bluuebunny/crossref_metadata_2025 huggingface dataset:
Wavelet Nyström fast numerical algorithm for the integral equation in scattering problems
Authors: Xu Yangyang , Shang Yaoda , Meng Xiangyu , Sun Jianguo
Published: February 2021

We present a fast Nyström algorithm to solving the inhomogeneous Lippmann– Schwinger equation for scattering wave field problems. This algorithm transforms the discrete matrix of the linear integral operator into a sparse matrix utilizing the compression property of the wavelet transform. The sparse linear equations are solved by the double conjugate gradient method. In the numerical part, we verified the feasibility and effectiveness of our method by modeling the wave field for a synthetic model.
Inversion of 1D audio magnetotelluric data based on residual convolution neural network
Authors: Liu Zhengguang , Ren Zhengyong , Tang Jingtian , Zhang Liang
Published: February 2021

The 18-layer residual convolution neural network (ResNet18) were used for 1D audio magnetotelluric(AMT) data inversion. In order to avoid the dependence of the traditional iterative algorithm on the initial model and calculate sensitivity matrix, we have trained ResNet18 via providing model parameters instantaneously. The residual network was used to solve the problem of deep network gradient disappearing. Deep network and lots of sample data could improve the generalization of the network. The experimental results showed that it could obtain reliable inversion results for synthetic AMT data.
Study on conical source transient electromagnetic based on AWPSO algorithm
Authors: Huang Gang , Yang Haiyan
Published: February 2021

The transient electromagnetic conical field source device can effectively reduce the inductance between the coils and improve the resolution of the small device to detect the shallow underground layer. However, the conventional inversion method requires an initial model and has the disadvantage of low inversion precision. Combined with the results of previous studies, this paper proposed an adaptive weighted particle swarm optimization (AWPSO) algorithm based on Sigmoid function through the analysis and research of PSO, which solved the problem of artificial initial model and low precision of inversion results. By calculating the test function, the algorithm can effectively improve the searching ability of particle swarm optimization algorithm. Several different typical geoelectric models are designed, and the algorithm is applied to data inversion of transient electromagnetic geoelectric model. Combined with the measured data of a hot spring practice area, the inversion calculation and interpretation of the sounding data were carried out, and the inversion calculation results were confirmed by the geological and hydrological data. The results show that the proposed particle swarm optimization algorithm has a high inversion fitting degree to the theoretical model and the measured data, achieves the separation of the apparent resistivity anomalies in the shallow subsurface, and improves the resolution and interpretation accuracy of the measured data in the conical field source transient electromagnetic method.
FCT finite difference forward simulation of the submarine viscoelastic seismic wavefield
Authors: Xi Jianjun , Cui Dandan
Published: February 2021

The actual seafloor is the typical viscoelastic medium, covered with unconsolidated geological bodies like sand, gravel, sludge, and detritus on the surface. When the seismic wave is propagating therein, viscosity of the seafloor strata will cause seismic wave energy loss, amplitude attenuation and gradual frequency reduction at the wavelet center, and then the accurate subsurface information and high-resolution images cannot be obtained directly from the seismic data due to the reduced signal resolution and SNR. Considering seabed viscoelastic media properties, a model including quality factor, density, and other physical parameters, the flux corrected transport (FCT) algorithm is established to describe the target seafloor and solve the wave equation, in which, the finite difference numerical simulation method of FCT is used to suppress the numerical dispersion generated by differential calculation in coarse grid, improve the seismic wavefield simulation accuracy and computational efficiency. Based on the submarine ancient channel types and the basic characteristics of the real and typical marine geological phenomena, the seismic responses to the three types of submarine ancient channel models, which are straight, curved and braided, are calculated, with good results acquired.
A new landslide classification method based on electrical differences and relevant examples
Authors: Xie Xinglong , Ma Xuemei , Ming Yuanyuan , Li Qinchen , Ren Zhengwei
Published: February 2021

A new landslide classification method based on electrical differences is proposed in this paper. The electrical parameters are obtained by the high-density electrical method, which is commonly used in landslide exploration. In this paper, landslides are divided into four categories based on the electrical difference between overburden and bedrock, and on this basis, the landslides are further divided into four categories according to the local electrical difference of landslides, totally eight kinds of landslides. The high-density resistivity method works well for exploration of both type I and type II slides. However, for type III and type IV, other geophysical methods should be supplemented. For type V-VIII landslides, they are simplified into type I-IV landslides in sections according to their electrical characteristics. As for complex landslides caused by multiple factors, more survey lines need to be laid systematically, combined with various methods, as well as information of drilling and trenching for comprehensive prospecting. The landslide classification method proposed in this paper provides some basis and reference for landslide exploration.
3D characterization of archaeological remains buried under obstacles using annular array electric resistivity tomography
Authors: Shi Zhanjie , Yu Tianxiang , Xu Liuwei
Published: February 2021

