Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both g...Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.展开更多
The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-ji...The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifically in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.展开更多
Background:To explore the application effect of Acknowledge-Introduce-Duration-Explanation-Thank you(AIDET)communication mode in reducing anxiety and improving the care services satisfaction of the patients.Methods:Th...Background:To explore the application effect of Acknowledge-Introduce-Duration-Explanation-Thank you(AIDET)communication mode in reducing anxiety and improving the care services satisfaction of the patients.Methods:The 100 cases undergoing cataract daytime operation from February to July 2019 were divided into test group and control group.The test group conducted health education and nursing care for patients during admission,pre-operation,post-operation,and discharge according to the AIDET communication mode.And the control group was given health education and nursing care to the patients according to the traditional way of communication.Results:The difference of the socioeconomic information between these two groups showed no statistical significance.The care services satisfaction score in the test group was statistically higher than that in the control group(P<0.05).The Self-Rating Anxiety Scale(SAS)score in the test group was significantly lower than that in the control group(P<0.01).This result indicated that the patients suffered less anxiety with the AIDET mode of communication.Conclusions:The application of AIDET communication mode to the nursing service of cataract daytime operation can reduce the tension and anxiety of the patients from the treatment and improve their satisfaction to care services.展开更多
An approach of training working staff of power system operation mode based on state evaluation is proposed. In terms of knowledge features of power system operation mode, we studied a training method based on evaluati...An approach of training working staff of power system operation mode based on state evaluation is proposed. In terms of knowledge features of power system operation mode, we studied a training method based on evaluation of learning state. This training method makes individual learning for different individual condition to give them ability to grasp learning points quickly, evaluate real-time learning effect, update learning style in time and summarize problems after one learning stage, so that learners can master professional knowledge in constant summaries and feedbacks. Obvious effects can be obtained on discontinuous learning time that trainees can master basic theories associated with their working and operations adapted to practical work quickly.展开更多
The Pearl River Estuary(PRE)is one of China’s busiest shipping hubs and fishery production centers,as well as a region with abundant island tourism and wind energy resources,which calls for accurate short-term wind f...The Pearl River Estuary(PRE)is one of China’s busiest shipping hubs and fishery production centers,as well as a region with abundant island tourism and wind energy resources,which calls for accurate short-term wind forecasts.First,this study evaluated three operational numerical models,i.e.,ECMWF-EC,NCEP-GFS,and CMA-GD,for their ability to predict short-term wind speed over the PRE against in-situ observations during 2018-2021.Overall,ECMWF-EC out-performs other models with an average RMSE of 2.24 m s^(-1)and R of 0.57,but the NCEP-GFS performs better in the case of strong winds.Then,various bias correction and multi-model ensemble(MME)methods are used to perform the deterministic post-processing using a local and lead-specific scheme.Two-factor model output statistics(MOS2)is the optimal bias correction method for reducing(increasing)the overall RMSE(R)to 1.62(0.70)m s^(-1),demonstrating the benefits of considering both initial and lead-specific information.Intercomparison of MME results reveals that Multiple linear regression(MLR)presents superior skills,followed by random forest(RF),but it is slightly inferior to MOS2,particularly for the first few forecasting hours.Furthermore,the incorporation of additional features in MLR reduces the overall RMSE to 1.53 m s^(-1)and increases R to 0.74.Similarly,RF presents comparable results,and both outperform MOS2 in terms of correcting their deficiencies at the first few lead hours and limiting the error growth rate.Despite the satisfactory skill of deterministic post-processing techniques,they are unable to achieve a balanced performance between mean and extreme statistics.This highlights the necessity for further development of probabilistic forecasts.展开更多
During the 14th Five Year Plan period,the main task of talent team construction in China’s asset appraisal industry was to develop innovative talent training models.Therefore,this article focuses on the talent cultiv...During the 14th Five Year Plan period,the main task of talent team construction in China’s asset appraisal industry was to develop innovative talent training models.Therefore,this article focuses on the talent cultivation model of integrating industry and education in asset evaluation in universities,systematically summarizes the theoretical and practical significance of research on asset evaluation talent cultivation models in universities,and explores the construction measures of asset evaluation talent cultivation models based on the integration of industry and education that meet social needs and the development of the times[1].At the same time,the strategy of constructing a deep integration talent training system was explored,guided by the integration of industry and education,to cultivate asset evaluation composite talents with strong practical skills.The aim is to provide a reference for improving the quality of asset evaluation professionals in China and promoting the development of asset evaluation talent training models.展开更多
