Abstract: A test tube rack (1) that is suited for storing and transporting test tubes. The test tube rack (1) according to the invention includes a bottom plate (3), a cover plate (2), and a centering plate (4), which are arranged parallel to one another and spaced apart from one another. The plates have a substantially rectangular shape. At each corner a screw connector (8) is arranged, through which the plates are joined to each other. The screw connectors (8) are designed such that, when stacking a plurality of test tube racks (1), the screw connectors (8) of one test tube rack (1) partially engage with the screw connectors (8) of another test tube rack (1), and thereby ensure a secure connection, at least with respect to lateral shifting. Additionally, the screw connectors (8) can be provided with a locking mechanism, which allows a rigid connection between test tube racks (1).

Abstract: A test tube rack (1) that is suited for storing and transporting test tubes. The test tube rack (1) according to the invention includes a bottom plate (3), a cover plate (2), and a centering plate (4), which are arranged parallel to one another and spaced apart from one another. The plates have a substantially rectangular shape. At each corner a screw connector (8) is arranged, through which the plates are joined to each other. The screw connectors (8) are designed such that, when stacking a plurality of test tube racks (1), the screw connectors (8) of one test tube rack (1) partially engage with the screw connectors (8) of another test tube rack (1), and thereby ensure a secure connection, at least with respect to lateral shifting. Additionally, the screw connectors (8) can be provided with a locking mechanism, which allows a rigid connection between test tube racks (1).

Abstract: Yarn sheet tension in a warp beaming operation is controlled by supplying a primary analog correcting signal to the drive of the warp beam based upon ultrasonic measurement of the progressively increasing effective beam diameter and by adding a supplementary proportional-plus-integral-plus-derivative (PID) correcting signal thereto based upon detected movements of a movable dancer roll biased into peripheral engagement with the yarn sheet as it is delivered to the warp beam.