When archaeological remains are buried under buildings or other obstacles, it is very difficult to detect them by performing the traditional electric resistivity tomography (ERT) which commonly sets out survey lines right above those remains. We presented an annular array ERT method to solve the above problem. All electrodes were arranged around the obstacles in an annular array form. The apparent resistivity data were acquired through a special electrode shifting design. The electrode moved in the same serial number order with the cross diagonal survey of a 3D rectangular array. ERT apparent resistivity data were inverted by a 3D resistivity inversion package named RESINVM3D. The proposed method was tested using a synthetic model and field data. Synthetic results show that the target buried under obstacles can be imaged through the annular array. The result of field case indicates grave chamber buried under grave mound can be characterized using the proposed method. We conclude that the annular array ERT is an effective and valuable scheme for the detection and characterization of archaeological remains buried under obstacles.
Early time data processing in shallow AEM exploration
Authors: Jing Chunyang , Zhu Kaiguang , Peng Cong , Fan Tianjiao , Yang Yang , Liu Donglai
Published: February 2021

For shallow exploration, high-frequency pseudo-random binary sequence is used in the time-domain airborne electromagnetic system. This system is working in the on-time and the earth response could be derived from system identification, which is different from the previous time-domain electromagnetic systems. The early time data is crucial for obtaining a detailed resolution. It could be severely disturbed by the primary field, the receiver response and noise. Here we present an approach for removing the primary field by matching subtraction in transformation of correlation calculation. The noise is suppressed as not correlated with the pseudo-random binary sequence. This approach is proved efficient by applying to simulation data based on forward modeling. The receiver influence is analyzed through the response of the equivalent electronic circuit. The 1D inversion results indicate that critical damping state and high cut-off frequency could reduce the adverse effect on the resolution of shallow exploration.
A New Improved Algorithm for Aeromagnetic Compensation
Authors: Zhao Xiao , Yu Ping , Jiao Jian
Published: February 2021

Magnetic compensation is a necessary step in aeromagnetic data processing. The aeromagnetic compensation model is a linear regression model, but the model has multiple collinearity problems, which will reduce the performance of the compensation model. In view of this problem, we propose a deep autoencoder (DAE) aeromagnetic compensation algorithm. The DAE network extracts the features of the data by learning the compressed representation of the coefficient matrix, thereby weakening the correlation between the coefficient matrix variables. The feature obtained after dimension reduction is used for compensation calculation. The DAE algorithm is verified by Unmanned Aerial Vehicles, and the results show that the compensation quality of the DAE is better than the least squares algorithm.
A Comparison of Different Divergence-free Solutions for 3D Anisotropic CSEM Modeling Using Staggered Finite Difference Method
Authors: Li Jian , Liu Jianxin , Guo Rongwen , Liu Rong , Wang Xulong , Wang Yongfei , Chen Hang
Published: February 2021

This paper presents a staggered finite difference (FD) method for numerical modeling of 3D controlled-source electromagnetic (CSEM) data in an anisotropic conductive medium. The traditional Krylov subspace methods may not be convergence for EM modeling in strong electrical anisotropy due to the variation of the conductivity in the sea-bottom sediments over a range of frequencies (0.1-10 HZ). The algorithm is based on a modified version of the curl-curl equations with scaled grad-div operator (CCGD) in frequency domain. In this approach, we integrate the divergence correction term in the original system with its importance controlled by scaling factors (the same values as model resistivities are used in this paper) and avoid the application of the iterative divergence correction. The corresponding responses calculated by the CCGD and the traditional CC-DC approach for the VTI ocean canonical reservoir model are nearly identical. Then based on the case, we examine the numerical performance of the CCGD approach, and compare it with the CC-DC in terms of computing time and iteration number. The results indicate that the proposed CCGD approach is efficient and stable over different frequencies.
An optimal method for a staggered-grid finite-difference solution of elastic wave equations including rotational deformation
Authors: Wang Zhiyang , Bai Wenlei , Li Youming , Liu Hong , Chen Chaopu
Published: February 2021

The staggered-grid finite-difference (SGFD) method is one of the most popular means used in seismic numerical modelling because of its computational efficiency and it is easy to implement. However, it will lead to serious numerical errors while using coarse grids or wavelet with high-frequency. In this work, we proposed an optimal spatial SGFD method based on a new improved particle swarm optimization (PSO) algorithm. Then the dispersion of numerical solution of the first-order spatial derivatives is analyzed. Meanwhile, numerical modelling of elastic wave equations and elastic wave equations including rotational deformation are performed with the optimal spatial SGFD method based on the improved PSO algorithm. Numerical dispersion analysis and numerical modeling results indicate that the optimal spatial SGFD method based on the improved PSO algorithm has high modeling accuracy and can efficiently suppress the numerical dispersion.
Spectral Clustering Analysis of High-speed Train Seismic Events and 4D Ground Frequency Map
Authors: Jiang Yiran , Bao Tiezhao , Ning Jieyuan , Zhang Xianbing
Published: February 2021

