Determination of strut efficiency factor for concrete deep beams with and without fibre

Sandeep, M.S.,Nagarajan, Praveen,Shashikala, A.P.,Habeeb, Shehin A. Techno-Press 2016 Advances in computational design Vol.1 No.3

Based on the variation of strain along the cross section, any region in a structural member can be classified into two regions namely, Bernoulli's region (B-region) and Disturbed region (D-region). Since the variation of strain along the cross section for a B-region is linear, well-developed theories are available for their analysis and design. On the other hand, the design of D-region is carried out based on thumb rules and past experience due to the presence of nonlinear strain distribution. Strut-and-Tie method is a novel approach that can be used for the analysis and design of both B-region as well as D-region with equal importance. The strut efficiency factor (${\beta}_s$) is needed for the design and analysis of concrete members using Strut and Tie method. In this paper, equations for finding ${\beta}_s$ for bottle shaped struts in concrete deep beams (a D-region) with and without steel fibres are developed. The effects of transverse reinforcement on ${\beta}_s$ are also considered. Numerical studies using commercially available finite element software along with limited amount of experimental studies were used to find ${\beta}_s$.

Structural characterization of human CRTh2: a combined homology modeling, molecular docking and 3D-QSAR-based in silico approach

Babu, S.,Nagarajan, S. K.,Lee, S. H.,Madhavan, T. Springer Science + Business Media 2016 MEDICINAL CHEMISTRY RESEARCH Vol.25 No.4

<P>Chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTh2) is an important therapeutic target for the treatment of asthma, chronic obstructive pulmonary disease, allergic rhinitis and atopic dermatitis. In this study, we report the binding site analysis of CRTh2 through molecular docking and quantitative structure-activity relationship (QSAR) studies to explore the interaction of 2-(2-(benzylthio)-1H-benzo[d]imidazol-1-yl) acetic acid derivatives. Various comparative models were generated using the available crystal structure of human delta opioid receptor (4N6H) as the template, and benzylthio acetic acid derivatives were docked into the predicted binding site region of human CRTh2 receptor. Surflex docking studies enabled us to identify that K5.43, Y4.60, N185, Y6.51, Q5.36, E6.58, T7.38 and H6.52 residues were the most crucial amino acids interacting with the ligand. In addition to docking, atom-by-atom matching and structure-based 3D-QSAR method CoMFA was performed. Based on better q (2) and r (2) (pred) values, the best predictions were obtained for the ligand-based (q (2) = 0.552, r (2) (pred) = 0.636) and for receptor-based (q (2) = 0.507, r (2) (pred) = 0.541) QSAR model, whose robustness and predictability were verified by external test set validation. The results correlate well with the previously reported mouse model, and our study serves as a guide for mutational studies of human CRTh2 and further experimental investigations on the synthesis of new CRTh2 antagonist.</P>

Effect of Geometrical Parameters on Optimal Design of Synchronous Reluctance Motor

V. S. Nagarajan,V. Kamaraji,M. Balaji,R. Arumugam,N. Ganesh,R. Rahul,M. Lohit 한국자기학회 2016 Journal of Magnetics Vol.21 No.4

Torque ripple minimization without decrease in average torque is a vital attribute in the design of Synchronous Reluctance (SynRel) motor. As the design of SynRel motor is an arduous task, which encompasses many design variables, this work first analyses the significance of the effect of varying the geometrical parameters on average torque and torque ripple and then proposes an extensive optimization procedure to obtain configurations with improved average torque and minimized torque ripple. A hardware prototype is fabricated and tested. The Finite Element Analysis (FEA) software tool used for validating the test results is MagNet 7.6.0.8. Multi Objective Particle Swarm Optimization (MOPSO) is used to determine the various designs meeting the requirements of reduced torque ripple and improved torque performance. The results indicate the efficacy of the proposed methodology and substantiate the utilization of MOPSO as a significant tool for solving design problems related to SynRel motor.

Morphometric evaluation of great vein of Galen and its clinical implications

Grace Suganya. S(Grace Suganya. S ),Ariharan. K(Ariharan. K ),Raveendranath Veeramani(Raveendranath Veeramani ),Dinesh Kumar. V(Dinesh Kumar. V ),Nagarajan Krishnan(Nagarajan Krishnan ) 대한해부학회 2023 Anatomy & Cell Biology Vol.56 No.1

The Galenic venous system plays a vital role in the drainage of blood from deeper parts of the brain. This venous system is contributed by many major veins. These veins are located closer to the pineal gland making the surgical approach in this region difficult. Any accidental injury or occlusion of the vein of Galen could lead to devasting results. Thus, studying the dimensions of the vein of Galen is more important. Hence, we aimed to evaluate the morphometry and trajectory to the vein of Galen. About 100 computed tomographic venography records were evaluated and the length, diameter of vein of Galen, angle between straight sinus and vein of Galen and distance from internal occipital protuberance and roof of fourth ventricle to vein of Galen were studied. The mean length and diameter of vein of Galen were 9.8±2.7 and 4.08±1.04 respectively. The mean angle between straight sinus and vein of Galen was 64.2°. The mean distance between external occipital protuberance and roof of fourth ventricle to vein of Galen were 52±6.9 and 33.3±4.5 respectively. No significant morphometric differences were observed between the age groups as well as between the sexs. The results obtained from this study may be helpful for the neurosurgeons in better understanding of the anatomy of the Galenic venous system and to adopt a safe surgical approach to improve the efficacy of the surgeries of the pineal gland and also in the region of vein of Galen.