The damages of different drilling modes to reservoirs are different in types and degrees.In this paper,the geologic characteristics and types of such damages were analyzed.Then,based on the relationship between reserv...The damages of different drilling modes to reservoirs are different in types and degrees.In this paper,the geologic characteristics and types of such damages were analyzed.Then,based on the relationship between reservoir pressure and bottom hole flowing pressure corresponding to different drilling modes,the experimental procedures on reservoir damages in three drilling modes(e.g.gas drilling,liquid-based underbalanced drilling and overbalanced drilling)were designed.Finally,damage simulation experiments were conducted on the tight sandstone reservoir cores of the Jurassic Ahe Fm in the Tarim Basin and Triassic Xujiahe Fm in the central Sichuan Basin.It is shown that the underbalanced drilling is beneficial to reservoir protection because of its less damage on reservoir permeability,but it is,to some extent,sensitive to the stress and the empirical formula of stress sensitivity coefficient is obtained;and that the overbalanced drilling has more reservoir damages due to the invasion of solid and liquid phases.After the water saturation of cores rises to the irreducible water saturation,the decline of gas logging permeability speeds up and the damage degree of water lock increases.It is concluded that the laboratory experiment results of reservoir damage are accordant with the reservoir damage characteristics in actual drilling conditions.Therefore,this method reflects accurately the reservoir damage characteristics and can be used as a new experimental evaluation method on reservoir damage in different drilling modes.展开更多
Geological Hazards Investigation and Evaluation is the core course of Environmental Geological Engineering,aiming to cultivate skilled talents with solid theoretical knowledge and excellent practical skills.At present...Geological Hazards Investigation and Evaluation is the core course of Environmental Geological Engineering,aiming to cultivate skilled talents with solid theoretical knowledge and excellent practical skills.At present,the course faces several issues,including a teaching environment disconnected from real-world work scenarios,course content that deviates from job-related tasks,a lack of digital teaching resources,and reliance on a single teaching method,leading to students’poor feedback from employers.Based on the concept of outcome-based education,the course team of Geological Hazards Investigation and Evaluation establishes a“five-step double-rotation”blended teaching model with the help of a Small Private Online Course platform.The program is designed to improve the teaching environment and expand the digitalized teaching resources in order to improve students’learning motivation,enhance learning effectiveness,and cultivate skillful talents who meet employers’satisfaction.展开更多
This paper describes a method for fast engineering evaluation of the transmission characteristicsof single-mode optical fibers.A versatile microcomputer program is presented which can be utilized to ana-lyze mode fiel...This paper describes a method for fast engineering evaluation of the transmission characteristicsof single-mode optical fibers.A versatile microcomputer program is presented which can be utilized to ana-lyze mode field characteristics of single-mode fibers with arbitrary refractive index profiles.Our computationshows that the mathematical algorithm and the corresponding programs developeod in this paper are rela-tively simple and accurate enough for the engineenring design of single-mode fibers for optical communica-tion systems.展开更多
In order to improve the incipient fault sensitivity and stability of degradation index in the rolling bearing performance degradation evaluation process,an embedding selection-based neighborhood preserving embedding(E...In order to improve the incipient fault sensitivity and stability of degradation index in the rolling bearing performance degradation evaluation process,an embedding selection-based neighborhood preserving embedding(ESNPE)method is proposed.Firstly,the acquired vibration signals are decomposed by variational mode decomposition(VMD),and the singular value and relative energy of each intrinsic mode function(IMF)are extracted to form a high-dimensional feature set.Then,the NPE manifold learning method is used to extract the embedded features in the feature space.Considering the problem that useful embedding information is easily suppressed in NPE,an embedding selection strategy is built based on the Spearman correlation coefficient.The effectiveness of embeddings is measured by the coefficient absolute value,and useful embeddings are preserved in the early stage of bearing degradation by using the first-order difference method.Finally,the degradation index is established using the support vector data description(SVDD)model and bearing performance degradation evaluation is achieved.The proposed method was tested with the whole life experiment data of a rolling bearing,and the result was compared with the feature extraction methods of traditional principal component analysis(PCA)and NPE.The results show that the proposed method is superior in improving the incipient fault sensitivity and stability of the degradation index.展开更多
