We propose a quasi-one-dimensional non-Hermitian Creutz ladder with an entirely flat spectrum by introducing alternating gain and loss components while maintaining inversion symmetry.Destructive interference generates...We propose a quasi-one-dimensional non-Hermitian Creutz ladder with an entirely flat spectrum by introducing alternating gain and loss components while maintaining inversion symmetry.Destructive interference generates a flat spectrum at the exceptional point,where the Creutz ladder maintains coalesced and degenerate eigenvalues with compact localized states distributed in a single plaquette.All excitations are completely confined within the localization area,unaffected by gain and loss.Single-site excitations exhibit nonunitary dynamics with intensities increasing due to level coalescence,while multiple-site excitations may display oscillating or constant intensities at the exceptional point.These results provide insights into the fascinating dynamics of non-Hermitian localization,where level coalescence and degeneracy coexist at the exceptional point.展开更多
We study the nonlinear perturbation of a high-order exceptional point(EP)of the order equal to the system site number L in a Hatano-Nelson model with unidirectional hopping and Kerr nonlinearity.Notably,we find a clas...We study the nonlinear perturbation of a high-order exceptional point(EP)of the order equal to the system site number L in a Hatano-Nelson model with unidirectional hopping and Kerr nonlinearity.Notably,we find a class of discrete breathers that aggregate to one boundary,here named as skin discrete breathers(SDBs).The nonlinear spectrum of these SDBs shows a hierarchical power-law scaling near the EP.Specifically,the response of nonlinear energy to the perturbation is given by E_(m)∝Γ~(α_(m)),whereα_(m)=3^(m-1)is the power with m=1,...,L labeling the nonlinear energy bands.This is in sharp contrast to the L-th root of a linear perturbation in general.These SDBs decay in a double-exponential manner,unlike the edge states or skin modes in linear systems,which decay exponentially.Furthermore,these SDBs can survive over the full range of nonlinearity strength and are continuously connected to the self-trapped states in the limit of large nonlinearity.They are also stable,as confirmed by a defined nonlinear fidelity of an adiabatic evolution from the stability analysis.As nonreciprocal nonlinear models may be experimentally realized in various platforms,such as the classical platform of optical waveguides,where Kerr nonlinearity is naturally present,and the quantum platform of optical lattices with Bose-Einstein condensates,our analytical results may inspire further exploration of the interplay between nonlinearity and non-Hermiticity,particularly on high-order EPs,and benchmark the relevant simulations.展开更多
Elastic wave absorption at subwavelength scale is of significance in many engineering applications.Non-Hermitian metamaterials show the ability in high-efficiency wave absorption.However,the single functionality of me...Elastic wave absorption at subwavelength scale is of significance in many engineering applications.Non-Hermitian metamaterials show the ability in high-efficiency wave absorption.However,the single functionality of metamaterials is an important limitation on their practical applications for lack of tunability and reconfigurability.Here,we propose a tunable and reconfigurable non-Hermitian piezoelectric metamaterial bar,in which piezoelectric bars connect with resonant circuits,to achieve asymmetric unidirectional perfect absorption(UPA)and symmetric bidirectional perfect absorption(PA)at low frequencies.The two functions can be arbitrarily switched by rearranging shunted circuits.Based on the reverberation-ray matrix(RRM)method,an approach is provided to achieve UPA by setting an exceptional point(EP)in the coupled resonant bandgap.By using the transfer matrix method(TMM)and the finite element method(FEM),it is observed that a non-Hermitian pseudo-band forms between two resonant bandgaps,and the EP appears at the bottom of the pseudo-band.In addition,the genetic algorithm is used to accurately and efficiently design the shunted circuits for desired low-frequency UPA and PA.The present work may provide new strategies for vibration suppression and guided waves manipulation in wide potential applications.展开更多
Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming ...Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming and thermal degradation in permafrost or seasonally frozen ground(SFG)has long been recognized.Still,a predictive relationship between historical wetting under warming climate conditions and frozen ground has not yet been well demonstrated,despite the expectation that it will become even more important because precipitation over the QTP has been projected to increase continuously in the near future.This study investigates the response of the thermal regime to historical wetting in both permafrost and SFG areas and examines their relationships separately using the Community Land Surface Model version 4.5.Results show that wetting before the 1990s across the QTP mainly cooled the permafrost body in the arid and semiarid zones,with significant correlation coefficients of 0.60 and 0.48,respectively.Precipitation increased continually at the rate of 6.16 mm decade–1 in the arid zone after the 1990s but had a contrasting warming effect on permafrost through a significant shortening of the thawing duration within the active layer.However,diminished rainfall in the humid zone after the 1990s also significantly extended the thawing duration of SFG.The relationship between the ground thawing index and precipitation was significantly negatively correlated(−0.75).The dual effects of wetting on the thermal dynamics of the QTP are becoming critical because of the projected increases in future precipitation.展开更多
The demand for effective interventions to improve domain-specific academic outcomes for individuals with special needs at either end of the spectrum has existed for some time.Since the earlier contributions to the lit...The demand for effective interventions to improve domain-specific academic outcomes for individuals with special needs at either end of the spectrum has existed for some time.Since the earlier contributions to the literature documenting gifted individuals who were simultaneously exhibiting disabilities,there has been some progress in our understanding.We now know that in individuals with both gifts and disabilities,potentially,either or both of the exceptionalities can obscure the effects of the other,which significantly delays the average time to receive a diagnosis.Such delays in diagnosis detrimentally impact the the form of effective interventions without a diagnosis.The purpose of this paper is t quality of life across various domains because there can be no opportunity to receive help in o determine whether effective interventions exist to improve domain-specific(i.e.,social,emotional,or academic)outcomes for people with both gifts and disabilities.A query was performed using evidence databases TRIP and PDQ for“twice-exceptional,”“Giftedness,”“Disability,”and“intervention.”The four most relevant,freely available studies in English were selected for critique.Despite identifying potential threats to validity among the studies,methodological similarities among them were strong enough to confidently conclude that not only do effective interventions exist for the population of gifted with ADHD,but the outcomes of these interventions may also carry over into other domains resulting in indirect effects.展开更多
During the period of different changes in the global situation,the stock indexes of China,the United States,and the United Kingdom all showed different trends.Overall,during the outbreak of the epidemic,they all recei...During the period of different changes in the global situation,the stock indexes of China,the United States,and the United Kingdom all showed different trends.Overall,during the outbreak of the epidemic,they all received a huge impact,and due to the different policies and coping strategies of various countries,the follow-up performance also varies greatly.Brexit has only had a slight impact on the British domestic market in a short period time,and China and the United States have prepared for investment in the new market after Brexit,which has also caused the corresponding market index to perform better before the follow-up.Due to the differences in the main market targets and the differences in the geographical location of countries,the negative impact on the British market was more obvious during the Russia-Ukraine conflict,while the stock indexes of China and the United States were relatively stable and even showed an upward trend.It can be seen from the data analysis that the markets in different countries are affected by time differently.With the growing correlation between the markets of various countries,investors should pay more attention to the global situation and the policy orientation of different countries.Considering risk diversification while taking policy dividends helps to obtain stable returns.展开更多
