Abstract

Measurement of the electric field radiations by ultra-wideband antenna is a challenging task. In general, all the antennas are measured for the radiation pattern and return loss to estimate their overall performance. However, when it comes to the antennas that are fed by very high voltages (HV), in the order of few hundreds of kilo volts and the input is not continuous, the measurements become complex. There arises an ambiguity in deciding about the peak value of the high electric fields generated, especially when the HV electric discharge mechanism is involved in the radiation of the antenna. The electric discharges are, in general, not repetitive. This paper proposes a measurement technique that is well suited for measuring the high electric fields, especially in the order of hundreds of kV/m. The proposed measurement procedure is verified and validated by experiments. The repeatability and reliability of the proposed measurement procedure are checked and presented here.

Abstract

We introduce PeeledHuman - a novel shape representation of the human body that is robust to self-occlusions. PeeledHuman encodes the human body as a set of Peeled Depth and RGB maps in 2D, obtained by performing raytracing on the 3D body model and extending each ray beyond its first intersection. This formulation allows us to handle self-occlusions efficiently compared to other representations. Given a monocular RGB image, we learn these Peeled maps in an end-to-end generative adversarial fashion using our novel framework - PeelGAN. We train PeelGAN using a 3D Chamfer loss and other 2D losses to generate multiple depth values per-pixel and a corresponding RGB field per-vertex in a dual-branch setup. In our simple non-parametric solution, the generated Peeled Depth maps are back-projected to 3D space to obtain a complete textured 3D shape. The corresponding RGB maps provide vertex-level texture details. We compare our method with current parametric and non-parametric methods in 3D reconstruction and find that we achieve state-of-the-art-results. We demonstrate the effectiveness of our representation on publicly available BUFF and MonoPerfCap datasets as well as loose clothing data collected by our calibrated multi-Kinect setup.

Abstract

Shayari is a form of poetry mainly popular in the Indian subcontinent, in which the poet expresses his emotions and feelings in a very poetic manner. It is one of the best ways to express our thoughts and opinions. Therefore, it is of prime importance to have an annotated corpus of Hindi shayaris for the task of sentiment analysis. In this paper, we introduce SUKHAN, a dataset consisting of Hindi shayaris along with sentiment polarity labels. To the best of our knowledge, this is the first corpus of Hindi shayaris annotated with sentiment polarity information. This corpus contains a total of 733 Hindi shayaris of various genres. Also, this dataset is of utmost value as all the annotation is done manually by five annotators and this makes it a very rich dataset for training purposes. This annotated corpus is also used to build baseline sentiment classification models using machine learning techniques.

Abstract

Development of Force-based seismic design is historical, and every earthquake has thrown new challenges for already existing assumptions and principles, which helped in the evolution of force-based design. Although many of the assumptions were answered but some remained unaltered and unanswered. Hence, this paved way for developing new theories and philosophies and one such theory is Direct Displacement-Based seismic Design (DDBD). Indian Standard codes, IS 1893 and IS 13920, underwent a major revision in the year 2016, considering the latest developments in Force based design principles. Current work is an attempt to understand the performance comparison between latest IS 1893 & IS 13920 with DDBD method. Initially, three buildings i.e., 3, 6 and 9 storey buildings were designed using DDBD at inter-storey drift of 4% with a performance objective to achieve “No collapse”. The spectrum developed using IS code equations does not represent ideal displacement spectrum shape and hence PGA, T and CA dependent equations are used for DDBD methodology of design. PGA of 0.36g is used in the current study which represents the highest seismic zone in India. Later these buildings were subjected to lateral displacement using displacement-based pushover analysis method. The inelastic strength along with drifts achieved by DDBD are compared with the IS code compliant buildings. From the comparison, it was observed that inelastic strength achieved by 6,9 storey buildings designed according to FBD are greater than the buildings designed according to DDBD at “No Collapse”. For 3 storey structure, the strength achieved by FBD is less than DDBD. If zone is reduced from Zone V to IV or PGA is increased from 0.36g, then inelastic strength achieved by DDBD with performance objective “No Collapse” would be more than FBD requiring revision of response reduction values for different categories of buildings or PGA values in respective seismic zones. The inelastic drifts achieved by both the methods are comparable only for 3 storey structure.

