Damping Ratios of Pristine Composite Beam and Constrained Layer Damped Composite Beam of Equal Stiffness

Ramadas Chennamsetti,Avinash Hood,Siddlingappa Guruprasad,Sajal Roy,Makarand Joshi 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

Constrained layer damping is one of the passive techniques to control amplitude of vibration of structural components. In the present work an attempt has been made to quantify and compare damping ratios of composite-rubber-composite sandwich beam with that of pristine composite beam having nearly the same flexural stiffness and range of frequency of vibration from 20 Hz to 100 Hz. Length and thickness of sandwich and pristine beams in order to have the same flexural stiffness and desired frequency range of vibration were specifically designed. The damping ratio of each sandwich and pristine composite beams were measured experimentally using logarithmic decay and half-power bandwidth techniques.

Analysis of genetic diversity in CYTB and control region sequences of Melanochelys trijuga (Schweigger, 1812) from Karnataka

Ramadas Lalitha,Vidya Ramakrishna Chandavar 국립중앙과학관 2018 Journal of Asia-Pacific Biodiversity Vol.11 No.3

Melanochelys trijuga indigenously called Indian black turtle is an endemic freshwater turtle species of Asia. Current study is the first report on mitochondrial marker of M. trijuga from this region. The study highlights intraspecies nucleotide diversity in CYTB and control region (CR) sequences. The CYTB gene analyzed revealed 4.47% variability with no indels and CR region consist 13.5% variability with 22 indels. In CYTB pyrimidine transitions (Ts) (T↔C) exceeded purine Ts (A↔G). This resulted in synonymous substitutions of amino acids in the protein without altering its structure and function. The partial fragment of CR contained CSB 1, 2, 3 that are required for its regulatory function and consist more of Ts than transversions. The nucleotide diversity (π) for CR was greater than that of CYTB which indicates CR is highly susceptible for mutation. The number of haplotypes and haplotype diversity were poorly resolved and probable reasons have been discussed.

Socio-Demography and Medical History as Predictors of Health-Related Quality of Life of Breast Cancer Survivors

Ramadas, Amutha,Qureshi, Ahmad Munir,Dominic, Nisha Angela,Botross, Nevein Philip,Riad, Amgad,Arasoo, Valliammai Jayanthi Thirunavuk,Elangovan, Soman Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.4

Background: Even after completion of conventional treatment, breast cancer survivors continue to exhibit a variety of psychological and physical symptoms, affecting their quality of life. The study aimed to investigate the relationship between socio-demography, medical characteristics and health-related quality of life (HR-QOL) of a sample of breast cancer survivors in Malaysia. Materials and Methods: This pilot cross-sectional survey was conducted among breast cancer survivors (n=40) who were members of Breast Cancer Support Group Centre Johor Bahru. A validated self-administered questionnaire was used to identify the relationships between socio-demography, medical characteristics and HR-QOL of the participants. Results: Living with family and completion of treatment were significant predictive factors of self-rated QOL, while living with family and ever giving birth significantly predicted satisfaction with health and physical health. Psychological health had moderate correlations with number of children and early cancer stage. Survivors' higher personal income (>MYR4,500) was the only significant predictor of social relationship, while age, income more than MYR4,500 and giving birth significantly predicted environment domain score. Conclusions: The findings suggested the survivors coped better in all four HR-QOL domains if they were married, lived with family, had children and were employed.

Changes Observed in Ao Mode Due to Rotational Misalignment of Air-Coupled Transducers in Isotropic Plates

Ramadas Chennamsetti,Irfan Khan,Avinash Hood,Makarand Joshi 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

Misalignments are a major concern, when air-coupled ultrasonic probes are deployed for transmission and reception of Lamb waves. Misalignments between the air-coupled probes result in reduction in amplitude and change in arrival time of the Lamb waves. This reduction in amplitude can give a false alarm in Non-destructive Testing (NDT) applications, if amplitude is the criterion for flaw or damage detection. In the present work, one of the probe’s (transmitter or receiver) position was kept fixed, and the other probe was rotated to introduce a misalignment termed ‘rotational misalignment’. This rotation had violated the co-planarity condition,resulting in reduction in amplitude of the received fundamental anti-symmetric mode (Ao) in an isotropic material plate. Interestingly,variation in amplitude of the Ao mode with the rotational misalignment angle revealed that, at certain angular locations, there exists a local maximum and local minimum resembling sync function. Subsequently, the angular location of occurrence of these is attributed to dispersion characteristics of the Ao mode.

