In this paper we propose a new space diversity scheme for broadband PLC systems using orthogonal space-time block coding (OSTBC) transmission combined with Single-carrier Frequency-domain equalization (SC-FDE). To apply this diversity technique to PLC channels, we first propose a new technique for combining SC-FDE with OSTBCs applicable to all dispersive multipath channels impaired by impulsive noise. The proposed technique is then applied to indoor and outdoor PLC channels under different channel scenarios in the presence of background and impulsive noises. We perform the simulations for SISO, MISO and MIMO configurations and show that a significant SNR gain is achieved when SC-FDE is combined with diversity techniques. We also compare our proposed technique with OFDM using Alamouti code for broadband PLC and show the superiority of our technique.

The sonochemical activity of an oxygen bubble formed in an aqueous medium and oscillating under a dual-Frequency excitation is studied in this paper. Several couples of frequencies are formed amongst 35, 140, 300, and 515 kHz, with a maximum acoustic amplitude of 1. 5 atm. The molar yields of the emerging oxidants are analyzed in accordance with the combined frequencies and compared to the cases of mono-Frequency excitations of similar maximum amplitude, i. e., 1. 5 atm. Qualitatively, passing from a mono to a dual-Frequency excitation demonstrated to be with no effect on the predominant species which remain 𝐻 𝑂 • , 𝐻 𝑂 2• , 𝑂 and 𝑂 3. However, the results exhibited a very selective quantitative evolution depending on the combined frequencies. Some couples proved to induce a negative effect and reduce the production at the Single bubble level, particularly with basic frequencies of 140 and 300 kHz, while some others demonstrated a noticeable enhancement such as the couples (35, 140 kHz) and (515, 35 kHz), as compared to mono-Frequency fields.

In this paper we present the problem of designing a three level hub center Network. In our Network, the top level consists of a complete Network where a direct link is between all central hubs. The second and third levels consist of star Networks that connect the hubs to central hubs and the demand nodes to hubs and thus to central hubs, respectively. We model this problem in an incomplete Network environment. In this case, the top level is an incomplete Network where the direct link between all central hubs is not necessary and may lead to lower transportation costs. We propose mixed integer programming model for these problems and conduct a computational study for these two developed models by using the CAB data.