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61.
车载移动测量系统的发展促进了实景影像数据的广泛应用,但是数据标准和服务规范的缺失使异构的应用系统无法实现可量测实景影像数据和服务的共享,从而带来数据使用效率较低、互操作困难的问题,为解决这一问题,本文从充分分析实景影像数据的结构特征和功能特点出发,以Web服务体系为基础,结合OGC空间服务的相关规范,提出网络实景影像空间服务(Web Image Service,WIS),从接口设计、参数设计、交互过程、调用方式4个角度对WIS进行全面的研究,并对该服务模型进行原型实现和应用验证,探讨该服务模型在城市管理中的重要作用和意义. 相似文献
62.
Kang Du Yan-Bo Guo Fei Wang Jun Fan Xiao-Chuan Wang Wen-Zhong Lu Wen Lei 《Journal of the American Ceramic Society》2021,104(2):974-984
Ca1+2xSnSi2x+yO3+6x+2y (0.1 ≤ x ≤ 0.9; 0.1 ≤ y ≤ 0.9) microwave dielectric ceramics were prepared through traditional solid-state reaction sintered at 1450°C–1500°C for 5 hours. The Ca3SnSi2O9 second phase replaced the SnO2 second phase of the Ca1+2xSnSi2xO3+6x (x = 0, y = 0) ceramics by controlling the ratio of Ca:Sn:Si. The cracks of CaSnO3 (x = 0, y = 0) ceramic were inhibited, the microwave dielectric properties were optimized by introducing the Ca3SnSi2O9 second phase, and the CaSnO3-Ca3SnSi2O9 mixture system existed at (0.1 ≤ x ≤ 0.9, y = 0). The CaSnSiO5 phase with positive τf value was related to the Si-rich in CaSnSiyO3+2y (x = 0; 0.1 ≤ y ≤ 0.9), and the coexistence of three and four phases was obtained at CaSnSiyO3+2y (0.1 ≤ y ≤ 0.9) ceramics. The CaSnSiO5 phase appeared at CaSnSiyO3+2y (0.3 ≤ y ≤ 0.9) ceramics. The CaSnSiyO3+2y (y = 0.8) ceramic with 49.2 wt% CaSnSiO5 phase exhibited excellent microwave dielectric properties: εr = 11.06, Q × f = 57,500 GHz (at 11.5 GHz), and τf = +8.1 ppm/°C. 相似文献
63.
Xiao-Qiang Song Wen Lei Fei Wang Tao Chen Shi-Wo Ta Zhen-Xiao Fu Wen-Zhong Lu 《Journal of the American Ceramic Society》2021,104(4):1740-1749
A gillespite-structured MCuSi4O10 (M = Ba1-xSrx, Sr1-xCax) ceramics with tetrahedral structure (P4/ncc) were prepared by solid-state reaction method. X-ray diffraction and thermogravimetry with differential scanning calorimetry (TG-DSC) were employed to study the phase synthesis process of BaCuSi4O10. Pure BaCuSi4O10 phase was obtained at 1075°C and decomposed into BaSiO3, BaCuSi2O6, and SiO2 when calcined at 1200°C. The relationships between the crystal structure and microwave dielectric properties of MCuSi4O10 ceramics were revealed based on the Rietveld refinement and P-V-L complex chemical bond theory. The dielectric constant (εr) decreased linearly with decreasing total bond susceptibility and ionic polarizability. Quality factor (Q × f) was closely dependent on bond strength and lattice energy. The temperature coefficient of resonant frequency (τf) was controlled by the stability of [CuO4]6− plane in MCuSi4O10. Optimum microwave dielectric properties were obtained for SrCuSi4O10 when sintered at 1100°C for 3 hours with a εr of 5.59, a Q × f value of 82 252 GHz, and a τf of −41.34 ppm/°C. Thus, SrCuSi4O10 is a good candidate for millimeter-wave devices. 相似文献
64.
