Objective Calibrated Automated Thrombogram(CAT) is a test to monitor the generation of thrombin. It can be described by four parameters: lag time, peak thrombin, endogenous thrombin potential (ETP) and time to pe...Objective Calibrated Automated Thrombogram(CAT) is a test to monitor the generation of thrombin. It can be described by four parameters: lag time, peak thrombin, endogenous thrombin potential (ETP) and time to peak (ttPeak). This study aims to determine the normal ranges of CAT parameters in Chinese, and evaluate whether thrombin generation is correlated with the concentration of heparin/Iow molecular weight heparin. Methods Plasma from 120 healthy subjects were collected to determine the normal rangea of CAT parameters in Chinese. Normal plasma pool (NPP, n=25) spiked with different concentrations of heparin or enoxaparin were used to detecte CAT parameters. The overall and age specific normal ranges of CAT parameters were calculated using descriptive statistics method with mean+-2SD. The correlation between CAT parameters and age or concentrations of heparin, enoxaparin were analyzed with linear regression model. Results The normal ranges for lag time, peak thrombin, ETP, ttPeak in the subjects were 3.648+2.465 min, 367.39+151.93 nmol/L, 2277+_1030 nmol/L.min and 6.372+_4.280 min respectively. Age was linearly correlated with lag time (r=-0.6583, P〈0.0002), peak thrombin (r=0.4863, P〈0.0002), ETP (r=0.3608, P〈0.0014) and ttPeak (r=-0.6323, P〈0.0002). The values of ETP/peak ratio were linearly correlated with concentrations of heparin. Conclusion The normal ranges of four CAT parameters for Chinese were determined. CAT parameters are associated with age. ETP/peak ratio could be used to monitor the process of anticoagulation therapy.展开更多
Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by sof...Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by software testing groups.This paper conducts an empirical study on the state-of-the-art automated tools for Java,i.e.,EvoSuite,Randoop,JDoop,JTeXpert,T3,and Tardis.We design a test workflow to facilitate the process,which can automatically run tools for test generation,collect data,and evaluate various metrics.Furthermore,we conduct empirical analysis on these six tools and their related techniques from different aspects,i.e.,code coverage,mutation score,test suite size,readability,and real fault detection ability.We discuss about the benefits and drawbacks of hybrid techniques based on experimental results.Besides,we introduce our experience in setting up and executing these tools,and summarize their usability and user-friendliness.Finally,we give some insights into automated tools in terms of test suite readability improvement,meaningful assertion generation,test suite reduction for random testing tools,and symbolic execution integration.展开更多
Based on updating of new generation weather radar software,compilation system of new generation weather radar case data could automatically back up data and compile radar case.Using C language and VC++6.0 development ...Based on updating of new generation weather radar software,compilation system of new generation weather radar case data could automatically back up data and compile radar case.Using C language and VC++6.0 development technology,the software realizes the automatic sorting and saving of radar base data,radar products and radar status information on different machines every day,and automatically creates various folders and files required for compiling data.By inputting the days,date,start and end times,renaming and compression of the base data,product data and status information could be automatically completed,to realize automation,batch,process and standardization of case data compilation.Since putting into the radar business,the operation has been stable and reliable.The working efficiency of business personnel has been improved,and a large number of manpower has been saved.It can be transplanted and popularized in other new generation weather radar stations.展开更多
This paper introduces a novel automatic physical synthesis methodology for analog circuits based on the signal-flow analysis.Circuit analysis sub-system adopts the newly advanced methodology,circuit topology analysis,...This paper introduces a novel automatic physical synthesis methodology for analog circuits based on the signal-flow analysis.Circuit analysis sub-system adopts the newly advanced methodology,circuit topology analysis,and circuit sensitivity analysis to generate layout constraints and control performance degradations.Considering the heuristic information about signal-flow,complexity of the methodology is less than the pure performance-driven methodology.And then these constraints are implemented in device generation,placement,and routing sub-systems separately,which makes the different constraints be satisfied at most easily implemented stages.Excellent circuit performance obtained by the methodology is demonstrated by practical circuit examples.展开更多
