A digital-to-analog converter with high linearity includes a switched capacitor amplifier removably coupled to a capacitor array. That is, a LVRB and a DVRB which are the units of a scheduling resource are defined and a resource allocation method and a method for transmitting resource allocation information using the same are disclosed. The virtual models andor the physical models may be used in the design and manufacture of copings or of prostheses. Through the disclosed use of a modified Domain Name Services, communication between wired and wireless nodes, moving or stationary, is supported and is transparent to the end-user. Such ring system as can be used for the intravaginal, intraperitoneal, and subcutaneous delivery of at least one bioactive agent, including those used as contraceptives, antimicrobial agents, andor antiviral agents, as well as those for the treatment of cancer.