AIM:To assess the corneal high-order aberration(HOA)and its correlation with corneal morphological parameters in patients with bilateral keratoconus(KCN)and unilateral Vogt’s striae.METHODS:A total of 168 eyes of 84 ...AIM:To assess the corneal high-order aberration(HOA)and its correlation with corneal morphological parameters in patients with bilateral keratoconus(KCN)and unilateral Vogt’s striae.METHODS:A total of 168 eyes of 84 patients with KCN,whose corneas had definite signs of unilateral Vogt’s striae,were enrolled.Corneal HOA and morphological parameters were measured using Pentacam HR.RESULTS:The corneal morphological parameters between KCN eyes with and without Vogt’s striae were evidently different(P<0.001).The 3rd coma 90°,4th spherical aberration,5th coma 90°,root-mean-square(RMS)(total),and RMS(HOA)in the front,back surfaces and total cornea in KCN eyes with Vogt’s striae were significantly higher than those in KCN eyes without Vogt’s striae(P<0.001).In KCN eyes with Vogt’s striae,the 3rd coma 90°and 4th spherical aberration in the front surface and total cornea were negatively correlated with flat keratometry value(K1),steep keratometry value(K2),mean keratometry value(Km),maximum keratometry value(Kmax),anterior corneal elevation(ACE),and posterior corneal elevation(PCE;P<0.05).The 3rd coma 90°,4th spherical aberration in back surface and RMS(total),RMS(HOA)in the front,back surfaces,total cornea were positively correlated with K1,K2,Km,Kmax,ACE,and PCE(P<0.05).CONCLUSION:Corneal HOA especially vertical coma and spherical aberration may increase when Vogt’s striae appeared in KCN eyes.The scale of increase is significantly related with changes in corneal shapes.展开更多
BACKGROUND We invented Endoscopic Ruler,a new endoscopic device to measure the size of varices in patients with cirrhosis and portal hypertension.AIM To assess the feasibility and safety of Endoscopic Ruler,and evalua...BACKGROUND We invented Endoscopic Ruler,a new endoscopic device to measure the size of varices in patients with cirrhosis and portal hypertension.AIM To assess the feasibility and safety of Endoscopic Ruler,and evaluate the agreement on identifying large oesophageal varices(OV)between Endoscopic Ruler and the endoscopists,as well as the interobserver agreement on diagnosing large OV using Endoscopic Ruler.METHODS We prospectively and consecutively enrolled patients with cirrhosis from 11 hospitals,all of whom got esophagogastroduodenoscopy(EGD)with Endoscopic Ruler.The primary study outcome was a successful measurement of the size of varices using Endoscopic Ruler.The secondary outcomes included adverse events,operation time,the agreement of identifying large OV between the objective measurement of Endoscopic Ruler and the empirical reading of endoscopists,together with the interobserver agreement on diagnosing large OV by Endoscopic Ruler.RESULTS From November 2020 to April 2022,a total of 120 eligible patients with cirrhosis were recruited and all of them underwent EGD examinations with Endoscopic Ruler successfully without any adverse event.The median operation time of Endoscopic Ruler was 3.00 min[interquartile range(IQR):3.00 min].The kappa value between Endoscopic Ruler and the endoscopists while detecting large OV was 0.52,demonstrating a moderate agreement.The kappa value for diagnosing large OV using Endoscopic Ruler among the six independent observers was 0.77,demonstrating a substantial agreement.CONCLUSION The data demonstrates that Endoscopic Ruler is feasible and safe for measuring the size of varices in patients with cirrhosis and portal hypertension.Endoscopic Ruler is potential to promote the clinical practice of the two-grade classification system of OV.展开更多
The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffrac...The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.展开更多
This study explores the key physicochemical factors affecting the hydrophilic characteristics of iron mine blasting dust(BD). The BD is separated into an unwetted part(UWBD, hydrophobic part) and a wetted part(WBD, hy...This study explores the key physicochemical factors affecting the hydrophilic characteristics of iron mine blasting dust(BD). The BD is separated into an unwetted part(UWBD, hydrophobic part) and a wetted part(WBD, hydrophilic part). Its particle size, true density(TD), pore parameters, mineral composition, and surface compounds are comprehensively characterized and compared. The results indicate that a smaller particle size and more developed pore parameters are two key factors responsible for the strong hydrophobicity of the BD. The mineral composition of the BD has no direct effect on its wetting properties;however, it indirectly influences the deposition characteristics of the BD in water by affecting its TD. Unlike coal dust, the surface organic composition of the BD does not affect its wettability and the peak area of C–C/C–H hydrophobic groups in the C 1s X-ray photoelectron spectrum of the UWBD(45.03%) is smaller than that in the C 1s spectrum of the WBD(68.30%). Thus, eleven co-influencing processes of physicochemical properties of the BD on its wettability are summarized. This research sheds light on the key factors affecting the wettability of the BD.展开更多
A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central fre...A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.展开更多
Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges relate...Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges related to COGs remain unsolved,and a literature review of the current state of the technology is needed.First,the present article summarizes the basic information and applications of COGs,including their oxygen production mechanism,components,forming technology,and ignition system.Four current challenges encountered in applying COGs are discussed,along with the strategies adopted thus far to solve these problems,as found in the published literature.The literature survey reveals that,although much effort has been devoted to controlling the oxygen production rate and the heat output of COGs,the mechanism of producing toxic gases remains unclear and a reliable and safe ignition system has not been fully developed.Finally,future opportunities in the development of COGs are briefly listed.展开更多
Irreversible drift-diffusion processes are very common in biochemical reactions.They have a non-equilibrium stationary state(invariant measure)which does not satisfy detailed balance.For the corresponding Fokker-Planc...Irreversible drift-diffusion processes are very common in biochemical reactions.They have a non-equilibrium stationary state(invariant measure)which does not satisfy detailed balance.For the corresponding Fokker-Planck equation on a closed manifold,using Voronoi tessellation,we propose two upwind finite volume schemes with or without the information of the invariant measure.Both schemes possess stochastic Q-matrix structures and can be decomposed as a gradient flow part and a Hamiltonian flow part,enabling us to prove unconditional stability,ergodicity and error estimates.Based on the two upwind schemes,several numerical examples–including sampling accelerated by a mixture flow,image transformations and simulations for stochastic model of chaotic system–are conducted.These two structurepreserving schemes also give a natural random walk approximation for a generic irreversible drift-diffusion process on a manifold.This makes them suitable for adapting to manifold-related computations that arise from high-dimensional molecular dynamics simulations.展开更多
Background：Knee osteoarthritis （KOA） is a chronic joint disease that manifests as knee pain as well as different degrees of lower limb swelling,stiffness,and movement disorders.The therapeutic goal is to alleviate ...Background：Knee osteoarthritis （KOA） is a chronic joint disease that manifests as knee pain as well as different degrees of lower limb swelling,stiffness,and movement disorders.The therapeutic goal is to alleviate or eliminate pain,correct deformities,improve or restore joint functions,and improve the quality of life.This study aimed to evaluate the efficacy and safety of Zhuanggu joint capsules combined with celecoxib and the benefit of treatment with Zhuanggu alone for KOA.Methods：This multi-center,randomized,double-blind,double-dummy,parallel controlled trial,started from December 2011 to May 2014,was carried out in 6 cities,including Beijing,Shanghai,Chongqing,Changchun,Chengdu,and Nanjing.A total of 432 patients with KOA were divided into three groups （144 cases in each group）.The groups were treated,respectively,with Zhuanggu joint capsules combined with celecoxib capsule simulants,Zhuanggu joint capsules combined with celecoxib capsules,and celecoxib capsules combined with Zhuanggu joint capsule simulants for 4 weeks consecutively.The improvement of Western Ontario and McMaster Universities Osteoarthritis （WOMAC） index and the decreased rates in each dimension of WOMAC were evaluated before and after the treatment.Intergroup and intragroup comparisons of quantitative indices were performed.Statistically significant differences were evaluated with pairwise comparisons using Chi-square test （or Fisher＆#39;s exact test） and an inspection level ofα =0.0167.Results：Four weeks after treatment,the total efficacies of Zhuanggu group,combination group,and celecoxib group were 65%,80%,and 64%,respectively,with statistically significant differences among the three groups （P =0.005）.Intergroup pairwise comparisons showed that the total efficacy of the combination group was significantly higher than that of the Zhuanggu （P =0.005） and celecoxib （P =0.003）groups.The difference between the latter two groups was not statistically significant （P 〉 0.0167）.Four weeks after discontinuation,the efficacies of the three groups were 78%,95%,and 65%,respectively,with statistically significant differences （P 〈 0.0001）.Intergroup pairwise comparisons revealed that the efficacy of the combination group was significantly better than that of the Zhuanggu and the celecoxib groups （P 〈 0.0001）.The difference between the latter two groups was not statistically significant （P 〉 0.0167）.The incidences of adverse events in Zhuanggu group,combination group,and celecoxib group were 8.5%,8.5%,and 11.1%,respectively,with insignificant differences （P 〉 0.05）.Conclusions：Zhuanggu joint capsules alone or combined with celecoxib showed clinical efficacy in the treatment of KOA.The safety of Zhuanggu joint capsules alone or combined with celecoxib was acceptable.展开更多
