Experimental Investigations on Laminated Rubber Bearings

Increasing application of base isolation as a seismic protection method has subsequently increased its analytical and experimental studies. Being the most critical part of the base isolated buildings, accurate evaluation of structural properties and precise modeling of isolation devices is of utmost importance in predicting the response of the buildings during the earthquakes. This technical note is concerned with experimental study on laminated rubber bearings. Free vibration and harmonic base excitation tests are performed on a three-storey building model to evaluate the properties of the structure, efficiency of the system, and effect of base excitations. It is found that these experimental methods can effectively be used for this purpose.     

A locally-constrained YOLO framework for detecting small and densely-distributed building footprints

ABSTRACT

Building footprints are among the most predominant features in urban areas, and provide valuable information for urban planning, solar energy suitability analysis, etc. We aim to automatically and rapidly identify building footprints by leveraging deep learning techniques and the increased availability of remote sensing datasets at high spatial resolution. The task is computationally challenging due to the use of large training datasets and large number of parameters. In related work, You-Only-Look-Once (YOLO) is a state-of-the-art deep learning framework for object detection. However, YOLO is limited in its capacity to identify small objects that appear in groups, which is the case for building footprints. We propose a LOcally-COnstrained (LOCO) You-Only-Look-Once framework to detect small and densely-distributed building footprints. LOCO is a variant of YOLO. Its layer architecture is determined by the spatial characteristics of building footprints and it uses a constrained regression modeling to improve the robustness of building size predictions. We also present an invariant augmentation based voting scheme to further improve the precision in the prediction phase. Experiments show that LOCO can greatly improve the solution quality of building detection compared to related work.     

Period-luminosity relations for Cepheid variables: from mid-infrared to multi-phase

This paper discusses two aspects of current research on the Cepheid period-luminosity (P-L) relation: the derivation of mid-infrared (MIR) P-L relations and the investigation of multi-phase P-L relations.     

Geophysical surveys for identifying source and pathways of subsurface water inflow at the Bangur chromite mine,Odisha, India

Geophysical survey was carried out in an effort to solve an underground flooding problem at the Bangur chromite mine of Odisha Mining Corporation Limited, Odisha, India. To identify sources and pathways of the influx, very low-frequency electromagnetic, self-potential and resistivity surveys were performed. Geophysical studies clearly depict a major fracture zone passing through the mine and its connection to a water storage pond. The fracture zone extends further west from the pond to the Salandi River and the Salandi Reservoir. The dip of the delineated fracture zone is around 45° to the N, and it matches with the fault plane exposed in the mine. Since water enters into the mine from the west, the delineated fracture zone is thought to be the main pathway for the inflow. Geophysical studies conclude that the IMFA pond, Salandi River and Salandi Reservoir could be possible sources of water in the mine. To ascertain the source and pathway, tracer testing was conducted at two locations, based on the geophysical survey by the hydrogeological team, but tracer test results were inconclusive. However, the fact remains that the water enters to the mine through the delineated fracture and poses threat in mine operation. Dumping water in nearby pond will again enter in mine with interconnected fractures. Therefore, for safe mining operation, it is proposed to drill a slanted tube well at the delineated fracture and pump out maximum water and discharge the pumped water at canal situated about 2.5 km from the mine.     

Intensity variation of atomic oxygen red line in the day airglow with solar activity

Rates of production of O(¹ D) atoms in the upper atmosphere by photodissociation of O₂, dissociative recombination of O₂ ⁺, NO⁺ and electron impact excitation of O(³ P) have been calculated for low, medium and high levels of solar activity. Variations with solar activity, of neutral and ionic composition, electron and neutral temperatures of the upper atmosphere and solar extreme ultraviolet fluxes incident on it have been taken into consideration.Emission rates ofOi red line (6300Å) have been computed taking into account the deactivation both by molecular oxygen and nitrogen. It has been shown that the integrated intensity from low to high activity period varies by approximately an order of magnitude in agreement with the results of experimental observations.     