Film Diffusion Mechanism of Methyl Parathion in Biopolymers: Kinetics and Thermodynamic Equilibrium

Sadasivam, Senthilkumaar,Kandasamy, Krishna S.,Ponnusamy, Kalaamani,Subramaniam Nagarajan, Ganapathi,Kang, Tae Won American Chemical Society 2011 Journal of chemical and engineering data Vol.56 No.11

<P>Sulfuric acid treated biopolymers (STB) were prepared from a lignocellulosic-based agricultural byproduct. The STB has been used as an effective adsorbent in a batch experiment for the removal of methyl parathion (MP) from aqueous solution. The as-prepared STB has been characterized by using surface area analyzer, scanning electron microscope (SEM), elemental analyzer, and proximate analysis methods. A batch adsorption study was carried out to investigate the adsorption equilibrium, kinetics, and thermodynamics as a function of agitation time, initial concentration of MP, initial pH, temperature, and carbon dose. Adsorption data were used to perform the kinetic models. The adsorption data was found to obey the Langmuir adsorption isotherm. Thermodynamic parameters of the adsorption process Δ<I>G</I>, Δ<I>S</I>, and Δ<I>H</I> were calculated, and their negative values indicate the feasible exothermic and spontaneous nature of the process. The diffusion of the MP molecule onto the biopolymer was confirmed by using the Weber–Morris equation. Reichenberg's equation shows the film diffusion of MP.</P>

Modulation of 3D Bioprintability in Polysaccharide Bioink by Bioglass Nanoparticles and Multiple Metal Ions for Tissue Engineering

Bhattacharyya Amitava,Khatun Mst Rita,Narmatha S.,Nagarajan R.,Noh Insup 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.2

Background: Bioglasses are used in applications related to bone rehabilitation and repair. The mechanical and bioactive properties of polysaccharides like alginate and agarose can be modulated or improved using bioglass nanoparticles. Further essential metal ions used as crosslinker have the potential to supplement cultured cells for better growth and proliferation. Method: In this study, the alginate bioink is modulated for fabrication of tissue engineering scaffolds by extrusion-based 3D bioprinting using agarose, bioglass nanoparticles and combination of essential trace elements such as iron, zinc, and copper. Homogeneous bioink was obtained by in situ mixing and bioprinting of its components with twin screw extruder (TSE) based 3D bioprinting, and then distribution of metal ions was induced through post-printing diffusion of metal ions in the printed scaffolds. The mechanical and 3d bioprinting properties, microscopic structure, biocompatibility of the crosslinked alginate/agarose hydrogels were analyzed for different concentrations of bioglass. The adipose derived mesenchymal stem cells (ADMSC) and osteoblast cells (MC3T3) were used to evaluate this hydrogel’s biological performances. Results: The porosity of hydrogels significantly improves with the incorporation of the bioglass. More bioglass concentration results in improved mechanical (compressive, dynamic, and cyclic) and 3D bioprinting properties. Cell growth and extracellular matrix are also enhanced with bioglass concentration. Conclusion: For bioprinting of the bioinks, the advanced TSE head was attached to 3D bioprinter and in situ fabrication of cell encapsulated scaffold was obtained with optimized composition considering minimal effects on cell damage. Fabricated bioinks demonstrate a biocompatible and noncytotoxic scaffold for culturing MC3T3 and ADMSC, while bioglass controls the cellular behaviors such as cell growth and extracellular matrix formation. Background: Bioglasses are used in applications related to bone rehabilitation and repair. The mechanical and bioactive properties of polysaccharides like alginate and agarose can be modulated or improved using bioglass nanoparticles. Further essential metal ions used as crosslinker have the potential to supplement cultured cells for better growth and proliferation. Method: In this study, the alginate bioink is modulated for fabrication of tissue engineering scaffolds by extrusion-based 3D bioprinting using agarose, bioglass nanoparticles and combination of essential trace elements such as iron, zinc, and copper. Homogeneous bioink was obtained by in situ mixing and bioprinting of its components with twin screw extruder (TSE) based 3D bioprinting, and then distribution of metal ions was induced through post-printing diffusion of metal ions in the printed scaffolds. The mechanical and 3d bioprinting properties, microscopic structure, biocompatibility of the crosslinked alginate/agarose hydrogels were analyzed for different concentrations of bioglass. The adipose derived mesenchymal stem cells (ADMSC) and osteoblast cells (MC3T3) were used to evaluate this hydrogel’s biological performances. Results: The porosity of hydrogels significantly improves with the incorporation of the bioglass. More bioglass concentration results in improved mechanical (compressive, dynamic, and cyclic) and 3D bioprinting properties. Cell growth and extracellular matrix are also enhanced with bioglass concentration. Conclusion: For bioprinting of the bioinks, the advanced TSE head was attached to 3D bioprinter and in situ fabrication of cell encapsulated scaffold was obtained with optimized composition considering minimal effects on cell damage. Fabricated bioinks demonstrate a biocompatible and noncytotoxic scaffold for culturing MC3T3 and ADMSC, while bioglass controls the cellular behaviors such as cell growth and extracellular matrix formation.