The computation of compressible flows becomesmore challengingwhen the Mach number has different orders of magnitude.When the Mach number is of order one,modern shock capturing methods are able to capture shocks and ot...The computation of compressible flows becomesmore challengingwhen the Mach number has different orders of magnitude.When the Mach number is of order one,modern shock capturing methods are able to capture shocks and other complex structures with high numerical resolutions.However,if theMach number is small,the acoustic waves lead to stiffness in time and excessively large numerical viscosity,thus demanding much smaller time step and mesh size than normally needed for incompressible flow simulation.In this paper,we develop an all-speed asymptotic preserving(AP)numerical scheme for the compressible isentropic Euler and Navier-Stokes equations that is uniformly stable and accurate for all Mach numbers.Our idea is to split the system into two parts:one involves a slow,nonlinear and conservative hyperbolic system adequate for the use of modern shock capturing methods and the other a linear hyperbolic system which contains the stiff acoustic dynamics,to be solved implicitly.This implicit part is reformulated into a standard pressure Poisson projection system and thus possesses sufficient structure for efficient fast Fourier transform solution techniques.In the zero Mach number limit,the scheme automatically becomes a projection method-like incompressible solver.We present numerical results in one and two dimensions in both compressible and incompressible regimes.展开更多
Despite important advances in the mathematical analysis of the Euler equations for water waves,especially over the last two decades,it is not yet known whether local singularities can develop from smooth data in well-...Despite important advances in the mathematical analysis of the Euler equations for water waves,especially over the last two decades,it is not yet known whether local singularities can develop from smooth data in well-posed initial value problems.For ideal free-surface flow with zero surface tension and gravity,the authors review existing works that describe"splash singularities",singular hyperbolic solutions related to jet formation and"flip-through",and a recent construction of a singular free surface by Zubarev and Karabut that however involves unbounded negative pressure.The authors illustrate some of these phenomena with numerical computations of 2D flow based upon a conformal mapping formulation.Numerical tests with a different kind of initial data suggest the possibility that corner singularities may form in an unstable way from specially prepared initial data.展开更多
Entity perception of ambiguous user comments is a critical problem of target identification for huge amount of public opinions.In this paper,a Two-Step-Matching method is proposed to identify the precise target entity...Entity perception of ambiguous user comments is a critical problem of target identification for huge amount of public opinions.In this paper,a Two-Step-Matching method is proposed to identify the precise target entity from multiple entities mentioned.Firstly,potential entities are extracted by BiLSTM-CRF model and characteristic words by TF-IDF model from public comments.Secondly,the first matching is implemented between potential entities and an official business directory by Jaro-Winkler distance algorithm.Then,in order to find the pre-cise one,an industry-characteristic dictionary is developed into the second matching process.The precise entity is identified according to the count of characteristic words matching to industry-characteristic dictionary.In addition,associated rate(global indicator)and accuracy rate(sample indicator)are defined for evaluation of matching accuracy.The results for three data sets of public opinions about major public health events show that the highest associated rate and accuracy rate arrive at 0.93 and 0.95,averagely enhanced by 32%and 30%above the case of using the first matching process alone.This framework provides the method to find the true target entity of really wanted expression from public opinions.展开更多
Based on the Hirota’s bilinear form and symbolic computation,the Kadomtsev-Petviashvili equation with variable coefficients is investigated.The lump solutions and interaction solutions between lump solution and a pai...Based on the Hirota’s bilinear form and symbolic computation,the Kadomtsev-Petviashvili equation with variable coefficients is investigated.The lump solutions and interaction solutions between lump solution and a pair of resonance stripe solitons are presented.Their dynamical behaviors are described by some three-dimensional plots and corresponding contour plots.展开更多
In this paper, a generalized (3+1)-dimensional variable-coefficient nonlinear-wave equation is studied in liquid with gas bubbles. Based on the Hirota’s bilinear form and symbolic computation, lump and interaction so...In this paper, a generalized (3+1)-dimensional variable-coefficient nonlinear-wave equation is studied in liquid with gas bubbles. Based on the Hirota’s bilinear form and symbolic computation, lump and interaction solutions between lump and solitary wave are obtained,which include a periodic-shape lump solution, a parabolic-shape lump solution, a cubic-shape lump solution, interaction solutions between lump and one solitary wave, and between lump and two solitary waves. The spatial structures called the bright lump wave and the bright-dark lump wave are discussed. Interaction behaviors of two bright-dark lump waves and a periodic-shape bright lump wave are also presented. Their interactions are shown in some 3D plots.展开更多
