A dump body heater according to an embodiment of the present invention blows hot air into the dump body, heating the body and preventing material from freezing to the body in cold weather. At least one collimator arrangement comprises a lens system with a micro-lens array, and a light-waveguide holder firmly mounted to the micro-lens array with an intermediate space between the holder and the micro-lens array. The group key manager may periodically issue a new group key to be used in protecting communications among the network nodes. The spoke simultaneously contacts the hole and the connector to maintain the connector in the second lateral position. The bus bars are respectively inserted into the holding grooves, and are thus stacked in a radial direction of the centralized power distribution unit. A lack of substantial difference in the results is indicative that the ISV code adversely affects the host code while a difference between the results is indicative of an error in the modified code.