- Université Gustave Eiffel
- Research Field
- Computer science
- Researcher Profile
- First Stage Researcher (R1)
- Application Deadline
- Type of Contract
- Job Status
- Hours Per Week
- Is the job funded through the EU Research Framework Programme?
- H2020 / Marie Skłodowska-Curie Actions COFUND
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- Is the Job related to staff position within a Research Infrastructure?
State of the art
To date, the continuous development in distributed fiber optic sensors (DFOS) technologies for physical parameters measurements (e.g. temperature, mechanical strain, mechanical and acoustic vibrations) has enabled the deployment of these sensors in real applications in numerous domains (e.g. civil engineering, geotechnics, intelligent structures) [1-6]. Therefore, DFOSs can be particularly suitable for instrumentation in areas that are difficult to access or in restrictive environments where conventional sensors are not functional. In the case of complex and large-scale civil engineering structures, the DFOS instrumentation network and the installation geometry require the compatibility between the following three components:
1.The optoelectronic interrogation unit:
This unit is the "brain" of the network that carries out an interrogation on the optical fiber core and translates the intrinsic measured characteristics into strain or thermal values. The interrogation techniques are based on optical time (or frequency) domain reflectometry; making it possible to obtain the profile of strain and/or temperature along the optical fiber with tens of thousands of measurement points. This unit is mainly characterized by:
-the investigated backscattering phenomena (Rayleigh, Brillouin or Raman)
-the optical power unit and the detection sensitivity
-the electronic processing unit capacity
These characteristics would allow, depending on the type of the sensing optical fiber, to specify the range, the spatial resolution, the mechanical/thermal sensitivity and finally the acquisition frequency.
2.The fiber optic sensing cable (i.e. neuron) installed in a host medium:
Consists of one optical fiber or more assembled in a single cable. The different layers of sensing cable should protect and fully transfer the structural strain/thermal field into the optical fiber core. The sensing cable design should satisfy all the constraints related to host medium the installation, conditions of use and operation [7-9]. DFOSs that are based on optical reflectometry techniques explore the optical fiber as uniaxial sensor along its axis of symmetry [10-11]. "Neuron" is characterized mainly by its geometry, materials, mechanical/thermal characteristics, mechanical adhesion/thermal conductivity between the various layers of the cable and their long-term chemical stabilities.
3.The interconnection cables:
The connection fibers must guarantee an optical signal transfer between the optoelectronic unit (i.e. brain) and the sensor cable (i.e. neuron), without degradation. It may contain active and passive optical components (e.g. optical switches, optical amplifiers) to distribute the optical signal to the different “neurons” depending on the complexity of the instrumented structure. However, the implementation of an efficient and sustainable DFOSs network into infrastructures depends on the following instrumentation objectives:
-Providing structural health alerts
-Detection, quantification, classification of anomalies (e.g. cracks in concrete) and monitor their evolution
-Measurement of strain, mechanical vibrations and temperature with high precision 
This implantation works perfectly for all structures in laboratory conditions and in controlled environment. However, as soon as the structure is exposed to external or environmental disturbances, the different measurements become unusable and the instrumentation network becomes non-functional. Up today, the majority of DFOSs applications in large structures instrumentation have been carried out with low external disturbances and limited durations.
In general, the acquired information delivered by the optoelectronic interrogation unit needs post-processing operations with a significant investigation time. This procedure becomes very complex for massive data in the presence of various disturbances; particularly, the instrumentation of large structures and various parameters.
Therefore, the use of DFOS has been limited to specific cases such as linear installation of optical fibers, low environmental disturbances within a short term. IMSE Lab. has developed its expertise to deliver an accurate measurement of the strain and thermal variations profile that allows early identification of anomalies in different types of structures and applications [12-17].
The objective of this thesis will be to study and validate the concept of a “smart” DFOS: it is required to develop a method with massive processing of measurements obtained by optical fibers in real structures with a complex geometry, that may undergo various environmental disturbances. The main expected results are: an accurate profile of mechanical strain and thermal variations and an automatic diagnostic of the opening of cracks in contact with the sensing optical fiber and the identification of microcracks.
