This paper made a research on the Intelligent Optimization Operating Modeling of Pumped Storage Power Station in Hunan Power Grid. First it introduces the characteristics of Hunan power grid and analysis the practical...This paper made a research on the Intelligent Optimization Operating Modeling of Pumped Storage Power Station in Hunan Power Grid. First it introduces the characteristics of Hunan power grid and analysis the practical requirement of dispatching. Then it brings forward the intelligent optimization model and set up running model for pumped storage power station of Hei Mi-feng. At last, it introduces the application of pumped storage power station in Hunan power grid and proves the effectiveness of the optimization models.展开更多
Effective short-term prediction of regional voltage load is of great significance to the implementation of energy saving and emission reduction policies in China.Accurate prediction of real-time demand voltage can red...Effective short-term prediction of regional voltage load is of great significance to the implementation of energy saving and emission reduction policies in China.Accurate prediction of real-time demand voltage can reduce power waste and carbon emissions,make outstanding contributions to delaying global climate warming,and is conducive to global environmental protection and sustainable development.On the short-term load forecasting of power system,a variant model of RNN-LSTM is tested in this paper.It effectively solves the problem of gradient explosion and disappearance caused by large amount of data input in classical RNN.On the basis of this model,optimization experiments are carried out under different super parameters to achieve better prediction results.The experimental results show that the accuracy of test set reaches 99.8%,which proves that the method proposed in this paper has certain reference value.展开更多
The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers...The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers direct power trading, a novel security correction method based on DC power transfer distribution factor was proposed. Using the presented method to comply security correction, all the transactions that satisfy the specific requirements of maximizing social welfare are able to enter security correction process, and when the power of transmission line is out of limit, this method avoid the transaction which causes this problem is abandoned directly by introducing supplement transactions. The simulation has shown that the proposed security correction method of large consumers direct power trading based on DC power transfer distribution factor is effective.展开更多
With the increasing integration of emerging source-load types such as distributed photovoltaics,electric vehicles,and energy storage into distribution networks,the operational characteristics of these networks have ev...With the increasing integration of emerging source-load types such as distributed photovoltaics,electric vehicles,and energy storage into distribution networks,the operational characteristics of these networks have evolved from traditional single-load centers to complex multi-source,multi-load systems.This transition not only increases the difficulty of effectively classifying distribution networks due to their heightened complexity but also renders traditional energy management approaches-primarily focused on economic objectives-insufficient to meet the growing demands for flexible scheduling and dynamic response.To address these challenges,this paper proposes an adaptive multi-objective energy management strategy that accounts for the distinct operational requirements of distribution networks with a high penetration of new-type source-loads.The goal is to establish a comprehensive energy management framework that optimally balances energy efficiency,carbon reduction,and economic performance in modern distribution networks.To enhance classification accuracy,the strategy constructs amulti-dimensional scenario classification model that integrates environmental and climatic factors by analyzing the operational characteristics of new-type distribution networks and incorporating expert knowledge.An improved split-coupling K-means preclustering algorithm is employed to classify distribution networks effectively.Based on the classification results,fuzzy logic control is then utilized to dynamically optimize the weighting of each objective,allowing for an adaptive adjustment of priorities to achieve a flexible and responsivemulti-objective energy management strategy.The effectiveness of the proposed approach is validated through practical case studies.Simulation results indicate that the proposed method improves classification accuracy by 18.18%compared to traditional classification methods and enhances energy savings and carbon reduction by 4.34%and 20.94%,respectively,compared to the fixed-weight strategy.展开更多
Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition...Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition rate,structure and corrosion resistance performance of Ni-W-P coatings were studied by single factor method.Surface morphology,crystallographic structure and composition of Ni-W-P coatings were investigated by means of scanning electron microscopy,X-ray diffractometry and energy dispersive X-ray spectroscopy,respectively.Corrosion resistance performances of Ni-W-P coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in3.5%NaCl solution(mass fraction)and soil-containing solution.It was found that the pulse electroplated Ni-W-P coatings have superior corrosion resistance performance and the electroplating parameters significantly affect the structure and corrosion resistance performance of Ni-W-P coatings.The optimized parameters of pulse electroplating Ni-W-P coatings were as follows:pH2.0,temperature60°C,average current density4A/dm2,and pulse frequency600Hz.The Ni-W-P coating prepared under the optimized parameters has superior corrosion resistance(276.8kΩ)and compact surface without any noticeable defect.展开更多