Abstract

An earthquake Mw7.8 occurred on 25 April 2015 in a seismically dominant area of Nepal. No major earthquakes (>Mw7.0) were recorded in the past two decades, though Nepal is one of the active seismic regions in the world. The combined effect of the main event and the aftershocks, which are temporally distributed over 40 days, has led to a huge devastation, killing thousands of people in the epi-central area. A complete seismic catalog and influencing parameters such as type of fault, epi-central/hypo-central distance, type of soil are required for a region to assess seismic hazard scenario. The seismic hazard can be represented in terms of Peak Ground Acceleration (PGA), which is the most widely used parameter in strong motion studies. The main objective of this paper is to understand the characteristics of ground motion of the 2015 Nepal earthquake. Since the available ground motion records are limited, an attempt has been made to generate ground motion records using a modified semi-empirical approach. Contour maps of PGA and intensity have also been generated. It is observed that around 22% of buildings experienced an intensity of VI on MMI scale at Bageswari mandal. A few buildings have experienced an intensity of VII in Thankot, Seuchatar, Satikhel, Mahadevathan, Indrayani, Chhaimale, and Balambu.

Abstract

In last two decades, operational modal analysis is widely used for modal identification of structures which uses ambient responses of structure for determining the modal parameters and Frequency Domain Decomposition is one of the most popular method, but seismic excitations and high damping values of structures do not satisfy the assumptions of this classical method. The dynamic modal parameters derived from earthquake responses are more reliable than those from small amplitude responses since dynamic properties of civil structures are dependent on amplitude. In recent years, a new algorithm known as refined Frequency Domain Decomposition (rFDD) is developed which uses structural response to strong ground motions that can be short in duration and is applicable for structures with light to heavy damping. The refined Frequency Domain Decomposition (rFDD) algorithm was initially developed using synthetic seismic response signals as input and later real strong motion response records were used to demonstrate the effectiveness of this algorithm for modal dynamic identification of structures under real earthquake excitations. This method is well developed to counter the problems that normally arise in modal identification and in cases of heavy damping and non-stationarity of the signal, making it lengthy and tedious to process. In this paper the main feature of this method which is Integrated Power Spectral Density matrix computation is taken and applied on mild earthquakes responses of structure. The modal parameters identified are then compared with target values obtained from classical FDD method using ambient responses and interpreted, presenting a case for usage of rFDD in simplified manner in modal dynamic identification of structures. Keywords: Operational Modal analysis, mild earthquake response, refined Frequency Domain Decomposition

Abstract

Damage index models are used for quantification of damage in any numerical model of a building. While using any particular damage model there is high possibility that it might give similar result for two identical structures, each having different attributes. So, though currently available damage index models precisely quantify damage in the structure but fails to identify the reason or attributes/irregularities present in it. Therefore, for quantitative assessment, a unique aspect should be used which will depend on structural as well as architectural features. This paper presents new method for quantification of damage for reinforced concrete (RC) moment resisting framed (MRF) structures using the pattern of hinge formation in structure when it is subjected to a monotonic loading. A two-dimensional RC MRF structures with different building irregularities were modeled. As a primary step to estimate the damage from the pattern of hinge formation, it is necessary to understand and study the relation between damage and hinge pattern. For this purpose, energy-based damage index model is used. The relation between damage index and pattern of hinge formation is studied with the help of regression analysis. A multiple regression analysis is performed taking damage index as dependent variable and the number of hinges formed in each damage state as independent variables. The paper also discusses two different approaches for regression analysis determining the corresponding coefficients. The regression analysis resulted in an equation which can approximately quantify the damage in the structure using total number of hinges formed in each structural member.

