In this paper, we study the stability of locally rotationally symmetric （LRS） Bianchi I universe model in f（T） gravity through phase space analysis. We assume that the f（T） gravity can be treated as effective da...In this paper, we study the stability of locally rotationally symmetric （LRS） Bianchi I universe model in f（T） gravity through phase space analysis. We assume that the f（T） gravity can be treated as effective dark energy behaving like perfect fluid, and suggest that there are interactions between pressureless matter as well as dark energy. We construct the corresponding autonomous system of equations to check the stability of the model for non phantom, vacuum and phantom phases. It is concluded that critical points remain more stable in phantom phase as compared to non phantom and vacuum cases. Finaily, we discuss the cosmological behavior of the model through some cosmological parameters.展开更多
Using a dynamical system method,we study a Friedmann-Robertson-Walker(FRW)cosmological model within the context of f(Q,C)gravity,where Q is the non-metricity scalar and C represents the boundary term,considering both ...Using a dynamical system method,we study a Friedmann-Robertson-Walker(FRW)cosmological model within the context of f(Q,C)gravity,where Q is the non-metricity scalar and C represents the boundary term,considering both interacting and non-interacting models.A set of autonomous equations is derived,and solutions are calculated accordingly.We assess the critical points obtained from these equations,identify their characteristic values,and explore the physical interpretation of the phase space for this system.Two types of f(Q,C)are assumed:(i)f(Q,C)=Q+αQ+βClogC and(i)f(Q,C)=Q+αQ+β/C,where α and β are the parameters.In Model I,we obtain two stable critical points,whereas in Model Il,we identify three stable critical points for both interacting and non-interacting models.We examine the behavior of phase space trajectories at every critical point.We calculate the values of the physical parameters for both systems at each critical point,indicating the accelerated expansion of the Universe.展开更多
In this paper,the image space analysis (for short,ISA) is employed to investigate variational in- equalities (for short,VI) with cone constraints.Linear separation for VI with cone constraints is characterized by usin...In this paper,the image space analysis (for short,ISA) is employed to investigate variational in- equalities (for short,VI) with cone constraints.Linear separation for VI with cone constraints is characterized by using the normal cone to a regularization of the image,and saddle points of the generalized Lagrangian func- tion.Lagrangian-type necessary and sufficient optimality conditions for VI with cone constraints are presented by using a separation theorem.Gap functions and weak sharpness for VI with cone constraints are also investi- gated.Finally,the obtained results are applied to standard and time-dependent traffic equilibria introduced by Daniele,Maugeri and Oettli.展开更多
The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).A...The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).Alternatively,physical space analysis system(4D-PSAS)is proposed to reduce the computation cost,in which the 4D-Var problem is solved in physical space(i.e.,observation space).In this study,the conjugate gradient(CG)algorithm,implemented in the 4D-PSAS system is evaluated and it is found that the non-monotonic change of the gradient norm of 4D-PSAS cost function causes artificial oscillations of cost function in the iteration process.The reason of non-monotonic variation of gradient norm in 4D-PSAS is then analyzed.In order to overcome the non-monotonic variation of gradient norm,a new algorithm,Minimum Residual(MINRES)algorithm,is implemented in the process of assimilation iteration in this study.Our experimental results show that the improved 4D-PSAS with the MINRES algorithm guarantees the monotonic reduction of gradient norm of cost function,greatly improves the convergence properties of 4D-PSAS as well,and significantly restrains the numerical noises associated with the traditional 4D-PSAS system.展开更多
The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing g...The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing geological measurements are insufficient to obtain such information because the coal seam is typically deeply buried and the geological conditions are often complex.This paper introduces a cylindrical model for the gasification channel.The rock and soil masses are assumed to be homogeneous and isotropic and the effect of seepage on the temperature field was neglected.The theory of heat conduction was used to write the equation predicting the temperature field around the gasification channel.The idea of an excess temperature was introduced to solve the equations.Applying this model to UCG in the field for an influence radius,r,of 70 m gave the model parameters,u1,2,3...,of 2.4,5.5,8.7...By adjusting the radius(2,4,or 6 m) reasonable temperatures of the gasification channel were found for 4 m.The temperature distribution in the vertical direction,and the combustion volume,were also calculated.Comparison to field measurements shows that the results obtained from the proposed model are very close to practice.展开更多
We have examined an isotropic and homogeneous cosmological model in f(R,T^(φ))gravity,where R represents the Ricci scalar and T^(φ)exhibits the energy momentum tensor's trace.We examine the stability criteria by...We have examined an isotropic and homogeneous cosmological model in f(R,T^(φ))gravity,where R represents the Ricci scalar and T^(φ)exhibits the energy momentum tensor's trace.We examine the stability criteria by performing the dynamical system analysis for our model f(R,T^(φ))=R+2(a T^(φ)+b),where a and b are the constants.We derive a set of autonomous equations and find their solutions by assuming a flat potential V0.We assess the equilibrium points from these equations and find the eigenvalues.We analyze the physical interpretation of the phase space for this system.We obtain three stable equilibrium points.We also examine the interaction between the scalar field and dark energy,represented by Q=ψH_(ρde)and determine the equilibrium points for this interaction.We identify four stable equilibrium points for this interaction.We calculate the values of the physical parameters for both scenarios at each equilibrium point,indicating the Universe's accelerated expansion.展开更多
