Abstract

Abstract: Pipeline generally extends over long distances traversing through wide variety of different soils, geological conditions and regions with different seismicity. Most analytical models developed in the past for pipeline fault crossing are of limited usage as models developed were useful only for strike slip fault. Incorporating the large geometric changes in analytical study is a tricky task; however pipeline subjected to the fault motion itself is a phenomenon of large geometric changes, especially when pipeline subjected to compression in addition to material deformation, it also undergoes local buckling with bending. With computational advancement in numerical modelling, pipes under compression can also be studied. In this paper, a 3D FE-based numerical model is suggested to carry out pipeline performance of buried pipeline subjected to fault motion including material non-linearity and large geometric deformations. A 3D FE programme is developed using MATLAB. Displacement controlled arc-length technique is implemented to solve the non-linear behaviour.

Abstract

The Indian Seismic Code IS: 1893-2007 indicates that approximately 60% of India’s land area is under the threat of moderate to severe earthquake shaking. According to census 2011, number of houses exposed such high hazard is almost 80%. This is due to uneven population distribution. In order to find out the potential risk to housing in a city, it is necessary to evaluate Hazard (H), Exposure (E) and Vulnerability (V). Since, vulnerability of a building is a combination of many factors like, planning, design, execution and maintenance; it is very difficult to assess the same for entire city. As a case study, a 3-storey RC framed building, which lies in a highly seismic area, has been selected in the Union Territory of Chandigarh and its vulnerability to nearby earthquakes is studied. Building vibration sensors (accelerometers) have been installed at appropriate locations on the building and data acquisition has been done. In this paper, we present a comparison of Fourier amplitude spectrums generated from the data acquired using a micro-tremor observation system and permanent sensors. The companion paper presents a study of the response of the building to the acceleration data, recorded at ground, normalized to the earthquakes in zone IV. We then propose a potential risk model to the scenario earthquake by analyzing the fragility curve developed for the building area.

Abstract

The Indian Seismic Code IS: 1893-2007 indicates that about 60% of India’s land area is under threat of moderate to severe earthquake shaking. Also according to census 2011, number of houses exposed such high hazard is almost 80%. This is due to uneven population distribution. In order to find out the potential risk to housing for a city, it is necessary to evaluate Hazard (H), Exposure (E) and Vulnerability (V). Since, vulnerability of a building is combination of many factors like, planning, design, execution and maintenance; it is very difficult to assess the same for entire city. As a case study, a 3-storey RC framed building has been selected in the Union Territory of Chandigarh, which lies in high seismic area; and vulnerability of the same to nearby earthquakes is studied. Building vibration sensors (accelerometers) have been installed at appropriate locations on the building and data acquisition is done. In companion paper, data is acquired first by using micro-tremor observation system and later by using permanent sensors. In this paper, event accelerations recorded at the ground were normalized to earthquakes in zone IV and zone-V areas and response of the building is studied. Fragility curve has been developed for the building area.

Abstract

For the assessment of risk of any area three components are necessary viz., Hazard, Exposure and Vulnerability. While most of the times Exposure and Vulnerability are easy to obtain compared to Hazard. For Hazard estimation, real ground motions are required. However, in highly seismic areas with less number of recorded ground motions, artificial ground motions are quite helpful. The estimation of strong ground motion parameters for a particular region can be done either by analytical methods or by numerical methods. Present work illustrates a comparative study of real and artificial ground motion generated for Uttarkashi earthquake. Midorikawa technique is used for generating strong ground motions at different locations. Ground motions records are considered at 13 stations during Uttarkashi earthquake. The synthetic ground motions are compared with recorded accelerograms at stations. The results of the analyses with both artificial and real accelerograms were compared in terms of site-transfer function, acceleration response spectrum and several strong motion parameters.

Abstract

Analysis and design of high-rise buildings for lateral load such as wind load and earthquake are the major issues which are playing significant role in recent decades. This paper describes a recent application of the computational fluid dynamics technique for wind analysis. Conventional wind analysis suggests wind tunnel experiment for arriving at the wind forces for a given structural form. As a case study a regular 38-story high-rise building (Jamieson place, Calgary Canada1) made of concrete with shear wall, built in downtown Calgary 2010 is selected. It is assumed that the building is located in highly seismic area. The design objective was to develop most cost-effective structural system while meeting building functionality goals and adhering to code requirement. The main structural design issues considered in this building are reviewed: Static analysis, Dynamic Analysis, Wind Analysis and Stability Analysis. Initial static and dynamic analysis is conducted in SAP and later wind analysis is conducted in Ansys as opposed to wind tunnel experiments. The building model is modeled in Ansys workbench and then the mesh file is imported to Ansys CFX for CFD simulation and analysis. After CFD analysis the wind forces on the building model are extracted in Ansys CFX-Post and imported to the structural model in SAP 2000 for the structural analysis.

