Methodologies for numerical modelling of prestressed concrete box-girder for long term deflection

M.C. Lalanthi,P. Kamatchi,K. Balaji Rao,S. Saibabu 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.3

In this paper, two methods M1 and M2 to determine long-term deflection through finite element analyses including the effect of creep and relaxation are proposed and demonstrated for a PSC box-girder. In both the methods, the effect of creep is accounted by different models from international standards viz., ACI-209R-92, CEB MC 90-99, B3 and GL2000. In M1, prestress losses due to creep and relaxation and age adjusted effective modulus are estimated through different models and have been used in finite element (FE) analyses for individual time steps. In M2, effects of creep and relaxation are implemented through the features of FE program and the time dependent analyses are carried out in single step. Variations in time-dependent strains, prestress losses, stresses and deflections of the PSC box-girder bridge through M1 and M2 are studied. For the PSC girder camber obtained from both M1 and M2 are lesser than simple bending theory based calculations, this shows that the camber is overestimated by simple bending theory which may lead to non-conservative design. It is also observed that stresses obtained from FEM for bottom fibre are lesser than the stresses obtained from bending theory at transfer for the PSC girder which may lead to non-conservative estimates.

SITUATIONAL, INDIVIDUAL, AND SOCIAL NETWORK DETERMINANTS OF NEGATIVE ONLINE WORD-OF-MOUTH

M S Balaji,Khong Kok Wei 글로벌지식마케팅경영학회 2014 Global Marketing Conference Vol.2014 No.5

This paper examines the situational, individual and social network determinants of negative online word-of-mouth on social network sites. The findings of the empirical study indicate that feeling of injustice, firm attribution, perceived service image, face concern, emotion regulation, SNS use intensity and tie strength significantly affects negative word-of-mouth.

SITUATIONAL, INDIVIDUAL, AND SOCIAL NETWORK DETERMINANTS OF NEGATIVE ONLINE WORD-OF-MOUTH

M S Balaji,Khong Kok Wei 글로벌지식마케팅경영학회 2014 Global Marketing Conference Vol.2014 No.7

This paper examines the situational, individual and social network determinants of negative online word-of-mouth on social network sites. The findings of the empirical study indicate that feeling of injustice, firm attribution, perceived service image, face concern, emotion regulation, SNS use intensity and tie strength significantly affects negative word-of-mouth.

Sensitivity Analysis of Geometrical Parameters of a Switched Reluctance Motor with Modified Pole Shapes

Balaji, M.,Ramkumar, S.,Kamaraj, V. The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

A major problem in Switched Reluctance Motor (SRM) is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in SRM by modifying stator and rotor geometry. This paper presents a comparative study on torque ripple minimization in SRM with modified pole shapes such as stator pole taper, stator pole face with non-uniform air gap and pole shoe attached to rotor pole. Further this paper presents a detailed sensitivity analysis of the effect of different geometrical parameters that alter the pole face shapes on the performance of SRM. The analysis is performed using finite-element method considering average torque and torque ripple as performance parameters. Based on the analysis, a design combining stator pole taper with non-uniform air gap is proposed to improve the torque characteristics of SRM. The dynamic characteristics of the proposed design are simulated and the results show satisfactory reduction in torque ripple.

GCD Matrix based PAPR Reduction Technique for OFDM System

Balaji Naik.M,SD Mohiddin Mehata,Bojja Durga Bhavani 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

Orthogonal Frequency Division Multiplexing (OFDM) is an efficient method of data transmission for high speed communication systems. One of the challenging issues for OFDM system is its high Peak-to-Average Power Ratio (PAPR) which causes inefficient use of the High Power Amplifier (HPA) and could limit transmission efficiency. In this paper we analyze the effects of PAPR on HPA and its reduction technique based on GCD matrix In Selected Mapping (SLM) method. Simulation results shows that the new phase sequence based SLM method has good performance in PAPR reduction.

Sensitivity Analysis of Geometrical Parameters of a Switched Reluctance Motor with Modified Pole Shapes

M. Balaji,S. Ramkumar,V. Kamaraj 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

A major problem in Switched Reluctance Motor (SRM) is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in SRM by modifying stator and rotor geometry. This paper presents a comparative study on torque ripple minimization in SRM with modified pole shapes such as stator pole taper, stator pole face with non-uniform air gap and pole shoe attached to rotor pole. Further this paper presents a detailed sensitivity analysis of the effect of different geometrical parameters that alter the pole face shapes on the performance of SRM. The analysis is performed using finite-element method considering average torque and torque ripple as performance parameters. Based on the analysis, a design combining stator pole taper with non-uniform air gap is proposed to improve the torque characteristics of SRM. The dynamic characteristics of the proposed design are simulated and the results show satisfactory reduction in torque ripple.

