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As advanced scenarios are developed for tokamak operations, the demand for flexibility of the electron cyclotron emission (ECE) channels’ locations has increased. The tunable feature of yttrium iron garnet (YIG) filters provides this spatial flexibility. Here, we present a method of performing ECE measurements on fixed flux surfaces instead of fixed frequencies. This is achieved by adjusting YIG filters utilized in the intermediate frequency section to frequencies associated with flux surfaces in regions of interest during the discharge. The key components are the application of tunable YIG filters and a control program that calculates the filter settings using flux information from real-time reconstruction equilibria (EFIT). This fast procedure facilitates Te measurements in regions of interest to investigate plasma dynamic behaviors.

Evidence from terrestrial sedimentary heavy metals record is a robust indicator of anthropogenic activity changes. Heavy metals and particle sizes in 210Pb-dated sediment cores extracted from Hulun and Chagan lakes were measured to reconstruct the sediment record and evaluated health risk of heavy metals in the last 150 years in Northeast China. In general, the particle size of Hulun Lake was finer with more contents of clay than Chagan Lake, while the concentrations of most heavy metals in Hulun Lake was lower. Prior to the 1970s, significant positive correlations between most heavy metals and clay, indicating that that they were likely co-transported and both lakes were dominated by natural inputs. The two records showed significant increases in concentrations of heavy metals between 1970s and 1990s, which were associated with recent anthropogenic activities derived from principal component analysis of clay and heavy metals. Specifically, the exploitation of mineral resources and traffic source in the Hulun Lake, and the emissions of pesticides and fertilizers from agricultural activity, and the combustions of coal and fossil fuels from industrial activity in the Chagan Lake. Since 1990s, natural processes was the main source of heavy metals in Hulun Lake due to the environmental protection policy, while emissions of industrial, agricultural and domestic sewage were still the main source in Chagan Lake. Overall carcinogenic risks caused by single heavy metal elements determined for the two lakes were considered to be acceptable. However, Cr was associated with a risk for children across since 1970s which should be paid more attention.

Utilizing variable-frequency channels, e.g., yttrium iron garnet (YIG) bandpass filters, in the intermediate frequency (IF) section of an electron cyclotron emission (ECE) radiometer facilitates flexibility in the volume viewed by the ECE channels as well as high resolution electron temperature and temperature fluctuation measurements in tokamaks. Fast modulating electron cyclotron emission (FMECE), a stand-alone IF section with eight channels, is a novel application of YIG filters for real-time electron temperature gradient and gradient scale length measurements. Key to FMECE is a simultaneous input/output data acquisition unit, as well as a modified type of YIG filters, which is capable of fast switching of their center (set) frequencies with a frequency slew rate of 600 µs/GHz. A new FMECE has been implemented and tested on the DIII-D tokamak, demonstrating its capability in real-time gradient measurements. The data presented here shows that FMECE can identify flattening in the electron temperature profile; the latter can be used as a sensor for real time monitoring and control of plasma instabilities. Implementation and application are planned for the EAST tokamak.

The color histogram of an image has been widely used as a feature descriptor for the image in content-based retrieval applications. In this paper, we report some results from our investigation efforts into its usage. We outline three typical color space quantization schemes used in our experiments, and introduce the soft-decision histogramming method to eliminate the discontinuity problem in traditional color histogram population process. Then, to improve the effectiveness of color histogram-based retrieval algorithms, several similarity metrics are proposed for comparing color histograms, including three special forms of the Kantorovich metric.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.