一种6~18 GHz宽带高精度有源移相器

设计了一种6 bit 6~18 GHz工作频段的宽带高精度有源移相器。片上集成了输入无源巴伦、逻辑编码器、RC多相滤波器、矢量合成单元、数控单元等。该移相器的设计采用55 nm CMOS工艺实现,芯片尺寸为1.29 mm×0.9 mm,移相器核心尺寸为1.02 mm×0.58 mm。后仿结果表明,在6~18 GHz频率范围内,增益误差RMS值小于1 dB,相位误差RMS值小于0.75°,输入回波损耗、输出回波损耗分别小于-8.5 dB、-8.9 dB,芯片总功耗为20.7 mW。该6 bit移相器的相对带宽为100%,覆盖C、X和Ku波段,适用于雷达探测等领域。     

Removal of vanadium from wastewater by multi-walled carbon nanotubes

Nitric acid heating reflux modified multi-walled carbon nanotubes (HMWCNTs) were used for the removal of vanadium(V) in aqueous solution. The removal rate of vanadium(V) decreased with the increase of the initial vanadium(V) concentration and the solution pH, and increased with the increase of reaction time, HMWCNTs amount and solution temperature. The adsorption equilibrium and dynamic kinetics fitted the Langmuir adsorption isotherm and pseudo-second order models. The results obtained by scanning electron micrography and Fourier transform infrared spectroscopy analysis revealed that the hydroxyl and carboxyl functional groups are mainly responsible for the vanadium adsorption. This study showed that the HMWCNTs proved to be a considerable adsorbent for the removal of vanadium from wastewater.     

Phase adjustment for multistatic passive radar imaging based on image entropy and image contrast

Multistatic passive radar imaging system (MPRIS) does not behave as well as traditional inverse synthetic aperture radar (ISAR) imaging system does on account of the limited illuminators of opportunity and relatively narrow bandwidth of the signals. Furthermore, in the MPRIS, limited by the unavoidable measurement errors of the positions of the illuminators or receivers, or the manoeuvrability of the moving target, the translation motion of the target cannot be compensated accurately, in which the echo will be contaminated by an error phase, resulting in the occurrence of serious image defocus and the degeneracy of the image quality. In this article, two nonparametric autofocusing techniques based on the principles of minimum entropy and maximum contrast, respectively, are proposed to deal with the undesired problems under the multistate geographical configuration consisting of one illuminator and several receivers distributed around a target. The error phase is corrected by introducing an adjustment phase in the frequency domain and the adjustment phase can be searched by iteratively solving an equation that is derived by optimizing the quality measure of the image. Since no assumption is made during the derivation, the proposed techniques could be used to compensate any form of the phase error. In addition, the influence of the multistatic configuration on the image resolution is analysed and an optimized configuration is obtained. The effectiveness of the proposed algorithms is verified via the theoretical derivations and simulations.     

基于ASP.NET的旅游网站的设计与实现

本文通过对旅游行业现状进行分析提出了基于ASP.NET的开发思路,介绍了旅游网站的功能设计、数据库设计和具体模块的实现代码。旅游网站包括旅游信息浏览、预定线路和后台管理等功能,通过旅游网站,可以满足游客的个性化需求,提高旅游服务质量,增加效益。     

基于PDE和小波分析的破损路面检测技术

提出了一种基于PDE和小波分析的破损路面检测技术。通过CCD采集路面信息,并运用PDE进行去噪处理,从而很好地保留原始图像的边缘和纹理;利用小波分析进行边缘检测,再采用Canny算法对图像边缘进行提取,以确定破损路面的位置。实验结果表明,检测结果与实际结果相吻合。     

一种基于Nios II的喷涂控制系统设计方案

文中介绍基于NiosII处理器的嵌入式改进喷涂控制系统的实现。该系统通过在SOPC加载Nios软核和相应的外围电路,利用FPGA开发板和NiosII的定制指令来实现。该系统具有开发周期短、成本低、易于实现等优点。     

Novel porous carbon felt cathode modified by cyclic voltammetric electrodeposited polypyrrole and anthraquinone 2-sulfonate for an efficient electro-Fenton process