Fusion of Visible and Infrared Image Via Compressive Sensing using Convolutional Sparse Representation

S. Nirmalraj,G. Nagarajan 한국통신학회 2021 ICT Express Vol.7 No.3

An effective visible light and infrared image fusion method using a deep learning framework is designed to obtain a fused image which contains all the features from infrared and visible images. First, the source images are decomposed into low frequency and high frequency sub bands using wavelet transform. Then the low frequency is fused by maximum fusion rule. For the high frequency sub bands a deep learning network is used to find activity level measurements and then fused using the maximum fusion rule. For reconstruction, the optimized orthogonal matching pursuit algorithm and inverse wavelet transform are used.

Geochemistry of Neoproterozoic limestones of the Shahabad Formation, Bhima Basin, Karnataka, southern India

Ramasamy Nagarajan,Jayagopal Madhavaraju,John S. Armstrong-Altrin,Raghavendra Nagendra 한국지질과학협의회 2011 Geosciences Journal Vol.15 No.1

Major, trace and rare earth element (REE) geochemistry of carbonate rocks of the Neoproterozoic Shahabad Formation, southern India were studied in order to investigate the depositional environment and source for the REEs. The PAAS (Post Archaean Australian Shale) normalized REE + Y pattern of Shahabad limestones have consistent seawater-like pattern i.e., i) LREE depletion (average (Nd/Yb)_(SN) = 0.64 ± 0.08), ii) negative Ce anomaly, iii) positive Gd anomaly (average Gd_(SN)/Gd^* = 1.05 ± 0.16), iv) superchondritic Y/Ho ratio (average Y/Ho = 38.13 ± 21.35). The depletion of LREE and enrichment of HREE are clearly indicated by the (La/Yb)_(SN), (Dy/Yb)_(SN) and (Nd/Yb)_(SN) ratios, which suggest the retention of seawater characteristics in these limestones. The negative Ce anomaly reflects the incorporation of REE directly from seawater or from the pore water under oxic condition, and also reveals the mixing of two-component systems with terrigenous clay (detrital) in the marine sediments. The terrigenous input in these limestones is confirmed by positive correlation of REE with Al_2O_3, negative correlation of REE with CaO and differences in Y/Ho ratios. V, Cr, and Sc, are positively correlated with Ti, and strong positive correlation of REE with Fe_2O_3, Ni, Cr, Sc, and Y also indicate the presence of terrigenous materials in the Shahabad limestones.

Synergistic Catalytic Effect of a Composite (CoS/PEDOT:PSS) Counter Electrode on Triiodide Reduction in Dye-Sensitized Solar Cells

Sudhagar, P.,Nagarajan, S.,Lee, Yong-Gun,Song, Donghoon,Son, Taewook,Cho, Woohyung,Heo, Miyoung,Lee, Kyoungjun,Won, Jongok,Kang, Yong Soo American Chemical Society 2011 ACS APPLIED MATERIALS & INTERFACES Vol.3 No.6

<P>Inorganic/organic nanocomposite counter electrodes comprised of sheetlike CoS nanoparticles dispersed in polystyrenesulfonate-doped poly(3,4-ethylenedioxythiophene (CoS/PEDOT:PSS) offer a synergistic effect on catalytic performance toward the reduction of triiodide for dye-sensitized solar cells (DSSCs), yielding 5.4% power conversion efficiency, which is comparable to that of the conventional platinum counter electrode (6.1%). The electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements revealed that the composite counter electrodes exhibited better catalytic activity, fostering rate of triiodide reduction, than that of pristine PEDOT: PSS electrode. The simple preparation of composite (CoS/PEDOT:PSS) electrode at low temperature with improved electrocatalytic properties are feasible to apply in flexible substrates, which is at most urgency for developing novel counter electrodes for lightweight flexible solar cells.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2011/aamick.2011.3.issue-6/am2003735/production/images/medium/am-2011-003735_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am2003735'>ACS Electronic Supporting Info</A></P>

Influence of SF<SUB>6</SUB> /N₂ Gas Mixture Ratios on the Lightning Streamer Propagation Characteristics of 22 kV MV Circuit Breaker

R. Gandhi,S. Chandrasekar,C. Nagarajan 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of SF6 gas, many research works are being carried out towards the mixture of SF6 gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of SF6/N₂ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with SF6/N₂ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI (1.2/50 μs) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the 25% SF6+75%N₂ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% SF₆ gas mixed with 90% N₂ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.