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Biomedical Engineering

This page shows you the most recent publications within this specialty of the MedWorm directory. This is page number 13.

An Efficient and Compact Compressed Sensing Microsystem for Implantable Neural Recordings
Multi-Electrode Arrays (MEA) have been widely used in neuroscience experiments. However, the reduction of their wireless transmission power consumption remains a major challenge. To resolve this challenge, an efficient on-chip signal compression method is essential. In this paper, we first introduce a signal-dependent Compressed Sensing (CS) approach that outperforms previous works in terms of compression rate and reconstruction quality. Using a publicly available database, our simulation results show that the proposed system is able to achieve a signal compression rate of 8 to 16 while guaranteeing almost perfect spike cl...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

A 2.4 GHz ULP Reconfigurable Asymmetric Transceiver for Single-Chip Wireless Neural Recording IC
This paper presents a 2.4 GHz ultra-low-power (ULP) reconfigurable asymmetric transceiver and demonstrates its application in wireless neural recording. Fabricated in $0.13~mu{rm m}$ CMOS technology, the transceiver is optimized for sensor-gateway communications within a star-shaped network, and supports both the sensor and gateway operation modes. Binary phase-shift keying (BPSK) modulation with high data rate (DR) of 1 to 8 Mbps is used in the uplink from sensor to gateway, while on-off keying (OOK) modulation with low DR of 100 kbps is adopted in the downlink. A fully integrated Class-E PA with moderate output power has...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

A Frequency Shaping Neural Recorder With 3 pF Input Capacitance and 11 Plus 4.5 Bits Dynamic Range
This paper presents a frequency-shaping (FS) neural recording architecture and its implementation in a 0.13 $mu$ m CMOS process. Compared with its conventional counterpart, the proposed architecture inherently rejects electrode offset, increases input impedance 5–10 fold, compresses neural data dynamic range (DR) by 4.5-bit, simultaneously records local field potentials (LFPs) and extracellular spikes, and is more suitable for long-term recording experiments. Measured at a 40 kHz sampling clock and ${pm} 0.6$ V supply, the recorder consumes 50 $mu$W/ch, of which 22 $,mu$W per FS amplifier, 24 $mu$ W per buffer, 4 $m...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

A Digitally Assisted, Signal Folding Neural Recording Amplifier
A novel signal folding and reconstruction scheme for neural recording applications that exploits the $1/f^{n}$ characteristics of neural signals is described in this paper. The amplified output is ‘folded’ into a predefined range of voltages by using comparison and reset circuits along with the core amplifier. After this output signal is digitized and transmitted, a reconstruction algorithm can be applied in the digital domain to recover the amplified signal from the folded waveform. This scheme enables the use of an analog-to-digital convertor with less number of bits for the same effective dynamic range. It...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

Programmable ExG Biopotential Front-End IC for Wearable Applications
This paper presents a configurable CMOS integrated circuit front-end for the recording of a wide range of biopotentials (ExG). The system offers a choice between a single-differential or double-differential recording channel topology, wide continuously adjustable gain range (37–66 dB), selectable CMOS or BJT input stages, offset compensation, differential and buffered single-ended voltage output. Measured results from a prototype manufactured in 0.35 $mu{rm m}$ CMOS technology are presented. Practical recording examples of the electrocardiogram (ECG) and electromyogram (EMG) confirm its operation. The chip consumes ...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Biomedical Circuits and Systems publication information
(Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

Asynchronous Binaural Spatial Audition Sensor With 2$,times,$64$,times,$4 Channel Output
This paper proposes an integrated event-based binaural silicon cochlea system aimed at efficient spatial audition and auditory scene analysis. The cochlea chip has a matched pair of digitally-calibrated 64-stage cascaded analog second-order filter banks with 512 pulse-frequency modulated (PFM) address-event representation (AER) outputs. The quality factors (Qs) of channels are individually adjusted by local DACs. The 2P4M 0.35 um CMOS chip consumes an average power of 14 mW including its integrated microphone preamplifiers and biasing circuits. Typical speech data rates are 10 k to 100 k events per second (eps) with peak o...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

Real-Time Embedded Implementation of the Binary Mask Algorithm for Hearing Prosthetics
In this paper, we present a real-time embedded implementation of the binary masking algorithm, which has been shown to significantly improve speech-in-noise intelligibility. Our real-time implementation relies on a balance of parallel processing and hardware pipelining. We have tested and evaluated our implementation on a Spartan 3A FPGA. The measured latency was 8.5 ms . The highest measured improvement in short-time objective intelligibility was 85%. (Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

