Parametric Methods for the Regional Assessment of Cardiac Wall Motion Abnormalities: Comparison Study

Left ventricular(LV)dysfunction is mainly assessed by global contractile indices such as ejection fraction and LV Volumes in cardiac MRI.While these indices give information about the presence or not of LV alteration,they are not able to identify the location and the size of such alteration.The aim of this study is to compare the performance of three parametric imaging techniques used in cardiac MRI for the regional quantification of cardiac dysfunction.The proposed approaches were evaluated on 20 patients with myocardial infarction and 20 subjects with normal function.Three parametric images approaches:covariance analysis,parametric images based on Hilbert transform and those based on the monogenic signal were evaluated using cine-MRI frames acquired in three planes of views.The results show that parametric images generated from the monogenic signal were superior in term of sensitivity(89.69%),specificity(86.51%)and accuracy(89.06%)to those based on covariance analysis and Hilbert transform in the detection of contractile dysfunction related to myocardial infarction.Therefore,the parametric image based on the monogenic signal is likely to provide additional regional indices about LV dysfunction and it may be used in clinical practice as a tool for the analysis of the myocardial alterations.

An Efficient Text Recognition System from Complex Color Image for Helping the Visually Impaired Persons

The challenge faced by the visually impaired persons in their day-today lives is to interpret text from documents.In this context,to help these people,the objective of this work is to develop an efficient text recognition system that allows the isolation,the extraction,and the recognition of text in the case of documents having a textured background,a degraded aspect of colors,and of poor quality,and to synthesize it into speech.This system basically consists of three algorithms:a text localization and detection algorithm based on mathematical morphology method(MMM);a text extraction algorithm based on the gamma correction method(GCM);and an optical character recognition(OCR)algorithm for text recognition.A detailed complexity study of the different blocks of this text recognition system has been realized.Following this study,an acceleration of the GCM algorithm(AGCM)is proposed.The AGCM algorithm has reduced the complexity in the text recognition system by 70%and kept the same quality of text recognition as that of the original method.To assist visually impaired persons,a graphical interface of the entire text recognition chain has been developed,allowing the capture of images from a camera,rapid and intuitive visualization of the recognized text from this image,and text-to-speech synthesis.Our text recognition system provides an improvement of 6.8%for the recognition rate and 7.6%for the F-measure relative to GCM and AGCM algorithms.

An Efficient HW/SW Design for Text Extraction from Complex Color Image

In the context of constructing an embedded system to help visually impaired people to interpret text,in this paper,an efficient High-level synthesis(HLS)Hardware/Software(HW/SW)design for text extraction using the Gamma Correction Method(GCM)is proposed.Indeed,the GCM is a common method used to extract text from a complex color image and video.The purpose of this work is to study the complexity of the GCM method on Xilinx ZCU102 FPGA board and to propose a HW implementation as Intellectual Property(IP)block of the critical blocks in this method using HLS flow with taking account the quality of the text extraction.This IP is integrated and connected to the ARM Cortex-A53 as coprocessor in HW/SW codesign context.The experimental results show that theHLS HW/SW implementation of the GCM method on ZCU102 FPGA board allows a reduction in processing time by about 89%compared to the SW implementation.This result is given for the same potency and strength of SW implementation for the text extraction.

Reactive Power Reserve Improvement Using Power Systems Inherent Structural Characteristics

This paper considers the use of the inherent structural characteristics of power system networks for improving the reactive power reserve margins for both topologically weak and strong networks. The inherent structural characteristics of the network are derived from the Schur complement of the partitioned Y-admittance matrix using circuit theory representations. Results show that topologically strong networks, operating close to the upper voltage limit could be made to increase their loadability margin by locating reactive power compensators close to generator sources, whereas topologically weak (ill conditioned) networks could be made to operate within the feasible operating limits by locating reactive power compensators on buses farther from generator sources.

On-chip parallel Fourier transform spectrometer for broadband selective infrared spectral sensing

Optical spectrometers enable contactless chemical analysis.However,decreasing both their size and cost appears to be a prerequisite to their widespread deployment.Chip-scale implementation of optical spectrometers still requires tackling two main challenges.First,operation over a broad spectral range extending to the infrared is required to enable covering the molecular absorption spectrum of a broad variety of materials.This is addressed in our work with an Micro-Electro Mechanical Systems(MEMS)-based Fourier transform infrared spectrometer with an embedded movable micro-mirror on a silicon chip.Second,fine spectral resolutionΔλis also required to facilitate screening over several chemicals.A fundamental limit states thatΔλis inversely proportional to the mirror motion range,which cannot exceed the chip size.To boost the spectral resolution beyond this limit,we propose the concept of parallel(or multi-core)FTIR,where multiple interferometers provide complementary optical paths using the same actuator and within the same chip.The concept scalability is validated with 4 interferometers,leading to approximately 3 times better spectral resolution.After the atmospheric contents of a greenhouse gas are monitored,the methane absorption bands are successfully measured and discriminated using the presented device.

