Under the background of the new curriculum standard, the Ministry of Education has new requirements for mathematics classroom teaching in secondary vocational schools. Through the use of generative teaching mode, to e...Under the background of the new curriculum standard, the Ministry of Education has new requirements for mathematics classroom teaching in secondary vocational schools. Through the use of generative teaching mode, to enhance students' independent inquiry and learning ability, improve the teaching effect of secondary vocational mathematics classroom. This paper discusses the application of generative teaching in secondary vocational mathematics classroom, hoping to improve the quality of secondary vocational mathematics classroom teaching.展开更多
Craton basins are a significant petroliferous provenance. Having undergone multiple open- dose tectonic cycles and strong reworking of the late Cenozoic tectonic movement, the craton basins in China are highly broken....Craton basins are a significant petroliferous provenance. Having undergone multiple open- dose tectonic cycles and strong reworking of the late Cenozoic tectonic movement, the craton basins in China are highly broken. This has resulted in multi-source and multiphase hydrocarbon generation and later hydrocarbon accumulation so that a complicated spatial assemblage of primary, paraprimary and secondary oil-gas pools has been formed. The primary factors controlling hydrocarbon accumulation include hydrocarbon-generating depressions, paleouplifts, paleoslopes, unconformity surfaces, paleo-karst, faults and fissure systems as well as the later conservation conditions. In consequence, the strategy of exploration for China＇s craton basins is to identify the effective source rocks, pay attention to the different effects of paleohighs and late reworking, enhance studies of the secondary storage space, attach importance to the exploration of lithologic oil-gas reservoirs and natural gas pools, and approach consciously from the secondary oil pools to the targets near the source rocks. At the same time, a complete system of technologies and techniques must be built up.展开更多
A large number of oilfield water samples were analyzed in this work. Research on the relationship between the concentrations and distribution of dissolved hydrocarbons suggested that the contents and composition of di...A large number of oilfield water samples were analyzed in this work. Research on the relationship between the concentrations and distribution of dissolved hydrocarbons suggested that the contents and composition of dissolved hydrocarbons varied with the hydrocarbon-generating potential of reservoirs. The concentrations of dissolved hydrocarbons were low in dry layers, water layers and gas-water layers, but high in gas reservoirs and oil reservoirs, especially in gas reservoirs with condensed oil. Series of carbon-number alkanes were usually absent in oilfield water from dry layers, water layers and gas-water layers but abundant in oilfield water from oil-water reservoirs, gas reservoirs and oil reservoirs, whose carbon numbers varied most widely in oil reservoirs and least in gas reservoirs. A preliminary evaluation model for reservoir hydrocarbon-generating potential was established based on the characteristics of dissolved hydrocarbons in oilfield water to assist hydrocarbon exploration.展开更多
Antiviral software systems (AVSs) have problems in detecting polymorphic variants of viruses without specific signatures for such variants. Previous alignment-based approaches for automatic signature extraction have s...Antiviral software systems (AVSs) have problems in detecting polymorphic variants of viruses without specific signatures for such variants. Previous alignment-based approaches for automatic signature extraction have shown how signatures can be generated from consensuses found in polymorphic variant code. Such sequence alignment approaches required variable length viral code to be extended through gap insertions into much longer equal length code for signature extraction through data mining of consensuses. Non-nested generalized exemplars (NNge) are used in this paper in an attempt to further improve