Search results for: Leadership Structure

Authors: Akhila Palat, B. Umashankar

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Back-to-back Mechanically Stabilized Earth (MSE) walls are cost-effective soil-retaining structures that can tolerate large settlements compared to conventional gravity retaining walls. They are also an economical way to meet everyday earth retention needs for highway and bridge grade separations, railroads, commercial and residential developments. But, existing design guidelines (FHWA/BS/ IS codes) do not provide a mechanistic approach for the design of back-to-back reinforced retaining walls. The settlement analysis of such structures is limited in the literature. A better understanding of the deformations of this wall system requires an analytical tool that incorporates the properties of backfill material, foundation soil, and geosynthetic reinforcement, and account for the soil–structure interactions in a realistic manner. This study was conducted to investigate the effect of reinforced back-to-back MSE walls on wall settlements and facing deformations. Back-to-back reinforced retaining walls were modeled and compared using commercially available finite difference package FLAC 2D. Parametric studies were carried out for various angles of shearing resistance of backfill material and foundation soil, and the axial stiffness of the reinforcement. A 6m-high wall was modeled, and the facing panels were taken as full-length panels with nominal thickness. Reinforcement was modeled as cable elements (two-dimensional structural elements). Interfaces were considered between soil and wall, and soil and reinforcement.

Keywords: back-to-back walls, numerical modeling, reinforced wall, settlement

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Authors: Selamawit Dires, Solomon Tesfamariam, Thomas Tannert

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Modern earthquake engineering and design encompass performance-based design philosophy. The main objective in performance-based design is to achieve a system performing precisely to meet the design objectives so to reduce unintended seismic risks and associated losses. Energy-based earthquake-resistant design is one of the design methodologies that can be implemented in performance-based earthquake engineering. In energy-based design, the seismic demand is usually described as the ratio of the hysteretic to input energy. Once the hysteretic energy is known as a percentage of the input energy, it is distributed among energy-dissipating components of a structure. The hysteretic to input energy ratio is highly dependent on the inherent damping of a structural system. In numerical analysis, damping can be modeled as stiffness-proportional, mass-proportional, or a linear combination of stiffness and mass. In this study, the effect of mathematical modeling of damping on the estimation of seismic energy demands is investigated by considering elastic-perfectly-plastic single-degree-of-freedom systems representing short to long period structures. Furthermore, the seismicity of Vancouver, Canada, is used in the nonlinear time history analysis. According to the preliminary results, the input energy demand is not sensitive to the type of damping models deployed. Hence, consistent results are achieved regardless of the damping models utilized in the numerical analyses. On the other hand, the hysteretic to input energy ratios vary significantly for the different damping models.

Keywords: damping, energy-based seismic design, hysteretic energy, input energy

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Authors: Akinyemi Tomiwa

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The microstructure of rainfall is important for predicting and modeling various environmental processes, such as rainfall interception by vegetation, soil erosion, and radar signals in rainfall. This rain microstructure was studied with a vertically pointing Micro Rain Radar (MRR) located at a tropical location in Akure South West Nigeria (7o 15’ N, 5o 15’ E). This research utilizes two years of data (2018 and 2019), and the data obtained comprises rainfall parameters such as Rain rates, radar reflectivity, liquid water content, fall velocity and Drop Size Distribution (DSD) based on vertical profiles. The measurement and variations of rain microstructure of these parameters with heights for different rain types were presented from ground level up to the height of 4800 m at 160 m range gates. It has been found that the convective, stratiform and mixed, which are the three major rain types, have different rain microstructures at different heights and were evaluated in this research. The correlation coefficient and the regression line equation were computed for each rain event. The highest rain rate and liquid water content were observed within the height range of 160-4800. It was found that a good correlation exists between the measured parameters. Hence it shows that specific liquid water content increases with increasing rain rate for both stratiform and convective rain types in this part of the world. The results can be very useful for a better understanding of rain structure over tropical regions.

Keywords: rain microstructure, drop size distribution, rain rates, stratiform, convective.

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Authors: Chien-Hung Liu, Yu-Fen Chen

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This study used triangular laser probe and three-axial direction mobile platform for surface measurement, programmed it and applied it to real-time analytic statistics of different measured data. This structure was used to design a system integration program: using triangular laser probe for scattering or reflection non-contact measurement, transferring the captured signals to the computer through RS-232, and using RS-485 to control the three-axis platform for a wide range of measurement. The data captured by the laser probe are formed into a 3D surface. This study constructed an optical measurement application program in the concept of visual programming language. First, the signals are transmitted to the computer through RS-232/RS-485, and then the signals are stored and recorded in graphic interface timely. This programming concept analyzes various messages, and makes proper presentation graphs and data processing to provide the users with friendly graphic interfaces and data processing state monitoring, and identifies whether the present data are normal in graphic concept. The major functions of the measurement system developed by this study are thickness measurement, SPC, surface smoothness analysis, and analytical calculation of trend line. A result report can be made and printed promptly. This study measured different heights and surfaces successfully, performed on-line data analysis and processing effectively, and developed a man-machine interface for users to operate.

