Application of time series based damage detection algorithms to the benchmark experiment at the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan

Noh, Hae Young,Nair, Krishnan K.,Kiremidjian, Anne S.,Loh, C.H. Techno-Press 2009 Smart Structures and Systems, An International Jou Vol.5 No.1

In this paper, the time series based damage detection algorithms developed by Nair, et al. (2006) and Nair and Kiremidjian (2007) are applied to the benchmark experimental data from the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan. Both acceleration and strain data are analyzed. The data are modeled as autoregressive (AR) processes, and damage sensitive features (DSF) and feature vectors are defined in terms of the first three AR coefficients. In the first algorithm developed by Nair, et al. (2006), hypothesis tests using the t-statistic are applied to evaluate the damaged state. A damage measure (DM) is defined to measure the damage extent. The results show that the DSF's from the acceleration data can detect damage while the DSF from the strain data can be used to localize the damage. The DM can be used for damage quantification. In the second algorithm developed by Nair and Kiremidjian (2007) a Gaussian Mixture Model (GMM) is used to model the feature vector, and the Mahalanobis distance is defined to measure damage extent. Additional distance measures are defined and applied in this paper to quantify damage. The results show that damage measures can be used to detect, quantify, and localize the damage for the high intensity and the bidirectional loading cases.

Application of time series based damage detection algorithms to the benchmark experiment at the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan

Hae Young Noh,Krishnan Nair,Anne S. Kiremidjian,C-H. Loh 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.1

In this paper, the time series based damage detection algorithms developed by Nair, et al. (2006) and Nair and Kiremidjian (2007) are applied to the benchmark experimental data from the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan. Both acceleration and strain data are analyzed. The data are modeled as autoregressive (AR) processes, and damage sensitive features (DSF) and feature vectors are defined in terms of the first three AR coefficients. In the first algorithm developed by Nair, et al. (2006), hypothesis tests using the t-statistic are applied to evaluate the damaged state. A damage measure (DM) is defined to measure the damage extent. The results show that the DSF’s from the acceleration data can detect damage while the DSF from the strain data can be used to localize the damage. The DM can be used for damage quantification. In the second algorithm developed by Nair and Kiremidjian (2007) a Gaussian Mixture Model (GMM) is used to model the feature vector, and the Mahalanobis distance is defined to measure damage extent. Additional distance measures are defined and applied in this paper to quantify damage. The results show that damage measures can be used to detect, quantify, and localize the damage for the high intensity and the bidirectional loading cases.

Improvement in the Commercial Traits of Silkworm, Bombyx mori L. by Administration of a Juvenoid, R394

Nair, K.Sashindran,Vijayan, V.A,,Trivedy, Kanika,Nair, Jula S. Korean Society of Sericultural Science 2001 International Journal of Industrial Entomology Vol.3 No.2

A synthetic juvenoid, R394 (Ethyl 9-cyclohexyl-3, 7-dimethyl-2, 4-nonadienoate) which is known to be a strong pest control agent was administered to silkworm, Bombyx mori L. in minute quantity for improving the silk yield. Based on the result of an earlier preliminary screening, three concentrations of the compound, viz., 0.1563, 0.3125, 31.25 nl/ml were prepared in the form of an emulsion and administered topically as a single dose, to separate batches of $5^{th}$ instar silkworm at 24, 48, 72 and 96 hrs to determine the required concentration and critical time of application for an economically favourable response. Two popular commercial silkworm hybrids, PM ${\times}$ NB4D2 (multivoltine${\times}$bivoltine) and KA${\times}$NB4D2 (bivoltine$\times$bivoltine) were subjected to the experiment. The medium and absolute control were maintained in parallel to compare the results. The results showed that 0.3125 nl/ml was the best concentration of the compound and 72 hrs of $5^{th}$instar was the most favourable age for its administration to get the maximum improvement in the commercial traits. The possible role of exogenous juvenoids in eliciting favourable response in silkworm which ultimately leads to improvement in the commercial traits is discussed.

THYROID ULTRASOUND : A REVIEW OF 405 CASES

Ramachandran Nair Parameswaran,Pradeep,Nair, Krishnan 대한핵의학회 1984 핵의학 분자영상 Vol.18 No.1

Improvement in the Commercial Traits of Silkworm, Bombyx mori L. by Administration of a Juvenoid, R394

( K. Sashindran Nair ),( V. A. Vijayan ),( Kanika Trivedy ),( Jula S. Nair ) 한국잠사학회 2001 International Journal of Industrial Entomology Vol.3 No.2

