The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface are...The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability.展开更多
In this review paper,we present a thorough investigation into the role of pavement technologies in advancing urban sustainability.Our analysis traverses the historical evolution of these technologies,meticulously eval...In this review paper,we present a thorough investigation into the role of pavement technologies in advancing urban sustainability.Our analysis traverses the historical evolution of these technologies,meticulously evaluating their socio-economic and environmental impacts,with a particular emphasis on their role in mitigating the urban heat island effect.The evaluation of pavement types and variables influencing pavement performance to be used in the multi-criteria decision-making(MCDM)framework to choose the optimal pavement application are at the heart of our research.Which serves to assess a spectrum of pavement options,revealing insights into the most effective and sustainable practices.By highlighting both the existing challenges and potential innovative solutions within thefield,this paper aims to offer a directional compass for future urban planning and infrastructural advancements.This review not only synthesizes the current state of knowledge but also aims to chart a course for future exploration,emphasizing the critical need for innovative and environmentally sensitive pavement tech-nologies in the creation of resilient and sustainable urban environments.展开更多
Since the implementation of the Action Plan for Air Pollution Prevention and Control , all regions of China have steadily promoted the prevention and control of air pollution and achieved results continuously. However...Since the implementation of the Action Plan for Air Pollution Prevention and Control , all regions of China have steadily promoted the prevention and control of air pollution and achieved results continuously. However, the atmospheric environment in key areas such as Beijing-Tianjin-Hebei region, the Yangtze River Delta region, and Fenwei Plain is still severe, and especially during the heating period heavy pollution occurs frequently, which has become the focus and difficulty of improving the quality of the atmospheric environment and is also the weakest link of China s air pollution control at present. How to alleviate air pollution, how to win the battle of pollution prevention and control, how to hold the fruits of the blue sky defense war, energy consumption is key.展开更多
Under the constrained condition induced by the eigenfunction expresson of the potential (u, v)T = (-[A2q, q], [A2p, p])T = f (q, p), the spatial part of the Lax pair of the Kaup-Newell equation is non linearized to be...Under the constrained condition induced by the eigenfunction expresson of the potential (u, v)T = (-[A2q, q], [A2p, p])T = f (q, p), the spatial part of the Lax pair of the Kaup-Newell equation is non linearized to be a completely integrable system (R2N, Adp AND dq, H = H-1) with the Hamiltonian H-1 = -[A3q, p]-1/2[A2p, p][A2q, q]. while the nonlinearization of the time part leads to its N-involutive system {H(m)}. The involutive solution of the compatible fsystem (H-1), (H(m)) is mapped by into the solution of the higher order Kaup-Newell equation.展开更多
Using the focal mechanism solutions of 24 moderately strong earthquakes in the northern Tianshan area,we carried out system cluster and stress field inversion analysis.The result indicates that,the focal mechanism sol...Using the focal mechanism solutions of 24 moderately strong earthquakes in the northern Tianshan area,we carried out system cluster and stress field inversion analysis.The result indicates that,the focal mechanism solutions of moderately strong earthquakes are mainly dip-slip reverse faulting in the northern Tianshan area.The principal rupture planes of earthquakes are NW-oriented.It is basically consistent with the strike of earthquake structure in its adjacent area.The direction of the principal compression stress P axis is nearly NS,and its inclination angle is small;while the inclination angle of the principal extensional stress T axis is large.It shows that the regional stress field is mainly controlled by the near-NS horizontal compressive stress.The direction of the maximum principal stress shows a gradation process of NNE-NS-NW from east to west.展开更多
Introduction
Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simul...Introduction
Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simultaneously, the fluid production rate, oil production rate and water injection rate has changed greatly so that the inflicts and problems from the established surface systems will become more obvious. Energy cost of production and running has increasing continuously. Capacity has been unbalance in systems and areas.展开更多