the automatic detection of polymorphic variants. The important contribution of this paper is to compare a variable length data mining technique using viral source code to the previously used equal length data mining technique obtained through sequence alignment. This comparison was achieved by conducting three different experiments (i.e. Experiments I-III). Although Experiments I and II generated unique and effective syntactic signatures, Experiment III generated the most effective signatures with an average detection rate of over 93%. The implications are that future, syntactic-based smart AVSs may be able to generate effective signatures automatically from malware code by adopting data mining and alignment techniques to cover for both known and unknown polymorphic variants and without the need for semantic (run-time) analysis.展开更多
针对现有起重机路径规划效率低的问题,提出一种基于改进快速探索随机树(rapidly-exploring random tree,RRT)的起重机路径规划算法。将广义距离替代经典RRT中欧氏距离,解决多自由度(degree of freedom,DOF)下RRT中距离的定义不明确的问...针对现有起重机路径规划效率低的问题,提出一种基于改进快速探索随机树(rapidly-exploring random tree,RRT)的起重机路径规划算法。将广义距离替代经典RRT中欧氏距离,解决多自由度(degree of freedom,DOF)下RRT中距离的定义不明确的问题。基于降维概念的胞元法,将C构型空间(configuration space,C空间)划分为大小相等的单元格,解决经典RRT中最近邻搜索(nearest neighbor search,NNS)在计算时间和资源方面效率低的问题。实验结果表明:在相同实验条件下,改进的RRT算法比双向RRT算法计算时间减少89.5%,能提高计算时间效率和提升搜寻路径质量,具有一定的参考价值。展开更多
为适应大容量同步发电机组并网点母线电压波动增加对自动电压调节器(automatic voltage regulator,AVR)系统响应能力的更高要求,提出一种基于含探索网络的双延迟深度确定性策略梯度(twin delayed deep deterministic policy gradient wi...为适应大容量同步发电机组并网点母线电压波动增加对自动电压调节器(automatic voltage regulator,AVR)系统响应能力的更高要求,提出一种基于含探索网络的双延迟深度确定性策略梯度(twin delayed deep deterministic policy gradient with Explorer network,TD3EN)算法的同步发电机励磁电压控制方法。首先,通过传递函数对同步发电机励磁调压子系统进行建模;然后建立TD3EN算法探索网络、动作网络和评价网络,并设置相应参数;接着利用TD3EN算法训练智能体,通过探索网络探索动作空间,并根据评价网络更新动作网络参数,使其为AVR提供控制信号;将训练完成的智能体接入AVR系统,实现对发电机机端电压的控制。仿真结果表明,所提方法提高了AVR系统响应调节指令和应对电压暂降的能力。展开更多
This paper proposes a novel state-dependent switched energy function(SdSEF)for general nonlinear autonomous systems,and constructs an SdSEF for doubly-fed induction generator(DFIG)-based wind power generation systems(...This paper proposes a novel state-dependent switched energy function(SdSEF)for general nonlinear autonomous systems,and constructs an SdSEF for doubly-fed induction generator(DFIG)-based wind power generation systems(WPGSs).Different from the conventional energy function,SdSEF is a piece-wise continuous function,and it satisfies the conditions of conventional energy functions on each of its continuous segments.SdSEF is designed to bridge the gap between the well-developed energy function theory and the description of system energy of complex nonlinear systems,such as power electronics converter systems.The stability criterion of nonlinear autonomous systems is investigated with SdSEF,and mathematical proof is presented.The SdSEF of a typical DFIGbased WPGS is simulated in the whole processes of a grid fault and fault recovery.Simulation results verify the negativeness of the derivative of each continuous segment of the SdSEF.展开更多
智能体路径规划算法旨在规划某个智能体的行为轨迹,使其在不碰到障碍物的情况下安全且高效地从起始点到达目标点.目前智能体路径规划算法已经被广泛应用到各种重要的物理信息系统中,因此在实际投入使用前对算法进行测试,以评估其性能是...智能体路径规划算法旨在规划某个智能体的行为轨迹,使其在不碰到障碍物的情况下安全且高效地从起始点到达目标点.目前智能体路径规划算法已经被广泛应用到各种重要的物理信息系统中,因此在实际投入使用前对算法进行测试,以评估其性能是否满足需求就非常重要.然而,作为路径规划算法的输入,任务空间中威胁障碍物的分布形式复杂且多样.此外,路径规划算法在为每个测试用例规划路径时,通常需要较高的运行代价.为了提升路径规划算法的测试效率,将动态随机测试思想引入到路径规划算法中,提出了面向智能体路径规划算法的动态随机测试方法(dynamic random testing approach for intelligent agent path planning algorithms,DRT-PP).具体来说,DRT-PP对路径规划任务空间进行离散划分,并在每个子区域内引入威胁生成概率,进而构建测试剖面,该测试剖面可以作为测试策略在测试用例生成过程中使用.此外,DRT-PP在测试过程中通过动态调整测试剖面,使其逐渐优化,从而提升测试效率.实验结果显示,与随机测试及自适应随机测试相比,DRT-PP方法能够在保证测试用例多样性的同时,生成更多能够暴露被测算法性能缺陷的测试用例.展开更多
文摘Under the background of the new curriculum standard, the Ministry of Education has new requirements for mathematics classroom teaching in secondary vocational schools. Through the use of generative teaching mode, to enhance students' independent inquiry and learning ability, improve the teaching effect of secondary vocational mathematics classroom. This paper discusses the application of generative teaching in secondary vocational mathematics classroom, hoping to improve the quality of secondary vocational mathematics classroom teaching.