A novelty two-step synthesized porous carbon felt (PCF) cathode modified by cyclic voltammetric (CV) electrodeposited polypyrrole (Ppy) and anthraquinone 2-sulfonate (AQS) (PCF/Ppy/AQS) for an efficient electro-Fenton process has been investigated. Brunauer Emmett Teller (BET) and scanning electron microscope (SEM) measurements verified the three-dimensional porous structure of the PCF, revealing that the specific surface area was approximately 2.5 times higher than that of the bare carbon felt (CF), which ensured more active sites available for oxygen reduction reaction (ORR). In addition, the electrodeposited Ppy decreases the charge transfer resistance (R_ct) of the PCF cathode. AQS, a type of anthraquinone that can serve as an oxygen reduction catalyzer, could accelerate the ORR process and subsequently improve the performance of the electro-Fenton system. Rotating disk electrode (RDE) analysis confirmed that the ORR catalyzed by AQS was a double-electron reduction process, which contributed to hydrogen peroxide (H₂O₂) generation. The removal efficiency of total organic carbon (TOC) from Rhodamine B (RhB) could reach 51% within 1 h in the electro-Fenton system equipped with the PCF/Ppy/AQS, resulting in an improvement of approximately 24% compared with the bare CF cathode without porous treatment. The cycle experiment showed a good stability of the PCF/Ppy/AQS cathode. Additionally, the possible mechanism of degradation process in the electro-Fenton equipped with the PCF/Ppy/AQS cathode was proposed based on the electron paramagnetic resonance (EPR) analysis and quenching experiment. The novel fabricated PCF/Ppy/AQS provides an alternative as a high-efficiency cathode, yielding energy savings in the electro-Fenton system.     

Grain growth kinetics and growth mechanism of columnar Al2O3 crystals in xNb2O5–7.5La2O3-Al2O3 ceramic composites

xNb₂O₅–7.5La₂O₃-Al₂O₃ ceramic composites with in-situ-grown columnar Al₂O₃ crystals were successfully prepared by microwave sintering at 1450–1525?°C using α-Al₂O₃, Nb₂O₅, and La₂O₃ powders as raw materials. X-ray diffraction results indicated that the main phases were Al₂O₃, LaNbO₄, and Nb₂O₅ in the prepared samples. A field emission scanning electron microscope (FESEM) showed that the Al₂O₃ crystals appeared as columnar in the structure. Moreover, the grain size of the columnar Al₂O₃ crystals increased with the Nb₂O₅ content. The ratio of the major axis to the minor axis of the crystals was largest when the Nb₂O₅ content was 15?vol%. Furthermore, the grain-growth kinetics index (n), growth activation energy (Q), and growth mechanism of the columnar Al₂O₃ crystals were studied. The results indicated that the Nb₂O₅ addition could promote formation and growth of columnar Al₂O₃ crystals, and the grain-growth activation energy indicated that the dissolution process controls the crystal growth. The growth mechanism of the columnar Al₂O₃ crystals was also studied. The present work demonstrated that Nb₂O₅ is a good additive for the preparation of Nb₂O₅–7.5La₂O₃-Al₂O₃ composite ceramics with columnar Al₂O₃ crystals.     

溶液法合成的功能无机材料氧化镍对钙钛矿太阳能电池光电性能的影响

功能无机材料氧化镍 （NiO_x） 作为钙钛矿太阳能电池中最有前途的空穴传输材料之一，其有着高空穴迁移率、良好的稳定性、易于加工以及适合的费米能级等优点。但是，由于 NiO_x自身固有电导率低，Ni空位的电离能相当大，未掺杂的 NiO_x中空穴密度受到很大限制，加上孔洞的积累增加了载流子复合的可能，从而降低了有效的电荷收集。因此，优化 NiO_x薄膜的成膜质量是解决上述问题的关键。本文通过溶液法使用乙二醇甲醚（MEA）、乙醇（EA）和去离子水作为溶液，分别制备了 DME-NiO_x、EA-NiO_x 和 NCs-NiO_x 薄膜，并在浓度调节范围内对基于 NiO_x的钙钛矿器件进行优化，最终得到了光电转化效率 （PCE） 为 18.50%，开路电压 (V_oc) 为 1.034 V，短路电流 (J_sc) 为 22.94 mA/cm²，填充因子 （FF） 为 78% ...