The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil im...The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.展开更多
Abstract An f-coloring of a graph G is an edge-coloring of G such that each color appears at each vertex v ∈ V（G） at most f（v） times. The f-core of G is the subgraph of G induced by the vertices v of degree d（v...Abstract An f-coloring of a graph G is an edge-coloring of G such that each color appears at each vertex v ∈ V（G） at most f（v） times. The f-core of G is the subgraph of G induced by the vertices v of degree d（v） = f（v）maxv∈y（G）{ [d（v）/f（v）l}. In this paper, we find some necessary conditions for a simple graph, whose f-core has maximum degree two, to be of class 2 for f-colorings.展开更多
传统的F类和逆F类功率放大器的带宽不宽,且对于功放输出信号的谐波控制比较严格。在连续类功放理论的基础上,设计了一款在工作带宽内连续F类和连续逆F类模式转换的功率放大器。设计的功放采用了Cree公司的CGH40010F GaN HEMT晶体管。通...传统的F类和逆F类功率放大器的带宽不宽,且对于功放输出信号的谐波控制比较严格。在连续类功放理论的基础上,设计了一款在工作带宽内连续F类和连续逆F类模式转换的功率放大器。设计的功放采用了Cree公司的CGH40010F GaN HEMT晶体管。通过调整功放管输出端的谐波控制网络,控制谐波阻抗在Smith圆图中位置分布,从而在带宽内同时实现连续F类和连续逆F类的工作模式。制作了测试板,结果表明在2.4～4.2 GHz的带宽内,增益在11 dB以上,漏极效率为55%～82%,输出功率在39.5～41.9 dBm。采用了10 MHz的LTE单载波信号进行功放的数字预失真测试,功放的输出ACPR改善了6 dB以上。展开更多
针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起...针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起的性能偏差;输出匹配网络采用F类功率放大器谐波理论而设计。在1 920~1 980 MHz频段和电源电压3.4 V条件下,测得常温状态该功率放大器增益为27 d B;输出功率在28 d Bm时功率附加效率达到42%,邻信道功率比为?36 d Bc;在?20℃~80℃之间功率附加效率和邻信道功率比基本不变。展开更多
为了满足功率放大器对高效率和宽带的要求,介绍了一种连续逆F类功率放大器设计方法。在分析连续逆F类模式的基波和谐波阻抗基础上,提出了一种阶跃阻抗匹配网络电路。为了验证方法的有效性,设计并实现了一个1.7~2.9 GHz宽带的连续逆F类...为了满足功率放大器对高效率和宽带的要求,介绍了一种连续逆F类功率放大器设计方法。在分析连续逆F类模式的基波和谐波阻抗基础上,提出了一种阶跃阻抗匹配网络电路。为了验证方法的有效性,设计并实现了一个1.7~2.9 GHz宽带的连续逆F类功率放大器。测试结果表明,在工作带宽内,增益波动小于2 d B,饱和功率大于40.5 d Bm,峰值效率为65%~76%。该方法为宽带高效率放大器设计提供了有益的参考。展开更多
逆F类功放在接近饱和区工作时效率很高,将其与Doherty功放结构相结合,可以实现一种在大功率回退的情况下仍然具有很高效率的射频功率放大器。本文设计了一款基于Ga N HEMT晶体管的高效率的逆F类Doherty功率放大器,工作频带为910MHz^950...逆F类功放在接近饱和区工作时效率很高,将其与Doherty功放结构相结合,可以实现一种在大功率回退的情况下仍然具有很高效率的射频功率放大器。本文设计了一款基于Ga N HEMT晶体管的高效率的逆F类Doherty功率放大器,工作频带为910MHz^950MHz。单音信号测试结果显示,在930MHz处,功放回退7.5d B后漏极效率仍高达64.2%。使用3载波WCDMA信号作为测试信号,利用数字预失真技术进行线性化后,功放输出信号的上下边带邻信道功率比(ACPR)分别为-35.39d Bc和-35.9d Bc。展开更多
提出了一款4G频段全覆盖高输出功率高效率功率放大器。设计采用的是Cree公司提供的Ga N HEMT晶体管CGH40025F。基于F类功率放大器的设计理论,通过对晶体管的输入输出端均采用谐波控制网络,并将渐变式阻抗匹配这种宽带匹配方法应用到输...提出了一款4G频段全覆盖高输出功率高效率功率放大器。设计采用的是Cree公司提供的Ga N HEMT晶体管CGH40025F。基于F类功率放大器的设计理论,通过对晶体管的输入输出端均采用谐波控制网络,并将渐变式阻抗匹配这种宽带匹配方法应用到输入输出端的基波匹配当中。在实现二次谐波阻抗匹配至低阻抗区,三次谐波阻抗匹配至高阻抗区的同时基波阻抗被匹配至50Ω附近,从而有效提高了功率放大器的输出功率、效率和带宽。最终的测试结果表明在1.7~2.7 GHz频率范围内,漏极效率维持在62.55%~76%,输出功率在20~41W,增益在10 d B以上。仿真与实测结果基本一致。展开更多
基金supported by the Polish National Science Center(Grant No.2022/06/X/ST10/00320)received by Witold Tisler.
文摘The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.
基金Supported by National Natural Science Foundation of China(Grant Nos.10901097,11001055)Tianyuan Youth Foundation of Mathematics(Grant No.10926099)+1 种基金Natural Science Foundation of Shandong(Grant No.ZR2010AQ003)Shandong Province Higher Educational Science and Technology Program(Grant No.G13LI04)of China
文摘Abstract An f-coloring of a graph G is an edge-coloring of G such that each color appears at each vertex v ∈ V（G） at most f（v） times. The f-core of G is the subgraph of G induced by the vertices v of degree d（v） = f（v）maxv∈y（G）{ [d（v）/f（v）l}. In this paper, we find some necessary conditions for a simple graph, whose f-core has maximum degree two, to be of class 2 for f-colorings.
文摘针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起的性能偏差;输出匹配网络采用F类功率放大器谐波理论而设计。在1 920~1 980 MHz频段和电源电压3.4 V条件下,测得常温状态该功率放大器增益为27 d B;输出功率在28 d Bm时功率附加效率达到42%,邻信道功率比为?36 d Bc;在?20℃~80℃之间功率附加效率和邻信道功率比基本不变。
文摘为了满足功率放大器对高效率和宽带的要求,介绍了一种连续逆F类功率放大器设计方法。在分析连续逆F类模式的基波和谐波阻抗基础上,提出了一种阶跃阻抗匹配网络电路。为了验证方法的有效性,设计并实现了一个1.7~2.9 GHz宽带的连续逆F类功率放大器。测试结果表明,在工作带宽内,增益波动小于2 d B,饱和功率大于40.5 d Bm,峰值效率为65%~76%。该方法为宽带高效率放大器设计提供了有益的参考。
文摘提出了一款4G频段全覆盖高输出功率高效率功率放大器。设计采用的是Cree公司提供的Ga N HEMT晶体管CGH40025F。基于F类功率放大器的设计理论,通过对晶体管的输入输出端均采用谐波控制网络,并将渐变式阻抗匹配这种宽带匹配方法应用到输入输出端的基波匹配当中。在实现二次谐波阻抗匹配至低阻抗区,三次谐波阻抗匹配至高阻抗区的同时基波阻抗被匹配至50Ω附近,从而有效提高了功率放大器的输出功率、效率和带宽。最终的测试结果表明在1.7~2.7 GHz频率范围内,漏极效率维持在62.55%~76%,输出功率在20~41W,增益在10 d B以上。仿真与实测结果基本一致。
