摆式陀螺经纬仪粗寻北的新方法

针对现有摆式陀螺经纬仪粗寻北方法存在的不足,提出利用检测陀螺力矩实现陀螺经纬仪粗寻北的新方法.推导了陀螺力矩对轴承的水平作用力与陀螺主轴方位角之间的数学公式,在地球自转角速度相对陀螺转子角速度非常小的情况下,对公式进行了简化和仿真运算.采用该方法改进了某型号陀螺经纬仪的粗寻北,实验表明在不影响陀螺经纬仪测量精度的前提下,简化了操作程序,缩短了测量时间.     

陀螺经纬仪光电积分法中几个关键问题的技术途径

陀螺经纬仪光电积分测量系统,在我国属首次研制,已获成功。本文论述了研制中光电检测器的线性度及电压稳定度、光强、陀螺马达的指向精度、悬带零位稳定性、系统温度漂移误差等几个关键问题的技术途径。实践证明,光电积分法测量,可以自动精密寻北;缩短了观测时间;增强了抗干扰能力,便于在野外和机动条件下使用。这种测量方法在陀螺经纬仪中具有普遍推广应用价值。     

纬度对陀螺经纬仪的影响测试分析

理论分析了纬度对陀螺经纬仪的影响规律,纬度越高陀螺指向力矩越小,陀螺仪跟踪周期和不跟踪周期越长,由此引起的陀螺经纬仪测量精度随纬度增高而趋势性变差。利用4台高精度陀螺经纬仪在纬度间隔约5°条件下进行了实地测试实验。结果表明,纬度从18°升高到53°,陀螺经纬仪测量精度变化约在3″左右,实验结果与理论分析结果一致。在考虑随机误差、仪器常数稳定性等其他因素影响的情况下,对中低精度的陀螺经纬仪影响可以接受,而对于高精度陀螺经纬仪不可忽视,可通过适当的测试数据拟合方式对纬度影响进行补偿。     

光电积分式陀螺经纬仪用于发射阵地定向误差分析

为实现导弹快速精确的发射,必须准确标定导弹发射阵地基准射向。陀螺经纬仪的使用可有效标定阵地射向,同时陀螺经纬仪系统误差又使阵地基准方向产生偏差。在确定各种系统误差的基础上,对陀螺经纬仪系统误差中的第一项进行了分析,推导出其后三项引起导弹发射阵地定向的方位误差模型,定量分析了其对导弹落点横向偏差的影响,并进行了仿真。仿真数据为不同射程导弹对系统误差的具体指标要求提供了依据,为下一步研究光电积分式陀螺经纬仪在导弹发射阵地快速、精确定向奠定一定的基础。     

TJ-707型陀螺经纬仪

ＴＪ－７０７型陀螺经纬仪陀螺经纬仪是一种不受外界限制，可以全天候独立测定真北的精密仪器。其定向原理是：一个用金属丝悬挂的且重力下移的陀螺灵敏部敏感地球自转角速度的水平分量，在重力作用下陀螺主轴绕地球子午面作往复摆动，其摆动方程近似为α＝αｍｓｉｎ２π...     

高精度陀螺经纬仪在阵地定向测量中的应用

战略武器的试验与发射是一项复杂精密的特殊工程，基准射向标定是该工程中的关键之一。基准射向的标定方法有多种，而采用Gyromat2000陀螺经纬仪是目前高精度阵地测量定向的最简捷方法。与传统定向方式相比较，高精度陀螺经纬仪的使用为发射阵地的射向标定提供了更为有效的测量和检核途径。在简述了Gyromat2000陀螺经纬仪在战略武器发射阵地的测量应用情况的同时，提出了对于该仪器测量前后仪器常数“e”的标定、测量成果F检核方式和仪器测量不确定度分析的内容，说明Gyromat2000陀螺经纬仪可以作为战略武器发射射向标定的高精度测量仪器，同时为该仪器的使用提供了重要而积极的作用。     

陀螺定向技术

本文主要阐述三个问题:①陀螺电机;②零位误差;③测量技术。陀螺经纬仪应选择什么样的电机最合适;零位误差是否一定要改正;众多的测量方法中运用哪一种有利;文中分别进行了分析比较。     

航天测量船静电陀螺监控器标定分析与应用

针对航天测量船标校经纬仪设备航向测量的局限性以及新装备的投入使用现状,分析了海上动态条件下静电陀螺监控器标定过程外界的影响因素,提出了静电陀螺监控器设备导航数据质量的分析方法.在此基础上,进行了试验数据的分析,通过与标校经纬仪测星计算的惯导航向误差比对,充分说明了该设备的良好性能,从而解决了测量船多云天气下标校经纬仪无法测星为惯导系统校准提供航向差的问题,实现了与标校经纬仪数据的互补,进而保障了航天测量船全天候海上测控的精度.     

