中心距误差对准端面圆弧齿轮敏感性分析

计算得到准端面双圆弧齿轮的基本齿形,并对比分析了准端面双圆弧齿轮中心距误差对压力角变化的影响和法面圆弧齿轮中心距误差对压力角变化的影响。     

Diversity Performance of Multimode Antennas in Directive Angle of Arrival Scenarios

The growing demand for wireless communications with increased spectral efficiency seeks for multi-element antenna techniques in personal communications to support high data rates by means of multiple-input multiple-output (MIMO) transmission schemes. Since the integration of multi-element antenna equipment at the mobile device needs to be well-aligned with the required form factors and aesthetical design issues, antenna array concepts with spatially decorrelated radiators are almost difficult to be implemented. Multimode antenna configurations operating with independent polarizations and different radiation patterns may substantially reduce size requirements since they do not necessarily require spatially separated phase centers. This article provides the theoretical framework for the analysis of the diversity efficiency of multimode antennas in directive angle-of-arrival scenarios. The analysis applies an idealized mathematical model of a multimode antenna based on the characterization of orthonormal, spherical harmonics. This mathematical foundation enables a detailed in-depth study of the impact of finite pattern correlation and branch power imbalances on the diversity efficiency of the multimode antenna. Based on the introduction of reliable performance metrics, the model enables a separate analysis of both effects. It serves as a guideline for the determination of the diversity efficiency when applying multimode antenna elements in mobile fading scenarios with defined angle-of-arrival scenarios.

Wireless sensor networks scheduling for full angle coverage

Many current studies in tracking and surveillance assume that a target can be monitored by a single sensor. However, there are situations where a sensor can only monitor a certain portion of the object. Examples include image capturing and coastline monitoring. In our previous work, we develop the Minimum Cost Cover algorithm to identify a set of sensors which preserve 360° coverage of a target with minimum cost, such that when different cost functions for the sensors are used, covers with different optimization objectives can be identified. In this work, we study the scheduling problem to monitor a target continuously with full angle coverage. To increase network lifetime, we develop several algorithms by adopting different cost functions in selecting the sensors. We evaluate the performance of our schemes through extensive simulations. The simulation results show that our proposed Conditional Scheduling metric can help to improve the network lifetime as well as the time to the first node failure.

一种大型设备多自由度自动对接方法

提出一种新颖的大型设备多自由度自动对接方法,该方法采用基于“三叉形”分划板的高精度CCD自准直仪来测量垂直与水平方向的二维小角度,采用单线阵CCD器件来测量轴向滚动、垂直、水平方向三自由度偏差,在嵌入式计算机的控制下通过测量这五个自由度偏差来调整设备姿态,直至对接完成。建立了五个自由度偏差的数据模型,并设计出包括CCD自准直仪、CCD接收处理装置、嵌入式计算机和执行机构的自动对接系统。该方法速度快、测量精度高,能实现大型设备的精确定位和自动对接,其角度测量精度为0.5″。     

优选精梳工艺参数的实践

为提高特细号精梳纱质量,通过对精梳落棉、给棉长度、锡林齿面圆心角及锡林速度等工艺参数的试验与优选,改进毛刷管理,正确使用自动减速装置,合理设定锡林清洁周期及时间,结果取得了较好的改进效果,CJ 5.8 tex品种精梳条及成纱质量得到较明显的改善。     

错位纺纱角变化对纱线质量的影响

为了研究错位纺纱角对纱线质量的影响,通过自制导纱装置,在前罗拉钳口至导纱钩之间形成一个偏移的纱路.分别采用5种左斜纺纱角对5种不同细度纱线进行了纺纱质量对比试验.结果表明:在Z捻左斜的情况下,纱线有害毛羽最多可以减少16.6%～40.5%,且与细号纱相比,粗号纱毛羽的改善更为显著;不同纱号的最佳左斜角不同,粗号纱和细号纱适应大角度偏移量(在8.4°～11°之间),而中号纱只要小角度偏移(4.2°)就能使纱线毛羽得到较好改善;但过大的偏移量(16.6°以上)对改善毛羽不利,甚至会恶化毛羽.错位纺纱角对纱线条干影响不大,对纱线强力几乎没有影响.指出:错位纺纱方式可以改善环锭纺成纱毛羽,其关键是要根据纺纱号数优选错位纺纱角.     

双曲柄机构的最佳传动角设计

在满足机构的杆长约束条件和使机构具有最佳传动角要求的前提下，探讨了双曲柄机构的尺寸可行区域，并分析了对传动最有利的双曲柄机构的设计方法。     

Q235-A钢管弯曲回弹角建模与分析

分析Q2 3 5—A钢管弯曲回弹过程 ,利用残余应力分布规律、静力矩平衡条件、变形协调条件等回弹理论推出回弹曲率和回弹角的计算公式 ,计算其回弹角并与实测值比较。比较结果表明 ,弯曲角度和弯曲半径与管子直径比值改变时 ,误差不同。在一定条件下 ,误差在 5 %以内     

“角度基准”中系统误差的修正杨进堂(中国科学院长春光学精密机械研究所

“圆光栅用于角度基准的研究”（角度基准）为国家提供了一台光、机、电、计算机相结合的仪器，它加工装调精细，又采用了许多高新技术，为高精度测角奠定了坚实基础。使用计算机误差修正技术，又进一步提高了仪器的测角精度。本文在分析了分度基准和细分器产生系统误差的根源之后，分别介绍了两种系统误差的测量与修正     

车齿机刀具扳角对渐开线蜗杆加工的影响

通过分析与实践,用同一种车齿刀采用刀具扳角的方法,加工不同螺旋角的蜗杆在实际生产中是不可取的。