Cavity enhanced Raman spectroscopy (CERS) is an emerging technique for real time analysis of gas mixtures. In this paper, the authors employed a passive self-injection locking technique utilizing an anti-reflection (AR) coated blue laser diode and a high finesse external power build-up cavity (PBC) for trace gas analysis by CERS. With a 20 to 30-mW laser diode passively injection locked to resonant frequencies of the PBC by optical feedback, a power build-up factor greater than 5000 and internal power storage of over 100 W were achieved. To the best of our knowledge, this is the first demonstration of a power build-up cavity pumped by a passively frequency locked AR coated laser diode in the violet-blue wavelength region. In an implementation of this method, limit of detection (LOD) of 0.7 ppm for hydrogen gas at atmospheric pressure was successfully demonstrated in a 1-minute measurement. This system is simple and robust without any electronic controls, suitable for compact field applications.
In this study, we examined the feasibility of thermal energy storage (TES) in individual distributed air conditioning systems for adjusting the renewable power supply and the cooling/heating demands in buildings. Effective TES schedule was determined based on daily changes in area-dependent prices, as an index representing the renewable power supply, by energy simulation in which cooling/heating loads measured in an office building in Kochi were given as the input. The calculation result indicated that the electricity price in the proposed TES system was reduced by 10.4% in summer and 16.5% in winter from a conventional air conditioning system without TES.
Fault damage zones record the evolution of brittle deformation and play a key role in controlling rock strength and fluid flow. In this study, we quantitatively evaluate the width and internal architecture of the fault damage zone along the Median Tectonic Line (MTL) in southwest Japan using an integrated geological and geophysical approach. A 125 m-long drilled core penetrating the MTL was analyzed using detailed geological core observation, fracture analysis, X-ray computed tomography (X-CT), and borehole geophysical logging data. We developed and applied a new image-processing method to automatically extract open crack parameters, including crack density, intensity, and mean length, from X-CT images. Cumulative frequency curves of open cracks reveal a highly asymmetric open crack–based damage zone (OCDZ): 24 m wide in the hanging wall and only 2 m in the footwall. This asymmetry is further supported by variations in rock rigidity. A reanalysis of published displacement–damage zone width scaling shows that lithology exerts a stronger control than structural position, consistent with the mechanical contrast between the weaker Izumi Group sedimentary rocks in the hanging wall and the stronger Sambagawa metamorphic rocks in the footwall. Depth constraints indicate that the OCDZ formed at shallow crustal levels (< 3.5 km depth) under a normal-faulting regime during 15–14 Ma, consistent with conditions inferred from clay mineral stability. Our integrated approach, combining geological and geophysical datasets from drilled cores, provides a framework for characterizing fault damage zones at shallow crustal levels. Such quantitative characterization is essential for constraining the conditions and timing of damage zone development in long-lived faults such as the MTL, where multiple deformation phases are superimposed.
The Aso-4 explosive eruption on Kyushu, Japan, 89,500 years ago was one of the biggest eruptions in the last one hundred millennia, with a magnitude of approximately M8. Modern society requires the likelihood of natural events with potentially disastrous consequences to be evaluated, even if probabilities of occurrence are diminishingly small. For some situations, it is not satisfactory to assert an event scenario probability is “negligible” or can be “ignored”. Judicial hearings or litigation may require risk levels to be quantified, in which case, statements of scientific confidence could be decisive. Internationally, e.g., for nuclear site safety evaluations, event likelihoods on order of 10–7/year are often considered for quantitative assessment. At such hazard levels, this might include evaluating the proposition that a particular volcano can deliver a future super-eruption, a supposition that could be attached to Aso volcano. But, simplistically taking the average recurrence interval between past caldera-forming eruptions at a given volcano is an unreliable guide to the likelihood of a future repeat: each past event represented a unique set of tectonic and magmatic conditions within a continually evolving volcanic system. Such processes are not temporally stationary nor statistically uniform. To evaluate the probability of a new M8 event at Aso, within the next 100 years, we performed a comprehensive stochastic probability uncertainty analysis using a model implemented with advanced computational Bayes Net (BN) software. Our eruption process model is informed by multiple strands of evidence from volcanology, petrology, geochemistry and geophysics, together with estimates of epistemic (knowledge) uncertainty, adduced from reviews of published data, modelling and from expert judgement elicitation. Several lines of evidence characterise the likely structure, magmatic composition and eruptive state of the present-day Aso volcano, which has had numerous smaller eruptions since Aso-4. To calculate the probability of another M8 eruption of Aso, we implemented probabilistic ‘Importance Sampling’ in our model. With this approach, we find the chance of an Aso-4 scale eruption (characterised by mean volume 500 km3 DRE and approximate 90
In the course of elementary linear algebra, it is a must to teach how to solve a system of linear equations with plural solutions, however, it is rarely taught how to analyze an overdetermined system of linear equations with no solution, which is often required in practical applications. In this paper, we discuss how to analyze an overdetermined system of linear equations with no solution, which is important from the viewpoint of both practical applications and mathematical education.
