arXiv subjects

Javier Martinez

Publications and source records attributed to Javier Martinez.

7 recordsLinked to original sources

arXiv2025

Blast Hole Seeking and Dipping -- The Navigation and Perception Framework in a Mine Site Inspection Robot

In open-pit mining, holes are drilled into the surface of the excavation site and detonated with explosives to facilitate digging. These blast holes need to be inspected internally to assess subsurface material types and drill quality, in order to significantly reduce downstream material handling costs. Manual hole inspection is slow and expensive, limited in its ability to capture the geometric and geological characteristics of holes. This has been the motivation for the development of our autonomous mine-site inspection robot - "DIPPeR". In this paper, the automation aspect of the project is explained. We present a robust perception and navigation framework that provides streamlined blasthole seeking, tracking and accurate down-hole sensor positioning. To address challenges in the surface mining environment, where GPS and odometry data are noisy without RTK correction, we adopt a proximity-based adaptive navigation approach, enabling the vehicle to dynamically adjust its operations based on detected target availability and localisation accuracy. For perception, we process LiDAR data to extract the cone-shaped volume of drill-waste above ground, then project the 3D cone points into a virtual depth image to form accurate 2D segmentation of hole regions. To ensure continuous target-tracking as the robot approaches the goal, our system automatically adjusts projection parameters to preserve consistent hole image appearance. At the vicinity of the hole, we apply least squares circle fitting with non-maximum candidate suppression to achieve accurate hole detection and collision-free down-hole sensor placement. We demonstrate the effectiveness of our navigation and perception system in both high-fidelity simulation environments and on-site field trials. A demonstration video is available at https://www.youtube.com/watch?v=fRNbcBcaSqE.

cs.RO↗

arXiv2025

Direct laser ablation of 2D material films for fabricating multi-functional flexible and transparent devices

We present a scalable method for direct patterning of graphite and transition metal dichalcogenide (TMD) films on polycarbonate (PC) and other transparent substrates using fiber laser ablation. This process facilitates the fabrication of various functional devices, including strain gauges, supercapacitors, and photodetector arrays, without the need for photolithography or solvents, thereby simplifying device production and enhancing environmental sustainability. Utilizing roll-to-roll mechanical exfoliation, homogeneous nanosheet films are created and then patterned with a laser engraving system. Electrical and optical characterization confirms that the laser-processed films maintain their crystallinity, with no observable damage to the underlying substrate. We demonstrate the scalability of this approach by constructing a WSe2/graphite photodetector array on PC, which exhibits high sensitivity, low noise, and uniform photocurrent response across its active channels. As a proof-of-concept, this array is used as an image sensor to capture light patterns, showcasing its potential for flexible and semi-transparent imaging applications. These findings open up new avenues for incorporating all-van der Waals devices into wearable electronics, optoelectronics, and imaging technologies.

physics.app-ph↗

arXiv2023

Physics-based bias-dependent compact modeling of 1/f noise in single- to few- layer 2D-FETs

1/f noise is a critical figure of merit for the performance of transistors and circuits. For two-dimensional devices (2D-FETs), and especially for applications in the GHz range where short-channel FETs are required, velocity saturation (VS) effect can result in the reduction of 1/f noise at high longitudinal electric fields. A new physics-based compact model is for the first time introduced for single- to few- layer 2D-FETs in this study, precisely validating 1/f noise experiments for various types of devices. The proposed model mainly accounts for the measured 1/f noise bias dependence as the latter is defined by different physical mechanisms. Thus, analytical expressions are derived, valid in all regions of operation in contrast to conventional approaches available in literature so far, accounting for carrier number fluctuation (DN), mobility fluctuation (Dmu}) and contact resistance (DR) effects based on the underlying physics that rules these devices. DN mechanism due to trapping/detrapping together with an intense Coulomb scattering effect, dominates 1/f noise from medium to strong accumulation region while Dmu, is also demonstrated to modestly contribute in subthreshold region. DR can also be significant in very high carrier density. The VS induced reduction of 1/f noise measurements at high electric fields, is also remarkably captured by the model. The physical validity of the model can also assist in extracting credible conclusions when conducting comparisons between experimental data from devices with different materials or dielectrics.

cond-mat.mes-hall↗

arXiv2022

Computer vision application for improved product traceability in the granite manufacturing industry

The traceability of granite blocks consists in identifying each block with a finite number of color bands which represent a numerical code. This code has to be read several times throughout the manufacturing process, but its accuracy is subject to human errors, leading to cause faults in the traceability system. A computer vision system is presented to address this problem through color detection and the decryption of the associated code. The system developed makes use of color space transformations, and several thresholds for the isolation of the colors. Computer vision methods are implemented, along with contour detection procedures for color identification. Lastly, the analysis of geometrical features is used to decrypt the color code captured. The proposed algorithm is trained on a set of 109 pictures taken in different environmental conditions and validated on a set of 21 images. The outcome shows promising results with an accuracy rate of 75.00% in the validation process. Therefore, the application presented can help employees reduce the number of mistakes on product tracking.

cs.CV↗

arXiv2017

E-polynomials of $PGL(2,\mathbb{C})$-character varieties of surface groups

In this paper, we compute the E-polynomials of the $PGL(2,\mathbb{C})$-character varieties associated to surfaces of genus $g$ with one puncture, for any holonomy around it, and compare it with its Langlands dual case, $SL(2,\mathbb{C})$. The study is based on the stratification of the space of representations and on the analysis of the behaviour of the E-polynomial under fibrations.

math.AG↗

arXiv2016

Mid-infrared surface plasmon polariton chemical sensing on fiber-coupled ITO coated glass

A novel fiber-coupled ITO coated glass slide sensor for performing surface plasmon polariton chemical monitoring in the 3.5 um mid-IR range is reported. Efficient mid-IR fiber coupling is achieved with 3D laser written waveguides, and the coupling of glass waveguide modes to ITO SPPs is driven by the varying phase matching conditions of different aqueous analytes across the anomalous dispersion range determined by their molecular fingerprints. By means of using both a mid-IR fiber supercontinuum source and a diode laser the excitation of SPPs is demonstrated. The efficient optical monitoring of mid-IR SPPs in smart glass could have a broad range of applications in biological and chemical sensing.

physics.optics↗

arXiv2014

E-polynomial of SL(2,C)-character varieties of complex curves of genus 3

We compute the E-polynomials of the moduli spaces of representations of the fundamental group of a complex curve of genus g=3 into $ SL(2,C), and also of the moduli space of twisted representations. The case of genus g=1,2 has already been done in [http://arxiv.org/abs/1106.6011]. We follow the geometric technique introduced in [http://arxiv.org/abs/1106.6011], based on stratifying the space of representations, and on the analysis of the behaviour of the E-polynomial under fibrations.

math.AG↗