Abstract: An access control system stores two codes for each user that is authorized to access a resource, a primary code and a secondary code. When a user desiring access inputs the primary code to the system, the code is compared with the stored code for that user. If the primary code is valid, the user is allowed to access the resource. However, if the primary code is entered incorrectly, a count of the number of invalid attempts for that user is incremented, and if the count does not exceed a first threshold, the user can try again. When the number of invalid access attempts for the user exceeds the first threshold, the system requires the user to correctly input both the primary and secondary codes, before access to the resource is allowed. A second count is also maintained of the number of failed attempts in providing both codes. When the number of failed attempts exceeds a second threshold, the user is "locked out", i.

Abstract: A geometric vector quantizer coding technique is illustrated in the context of a full motion video coder based on a three-dimensional sub-band framework. The original image data is decomposed into different spatial-temporal frequency bands and based on the data in each, different quantization strategies are applied to the bands. The lowest spatial-temporal frequency band is coded using a traditional three-dimensional switched predictor and optimum scaler quantizer. The non-dominant sub-bands are coded using the vector quantization approach to efficiently encode the images while appropriately exploiting the sparse, highly structured nature of the data to design the codebooks. Variable resolution is achieved using these techniques and no training is needed to establish or maintain the codebook.