Objective:To explore and analyze the effect of nebulized budesonide inhalation on children with asthma and its influence on immune indexes.Methods:300 children who were with asthma admitted to the Pediatric Respirator...Objective:To explore and analyze the effect of nebulized budesonide inhalation on children with asthma and its influence on immune indexes.Methods:300 children who were with asthma admitted to the Pediatric Respiratory Department of our hospital from January 2021 to January 2023 were selected as the research subjects.The patients were divided into a nebulization group(n=150)and a reference group(n=150)by drawing lots.The nebulization group received routine treatment along with budesonide nebulization inhalation therapy,while the reference group only received routine treatment.The treatment effect,the immune indicators,the time taken for the disappearance of symptoms,and the pulmonary function indicators of both groups were compared.Results:The total efficacy of treatment received in the nebulization group was significantly higher than that in the reference group(P<0.05).Before treatment,there was no statistically significant difference in the CD4^(+),CD8^(+),CD4^(+)/CD8^(+),between the two groups(P>0.05);after treatment,the nebulization group’s CD4^(+),CD8^(+),CD4^(+)/CD8^(+)and other immune indicators were significantly better than the reference group(P<0.05).The time taken for the disappearance of symptoms like wheezing,coughing,crackles,shortness of breath,and other symptoms in the nebulization group was significantly shorter than in the reference group(P<0.05).Before treatment,there was no statistically significant difference in the pulmonary function indexes such as FEV1,PEF,and FVC between the two groups(P>0.05);after treatment,the pulmonary function indexes of the patients in the nebulization group were significantly better than those in the reference group(P<0.05).Conclusion:Nebulized budesonide inhalation therapy has shown significant efficacy in the treatment of pediatric asthma,with notable improvements in immune indicators.Therefore,it is worthy of recommendation and further promotion.展开更多
Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of rai...Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.展开更多
大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知...大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知和对其指标的量化描述。本文作者通过承担国家重点研发计划“区域大气氧化能力与空气质量的定量关系及调控原理”研究等项目,从大气化学基本理论入手,对AOC开展了系列研究,并在其量化表达方面取得了突破性进展。本文将围绕“大气氧化能力量化研究”这一科学问题,对这些进展进行简要的描述。首先在深入认知AOC内涵的基础上,分别从大气化学的热力学和动力学基本原理出发,构建了大气氧化能力表观指数(AOIe)和潜势指数(AOIp),并通过二者归一化指数日变化闭合研究,发现了非均相化学过程对AOC的贡献不容忽视。随着PM2.5污染的加重,无论夏季还是冬季,AOIe亦随之增加,但在冬季AOIp则出现了相反的情景,表现出AOIp的变化受气象条件的影响更大。AOC闭合研究思路用于大气OH自由基的储库分子HONO“未知源”研究,发现了北京大气HONO的重要非均相来源,阐释了MCM(Master Chemical Mechanism)机制对冬季AOC低估的重要原因。AOIp用于预测我国大气臭氧污染潜势格局,发现臭氧光化学生成表观潜势(AOIp_O_(3))与NO_(2)的光解系数[J(NO_(2))]直接相关,全国J(NO_(2))的年均值为4.39×10^(-3)s^(-1),高值区主要分布在四川、贵州、重庆和湖南等地。与其他化学反应氧化性指数对比,AOIe与AOIp组合指数更具准确性、普适性和实用性,可评价已发生的污染过程AOC的变化,亦可预测城市或区域重污染发生的可能性及其变化和格局。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12222504 and 11975128).
文摘We propose a quasi-one-dimensional non-Hermitian Creutz ladder with an entirely flat spectrum by introducing alternating gain and loss components while maintaining inversion symmetry.Destructive interference generates a flat spectrum at the exceptional point,where the Creutz ladder maintains coalesced and degenerate eigenvalues with compact localized states distributed in a single plaquette.All excitations are completely confined within the localization area,unaffected by gain and loss.Single-site excitations exhibit nonunitary dynamics with intensities increasing due to level coalescence,while multiple-site excitations may display oscillating or constant intensities at the exceptional point.These results provide insights into the fascinating dynamics of non-Hermitian localization,where level coalescence and degeneracy coexist at the exceptional point.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1405304)the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2019B030330001)the Guangdong Provincial Key Laboratory(Grant No.2020B1212060066)。
文摘We study the nonlinear perturbation of a high-order exceptional point(EP)of the order equal to the system site number L in a Hatano-Nelson model with unidirectional hopping and Kerr nonlinearity.Notably,we find a class of discrete breathers that aggregate to one boundary,here named as skin discrete breathers(SDBs).The nonlinear spectrum of these SDBs shows a hierarchical power-law scaling near the EP.Specifically,the response of nonlinear energy to the perturbation is given by E_(m)∝Γ~(α_(m)),whereα_(m)=3^(m-1)is the power with m=1,...,L labeling the nonlinear energy bands.This is in sharp contrast to the L-th root of a linear perturbation in general.These SDBs decay in a double-exponential manner,unlike the edge states or skin modes in linear systems,which decay exponentially.Furthermore,these SDBs can survive over the full range of nonlinearity strength and are continuously connected to the self-trapped states in the limit of large nonlinearity.They are also stable,as confirmed by a defined nonlinear fidelity of an adiabatic evolution from the stability analysis.As nonreciprocal nonlinear models may be experimentally realized in various platforms,such as the classical platform of optical waveguides,where Kerr nonlinearity is naturally present,and the quantum platform of optical lattices with Bose-Einstein condensates,our analytical results may inspire further exploration of the interplay between nonlinearity and non-Hermiticity,particularly on high-order EPs,and benchmark the relevant simulations.
