This paper discusses the problem of reducing the number of keys required to authenticate a source state (plaintext), as well as introducing a new way of constructing authentication codes. The construction uses association schemes, which are well-defined schemes in combinatorial design theory. The association scheme on the message (ciphertext) space is established by defining two relations between any two messages: The 1st relation is when the two messages do not share a common key, and the 2nd relation is when they do. Using association schemes of the triangular and group divisible types, we are able to reduce the number of keys.

A network system is proposed for segmenting and extracting multiple moving objects in 2D images. The system uses an interconnected neural network in which grouping factors, such as edge proximity, smoothness of edge orientatio, and smoothness of velocity perpendicular to an edge, are embedded. The system groups edges so that the network energy may be minimized, i.e. edges may be organized into perceptually plausible configuration. Experimantal results are provided to indicate the performance and noise robustness of the system in extracting objects in synthetic images.

We consider a communication system in which a transmitter is connected to a receiver through parallel channels, and the Go-Back-N ARQ scheme is used to handle transmission errors. A packet error on one channel results in retransmission of packets assigned to other channels under the Go-Back-N ARQ scheme. Therefore, the channel-grouping (a grouped-channel is used to transmit the same packet at a time), would affect the throughput performance. We analyze the throughput performance, and give a tree-algorithm to efficiently search for the optimal channel-grouping which makes the throughput to become maximum. Numerical results show that the throughput is largely improved by using the optimal channel-grouping.

A new class of the universal representation for the positive integers is proposed. The positive integers are divided into infinite groups, and each positive integer n is represented by a pair of integers (p,q), which means that n is the q-th number in the p-th group. It is shown that the new class includes the message length strategy as a special case, and the asymptotically optimal representation can easily be realized. Furthermore, a new asymptotically and practically efficient representation scheme is proposed, which preserves the numerical, lexicographical, and length orders.

In this paper, the effects of the grouping and the addressing methods on the accuracy and the response time in a visual search task were investigated. Four grouping conditions (4, 8, 16 and 32 groups) and four addressing methods (random, ordered, cartesian and polar) were selected in the experiment. For each combination of grouping and addressing methods, subjects repeated the search task 30 times. No remarkable differences of the percent correct were observed both among the levels of grouping and among the addressing methods. The mean response time increased with the increase of the number of groups. Moreover, the interaction between addressing methods and grouping for both percent correct and response time was clarified.