In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the com...In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the complex formula derivation in the traditional amplifier circuit design process,and the design process is more simple and intuitive.Besides,it only takes three steps to build the load modulation network(LMN) of two power amplifiers(PA) of the DPA.Besides,a capacitor is used to replace the parasitic parameters of the transistor,and the LMN designed in the two modes is used for exploration and comparison.Further more,the output impedance of the peaking PA is introduced to make the reflection coefficient trajectory on Smith chart lowfrequency dispersion so as to expand the bandwidth of the DPA at the output power back-off(OBO) level.It would not affect the performance of DPA in the saturation(SAT) state.In this way,a broadband DPA can be implemented easily.To validate the proposed design method,a broadband DPA operating from 1.9to 2.6 GHz is designed and measured based on the proposed method.Under the continuous-wave excitation,the fabricated DPA has a 6 dB OBO efficiency of 48%-56% and a SAT efficiency of 64%-73% from 1.75 to 2.45 GHz,and the peak output power is 48.9-49.8 dBm.展开更多
Conception of graphic art,is widely increased in nowadays,because of persistent acquire of new ideas and art practices,which is key feature of modern art.As a result,variety of graphic art grew heavily-constantly acqu...Conception of graphic art,is widely increased in nowadays,because of persistent acquire of new ideas and art practices,which is key feature of modern art.As a result,variety of graphic art grew heavily-constantly acquiring new aspects and experimenting with new materials,but also not forgetting about classic techniques of graphic art.That is why Latvia’s contemporary art is rich with outstanding graphics artists,which is masters of their profession.But time goes and everything sees it’s end,and on Latvia’s art horizon start to appear new faces and new talents of Latvia’s graphics art,which already had their opportunity to demonstrate highest level of their mastery and creativity,not only in Latvia,but also on international level.Living in a rhythm of modern fast-paced technology and innovation era,Latvia’s graphic artists,still say“Yes!”,to classic techniques of graphic art-linocutting,lithography and drypointing.However,they are open-minded persons and like to experiment with new techniques(for example-digiprint),or if it is suitable for their idea-combine them,to reach their goal.Aim of this paper is to get acquainted with Latvia’s next-gen graphic artists,their ideas and views,as well with results of their creative,acquiring brief review of Latvia’s graphic trends in general.As a result reader will become familiar not only with Latvia’s domestic artists and their creativity,but also will get general review of the current trends in the world of graphic art,which is not only classic,but also very innovative,regarding of new materials and techniques.展开更多
反导体系是抵御威胁的重要防线,如何更加准确地描述、评估反导体系的作战效能是一件非常重要而复杂的工作。针对反导体系效能评估问题,分析反导作战体系的特征,结合图示评审技术(graphical evaluation and review technique,GERT),首先...反导体系是抵御威胁的重要防线,如何更加准确地描述、评估反导体系的作战效能是一件非常重要而复杂的工作。针对反导体系效能评估问题,分析反导作战体系的特征,结合图示评审技术(graphical evaluation and review technique,GERT),首先构建反导作战GERT网络,为效能评价提供模型框架;其次引入节点重要度思想,通过分析装备自身属性和关联装备的重要性,修正装备能力,并利用梅森公式和矩母函数的优良性质,解决基于节点重要度的反导体系作战效能评估问题;最后通过算例研究,说明基于节点重要度的反导体系效能评估方法的实用性和有效性。结果表明,基于节点重要度的效能评估方法能够有效量化装备异质性及网络结构对整体效能的影响,充分考虑关键节点对体系效能的影响,为反导体系的效能评估与优化提供了一种更贴合实际的新思路。展开更多
