Correction to: Efficient Hardware Architectures for 1D- and MD-LSTM Networks

Journal of Signal Processing Systems -     

Antibacterial action of chitosan

The antibacterial action of chitosan hydroglutamate (CH), chitosan lactate (CL) and chitosan derived from fungal mycelia was examined against both gram‐negative and gram‐positive bacteria. Plate counts indicated inactivation rates of one‐ to five‐log‐cycles within one hour. Fungal chitosan had significantly less antibiotic effect than CH and CL. The antibacterial action of CH and CL was very similar and shown to be concentration dependent with 0.1 mg/mL more effective than 2.0 and 5.0 mg/mL. When CH (or CL) and polygalacturonate were added to cell suspensions, death was prevented, possibly indicating that chitosan complexed with polygalacturonate could not penetrate the cell or disrupt the membrane. Leakage of intracellular components caused by chitosan was determined by exposing lactose‐induced Escherichia coli to chitosan with assay for ß‐galactosidase activity indicating that cell permeabilization occurred more extensively at the low chitosan concentrations. Microscopic examination showed that chitosan caused cell agglutination at pH 5.8. Injury to chitosan‐exposed Staphylococcus aureus MF‐31 could not be demonstrated using the criterion that sublethally stressed cells have increased sensitivity to high levels of sodium chloride.     

High field performance of thin-wall spacers in a vacuum gap

This paper reports the electrical conduction and breakdown characteristics of thin-wall ceramic spacers for a field emission display (FED). These spacers bridge two thin-film electrodes, which represent the FED cathode and the phosphor anode in a FED. Techniques to set up a high aspect-ratio thin-wall spacer without glue were developed. An extra-low light detection 3D-imaging system using an intensified CCD camera was developed which was able to identify the location of low-level light activity in the stressed vacuum-gap, indicative of imminent device failure. Thin wall spacers made of various ceramics were investigated extensively. The scanning electron microscopy (SEM) surface investigation showed that zirconia spacers exhibited a smoother surface morphology compared to all other materials studied; however, their breakdown voltages were rather low. The breakdown voltages of alumina spacers were severely limited by triple junction effects. At HV, breakdown at the edge of the thin-film electrode was observed. This edge breakdown can be used to explain the saturation of the breakdown voltage vs. vacuum gap spacing. The results of this work are highly encouraging in that an ~1000 μm tall spacer can support ~18 kV dc, at least 80% above the expected operational voltage of HV FED. The spacer breakdown voltage is expected to improve through surface treatment and elimination of the electrode edge-breakdown and triple junction effects     

Mechanical properties of vinylester/glass and polyester/glass composites fabricated by resin transfer molding and hand lay‐up

This paper reports the comparative performance of vinylester/glass and polyester/glass laminates fabricated by resin transfer molding (RTM) and hand lay‐up. A resin transfer mold was designed and fabricated for preparing the laminates. Void content was much lower in Spartan II RTM specimens than in that of hand lay‐up. Ultimate tensile strength, Young's modulus, flexural strength, flexural modulus, impact strength, and interlaminar shear strength of RTM specimens were superior to that of the hand lay‐up for both vinylester/glass and polyester/glass. The improvements for vinylester/glass were 44%, 28%, 88%, 84%, 36%, and 78% for the respective properties. The corresponding improvements for polyester/glass were 21%, 52%, 70%, 74%, 57%, and 82%, respectively. Particle impact erosion rate was lower in RTM specimens than that of the hand lay‐up. J. VINYL ADDIT. TECHNOL. 21:166–173, 2015. © 2014 Society of Plastics Engineers     

Role of energy transfer,defect, and lattice dimension in photophysical characteristics of AWO4:Nd3+ (A=Ca,Sr and Ba)

The fact that the scheelite based compounds are of high technological importance in the area of scintillator and optoelectronics, makes their detailed photophysical study relevant not only for fundamental material science but also in tailoring their optical properties for advanced applications. With this view, we have carried out a very systematic study on near infra-red (NIR) emitting Nd³⁺ doped CaWO₄, SrWO₄, and BaWO₄ compounds. Light emitting efficiency in AWO4:Nd³⁺ is governed strongly by radiative/nonradiative properties, host-dopant energy transfer (HDET) efficiency and defect density. We have used photoluminescence, positron annihilation, and photoacoustic (PA) spectroscopy to study the factors effecting light emission. These scheelites are known to exhibit self activated luminescence in visible region due to charge transfer within the tungstate group and wavelength maxima exhibited red shift as we move from Ca→Sr→Ba. This can provide a new strategy to achieve spectral tunability in AWO₄ scheelite by changing A²⁺ ionic radius. The fractional intensity in the green region is least in the case of SrWO₄ samples suggesting that the oxygen vacancy density is minimal in case of SrWO₄ which is well-supported by the positron annihilation lifetime spectroscopy (PALS). Based on our studies, we found that the HDET was highly efficient in CaWO₄:Nd³⁺ and minimal in BaWO₄:Nd³⁺ which get's reflected in photoluminescence intensity. Emission lifetimes are shorter in CaWO₄ and highest in SrWO₄ host which are in sync with positron annihilation lifetime values. Based on our results of PALS, it was found that CaWO₄:Nd³⁺ has the highest concentration of defects i.e. cation vacancies; so larger is the probability of nonradiative signals and hence higher PA intensity from it.     