Employing a temporary array under a high-speed railway viaduct deployed by Peking University, we observe how the spectral characteristics vary with changes of the speed and the model of the train as well as the rail and groundsill by using the clustering algorithm K-Means. For a train in uniform motion, the spectrum of high-speed rail seismic wave is mainly composed of nearly equally spaced peaks and its fundamental frequency is equal to the ratio of the train speed to the carriage length. We reduce the influence from the train speed by aligning the fundamental frequency to make the spectrum pattern clear and easy for comparison. Clustering results show that the spectra of the high-speed rail seismic events have stable patterns under the same train model, rail and groundsill conditions; the stable spectrum patterns change significantly with the changes of the train model, rail and groundsill conditions; monitoring the stable spectral characteristics might be used in safety control of high-speed rail. We apply the clustering method on all the stations of the array. In order to obtain spectra with higher signal to noise ratio at farther stations, we consider the variation of train type and stack the spectrums of three components of high-speed rail seismic signal produced by trains of the same type on the same station. Using the clustering algorithm, we get the regular pattern of how the three component spectra vary with the train type and station position. Based on the above research on the characteristics of high-speed rail seismic spectra and their variation, we propose the concept of 4D ground-frequency map, and discuss its practicability in monitoring the status of high-speed rail and its surrounding media.
Electrochemical self-assembly of bunch-shaped ZnO nanowire without catalysts
Authors: Chuah L S , Shafiee Haron M F , Yusof Y
Published: February 2021

There are many types of metal oxide nanostructure and one of them is zinc oxide (ZnO). Despite of vast field of application for this material, the fabrication process of nanostructure (ZnO) is rather costly or complicated due to exotic equipment or reagent required. To the leading of our understanding, there are no details about synthesizing the bunch-shaped ZnO nanowire patterns on silicon substrate. A series based on aqueous medium composition: (x) Zn (NO3)2 + 0.1 NaOH, where 0.005 ⩽ x ⩽ 0.2 mol% is prepared using chemical bath method. The distribution and size of ZnO nanostructure was determined using FESEM spectroscopy. Meanwhile, EDX spectra show the presence of ZnO nanostructures in all samples. These researches generate new knowledge on embodiment of ZnO nanostructures on silicon thin film which may useful for finding material with high optical quality for diverse application in photonic devices.
Neural Networks Algorithm for Arabic Language Features-Based Text Mining
Authors: Alrufaye Faiez Musa L , Mhaibes Hakeem Imad , Neamah Ali F
Published: February 2021

Text mining aims to understand texts correctly by utilising several phases to collect those features of Arabic words which are valuable and important to the applications mentioned above in making a correct decision. The technology then builds a strong system that relies on AI techniques, such as neural networks, to collect words in accordance with those features. An ANN is a collection of connected nodes called artificial neurons, which loosely model the neurons in a biological brain. Each connection, like the synapses in a biological brain, can transmit a signal to other neurons. An artificial neuron is one that receives a signal then processes it and can signal to neurons connected to it. The current study is concerned with building a system for analysing words in the Arabic language. This system can be included in any application to address the Arabic language, becoming part of it. The system generates strings for all names and pronouns appearing in the entered text and depends mainly on the automatic assembly of a set features by using neural networks. We implemented the system, with its two phases, on the documents in succession. The results were encouraging, ranging between 83% and 96%.
Descriptive Analysis on Products/Services demand and Market conspectus: A quantitative approach
Authors: Ahmed Mohammed Afaounodden , Azhakath Adresya Suresh , Muthalagu Raja
Published: February 2021

The research conducted in this paper consists of finding out the shortcomings of Efficient Market Hypothesis as it is purely based on if information is immediately priced in the Trading markets. Efficient market hypothesis(EMH) also suggests that it is not possible for someone to give more returns than the market in long term, Which has been disproven in this research using multiple criteria decision making and taking the companies with Good Debt to Market cap ratio and check their aggregated outcome over a long period of time and the rate of return came out to be significantly higher than the growth in the market. One of the main assumptions of EMH also happens to be that fundamental analysis does not affect stock market or stock indexes but its proven to be false as in long term if indexes are selected based on good criterias. Efficient market hypothesis says that stock prices depend on news and the news of the next day is by default unpredictable, but it doesn't take into account the fact that not everyone interprets the news in the same way and even if they do they don't process the information on the same intensity.
Design, simulation and analysis of monofacial solar pv panel based energy system for university residence: a case study
Authors: Mehadi Abdullah Al , Chowdhury Misbahul Alam , Nishat Mirza Muntasir , Faisal Fahim , Islam Md Minhajul
Published: February 2021

This paper proposes a design and software simulation of monofacial solar photovoltaic panel based energy harvesting system for university residence. As the site of the proposed system, the rooftop of North Hall of Residence of the Islamic University of Technology (IUT) is considered. The 3D model of the system is demonstrated by utilizing PVSOL software. The monthly energy production is obtained by performing the simulation in three software named PVSOL, PVsyst, and System Advisor Model (SAM). However, the monthly consumption of the residence is tabulated and graphical presentation is depicted. Hence, the energy flow diagram is illustrated showing that the proposed PV system can contribute 18.4% in the annual demand of the site. The performance of each of the software is evaluated and deviation analysis is performed so that more insight can be achieved in terms of harvesting solar energy. Hence, a cost-effective and self-reliant solar energy model for the rooftop of a university residence is proposed by utilizing monofacial solar PV panels.
A study on sodium - the fast breeder reactor coolant
Authors: Rajan K K
Published: February 2021