Keywords: laser probe, non-contact measurement, triangulation measurement principle, statistical process control, labVIEW

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Authors: Nkereke Mfon Essien

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In an ambisyllabic environment, one consonant sound simultaneously assumes both the coda and onset positions of a word due to its structural proclivity to affect two phonological processes or repair two ill-formed sequences in those syllable positions at the same time. This study sets out to examine the structural conditions that trigger this not-so-common phonological privilege for consonant sounds in the English language and Nigerian English and if such constraints could have any correspondence in the language studied. Data for the study were obtained from a native speaker of English who was the control and twenty (20) educated Nigerian speakers of English from the three ethnic/linguistic groups in Nigeria. Preliminary findings from the data show that ambisyllabicity in English is triggered mainly by stress, a condition which causes a consonant in a stressed syllable to become glottalised and simultaneously devoices the nearest voiced consonant in the next syllable. For example, in the word coupler,/'kʌplɜr/ is realized as ['kʌˀpl̥ɜr]. In some Nigerian English, preliminary findings show that ambisyllabicity is triggered by a sequence of intervocalic short, high central vowels and a coda nasal. Since the short vowel may not occur in an open syllable, the nasal serves to close the impermissible open syllable. However, since the Nigerian English foot structure does not permit a CVC.V syllable, the same coda nasal simultaneously repairs the impermissible syllable foot to (CV.CV) by applying the Maximal Onset Principle since this is a preliminary investigation, a conclusion would not suffice yet.

Keywords: ambisyllabicity, nasal, coda, stress, phonological process, syllable, foot

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Authors: Ya-Ting Liao, Chien-Chang Huang

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Green diesel is a renewable biofuel obtained from plant oil or fatty acid deoxygenation. Because the molecular structure of green diesel is similar to that of fossil fuel, green diesel can be directly used in present vehicle engines without blending with fossil fuel. In this study, mesoporous carbon-based catalysts with doped metal ions, such as Mg, Ni, or Fe, were prepared using co-polymers and gallic acid as molecular templates and carbon sources, respectively. The prepared catalysts were then applied to carry out the deoxygenation of fatty acid and waste cooking oil. To obtain the highest net energy from the produced green diesel, the catalyzed deoxygenation reaction and catalyst preparation processes were carried out under ambient conditions, respectively, to avoid using H₂ as a reagent and reducing agent. XRD, BET, SEM, EDS, FT-IR, and pyridine-IR characterized the composition and configuration of the prepared catalyst. The results display that the doped metal ions were well-dispersed in the carbon-based catalyst and the surface of the catalysts was rich in Lewis acid sites after the catalysts were calcined at the proper temperature. The pore size present on the catalyst was 9-11 nm. To catalyze the deoxygenation of fatty acid by the prepared catalysts at 320℃ under H₂-free conditions, high fatty acid conversion (99%) and high selectivity for hydrocarbons (78%) were obtained when the ratio of doped Ni to doped Mg was optimized.

Keywords: ordered mesoporous carbon, catalysts, hydrocarbons, deoxygenation

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Authors: Samba Lamine Cisse, Cheick Oumar Tangara, Seynabou Sissoko, Mahamadou Diakite, Seydou Doumbia

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Background: Financial management of a scientific research center is a crucial element in achieving ambitious scientific goals. It can be a driving force for research success, but it also has shortcomings that are important to understand. This study focuses on the crucial aspects of financial management in the context of scientific research centers, more specifically the USTTB (UCRC) in Mali in terms of strengths and weaknesses. Methodology: This study concerns the case of the UCRC, one of the USTTB's research centers. It is a qualitative study based on years of experience in project management at the USTTB, and on analyses and interpretations of everyday activities. Result: It offers practical recommendations for improving the financial stability of research institutions, thereby contributing to their mission of promoting scientific research and innovation. Scientific research centers play a crucial role in the development of knowledge, and their effective operation largely depends on the appropriate management of their financial resources. It begins with an in-depth analysis of UCRC's typical financial structure, highlighting its types and sources of funding, followed by an analysis of the strengths and weaknesses of its current financial management system. Conclusion: Financial management of a scientific research center is essential to ensure the continuity of research activities, the development of innovative projects and the achievement of scientific objectives. Adaptive financial management focused on efficiency, diversification of funding and risk control. They are essential to meeting these challenges and fostering excellence in scientific research.

Keywords: financial, management, strengths, weaknesses, recommendations

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Authors: Delphine Vendryes, Dushyanth Sekhar, Baojia Tong, Matthew Theisen, Chester Curme

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Much of the data that inform the decisions of governments, corporations and individuals are harvested from unstructured documents. Data extraction is defined here as a process that turns non-machine-readable information into a machine-readable format that can be stored, for instance, in a database. In financial services, introducing more automation in data extraction pipelines is a major challenge. Information sought by financial data consumers is often buried within vast bodies of unstructured documents, which have historically required thorough manual extraction. Automated solutions provide faster access to non-machine-readable datasets, in a context where untimely information quickly becomes irrelevant. Data quality standards cannot be compromised, so automation requires high data integrity. This multifaceted task is broken down into smaller steps: ingestion, table parsing (detection and structure recognition), text analysis (entity detection and disambiguation), schema-based record extraction, user feedback incorporation. Selected intermediary steps are phrased as machine learning problems. Solutions leveraging cutting-edge approaches from the fields of computer vision (e.g. table detection) and natural language processing (e.g. entity detection and disambiguation) are proposed.