Automatically generating test cases by evolutionary algorithms to satisfy the path coverage criterion has attracted much research attention in software testing.In the context of generating test cases to cover many tar...Automatically generating test cases by evolutionary algorithms to satisfy the path coverage criterion has attracted much research attention in software testing.In the context of generating test cases to cover many target paths,the efficiency of existing methods needs to be further improved when infeasible or difficult paths exist in the program under test.This is because a significant amount of the search budget(i.e.,time allocated for the search to run)is consumed when computing fitness evaluations of individuals on infeasible or difficult paths.In this work,we present a feedback-directed mechanism that temporarily removes groups of paths from the target paths when no improvement is observed for these paths in subsequent generations.To fulfill this task,our strategy first organizes paths into groups.Then,in each generation,the objective scores of each individual for all paths in each group are summed up.For each group,the lowest value of the summed up objective scores among all individuals is assigned as the best aggregated score for a group.A group is removed when no improvement is observed in its best aggregated score over the last two generations.The experimental results show that the proposed approach can significantly improve path coverage rates for programs under test with infeasible or difficult paths in case of a limited search budget.In particular,the feedback-directed mechanism reduces wasting the search budget on infeasible paths or on difficult target paths that require many fitness evaluations before getting an improvement.展开更多
Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing t...Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing table) is often used in the industry, which is more rigid than a5-axis milling machine. Since impeller blades are designed with complex B-spline surfaces and impeller channels spaces vary significantly, it is more efficient to use multiple cutters as large as possible to cut a channel in sections and a blade surface in patches, instead of only using a small cutter to machine a whole blade and a channel. Unfortunately, no approach has been established to automatically calculate the largest diameters of cutters and their paths, which include the indexing table angles. To address this problem, an automated and optimization approach is proposed. Based on the structure of a 4?-axis machine, a geometric model for a cutter gouging/interfering the impeller is formulated, and an optimization model of the cutter diameter in terms of the indexing table angle is established at a cutter contact(CC) point on a blade surface. Then, the diameters of the tools,their orientations, and the indexing table angles are optimized, and each tool's paths are generated for machining its corresponding impeller section. As a test, an impeller is efficiently machined with these tools section by section; thus, this approach is valid. It can be directly used in the industry to improve efficiency of machining centrifugal impellers.展开更多
The ability to solve various constraints is a principal factor of automatic constraint solvers. Most object-oriented languages treat a character string as a primitive data type which is manipulated by string library f...The ability to solve various constraints is a principal factor of automatic constraint solvers. Most object-oriented languages treat a character string as a primitive data type which is manipulated by string library functions. Most constraint solvers have limitations on their input constraints, such as strong restrictions on the expressiveness of constraints or lack of the ability to solve hybrid constraints. These limitations hinder applying automated constraint solvers on program analysis techniques for programs containing strings and string manipulation functions. We propose an approach to automatically solve program constraints involving strings and string manipulation functions. Based on the character array model, we design a constraint language which contains primitive operations to precisely describe the constraints of commonly used string manipulation functions. The translated string constraints together with numeric constraints are then solved by a two- phase test generation procedure: firstly, a partial solution is obtained to satisfy the arithmetic constraints of the position variables, and the solution is utilized to simplify the string constraints into pure character array constraints; secondly, the pure array constraints are solved by an off-the-shelf array-specific theory based constraint solver. We integrate the approach into an automated testing tool to support the generation of string test cases, and then perform experiments. The results of the experiments prove that the integration of the proposed approach promotes the testing coverage of the existing testing tool, and the integrated tool has an advantage of handling specific string manipulation functions compared with an existing string solver.展开更多
Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst cas...Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.展开更多
In the modern analogue design, Transistor Level Fault Simulation (TLFS) plays the im-portant part since every fault in the whole circuit has to be simulated at that level. Unfortunately, it is a very CPU intensive tas...In the modern analogue design, Transistor Level Fault Simulation (TLFS) plays the im-portant part since every fault in the whole circuit has to be simulated at that level. Unfortunately, it is a very CPU intensive task even though it maintains the high accuracy. Therefore, High Level Fault Modeling (HLFM) and High Level Fault Simulation (HLFS) are required in order to alleviate the efforts of simulation. In this paper, different HLFM approaches are reviewed at the device level during last two decades. We clarify their domains of application and evaluate their strengths and current limitations. We also analyze causes of faults and introduce various test approaches.展开更多
