Novel moving-magnet electrodynamic feed units for small machine tools

Small feed motions in the mm and cm range today are mostly realised with miniaturised leadscrew motor systems, piezo stages and moving-coil actuators. A short survey on typical properties of those existing feed units for small machine tools is given first. A simple yet powerful complement or alternative to the above-mentioned small drives are single-phase linear direct drives with moving magnets. Especially motor designs with slotted stator winding offer high force densities and good dynamics. Combination of those short-stroke motors with ball or flexure guides and with embedded position or force control resp. leads to particular compact feed units. Such modules are currently being developed at Technische Universität Dresden for applications in future small machine tools and in automation. Two different prototypes of those feed modules are presented in this paper. With travel ranges of 11 and 14 mm, resp., peak forces of 39 and 112 N resp., linear force characteristics and speeds up to 1.6 m/s they feature attractive properties. A first module with ball-guided slide already contains an integrated low-cost position sensor and embedded state space position control. A second module with flexure-guided mover is currently being extended with latter embedded control components. Due to their high compactness, force density, dynamics and modularity, the developed feed units can widely be used in future small machine tools and in automation.     

一双鞋子造就的博物馆

<正>西雅图有一座从一双鞋子的疑问开始的博物馆.它就是"陆荣昌亚洲博物馆"。它诞生已超过40年,是全美惟一的一座亚美文化博物馆,也是西雅图鲜为人知的珍宝。它的成立是为了纪念美国西北岸第一位亚     

Positioning post-outpatient cardiac catheterization

The optimal positioning post-outpatient cardiac catheterization is a largely unexplored area of research. Traditionally, patients have been placed supine, with the head of the bed (HOB) flat. This study sought to explore the influence of three different post-procedure positions on the incidence of complications and patient perceptions of satisfaction. Sixty-nine patients were randomized into three groups immediately after hemostasis of the arterial puncture site was achieved. Group 1 patients were placed supine with the HOB flat. Group 2 patients were placed on their sides, with the affected extremity straight. Group 3 patients were placed on their backs, with the HOB at 15-30 degrees. Endpoints included the presence of any complication (bleeding, hematoma formation or expansion, back pain and urinary retention) and patient comfort and satisfaction with the randomized position. Patients were asked prior to discharge to select the position they would have preferred post-procedure. Selection of an alternative position was felt to indicate dissatisfaction with the randomized position. Ten patients in Group 1, and nine patients in Group 2 and Group 3 experienced a complication (X2 = 3.682, df = 1, p = 0.05). Eighty-five percent of Group 1 patients selected an alternative position vs. 24% of those patients in Group 2 and Group 3 (X2 = 27.6, df = 1, p < .001). Conclusion: varying patient position post-outpatient cardiac catheterization is at least as safe as the traditional supine position and is more comfortable for patients.