AO Lamb Mode Radiation Characteristics of Air-Coupled Transducers in Isotropic Plates

Ramadas Chennamsetti,Irfan Khan 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The fundamental anti-symmetric Lamb mode (Ao) radiation characteristics of air-coupled transducers in isotropic (aluminium) plateswere measured experimentally for the first time. To evaluate the radiation characteristics, experiments were performed by fixing theposition of one of the transducers (either transmitter or receiver) and then moving other one (either receiver or transmitter) alongthe circumference of a circle, whose radius was equal to that of the distance of separation between the transducers. Experiments wereconducted to evaluate the radiation pattern of 100 kHz, 200 kHz and 500 kHz air-coupled transducers in one mm and three mm thickaluminium plates. It is interesting to note that, Ao Lamb mode radiation pattern emitted by air-coupled transducers in isotropic platesis characterised by Gaussian curve.

Attenuation modelling of bulk waves generated by a point source in an isotropic medium

C. Ramadas 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10

Attenuation of a bulk wave, generated by a point source, propagating in an isotropic medium, is due to the geometry and nature of the material involved. In numerical simulations, if the complete domain of propagation is modeled, then it captures the attenuation of a wave caused due to its geometry. To model the attenuation of the wave caused due to the nature of the material, it is required to know the material’s attenuation coefficient. Since experimental measurement on attenuation of a wave involves both the effects of geometry and material, a method based on curve fitting to estimate the material’s attenuation coefficient from effective attenuation coefficient, is proposed. Using the material’s attenuation coefficient in the framework of Rayleigh damping model, numerical modeling on attenuation of both the bulk waves - longitudinal and shear excited by a point source was carried out. It was shown that the proposed method captures the attenuation of bulk waves caused on account of geometry as well as nature of the material.

Determinants of Participation in a Breast Cancer Screening Trial in Trivandrum District, India

Frie, Kirstin Grosse,Ramadas, Kunnambath,Anju, Gopan,Mathew, Beela Sara,Muwonge, Richard,Sauvaget, Catherine,Thara, Somanathan,Sankaranarayanan, Rengaswamy Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Background: Conspicuous differences in participation rates for breast self-examination (BSE), clinical breast examination (CBE), and referral for further investigations have been observed indicating involvement of a number of different factors. This study analysed determinants for participation in different levels of the breast cancer screening process in Indian females. Materials and Methods: An intervention group of 52,011 women was interviewed in a breast cancer screening trial in Trivandrum district, India. In order to assess demographic, socio-economic, reproductive, and cancer-related determinants of participation in BSE, CBE, and referral, uni- and multi-variate logistic regression was employed. Results: Of the interviewed women, 23.2% reported practicing BSE, 96.8% had attended CBE, and 49.1% of 2,880 screen-positives attended referral. Results showed an influence of various determinants on participation; women who were currently not married or who had no family history of cancer were significantly less likely to attend the screening process at any level. Conclusions: Increasing awareness about breast cancer, early detection methods, and the advantages of early diagnoses among women, and their families, as well as health care workers offering social support, could help to increase participation over the entire screening process in India.

