检索结果-南通市图书馆

基于正则化与恒星日滤波的BDS多路径误差削减方法

在线全文

学校读者我要写书评

暂无评论

大地测量与地球动力学 2024年第2期44卷 116-121页

作者：李新忠熊永良徐韶光西南交通大学地球科学与环境工程学院成都611756

在重构的载波相位单差残差基础上,利用分段思想估计北斗卫星的多路径重复时间,分别采用正则化方法和经典小波滤波方法提取载波相位单差残差的多路径信号,得到“干净”的单差残差序列。实验结果表明,利用Tikhonov正则化方法正确提取多路... 详细信息

在重构的载波相位单差残差基础上,利用分段思想估计北斗卫星的多路径重复时间,分别采用正则化方法和经典小波滤波方法提取载波相位单差残差的多路径信号,得到“干净”的单差残差序列。实验结果表明,利用Tikhonov正则化方法正确提取多路径信号是可行的,多路径信号比原始测量残差更具平滑性,并进一步优化了正则化参数的估计方法。利用优化后的Tikhonov正则化方法与恒星日滤波后,载波相位单差残差平均改进40.5%;坐标残差E、N、U方向分别改进24.8%、26.3%和42.7%。无论是观测值域还是坐标域,优化后的Tikhonov正则化方法较传统的小波滤波方法更具优越性。

关键词： BDS Tikhonov正则化恒星日滤波多路径误差

GNSS模糊度搜索空间的相关性分析与优化策略

在线全文

学校读者我要写书评

暂无评论

大地测量与地球动力学 2024年第7期44卷 667-673页

作者：李新忠熊永良徐韶光西南交通大学地球科学与工程学院成都市611756

初始搜索空间设置是否合理,会直接影响模糊度解算的可靠性和搜索效率。针对BDS系统星座特性,有必要对BDS2和BDS3在不同卫星数、不同频率下椭球容积与候选点个数的相关性以及数据冗余的影响进行分析。对于目标函数方法在确定模糊度搜索... 详细信息

初始搜索空间设置是否合理,会直接影响模糊度解算的可靠性和搜索效率。针对BDS系统星座特性,有必要对BDS2和BDS3在不同卫星数、不同频率下椭球容积与候选点个数的相关性以及数据冗余的影响进行分析。对于目标函数方法在确定模糊度搜索空间时容易产生过多的模糊度候选向量这一缺点,提出一种优化的搜索空间确定方法,并通过实验验证改进方法的有效性。结果表明,改进的搜索空间确定方法可明显减少实际模糊度候选向量个数,平均改进率最大可达35.02%,且保证94%的空间内所包含的候选向量个数符合要求。改进的搜索空间确定方法应用于不同搜索方法后搜索效率平均提升近33%,有利于分离出初始搜索空间中的冗余候选向量,从而提高模糊度搜索效率。

关键词： GNSS 整数最小二乘搜索空间椭球容积目标函数

Nutation instability of spinning solid rocket motor spacecraft

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第4期30卷 1363-1372页

作者： Dan YANG yongliang xiong Qian REN Xianyong WANG School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Wuhan 430074 China Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Luoyu Road 1037 Wuhan 430074 China

The variation of mass, and moment of inertia of a spin-stabilized spacecraft leads to concern about the nutation instability. Here a careful analysis on the nutation instability is performed on a spacecraft propelled by solid rocket booster（SRB）. The influences of specific solid propellant designs on transversal angular velocity are discussed. The results show that the typical SRB of End Burn suppresses the non-principal axial angular velocity. On the contrary, the frequently used SRB of Radial Burn could amplify the transversal angular velocity. The nutation instability caused by a design of Radial Burn could be remedied by the addition of End Burn at the same time based on the study of the combination design of both End Burn and Radial *** analysis of the results proposes the design conception of how to control the nutation *** method is suitable to resolve the nutation instability of solid rocket motor with complex propellant patterns.