A Real-Time Research Platform to Study Vestibular Implants With Gyroscopic Inputs in Vestibular Deficient Subjects
We describe a system based on National Instrument's CompactRIO platform that can meet this requirement and also offers floating point precision for advanced transfer functions. It is designed for acute clinical interventions, and is sufficiently powerful and flexible to serve as a development platform for evaluating prosthetic control strategies. Amplitude and pulse frequency modulation to predetermined functions or sensor inputs have been validated. The system has been connected to human patients, who each have received a modified MED-EL cochlear implant for vestibular stimulation, and patient tests are ongoing. (Source: ...
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

Table of Contents
(Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - July 25, 2014 Category: Biomedical Engineering Source Type: research

A magnetic resonance imaging study on the articulatory and acoustic speech parameters of Malay vowels
The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all...
Source: BioMedical Engineering OnLine - July 25, 2014 Category: Biomedical Engineering Authors: Alireza ZourmandSeyed MirhassaniHua-Nong TingShaik BuxKwan NgMehmet BilgenMohd Jalaludin Source Type: research

Improving the growth of Rubrivivax gelatinosus cultivated in sewage environment.
Abstract Rubrivivax gelatinosus cultivated in wastewater environment can combine the biomass resource recycling for generating chemicals with sewage purification. However, low biomass accumulation restricts the exertion of this advantage. Thus, this paper investigated Fe(3+) advancement for biomass production in starch wastewater under light-anaerobic condition. Results showed that addition of Fe(3+) was successful in enhancing biomass production, which certainly improved the feasibility of biomass recycling in R. gelatinosus starch wastewater treatment. With optimal Fe(3+) dosage (20 mg/L), biomass production rea...
Source: Bioprocess and Biosystems Engineering - July 25, 2014 Category: Biomedical Engineering Authors: Wu P, Li JZ, Wang YL, Tong QY, Liu XS, Du C, Li N Tags: Bioprocess Biosyst Eng Source Type: research

Mathematica numerical simulation of peristaltic biophysical transport of a fractional viscoelastic fluid through an inclined cylindrical tube.
Abstract This paper studies the peristaltic transport of a viscoelastic fluid (with the fractional second-grade model) through an inclined cylindrical tube. The wall of the tube is modelled as a sinusoidal wave. The flow analysis is presented under the assumptions of long wave length and low Reynolds number. Caputo's definition of fractional derivative is used to formulate the fractional differentiation. Analytical solutions are developed for the normalized momentum equations. Expressions are also derived for the pressure, frictional force, and the relationship between the flow rate and pressure gradient. Mathemati...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 25, 2014 Category: Biomedical Engineering Authors: Tripathi D, Bég OA Tags: Comput Methods Biomech Biomed Engin Source Type: research

Lagrangian Postprocessing of Computational Hemodynamics.
Abstract Recent advances in imaging, modeling, and computing have rapidly expanded our capabilities to model hemodynamics in the large vessels (heart, arteries, and veins). This data encodes a wealth of information that is often under-utilized. Modeling (and measuring) blood flow in the large vessels typically amounts to solving for the time-varying velocity field in a region of interest. Flow in the heart and larger arteries is often complex, and velocity field data provides a starting point for investigating the hemodynamics. This data can be used to perform Lagrangian particle tracking, and other Lagrangian-base...
Source: Annals of Biomedical Engineering - July 25, 2014 Category: Biomedical Engineering Authors: Shadden SC, Arzani A Tags: Ann Biomed Eng Source Type: research

Automatic modeling of corrective prosthesis using artificial neural networks
–1Pectus excavatum is the most common deformity of the thoracic wall, occurring between 1/400 and 1/1000 births and a male to female ratio of 4:1. It is characterized by a depression in the patient chest, which demands surgical correction in a high percentage of cases [1,2]. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 25, 2014 Category: Biomedical Engineering Authors: Pedro L. Rodrigues, Nuno F. Rodrigues, ACM Pinho, Jaime C. Fonseca, Jorge Correia-Pinto, João L. Vilaça Source Type: research

