A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, designed, and investigated in this paper. The metamaterial is composed of modified S-shaped split-ring resonators (S-SRR). The periodic structure is designed and simulated using CST MWs. Next, the experiments are carried out, and it is shown that the simulation and the experimental results agree well and the designed structure has a wide bandwidth in X-band. An absorber application of this metamaterial is also provided, and the structure can be used as an absorber with absorption rate of over 80% for the polarization angles between 0 ∘ and 40 ∘ .
Spillways are constructed to evacuate the flood discharge safely not to let the flood wave overtop the dam body. There are different types of spillways, ogee type being the conventional one. Stepped spillway is an example of nonconventional spillways. The turbulent flow over stepped spillway was studied numerically by using the Flow-3D package. Different fluid flow characteristics such as longitudinal flow velocity, temperature distribution, density and chemical concentration can be well simulated by Flow-3D. In this study, the influence of slope changes on flow characteristics such as air entrainment, velocity distribution and dynamic pressures distribution over the stepped spillway was modelled by Flow-3D. The results from the numerical model were compared with the experimental study done by others in the literature. Two models of the stepped spillway with different discharge for each model was simulated. The turbulent flow in the experimental model was simulated by the Renormalized Group (RNG) turbulence scheme in the numerical model. A good agreement was achieved between the numerical results and the observed ones, which were exhibited in terms of graphics and statistical tables.
Our project was divided into two distinct sections, circuit transmitting and receiving ultrasound Wave Based on Laser Light. A Wien Bridge and a Triangle Wave Oscillators used to obtain a sine and a triangular wave, respectively. A comparator circuit which produces Pulse Width Modulation (PWM) that has the same frequency for triangle wave. The PWM was used to drive laser diode that produced laser light through by MOSFET transistor and received this light by receiving circuit which consists of a photodiode with resistor as a voltage divider, amplifier circuit to amplify the signal and filter to get any desired frequency. The main objective of this project primarily was to realize a transmission-reception system to transfer ultrasound Frequency via Laser without a guiding medium, using modulation with little quality loss.
A Fishnet-Mushroom-like metamaterial electromagnetic behaviour is represented in S-parameters numerically and experimentally for X-band frequencies arena. The design has introduced a dielectric substrate as a host with metallic parts. The proposed design is predicted to provide the electromagnetic band gap characterization with desired reiterative characteristic parameters, negative permittivity, and negative permeability exhibiting a double negative left-handed region, which is identified with the X-band regime with good agreement between the simulated and the measured results.
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