USE OF SHELL-CONTAINING SOIL IN TRANSPORT CONSTRUCTION

The article deals with the problem of using soils represented by sand with a significant content of shell in the construction of embankments of railways and highways. The review of literature sources on this topic did not yield any results, which aroused interest in the possibility of using this soil. Research has been carried out to determine the main physical and mechanical properties of shell sand. Data showing the dynamics of changes in the physical and mechanical properties of the soil during compaction are obtained. The dependence of the reduction of partial residues from 10 to 0.1 sieves is revealed. The maximum increase in the partial remainder occurs on the screen 0,1. Obviously, these changes are the result of grinding the soil under the influence of a large mechanical load and are one of the factors reducing filtration in this soil. It is found that the value of the filtration coefficient at the input control is 2.58 m/day., after compaction of the same soil in the body of the embankment, the filtration coefficient fell to-1.51 m/day. Thus, there is a decrease in the filtration coefficient after compaction of the soil by 41.5% in comparison with the input tests of the soil. The need for further research to find technological solutions for the use of such soil on road construction sites is justified.

On the Redundant Representation of Partial Remainders in Radix-4 SRT Dividers

Most digit-recurrence algorithms for division, such as the Sweeney–Robertson–Tocher (SRT) algorithm, have been used in order to take advantage of the redundant representations of the partial remainder. This way, full carry propagate additions are avoided, obtaining significant latency improvements. Furthermore, the delay corresponding to one division iteration is independent of the size of the operands. The most frequent redundant form for the partial remainders is the carry-save (CS) representation, which uses 2 bits of representation (carry and sum bits) for each bit of the partial remainder. This paper proposes radix-4 SRT dividers which use (3, 2) redundancy (3 bits of representation for 2 bits of the partial remainder) and (5, 4) redundancy (5 bits of representation for 4 bits of the partial remainder). The goal of using these representations is represented by a decreased cost due to the reduced number of sequential elements required to store the partial remainder. The proposed dividers use 2-bit carry propagate adders and 4-bit carry propagate adders to compute the new partial remainder. Thus, the full carry propagate addition is avoided, while the latency of one division iteration is independent of the operands’ size. The synthesis result for Xilinx Virtex-5 FPGA devices show that similar working frequencies are obtained for divider using the proposed redundant representation with respect to the conventional carry-save, while requiring up to 12% for (3, 2) representation and 18% for (5, 4) representation less sequential elements.