文摘Craton basins are a significant petroliferous provenance. Having undergone multiple open- dose tectonic cycles and strong reworking of the late Cenozoic tectonic movement, the craton basins in China are highly broken. This has resulted in multi-source and multiphase hydrocarbon generation and later hydrocarbon accumulation so that a complicated spatial assemblage of primary, paraprimary and secondary oil-gas pools has been formed. The primary factors controlling hydrocarbon accumulation include hydrocarbon-generating depressions, paleouplifts, paleoslopes, unconformity surfaces, paleo-karst, faults and fissure systems as well as the later conservation conditions. In consequence, the strategy of exploration for China＇s craton basins is to identify the effective source rocks, pay attention to the different effects of paleohighs and late reworking, enhance studies of the secondary storage space, attach importance to the exploration of lithologic oil-gas reservoirs and natural gas pools, and approach consciously from the secondary oil pools to the targets near the source rocks. At the same time, a complete system of technologies and techniques must be built up.
文摘A large number of oilfield water samples were analyzed in this work. Research on the relationship between the concentrations and distribution of dissolved hydrocarbons suggested that the contents and composition of dissolved hydrocarbons varied with the hydrocarbon-generating potential of reservoirs. The concentrations of dissolved hydrocarbons were low in dry layers, water layers and gas-water layers, but high in gas reservoirs and oil reservoirs, especially in gas reservoirs with condensed oil. Series of carbon-number alkanes were usually absent in oilfield water from dry layers, water layers and gas-water layers but abundant in oilfield water from oil-water reservoirs, gas reservoirs and oil reservoirs, whose carbon numbers varied most widely in oil reservoirs and least in gas reservoirs. A preliminary evaluation model for reservoir hydrocarbon-generating potential was established based on the characteristics of dissolved hydrocarbons in oilfield water to assist hydrocarbon exploration.
文摘Antiviral software systems (AVSs) have problems in detecting polymorphic variants of viruses without specific signatures for such variants. Previous alignment-based approaches for automatic signature extraction have shown how signatures can be generated from consensuses found in polymorphic variant code. Such sequence alignment approaches required variable length viral code to be extended through gap insertions into much longer equal length code for signature extraction through data mining of consensuses. Non-nested generalized exemplars (NNge) are used in this paper in an attempt to further improve the automatic detection of polymorphic variants. The important contribution of this paper is to compare a variable length data mining technique using viral source code to the previously used equal length data mining technique obtained through sequence alignment. This comparison was achieved by conducting three different experiments (i.e. Experiments I-III). Although Experiments I and II generated unique and effective syntactic signatures, Experiment III generated the most effective signatures with an average detection rate of over 93%. The implications are that future, syntactic-based smart AVSs may be able to generate effective signatures automatically from malware code by adopting data mining and alignment techniques to cover for both known and unknown polymorphic variants and without the need for semantic (run-time) analysis.
