直流电机网络控制系统仿真

对直流电机网络闭环控制系统进行仿真分析,根据电机网络闭环控制系统原理建立仿真模型。对具有数据丢包的直流电机网络伺服控制系统输出响应特性进行仿真,比较系统分别采用PI控制及增益,可调PI控制方式时的输出特性。结果表明,相比常规PI控制增益可调PI控制方法在网络环境下具有更好的控制特性。该研究为网络伺服控制技术提供可靠的参考依据。     

基于TC783A的三相电动机缺相保护电路的设计与实现

介绍用于三相电动机缺相保护装置的设计方法,采用集成芯片TC783A为核心元件实现,有效地解决三相电动机其他保护元件的局限性。具有快速切断控制回路电源的功能及缺相指示和相序指示,试验证明系统工作性能良好。     

The role of motor processes in mental rotation: selective shaping of cognitive processing via specific sensorimotor experience

The involvement of motor processes in mental rotation is experience-dependent: different levels of expertise in sensorimotor interactions lead to different strategies in mental rotation. In the present study, wrestlers, gymnasts, and nonathletes physically rotated objects that were either light (wooden) or heavy (lead) but otherwise having the same sizes and shapes. They then performed a mental rotation task using photographs of these objects in which the material and therefore the weight was visible. I hypothesized that wrestlers would rely more heavily on experience-based sensorimotor strategies in performing mental rotation because during their athletic practice they not only manipulate external “objects” (i.e., their opponent) but also have to plan future actions taking into account past experience of these “objects” (for example their weight). All participants reported that lead objects were harder to physically rotate than wooden ones. However, only wrestlers mentally rotated lead objects more slowly than wooden ones—as they would if they were physically rotating them—suggesting the involvement of motor processes. These findings show that the involvement of motor processes in mental rotation depends on specific rather than mere sensorimotor experience.     

Three-dimensional numerical analysis on combustion performance and flow of hybrid rocket motor with multi-segmented grain

This paper presents the combustion characteristics in hybrid rocket motors with multi-segmented grain through three-dimensional numerical simulations. Multi-segmented grain is composed of several thin grains with two or more ports. The numerical model consists of Navier-Stokes equations with turbulence, solid fuel pyrolysis, chemical reactions, a fluid–solid coupling model and a regression rate model. The simulations adopt 90% Hydrogen Peroxide (HP) and PolyEthylene (PE) as the propellant combination. The effects of the rotation, port number, fuel grain segment number and mid-chamber length on the flow field and combustion performances are analyzed. The results indicate that the multi-segmented grain configuration can strengthen the flow field, and the regression rate and combustion efficiency are enhanced. Take the cases with two grain segments and three ports for example, the regression rate is increased by 32.4%−45.1% and the combustion efficiency increases by 6%−8.6% in different rotation angles.     

低速大转矩永磁游标电机在发酵罐中的应用

采用秸秆生产丁醇时,为了达到高效率发酵,需要使发酵液中菌体分布均匀,所加物料需要及时搅拌。工业化生产丁醇的发酵罐尺寸较大,搅拌过程对驱动电机的输出转矩要求较高,因此高效率、小体积、低速大转矩的秸秆发酵搅拌电机对工业化发酵生产丁醇意义重大。设计了一种定转子永磁游标电机用于发酵液搅拌,并对电机的槽极数、电磁性能进行了具体的研究。制造样机并采用滞环控制实现了对液态发酵对象的快速响应,且实现了低能耗、高效率的发酵过程。     

水下超声速射流对上浮水雷受力特性影响研究

固体火箭发动机具有功率密度大、推力大等优势,常被用于上浮水雷的推进器。然而发动机在水下工作时燃气射流使流场压力发生剧烈脉动,进而影响发动机的推力性能及上浮水雷的受力特性。基于VOF多相流模型和理想气体模型,建立了上浮水雷在不同工作状态(欠膨胀、完全膨胀、过膨胀)下的数值模型,研究了水下燃气喷射流对上浮水雷的受力特性影响。结果显示,欠膨胀工况时,发动机推力平缓,大小为12.2KN,上浮水雷受力未出现负值;完全膨胀时,射流发生颈缩、胀鼓现象位置距离雷体较远,导致发动机推力及水雷壳体受力振荡不剧烈;过膨胀工况时,射流发生颈缩、胀鼓现象距离喷管较近,发动机推力发生剧烈脉动,产生21.37%的振荡幅度,胀鼓现象发生时,流场压力显著降低使得上浮水雷后体受力减小,壳体阻力增大,上浮水雷最大产生27KN的负推力。     

双脉冲固体火箭发动机隔舱打开与破片运动过程模拟

相比传统固体火箭发动机,具有能量管理特性的双脉冲固体火箭发动机结构更为复杂,为了提高其工作可靠性,针对核心部件金属隔舱的破片运动过程开展了数值仿真与试验研究。首先基于LS-DYNA软件,分析中引入监测函数、逻辑开关函数和加载驱动函数,模拟燃气流对破片的连续作用力,计算得到了在不同时刻破片的空间分布规律、撞击点位置及发动机内部损伤情况,保证了破片运动过程的高保真还原。其次,为了验证仿真结果的准确性,进行了模拟二脉冲初始工况的热流试验,发现破片撞击位置及损伤程度的仿真结果与试验数据一致性较高,其中撞击位置的预示误差小于9%,试验结果充分验证了有限元模型的准确性。由此,建立了适用于双脉冲固体火箭发动机金属隔舱破片运动过程的分析模型,实现了破片撞击位置及损伤程度的高精度预示。     

PE燃料热解过程对H2O2-PE固液发动机点火的影响

通过85%H2O2-PE固液火箭发动机中含有液体层的燃料热解模型,计算了PE燃料的热解过程,分析了燃料热解过程对点火时间的影响,计算结果和试验值一致。H2O2的流量对点火过程起决定性作用,当氧化剂流量低于最小点火流量时,发动机将无法点火。     

飞机高升力系统扭力管旋转角度测试方法

在飞机地面模拟试验环境下需要测试高升力系统襟翼扭力管旋转角度.由于扭力管属于系统试验件,在不改变试验环境构型的情况下不可截断或更换安装用于测试扭力管旋转角度的旋转编码器.本文利用同步轮法实现了在不破坏扭力管前提下安装旋转编码器测试扭力管旋转角度,方法简单、可靠,且容易实现,很好的满足了试验大纲要求.     

ZSGA?2型重力敏感器关键技术分析与试验验证

与国外主流海洋重力仪相比,国产海洋重力仪的分辨率低一个数量级,这制约了国产海洋重力仪的应用。针对国产海洋重力仪亟需提高分辨技术的需求,根据ZSGA-2型重力敏感器的工作原理,建立了弹性系统的力学模型,并开展了样机的静态性能测试。测试结果表明,经零位漂移和大地固体潮汐修正后的静态精度达到了0.03mGal,样机随重力仪进行楼层高差测量的重复性为0.15mGal。该型重力敏感器的分辨率已经达到了国外同类产品的技术水平,并具备了一定的动态适应性,为该型高分辨率零长弹簧重力敏感器开展高动态环境适应性技术研究奠定了坚实基础。