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- Backscatter measurement (1)
- CO2 separation membranes (1)
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- OTDR (1)
- Optical fiber sensors (1)
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- SDC (1)
- Samarium doped ceria (1)
- Scavenging effect of iron (1)
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This article reports on recent advancements in the field of distributed optical fiber sensing with a focus on the monitoring of geotechnical structures and buildings. While the classical time-domain approach to distributed sensing is widely known, this article provides an introduction into the frequency-domain analysis technique for both distributed Brillouin measurements (as commonly used for strain and temperature monitoring) and for linear backscattering measurements. The article also addresses an issue which arises when truly distributed measurements are compared among each other; a new approach to calculate differential curves from a measurement and a base-line which avoids misleading large amplitudes at physical events with strong gradients is proposed. Finally, a field test of a new read-out technology, the OFDR (optical frequency domain reflectometry) technique providing dynamic readings of length changes between discrete fiber positions, is presented.
We propose a digital implementation of the incoherent optical frequency domain reflectometry (I-OFDR) technique for precise backscatter measurement and optical fiber sensing applications. Specific performance parameters of the I-OFDR are discussed and compared to an analog vector network analyzer-based I-OFDR system. Improved sensitivity, dynamic range and signal stability of the digital I-OFDR is presented and demonstrated by means of quasi-distributed length change measurement.
Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.