In the non-uniform stress field, the surrounding rock plastic zone of the circular roadway shows different shapes under the different confining pressure conditions. Based on the boundary shape characteristics of the p...In the non-uniform stress field, the surrounding rock plastic zone of the circular roadway shows different shapes under the different confining pressure conditions. Based on the boundary shape characteristics of the plastic zone, the characteristic radii of the plastic zone were proposed, namely the horizontal,longitudinal and medial axis radii, which could reflect the plastic zone shapes characteristics and classify the sizes of the key parts. On the theoretical basis of elastic-plastic mechanics, analytical solutions for the characteristic radii were obtained by theoretical deduction, and the relationships between the characteristic radii and key influencing factors were analyzed. Finally, the evaluation criterion of the circular roadway surrounding rock plastic zone shapes, evaluation criterion of the location of potential hazards caused by the roadway surrounding rock and evaluation critical points of roadway dynamic disasters based on characteristic radii were proposed. This work could provide a theoretical basis for stability analysis of the surrounding rock, support design, and guide the prevention and control of dynamic roadway disasters.展开更多
In the paper, we use the Central Moment Tensor (CMT) solution acquired by Harvard Univ. for the earthquakes occurred in Kurile Islands to analyze the consistent focal mechanism in the area and propose the idea of maki...In the paper, we use the Central Moment Tensor (CMT) solution acquired by Harvard Univ. for the earthquakes occurred in Kurile Islands to analyze the consistent focal mechanism in the area and propose the idea of making earthquake prediction based on the consistent parameter a of focal mechanism and stress field. The results from the study indicate that before Mw greater than or equal 7.5 earthquakes, the consistent parameter a decreases, which starts about 10-110 days and ends about 30-2 days before the great earthquakes. Although the phenomenon is not totally the same for individual earthquake, the difference is not large. Certainly, the phenomenon should be tested by time for its reliability. However, it should not be random that the focal mechanism of Mw greater than or equal 5.3 earthquakes are consistent successively with the stress field in an area of several hundreds kilometers in length. It should be a phenomenon of predictive significance. When the accumulated earthquake examples are sufficient, uniform judgment criteria and prediction principles can be stipulated then.展开更多
At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in...At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in current language teaching and provides some solutions.展开更多
There are large deltaic systems in the Triassic Yanchang Formation in the northern Shaanxi area of the Ordos Basin, and developed two sets of good source-reservoir-caprock assemblages and many sets of oil-bearing beds...There are large deltaic systems in the Triassic Yanchang Formation in the northern Shaanxi area of the Ordos Basin, and developed two sets of good source-reservoir-caprock assemblages and many sets of oil-bearing beds. Exploration experience demonstrates that the formation and distribution of the reservoir were controlled by the generative depression of the Yanchang Formation, and deltaic reservoir sand body is the material basis for large-scale oilfields. In addition, secondary laumontite in a low permeable area was dissolved and then a high permeable area was formed. The updip lithologic variety of reservoir sand bodies is favorable to the formation of subtle lithologic traps, and the deltaic reservoirs are characterized by large multi-beds of oil-generation and abundant hydrocarbon resources. In this paper, the petroleum geologic settings of the studied area are analyzed, and the accumulation characteristics and exploration methods of lithologic reservoirs are summarized. It is of theoretical significance for the study of the exploration theories of lithologic reservoirs, and also expedites the exploration steps of deltaic reservoirs in the northern Shaanxi area.展开更多
Taking 6 residential areas in Nyingchi of Tibet as research objects,from aesthetic effect,ecological function and leisure service,this paper established the evaluation indicator system for plant landscape in residenti...Taking 6 residential areas in Nyingchi of Tibet as research objects,from aesthetic effect,ecological function and leisure service,this paper established the evaluation indicator system for plant landscape in residential areas using AHP,and calculated the weight of indicators using the judgment matrix. Besides,it calculated the ideal solution and closeness degree of matrix using TOPSIS,and established the evaluation method and preference method for plant landscape in residential areas. The results show that the indicators of seasonal variation,environmental benefit and per capita green space mattered most in the landscape evaluation of residential areas. The richness of flowering plant is weak in the landscape evaluation. From the comprehensive evaluation of residential areas,Nyingchi Garden District and Xingfu District have excellent plant landscape,Jialong Garden District and Shangcheng Garden District have general plant landscape,and Sun City District and Niyang Garden District have poor plant landscape.展开更多