Ecological security of tourism destination is an important factor for the sustainable development of tourism industry, and many tourism destinations are threatened by various ecological problems. A complete understand...Ecological security of tourism destination is an important factor for the sustainable development of tourism industry, and many tourism destinations are threatened by various ecological problems. A complete understanding of eco-security situation is the foundation of maintaining sustainable development for tourism destinations. However, study on tourism destination eco-security has remained in the initial stage, based on domestic and international researches, the connotations and dynamic characteristics of tourism destination eco-security were discussed. Then, evaluation method of tourism destination eco-security and standard system were proposed, also dynamic evaluation method of tourism destination eco-safety based on the situation evaluation and trend was analyzed.展开更多
To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation...To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation process of the equipment SoS contribution rate were redefined and standardized.To solve the existing problems in the application of the original contribution rate formula,a modified contribution rate calculation formula is proposed.Finally,the contribution rate evaluation index was divided into latent and explicit variables.The measurement and structural equations in the SEM were used to calculate and analyze the latent variables.The simulation results show that the number of defense lines of air defense weapon equipment has a greater impact on the linear configuration than the group configuration.When the number of K-type air defense weapons is sufficient,the two-layer linear configuration should be adopted with 20 air defense weapon systems.When the number of K-type air defense weapons is insufficient,the single-layer group configuration should be adopted with 12 air defense weapon systems.展开更多
This paper introduces a multi-model approach to design a robust supplementary damping controller. The designed fixed-order supplementary damping controller adjusts the voltage reference set point of SVC. There are two...This paper introduces a multi-model approach to design a robust supplementary damping controller. The designed fixed-order supplementary damping controller adjusts the voltage reference set point of SVC. There are two main objectives of the controller design, damping low frequencies oscillations and enhancing power system stability. This method relies on shaping the closed-loop sensitivity functions in the Nyquist plot under the constraints of these functions. These constraints can be linearized by choosing a desired open-loop transfer function. The robust controller is designed to minimize the error between the open-loop of the original plant model and the desired transfer functions. These outcomes can be achieved by using convex optimization methods. Convexity of the problem formulation ensures global optimality. One of the advantages of the proposed approach is that the approach accounts for multi-model uncertainty. In contrast to the methods available in the literature, the proposed approach deals with full-order model (i.e., model reduction is not required) with lower controller order. The issue of time delay of feedback signals has been addressed in this paper for different values of time delay by applying a multi-model optimization technique. The proposed approach is compared to other existing techniques to design a robust controller which is based on H2 under pole placement. Both techniques are applied to the 68-bus system to evaluate and validate the robust controller performance under different load scenarios and different wind generations.展开更多
Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geolog...Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geological schemes for constructing the underground gas storages rebuilt from gas reservoirs and optimize the UGS operation parameters,we analyzed the UGS basic characteristics of multi-cycle high-rate injection and production.Then,the dynamic sealing capacity of traps and the wateregas high-speed interactive flow mechanism of UGSs rebuilt from gas reservoirs with complex geological conditions were investigated by both physical simulation and numerical simulation.Finally,the key technologies for evaluating the dynamic sealing capacity of caprocks and faults and the storage capacity parameters were developed.Some results were obtained.First,the alternating stress in the process of UGS injection and production weakens the original static capillary sealing capacity and mechanical integrity of caprocks to different extents,and the trap sealing capacity can be quantified and evaluated comprehensively by using dynamic breakthrough pressures,shear safety indexes and other indicators.Second,a UGS capacity design method based on effective gas-bearing pores was developed according to the local pore-based recovery mechanism revealed in the high-speed gasewater mutual flooding test.Field application in the multi-layer UGS of H shows that these technologies provide an effective guidance for the design of geologic schemes.After five cycles of injection and production,its ramp-up ratio reached 91.8%and the peak shaving capacity increased quickly to 36.3×10^(8)m^(3)from 2.7×10^(8)m^(3)in the early stage of production.Moreover,the operation indicators matched well with the design.展开更多
In order to analyze the sources of merger and acquisition(M & A)information,and the relationship between the M & A information and the M & A corporation management bureau,the searching and evaluation proce...In order to analyze the sources of merger and acquisition(M & A)information,and the relationship between the M & A information and the M & A corporation management bureau,the searching and evaluation procedure of M & A target was discussed.The standard modes and procedures of finding the sources of the M & A target,examination of the M & A information,depicting on the future of M & A,and evaluation of the M & A target,were brought forward.展开更多