文摘针对现有起重机路径规划效率低的问题,提出一种基于改进快速探索随机树(rapidly-exploring random tree,RRT)的起重机路径规划算法。将广义距离替代经典RRT中欧氏距离,解决多自由度(degree of freedom,DOF)下RRT中距离的定义不明确的问题。基于降维概念的胞元法,将C构型空间(configuration space,C空间)划分为大小相等的单元格,解决经典RRT中最近邻搜索(nearest neighbor search,NNS)在计算时间和资源方面效率低的问题。实验结果表明:在相同实验条件下,改进的RRT算法比双向RRT算法计算时间减少89.5%,能提高计算时间效率和提升搜寻路径质量,具有一定的参考价值。
文摘为适应大容量同步发电机组并网点母线电压波动增加对自动电压调节器(automatic voltage regulator,AVR)系统响应能力的更高要求,提出一种基于含探索网络的双延迟深度确定性策略梯度(twin delayed deep deterministic policy gradient with Explorer network,TD3EN)算法的同步发电机励磁电压控制方法。首先,通过传递函数对同步发电机励磁调压子系统进行建模;然后建立TD3EN算法探索网络、动作网络和评价网络,并设置相应参数;接着利用TD3EN算法训练智能体,通过探索网络探索动作空间,并根据评价网络更新动作网络参数,使其为AVR提供控制信号;将训练完成的智能体接入AVR系统,实现对发电机机端电压的控制。仿真结果表明,所提方法提高了AVR系统响应调节指令和应对电压暂降的能力。
基金This work was supported in part by the National Natural Science Foundation of China under Grant No.51807067 and No.U1866210Young Elite Scientists Sponsorship Program by CSEE under Grant No.CSEE-YESS-2018Fundamental Research Funds for the Central Universities of China under Grant No.2018MS77.
文摘This paper proposes a novel state-dependent switched energy function(SdSEF)for general nonlinear autonomous systems,and constructs an SdSEF for doubly-fed induction generator(DFIG)-based wind power generation systems(WPGSs).Different from the conventional energy function,SdSEF is a piece-wise continuous function,and it satisfies the conditions of conventional energy functions on each of its continuous segments.SdSEF is designed to bridge the gap between the well-developed energy function theory and the description of system energy of complex nonlinear systems,such as power electronics converter systems.The stability criterion of nonlinear autonomous systems is investigated with SdSEF,and mathematical proof is presented.The SdSEF of a typical DFIGbased WPGS is simulated in the whole processes of a grid fault and fault recovery.Simulation results verify the negativeness of the derivative of each continuous segment of the SdSEF.
文摘智能体路径规划算法旨在规划某个智能体的行为轨迹,使其在不碰到障碍物的情况下安全且高效地从起始点到达目标点.目前智能体路径规划算法已经被广泛应用到各种重要的物理信息系统中,因此在实际投入使用前对算法进行测试,以评估其性能是否满足需求就非常重要.然而,作为路径规划算法的输入,任务空间中威胁障碍物的分布形式复杂且多样.此外,路径规划算法在为每个测试用例规划路径时,通常需要较高的运行代价.为了提升路径规划算法的测试效率,将动态随机测试思想引入到路径规划算法中,提出了面向智能体路径规划算法的动态随机测试方法(dynamic random testing approach for intelligent agent path planning algorithms,DRT-PP).具体来说,DRT-PP对路径规划任务空间进行离散划分,并在每个子区域内引入威胁生成概率,进而构建测试剖面,该测试剖面可以作为测试策略在测试用例生成过程中使用.此外,DRT-PP在测试过程中通过动态调整测试剖面,使其逐渐优化,从而提升测试效率.实验结果显示,与随机测试及自适应随机测试相比,DRT-PP方法能够在保证测试用例多样性的同时,生成更多能够暴露被测算法性能缺陷的测试用例.