Starting from the traditional form of“graphic”architectural education,this paper explores a teaching method of entity construction experience,instrument assistance,and digital virtual expression symbiosis symbiosis ...Starting from the traditional form of“graphic”architectural education,this paper explores a teaching method of entity construction experience,instrument assistance,and digital virtual expression symbiosis symbiosis from three aspects:environmental perception,ontology perception,and extension perception.Using physical perception as a medium,and gradually rising from active perception to a comprehensive expression of visual audience perception through practical operation,it allows students to have a more comprehensive understanding of the meaning of architectural design on the basis of the“graphic”expression paradigm.展开更多
效能是衡量多阶段攻防对抗体系(system-of-systems,SoS)性能的重要指标,代表着完成任务的有效程度。在执行任务期间,外部环境不断变化,SoS效能存在时间依赖关系。针对此问题,运用拓展的图示评审技术(graphical evaluation and review te...效能是衡量多阶段攻防对抗体系(system-of-systems,SoS)性能的重要指标,代表着完成任务的有效程度。在执行任务期间,外部环境不断变化,SoS效能存在时间依赖关系。针对此问题,运用拓展的图示评审技术(graphical evaluation and review technique,GERT)来评估多阶段攻防对抗SoS效能。首先,根据SoS任务执行的多阶段特征构建GERT网络,并分析网络的传递特性。然后,在效能结果计算上,考虑时间因素,设计一个新的任务有效度参数来体现效能的时间依赖特征,利用c、z标记法,以获得关键组件系统执行关键任务的相关参数。最后,以导弹防御SoS的防御作战任务为例,对防御作战任务的执行效果进行评估,获得体系效能、作战时间、备弹量、导弹首次击中目标时间等指标数据,为体系编配方案优化提供涵盖更多信息的决策指标。展开更多
图示评审技术(graphic evaluation and review technique,GERT)解析法一般利用信号流图的拓扑特征(梅森公式)和矩母函数进行求解,但当GERT网络节点较多且结构复杂(回路众多)时,拓扑结构特征的分析十分困难,易出现错判或遗漏情况。针对...图示评审技术(graphic evaluation and review technique,GERT)解析法一般利用信号流图的拓扑特征(梅森公式)和矩母函数进行求解,但当GERT网络节点较多且结构复杂(回路众多)时,拓扑结构特征的分析十分困难,易出现错判或遗漏情况。针对此问题,将GERT网络用矩阵形式进行表征,分析了以梅森公式为基础的解析法与矩阵变换的关系,设计了两类基于矩阵的GERT求解算法。首先给出GERT网络与信号流图增益矩阵、流图增益矩阵一一对应关系,分析增益矩阵行列式变换与信号流图求解公式的对应关系,设计GERT网络的增益矩阵行列式变换求解算法。另外,研究GERT网络(信号流图)化简操作(消除自环、消除节点)在信号流图增益矩阵上的变换形式,提出了GERT网络解析的矩阵变换方法。最后用两个例子说明矩阵表征及求解模型的简便性和正确性,为GERT解析的计算机操作奠定基础。展开更多
基金National Natural Science Foundation of China (No. 62001061)。
文摘In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the complex formula derivation in the traditional amplifier circuit design process,and the design process is more simple and intuitive.Besides,it only takes three steps to build the load modulation network(LMN) of two power amplifiers(PA) of the DPA.Besides,a capacitor is used to replace the parasitic parameters of the transistor,and the LMN designed in the two modes is used for exploration and comparison.Further more,the output impedance of the peaking PA is introduced to make the reflection coefficient trajectory on Smith chart lowfrequency dispersion so as to expand the bandwidth of the DPA at the output power back-off(OBO) level.It would not affect the performance of DPA in the saturation(SAT) state.In this way,a broadband DPA can be implemented easily.To validate the proposed design method,a broadband DPA operating from 1.9to 2.6 GHz is designed and measured based on the proposed method.Under the continuous-wave excitation,the fabricated DPA has a 6 dB OBO efficiency of 48%-56% and a SAT efficiency of 64%-73% from 1.75 to 2.45 GHz,and the peak output power is 48.9-49.8 dBm.