We present a fast Poisson solver on spherical shells.With a special change of variable,the radial part of the Laplacian transforms to a constant coefficient differential operator.As a result,the Fast Fourier Transform...We present a fast Poisson solver on spherical shells.With a special change of variable,the radial part of the Laplacian transforms to a constant coefficient differential operator.As a result,the Fast Fourier Transform can be applied to solve the Poisson equation with O(N^(3) logN)operations.Numerical examples have confirmed the accuracy and robustness of the new scheme.展开更多
A fourth-order finite difference method is proposed and studied for the primitive equations(PEs)of large-scale atmospheric and oceanic flow based on mean vorticity formulation.Since the vertical average of the horizon...A fourth-order finite difference method is proposed and studied for the primitive equations(PEs)of large-scale atmospheric and oceanic flow based on mean vorticity formulation.Since the vertical average of the horizontal velocity field is divergence-free,we can introduce mean vorticity and mean stream function which are connected by a 2-D Poisson equation.As a result,the PEs can be reformulated such that the prognostic equation for the horizontal velocity is replaced by evolutionary equations for the mean vorticity field and the vertical derivative of the horizontal velocity.The mean vorticity equation is approximated by a compact difference scheme due to the difficulty of the mean vorticity boundary condition,while fourth-order long-stencil approximations are utilized to deal with transport type equations for computational convenience.The numerical values for the total velocity field(both horizontal and vertical)are statically determined by a discrete realization of a differential equation at each fixed horizontal point.The method is highly efficient and is capable of producing highly resolved solutions at a reasonable computational cost.The full fourth-order accuracy is checked by an example of the reformulated PEs with force terms.Additionally,numerical results of a large-scale oceanic circulation are presented.展开更多
We consider in this paper random batch interacting particle methods forsolving the Poisson-Nernst-Planck (PNP) equations, and thus the Poisson-Boltzmann(PB) equation as the equilibrium, in the external unbounded domai...We consider in this paper random batch interacting particle methods forsolving the Poisson-Nernst-Planck (PNP) equations, and thus the Poisson-Boltzmann(PB) equation as the equilibrium, in the external unbounded domain. To justify thesimulation in a truncated domain, an error estimate of the truncation is proved inthe symmetric cases for the PB equation. Then, the random batch interacting particle methods are introduced which are O(N) per time step. The particle methods cannot only be considered as a numerical method for solving the PNP and PB equations,but also can be used as a direct simulation approach for the dynamics of the chargedparticles in solution. The particle methods are preferable due to their simplicity andadaptivity to complicated geometry, and may be interesting in describing the dynamics of the physical process. Moreover, it is feasible to incorporate more physical effectsand interactions in the particle methods and to describe phenomena beyond the scopeof the mean-field equations.展开更多
Although interest in numerical approximations of the water wave equationgrows in recent years, the lack of rigorous analysis of its time discretization inhibits thedesign of more efficient algorithms. In practice of w...Although interest in numerical approximations of the water wave equationgrows in recent years, the lack of rigorous analysis of its time discretization inhibits thedesign of more efficient algorithms. In practice of water wave simulations, the tradeoff between efficiency and stability has been a challenging problem. Thus to shed lighton the stability condition for simulations of water waves, we focus on a model simpli-fied from the water wave equation of infinite depth. This model preserves two mainproperties of the water wave equation: non-locality and hyperbolicity. For the constantcoefficient case, we conduct systematic stability studies of the fully discrete approximation of such systems with the Fourier spectral approximation in space and generalRunge-Kutta methods in time. As a result, an optimal time discretization strategy isprovided in the form of a modified CFL condition, i.e. ∆t = O(√∆x). Meanwhile,the energy stable property is established for certain explicit Runge-Kutta methods.This CFL condition solves the problem of efficiency and stability: it allows numericalschemes to stay stable while resolves oscillations at the lowest requirement, which onlyproduces acceptable computational load. In the variable coefficient case, the convergence of the semi-discrete approximation of it is presented, which naturally connectsto the water wave equation. Analogue of these results for the water wave equationof finite depth is also discussed. To validate these theoretic observation, extensive numerical tests have been performed to verify the stability conditions. Simulations of thesimplified hyperbolic model in the high frequency regime and the water wave equation are also provided.展开更多
基金Supported by Xi’an Health Committee Research Projects(No.2023yb14)Shaanxi Province Natural Science Basic Research Project(No.2024JC-YBMS-623)Shaanxi Province Science and Technology Plan Project(No.2024SFYBXM-331).
