Segmentation of brain MRI using active contour model

Alzheimer disease is a neurodegenerative disorder that impairs memory, cognitive function, and gradually leads to dementia, physical deterioration, loss of independence, and death of the affected individual. In this context, segmentation of medical images is a very important technique in the field of image analysis and Computer‐Assisted Diagnosis. In this article, we introduce a new automatic method of brain images’ segmentation based on the Active Contour (AC) model to extract the Hippocampus and the Corpus Callosum (CC). Our contribution is to combine the geometric method with the statistical method of the AC. We used the Caselle Level Set and added a learning phase to build an average shape and to make the initialization task automatic. For the step of contour evolution, we used the principle of Level set and we added to it the a priori knowledge. Experimental results are very promising. © 2017 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 27, 3–11, 2017     

Stimulated Transitions of Directed Nonequilibrium Self‐Assemblies

Near‐equilibrium stimulus‐responsive polymers have been used extensively to introduce morphological variations in dependence of adaptable conditions. Far‐less‐well studied are triggered transformations at constant conditions. These require the involvement of metastable states, which are either able to approach the equilibrium state after deviation from metastability or can be frozen on returning from nonequilibrium to equilibrium. Such functional nonequilibrium macromolecular systems hold great promise for on‐demand transformations, which result in substantial changes in their material properties, as seen for triggered gelations. Herein, a diblock copolymer system consisting of a hydrophilic block and a block that is responsive to both pressure and temperature, is introduced. This species demonstrates various micellar transformations upon leaving equilibrium/nonequilibrium states, which are triggered by a temperature deflection or a temporary application of hydrostatic pressure.     

Miniaturized on‐body antenna for small and wearable brain microwave imaging systems

A miniaturized inset‐fed on‐body meandered bowtie antenna designed for brain microwave imaging systems is presented in this article. The proposed on‐body antenna can contribute to the realization of a wearable and portable brain microwave imaging system. The size of 18 × 18 mm² is achieved at a frequency range of 0.75 to 4 GHz by the simultaneous use of self‐complementary structures and meandered lines. The frequency band is a trade‐off between penetration depth and spatial resolution. The proposed antenna performance was studied at different positions on the human head voxel model in terms of several parameters such as reflection coefficient, near‐field directivity, and fidelity factor. In addition, the antenna bandwidth was surveyed on several volunteers using a wearable measurement setup. It has been found that the averages of measured reflection coefficients in different scenarios are in good agreement with the corresponding simulation results, and the antenna shows stable performance under different practical situations. The proposed antenna takes advantage of a small footprint and body matching, which make it an eligible choice for compact, portable, and wearable head microwave imaging systems.     

Elderly fall detection based on multi-stream deep convolutional networks

Multimedia Tools and Applications - Fall is the biggest threat to seniors, with significant emotional, physical and financial implications. It is the major cause of serious injuries, disabilities,...     

Miniaturized substrate integrated waveguide filter using fractal open complementary split‐ring resonators

A miniaturized substrate integrated waveguide (SIW) bandpass filter using fractal open complementary split‐ring resonators (FOCSRRs) unit‐cell is proposed. The proposed structure is realized by etching the proposed FOCSRR unit‐cells on the top metal surface of the SIW structure. The working principle of the proposed filter is based on the evanescent‐mode propagation. The proposed FOCSRRs behave as an electric dipoles in condition of the appropriate stimulation, which are able to generate a forward‐wave passband region below the cutoff frequency of the waveguide structure. Since, the electrical size of the proposed FOCSRRs unit‐cell is larger than the conventional OCSRRs unit‐cell; therefore, the FOCSRR unit‐cell is a good candidate to miniaturize the SIW structure. The proposed filter represents high selectivity and compact size because of the utilization of the sub‐wavelength resonators. The introduced filter is simulated by a 3D electromagnetic simulator. In order to validate the ability of the proposed topology in size reduction, 1‐ and 2‐stage of the proposed filters have been fabricated based on the standard printed circuit board process. The measured S‐parameters of the fabricated filters are in a good agreement with the simulated ones. The proposed SIW filters have many advantages in term of compact size, low insertion loss, high return loss, easy fabrication and integration with other circuits. It is the first time that the FOCSRR unit‐cells were combined with the SIW structure for miniaturization of this structure. Furthermore, a wide upper‐stopband with the attenuation >20 dB in the range of 3–8 GHz is achieved. The results show that, a miniaturization factor about 75.5% has been obtained.     

Performance Analysis in Digital Circuits for Process Corner Variations,Slew-Rate and Load Capacitance

The aggressive scaling of CMOS technology has inevitably led to vastly increased power dissipation, process variability and reliability degradation, posing tremendous challenges to robust circuit design. To continue the success of integrated circuits, advanced design research must start in parallel with or even ahead of technology development. In this paper, an attempt is made to analyze various circuits’ delay and power performance by introducing certain level of variation to important process parameters like threshold voltage (V_th), mobility of carriers (μ₀), oxide thickness (t_ox) and doping concentration (n_sd). Basic Monte Carlo simulation is carried out on these circuits to ascertain the stability in performances. A 16 × 1 multiplexer is considered for detailed analysis. SPICE characterization is done for three different input slew rates (0.1, 0.5 and 1 ns) against four different output load drive strengths (1×, 2×, 3× and 4× output capacitive load). From the obtained results, output slew rates and average power results are observed and discussed.     

