Three fiber micro displacement sensors can be combined to realize three-dimensional (3D) displacement sensing, but the system is complex. In this paper, a 3D displacement sensor based on fiber SPR was proposed, which was composed of displacement fiber and sensing fiber. By cascading the eccentric dual-core fiber and graded multimode fiber, the displacement fiber was realized. The V-groove was processed in the vertical and horizontal directions of the graded multimode fiber, and the inclined SPR sensing areas were fabricated to realize the sensing fiber. A straight beam from the middle core of the displacement fiber contacted the vertical V-groove inclined plane of the sensing fiber to realize the Y axis (up and down) direction micro displacement, contacted the horizontal V-groove inclined plane of the sensing fiber to realize the Z axis (front and back) direction micro displacement sensing. An oblique beam from the eccentric core of the displacement fiber cooperated with the sensing fiber to realize the micro displacement sensing in the X-axis (left and right) direction. The testing results indicate that the fiber SPR 3D micro displacement sensor can sense micro displacement in the X axis, Y axis and Z axis, and the wavelength sensitivity is 0.148 nm/µm, -3.724 nm/µm and 3.543 nm/µm, respectively. The light intensity sensitivity is -0.0014a.u./µm, -0.0458a.u./µm and -0.0494a.u./µm, respectively. When adjusting the parameters of eccentric dual-core fiber, the larger the core distance is, the greater the displacement sensitivity in the X-axis direction of the sensor is, and the smaller the detection range is. The proposed sensor can realize 3D micro displacement sensing by itself, which is expected to be used in the field of 3D micro displacement measurement and 3D space precision positioning.
Understanding the complex relationships among ecosystem services (ESs) is a prerequisite for optimized management and is of great significance to China's current implementation of an eco-civilization. However, it is always difficult to simultaneously reveal the relationships among multiple ESs from a local perspective. We proposed an assessment framework that can quantify and conveniently display the intensities of relationships (tradeoffs, synergies, and losses) among multiple ESs, permitting the spatial heterogeneity and gradient effects of these relationships to be revealed. Using township as the study unit, a case study was conducted and nine ESs were evaluated in a transitional area, the Beijing Bay Area (BBA), where the conflict between conservation and development has been prominent. The results suggested that nine ESs were clumped and showed either a high-low (ecosystem-dominated ESs) or a low-high (human-dominated ESs) spatial pattern from northwest to southeast in the BBA. In addition, the relationships among multiple ESs showed significant spatial heterogeneity across townships. In general, tradeoff intensity was mainly related to the supply of human-dominated ESs (especially food supply or water quality regulation), and synergy intensity and loss intensity were mainly related to the supply of ecosystem-dominated ESs. Moreover, all relationships among multiple ESs showed gradient effects along influencing factors. The tradeoff intensity largely exhibited V-shaped patterns, first decreasing and then increasing. Synergy intensity and loss intensity were mainly characterized by monotonically increasing or decreasing patterns. Overall, we found that the process of formation of ESs and their dominating factors largely determined their spatial patterns, spatial heterogeneity, and the gradient effects along influencing factors within the BBA. Based on these results, we propose optimized management suggestions for different townships, combining new plans for development of the BBA. The results of our study will provide information for policy makers to alleviate conflict between conservation and development and will promote sustainable development in the area.
In this paper, a fiber Mach Zehnder (MZ) interferometer based on sawtooth structure was proposed. It not only has the ability of bending sensing and bending direction recognition, but also can be applied to multi parameter sensing. Here we established the fiber hetero core structure with single mode fiber-multimode fiber-single mode fiber (MSM), and then fabricated the sawtooth structure on the single mode fiber in the middle by CO 2 laser. Since part of the cladding on the single-mode fiber was removed, the fiber core was no longer at the neutral plane. When the sensor is bent in the 0° direction or 180° direction, the effective refractive index and optical path length of the core mode will increase or decrease, resulting in the increase or decrease of the optical path difference between the core mode and the cladding mode. And then the interference wavelength will show a red shift or blue shift, so as to realize the curvature sensing with bending direction recognition. Meanwhile, due to the local stress of the sawtooth structure in the bending, the sensitivity of the bending sensor is improved. The testing results indicate that the sensitivity of 0° bending and 180° bending are −15.16 nm/m −1 and 8.32 nm/m −1 with the curvature range of 0–1 m −1 . Moreover, the sawtooth structure sensor has excellent performance in strain, temperature and torsion sensing. The torsional sensitivity of the sensor reaches −0.30 nm/(rad/m) with torsional range of 0–13.96 rad/m, the temperature sensitivity reaches 58.90 pm/°C, and the strain sensitivity reaches −3.62 pm/μϵ. In strain sensing, there are some interference valleys insensitive to strain, which can realize the simultaneous measurement of other parameters and strain.