The effects of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7) on corrosion behavior of Q235 steel in resistance reducing agent(RRA)containing sodium bentonite were studied by mass loss,scanning electron microscopy and electrochem...The effects of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7) on corrosion behavior of Q235 steel in resistance reducing agent(RRA)containing sodium bentonite were studied by mass loss,scanning electron microscopy and electrochemical measurement.The results showed that both the independent and mixed additions of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7),can reduce the corrosion rate of Q235 steel in RRA containing sodium bentonite.And the inhibition effect of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7)increased with their dosage increase.With the same dosage,the inhibition efficiency of the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7),was higher than that of their independent addition.The passivation effect of Q235 steel was easy to obtain in the RRA with the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7).The optimized inhibitor for the RRA containing sodium bentonite was the mixture of Na_(2)B_(4)O_(7) and Na_(2)MoO_(4) with a total concentration of 1.5 wt.%.Furthermore,the increase in corrosion potential E_(corr) and the decrease in corrosion current density i_(cor) in carbon steel were one of the important criteria for the formation of passivation film.展开更多
Recently, CulnS2/ZnS nanocrystals （CISZ NCs） have been widely used in many fields due to their excellent properties, such as tunable photoluminescence （PL） spectra, broad absorption, and non-toxicity. In order to ...Recently, CulnS2/ZnS nanocrystals （CISZ NCs） have been widely used in many fields due to their excellent properties, such as tunable photoluminescence （PL） spectra, broad absorption, and non-toxicity. In order to expand the application ofCISZ NCs, Gd3＋ was introduced into the host serving as paramagnetic modules to achieve magnetic resonance imaging （MRI） enhancement. MRI probes could provide high-resolution anatomical information. The derived Gd-Cu-In-S/ZnS nanocrystals （GCISZNCs） exhibited the strong orange photoluminescence with a quantum yield of 57.6% and significantly high longitudinal relaxivity （rl-20.4 mmol/s） in comparison with commmercial Magnevist （Gd-DTPA, r1=4.5mmol/s）. Effective enhancement of MRI and improved longitudinal relaxivity as well as lower cytotoxicity mode GCISZ NCs an ideal MRI probe, suggesting its potential and significance in practical biological and clinic applications in the future.展开更多
Text sentiment analysis is a common problem in the field of natural language processing that is often resolved by using convolutional neural networks(CNNs).However,most of these CNN models focus only on learning local...Text sentiment analysis is a common problem in the field of natural language processing that is often resolved by using convolutional neural networks(CNNs).However,most of these CNN models focus only on learning local features while ignoring global features.In this paper,based on traditional densely connected convolutional networks(DenseNet),a parallel DenseNet is proposed to realize sentiment analysis of short texts.First,this paper proposes two novel feature extraction blocks that are based on DenseNet and a multiscale convolutional neural network.Second,this paper solves the problem of ignoring global features in traditional CNN models by combining the original features with features extracted by the parallel feature extraction block,and then sending the combined features into the final classifier.Last,a model based on parallel DenseNet that is capable of simultaneously learning both local and global features of short texts and shows better performance on six different databases compared to other basic models is proposed.展开更多
With the development of information technology,cloud computing technology has brought many conveniences to all aspects of work and life.With the continuous promotion,popularization and vigorous development of e-govern...With the development of information technology,cloud computing technology has brought many conveniences to all aspects of work and life.With the continuous promotion,popularization and vigorous development of e-government and e-commerce,the number of documents in electronic form is getting larger and larger.Electronic document is an indispensable main tool and real record of e-government and business activities.How to scientifically and effectively manage electronic documents?This is an important issue faced by governments and enterprises in improving management efficiency,protecting state secrets or business secrets,and reducing management costs.This paper discusses the application of cloud computing technology in the construction of electronic file management system,proposes an architecture of electronic file management system based on cloud computing,and makes a more detailed discussion on key technologies and implementation.The electronic file management system is built on the cloud architecture to enable users to upload,download,share,set security roles,audit,and retrieve files based on multiple modes.An electronic file management system based on cloud computing can make full use of cloud storage,cloud security,and cloud computing technologies to achieve unified,reliable,and secure management of electronic files.展开更多
A long reach dense wavelength division multiplexing passive optical network(DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the ...A long reach dense wavelength division multiplexing passive optical network(DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers(RSOAs) are installed in both optical line terminal(OLT) and optical network units(ONUs) as colorless transmitter. The experimental results show that the bidirectional transmission for 1.2 Gbit/s data rate is achieved over 80 km single mode fiber(SMF).展开更多
