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991.
李云志 《信息技术与标准化》2011,(8):71-74
对射频信号源的绝对电平和调谐射频电平的测量方法、测量仪器的配置选择、误差来源,以及测量不确定度等方面进行了综合分析和研究. 相似文献
992.
Crash sensing and its assessment play a pivotal role in autonomous vehicles for preventing fatal casualties. Existing crash sensors are severely bottlenecked by sluggish response time, rigid mechanical components, and space constraints. Miniaturized sensors embedded with custom‐tailored nanomaterials upholds potential to overcome these limitations. In this article, piezoelectric Zinc‐Oxide thin film as a crash sensing layer is integrated onto a flexible metal‐alloy cantilever. Material characterization studies are conducted to confirm piezoelectric property of sputtered ZnO film. The piezoelectric d 31 coefficient value of ZnO film was 7.2 pm V–1. The ZnO sensing element is firmly mounted on a scaled car model and used in a crash sensing experimental set‐up. A comprehensive theoretical analysis for two different real scenarios (nearly elastic and nearly inelastic collision) of crash events followed by experimental study is discussed. The crash sensor's output exhibits a linear relationship with magnitude of impact forces experienced at crash events. The response time of ZnO crash sensor is 18.2 ms, and it exhibits a sensitivity of 28.7 mV N–1. The developed crash sensor has potential to replace bulk material sensors owing to its faster response time, high sensitivity, and compactness as the demand for crash sensors in next‐generation automobile industries is progressively growing. 相似文献
993.
Tunc Sertel Nihan Akin Sonmez S. Sebnem Cetin Suleyman Ozcelik 《Ceramics International》2019,45(1):11-18
Influences of thermal annealing on structural, optical and morphological properties of the tantalum pentoxide (Ta2O5) thin films were investigated and anti-reflective performances were discussed in detail. The Ta2O5 thin films were deposited onto Corning Glass (CG), Si, GaAs and Ge substrates by radio-frequency (RF) magnetron sputtering technique using Ta2O5 ceramic target. The obtained secondary ion mass spectroscopy (SIMS) analysis results showed that uniform Ta and O distribution have formed throughout depth of the films deposited on substrates. The X-Ray diffraction (XRD) results indicated that the annealed Ta2O5 thin films at 100, 200, 300 and 500?°C have exhibited amorphous (a-Ta2O5) characteristic. The increased temperature has resulted in increasing the surface roughness from 0.67 to 1.60?nm. The optical transmittance of the annealed thin films has increased from 70.85 to 80.32% with increasing temperature. Spectroscopic ellipsometer (SE) measurement results demonstrated that the increased temperature has increased the refractive index of the Ta2O5 thin film from 2.11 to 2.18. The Ta2O5 thin film has reduced the average optical reflectivity of the Si, GaAs and Ge substrates by 78, 55 and 70%, respectively. In addition, thermal annealing process has decreased the optical reflectivity of the film. The obtained experimental results showed that single-layer Ta2O5 thin films can be used as anti-reflective layer in optical and optoelectronic applications. The best optical transmittance and anti-reflective performance were obtained at the annealing temperature of 500?°C. 相似文献
994.
基于射频开关通过互联的方式获得不同的逻辑组合,从而形成射频开关网络对网络分析仪的端口数量进行扩展,用以满足多种功能的测试需求。文章介绍的装置同时具有4端口全矩阵,4端口半矩阵的功能,且可以通过改变跳线连接来实现不同功能的测试。从而大幅度提高多端口射频器件(如多端口基站天线,多系统合路平台(POI),多频合路器等)生产测试效率、降低测试成本,也可应用于无线终端或基站的多端口射频测试。 相似文献
995.
