Theory and Experimental Verification on Cymbal-shaped Slotted Valve Piezoelectric Pump

Valve piezoelectric pumps usually have larger flow rate than that of valveless ones. However, the traditional cantilever valve easily induces stress concentration which impacts the reliability of pumps. Therefore, a cymbal-shaped slotted check valve is proposed to be applied in a piezoelectric pump in order to reduce the stress concentration of the valve and thus improve the reliability of the piezoelectric pump. The structure and working principle of the piezoelectric pump are analyzed; the stress analysis of the cymbal-shaped slotted valve diaphragm is conducted. In addition, finite element software is employed to analyze the difference of the Von-Mises stress between the cymbal-shaped slotted diaphragm and the slotted flat diaphragm. The simulation results show that, the Von-Mises stress of cymbal-shaped slotted diaphragm is smaller than that of the slotted flat one. Furthermore, the cymbal-shaped slotted valve piezoelectric pump is also fabricated, and flow rate experiment is performed. The experimental results indicate that the flow rate of piezoelectric pump working in low frequencies(0 Hz < f< 50 Hz) is larger than that working in high frequencies(200 Hz < f< 2000 Hz). When driven at voltage of 160 V and frequency of 5 Hz, the pump reaches its maximum flow rate of 6.6 g/min. The experimental results validate the feasibility of the cymbal-shaped slotted check valve. This research can effectively solve the problem of stress concentration of valve piezoelectric pumps and is helpful for improving the reliability of them.

A method of elimination of undesired resonant points of microstrip antenna by cutting U-shaped slot on the ground

本文提出一种消除微带天线杂谐振点的方法,该微带天线为双层介质板,其谐振频率为2.4 GHz,共有两个杂谐振点分别在4.4 GHz附近及5.8 GHz附近。这两个杂谐振点破坏了微带天线的性能,故本文通过在接地板上合理地开U型缝来消除这两个谐振点,U型缝隙的长度为相应频率谐振点波长的一半;如果在缝隙上有开放端口,则U型缝隙长度为相应频率谐振点波长的四分之一。仿真结果表明:该方法可有效消除杂谐振点。

Double U-Shaped Slots Loaded Stacked Patch Antenna for Multiband Operation

The design of a seven-band stacked patch antenna for the C, X and Ku band is presented. The antenna consists of an H-slot loaded fed patch, stacked with dual U-slot loaded rectangular patch to generate the seven frequency bands. The total size of the antenna is 39.25 × 29.25 mm2. The multiband stacked patch antenna is studied and designed using IE3D simulator. For verification of simulation results, the antenna is analyzed by circuit theory concept. The simulated return loss, radiation pattern and gain are presented. Simulated results show that the antenna can be designed to cover the frequency bands from (4.24 GHz to 4.50 GHz, 5.02 GHz to 5.25 GHz) in C-band application, (7.84 GHz to 8.23 GHz) in X-band and (12.16 GHz to 12.35 GHz, 14.25 GHz to 14.76 GHz, 15.25 GHz to 15.51 GHz, 17.52 GHz to 17.86 GHz) in Ku band applications. The bandwidths of each band of the proposed antenna are 5.9%, 4.5%, 4.83%, 2.36%, 3.53%, 1.68% and 1.91%. Similarly the gains of the proposed band are 2.80 dBi, 4.39 dBi, 4.54 dBi, 10.26 dBi, 8.36 dBi and 9.91 dBi, respectively.

Triple Notched Band Characteristics UWB Antenna Using C-Shaped Slots and Slot-Type Capacitively-Loaded Loop (CLL)

Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.

N Design of an H-shaped Slot Multi-frequency Microstrip Antenna

Conventional slot microstrip antenna is analyzed,an h-shaped multi-frequency and miniaturization slot microstrip antenna is proposed.Numerical simulation is performed for the characteristics of the antenna with the software HFSS11.0,which is a kind of simulation software based on Finite Element Method,the simulation results shown that the antenna operated at 2.26~2.42GHz,2.67~2.82GHz,4.28~4.39GHz and 5.76~5.89GHz when the return loss S11<-10dB,the size reduced compare to general microstrip antenna,demonstrated the effectiveness of the design scheme.The antenna structure is simple and easily to be implemented,met the wireless LAN 802.11a/b/g/n mobile terminal antenna miniaturization and multi-band requirements.

Plus Shape Slotted Fractal Antenna for Wireless Applications

Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlines a multiband antenna design based on fractal concepts. Fractal antennas show multiband behavior due to self-similarity in their structure. The plus shaped fractal antenna has been designed on a substrate of dielectric constant €r = 4.4 and thickness 1.6mm. The proposed antenna is characterized by a compact size and it is microstrip feed fractal patch of order 1/3. It is observed that the antenna is radiating at multiple resonant frequencies. The resonant frequency is reduced from 2.2 GHz to 900 MHz after I & II iterations respectively. Thus considerable size reduction of 81.77% & overall bandwidth of 12.92% are achieved. The proposed antenna is simulated using the method of moment based commercial software (IE3D) and it is found that simulated results are in good agreement with the experimental results.