Sodium, the second alkali metal in the first group of periodic table is highly chemically reactive. Sodium is widely used in pharmaceutical industries to manufacture lifesaving medicines. Liquid sodium is an excellent reducing agent and heat transport medium, which makes it an important industrial material. The application of this element in liquid form at high temperature as a coolant in fast breeder nuclear reactors necessitated development of sodium technology. Physical, chemical and nuclear properties of sodium led to the choice of sodium as the universally accepted fast breeder reactor (FBR) coolant. The manufacturing of sodium is by electrolysis process. The design and manufacturing requirements of high temperature liquid sodium system components are successfully addressed. Special type of sensors needed for high temperature liquid sodium system are specifically designed and developed. Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam is involved in the development of sodium technology in India. Sodium technology is matured to an extent and around twenty FBRs with sodium as the coolant were constructed, commissioned and successfully operated all over the world. Five sodium cooled fast reactors are currently in operation including fast breeder test reactor (FBTR) in India. Prototype fast breeder reactor (PFBR) is in the advanced stage of commissioning at Kalpakkam. This review paper explains the choice of sodium as FBR coolant and gives highlights on the research and development took place in sodium technology all over the world especially in India with an aim to give an exposure to this technology to the academic community.
A bibliometric analysis on path planning methods for mobile robots published in scientific citation index-expanded indexed journals between 2000-2020
Authors: Muhammad Aisha , Ali Mohammed AH , Shanono Ibrahim Haruna
Published: February 2021

Robots are currently replacing humans in different tasks in various sectors. Among the vital features desirable in autonomous robots is the capability of navigating safely through a given environment. Robot navigation is a process designed with the ability of avoiding any hitches or obstacles while aiming at a specific predefined position. Many studies have been proposed to find solutions to robot path-planning problems. This paper presents a bibliometric analysis of the relevant publications published from 2000 to 2020. The results show that 5385 articles were published in 1128 journals, hence indicating publication diversity. There is a steady rise in the yearly publication output, reflecting an increase in global research interest in the topic. In general, this research provides useful insight into path-planning research so that researchers in this area can better recognize the relevant research study topics and search for the appropriate research partners.
Tuning and experimental assessment of second-order generalized integrator –frequency locked loop grid synchronization for single-phase grid assisted system
Authors: Brahmbhatt Bhavik , Chandwani Dr. Hina
Published: February 2021

The phase-locked loop (PLL) is an essential part of the grid-tied system to synchronize control of converter with grid voltage, particularly affects the converter stability as well as performance under weak grid conditions. During abnormality in a grid, its bandwidth ought to be a11dequately brought down to achieve appropriate disturbance rejection capability with a compromise to slower detection speed. The researchers have done intended work in advanced PLLs to improve phase-angle detection speed by modifying the pre/in-loop filtering stage. A most concerning challenge with the PLLs is the means by which to additionally provide superior dynamic performance and reduced settling time without bargaining stability of system along with the capability of disturbance elimination To overcome this challenge, this paper describes the second-order generalized integrator (SOGI-Frequency Look loop (FLL) which offers filtering capability like band-pass filter, low-pass filter, and notch filter for adaptive frequency tuning as well as an orthogonal signal generation for the grid-tied photovoltaic inverter. The impact of control parameters on their dynamic performance in SOGI-FLL is tabulated from a step response of frequency estimation by taking a frequncy shift. Furthermore, Low-cost DSP based STM32F407VGT the microcontroller is employed to implement a SOGI-FLL to test under adverse grid conditions using Waijung Block-set of SIMULINK/MATLAB. The experimental results of SOGI-FLL have proven superior dynamic performance over type-2 PLLs by choosing the appropriate value of the control parameter of SOGI-FLL.
A review on training and leadership development: its effectiveness for enhancing employee performance in Indian construction industry
Authors: Misra Pramod Kumar , Mohanty Jitendra
Published: February 2021

The second largest contributor to Indian GDP is the construction industry. It is the largest employing industry having huge economic potential which was valued over $126 billion in 2016 and it continues on a steady growth path. It is expected that the value of the real estate and construction market will increase seven-fold by 2028. Growth is likely to be underpinned by stable government support for infrastructure development, as well as through expanded private sector involvement. However, the industry suffers from inefficiencies that result in time and cost overrun in their projects. Some of the potential causes of inefficiencies originate from the underdeveloped labour market and poor organizational structures that operate in the industry. An exhaustive list of factors found to drive the industry to its inefficient operation resulting invariably to failures. If we put all these factors in one basket, they reduce to one single word; “lack of training of workforce and poor management”, whether it refers to the skilled, semi-skilled or unskilled labour force and/or the poor project management from the organizational side of the project. The present study extensively reviews problems of construction company that originate from the labour market.
Production of high strength bioliquid from municipal solid waste (MSW) using mixed culture
Authors: Zainol N , Sidek N S M , Ya’acob A
Published: February 2021