Case Method originated in the 1920s and was initiated by Harvard Business School in the United States.At that time,it adopted a unique style of case study,which was based on real situations or events in business manag...Case Method originated in the 1920s and was initiated by Harvard Business School in the United States.At that time,it adopted a unique style of case study,which was based on real situations or events in business management,in this way,it is helpful to cultivate and develop students’active participation in class discussion.For investment students,specialized courses such as Investment Project Evaluation and corporate finance are concentrated in the upper grades,and in the freshman,sophomore phase has completed the Finance,finance,macroeconomics and other basic courses.On the basis of students’existing knowledge structure,the course“Investment Project Evaluation”needs to fully tap students’potential in learning and train students’practical problem-solving ability,to cultivate students’thinking ability of combining theoretical knowledge with practical cases,to avoid the teaching mode of“I tell you to listen”,and to guide students to think,analyze and solve problems actively.展开更多
Quantification of river flood risks is a prerequisite for floodplain management and development.The lower Yellow River(LYR)is characterized by a complex channel–floodplain system,which is prone to flooding but inhabi...Quantification of river flood risks is a prerequisite for floodplain management and development.The lower Yellow River(LYR)is characterized by a complex channel–floodplain system,which is prone to flooding but inhabits a large population on the floodplains.Many floodplain management modes have been presented,but implementation effects of these management modes have not been evaluated correctly.An integrated model was first proposed to evaluate the flood risks to people’s life and property,covering an improved module of two-dimensional(2D)morphodynamic processes and a module of flood risk evaluation for people,buildings and crops on the floodplains.Two simulation cases were then conducted to validate the model accuracy,including the hyperconcentrated flood event and dike-breach induced flood event occurring in the LYR.Finally,the integrated model was applied to key floodplains in the LYR,and the effects of different floodplain management modes were quantified on the risks to people’s life and property under an extreme flood event.Results indicate that:①Satisfactory accuracy was achieved in the simulation of these two flood events.The maximum sediment concentration was just underestimated by 9%,and the simulated inundation depth agreed well with the field record;②severe inundation was predicted to occur in most domains under the current topography(SchemeⅠ),which would be alleviated after implementing different floodplain management modes,with the area in slight inundation degree accounting for a large proportion under the mode of“construction of protection embankment”(SchemeⅡ)and the area in medium inundation degree occupying a high ratio under the mode of“floodplain partition harnessing”(SchemeⅢ);and③compared with SchemeⅠ,the high-risk area for people’s life and property would reduce by 21%–49%under SchemeⅡ,and by 35%–93%under SchemeⅢ.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U2342210 and 42275043)the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant Nos.J2223806,ZDJ2024-25 and ZDJ2025-34)。
文摘Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.
文摘The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifically in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.
文摘Background:To explore the application effect of Acknowledge-Introduce-Duration-Explanation-Thank you(AIDET)communication mode in reducing anxiety and improving the care services satisfaction of the patients.Methods:The 100 cases undergoing cataract daytime operation from February to July 2019 were divided into test group and control group.The test group conducted health education and nursing care for patients during admission,pre-operation,post-operation,and discharge according to the AIDET communication mode.And the control group was given health education and nursing care to the patients according to the traditional way of communication.Results:The difference of the socioeconomic information between these two groups showed no statistical significance.The care services satisfaction score in the test group was statistically higher than that in the control group(P<0.05).The Self-Rating Anxiety Scale(SAS)score in the test group was significantly lower than that in the control group(P<0.01).This result indicated that the patients suffered less anxiety with the AIDET mode of communication.Conclusions:The application of AIDET communication mode to the nursing service of cataract daytime operation can reduce the tension and anxiety of the patients from the treatment and improve their satisfaction to care services.
文摘An approach of training working staff of power system operation mode based on state evaluation is proposed. In terms of knowledge features of power system operation mode, we studied a training method based on evaluation of learning state. This training method makes individual learning for different individual condition to give them ability to grasp learning points quickly, evaluate real-time learning effect, update learning style in time and summarize problems after one learning stage, so that learners can master professional knowledge in constant summaries and feedbacks. Obvious effects can be obtained on discontinuous learning time that trainees can master basic theories associated with their working and operations adapted to practical work quickly.
