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基于小波变换的自适应多用户检测算法 总被引:1,自引:0,他引:1
在分析传统自适应多用户检测的基础上 ,提出了一种基于小波变换的自适应多用户检测算法。用小波变换进行前处理 ,然后再通过 LMS算法实现自适应多用户检测。与通常的自适应多用户检测算法相比 ,该算法利用了小波变换对小波空间进行了分解 ,信号经小波变换后自相关性会下降 ,收敛速度提高。同时在此分解过程中 ,根据信号与白噪声在不同尺度上的小波变换模极大值表现完全不同的特性进行信号的消噪。理论分析和仿真结果表明 ,该算法收敛速度较快 ,计算量增加较少 ,易于实时实现 ,而且具有良好性能。同时仿真实验表明 ,收敛速度与小波基选择有关 ,对于同一小波基系列 ,小波基的正则性越好收敛速度越快 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(7):1818-1830
Advanced space-borne thermal emission and reflection radiometer (ASTER) data were evaluated for the hydrothermal alteration mapping of the Nimu porphyry copper deposit, southern Tibet. According to the metallogenic model for porphyry copper, we chose hydrothermal alteration mineral association and then established a remote sensing model. Relative absorption-band depth (RBD) and simple band combination methods in visible near infrared (VNIR) and shortwave infrared (SWIR) bands were used to retrieve information about lithological distributions. Principal component analyses (PCA) were applied to extract the prospecting information based on the spectral information of argillization mineral association, propylitization mineral association, and iron stained (limonite) effects. Results of the study match up well with known copper occurrences and a circular structure in study area, while circular structures usually have close relationship with mineralization. Combined with field validation, ASTER data are proved able to characterise the alteration zone of these porphyry deposits. With VNIR and SWIR bands, argillic, propylitic and ferritization alterations in a single deposit can be effectively discriminated. 相似文献
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《中国航空学报》2021,34(10):20-35
Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion (DEP) aircraft, a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been developed and validated numerically. Variable-fidelity modelling for propeller aerodynamics has been used to achieve computational efficiency with reasonable accuracy. By optimizing the aerodynamic loading distributions on the tractor propeller disk, the induced slipstream is redistributed into a form that is beneficial for the wing downstream, based on which the propeller blade geometry is generated through a rapid inversed design procedure. As compared with the Minimum Induced Loss (MIL) propeller at a specified thrust level, significant improvements of both the lift-to-drag ratio of the wing and the propeller/wing integrated aerodynamic efficiency is achieved, which shows great promise to deliver aerodynamic benefits for the wing within the propeller slipstream without any additional devices. 相似文献
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S.P. Kuzin S.K. Tatevian S.G. Valeev V.A. Fashutdinova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
An accuracy of geocenter motion estimation is strongly dependent on the geodetic network size and stations distribution over the Earth’s surface. From this point of view DORIS system has an advantage, as its ground network of beacons consists of more than 50 sites, equally distributed over the Earth’s surface. Aiming to study variations of the geocenter movements, the results of DORIS data analysis for the time span 1993.0–2009.0 (inawd06.snx series), performed at the Analysis Centre of the Institute of astronomy of the Russian Academy of Sciences, have been used. DORIS data processing was made with GIPSY/OASIS II software, developed by Jet Propulsion Laboratory and modified for DORIS data processing by Institute Géographique National. Standard deviations of stations coordinates are estimated at the level 0.5–4.0 cm (internal consistency), depending on the number of satellites used in the solution. RMS of estimated components of the DORIS satellites orbits, compared with the solutions of other IDS analysis centres, do not exceed 1–2 cm. Weekly solutions for coordinates have been transformed from free network solutions (inawd06.snx series) to a well defined terrestrial reference frame ITRF2005 with the use of seven parameters of Helmert transformation, which were examined with a view to study variations of the geocenter movements (ina05wd01.geoc time series). In order to estimate linear trend, amplitudes, periods and phases of geocenter variation a method of linear regression was applied. The evaluated amplitudes of annual variations are of the order of 5–7 mm for X and Y components and 27–29 mm for Z component. Semi-annual amplitudes are also noticeable in all components (1–34 mm for X, Y and Z components). Secular trends in the DORIS geocenter coordinates are: −1.2, −0.1 and −0.3 mm/year for X, Y and Z directions respectively. 相似文献
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以国产碳纤维复合材料CCF300/QY8911含孔层合板静力拉伸试验为基础,建立了符合其损伤失效模式的有限元三维预测模型.通过引入Cohesive界面单元分析了层合板拉伸过程中的分层扩展,数值模拟的结果与试验结果吻合较好,破坏载荷预测结果与试验数据相比误差在5%以内.根据CCF300复合材料构件在制造过程和实际使用中产生的孔边分层缺陷的情况,在孔边预置分层,分析了初始分层损伤对于层合板剩余强度的影响.结果表明表面预制分层对剩余强度影响较小,但会引起自由边提前分层失效. 相似文献