Predicting flow in aortic dissection: Comparison of computational model with PC-MRI velocity measurements
Aortic dissection is a life-threatening process in which the weakened wall develops a tear, causing separation of wall layers. The dissected layers separate the original true aortic lumen and a newly created false lumen. If untreated, the condition can be fatal. Flow rate in the false lumen is a key feature for false lumen patency, which has been regarded as one of the most important predictors of adverse early and later outcomes. Detailed flow analysis in the dissected aorta may assist vascular surgeons in making treatment decisions, but computational models to simulate flow in aortic dissections often involve several ass...
Source: Medical Engineering and Physics - July 25, 2014 Category: Biomedical Engineering Authors: Z. Cheng, C. Juli, N.B. Wood, R.G.J. Gibbs, X.Y. Xu Source Type: research

Biomedical engineer looks at new applications for novel lupus drug
(University of Houston) Expanding on his work with a new drug that successfully treated lupus in mice, a biomedical engineer at the University of Houston has received a $250,000 grant to expand his research to a new version of the drug in an effort to treat a wider range of autoimmune diseases.The drug that Chandra Mohan and his collaborators at a biopharmaceutical firm are focused on targets B cells, key cells in the immune system that lead to the development of lupus. (Source: EurekAlert! - Medicine and Health)
Source: EurekAlert! - Medicine and Health - July 24, 2014 Category: Global & Universal Source Type: news

Investigation of gastric cancers in nude mice using X-ray in-line phase contrast imaging
Conclusions: This is a very preliminary feasibility study. With further researches, XILPCI could become a noninvasive method for future the early detection of gastric cancers or medical researches. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - July 24, 2014 Category: Biomedical Engineering Authors: Qiang TaoShuqian Luo Source Type: research

Arterial pulsatility improvement in a feedback-controlled continuous flow left ventricular assist device: An ex-vivo experimental study
Continuous flow left ventricular assist devices (CF-LVADs) reduce arterial pulsatility, which may cause long-term complications in the cardiovascular system. The aim of this study is to improve the pulsatility by driving a CF-LVAD at a varying speed, synchronous with the cardiac cycle in an ex-vivo experiment. A Micromed DeBakey pump was used as CF-LVAD. The heart was paced at 140bpm to obtain a constant cardiac cycle for each heartbeat. First, the CF-LVAD was operated at a constant speed. At varying-speed CF-LVAD assistance, the pump was driven such that the same mean pump output was generated. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 24, 2014 Category: Biomedical Engineering Authors: Selim Bozkurt, Sjoerd van Tuijl, Stephanie Schampaert, Frans N. van de Vosse, Marcel C.M. Rutten Source Type: research

An in vitro investigation of the influence of stenosis severity on the flow in the ascending aorta
Cardiovascular diseases can lead to abnormal blood flows, some of which are linked to hemolysis and thrombus formation. Abnormal turbulent flows of blood in the vessels with stenosis create strong shear stresses on blood elements and may cause blood cell destruction or platelet activation. We implemented a Lagrangian (following the fluid elements) measurement technique of three dimensional particle tracking velocimetry that provides insight on the evolution of viscous and turbulent stresses along blood element trajectories. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 24, 2014 Category: Biomedical Engineering Authors: Utku Gülan, Beat Lüthi, Markus Holzner, Alex Liberzon, Arkady Tsinober, Wolfgang Kinzelbach Source Type: research

A neural network approach for determining gait modifications to reduce the contact force in knee joint implant
This study employed an artificial neural network to develop a cost-effective computational framework for designing gait rehabilitation patterns. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 24, 2014 Category: Biomedical Engineering Authors: Marzieh Mostafavizadeh Ardestani, Zhenxian Chen, Ling Wang, Qin Lian, Yaxiong Liu, Jiankang He, Dichen Li, Zhongmin Jin Source Type: research

Changes in dissipated energy and contact pressure after osteochondral graft transplantation
Osteochondral autologous transplantation is frequently used to repair small cartilage defects. Incongruence between the osteochondral graft surface and the adjacent cartilage leads to changed friction and contact pressure. The present study wanted to analyze the differences between intact and surgically treated cartilage surface in respect to contact pressure and frictional characteristic (dissipated energy). Six ovine carpometacarpal joints were used in the present study. Dissipated energy during instrumentally controlled joint movement as well as static contact pressure were measured in different cartilage states (intact...
Source: Medical Engineering and Physics - July 24, 2014 Category: Biomedical Engineering Authors: Evgenij Bobrowitsch, Andrea Lorenz, Johanna Jörg, Ulf G. Leichtle, Nikolaus Wülker, Christian Walter Source Type: research

