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  • Author: Cong Dinh Nguyen x
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Loessoid Soils Improvement – Laboratory Tests and Road Engineering Applications

Abstract

Moisture-sensitive or collapsible soils are materials with high porosity that under the loads transmitted by the superstructure or even under its own weight present additional settlements once the soil is saturated. This category includes loess deposits and other high silt content soils with uneven porosity. A method often used for foundation on these soils is the realization of local loessoid material compacted columns. This paper presents, on one hand, the experimental laboratory programs aiming to achieve some optimal mixtures of local material (loess) and different other materials (sand, bentonite, cement) in order to improve the values of the mechanical parameters of the soil and so, to limit the settlements. On the other hand, it presents a lot of settlement calculations for different case scenarios.

Open access
Controlling sequence length of DS-IR-UWB to enhance performance of multi-WBAN systems

Abstract

The international standard of wireless body area networks (WBANs), ie IEEE 802.15.6, was established in Feb. 2012, and this standard decided spreading code as a suppressing interference technology. However, the sequence length of spreading code is fixed, hence it is difficult to guarantee secure communications due to noise and interference from other WBANs. In this paper, we propose utilizing direct sequence impulse radio ultra wideband (DS-IR-UWB) for multi-WBAN systems, and then analyze multi-WBAN systems theoretically, derive equations of inter-WBAN interference, packet error rate (PER) and throughput. Furthermore, to guarantee secure communications, the desired PER is introduced, and then an algorithm is proposed to take the control of sequence length of DS-IR-UWB in order to ensure that the PER of system is always below the desired PER while maximizing the throughput. The numerical evaluation shows that the sequence length of proposed control method is changed according to the SNR and the number of WBANs, it lets the proposed algorithm of control of sequence length outperform the conventional fixed sequence length method.

Open access