关键词： Attitude control Nutation dampers Payloads Solid rocket booster Spin stabilization of spacecraft

Combining field-modulating electroosmotic vortex and insulating post to manipulate particles based on dielectrophoresis

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2021年第3期42卷 371-386页

作者： Bing YAN Bo CHEN Fanyun LIU Jiankang WU yongliang xiong School of Civil Engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China

The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate *** way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous ***,the thickness of the modulating electrode is *** practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles *** this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to *** results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating ***,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing ***,the range of regulating channel flux to achieve the optimal separation is ***,the separation efficiency improves since the perfect separation can be achieved at a higher flow ***,the effects of the location and the size of the insulating post on particle separation are analyzed in *** present work could provide the reference for the application of the DEP technology.

关键词： electroosmotic vortex dielectrophoresis(DEP) insulating post particle separation

Effect of Joule heating on the electroosmotic microvortex and dielectrophoretic particle separation controlled by local electric field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第11期30卷 401-410页

作者： Bing Yan Bo Chen yongliang xiong Zerui Peng School of Aerospace Engineering Huazhong University of Science and TechnologyWuhan 430074China

Dielectrophoresis(DEP)technology has become important application of microfluidic technology to manipulate *** using a local modulating electric field to control the combination of electroosmotic microvortices and DEP,our group proposed a device using a direct current(DC)electric field to achieve continuous particle *** this paper,the influence of the Joule heating effect on the continuous separation of particles is *** show that the Joule heating effect is caused by the local electric field,and the Joule heating effect caused by adjusting the modulating voltage is more significant than that by driving ***,a non-uniform temperature distribution exists in the channel due to the Joule heating effect,and the temperature is the highest at the midpoint of the modulating *** channel flux can be enhanced,and the enhancement of both the channel flux and temperature is more obvious for a stronger Joule heating *** addition,the ability of the vortices to trap particles is enhanced since a larger DEP force is exerted on the particles with the Joule heating effect;and the ability of the vortex to capture particles is stronger with a stronger Joule heating *** separation efficiency can also be increased because perfect separation is achieved at a higher channel *** optimization of the separation device,such as the convective heat transfer coefficient of the channel wall,the length of modulating electrode,and the width of the channel,is performed.

关键词： dielectrophoresis microvortices Joule heating effect particle separation

On the Transient Numerical Simulation of Solid Rocket Motor by Coupling Quasi One⁃Dimension Internal Flow with Three⁃Dimension Propellant Grain Burnback

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2021年第5期28卷 15-27页

作者： Juan Duan yongliang xiong Ningdong Hu Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Wuhan 430074China

The quasi one⁃dimension compressible flowfield coupled to the three⁃dimension propellant grain regression solved by the level⁃set method was used to simulate the transient internal ballistics of solid rocket ***⁃dimension flowfield instead of three⁃dimension can save computational cost on the premise of calculation accuracy because the radial and azimuthal variations parameters have little contribution to the internal *** grain regression in real⁃time could provide accurate geometrical information for simulation.A combination of flowfluid solver and grain regression can reappear in a relatively real internal ballistic flowfield,so it is good for further studying the instability of solid rocket *** level⁃set equations,the total variation⁃diminishing second⁃order Runge⁃Kutta method for temporal derivatives and a fifth⁃order weighted⁃essentially⁃non⁃oscillatory scheme for spatial derivatives were *** total variation⁃diminishing MacCormack method was used to discrete the Euler equations in flowfield *** modules of this code were tested in this study:one is the burning rate module and the other is the nozzle erosion *** show that the burning rate influenced the solid rocket motor efficiency,and the velocity profile in the chamber was affected by the nozzle shape,and the nozzle erosion could influence the head⁃end pressure spike.

关键词： transient compressible solver internal ballistics simulation level⁃set method solid rocket motor

在线全文

学校读者我要写书评

暂无评论

不同头型回转体高速入水运动过程对比研究

水下无人系统学报 2024年第3期32卷 451-462页

作者：王余熊永亮田轩麾周福昌刘翱孙国仓华中科技大学航空航天学院湖北武汉430074 中国运载火箭技术研究院北京100076 中国船舶集团有限公司第七一九研究所湖北武汉430064

跨介质回转体高速入水是一个瞬态流动过程,涉及到回转体与气相和液相的复杂多相流动。文中基于雷诺时均方程,并考虑自然空化现象的多相流模型,建立了入水空泡动力学数值模型,并研究了不同头型回转体垂直入水过程运动特性和流体动力的影... 详细信息