基金Science and Technology Research Project of Guangdong Meteorological Service(GRMC2021M19,GRMC2022Q16,GRMC2023M29)。
文摘The Pearl River Estuary(PRE)is one of China’s busiest shipping hubs and fishery production centers,as well as a region with abundant island tourism and wind energy resources,which calls for accurate short-term wind forecasts.First,this study evaluated three operational numerical models,i.e.,ECMWF-EC,NCEP-GFS,and CMA-GD,for their ability to predict short-term wind speed over the PRE against in-situ observations during 2018-2021.Overall,ECMWF-EC out-performs other models with an average RMSE of 2.24 m s^(-1)and R of 0.57,but the NCEP-GFS performs better in the case of strong winds.Then,various bias correction and multi-model ensemble(MME)methods are used to perform the deterministic post-processing using a local and lead-specific scheme.Two-factor model output statistics(MOS2)is the optimal bias correction method for reducing(increasing)the overall RMSE(R)to 1.62(0.70)m s^(-1),demonstrating the benefits of considering both initial and lead-specific information.Intercomparison of MME results reveals that Multiple linear regression(MLR)presents superior skills,followed by random forest(RF),but it is slightly inferior to MOS2,particularly for the first few forecasting hours.Furthermore,the incorporation of additional features in MLR reduces the overall RMSE to 1.53 m s^(-1)and increases R to 0.74.Similarly,RF presents comparable results,and both outperform MOS2 in terms of correcting their deficiencies at the first few lead hours and limiting the error growth rate.Despite the satisfactory skill of deterministic post-processing techniques,they are unable to achieve a balanced performance between mean and extreme statistics.This highlights the necessity for further development of probabilistic forecasts.
文摘During the 14th Five Year Plan period,the main task of talent team construction in China’s asset appraisal industry was to develop innovative talent training models.Therefore,this article focuses on the talent cultivation model of integrating industry and education in asset evaluation in universities,systematically summarizes the theoretical and practical significance of research on asset evaluation talent cultivation models in universities,and explores the construction measures of asset evaluation talent cultivation models based on the integration of industry and education that meet social needs and the development of the times[1].At the same time,the strategy of constructing a deep integration talent training system was explored,guided by the integration of industry and education,to cultivate asset evaluation composite talents with strong practical skills.The aim is to provide a reference for improving the quality of asset evaluation professionals in China and promoting the development of asset evaluation talent training models.
基金Project supported by the Scientific Research and Innovation Team Fund of Universities Affiliated to Sichuan Province(No.2014TD0006)“Research on downhole safety risk and control methods of gas drilling”in Sichuan outstanding young academic technology leader training plan(No.2014JQ0045)Device and software development for quantitative evaluation of low-permeability gas reservoir damages(No.2016ZX05021-004-005).
文摘The damages of different drilling modes to reservoirs are different in types and degrees.In this paper,the geologic characteristics and types of such damages were analyzed.Then,based on the relationship between reservoir pressure and bottom hole flowing pressure corresponding to different drilling modes,the experimental procedures on reservoir damages in three drilling modes(e.g.gas drilling,liquid-based underbalanced drilling and overbalanced drilling)were designed.Finally,damage simulation experiments were conducted on the tight sandstone reservoir cores of the Jurassic Ahe Fm in the Tarim Basin and Triassic Xujiahe Fm in the central Sichuan Basin.It is shown that the underbalanced drilling is beneficial to reservoir protection because of its less damage on reservoir permeability,but it is,to some extent,sensitive to the stress and the empirical formula of stress sensitivity coefficient is obtained;and that the overbalanced drilling has more reservoir damages due to the invasion of solid and liquid phases.After the water saturation of cores rises to the irreducible water saturation,the decline of gas logging permeability speeds up and the damage degree of water lock increases.It is concluded that the laboratory experiment results of reservoir damage are accordant with the reservoir damage characteristics in actual drilling conditions.Therefore,this method reflects accurately the reservoir damage characteristics and can be used as a new experimental evaluation method on reservoir damage in different drilling modes.
基金Scientific Research Fund of Hunan Provincial Education Department Excellent Youth Project(23B0953)Hunan Province Vocational College Education and Teaching Reform Research Project(ZJGB2022427)。
文摘Geological Hazards Investigation and Evaluation is the core course of Environmental Geological Engineering,aiming to cultivate skilled talents with solid theoretical knowledge and excellent practical skills.At present,the course faces several issues,including a teaching environment disconnected from real-world work scenarios,course content that deviates from job-related tasks,a lack of digital teaching resources,and reliance on a single teaching method,leading to students’poor feedback from employers.Based on the concept of outcome-based education,the course team of Geological Hazards Investigation and Evaluation establishes a“five-step double-rotation”blended teaching model with the help of a Small Private Online Course platform.The program is designed to improve the teaching environment and expand the digitalized teaching resources in order to improve students’learning motivation,enhance learning effectiveness,and cultivate skillful talents who meet employers’satisfaction.