Keywords: computer vision, entity recognition, finance, information retrieval, machine learning, natural language processing

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Authors: Rahmat Ali, Amjad Naseer, Abid A. Shah

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This paper is an attempt to presents the performance of building observed during 26th Oct, 2015 earthquake in District Swat and Shangla region. Most of the buildings in the earthquake hit areas were built with Rubble stone masonry, dress Stone Masonry, brick masonry with and without RC column, Brick masonry with RC beams and column, Block Masonry with and without RC column. It was found that most of the buildings were built without proper supervision and without following any codes. A majority of load bearing masonry walls were highly affected during the earthquake. The load bearing walls built with rubble stone masonry were collapsed resulting huge damages and loss of property and life. Load bearing bricks masonry walls were also affected in most of the region. In some residential buildings the bricks were crushed in a single brick walls. Severe cracks were also found in double brick masonry walls. In RC frame structure beams and columns were also seriously affected. A majority of building structures were non-engineered. Some buildings designed by unskilled local consultants were also affected during the earthquake. Several architectural and structural mistakes were also found in various buildings designed by local consultant. It was found that the structures were collapsed prematurely either because of unskillful labor and using substandard materials or avoiding delicate repair, maintenance, and health monitoring activities because of lack of available sophisticated technology in our country.

Keywords: cracks, collapse, earthquake, masonry, repair

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Authors: Ubeyd Toçoğlu, Miraç Alaf, Hatem Akbulut

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We present a work which was conducted in order to improve the cycle life of silicon based lithium ion battery anodes by utilizing novel composite structure. In this study, carbon coated nano sized (50-100 nm) silicon particles were embedded into Graphene/MWCNT silicon matrix to produce free standing silicon based electrodes. Also, conventional Si powder anodes were produced from Si powder slurry on copper current collectors in order to make comparison of composite and conventional anode structures. Free –standing composite anodes (binder-free) were produced via vacuum filtration from a well dispersion of Graphene, MWCNT and carbon coated silicon powders. Carbon coating process of silicon powders was carried out via microwave reaction system. The certain amount of silicon powder and glucose was mixed under ultrasonication and then coating was conducted at 200 °C for two hours in Teflon lined autoclave reaction chamber. Graphene which was used in this study was synthesized from well-known Hummers method and hydrazine reduction of graphene oxide. X-Ray diffraction analysis and RAMAN spectroscopy techniques were used for phase characterization of anodes. Scanning electron microscopy analyses were conducted for morphological characterization. The electrochemical performance tests were carried out by means of galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy.

Keywords: graphene, Li-Ion, MWCNT, silicon

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Authors: M. A. Kassim, R. Potumarthi, A. Tanksale, S. C. Srivatsa, S. Bhattacharya

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Enzymatic saccharification of biomass for reducing sugar production is one of the crucial processes in biofuel production through biochemical conversion. In this study, enzymatic saccharification of dilute potassium hydroxide (KOH) pre-treated Tetraselmis suecica biomass was carried out by using cellulase enzyme obtained from Trichoderma longibrachiatum. Initially, the pre-treatment conditions were optimised by changing alkali reagent concentration, retention time for reaction, and temperature. The T. suecica biomass after pre-treatment was also characterized using Fourier Transform Infrared Spectra and Scanning Electron Microscope. These analyses revealed that the functional group such as acetyl and hydroxyl groups, structure and surface of T. suecica biomass were changed through pre-treatment, which is favourable for enzymatic saccharification process. Comparison of enzymatic saccharification of untreated and pre-treated microalgal biomass indicated that higher level of reducing sugar can be obtained from pre-treated T. suecica. Enzymatic saccharification of pre-treated T. suecica biomass was optimised by changing temperature, pH, and enzyme concentration to solid ratio ([E]/[S]). Highest conversion of carbohydrate into reducing sugar of 95% amounted to reducing sugar yield of 20 (wt%) from pre-treated T. suecica was obtained from saccharification, at temperature: 40°C, pH: 4.5 and [E]/[S] of 0.1 after 72 h of incubation. Hydrolysate obtained from enzymatic saccharification of pretreated T. suecica biomass was further fermented into biobutanol using Clostridium saccharoperbutyliticum as biocatalyst. The results from this study demonstrate a positive prospect of application of dilute alkaline pre-treatment to enhance enzymatic saccharification and biobutanol production from microalgal biomass.

Keywords: microalgal biomass, enzymatic saccharification, biobutanol, fermentation

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Authors: Qijiao He

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MicroElectrical-Mechanical System (MEMS) is one of the most rapidly developing frontier research field both in theory study and applied technology. Micro-channel is a very important link component of MEMS. With the research and development of MEMS, the size of the micro-devices and the micro-channels becomes further smaller. Compared with the macroscale flow, the flow characteristics of gas in the micro-channel have changed, and the rarefaction effect appears obviously. However, for the rarefied gas and microscale flow, Navier-Stokes-Fourier (NSF) equations are no longer appropriate due to the breakup of the continuum hypothesis. A Nonlinear Coupled Constitutive Model (NCCM) has been derived from the Boltzmann equation to describe the characteristics of both continuum and rarefied gas flows. We apply the present scheme to simulate continuum and rarefied gas flows in a micro-channel structure. And for comparison, we apply other widely used methods which based on particle simulation or direct solution of distribution function, such as Direct simulation of Monte Carlo (DSMC), Unified Gas-Kinetic Scheme (UGKS) and Lattice Boltzmann Method (LBM), to simulate the flows. The results show that the present solution is in better agreement with the experimental data and the DSMC, UGKS and LBM results than the NSF results in rarefied cases but is in good agreement with the NSF results in continuum cases. And some characteristics of both continuum and rarefied gas flows are observed and analyzed.

