Scielo RSS <![CDATA[Brazilian Archives of Biology and Technology]]> vol. 59 num. SPE2 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[EDITORIAL]]> <![CDATA[Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach]]> ABSTRACT Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π - bridge, donor group and LUMO are localized on π - bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π - bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π-bridge display an enhanced optoelectronic properties than with less π - bridge. <![CDATA[Investigation of Structural, Morphological, Magnetic Properties and Biomedical applications of Cu<sup>2+</sup> Substituted Uncoated Cobalt Ferrite Nanoparticles]]> ABSTRACT In the present work, Cu2+ substituted cobalt ferrite (Co1-xCuxFe2O4, x = 0, 0.3, 0.5, 0.7 and 1) magnetic nanopowders were synthesized via chemical co-precipitation method. The prepared powders were investigated by various characterization methods such as X-ray diffraction analysis (XRD), scanning electron microscope analysis (SEM), vibrating sample magnetometer analysis (VSM) and fourier transform infrared spectroscopy analysis (FTIR). The XRD analysis reveals that the synthesized nanopowders possess single phase centred cubic spinel structure. The average crystallite size of the particles ranging from 27-49 nm was calculated by using Debye-scherrer formula. Magnetic properties of the synthesized magnetic nanoparticles are studied by using VSM. The VSM results shows the magnetic properties such as coercivity, magnetic retentivity decreases with increase in copper substitution whereas the saturation magnetization shows increment and decrement in accordance with Cu2+ substitution in cobalt ferrite nanoparticles. SEM analysis reveals the morphology of synthesized magnetic nanoparticles. FTIR spectra of Cu2+ substituted cobalt ferrite magnetic nanoparticles were recorded in the frequency range 4000-400cm-1. The spectrum shows the presence of water adsorption and metal oxygen bonds. The adhesion nature of Cu2+ substituted cobalt ferrite magnetic nanoparticles with bacteria in reviewed results indicates that the synthesized nanoparticles could be used in biotechnology and biomedical applications. <![CDATA[Classification of Flying Insects with high performance using improved DTW algorithm based on hidden Markov model]]> ABSTRACT Insects play significant role in the human life. And insects pollinate major food crops consumed in the world. Insect pests consume and destroy major crops in the world. Hence to have control over the disease and pests, researches are going on in the area of entomology using chemical, biological and mechanical approaches. The data relevant to the flying insects often changes over time, and classification of such data is a central issue. And such time series mining tasks along with classification is critical nowadays. Most time series data mining algorithms use similarity search and hence time taken for similarity search is the bottleneck and it does not produce accurate results and also produces very poor performance. In this paper, a novel classification method that is based on the dynamic time warping (DTW) algorithm is proposed. The dynamic time warping algorithm is deterministic and lacks in modeling stochastic signals. The dynamic time warping (DTW) algorithm is improved by implementing a nonlinear median filtering (NMF). Recognition accuracy of conventional DTW algorithms is less than that of the hidden Markov model (HMM) by same voice activity detection (VAD) and noise-reduction. With running spectrum filtering (RSF) and dynamic range adjustment (DRA). NMF seek the median distance of every reference of time series data and the recognition accuracy is much improved. In this research work, optical sensors are used to record the sound of insect flight, with invariance to interference from ambient sounds. The implementation of our tool includes two parts, an optical sensor to record the "sound" of insect flight, and a software that leverages on the sensor information, to automatically detect and identify flying insects. <![CDATA[An Efficient Human Identification through MultiModal Biometric System]]> ABSTRACT Human identification is essential for proper functioning of society. Human identification through multimodal biometrics is becoming an emerging trend, and one of the reasons is to improve recognition accuracy. Unimodal biometric systems are affected by various problemssuch as noisy sensor data,non-universality, lack of individuality, lack of invariant representation and susceptibility to circumvention.A unimodal system has limited accuracy. Hence, Multimodal biometric systems by combining more than one biometric feature in different levels are proposed in order to enhance the performance of the system. A supervisor module combines the different opinions or decisions delivered by each subsystem and then make a final decision. In this paper, a multimodal biometrics authentication is proposed by combining face, iris and finger features. Biometric features are extracted by Local Derivative