Abstract: Enhancing the efficiency of public services is essential to residents in mountainous areas. It is also important to promote sus- tainable development of these regions. Analysing residents' satisfaction wit...Abstract: Enhancing the efficiency of public services is essential to residents in mountainous areas. It is also important to promote sus- tainable development of these regions. Analysing residents' satisfaction with public services in mountainous areas can help in evaluating outcomes of fiscal investment and identifying potential coping approaches for improving public service efficiencies. The residents' satisfaction with public services and the factors that influence such satisfaction were examined in this study. A study of 12 towns located in the southwestern Sichuan Province was performed using an entropy-weighted analytic hierarchy process (EWAHP), the technique for order preference by similarity to ideal solution (TOPSIS) and Tobit regression methods. The results indicate that: 1) the spatial distribu- tion of satisfaction with public services is non-uniform, and the spatial distribution structure varies for different types of public services. 2) Residents' satisfaction with public services is influenced by both objective and subjective factors. Population density, economic dis- tance, social and cultural divisions and elevation are the major objective factors, whereas bounded rationality, the hierarchy of needs and service expectations are the main subjective factors. The most effective strategies for enhancing residents' satisfaction with public ser- vices are likely to be clustering the population, choosing supply centres with different public services, regulating the cultural division in ethnic minority towns, selecting supply priorities in accordance with residents' needs, implementing targeted intervention policies and establishing 'bottom-up' and 'top-down' integrated decision-making mechanisms. Keywords: mountainous areas; public services; residents' satisfaction; entropy-weighted analytic hierarchy process (EWAHP); technique for order preference by similarity to ideal solution (TOPSIS); Tobit regression; southwestern Sichuan Province展开更多
Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soi...Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas.However,little knowledge is available about the process and mechanisms of salt migration in frozen soil.This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments.The results are as follows.The solute concentrations of liquid and solid phases at the ice-liquid interface(C*_(L),C*_(S))gradually increased at the initial stage of freezing and remained approximately constant at the middle stage.As the ice-liquid interface advanced toward the system boundary,the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts.As a result,C*_(L)and C*_(S)rapidly increased at the final stage of freezing.The distribution characteristics of solutes in ice and the liquid phases before C*_(L)and C*_(S)became steady were mainly affected by the freezing temperature,initial concentrations,and particle-size distribution of media(quartz sand and kaolin).In detail,the lower the freezing temperature and the better the particle-size distribution of media,the higher the solute proportion in the ice phase at the initial stage of freezing.Meanwhile,the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase.These results have insights and scientific significance for the tackling of climate change,the environmental protection of groundwater and soil,and infrastructure protection such as roads,among other things.展开更多
This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimat...This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimate of the ratio of the respective free energies of systems with and without A show that the system variables given by Gibbs suffice to describe the volumetric properties of the fluid. The well-known Gibbsian expressions for the internal energies of the two-phase fluid, namely for the vapor and for the condensate (liquid or solid), only differ with respect to the phase-specific volumes and . The saturation temperature T, vapor presssure p, and chemical potential are intensive parameters, each of which has the same value everywhere within the fluid, and hence are phase-independent quantities. If one succeeds in representing as a function of and , then the internal energies can also be described by expressions that only differ from one another with respect to their dependence on and . Here it is shown that can be uniquely expressed by the volume function . Therefore, the internal energies can be represented explicitly as functions of the vapor pressure and volumes of the saturated vapor and condensate and are absolutely determined. The hitherto existing problem of applied thermodynamics, calculating the internal energy from the measurable quantities T, p, , and , is thus solved. The same method applies to the calculation of the entropy, chemical potential, and heat capacity.展开更多
Perovskite solar cells(PSCs)have attracted significant research interest due to the rapid rise in efficiency.However,a large efficiency gap still exists between laboratory-based small devices and industrialoriented la...Perovskite solar cells(PSCs)have attracted significant research interest due to the rapid rise in efficiency.However,a large efficiency gap still exists between laboratory-based small devices and industrialoriented large-scale modules.One of the main reasons for the efficiency losses is the degraded quality and morphology of the deposited large-area films,which is closely associated with crystallization processes.In this review,we discuss the nucleation and crystallization processes in solution and vaporbased up-scaling deposition methods for large-area perovskite films.We review recent scientific achievements and technical developments that have been made in the field of large-area cells.We present the existing problems that limit the performance of large devices and extensively discuss the key influencing parameters from the perspective of nucleation and crystallization over large areas.This review highlights the importance of crystallization control in up-scaling fabrications and presents promising strategies towards large-area perovskite-based optoelectronic devices.展开更多
