船舶交流轴带发电机液压耦合研究

针对现有的轴带发电机的耦合方式不同程度地存在着当柴油机在变速运行时会产生供电频率不稳问题,提出船舶交流轴带发电机液压耦合方式,该耦合系统采用油马达转速作为控制信号控制变量泵的流量,从而使得主机在变速运行时轴带发电机供电频率稳定.     

Simulation on spread of fire smoke in the elevator shaft for a high-rise building

Spread of fire smoke in the elevator shaft of a high-rise building is influenced by many driving facts. We simulate smoke spreading in the elevator shaft, stair room, and pre-chamber with and without different supplied pressurized air. The simulation shows that smoke moves very fast in the elevator shaft. When a 12 floor high-rise building is in fire, smoke can fill up the elevator shaft in less than 1.5 min after a fire started, temperature in the elevator shaft can be higher than 187°C in 5 min, and the concentration of CO can also reach a high level. The elevator shaft has a very low visibility in less than about 100 s.     

Analytical estimation of the noise due to a rotating shaft

This article focuses on noise prediction of a rotating shaft. The governing equations of motion for a Rayleigh beam, rotating about its longitudinal axis and subjected to a harmonic force, are first established using the Hamilton’s principle and Galerkin’s method. Then, the vibrating displacement of the shaft is solved for. The aeroacoustic theory, introduced by Lighthill and improved by Ffowcs Williams and Hawkings, is used for calculating the developed noise of the shaft in motion. The dominant effect to the noise is the surface pressure on the moving shaft. Parametric studies also presented. From the numerical data, the noise value, from a rotating shaft, corresponding to the higher significant resonance is greater than that related to the first resonant mode. This phenomenon has not been found in the frequency response of the shaft’s displacement.     

基于FPGA的视频瞄准分划线的设计与实现

传统的雷达光电轴一致性标校方法,是以望远镜的光轴为基准进行的,该方法主要存在判读困难,适应性较差等缺点。鉴于这些不足,结合用户需求,设计实现了基于FPGA的视频瞄准分划线系统,结果表明以此为核心的雷达电视标校系统,不仅可以对雷达光电轴一致性进行标定,还能通过电视监控雷达周围的环境状况。     

Dynamic Response and Stability of a Rotating Asymmetric Shaft Mounted on a Flexible Base

This paper presents the dynamic response and stability of an asymmetric rotating shaft supported by a flexible base near the major critical speed and the secondary critical speed. In this system, the base is movable only in a direction transversal to the shaft. In the theoretical analysis, taking into account the effects of damping, the unstable vibrations near the major critical speed are mainly considered, and also the behavior of the forced oscillations near the major and secondary critical speeds is investigated. From the theoretical analysis, the unstable region is found to be divided into at most six subregions which depend on the mass of the base, the stiffness of the base, and the asymmetry of the shaft. In addition, the resonance curves near unstable subregions are calculated. It is found that there exist two shapes of resonance curves. In experiments, five types of response curves, which contained n unstable subregion (n = 1, 2, ¨, 5) near the major critical speed, were obtained by changing the mass of the base. It was ascertained that the theoretical results for the behavior near the major critical speed agreed quantitatively with the experimental results.     

二端面弹性转轴相对转动动力学模型研究

建立了二端面弹性转轴系统相对转动的非线性微分方程模型．对自治系统（二端面等力矩系统）进行了定量分析,证明了方程在一定条件下存在调和解,用数值方法,分析了系统的倍周期分岔现象．     

螺杆钻具传动轴接头表面裂纹断裂性能研究

以螺杆钻具的作业载荷为依据,对传动轴上端接头螺纹进行断裂性能研究。首先,通过强度分析,确定接头螺纹易发生断裂的危险位置;然后,考虑材料的弹塑性以及螺纹升角,建立螺纹根部含横向半椭圆表面裂纹的外螺纹接头和相啮合水帽的有限元模型,定量评价弹塑性和螺纹升角对接头断裂性能的影响。结果表明,材料塑性变形和螺纹升角对裂纹前缘J积分的影响较大,忽略这两个因素得到的结果偏于不安全。最后,利用所建立的弹塑性有限元模型,对于上扣预紧力单独作用以及上扣预紧力和工作扭矩共同作用的两种载荷条件,得到螺纹根部裂纹前缘的临界形状比及其对应的量纲为一的J积分随裂纹扩展的变化,为进一步研究螺杆钻具传动轴接头螺纹的疲劳寿命提供依据。     

分光计中望远镜的调节原理

探讨了分光计中对望远镜进行各步调节的原理,解释望远镜聚焦无穷远、望远镜光轴垂直于仪器转轴及分划板竖直准线平行于仪器转轴的调节原理,并建议在分划板竖直准线上平均划分出尽可能小的刻度,以便减少对光轴的调节次数。     

The Analysis of Seam Pressure Released Effect in Protection Layer Mining of Kilometer Deep Shaft

平顶山天安煤业股份有限公司十二矿己15-31010工作面垂深为1 015～1 130 m,为煤与瓦斯突出煤层,采用开采解放层己14煤层预抽瓦斯是解决己15煤层煤与瓦斯突出的关键技术,因此,针对深部保护层开采过程中下部煤层的卸压效果需进行深入分析。首先根据实际地质条件建立了三维数值模型,计算了己14煤开采过程中下部己15煤层的应力分布。计算结果显示,下部己15煤层在上部保护层开采过程中压力先升高后降低,在采面通过40 m后煤层压力降低至小于1 MPa;但在采空区外侧集中应力区,最大应力值高达42 MPa。现场监测数据显示,采空区下方煤层巷道瓦斯浓度显著增大,但外侧煤层巷道瓦斯浓度变化较小,在上方采面通过40 m后,巷道变形趋于稳定,煤层得到充分卸压。综合数值计算结果和现场监测数据可知,深部近距离保护层开采可以显著降低下部煤层压力,释放煤层瓦斯,但由于集中应力的影响,难以释放位于采空区边缘的下部煤层瓦斯。     

复杂螺旋回转体板式楔横轧应力分析

基于DEFORM-3D的有限元软件,模拟螺旋回转体的板式楔横轧成形过程,发现轧制单线螺纹回转体在横截面处只有1个变形区,纵截面有2个变形区.同时,揭示了轧件成形过程中起楔段和展宽段的应力分布及变化规律.