Motion compensation approach for wide-swath missile-borne SAR imagery

In wide-swath missile-borne synthetic aperture radar (SAR) imaging, the range-variant residual phase modulation, which is introduced by the presence of trajectory deviations, will seriously degrade the focusing quality of the final image. To deal with this problem, a motion compensation approach for missile-borne SAR is proposed. In the approach, the signal model of motion error for diving movement is established. Then, according to the inertial navigation system (INS) information, the range-variant residual Doppler rates of the echoes are extracted by using the Doppler rate estimation, on the basis of which the corresponding phase error can be calculated and compensated. Simulation results show that, by using the proposed approach, the influences of the motion error on focusing are greatly reduced with the well focused image obtained.     

Motion compensation approach for airborne bistatic SAR imaging

In airborne bistatic synthetic aperture radar (BiSAR) imaging, not only the motion error of the airborne platform, but also the inaccuracy of data acquisition geometry will introduce an additional phase error that seriously degrades the focusing quality of the final image. For one-stationary BiSAR imaging, the influence of the inaccurate geometry is analyzed in detail and an applicable motion compensation approach is proposed. By using Doppler rates estimation, the phase error both from the motion error and the inaccurate geometry is appropriately compensated so that the focusing quality of the final image is consequently improved. Analyses of acquired raw data are presented to verify the proposal.     

Heat treatment temperature effect on the microstructure and optical properties of Dy2(WO4)3 powders

Dy₂(WO₄)₃ powders were synthesized through liquid-phase reaction. The structure transformation of Dy₂(WO₄)₃ powders were analyzed by differential scanning calorimetry (DSC), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The optical absorption and photoluminescence properties were characterized by UV-vis-infra diffuse reflectance spectra and fluorescence spectra. The Dy₂(WO₄)₃ host could absorb deep UV light and transfer the energy of UV light to Dy³⁺ ions, which convert the high-energy UV light to blue light (482 nm, ⁴ F _9/2→⁶ H _15/2) and yellow light (547 nm, ⁴ F _9/2→⁶ H _13/2). The Dy₂(WO₄)₃ powders could also absorb near UV light and exhibit blue and yellow emissions near 482 and 547 nm, respectively. Heat treating promoted the crystallization and regulated the micro-structure of Dy₂(WO₄)₃ hosts. The bands of W-O_d anti-symmetric stretching vibration exhibited red shift with the increasing of sintering temperature. The W-O_b-W groups tended to combine with each other to form W-O_c-W groups after heat treating. These regulation of micro-structure had influence on the luminescent color of Dy₂(WO₄)₃. The samples could emit yellow-green, white-yellow and white light under the excitation of 350 nm after being treated at 600, 800 and 1 000 °C, respectively. The prepared Dy₂(WO₄)₃ powders have potential to act as UV absorber for solar cell to improve the conversion efficiency and also exhibit potential for white light LED.     

Time dependent chloride diffusion coefficient in concrete

In order to study how to correctly apply the two different time dependencies to service life prediction models, the definition of parameters in the time dependent equation using the long-term test method and the short-term test method, and its relationship were discussed. The experimental results show that, as the two time dependencies have different meanings, they have different manners when handled in service life prediction models. Time dependency of chloride diffusion coefficients in concrete was obtained by fitting experimental data. A large number of accurate experimental data were required to fit the formula of time dependency to ensure the accuracy of service life prediction model.     

Degradation mechanism of lacquered tinplate in energy drink by in-situ EIS and EN

The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages: organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.     

基于VFD显示触屏定时器的分析与设计

随着社会对家电产品期望值的提高,智能化成为家电产品发展的必然趋势．目前,智能家电已经能够实现家电附加值的提升．在阐述了电烤箱定时器设计性能指标,以及调研分析的基础上,提出了实现智能电烤箱控制的硬件电路设计方案,对智能电烤箱硬件电路的工作原理进行了分析,并对各个电路模块进行了介绍．同时,进行了定时器电路印制板的设计和指令汇编,实现了智能控制方案,对VFD显示触屏定时器通过调试验证,符合产品的实际工作性能要求．     

钛表面处理对增强钛/瓷结合强度的影响

为了提高钛/瓷结合强度,通过不同方法对钛表面进行处理,研究了钛表面处理后钛/瓷界面组织及结合强度。试验结果表明,烤瓷前进行钛表面喷砂处理,对增强钛/瓷结合强度的影响并不显著,但对抑制钛/瓷界面裂纹的扩展起到积极作用;钛表面预氧化处理能够在钛表面形成一层均匀的氧化膜,使参与界面反应的TiO2增多,反应层增厚,但预氧化温度对钛/瓷结合强度有重要影响;钛表面磁控溅射Zr中间层能够抑制钛表面生成过厚氧化层,而中间层厚度对钛/瓷结合强度也有较大影响。     

港口腹地结构研究——以宁波港为例

从港口腹地的定义和腹地理论出发,利用圈层结构方法和点轴结构法对宁波港腹地结构进行定性描述;定量分析各腹地区域及宁波经济本身对宁波港的贡献率,由此得出宁波港的发展重点应放在浙江省内,依次兼顾内层圈和外层圈,不能盲目拓展腹地的结论.     

计算机云备份技术的特征及可用性评估模型的建立

运用文献法和逻辑分析,对计算机云备份技术的特征及可用性评估模型的建立进行了详尽的分析,从可扩展性、可用性、效率和可靠性等方面论述了云备份技术的优势,提出云备份存储将满足未来出现的大量存储需求,而且以非常好的性价比实现这个目的。最后从吸引性、易学性、易用性以及交互性四个方面对云备份软件可用性评估模型进行了构建。     

锚杆锚固质量无损检测数据的处理方法研究

以声波法为基础的无损检测技术已经逐渐取代传统的拉拔实验成为锚杆锚固质量检测的主要手段。随着锚杆锚固技术在各类土木工程中的应用日益增加,锚杆锚固质量无损检测数据处理方法的研究工作也越来越受到重视。本文在分析锚杆锚固质量无损检测原理的基础上提出了以Hilbert变换为基础的数据处理方法,并将该方法应用于实际工程中,验证了其可行性。