The Xiluodu(XLD)reservoir is the second largest reservoir in China and the largest in the Jinsha River basin.The occurrence of two M>5 earthquakes after reservoir impoundment has aroused great interest among seismo...The Xiluodu(XLD)reservoir is the second largest reservoir in China and the largest in the Jinsha River basin.The occurrence of two M>5 earthquakes after reservoir impoundment has aroused great interest among seismologists and plant operators.We comprehensively analyzed the seismicity of the XLD reservoir area using precise earthquake relocation results and focal mechanism solutions and found that the seismicity of this area was weak before impoundment.Following impoundment,earthquake activity increased significantly.The occurrence of M≥3.5 earthquakes within five years of impoundment also appear to be closely related to rapid rises and falls in water level,though this correlation weakened after five years because earthquake activity was far from the reservoir area.Earthquakes in the XLD reservoir area are clustered;near the dam(Area A),small faults are intermittently distributed along the river,while Area B is composed of multiple NW-trending left-lateral strikeslip faults and a thrust fault and Area C is composed of a NW-trending left-lateral strike-slip main fault and a nearly EWtrending right-lateral strike-slip minor fault.The geometries of the deep and the shallow parts of the NW-trending fault differ.Under the action of the NW-trending background stress field,a series of NW-trending left-lateral strike-slip faults and NE-trending thrust faults in critical stress states were dislocated due to the stress caused by reservoir impoundment.The two largest earthquakes in the XLD reservoir area were tectonic earthquakes that were directly triggered by impoundment.展开更多
Exploring the spatial and temporal evolution characteristics of the border land use multifunctionality(LUMF)provides insights for taking advantage of border land use and optimizing border land use policies.Based on th...Exploring the spatial and temporal evolution characteristics of the border land use multifunctionality(LUMF)provides insights for taking advantage of border land use and optimizing border land use policies.Based on the improved Technique for Order Preference by Similarity to an Ideal Solution(TOPSIS)mode,this study identifies and evaluates the LUMFs in the China-Vietnam border area between 2000 and 2018 from the perspectives of agricultural production,social security,ecological service,landscape recreation,and national security.The results show that:1)The comprehensive land use functions in most counties and cities continued to be improved.2)The comprehensive land use function exhibits remarkable spatial divergence and aggregation characteristics.The high-value area of the agricultural production function and social security function evolves from the east to the west.In addition,the spatial evolution of ecological service function is complicated,without an obvious spatial divergence and aggregation pattern.The landscape recreation function shows different spatial differentiation characteristics in the early and middle stage,and forms a large cluster in the later stage.Finally,the spatial evolution pattern of the national security function is significant.3)Designing differentiated border land policies,improving border land use security,and establishing a long-term mechanism for ecological protection and ecological compensation can aid in optimizing the LUMF level in the border area.展开更多
Jiashi and its surrounding areas are composed of many structural zones. Using the focal mechanism solutions of 59 moderately strong earthquakes in Jiashi and its surrounding areas, and combining these with the calcula...Jiashi and its surrounding areas are composed of many structural zones. Using the focal mechanism solutions of 59 moderately strong earthquakes in Jiashi and its surrounding areas, and combining these with the calculation results of system cluster and stress field inversion, we aualyzed the evolvement characteristics of the stress field for different times and different regions. The results were as follows: The earthquakes in Jiashi are mainly strike-slip. However, those of the Kalpin block are mainly reverse events, showing an obvious thrusting. The regional characteristics are different from other areas. The direction of the regional principal stress field is near NS. However, under different tectonic backgrounds, the directions of the stress fields are different. The direction of the principal compress stress is near NS in the Kashi-Wuqia area. But before and after the 3 earthquakes with M7.0, dynamic evolution from NW to NS and then to NE with time process was observed. The Kalpin block has been dominated by a consistent stress field in the NW direction for a long time. However, the direction of the stress field of the Jiashi region is NE. Since 1996, the direction of the regional stress field has changed obviously. The direction of the P axis was deflected towards the NE, and the plunge angle increased. The result shows clearly the regional characteristics and variation of the distribution pattern of the stress field in different tectonic environments.展开更多
文摘The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability.