文摘AIM:To assess the corneal high-order aberration(HOA)and its correlation with corneal morphological parameters in patients with bilateral keratoconus(KCN)and unilateral Vogt’s striae.METHODS:A total of 168 eyes of 84 patients with KCN,whose corneas had definite signs of unilateral Vogt’s striae,were enrolled.Corneal HOA and morphological parameters were measured using Pentacam HR.RESULTS:The corneal morphological parameters between KCN eyes with and without Vogt’s striae were evidently different(P<0.001).The 3rd coma 90°,4th spherical aberration,5th coma 90°,root-mean-square(RMS)(total),and RMS(HOA)in the front,back surfaces and total cornea in KCN eyes with Vogt’s striae were significantly higher than those in KCN eyes without Vogt’s striae(P<0.001).In KCN eyes with Vogt’s striae,the 3rd coma 90°and 4th spherical aberration in the front surface and total cornea were negatively correlated with flat keratometry value(K1),steep keratometry value(K2),mean keratometry value(Km),maximum keratometry value(Kmax),anterior corneal elevation(ACE),and posterior corneal elevation(PCE;P<0.05).The 3rd coma 90°,4th spherical aberration in back surface and RMS(total),RMS(HOA)in the front,back surfaces,total cornea were positively correlated with K1,K2,Km,Kmax,ACE,and PCE(P<0.05).CONCLUSION:Corneal HOA especially vertical coma and spherical aberration may increase when Vogt’s striae appeared in KCN eyes.The scale of increase is significantly related with changes in corneal shapes.
基金This study is registered at https://www.clinicaltrials.gov/.The registration identification number is NCT04639323.
文摘BACKGROUND We invented Endoscopic Ruler,a new endoscopic device to measure the size of varices in patients with cirrhosis and portal hypertension.AIM To assess the feasibility and safety of Endoscopic Ruler,and evaluate the agreement on identifying large oesophageal varices(OV)between Endoscopic Ruler and the endoscopists,as well as the interobserver agreement on diagnosing large OV using Endoscopic Ruler.METHODS We prospectively and consecutively enrolled patients with cirrhosis from 11 hospitals,all of whom got esophagogastroduodenoscopy(EGD)with Endoscopic Ruler.The primary study outcome was a successful measurement of the size of varices using Endoscopic Ruler.The secondary outcomes included adverse events,operation time,the agreement of identifying large OV between the objective measurement of Endoscopic Ruler and the empirical reading of endoscopists,together with the interobserver agreement on diagnosing large OV by Endoscopic Ruler.RESULTS From November 2020 to April 2022,a total of 120 eligible patients with cirrhosis were recruited and all of them underwent EGD examinations with Endoscopic Ruler successfully without any adverse event.The median operation time of Endoscopic Ruler was 3.00 min[interquartile range(IQR):3.00 min].The kappa value between Endoscopic Ruler and the endoscopists while detecting large OV was 0.52,demonstrating a moderate agreement.The kappa value for diagnosing large OV using Endoscopic Ruler among the six independent observers was 0.77,demonstrating a substantial agreement.CONCLUSION The data demonstrates that Endoscopic Ruler is feasible and safe for measuring the size of varices in patients with cirrhosis and portal hypertension.Endoscopic Ruler is potential to promote the clinical practice of the two-grade classification system of OV.
基金financially supported by the National Key Research and Development Program of China(No.SQ2017YFSF060069)the National Natural Science Foundation of China(No.51574017)
文摘The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFC0805204)the National Natural Science Foundation of China (Nos. 51874015 and 51504017)
文摘This study explores the key physicochemical factors affecting the hydrophilic characteristics of iron mine blasting dust(BD). The BD is separated into an unwetted part(UWBD, hydrophobic part) and a wetted part(WBD, hydrophilic part). Its particle size, true density(TD), pore parameters, mineral composition, and surface compounds are comprehensively characterized and compared. The results indicate that a smaller particle size and more developed pore parameters are two key factors responsible for the strong hydrophobicity of the BD. The mineral composition of the BD has no direct effect on its wetting properties;however, it indirectly influences the deposition characteristics of the BD in water by affecting its TD. Unlike coal dust, the surface organic composition of the BD does not affect its wettability and the peak area of C–C/C–H hydrophobic groups in the C 1s X-ray photoelectron spectrum of the UWBD(45.03%) is smaller than that in the C 1s spectrum of the WBD(68.30%). Thus, eleven co-influencing processes of physicochemical properties of the BD on its wettability are summarized. This research sheds light on the key factors affecting the wettability of the BD.