A multinational, biomedical engineering student, clinical immersion experience in obstetrics in Ghana
Among other obstacles, the continued lack of access to health technology, especially in low-resource countries, will contribute to many failing to meet Millennium Development Goal 5 by 2015 [1]. There is growing recognition among the global health community of the role that appropriate cost-effective health technologies can play in supporting healthcare providers’ ability to deliver minimum standards of care [2,3]. (Source: International Journal of Gynaecology and Obstetrics)
Source: International Journal of Gynaecology and Obstetrics - July 24, 2014 Category: OBGYN Authors: Kathleen H. Sienko, Elsie Effah Kaufmann, Moses E. Musaazi, Amir S. Sarvestani, Samuel Obed Source Type: research

Obstetrics-based clinical immersion of a multinational team of biomedical engineering students in Ghana
Among other obstacles, the continued lack of access to health technology, especially in low-resource countries, will contribute to many failing to meet Millennium Development Goal 5 by 2015 [1]. There is growing recognition among the global health community of the role that appropriate cost-effective health technologies can play in supporting healthcare providers’ ability to deliver minimum standards of care [2,3]. (Source: International Journal of Gynaecology and Obstetrics)
Source: International Journal of Gynaecology and Obstetrics - July 24, 2014 Category: OBGYN Authors: Kathleen H. Sienko, Elsie Effah Kaufmann, Moses E. Musaazi, Amir Sabet Sarvestani, Samuel Obed Source Type: research

Clinical and pathological correlates of severity classifications in trigger fingers based on computer-aided image analysis
Conclusions: The criteria of clinical classification were found to be highly associated with the pathological changes of affected tissues. The correlations serve as explicit evidence supporting clinicians in making a treatment strategy of trigger finger. In addition, our proposed computer-aided image analysis system was considered to be a promising and objective approach to determining trigger finger severity at the microscopic level. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - July 23, 2014 Category: Biomedical Engineering Authors: Tai-Hua YangHsin-Chen ChenYung-Chun LiuHui-Hsuan ShihLi-Chieh KuoStephen ChaHsiao-Bai YangDee-Shan YangI-Ming JouYung-Nien SunFong-Chin Su Source Type: research

The effect of baseline pressure errors on an intracranial pressure-derived index: results of a prospective observational study
Background: In order to characterize the intracranial pressure-volume reserve capacity, the correlation coefficient (R) between the ICP wave amplitude (A) and the mean ICP level (P), the RAP index, has been used to improve the diagnostic value of ICP monitoring. Baseline pressure errors (BPEs), caused by spontaneous shifts or drifts in baseline pressure, cause erroneous readings of mean ICP. Consequently, BPEs could also affect ICP indices such as the RAP wherein the mean ICP is incorporated. Methods: A prospective, observational study was carried out on patients with aneurysmal subarachnoid hemorrhage (aSAH) undergoing IC...
Source: BioMedical Engineering OnLine - July 23, 2014 Category: Biomedical Engineering Authors: Per EideAngelika SortebergTorstein MelingWilhelm Sorteberg Source Type: research

Capacitive Measurement of ECG for Ubiquitous Healthcare.
Abstract The technology for measuring ECG using capacitive electrodes and its applications are reviewed. Capacitive electrodes are built with a high-input-impedance preamplifier and a shield on their rear side. Guarding and driving ground are used to reduce noise. An analysis of the intrinsic noise shows that the thermal noise caused by the resistance in the preamplifier is the dominant factor of the intrinsic noise. A fully non-contact capacitive measurement has been developed using capacitive grounding and applied to a non-intrusive ECG measurement in daily life. Many ongoing studies are examining how to enhance ...
Source: Annals of Biomedical Engineering - July 23, 2014 Category: Biomedical Engineering Authors: Lim YG, Lee JS, Lee SM, Lee HJ, Park KS Tags: Ann Biomed Eng Source Type: research