Reliability studies on RC beams exposed to fire based on IS456:2000 design methods

Aneesha Balaji,M.S. Aathira,T.M. Madhavan Pillai,Praveen Nagarajan 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.5

This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named 500oC isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS(R) Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.

High sheet resistance emitter c-Si solar cells with low SRV by local line contact with transparent conducting oxides

Kim, M.,Kim, J.,Lee, Y.J.,Ju, M.,Park, C.,Balaji, N.,Lee, S.,Kim, J.,Yi, J. North-Holland 2014 Materials letters Vol.116 No.-

The high sheet resistance (R<SUB>s</SUB>) solar cells with ITO full contact suffer from low open circuit voltage (V<SUB>oc</SUB>) with a negligible/no passivation effect. To overcome this, we approached ITO local line contact with SiO<SUB>2</SUB> passivation to reduce the recombination loss. Passivation area increases to 91.29%. The improvement in carrier lifetime, V<SUB>oc,</SUB> reveals the melioration in passivation. With high R<SUB>s</SUB> emitter, the ITO full contact solar cell results in efficiency of 16.26% whereas the ITO local line contact solar cell results in 17.15%.

Trace element dynamics of biosolids-derived microbeads

Wijesekara, Hasintha,Bolan, Nanthi S.,Bradney, Lauren,Obadamudalige, Nadeeka,Seshadri, Balaji,Kunhikrishnan, Anitha,Dharmarajan, Rajarathnam,Ok, Yong Sik,Rinklebe, Jö,rg,Kirkham, M.B.,Vithanage, M Elsevier 2018 CHEMOSPHERE - Vol.199 No.-

<P><B>Abstract</B></P> <P>This study focused on quantifying and characterising microbeads in biosolids (i.e., treated sewage sludge), and in examining interactions of microbeads with trace elements when biosolids are added to soil. Under laboratory conditions, batch experiments were conducted to investigate the adsorption of Cu onto pure and surface modified microbeads suspended in soil. The ecotoxicity of microbead-metal complexes to soil microbial activities was also investigated by monitoring basal respiration and dehydrogenase activity. Concentrations of the microbeads were 352, 146, 324, and 174 particles kg<SUP>−1</SUP> biosolids for ≤50, 50–100, 100–250, 250–1000 μm size fractions, respectively. The Scanning Electron Microscope (SEM) images illustrated wrinkled and fractured surfaces due to degradation. The adsorption of dissolved organic matter onto microbeads was confirmed through FT-IR microscopy, while using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) the presence of trace metals including Cd (2.34 ng g<SUP>−1</SUP>), Cu (180.64 ng g<SUP>−1</SUP>), Ni (12.69 ng g<SUP>−1</SUP>), Pb (1.17 ng g<SUP>−1</SUP>), Sb (14.43 ng g<SUP>−1</SUP>), and Zn (178.03 ng g<SUP>−1</SUP>) was revealed. Surface modified microbeads were capable of adsorbing Cu compared to the pure microbeads, which may be attributed to the complexation of Cu with dissolved organic matter associated with the microbeads in the matrix. It was further revealed that the biosolids derived microbead-metal complexes decreased soil respiration (up to ∼ 26%) and dehydrogenase activity (up to ∼ 39%). Hence, microbeads reaching biosolids during wastewater treatment are likely to serve as a vector for trace element contamination, transportation, and toxicity when biosolids are applied to soil.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biosolids are a major source for microbeads in soil. </LI> <LI> A first-time study on microbial toxicity of biosolids-derived microbeads. </LI> <LI> Microbeads serve as a vector for transportation of trace elements in soil. </LI> <LI> Dissolved organic matter enhanced the adsorption of trace elements by microbeads. </LI> <LI> Microbeads decreased microbial respiration and dehydrogenase activity in soil. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Performance-based remaining life assessment of reinforced concrete bridge girders

M. B. Anoop,K. Balaji Rao,B. K. Raghuprasad 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.1

Performance-based remaining life assessment of reinforced concrete bridge girders subject to chloride-induced corrosion of reinforcement, is addressed in this paper. Towards this, a methodology that takes into consideration the human judgmental aspects in expert decision making regarding condition state assessment is proposed. The condition of the bridge girder is specified by the assignment of a condition state from a set of predefined condition states, considering both serviceability- and ultimate- limit states, and, the performance of the bridge girder is described using performability measure. A non-homogeneous Markov chain is used for modelling the stochastic evolution of condition state of the bridge girder with time. The thinking process of the expert in condition state assessment is modelled within a probabilistic framework using Brunswikian theory and probabilistic mental models. The remaining life is determined as the time over which the performance of the girder is above the required performance level. The usefulness of the methodology is illustrated through the remaining life assessment of a reinforced concrete T-beam bridge girder.