基金Project supported by the National Key Scientific Instrument and Equipment Development,China(Grant No.2014YQ060537)the National Key Research and Development Program,China(Grant No.2016YFC0201103)
文摘A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.
基金financially supported by the National Key Research and Development Program of China (No.2017YFC0805204)the National Natural Science Foundation of China (Nos.51504017 and 51874015)
文摘Chemical oxygen generators(COGs)have been used worldwide in confined spaces as an emergency oxygen supply technology,mainly because they are independent and have a long shelf life.However,a number of challenges related to COGs remain unsolved,and a literature review of the current state of the technology is needed.First,the present article summarizes the basic information and applications of COGs,including their oxygen production mechanism,components,forming technology,and ignition system.Four current challenges encountered in applying COGs are discussed,along with the strategies adopted thus far to solve these problems,as found in the published literature.The literature survey reveals that,although much effort has been devoted to controlling the oxygen production rate and the heat output of COGs,the mechanism of producing toxic gases remains unclear and a reliable and safe ignition system has not been fully developed.Finally,future opportunities in the development of COGs are briefly listed.
基金Jian-Guo Liu was supported in part by NSF under awards DMS-2106988by NSF RTG grant DMS-2038056Yuan Gao was supported by NSF under awards DMS-2204288.
文摘Irreversible drift-diffusion processes are very common in biochemical reactions.They have a non-equilibrium stationary state(invariant measure)which does not satisfy detailed balance.For the corresponding Fokker-Planck equation on a closed manifold,using Voronoi tessellation,we propose two upwind finite volume schemes with or without the information of the invariant measure.Both schemes possess stochastic Q-matrix structures and can be decomposed as a gradient flow part and a Hamiltonian flow part,enabling us to prove unconditional stability,ergodicity and error estimates.Based on the two upwind schemes,several numerical examples–including sampling accelerated by a mixture flow,image transformations and simulations for stochastic model of chaotic system–are conducted.These two structurepreserving schemes also give a natural random walk approximation for a generic irreversible drift-diffusion process on a manifold.This makes them suitable for adapting to manifold-related computations that arise from high-dimensional molecular dynamics simulations.
文摘Background：Knee osteoarthritis （KOA） is a chronic joint disease that manifests as knee pain as well as different degrees of lower limb swelling,stiffness,and movement disorders.The therapeutic goal is to alleviate or eliminate pain,correct deformities,improve or restore joint functions,and improve the quality of life.This study aimed to evaluate the efficacy and safety of Zhuanggu joint capsules combined with celecoxib and the benefit of treatment with Zhuanggu alone for KOA.Methods：This multi-center,randomized,double-blind,double-dummy,parallel controlled trial,started from December 2011 to May 2014,was carried out in 6 cities,including Beijing,Shanghai,Chongqing,Changchun,Chengdu,and Nanjing.A total of 432 patients with KOA were divided into three groups （144 cases in each group）.The groups were treated,respectively,with Zhuanggu joint capsules combined with celecoxib capsule simulants,Zhuanggu joint capsules combined with celecoxib capsules,and celecoxib capsules combined with Zhuanggu joint capsule simulants for 4 weeks consecutively.The improvement of Western Ontario and McMaster Universities Osteoarthritis （WOMAC） index and the decreased rates in each dimension of WOMAC were evaluated before and after the treatment.Intergroup and intragroup comparisons of quantitative indices were performed.Statistically significant differences were evaluated with pairwise comparisons using Chi-square test （or Fisher＆#39;s exact test） and an inspection level ofα =0.0167.Results：Four weeks after treatment,the total efficacies of Zhuanggu group,combination group,and celecoxib group were 65%,80%,and 64%,respectively,with statistically significant differences among the three groups （P =0.005）.Intergroup pairwise comparisons showed that the total efficacy of the combination group was significantly higher than that of the Zhuanggu （P =0.005） and celecoxib （P =0.003）groups.The difference between the latter two groups was not statistically significant （P 〉 0.0167）.Four weeks after discontinuation,the efficacies of the three groups were 78%,95%,and 65%,respectively,with statistically significant differences （P 〈 0.0001）.Intergroup pairwise comparisons revealed that the efficacy of the combination group was significantly better than that of the Zhuanggu and the celecoxib groups （P 〈 0.0001）.The difference between the latter two groups was not statistically significant （P 〉 0.0167）.The incidences of adverse events in Zhuanggu group,combination group,and celecoxib group were 8.5%,8.5%,and 11.1%,respectively,with insignificant differences （P 〉 0.05）.Conclusions：Zhuanggu joint capsules alone or combined with celecoxib showed clinical efficacy in the treatment of KOA.The safety of Zhuanggu joint capsules alone or combined with celecoxib was acceptable.
