Fiber absorption measurement errors resulting from re-emission of radiation

We show that errors in the absorption measured in rare-earth-doped fibers can exceed 50% and severely distort the spectral shape. This is a result of re-emission in fibers with overlapping absorption and emission spectra

Physical Exercise and Its Protective Effects on Diabetic Cardiomyopathy: What Is the Evidence?

As one of the most serious complications of diabetes, diabetic cardiomyopathy (DCM) imposes a huge burden on individuals and society, and represents a major public health problem. It has long been recognized that physical exercise has important health benefits for patients with type 2 diabetes, and regular physical exercise can delay or prevent the complications of diabetes. Current studies show that physical exercise has been regarded as an importantly non-pharmacological treatment for diabetes and DCM, with high efficacy and low adverse events. It can inhibit the pathological processes of myocardial apoptosis, myocardial fibrosis, and myocardial microvascular diseases through improving myocardial metabolism, enhancing the regulation of Ca2+, and protecting the function of mitochondria. Eventually, it can alleviate the occurrence and development of diabetic complications. Describing the mechanisms of physical exercise on DCM may provide a new theory for alleviating, or even reversing the development of DCM, and prevent it from developing to heart failure

Multi-disruption resilience assessment of rail transit systems with optimized commuter flows

This paper studies the resilient performance of urban rail transit systems by extending a linear programming optimization model, which can provide optimized commuter flows with contingency routing under multiple disruptions. The rail transit systems in Singapore and Chongqing (China) are selected as case studies, and the system resilience and the effectiveness of providing bus-bridging services are comparatively studied. Intuitively, failures of the interchange stations would inevitably lead to a significant loss of resilience due to deteriorated network connectivity. However, the Singapore case shows that attacking those interchange stations does not always result in an extensive resilience loss. Comparing with the Chongqing case, it is discernible that the position of interchange stations would affect the system resilience. The numerical simulations reveal that the positive effect of providing bus-bridging strategy, in terms of improving the system resilience, is heterogeneous in different systems, which varies from 14% to 30% on average. As demonstrated in the sensitivity on travel demands, this positive effect is robust, yet dynamic, indicating that there is no one-size-fits-all solution for designing transfer-based recovery strategies in disruption management of rail transit systems. The managerial implications for decision makers are also provided and discussed in terms of infrastructure planning

Absorption measurement errors in single-mode fibers resulting from re-emission of radiation

We investigate errors in small-signal absorption spectra that result from re-emission in single-mode fibers with overlapping absorption and emission spectra. Experiments on Er-doped fibers and simulations of Er- and Yb-doped fibers show that the re-emission can severely distort the spectrum, especially the peak, under common measurement conditions, and underestimate the absorption by well over 10% already at 30-dB peak absorption, if only the source or the detector is spectrally filtered. Re-emission can then be the dominant source of errors. The error increases for higher absorption and higher fiber-NA. For sufficiently high NA, a significant error remains even in the limit of zero absorption and reaches 5% at the peak of a 0.46-NA Yb-doped fiber. Furthermore, in contrast to the high-absorption case, the error is larger at longer wavelengths than at the peak. Simultaneous filtering of both source and detector with 0.1-nm bandwidth reduces the re-emission error to ~1% or less up to 90-dB absorption. Then, detector noise or saturation errors are likely to dominate and render re-emission errors insignificant. A standard amplifier model is well suited to the simulations of the rich physics of single-mode-fiber absorption measurements

Data for ASSL conference paper "Fiber absorption measurement errors resulting from re-emission of radiation"

We show that errors in the absorption measured in rare-earth-doped fibers can exceed 50% and severely distort the spectral shape. This is a result of re-emission in fibers with overlapping absorption and emission spectra.</span

Absorption measurement errors in single-mode fibers resulting from re-emission of radiation

We investigate errors in small-signal absorption spectra that can result from re-emission of absorbed photons in fibers with overlapping absorption and emission spectra. Experiments on Er-doped fibers as well as simulations of Er and Yb-doped single-mode fibers show that the re-emission can severely distort the spectral shape, especially the peak, under common measurement conditions. Errors can reach well over 10% already at 30 dB peak absorption, and 5% at 20 dB, if only the source or the detector is spectrally filtered. Re-emission can then be the dominant source of error. These levels of absorption are well within the dynamic range of commonly-used equipment, so it is easy to make the mistake of measuring too high absorption and thus introduce re-emission errors. The error increases for higher fiber-NA, and for sufficiently high NA, a significant error remains also in low-absorbing fibers, even in the limit of zero absorption. The error can then reach 5% at the peak of a 0.46-NA Yb-doped fiber. Furthermore, in contrast to the case of high absorption levels, the error is larger for longer wavelengths than it is at the peak. On the other hand, if both source and detector are spectrally filtered with 0.1 nm bandwidth then the re-emission error becomes as low as around 1% even for as much as 90 dB absorption. At such high absorption, other sources of error such as receiver noise and saturation effects are likely to be higher, so that re-emission are no longer significant. We also conclude that that standard amplifier models are well suited to simulations of the rich physics of absorption measurements of single-mode fibers. Original spreadsheet updated 2017-05-04 to combine fig 5a and fig 5b into a single fig 5. Funded by AFOSR (FA9550-14-1-0382).</span

Absorption Measurement Errors in Single-Mode Fibers Resulting From Re-Emission of Radiation

We investigate errors in small-signal absorption spectra that result from re-emission in single-mode fibers with overlapping absorption and emission spectra. Experiments on Er-doped fibers and simulations of Er- and Yb-doped fibers show that the re-emission can severely distort the spectrum, especially the peak, under common measurement conditions, and underestimate the absorption by well over 10% already at 30-dB peak absorption, if only the source or the detector is spectrally filtered. Re-emission can then be the dominant source of errors. The error increases for higher absorption and higher fiber-NA. For sufficiently high NA, a significant error remains even in the limit of zero absorption and reaches 5% at the peak of a 0.46-NA Yb-doped fiber. Furthermore, in contrast to the high-absorption case, the error is larger at longer wavelengths than at the peak. Simultaneous filtering of both source and detector with 0.1-nm bandwidth reduces the re-emission error to ~1% or less up to 90-dB absorption. Then, detector noise or saturation errors are likely to dominate and render re-emission errors insignificant. A standard amplifier model is well suited to the simulations of the rich physics of single-mode-fiber absorption measurements