Abstract

Radiating boundary conditions are essential in the numerical analysis of infinite domains such as dynamic SoilStructure-Interaction analysis. Local absorbing boundary conditions proposed by Lysmer and Kuhlemeyer (1969) are widely used in SSI analysis. These boundary conditions are developed based on the wave propagation in elastic materials. However, almost all soil materials exhibit viscoelastic properties. Badry and Ramancharla (2018) proposed the Absorbing Boundary Conditions for wave propagation in viscoelastic materials (VABC). The VABC conditions were developed from the original Absorbing Boundary Conditions (ABC) by including a spring in addition to the dashpot. In fact, these boundary conditions are inefficient when the waves impinge other than normal direction. In this paper, the radiating boundary conditions are modelled using VABC and ALID (Absorbing Layers by Increase in Damping) together to include the advantages of both the boundary conditions and to overcome the drawback of ABC on angle incidence. A detailed numerical analysis is carried out to verify the boundary conditions. The efficiency of the proposed method has been verified for both 1D and 2D wave propagation problems. The efficiency on angle incidence is verified using 2D plane strain model response through spatial Fourier Transformation. The study concludes that the proposed method is simple and reliable method for modelling radiating boundary conditions. Keywords: Local Absorbing Boundaries, Viscoelastic wave propagation, Rayleigh damping, Soil-Structure interaction, Absorbing Layers by Increase in Damping (ALID)

Abstract

UN World Conference on Disaster Risk Reduction held in 2015 at Sendai, Japan, reiterated the need for substantial reduction in loss of life and property. Thus, assessing disaster risk and identifying key items for risk mitigation are in focus. Assessment of disaster risk is a multidisciplinary effort, which includes expected tangible physical loss, such as collapse and damage to built environment. In countries with limited resources, prioritizing risk reduction effort across the different parts of the country needs a quantitative (yet simple) approach to bring objectivity into the decision-making process. This paper presents a simple method, called Earthquake Disaster Risk Index (EDRI), for estimating relative earthquake risk across the different regions in a country; it uses three major constituents of risk, namely Hazard, Exposure and Vulnerability. Hazard is taken as the acceleration hazard specified in the national earthquake design standard, Exposure as per the permitted occupancy in the Local Municipal Byelaws, and Vulnerability through a Level 2 Detailed Qualitative Assessment of buildings built in the Town or City (with penalty points for missing features of earthquake resistance compared to an Ideal Building). First, the EDRI of a Town or City is estimated for each typology of building in the Town or City, and then the net EDRI of the Town or City is obtained as a weighted average of the EDRI of each typology of buildings using the number of buildings of each typology present in the city. The EDRI of a city so estimated can be compared with that of another city. Also, disaggregation of risk through its three major constituents of EDRI will increase awareness of the factors which contribute to risk – from expected intensity of earthquake ground shaking, to exposure of people in each building type, to vulnerability of each building typology. The exercise can be undertaken at a large scale across the country. Policy Makers of a prefecture or a state in a nation will find the results of EDRI to be a useful tool for prioritising allocation of earthquake risk mitigation resources and effort across Towns and Cities.

Abstract

Structural engineering involves clear understanding of characteristics of ground motion used in the design of structures to identify the critical aspects of their behavior. Peak amplitude of response (a, v, or d), predominant frequency and duration of strong ground motion are the most important parameters of ground motion that are required for this purpose. These parameters are influenced by the source, path and site conditions. However, it is also found that for the same distance these characteristics are highly sensitive to the fault direction and the side on which the site lies i.e., hanging wall or foot wall. In this paper, a case study is performed to understand the influence of fault direction and location of site on the characteristics of the ground motion. For this purpose, 371 ground motions recorded during 1999 Chi-Chi, Taiwan earthquake are selected. Initially, these ground motions were arranged in terms of fault parallel and fault normal direction and also according to distance from the fault. Later, ground motion characteristics were obtained using standard procedures. From the above, it was found that, in the near-fault region, PGA and PGV on the hanging wall are higher by at-least 20% than that on the footwall. From this observation, the near-fault region can be defined not by using the distance from the fault, but by observing the ratio of PGA values in fault normal and parallel directions. This method of estimating the near-fault region is reliable because the hanging wall effect is caused only due to the inclined dip-angle of the fault which is inevitable in most of the thrust and normal faults. Keywords: Hanging wall effect; PGA; Thrust faults; Fault Normal; Fault Parallel