压差控制器的稳定性分析和设计参数的研究

压差控制器是航空发动机燃油计量的重要部件,用于保持计量活门前后的压差恒定.为探究其控制压差能力的因素,研究了某型发动机加力系统中压差控制器的性能,分析并推导出其影响控压差能力的主要因素,并在AMESim仿真环境下对所得结果进行建模仿真,验证了所得结论的正确性.在此基础上对其进行合理的改型,为保证改型不影响系统稳定性,用小偏差原理对改型前后的压差控制器辨识,得到传递函数,确保改型并未损失其动态性能.最终得到改进压差控制器控压差能力的理论依据.     

负反馈放大器的简便分析方法

本文介绍了一种判断、分析负反馈放大器的简便方法。     

挠性飞行器的脉冲调制控制

三轴稳定控制是大挠性飞行器有效和重要的姿态控制方式，喷嘴控制是实现三轴稳定控制的手段之一。本文针对伪速率调制器（ＰＳＲＭ）和脉冲调宽调频调制器（ＰＷＰＦＭ），采用非线性脉冲调制器线性化和描述函数两种方法来分析大挠性航天飞行器的姿态稳定性问题，并对某型卫星的远地点点火姿态控制系统进行了分析和仿真。     

NONLINEAR PREDICTIVE CONTROL FOR TERRAIN FOLLOWING

ＮＯＮＬＩＮＥＡＲＰＲＥＤＩＣＴＩＶＥＣＯＮＴＲＯＬＦＯＲＴＥＲＲＡＩＮＦＯＬＬＯＷＩＮＧＣｕｉＨｕｔａｏ（崔祜涛），ＧｅｎｇＹｕｎｈａｉ（耿云海），ＹａｎｇＤｉ（杨涤）（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｐ．Ｏ．Ｂｏｘ１３７，...     

模糊数学在机械工程材料选择中的应用

介绍了模糊数学中的基本概念、隶属函数及模糊评判的基本理论，并首次提出将模糊数学的理论知识、分析方法与人工智能基本理论相结合，并借助于计算机完成机械工程材料的选择，从而使机械工程材料选择更为科学、更为简单。本文还对此方法进行了实例验证，其效果良好，设计者只需输入工作要求，便可以确定出欲选材料的优先次序。     

数字多用表自动校准/检定系统

简述数字多用表自动校准 检定系统的组成 ,多种功能和系统软硬件的设计特点 ,并以HP 3440 1A为例说明DMM的自动检定程序流程。详细介绍了作为标准的 570 0A校准器的特有性能 ,以及该系统可解决的实际工作问题     

Al—Si过共晶合金中初生硅溶解特性的实验研究

利用等温液淬及快速凝固技术研究了Ａｌ－１８．０８％Ｓｉ合金中初生硅在液态中的溶解行为。实验表明，合金液加热到１０００℃以下，保温２ｈ，初生硅仍未完全溶入液态合金。初生硅的溶解速率随时间延长而减小。快速凝固证实初生硅在液态合金中具有较高的化学稳定性。     

中继卫星复合控制系统设计

根据中继卫星系统多体控制的特点，合理地选择了中继卫星复合控制系统方案；然后根据所选择的方案，分别设计了中继卫星星体姿态稳定控制系统和单址天线指向控制系统，详细描述了天线指向控制概念，并且设计了星上自主控制方案；最后以不同的用户星作为跟踪目标，对所设计的复合控制系统进行了数学仿真。通过对仿真结果的分析，验证了该系统的有效性。     

三维修形对薄轮缘斜齿轮共振应力影响的实验研究

以８对具有不同辐板布置薄轮缘斜齿轮传动为对象，通过实验研究了三维修形对斜齿轮共振应力的影响。运用建立在有限元法、柔度矩阵和数学规划法基础上的三维修形方法获得了每对齿轮副的修形曲线。结果表明，采用三维修形技术将显著降低薄轮缘斜齿轮中的应力波动和振动水平，有利于延长齿轮传动的工作寿命。     

Unsteady aerodynamics and flow control for flapping wing flyers

The creation of micro air vehicles (MAVs) of the same general sizes and weight as natural fliers has spawned renewed interest in flapping wing flight. With a wingspan of approximately 15 cm and a flight speed of a few meters per second, MAVs experience the same low Reynolds number (10⁴–10⁵) flight conditions as their biological counterparts. In this flow regime, rigid fixed wings drop dramatically in aerodynamic performance while flexible flapping wings gain efficacy and are the preferred propulsion method for small natural fliers. Researchers have long realized that steady-state aerodynamics does not properly capture the physical phenomena or forces present in flapping flight at this scale. Hence, unsteady flow mechanisms must dominate this regime. Furthermore, due to the low flight speeds, any disturbance such as gusts or wind will dramatically change the aerodynamic conditions around the MAV. In response, a suitable feedback control system and actuation technology must be developed so that the wing can maintain its aerodynamic efficiency in this extremely dynamic situation; one where the unsteady separated flow field and wing structure are tightly coupled and interact nonlinearly. For instance, birds and bats control their flexible wings with muscle tissue to successfully deal with rapid changes in the flow environment. Drawing from their example, perhaps MAVs can use lightweight actuators in conjunction with adaptive feedback control to shape the wing and achieve active flow control. This article first reviews the scaling laws and unsteady flow regime constraining both biological and man-made fliers. Then a summary of vortex dominated unsteady aerodynamics follows. Next, aeroelastic coupling and its effect on lift and thrust are discussed. Afterwards, flow control strategies found in nature and devised by man to deal with separated flows are examined. Recent work is also presented in using microelectromechanical systems (MEMS) actuators and angular speed variation to achieve active flow control for MAVs. Finally, an explanation for aerodynamic gains seen in flexible versus rigid membrane wings, derived from an unsteady three-dimensional computational fluid dynamics model with an integrated distributed control algorithm, is presented.