窄河谷大夹角挑流消能工体型优化研究

针对窄河谷大夹角条件下挑流消能易出现冲击两岸、冲坑过深的问题,采用水工整体模型试验方法对具有代表性的某水利枢纽深孔放水冲沙洞挑流鼻坎体型开展优化研究,并对比分析了水舌形态和下游河道冲刷特性。结果表明,不对称收缩的异型窄缝式消能工可使水流在狭窄河道归槽,水舌纵向拉伸效果较好,大幅减轻了河床冲刷;提出了收缩比、收缩角差、斜切面积比等特征参数适宜的挑流消能工体型,可供窄河谷大夹角条件下挑流消能设计参考。

节流槽形状对液压滑阀卡滞力的影响

液压滑阀是液压系统中的关键控制部件之一,其结构简单可靠,易于实现流量、压力控制。但是运行过程中由于热负荷产生的微小变形会导致阀芯卡滞现象的出现。当阀芯发生卡滞现象时,可能会严重降低液压阀的精度和灵敏度。基于热-流-固耦合模型,分析了节流槽形状对液压滑阀卡滞力的影响。首先建立了阀内固定开度流道模型,计算获得了不同节流槽形状下阀内流动特性;其次,将流体分析得到的温度场信息作为边界条件加载到热分析中,得到阀芯上的温度分布特性;最后研究了不同节流槽形状下阀芯间隙的变形量,分析阀芯卡滞的变化,为减小阀芯卡滞措施的研究提供参考。

基于DGS的紧凑型低通滤波器

文中提出一种基于缺陷地结构的新型低通滤波器。其由位于微带结构顶部的加宽微带线、位于接地层中的经典哑铃型缺陷地结构(DGS)和蛇形缝隙缺陷地结构(DGS)组成,结构设计紧凑,容易调整。文中选用0.01 dB等波纹的切比雪夫型低通滤波器,分别采用哑铃型DGS、蛇形缝隙DGS替换LPF原型电路中的电感,加宽微带线替换并联电容,同时将加宽微带线产生的寄生电感考虑进去。哑铃型DGS产生的高频衰减点加宽阻带,蛇形缝隙DGS提供的低频衰减点使得通带到阻带陡峭过渡。实验结果表明,所设计的截止频率为2.54 GHz的低通滤波器具有明显的截止频率响应,通带内插损均在0.9dB以下,阻带抑制均在21dB以下。经实物加工测试验证,所设计的低通滤波器实际结果与仿真结果基本一致,具有可行性。

On the Design of Plus Slotted Fractal Antenna Array

A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.

小型化多陷波新型超宽带天线设计与研究

提出了一种小型化新型多陷波超宽带(UWB)天线,陷波结构简单且紧凑,该天线体积仅为25 mm×18 mm×1 mm。天线由改进矩形辐射贴片和改进的半圆形接地板组成,天线的工作带宽为3.1~15.1 GHz。在辐射贴片上开U形窄缝隙和倒U形槽,实现了4.1~4.8 GHz频段和7.1~7.9 GHz频段的陷波特性,且在微带线上刻蚀U形窄缝隙,产生了5.4~5.9 GHz频段的陷波特性,通过优化测试表明,该天线能有效抑制INSAT波段(4.4~4.5 GHz)、国际卫星波段(4.5~4.8 GHz)波段、部分WLAN波段(5.725~5.825 GHz)以及X波段(7.25~7.75 GHz)多频段的窄带信号干扰。除陷波频段外,该天线具有良好的性能和全向辐射特性,适合应用于各类超宽带系统中。

基于多时隙业务联合整形的低能耗资源调度方法

面向未来6G移动通信系统超高数据密度的业务需求场景,为保障用户服务质量(QoS)并降低系统能耗,首先分析了移动通信系统的能耗构成,发现了系统能耗的非线性特征。然后在此基础上,设计了多时隙业务联合整形的低能耗资源调度方法。该方法通过感知用户业务流量和时延要求等需求侧的数据特征,利用深度强化学习算法在给定的多个时隙内动态调整基站资源分配策略。该资源分配策略降低了用户业务请求的非平稳性,从而减少了基站的非线性传输特性产生的额外能耗。最后通过软件仿真对比不同方法,验证了基于多时隙业务联合整形的理论和算法的正确性及有效性。

适用于道钉通信的V形缝隙天线的设计

设计了一种2.45 GHz频段下用于铸铝道钉通信的V形缝隙天线。天线尺寸为60 mm×40 mm,是依据道钉壳体内腔大小而设计的,且基板侧壁用铜皮包裹,起到电磁波能量向顶面汇聚的作用。天线顶面辐射贴片紧贴道钉的太阳能电池板,四周缩进基板边缘3 mm,电磁波能量可从电池板缝隙有效辐射出去。在辐射贴片的一条对角线上开对称的V形槽,在另一条对角线附近引入对称的2根短路探针,降低了天线的谐振频率,同时减小了天线的尺寸。天线工作频段为2.42~2.47 GHz,制作天线样机,通过无线通信模块测试,该天线在距离地面1 m高时,通信距离为66 m,在铸铝道钉腔体内且紧贴地面放置时,通信距离为35 m,超越现有道钉产品通信距离,符合实际工程应用需求。