Landfilling is one of the most commonly used methods of municipal solid waste (MSW) disposal. It is necessary because there are residues in all waste management processes that cannot be reused or recovered further and are essentially landfilled. For the degradation of MSW, thermal, mechanical and biological pretreatment techniques are used. MSW could be treated and converted into liquid biomass (bioliquid) by using enzymes. This research focused on the production of high strength bioliquid in MSW. The experiments were conducted in three stages namely: acclimatization process, preliminary study and factorial analysis to determine the production of high strength bioliquid in MSW. The selected factors were ratio of AMC and substrates (1:2 and 1:5), temperature (room temperature and 37 °C), pH (adjusted pH and no pH adjustment), PET plastics size (1cm2 and 4cm2) and Hydraulic Retention Time (3 hours and 9 hours). Design Expert software (Version 7) was used to construct an experimental table where all the factors were randomized. Two-level factorial analysis (TLFA) was used to analyze the most contributing factor and interaction between the factors. The results showed that the most significant factor was temperature, while the interaction factors were between temperature and HRT. The best conditions of COD increment were determined at AMC/S ratio 1:5, adjusted pH, PET plastics size of 1cm x 1cm, at room temperature and HRT of 3 hours. The experimental and targeted final increments of COD were 2.19 and 1.99 respectively. Since the error was less than 10%, it is acceptable, and the objectives of this research were successfully achieved.
Cosmic acceleration in LRS bianchi type I space- time with bulk viscosity in general relativity
Authors: Sharma Sanjay , Poonia Laxmi
Published: February 2021

In present paper our intention to construct a locally rotational symmetric bianchi type I space time under framework of massless scalar field have flat potential. In existence of bulk viscosity the developed model provides inflationary solutions. The System of nonlinear Einstein field equations are solved by using suitable condition V(φ) = K (constant) and the bulk viscosity coefficient is inversely proportional to scalar of expansion i.e. ξθ = α yields the negative deceleration parameter, which favorable to cosmic accelerating universe in current scenario. The model isotropize at particular cases. The Proper volume for model increase with time represents eternal inflation of present universe. The physical and structural aspects of model are discussed in significantly manner.
Comparison of reducing agent for reduced graphene oxide as cathode for zinc-ion hybrid capacitors
Authors: Prasertkaew S , Dejthammathorn T , Pattananuwat P
Published: February 2021

The comparative study of using the different reduced graphene oxide sources, obtained from thiourea and 1-ascorbic acid as reducing agent, for zinc cathode capacitors is investigated. The chemical structure and the surface morphology of both reduced graphene oxide samples are examined by infrared spectrum and scanning electron microscopy, respectively. Serving as cathode for zinc-ion hybrid capacitors, the as-prepared reduced graphene from 1-ascorbic acid reveals the better the specific discharge capacity (41.50 mAh g-1) than that of the obtained from thiourea (40.78 mAh g-1). The cycle stability of zinc-ion hybrid capacitors coin cell in 2M ZnSO4 electrolyte is examined by multi-cycles of GCD at 0.1 A g-1, demonstrating that rGO obtained from 1-ascorbic acid can endow the retention up to 72.8% after 200 cycles, while rGO obtained from thiourea is remained at 63.1%.
Simulation and experimental validation of hysteresis current control technique for speed control of brushless DC motor
Authors: Patel Hetal , Chandwani Hina
Published: February 2021

Brushless DC Motors (BLDC) are finding wide applications in household appliances and electrical vehicles. Microcontroller are widely used for controlling the BLDC motors however the realization of BLDC drive requires expertise in microcontroller programming. In this paper modelling, simulation and easy hardware implementation of BLDC motor having shaft encoder using STM32F4 series ARM Cortex-M4 microcontroller is demonstrated. A simple method of controlling the BLDC motor in closed loop, using a hysteresis current controller is implemented. The hall sensors are used to find the exact rotor position for the electronic commutation and the encoder is used to measure actual motor speed. The closed loop operation consists of an inner loop which is hysteresis current controller. The gate pulses for the three phase inverter bridge are produced by comparing the actual currents with the reference currents. The outer speed loop consists of a PI controller which compares the actual speed with the reference speed to obtain smooth speed control under varied load condition. The complete hardware circuits and MATLAB/Simulink environment blocks for programming are discussed in detail. The hardware results demonstrate the easy and accurate realisation of closed loop speed control of BLDC Motor.
AE signature analysis using continuous and discrete wavelet transforms to predict grinding wheel conditions
Authors: Shivith K , Rameshkumar K
Published: February 2021