This paper is research on the dispatching models for monthly generation plan which is manage the congestion considering the security constrains of the power grid. Since the monthly generation plan is the result of var...This paper is research on the dispatching models for monthly generation plan which is manage the congestion considering the security constrains of the power grid. Since the monthly generation plan is the result of vary monthly power exchange, including long-term power contract, power exchange among provinces and generation constitution exchanges, The application of monthly security constrained dispatching is with significant meaning for the security and stability of power grid. This paper brings forward the purpose and contents of security dispatching and introduces the working procedure and mathematic models. At last, the practical example of the Hunan Province power grid is introduced to explain the models.展开更多
The failure cause of a tinned copper wire clamp in marine atmosphere was studied systematically by X-ray photoelectron spectroscopy,scanning electron microscopy with energy dispersive spectroscopy and electrochemical ...The failure cause of a tinned copper wire clamp in marine atmosphere was studied systematically by X-ray photoelectron spectroscopy,scanning electron microscopy with energy dispersive spectroscopy and electrochemical measurements.The main components of the green rust on the surface of the damaged wire clamp are SnO_(2),CuO,Cu_(2)Cl(OH)_(3) and CuCO(OH)_(2).Much of green rust distributes at the platform edge along the axial direction on the crimp connection,and severe corrosion and corrosion pits occur at the platform edge zone along the axial direction.The enriching Cl-at the marine atmosphere and the existing O_(2) in air collectively enhance the corrosion process of the tin coating and the copper matrix.Finite element model results show that the residual stress and strain of the tin coating are the largest at the platform edge along the axial direction on the crimp connection,and the corresponding electrode potential of the tin coating at this zone drops significantly.The above results indicate that the residual strain increases the driving force of the corrosion electrochemical reactions and accelerates the corrosion rate and the pit corrosion of the tin coating at this zone.展开更多
Conventional resource provision algorithms focus on how to maximize resource utilization and meet a fixed constraint of response time which be written in service level agreement（SLA）.Unfortunately,the expected respo...Conventional resource provision algorithms focus on how to maximize resource utilization and meet a fixed constraint of response time which be written in service level agreement（SLA）.Unfortunately,the expected response time is highly variable and it is usually longer than the value of SLA.So,it leads to a poor resource utilization and unnecessary servers migration.We develop a framework for customer-driven dynamic resource allocation in cloud computing.Termed CDSMS（customer-driven service manage system）,and the framework’s contributions are twofold.First,it can reduce the total migration times by adjusting the value of parameters of response time dynamically according to customers’profiles.Second,it can choose a best resource provision algorithm automatically in different scenarios to improve resource utilization.Finally,we perform a serious experiment in a real cloud computing platform.Experimental results show that CDSMS provides a satisfactory solution for the prediction of expected response time and the interval period between two tasks and reduce the total resource usage cost.展开更多
In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slop...In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.展开更多
The system controlled in synchronous frame is commonly used. However, it is a problem how to transform the controller in synchronous frame to stationary frame. This paper deduces the stationary frame equivalent model ...The system controlled in synchronous frame is commonly used. However, it is a problem how to transform the controller in synchronous frame to stationary frame. This paper deduces the stationary frame equivalent model of arbitrarily controller in synchronous frame. The equivalent model can reflect the control performance of the input signal at different frequency accurately. The unified frequency-domain model of the overall system can be established using the equivalent model, and the guidance for frequency analysis and stability analysis can be provided. Theoretical derivation and simulation results verify the correctness and generality of the equivalent model.展开更多
Due to the strict requirements of extremely high accuracy and fast computational speed, real-time transient stability assessment(TSA) has always been a tough problem in power system analysis.Fortunately, the developme...Due to the strict requirements of extremely high accuracy and fast computational speed, real-time transient stability assessment(TSA) has always been a tough problem in power system analysis.Fortunately, the development of artificial intelligence and big data technologies provide the new prospective methods to this issue, and there have been some successful trials on using intelligent method, such as support vector machine(SVM) method.However, the traditional SVM method cannot avoid false classification, and the interpretability of the results needs to be strengthened and clear.This paper proposes a new strategy to solve the shortcomings of traditional SVM,which can improve the interpretability of results, and avoid the problem of false alarms and missed alarms.In this strategy, two improved SVMs, which are called aggressive support vector machine(ASVM) and conservative support vector machine(CSVM), are proposed to improve the accuracy of the classification.And two improved SVMs can ensure the stability or instability of the power system in most cases.For the small amount of cases with undetermined stability, a new concept of grey region(GR) is built to measure the uncertainty of the results, and GR can assessment the instable probability of the power system.Cases studies on IEEE 39-bus system and realistic provincial power grid illustrate the effectiveness and practicability of the proposed strategy.展开更多
