchain consensus security,energy efficiency,and hybrid mechanisms within 60%of research papers post-2019,identifying gaps in scalability,privacy,and interoperability for future exploration.By synthesizing the existing research and identifying the key trends,this SLR contributes to advancing the understanding of blockchain consensus mechanisms’security and guiding future research and structured innovation in blockchain systems and applications.
基金supported by the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDB-SSW-JSC002)the Sino-German Center(GZ1391)the National Natural Science Foundation of China(61991452).
文摘Most of the neural networks proposed so far for computational imaging(CI)in optics employ a supervised training strategy,and thus need a large training set to optimize their weights and biases.Setting aside the requirements of environmental and system stability during many hours of data acquisition,in many practical applications,it is unlikely to be possible to obtain sufficient numbers of ground-truth images for training.Here,we propose to overcome this limitation by incorporating into a conventional deep neural network a complete physical model that represents the process of image formation.The most significant advantage of the resulting physics-enhanced deep neural network(PhysenNet)is that it can be used without training beforehand,thus eliminating the need for tens of thousands of labeled data.We take single-beam phase imaging as an example for demonstration.We experimentally show that one needs only to feed PhysenNet a single diffraction pattern of a phase object,and it can automatically optimize the network and eventually produce the object phase through the interplay between the neural network and the physical model.This opens up a new paradigm of neural network design,in which the concept of incorporating a physical model into a neural network can be generalized to solve many other CI problems.
文摘Since the realization of Bose Einstein condensation(BEC)[1-3]and degenerate Fermi gases[4],ultracold quantum gases have become important platforms to study quantum phenomena and novel states of matter with precise control over both internal and external degrees of freedom.While quantum gases arc typically dilute and weakly interacting,the interactions intrinsically determine their essential properties,such as the superfluidity of a BEC.
基金This work is supported by the National Basic Research Program(973 Program)of China under Grant No.2012CB921900the National Natural Science Foundation of China(NSFC)under Grant Nos.61377008,61107003,and 61275191.
文摘When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this paper,we propose a scheme for spatial resolution enhancement of DHM by using the structured illumination but without phase shifting.The structured illuminations of different directions,which are generated by a spatial light modulator,illuminate the sample sequentially in the object plane.The formed object waves interfere with a reference wave in an off-axis configuration,and a CCD camera records the generated hologram.After the object waves are reconstructed numerically,a synthetic aperture is performed by an iterative algorithm to enhance the spatial resolution.The resolution improvement of the proposed method is proved and demonstrated by both simulation and experiment.
基金This material is based upon work supported by Laboratory Directed Research and Development funding from Argonne National Laboratory,provided by the Director,Office of Science,of the U.S.Department of Energy(DOE)under Contract No.DEAC02-06CH11357This research used resources of the Argonne Leadership Computing Facility,which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357+3 种基金Argonne National Laboratory’s work was supported by the U.S.DOE,Office of Science,under contract DE-AC02-06CH11357This research used resources of the Advanced Photon Source,a U.S.DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357Use of the Center for Nanoscale Materials,an Office of Science user facility,was supported by the U.S.DOE,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357C.H.and A.N.K gratefully acknowledges useful discussions with Dr.Jens Smiatek,Dr.Frank Uhlig,and financial support from the German Funding Agency(Deutsche Forschungsgemeinschaft-DFG)under Germany’s Excellence Strategy—EXC 2075—390740016.
文摘We propose an active learning scheme for automatically sampling a minimum number of uncorrelated configurations for fitting the Gaussian Approximation Potential(GAP).Our active learning scheme consists of an unsupervised machine learning(ML)scheme coupled with a Bayesian optimization technique that evaluates the GAP model.We apply this scheme to a Hafnium dioxide(HfO2)dataset generated from a“melt-quench”ab initio molecular dynamics(AIMD)protocol.Our results show that the active learning scheme,with no prior knowledge of the dataset,is able to extract a configuration that reaches the required energy fit tolerance.Further,molecular dynamics(MD)simulations performed using this active learned GAP model on 6144 atom systems of amorphous and liquid state elucidate the structural properties of HfO2 with near ab initio precision and quench rates(i.e.,1.0 K/ps)not accessible via AIMD.The melt and amorphous X-ray structural factors generated from our simulation are in good agreement with experiment.In addition,the calculated diffusion constants are in good agreement with previous ab initio studies.
基金supported by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under grant number Os 111/50-1.