基金the National Natural Science Foundation of China(Nos.11991033 and 11890681)。
文摘Elastic wave absorption at subwavelength scale is of significance in many engineering applications.Non-Hermitian metamaterials show the ability in high-efficiency wave absorption.However,the single functionality of metamaterials is an important limitation on their practical applications for lack of tunability and reconfigurability.Here,we propose a tunable and reconfigurable non-Hermitian piezoelectric metamaterial bar,in which piezoelectric bars connect with resonant circuits,to achieve asymmetric unidirectional perfect absorption(UPA)and symmetric bidirectional perfect absorption(PA)at low frequencies.The two functions can be arbitrarily switched by rearranging shunted circuits.Based on the reverberation-ray matrix(RRM)method,an approach is provided to achieve UPA by setting an exceptional point(EP)in the coupled resonant bandgap.By using the transfer matrix method(TMM)and the finite element method(FEM),it is observed that a non-Hermitian pseudo-band forms between two resonant bandgaps,and the EP appears at the bottom of the pseudo-band.In addition,the genetic algorithm is used to accurately and efficiently design the shunted circuits for desired low-frequency UPA and PA.The present work may provide new strategies for vibration suppression and guided waves manipulation in wide potential applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41905008, 41975007, and 42075081)the Innovation and Entrepreneurship Training Program for College Students of Chengdu University of Information Technology (CUIT) (202210621003, 202210621039, 202110621015)provided by the Scientific Research Foundation of CUIT (KYTZ202126)
文摘Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming and thermal degradation in permafrost or seasonally frozen ground(SFG)has long been recognized.Still,a predictive relationship between historical wetting under warming climate conditions and frozen ground has not yet been well demonstrated,despite the expectation that it will become even more important because precipitation over the QTP has been projected to increase continuously in the near future.This study investigates the response of the thermal regime to historical wetting in both permafrost and SFG areas and examines their relationships separately using the Community Land Surface Model version 4.5.Results show that wetting before the 1990s across the QTP mainly cooled the permafrost body in the arid and semiarid zones,with significant correlation coefficients of 0.60 and 0.48,respectively.Precipitation increased continually at the rate of 6.16 mm decade–1 in the arid zone after the 1990s but had a contrasting warming effect on permafrost through a significant shortening of the thawing duration within the active layer.However,diminished rainfall in the humid zone after the 1990s also significantly extended the thawing duration of SFG.The relationship between the ground thawing index and precipitation was significantly negatively correlated(−0.75).The dual effects of wetting on the thermal dynamics of the QTP are becoming critical because of the projected increases in future precipitation.
文摘The demand for effective interventions to improve domain-specific academic outcomes for individuals with special needs at either end of the spectrum has existed for some time.Since the earlier contributions to the literature documenting gifted individuals who were simultaneously exhibiting disabilities,there has been some progress in our understanding.We now know that in individuals with both gifts and disabilities,potentially,either or both of the exceptionalities can obscure the effects of the other,which significantly delays the average time to receive a diagnosis.Such delays in diagnosis detrimentally impact the the form of effective interventions without a diagnosis.The purpose of this paper is t quality of life across various domains because there can be no opportunity to receive help in o determine whether effective interventions exist to improve domain-specific(i.e.,social,emotional,or academic)outcomes for people with both gifts and disabilities.A query was performed using evidence databases TRIP and PDQ for“twice-exceptional,”“Giftedness,”“Disability,”and“intervention.”The four most relevant,freely available studies in English were selected for critique.Despite identifying potential threats to validity among the studies,methodological similarities among them were strong enough to confidently conclude that not only do effective interventions exist for the population of gifted with ADHD,but the outcomes of these interventions may also carry over into other domains resulting in indirect effects.