基金J.-G.Liu was supported by NSF grant DMS 10-11738.J.Haack and S.Jin were supported by NSF grant DMS-0608720the NSF FRG grant”Collaborative research on Kinetic Description of Multiscale Phenomena:Modeling,Theory and Computation”(NSF DMS-0757285).
文摘The computation of compressible flows becomesmore challengingwhen the Mach number has different orders of magnitude.When the Mach number is of order one,modern shock capturing methods are able to capture shocks and other complex structures with high numerical resolutions.However,if theMach number is small,the acoustic waves lead to stiffness in time and excessively large numerical viscosity,thus demanding much smaller time step and mesh size than normally needed for incompressible flow simulation.In this paper,we develop an all-speed asymptotic preserving(AP)numerical scheme for the compressible isentropic Euler and Navier-Stokes equations that is uniformly stable and accurate for all Mach numbers.Our idea is to split the system into two parts:one involves a slow,nonlinear and conservative hyperbolic system adequate for the use of modern shock capturing methods and the other a linear hyperbolic system which contains the stiff acoustic dynamics,to be solved implicitly.This implicit part is reformulated into a standard pressure Poisson projection system and thus possesses sufficient structure for efficient fast Fourier transform solution techniques.In the zero Mach number limit,the scheme automatically becomes a projection method-like incompressible solver.We present numerical results in one and two dimensions in both compressible and incompressible regimes.
基金supported by the National Science Foundation under NSF Research Network Grant RNMS11-07444(KI-Net)the NSF Grants DMS-1514826,DMS-1812573,DMS-1515400,DMS-1812609the Simons Foundation under Grant 395796
文摘Despite important advances in the mathematical analysis of the Euler equations for water waves,especially over the last two decades,it is not yet known whether local singularities can develop from smooth data in well-posed initial value problems.For ideal free-surface flow with zero surface tension and gravity,the authors review existing works that describe"splash singularities",singular hyperbolic solutions related to jet formation and"flip-through",and a recent construction of a singular free surface by Zubarev and Karabut that however involves unbounded negative pressure.The authors illustrate some of these phenomena with numerical computations of 2D flow based upon a conformal mapping formulation.Numerical tests with a different kind of initial data suggest the possibility that corner singularities may form in an unstable way from specially prepared initial data.
基金This work is partially supported by the National Natural Science Foundation of China(Grant Nos.71901144,71771152,61773248)the Major Program of National Fund of Philosophy and Social Science of China(18ZDA088,20ZDA060)+2 种基金Shanghai Planning Office of Philosophy and Social Science Foundation(Grant No.2019EXW001)Foundation of University of Finance and Economics(Grant No.2017110709)S-Tech internet communication project(Grant Nos.2018PHD005 and 2018TECH003).
文摘Entity perception of ambiguous user comments is a critical problem of target identification for huge amount of public opinions.In this paper,a Two-Step-Matching method is proposed to identify the precise target entity from multiple entities mentioned.Firstly,potential entities are extracted by BiLSTM-CRF model and characteristic words by TF-IDF model from public comments.Secondly,the first matching is implemented between potential entities and an official business directory by Jaro-Winkler distance algorithm.Then,in order to find the pre-cise one,an industry-characteristic dictionary is developed into the second matching process.The precise entity is identified according to the count of characteristic words matching to industry-characteristic dictionary.In addition,associated rate(global indicator)and accuracy rate(sample indicator)are defined for evaluation of matching accuracy.The results for three data sets of public opinions about major public health events show that the highest associated rate and accuracy rate arrive at 0.93 and 0.95,averagely enhanced by 32%and 30%above the case of using the first matching process alone.This framework provides the method to find the true target entity of really wanted expression from public opinions.
基金Supported by National Natural Science Foundation of China under Grant No.81860771
文摘Based on the Hirota’s bilinear form and symbolic computation,the Kadomtsev-Petviashvili equation with variable coefficients is investigated.The lump solutions and interaction solutions between lump solution and a pair of resonance stripe solitons are presented.Their dynamical behaviors are described by some three-dimensional plots and corresponding contour plots.
基金Project supported by National Natural Science Foundation of China(Grant No 81960715)Science and Technology Project of Education Department of Jiangxi Province(GJJ151079)。
文摘In this paper, a generalized (3+1)-dimensional variable-coefficient nonlinear-wave equation is studied in liquid with gas bubbles. Based on the Hirota’s bilinear form and symbolic computation, lump and interaction solutions between lump and solitary wave are obtained,which include a periodic-shape lump solution, a parabolic-shape lump solution, a cubic-shape lump solution, interaction solutions between lump and one solitary wave, and between lump and two solitary waves. The spatial structures called the bright lump wave and the bright-dark lump wave are discussed. Interaction behaviors of two bright-dark lump waves and a periodic-shape bright lump wave are also presented. Their interactions are shown in some 3D plots.
