空间三轴机抖激光陀螺交流稳频系统设计

针对空间三轴机抖激光陀螺设计了交流稳频控制系统,分析了系统原理,进行了Simulink仿真建模和试验研究。在系统原理中分析了控制过程,推导了系统函数,通过Simulink交流稳频系统仿真建模摸索了空间三轴机抖激光陀螺交流稳频系统中PID参数对系统响应的影响,并得到了优化参数(K_P=0.048,K_I=0.0021,K_D=0.0037),为硬件调试提供了参考。将交流稳频控制系统应用于国产某型空间三轴机抖激光陀螺进行试验,试验结果显示通过PID参数调节后的交流稳频陀螺PZT码值变化平稳,陀螺静态脉冲输出稳定,与原直流稳频控制方法相比将空间三轴机抖激光陀螺的精度提高了20%。     

基于框架优选的钻机底座结构动态设计研究

建立底座的三维有限元模型，通过对底座进行结构有限元动力分析，了解到底座的动态特征．在对底座进行有限元动力分析的基础上，研究了各个基本框架对底座的动力特性的影响规律．按照分析结果，可通过框架优选对钻机底座进行结构动态设计或动力修改，所提方法有一定的实用价值，可用于指导底座的结构动态设计或动力修改．     

旋转导向钻具组合力学分析

旋转导向系统代表了当今定向钻井的先进水平,是井眼轨道控制技术的发展方向. 为了解决旋转导向钻井轨道控制问题,进行了旋转导向钻具组合(rotary steering bottom hole assembly, RS-BHA) 力学分析. 应用纵横弯曲法建立了典型的柔性RS-BHA 三维力学分析模型,得到了钻头侧向力和导向参数间的相互关系,进而根据极限曲率法可预测旋转导向工具的造斜能力,并计算设计井眼轨道需要的导向参数. 通过力学分析,可以优化RS-BHA,了解井眼轨道控制规律,为旋转导向工具设计和定向钻井自动控制提供理论依据.     

Criticality of bifurcation in the tuned axial–torsional rotary drilling model

We study the bifurcation characteristics of a lumped-parameter model of rotary drilling with 1:1 internal resonance between the axial and the torsional modes which leads to the largest stability thresholds. For this special case, the two-degree-of-freedom model for the drill-string reduces to an effectively single-degree-of-freedom system facilitating further analysis. The regenerative effect of the cutting action due to the axial vibrations is incorporated through a delayed term in the cutting force with the delay depending on the torsional oscillations. This state dependency of the delay introduces nonlinearity in the current model. Steady drilling loses stability via a Hopf bifurcation, and the nature of the bifurcation is determined by an analytical study using the method of multiple scales. We find that both subcritical and supercritical Hopf bifurcations are present in this system depending on the choice of operating parameters. Hence, the nonlinearity due to the state-dependent delay term could both be stabilizing or destabilizing in nature, and the self-interruption nonlinearity is essential to capture the global behavior. Numerical bifurcation analysis of a global axial–torsional model of rotary drilling further confirms the analytical results from the method of multiple scales. Further exploration of the rotary drilling dynamics unravels more complex phenomena including grazing bifurcations and possibly chaotic solutions.     

激光陀螺数字直流稳频系统设计

从激光陀螺稳频原理出发，分析了交流稳频和直流稳频的异同。设计实现了激光陀螺数字直流稳频系统，分析了控制系统的稳定性和误差并做了数字算法实现。最后试验验证了该系统的稳频性能，得到了优于交流稳频的效果。     

Stability evaluation of an accurately controllable multiple injection system

Aiming to further improve diesel engine fuel efficiency and exhaust emissions, we conducted tests of a newly devised rapidly operating secondary actuator that provides controllable multiple injection. Up to six shots per cycle were implemented under high-pressure injection. A high-speed camera and a flow rate metering system were used to obtain quantitative data regarding diesel spray and fuel flow dynamics. The advantages of the applied technique are very stable phasing, dwelling, duration, and dosing of multiple injection shots proved from data analysis.Abbreviations ARB Arbitrary waveform generator - CRIS Common rail injection system - DC Direct current - ECU Electronic control unit - EDU Electronic injection driving unit - fps Frames per second - HP High-pressure - LDA Laser Doppler anemometer (velocimeter) - ROSA Rapidly operating secondary actuator - RPM Revolutions per minute - SOI Start of injection - TDC Top dead center - TTL Transistor–transistor logic     

