Abstract: The present invention relates to an apparatus for defrostable ventilation systems which include an element for the transfer of heat from warm exhaust air (taken from inside a building) to cooler exterior fresh air which is drawn into the building, the system using warm interior air as defrost air for defrosting the system during cool weather. The present invention in particular provides an apparatus whereby, during a defrost cycle, the interior defrost air may circulate through both of the fresh air and exhaust air paths for delivery back into the building, i.e. the warm interior air may be confined to circulate from the interior of the building into the ventilation apparatus and back to the interior of the building. The apparatus can thus use interior air as defrost air while diminishing or avoiding the creation of a negative air pressure in the building.

Abstract: The invention consists in manually inserting a first piece of fabric (49) into the bottom portion of an edge guide comprising three superposed plates (2, 3, 4). The piece of fabric is pushed towards the end of the edge guide by means of jets of air until the side (51) of the piece along which sewing is to be performed is aligned with an end abutment. A dog (17) placed beneath the bottom plate (2) presses the piece of fabric (49) against the bottom face of the middle plate (3) and then displaces it along the sewing line direction until the other side (52) of the corner has reached a reference line (53). A second piece of fabric (54) is manually inserted and is positioned in the same way as the first by means of a dog (18) placed above the top plate (4). Once both of the pieces of fabric (49 and 54) are exactly superposed, the dogs (17, 18) drive them simultaneously at the same speed under the presser foot (47) of the sewing machine.

Abstract: The device for evaluating the efficiency of a ballplayer is provided with a target generator to control means whereby a visible target is rendered visible in a goal surface; the device further comprises means for measuring a parameter in relation with the speed of a ball going toward the goal surface and means for measuring the distance separating the target from the impact of the ball on the goal surface and computing means for determining the efficiency of the player in relation with the speed and position reached by the ball.