The vulnerability of ecological environment threatens social and economic development. Recent studies failed to reveal the driving mechanism behind it, and there is little analysis on the spatial clustering characteristics of the vulnerability of urban agglomerations. Therefore, this article estimates ecological environment vulnerability in 2005, 2011, and 2017, determines Moran Index (MI) with spatial autocorrelation model, analyzes the spatial-temporal difference characteristics of ecological environment vulnerability of Yangtze River Urban Agglomeration and the spatial aggregation effect, and discusses its driving factors. The study results estimate that the overall vulnerability index of the Yangtze River Urban Agglomeration is in a mild fragile state. However, most fragile and slightly fragile cities are developing in the direction of moderate to severe vulnerability. The spatial agglomeration effect of the ecological environment vulnerability of the Yangtze River Urban Agglomeration is not obvious, and the effect of mutual ecological environment influence among cities is not obvious. Moreover, the driving factors of ecological environment vulnerability of Yangtze River city group changed from natural factors to social economic factors and then to policy factors. It is necessary to develop an ecological economy, coordinate the spatial agglomeration of urban agglomerations, and make balance the internal differences of urban agglomerations.
We present a low-area implementation of an I/Q mismatch compensation (IQMC) circuit that comprises a correction engine and an adaptation engine. The correction engine performs I/Q mismatch compensation in the data path using a filter whose coefficients are updated after a programmable amount of time by a parallel adaptation engine that performs sample-by-sample off-line adaptation. This scheme allows very fast online adaptation while protecting the receiver data path from the degradations caused by a fast converging algorithm. The proposed scheme has been successfully implemented in 90-nm digital CMOS process for a low-IF quad-band GSM transceiver SoC. A single multiplier is used to perform complex multiplications for both correction and adaptation engines, resulting in a 0.025 mm 2 circuit. Image Rejection Ratio in excess of 50 dB is measured that is sufficient for IF frequencies as high as 200 kHz for GSM application.
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