跨介质回转体高速入水是一个瞬态流动过程,涉及到回转体与气相和液相的复杂多相流动。文中基于雷诺时均方程,并考虑自然空化现象的多相流模型,建立了入水空泡动力学数值模型,并研究了不同头型回转体垂直入水过程运动特性和流体动力的影响规律。通过数值仿真结果与相关文献试验结果对比,验证了模型和数值方法的有效性。结果表明,不同头型回转体入水后的空泡特征与运动速度规律有很大的差异,相应瞬态阻力系数也表现出很大差异;在空泡闭合前,体现出明显的回射流效应,并影响空泡形态与回转体阻力的变化;回转体的入水速度对空泡尺寸和冲击载荷具有非常直接的影响,入水速度较低时回转体速度衰减相对更快,阻力系数相对更大。

关键词：跨介质回转体入水空泡多相流

一种融合轨检信息的GNSS动态单历元多路径误差提取方法

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

武汉大学学报（信息科学版） 2021年第6期46卷 905-912页

作者：张芮熊永良雷飞西南交通大学地球科学与环境工程学院四川成都611756 中国电子科技集团公司第十研究所四川成都610036

随着中国高铁的发展,全球导航定位系统(global navigation satellite system,GNSS)动态定位技术在列车定位及轨道检测中具有广阔的应用前景,但其精度目前难以满足轨道检测要求。多路径效应是影响GNSS动态定位精度的一个主要误差源,目前... 详细信息

随着中国高铁的发展,全球导航定位系统(global navigation satellite system,GNSS)动态定位技术在列车定位及轨道检测中具有广阔的应用前景,但其精度目前难以满足轨道检测要求。多路径效应是影响GNSS动态定位精度的一个主要误差源,目前已有的多路径误差削弱方法大多适用于静态测量环境,尚无有效的方法削弱动态多路径误差。分别采用传统算法和以轨检几何信息作为约束条件的算法解算GNSS观测数据,并将受到多路径影响的测量结果与轨检信息进行对比分析,同时利用小波多尺度分解算法分离坐标残差序列中的多路径误差和噪声,得到"干净"的轨道坐标序列。实验结果表明,由于信息量增加,融合轨检信息的GNSS数据解算方法可以有效提取多路径误差和观测噪声;利用小波相关分析能进一步削弱坐标域中的多路径误差,提高GNSS动态定位的精度,满足高铁轨道测量的需求。

关键词：轨检信息 GNSS动态定位多路径误差坐标域小波

低温热液成矿作用中铊有机络合物搬运形式的研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

矿床地质 2010年第1期29卷 177-181页

作者：熊永良 Sandia National Laboratories 4100 National Parks Highway Carlsbad New Mexico 88220 USA

文章依据等库伦反应外推原理,计算了铊的醋酸(TlAc0)、柠檬酸(TlCit2-)、苹果酸(TlMal-)、草酸(TlOx-)及琥珀酸(TlSuc-)络合物在25～100℃之间的稳定常数。将这些稳定常数输入EQ3/6的***热力学数据库后,在75℃和100℃温度条件下,对铊的... 详细信息

文章依据等库伦反应外推原理,计算了铊的醋酸(TlAc0)、柠檬酸(TlCit2-)、苹果酸(TlMal-)、草酸(TlOx-)及琥珀酸(TlSuc-)络合物在25～100℃之间的稳定常数。将这些稳定常数输入EQ3/6的***热力学数据库后,在75℃和100℃温度条件下,对铊的诸物种于低温热液中在不同pH值条件下的分配进行了计算。计算表明,在中性及偏碱性条件下,在75℃还原环境中,自由铊离子(Tl+)所占比例约为55%,TlHS0约占10%,而其余则为铊的有机络合物,并以铊的柠檬酸络合物占绝对优势。在75℃氧化环境中,自由铊离子约占55%,而铊的有机络合物则为45%左右。在100℃还原环境中,自由铊离子所占比例约为20%,TlHS0约占20%,其余则为铊的有机络合物。在100℃氧化环境中,自由铊离子所占比例约为30%,其余则为铊的有机络合物。因而笔者认为,铊的有机络合物,尤其是铊的柠檬酸络合物,在低温热液中对于铊的溶解及搬运起着重要的作用。

关键词：地球化学铊矿床络合物稳定常数 SIT模式等库伦反应外推原理有机物质