Kernel Additive Models for Source Separation
Source separation consists of separating a signal into additive components. It is a topic of considerable interest with many applications that has gathered much attention recently. Here, we introduce a new framework for source separation called Kernel Additive Modelling, which is based on local regression and permits efficient separation of multidimensional and/or nonnegative and/or non-regularly sampled signals. The main idea of the method is to assume that a source at some location can be estimated using its values at other locations nearby, where nearness is defined through a source-specific proximity kernel. Such a ker...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Outage-Constrained Coordinated Beamforming With Opportunistic Interference Cancellation
In this paper, interference management is considered for the K-user multiple-input single-output (MISO) block-faded interference channel. It is assumed that perfect channel state information (CSI) can be obtained at the receivers, whereas only channel distribution information (CDI) is available to the transmitters. Furthermore, the receivers are assumed to be capable of implementing opportunistic interference cancellation (OIC). Based on these assumptions, the beamforming design problem for the MISO interference channel under consideration is formulated as a rate utility maximization problem under outage constraints and in...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

An MGF-Based Unified Framework to Determine the Joint Statistics of Partial Sums of Ordered i.n.d. Random Variables
The joint statistics of partial sums of ordered random variables (RVs) are often needed for the accurate performance characterization of a wide variety of wireless communication systems. A unified analytical framework to determine the joint statistics of partial sums of ordered independent and identically distributed (i.i.d.) random variables was recently presented. However, the identical distribution assumption may not be valid in several real-world applications. With this motivation in mind, we consider in this paper the more general case in which the random variables are independent but not necessarily identically distr...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

An Online Algorithm for Separating Sparse and Low-Dimensional Signal Sequences From Their Sum
This paper designs and extensively evaluates an online algorithm, called practical recursive projected compressive sensing (Prac-ReProCS), for recovering a time sequence of sparse vectors $S_{t}$ and a time sequence of dense vectors $L_{t}$ from their sum, $M_{t}:=S_{t}+L_{t}$, when the $L_{t}$ 's lie in a slowly changing low-dimensional subspace of the full space. A key application where this problem occurs is in real-time video layering where the goal is to separate a video sequence into a slowly changing background sequence and a sparse foreground sequence that consists of one or more moving regions/objects on-the-fly. ...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