Therefore, we are considering the following three axes:
To work on optical signal processing in order to improve signal quality and translate the acquired data. Analyzing the instrumentation network considering the parameters of the optoelectronic interrogation unit, connection cables and sensors. We will mainly use the optical frequency domain reflectometry technique based on Rayleigh backscattering. This technique provides access to the intrinsic data of the optical fiber with millimetric spatial resolution; particularly the evolution of the polarization of light in the fiber during its propagation. Additional methods like Brillouin based techniques will be investigated.
Fabrication of different samples of reinforced concrete (i.e. host medium). DFOS sensing cables will be installed inside the samples during manufacturing, supplementary cables would be installed on the surface afterword. In the meanwhile, conventional instrumentation will also be put in place. External mechanical disturbances will be introduced via piezoelectric components, cyclic thermal variations and then a controlled mechanical degradation of the samples. We will analyze the sensor performance with different optoelectronic transducers and specially the photoreceiver unit. Integrated semiconductor optical amplifier and photodiode (SOA-PD) will be used and compared to classical solution EDFA-PD (Erbium Doped Fiber Amplifier – PD).
c- AI implementation:
Implementation of algorithms to obtain strain profiles as a function of the temperature of the host medium to identify cracks and microcracks. In this phase, the development of a mechanical and thermal transfer function of optical fiber sensing cables should be studied. These algorithms will permit to optimize the post-processing of the acquired signals.
 A. Tixier, Université de Grenoble 2013
 H. MOUZANNAR, Université de Lyon 2016
 D. A. Ho, Université de Lyon 2017
 V. RAMAN, École centrale de Nantes 2017
 J. G. De Sauvage, Université de Lyon 2018
 I. ALJ, Université Paris-Est 2020
- Research Field
- Computer science
- Education Level
- Bachelor Degree or equivalent
- At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree.
- At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.
- High-quality doctoral training rewarded by a PhD degree, delivered by Université Gustave Eiffel
- Access to cutting-edge infrastructures for research & innovation.
- Appointment for a period of 36 months based on a salary of 2 700 € (gross salary per month).
- Job contract under the French labour legislation in force, respecting health and safety, and social security: 35 hours per week contract, 25 days of annual leave per year.
- International mobility will be mandatory
- An international environment supported by the adherence to the European Charter & Code.
- Access to dedicated CLEAR-Doc trainings with a strong interdisciplinary focus, together with a Career development Plan.
- At the time of the deadline, applicants must be in the first four years (full-time equivalent research experience) of their research career (career breaks excluded) and not yet been awarded a doctoral degree. Career breaks refer to periods of time where the candidate was not active in research, regardless of his/her employment status (sick leave, maternity leave etc). Short stays such as holidays and/or compulsory national service are not taken into account.
- At the time of the deadline, applicants must fulfil the transnational mobility rule: incoming applicants must not have resided or carried out their main activity (work, studies, etc.) in France for more than 12 months in the 3 previous years.
- One application per call per year is allowed.
- Applicants must be available full-time to start the programme on schedule (November 1st 2023).
- Application rules are enforced by the French doctoral system which specifies a standard duration of 3 years for a full-time PhD together with the MSCA standards and the OTM-R European rules as follows.
- Citizens of any nationality may apply to the programme.
- There is no age limit.
Please refer to the Guide for Applicants available on the CLEAR-Doc website: https://clear-doc.univ-gustave-eiffel.fr/how-to-apply/useful-documents/
- The First step before applying is contacting the PhD supervisor. You will not be able to apply without an acceptation letter from the PhD supervisor.
- International mobility planned:
The Applicant will have an international mobility at Politecnico di Milano
- Please contact the PhD supervisor for any additional detail on job offer.
- There are no restrictions concerning the age, gender or nationality of the candidates. Applicants with career breaks or variations in the chronological sequence of their career, with mobility experience or with interdisciplinary background or private sector experience are welcome to apply.
- Support service is available during every step of the application process by email: firstname.lastname@example.org
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