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设计了一种基于缺陷地结构(DGS)滤波器的高效率整流天线,可应用于低功率条件下的无线能量传输系统中。鉴于缝隙耦合微带天线具有较宽的阻带特性和高增益,因而被用于整流天线的接收天线,仿真得到该天线的谐振频率为5.8GHz,增益为8.2d B。整流电路采用DGS直通滤波器,以抑制交流信号传输到负载而被消耗。应用高频仿真软件HFSS对天线和滤波器进行仿真设计,应用ADS射频仿真软件对整流天线系统进行了仿真优化。仿真结果表明,该整流天线在3d Bm输入功率条件下,直流-微波转换效率达到了51.8%。 相似文献
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通过四线圈结构磁谐振式无线电能传输系统的电路模型推导出其传输效率表达式,用两线圈模型对参数进行初步设计得出谐振线圈的半径、匝数、线径等参数．利用四线圈模型对参数进行优化,调整线圈之间的互感使系统获得最大传输效率．通过两线圈模型和四线圈模型进行系统参数设计和分析,既保证了模型分析的准确性,又简化了谐振线圈设计过程,为谐振式无线电能传输系统的优化设计提供了理论依据． 相似文献
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为了探讨随机谐振现象的发生对信号、非线性系统和噪音的依赖性,特别是对噪音的依赖性,以互信息量为测度研究了二进制信号在非线性门限阵列的传输问题.在高斯混合噪音下计算了单门限系统和门限阵列的互信息量.通过研究得到:高斯混合噪音能改善信息的传输;随机谐振和超门限随机谐振现象不但在单门限系统中而且在门限阵列中存在;噪声分布中的参数影响随机谐振和超门限随机谐振现象的出现;随着门限阵列中门限单元数的增加,门限阵列能大大地改善信息的传输效果.这些结果进一步说明随机谐振和超门限随机谐振现象对噪声分布特性的依赖,同时也拓展了随机谐振和超门限随机谐振在信息传输中的应用. 相似文献
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在一维的完整光子晶体中对称插入两层等离子体缺陷形成双频滤波器.等离子是一种色散媒质,其等效折射率与电磁波频率和等离子体各参数有关,因而可以通过改变等离子体参数来改变光子晶体缺陷层的性质,从而使得缺陷层对电磁波的谐振频率发生变化,实现这种双频滤波器的频带的可调谐性.介质层和等离子体层分别采用了时域有限差分(FDTD)算法及分段线性电流密度卷积时域有限差分(PLJERC-FDTD)算法.数值仿真表明,这种结构的双频滤器可以在光子晶体禁带大范围可调谐,且透射频点具有较高的品质因数. 相似文献
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对于静电驱动的亚微米及纳米尺度的谐振器,衍射效应将会使其驱动及振动频率的光学检测变得更加困难,为克服衍射效应的影响,设计、制作了新型纳机电谐振梁——H型梁,使其产生高频振荡.并制作了双端固支谐振器以进行比较.2种谐振梁的最小宽度和厚度分别为180和200nm.对这2种结构的机械振动特性进行了实验研究.谐振器的基波振荡频率在6.8～20MHz之间,远低于理论预估值.通过模拟仿真发现,过腐蚀是导致振动频率低于理论值的重要原因之一.实验还发现:2种谐振器的谐振频率之差随着梁的长度增加而下降;在室温下减小样品腔的压强后,谐振器的品质因数可以大大提高. 相似文献
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《实验室研究与探索》2017,(7):56-58
采用典型的金属-介质-金属中刻蚀2条紧邻的缝隙结构,设计了一种新型的定向耦合器。分析本征模式的波导方程、反转粒子数与时间关系得到了定向耦合器的耦合条件。耦合器特性表明:设计的缝隙结构表面等离子能够通过缝隙1向缝隙2渗透,实现表面等离子在缝隙间的周期性传播,表面等离子传播在2 mm左右;耦合距离与缝隙大小表现为线性的关系,当缝隙设计成小于100 nm时,能够实现更高的耦合效率,更短的耦合距离;设计的定向耦合器可以通过减小缝隙间隔提高表面等离子传播的耦合效果。 相似文献
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彭直兴 《实验室研究与探索》2018,(3):59-61
采用典型的金属-介质-金属结构中刻蚀周期缝隙的光子晶体光纤(PCF)结构,设计了一种新型的定向耦合器,建立了PCF的H传输模型,得到了模型整体反射系数和透射系数的数学模型。基于计算机软件的偏振耦合特性分析表明,设计的PCF通过缝隙向缝隙渗透,能够实现缝隙周期性传播。周期缝隙的影响分析得出,缝隙小于金属层厚度时,能够实现更高的耦合效率,更短的耦合距离。由时间响应分析可以看出,模型具备了fs时间响应,时间动态特性有较高的非线性,能利用增益能量变换控制光子的弛豫率,实现PCF的耦合输出控制。 相似文献
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A novel defected ground structure （DGS） for the microstrip line is proposed in this paper. The DGS lattice has more defect parameters so that it can provide better performance than the conventional dumbbell-shaped DGS. Selectivity is improved by 97.2% with a sharpness factor of 24.6%. The method is applied to the design of a low-pass filter to confirm validity of the proposed DGS. 相似文献
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* A defected ground structure (DGS), realized byetching defects in backside metal ground, is devel-oped froma photonic bandgap (PBG) structure. DGScan change the equivalentcircuitand therefore changethe transformation characteristic of a microstrip line. PBG structure is a kind of artificial crystal, inwhich one dielectric material arranges periodically inanother. This structure can prevent the propagation ofthe electromagnetic wave in a special frequency band.PBG structure has a verybroa… 相似文献
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Seiji Isotani Helena M. Reis Danilo Alvares Anarosa A. F. Brandão Leônidas O. Brandão 《Interactive Learning Environments》2018,26(3):320-336