宽带差分微带天线及其阵列设计

提出了一种新型的差分微带线馈电式宽带微带天线单元及阵列。首先,结合微带天线的场分布特点,提出了一种终端短路的平行差分微带线结构,实现了对其TM_(01)主模的有效激励;所提出的微带天线的辐射层与馈线层共用金属地,在扩展天线带宽的同时,有效降低了天线的剖面高度;然后,通过在馈线上加载U型槽,改善其带内匹配特性,将天线的阻抗带宽(电压驻波比≤2)从7.6%提高到了15.9%;最后,基于微带馈线的周期性场分布特点,仅通过对馈电结构进行长度扩展,无需额外的功分结构,便实现了一款1×2的差分微带天线阵列,并对其性能进行了仿真与分析。

一种基于S波段缝隙贴片的双频涡旋波天线

随着5G等新一代通信技术的迅速发展,对信道容量和频谱利用效率的需求越来越高。以双频天线为阵元进行组阵,将同时在两个谐振频率处产生OAM波束,大大提高了频谱的利用率。本文提出一种基于S波段缝隙贴片的双频涡旋波天线。其由八个阵元以60mm为半径均匀排列,阵元为切角U型槽天线,采用同轴馈电。通过调节该双频涡旋波天线各阵元的馈电相位,实现了在2.7 GHz和3.7 GHz处同时产生七种不同模态的OAM波束。仿真结果显示:其在低频处|S11|<-10dB的回波损耗带宽为0.24 GHz(2.57~2.81 GHz),高频处为0.25 GHz(3.57~3.82 GHz)。双频带内隔离度均大于23dB。本天线可以进一步提高雷达系统的分辨率。

Shape optimization of 3D curved slots and its application to the squirrel-cage elastic support design

The squirrel-cage elastic support is one of the most important components of an aero-engine rotor system.A proper structural design will favor the static and dynamic performances of the system.In view of the deficiency of the current shape optimization techniques,a new mapping approach is proposed to define shape design variables based on the parametric equations of 3D curves and surfaces.It is then applied for the slot shape optimization of a squirrel-cage elastic support.To this end,an automatic design procedure that integrates the Genetic Algorithm (GA) is developed to solve the problem.Two typical examples with different shape constraints are considered.Numerical results provide reasonable optimum designs for the improvement of stiffness and strength of the squirrel-cage elastic support.

低副瓣微带天线设计

针对传统低副瓣天线工作带宽窄的问题,设计了一种应用于低副瓣天线阵列设计的新型宽带微带天线单元。通过采用H型槽耦合馈电方法,天线单元工作带宽达到11%以上。同时,为实现天线阵列的宽频带工作特性,对宽带馈电网络进行了专门设计。馈电网络采用串、并结合的馈电方式,利用阻抗变换节实现所需要的天线单元馈电幅相分布。基于所设计的天线单元和馈电网络,设计了一种基于道尔夫-切比雪夫电流分布的C波段微带天线阵,并对天线进行了加工、测试。测试结果表明,所设计的天线具有低副瓣、窄波束、高增益的特性,天线的旁瓣电平抑制大于20 dB。

一种低剖面频率可重构天线的设计与研究

针对目前频率可重构天线存在的尺寸较大、频率可调范围不足、带宽窄且难以同时覆盖5G/WiMAX/WLAN等常用频段的问题,提出一种结构新颖的频率可重构天线,共有3种工作状态,可分别工作在5G/WiMAX/WLAN频段,天线的尺寸仅为26mm×32 mm×1 mm,更加适合用于小型移动通信设备。该天线通过结合一个新的辐射贴片元件以及开槽和开关来实现天线不同工作模式的切换。整体结构可分为微带贴片天线和直流偏置电路2部分,直流偏置电路由4个二极管构成的2组开关SW1、SW2和直流偏置线组成,通过对SW1和SW2的控制,天线可以在宽带和2种双频状态下工作,宽带工作频段为3.04~5.54 GHz,一种双频工作频段分别为2.86~3.50 GHz、5.09~6.17 GHz,另一种双频工作频段分别为2.98~3.84 GHz、4.61~5.88 GHz。对天线模型实物加工并进行了实测。优化测试表明,天线可以在宽带模式和2个双频工作模式下正常工作,且天线的可重构特性使其能在5G/WiMAX/WLAN不同通信频段下切换工作模式,适合用于5G/WiMAX/WLAN信号源聚集的复杂通信环境。

一种低剖面宽带宽角扫描相控阵天线设计

设计了一种可应用于宽带宽角扫描相控阵雷达的低剖面阵列天线,该天线采用“L”形探针馈电开槽贴片天线作为阵列单元,借助ANSYS HFSS仿真设计了9×9阵列天线,使该阵列天线在工作带宽3.16 GHz内,E面、H面扫描角度达到±50°。该天线剖面低、重量轻、宽带宽角扫描性能优异,在相控阵雷达天线中具有很好的应用前景。