In this study, experiments were conducted in a surface grinding operation to acquire and analyze the AE signature to establish a statistical correlation between Acoustic Emission features extracted in wavelet domain with grinding wheel conditions. Grinding wear plot was established to identify the grinding wheel conditions by monitoring the wear in the abrasive grinding wheel and workpiece. Continuous and Discrete Wavelet transforms were carried out to extract the wavelet coefficients. Decision Tree based statistical models were built using discrete and continuous wavelet coefficients. The performance of J48 Decision tree and Classification and Regression Decision Tree (CART) are compared using the classification accuracy and kappa statistics measures. In discrete wavelet transforms, wavelet coefficients are extracted using four mother wavelets namely Haar, Daubechies, Symlet, and Coiflet. In Continuous Wavelet Transforms, the Morlet wavelet is used to extract the 1D wavelet coefficients using 2D scalograms.
Extraction of microbial chitosan for piezoelectric application
Authors: Zamli M I , Ahmad F B , Akmal M H M
Published: February 2021

Chitosan is a natural polysaccharide derived from chitin which is found in the fungus cell walls and crustacean shells. Chitosan has generated a great interest in piezoelectric application because of its interesting properties such as biodegradability, biocompatibility, and low toxicity. The purpose of this study is to focus on the cultivation, fabrication and characterization of chitosan thin film from fungal strain, Aspergillus oryzae cell walls. The fungi was cultivated in bioreactor. Fabrication of chitosan thin film via solvent casting method was optimized via one-factor-at-a-time (OFAT) with 2 parameters (drop-casting volume of solution and drying temperature). Pure chitosan dissolved in formic acid at 0.25 M concentration, dried at 60°C with 35 mL of solution volume gave the highest mechanical quality factor (3.22) and the lowest dissipation factor (0.327) for thin film fabrication. The optimized fabricate thin film was validated using fungal chitosan and shows the results of mechanical quality factor (3.68) and dissipation factor (0.248) which is comparable to conventional piezopolymer thin film. Therefore, fungal chitosan thin film obtained in this study has the potential to be used in piezoelectric application.
Design and Implementation of FEC for CDMA System
Authors: Smrithi M N , Abdul Rajak A R
Published: February 2021

In every wireless communication the data that is transferred is at a high risk of falling under the clutches of various types of disturbances termed as noise, there are various types of noises which are thermal noise, shot noise, IF noise, burst noise, avalanche noise etc. they occur due to a number of factors it can be due to temperature, device malfunctioning and frequency interference. Due to this, the data being transferred in the wireless communication channel gets corrupted resulting in data loss. This problem is rectified by employing FEC (Forward Error Correction) method on the data being transferred. This research focuses on the implementation of various FEC codes in CDMA system to study its detailed performance analysis with the help of MATLAB Software.
Investigative analysis of match-line sensing schemes in TCAM for high-speed performance
Authors: Faisal Fahim , Nishat Mirza Muntasir , Mim Sayka Afreen , Akter Hafsa , Kaysar Shagor Md. Rafid
Published: February 2021

This paper delineates an investigation of TCAM-design techniques for both circuit level and architectural level. In the case of circuit level, low power Match Line sensing techniques and Search Line driving propositions are exhibited. At the architectural level, four processes for curtailing power absorption are introduced. In this paper, 16×16 bit TCAM is designed in 0.18μm CMOS. The hypothesized Match Line sensing scheme truncates power absorption by pruning search time and dampering voltage swing of traditional ones. With respect to the conventional CR-MLSA, the proposed MLSAs delineate the depletion of 56% and 48% for measuring energy. For simulation, 1.8V supply voltage is used.
Ultracompact gas-sensor based on a 2D photonic crystal waveguide incorporating with tapered microcavity
Authors: Harhouz A , Hocini A , Tayoub H
Published: February 2021

In this study, a new ultra compact gas-sensor, based on a 2D photonic crystal waveguide incorporating with tapered microcavity, is designed to detect small refractive index changes. The refractive index (RI) sensor is formed by a point-defect resonant cavity in the sandwiched waveguide on Si slab with triangular lattice. The properties of the sensor are simulated by using the plane wave expansion (PWE) method and the finite-difference time-domain (FDTD) algorithm. The transmission spectra of the sensor with different ambient refractive indices ranging from n = 1.0 to n = 1.01 are calculated. The calculation results show that a change in ambient refractive index of Δn=1×10−4is apparent. The proposed sensor achieves a sensitivity (Δλ/Δn) of 523.2 nm/RIU. It was found that the resonance wavelength is a linear function of the refractive index in under study range. The sensor is appropriate for detecting homogeneous media.
Impact of using nano-hydroxyapatite on postoperative hypersensitivity of two bleaching techniques – randomized controlled clinical trial
Authors: Mohamed H , Fayed A , Elkassas D , Hassanien O
Published: February 2021