基金The research of Liu was supported by the NSF grant DMS 10-11738The research of Wang was supported by National Science Council of Taiwan under grant 97-2115-M-007-005In addition,this work is also supported in part by National Center for Theoretical Sciences of Taiwan.
文摘We present a fast Poisson solver on spherical shells.With a special change of variable,the radial part of the Laplacian transforms to a constant coefficient differential operator.As a result,the Fast Fourier Transform can be applied to solve the Poisson equation with O(N^(3) logN)operations.Numerical examples have confirmed the accuracy and robustness of the new scheme.
文摘A fourth-order finite difference method is proposed and studied for the primitive equations(PEs)of large-scale atmospheric and oceanic flow based on mean vorticity formulation.Since the vertical average of the horizontal velocity field is divergence-free,we can introduce mean vorticity and mean stream function which are connected by a 2-D Poisson equation.As a result,the PEs can be reformulated such that the prognostic equation for the horizontal velocity is replaced by evolutionary equations for the mean vorticity field and the vertical derivative of the horizontal velocity.The mean vorticity equation is approximated by a compact difference scheme due to the difficulty of the mean vorticity boundary condition,while fourth-order long-stencil approximations are utilized to deal with transport type equations for computational convenience.The numerical values for the total velocity field(both horizontal and vertical)are statically determined by a discrete realization of a differential equation at each fixed horizontal point.The method is highly efficient and is capable of producing highly resolved solutions at a reasonable computational cost.The full fourth-order accuracy is checked by an example of the reformulated PEs with force terms.Additionally,numerical results of a large-scale oceanic circulation are presented.
基金This work is partially supported by the National Key R&D Program of China,Project Number 2021YFA1002800The work of L.Li was partially sponsored by the Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDA25010403,and NSFC 11901389,12031013The work of J.-G.Liu was supported by NSF DMS-2106988.
文摘We consider in this paper random batch interacting particle methods forsolving the Poisson-Nernst-Planck (PNP) equations, and thus the Poisson-Boltzmann(PB) equation as the equilibrium, in the external unbounded domain. To justify thesimulation in a truncated domain, an error estimate of the truncation is proved inthe symmetric cases for the PB equation. Then, the random batch interacting particle methods are introduced which are O(N) per time step. The particle methods cannot only be considered as a numerical method for solving the PNP and PB equations,but also can be used as a direct simulation approach for the dynamics of the chargedparticles in solution. The particle methods are preferable due to their simplicity andadaptivity to complicated geometry, and may be interesting in describing the dynamics of the physical process. Moreover, it is feasible to incorporate more physical effectsand interactions in the particle methods and to describe phenomena beyond the scopeof the mean-field equations.
基金L.Li was supported by National Natural Science Foundation of China(Grant No.31571071)Shanghai Sailing Program 19YF1421300+2 种基金J.-G.Liu was supported in part by DMS-2106988Z.Zhou was supported by the National Key R&D Program of China,Project Number 2021YFA001200the NSFC,grant number 12171013.
文摘Although interest in numerical approximations of the water wave equationgrows in recent years, the lack of rigorous analysis of its time discretization inhibits thedesign of more efficient algorithms. In practice of water wave simulations, the tradeoff between efficiency and stability has been a challenging problem. Thus to shed lighton the stability condition for simulations of water waves, we focus on a model simpli-fied from the water wave equation of infinite depth. This model preserves two mainproperties of the water wave equation: non-locality and hyperbolicity. For the constantcoefficient case, we conduct systematic stability studies of the fully discrete approximation of such systems with the Fourier spectral approximation in space and generalRunge-Kutta methods in time. As a result, an optimal time discretization strategy isprovided in the form of a modified CFL condition, i.e. ∆t = O(√∆x). Meanwhile,the energy stable property is established for certain explicit Runge-Kutta methods.This CFL condition solves the problem of efficiency and stability: it allows numericalschemes to stay stable while resolves oscillations at the lowest requirement, which onlyproduces acceptable computational load. In the variable coefficient case, the convergence of the semi-discrete approximation of it is presented, which naturally connectsto the water wave equation. Analogue of these results for the water wave equationof finite depth is also discussed. To validate these theoretic observation, extensive numerical tests have been performed to verify the stability conditions. Simulations of thesimplified hyperbolic model in the high frequency regime and the water wave equation are also provided.
