Abstract: To improve a communication system including two communication apparatuses so as to reduce a possibility of having communication decrypted by a third party. The communication system includes a first communication apparatus and a second communication apparatus, where one of the communication apparatuses encrypts transmission subject data and transmits generated encrypted data to the other communication apparatus which decrypts received encrypted data. Each of the communication apparatuses generates an algorithm used for encryption each time it performs the encryption or decryption. In this case, each of the communication apparatuses generates the algorithm by assigning past solutions to a solution generating algorithm capable of having the past solutions assigned thereto and thereby generating a new algorithm. The past solutions are erased when they are no longer used.

Abstract: Recuperation systems and methods are applied to vapor compression cycles in dehumidification, such as in air conditioning. In some embodiments, a method for dehumidification includes introducing a refrigerant from a heating unit to a cooling unit along a first path; introducing the refrigerant from the cooling unit to the heating unit along a second path different from the first path; introducing the refrigerant from the heating unit to the cooling unit along a third path different from the first path; and contacting the cooling unit and the heating unit with a first gas stream.