Abstract Spatholobus suberectus Dunn as a traditional Chinese herbal medicine, which is susceptible to being infected by molds during storage. In order to explore the diversity characteristics of fungal community and the quality evaluation of Spatholobus suberectus Dunn during the process of mildew. The study used high-throughput sequencing technology to detect the diversity characteristics of fungal community, high-performance liquid chromatography (HPLC) and ultraviolet spectrophotometry (UV-spectrophotometry) methods to detect the content of flavonoids, and enzyme-linked immunosorbent assay (ELISA) method to detect the content of Aflatoxins B 1 (AFB 1 ). The result showed that the fungi of Spatholobus suberectus Dunn samples during the process of mildew belonged to 14 phyla, 43 classes, 92 orders, 189 families, 336 genera, 432 fungal taxa. The species diversity of fungal community was the highest at the early stage of mildew, and the species richness of fungal community was the highest at the late stage of mildew. At the genus level, the dominant fungus at the early stage of mildew was not obvious, while the dominant fungus of samples at middle and late stages of mildew was Aspergillus . The content of AFB 1 showed an upward trend and the content of flavonoids showed a downward trend during the process of mildew. In brief, the diversity of fungal community decreased gradually, the number of dominant flavus increased gradually, and the quality of Spatholobus suberectus decreased gradually during the process of mildew.
Stand structure and topography are important factors affecting forest vegetation carbon density (FVCD). Revealing the interaction mechanisms between stand structure and topography on FVCD is of great significance for enhancing forest vegetation carbon storage and achieving regional carbon neutrality. Based on stratified sampling, systematic distribution and forest continuous inventory sample plots in Jiangxi province, the variation characteristics of FVCD and its correlations with stand structure and topographic factors were studied. The results are as follows: (1) The average FVCD in Jiangxi province was 44.23 Mg/ha, which was dominated by the carbon density of the arbor layer, accounting for about 81.39% of the total forest—far lower than the average level of global FVCD, which proved that the forest in Jiangxi province was dominated by middle-age and young forests with low carbon density, and also showed that the potential for forest vegetation carbon storage in Jiangxi province was huge. (2) Except for vegetation carbon densities of shrub and herb layers, the vegetation carbon densities of other forest layers in Jiangxi province were significantly different among different forest types. Volume per unit area was the most important factor affecting the vegetation carbon densities of arbor and total forest, and vegetation carbon density–volume models of the main forests were built for vegetation carbon density calculation in Jiangxi province. (3) The vegetation carbon densities of arbor layer, snag and log layer, and total forest increased significantly with increases in elevation and slope. Except for the shrub layer and herb layer, the vegetation carbon densities of the other layers and the total forest had extremely significant or significant differences between slope position gradients—indicating that the effect of topography on FVCD in Jiangxi province was significant, mainly through influencing of forest distribution and human disturbance intensity.
The fact that ecosystem services have values that can be quantified has been widely accepted in recent years. Part of the economic values of ecosystem services have been realized partly by ecological compensation of fiscal transfer payments at different levels, trade and consumption of leisure tourism and ecological products, and carbon sequestration forest funds sponsored by non-governmental capital. However, it remains difficult to realize the economic value of ecosystem services as industrial products and support the coordinated and sustainable development of nature, economy and society. To reveal the role of ecological compensation, consumption of biological products, leisure tourism and ecosystem services trading in realizing the economic values of ecosystem services, we analyzed the composition, transfer and consumption pattern of ecosystem services. In order to provide theoretical and technological support for inter-regional ecological compensation, ecosystem service industry development and ecosystem services trade, the concept of ecosystem services credit and key problems with ecosystem services trading are proposed.
We proposed and demonstrated a novel optically tuned SPR sensor. A carbon disulfide (CS2) film was coated on the sensing gold film as modulation layer. By controlling light, the refractive index of the modulation layer was adjusted continuously. The simulating results indicated that the larger the power intensity of the controlling light was, the larger the sensing sensitivity was. And the dynamic range of the SPR resonance spectrum moved to long wavelength with the increased of the irradiance. The proposed optically tuned SPR sensor provided a new idea for the design of the distributed SPR sensor.
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