The development of renewable energy sources(RES)is important to promote the energy transition and address climate change.Unlike the centralized RES power plants in the north of China,the distributed RES power plants i...The development of renewable energy sources(RES)is important to promote the energy transition and address climate change.Unlike the centralized RES power plants in the north of China,the distributed RES power plants in the south of China for achieving local consumption have become an effective alternative.However,the differences between RES and hydropower consumption have become obvious in some areas.This paper investigates the key factors affecting the abandonment of RES in the south of China.To alleviate the problem of RES consumption,various measures are discussed from the aspects of evaluating the consumption capacity of power grids at different voltage levels,optimizing demand-side management,flexibly for reforming the peak-shaving power sources of thermal power plants and strengthening inter-provincial transactions.The production simulation is used to validate the analysis and discussion.展开更多
Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing dat...Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing data,an improved random forest filling algorithm is proposed.As a result of the horizontal and vertical directions of the electric power data are based on the characteristics of time series.Therefore,the method of improved random forest filling missing data combines the methods of linear interpolation,matrix combination and matrix transposition to solve the problem of filling large amount of electric power missing data.The filling results show that the improved random forest filling algorithm is applicable to filling electric power data in various missing forms.What’s more,the accuracy of the filling results is high and the stability of the model is strong,which is beneficial in improving the quality of electric power data.展开更多
To solve the problem of the energy harvesting(EEH)effect of the condition monitoring devices power supply on the transmission line is not ideal.The authors designed three kinds of EEH schemes based on AC electric fiel...To solve the problem of the energy harvesting(EEH)effect of the condition monitoring devices power supply on the transmission line is not ideal.The authors designed three kinds of EEH schemes based on AC electric field induction,which can effectively improve the output power of load power supply.The EEH principle of each scheme was analysed in detail,and the influence factors such as the shape of outer energy harvester,capacitance compensation and impedance matching characteristics were analysed.Finally,the experiment showed that 140.9 mW of power was obtained in direct-mode field EEH when the line voltage level was 10 kV.The high-potential field EEH mode obtained 4.1 mW of power.The harvesting effect of the inner energy harvester with the same potential as the aluminium wire was obviously better,and 30.7 mW of power was obtained.Finally,based on the third mode,when the load resistance was 2200Ω,the rectifier received 23.7 mW DC output.The experimental results are in agreement with the theoretical analysis,which verifies the effectiveness of the electric field induction power supply technology.展开更多
Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission lines.However,the detection effectiveness is adversely impacted by complex and changeable en...Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission lines.However,the detection effectiveness is adversely impacted by complex and changeable environmental backgrounds,particularly under extreme weather that elevates accident risks.Therefore,this research proposes a high-precision intelligent strategy based on the synthetic weather algorithm and improved YOLOv7 for detecting insulator defects under extreme weather.The proposed meth-odology involves augmenting the dataset with synthetic rain,snow,and fog algorithm processing.Additionally,the original dataset undergoes augmentation through affine and colour transformations to improve model's generalisation performance under complex power inspection backgrounds.To achieve higher recognition accuracy in severe weather,an improved YOLOv7 algorithm for insulator defect detection is proposed,integrating focal loss with SIoU loss function and incorporating an optimised decoupled head structure.Experimental results indicate that the synthetic weather algorithm processing significantly improves the insulator defect detection accuracy under extreme weather,increasing the mean average precision by 2.4%.Furthermore,the authors’improved YOLOv7 model achieves 91.8%for the mean average precision,outperforming the benchmark model by 2.3%.With a detection speed of 46.5 frames per second,the model meets the requirement of real-time detection of insulators and their defects during power inspection.展开更多
文摘This paper made a research on the Intelligent Optimization Operating Modeling of Pumped Storage Power Station in Hunan Power Grid. First it introduces the characteristics of Hunan power grid and analysis the practical requirement of dispatching. Then it brings forward the intelligent optimization model and set up running model for pumped storage power station of Hei Mi-feng. At last, it introduces the application of pumped storage power station in Hunan power grid and proves the effectiveness of the optimization models.