A Primal-Dual Proximal Algorithm for Sparse Template-Based Adaptive Filtering: Application to Seismic Multiple Removal
Unveiling meaningful geophysical information from seismic data requires to deal with both random and structured “noises”. As their amplitude may be greater than signals of interest (primaries), additional prior information is especially important in performing efficient signal separation. We address here the problem of multiple reflections, caused by wave-field bouncing between layers. Since only approximate models of these phenomena are available, we propose a flexible framework for time-varying adaptive filtering of seismic signals, using sparse representations, based on inaccurate templates. We recast the ...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Blind Source Separation by Entropy Rate Minimization
By assuming latent sources are statistically independent, independent component analysis separates underlying sources from a given linear mixture. Since in many applications, latent sources are both non-Gaussian and have sample dependence, it is desirable to exploit both properties jointly. In this paper, we use mutual information rate to construct a general framework for analysis and derivation of algorithms that take both properties into account. We discuss two types of source models for entropy rate estimation—a Markovian and an invertible filter model—and give the general independent component analysis co...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Likelihood Estimators for Dependent Samples and Their Application to Order Detection
Estimation of the dimension of the signal subspace, or order detection, is one of the key issues in many signal processing problems. Information theoretic criteria are widely used to estimate the order under the independently and identically distributed (i.i.d.) sampling assumption. However, in many applications, the i.i.d. sampling assumption does not hold. Previous approaches address the dependent sample issue by downsampling the data set so that existing order detection methods can be used. By discarding data, the sample size is decreased causing degradation in the accuracy of the order estimation. In this paper, we int...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Optimal Index Policies for Anomaly Localization in Resource-Constrained Cyber Systems
The objective is a probing strategy that minimizes the total expected cost, incurred by all the components during the detection process, under reliability constraints. We consider both independent and exclusive models. In the former, each component can be abnormal with a certain probability independent of other components. In the latter, one and only one component is abnormal. We develop optimal index policies under both models. The proposed index policies apply to a more general case where a subset (more than one) of the components can be probed simultaneously. The problem under study also finds applications in spectrum s...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Sparse Recovery of Streaming Signals Using $ell_1$-Homotopy
Most of the existing sparse-recovery methods assume a static system: the signal is a finite-length vector for which a fixed set of measurements and sparse representation are available and an $ell_1$ problem is solved for the reconstruction. However, the same representation and reconstruction framework is not readily applicable in a streaming system: the signal changes over time, and it is measured and reconstructed sequentially over small intervals. This is particularly desired when dividing signals into disjoint blocks and processing each block separately is infeasible or inefficient. In this paper, we discuss two streami...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Bayesian Estimation of Clean Speech Spectral Coefficients Given a Priori Knowledge of the Phase
While most short-time discrete Fourier transform-based single-channel speech enhancement algorithms only modify the noisy spectral amplitude, in recent years the interest in phase processing has increased in the field. The goal of this paper is twofold. First, we derive Bayesian probability density functions and estimators for the clean speech phase when different amounts of prior knowledge about the speech and noise amplitudes is given. Second, we derive a joint Bayesian estimator of the clean speech amplitudes and phases, when uncertain a priori knowledge on the phase is available. Instrumental measures predict that by i...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Sum-Rate Maximization for Active Channels With Unequal Subchannel Noise Powers
In this paper, an active channel, between a source and a destination, refers to a parallel channel where the source transmits power over different subchannels as well as the powers of the subchannels can be adjusted. We herein study the sum-rate maximization for an active channel subject to two constraints, one on the source total transmit power and one on the total channel power. Although this maximization is not convex, we use Karush–Kuhn–Tucker (KKT) conditions to develop a computationally efficient algorithm for optimal source and channel power allocation. To do so, we first show how KKT conditions can be...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Efficient Hardware Architecture for Sparse Coding
Sparse coding encodes natural stimuli using a small number of basis functions known as receptive fields. In this work, we design custom hardware architectures for efficient and high-performance implementations of a sparse coding algorithm called the sparse and independent local network (SAILnet). A study of the neuron spiking dynamics uncovers important design considerations involving the neural network size, target firing rate, and neuron update step size. Optimal tuning of these parameters keeps the neuron spikes sparse and random to achieve the best image fidelity. We investigate practical hardware architectures for SAI...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Ramanujan Sums in the Context of Signal Processing—Part II: FIR Representations and Applications
The mathematician Ramanujan introduced a summation in 1918, now known as the Ramanujan sum $c_q(n)$ . In a companion paper (Part I), properties of Ramanujan sums were reviewed, and Ramanujan subspaces ${cal S}_q$ introduced, of which the Ramanujan sum is a member. In this paper, the problem of representing finite duration (FIR) signals based on Ramanujan sums and spaces is considered. First, it is shown that the traditional way to solve for the expansion coefficients in the Ramanujan-sum expansion does not work in the FIR case. Two solutions are then developed. The first one is based on a linear combination of the first $N...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Ramanujan Sums in the Context of Signal Processing—Part I: Fundamentals
The famous mathematician S. Ramanujan introduced a summation in 1918, now known as the Ramanujan sum $c_q(n)$ . For any fixed integer $q$ , this is a sequence in $n$ with periodicity $q$ . Ramanujan showed that many standard arithmetic functions in the theory of numbers, such as Euler’s totient function $phi(n)$ and the Möbius function $mu (n)$, can be expressed as linear combinations of $c_q(n), 1 leq q leq infty$. In the last ten years, Ramanujan sums have aroused some interest in signal processing. There is evidence that these sums can be used to extract periodic components in discrete-time signals. The pu...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Multitask Diffusion Adaptation Over Networks
Adaptive networks are suitable for decentralized inference tasks. Recent works have intensively studied distributed optimization problems in the case where the nodes have to estimate a single optimum parameter vector collaboratively. However, there are many important applications that are multitask-oriented in the sense that there are multiple optimum parameter vectors to be inferred simultaneously, in a collaborative manner, over the area covered by the network. In this paper, we employ diffusion strategies to develop distributed algorithms that address multitask problems by minimizing an appropriate mean-square error cri...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research

Deep Scattering Spectrum
A scattering transform defines a locally translation invariant representation which is stable to time-warping deformation. It extends MFCC representations by computing modulation spectrum coefficients of multiple orders, through cascades of wavelet convolutions and modulus operators. Second-order scattering coefficients characterize transient phenomena such as attacks and amplitude modulation. A frequency transposition invariant representation is obtained by applying a scattering transform along log-frequency. State-the-of-art classification results are obtained for musical genre and phone classification on GTZAN and TIMIT...
Source: IEEE Transactions on Signal Processing - July 22, 2014 Category: Biomedical Engineering Source Type: research