A fault management dispatcher training simulator for large-scale Distribution Automation System (TDAS) is developed to train operators in distribution control center. This simulator is composed of independent simulati...A fault management dispatcher training simulator for large-scale Distribution Automation System (TDAS) is developed to train operators in distribution control center. This simulator is composed of independent simulation server and operator consoles and can be used for network analysis, network operation, fault management and evaluation. TDAS DB is duplicated online to the simulation server keeping the data security. The system can model distribution network penetrated with distributed generations (DG) using the real data from the TDAS DB. Network fault scenarios are automatically generated by calculating fault current and generating fault indicators. Also, manual entry of cry wolf alarm is available. Moreover, operation solution for scenario of fault isolation and service restoration is generated automatically so that trainee can check their operation result. Operator actions during training session are saved and can be played back as well as displayed on one-line diagram pictures.展开更多
A great concern for the modern distribution grid is how well it can withstand and respond to adverse conditions. One way that utilities are addressing this issue is by adding redundancy to their systems. Likewise, dis...A great concern for the modern distribution grid is how well it can withstand and respond to adverse conditions. One way that utilities are addressing this issue is by adding redundancy to their systems. Likewise, distributed generation (DG) is becoming an increasingly popular asset at the distribution level and the idea of microgrids operating as standalone systems apart from the bulk electric grid is quickly becoming a reality. This allows for greater flexibility as systems can now take on exponentially more configurations than the radial, one-way distribution systems of the past. These added capabilities, however, make the system reconfiguration with a much more complex problem causing utilities to question if they are operating their distribution systems optimally. In addition, tools like Supervisory Control and Data Acquisition (SCADA) and Distribution Automation (DA) allow for systems to be reconfigured faster than humans can make decisions on how to reconfigure them. As a result, this paper seeks to develop an automated partitioning scheme for distribution systems that can respond to varying system conditions while ensuring a variety of operational constraints on the final configuration. It uses linear programming and graph theory. Power flow is calculated externally to the LP and a feedback loop is used to recalculate the solution if a violation is found. Application to test systems shows that it can reconfigure systems containing any number of loops resulting in a radial configuration. It can connect multiple sources to a single microgrid if more capacity is needed to supply the microgrid’s load.展开更多
The new reality of smart distribution systems with use of generation sources of small and medium sizes brings new challenges for the operation of these systems. The complexity and the large number of nodes requires us...The new reality of smart distribution systems with use of generation sources of small and medium sizes brings new challenges for the operation of these systems. The complexity and the large number of nodes requires use of methods which can reduce the processing time of algorithms such as power flow, allowing its use in real time. This paper presents a known methodology for calculating the power flow in three phases using backward/forward sweep method, and also considering other network elements such as voltage regulators, shunt capacitors and sources of dispersed generation of types PV (active power and voltage) and PQ (active and reactive power). After that, new elements are introduced that allow the parallelization of this algorithm and an adequate distribution of work between the available processors. The algorithm was implemented using a multi-tiered architecture; the processing times were measured in many network configurations and compared with the same algorithm in the serial version.展开更多
The International Conference on Computer-Aided Design and Computer Graphics (CAD/Graphics) is a bian- nual international conference since 1989, which is affiliated with the Chinese Computer Federation (CCF). The c...The International Conference on Computer-Aided Design and Computer Graphics (CAD/Graphics) is a bian- nual international conference since 1989, which is affiliated with the Chinese Computer Federation (CCF). The conference is intended to provide an ideal forum for international researchers and developers to exchange new ideas on computer-aided design and computer graphics, electronic design automation, and visualization, to explore new ideas and trends.展开更多