基金Supported by Natural Science Foundation of Hunan Province(2020JJ4306)"Scientific Innovation Plan"of the Chinese Academy of Sciences(20194001882)。
文摘Effective short-term prediction of regional voltage load is of great significance to the implementation of energy saving and emission reduction policies in China.Accurate prediction of real-time demand voltage can reduce power waste and carbon emissions,make outstanding contributions to delaying global climate warming,and is conducive to global environmental protection and sustainable development.On the short-term load forecasting of power system,a variant model of RNN-LSTM is tested in this paper.It effectively solves the problem of gradient explosion and disappearance caused by large amount of data input in classical RNN.On the basis of this model,optimization experiments are carried out under different super parameters to achieve better prediction results.The experimental results show that the accuracy of test set reaches 99.8%,which proves that the method proposed in this paper has certain reference value.
文摘The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers direct power trading, a novel security correction method based on DC power transfer distribution factor was proposed. Using the presented method to comply security correction, all the transactions that satisfy the specific requirements of maximizing social welfare are able to enter security correction process, and when the power of transmission line is out of limit, this method avoid the transaction which causes this problem is abandoned directly by introducing supplement transactions. The simulation has shown that the proposed security correction method of large consumers direct power trading based on DC power transfer distribution factor is effective.
基金supported by the Science and Technology Project of the Headquarters of the State Grid Corporation(project code:5400-202323233A-1-1-ZN).
文摘With the increasing integration of emerging source-load types such as distributed photovoltaics,electric vehicles,and energy storage into distribution networks,the operational characteristics of these networks have evolved from traditional single-load centers to complex multi-source,multi-load systems.This transition not only increases the difficulty of effectively classifying distribution networks due to their heightened complexity but also renders traditional energy management approaches-primarily focused on economic objectives-insufficient to meet the growing demands for flexible scheduling and dynamic response.To address these challenges,this paper proposes an adaptive multi-objective energy management strategy that accounts for the distinct operational requirements of distribution networks with a high penetration of new-type source-loads.The goal is to establish a comprehensive energy management framework that optimally balances energy efficiency,carbon reduction,and economic performance in modern distribution networks.To enhance classification accuracy,the strategy constructs amulti-dimensional scenario classification model that integrates environmental and climatic factors by analyzing the operational characteristics of new-type distribution networks and incorporating expert knowledge.An improved split-coupling K-means preclustering algorithm is employed to classify distribution networks effectively.Based on the classification results,fuzzy logic control is then utilized to dynamically optimize the weighting of each objective,allowing for an adaptive adjustment of priorities to achieve a flexible and responsivemulti-objective energy management strategy.The effectiveness of the proposed approach is validated through practical case studies.Simulation results indicate that the proposed method improves classification accuracy by 18.18%compared to traditional classification methods and enhances energy savings and carbon reduction by 4.34%and 20.94%,respectively,compared to the fixed-weight strategy.
文摘Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition rate,structure and corrosion resistance performance of Ni-W-P coatings were studied by single factor method.Surface morphology,crystallographic structure and composition of Ni-W-P coatings were investigated by means of scanning electron microscopy,X-ray diffractometry and energy dispersive X-ray spectroscopy,respectively.Corrosion resistance performances of Ni-W-P coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in3.5%NaCl solution(mass fraction)and soil-containing solution.It was found that the pulse electroplated Ni-W-P coatings have superior corrosion resistance performance and the electroplating parameters significantly affect the structure and corrosion resistance performance of Ni-W-P coatings.The optimized parameters of pulse electroplating Ni-W-P coatings were as follows:pH2.0,temperature60°C,average current density4A/dm2,and pulse frequency600Hz.The Ni-W-P coating prepared under the optimized parameters has superior corrosion resistance(276.8kΩ)and compact surface without any noticeable defect.