Jing Lv Longhai Guo Chunjie Xie Weitong Xu Jun Ye Xiaoyu Li Teng Qiu Xinlin Tuo 《应用聚合物科学杂志》2021,138(44):51316
Being a new kind of nanomaterials, aromatic polyamide nanofibers (ANF) have been much highlighted in recent studies. We here demonstrate an isopropyl alcohol (IPA) accelerated chemical cleavage on poly (p-phenylene terephthalamide) chopped fibers, which provides an efficient preparation method of ANF. The comprehensive study on the processes accelerated by different alcohols revealed that the preparation time of ANF in the mixed medium of dimethyl sulfoxide (DMSO)-alcohol (20:1 in volume) was shorten to 45 min and 75 min for methanol (ethanol) and isopropanol, respectively. However, the nanofibers prepared in DMSO-IPA exhibited the minimum in axial and radial dimensions, providing the finest and most uniform diameter of 16 nm. The corresponding ANF films through vacuum assisted filtration also showed the highest tensile strength of 150 MPa, in comparison with those of the ANF films prepared using other alcohols, which were about 110 MPa. Furthermore, ANF/silicon hybrid films were prepared by the ionic ring-opening reaction followed by the alkoxysilane condensation and nanoparticle fabrication. By changing the organo functional groups in the alkoxysilane, the surface of the films were adjustable in a wide contact angle range from 56° (hydrophilic) to 150° (superhydrophobic), suggesting the amendable interfacial properties potential applicable to composite fabrication with most of the resin matrix. 相似文献
65.
《Journal of the European Ceramic Society》2021,41(15):7783-7791
Two 3Gd-TZP materials were manufactured from powders produced by intense mixing and milling of unstabilized zirconia starting powders and gadolinia as stabilizer oxide by hot pressing at 1250 °C – 1400 °C. The materials show a combination of high toughness and moderate strength. In detail depending on starting powder the two TZP showed distinct differences concerning transformation characteristics, sintering temperature dependence of mechanical properties and the tendency to develop R-curve related deformation features such as non-linear stress strain curves and formation of transformation bands prior to fracture. 相似文献
66.
利用多台焊接电源同时对同一工件进行焊接,当外电压波动时,众焊接电源依靠自身控制系统进行各自调节的过程也是对外电网干扰的再生过程。将模糊理论与神经网络相结合,并应用于多焊接电源的群控。在分析和设计了状态变量的隶属度函数、推理规则、解模糊算法等基础上,完成了基于T—S(Tagaki—Sugeno)模型的自适应模糊神经推理控制器设计。利用该控制模型在Simulink搭建的焊接电源群控模型上进行仿真。结果表明,该控制模型具有调整时间短,超调量小的优点(与众焊接电源各自单独调节相比较,调整时间缩短了22%,超调量减小了40%),反映出良好的动态特性。 相似文献
67.
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69.
Qiang Shen Weizheng Yuan Xiaoping Li Jianbing Xie Honglong Chang 《Microsystem Technologies》2015,21(6):1157-1166
This paper proposes an orthogonal analysis method for decoupling the multiple nozzle geometrical parameters of microthrusters, thus an reconfigured design can be implemented to generate a proper thrust. In this method, the effects of various nozzle geometrical parameters, including throat width W t , half convergence angle θ in , half divergence angle θ out , exit-to-throat section ratio W e /W t and throat radius of the curvature R t /W t , on the performance of microthrusters are sorted by range analysis. Analysis results show that throat width seriously affects thrust because range value of 67.53 mN is extremely larger than the range value of other geometry parameters. For average specific impulse (ASI), the range value of exit-to-throat section ratio W e /W t and half divergence angle θ out are 4.82 s and 3.72 s, respectively. Half convergence angle with the range value of 0.39 s and throat radius with 0.32 s have less influence on ASI compared with exit-to-throat section ratio and half divergence angle. When increasing the half convergence angle from 10° to 40° and throat radius of the curvature from 3 to 9, average specific impulse initially decreases and then increases. A MEMS solid propellant thruster (MSPT) with the reconfigured geometrical parameters of nozzle is fabricated to verify the feasibility of the proposed method. The thrust of the microthruster can reach 25 mN. Power is estimated to be 0.84 W. This work provides design guideline to reasonably configure geometry parameters of microthruster. 相似文献
70.