Semi-active rotary damper for a heavy off-road wheeled vehicle

The development, simulation and laboratory testing of two-state discrete adjustable semi-active rotary dampers for heavy off-road wheeled vehicles, which is a joint venture between the South African based company Reumech Ermetek and Horstman Defence Systems from the UK, is described. A brief history of semi-active damping and rotary dampers is given, after which the working principle and features of combining the two technologies is outlined. Three dimensional simulation is used to determine the ride comfort gains achievable with semi-active rotary dampers compared to the conventional translational dampers currently used on the vehicle under consideration. Simulations are performed over different terrains, including the APG track and discrete obstacles. Semi-active rotary dampers were integrated on the 6×6 GV6 Self-propelled Gun Howitzer in order to quantify the improvements in ride comfort, transient response and handling of the vehicle as indicated by the simulation results. The control system, control strategies and characterisation tests, which includes determination of on and off characteristics as well as valve response times, are discussed.     

5-1/2 FH钻杆接头极限承载能力研究

随着超深井、定向井、水平井、大位移井及大斜度井在石油钻井工程中的广泛应用,由井下复杂工况引起的钻杆接头过早失效问题日益突出,导致钻井周期增长,成本增加,成为制约钻井工程效益的主要因素之一.近年来,不少学者对钻杆接头进行了大量研究,多数采用二维轴对称模型,少数采用三维力学模型,但并未同时考虑螺纹升角和井眼弯曲作用等因素的影响,而钻杆接头的极限承载能力研究更是鲜见报道.针对上述问题,基于虚功原理、von Mises屈服原则及接触非线性理论,同时考虑螺纹升角和井眼弯曲作用,建立了钻杆接头的三维数值仿真模型与井眼曲率到加载弯矩的转换模型,研究了钻杆接头的上扣特性、井眼曲率对连接强度和密封性能的影响,考虑预紧力、弯曲载荷及动载安全系数,计算了钻杆接头的极限工作拉力和极限工作扭矩.研究结果表明:上扣扭矩使钻杆接头产生一定的初始接触压力,保证钻杆接头井下作业过程中的连接强度与密封性能;井眼曲率对钻杆接头井下作业过程中的连接强度与密封性能影响极大,常见的某些工况会导致钻杆接头的连接强度和密封性能丧失,考虑服役时的随机振动与冲击,常规的超深井、水平井、定向井、大位移井及大斜度井弯曲段钻杆接头的设计和选型应着重考虑井眼曲率的影响;针对设计的每种钻杆接头,都应考虑常见的井眼曲率和轴向拉伸载荷进行极限工作拉力和极限工作扭矩的精细化数值计算,以确保其安全工作.     

半潜式钻井平台管道钢构支架极限强度研究

钢构支架是半潜式钻井平台管道支吊架的主要类型之一,钢构支架的极限强度是管道系统正常工作的重要保障。研究结构极限强度的方法有理论分析、有限元数值仿真和实验分析。在分析极限理论的基础上由静力法计算四种钢构支架试件的极限载荷;利用MSC软件对试件极限载荷进行数值仿真分析,并对有限元模型化技术进行讨论;对试件进行实验极限载荷测试,对比分析了三种方法测得的极限载荷。结果表明,三种分析方法计算得到结构的极限载荷基本一致,对于结构形式较为简单的结构通过理论分析可以得到简化解析解析解;数值仿真分析中采用合理的有限元模型化技术(结构有限元模型、边界、约束等)可得到精度较高的计算结果。     

基于动能定理的火炮炮闩系统冲击试验台设计

针对火炮射击条件下炮闩系统性能数据测量困难,提出将炮闩系统单独出来建立系统冲击试验台进行分析研究的思路。在确定了试验台设计原理的前提下,通过对自动开闩虚拟样机模型进行改进,建立了试验台原理模型。依据动能定理,确定了炮闩系统冲击试验台实现开闩所需的最小开闩力。在最小开闩力下,基于试验台原理模型分别对开闩板质量取初始值m、10m、50m、100m时进行模拟实验,结果表明:4种工况下皆未实现开闩,但随着开闩板质量的增加,外力做功损失的能量越小,曲柄转过角度越大,越容易实现开闩。研究结果可为试验台建立提供理论支撑。     