Interactive or Dynamic Geometry System (DGS) is a tool that help to teach and learn geometry using a computer-based interactive environment. Traditionally, the interaction with DGS is based on keyboard and mouse events where the functionalities are accessed using a menu of icons. Nevertheless, recent findings suggest that such a traditional model of interaction has a steep learning curve and is inadequate to develop DGS for devices with multi-touch screens. Thus, we propose a new interaction model for DGS based on a gesture dictionary which enables the construction and manipulation of geometric objects without the need of accessing a menu of icons. The dictionary is divided into three types: (i) kernel gestures: which are the basis for defining gestures; (ii) navigation gestures: related to the manipulation and editing of geometric objects; and (iii) basic gestures of construction: to construct geometric objects. To validate our interaction model, a DGS for mobile device, GeoTouch, has been developed using the proposed dictionary. Usability tests were performed comparing GeoTouch with three other DGS for mobile devices. The results indicate that the GeoTouch interface has fewer usability problems than the other three DGS software and it is easier to learn and interact with. 相似文献
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Colette Laborde 《Educational Studies in Mathematics》2000,44(1-2):151-161
Is proof activity in danger with the use of dynamic geometry systems(DGS)? The papers of this special issue report about various teachingsequences based on the use of such DGS and analyse the possible roles ofDGS in both the teaching and learning of proof. This paper is a reaction tothese four papers. Starting from them, it attempts to develop a globaldiscussion about the roles of DGS, by addressing four points: the variety ofpossible contexts for proof in a DGS, the dual nature of proof (cognitiveand social) as reflected in the `milieu' constructed around the use of aDGS, from observing to proving, and the overcoming of the oppositionbetween doing and proving. 相似文献
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Colette Laborde 《Educational Studies in Mathematics》2000,44(1-3):151-161
Is proof activity in danger with the use of dynamic geometry systems(DGS)? The papers of this special issue report about various teachingsequences based on the use of such DGS and analyse the possible roles ofDGS in both the teaching and learning of proof. This paper is a reaction tothese four papers. Starting from them, it attempts to develop a globaldiscussion about the roles of DGS, by addressing four points: the variety ofpossible contexts for proof in a DGS, the dual nature of proof (cognitiveand social) as reflected in the `milieu' constructed around the use of aDGS, from observing to proving, and the overcoming of the oppositionbetween doing and proving.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
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Haug T 《Journal of deaf studies and deaf education》2011,16(3):343-361
There is a current need for reliable and valid test instruments in different countries in order to monitor deaf children's sign language acquisition. However, very few tests are commercially available that offer strong evidence for their psychometric properties. A German Sign Language (DGS) test focusing on linguistic structures that are acquired in preschool- and school-aged children (4-8 years old) is urgently needed. Using the British Sign Language Receptive Skills Test, that has been standardized and has sound psychometric properties, as a template for adaptation thus provides a starting point for tests of a sign language that is less documented, such as DGS. This article makes a novel contribution to the field by examining linguistic, cultural, and methodological issues in the process of adapting a test from the source language to the target language. The adapted DGS test has sound psychometric properties and provides the basis for revision prior to standardization. 相似文献
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Adnan Baki Temel Kosa Bulent Guven 《British journal of educational technology : journal of the Council for Educational Technology》2011,42(2):291-310
