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Experimental and Numerical Investigation for Estimating Optimal Depth-Bearing Capacity of Randomly Fiber-Reinforced Sandy Soils
Get PDFReinforcing will lead to improved mechanical properties of soil. Using different additives can help to increase bearing capacity, strength, or other important properties. In this study, poorly graded sandy soil was improved by adding synthetic fiber, and a strip footing was placed and loaded on unreinforced and reinforced soil. Samples were prepared in two relative densities of 50% and 65% and the soil was reinforced in 1B, 2B, 2.5B, and 3B depths (B is width of model footing). Bearing capacity and shear failure surfaces of soil that were analyzed by the Particle Image Velocimetry (PIV) method at different settlement to footing width ratios were obtained and compared. At the same time, experimental conditions were modeled with finite element method, and the results of shear failure surfaces were compared with experimental modeling. Results showed that reinforcing the soil under the strip footing forwarded shear failure surfaces toward downer surfaces from 1B up to 3B. In soils with a relative density of 50%, the main reinforcing depth was 2B and after 2B reinforcing did not have a considerable effect on improving the soil. By increasing the relative density from 50% to 65%, the effective reinforcing depth increased from 2B to 2.5B. Experimental and numerical modeling of soil under strip footing showed that the optimum reinforcing depth was between 2B and 2.5B that by increasing the reinforcing depth, the general shear failure behavior went toward local shear failure surfaces. The results of the study can be used as a reinforcing method and applied to real soil improvement applications in industry depending on the purpose of soil reinforcing for economic and efficient improvement design
Composite Attribute Based Ad-hoc On Demand Multipath Distance Vector Routing Protocol (CAB-AOMDV)
Get PDFIn this paper composite attribute-based ad-hoc on demand multipath distance vector (CAB-AOMDV) routing protocol has been proposed. Composite attributes are used to select the optimized multiple path for transmitting data and determined what percentage of total data can be share by the specific path. Composite factor is the combination of two factors, one is drop and another is queue factor. The performance analysis is evaluated under various node densities. Using control-overhead (CO), normalized-routing-overhead and throughput performance of proposed CAB-AOMDV is compared with Risk factor-based Ad-hoc on demand multipath (RF-AOMDV) routing protocol, from where it is observed that performance of proposed CAB-AOMDV is outperform RF-AOMDV in respect of all scenario taken into considerations
A Comparative Study on the Impact of the Capabilities of Manufacturing and Service Firms on Export Performance: Focusing on the Interaction Effect of R&D
Get PDFThis paper empirically examined the impact of firm capabilities and the interaction effect of R&D on the export performance of service firms in comparison with manufacturing firms. To this end, a total of 1,968 Korean firms were analyzed: 243 from service and 1,725 from manufacturing, and two-stage analysis was performed using multiple regression and hierarchical regression analysis. This research confirmed that network and customer capabilities played critical roles in the internationalization of service firms and R&D positively interacted with entrepreneurship and customer capabilities for export performance. These findings suggest valuable policy considerations for government trade policy and academic motivation for further research on the capabilities and R&D of service firms
PCK for Developing Understanding of NOS: A Review of Past Studies
Get PDFThe term ‘Nature of Science’ (NOS) is often used to refer to distinctive characteristics of scientific enterprise and qualities of scientists. An adequate understanding of NOS is crucial for better decision-making and positive scientific attitude. Teachers are expected to develop this understanding among their students for which they themselves require understanding of various aspects of NOS (e.g. scientific knowledge is tentative or science involves creativity). In addition, they need knowledge of how learners’ misconceptions about NOS and scientists can be challenged with the help of appropriate strategies. This knowledge base of teachers is popularly referred to as ‘PCK for NOS’ (Pedagogical Content Knowledge (PCK) for teaching NOS). This knowledge base is complex. How far teachers possess it needs investigation. In the present paper, the authors have provided a review of studies revealing the status of teachers’ PCK for NOS. Firstly, teachers’ understanding of NOS is discussed. Then, the status of science teaching in schools is reviewed. Thereafter, studies specific to PCK for NOS are examined. The factors that influence the teaching of science and NOS are also highlighted. The review reveals that teachers do not understand some important aspects of NOS and hold stereotypical image of scientists. The teaching-learning of science in schools is also not satisfactory and NOS is hardly addressed in science classrooms. However, the intentions and practices of teachers for teaching NOS evidently improve with interventions. Based on the review, the paper concludes that the way science is presented in science classrooms needs to be revisited. It is suggested that Teacher Education Programmes must play their role in developing PCK for NOS among teachers and suitable instruments must be developed for measuring PCK for NOS
Lithium Orthosilicate-Linear Low-Density Polyethylene Nano-Composite as Substrate for High Frequency Devices: Dielectric Characterization