A power supply module for autonomous portable electronics:ultralow-frequency MEMS electrostatic kinetic energy harvester with a comb structure reducing air damping

A MEMS electrostatic kinetic energy harvester(e-KEH)of about 1 cm2,working at ultralow frequency(1–20 Hz),without any supported additional mass on its mobile electrode,and working even without a vacuum environment is reported.The prototype is especially suitable for environments with abundant low frequency motions such as wearable electronics.The proposed e-KEH consists of a capacitor with a finger-teeth interdigited comb structure.This greatly reduces the air damping effect,and thus the capacitance variation remains important regardless of the presence of air.With the new design,the energy transduced per cycle of excitation is no less than 33 times higher than the classic design within 10–40 Hz/2 g_(peak),while is 85 times higher at 15 Hz/2 g_(peak).An enclosed miniature ball combined with non-linear stoppers enables the oscillation of the movable electrode through impact-based frequency up-conversion mechanism,which is also improved by the low air damping.Thanks to this new design,a higher efficiency than the classic gap-closing comb structure is obtained,as a larger range of working frequency(1–180 Hz)in air.A maximum energy conversion of 450 nJ/cycle is obtained with a bias voltage of 45 V and an acceleration of 11 Hz,3 g_(peak).Working with a diode AC-DC rectifier,the proposed KEH is able to support up to 3 RFID communications within 16 s while operated at 11 Hz,3 g_(peak).

Silicon micromirrors with three-dimensional curvature enabling lensless efficient coupling of free-space light

Miniaturized optical benches process free-space light propagating in-plane with respect to the substrate and have a large variety of applications,including the coupling of light through an optical fiber.High coupling efficiency is usually obtained using assembled micro-optical parts,which considerably increase the system cost and integration effort.In this work,we report a high coupling efficiency,monolithically integrated silicon micromirror with controlled three-dimensional(3D)curvature that is capable of manipulating optical beams propagating in the plane of the silicon substrate.Based on our theoretical modeling,a spherical micromirror with a microscale radius of curvature as small as twice the Gaussian beam Rayleigh range provides a 100%coupling efficiency over a relatively long optical path range.Introducing dimensionless parameters facilitates the elucidation of the role of key design parameters,including the mirror’s radii of curvature,independent of the wavelength.A micromachining method is presented for fabricating the 3D micromirror using fluorinated gas plasmas.The measured coupling efficiency was greater than 50%over a 200-mm optical path,compared to less than 10%afforded by a conventional flat micromirror,which was in good agreement with the model.Using the 3D micromirror,an optical cavity was formed with a round-trip diffraction loss of less than 0.4%,resulting in one order of magnitude enhancement in the measured quality factor.A nearly 100%coupling was also estimated when matching the sagittal and tangential radii of curvature of the presented micromirror’s surface.The reported class of 3D micromirrors may be an advantageous replacement for the optical lenses usually assembled in silicon photonics and optical benches by transforming them into real 3D monolithic systems while achieving wideband high coupling efficiency over submillimeter distances.

Spatiotemporal dynamics of nanowire growth in a microfluidic reactor

Co-integration of nanomaterials into microdevices poses several technological challenges and presents numerous scientific opportunities that have been addressed in this paper by integrating zinc oxide nanowires(ZnO-NWs)into a microfluidic chamber.In addition to the applications of these combined materials,this work focuses on the study of the growth dynamics and uniformity of nanomaterials in a tiny microfluidic reactor environment.A unique experimental platform was built through the integration of a noninvasive optical charaaerization technique with the microfluidic reactor.This platform allowed the unprecedented demonstration of time-resolved and spatially resolved monitoring of the in situ growth of NWs,in which the chemicals were continuously fed into the microfluidic reactor.The platform was also used to assess the uniformity of NWs grown quickly in a 10-mm-wide microchamber,which was intentionally chosen to be 20 times wider than those used in previous attempts because it can accommodate applications requiring a large surface of interaction while still taking advantage of submillimeter height.Further observations included the effects of varying the flow rate on the NW diameter and length in addition to a synergetic effect of continuous renewal of the growth solution and the confined environment of the chemical reaction.