文摘Conception of graphic art,is widely increased in nowadays,because of persistent acquire of new ideas and art practices,which is key feature of modern art.As a result,variety of graphic art grew heavily-constantly acquiring new aspects and experimenting with new materials,but also not forgetting about classic techniques of graphic art.That is why Latvia’s contemporary art is rich with outstanding graphics artists,which is masters of their profession.But time goes and everything sees it’s end,and on Latvia’s art horizon start to appear new faces and new talents of Latvia’s graphics art,which already had their opportunity to demonstrate highest level of their mastery and creativity,not only in Latvia,but also on international level.Living in a rhythm of modern fast-paced technology and innovation era,Latvia’s graphic artists,still say“Yes!”,to classic techniques of graphic art-linocutting,lithography and drypointing.However,they are open-minded persons and like to experiment with new techniques(for example-digiprint),or if it is suitable for their idea-combine them,to reach their goal.Aim of this paper is to get acquainted with Latvia’s next-gen graphic artists,their ideas and views,as well with results of their creative,acquiring brief review of Latvia’s graphic trends in general.As a result reader will become familiar not only with Latvia’s domestic artists and their creativity,but also will get general review of the current trends in the world of graphic art,which is not only classic,but also very innovative,regarding of new materials and techniques.
文摘反导体系是抵御威胁的重要防线,如何更加准确地描述、评估反导体系的作战效能是一件非常重要而复杂的工作。针对反导体系效能评估问题,分析反导作战体系的特征,结合图示评审技术(graphical evaluation and review technique,GERT),首先构建反导作战GERT网络,为效能评价提供模型框架;其次引入节点重要度思想,通过分析装备自身属性和关联装备的重要性,修正装备能力,并利用梅森公式和矩母函数的优良性质,解决基于节点重要度的反导体系作战效能评估问题;最后通过算例研究,说明基于节点重要度的反导体系效能评估方法的实用性和有效性。结果表明,基于节点重要度的效能评估方法能够有效量化装备异质性及网络结构对整体效能的影响,充分考虑关键节点对体系效能的影响,为反导体系的效能评估与优化提供了一种更贴合实际的新思路。
基金(2021jyxm0419,2022jyxm450,2021kcszsfkc137)Anhui Provincial Key Laboratory of Huizhou Architecture Open Subjects Funding Project(HPJZ-2020-03)Anhui Agricultural University Quality Engineering Project(2021auxsxxkc17,2021aujyxm59).
文摘Starting from the traditional form of“graphic”architectural education,this paper explores a teaching method of entity construction experience,instrument assistance,and digital virtual expression symbiosis symbiosis from three aspects:environmental perception,ontology perception,and extension perception.Using physical perception as a medium,and gradually rising from active perception to a comprehensive expression of visual audience perception through practical operation,it allows students to have a more comprehensive understanding of the meaning of architectural design on the basis of the“graphic”expression paradigm.
文摘效能是衡量多阶段攻防对抗体系(system-of-systems,SoS)性能的重要指标,代表着完成任务的有效程度。在执行任务期间,外部环境不断变化,SoS效能存在时间依赖关系。针对此问题,运用拓展的图示评审技术(graphical evaluation and review technique,GERT)来评估多阶段攻防对抗SoS效能。首先,根据SoS任务执行的多阶段特征构建GERT网络,并分析网络的传递特性。然后,在效能结果计算上,考虑时间因素,设计一个新的任务有效度参数来体现效能的时间依赖特征,利用c、z标记法,以获得关键组件系统执行关键任务的相关参数。最后,以导弹防御SoS的防御作战任务为例,对防御作战任务的执行效果进行评估,获得体系效能、作战时间、备弹量、导弹首次击中目标时间等指标数据,为体系编配方案优化提供涵盖更多信息的决策指标。
文摘图示评审技术(graphic evaluation and review technique,GERT)解析法一般利用信号流图的拓扑特征(梅森公式)和矩母函数进行求解,但当GERT网络节点较多且结构复杂(回路众多)时,拓扑结构特征的分析十分困难,易出现错判或遗漏情况。针对此问题,将GERT网络用矩阵形式进行表征,分析了以梅森公式为基础的解析法与矩阵变换的关系,设计了两类基于矩阵的GERT求解算法。首先给出GERT网络与信号流图增益矩阵、流图增益矩阵一一对应关系,分析增益矩阵行列式变换与信号流图求解公式的对应关系,设计GERT网络的增益矩阵行列式变换求解算法。另外,研究GERT网络(信号流图)化简操作(消除自环、消除节点)在信号流图增益矩阵上的变换形式,提出了GERT网络解析的矩阵变换方法。最后用两个例子说明矩阵表征及求解模型的简便性和正确性,为GERT解析的计算机操作奠定基础。