基金support of Foundation of Science and Technology of State Grid(5216AJ20000U)Hunan Provincial Key R&D Program of China(2021GK2008).
文摘The effects of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7) on corrosion behavior of Q235 steel in resistance reducing agent(RRA)containing sodium bentonite were studied by mass loss,scanning electron microscopy and electrochemical measurement.The results showed that both the independent and mixed additions of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7),can reduce the corrosion rate of Q235 steel in RRA containing sodium bentonite.And the inhibition effect of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7)increased with their dosage increase.With the same dosage,the inhibition efficiency of the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7),was higher than that of their independent addition.The passivation effect of Q235 steel was easy to obtain in the RRA with the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7).The optimized inhibitor for the RRA containing sodium bentonite was the mixture of Na_(2)B_(4)O_(7) and Na_(2)MoO_(4) with a total concentration of 1.5 wt.%.Furthermore,the increase in corrosion potential E_(corr) and the decrease in corrosion current density i_(cor) in carbon steel were one of the important criteria for the formation of passivation film.
基金Project supported by the National Natural Science Foundation of China(51472087)Shanghai Municipal Natural Science Foundation(13ZR1412500)+1 种基金Innovation Program of Shanghai Municipal Education Commission(14ZZ050)the ECNU Reward for Out-standing Doctoral Dissertation Cultivation Plan of Action(PY2015041)
文摘Recently, CulnS2/ZnS nanocrystals （CISZ NCs） have been widely used in many fields due to their excellent properties, such as tunable photoluminescence （PL） spectra, broad absorption, and non-toxicity. In order to expand the application ofCISZ NCs, Gd3＋ was introduced into the host serving as paramagnetic modules to achieve magnetic resonance imaging （MRI） enhancement. MRI probes could provide high-resolution anatomical information. The derived Gd-Cu-In-S/ZnS nanocrystals （GCISZNCs） exhibited the strong orange photoluminescence with a quantum yield of 57.6% and significantly high longitudinal relaxivity （rl-20.4 mmol/s） in comparison with commmercial Magnevist （Gd-DTPA, r1=4.5mmol/s）. Effective enhancement of MRI and improved longitudinal relaxivity as well as lower cytotoxicity mode GCISZ NCs an ideal MRI probe, suggesting its potential and significance in practical biological and clinic applications in the future.
基金This work was supported by the National Key R&D Program of China under Grant Number 2018YFB1003205by the National Natural Science Foundation of China under Grant Numbers U1836208,U1536206,U1836110,61602253,and 61672294+3 种基金by the Startup Foundation for Introducing Talent of NUIST(1441102001002)by the Jiangsu Basic Research Programs-Natural Science Foundation under Grant Number BK20181407by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)fundby the Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET)fund,China.
文摘Text sentiment analysis is a common problem in the field of natural language processing that is often resolved by using convolutional neural networks(CNNs).However,most of these CNN models focus only on learning local features while ignoring global features.In this paper,based on traditional densely connected convolutional networks(DenseNet),a parallel DenseNet is proposed to realize sentiment analysis of short texts.First,this paper proposes two novel feature extraction blocks that are based on DenseNet and a multiscale convolutional neural network.Second,this paper solves the problem of ignoring global features in traditional CNN models by combining the original features with features extracted by the parallel feature extraction block,and then sending the combined features into the final classifier.Last,a model based on parallel DenseNet that is capable of simultaneously learning both local and global features of short texts and shows better performance on six different databases compared to other basic models is proposed.
基金research Grants from the National Social Science Foundation of China(Grant No.18FTQ005).The author of the grant is Shi Jin.The URL of the sponsor site is http://www.npopss-cn.gov.cn/.
文摘With the development of information technology,cloud computing technology has brought many conveniences to all aspects of work and life.With the continuous promotion,popularization and vigorous development of e-government and e-commerce,the number of documents in electronic form is getting larger and larger.Electronic document is an indispensable main tool and real record of e-government and business activities.How to scientifically and effectively manage electronic documents?This is an important issue faced by governments and enterprises in improving management efficiency,protecting state secrets or business secrets,and reducing management costs.This paper discusses the application of cloud computing technology in the construction of electronic file management system,proposes an architecture of electronic file management system based on cloud computing,and makes a more detailed discussion on key technologies and implementation.The electronic file management system is built on the cloud architecture to enable users to upload,download,share,set security roles,audit,and retrieve files based on multiple modes.An electronic file management system based on cloud computing can make full use of cloud storage,cloud security,and cloud computing technologies to achieve unified,reliable,and secure management of electronic files.
