رضا مردانی

In this paper, three frequency divider structures for low-power and high-speed applications are proposed. In this design, true single phase clock (TSPC) flip-flop, AND modified gate diffusion input (AND_m-GDI) gate and multiplexer modified gate diffusion input (MUX_m-GDI) gate are used. This technique provides the dividers with reduced power consumption and high speed. Also, these blocks have a good performance at low supply voltage, which has a great effect on power consumption reduction. In order to improve the output swing in m-GDI cells under the mentioned supply voltage, complementary transistors have been used. The ÷2/3, ÷3/4 prescalers and ÷23/24 frequency divider are designed. Finally, according to the techniques used in this paper, a two-level frequency dividers with different values is proposed. The proposed frequency dividers are able to operate to 4 GHz, and their figure-of-merit (FoM) values in compared to other frequency dividers are improved, considerably. The maximum frequencies for the 2/3 and 3/4 are 4.5 GHz and 5 GHz, respectively. Average power consumption at frequency of 2.4 GHz, for the divider 2/3 and 3/4 are equal to 15.25 µW and 16.37 µW, respectively. The FoM values for the proposed frequency dividers in compared to others are considerably improved. Obtained results are based on post layout simulations performed with 65 nm CMOS technology.

The sound waves caused by the engine's operation and the rest of the floating interior equipment, if passed through a composite body, are detected by floating sea mines, especially acoustic mines. As a result, controlling and reducing the amount of sound transmitted from the floating body in operating parts is critical. In this study, due to the importance of passing the acoustic waves from the body of the particular vessels, the acoustic waves of different composite materials with layered and sandwich structures in water were evaluated and compared theoretically and experimentally. Five composite sheets were made to perform the tests. After placing them in water, the transmittance of acoustic waves per page was measured separately in two different frequency ranges. The first example is a sandwich panel with a plating foam core and glass and carbon fiber sheaths; the second specimen has a layered structure consisting of several layers of glass fiber, a third specimen like a second but with more layers, a fourth sample of sandwich panels with white wood core and shells. The fiberglass and final specimen are selected as a fourth sample but with a doped foam core. In the end, the results of the pages are presented in the form of a diagram and the necessary and applied comparisons between the experimental results and the theoretical calculations were made. The first and last samples are more absorbent than other specimens, even the first carbon-fiber sample is slightly better than the last one. It should be noted that the obtained results play an important role in the selection of composite materials and the design of a floating composite fuselage.