Keywords: continuum and rarefied gas flows, discontinuous Galerkin method, generalized hydrodynamic equations, numerical simulation

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Authors: Arth J. Shah, Madhu R. Kamble

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Voice biometric liveness detection is customized to certify an authentication process of the voice data presented is genuine and not a recording or synthetic voice. With the rise of deepfakes and other equivalently sophisticated spoofing generation techniques, it’s becoming challenging to ensure that the person on the other end is a live speaker or not. Voice Liveness Detection (VLD) system is a group of security measures which detect and prevent voice spoofing attacks. Motivated by the recent development of the Kolmogorov-Arnold Network (KAN) based on the Kolmogorov-Arnold theorem, we proposed KAN for the VLD task. To date, multilayer perceptron (MLP) based classifiers have been used for the classification tasks. We aim to capture not only the compositional structure of the model but also to optimize the values of univariate functions. This study explains the mathematical as well as experimental analysis of KAN for VLD tasks, thereby opening a new perspective for scientists to work on speech and signal processing-based tasks. This study emerges as a combination of traditional signal processing tasks and new deep learning models, which further proved to be a better combination for VLD tasks. The experiments are performed on the POCO and ASVSpoof 2017 V2 database. We used Constant Q-transform, Mel, and short-time Fourier transform (STFT) based front-end features and used CNN, BiLSTM, and KAN as back-end classifiers. The best accuracy is 91.26 % on the POCO database using STFT features with the KAN classifier. In the ASVSpoof 2017 V2 database, the lowest EER we obtained was 26.42 %, using CQT features and KAN as a classifier.

Keywords: Kolmogorov Arnold networks, multilayer perceptron, pop noise, voice liveness detection

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Authors: Saad M. Darwish, Magda M. Madbouly, Murad B. Khorsheed

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Sign Languages (SL) are the most accomplished forms of gestural communication. Therefore, their automatic analysis is a real challenge, which is interestingly implied to their lexical and syntactic organization levels. Hidden Markov models (HMM’s) have been used prominently and successfully in speech recognition and, more recently, in handwriting recognition. Consequently, they seem ideal for visual recognition of complex, structured hand gestures such as are found in sign language. In this paper, several results concerning static hand gesture recognition using an algorithm based on Type-2 Fuzzy HMM (T2FHMM) are presented. The features used as observables in the training as well as in the recognition phases are based on Singular Value Decomposition (SVD). SVD is an extension of Eigen decomposition to suit non-square matrices to reduce multi attribute hand gesture data to feature vectors. SVD optimally exposes the geometric structure of a matrix. In our approach, we replace the basic HMM arithmetic operators by some adequate Type-2 fuzzy operators that permits us to relax the additive constraint of probability measures. Therefore, T2FHMMs are able to handle both random and fuzzy uncertainties existing universally in the sequential data. Experimental results show that T2FHMMs can effectively handle noise and dialect uncertainties in hand signals besides a better classification performance than the classical HMMs. The recognition rate of the proposed system is 100% for uniform hand images and 86.21% for cluttered hand images.

Keywords: hand gesture recognition, hand detection, type-2 fuzzy logic, hidden Markov Model

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Authors: Can Otuzbir

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It is one of the most difficult areas of civil engineering to provide long-lasting structures with the rapid development of concrete and reinforced concrete structures. Concrete is a living material, and the structure where the concrete is located is constantly exposed to external influences. One of these effects is reinforcement corrosion. Reinforcement corrosion of reinforced concrete structures leads to a significant decrease in the carrying capacity of the structural elements, as well as reduced service life. It is undesirable that the service life should be completed sooner than expected. In recent years, advances in glass fiber technology and its use with concrete have developed rapidly. As a result of inability to protect steel reinforcements against corrosion, fiberglass reinforcements have started to be investigated as an alternative material to steel reinforcements, and researches and experimental studies are still continuing. Glass fiber reinforcements have become an alternative material to steel reinforcement because they are resistant to corrosion, lightweight and simple to install compared to steel reinforcement. Glass fiber reinforcements are not corroded and have higher tensile strength, longer life, lighter and insulating properties compared to steel reinforcement. In experimental studies, glass fiber reinforcements have been shown to show superior mechanical properties similar to beams produced with steel reinforcement. The performance of long-term use of glass fiber fibers continues with accelerated experimental studies.

Keywords: glass fiber polymer reinforcement, steel fiber concrete, ultra high performance concrete, bending, GFRP

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Authors: Kane Esien, Eadaoin McCourt, Peter Nockemann, Soveig Felton

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Magnetic ionic liquids (MILs) are a class of ionic liquid incorporating one or more magnetic atoms into the anion or cation of the ionic liquid, endowing the ionic liquid with magnetic properties alongside the existing properties of ionic liquids. MILs have applications in e.g. fluid-fluid separations, electrochemistry, and polymer chemistry. In this study three different types of Bis-Lanthanoates, that exist in different phases, have been synthesised and characterised (Ln = lanthanide): 1) imidazolium lanthanide acetate – [C4Mim]2[Ln2(OAc)8] – forms a crystalline solid at room temperature, 2) phosphonium lanthanide acetate – [P666 14]2[Ln2(OAc)8] – is in a solid glassy state, and 3) phosphonium lanthanide octanoate – [P666 14]2[Ln2(Oct)8] – is an ionic liquid. X-ray diffraction of the crystalline solid imidazolium lanthanide acetate – [C4Mim]2[Ln2(OAc)8] confirm that the Ln(III) ions form dimers, bridged by carboxyl groups, but cannot yield information about samples phosphonium lanthanide acetate – [P666 14]2[Ln2(OAc)8] (glass) and phosphonium lanthanide octanoate – [P666 14]2[Ln2(Oct)8] (ionic liquid) since these lack long-range order. SQUID magnetometry studies show that all three samples have effective magnetic moments consistent with non-interacting Ln(III) ions at room temperature but deviate from this behavior in the same way below 50 K. Through modeling the magnetic response, we are able to show that we have formed magnetic dimers, in all compounds, that are weakly antiferromagnetically interacting