文摘A long reach dense wavelength division multiplexing passive optical network(DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers(RSOAs) are installed in both optical line terminal(OLT) and optical network units(ONUs) as colorless transmitter. The experimental results show that the bidirectional transmission for 1.2 Gbit/s data rate is achieved over 80 km single mode fiber(SMF).
文摘This paper is research on the dispatching models for monthly generation plan which is manage the congestion considering the security constrains of the power grid. Since the monthly generation plan is the result of vary monthly power exchange, including long-term power contract, power exchange among provinces and generation constitution exchanges, The application of monthly security constrained dispatching is with significant meaning for the security and stability of power grid. This paper brings forward the purpose and contents of security dispatching and introduces the working procedure and mathematic models. At last, the practical example of the Hunan Province power grid is introduced to explain the models.
基金supports of National Natural Science Foundation of China(51971191)Henan Provincial Key R&D Program of China(2021GK2008)Youth Backbone Teacher Training Program of Henan Province(2021GGJS004).
文摘The failure cause of a tinned copper wire clamp in marine atmosphere was studied systematically by X-ray photoelectron spectroscopy,scanning electron microscopy with energy dispersive spectroscopy and electrochemical measurements.The main components of the green rust on the surface of the damaged wire clamp are SnO_(2),CuO,Cu_(2)Cl(OH)_(3) and CuCO(OH)_(2).Much of green rust distributes at the platform edge along the axial direction on the crimp connection,and severe corrosion and corrosion pits occur at the platform edge zone along the axial direction.The enriching Cl-at the marine atmosphere and the existing O_(2) in air collectively enhance the corrosion process of the tin coating and the copper matrix.Finite element model results show that the residual stress and strain of the tin coating are the largest at the platform edge along the axial direction on the crimp connection,and the corresponding electrode potential of the tin coating at this zone drops significantly.The above results indicate that the residual strain increases the driving force of the corrosion electrochemical reactions and accelerates the corrosion rate and the pit corrosion of the tin coating at this zone.
基金Supported by the National Natural Science Foundation of China(61272454)
文摘Conventional resource provision algorithms focus on how to maximize resource utilization and meet a fixed constraint of response time which be written in service level agreement（SLA）.Unfortunately,the expected response time is highly variable and it is usually longer than the value of SLA.So,it leads to a poor resource utilization and unnecessary servers migration.We develop a framework for customer-driven dynamic resource allocation in cloud computing.Termed CDSMS（customer-driven service manage system）,and the framework’s contributions are twofold.First,it can reduce the total migration times by adjusting the value of parameters of response time dynamically according to customers’profiles.Second,it can choose a best resource provision algorithm automatically in different scenarios to improve resource utilization.Finally,we perform a serious experiment in a real cloud computing platform.Experimental results show that CDSMS provides a satisfactory solution for the prediction of expected response time and the interval period between two tasks and reduce the total resource usage cost.
文摘In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.
基金supported by SGCC Scientific and Technological Project(5216A018000J)National Key R&D Program of China(2016YFB0900900)
文摘The system controlled in synchronous frame is commonly used. However, it is a problem how to transform the controller in synchronous frame to stationary frame. This paper deduces the stationary frame equivalent model of arbitrarily controller in synchronous frame. The equivalent model can reflect the control performance of the input signal at different frequency accurately. The unified frequency-domain model of the overall system can be established using the equivalent model, and the guidance for frequency analysis and stability analysis can be provided. Theoretical derivation and simulation results verify the correctness and generality of the equivalent model.