石油钻井旋转导向实验转台测试系统设计

设计了一种实验转台测试系统,主要用于在实验室环境下验证石油钻井旋转导向工具可行性并测试其性能参数。提出了总体方案,设计并完成了系统的关键组成部分：两轴手动转台、合力测试仪、惯性测量模块、信号处理系统,完成了计算参数和姿态误差角测试实验。实验结果表明,所设计的各部分工作正常,满足系统的总体要求。这为将来石油钻井导向工具的井下实验打下很好的基础。     

Application of piezoelectric actuation to regularize the chaotic response of an electrostatically actuated micro-beam

The impetus of this study is to investigate the nonlinear chaotic dynamics of a clamped–clamped micro-beam exposed to simultaneous electrostatic and piezoelectric actuation. The micro-beam is sandwiched with piezoelectric layers throughout its length. The combined DC and AC electrostatic actuation is imposed on the micro-beam through two upper and lower electrodes. The piezoelectric layers are actuated via a DC electric voltage applied in the direction of the height of the piezoelectric layers, which produces an axial force proportional to the applied DC voltage. The governing differential equation of the motion is derived using Hamiltonian principle and discretized to a nonlinear Duffing type ODE using Galerkin method. The governing ODE is numerically integrated to get the response of the system in terms of the governing parameters. The results show that the response of the system is greatly affected by the amounts of DC and AC electrostatic voltages applied to the upper and lower electrodes. The results show that the response of the system can be highly nonlinear and in some regions chaotic. Evaluating the K–S entropy of the system, based on several initial conditions given to the system, the chaotic response is distinguished from the periodic or quasiperiodic ones. The main objective is to passively control the chaotic response by applying an appropriate DC voltage to the piezoelectric layers.     

承重试验台同步加载系统设计计算及模糊PID耦合调平控制

针对试验台加载系统需具有高效率、快响应和高同步精度的特点,设计了一套液压油路系统,并开发了一种模糊PID交叉耦合同步调平四缸的控制算法。通过对理论模型输出位移的实时跟踪,实现了试验台的同步加载和精确调平控制。基于AMESim建立的同步加载系统的仿真结果,验证了主从式控制与模糊PID交叉耦合控制方案设计的合理性和可靠性。调平系统实验进一步表明,改变四液压油缸负载值使液压油缸负载不同步,可明显提高系统的高精度同步性能。     

氨燃料吸气式变循环发动机性能分析

针对飞行马赫数0 ~ 10的宽域飞行器对吸气式动力的需求, 提出了一种以氨为燃料和冷却剂的宽域吸气式变循环发动机, 其工作模态可有3种: 涡轮模态、预冷模态和冲压模态. 首先通过对该发动机各模态热力循环过程进行建模, 计算得到发动机比推力、比冲和总效率等性能参数, 初步验证其在马赫数0 ~ 10范围内工作的可行性; 然后, 选取甲烷和正癸烷为低温低密度和煤油类碳氢燃料的典型代表, 对比各模态下氨与碳氢燃料发动机的性能差异. 结果表明, 由于氨突出的当量总热沉和当量热值, 飞行马赫数3 ~ 5的预冷模态发动机性能各指标均优于碳氢燃料. 在涡轮模态和冲压模态下, 氨燃料发动机比冲较低, 但比推力和总效率优于碳氢燃料; 最后, 对比分析各类燃料马赫数0 ~ 10宽域工作特性, 发现氨预冷可以显著提升发动机比推力, 特别在高马赫数范围, 再生冷却通道内氨可发生裂解反应大量吸热并分解为氢气和氮气, 会进一步提升发动机比推力和比冲, 且不会堵塞冷却通道, 因此可胜任飞行马赫数0 ~ 10的宽范围飞行需求. 而煤油类碳氢燃料受限于比推力低和裂解结焦问题, 最高工作马赫数难以超过8. 本文提出的氨燃料吸气式变循环发动机, 当量冷却能力强且比推力高, 适合用于二级入轨飞行器的一级动力、高马赫数宽域吸气式飞行以及未来高超声速民航等场景.      