Keywords: dimeric ionic liquids, interactions, SQUID, structure

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Authors: Q. Toufeeq, R. Kauser, U. R. Jamil, N. Sohaib

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Foundation design of a structure needs soil investigation to avoid failures due to settlements. This soil investigation is expensive and time-consuming. Developments of new residential societies involve huge leveling of large sites that is accompanied by heavy land filling. Poor practices of land fill for deep depths cause differential settlements and consolidations of underneath soil that sometimes result in the collapse of structures. The extent of filling remains unknown to the individual developer unless soil investigation is carried out. Soil investigation cannot be performed on each available site due to involved costs. However, fair estimate of bearing capacity can be made if such tests are already done in the surrounding areas. The geotechnical guidance maps can provide a fair assessment of soil properties. Previously, GIS-based approaches have been used to develop maps using extrapolation and interpolations techniques for bearing capacities, underground recharge, soil classification, geological hazards, landslide hazards, socio-economic, and soil liquefaction mapping. Standard penetration test (SPT) data of surrounding sites were already available. Google Earth is used for digitization of collected data. Few points were considered for data calibration and validation. Resultant Geographic information system (GIS)-based guidance maps are helpful to anticipate the bearing capacity in the real estate industry.

Keywords: bearing capacity, soil classification, geographical information system, inverse distance weighted, radial basis function

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Authors: Sanjeev Kumar Raghuwanshi, Yadvendra Singh

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The objective of this paper is to develop and optimize the Fiber Bragg (FBG) grating based Surface Plasmon Resonance (SPR) sensor for monitoring the hazardous toxic chemicals and gases in underground mines or any industrial area. A fully cladded telecommunication standard FBG is proposed to develop to produce surface plasmon resonance. A thin few nm gold/silver film (subject to optimization) is proposed to apply over the FBG sensing head using e-beam deposition method. Sensitivity enhancement of the sensor will be done by adding a composite nanostructured Graphene Oxide (GO) sensing layer using the spin coating method. Both sensor configurations suppose to demonstrate high responsiveness towards the changes in resonance wavelength. The GO enhanced sensor may show increased sensitivity of many fold compared to the gold coated traditional fibre optic sensor. Our work is focused on to optimize GO, multilayer structure and to develop fibre coating techniques that will serve well for sensitive and multifunctional detection of hazardous chemicals. This research proposal shows great potential towards future development of optical fiber sensors using readily available components such as Bragg gratings as highly sensitive chemical sensors in areas such as environmental sensing.

Keywords: surface plasmon resonance, fibre Bragg grating, sensitivity, toxic gases, MATRIX method

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Authors: Satyabrata Bera, Mintu Mondal

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Two-dimensional (2D) ferromagnetic materials have garnered significant attention due to their potential to host intriguing scientific phenomena such as the anomalous Hall effect, anomalous Nernst effect, and high transport spin polarization. This study focuses on the investigation of air-stable van der Waals(vdW) ferromagnets, FeGeTe₂ (FₙGT with n = 3, 4, and 5). Particular emphasis is placed on the Fe4GeTe2 (F4GT) compound, which exhibits a complex and fascinating magnetic behavior characterized by two distinct transitions: (i) paramagnetic (PM) to ferromagnetic (FM) around T C ∼ 270 K, and (ii) another spins reorientation transition (SRT) at T SRT ∼ 100 K . Scaling analysis of magnetocaloric effect confirms the second-order character of the ferromagnetic transition, while the same analysis at T SRT suggests that SRT is first-order phase transition. Moreover, the F4GT exhibits a large anomalous Hall conductivity (AHC), ∼ 490 S/cm at 2 K . The near-quadratic behavior of the anomalous Hall resistivity with the longitudinal resistivity suggests that a dominant AHC contribution arises from an intrinsic Berry curvature (BC) mechanism. Electronic structure calculations reveal a significant BC resulting from SOC-induced gapped nodal lines around the Fermi level, thereby giving rise to large AHC. Additionally, we reported exceptionally large anomalous Hall angle (≃ 10.6%) and Hall factor (≃ 0.22 V −1 ) values, the largest observed within this vdW family. The findings presented here, provide valuable insights into the fascinating magnetic and transport properties of 2D ferromagnetic materials, in particular, FₙGT family.