气体介质对动力调谐陀螺仪性能的影响机理及调整措施

在动力调谐陀螺研制和生产过程中发现，陀螺从启动到稳定所需时间较长，在长时间随机漂移测试中，有明显的斜坡漂移。这在很大程度上降低了陀螺的性能，影响了陀螺的应用，经研究发现，陀螺的内部气体在这当中起着重要作用。本文详细分析了陀螺内部气体对动力调谐陀螺性能影响的机理，并提出了解决方法。     

无陀螺捷联惯性导航技术

无陀螺捷联惯性测量装置与传统捷联惯导系统的主要区别是角速度的获取方式不同,角速度的解算精度是无陀螺捷联惯性导航系统的核心问题,决定了系统的性能及实际应用的可行性。本文剖析了无陀螺捷联惯性测量装置的误差来源,建立了无陀螺捷联惯性导航系统角速度解算数学模型,并重点探讨了加速度计元件误差对角速度解算精度的影响。进行了无陀螺捷联惯性测量装置试验,结果表明,尽管计算误差较大,但无陀螺捷联惯性测量装置可以反映出运动平台的角运动规律,实际应用中对加速度计精度和计算机速度要求较高,另外应寻找更好的算法尽量补偿角速度解算误差。     

关于岩体结构力学基本观点探讨——试论孙广忠教授的岩体力学道路

本文着重探讨了孙广忠教授关于岩体结构力学的基本观点, 即岩体、岩体的结构与赋存环境, 岩体结构力学效应, 岩体结构控制论及工程地质-岩体力学-地质工程三位一体的观点等。纵观孙广忠教授的论著, 他走的一条“立足地质、以岩体结构力学效应为中心, 紧密结合地质工程”的岩体力学研究道路。     

Forced Oscillations of a System,Containing a Snap-Through Truss,Close to Its Equilibrium Position

The nonlinear dynamics of a two-degree-of-freedom mechanical system is considered. This system consists of a linear oscillator under the action of a time-periodic force and a snap-through truss, which acts as an absorber of the forced oscillations of the linear main system. The forced oscillations of the snap-through truss close to its equilibrium position are analyzed by the multiple scales method.     

An Improvement on Modeling of Forced Gravity Drainage in Dual Porosity Simulations Using a New Matrix-Fracture Transfer Function

In fractured oil reservoirs, the gravity drainage mechanism has great potentials to higher oil recovery in comparison with other mechanisms. Recently, the forced gravity drainage assisted by gas injection has also been considered; however, there are few comprehensive studies in the literature. Dual porosity model, the most common approach for simulation of fractured reservoirs, uses transfer function concept to represent the fluid exchange between matrix and its neighborhood fractures. This study compares the results of different available transfer functions with those of fine grid simulations when forced gravity drainage contributes to oil production from a single matrix block. These comparisons can lead to a more sophisticated formulation including the interplay of capillary, gravity and viscous forces. As a result, a new matrix-fracture transfer function can be developed and its results can be tested against the results of fine-grid simulations. Moreover, the reliability of this model for simulation of forced gravity drainage has been demonstrated by performing some sensitivity analysis.     

The effect of G?rtler instability on hypersonic boundary layer transition

The evolution of G?rtler vortices and its interaction with other instabilities are investigated in this paper.Both the Mack mode and the G?rtler mode exist in hypersonic boundary-layer flows over concave surfaces, and their interactions are crucially important in boundary layer transition. We carry out a direct numerical simulation to explore the interaction between the G?rtler and the oblique Mack mode.The results indicate that the interaction between the forced G?rtler mode and the oblique Mack mode promotes the onset of the transition. The forced oblique Mack mode is susceptible to nonlinear interaction.Because of the development of the G?rtler mode, the forced Mack mode and other harmonic modes are excited.     

常规螺杆泵定子有限元分析

螺杆泵定子橡胶不仅是易损构件，而且它与转子的配合状况对螺杆泵的工作性能影响显著。目前，还没有能够直接对实际工况下的定子橡胶的变形和受力状态进行测试的有效手段，因此对螺杆泵定子进行有限元分析自然是有益的尝试。重点研究定子橡胶衬垫内轮廓线的变形规律，而应力和应变分布情况仅作为辅助性的分析；对螺杆泵工况的考虑方面，重点研究均匀内压作用的情况，再考虑工作压差以及定子与转子的装配等所引起定子橡胶的变形和受力的变化。利用有限元分析软件Abaqus，对螺杆泵定子进行研究，得出了螺杆泵定子在不同工况下的受力状态和变形规律以及定子材料参数对变形规律的影响。利用此规律可对螺杆泵进行优化设计，提高其工作效率。     

Forced vibration and special effects of revolution shells in turning point range

The forced vibration in the turning point frequency range of a truncated revolution shell subject to a membrane drive or a bending drive at its small end or large end is studied by applying the uniformly valid solutions obtained in a previous paper. The vibration shows a strong coupling between the membrane and bending solutions: either the membrane drive or the bending drive causes motions of both the membrane type and bending type.Three interesting effects characteristic of the forced vibration emerge from the coupling nature:the non-bending effect,the inner-quiescent effect and the inner-membrane-motion-and-outer-bending-motion effect.These effects may have potential applications in engineering.     