A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed source...A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed sources can be switched independently and online from the gain-switched mode to the quasi-continuous wave mode to obtain optimal optical parameters for specific applications.To explore the physical mechanism of the semiconductor laser source,the rate equation that describes the carrier-photon transient change in a semiconductor laser cavity is numerically derived and solved.Subsequently,problems that need to be considered while designing the drive circuit are identified.The system evaluation indicates that the optical pulse frequency adjustment range is 250 Hz to 42 MHz,and the narrowest optical pulse output width is 80 ps.The pulse seed source can drive semiconductor lasers with different central wavelengths(1064,1550,and 1970 nm),and can also simultaneously drive two semiconductor lasers and output dual-band optical pulses.It can be used as a seed source for general high-power optical systems,and exhibits good application value and extensive market prospects.展开更多
基金supported by grant from the Ministry of Education of China(grant No.20110001120088)
文摘Objective Calibrated Automated Thrombogram(CAT) is a test to monitor the generation of thrombin. It can be described by four parameters: lag time, peak thrombin, endogenous thrombin potential (ETP) and time to peak (ttPeak). This study aims to determine the normal ranges of CAT parameters in Chinese, and evaluate whether thrombin generation is correlated with the concentration of heparin/Iow molecular weight heparin. Methods Plasma from 120 healthy subjects were collected to determine the normal rangea of CAT parameters in Chinese. Normal plasma pool (NPP, n=25) spiked with different concentrations of heparin or enoxaparin were used to detecte CAT parameters. The overall and age specific normal ranges of CAT parameters were calculated using descriptive statistics method with mean+-2SD. The correlation between CAT parameters and age or concentrations of heparin, enoxaparin were analyzed with linear regression model. Results The normal ranges for lag time, peak thrombin, ETP, ttPeak in the subjects were 3.648+2.465 min, 367.39+151.93 nmol/L, 2277+_1030 nmol/L.min and 6.372+_4.280 min respectively. Age was linearly correlated with lag time (r=-0.6583, P〈0.0002), peak thrombin (r=0.4863, P〈0.0002), ETP (r=0.3608, P〈0.0014) and ttPeak (r=-0.6323, P〈0.0002). The values of ETP/peak ratio were linearly correlated with concentrations of heparin. Conclusion The normal ranges of four CAT parameters for Chinese were determined. CAT parameters are associated with age. ETP/peak ratio could be used to monitor the process of anticoagulation therapy.
基金supported by the National Natural Science Foundation of China under Grant Nos.62072225 and 62025202.
文摘Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by software testing groups.This paper conducts an empirical study on the state-of-the-art automated tools for Java,i.e.,EvoSuite,Randoop,JDoop,JTeXpert,T3,and Tardis.We design a test workflow to facilitate the process,which can automatically run tools for test generation,collect data,and evaluate various metrics.Furthermore,we conduct empirical analysis on these six tools and their related techniques from different aspects,i.e.,code coverage,mutation score,test suite size,readability,and real fault detection ability.We discuss about the benefits and drawbacks of hybrid techniques based on experimental results.Besides,we introduce our experience in setting up and executing these tools,and summarize their usability and user-friendliness.Finally,we give some insights into automated tools in terms of test suite readability improvement,meaningful assertion generation,test suite reduction for random testing tools,and symbolic execution integration.
基金Supported by Scientific Research and Technology Development Project of Wuzhou Meteorological Bureau(WUQIKE2020001)。
文摘Based on updating of new generation weather radar software,compilation system of new generation weather radar case data could automatically back up data and compile radar case.Using C language and VC++6.0 development technology,the software realizes the automatic sorting and saving of radar base data,radar products and radar status information on different machines every day,and automatically creates various folders and files required for compiling data.By inputting the days,date,start and end times,renaming and compression of the base data,product data and status information could be automatically completed,to realize automation,batch,process and standardization of case data compilation.Since putting into the radar business,the operation has been stable and reliable.The working efficiency of business personnel has been improved,and a large number of manpower has been saved.It can be transplanted and popularized in other new generation weather radar stations.
文摘This paper introduces a novel automatic physical synthesis methodology for analog circuits based on the signal-flow analysis.Circuit analysis sub-system adopts the newly advanced methodology,circuit topology analysis,and circuit sensitivity analysis to generate layout constraints and control performance degradations.Considering the heuristic information about signal-flow,complexity of the methodology is less than the pure performance-driven methodology.And then these constraints are implemented in device generation,placement,and routing sub-systems separately,which makes the different constraints be satisfied at most easily implemented stages.Excellent circuit performance obtained by the methodology is demonstrated by practical circuit examples.
基金supported by the National Natural Science Foundation of China(No.61876207)the Natural Science Foundation of Guangdong Province(No.2022A1515011491)the Fundamental Research Funds for the Central Universities(No.2020ZYGXZR014).