Keywords: 2D vdW ferromagnet, spin reorientation transition, anomalous hall effect, berry curvature

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Authors: Parul Grover, K. A. Suri, Raj Kumar, Gulshan Bansal

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Background: Nyctanthes arbortristis Linn is traditionally used as anticancer herb in Indian system of medicine, but its introduction into modern system of medicine is still awaited due to lack of systematic scientific studies. Objective: The objective of the present study was to isolate and characterize anticancer phytoconstituents from N. arbortristis L. leaves based on bioactivity guided fractionation. Method: Different extracts of the leaves of the plant were prepared by Soxhlet extractor. Each extract was evaluated for anticancer activity against HL-60 cell lines. Chloroform and HA extract showed potent anticancer activity and hence were selected for fractionation. Fraction C1 from chloroform extract was found to be most potent amongst all when tested against three cell lines (HL-60, A-549, and HCT-116) and thus was selected for further fractionation and a pure compound CP-01 was isolated. RP-HPLC method has been developed for quantification of isolated compound by using Kinetex C-18 column with gradient elution at 0.7 mL/min using mobile phase containing potassium dihydrogen phosphate (0.01 M, pH 3.0) with acetonitrile. The wavelength of maximum absorption (λₘₐₓ) selected was 210 nm. Results: The structure of potent anticancer CP-01 was determined on the basis spectroscopic methods like IR, 1H-NMR, ¹³C-NMR and Mass Spectrometry and it was characterized as 1,1,2-tris(2’,4’-di-tert-butylbenzene)-4,4-dimethyl-pent-1-ene. The content of CP-01 was found to be 0.88 %w/w of chloroform extract and 0.08 %w/w of N.arbortristis leaves. Conclusion: The study supports the traditional use of N. arbortristis as anticancer herb & the identified compound CP-01 can serve as an excellent lead to develop potent and safe anticancer drugs.

Keywords: anticancer, HL-60 cell lines, Nyctanthes arbor-tristis, RP-HPLC

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Authors: Farzad Tofigh, Saeideh Najafi, Reza Heidari, Rashid Jamei

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In order to study the effects of magnetic field on the root system and growth of Phaseolus vulgaris, an experiment was conducted in 2012. The possible involvement of magnetic field (MF) pretreatment in physiological factors of Phaseolus vulgaris was investigated. Seeds were subjected to 10 days with 1.8 mT of magnetic field for 1h per day. MF pretreatment decreased the plant height, fresh and dry weight, length of root and length of shoot, Chlorophyll a, Chlorophyll b and carotenoid in 10 days old seedling. In addition, activity of enzymes such as Catalase and Guaiacol peroxidase was decreased due to MF exposure. Also, the total Protein and DPPH content of the treated by magnetic field was not significantly changed in compare to control groups, while the flavonoid, Phenol and prolin content of the treated of the treated by magnetic field was significantly changed in compare to control groups. Lateral branches of roots and secondary roots increased with MF. The results suggest that pretreatment of this MF plays important roles in changes in crop productivity. In all cases there was observed a slight stimulating effect of the factors examined. The growth dynamics were weakened. The plants were shorter. Moreover, the effect of a magnetic field on the crop of Phaseolus vulgaris and its structure was small.

Keywords: carotenoid, chlorophyll a, chlorophyll b, DPPH, enzymes, flavonoid, germination, growth, phenol, proline, protein, magnetic field

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Authors: Chrysanthos Maraveas, Argiris Plesias, Garyfalia G. Triantafyllou, Konstantinos Petronikolos

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The current paper presents a structural assessment and proposals for retrofit of the National Youth Foundation Building, an existing reinforced concrete (RC) building in the city of Igoumenitsa, Greece. The building is scheduled to be renovated in order to create a Municipal Cultural Center. The bearing capacity and structural integrity have been investigated in relation to the provisions and requirements of the Greek Retrofitting Code (KAN.EPE.) and European Standards (Eurocodes). The capacity of the existing concrete structure that makes up the two central buildings in the complex (buildings II and IV) has been evaluated both in its present form and after including several proposed architectural interventions. The structural system consists of spatial frames of columns and beams that have been simulated using beam elements. Some RC elements of the buildings have been strengthened in the past by means of concrete jacketing and have had cracks sealed with epoxy injections. Static-nonlinear analysis (Pushover) has been used to assess the seismic performance of the two structures with regard to performance level B1 from KAN.EPE. Retrofitting scenarios are proposed for the two buildings, including type Λ steel bracings and placement of concrete shear walls in the transverse direction in order to achieve the design-specification deformation in each applicable situation, improve the seismic performance, and reduce the number of interventions required.

Keywords: earthquake resistance, pushover analysis, reinforced concrete, retrofit, strengthening

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Authors: Eman A. Alghamdi, A. M. Aldhafiri

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It was found that the induce an isolated dopant close to the middle of the bandgap by occupying the Cd position in the CdTe lattice structure is an efficient factor in reducing the nonradiative recombination rate and increasing the solar efficiency. According to our laboratory results, this work has been carried out to obtain the effect of substrate temperature on the CdTe0.6Sn0.4 prepared by thermal evaporation technique for photovoltaic application. Various substrate temperature (25°C, 100°C, 150°C, 200°C, 250°C and 300°C) was applied. Sn-doped CdTe thin films on a glass substrate at a different substrate temperature were made using CdTe and SnTe powders by the thermal evaporation technique. The structural properties of the prepared samples were determined using Raman, x-Ray Diffraction. Spectroscopic ellipsometry and spectrophotometric measurements were conducted to extract the optical constants as a function of substrate temperature. The structural properties of the grown films show hexagonal and cubic mixed structures and phase change has been reported. Scanning electron microscopy (SEM) reviled that a homogenous with a bigger grain size was obtained at 250°C substrate temperature. The conductivity measurements were recorded as a function of substrate temperatures. The open-circuit voltage was improved by controlling the substrate temperature due to the improvement of the fundamental material issues such as recombination and low carrier concentration. All the result was explained and discussed on the biases of the influences of the Sn dopant and the substrate temperature on the structural, optical and photovoltaic characteristics.