Ternary Pattern (LDTP) in Contourlet domain and an extensive evaluation of LDTP is done using Support Vector Machine and Nearest Neighborhood Classifier. The experimental evaluations are performed on a public dataset demonstrating the accuracy of the proposed system compared with the existing systems. It is observed that, the combination of face, fingerprint and iris gives better performance in terms of accuracy, False Acceptance Rate, False Rejection Rate with minimum computation time. <![CDATA[Effect of Preheating on Microstructure and Tensile Properties of Friction Stir Welded AA7075 Aluminium Alloy Joints]]> ABSTRACT The high strength AA7075 aluminum alloy is commonly used in the aerospace components due to its exclusive mechanical properties like lightweight and high strength. This alloy cannot be welded by fusion welding techniques due to solidification cracking which severely degrade the mechanical properties of the joint. In contrast, through friction stir welding (FSW) process solidification relate defects can be eliminated. Anyhow, the strength of friction stir welded joint is influenced by process parameters and tool parameters. These parameters govern the heat input, metal flow, microstructure evolution and mechanical properties of the weld. In normal welding condition, (without preheating) heat is generated by friction force which is produced between tool and workpiece. In this paper an added heat input through preheating the metal before weld. This preheating temperature effects on microstructure, microhardness and tensile properties of the joints were investigated. From this study the following conclusions are derived. Sufficient heat input should be given to obtain defect free and quality joint. The results showed that, preheating the base metal to 100 °C prior to welding improved the tensile strength and joint efficiency compared to the joints made without preheating. <![CDATA[An Empirical Evaluation of the Local Texture Description Framework-Based Modified Local Directional Number Pattern with Various Classifiers for Face Recognition]]> ABSTRACT Texture is one of the chief characteristics of an image. In recent years, local texture descriptors have garnered attention among researchers in describing effective texture patterns to demarcate facial images. A feature descriptor titled Local Texture Description Framework-based Modified Local Directional Number pattern (LTDF_MLDN), capable of encoding texture patterns with pixels that lie at dissimilar regions, has been proposed recently to describe effective features for face images. However, the role of the descriptor can differ with different classifiers and distance metrics for diverse issues in face recognition. Hence, in this paper, an extensive evaluation of the LTDF_MLDN is carried out with an Extreme Learning Machine (ELM), a Support Vector Machine (SVM) and a Nearest Neighborhood Classifier (NNC) which uses Euclidian, Manhattan, Minkowski, G-statistics and chi-square dissimilarity metrics to illustrate differences in performance with respect to assorted issues in face recognition using six benchmark databases. Experimental results depict that the proposed descriptor is best suited with NNC for general case and expression variation, whereas, for the other facial variations ELM is found to produce better results. <![CDATA[An Efficient Watermarking Scheme for Medical Data Security With the Aid of Neural Network]]> ABSTRACT Digital watermarking has emerged as major technique for ensuring security for various types of data like medical data, digital copyright protection, transaction tracing and so on. With the advancement in digital data distribution over the network there has been increase in the need for protection of such data from unauthorized copying or usages. Watermarking helps in providing the security to some extent. Robustness against any sort of unauthenticated attack is the major requirement of watermarking. In this paper we proposed an efficient watermarking technique for medical data security with the aid of neural network. Usage of neural network is generally used to create and control watermarking strength automatically. This method provides better watermarked data which can be highly secured to unauthorized usage. It is observed that the proposed method provides better security for the multimedia data when compared with other data security methods. <![CDATA[Structural Behavior of SFRC Beams strengthened with GFRP Laminates: An Experimental and Analytical Investigation]]> ABSTRACT This paper presents the experimental results of a reinforced concrete beams (RC) strengthened with internal steel fibers (SF) and external glass fiber reinforced polymer laminates (GFRP). The research work studied the load carrying capacity, deformation, crack width and ductility of the reinforced concrete beams strengthened with different steel fiber ratios and steel fiber reinforced concrete beams strengthened with three different glass fiber reinforced polymer laminates of two different thickness. The experimental results clearly shows that incorporating