Electrochemical characterization of laser‐carbonized polyacrylonitrile nanofiber nonwovens

Porous carbon materials represent prospective materials for absorbers, filters, and electronic applications. Carbon fibers with high surface areas can be produced from polyacrylonitrile and spun as thin fibers from solution. The resulting polymer fibers are first stabilized to obtain conjugated ribbons and then carbonized to graphitic structures in a second high‐temperature step in an inert atmosphere. In this study, we investigated a previously described fast laser‐heating process that delivered fibers with a higher crystallinity and surface area compared to the thermally carbonized fibers. In a subsequent KOH‐activation step, the crystalline domains were exfoliated, and the surface of the fibers became macroporous. This led to a reduced specific surface area but a higher capacitance compared to thermally carbonized nanofibers. We report the electrochemical properties of the electrochemical cells and discuss their potential applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46398.     

Synthesis and Characterization of Anti-fungus,Anti-corrosion and Self-cleaning Hybrid Nanocomposite Coatings Based on Sol–Gel Process

Anti-corrosion, anti-fungus, and self-cleaning properties of coatings containing ZnO–TiO₂, SiO₂–TiO₂ and SiO₂/TiO₂/ZnO nanoparticles synthesized based on sol–gel precursors using tetra methoxysilane, 3-glycidoxypropyl trimethoxysilane, tetra (n-butyl orthotitanate) and zinc acetate dihydrate were investigated by FESEM, EDAX and TEM analyses. Results indicated uniform dispersion of inorganic nanoparticles in the range of 20–40 nm in size. Anti-corrosion property of the hybrid coating was characterized by EIS measurements and parametrically analyzed in an equivalent circuit when the coating was exposed to salt solution. Results showed that, ZnO and TiO₂ nanoparticles enhance anti-corrosion property of the hybrid coatings. Anti-fungus and anti-bacterial properties of the coatings were determined by diameter of inhibition zone and inhabitation of bacterial growth, respectively. The coating containing ZnO and TiO₂ nanoparticles showed anti-fungus and anti-bacterial properties which were related to their photocatalytic properties. Degradation of methylene blue in aqueous solution was determined by UV–Visible tests which indicated self-cleaning property of the coatings containing ZnO and TiO₂ nanoparticles.     

Assessment of contaminant diffusivities in building materials from porosimetry tests

Recent studies have shown that surface and gaseous contaminant interactions may play an important role in indoor air quality. Modeling is an important tool to improve our knowledge about the phenomena involved and define appropriate ventilation strategies. However, data for sorption isotherms and diffusion in building materials remain woefully lacking. This paper deals with the latter point. It aims at investigating a methodology based on an analysis of the material porosity first and then the application of Carniglia's mathematical model to determine the effective diffusivity of gaseous species in building materials. This methodology, whose main principles are presented in the first part of the paper, was applied to seven commonly found materials. Mercury intrusion porosimetry (MIP) tests, and the calculations using Carniglia's model, reveal typical total porosities and tortuosity factors for these materials. The analysis of pore size distributions (PSDs) also draws one's attention to the possible differences in the pore structures that may exist between two samples of the same type of material and the differences in the effective diffusivities of contaminants that may result from them. The computed effective diffusivities were subsequently compared to data from experiments carried out in the frame of the EC project MATHIS. An agreement was obtained, thus validating Carniglia's methodology - a methodology that offers many practical advantages compared to diffusion-cell methods.     

Characterization of a near-infrared laparoscopic hyperspectral imaging system for minimally invasive surgery

We developed and characterized a new imaging platform for minimally invasive surgical venues, specifically a system to help guide laparoscopic surgeons to visualize biliary anatomy. This platform is a novel combination of a near-infrared hyperspectral imaging system coupled with a conventional surgical laparoscope. Intraoperative tissues are illuminated by optical fibers arranged in a ring around a center-mounted relay lens collecting back-reflected light from tissues to the hyperspectral imaging system. The system consists of a focal plane array (FPA) and a liquid crystal tunable filter, which is continuously tunable in the near-infrared spectral range of 650-1100 nm with the capability of passing light with a mean bandwidth of 6.95 nm, and the FPA is a high-sensitivity back-illuminated, deep depleted charge-coupled device. Placing a standard resolution target 5.1 cm from the distal end of the laparoscope, a typical intraoperative working distance, produced a 7.6-cm-diameter field of view with an optimal spatial resolution of 0.24 mm. In addition, the system's spatial and spectral resolution and its wavelength tuning accuracy are characterized. The spectroscopic images are formatted into a three-dimensional hyperspectral image cube and processed using principle component analysis. The processed images provide contrast based on measured spectra associated with chemically different anatomical structures helping identify the main molecular chromophores inherent to each tissue. The principal component images were found to image swine gallbladder and biliary structures from surrounding tissues, in real time, during cholecystectomy surgery. Furthermore, it is shown that surgeons can interrogate selected image subregions for their molecular composition identifying biliary anatomy during surgery and before any invasive action is undertaken.