Under the macro background of rapid urbanization and social transformation in China,campus space renewal has become an important practice and carrier for the sustainable development of schools.The study on campus spac...Under the macro background of rapid urbanization and social transformation in China,campus space renewal has become an important practice and carrier for the sustainable development of schools.The study on campus space by big data and quantitative reflection of spatial distribution of applicable people in different areas of the campus can provide a certain scientific basis for campus space updating.West campus of Yangtze University is taken as research object.Based on cognitive map method,questionnaire survey method,behavior trajectory and correlation analysis method,the types and characteristics of campus space composition,campus satisfaction,usage and its relevance are analyzed.Research results show that ①the overall imageability of campus space is higher,which has a significantly positive correlation with the satisfaction of campus environment,and has no correlation with users’ behavior activities.The use frequency of non teaching areas varies greatly in different periods of time.②The correlation between the surrounding green vegetation and the image degree of campus landmarks is the most significant,and the coefficient is 0.886.③The correlation between spatial size suitability and regional image degree is the most significant,and the coefficient is 0.937.④The correlation between public activity facilities in the region and node image degree is the most significant,and the coefficient is 0.995.According to the research results,the corresponding solutions are put forward to provide scientific and quantitative reference suggestions for the renewal and transformation of the campus.展开更多
Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological me...Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.展开更多
Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper...Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper performs the spatial pattern analysis of the quantitative and structural changes of various landscapes at different altitudes, and uses the land use data in 1990, 2000, 2010 and 2015 to reveal how various land patterns have changed. The results show that, within the production-living-ecological space schema, the ecological space dominates Hengduan Mountains, while the production and living space was mainly distributed in south region. During 1990-2015, the production-living-ecological spatial changes had been gradually accelerated and the regional differences had become more prominent. The agricultural production space had continuously decreased by 1132.31 km^2, and the industrial and mining production space had rapidly increased by 281.4 km^2 during 1990-2015. The living space had steadily increased, and the ecological space had increased with fluctuations. The land space pattern in Hengduan Mountains was greatly restricted by the terrain, such as altitude and slope. The implementations of China Western Development Strategy and the Returning Farmland to Forest Program had favorably promoted the changes of land spatial pattern in Hengduan Mountains.展开更多
Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexi...Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexibility of bistatic platforms,resulting in kinds of models built independently among which there could be some similar even the same motion features.Comprehensive research on such systems in a more comprehensive and general point of view is required to address their difference and consistency.Property analysis of bistatic forwardlooking SAR with arbitrary geometry is achieved including stripmap and spotlight modes on airborne platform,missile-borne platform,and hybrid platform of both.Emphasis is placed on azimuth space variance of some key parameters significantly affecting the subsequent imaging processing,based on which the frequency spectra are further described and compared considering respective features of different platforms for frequency imaging algorithm developing.Simulation results confirm the effectiveness and correctness of our analysis.展开更多
The classification of coal resources generally is based on geometric factors and the complexity of geological structures. The classification has not considered coal quality factors such as ash content, sulphur content...The classification of coal resources generally is based on geometric factors and the complexity of geological structures. The classification has not considered coal quality factors such as ash content, sulphur content, caloric value. The development of international classification standards has required a geostatistical analysis for the estimation and classification of coal resources. The purpose of this research is to apply geostatistics method to determine optimal drill hole distance, and to analyze classification of coal resource based on data of coal quality and quantity. Based on global estimation variance （GEV） approach from geostatistics, relative error value was obtained. Drill hole spacing analysis （DHSA） results in optimal drill hole spacing on each coal seam for the coal resources classification. Estimation using kriging block results in the value of kriging relative error. Coal resources classification was based on relative error of 0-10% for measured resources, 10-20% for indicated resources and 〉 20% for inferred resources. Based on a case study in a coal field consisting of three coal seams, the geostatistical approach produced the smallest distance on seam-3 as the optimal borehole range in the research area. This classification yields a greater area of influence than the SNI standard on simple geological complexity.展开更多
Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors there...Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors therefore play a crucial role in defining the alternation of urban space--in particular, that of the centers. The main focus of this research article is on the methodology used in the survey and evaluation of ＂centralities＂ as well as their developments over the past four decades （1974-2014） in approaches to urban development that has been developed in Graz.~ The analysis has drawn on the four editions （＂evolution＂） of approaches to urban development as conceived by the city of Graz in order to examine their verbal characteristics in regard to centralities. At the same time, the analysis does not examine presentations of plans which exist in supplementary forms （e.g., explanatory reports and supplemented plans）--it restricts itself solely to the various plans set out in the STEKs.2 The highest degree of accuracy has been applied to the notion of ＂centralis＂ in approaches to urban development. The goal of the research project was to depict the modulation of the notion of ＂centrality＂ in the urban context as a space-forming dimension. Furthermore, it clearly shows the extent to which the notion of the ＂centre＂ （in the widest sense of the word） has become distanced from qualitative, spatial development and at the current time of urban development is experiencing a sort of Renaissance. In the field of ＂urban development＂, architectural references in the context of＂centrality＂ have scarcely been researched. This has led to the opening-up of a complex interdisciplinary research field. In order to make the complex architectural determinants of ＂centrality＂ more accessible to the participating disciplines, approaches to urban development have been explored in the form of a social and spatial analysis.展开更多