steel fibers in to the reinforced concrete beams reduced the crack width and distribute the crack evenly and also increases the bonding between tension face of the beam with glass fiber reinforced polymer laminates. The results also shows that glass fiber reinforced polymer laminates strengthened steel fiber reinforced concrete beams increases the flexural strength and ductility as compared with unstrengthened counterpart. In addition to this experimental work, theoretical calculations were done to find the ultimate load carrying capacity of the beam tested, and also compared with the experimental results. <![CDATA[Feature Level Two -Dimensional Arrays Based Fusion in the Personal Authentication system using Physiological Biometric traits]]> ABSTRACT The fingerprint, knuckle print and the retina are used to authenticate a person accurately because of the permanence in the features. These three biometric traits are fused for better security. The fingerprint and knuckle print images are pre-processed by morphological techniques and the features are extracted from the normalized image using gabor filter. The retinal image is converted to gray image and pre-processing is done using top hat and bottom hat filtering. Blood vessels are segmented and the features are extracted by locating the optic disk as the centre point. The extracted features from the fingerprint, knuckle print and the retina are fused together as one template and stored in the data base for authentication purpose, thus reducing the space and time complexity. <![CDATA[Energy Efficient Clustering in Multi-hop Wireless Sensor Networks Using Differential Evolutionary MOPSO]]> ABSTRACT The primary challenge in organizing sensor networks is energy efficacy. This requisite for energy efficacy is because sensor nodes capacities are limited and replacing them is not viable. This restriction further decreases network lifetime. Node lifetime varies depending on the requisites expected of its battery. Hence, primary element in constructing sensor networks is resilience to deal with decreasing lifetime of all sensor nodes. Various network infrastructures as well as their routing protocols for reduction of power utilization as well as to prolong network lifetime are studied. After analysis, it is observed that network constructions that depend on clustering are the most effective methods in terms of power utilization. Clustering divides networks into inter-related clusters such that every cluster has several sensor nodes with a Cluster Head (CH) at its head. Sensor gathered information is transmitted to data processing centers through CH hierarchy in clustered environments. The current study utilizes Multi-Objective Particle Swarm Optimization (MOPSO)-Differential Evolution (DE) (MOPSO-DE) technique for optimizing clustering. <![CDATA[Ananalysis on Runtime Associated QOS-Based Proficient Web Services Discovery Optimization]]> ABSTRACT In today's web world, Service-oriented architectures represent the main standard for IT infrastructures. Certainly, with the initiation of service oriented architecture, Web services have gained incredible growth. Web service discovery has become increasingly more significant as the existing use of web service. Discovering most appropriate web service from vast collection of web services is very decisive for successful execution of applications. In automation of web service discovery, there is always a need to deem Quality of Service (QoS) attributes during matching. A study of literature concerning the evolution of different web service discovery optimization methods with unique prominence to quality motivated service discovery have been carried out in this work. This paper depicts Bio-inspired algorithms optimizing the discovery process for semantic web services. Bio-inspired algorithm is a metaheuristics method that mimics the nature in order to unravel optimization difficulty and evaluates the analysis of some popular bio-inspired optimization algorithm systematically. This paper also focused on the principle of each algorithm and their application with respect to run time oriented QoSattributes and from result the best suitable bio-inspired optimization algorithm is been deployed. <![CDATA[Green Energy Generation Using FLC Based WECS With Lithium Ion Polymer Batteries]]> ABSTRACT Green Energy Generation Using Wind energy conversion system is achieved using Lithium Ion Polymer Batteries and Fuzzy logic controller. Presented scheme also provides the constant output power for the stand alone loads like Island, Hills Stations, Ships and Remote locations etc. A fuzzy-logic controller based Wind energy conversion system with permanent magnet synchronous machine is simulated using MATLAB Simulink. The controller provides the constant output voltage in Buck Boost Converter with the wind fluctuations. The SPWM based inverter can be used to produce the constant output voltage with constant frequency. Also a thin and light weight Lithium Ion Polymer Batteries provides the energy back to the Wind energy conversion system , when the wind