scholarly journals Instrumentation of Stratospheric Balloon Straps with Optical Fibre for Temperature and Strain Monitoring

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1433 ◽  
Author(s):  
Yann Lecieux ◽  
Cyril Lupi ◽  
Dominique Leduc ◽  
Quentin Macé ◽  
Valentin Jeanneau ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Pressure Field ◽  
Numerical Models ◽  
Industrial Process ◽  
Mechanical Tests ◽  
Optical Fibres ◽  
Frequency Shifts ◽  
Strain Monitoring ◽  
Stratospheric Balloon

This article is devoted to the instrumentation, with optical fibres, of the straps holding the envelope of stratospheric balloons. This instrumentation is motivated in the first instance by the need to validate the numerical models used in the design of balloons. It must also be used to measure the temperature along the envelope in order to deduce the pressure field. It is shown at first that the optical fibres can be inserted inside a strap during its fabrication. Different kinds of insertion are considered, none of them perturb the industrial process. The instrumented straps were then submitted to thermal and mechanical tests and the distributed Brillouin frequency shifts were measured. We thus determined the type of insertion to be used according to the parameter (temperature or strain) to be measured and assessed the performance of the measurement chain.

Assessing the Feasibility of Monitoring the Condition of Historic Tapestries Using Engineering Techniques

2007 ◽  
Vol 347 ◽  
pp. 187-192 ◽  
Author(s):  
Janice M. Dulieu-Barton ◽  
M. Sahin ◽  
F.J. Lennard ◽  
D.D. Eastop ◽  
A.R. Chambers
Keyword(s):  
Optical Fibre ◽  
Strain Measurement ◽  
Measurement Techniques ◽  
Mechanical Tests ◽  
Textile Material ◽  
Full Field ◽  
Strain Monitoring ◽  
Optical Strain Measurement ◽  
Optical Strain

The findings of a year-long programme carried out by a multidisciplinary engineering/conservation team are described. A mass-produced textile material that can be used to represent tapestries is identified and mechanical tests are detailed which demonstrate it behaves in a similar way to tapestry. The feasibility of using optical fibre sensors, full-field optical strain measurement techniques and thermography for monitoring tapestry degradation is assessed. The results of preliminary findings are presented and a rationale is developed for in-situ quantitative strain monitoring of tapestries.

scholarly journals Mechanical Testing of Composite Steel and Reactive Powder Concrete Structural Element

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3954
Author(s):  
Jan Bujnak ◽  
Peter Michalek ◽  
Frantisek Bahleda ◽  
Stefania Grzeszczyk ◽  
Aneta Matuszek-Chmurowska ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Composite Structures ◽  
Numerical Models ◽  
Concrete Slab ◽  
Initial Study ◽  
Cementitious Materials ◽  
Mechanical Tests ◽  
Reactive Powder Concrete ◽  
Structural Element ◽  
Reactive Powder

Reactive powder concrete (RPC), typically with higher compressive strength, is particularly attractive to structural engineers to apply them in infrastructures for enhancing their resistance under severe environments and loads. The main objective of the initial study presented in the paper was to investigate the behavior of two types of these new cementitious materials differing in the nature of microfibers. The RPC mixes were reinforced with steel and then with basalt microfibers. To evaluate the structural performance of developed unconventional materials, properties were investigated experimentally and compared with the control normal concrete mix. Mechanical tests indicated that dispersing fine fibers for making RPC, a mean compressive strength of 198.3 MPa and flexural strength 52.6 MPa or 23.2 MPa, respectively, were developed after 28 days of standard curing at ambient temperatures. In composite structures consisting of steel girders and a concrete slab, it is necessary to prevent the relative slip at the steel and concrete interface using shear connectors. The very high RPC strength enabled a material saving, weight-reduced application of precast construction, and particularly effective joint to steel beams. The investigation of such shear connection efficiency, in the case of the higher strength concrete deck, using standard push-out test specimens was executed. Finite element numerical models were developed. The outputs of the studies are presented in the paper.

scholarly journals Implications of information theory in optical fibre communications

2016 ◽  
Vol 374 (2062) ◽  
pp. 20140438 ◽  
Author(s):  
Erik Agrell ◽  
Alex Alvarado ◽  
Frank R. Kschischang
Keyword(s):  
Information Theory ◽  
Optical Fibre ◽  
Optical Fibres ◽  
Limited Capacity ◽  
Fibre Optic ◽  
Precious Resource ◽  
Basic Concepts

Recent decades have witnessed steady improvements in our ability to harness the information-carrying capability of optical fibres. Will this process continue, or will progress eventually stall? Information theory predicts that all channels have a limited capacity depending on the available transmission resources, and thus it is inevitable that the pace of improvements will slow. However, information theory also provides insights into how transmission resources should, in principle, best be exploited, and thus may serve as a guide for where to look for better ways to squeeze more out of a precious resource. This tutorial paper reviews the basic concepts of information theory and their application in fibre-optic communications.