This paper presents the dynamical properties of a Rydberg hydrogen atom between two metal surfaces using phase space analysis methods. The dynamical behaviour of the excited hydrogen atom depends sensitively on the at...This paper presents the dynamical properties of a Rydberg hydrogen atom between two metal surfaces using phase space analysis methods. The dynamical behaviour of the excited hydrogen atom depends sensitively on the atom-surface distance d. There exists a critical atom-surface distance dc = 1586 a.u. When the atom-surface distance d is larger than the critical distance de, the image charge potential is less important than the Coulomb potential, the system is near-integrable and the electron motion is regular. As the distance d decreases, the system will tend to be non-integrable and unstable, and the electron might be captured by the metal surfaces.展开更多
The short-range wireless communication technology has advanced considerably and provides the feasibility of train-train(T2T)communication link in the communication-based train control system.The introduction of the T2...The short-range wireless communication technology has advanced considerably and provides the feasibility of train-train(T2T)communication link in the communication-based train control system.The introduction of the T2T link would reduce the headway and improve operational efficiency.Formal methods are system design techniques that use rigorously specified mathematical models to ensure all behaviors work as expected.And it is exactly the functional safety verification needed.Therefore,to deal with the functional safety verification of the T2T link,an untimed colored petri net model is first constructed.Secondly,the verification process is performed.Conclusions can be drawn from the state space report and the computation tree logic queries.Lastly,the model is parameterized,and then data log files are obtained for further performance measurement.Results show that the proposed criteria are satisfied and there are no defects in the basic design requirements.The transmission delay has considered the reconnection,transmission errors and the interruption.The probability of the delay lower than 150 ms accounts for 98.106%,which meets the specification and the previous field test.展开更多
Purpose： We present a systematic review of the literature concerning major aspects of science mapping to serve two primary purposes： First, to demonstrate the use of a science mapping approach to perform the review ...Purpose： We present a systematic review of the literature concerning major aspects of science mapping to serve two primary purposes： First, to demonstrate the use of a science mapping approach to perform the review so that researchers may apply the procedure to the review of a scientific domain of their own interest, and second, to identify major areas of research activities concerning science mapping, intellectual milestones in the development of key specialties, evolutionary stages of major specialties involved, and the dynamics of transitions from one specialty to another.Design/methodology/approach： We first introduce a theoretical framework of the evolution of a scientific specialty. Then we demonstrate a generic search strategy that can be used to construct a representative dataset of bibliographic records of a domain of research. Next, progressively synthesized co-citation networks are constructed and visualized to aid visual analytic studies of the domain＇s structural and dynamic patterns and trends. Finally, trajectories of citations made by particular types of authors and articles are presented to illustrate the predictive potential of the analytic approach.Findings： The evolution of the science mapping research involves the development of a number of interrelated specialties. Four major specialties are discussed in detail in terms of four evolutionary stages： conceptualization, tool construction, application, and codification. Underlying connections between major specialties are also explored. The predictive analysis demonstrates citations trajectories of potentially transformative contributions.Research limitations： The systematic review is primarily guided by citation patterns in the dataset retrieved from the literature. The scope of the data is limited by the source of the retrieval, i.e. the Web of Science, and the composite query used. An iterative query refinement is possible if one would like to improve the data quality, although the current approach serves our purpose adequately. More in-depth analyses of each specialty would be more revealing by incorporating additional methods such as citation context analysis and studies of other aspects of scholarly publications.Practical implications： The underlying analytic process of science mapping serves many practical needs, notably bibliometric mapping, knowledge domain visualization, and visualization of scientific literature. In order to master such a complex process of science mapping, researchers often need to develop a diverse set of skills and knowledge that may span multiple disciplines. The approach demonstrated in this article provides a generic method for conducting a systematic review.Originality/value： Incorporating the evolutionary stages of a specialty into the visual analytic study of a research domain is innovative. It provides a systematic methodology for researchers to achieve a good understanding of how scientific fields evolve, to recognize potentially insightful patterns from visually encoded signs, and to synthesize various information so as to capture the state of the art of the domain.展开更多
Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial...Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial fundamental space filling mode approach was utilized. By using EHll mode, we have numerically solved the rate equations of a three-level pumping scheme for a fiber laser. The obtained results have shown a good agreement with the other experimental results, recently. The results have predicted amplifiers with gain efficiencies as high as 10 dB/mW.展开更多
In this paper,through the use of image space analysis,optimality conditions for a class of variational inequalities with cone constraints are proposed.By virtue of the nonlinear scalarization function,known as the Ger...In this paper,through the use of image space analysis,optimality conditions for a class of variational inequalities with cone constraints are proposed.By virtue of the nonlinear scalarization function,known as the Gerstewitz function,three nonlinear weak separation functions,two nonlinear regular weak separation functions and a nonlinear strong separation function are introduced.According to nonlinearseparation functions,some optimality conditions of the weak and strong alternative for variational inequalities with cone constraints are derived.展开更多
Generating compact and effective numerical representations of data is a fundamental step for many machine learning tasks.Traditionally,handcrafted features are used but as deep learning starts to show its potential,us...Generating compact and effective numerical representations of data is a fundamental step for many machine learning tasks.Traditionally,handcrafted features are used but as deep learning starts to show its potential,using deep learning models to extract compact representations becomes a new trend.Among them,adopting vectors from the model’s latent space is the most popular.There are several studies focused on visual analysis of latent space in NLP and computer vision.However,relatively little work has been done for music information retrieval(MIR)especially incorporating visualization.To bridge this gap,we propose a visual analysis system utilizing Autoencoders to facilitate analysis and exploration of traditional Chinese music.Due to the lack of proper traditional Chinese music data,we construct a labeled dataset from a collection of pre-recorded audios and then convert them into spectrograms.Our system takes music features learned from two deep learning models(a fully-connected Autoencoder and a Long Short-Term Memory(LSTM)Autoencoder)as input.Through interactive selection,similarity calculation,clustering and listening,we show that the latent representations of the encoded data allow our system to identify essential music elements,which lay the foundation for further analysis and retrieval of Chinese music in the future.展开更多
Ptanning the design of the emergency department （ED） is a complex process. Hospital readers and architects must consider many complex and interdependent factors, including evolving market demands, patient volume, ca...Ptanning the design of the emergency department （ED） is a complex process. Hospital readers and architects must consider many complex and interdependent factors, including evolving market demands, patient volume, care models, operational processes, staffing, and medical equipment. The application of digital toots, such as discrete event simulation （DES） and space syntax analysis （SSA）, arrows hospital administrators and designers to quantitativety and objectively optimize their facilities. This paper presents a case study that utitized both DES and SSA to optimize the care process and to design the space in an ED environment. DES was apptied in three phases： master planning, process improvement in the existing ED, and designing the new ED. SSA was used to compare the new design with the existing layout to evatuate the effectiveness of the new design in supporting visuat surveiltance and care coordination. This case study demonstrates that DES and SSA are effective toots for facilitating decision-making retated to design, reducing capital and operational costs, and improving organizational performance. DES focuses on operational processes and care flow. SSA complements DES with its strength in linking space to human behavior. Combining both tools can lead to high-performance ED design and can extend to broad applications in health care.展开更多
The article follows Max Weber's Comprehensive Sociology and uses the hermeneutic and iconological analysis sociological methods applied to plastic works(painting and sculpture),significant and representative of mo...The article follows Max Weber's Comprehensive Sociology and uses the hermeneutic and iconological analysis sociological methods applied to plastic works(painting and sculpture),significant and representative of modern and late modern art.Starting from these theoretical and methodological bases,it pursues three specific objectives:to analyze the construction of space in plastic art,to verify how this theme has evolved in artistic practices from the first modernity to the second and to verify the way in which the complementary visual language the conceptual of contemporary sociological theory.In this regard,the analysis and interpretation of the eleven selected works reveals three important consequences of the modern influence on space,gradually emptied of meaning and replaced by non-places:its conversion into merchandise,its loss of solidity and stability and the confusion that occurs in it between reality and its representation.Consequently,the implicit content converges with the essential postulates of the sociologists who have approached the subject of space,although it goes further because the foray into the iconographic hermeneutics of these works puts an image to the conceptual theoretical discourses of the sociologists,inaway that visual language complements and enriches,with more emotional and sensitive nuances Therefore our discipline begins to overcome a traditional deficit,in that it moves from the essential rationality that structures its origin and turns towards a greater coupling of the emotional and sensitive social plane.展开更多
文摘In this paper, we study the stability of locally rotationally symmetric （LRS） Bianchi I universe model in f（T） gravity through phase space analysis. We assume that the f（T） gravity can be treated as effective dark energy behaving like perfect fluid, and suggest that there are interactions between pressureless matter as well as dark energy. We construct the corresponding autonomous system of equations to check the stability of the model for non phantom, vacuum and phantom phases. It is concluded that critical points remain more stable in phantom phase as compared to non phantom and vacuum cases. Finaily, we discuss the cosmological behavior of the model through some cosmological parameters.
