A Novel Speech Enhancement Method Using Fourier Series Decomposition and Spectral Subtraction for Robust Speaker Identification

Wireless Personal Communications - This paper presents a novel speech enhancement approach by combining Fourier series expansion and spectral subtraction. This approach is implemented in speaker...     

Thermoelectric and Magnetic Properties of Pt-Substituted $${BaFe_{4-{x}}Pt_{{x}}Sb_{12}}$$ Compounds

\({BaFe_{4-{x}}Pt_{{x}}Sb_{12}}\) (x = 0, 0.1, 0.2) compounds were prepared by melting and annealing, followed by a spark plasma sintering method. Low-temperature thermoelectric and magnetic properties were investigated based on Seebeck coefficient, electrical and thermal conductivity and magnetization measurements. The structural properties of \({BaFe_{4-{x}}Pt_{{x}}Sb_{12}}\) (x = 0, 0.1, 0.2) compounds were ascertained by powder x-ray diffraction analysis, confirming that all samples have a main phase of a skutterudite structure with the space group Im\({\mathrm {\bar{3}}}\). The lattice parameters obtained, 9.202(5), 9.199(5) and 9.202(1) Å for x = 0, 0.1 and 0.2, respectively, were found consistent with literature. The Seebeck coefficient sign shows that holes are dominant carriers in all compounds. The local maximum Seebeck coefficient was observed around 50 K which may be a trace of paramagnon-drag effect of charge carriers. Thermal conductivity and electrical resistivity measurements were carried out between 4.2 and 300 K. Temperature dependence of electrical resistivity reflects that all samples show semi-metallic behavior in our temperature range of 4.2–300 K. Samples for x = 0.1 and x = 0.2 show Kondo-like behavior. In magnetization measurement, we observe that there are two successive magnetic transitions in Pt-substituted compounds; however, there is only one (transition from a paramagnetic state to long-range magnetic ordering) in Pt-free compounds. In Pt-substituted compounds, the first transition appears at \( T _{ {\rm c}}\) = 48 K. In addition, the second transition is observed at \( T _{ {\rm irr}}\) = 30 K where an intermediate state is observed before the magnetic ordering transforms to an irreversible ferromagnetic state. We concluded that Pt substitution on the Fe side effectual on the thermoelectric and magnetic properties of \({BaFe_{4-{x}}Pt_{{x}}Sb_{12}}\) (x = 0, 0.1, 0.2) compounds.     

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

A quantum‐tunneling metal‐insulator‐metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP‐CVD) for the first time. This scalable method is used to produce MIM diodes with high‐quality, pinhole‐free Al₂O₃ films more rapidly than by conventional vacuum‐based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum‐enabled devices. In fact, the MIM diodes fabricated by AP‐CVD show a lower effective barrier height (2.20 eV) at the electrode–insulator interface than those fabricated by conventional plasma‐enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero‐bias resistance, and better asymmetry of 107.     

SER and throughput analysis of space–time analog network coded relaying system over shadowed Rician fading channels

Wireless Networks - This research article presents an innovative approach based on analog network coding (ANC) in conjunction with space time block coding (STBC) which is termed as space time...     

Cold-cavity vectorial eigenmodes of VCSELs

An analytical approximate solution of Maxwell's equations for the cold-cavity eigenmodes of cylindrical etched air-post vertical-cavity surface-emitting lasers (VCSELs) is presented. In radial and azimuthal directions, the modes correspond to the hybrid modes of cylindrical optical waveguides. A vectorial transform matrix approach is derived which takes into account coupling of bound eigenmodes in VCSEL structures. The method is illustrated for the case of noncoupled modes and the corresponding simplified transform matrix approach is used to calculate the field profiles in longitudinal direction and predict the resonance wavelengths for the VCSEL eigenmodes. Although approximate, the resulting eigenmodes may be viewed as a useful alternative to full numerical solutions, especially with regard to future more comprehensive modeling of VCSELs     

Personal identification using feature and score level fusion of palm- and fingerprints

The ever increasing demand of security has resulted in wide use of Biometric systems. Despite overcoming the traditional verification problems, the unimodal systems suffer from various challenges like intra class variation, noise in the sensor data etc, affecting the system performance. These problems are effectively handled by multimodal systems. In this paper, we present multimodal approach for palm- and fingerprints by feature level and score level fusions (sum and product rules). The proposed multi-modal systems are tested on a developed database consisting of 440 palm- and fingerprints each of 55 individuals. In feature level fusion, directional energy-based feature vectors of palm- and fingerprint identifiers are combined to form joint feature vector that is subsequently used to identify the individual using a distance classifier. In score level fusion, the matching scores of individual classifiers are fused by sum and product rules. Receiver operating characteristics curves are formed for unimodal and multimodal systems. Equal Error Rate (EER) of 0.538% for feature level fusion shows best performance compared to score level fusion of 0.6141 and 0.5482% of sum and product rules, respectively. Multimodal systems, however, significantly outperform unimodal palm- and fingerprints identifiers with EER of 2.822 and 2.553%, respectively.     

