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.

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.

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

ACUTE INTERMITTENT PORPHYRIA AND HYPER THYROIDISM : A CASE REPORT

Parameswaran, Ramachandran Nair,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.

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.

Torque Estimation using Kalman Filter and Extended Kalman Filter Algorithms for a sensorless Direct Torque Controlled BLDC Motor drive: A Comparative Study

Nair Deepthi S,Jagadanand G.,George Saly 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

Torque estimation for Direct Torque Controlled BLDC motor drive using Kalman Filter and Extended Kalman Filter are described in this paper. In conventional direct torque control method, the torque estimation is done based on the position information, which in turn requires position sensors for accurate estimation. In this paper, torque is directly estimated using Kalman fi lter and Extended Kalman Filter algorithms without the aid of any feedback information, and a comparison is made between the two. Both the algorithms are perceptive to follow the actual torque; the error between the actual and reference is used for the selection of appropriate voltage vector for inverter switching. The refl ection of load changes in the control algorithm is also a part of the interest in this work. The potential of Extended Kalman Filter to follow exactly the changes in the load torque is utilized here and Extended Kalman Filter based sensorless drive is proposed for the torque estimation in Direct Torque Controlled BLDC motor. The performance parameters, viz. computational eff ort, torque ripple reduction are found to be superior with the Extended Kalman Filter algorithm, which is validated.

Water impact of three dimensional wedges using CFD

Nair, Vinod V.,Bhattacharyya, S.K. Techno-Press 2018 Ocean systems engineering Vol.8 No.2

In this paper the results of CFD simulations, that were carried out to study the impact pressures acting on a symmetric wedge during water entry under the influence of gravity, are presented. The simulations were done using a solver implementing finite volume discretization and using the VOF scheme to keep track of the free surface during water entry. The parameters such as pressure on impact, displacement, velocity, acceleration and net hydrodynamic forces, etc., which govern the water entry process are monitored during the initial stage of water entry. In addition, the results of the complete water entry process of wedges covering the initial stage where the impact pressure reaches its maximum as well as the late stage that covers the rebound process of the buoyant wedge are presented. The study was conducted for a few touchdown velocities to understand its influence on the water entry phenomenon. The simulation results are compared with the experimental measurements available in the literature with good accuracy. The various computational parameters (e.g., mesh size, time step, solver, etc.) that are necessary for accurate prediction of impact pressures, as well as the entry-exit trajectory, are discussed.

Performance Evaluation of Various Bus Clamped Space Vector Pulse Width Modulation Techniques

Nair, Meenu D.,Biswas, Jayanta,Vivek, G.,Barai, Mukti The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5

The space vector pulse width modulation (SVPWM) technique is a popular PWM method for medium voltage drive applications. Conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are the most common SVPWM techniques. This paper evaluates the performance of various advanced BCSVPWM strategies in terms of their harmonic distortion and switching loss based on a uniform frame work. A uniform frame work, pulse number captures the performance parameter variations of different SVPWM strategies for various number of samples with heterogeneous pulse numbers. This work compares different advanced BCSVPWM techniques based on the modulation index and location of the clamping position (zero vector changing angle ) of a phase in a line cycle. The frame work provides a fixed fundamental frequency of 50Hz. The different BCSVPWM switching strategies are implemented and compared experimentally on a 415V, 2.2kW, 50Hz, 3-phase induction motor drive which is fed from an IGBT based 2 KVA voltage source inverter (VSI) with a DC bus voltage of 400 V. A low cost PIC microcontroller (PIC18F452) is used as the controller platform.