Keywords: CdTe, conductivity, photovoltaic, ellipsometry

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Authors: W. Sornlar, S. Supothina, A. Wannagon

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Lightweight geopolymer can be prepared by using some foaming agents, such as metal powders or hydrogen peroxide; however, it is difficult to control the generated cell size due to the high reactivity of the system. This study aims to investigate the influence of Sodium Lauryl Ether Sulfate (SLES) foam addition and curing temperature on the physical, mechanical, thermal, and microstructure behaviors of the lightweight kaolinite-based geopolymer. To provide porous structure, the geopolymer paste was mixed with 0-15 wt% of SLES foam before casting into the mold. Testing and characterizations were carried out after 28 days. The results showed that SLES foam generated the regular and spherical macropores, which were well distributed in the geopolymer samples. The total porosity increased as SLES foam increased, similarly as the apparent porosity and water absorption. On the other hand, the bulk density and mechanical strength decreased as SLES foam increased. Curing temperature was studied simultaneously due to it strongly affects the mechanical strength of geopolymer. In this study, rising of curing temperature from 27 to 50°C (at 75% relative humidity) improved the compressive strength of samples but deteriorated after curing at 60°C. Among them, the composition of 15 wt% SLES foam (NF15) presented the highest porosity (70.51-72.89%), the lowest density (0.68-0.73 g/cm³), and very low thermal conductivity (0.172-0.197 W/mK). It had the proper compressive strength of 4.21-4.74 MPa that can be applied for the thermal insulation.

Keywords: lightweight, kaolinite-based geopolymer, curing temperature, foaming agent, thermal conductivity

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Authors: Ogunniran Kehinde Olurotimi, Adekoya Joseph, Ehi-Eromosele Cyril, Mehdi Shihab, Mesubi Adediran, Tadigoppula Narender

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Nicotinic acid hydrazide and 2,4-dihydoxylbenzaldehyde were condensed at 20°C to form an acylhydrazone (H3L) with ONO coordination pattern. The structure of the acylhydrazone was elucidated by using CHN analyzer, ESI mass spectrometry, IR, 1H NMR, 13C NMR and 2D NMR such as COSY and HSQC. Thereafter, five novel metal complexes [Mn(II), Fe(II), Pt(II) Zn(II) and Pd(II)] of the hydrazone ligand were synthesized and their structural characterization were achieved by several physicochemical methods, namely elemental analysis, electronic spectra, infrared, EPR, molar conductivity and powder X-ray diffraction studies. Structural geometries of some of the compounds were supported by using Hyper Chem-8 program for the molecular mechanics and semi-empirical calculations. The stability energy (E) and electron potentials (eV) for the frontier molecules were calculated by using PM3 method. An octahedral geometry was suggested for both Pd(II) and Zn(II) complexes while both Mn(II) and Fe(II) complexes conformed with tetrahedral pyramidal. However, Pt(II) complex agreed with tetrahedral geometry. In vitro antitubercular activity study of the ligand and the metal complexes were evaluated against Mycobacterium tuberculosis, H37Rv, by using micro-diluted method. The results obtained revealed that (PtL1) (MIC = 0.56 µg/mL), (ZnL1) (MIC = 0.61 µg/mL), (MnL1) (MIC = 0.71 µg/mL) and (FeL1) (MIC = 0.82 µg/mL), exhibited a significant activity when compared with first line drugs such as isoniazid (INH) (MIC = 0.9 µg/mL). H3L1 exhibited lesser antitubercular activity with MIC value of 1.02 µg/mL. However, the metal complexes displayed higher cytoxicity but were found to be non-significant different (P ˂ 0.05) to isoniazid drug.

Keywords: hydrazones, electron spin resonance, thermogravimetric, powder X-ray diffraction, antitubercular agents

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Authors: Zekun Lin, Xun Li

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Silicon photonics has gained much interest and extensive research for a promising aspect for fabricating compact, high-speed and low-cost photonic devices compatible with complementary metal-oxide-semiconductor (CMOS) process. Despite the remarkable progress made on the development of silicon photonics, high-performance, cost-effective, and reliable silicon laser sources are still missing. In this work, we present a 1550 nm III-V/silicon laser design with stable single-mode lasing property and robust and high-efficiency vertical coupling. The InP cavity consists of two uniform Bragg grating sections at sides for mode selection and feedback, as well as a central second-order grating for surface emission. A grating coupler is etched on the SOI waveguide by which the light coupling between the parallel III-V and SOI is reached vertically rather than by evanescent wave coupling. Laser characteristic is simulated and optimized by the traveling-wave model (TWM) and a Green’s function analysis as well as a 2D finite difference time domain (FDTD) method for the coupling process. The simulation results show that single-mode lasing with SMSR better than 48dB is achievable, and the threshold current is less than 15mA with a slope efficiency of around 0.13W/A. The coupling efficiency is larger than 42% and possesses a high tolerance with less than 10% reduction for 10 um horizontal or 15 um vertical dislocation. The design can be realized by standard flip-chip bonding techniques without co-fabrication of III-V and silicon or precise alignment.