Abstract

Visual localization in crowded dynamic environments requires information about static and dynamic objects. This paper presents a robust method that learns the useful features from multiple runs in highly crowded urban environments. Useful features are identified as distinctive ones that are also reliable to extract in diverse imaging conditions. Relative importance of features is used to derive the weight for each feature. The popular Bag-of-words model is used for image retrieval and localization, where query image is the current view of the environment and database contains the visual experience from previous runs. Based on the reliability, features are augmented and eliminated over runs. This reduces the size of representation, and makes it more reliable in crowded scenes. We tested the proposed method on data sets collected from highly crowded Indian urban outdoor settings. Experiments have shown that with the help of a small subset (10%) of the detected features, we can reliably localize the camera. We achieve superior results in terms of localization accuracy even when more than 90% of the pixels are occluded or dynamic.

Abstract

Depth information has been shown to affect identification of visually salient regions in images. In this paper, we investigate the role of depth in saliency detection in the presence of (i) competing saliencies due to appearance,(ii) depth-induced blur and (iii) centre-bias. Having established through experiments that depth continues to be a significant contributor to saliency in the presence of these cues, we propose a 3D-saliency formulation that takes into account structural features of objects in an indoor setting to identify regions at salient depth levels. Computed 3D saliency is used in conjunction with 2D saliency models through non-linear regression using SVM to improve saliency maps. Experiments on benchmark datasets containing depth information show that the proposed fusion of 3D saliency with 2D saliency models results in an average improvement in ROC scores of about 9% over state-of-the-art 2D saliency models.

Abstract

Modern research in India on dams has entered a distinct phase subsequent to the damage to Koyna dam, located in hitherto considered stable continental part, due to an earthquake on 11th December, 1967 in Koyna district, India. Out of about 5,100 large dams in India, a significant number are in moderately high and high seismic zones. As such they may be prone to probable instability to the dam’s structure due to earthquake resultant impacts. Even though none of the dams other than Koyna got damaged in India due to high magnitude earthquake activity, since 1967, it is felt necessary to understand the behaviour of dams due to water load coupled with dynamics of faults that are present in the vicinity of the dam, as dam failures due to earthquake activity are reported from different parts of the world. In this paper, damage to Koyna dam due to a fault motion caused nearby has been studied. A concrete gravity dam is selected from the National Importance Dams of India. Structure-1(S1) as a concrete gravity dam with foundation and structure-2 (S2) as a concrete gravity dam with foundation and soil strata are numerically modeled using Applied Element Method (AEM). Displacement at the base of soil strata is given to generate reverse fault effect on the dam. Behavior of dam is studied by direct and sub-structure methods. In the direct method, the effect of fault motion on dam is studied in S2, by modeling dam at different locations on foot wall and hanging wall. In sub-structure method, free-field accelerations are recorded at different locations on foot wall and hanging wall while only the sub-structure is subjected to fault motion. The recorded accelerations on the surface are used as input to analyze super structure S1. Comparison on behavior of dam in models S1 and S2 is later drawn.

Abstract

This paper presents a method to capture the orbiting objects using a robotic system mounted on a service satellite. The main objective is to manipulate the robot such that no reaction moment gets transferred to the base satellite. This will avoid use of any attitude controller resulting in fuel savings. Note that the constraints leading to zero reaction moment are nonholonomic, and this makes path planning a complex problem. In this work, first a method based on holonomic distribution of the nonholonomic constraints is discussed. As this method exploits constraints in terms of joint velocities, it does not always ensure successful capture. Next, a method based on task-level constraints, written in terms of end-effector's velocities, has been illustrated. It is shown that the path planned using this method has several singular points. In order to overcome disadvantages of the above two methods a novel approach is proposed which uses holonomic distribution to reach closer to the target and task-level constraints to finally capture the target. Efficacy of the method is shown using a 3-link robot mounted on a service satellite.

Abstract

A series of dihydrogen complexes trans-[Ru(η2-H2){SC(SR)H}(dppe)2][X][BF4] (R = CH3, X = OTf; R = C6H5CH2, X = BPh4; R = H2C=CHCH2, X = BPh4; dppe = Ph2PCH2CH2PPh2) bearing sulfur-donor ligands has been synthesized by protonation of the (alkyl dithioformate)hydrido complexes trans-[Ru(H){SC(SR)H}(dppe)2][X] by using HBF4•Et2O. Competitive substitution reactions between H2 and SC(SR)H in trans-[Ru(η2-H2){SC(SR)H}(dppe)2][X][BF4] have been studied by treatment with CH3CN, CO, and P(OCH3)3. These resulted in the expulsion of SC(SR)H from the metal center, thus indicating that the alkyl dithioformate ligand is more labile than H2. Bonding of alkyl dithioformate ligands (sulfur-donor ligands) trans to H2 have been studied by comparing the H–H distances and chemical-shift values (1H NMR spectroscopy) of the various dihydrogen complexes bearing different trans ligands. This study qualitatively suggests that the alkyl dithioformate ligands in these trans-dihydrogen complexes show a poor π effect, and it is further supported by density functional theory calculations. The first example of a dihydrogen complex bearing dithioformic acid, trans-[Ru(η2-H2){SC(SH)H}(dppe)2][BF4]2, was obtained by protonation of trans-[Ru(H){SC(S)H}(dppe)2] by using HBF4•Et2O.