Injection characteristics simulation and analysis in diesel engines

By means of a purposely developed numerical code an investigation of injection systems in diesel engines has been carried out. Cavitation at low pressure was simulated. The experimental results obtained were compared with the numerical ones. Data on cavitation waves, in the pipe between pump and injector, were obtained during that simulation. In particular, the influence of the relief volume on cavitation volume and injected fuel rate were computed. Unstable working conditions, characterized by a large variation of the injected fuel, at the same operating point, have been experimentally investigated and simulated. Lecture delivered at the Workshop on Fluiddynamics, Combustion and Exposition in Reciprocating Engines, held at Capri in 1990.     

Suppression of chaos in a MEMS resonator by delayed position feedback

A delayed position feedback control is applied on DC voltage source for suppressing chaos of a typical MEMS resonator actuated by electrostatic forces. A theoretical necessary condition for chaotic oscillation of the controlled system is presented. Numerical results and the analytical prediction reveal the evolution of dynamical behavior of the system with AC voltage amplitude and the control effect of delayed feedback on reducing chaos of the system. It shows that the delayed feedback control is effective on suppressing chaos of the micro mechanical resonator.     

37mm冲压加速器试验和计算

气动中心超高速所自1995年正式开展冲压加速器研究以来,自行研制成功了国内第一座冲压加速器．给出冲压加速器这一新型超高速发射器的工作原理及国内外研究现状,然后介绍气动中心超高速所37mm冲压加速器系统组成、典型发射试验结果及有关的数值计算工作．     

Coupled axial-torsional dynamics in rotary drilling with state-dependent delay: stability and control

Nonlinear motions of a rotary drilling mechanism are considered, and a two degree-of-freedom model is developed to study the coupled axial-torsional dynamics of this system. In the model development, state-dependent time delay and nonlinearities that arise due to dry friction and loss of contact are considered. Stability analysis is carried out by using a semi-discretization scheme, and the results are presented in terms of stability volumes in the three-dimensional parameter space of spin speed, cutting depth, and a cutting coefficient. These stability volume plots can serve as a guide for choosing parameters for rotary drilling operations. A control strategy based on state and delayed-state feedback is presented with the goal of enlargening the stability region, and the effectiveness of this strategy to suppress stick-slip oscillations is illustrated.     

硅微谐振加速度计交流检测信号解耦技术

硅微谐振加速度计以高精度的频率信号输出及潜在的敏感结构与处理电路实现一次集成的优势,成为硅微传感器研制的热点之一。针对交流检测信号耦合效应对硅微谐振加速度计性能的重要影响,在分析硅微谐振加速度计工作机理的基础上,从结构和电路两方面研究了交流检测信号耦合效应的来源,分析了耦合效应对检测电路和闭环控制精度的影响。采用双质量块结构方案和电路优化设计所研制的硅微谐振加速度计,基频为15 kHz,标度因数为36 Hz/g,量程为±30 g。试验证明耦合效应对仪表性能的影响降低到0.3 mg以内。     

A comparative study of hybrid electric vehicle fuel consumption over diverse driving cycles

Environmental pollution and declining resources of fossil fuels in recent years, have increased demand for better fuel economy and less pollution for ground transportation. Among the alternative solutions provided by researchers in recent decades, hybrid electric vehicles consisted of an internal combustion engine and an electric motor have been considered as a promising solution in the short-term. In the present study, fuel economy characteristics of a parallel hybrid electric vehicle are investigated by using numerical simulation. The simulation methodology is based on a fast forward facing simulation model of a parallel hybrid and an internal combustion engine powertrains. The objective of this study is to present the main parameters which result in an optimum combination of hybrid powertrain components in order to obtain a better fuel economy of hybrid powertrains regarding different driven cycles and hybridization factors. Then, the fuel consumption of the parallel hybrid electric vehicles are compared considering various driven cycles and hybridization factors. The results showed that the better fuel economy of hybrid powertrains increases by decreasing average load of the test cycle and the point of the best fuel economy for a particular average load of the cycle moves towards higher hybridization factors when the average load of the test cycle is reduced.