ÐWe present a novel data organization for disk arraysÐSegmented Information Dispersal (SID). SID provides protection against disk failures while ensuring that the reconstruction of the missing data requires only relatively small contiguous accesses to the available disks. SID has a number of properties that make it an attractive solution for fault-tolerant video servers. Under fault-free condit...

This paper describes an experimental comparison between a discrete stochastic optimization procedure (Simulated Annealing, SA) and a continuous deterministic one (Mean Field Annealing), as applied to the generation of Balanced Incomplete Block Designs (BIBDs). A neural cost function for BIBD generation is proposed with connections of arity four, and its continuous counterpart is derived, as req...

This paper deals with the generation of balanced incomplete block designs (BIBD), a hard constrained combinatorial problem with multiple applications. This problem is here formulated as a combinatorial optimization problem (COP) whose solutions are binary matrices. Two different neighborhood structures are defined, based on bit-flipping and position-swapping. These are used within three metaheu...

The class of nearly balanced incomplete block designs with concurrence range l, or NBBD(l), is defined. This extends previous notions of “most balanced” designs to cover settings where off-diagonal entries of the concurrence matrix must differ by a positive integer l ≥ 2. Sufficient conditions are found for optimality of NBBD(2)’s under type-1 criteria, then used to establish Aand D-optimality ...

In a completely randomized design the experimental material is divided into a number of units, or plots, to which a treatment can be applied. In a randomized block design the units are grouped into blocks so that the variation within blocks is less than the variation between blocks. If every treatment is applied to one plot in each block it is a complete block design. If there are fewer plots p...

A backtrack search with isomorph rejection is carried out to enumerate the 2-(12,3,2) designs. There are 242 995 846 such designs, which have automorphism groups whose size range from 1 to 1536. There are 88 616 310 simple designs. The number of resolvable designs is 62 929; these have 74 700 nonisomorphic resolutions. We use the following standard notations. A t-(v, k, >.) design is a family o...