文摘This paper describes a method for fast engineering evaluation of the transmission characteristicsof single-mode optical fibers.A versatile microcomputer program is presented which can be utilized to ana-lyze mode field characteristics of single-mode fibers with arbitrary refractive index profiles.Our computationshows that the mathematical algorithm and the corresponding programs developeod in this paper are rela-tively simple and accurate enough for the engineenring design of single-mode fibers for optical communica-tion systems.
基金The National Natural Science Foundation of Chin(No.51975117)
文摘In order to improve the incipient fault sensitivity and stability of degradation index in the rolling bearing performance degradation evaluation process,an embedding selection-based neighborhood preserving embedding(ESNPE)method is proposed.Firstly,the acquired vibration signals are decomposed by variational mode decomposition(VMD),and the singular value and relative energy of each intrinsic mode function(IMF)are extracted to form a high-dimensional feature set.Then,the NPE manifold learning method is used to extract the embedded features in the feature space.Considering the problem that useful embedding information is easily suppressed in NPE,an embedding selection strategy is built based on the Spearman correlation coefficient.The effectiveness of embeddings is measured by the coefficient absolute value,and useful embeddings are preserved in the early stage of bearing degradation by using the first-order difference method.Finally,the degradation index is established using the support vector data description(SVDD)model and bearing performance degradation evaluation is achieved.The proposed method was tested with the whole life experiment data of a rolling bearing,and the result was compared with the feature extraction methods of traditional principal component analysis(PCA)and NPE.The results show that the proposed method is superior in improving the incipient fault sensitivity and stability of the degradation index.
基金Supported by Project of National Key Technology R & D (2012BAC16B04)
文摘Ecological security of tourism destination is an important factor for the sustainable development of tourism industry, and many tourism destinations are threatened by various ecological problems. A complete understanding of eco-security situation is the foundation of maintaining sustainable development for tourism destinations. However, study on tourism destination eco-security has remained in the initial stage, based on domestic and international researches, the connotations and dynamic characteristics of tourism destination eco-security were discussed. Then, evaluation method of tourism destination eco-security and standard system were proposed, also dynamic evaluation method of tourism destination eco-safety based on the situation evaluation and trend was analyzed.
基金The National Social Science Foundation Military Science Project(No.16GJ003-068).
文摘To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation process of the equipment SoS contribution rate were redefined and standardized.To solve the existing problems in the application of the original contribution rate formula,a modified contribution rate calculation formula is proposed.Finally,the contribution rate evaluation index was divided into latent and explicit variables.The measurement and structural equations in the SEM were used to calculate and analyze the latent variables.The simulation results show that the number of defense lines of air defense weapon equipment has a greater impact on the linear configuration than the group configuration.When the number of K-type air defense weapons is sufficient,the two-layer linear configuration should be adopted with 20 air defense weapon systems.When the number of K-type air defense weapons is insufficient,the single-layer group configuration should be adopted with 12 air defense weapon systems.
文摘This paper introduces a multi-model approach to design a robust supplementary damping controller. The designed fixed-order supplementary damping controller adjusts the voltage reference set point of SVC. There are two main objectives of the controller design, damping low frequencies oscillations and enhancing power system stability. This method relies on shaping the closed-loop sensitivity functions in the Nyquist plot under the constraints of these functions. These constraints can be linearized by choosing a desired open-loop transfer function. The robust controller is designed to minimize the error between the open-loop of the original plant model and the desired transfer functions. These outcomes can be achieved by using convex optimization methods. Convexity of the problem formulation ensures global optimality. One of the advantages of the proposed approach is that the approach accounts for multi-model uncertainty. In contrast to the methods available in the literature, the proposed approach deals with full-order model (i.e., model reduction is not required) with lower controller order. The issue of time delay of feedback signals has been addressed in this paper for different values of time delay by applying a multi-model optimization technique. The proposed approach is compared to other existing techniques to design a robust controller which is based on H2 under pole placement. Both techniques are applied to the 68-bus system to evaluate and validate the robust controller performance under different load scenarios and different wind generations.