A synthetic juvenoid, R394 (Ethyl 9-cyclohexyl-3, 7-dimethyl-2, 4-nonadienoate) which is known to be a strong pest control agent was administered to silkworm, Bombyx mori L. in minute quantity for improving the silk yield. Based on the result of an earlier preliminary screening, three concentrations of the compound, viz., 0.1563, 0.3125, 31.25 nl/ml were prepared in the form of an emulsion and administered topically as a single dose, to separate batches of 5th instar silkworm at 24, 48, 72 and 96 hrs to determine the required concentration and critical time of application for an economically favourable response. Two popular commercial silkworm hybrids, PM×NB4D2 (multivoltine×bivoltine) and KA×NB4D2 (bivoltine×bivoltine) were subjected to the experiment. The medium and absolute control were maintained in parallel to compare the results. The results showed that 0.3125 nl/ml was the best concentration of the compound and 72 hrs of 5th instar was the most favourable age for its administration to get the maximum improvement in the commercial traits. The possible role of exogenous juvenoids in eliciting favourable response in silkworm which ultimately leads to improvement in the commercial traits is discussed.

ACUTE INTERMITTENT PORPHYRIA AND HYPER THYROIDISM : A CASE REPORT

Parameswaran, Ramachandran Nair,Pradeep,Nair, Krishnan 대한핵의학회 1984 핵의학 분자영상 Vol.18 No.1

1, 25-(OH)2D3 protects against ER stress and miRNA dysregulation in Mus musculus neurons

Jayachandran Parvathy,Koshy Linda,Sudhakaran Perumana R.,Nair Govindapillai Mohanadasan,Gangaprasad Appukuttan Nair,Nair Ananthakrishnan Jayakumaran 한국유전학회 2022 Genes & Genomics Vol.44 No.12

Background: The pathophysiology of neurodegenerative diseases (NDDs) is closely associated with cellular oxidative stress which can result in the accumulation of toxic proteins in the endoplasmic reticulum (ER) leading to ER stress and subsequent unfolded protein response (UPR) signaling, a mechanism that aggravate these disorders. Vitamin D has been suggested to have important neuroprotective role and its administration has been shown to reduce neuronal injury, neurotoxicity and oxidative stress in various animal systems. Objective: The current study was undertaken to examine the effect of vitamin D3 on UPR in ER stress induced Mus musculus neuronal cells. Methods: Mus musculus cortical and hippocampal primary neuronal cultures were pretreated with 1,25-dihydroxyvitamin D3 (1, 25-(OH)2D3), the active form of vitamin D, followed by ER stress induction with a chemical ER stress inducer thapsigargin and with an advanced glycated protein, AGE-BSA. The UPR genes and related microRNAs (miRNA) expressions were analyzed mainly using real-time PCR. Results: The experiment resulted in the suppression of ER stress marker BiP and UPR pathway genes such as Perk, Ire1α, Chop and Puma which mediate cellular apoptosis indicating the protective effect of 1, 25-(OH)2D3 against neuronal ER stress. Further studies into the molecular aspects showed that ER stress mediated down-regulated expression of microRNAs (miRNAs) such as mmu-miR-24, 27b, 124, 224, 290, 351 and 488 which are known to regulate the UPR pathway genes were also reduced with vitamin pretreatment, of which the miRNAs miR-24 and 27b which shares the same cluster are potentially involved in various human diseases. Conclusion: This study emphasizes the therapeutic role of vitamin D in reducing neuronal ER stress and the need for maintaining sufficient amount of this vitamin in our diet.

Assessment of silver nanoparticle-induced physiological and molecular changes in Arabidopsis thaliana.

Nair, Prakash M Gopalakrishnan,Chung, Ill Min Ecomed 2014 Environmental Science and Pollution Research Vol.21 No.14

<P>In this study, the effect of silver nanoparticles and silver ions on Arabidopsis thaliana was investigated at physiological and molecular levels. The seedlings were grown in sublethal concentrations of silver nanoparticles and silver ions (0.2, 0.5, and 1 mg/L) in 1/4 Hoagland's medium for 14 days under submerged hydroponic conditions. Significantly higher reduction in the total chlorophyll and increase in anthocyanin content were observed after exposure to 0.5 and 1 mg/L silver nanoparticles as compared to similar concentrations of silver ions. Lipid peroxidation increased significantly after exposure to 0.2, 0.5, and 1 mg/L of silver nanoparticles and 0.5 and 1 mg/L of silver ions. Qualitative analysis with dichloro-dihydro-fluorescein diacetate and rhodamine 123 fluorescence showed a dose-dependent increase in reactive oxygen species production and changes in mitochondrial membrane potential in the roots of seedlings exposed to different concentrations of silver nanoparticles. Real-time PCR analysis showed significant upregulation in the expression of sulfur assimilation, glutathione biosynthesis, glutathione S-transferase, and glutathione reductase genes upon exposure to silver nanoparticles as compared with silver ions. Overall, based on the physiological and molecular level responses, it was observed that exposure to silver nanoparticles exerted more toxic response than silver ions in A. thaliana.</P>

Global millimeter VLBI array survey of ultracompact extragalactic radio sources at 86 GHz

Nair, Dhanya G.,Lobanov, Andrei P.,Krichbaum, Thomas P.,Ros, Eduardo,Zensus, Johann Anton,Kovalev, Yuri Y.,Lee, Sang-Sung,Mertens, Florent,Hagiwara, Yoshiaki,Bremer, Michael,Lindqvist, Michael,de Vice Springer-Verlag 2019 Astronomy and astrophysics Vol.622 No.-

<P><I>Context</I>. Very long baseline interferometry (VLBI) observations at 86 GHz (wavelength, <I>λ</I> = 3 mm) reach a resolution of about 50 <I>μ</I>as, probing the collimation and acceleration regions of relativistic outflows in active galactic nuclei (AGN). The physical conditions in these regions can be studied by performing 86 GHz VLBI surveys of representative samples of compact extragalactic radio sources.</P><P><I>Aims</I>. To extend the statistical studies of compact extragalactic jets, a large global 86 GHz VLBI survey of 162 compact radio sources was conducted in 2010-2011 using the Global Millimeter VLBI Array (GMVA).</P><P><I>Methods</I>. The survey observations were made in a snapshot mode, with up to five scans per target spread over a range of hour angles in order to optimize the visibility coverage. The survey data attained a typical baseline sensitivity of 0.1 Jy and a typical image sensitivity of 5 mJy beam<SUP>−1</SUP>, providing successful detections and images for all of the survey targets. For 138 objects, the survey provides the first ever VLBI images made at 86 GHz. Gaussian model fitting of the visibility data was applied to represent the structure of the observed sources and to estimate the flux densities and sizes of distinct emitting regions (components) in their jets. These estimates were used for calculating the brightness temperature (<I>T</I>b) at the jet base (core) and in one or more moving regions (jet components) downstream from the core. These model-fit-based estimates of <I>T</I>b were compared to the estimates of brightness temperature limits made directly from the visibility data, demonstrating a good agreement between the two methods.</P><P><I>Results</I>. The apparent brightness temperature estimates for the jet cores in our sample range from 2.5 × 10<SUP>9</SUP> K to 1.3 × 10<SUP>12</SUP> K, with the mean value of 1.8 × 10<SUP>11</SUP> K. The apparent brightness temperature estimates for the inner jet components in our sample range from 7.0 × 10<SUP>7</SUP> K to 4.0 × 10<SUP>11</SUP> K. A simple population model with a single intrinsic value of brightness temperature, <I>T</I>0, is applied to reproduce the observed distribution. It yields <I>T</I>0 = (3.77−0.14<SUP>+0.10</SUP>) × 10<SUP>11</SUP> K for the jet cores, implying that the inverse Compton losses dominate the emission. In the nearest jet components, <I>T</I>0 = (1.42−0.19<SUP>+0.16</SUP>) × 10<SUP>11</SUP> K is found, which is slightly higher than the equipartition limit of ∼5 × 10<SUP>10</SUP> K expected for these jet regions. For objects with sufficient structural detail detected, the adiabatic energy losses are shown to dominate the observed changes of brightness temperature along the jet.</P>

An experimental case study on corrosion characterization of Cu₄₆Zr₄₀Ti_8.5Al_5.5 metallic glass

Nair, Adithya,Prabhu, Yogesh,Mendonca, Jasmitha,Ryu, W.H.,Park, E.S.,Bhatt, Jatin,Vincent, S. Elsevier 2019 Journal of non-crystalline solids Vol.524 No.-

<P><B>Abstract</B></P> <P>In the present work, a novel Cu<SUB>46</SUB>Zr<SUB>40</SUB>Ti<SUB>8.5</SUB>Al<SUB>5.5</SUB> metallic glass is synthesized by melt spun technique and investigated for corrosion behavior at various molar concentrations in acidic, neutral and alkaline solutions (at different pH levels), using potentiodynamic polarization experiment and electrochemical impedance spectroscopy (EIS). Surface morphology and composition analysis after corrosion test were carried out by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Results indicate that corrosion resistance decreases with increase in chloride ion concentration in case of acidic and neutral media. However, in case of alkaline solution, corrosion resistance is found to be similar for pH 8 and pH 10, but is observed to decrease at pH 12. Melt spun sample was highly susceptible to pitting corrosion at higher molarity in acidic and neutral solution as observed from SEM analysis. EDS results indicate depletion of galvanically active metals (Al > Ti > Zr) from pit interior. Furthermore, an attempt has been made to study the influence of Al in corrosion behavior of the sample.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Corrosion behavior of novel Cu<SUB>46</SUB>Zr<SUB>40</SUB>Ti<SUB>8.5</SUB>Al<SUB>5.5</SUB> is studied in neutral, acidic and alkaline media. </LI> <LI> Pitting corrosion at high molarity in acidic and neutral solution as observed from SEM analysis. </LI> <LI> EDS results indicate depletion of galvanically active metals (Al > Ti > Zr) from pit interior. </LI> </UL> </P>