Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

THE DOUBLE-LAYER STRUCTURE OF THE HADLEY CIRCULATION AND ITS INTERDECADAL EVOLUTION CHARACTERISTICS

Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.

Numerical Analysis of the Structure of High-Strength Double-Layer Steel Plate Concrete Shaft by Drilling Method of Water-Bearing Weak Rock Formation

In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.

Impact of EBG Structures' Positions on the Performance of an EBG Antenna

Six circularly polarized patch antennas with electromagnetic band gap（EBG）arranged at different locations were studied.These EBG antennas were compared in terms of impedance bandwidth,axial ratio（AR）bandwidth and radiation patterns.When the EBG cells were placed closer to the edge of the substrate,the EBG antenna had a larger front radiation and a narrower bandwidth.Integrating the EBG cells closer to the center of the patch resulted in a wider impedance bandwidth,a wider axial ratio bandwidth and a decreased front gain.

Preparation and Microwave Absorbing Properties of Double-layer Fine Iron Tailings Cementitious Materials

To develop the microwave absorbing(MA)properties of cementitious material mixed with mine solid waste,the iron tailings cementitious microwave absorbing materials were prepared.The iron tailings was treated into different particle sizes by planetary ball mill,and the physicochemical properties of iron tailings were tested by laser particle size analyzer and scanning electron microscope(SEM).The electromagnetic parameters of iron tailings cementitious materials were characterized by a vector network analyzer and simulated MA properties,and the MA properties of iron tailings-cement composite system with steel fiber as absorber was studied.Based on the design of the single-layer structure,optimum mix ratio and thickness configuration method of double-layer structure were further studied,meanwhile,the mechanical properties and engineering application were analyzed and discussed.The results show that the particle size of iron tailings can afiect its electromagnetic behavior in cementitious materials,and the smaller particles lead the increase of demagnetisation efiect induced by domain wall motion and achieve better microwave absorbing properties in cementitious materials.When the thickness of matching layer and absorbing layer is 5 mm,the optimized microwave absorbing properties of C1/C3 double-layer cementitious material can obtain optimal RL value of-27.61 dB and efiective absorbing bandwidth of 0.97 GHz,which attributes to the synergistic efiect of impedance matching and attenuation characteristics.The double-layer microwave absorbing materials obtain excellent absorbing properties and show great design flexibility and diversity,which can be used as a suitable candidate for the preparation of favorable microwave absorbing cementitious materials.

小型化EBG结构双频牛仔可穿戴天线

实现了一种基于电磁带隙(EBG)结构的可穿戴牛仔天线,用于2.45 GHz和5.8 GHz双频段无线体域网(WBAN)通信。天线采用牛仔布料作为EBG结构基板和天线的介质基板,优化了天线的可穿戴性能;将天线分别在X方向和Y方向上进行弯折测试,通过对比其仿真和实测的结果,天线仍可满足可穿戴的需求。

Different Feeding Techniques of Microstrip Patch Antennas with Spiral Defected Ground Structure for Size Reduction and Ultra-Wide Band Operation

Different feeding techniques of microstrip patch antennas with different spiral defected ground structures are presented in this paper. The investigated structures illustrate some merits in designing multi-electromagnetic band-gap structures by adjusting the capacitance and changing the inductance through varying the width and length of spiral defected ground structure. Then by applying the three different spirals shapes (one, two and four arms) as the ground plane of microstrip patch antenna with different feeding techniques to create multi or ultra wide-band, improve the antenna gain and reduce the antenna size, it is found that the four arms spiral defected ground structure of microstrip patch antenna with offset feed gives good performance, electrical size reduction to about 75% as compared to the original patch size and ultra-wide bandwidth extends from 2 GHz up to 12 GHz with ?8 dB impedance bandwidth.