Get PDFDielectric properties of nanosized Lithium Orthosilicate (Li4SiO4) and linear low-density polyethylene composite at X-Band frequencies are investigated, to realize its utility as a substrate for microwave devices. Solid state technique is used to synthesize nano Li4SiO4. To confirm the structural and morphological properties of the synthesized nano Li4SiO4, X-ray diffraction, Fourier transformed infrared spectroscopy and transmission electron microscopy are used. Composites of nano Li4SiO4 and linear low-density polyethylene matrix are synthesized with varying weight fraction of nano Li4SiO4 viz. 2%, 4% and 6%. The lateral portion of a fractured sample (composite) is examined using scanning electron microscope to confirm homogeneous dispersion of nano Li4SiO4 in linear low-density polyethylene matrix. Water absorption measurement of all the composites are carried out based on ASTM D570-98. Densities of the composites are measured via hydrostatic weighing by using Archimedes principle. Complex permittivity and permeability measurement of the composites are recorded by utilizing Nicholson-Ross approach. For all weight fraction of the nano inclusions, the real component of permittivity and dielectric loss tangent of the composites in the X-band are found to be in the range of 2.2 – 2.6 and 10-2 –10-4, respectively. Return losses for the composites are calculated from complex permittivity and permeability values to validate its applicability as substrate for various high frequency applications
Dactylorhiza hatagirea (D. Doon) Soo, an important medicinal herb of the Himalaya and urgent need for its conservation- A review
Get PDFDactylorhiza hatagirea (D. Doon) Soo (Family Orchidaceae) is a terrestrial orchid, native to alpine and sub-alpine zones of Himalaya, well known for medicinal uses because of its immense pharmacological properties and therapeutic potential. Leaves and tubers of the herb finds enormous uses in traditional Indian medicinal system like Ayurveda, Siddha, Unani and Sowa-rigpa for treatment of different ailments like dysentery, diarrhoea, chronic fever, cough, wounds, burns, fractures, stomach-ache, etc. The present review analyses the distribution, medicinal uses, phytochemistry, pharmacology, and conservation status of D. hatagirea. The review is based on literature available on this orchid with an objective to compile and understand diverse medicinal uses among the indigenous Himalayan communities and phytochemical potential in pharmacology. This review also highlights the potential threats faced by this orchid and suggests future conservation prospects and strategies
Combining CEEMDAN with PCA for Effective Cardiac Artefact Suppression from Single-Channel EEG
Get PDFThe large signal due to cardiac activity can easily distort the signals originating from the relatively weak electrical activity of the brain, commonly measured as an Electroencephalogram (EEG). The artifact due to cardiac activity in EEG is called cardiac artifact, which contaminates the EEG data and makes interpretation of the EEG difficult for clinicians. Hence it is crucial to remove the cardiac artifact from EEG data. To suppress the cardiac artifact, we propose a novel approach to effectively extract cardiac artifacts from single-channel contaminated EEG data without using reference Electrocardiogram (EKG) data. The proposed methodology uses Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) to decompose EEG data contaminated by cardiac activity into the Intrinsic Mode Functions (IMFs). Principal Component Analysis (PCA) is performed on these IMFs to obtain the principal components arranged in the order of decreasing variance. Effective cardiac artifact extraction is achieved by optimizing the signal reconstruction process so that only those principal components that capture the cardiac activity are retained with the constraint that distortion introduced in EEG data should be minimum. The comparison clearly shows that the proposed method outperforms conventionally employed methods like wavelet-based approach
Uncertainties in Bistatic RCS Measurements
Get PDFRadar Cross Section (RCS) is a far field parameter and limited test range length produces error in its measurements. RCS measured with co-located Tx and Rx antennas is termed as monostatic RCS and with spatially separated Tx and Rx antennas as Bistatic RCS (BRCS). Interest in BRCS measurements has grown due to increase in use of multi-static Radars for detecting low-observable targets. In literature BRCS measurement techniques explored are either horn antenna based far field setups or Compact Antenna Test Range (CATR) based setups. All the techniques have inherent limitations and errors, which need to be assessed as the information generated plays a decisive role in the design of military platforms. In the present paper, the errors in each measurement technique are obtained through extensive numerical computation and measurements on various canonical as well as complex shapes. The results highlight the effect of the phase curvature in either or both, Tx, and Rx paths, affect the measurement accuracies, thereby limiting the target size and highest frequency of operation of present techniques
Effect of Anatase and Rutile Phase Microspheres Composition on Dye-SensitizedSolar Cell Photoanode Performance
Get PDFThe effect of calcination temperature on the phase stability of solvothermally synthesized mesoporous anatase TiO2 microspheres has been investigated through X-ray diffraction and Raman spectroscopy. Morphological change owing to anatase to rutile phase transformation has been examined by transmission electron microscopy. Dye-sensitized Solar Cell with anatase TiO2 microspheres photoanode exhibits good photovoltaic performance with an overall cell efficiency of 4.47 %. Calcination above 900 °C reduces the efficiency. Incident Photon to Current Conversion Efficiency (IPCE) studies reveals that the TiO2 microspheres calcined at 700 °C have high IPCE due to high dye loading owing to its high surface area and porous structure