文摘During the period of different changes in the global situation,the stock indexes of China,the United States,and the United Kingdom all showed different trends.Overall,during the outbreak of the epidemic,they all received a huge impact,and due to the different policies and coping strategies of various countries,the follow-up performance also varies greatly.Brexit has only had a slight impact on the British domestic market in a short period time,and China and the United States have prepared for investment in the new market after Brexit,which has also caused the corresponding market index to perform better before the follow-up.Due to the differences in the main market targets and the differences in the geographical location of countries,the negative impact on the British market was more obvious during the Russia-Ukraine conflict,while the stock indexes of China and the United States were relatively stable and even showed an upward trend.It can be seen from the data analysis that the markets in different countries are affected by time differently.With the growing correlation between the markets of various countries,investors should pay more attention to the global situation and the policy orientation of different countries.Considering risk diversification while taking policy dividends helps to obtain stable returns.
文摘Objective:To explore and analyze the effect of nebulized budesonide inhalation on children with asthma and its influence on immune indexes.Methods:300 children who were with asthma admitted to the Pediatric Respiratory Department of our hospital from January 2021 to January 2023 were selected as the research subjects.The patients were divided into a nebulization group(n=150)and a reference group(n=150)by drawing lots.The nebulization group received routine treatment along with budesonide nebulization inhalation therapy,while the reference group only received routine treatment.The treatment effect,the immune indicators,the time taken for the disappearance of symptoms,and the pulmonary function indicators of both groups were compared.Results:The total efficacy of treatment received in the nebulization group was significantly higher than that in the reference group(P<0.05).Before treatment,there was no statistically significant difference in the CD4^(+),CD8^(+),CD4^(+)/CD8^(+),between the two groups(P>0.05);after treatment,the nebulization group’s CD4^(+),CD8^(+),CD4^(+)/CD8^(+)and other immune indicators were significantly better than the reference group(P<0.05).The time taken for the disappearance of symptoms like wheezing,coughing,crackles,shortness of breath,and other symptoms in the nebulization group was significantly shorter than in the reference group(P<0.05).Before treatment,there was no statistically significant difference in the pulmonary function indexes such as FEV1,PEF,and FVC between the two groups(P>0.05);after treatment,the pulmonary function indexes of the patients in the nebulization group were significantly better than those in the reference group(P<0.05).Conclusion:Nebulized budesonide inhalation therapy has shown significant efficacy in the treatment of pediatric asthma,with notable improvements in immune indicators.Therefore,it is worthy of recommendation and further promotion.
基金funded by the National Key R&Dprogram of China[Grant No.2022YFB2603302]the Science and Technology Research and Development Program of China State Railway Group Co.,Ltd[Grant No.K2022G015]the Fund Project of China Academy of Railway Sciences Corporation Limited[Grant No.2022YJ305].
文摘Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.
文摘大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知和对其指标的量化描述。本文作者通过承担国家重点研发计划“区域大气氧化能力与空气质量的定量关系及调控原理”研究等项目,从大气化学基本理论入手,对AOC开展了系列研究,并在其量化表达方面取得了突破性进展。本文将围绕“大气氧化能力量化研究”这一科学问题,对这些进展进行简要的描述。首先在深入认知AOC内涵的基础上,分别从大气化学的热力学和动力学基本原理出发,构建了大气氧化能力表观指数(AOIe)和潜势指数(AOIp),并通过二者归一化指数日变化闭合研究,发现了非均相化学过程对AOC的贡献不容忽视。随着PM2.5污染的加重,无论夏季还是冬季,AOIe亦随之增加,但在冬季AOIp则出现了相反的情景,表现出AOIp的变化受气象条件的影响更大。AOC闭合研究思路用于大气OH自由基的储库分子HONO“未知源”研究,发现了北京大气HONO的重要非均相来源,阐释了MCM(Master Chemical Mechanism)机制对冬季AOC低估的重要原因。AOIp用于预测我国大气臭氧污染潜势格局,发现臭氧光化学生成表观潜势(AOIp_O_(3))与NO_(2)的光解系数[J(NO_(2))]直接相关,全国J(NO_(2))的年均值为4.39×10^(-3)s^(-1),高值区主要分布在四川、贵州、重庆和湖南等地。与其他化学反应氧化性指数对比,AOIe与AOIp组合指数更具准确性、普适性和实用性,可评价已发生的污染过程AOC的变化,亦可预测城市或区域重污染发生的可能性及其变化和格局。
