单轴旋转惯导系统旋转性误差分析及补偿

对单轴旋转惯导系统因旋转而引入的各项误差进行分析,研究其误差特性及补偿方法。针对单轴正反连续旋转方案,在假定惯性测试组件的器件误差和其他非旋转性的误差在精确标定的情况下,推导了因旋转轴安装不正交引起的涡动、轴系间隙引起的晃动、测角器件误差、旋转控制引起的换向超调误差、角位置、角速度不准确等因素而引起的误差的表现形式,定性和定量地分析了各误差对于系统精度的影响。针对对系统影响显著的旋转轴不正交误差,提出了一种基于系统自身旋转轴正反旋转的误差标定及补偿方法并进行了仿真实验。在给定条件下的仿真结果表明,该方法能够准确标定出旋转轴的不正交误差,标定精度达到角秒级。     

爆炸荷载作用下地下拱形结构动力响应样条小波有限元研究

采用小波有限元方法研究爆炸荷载作用下地下结构的动力响应,克服在模拟过程中由于材料的奇异性、地质条件的复杂性和加载的快速性出现的应力集中和计算效率低下,根据样条有限点法,构造了单向和双向区间B样条圆环扇形小波单元,用尺度函数作为插值函数;结合工程实例,通过Matlab软件编程对爆炸荷载作用地下拱形结构的动力响应进行了数值模拟,并与应用传统有限元程序模拟结果进行对比。结果表明,小波有限元用很少单元取得了较高的精度,计算效率比传统有限元提高一倍。     

HL-2A托卡马克装置真空系统

介绍了HL 2A装置真空系统研制。它由真空主抽气系统、抽气偏滤器、直流辉光放电清洗系统组成。主抽气系统提供了装置真空室从大气到高真空、烘烤除气、直流辉光放电清洗所需要的抽气能力。抽气偏滤器初步实现了托卡马克放电过程中边缘粒子的抽运与控制;直流辉光放电清洗系统保证了装置良好的真空器壁条件。介绍了这些系统的初步运行情况,并给出了其测试结果。HL 2A装置首轮物理实验运行时真空室极限真空度达到4.6×10-6Pa,12h总漏放气率为1.8×10-5Pa·m3·s-1。     

谱有限元数值分析各向异性复合板中导波色散特性

提出谱有限元方法研究层状各向异性复合板中导波的色散特性和波结构。基于三维弹性动力学方程,用有限元方法离散波导截面,波传播方向的位移用简谐波表示,得到了导波色散的特征方程。分析了单层和双层复合板中导波沿不同方向传播的色散特性和波结构,讨论了双层复合板中层厚比对相速度的影响。数值研究结果表明:导波的对称模态沿纤维方向传播时在较宽的频率范围内保持弱色散状态。双层复合板中导波基本模态的相速度在低频时受层厚比的影响较明显,随着频率的增加趋向于相速度较低的材料。数值模拟结果为导波用于复合材料定量无损检测和性能评价提供理论依据。      

大分子不饱和单体法合成具有核壳结构的丙烯酸酯/聚氨酯乳液及表征

采用丙烯酸酯（AC）对水性聚氨酯（WPU）进行改性,合成了接枝型丙烯酸酯/聚氨酯(PUA)复合乳液。 随着共聚物中丙烯酸酯质量分数的增加,乳液外观由透明变为不透明,乳液粒径随之增大、分布变宽。 TEM显示,PUA乳胶粒子呈现清晰的核壳结构,且形态规整,粒径分布在60~120 nm之间。 FTIR测试表明,随着丙烯酸酯质量分数的增加,聚氨酯(PU)硬段氢键化作用先增强后减弱,硬段的有序度逐渐降低。 DSC分析表明,当AC的质量分数低于75%时,PU、聚丙烯酸酯(PA)两组分相容性较好,只出现一个玻璃化转变温度,并且随着PA质量分数的增加逐渐升高。 PA质量分数的增加,使胶膜的最大热失重速率从363 ℃提高至412 ℃,吸水率从11.3%降低至5.7%,弹性模量从16.4 MPa提高至47.6 MPa,拉伸强度从9.0 MPa提高至23.7 MPa,断裂伸长率从365%提高至408%,同时乳液的粘度下降,干燥时间变短,胶膜的附着力变好。     