文摘Using a dynamical system method,we study a Friedmann-Robertson-Walker(FRW)cosmological model within the context of f(Q,C)gravity,where Q is the non-metricity scalar and C represents the boundary term,considering both interacting and non-interacting models.A set of autonomous equations is derived,and solutions are calculated accordingly.We assess the critical points obtained from these equations,identify their characteristic values,and explore the physical interpretation of the phase space for this system.Two types of f(Q,C)are assumed:(i)f(Q,C)=Q+αQ+βClogC and(i)f(Q,C)=Q+αQ+β/C,where α and β are the parameters.In Model I,we obtain two stable critical points,whereas in Model Il,we identify three stable critical points for both interacting and non-interacting models.We examine the behavior of phase space trajectories at every critical point.We calculate the values of the physical parameters for both systems at each critical point,indicating the accelerated expansion of the Universe.
基金supported by National Natural Science Foundation of China (Grants Nos. 60804065, 70831005)the Key Project of Chinese Ministry of Education (Grant No. 211163)Sichuan Youth Science and Technology Foundation and the Research Foundation of China West Normal University (Grant No. 08B075)
文摘In this paper,the image space analysis (for short,ISA) is employed to investigate variational in- equalities (for short,VI) with cone constraints.Linear separation for VI with cone constraints is characterized by using the normal cone to a regularization of the image,and saddle points of the generalized Lagrangian func- tion.Lagrangian-type necessary and sufficient optimality conditions for VI with cone constraints are presented by using a separation theorem.Gap functions and weak sharpness for VI with cone constraints are also investi- gated.Finally,the obtained results are applied to standard and time-dependent traffic equilibria introduced by Daniele,Maugeri and Oettli.
基金The National Key Research and Development Program of China under contract Nos 2017YFC1501803 and2018YFC1506903the National Natural Science Foundation of China under contract Nos 91730304,41475021 and 41575026
文摘The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).Alternatively,physical space analysis system(4D-PSAS)is proposed to reduce the computation cost,in which the 4D-Var problem is solved in physical space(i.e.,observation space).In this study,the conjugate gradient(CG)algorithm,implemented in the 4D-PSAS system is evaluated and it is found that the non-monotonic change of the gradient norm of 4D-PSAS cost function causes artificial oscillations of cost function in the iteration process.The reason of non-monotonic variation of gradient norm in 4D-PSAS is then analyzed.In order to overcome the non-monotonic variation of gradient norm,a new algorithm,Minimum Residual(MINRES)algorithm,is implemented in the process of assimilation iteration in this study.Our experimental results show that the improved 4D-PSAS with the MINRES algorithm guarantees the monotonic reduction of gradient norm of cost function,greatly improves the convergence properties of 4D-PSAS as well,and significantly restrains the numerical noises associated with the traditional 4D-PSAS system.
基金supported by a grant from the Major State Basic Research and Development Program of China (No. 2007CB714102)sponsored by the Fundamental Research Funds for the Central Universities (No. 2009B00714)
文摘The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing geological measurements are insufficient to obtain such information because the coal seam is typically deeply buried and the geological conditions are often complex.This paper introduces a cylindrical model for the gasification channel.The rock and soil masses are assumed to be homogeneous and isotropic and the effect of seepage on the temperature field was neglected.The theory of heat conduction was used to write the equation predicting the temperature field around the gasification channel.The idea of an excess temperature was introduced to solve the equations.Applying this model to UCG in the field for an influence radius,r,of 70 m gave the model parameters,u1,2,3...,of 2.4,5.5,8.7...By adjusting the radius(2,4,or 6 m) reasonable temperatures of the gasification channel were found for 4 m.The temperature distribution in the vertical direction,and the combustion volume,were also calculated.Comparison to field measurements shows that the results obtained from the proposed model are very close to practice.
