XBLOC-PLUS – DEVELOPMENT OF A REGULAR PLACED INTERLOCKING ARMOUR UNIT

Randomly placed single layer interlocking concrete armor units are currently the most advanced and cost-efficient option for the protection of breakwaters. The key feature of these units is the random orientation of the units, which requires the crane operator to assess the orientation of each individual unit during block placement. DMC noticed the desire for a block which can be placed in a regular pattern as this will increase the placement rates. Apart of this, regular placement of armor units can also be preferred for aesthetical reasons. Fifteen years after the introduction of Xbloc, DMC therefore introduces a new breakwater armour unit called XblocPlus which is placed with uniform block orientations.

A 1D CELLULAR AUTOMATON THAT MOVES PARTICLES UNTIL REGULAR SPATIAL PLACEMENT

We consider a finite cellular automaton with particles where each site can host at most one particle. Starting from an arbitrary initial configuration, our goal is to move the particles between neighbor sites until the distance to the nearest particle is minimized globally. Such a configuration corresponds in fact to a regular placement. This problem is a cellular automata equivalent of load-balancing in parallel computing, where each task is a particle and each processor a connected set of sites. We present a cellular automata rule that solves this problem in the 1D case, and is convergent, i.e. once the regular placement is achieved, the configuration does not change anymore. The rule is inspired from the Lloyd algorithm, computing a centroidal Voronoi tessellation. The dynamic of the rule is described at a higher level, using self-explanatory space-time diagrams. They exhibit signals acting as quantity of movement carrying the energy of system. Each signal bounces or pass through particles, causing their movement, until it eventually reaches the border and vanishes. When signals have all vanished, particles are regularly placed.

NET-REGULAR PLACEMENT FOR HIGH PERFORMANCE CIRCUITS

We examine a placement strategy incorporating the knowledge of underlying circuit structure targeted for high performance circuits. We measure the "net regularity" using the standard deviation of the locations of its terminals. Experimental results showed that exploiting circuit structural information led to substantially more regular nets, compared to placement without structural information. Benchmark circuits from MCNC showed 1.9 to 26 times increase in the number of nets with zero standard deviation. Furthermore, the length of the longest net in a chip was reduced from 5 to 22%. The placement strategy is crucial for high performance circuits since regular nets have relatively fewer vias and reducing the longest net length improves signal delay.

Discrimination of Stimulus Aperiodicity as a Function of Temporal Patterning: A Discrepancy between Psychophysical and Sensory—Neural Assessments

Tactile discrimination of stimulus aperiodicity was investigated in a two-alternative forced-choice task by having subjects report which of two successively presented trains of mechanical pulses, one with complete pulse periodicity and one in which a single pulse was temporally displaced from its regular placement, was temporally irregular or aperiodic. Trains contained three, four, or five pulses and were presented at interpulse intervals of 60, 75, 85, 100, 125, and 150 ms. Aperiodic trains had one pulse, other than the first or last pulse, temporally advanced or receded by 40% of the interstimulus interval. Results showed that: (i) although the percentage of correct reports of aperiodicity decreased as presentation rate increased (smaller interpulse intervals), the amount of decrease was a function of the number of pulses in a train; (ii) the discrimination of aperiodicity was dependent upon the specific location of the irregularity within the stimulus temporal pattern; and (iii) all patterns with complete temporal reversals of their successive interpulse intervals yielded nearly equivalently accurate reports of aperiodicity. These data suggest that central, attentional factors are involved in the discrimination of stimulus aperiodicity.