The study compared the effects of dynamic geometry software and physical manipulatives on the spatial visualisation skills of first‐year pre‐service mathematics teachers. A pre‐ and post‐test quasi‐experimental design was used. The Purdue Spatial Visualisation Test (PSVT) was used for the pre‐ and post‐test. There were three treatment groups. The first group (n = 34) used Dynamic Geometry Software (DGS) Cabri 3D as a virtual manipulative and the second group (n = 32) used physical manipulatives. In the control group (n = 30), the students received traditional instruction. The results of the study showed that physical manipulatives and DGS‐based types of instruction are more effective in developing the students' spatial visualisation skills than traditional instruction. In addition, students in the DGS‐based group performed better than the physical manipulative‐based group in the views section of the PSVT. 相似文献
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INTRODUCTIONCoronaryarterydisease (CAD)continuestobethemajorcauseofmorbidityandmortalityinourcountry .TheactivityofbloodcoagulationfactorshasbeenshowntobeanimportantriskindicatorforCAD .However,circulatinglevelsofcoagulationfactorsmaynotaccuratelyreflectt… 相似文献
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Objective: To determine whether polymorphisms in the genes for coagulation factor. II, V, VII could predispose an individual
to increase risk for coronary artery disease (CAD) and/or myocardial infarction (MI) in Chinese. Methods: We screened coagulation
factor II(G20210A), V(G1691A), VII (R353Q and HVR4) genotype in 374 patients undergoing coronary angiography by polymerase
chain reaction and restriction fragment length polymorphism (PCR-RFLP) assay. Results: The R353Q and HVR4 gemotype of the
factor VII distribution was in accordance with Hardy-Weinberg equilibrium. The frequencies of FVII genotype or allele did
not show statistically significant differences between CAD group and controls or between male and female. The frequencies
of the Q allele and (RQ+QQ) genotype were significantly higher among the CAD patients without myocardial infarction (MI) history
than among those with MI history (P<0.05). However, HVR4 polymorphism was not significantly different within groups. We only find one normal control of factorII
(G20210A) mutation. No coagulation factor V(G1691A) mutation was found in the CAD patients and controls. Conclusion: The factor
II(G20210A), V(G1691A) mutation is absent and may not be a major genetic factor for CAD and/or MI; the Q allele of the R353
Q polymorphism of the factor VII gene may be a protective genetic factor against myocardial infarction in Chinese.
Project (No. 021103166) supported by a grant from the Key Project of Science and Technology Commission of Zhejiang Province,
China 相似文献
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The recent development of powerful new technologies such as dynamic geometry software (DGS) with drag capability has made possible the continuous variation of geometric configurations and allows one to quickly and easily investigate whether particular conjectures are true or not. Because of the inductive nature of the DGS, the experimental-theoretical gap that exists in the acquisition and justification of geometrical knowledge becomes an important pedagogical concern. In this article we discuss the implications of the development of this new software for the teaching of proof and making proof meaningful to students. We describe how three prospective primary school teachers explored problems in geometry and how their constructions and conjectures led them see proofs in DGS.
Constantinos Christou: Author for correspondence. 相似文献