基金supported by PetroChina Major Science and Technology Project“Study and application of geological and gas reservoir engineering technologies for underground gas storages”(No.:2015E-4002).
文摘Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geological schemes for constructing the underground gas storages rebuilt from gas reservoirs and optimize the UGS operation parameters,we analyzed the UGS basic characteristics of multi-cycle high-rate injection and production.Then,the dynamic sealing capacity of traps and the wateregas high-speed interactive flow mechanism of UGSs rebuilt from gas reservoirs with complex geological conditions were investigated by both physical simulation and numerical simulation.Finally,the key technologies for evaluating the dynamic sealing capacity of caprocks and faults and the storage capacity parameters were developed.Some results were obtained.First,the alternating stress in the process of UGS injection and production weakens the original static capillary sealing capacity and mechanical integrity of caprocks to different extents,and the trap sealing capacity can be quantified and evaluated comprehensively by using dynamic breakthrough pressures,shear safety indexes and other indicators.Second,a UGS capacity design method based on effective gas-bearing pores was developed according to the local pore-based recovery mechanism revealed in the high-speed gasewater mutual flooding test.Field application in the multi-layer UGS of H shows that these technologies provide an effective guidance for the design of geologic schemes.After five cycles of injection and production,its ramp-up ratio reached 91.8%and the peak shaving capacity increased quickly to 36.3×10^(8)m^(3)from 2.7×10^(8)m^(3)in the early stage of production.Moreover,the operation indicators matched well with the design.
文摘In order to analyze the sources of merger and acquisition(M & A)information,and the relationship between the M & A information and the M & A corporation management bureau,the searching and evaluation procedure of M & A target was discussed.The standard modes and procedures of finding the sources of the M & A target,examination of the M & A information,depicting on the future of M & A,and evaluation of the M & A target,were brought forward.
基金Achievement of teaching reform research project in Sichuan University of Science&Engineering[JG1963]。
文摘Case Method originated in the 1920s and was initiated by Harvard Business School in the United States.At that time,it adopted a unique style of case study,which was based on real situations or events in business management,in this way,it is helpful to cultivate and develop students’active participation in class discussion.For investment students,specialized courses such as Investment Project Evaluation and corporate finance are concentrated in the upper grades,and in the freshman,sophomore phase has completed the Finance,finance,macroeconomics and other basic courses.On the basis of students’existing knowledge structure,the course“Investment Project Evaluation”needs to fully tap students’potential in learning and train students’practical problem-solving ability,to cultivate students’thinking ability of combining theoretical knowledge with practical cases,to avoid the teaching mode of“I tell you to listen”,and to guide students to think,analyze and solve problems actively.
基金supported by the National Natural Science Foundation of China(U2243238)the Program of the National Key Research and Development Plan(2023YFC3209304).
文摘Quantification of river flood risks is a prerequisite for floodplain management and development.The lower Yellow River(LYR)is characterized by a complex channel–floodplain system,which is prone to flooding but inhabits a large population on the floodplains.Many floodplain management modes have been presented,but implementation effects of these management modes have not been evaluated correctly.An integrated model was first proposed to evaluate the flood risks to people’s life and property,covering an improved module of two-dimensional(2D)morphodynamic processes and a module of flood risk evaluation for people,buildings and crops on the floodplains.Two simulation cases were then conducted to validate the model accuracy,including the hyperconcentrated flood event and dike-breach induced flood event occurring in the LYR.Finally,the integrated model was applied to key floodplains in the LYR,and the effects of different floodplain management modes were quantified on the risks to people’s life and property under an extreme flood event.Results indicate that:①Satisfactory accuracy was achieved in the simulation of these two flood events.The maximum sediment concentration was just underestimated by 9%,and the simulated inundation depth agreed well with the field record;②severe inundation was predicted to occur in most domains under the current topography(SchemeⅠ),which would be alleviated after implementing different floodplain management modes,with the area in slight inundation degree accounting for a large proportion under the mode of“construction of protection embankment”(SchemeⅡ)and the area in medium inundation degree occupying a high ratio under the mode of“floodplain partition harnessing”(SchemeⅢ);and③compared with SchemeⅠ,the high-risk area for people’s life and property would reduce by 21%–49%under SchemeⅡ,and by 35%–93%under SchemeⅢ.