To evaluate the impact of using Nano-hydroxyapatite on post-bleaching hypersensitivity after using two different bleaching techniques. Twenty-eight patients were enrolled in this study according to inclusion and exclusion criteria. The patients were randomly assigned into four groups (n=7). G1; bleaching was performed using photo-catalyzed bleaching technique (Philips, zoom), followed by application of Amorphous Calcium phosphate based desensitizing agent (ACP, Relief ACP). G2; bleaching was performed using chemo-catalyzed bleaching technique (Philips, Dash), followed by application of ACP. G3: bleaching was performed using zoom, followed by application of nano-hydroxyapatite based desensitizing agent (Nano p), G4: bleaching was performed using Dash, followed by application of Nano-hydroxyapatite. Post bleaching hypersensitivity was assessed using “Visual analogue scale”. Hypersensitivity was evaluated after: bleaching immediately, application of the desensitizing agent immediately, 24 hours, 48 hours and after one week. Cases with severe hypersensitivity were relieved immediately after Nano p application, meanwhile in case of ACP, cases with severe pain were relieved after 24 hours after its application. Statistically significant difference was evident with the photo catalyzed group immediately after Nano p application than before its application. Reduction in hypersensitivity by time was evident in both the chemo and photo catalyzed groups. In addition, it was found that after one week, all pain scores disappeared with all tested groups. Nano hydroxyapatite particles have an immediate (just post application) relief effect of severe pain with both used bleaching systems. However, the post bleaching hypersensitivity diminished completely after 1 week, irrespective of the desensitizing agent used. The application of Nano hydroxyapatite paste after bleaching is a valid method for diminishing severe post bleaching hypersensitivity when applied with either a photo or chemo catalyzed bleaching agents.
Synthesis, spectroscopic study, biological activity and dyeing application of curcumin - Schiff base with various metal ions complexes
Authors: Ali A M , Al-Noor T H
Published: February 2021

A tetradentate (N2O2) Schiff base (H2Ldfm) was successfully synthesized via condensation of curcumin / diferuloylmethane (dfm) and L-leucine amino acid (HL). There were three different methods that used for synthesizing H2Ldfm; (refluxing, grading, and fusion). Ten different metal complexes were also successfully synthesized by combination of the Schiff base (H2Ldfm) and 1,10-phenanthroline (phen) ligand to form a hexadentate (N4O2) mixed ligands (Ldfm, phen) with ten different metal salts (M) where{ M= Al(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Ag(I), Cd(II), Hg(II), and Pb(II)}. The molar ratio of reactants was (1:1:1) (M: H2Ldfm : phen). The new Schiff base and its new complexes were characterized by different physicochemical techniques such as FT-IR, UV-Visible, elemental analysis (C.H.N), 13C-NMR, 1H-NMR, molar conductivity, mass spectroscopy, magnetic susceptibility, and thermal analysis. All complexes exhibited octahedral geometry. The solution conductivity of (Al (III), Fe (III), and Ag(I)) complexes in DMSO shows an electrolytic behavior, while the solution conductivity of (Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Hg(II) and Pb(II)) complexes shows non-electrolytic attitude. The Schiff base (H2Ldfm) and its metal complexes were used for industrial and biological application such as dyeing cotton fibers testing and two types of bacteria testing like (Staphylococcus aureus and Escherichia Coli).
Dielectric and dynamic mechanical properties of Rochelle salt / PVA composites
Authors: Taha E O , Nasr G M
Published: February 2021

A new type of PVA composites containing Rochelle salt was prepared using the casting method. The electrical, Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) tests were performed on 0, 20, 30, and 50 weight% PVA based Rochelle salt to identify the effect of salt on the electrical, thermal and mechanical properties of composites. The results showed that the dielectric properties of composites were greatly improved by the addition of salt. The dielectric constant by 28.5%, 98.4% and 236.5% for composite contents 20 wt%, 30 wt% and 50 wt% Rochelle salt, respectively. The observations of dynamic mechanical analysis indicated that the adding of salt reduces both the storage modulus and affect the glass transition temperature of the composites. Moreover, the thermal stability and char yield of the PVA composites were highly affected by the Rochelle salt content.
Shear bond strength of bio-active cement versus self-adhesive resin cement with enamel and dentin when bonded to zirconia in wet and dry conditions (in-vitro study)
Authors: Elattar M A , Khalil A H , Younis J F
Published: February 2021

ACTIVA bio-active cement is resin-modified glass-ionomer cement that was introduced for re-mineralizing of the disintegrated joint. Due to the lack of data about this bioactive cement, this study evaluated the shear bond strength of bioactive cement and self-adhesive resin cements to tooth substrate (enamel and dentin), in wet and dry conditions when bonded to zirconia. In this study, 40 extracted mandibular molars caries-free were collected. Each tooth was cut by diamond disk (bucco-lingual section) to expose the dentin and enamel. Teeth were randomly divided into two groups enamel and dentin (n=20). Each group was further divided into two subgroups; wet and dry samples (n=10). Each subgroup was divided according to the cement used, into resin cement or bioactive cement (n=5) and bonded to zirconia. Shear bond strength was determined, after thermo-cycling. Statistical analysis of the results showed that there was no statistically significant difference between shear bond strength of the two cement types either with wet enamel or dentin. With both cements, enamel showed statistically significantly higher mean shear bond strength than dentin. It was concluded that, both cements showed comparable results with significant superiority to the self-adhesive resin cement.
Study of dark electrical properties and photoelectric performance of organic/inorganic (ZnPc/p-Si) Solar cells
Authors: El Amin A A , Mahmoud M M
Published: February 2021