文摘Automatically generating test cases by evolutionary algorithms to satisfy the path coverage criterion has attracted much research attention in software testing.In the context of generating test cases to cover many target paths,the efficiency of existing methods needs to be further improved when infeasible or difficult paths exist in the program under test.This is because a significant amount of the search budget(i.e.,time allocated for the search to run)is consumed when computing fitness evaluations of individuals on infeasible or difficult paths.In this work,we present a feedback-directed mechanism that temporarily removes groups of paths from the target paths when no improvement is observed for these paths in subsequent generations.To fulfill this task,our strategy first organizes paths into groups.Then,in each generation,the objective scores of each individual for all paths in each group are summed up.For each group,the lowest value of the summed up objective scores among all individuals is assigned as the best aggregated score for a group.A group is removed when no improvement is observed in its best aggregated score over the last two generations.The experimental results show that the proposed approach can significantly improve path coverage rates for programs under test with infeasible or difficult paths in case of a limited search budget.In particular,the feedback-directed mechanism reduces wasting the search budget on infeasible paths or on difficult target paths that require many fitness evaluations before getting an improvement.
基金supported by the National Natural Science Foundation of China(No.51475328)the National Science and Technology Major Project of China(No.2015ZX04001202)
文摘Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing table) is often used in the industry, which is more rigid than a5-axis milling machine. Since impeller blades are designed with complex B-spline surfaces and impeller channels spaces vary significantly, it is more efficient to use multiple cutters as large as possible to cut a channel in sections and a blade surface in patches, instead of only using a small cutter to machine a whole blade and a channel. Unfortunately, no approach has been established to automatically calculate the largest diameters of cutters and their paths, which include the indexing table angles. To address this problem, an automated and optimization approach is proposed. Based on the structure of a 4?-axis machine, a geometric model for a cutter gouging/interfering the impeller is formulated, and an optimization model of the cutter diameter in terms of the indexing table angle is established at a cutter contact(CC) point on a blade surface. Then, the diameters of the tools,their orientations, and the indexing table angles are optimized, and each tool's paths are generated for machining its corresponding impeller section. As a test, an impeller is efficiently machined with these tools section by section; thus, this approach is valid. It can be directly used in the industry to improve efficiency of machining centrifugal impellers.
基金This work was partially supported by the National Natural Science Foundation of China under Grant Nos. 61202080, 61702044, and 61502029.
文摘The ability to solve various constraints is a principal factor of automatic constraint solvers. Most object-oriented languages treat a character string as a primitive data type which is manipulated by string library functions. Most constraint solvers have limitations on their input constraints, such as strong restrictions on the expressiveness of constraints or lack of the ability to solve hybrid constraints. These limitations hinder applying automated constraint solvers on program analysis techniques for programs containing strings and string manipulation functions. We propose an approach to automatically solve program constraints involving strings and string manipulation functions. Based on the character array model, we design a constraint language which contains primitive operations to precisely describe the constraints of commonly used string manipulation functions. The translated string constraints together with numeric constraints are then solved by a two- phase test generation procedure: firstly, a partial solution is obtained to satisfy the arithmetic constraints of the position variables, and the solution is utilized to simplify the string constraints into pure character array constraints; secondly, the pure array constraints are solved by an off-the-shelf array-specific theory based constraint solver. We integrate the approach into an automated testing tool to support the generation of string test cases, and then perform experiments. The results of the experiments prove that the integration of the proposed approach promotes the testing coverage of the existing testing tool, and the integrated tool has an advantage of handling specific string manipulation functions compared with an existing string solver.
文摘Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.
基金Supported by the Fundamental Research Grand Scheme(Ref: frgs 2/2010/TK/UTP/0318, Ministry of High Education (MOHE)MalaysiaShort Tem Internal Research Fund (STIRF No. 20/10.11)) provided by Research Enterprise Office, Universiti Teknologi Petronas, Malaysia in 2010-2012
文摘In the modern analogue design, Transistor Level Fault Simulation (TLFS) plays the im-portant part since every fault in the whole circuit has to be simulated at that level. Unfortunately, it is a very CPU intensive task even though it maintains the high accuracy. Therefore, High Level Fault Modeling (HLFM) and High Level Fault Simulation (HLFS) are required in order to alleviate the efforts of simulation. In this paper, different HLFM approaches are reviewed at the device level during last two decades. We clarify their domains of application and evaluate their strengths and current limitations. We also analyze causes of faults and introduce various test approaches.
