Free vibrations of open-section shear walls

The coupled torsional-flexural vibration of open-section shear walls, braced by connecting beams at each floor level, is analysed on the basis of Vlasov's theory of thin-walled beams. The basic dynamic equations and boundary conditions are derived from Hamilton's principle, and a numerical solution obtained by the Ritz-Galerkin method. In addition to the primary torsional and flexural inertias, secondary effects due to rotatory and warping inertia forces have also been taken into account. The method is suitable for both rigid and flexible base conditions. A series of numerical examples is presented in which analytical results are compared with available experimental data, and the effects of secondary inertia forces, base flexibility and connecting beams upon the vibration characteristics of such shear walls are examined for two different structural forms.     

Bringing communities at the Centre of Impact Assessment of Road Projects: integrating AHP with qualitative research

GeoJournal - This paper proposes a framework for measuring impacts associated with road projects on rural communities situated on either side of the road alignment. The extant approaches for...     

Charged Particle Monitor on the Astrosat Mission

Charged Particle Monitor (CPM) on-board the Astrosat satellite is an instrument designed to detect the flux of charged particles at the satellite location. A Cesium Iodide Thallium (CsI(Tl)) crystal is used with a Kapton window to detect protons with energies greater than 1 MeV. The ground calibration of CPM was done using gamma-rays from radioactive sources and protons from particle accelerators. Based on the ground calibration results, energy deposition above 1 MeV are accepted and particle counts are recorded. It is found that CPM counts are steady and the signal for the onset and exit of South Atlantic Anomaly (SAA) region are generated in a very reliable and stable manner.     

Variability of rainfall and effective onset and length of the monsoon season over a sub-humid climatic environment

The study has analyzed the variability and trends in monthly, seasonal and annual rainfall and rainy days of four locations over different agro-ecological zones of Bihar, namely Samastipur (zone-I), Madhepura (zone-II), Sabour (zone-IIIA) and Patna (zone-IIIB). The Mann–Kendall nonparametric test was employed for detection of statistical significance and slopes of the trend lines were determined using the method of least square linear fitting. The variability and trends of onset of effective monsoon and length of monsoon period were also analyzed using the same method. The mean annual rainfall varies from 1137 mm at Patna to 1219 mm at Sabour. July is the rainiest month in all the zones followed by August. Maximum increase in annual rainfall was found at Sabour (40.1% of mean/30 years at 95% confidence level) and minimum for Patna (10.1% of mean/30 years). Significant increasing trend of rainfall during July, August and September at rates of 41.9, 83.2, and 112.7% of the mean/30 years, respectively has been noticed at Madhepura. Analysis of rainy days indicates that rainy days increased during winter and annually for all the sites. The mean effective onset of monsoon varies from 18th June at Sabour to 28th June at Patna. The trends in the date of effective onset of monsoon indicate that the date tends to be early in all the sites except Madhepura. But a significant delayed trend in the onset at a rate of 2.8% of the mean/30 years has been observed for Madhepura. The early trend of the effective onset of monsoon and increasing trends of length of monsoon season have been observed for Samastipur, Sabour and Patna.     

An assessment of the potential impact of climate change on flood risk in Mumbai

Managing risks from extreme events will be a crucial component of climate change adaptation. In this study, we demonstrate an approach to assess future risks and quantify the benefits of adaptation options at a city-scale, with application to flood risk in Mumbai. In 2005, Mumbai experienced unprecedented flooding, causing direct economic damages estimated at almost two billion USD and 500 fatalities. Our findings suggest that by the 2080s, in a SRES A2 scenario, an ??upper bound?? climate scenario could see the likelihood of a 2005-like event more than double. We estimate that total losses (direct plus indirect) associated with a 1-in-100 year event could triple compared with current situation (to $690?C$1,890 million USD), due to climate change alone. Continued rapid urbanisation could further increase the risk level. The analysis also demonstrates that adaptation could significantly reduce future losses; for example, estimates suggest that by improving the drainage system in Mumbai, losses associated with a 1-in-100 year flood event today could be reduced by as much as 70%.,We show that assessing the indirect costs of extreme events is an important component of an adaptation assessment, both in ensuring the analysis captures the full economic benefits of adaptation and also identifying options that can help to manage indirect risks of disasters. For example, we show that by extending insurance to 100% penetration, the indirect effects of flooding could be almost halved. We conclude that, while this study explores only the upper-bound climate scenario, the risk-assessment core demonstrated in this study could form an important quantitative tool in developing city-scale adaptation strategies. We provide a discussion of sources of uncertainty and risk-based tools could be linked with decision-making approaches to inform adaptation plans that are robust to climate change.     

Photometric study of an eclipsing binary in the field of M37

CCD photometric observations with B and V passbands were performed on the contact binary V3 in the field of open cluster M37. The solutions were obtained for data from both B and V passbands along with R passband given by Hartman et al.using the Wilson-Devinney code. The positive O'Connell effect was observed in all the three passbands and its associated cool spot parameters were derived. The results indicate that the spot parameters have not shown any significant variability during the last four years. The spot radius was found to be 40and located close to the equator of the secondary component. The absolute parameters of the system were derived using the empirical relations given by Gazeas et al.     

Long Term Variations in Chromospheric Features from Ca-K Images at Kodaikanal

There is a collection of about 100 years of Ca-K line spectroheliograms at the Kodaikanal Observatory (KKL) obtained on daily basis with a single instrument that can be used to study long term variations of various chromospheric features. All the Ca-K images have been digitized using specially developed digitizers with uniform and highly stable light source, high quality lens and 4k×4k format CCD camera. The digitization has been carried out in a room with controlled temperature and humidity. The digitized data are in 16-bit format with pixel resolution of 0.86 arcsec. The digitized images have been calibrated by a process that includes flat-fielding, density to intensity conversion, centering the image, and rotation of the image to make the solar north pole in the fixed direction. Then we applied correction for the limb darkening effect and also made the background in the image uniform. The image background was normalized to unity that enabled us to use the intensity contrast to identify different features, such as plages, enhanced (EN), active (AN), and quite network on images and classified them by using different image contrast and area threshold values. After several experiments with different threshold values for different features and careful analysis of a large number of images, we could fix the threshold values of intensity contrast larger than 1.35 and area larger than 1 arcmin² for plages, larger than 1.35 but area less than 1 arcmin² for EN, and between 1.25?–?1.35 for AN. We compared the quarterly averaged and half yearly averaged plage areas obtained from KKL with the Mount Wilson (MWO) data and sunspot number. We find that the plage area extracted from the KKL is highly correlated with the MWO plage area, though there is a slight difference between the two data set in cycle 19. The plage area of KKL is also highly correlated with the sunspot number. The areas of EN and AN are also found to have smaller quasi-periodic variations apart from the solar cycle variations.