不同热解活化条件下制备的污泥炭常温催化氧化NO

以市政污泥为原料制备污泥炭(SC),开展了SC常温催化氧化NO的实验研究.通过对不同热解温度(600 、700和800 ℃)和不同干基污泥(DS)/KOH混合质量比下(4:1、3:1、2:1和1:1)的NO脱除特性研究,探究了污泥裂解活化工艺对NO常温催化氧化的影响规律和作用机理.结果表明,热解温度和KOH活化均对SC...     

某抽水蓄能电站地下洞室围岩岩体质量特征分析

考虑材料的黏性效应建立了II型动态扩展裂纹尖端的力学模型,假设黏性 系数与塑性等效应变率的幂次成反比,通过分析使尖端场的弹、黏、塑性得到合理匹配,并 给出边界条件作为扩展裂纹定解的补充条件,对理想塑性材料中平面应变扩展裂纹尖端场进 行了弹黏塑性渐近分析,得到了不含间断的连续解,并讨论了II型裂纹数值解的性质随各参 数的变化规律. 分析表明应力和应变均具有幂奇异性,对于II型裂纹,裂尖场不含弹性卸载 区. 引入Airy应力函数,求得了II型准静态裂纹尖端场的控制方程,并进行了数值分析, 给出了裂纹尖端的应力应变场. 当裂纹扩展速度($M\to 0$)趋于零时,动态解趋 于准静态解,表明准静态解是动态解的特殊形式.     

Two-dimensional discrete mathematical model of tumor-induced angiogenesis

A 2D discrete mathematical model of a nine-point finite difference scheme is built to simulate tumor-induced angiogenesis. Nine motion directions of an individual endothelial cell and two parent vessels are extended in the present model. The process of tumor-induced angiogenesis is performed by coupling random motility, chemotaxis, and haptotaxis of endothelial cell in different mechanical environments inside and outside the tumor. The results show that nearly realistic tumor microvascular networks with neoplastic pathophysiological characteristics can be generated from the present model. Moreover, the theoretical capillary networks generated in numerical simulations of the discrete model may provide useful information for further clinical research.     

Analysis of thermal conductivity in tree-like branched networks

Asymmetric tree-like branched networks are explored by geometric algorithms. Based on the network, an analysis of the thermal conductivity is presented. The relationship between effective thermal conductivity and geometric structures is obtained by using the thermal-electrical analogy technique. In all studied cases, a clear behaviour is observed, where angle (δ ,θ ) among parent branching extended lines, branches and parameter of the geometric structures have stronger effects on the effective thermal conductivity. When the angle δ is fixed, the optical diameter ratio β^* is dependent on angle θ . Moreover, γ and m are not related to β ^* . The longer the branch is, the smaller the effective thermal conductivity will be. It is also found that when the angle θ < δ / 2, the higher the iteration m is, the lower the thermal conductivity will be and it tends to zero, otherwise, it is bigger than zero. When the diameter ratio β ₁< 0.707 and angle δ is bigger, the optimal k of the perfect ratio increases with the increase of the angle δ ; when β ₁> 0.707, the optimal k decreases. In addition, the effective thermal conductivity is always less than that of single channel material. The present results also show that the effective thermal conductivity of the asymmetric tree-like branched networks does not obey Murray's law.     

Accurate and rapid error estimation on global gravitational field from current GRACE and future GRACE Follow-On missions

Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser (K-band) ranging system, the orbital position and velocity of a global positioning system (GPS) receiver and non-conservative force of an accelerometer, is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach. Secondly, the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985× 10^-1~m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory (JPL), and the cumulative geoid height error is 5.825× 10^ - 2~m at degree 360 using GRACE Follow-On orbital altitude 250~km and inter-satellite range 50 km. The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward, and the dependability of the combined error model is validated. Finally, the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes.