Luleå University of Technology Publications
Not a member yet
39356 research outputs found
Sort by
Weighing geophysical data with trans-dimensional algorithms: An earthquake location case study
No full textIn geophysical inverse problems, the distribution of physical properties in an Earth model is inferred from a set of measured data. A necessary step is to select data that are best suited to the problem at hand. This step is performed ahead of solving the inverse problem, generally on the basis of expert knowledge. However, expert-opinion can introduce bias based on pre-conceptions. Here we apply a trans-dimensional algorithm to automatically weigh data on the basis of how consistent they are with the fundamental assumptions made to solve the inverse problem. We demonstrate this approach by inverting arrival times for the location of a seismic source in an elastic half space, under the assumptions of a point source and constant velocities. The key advantage is that the data do no longer need to be selected by an expert, but they are assigned varying weights during the inversion procedure.Funder: Ministero dell’Istruzione e del Merito;Full text license: CC BY, "Authors retain copyright to all content posted on ESS Open Archive. The submitting author must be the copyright holder or have the appropriate permission from the copyright holder to submit all content. ESS Open Archive offers five separate licenses to authors."</p
Nonlinear Effects of Gravity in Cosmology
No full textWe investigate some nonlinear effects of gravity in cosmology. Possible physically interesting consequences include: non-requirement ofdark matter and dark energy, asymmetric gravitational matter-creation,emergent homogeneity/isotropy & asymptotic flatness, resolution of“cosmic coincidence” Ωm∼Ω, effective cutoff of gravitational inter-action at the scale of cosmic voids
Deep Ontology Alignment with BERT_INT: Improvements and Industrial Internet of Things (IIoT) Case Study
No full text“He who knows no foreign languages knows nothing of his own.” Johann Wolfgang emphasized the worth of languages for expanding ones learning horizons. This work instills the same notion into the industrial internet of things (IIoT) sensory devices paradigm. We study the interoperability problem setting with a new perspective of envisioning knowledge graphs (KGs) modeling for the device to device ontology alignment. Ontology alignment is structured as entity alignment in which similar entities are linked from two heterogeneous knowledge graphs. The novelty is conceiving the IIoT ontology graph as a language of the sensory device and then addressing it through the natural language processing (NLP) language translation approach. The IIoT ontology graph nodes have unique URIs so they act as words (sentences) for the NLP model and the schema of the graph is depicted as the language structure. Existing methods give less attention to the importance of structural information which ignores the fact of even when a node pair has similar entity labels it may not refer to a similar context and vice versa. To deal with these issues, we propose a novel solution using a modified BERT_INT model on graph Triplets for ontology alignment among heterogeneous IIoT devices. Moreover, an iterative framework is designed to leverage the alignments within nodes as well as among relations. As the first attempt at this problem, the proposed model is tested on a contemporary language dataset of DBP15K and compared with the best state-of-the-art results. The proposed model outperforms the target baseline BERT_INT model by 2.1% in terms of HR@1, HR@10, and MRR. Next, a dataset on ontology instances is constructed on smart building sensors using two W3C standardized IIoT ontologies i.e. SSN and SOSA. Comprehensive experiments and analysis with ablation study on language and structural encoders demonstrate the effectiveness of our model
Towards a Reduced Dependency Framework for Autonomous Unified Inspect-Explore Missions
No full textThe task of establishing and maintaining situational awareness in an unknown environment is a critical step to fulfil in a mission related to the field of rescue robotics. Predominantly, the problem of visual inspection of urban structures is dealt with view-planning being addressed by map-based approaches. In this article, we propose a novel approach towards effective use of Micro Aerial Vehicles (MAVs) for obtaining a 3-D shape of an unknown structure of objects utilizing a map-independent planning framework. The problem is undertaken via a bifurcated approach to address the task of executing a closer inspection of detected structures with a wider exploration strategy to identify and locate nearby structures, while being equipped with limited sensing capability. The proposed framework is evaluated experimentally in a controlled indoor environment in presence of a mock-up environment validating the efficacy of the proposed inspect-explore policy
A mineral systems-scale investigation into the Kiruna mining district and implications for the timing of ore forming processes within a regional tectonic framework
No full textThe formation of iron oxide apatite (IOA) and iron oxide-copper-gold (IOCG) deposits and their relation to each other is currently strongly debated. Recent characterization of the polyphase Svecokarelian orogeny in the northern Norrbotten ore province provides a tectonic framework that can be used to assess the timing of IOA and IOCG genetic processes from a broader mineral systems perspective. This study combined whole rock lithogeochemistry, whole rock Sr and Nd isotopes, U-Pb zircon geochronology, and structural data to gain insight into the Kiruna mining district mineral system. Results show that the igneous intrusions range from mafic to felsic in composition and developed in an active continental margin with both volcanic arc and within-plate affinities. The intrusions have ages ranging from 1891 ± 6 Ma to 1876 ± 11 Ma. One magnetite-ilmenite gabbro gives a concordia age of 1881 ± 8 Ma. These ages indicate a thermal drive for the mineral system can be recognized occurring during an early-orogenic deformation phase (D0-D1) but remains enigmatic for a late-orogenic phase (D2). 87Sr/86Sri and εNdi data from ore-related alteration (Na-alteration and late K-Fe overprint) at Pahtohavare Cu ± Au and Rakkurijärvi IOCG deposits as well as district igneous, greenstone, and Archean rocks indicate that the deposits have distinct Sr-mixing trends and that both sourced Sr and Nd from a wide variety of protoliths. Alteration results show a prominent Na-metasomatism with certain areas showing a K-overprint. New structural analysis of the Pahtohavare area indicates the main ore-related generation of quartz-carbonate-sulfide veins cross cut foliation and were introduced during F2 folding in the late Svecokarelian (D2), suggesting that a late Cu-Au mineralization/remobilization occurred in the Kiruna mining district ca. 80 m.y. after the emplacement of the Kiirunavaara IOA deposit. In brief, our data show that IOA and IOCG systems can be of different ages and sources within the same district