Renewable and Storage Energy Integration for Smart Grid Housing

This paper presents the design,implementation and testing of an embedded system that integrates solar and storage energy resources to smart homes within the smart microgrid.The proposed system provides the required home energy by installing renewable energy and storage devices.It also manages and schedules the power flow during peak and off-peak periods.In addition,a two-way communication protocol is developed to enable the home owners and the utility service provider to improve the energy flow and the consumption efficiency.The system can be an integral part for homes in a smart grid or smart microgrid power networks.A prototype for the proposed system was designed,implemented and tested by using a controlled load bank to simulate a scaled random real house consumption behavior.Three different scenarios were tested and the results and findings are reported.Moreover,data flow security among the home,home owners and utility server is developed to minimize cyber-attacks.     

A Practical Space-Code Correlator Receiver for DSP Based Software Radio Implementation in CDMA2000

Development of practical algorithms for beamforming in 3G CDMA systems and their software radio implementations are still a challenging task, which will facilitate upgrading of traditional base stations into smart antenna capable 3G base stations. In this paper, we propose a practical space-code correlator (SCC) receiver structure for its software radio implementation a DSP. SCC’s advantage comes from the fact that it doesn’t require any training sequence or learning parameter as in other algorithms (LMS or CM). DSP implementations of the SCC are performed using Texas Instruments C67xx family platforms. In the simulations, reverse link base band signal format of CDMA2000 is used and the effects of different array topologies (uniform linear array-ULA or uniform circular array-UCA) are considered. The implementation results regarding beamforming accuracy, weight vector computation time (execution time), search resolution effect on DOA estimation accuracy, DSP resource utilization, and received SINR are presented. The results show that DSP based SCC beamformer can estimate weight vectors within less than 10 ms with DOA search resolution of 2° especially when C6713 DSP is used. With faster DSPs and larger search resolutions, execution time could be significantly reduced as well. It provides comparable SINR performance with LMS and CM algorithms.

Multipath channel identification by using global optimization in ambiguity function domain

A new transform domain array signal processing technique is proposed for identification of multipath communication channels. The received array element outputs are transformed to delay-Doppler domain by using the cross-ambiguity function (CAF) for efficient exploitation of the delay-Doppler diversity of the multipath components. Clusters of multipath components can be identified by using a simple amplitude thresholding in the delay-Doppler domain. Particle swarm optimization (PSO) can be used to identify parameters of the multipath components in each cluster. The performance of the proposed PSO-CAF technique is compared with the space alternating generalized expectation maximization (SAGE) technique and with a recently proposed PSO based technique at various SNR levels. Simulation results clearly quantify the superior performance of the PSO-CAF technique over the alternative techniques at all practically significant SNR levels.     

Detection of interdependent primary systems using wideband cognitive radios

Cognitive radios (CRs) may be sharing multiple frequency bands with primary systems if the CR is a wideband or an ultra wideband (UWB) system. In that case, the CR should ensure all the coexisting primary systems in these bands are detected before it can start data transmission. In this work, we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may be jointly active. Accordingly, we consider the implementation of energy detection scheme in multiple bands followed by two detection methods: (i) a maximum-a-posteriori (MAP) based detection (i.e., joint detection) that takes into account the statistics of simultaneously operating systems in independent bands and (ii) a Neyman–Pearson (NP) test based detection that optimizes the threshold values independently in each band (i.e., independent detection). For a simpler implementation of the independent detection, we show that the threshold values obtained from joint detection can be used in order to achieve the optimum NP test based independent detection results. In addition to quantifying the gain of joint detection over independent detection in terms of probabilities of false alarm and detection for practical scenarios, we also present the operation capability of CRs in terms of the fractions of time the CR can access the channel without interfering with the primary systems. The results are important for the practical implementation of multiband detection when the primary systems are known to be interdependent.