文摘A fault management dispatcher training simulator for large-scale Distribution Automation System (TDAS) is developed to train operators in distribution control center. This simulator is composed of independent simulation server and operator consoles and can be used for network analysis, network operation, fault management and evaluation. TDAS DB is duplicated online to the simulation server keeping the data security. The system can model distribution network penetrated with distributed generations (DG) using the real data from the TDAS DB. Network fault scenarios are automatically generated by calculating fault current and generating fault indicators. Also, manual entry of cry wolf alarm is available. Moreover, operation solution for scenario of fault isolation and service restoration is generated automatically so that trainee can check their operation result. Operator actions during training session are saved and can be played back as well as displayed on one-line diagram pictures.
文摘A great concern for the modern distribution grid is how well it can withstand and respond to adverse conditions. One way that utilities are addressing this issue is by adding redundancy to their systems. Likewise, distributed generation (DG) is becoming an increasingly popular asset at the distribution level and the idea of microgrids operating as standalone systems apart from the bulk electric grid is quickly becoming a reality. This allows for greater flexibility as systems can now take on exponentially more configurations than the radial, one-way distribution systems of the past. These added capabilities, however, make the system reconfiguration with a much more complex problem causing utilities to question if they are operating their distribution systems optimally. In addition, tools like Supervisory Control and Data Acquisition (SCADA) and Distribution Automation (DA) allow for systems to be reconfigured faster than humans can make decisions on how to reconfigure them. As a result, this paper seeks to develop an automated partitioning scheme for distribution systems that can respond to varying system conditions while ensuring a variety of operational constraints on the final configuration. It uses linear programming and graph theory. Power flow is calculated externally to the LP and a feedback loop is used to recalculate the solution if a violation is found. Application to test systems shows that it can reconfigure systems containing any number of loops resulting in a radial configuration. It can connect multiple sources to a single microgrid if more capacity is needed to supply the microgrid’s load.
文摘The new reality of smart distribution systems with use of generation sources of small and medium sizes brings new challenges for the operation of these systems. The complexity and the large number of nodes requires use of methods which can reduce the processing time of algorithms such as power flow, allowing its use in real time. This paper presents a known methodology for calculating the power flow in three phases using backward/forward sweep method, and also considering other network elements such as voltage regulators, shunt capacitors and sources of dispersed generation of types PV (active power and voltage) and PQ (active and reactive power). After that, new elements are introduced that allow the parallelization of this algorithm and an adequate distribution of work between the available processors. The algorithm was implemented using a multi-tiered architecture; the processing times were measured in many network configurations and compared with the same algorithm in the serial version.
文摘The International Conference on Computer-Aided Design and Computer Graphics (CAD/Graphics) is a bian- nual international conference since 1989, which is affiliated with the Chinese Computer Federation (CCF). The conference is intended to provide an ideal forum for international researchers and developers to exchange new ideas on computer-aided design and computer graphics, electronic design automation, and visualization, to explore new ideas and trends.
基金Project supported by the Basic Research Foundation of Knowledge Innovation Program of Shenzhen City,China(No.JCYJ20180301-171044707)the University-Enterprise Cooperation Research and Development Project of Shenzhen Technology University,China(Nos.2018010802002,2018010802005,and 2019310103001)。
文摘A set of semiconductor laser pulse seed sources based on an embedded chip is proposed.The greatest feature is that the optical pulse frequency and width can be independently adjusted in real time.The pulse seed sources can be switched independently and online from the gain-switched mode to the quasi-continuous wave mode to obtain optimal optical parameters for specific applications.To explore the physical mechanism of the semiconductor laser source,the rate equation that describes the carrier-photon transient change in a semiconductor laser cavity is numerically derived and solved.Subsequently,problems that need to be considered while designing the drive circuit are identified.The system evaluation indicates that the optical pulse frequency adjustment range is 250 Hz to 42 MHz,and the narrowest optical pulse output width is 80 ps.The pulse seed source can drive semiconductor lasers with different central wavelengths(1064,1550,and 1970 nm),and can also simultaneously drive two semiconductor lasers and output dual-band optical pulses.It can be used as a seed source for general high-power optical systems,and exhibits good application value and extensive market prospects.