A method for detecting Special Nuclear Materials or Radiological dispersion Devices, comprising: conveying an object along a predetermined path; imaging a distribution of radioactive sources associated with the object as it passes along said path; determining the presence and location of one or both of an RDD or SNM radioactive source within the object. The system further includes a processing unit configured to determine dynamically the equalization coefficients of the filter without using a predetermined training pattern in the received data signal. A server and terminal share a hash function and an initial value determined for each terminal, calculate the same temporary ID by hashing the initial value the same number of times with the hash function, and identify the terminal using the calculated temporary ID. The dust mop andor cleaning device attracts the oppositely charged particles.