文摘Optical scatterometry is one of the most important metrology techniques for process monitoring in high-volume semiconductor manufacturing.By comparing measured signatures to modelled ones,scatterometry indirectly retrieves the dimensions of nanostructures and,hence,solves an inverse problem.However,the increasing design complexity of modern semiconductor devices makes modelling of the structures ever more difficult and requires a multitude of parameters.Such large parameter spaces typically cause ambiguities in the reconstruction process,thereby complicating the solution of the inherently ill-posed inverse problem further.An effective means of regularisation consists of systematically maximising the information content provided by the optical sensor.With this in mind,we combined the classical techniques of white-light interferometry,Mueller polarimetry,and Fourier scatterometry into one apparatus,allowing for the acquisition of fully angle-and wavelength-resolved Mueller matrices.The large amount of uncorrelated measurement data improve the robustness of the reconstruction in the case of complex multi-parameter problems by increasing the overall sensitivity and reducing cross-correlations.In this study,we discuss the sensor concept and introduce the measurement strategy,calibration routine,and numerical post-processing steps.We verify the practical feasibility of our method by reconstructing the profile parameters of a sub-wavelength silicon line grating.All necessary simulations are based on the rigorous coupledwave analysis method.Additional measurements performed using a scanning electron microscope and an atomic force microscope confirm the accuracy of the reconstruction results,and hence,the real-world applicability of the proposed sensor concept.
基金This work is part of the project “Plasma-induced CO2-conversion”(PiCK,project number:03SFK2S3B)and financially supported by the German Federal Ministry of Education and Research in the framework of the“Kopemikus projects for the Energiewende”.The authors are thankfUl to B.Sc.Laura Steinle(University of Stuttgart)for her assistance during the CO stability tests,and Christine Stefani and Prof.Dr.Robert Dinnebier(Max Planck Institute for Solid State Research,Stuttgart)for the in situ PXRD measurements,respectively.G.C.thanks Frank Hack and Dr.Angelika Veziridis for their kind support during experiments and discussions.
文摘A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.
文摘In this paper,we propose a dual-wavelength digital holographic interferometry method based on a compact dual vertical-cavity surface-emitting laser(VCSEL)source.The source simultaneously emits light from two highly stabilized coherent light sources with slightly different wavelengths.A highly stabilized and adjustable current source enables the application of digital holographic dual-wavelength techniques to measure the shape of an object with height steps of a few millimeters.The wavelength drift over 12 h over the entire measurement range,which was evaluated using a wavemeter,was smaller than 1 pm.In addition to the low measurement uncertainty at large height jumps,the dual-wavelength digital holographic system distinguishes itself by its robustness to environmental disturbances such as air turbulence,heat load,and/or mechanical vibrations.This is enabled via a fiber-based almost common-path single-shot digital holographic acquisition of the information of the two different wavelengths using angular multiplexing.The experimental setup and data evaluation are discussed,and we present measurements of non-cooperative objects with specular reflective and/or diffuse reflective surfaces having different colors.
基金support from a Grant-in-Aid for Transformative Research Areas(A)Grant Number A20H05888.
文摘Imaging through random media continues to be a challenging problem of crucial importance in a wide range of fields of science and technology,ranging from telescopic imaging through atmospheric turbulence in astronomy to microscopic imaging through scattering tissues in biology.To meet the scope of this anniversary issue in holography,this review places a special focus on holographic techniques and their unique functionality,which play a pivotal role in imaging through random media.This review comprises two parts.The first part is intended to be a mini tutorial in which we first identify the true nature of the problems encountered in imaging through random media.We then explain through a methodological analysis how unique functions of holography can be exploited to provide practical solutions to problems.The second part introduces specific examples of experimental implementations for different principles of holographic techniques,along with their performance results,which were taken from some of our recent work.
基金support from the Foundation Simone&Cino Del Duca,the European Commission for the FP7-ITN PICQUE project(Grant Agreement No.608062)l’Agence Nationale de la Recherche(ANR)for the CONNEQT,SPOCQ and SITQOM projects(Grants ANR-EMMA-002-01,ANR-14-CE32-0019 and ANR-15-CE24-0005,respectively)the iXCore Research Foundation.
文摘White-light interferometry is one of today’s most precise tools for determining the properties of optical materials.Its achievable precision and accuracy are typically limited by systematic errors due to a high number of interdependent data-fitting parameters.Here,we introduce spectrally resolved quantum white-light interferometry as a novel tool for optical property measurements,notably,chromatic dispersion in optical fibres.By exploiting both spectral and photon-number correlations of energy-time entangled photon pairs,the number of fitting parameters is significantly reduced,which eliminates systematic errors and leads to an absolute determination of the material parameter.By comparing the quantum method to state-of-the-art approaches,we demonstrate the quantum advantage of 2.4 times better measurement precision,despite requiring 62 times fewer photons.The improved results are due to conceptual advantages enabled by quantum optics,which are likely to define new standards in experimental methods for characterising optical materials.