文摘In this review paper,we present a thorough investigation into the role of pavement technologies in advancing urban sustainability.Our analysis traverses the historical evolution of these technologies,meticulously evaluating their socio-economic and environmental impacts,with a particular emphasis on their role in mitigating the urban heat island effect.The evaluation of pavement types and variables influencing pavement performance to be used in the multi-criteria decision-making(MCDM)framework to choose the optimal pavement application are at the heart of our research.Which serves to assess a spectrum of pavement options,revealing insights into the most effective and sustainable practices.By highlighting both the existing challenges and potential innovative solutions within thefield,this paper aims to offer a directional compass for future urban planning and infrastructural advancements.This review not only synthesizes the current state of knowledge but also aims to chart a course for future exploration,emphasizing the critical need for innovative and environmentally sensitive pavement tech-nologies in the creation of resilient and sustainable urban environments.
基金Supported by Special Project for Research on Prevention and Control of Air Pollution from Fire Coal in 2018 of Ministry of Ecology and Environment of the People’s Republic of China(2018A030)National Natural Science Foundation of China(41771498)
文摘Since the implementation of the Action Plan for Air Pollution Prevention and Control , all regions of China have steadily promoted the prevention and control of air pollution and achieved results continuously. However, the atmospheric environment in key areas such as Beijing-Tianjin-Hebei region, the Yangtze River Delta region, and Fenwei Plain is still severe, and especially during the heating period heavy pollution occurs frequently, which has become the focus and difficulty of improving the quality of the atmospheric environment and is also the weakest link of China s air pollution control at present. How to alleviate air pollution, how to win the battle of pollution prevention and control, how to hold the fruits of the blue sky defense war, energy consumption is key.
文摘Under the constrained condition induced by the eigenfunction expresson of the potential (u, v)T = (-[A2q, q], [A2p, p])T = f (q, p), the spatial part of the Lax pair of the Kaup-Newell equation is non linearized to be a completely integrable system (R2N, Adp AND dq, H = H-1) with the Hamiltonian H-1 = -[A3q, p]-1/2[A2p, p][A2q, q]. while the nonlinearization of the time part leads to its N-involutive system {H(m)}. The involutive solution of the compatible fsystem (H-1), (H(m)) is mapped by into the solution of the higher order Kaup-Newell equation.
基金sponsored by the Subject of City ActiveFault Exploration Program of Urumqi and Joint Foundation of Earthquake Administration of Xinjiang Uygur Autonomous Region (200704),China
文摘Using the focal mechanism solutions of 24 moderately strong earthquakes in the northern Tianshan area,we carried out system cluster and stress field inversion analysis.The result indicates that,the focal mechanism solutions of moderately strong earthquakes are mainly dip-slip reverse faulting in the northern Tianshan area.The principal rupture planes of earthquakes are NW-oriented.It is basically consistent with the strike of earthquake structure in its adjacent area.The direction of the principal compression stress P axis is nearly NS,and its inclination angle is small;while the inclination angle of the principal extensional stress T axis is large.It shows that the regional stress field is mainly controlled by the near-NS horizontal compressive stress.The direction of the maximum principal stress shows a gradation process of NNE-NS-NW from east to west.
文摘Introduction
Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simultaneously, the fluid production rate, oil production rate and water injection rate has changed greatly so that the inflicts and problems from the established surface systems will become more obvious. Energy cost of production and running has increasing continuously. Capacity has been unbalance in systems and areas.
基金supported by the National Natural Science Foundation of China (Grant No. 51234006)the National Key Research and Development Program of China (Grant No. 2016YFC0600708)
文摘In the non-uniform stress field, the surrounding rock plastic zone of the circular roadway shows different shapes under the different confining pressure conditions. Based on the boundary shape characteristics of the plastic zone, the characteristic radii of the plastic zone were proposed, namely the horizontal,longitudinal and medial axis radii, which could reflect the plastic zone shapes characteristics and classify the sizes of the key parts. On the theoretical basis of elastic-plastic mechanics, analytical solutions for the characteristic radii were obtained by theoretical deduction, and the relationships between the characteristic radii and key influencing factors were analyzed. Finally, the evaluation criterion of the circular roadway surrounding rock plastic zone shapes, evaluation criterion of the location of potential hazards caused by the roadway surrounding rock and evaluation critical points of roadway dynamic disasters based on characteristic radii were proposed. This work could provide a theoretical basis for stability analysis of the surrounding rock, support design, and guide the prevention and control of dynamic roadway disasters.
