Abstract: A machining device may include an electric motor, a blade rotatably driven by the electric motor for machining a workpiece, and a blade cover configured to surround the blade. A resonance sound reduction device may be disposed at the blade cover and may reduce air vibration generated by the rotation of the blade.

Abstract: A document print management system comprises a storage unit in which a print management table is maintained and a processor programmed to grant or deny a request to print an electronic document on any of a plurality of image forming devices that are connected over a network according to information recorded in the print management table, so as to control a total number of times each of the electronic documents identified in the print management table can be printed by a user authorized to print the electronic document.

Abstract: In a liquid pump, n sets of concavities are formed in an outer circumference of an impeller. In a case where an angle between an ith first line and an ith second line is a pitch angle ?i and an ith difference of adjacent pitch angles is ?i (?i=?i+1??i) (the i may be any integer of 1 to n), the pitch angles ?i may be inhomogeneous. For each of the pitch angles ?i, there may be one or more other pitch angle ?k (the k maybe any integer of 1 to n and other than i) being equal to the pitch angle ?i. Formulas 0.05???/(average of ?)?0.30 and 0.15?C??0.35 may be satisfied.