A Zinc Phthalocyanine (ZnPc) film was deposited by thermal evaporation on a monocrystalline p-Si substrate to provide a p-ZnPc/p-Si organic/inorganic heterojunction. The electrical characteristics of the fabricated cell were examined by measuring the current density versus voltage (J-V). The fabricated cell was characterized by a contact barrier of 0.56 eV and a rectification ratio of 230 calculated at ± 1 V−1. The dark J-V measurement suggested that the DC current density in this junction contains a thermionic conduction mechanism when the applied voltage is relatively low. At higher voltages another conduction is dominated called the space-charge limited conduction mechanism (SCLC) controlled by a single trapping level. The I-V measurement was performed with an illumination of 100 mWcm−2 and the photoelectric conversion characteristics of the junction were also studied, achieving a power conversion efficiency of 2.7%. The other solar cell parameters such as the short-circuit current Isc, the open-circuit voltage Voc and the filling factor FF were evaluated and equaled to 2.5 A, 1.132 V and 0.477 at room temperature. The dependence of these parameters as a function of the temperature has also been studied in the temperature range from 300 to 400 K.
Effect of stirring time on ZnO nanoparticles properties and morphology
Authors: Moghazy M A
Published: February 2021

The impact of stirring time on the ZnO nanoparticles assembly and properties as a novel study was investigated. A precipitation technique has been used for synthesizing ZnO nanoparticles and the impact of stirring time as well as calcination temperature and time were analyzed. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR) were used for characterizing the resulting powder. The effect of stirring time, (viz., 0, 2, 4 and 6 h), on the optical properties was investigated using UV-Visible spectroscopy. The XRD analysis shown that all of the acquired powders had a pure form of ZnO nanoparticles with distinct crystallite size. The best circumstances for ZnO nanoparticle synthesis were 2h stirrings time and 400°C for 1 h, as calcination temperature and time, respectively. The FTIR spectra show that ZnO nanoparticles prepared at different stirring times appeared in wavenumber range 435.3 - 458.2 cm−1. SEM pictures reveal different surface distribution with some agglomeration through a variation on stirring time. The bandgap value was identical for 2 and 4 h stirring time with value 3.18 eV while, zero and 6 h stirring showing the same value with slight increase compared with 2 and 4 stirring to be 3.2 eV.
Microstructural changes and fracture resistance of nano-crystalline monolithic zirconia restorations upon aging
Authors: Kamel M H , Zaghloul H , Salah T , Ghanem L
Published: February 2021

To assess the effect of nano-modification of two CAD/CAM monolithic Zirconia systems (wet and dry-milled) on microstructural changes and fracture resistance upon aging. Twenty monolithic Zirconia discs (10mm x1.5mm) were divided into 2 groups (n=10) according to fabrication system;wet-milled (Incoris TZI) and dry-milled (CeramillZolid). Each group was subdivided into two subgroups (n=5), whether subjected to aging or not. Aging proceduresincluded accelerated hydrothermal aging and cyclic loading. Microstructural changes were assessed quantitatively and qualitatively using x-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Discs were subjected to fracture resistance test usinguniversal testing machine. Meansandstandard deviations were recorded for phase transformation (t-m)of Zirconia and repeated ANOVA was used to correlate phase transformation with fracture resistance results (p≤0.05). For aged subgroups, XRD analysis revealed significantly higher phase transformation of wet-milled than dry-milled (p≤0.05) and SEM analysis revealed wide zone phase transformation for wet-milled zirconia and minimal zone for dry-milled. For both systems, no significant difference between the mean flexural strength values ofnon-agedand aged zirconia (p≤0.05). Nanocrystalline microstructure of monolithic zirconia improved its resistance to aging. The fracture resistance of the two systems was not affected by aging.
A DFT investigation of anion-π interactions between halogen oxyanions (XO3
−, X = Cl, Br, I) and aromatic π-systems (benzene and coronene)
Authors: Elgengehi S M , El-Kelany Kh E , El-Taher S
Published: February 2021

Anion-π interactions have proved to play a key role in many chemical and biochemical phenomena. In order to investigate the nature and the applications of these interactions, the anion-π interactions of the chlorate (ClO3
−), bromate (BrO3
−), and iodate (IO3
−) oxyanions with benzene and coronene have been studied using density functional theory (DFT). The structures, adsorption energies, and electronic properties of XO3
−(X = Cl, Br, I) adsorbed on benzene and coronene have been explored using dispersion corrected DFT hybrid functional, M06-2X-D3, with the def2-TZVP basis set. Benzene and coronene have been respectively used as a building block and a simple flake of graphene. The interaction of these anions with benzene is found to be unexpectedly favorable. Their binding strength is further increased when the anions are adsorbed on coronene. Moreover, energy decomposition analysis based on symmetry adapted perturbation theory (SAPT) has been performed and the nature of interaction is characterized using noncovalent interaction analysis (NCI) based on reduced density gradient (RDG) method. Generally, the favorable binding of these anions with benzene or coronene is mainly ascribed to dispersion interactions. These anion-π interactions with graphene flakes or with benzene can be utilized in the design of anions receptors and detectors.