speed decreases below the base wind velocity. Simulation results are provided to demonstrate the validity of the proposed fuzzy-logic-based controller and comply with the theoretical results. The performance of the system is compared using various controllers. <![CDATA[Certain Aspects of Univalent Function with Negative Coefficients Defined by Bessel Function]]> ABSTRACT Key words: In recent years, applications of Bessel functions have been effectively used in the modelling of chemical engineering processes and theory of univalent functions.In this paper, we study a new class of analytic and univalent functions with negative coefficients in the open unit disk defined by Modified Hadamard product with Bessel function. We obtain coefficient bounds and exterior points for this new class. <![CDATA[Efficiency of Single Site Phase Transfer Catalyst in Free Radical Polymerization of Butyl Methacrylate - A Kinetic Study]]> ABSTRACT The effectiveness of single site phase transfer catalyst- 2- benzoylethyldecyldimethylammonium bromide has been studied with the help of kinetics of free radical polymerization of butyl methacrylate. The radical polymerization was catalysed with single site phase transfer catalyst, initiated by water soluble potassium peroxydisulphate initiator in ethyl acetate / water biphasic media, under inert and unstirred condition at constant temperature, 60±1ºC. The dependence of rate of polymerization on various experimental conditions, different concentrations of monomer, initiator, and phase transfer catalyst was evaluated and effect of temperature as well as solvent polarity was determined. The order of the reaction with respect to monomer, initiator and phase transfer catalyst was found to be 1, 0.5 and 0.5 respectively. It was also observed that a slight increase in rate of polymerization as the polarity of solvents increased. A suitable kinetic mechanism has been suggested as per the investigational conditions. Molecular weight of the polybutyl methacrylate which has been polymerized bysingle site phase transfer catalyst was evaluated using gel permeation chromatographic technique. <![CDATA[Fuzzy Based Mobility Management in 4G Wireless Networks]]> ABSTRACT Handover is the key procedure in wireless networks to provide required qual ity of service to the users during mobility Handover. As the current scenario of wireless communication comprises of heterogeneity in architecture, application and radio access technologies concentrating on vertical handover becomes important to provide continuous communication and ubiquitous coverage .This paper provides comprehensive survey of the vertical handover, decision technique and parameter used for making proper handover in horizontal and vertical handover . The recent handover schemes are discussed and classified which varies based on concepts and the adopted schemes. A Fuzzy based decision making algorithm is proposed to made the handover decision more appropriate and to avoid loss of communication and provide better performance. <![CDATA[Novel Image Classification technique using Particle Filter Framework optimised by Multikernel Sparse Representation]]> ABSTRACT The robustness and speed of image classification is still a challenging task in satellite image processing. This paper introduces a novel image classification technique that uses the particle filter framework (PFF)-based optimisation technique for satellite image classification. The framework uses a template-matching algorithm, comprising fast marching algorithm (FMA) and level set method (LSM)-based segmentation which assists in creating the initial templates for comparison with other test images. The created templates are trained and used as inputs for the optimisation. The optimisation technique used in this proposed work is multikernel sparse representation (MKSR). The combined execution of FMA, LSM, PFF and MKSR approaches has resulted in a substantial reduction in processing time for various classes in a satellite image which is small when compared with Support Vector Machine (SVM) and Independent Component Discrimination Analysis (ICDA)based image classifications obtained for comparison purposes. This study aims to improve the robustness of image classification based on overall accuracy (OA) and kappa coefficient. The variation of OA with this technique, between different classes of a satellite image, is only10%, whereas that with the SVM and ICDA techniques is more than 50%. <![CDATA[Nano Coated Lead Free Solders for Sustainable Electronic Waste Management]]> ABSTRACT Lead has been used in a wide range of applications, but in the past decades it became clear that its high toxicity could cause various problems. Studies indicate that exposure to high concentrations of lead can cause harmful damages to humans. To eliminate the usage of lead in electronic products as an initiative towards electronic waste management (e waste), lead free solders were produced with suitable methods by replacing lead. But lead free solders are not preferred as a substitute of lead because they are poor in their