Microwave-frequency carriers on optical fibres

1989 ◽  
Vol 329 (1603) ◽  
pp. 23-36 ◽  
Keyword(s):  
Optical Fibre ◽  
Microwave Frequency ◽  
Optical Fibres ◽  
New Approach ◽  
Large Bandwidth ◽  
Design Flexibility ◽  
Baseband Signal ◽  
Microwave Multiplexing ◽  
Voice Data ◽  
Natural Way

The use of microwave carrier frequencies in wideband optical-fibre networks is a promising new approach to the distribution of voice, data and video services to subscribers. This paper discusses the general features and design rules of microwave multiplexed wideband optical-fibre systems and reports on several specific systems developed at GTE Laboratories. These include transmission of 60 frequency modulated (FM) video channels multiplexed on carriers in the 2.7-5.2 GHz band, and the transmission of 20 frequency-shift-keyed (FSK) 100 Mb s -1 digital video channels in the 2-6 GHz band. A hybrid system is also described that transmits a 100 Mb s -1 baseband signal in addition to the 60 FM video channels. These transmission experiments illustrate the large bandwidth capability and design flexibility of microwave-multiplexed lightwave systems. As lightwave systems push towards larger and larger bandwidths, microwave-multiplexing may emerge as the more natural way to exploit the enormous bandwidth of lightwave components.

scholarly journals Numerical Modelling of the Ultrasonic Treatment of Aluminium Melts: An Overview of Recent Advances

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3262 ◽  
Author(s):  
Bruno Lebon ◽  
Iakovos Tzanakis ◽  
Koulis Pericleous ◽  
Dmitry Eskin
Keyword(s):  
Best Practice ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
State Of The Art ◽  
Liquid Metals ◽  
Numerical Models ◽  
Acoustic Cavitation ◽  
Velocity Fields ◽  
Melt Processing ◽  
Best Practice Guidelines

The prediction of the acoustic pressure field and associated streaming is of paramount importance to ultrasonic melt processing. Hence, the last decade has witnessed the emergence of various numerical models for predicting acoustic pressures and velocity fields in liquid metals subject to ultrasonic excitation at large amplitudes. This paper summarizes recent research, arguably the state of the art, and suggests best practice guidelines in acoustic cavitation modelling as applied to aluminium melts. We also present the remaining challenges that are to be addressed to pave the way for a reliable and complete working numerical package that can assist in scaling up this promising technology.

Models and Analysis of the Pressure Field for a Hybrid Electric Vehicle With a Fuel Vapor-Containment System in a Refueling Process

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Yanyue Fang ◽  
Ren He ◽  
Baowei Fan
Keyword(s):  
Vapor Pressure ◽  
Electric Vehicle ◽  
Hybrid Electric Vehicle ◽  
Pressure Field ◽  
Numerical Models ◽  
Pressure Change ◽  
Pipe Diameter ◽  
Fuel Vapor ◽  
Containment System ◽  
Hybrid Electric

In order to ensure and improve the performance of the fuel vapor-containment system (FVS) on a hybrid electric vehicle (HEV), the vapor pressure field of the evaporative (EVAP) system in the refueling process was analyzed. Numerical models were established to describe the pressure change in the EVAP system. Based on these numerical models, the influences of refueling speed, filler pipe diameter, vent pipe diameter, and fuel vapor-containment valve (FVV) port diameter on pressure change were discussed. The numerical models and the influences of aforementioned effects were validated by experiments. Simulation and experimental results indicated that the vapor pressure field in the EVAP system is more susceptible to the change of refueling speed and FVV port diameter. If the refueling speed increased and the FVV port diameter decreased, the vapor pressure in the EVAP system strongly fluctuated. Furthermore, results also show that the FVV port diameter should be as large as possible but less than 20 mm, while refueling speed should be 50 l/min. The filler pipe diameter can be chosen in the range of 23–28 mm.

scholarly journals FEM-Based Methodology for the Design of Reduced Scale Representative Experimental Testing Allowing the Characterization of Defect Evolution during Hot Rolling of Bars

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1035
Author(s):  
Corentin Pondaven ◽  
Laurent Langlois ◽  
Régis Bigot ◽  
Damien Chevalier
Keyword(s):  
Hot Rolling ◽  
Numerical Models ◽  
Experimental Testing ◽  
Effective Strain ◽  
Fem Simulation ◽  
Industrial Process ◽  
Cylindrical Sample ◽  
Forming Process ◽  
Defect Evolution ◽  
Reduced Scale

Defects generated during the casting process of steel can be reduced by forming processes such as hot rolling. During these processes the effective strain, the temperature, the stress state and the alternation of the forming direction all influence the defect evolution. Analytical or numerical models are available in the literature to predict the defect evolution. However, experiments have to be carried out to identify the parameters of these models. Thus, the quality of the identification depends on the representativeness of the experiments with respect to the industrial forming process. This paper proposes a methodology to design reduced scale experiments with an improved level of representativeness. This methodology consists first in the identification of the thermomechanical parameters driving the defect evolution and the quantification of these parameters in the industrial process by FEM simulation. These last results are then utilised as criteria for the representative experiment design. In this work the methodology is applied to the rolling of bars. The representative experiment consists of successive forming operations of a cylindrical sample between shaped anvils reproducing the roll shape at a 1:10 scale. A validation is finally achieved by reproducing qualitative results concerning the evolution of voids in the vicinity of hard inclusions.

scholarly journals Prospects for Fibreoptics in Future Telescope Instrumentation

1984 ◽  
Vol 79 ◽  
pp. 617-635 ◽  
Author(s):  
Glenn Lund
Keyword(s):  
Full Advantage ◽  
Optical Fibre ◽  
Optical Systems ◽  
Optical Fibres ◽  
Astronomical Instrumentation ◽  
The Past ◽  
Single Instrument

The importance and applied use of fibreoptics in astronomy has received rapidly growing attention in the past 5 years, particularly for instrumentation where the lightness, flexibility and simplicity of fibres, compared with classical optical systems, can be exploited to full advantage.Angel and Angel et al, who seem to be the first to have used an optical fibre to link a telescope to an instrument, also made the first proposal for the construction of a VLT (FLOAT) consisting of 40 independent mirrors linked to a single instrument via optical fibres. Since that time many authors, including Connes, Serkowski et al, Hubbard et al, Heacox, Hill et al, Vanderriest, Courtes, Tubbs et al, Gray, Lund et al, Schiffer, Watson et al, Vanderriest et al, and Felenbock et al, have proposed or reported various applications involving fibres with astronomical instrumentation.

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