基金Key Project of State Science and Technology during the tenth Five-year Plan (2001BA601B01-01-05).
文摘In the paper, we use the Central Moment Tensor (CMT) solution acquired by Harvard Univ. for the earthquakes occurred in Kurile Islands to analyze the consistent focal mechanism in the area and propose the idea of making earthquake prediction based on the consistent parameter a of focal mechanism and stress field. The results from the study indicate that before Mw greater than or equal 7.5 earthquakes, the consistent parameter a decreases, which starts about 10-110 days and ends about 30-2 days before the great earthquakes. Although the phenomenon is not totally the same for individual earthquake, the difference is not large. Certainly, the phenomenon should be tested by time for its reliability. However, it should not be random that the focal mechanism of Mw greater than or equal 5.3 earthquakes are consistent successively with the stress field in an area of several hundreds kilometers in length. It should be a phenomenon of predictive significance. When the accumulated earthquake examples are sufficient, uniform judgment criteria and prediction principles can be stipulated then.
文摘At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in current language teaching and provides some solutions.
文摘There are large deltaic systems in the Triassic Yanchang Formation in the northern Shaanxi area of the Ordos Basin, and developed two sets of good source-reservoir-caprock assemblages and many sets of oil-bearing beds. Exploration experience demonstrates that the formation and distribution of the reservoir were controlled by the generative depression of the Yanchang Formation, and deltaic reservoir sand body is the material basis for large-scale oilfields. In addition, secondary laumontite in a low permeable area was dissolved and then a high permeable area was formed. The updip lithologic variety of reservoir sand bodies is favorable to the formation of subtle lithologic traps, and the deltaic reservoirs are characterized by large multi-beds of oil-generation and abundant hydrocarbon resources. In this paper, the petroleum geologic settings of the studied area are analyzed, and the accumulation characteristics and exploration methods of lithologic reservoirs are summarized. It is of theoretical significance for the study of the exploration theories of lithologic reservoirs, and also expedites the exploration steps of deltaic reservoirs in the northern Shaanxi area.
文摘Taking 6 residential areas in Nyingchi of Tibet as research objects,from aesthetic effect,ecological function and leisure service,this paper established the evaluation indicator system for plant landscape in residential areas using AHP,and calculated the weight of indicators using the judgment matrix. Besides,it calculated the ideal solution and closeness degree of matrix using TOPSIS,and established the evaluation method and preference method for plant landscape in residential areas. The results show that the indicators of seasonal variation,environmental benefit and per capita green space mattered most in the landscape evaluation of residential areas. The richness of flowering plant is weak in the landscape evaluation. From the comprehensive evaluation of residential areas,Nyingchi Garden District and Xingfu District have excellent plant landscape,Jialong Garden District and Shangcheng Garden District have general plant landscape,and Sun City District and Niyang Garden District have poor plant landscape.