Keywords: III-V/silicon integration, silicon photonics, single mode laser, vertical coupling

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Authors: Nadir Ali Mugheri, Shaukat Ali Lohar

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In a multilingual society like Pakistan, code switching is commonly observed in different contexts. Mostly people use L1 (Native Languages) and L2 for common communications and L3 (i.e. English, Urdu, Sindhi) in formal contexts and for academic writings. Such a frequent code switching does affect EFL learners' acquisition of grammar and lexis of the target language which in the long run result in different types of errors in their writings. The current study is to investigate and identify common elements of L1 and L2 (spoken by students of the Universities in Pakistan) which create hindrances for EFL learners. Case study method was used for this research. Formal writings of 400 EFL learners (as participants from various Universities of the country) were observed. Among 400 participants, 200 were female and 200 were male EFL learners having different academic backgrounds. Errors found were categorized into different types according to grammatical items, the difference in meanings, structure of sentences and identifiers of tenses of L1 or L2 in comparison with those of the target language. The findings showed that EFL learners in Pakistani varsities have serious problems in their writings and they committed serious errors related to the grammar and meanings of the target language. After analysis of the committed errors, the results were found in the affirmation of the hypothesis that L1 or L2 does affect EFL learners. The research suggests in the end to adopt natural ways in pedagogy like task-based learning or communicative methods using contextualized material so as to avoid impediments of L1 or L2 in acquisition the target language.

Keywords: multilingualism, L2 acquisition, code switching, language acquisition, communicative language teaching

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Authors: Xinyuan Zou, Qihui Tang, Shujian Wang, Yulin Huang, Jie Gui, Xiangping Liu, Gang Liu, Yanqiang Tao

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Childhood trauma can have a long-lasting influence on individuals and contribute to mental disorders, including depression and anxiety. The current study aimed to explore the symptomatic and developmental patterns of depression, anxiety, and stress among adolescents who have suffered from childhood trauma. A total of 3,598 college students (female = 1,617 (44.94%), Mean Age = 19.68, SD Age = 1.35) in China completed the Childhood Trauma Questionnaire (CTQ) and the Depression, Anxiety, and Stress Scales (DASS-21), and 2,337 participants met the selection standard based on the cut-off scores of the CTQ. The symptomatic network and directed acyclic graph (DAG) network approaches were used. The results revealed that males reported experiencing significantly more physical abuse, physical neglect, emotional neglect, and sexual abuse compared to females. However, females scored significantly higher than males on all items of DASS-21, except for “Worthless”. No significant difference between the two genders was observed in the network structure and global strength. Meanwhile, among all participants, “Down-hearted” and “Agitated” appeared to be the most interconnected symptoms, the bridge symptoms in the symptom network, as well as the most vital symptoms in the DAG network. Apart from that, “No-relax” also served as the most prominent symptom in the DAG network. The results suggested that intervention targeted at assisting adolescents in developing more adaptive coping strategies with stress and regulating emotion could benefit the alleviation of comorbid depression, anxiety, and stress.

Keywords: symptom network, childhood trauma, depression, anxiety, stress

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Authors: Naohiro Nakamura

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Analysis methods to accurately estimate the behavior of buildings when earthquakes occur is very important for improving the seismic safety of such buildings. Recently, the use of damping devices has increased significantly and there is a particular need to appropriately evaluate the behavior of buildings with such devices during earthquakes in the design stage. At present, however, the accuracy of the analysis evaluations is not sufficient. One reason is that the accuracy of current analysis methods has not been appropriately verified because there is very limited data on the behavior of actual buildings during earthquakes. Many types of shaking table test of large structures are performed at the '3-Dimensional Full-Scale Earthquake Testing Facility' (nicknamed 'E-Defense') operated by the National Research Institute of Earth Science and Disaster Prevention (NIED). In this study, simulations using 3- dimensional analysis models were conducted on shaking table test of a 5-story steel-frame structure with dampers. The results of the analysis correspond favorably to the test results announced afterward by the committee. However, the suitability of the parameters and models used in the analysis and the influence they had on the responses remain unclear. Hence, we conducted additional analysis and studies on these models and parameters. In this paper, outlines of the test are shown and the utilized analysis model is explained. Next, the analysis results are compared with the test results. Then, the additional analyses, concerning with the hysteresis curve of the dampers and the beam-end stiffness of the frame, are investigated.

Keywords: three-dimensional analysis, E-defense, full-scale experimen, vibration control damper

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Authors: Zahra Bakhtiari

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Middle East countries confront a multitude of main environmental challenges which are inevitable. The unstable economic and political structure which dominates numerous middle East countries makes it difficult to react effectively to unfavorable climate change impacts. This study applies a qualitative methodology and relies on secondary literature aimed to investigate how countries in the Middle East are balancing economic security and climatic security in terms of budgeting, infrastructure investment, political engagement (domestically through discourses or internationally in terms of participation in international organizations or bargaining, etc.) There has been provided an outline of innovative measures in both economic and environmental fields that are in progress in the Middle East countries and what capacity they have for economic development and environmental adaptation, as well as what has already been performed. The primary outcome is that countries that rely more on infrastructure investment such as negative emissions technologies (NET) through green social capital enterprises and political engagement, especially nationally determined contributions (NDCs) commitments and United Nations Framework Convention on Climate Change (UNFCCC), experience more economic and climatological security balance in the Middle East. Since implementing these measures is not the same in all countries in the region, we see different levels of balance between climate security and economic security. The overall suggestion is that the collaboration of both the bottom-up and top-down approaches helps create strategic environmental strategies which are in line with the economic circumstances of each country and creates the desired balance.

Keywords: climate change, economic growth, sustainability, the Middle East, green economy, renewable energy

Procedia PDF Downloads 81