Double-layer microwave absorber of nanocrystalline strontium ferrite and iron microfibers

Microwave absorption properties of the nanocrystalline strontium ferrite （SrFe12O19） and iron （α-Fe） microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz 18 GHz. For the singlelayer absorbers, the nanocrystalline SrFe12O19 microfibers show some microwave absorptions at 6 GHz 18 GHz, with a minimum reflection loss （RL） value of -11.9 dB at 14.1 GHz for a specimen thickness of 3.0 mm, while for the nanocrystalline α-Fe microfibers, their absorptions largely take place at 15 GHz-18 GHz with the RL value exceeding -10 dB, with a minimum .RL value of about -24 dB at 17.5 GHz for a specimen thickness of 0.7 mm. For the doublelayer absorber with an absorbing layer of α-Fe microfibers with a thickness of 0.7 mm and matching layer of SrFe12O19 microfibers with a thickness of 1.3 ram, the minimum RL value is about -63 dB at 16.4 GHz and the absorption band width is about 6.7 GHz ranging from 11.3 GHz to 18 GHz with the RL value exceeding -10 dB which covers the whole Ku-band （12.4 GHz 18 GHz） and 27% of X-band （8.2 GHz 12.4 GHz）.

Double-layer indium doped zinc oxide for silicon thin-film solar cell prepared by ultrasonic spray pyrolysis

Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82 × 10^-3 Ω. cm and particle grains. The doublelayers structure is designed to fabricate the ZnO：In thin film with low resistivity （2.58 × 10^-3 Ω. cm） and good surface morphology. It is found that the surface morphology of the double-layer ZnO：In film strongly depends on the substratelayer, and the second-layer plays a large part in the resistivity of the doublewlayer ZnO：In thin film. Both total and direct transmittances of the double-layer ZnO：In film are above 80% in the visible light region. Single junction a-Si：H solar cell based on the double-layer ZnO：In as front electrode is also investigated.

曲面EBG结构带隙特性的研究

利用光学B ragg反射条件,设计了一种曲面电磁带隙结构。采用悬置微带线法,分析了其结构参数以及圆柱结构参数对带隙特性的影响。结果表明,结构参数对表面波带隙影响的规律与平面上一致,圆柱曲率对表面波带隙的影响不是太大,只是带隙中心频率略有下降。这一结论对在曲面共形天线上应用电磁带隙结构提高天线性能有重要的指导意义。

一种抑制封装中电源噪声的新型电磁带隙结构

面向高密度集成系统级封装中同步开关噪声引起的电源完整性问题,设计了一种新型电磁带隙结构。该结构由互补开口谐振环单元结构和类L-bridge型的单元间连桥结构形成,刻蚀缝隙以降低贴片的有效电容,增大连桥长宽比以增加贴片的有效电感。采用电磁全波仿真软件HFSS对所提出结构进行建模与仿真。仿真结果表明,以抑制深度-40 dB为标准,能够达到12.9 GHz的超宽禁带,明显优于常规电磁带隙结构,可以更好地抑制同步开关噪声。

EBG高阻表面结构的矩形波导宽边缝隙天线

本文提出了波导宽边缝隙天线提高方向图前后辐射比的一种新的实现途径.文中采用在波导宽边上附加EBG(electrom agnetic band-gap)高阻表面结构作为高阻接地面的新方法来提高波导缝隙天线方向图的前后辐射比,并对设计的EBG波导缝隙天线单元和阵列的辐射特性进行了仿真分析和实际测量,仿真和测量结果说明该方法对提高矩形波导宽边缝隙天线方向图的前后辐射比是十分有效的.

基于一维EBG结构的圆波导高增益天线

提出了一种基于一维电磁带隙(EBG)结构覆层来提高圆波导天线增益的新方法,利用数值分析方法对EBG结构和基于EBG结构圆波导高增益天线的电磁特性进行了仿真研究,并将它们与传统圆波导天线进行了比较。仿真和实验结果表明,应用这种EBG覆层结构可以有效地实现辐射能量的聚集,从而提高天线的增益,降低了天线副瓣电平,有效地改善了天线的辐射特性。

基于UC-EBG的紧凑微波光子晶体研究

为了提高微波光子晶体结构尺寸的紧凑性,根据其局域谐振原理和等效电路分析模型,对已有的电磁带隙(EBG)结构进行了改进,得到了一种新型EBG结构。该结构通过引入弯曲折线延长了电流长度,增大了等效电感效应,同时采用了螺旋结构,延长了等效磁流,增强了等效电容效应。实验结果表明,新结构能够产生频率带隙,其带隙中心频率比已有的EBG结构低48.1%,且相对带宽也有24.3%的改善,达到了实现紧凑宽带EBG结构的目的。