Object-Oriented Framework for Genetic Algorithms with Application to Space Truss Optimization

Genetic algorithms have been shown to be very effective optimization tools for a number of engineering problems. Since the genetic processes typically operate independent of the actual problem, a core genetic algorithm library consisting of all the genetic operators having an interface to a generic objective function can serve as a very useful tool for learning as well as for solving a number of practical optimization problems. This paper discusses the object-oriented design and implementation of such a core library. Object-oriented design, apart from giving a more natural representation of information, also facilitates better memory management and code reusability. Next, it is shown how classes derived from the implemented libraries can be used for the practical size optimization of large space trusses, where several constructibility aspects have been incorporated to simulate real-world design constraints. Strategies are discussed to model the chromosome and to code genetic operators to handle such constraints. Strategies are also suggested for member grouping for reducing the problem size and implementing move-limit concepts for reducing the search space adaptively in a phased manner. The implemented libraries are tested on a number of large previously fabricated space trusses, and the results are compared with previously reported values. It is concluded that genetic algorithms implemented using efficient and flexible data structures can serve as a very useful tool in engineering design and optimization.     

Application of empirical mode decomposition (EMD) for automated identification of congestive heart failure using heart rate signals

Electrocardiogram is widely used to diagnose the congestive heart failure (CHF). It is the primary noninvasive diagnostic tool that can guide in the management and follow-up of patients with CHF. Heart rate variability (HRV) signals which are nonlinear in nature possess the hidden signatures of various cardiac diseases. Therefore, this paper proposes a nonlinear methodology, empirical mode decomposition (EMD), for an automated identification and classification of normal and CHF using HRV signals. In this work, HRV signals are subjected to EMD to obtain intrinsic mode functions (IMFs). From these IMFs, thirteen nonlinear features such as approximate entropy \( (E_{\text{ap}}^{x} ) \), sample entropy \( (E_{\text{s}}^{x} ) \), Tsallis entropy \( (E_{\text{ts}}^{x} ) \), fuzzy entropy \( (E_{\text{f}}^{x} ) \), Kolmogorov Sinai entropy \( (E_{\text{ks}}^{x} ) \), modified multiscale entropy \( (E_{{{\text{mms}}_{y} }}^{x} ) \), permutation entropy \( (E_{\text{p}}^{x} ) \), Renyi entropy \( (E_{\text{r}}^{x} ) \), Shannon entropy \( (E_{\text{sh}}^{x} ) \), wavelet entropy \( (E_{\text{w}}^{x} ) \), signal activity \( (S_{\text{a}}^{x} ) \), Hjorth mobility \( (H_{\text{m}}^{x} ) \), and Hjorth complexity \( (H_{\text{c}}^{x} ) \) are extracted. Then, different ranking methods are used to rank these extracted features, and later, probabilistic neural network and support vector machine are used for differentiating the highly ranked nonlinear features into normal and CHF classes. We have obtained an accuracy, sensitivity, and specificity of 97.64, 97.01, and 98.24 %, respectively, in identifying the CHF. The proposed automated technique is able to identify the person having CHF alarming (alerting) the clinicians to respond quickly with proper treatment action. Thus, this method may act as a valuable tool for increasing the survival rate of many cardiac patients.

     

The Nonlinearly Viscoelastic Response of a Wood-Thermoplastic Composite

This study considers the time-dependent response of a woodthermoplastic composite. The extruded material under considerationconsists of wood flour embedded in a high-density polyethylene (HDPE)matrix. The characterization study is based on a series of creep andrecovery tests. Stiffness reduction (i.e. damage) and permanentdeformation was observed in the material when the creep stress amplitudeexceeded a threshold value. The damage and permanent strains were foundto depend on creep stress amplitude and duration. The permanentdeformation was more efficiently accommodated by considering the coupontotal strain, however. A nonlinearly viscoelastic model is presentedthat incorporates damage and permanent deformation effects. Damage wasmodeled by considering an effective stress. The model is shown tocompare favorably with the experimental creep/recovery data as well astwo-step load history verification tests.     

Effect of hydrogen charging on the torsional fatigue behaviour of 2024 aluminium

Torsional fatigue tests have been carried out on overaged and hydrogen charged specimens of 2024 aluminium in gaseous hydrogen and humid air. Hydrogen charging was found to significantly increase the number of fatigue crack initiation sites compared with uncharged specimens tested in argon, resulting in an overall reduction in fatigue life. Fatigue testing in gaseous hydrogen and humid air influenced both initiation and propagation of cracks. The fracture sites of both charged and uncharged specimens were similar, and the fracture mode was predominantly tensile in all specimens. However, specimens tested in humid air showed small amounts of longitudinal and transverse fracture, with ≈5% shear at low humidity and 10% at high humidity.