基金Under the auspices of the National Natural Science Foundation of China(No.41601141,41471469)Humanities and Social Sciences Youth Foundation of Ministry of Education of the People’s Republic of China(No.14YJCZH130)+1 种基金Soft Science Research Projects of Science and Technology Office of Sichuan Province(No.2015ZR0115)Research Foundation of Chengdu University of Information Technology(No.KYTZ201628,J201617)
文摘Abstract: Enhancing the efficiency of public services is essential to residents in mountainous areas. It is also important to promote sus- tainable development of these regions. Analysing residents' satisfaction with public services in mountainous areas can help in evaluating outcomes of fiscal investment and identifying potential coping approaches for improving public service efficiencies. The residents' satisfaction with public services and the factors that influence such satisfaction were examined in this study. A study of 12 towns located in the southwestern Sichuan Province was performed using an entropy-weighted analytic hierarchy process (EWAHP), the technique for order preference by similarity to ideal solution (TOPSIS) and Tobit regression methods. The results indicate that: 1) the spatial distribu- tion of satisfaction with public services is non-uniform, and the spatial distribution structure varies for different types of public services. 2) Residents' satisfaction with public services is influenced by both objective and subjective factors. Population density, economic dis- tance, social and cultural divisions and elevation are the major objective factors, whereas bounded rationality, the hierarchy of needs and service expectations are the main subjective factors. The most effective strategies for enhancing residents' satisfaction with public ser- vices are likely to be clustering the population, choosing supply centres with different public services, regulating the cultural division in ethnic minority towns, selecting supply priorities in accordance with residents' needs, implementing targeted intervention policies and establishing 'bottom-up' and 'top-down' integrated decision-making mechanisms. Keywords: mountainous areas; public services; residents' satisfaction; entropy-weighted analytic hierarchy process (EWAHP); technique for order preference by similarity to ideal solution (TOPSIS); Tobit regression; southwestern Sichuan Province
基金This research was financially supported by the National Natural Science Foundation of China(41572225)project of China Geological Survey(DD20189662,DD20211256).
文摘Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas.However,little knowledge is available about the process and mechanisms of salt migration in frozen soil.This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments.The results are as follows.The solute concentrations of liquid and solid phases at the ice-liquid interface(C*_(L),C*_(S))gradually increased at the initial stage of freezing and remained approximately constant at the middle stage.As the ice-liquid interface advanced toward the system boundary,the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts.As a result,C*_(L)and C*_(S)rapidly increased at the final stage of freezing.The distribution characteristics of solutes in ice and the liquid phases before C*_(L)and C*_(S)became steady were mainly affected by the freezing temperature,initial concentrations,and particle-size distribution of media(quartz sand and kaolin).In detail,the lower the freezing temperature and the better the particle-size distribution of media,the higher the solute proportion in the ice phase at the initial stage of freezing.Meanwhile,the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase.These results have insights and scientific significance for the tackling of climate change,the environmental protection of groundwater and soil,and infrastructure protection such as roads,among other things.
文摘This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimate of the ratio of the respective free energies of systems with and without A show that the system variables given by Gibbs suffice to describe the volumetric properties of the fluid. The well-known Gibbsian expressions for the internal energies of the two-phase fluid, namely for the vapor and for the condensate (liquid or solid), only differ with respect to the phase-specific volumes and . The saturation temperature T, vapor presssure p, and chemical potential are intensive parameters, each of which has the same value everywhere within the fluid, and hence are phase-independent quantities. If one succeeds in representing as a function of and , then the internal energies can also be described by expressions that only differ from one another with respect to their dependence on and . Here it is shown that can be uniquely expressed by the volume function . Therefore, the internal energies can be represented explicitly as functions of the vapor pressure and volumes of the saturated vapor and condensate and are absolutely determined. The hitherto existing problem of applied thermodynamics, calculating the internal energy from the measurable quantities T, p, , and , is thus solved. The same method applies to the calculation of the entropy, chemical potential, and heat capacity.
文摘Perovskite solar cells(PSCs)have attracted significant research interest due to the rapid rise in efficiency.However,a large efficiency gap still exists between laboratory-based small devices and industrialoriented large-scale modules.One of the main reasons for the efficiency losses is the degraded quality and morphology of the deposited large-area films,which is closely associated with crystallization processes.In this review,we discuss the nucleation and crystallization processes in solution and vaporbased up-scaling deposition methods for large-area perovskite films.We review recent scientific achievements and technical developments that have been made in the field of large-area cells.We present the existing problems that limit the performance of large devices and extensively discuss the key influencing parameters from the perspective of nucleation and crystallization over large areas.This review highlights the importance of crystallization control in up-scaling fabrications and presents promising strategies towards large-area perovskite-based optoelectronic devices.