Erik von HarbouSandra Parada Christoph GrossmannHans Hasse 《Chemical Engineering Research and Design》2011,89(8):1271-1280
Recently, novel equipment for heterogeneously catalysed reactive distillation, the D+R tray, has been introduced by Schmitt et al. (2009). The present work reports results of measurements of the separation capacity of D+R trays. Furthermore, results of reactive distillation experiments on two test systems are presented that show that the D+R tray can be used routinely for laboratory studies of heterogeneously catalysed reactive distillation. As test systems, the esterifications yielding butyl acetate and hexyl acetate were chosen. Reactive distillation using catalytic packings was studied previously in detail (
[Parada, 2008],
[Schmitt et al., 2004] and [Schmitt et al., 2005]) with the same test system. The experiments of the present work are carried out so that a direct comparison is possible. For both test systems, the most important process parameters such as feed rate and mass of catalyst were systematically varied. High conversions of the reactants and high purities of the products were achieved. The reproducibility of the results is excellent. The study shows that the D+R tray is a novel laboratory equipment that facilitates fast and flexible investigations of heterogeneously catalysed reactive distillation processes and that it can be used for studying process designs of columns equipped with either catalytic packings or trays. 相似文献
996.
997.
998.
通过射频磁控溅射法,在不锈钢金属托槽表面制备了不同厚度的TiO2-xNx薄膜。薄膜的晶体结构,表面形貌和表面粗糙度分别通过X射线衍射、扫描电子显微镜和2206型表面粗糙度测量仪分析。通过14FW往复摩擦磨损测试仪考察薄膜托槽体外摩擦性能。结果显示,所制备的纳米TiO2-xNx薄膜为锐钛矿型,结构均匀致密。不同厚度的TiO2-xNx薄膜托槽的动、静摩擦系数不论干燥或湿润条件下均小于对照组。在同一湿性环境下,随薄膜厚度增加TiO2-x Nx薄膜托槽摩擦系数呈递减趋势。TiO2-xNx薄膜托槽表现出了良好的低摩擦性能。 相似文献
999.
基于Impinj R2000芯片,设计一款四天线读写器核心模块,实现了四天线读写标签功能。核心读写器模块采用ARM7作为主控芯片,搭载RF1604DS芯片进行硬件设计。软件基于Impinj公司的R2000配套固件,设计了一款适用于四天线读写器模块的程序,可以实现四天线访问标签、四天线轮询访问标签功能,可以操作芯片内部寄存器,对模块的各个天线进行配置。经过现场测试与应用,结果表明,该程序能有效控制读写器完成四天线单独访问标签及四天线轮询访问标签的功能,实现了四天线读写器模块的功能。 相似文献
1000.
Paolo Della Vedova Mirolyuba Ilieva Vitaliy Zhurbenko Ramona Mateiu Adele Faralli Martin Dufva Ole Hansen 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(2):248-256
A novel molecular beacon (a nanomachine) is constructed that can be actuated by a radio frequency (RF) field. The nanomachine consists of the following elements arranged in molecular beacon configuration: a gold nanoparticle that acts both as quencher for fluorescence and a localized heat source; one reporter fluorochrome, and; a piece of DNA as a hinge and recognition sequence. When the nanomachines are irradiated with a 3 GHz RF field the fluorescence signal increases due to melting of the stem of the molecular beacon. A control experiment, performed using molecular beacons synthesized by substituting the gold nanoparticle by an organic quencher, shows no increase in fluorescence signal when exposed to the RF field. It may therefore be concluded that the increased fluorescence for the gold nanoparticle‐conjugated nanomachines is not due to bulk heating of the solution, but is caused by the presence of the gold nanoparticles and their interaction with the RF field; however, existing models for heating of gold nanoparticles in a RF field are unable to explain the experimental results. Due to the biocompatibility of the construct and RF treatment, the nanomachines may possibly be used inside living cells. In a separate experiment a substantial increase in the dielectric losses can be detected in a RF waveguide setup coupled to a microfluidic channel when gold nanoparticles are added to a low RF loss liquid. This work sheds some light on RF heating of gold nanoparticles, which is a subject of significant controversy in the literature. 相似文献