基金funded by Researchers Supporting Project No.RSPD2025R733,King Saud University,Riyadh,Saudi Arabia。
文摘We have examined an isotropic and homogeneous cosmological model in f(R,T^(φ))gravity,where R represents the Ricci scalar and T^(φ)exhibits the energy momentum tensor's trace.We examine the stability criteria by performing the dynamical system analysis for our model f(R,T^(φ))=R+2(a T^(φ)+b),where a and b are the constants.We derive a set of autonomous equations and find their solutions by assuming a flat potential V0.We assess the equilibrium points from these equations and find the eigenvalues.We analyze the physical interpretation of the phase space for this system.We obtain three stable equilibrium points.We also examine the interaction between the scalar field and dark energy,represented by Q=ψH_(ρde)and determine the equilibrium points for this interaction.We identify four stable equilibrium points for this interaction.We calculate the values of the physical parameters for both scenarios at each equilibrium point,indicating the Universe's accelerated expansion.
文摘Under the macro background of rapid urbanization and social transformation in China,campus space renewal has become an important practice and carrier for the sustainable development of schools.The study on campus space by big data and quantitative reflection of spatial distribution of applicable people in different areas of the campus can provide a certain scientific basis for campus space updating.West campus of Yangtze University is taken as research object.Based on cognitive map method,questionnaire survey method,behavior trajectory and correlation analysis method,the types and characteristics of campus space composition,campus satisfaction,usage and its relevance are analyzed.Research results show that ①the overall imageability of campus space is higher,which has a significantly positive correlation with the satisfaction of campus environment,and has no correlation with users’ behavior activities.The use frequency of non teaching areas varies greatly in different periods of time.②The correlation between the surrounding green vegetation and the image degree of campus landmarks is the most significant,and the coefficient is 0.886.③The correlation between spatial size suitability and regional image degree is the most significant,and the coefficient is 0.937.④The correlation between public activity facilities in the region and node image degree is the most significant,and the coefficient is 0.995.According to the research results,the corresponding solutions are put forward to provide scientific and quantitative reference suggestions for the renewal and transformation of the campus.
基金supported by the National Natural Science Foundation of China,No.82274304(to YH)the Major Clinical Study Projects of Shanghai Shenkang Hospital Development Center,No.SHDC2020CR2046B(to YH)Shanghai Municipal Health Commission Talent Plan,No.2022LJ010(to YH).
文摘Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.
基金Major State Basic Research Development Program of China,No.2015CB452706
文摘Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper performs the spatial pattern analysis of the quantitative and structural changes of various landscapes at different altitudes, and uses the land use data in 1990, 2000, 2010 and 2015 to reveal how various land patterns have changed. The results show that, within the production-living-ecological space schema, the ecological space dominates Hengduan Mountains, while the production and living space was mainly distributed in south region. During 1990-2015, the production-living-ecological spatial changes had been gradually accelerated and the regional differences had become more prominent. The agricultural production space had continuously decreased by 1132.31 km^2, and the industrial and mining production space had rapidly increased by 281.4 km^2 during 1990-2015. The living space had steadily increased, and the ecological space had increased with fluctuations. The land space pattern in Hengduan Mountains was greatly restricted by the terrain, such as altitude and slope. The implementations of China Western Development Strategy and the Returning Farmland to Forest Program had favorably promoted the changes of land spatial pattern in Hengduan Mountains.
基金supported by the National Natural Science Foundation of China(6100121161303035+1 种基金61471283)the Fundamental Research Funds for the Central Universities(K5051202016)
文摘Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexibility of bistatic platforms,resulting in kinds of models built independently among which there could be some similar even the same motion features.Comprehensive research on such systems in a more comprehensive and general point of view is required to address their difference and consistency.Property analysis of bistatic forwardlooking SAR with arbitrary geometry is achieved including stripmap and spotlight modes on airborne platform,missile-borne platform,and hybrid platform of both.Emphasis is placed on azimuth space variance of some key parameters significantly affecting the subsequent imaging processing,based on which the frequency spectra are further described and compared considering respective features of different platforms for frequency imaging algorithm developing.Simulation results confirm the effectiveness and correctness of our analysis.
文摘The classification of coal resources generally is based on geometric factors and the complexity of geological structures. The classification has not considered coal quality factors such as ash content, sulphur content, caloric value. The development of international classification standards has required a geostatistical analysis for the estimation and classification of coal resources. The purpose of this research is to apply geostatistics method to determine optimal drill hole distance, and to analyze classification of coal resource based on data of coal quality and quantity. Based on global estimation variance （GEV） approach from geostatistics, relative error value was obtained. Drill hole spacing analysis （DHSA） results in optimal drill hole spacing on each coal seam for the coal resources classification. Estimation using kriging block results in the value of kriging relative error. Coal resources classification was based on relative error of 0-10% for measured resources, 10-20% for indicated resources and 〉 20% for inferred resources. Based on a case study in a coal field consisting of three coal seams, the geostatistical approach produced the smallest distance on seam-3 as the optimal borehole range in the research area. This classification yields a greater area of influence than the SNI standard on simple geological complexity.