基金funded by the project of"The Seismogenesis and Discrimination Methods of Cascade Reservoir in the Lower reaches of Jinsha River"(JG/20023B)from the China Three Gorges Construction Engineering Corporationthe Fundamental Research Funds for the Institute of Earthquake Forecasting,China Earthquake Administration(Nos.2021IEF0603,CEAIEF2022030100)the Basic Research Program on Natural Science in Shaanxi Province(No.2021JM-600)。
文摘The Xiluodu(XLD)reservoir is the second largest reservoir in China and the largest in the Jinsha River basin.The occurrence of two M>5 earthquakes after reservoir impoundment has aroused great interest among seismologists and plant operators.We comprehensively analyzed the seismicity of the XLD reservoir area using precise earthquake relocation results and focal mechanism solutions and found that the seismicity of this area was weak before impoundment.Following impoundment,earthquake activity increased significantly.The occurrence of M≥3.5 earthquakes within five years of impoundment also appear to be closely related to rapid rises and falls in water level,though this correlation weakened after five years because earthquake activity was far from the reservoir area.Earthquakes in the XLD reservoir area are clustered;near the dam(Area A),small faults are intermittently distributed along the river,while Area B is composed of multiple NW-trending left-lateral strikeslip faults and a thrust fault and Area C is composed of a NW-trending left-lateral strike-slip main fault and a nearly EWtrending right-lateral strike-slip minor fault.The geometries of the deep and the shallow parts of the NW-trending fault differ.Under the action of the NW-trending background stress field,a series of NW-trending left-lateral strike-slip faults and NE-trending thrust faults in critical stress states were dislocated due to the stress caused by reservoir impoundment.The two largest earthquakes in the XLD reservoir area were tectonic earthquakes that were directly triggered by impoundment.
基金Under the auspices of National Natural Science Project(No.42161046)National Social Science Project(No.21CJY075)+2 种基金Guangxi Natural Science Project(No.2021JJB150070)Guangxi Philosophy and Social Science Project(No.20FJY027)Guangxi First-class Discipline Applied Economics Construction Project Fund(Guangxi Education and Scientific Research(No.[2022]No.1))。
文摘Exploring the spatial and temporal evolution characteristics of the border land use multifunctionality(LUMF)provides insights for taking advantage of border land use and optimizing border land use policies.Based on the improved Technique for Order Preference by Similarity to an Ideal Solution(TOPSIS)mode,this study identifies and evaluates the LUMFs in the China-Vietnam border area between 2000 and 2018 from the perspectives of agricultural production,social security,ecological service,landscape recreation,and national security.The results show that:1)The comprehensive land use functions in most counties and cities continued to be improved.2)The comprehensive land use function exhibits remarkable spatial divergence and aggregation characteristics.The high-value area of the agricultural production function and social security function evolves from the east to the west.In addition,the spatial evolution of ecological service function is complicated,without an obvious spatial divergence and aggregation pattern.The landscape recreation function shows different spatial differentiation characteristics in the early and middle stage,and forms a large cluster in the later stage.Finally,the spatial evolution pattern of the national security function is significant.3)Designing differentiated border land policies,improving border land use security,and establishing a long-term mechanism for ecological protection and ecological compensation can aid in optimizing the LUMF level in the border area.
基金The research was jointly sponsored by the State Key Science and Technology Development and Research Program of the 10th Five-Year Plan ( Grant No. 2001BA601B010303)the project of Science and Technology Department of Xinjiang Uygur Autonomous Region (Grant No.200333116) .
文摘Jiashi and its surrounding areas are composed of many structural zones. Using the focal mechanism solutions of 59 moderately strong earthquakes in Jiashi and its surrounding areas, and combining these with the calculation results of system cluster and stress field inversion, we aualyzed the evolvement characteristics of the stress field for different times and different regions. The results were as follows: The earthquakes in Jiashi are mainly strike-slip. However, those of the Kalpin block are mainly reverse events, showing an obvious thrusting. The regional characteristics are different from other areas. The direction of the regional principal stress field is near NS. However, under different tectonic backgrounds, the directions of the stress fields are different. The direction of the principal compress stress is near NS in the Kashi-Wuqia area. But before and after the 3 earthquakes with M7.0, dynamic evolution from NW to NS and then to NE with time process was observed. The Kalpin block has been dominated by a consistent stress field in the NW direction for a long time. However, the direction of the stress field of the Jiashi region is NE. Since 1996, the direction of the regional stress field has changed obviously. The direction of the P axis was deflected towards the NE, and the plunge angle increased. The result shows clearly the regional characteristics and variation of the distribution pattern of the stress field in different tectonic environments.