Surface exchange of water vapour between an open sphagnum fen and the atmosphere

Water loss by evapotranspiration (ET) is a principal component of the hydrologic cycle in wetlands. Using micrometeorological techniques, we measured ET from a Sphagnum-dominated open fen in northcentral Minnesota (U.S.A.) from May to October in 1991 and 1992. The daily ET rate ranged from 0.2–4.8 mm d^-1 with a growing season average of 3.0 mm d^-1. The evapotranspiration rate of the fen was near the potential rate of open water evaporation when the vascular plants were actively growing and the water table level was within or above the rooting zone. Using a dual-source modification of the Penman-Monteith equation (Massman, 1992), we partitioned the measured ET into evaporation from the non-vascular Sphagnum surfaces and transpiration from vascular plants. The analysis indicated that about two thirds of the water vapour flux to the atmosphere was from evaporation when the Sphagnum surface was wet. Such an evaporative flux was expected because of vertical distribution of vascular plant leaves which had a small leaf area index (0.4–0.7) and intercepted only about 30% of net radiation (R _n ) during the day. The remainder of R _n was thus available for evaporation from Sphagnum. Evaporation significantly decreased as the Sphagnum surface dried out. When the water table was within the rooting zone (0–0.4 m), the vascular plants absorbed Sphagnum-generated sensible heat, which amounted up to one third of their transpiration energy flux. Under these conditions, the total water vapour flux remained near its potential rate owing to the enhanced transpiration from vascular plants. A drop in water table of 0.15–0.2 m below the hollow bottom during vascular plant senescence resulted in ET rates lower than the potential rates by 5–65%.     

Eddy fluxes of CO2, water vapor,and sensible heat over a deciduous forest

Fluxes of CO₂, latent heat and sensible heat were measured above a fully-leafed deciduous forest in eastern Tennessee with the eddy correlation technique. These are among the first reported observations over such a surface. The influences of solar radiation, vapor pressure deficit and the aerodynamic and canopy resistances on these mass and energy exchanges are examined. Following a concept introduced by McNaughton and Jarvis (1983), examination of our data suggest that the water vapor exchange of a deciduous forest is not as strongly coupled with net radiation as is that of agricultural crops. The degree of decoupling is smaller than in the case of a coniferous forest. This difference may be attributable in part to the greater aerodynamic resistance to water vapor transfer in a deciduous forest. It appears that the concept of decoupling may be extended to the CO₂ exchange of a deciduous forest as well.Published as Paper No. 7832, Journal Series, Nebraska Agricultural Research Division. ATDD Contribution No. 85-17.     

Ecological variables influencing the diversity and distribution of macrolichens colonizing <Emphasis Type="Italic">Quercus leucotrichophora</Emphasis> in Uttarakhand forest

Ecological variables play a significant role in determining the diversity and distribution of any living organism on earth. Lichens are not exceptional and are quite sensitive in comparison to other organisms; hence the present study focuses on the impact of ecological variables on the diversity and distribution of epiphytic macrolichens colonizing Quercus leucotrichophora across eight different sites (50 m × 50 m) in Thal Ke Dhar forest, Kumaun Himalaya, Uttarakhand, India. For sampling of macrolichens, 200 trees (25 trees from each site) of Q. leucotrichophora were selected from each site and five quadrats of 5 cm × 10 cm (1000 quadrats in totality) were drawn at the tree trunk. From all the sampled trees, a total of 54 species of epiphytic macrolichens belonging to 18 genera and five families were recorded. Various ecological variables, namely altitude, aspect, slope, diameter at breast height (DBH), and lopping percent (partial cutting of the twigs as disturbance), were also analyzed to investigate their influence on macrolichen species composition and distribution pattern in the study area. For the determination of relationships between these variables, statistical analysis, namely Pearson’s Correlation Coefficient, Polynomial regression analysis and Principal Component Analysis (PCA) were performed. Out of all variables, lopping was significantly correlated to species richness of epiphytic macrolichens (0.712*, p<0.05) and it was confirmed by Pearson’s Correlation Coefficient. Despite of having high anthropogenic pressure or impact through lopping, the maximum number of macrolichen species was recorded at elevation 2267 meter above sea level (m asl). The present study revealed that besides other ecological variables, lopping practices can act as a key parameter in controlling the diversity and distribution not only of epiphytic macrolichens but also of other life forms such as bryophytes, pteridophytes, insects, birds etc. and can be either negatively or positively correlated.