Steady-State dynamics of a linear structure weakly coupled to an essentially nonlinear oscillator

We present a theoretical study of the dynamics of the coupled system of Jiang, McFarland, Bergman, and Vakakis. It comprises a harmonically excited linear subsystem weakly coupled to an essentially nonlinear oscillator. We explored the rich dynamics exhibited by this coupled system by determining its periodic responses and their bifurcations. Not surprisingly, we found a lot of interesting dynamics over a broad frequency range: cyclic-fold, Hopf, symmetry-breaking, and period-doubling bifurcations; phase-locked motions; regions with multiple coexisting solutions; hysteresis; and chaos. We did not find any occurrence of energy transfer via modulation (also known as zero-to-one internal resonance); theoretically, the possibility of its occurrence was ruled out for systems with weak nonlinearity and damping. Finally, we investigated the ef fectiveness of the so-called nonlinear energy sink (NES) in vibration attenuation of forced linear structures. We found that the NES results in an increase in the vibration amplitude of the linear subsystem, especially when the damping is low, contrary to the claim made by Jiang et al. Also, we did not find any indication of nonlinear energy pumping or localization of energy in the NES, away from the directly forced linear subsystem, indicating that the NES is not ef fective for controlling the vibrations of forced linear structures.     

General integral equations of thermoelasticity in micromechanics of composites with imperfectly bonded interfaces

One considers a linear thermoelastic composite medium, which consists of a homogeneous matrix containing a statistically inhomogeneous random set of heterogeneities with various interface effects and subjected to essentially inhomogeneous loading by the fields of the stresses, temperature, and body forces (e.g., for a centrifugal load). The general integral equations connecting the stress and strain fields in the point being considered and the surrounding points are obtained for the random and deterministic fields of inclusions. The method is based on a centering procedure of subtraction from both sides of a new initial integral equation their statistical averages obtained without any auxiliary assumptions such as the effective field hypothesis (EFH), which is implicitly exploited in the known centering methods. The new initial integral equation is presented in a general form of perturbations introduced by the heterogeneities and taking into account both the spring-layer model and coherent imperfect one. Some particular cases, asymptotic representations, and simplifications of proposed equations as well as a model example demonstrating the essence of two-step statistical average scheme are considered. General integral equations for the doubly and triply periodical structure composites are also obtained.     

Nonlinear Forced Vibration of Cantilevered Pipes Conveying Fluid

The nonlinear forced vibrations of a cantilevered pipe conveying fluid under base excitations are explored by means of the full nonlinear equation of motion, and the fourthorder Runge-Kutta integration algorithm is used as a numerical tool to solve the discretized equations. The self-excited vibration is briefly discussed first, focusing on the effect of flow velocity on the stability and post-flutter dynamical behavior of the pipe system with parameters close to those in previous experiments. Then, the nonlinear forced vibrations are examined using several concrete examples by means of frequency response diagrams and phase-plane plots. It shows that, at low flow velocity, the resonant amplitude near the first-mode natural frequency is larger than its counterpart near the second-mode natural frequency. The second-mode frequency response curve clearly displays a softening-type behavior with hysteresis phenomenon, while the first-mode frequency response curve almost maintains its neutrality. At moderate flow velocity,interestingly, the first-mode resonance response diminishes and the hysteresis phenomenon of the second-mode response disappears. At high flow velocity beyond the flutter threshold, the frequency response curve would exhibit a quenching-like behavior. When the excitation frequency is increased through the quenching point, the response of the pipe may shift from quasiperiodic to periodic. The results obtained in the present, work highlight the dramatic influence of internal fluid flow on the nonlinear forced vibrations of slender pipes.     

Nonstationary one-dimensional gas flows in channels in the presence of periodic perturbations of the boundary conditions

A study is made of the propagation in channels of forced oscillations generated by harmonic variation of the boundary conditions at the entrance and exit sections. Linear theory is used to find classes of boundary conditions and frequencies of the forced oscillations corresponding to the greatest gain or attenuation of high-frequency oscillations in a channel of variable section and of oscillations of arbitrary frequency in a channel of constant section. The resonance phenomenon that arises in channels when the frequencies of the forced oscillations and the fundamental oscillations are equal is studied. The wave process in a channel of variable section is investigated numerically, its characteristics found, and a comparison made with the linear theory. It is shown that the results of the calculations and the data of the linear analysis agree well.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 127–135, September–October, 1980.We thank A. B. Vatazhin for helpful discussions.