PSO Based Fuzzy Logic Controller for Load Frequency Control in EV Charging Station

Vinitha J. C.,Ramadas Geetha,Rani P. Usha 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Electric vehicles are highly preferred in today's scenario to provide an environmentally friendly nature and preserve natural resources such as petroleum and diesel. Many studies on the technical and economic feasibility of electric vehicle charging stations have been conducted. The majority of the research does not focus on power fuctuations in the charging station caused by load variations. Only a few studies have looked into this issue and proposed a static frequency control method for power fuctuation control. However, they used a predefned solver feasp to fnd the best value for controlling the primary and secondary frequency controls in this method. Within its local optimal region, this technique fnds its solution. As a result, an optimization-based feasp for controlling power fuctuations in charging stations is proposed. The Enhanced Particle Swarm Optimization based Fuzzy Logic Controller (FLC) is suggested here for fnding the best solution to reduce power fuctuations using feasp. This optimized approach efectively reduces power fuctuations by determining the best value for controlling the primary and secondary charging frequency in electric vehicles. The system becomes stable in the shortest time with PSO-based FLC, according to simulation results. Furthermore, the magnitude of frequency oscillations, peak overshoot, and settling time are reduced. A comparison of the PSO-FLC method with the conventional method and the Linear–Quadratic Regulator method are compared to justify controller tuning.

Propagation of Ao Mode through the Front Edge of a Delamination: Numerical and Experimental Studies

Rakesh Kumar Singh,Ramadas Chennamsetti 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Numerical and experimental studies carried out on the propagation of ultrasonic Lamb wave and its interaction with the front edgeof a delamination in a cross-ply and unidirectional composite laminates are presented in this paper. When the fundamental antisymmetricLamb mode (Ao) is incident at the leading (front) edge of a delamination, it undergoes reflection and transmission into thesub-laminates. Numerical simulations carried out on the interaction of the Ao mode with the edge of a semi-infinite delaminationrevealed that during this interaction, So mode is generated and propagate as AoSo (propagation of the So mode due to the incidentAo mode) mode in the top and bottom sub-laminates along with the incident Ao mode, which propagates as AoAo (propagation of theAo mode due to the incident Ao mode) mode. Transmission factors and power transmission coefficients of AoAo and AoSo modes onan assortment of excitation frequencies – 150 kHz, 175 kHz, 200 kHz and 225 kHz, and thickness ratios were computed. Experimentalvalidation of results arrived through numerical simulations, was also carried out employing air-coupled ultrasonic transducers.

Association of Serum and Salivary Tumor Necrosis Factor-α with Histological Grading in Oral Cancer and its Role in Differentiating Premalignant and Malignant Oral Disease

Krishnan, Rajkumar,Thayalan, Dinesh Kumar,Padmanaban, Rajashree,Ramadas, Ramya,Annasamy, Ramesh Kumar,Anandan, Nirmala Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Background: Oral squamous cell carcinoma (OSCC) is an important malignancy throughout the world; early detection is an important criterion for achieving high cure rate. Out of the many reported markers for OSCC, this study validated the efficacy of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) in differentially diagnosing premalignant oral lesions and OSCC. Also, the study aimed to correlate the levels of salivary and serum TNF-${\alpha}$ with clinicopathologic factors. Materials and Methods: A prospective experimental laboratory study was designed. Serum and salivary samples from 100 subjects in each group of healthy control, premalignant disease (PMD) and OSCC were collected for the study following appropriate exclusion and inclusion criteria. Serum and salivary level of TNF-${\alpha}$ was analysed by enzyme linked immunosorbent assay. The data obtained were subjected to appropriate statistical analysis. Results: Increased level of both serum and salivary TNF-${\alpha}$ was observed in OSCC subjects compared to healthy control and PMD group. Receiver operator characteristic curve analysis and area under curve values showed high specificity and sensitivity for salivary TNF-${\alpha}$ in differentiating OSCC from PMD and healthy controls. There was significant increase in TNF-${\alpha}$ level in moderately and poorly differentiated lesion compared to well differentiated lesion and in stage IV of clinical stage. A positive correlation was observed only with histological grading of OSCC and TNF-${\alpha}$. Conclusions: Salivary TNF-${\alpha}$ is proved to be superior for detecting OSCC. Increase in TNF-${\alpha}$ with histological grading and clinical staging suggests a role in prognosis.