基金supported by Science and Technology Project of State Grid Corporation of ChinaNational Natural Science Foundation of China (No.51777104)China State Key Laboratory of Power System (No.SKLD16Z08)
文摘Due to the strict requirements of extremely high accuracy and fast computational speed, real-time transient stability assessment(TSA) has always been a tough problem in power system analysis.Fortunately, the development of artificial intelligence and big data technologies provide the new prospective methods to this issue, and there have been some successful trials on using intelligent method, such as support vector machine(SVM) method.However, the traditional SVM method cannot avoid false classification, and the interpretability of the results needs to be strengthened and clear.This paper proposes a new strategy to solve the shortcomings of traditional SVM,which can improve the interpretability of results, and avoid the problem of false alarms and missed alarms.In this strategy, two improved SVMs, which are called aggressive support vector machine(ASVM) and conservative support vector machine(CSVM), are proposed to improve the accuracy of the classification.And two improved SVMs can ensure the stability or instability of the power system in most cases.For the small amount of cases with undetermined stability, a new concept of grey region(GR) is built to measure the uncertainty of the results, and GR can assessment the instable probability of the power system.Cases studies on IEEE 39-bus system and realistic provincial power grid illustrate the effectiveness and practicability of the proposed strategy.
基金This work was supported in part by Science and Technology Project SGCC(5216A218000P)Science-Technology Innovation Platform and Talents Program of Hunan Providence,China(2019TP1053).
文摘The development of renewable energy sources(RES)is important to promote the energy transition and address climate change.Unlike the centralized RES power plants in the north of China,the distributed RES power plants in the south of China for achieving local consumption have become an effective alternative.However,the differences between RES and hydropower consumption have become obvious in some areas.This paper investigates the key factors affecting the abandonment of RES in the south of China.To alleviate the problem of RES consumption,various measures are discussed from the aspects of evaluating the consumption capacity of power grids at different voltage levels,optimizing demand-side management,flexibly for reforming the peak-shaving power sources of thermal power plants and strengthening inter-provincial transactions.The production simulation is used to validate the analysis and discussion.
基金Supported by the State Grid Power Company of Hunan Province Science and Technology Project(No.5216A517000U).
文摘Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing data,an improved random forest filling algorithm is proposed.As a result of the horizontal and vertical directions of the electric power data are based on the characteristics of time series.Therefore,the method of improved random forest filling missing data combines the methods of linear interpolation,matrix combination and matrix transposition to solve the problem of filling large amount of electric power missing data.The filling results show that the improved random forest filling algorithm is applicable to filling electric power data in various missing forms.What’s more,the accuracy of the filling results is high and the stability of the model is strong,which is beneficial in improving the quality of electric power data.
文摘To solve the problem of the energy harvesting(EEH)effect of the condition monitoring devices power supply on the transmission line is not ideal.The authors designed three kinds of EEH schemes based on AC electric field induction,which can effectively improve the output power of load power supply.The EEH principle of each scheme was analysed in detail,and the influence factors such as the shape of outer energy harvester,capacitance compensation and impedance matching characteristics were analysed.Finally,the experiment showed that 140.9 mW of power was obtained in direct-mode field EEH when the line voltage level was 10 kV.The high-potential field EEH mode obtained 4.1 mW of power.The harvesting effect of the inner energy harvester with the same potential as the aluminium wire was obviously better,and 30.7 mW of power was obtained.Finally,based on the third mode,when the load resistance was 2200Ω,the rectifier received 23.7 mW DC output.The experimental results are in agreement with the theoretical analysis,which verifies the effectiveness of the electric field induction power supply technology.
基金National Natural Science Foundation of China,Grant/Award Number:52207158。
文摘Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission lines.However,the detection effectiveness is adversely impacted by complex and changeable environmental backgrounds,particularly under extreme weather that elevates accident risks.Therefore,this research proposes a high-precision intelligent strategy based on the synthetic weather algorithm and improved YOLOv7 for detecting insulator defects under extreme weather.The proposed meth-odology involves augmenting the dataset with synthetic rain,snow,and fog algorithm processing.Additionally,the original dataset undergoes augmentation through affine and colour transformations to improve model's generalisation performance under complex power inspection backgrounds.To achieve higher recognition accuracy in severe weather,an improved YOLOv7 algorithm for insulator defect detection is proposed,integrating focal loss with SIoU loss function and incorporating an optimised decoupled head structure.Experimental results indicate that the synthetic weather algorithm processing significantly improves the insulator defect detection accuracy under extreme weather,increasing the mean average precision by 2.4%.Furthermore,the authors’improved YOLOv7 model achieves 91.8%for the mean average precision,outperforming the benchmark model by 2.3%.With a detection speed of 46.5 frames per second,the model meets the requirement of real-time detection of insulators and their defects during power inspection.