mechanical properties such as tensile strength, shear strength and hardness which are ultimately required for a material to resist failure.Nano-Structured materials and coatings offer the potential for Vital improvements in engineering properties based on improvements in physical and mechanical properties resulting from reducing micro structural features by factors of 100 to 1000 times compared to current engineering materials. <![CDATA[Mechanical Behavior of Concrete Modified by Replacement of Cement by Rice Husk Ash]]> ABSTRACT Construction industry is in need of lump sum quantities of materials which has increased both their demand and price. The use of large quantities of cement leads to increasing CO2 emission and as a consequence, the greenhouse effect. Consumption of wastes and byproducts from various sources in the manufacture of concrete has gained a great deal of importance in present days. Various researches are currently being conducted concerning the use of such products in concrete. RHA is a carbon neutral green product. Lots of ways are being thought of for disposing them by making commercial use of this. Rice husk ash is a good super-pozzolan which can be used to make special concrete mixes. The rice husk ash has been taken for this present study due to its easy availability and effective pozzolonic properties that are expected to improve the mechanical strength properties of concrete. Concrete specimens were made for evaluation of Compressive, Split Tensile, Flexural strength and Stress-Strain Behavior of concrete. The tests were conducted at the age of 7 and 28 days. Generally all mixes containing RHA achieved better properties than the conventional mix without RHA. By the experimental investigation the recommendation is given for using optimum percentage of RHA in concrete. <![CDATA[Experimental Investigation on Self-Compacting Self-Curing Concrete Incorporated with the Light Weight Aggregates]]> ABSTRACT Self-Compacting Concrete (SCC) flows around obstructions by its self-weight to fill entirely and self-consolidate (without any need for vibration), without any part of disconnection and chunking. The eradication of the need for consolidation leads to better quality concrete and substantial improvement of running conditions. The fresh state of SCC mixes will usually have huge amount of fine fillers, including cement, and produce excessively high compressive strength concrete. In order to overcome the workability problem Super Plasticizer (SP) and Viscosity Modifying Agent (VMA) are used. Here, the workability admixtures are fixed at a constant rate of 2% based on the weight of cement. This technique examines special applications in cases of bottleneck reinforced sections, rafts, tunnel linings, highly reinforced columns, underwater repairs, bridge piers and placements. LECA and Vermiculite have high porosity, and are added to concrete mixtures to create a lightweight concrete mix. An attempt has been made to develop a combination of self-compacting and self-curing concrete with each 5% and 10% of LECA and Vermiculite as a partial replacement to fine aggregate. As there was no proper mix design for the development of this modern concrete, the design has been carried out based on EFNARC specifications for the design strength of M40 grade concrete. The porosity of light weight aggregate provide source of water for internal curing of concrete which enhances concrete strength and durability. Based on more trials, it was noticed that the concrete with 10% of LECA and Vermiculite in individual provides good results. <![CDATA[HRL-Local Infinite Triangular Array Languages]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Isolation, Culturing, Characterization and Aging of Adipose Tissue-derived Mesenchymal Stem Cells: A Brief Overview]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Identification of a fat-soluble fraction of Sparganium stoloniferum that inhibits cervical cancer HeLa cells]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Effect of LPS on the Viability and Proliferation of Human Oral and Esophageal Cancer Cell Lines]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Chemical quality of bottled mineral waters from markets of Curitiba-PR-Brazil]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Characterization Of A Novel Hydrolytic Enzyme Producing Thermophilic Bacterium Isolated From The Hot Spring Of Azad Kashmir-Pakistan]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Blackberry Vinegar Produced By Successive Acetification Cycles: Production, Characterization And Bioactivity Parameters]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages. <![CDATA[Erratum: Isolation, Identification and Molecular Characterization of Highly Pathogenic Newcastle Disease Virus From Field Outbreaks]]> ABSTRACT A new subclass of infinite triangular arrays called hrl-local infinite triangular arrays is introduced. We introduce infinite triangular domino systems to recognize the infinite triangular picture language. Also we introduce strictly domino testable ωω-triangular array languages.