文摘Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors therefore play a crucial role in defining the alternation of urban space--in particular, that of the centers. The main focus of this research article is on the methodology used in the survey and evaluation of ＂centralities＂ as well as their developments over the past four decades （1974-2014） in approaches to urban development that has been developed in Graz.~ The analysis has drawn on the four editions （＂evolution＂） of approaches to urban development as conceived by the city of Graz in order to examine their verbal characteristics in regard to centralities. At the same time, the analysis does not examine presentations of plans which exist in supplementary forms （e.g., explanatory reports and supplemented plans）--it restricts itself solely to the various plans set out in the STEKs.2 The highest degree of accuracy has been applied to the notion of ＂centralis＂ in approaches to urban development. The goal of the research project was to depict the modulation of the notion of ＂centrality＂ in the urban context as a space-forming dimension. Furthermore, it clearly shows the extent to which the notion of the ＂centre＂ （in the widest sense of the word） has become distanced from qualitative, spatial development and at the current time of urban development is experiencing a sort of Renaissance. In the field of ＂urban development＂, architectural references in the context of＂centrality＂ have scarcely been researched. This has led to the opening-up of a complex interdisciplinary research field. In order to make the complex architectural determinants of ＂centrality＂ more accessible to the participating disciplines, approaches to urban development have been explored in the form of a social and spatial analysis.
基金supported by the National Natural Science Foundation of China (Grant No. 10774093)the Natural Science Foundation of Shandong Province (Grant No. ZR2009FZ006)
文摘This paper presents the dynamical properties of a Rydberg hydrogen atom between two metal surfaces using phase space analysis methods. The dynamical behaviour of the excited hydrogen atom depends sensitively on the atom-surface distance d. There exists a critical atom-surface distance dc = 1586 a.u. When the atom-surface distance d is larger than the critical distance de, the image charge potential is less important than the Coulomb potential, the system is near-integrable and the electron motion is regular. As the distance d decreases, the system will tend to be non-integrable and unstable, and the electron might be captured by the metal surfaces.
基金National Natural Science Foundation of China(No.61963023)。
文摘The short-range wireless communication technology has advanced considerably and provides the feasibility of train-train(T2T)communication link in the communication-based train control system.The introduction of the T2T link would reduce the headway and improve operational efficiency.Formal methods are system design techniques that use rigorously specified mathematical models to ensure all behaviors work as expected.And it is exactly the functional safety verification needed.Therefore,to deal with the functional safety verification of the T2T link,an untimed colored petri net model is first constructed.Secondly,the verification process is performed.Conclusions can be drawn from the state space report and the computation tree logic queries.Lastly,the model is parameterized,and then data log files are obtained for further performance measurement.Results show that the proposed criteria are satisfied and there are no defects in the basic design requirements.The transmission delay has considered the reconnection,transmission errors and the interruption.The probability of the delay lower than 150 ms accounts for 98.106%,which meets the specification and the previous field test.
文摘Purpose： We present a systematic review of the literature concerning major aspects of science mapping to serve two primary purposes： First, to demonstrate the use of a science mapping approach to perform the review so that researchers may apply the procedure to the review of a scientific domain of their own interest, and second, to identify major areas of research activities concerning science mapping, intellectual milestones in the development of key specialties, evolutionary stages of major specialties involved, and the dynamics of transitions from one specialty to another.Design/methodology/approach： We first introduce a theoretical framework of the evolution of a scientific specialty. Then we demonstrate a generic search strategy that can be used to construct a representative dataset of bibliographic records of a domain of research. Next, progressively synthesized co-citation networks are constructed and visualized to aid visual analytic studies of the domain＇s structural and dynamic patterns and trends. Finally, trajectories of citations made by particular types of authors and articles are presented to illustrate the predictive potential of the analytic approach.Findings： The evolution of the science mapping research involves the development of a number of interrelated specialties. Four major specialties are discussed in detail in terms of four evolutionary stages： conceptualization, tool construction, application, and codification. Underlying connections between major specialties are also explored. The predictive analysis demonstrates citations trajectories of potentially transformative contributions.Research limitations： The systematic review is primarily guided by citation patterns in the dataset retrieved from the literature. The scope of the data is limited by the source of the retrieval, i.e. the Web of Science, and the composite query used. An iterative query refinement is possible if one would like to improve the data quality, although the current approach serves our purpose adequately. More in-depth analyses of each specialty would be more revealing by incorporating additional methods such as citation context analysis and studies of other aspects of scholarly publications.Practical implications： The underlying analytic process of science mapping serves many practical needs, notably bibliometric mapping, knowledge domain visualization, and visualization of scientific literature. In order to master such a complex process of science mapping, researchers often need to develop a diverse set of skills and knowledge that may span multiple disciplines. The approach demonstrated in this article provides a generic method for conducting a systematic review.Originality/value： Incorporating the evolutionary stages of a specialty into the visual analytic study of a research domain is innovative. It provides a systematic methodology for researchers to achieve a good understanding of how scientific fields evolve, to recognize potentially insightful patterns from visually encoded signs, and to synthesize various information so as to capture the state of the art of the domain.
