arXiv subjects

Partha Pratim Nath

Publications and source records attributed to Partha Pratim Nath.

3 recordsLinked to original sources

arXiv2024

ADL4D: Towards A Contextually Rich Dataset for 4D Activities of Daily Living

Hand-Object Interactions (HOIs) are conditioned on spatial and temporal contexts like surrounding objects, previous actions, and future intents (for example, grasping and handover actions vary greatly based on objects proximity and trajectory obstruction). However, existing datasets for 4D HOI (3D HOI over time) are limited to one subject interacting with one object only. This restricts the generalization of learning-based HOI methods trained on those datasets. We introduce ADL4D, a dataset of up to two subjects interacting with different sets of objects performing Activities of Daily Living (ADL) like breakfast or lunch preparation activities. The transition between multiple objects to complete a certain task over time introduces a unique context lacking in existing datasets. Our dataset consists of 75 sequences with a total of 1.1M RGB-D frames, hand and object poses, and per-hand fine-grained action annotations. We develop an automatic system for multi-view multi-hand 3D pose annotation capable of tracking hand poses over time. We integrate and test it against publicly available datasets. Finally, we evaluate our dataset on the tasks of Hand Mesh Recovery (HMR) and Hand Action Segmentation (HAS).

cs.CV↗

arXiv2023

A new class of traversable exponential wormhole metrics

In this work we have formulated a new class of traversable exponential wormhole metrics. Here initially we have considered a exponential wormhole metric in which the temporal component is an exponential function of $r$ but the spatial components of the metrics are fixed as a particular function $e^{\frac{2m}{r}+2αr}$. Following that, we have constructed a generalised exponential wormhole metric in which the spatial component is an exponential function of $r$ but the temporal component is fixed as a particular function given by $e^{-\frac{2m}{r}-2αr}$. Finally we have considered exponential metric in which both the temporal and spatial components are generalised exponential function of $r$. We have also studied some of their properties including throat radius, stability, energy conditions, examined singularity, the metric in curvature coordinates, effective refractive index, innermost stable circular orbit(ISCO) and photon sphere, Regge-Wheeler potential and determined the curvature tensor. The radius of the throat is found to be consistent with the properties of wormholes and donot contain any types of singularities, which are given by $r=m$, $r = \frac{-1+\sqrt{1+4αm}}{2α}$, $r=\frac{-1+\sqrt{1+8αm}}{4α}$, $r=m+\frac{1}α$, $r=m+\frac{2}α$...etc. Most interestingly, we find that their throat radius is same for the same spatial component and the same range of values of $m$. In addition to these they also violate Null Energy Condition(NEC) near the throat. These newly constructed metrics form a new class of traversable wormhole.

gr-qc↗

arXiv2023

Study of exponential wormhole metric in $f(R)$ gravity

In this work, we have studied an "exponential form" of spacetime metric: \begin{equation*} ds^2 = -e^{-\frac{2m}{r}}dt^2 +e^{\frac{2m}{r}}dr^2 + e^{\frac{2m}{r}}[r^2 dθ^2 + r^2 \sin^2θdϕ^2] \end{equation*} in some of the viable $f(R)$ gravity models, viz. exponential gravity model, Starobinsky gravity model, Tsujikawa model and Gogoi-Goswami f(R) gravity model. Here we have calculated the parameters including energy density, tangential and radial pressure for these corresponding models of $f(R)$ gravity. Subsequently we have investigated the energy conditions viz. null energy condition(NEC), weak energy condition(WEC) and strong energy condition(SEC) for the considered models. We have also explained the suitable conditions of energy for these models by related plots.

gr-qc↗