EBG结构磁性材料微带天线的研究与设计

以磁性材料(JV-5)作为基板,设计双L型结构的微带天线,带宽是普通基板的2倍以上,尺寸缩小了40%。在此基础上引入电磁带隙(EBG)结构,设计了一种基于磁性基板EBG结构的微带天线,该EBG结构采用接地板腐蚀性,即在地板上腐蚀出周期H型和圆形结构,采用电磁仿真软件HFSS14.0进行仿真设计。结果显示,与非磁性材料做基板的微带天线相比,EBG结构磁性材料具有小型化和宽频化突出优点,相对带宽达到10%以上,增益方面略有降低,引入EBG结构后能在一定程度上减小了天线的尺寸同时增大了天线的带宽,改善了天线的增益和辐射特性。

EBG对圆波导介质棒相控阵扫描特性的改善

将电磁带隙(EBG)结构应用到圆波导介质棒相控阵列中,利用EBG结构所具有的表面波带隙特性有效消除了相控阵中的扫描盲区。比较了无限阵列的扫描特性和有限阵列中心单元方向图在EBG加载前后的变化。仿真分析表明,以EBG结构作为圆波导介质棒相控阵的地平面,能有效消除扫描盲区,扩展扫描范围。

基于EBG结构的W波段宽带低损耗滤波器

基于电磁带隙结构(Electromagnetic Band-gap,EBG),本文设计实现了一种W波段宽带低损耗带通滤波器。通过EBG结构的频率带阻特性实现低通滤波,同时利用矩形波导固有的高通特性实现滤波器的低端频率截止。采用减宽波导加载微带EBG结构的方式将高通与低通结构相结合,经过适当的阻抗匹配设计,实现了覆盖75~110GHz全W波段的宽带滤波特性。EBG结构通过在5mil厚Rogers5880基片上制作一系列E面周期加载的谐振单元构成。实物测量结果表明,在75GHz^100GHz内,回波损耗典型值为-20d B,在100GHz^110GHz范围内,回波损耗典型值为-15d B,全带宽内插入损耗典型值小于1d B。该滤波器可用于各种W波段电子系统及测量设备中。

一种EBG微带滤波器的设计

在分析T型低通滤波器的周期性副响应的基础上，设计出满足布喇咯公式的电磁带隙（EBG）结构的微带滤波器。经模型仿真和实测，该滤波器阻带中心频率12GHz，阻带带宽5～6GHz，中心的阻带深度达到了-30dB左右，成功克服了以截止频率3GHz的微带线T型低通滤波器的周期性的第二副响应，即4倍其截止频率为中心的第二通带。

一种应用于柱面共形天线的EBG结构设计

表面波以及阵元之间的耦合一直以来都是共形天线设计中的难题。本文设计了一种新型EBG结构应用于柱形共形贴片天线,该结构采用基底打孔型EBG,孔的形状为椭圆形,使得天线的辐射频率落在EBG结构的带阻频率内。从而达到抑制表面波辐射和降低耦合的目的。文中分别从单元尺寸、介质层介电常数和介质层厚度对共形天线性能影响的角度进行了较细致的分析。

基于EBG结构的高阻抗反射背板研究

提出一种带缺陷结构的圆形贴片六角晶格EBG结构,构建宽带高阻抗反射背板。通过数值仿真软件CST,对正方晶格方型贴片、六角晶格圆形贴片以及带缺陷结构的高阻抗反射背板的带隙特性进行对比。实验制作了基于陶瓷基板的三种EBG结构高阻抗反射背板,实测得到正方形晶格贴片、六角晶格圆形贴片和缺陷型圆形贴片背板结构的带宽分别为1.68GHz、1.98GHz和2.24GHz。实验结果与仿真结果相吻合,表明带缺陷六角晶格圆形贴片EBG高阻抗表面相比于原有结构,在带隙特性方面具有更好的优势。