Abstract: A method of generating randomness by public participation may comprise: communicating with the commodity devices to execute a protocol comprising a setup phase, a contribution phase and a result-generation phase, wherein: in the setup phase, parameters are initialized, a verifiable delay function is setup, and the parameters are published; the contribution phase is divided into at least one first stage, published parameters are provided, random values are received, and a Merkle tree root and Merkle tree audit paths are published in each of the first stage; and the result-generation phase is divided into at least one second stage of the same number as that of the first stage, each second stage is dedicated to one of the first stage ahead of the second stage for a period, and in each second stage, computation is performed to generate a result of randomness which is published.

Abstract: A method of generating randomness by public participation may comprise: communicating with the commodity devices to execute a protocol comprising a setup phase, a contribution phase and a result-generation phase, wherein: in the setup phase, parameters are initialized, a verifiable delay function is setup, and the parameters are published; the contribution phase is divided into at least one first stage, published parameters are provided, random values are received, and a Merkle tree root and Merkle tree audit paths are published in each of the first stage; and the result-generation phase is divided into at least one second stage of the same number as that of the first stage, each second stage is dedicated to one of the first stage ahead of the second stage for a period, and in each second stage, computation is performed to generate a result of randomness which is published.

Abstract: A mechanical operating arm device includes an arm attached to a tractor, a seat rotatably secured to one end of the arm, a pair of pawls each having one end pivotally secured to the seat, and a pair of actuators coupled between the seat and the pawls respectively for actuating the actuators to operate the pawls. The tractor may include a control stick for moving the arm and the pawls to the required working position, and a foot pedal for operating the pawls to grasp objects. Two bars may be attached to the pawls and each has a number of projections for objects holding purposes.