Bragg Reflection Waveguide: Anti-Mirror Reflection and Light Slowdown

The effect of the light group velocity reduction in dielectric Bragg reflection waveguide structures (SiO$_2$/TiO$_2$) in the vicinity of the cutoff frequency is studied experimentally. The effect of anti-mirror reflection, specific for the Bragg reflection waveguides, is described and employed for detection of "slow light". The experiments were performed with the use of the Ti:sapphire laser pulses ~ 100 fs in length. The group index $n_g \sim$ 30 with a fractional pulse delay (normalized to the pulse width) of $\sim$ 10 is demonstrated. The problems and prospects of implementation of the slow-light devices based on the Bragg reflection waveguide structures are discussed.Comment: 11 pages, in the previous version, we failed to insert figure

High Speed Dim Air Target Detection Using Airborne Radar under Clutter and Jamming Effects

The challenging potential problems associated with using airborne radar in detection of high Speed Maneuvering Dim Target (HSMDT) are the highly noise, jamming and clutter effects. The problem is not only how to remove clutter and jamming as well as the range migration and Doppler ambiguity estimation problems due to high relative speed between the targets and airborne radar. Some of the recently published works ignored the range migration problems, while the others ignored the Doppler ambiguity estimation. In this paper a new hybrid technique using Optimum Space Time Adaptive Processing (OSTAP), Second Order Keystone Transform (SOKT), and the Improved Fractional Radon Transform (IFrRT) was proposed. The OSTAP was applied as anti-jamming and clutter rejection method, the SOKT corrects the range curvature and part of the range walk, then the IFrRT estimates the target’ radial acceleration and corrects the residual range walk. The simulation demonstrates the validity and effectiveness of the proposed technique, and its advantages over the previous researches by comparing its probability of detection with the traditional methods. The new approach increases the probability of detection, and also overcomes the limitation of Doppler frequency ambiguity

Evaluation of operational amplifier immunity by means of Weibull distribution

The immunity of operational amplifiers is a trend topic for electromagnetic compatibility EMC community. Radiofrequency interference is usually applied to the operation amplifier and the voltage offset is monitored as a parameter to evaluate the EMC degradation. However, this method does not provide enough information to know the probability of failure to electromagnetic interference of the devices. In this paper, an alternative statistical analysis based on the Weibull distribution is used to analyze the electromagnetic immunity performance of operational amplifiers under different frequency interferences and modulation index. The results confirm the feasibility of the Weibull distribution to evaluate the radiofrequency interference RFI behavior.Peer ReviewedPostprint (author’s final draft

Small Multi-Band Rectangular Dielectric Resonator Antennas for Personal Communication Devices

The design of a novel rectangular dielectric resonator antenna (DRA) for multi-band application has been presented in this paper. The presented antenna has been composed of very low cost and relatively low dielectric constant substrate materials while three-segment thin dielectrics with different sizes have been used and separated by two metal plates in order to set the four different frequency bands. The proposed quad-band antenna operates at 2.4/3.5/5.2 & 5.8 GHz. The radiation pattern, gain and VSWR of this antenna show very good operation for this antenna in all frequency bands. The first method based on finite element method (FEM) and the second one based on finite integral technique (FIT) have been used to analyze antenna structure, and subsequently the Genetic Algorithm (GA) has been applied by using HFSS simulator to obtain the optimized parameters.DOI:http://dx.doi.org/10.11591/ijece.v4i1.457

The New ADE-TLM Algorithm for Modeling Debye Medium

In this paper, we present a novel approach to simulating the interaction between electromagnetic waves and a Debye medium utilizing a Transmission Line Matrix (TLM) algorithm with the symmetrical condensed node (SCN-TLM) technique. The proposed method utilizes the polarization current within the media and incorporates the auxiliary differential equation (ADE) technique to handle scattering following the conventional discretization process. The averaged approximation is employed to utilize the polarization current density J and the electric voltage. By reducing the number of operations required per iteration, the New ADE- TLM method has successfully decreased the computational time compared to time convolution techniques. Despite this reduction in computational time, the New ADE-TLM method maintains a numerical accuracy that is comparable to that of time convolution techniques. The efficiency and precision of this approach are confirmed by the agreement between the results obtained and those predicted by the analytic model

Heuristics for Routing and Spiral Run-time Task Mapping in NoC-based Heterogeneous MPSOCs

This paper describes a new Spiral Dynamic Task Mapping heuristic for mapping applications onto NoC-based Heterogeneous MPSoC. The heuristic proposed in this paper attempts to map the tasks of an applications that are most related to each other in spiral manner and to find the best possible path load that minimizes the communication overhead. In this context, we have realized a simulation environment for experimental evaluations to map applications with varying number of tasks onto an 8x8 NoC-based Heterogeneous MPSoCs platform, we demonstrate that the new mapping heuristics with the new modified dijkstra routing algorithm proposed are capable of reducing the total execution time and energy consumption of applications when compared to state-of the-art run-time mapping heuristics reported in the literature

Cardinality Enhancement of SAC-OCDMA Systems Using New Diagonal Double Weight Code

Optical code division multiple access (OCDMA) provides  another dimension to multiple access systems,  in which each user is assigned a unique code. This allows  each subscriber  to simultaneously access the medium without any contention. However, simultaneous access of multiple users introduce multiple access interference  (MAI)  which primarily deteriorates  the performance of OCDMA systems.  This paper proposes a new code called diagonal double weight (DDW) code to elevate the performance and cardinality of spectral amplitude coding  (SAC) OCDMA  systems. Performance of our proposed code is evaluated using comprehensive analytical  analysis  followed by simulation analysis. Examination  of bit error rate shows that DDW code along with  single photodiode detection  technique  provides efficient performance, with added benefits of simplified design, large cardinality and ease of implementation