Overcoming the barrier of nanoparticle production by femtosecond laser ablation in liquids using simultaneous spatial and temporal focusing

There exists an increasing demand of industrial-scale production of high-purity ligand-free nanoparticles due to the continuous development of biomedicine, catalysis, and energy applications. In this contribution, a simultaneous spatial and temporal focusing(SSTF) setup is first proposed for increasing nanoparticle productivity of the eco-friendly pulsed laser ablation in liquids(PLAL) technique. In spite of the fact that femtosecond pulses have proved to achieve higher ablation rates in air than picosecond pulses, in PLAL this is reversed due to the nonlinear energy losses in the liquid. However, thanks to the incorporation of SSTF, the energy delivered to the target is increased up to 70%, which leads to a nanoparticle production increase of a 2.4 factor. This breaks a barrier toward the employment of femtosecond lasers in high-efficiency PLAL.

A domain-independent methodology to analyze IoT data streams in real-time.A proof of concept implementation for anomaly detection from environmental data

Pushed by the Internet of Things(IoT)paradigm modern sensor networks monitor a wide range of phenomena,in areas such as environmental monitoring,health care,industrial processes,and smart cities.These networks provide a continuous pulse of the almost infinite activities that are happening in the physical space and are thus,key enablers for a Digital Earth Nervous System.Nevertheless,the rapid processing of these sensor data streams still continues to challenge traditional data-handling solutions and new approaches are being requested.We propose a generic answer to this challenge,which has the potential to support any form of distributed real-time analysis.This neutral methodology follows a brokering approach to work with different kinds of data sources and uses web-based standards to achieve interoperability.As a proof of concept,we implemented the methodology to detect anomalies in real-time and applied it to the area of environmental monitoring.The developed system is capable of detecting anomalies,generating notifications,and displaying the recent situation to the user.

Time-expanded phase-sensitive optical time-domain reflectometry

Phase-sensitive optical time-domain reflectometry(CDOTDR)is a well-established technique that provides spatiotemporal measurements of an environmental variable in real time.This unique capability is being leveraged in an everincreasing number of applications,from energy transportation or civil security to seismology.To date,a wide number of different approaches have been implemented,providing a plethora of options in terms of performance(resolution,acquisition bandwidth,sensitivity or range).However,to achieve high spatial resolutions,detection bandwidths in the GHz range are typically required,substantially increasing the system cost and complexity.Here,we present a novel OOTDR approach that allows a customized time expansion of the received optical traces.Hence,the presented technique reaches cm-scale spatial resolutions over t km while requiring a remarkably low detection bandwidth in the MHz regime.This approach relies on the use of dual-comb spectrometry to interrogate the fibre and sample the backscattered light.Random phase-spectral coding is applied to the employed combs to maximize the signal-to-noise ratio of the sensing scheme.A comparison of the proposed method with alternative approaches aimed at similar operation features is provided,along with a thorough analysis of the new trade-offs.Our results demonstrate a radically novel high-resolution OOTDR scheme,which could promote new applications in metrology,borehole monitoring or aerospace.

Three-dimensional trees for virtual globes

One of the problems in virtual globes technologies is the real-time representation of vegetal species.In forest or garden representations,the low detailed plants produce a lack of realism.Efficient techniques are required to achieve accurate interactive visualisation due to the great number of polygons the vegetal species have.This article presents a multi-resolution model based on a geometric representation of vegetal species that allows the application to perform the progressive transmission of the model,that is,the transmission of a simple representation followed by successive refinements of it.It has a hardware-oriented design in order to obtain interactive frame rates.The geometric data of the objects are stored in the graphics processing unit and,moreover,the change from one approximation to another is obtained by performing mathematical calcula-tions in this graphics hardware.The multi-resolution model presented here enables instancing:as many vegetal species as desired can be rendered with different levels of detail,while all of them are accessing the same geometric data.This model has been used to build a real-time representation of a not imaginary scenario.