文摘Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial fundamental space filling mode approach was utilized. By using EHll mode, we have numerically solved the rate equations of a three-level pumping scheme for a fiber laser. The obtained results have shown a good agreement with the other experimental results, recently. The results have predicted amplifiers with gain efficiencies as high as 10 dB/mW.
文摘In this paper,through the use of image space analysis,optimality conditions for a class of variational inequalities with cone constraints are proposed.By virtue of the nonlinear scalarization function,known as the Gerstewitz function,three nonlinear weak separation functions,two nonlinear regular weak separation functions and a nonlinear strong separation function are introduced.According to nonlinearseparation functions,some optimality conditions of the weak and strong alternative for variational inequalities with cone constraints are derived.
基金US Department of Energy Los Alamos National Laboratory contract 47145 and UT-Battelle LLC contract 4000159447 program manager Laura Biven.
文摘Generating compact and effective numerical representations of data is a fundamental step for many machine learning tasks.Traditionally,handcrafted features are used but as deep learning starts to show its potential,using deep learning models to extract compact representations becomes a new trend.Among them,adopting vectors from the model’s latent space is the most popular.There are several studies focused on visual analysis of latent space in NLP and computer vision.However,relatively little work has been done for music information retrieval(MIR)especially incorporating visualization.To bridge this gap,we propose a visual analysis system utilizing Autoencoders to facilitate analysis and exploration of traditional Chinese music.Due to the lack of proper traditional Chinese music data,we construct a labeled dataset from a collection of pre-recorded audios and then convert them into spectrograms.Our system takes music features learned from two deep learning models(a fully-connected Autoencoder and a Long Short-Term Memory(LSTM)Autoencoder)as input.Through interactive selection,similarity calculation,clustering and listening,we show that the latent representations of the encoded data allow our system to identify essential music elements,which lay the foundation for further analysis and retrieval of Chinese music in the future.
文摘Ptanning the design of the emergency department （ED） is a complex process. Hospital readers and architects must consider many complex and interdependent factors, including evolving market demands, patient volume, care models, operational processes, staffing, and medical equipment. The application of digital toots, such as discrete event simulation （DES） and space syntax analysis （SSA）, arrows hospital administrators and designers to quantitativety and objectively optimize their facilities. This paper presents a case study that utitized both DES and SSA to optimize the care process and to design the space in an ED environment. DES was apptied in three phases： master planning, process improvement in the existing ED, and designing the new ED. SSA was used to compare the new design with the existing layout to evatuate the effectiveness of the new design in supporting visuat surveiltance and care coordination. This case study demonstrates that DES and SSA are effective toots for facilitating decision-making retated to design, reducing capital and operational costs, and improving organizational performance. DES focuses on operational processes and care flow. SSA complements DES with its strength in linking space to human behavior. Combining both tools can lead to high-performance ED design and can extend to broad applications in health care.
文摘The article follows Max Weber's Comprehensive Sociology and uses the hermeneutic and iconological analysis sociological methods applied to plastic works(painting and sculpture),significant and representative of modern and late modern art.Starting from these theoretical and methodological bases,it pursues three specific objectives:to analyze the construction of space in plastic art,to verify how this theme has evolved in artistic practices from the first modernity to the second and to verify the way in which the complementary visual language the conceptual of contemporary sociological theory.In this regard,the analysis and interpretation of the eleven selected works reveals three important consequences of the modern influence on space,gradually emptied of meaning and replaced by non-places:its conversion into merchandise,its loss of solidity and stability and the confusion that occurs in it between reality and its representation.Consequently,the implicit content converges with the essential postulates of the sociologists who have approached the subject of space,although it goes further because the foray into the iconographic hermeneutics of these works puts an image to the conceptual theoretical discourses of the sociologists,inaway that visual language complements and enriches,with more emotional and sensitive nuances Therefore our discipline begins to overcome a traditional deficit,in that it moves from the essential rationality that structures its origin and turns towards a greater coupling of the emotional and sensitive social plane.
