An operator T is said to satisfy a-Browder's theorem if σ_a(T)\σ_ea(T)???π₀₀^a(T), where σ_a(T) and σ_ea(T) denote the approximate point spectrum and the essential approximate point spectrum, respectively, and π₀₀^a(T)={λ∈isoσ_a(T),0< dimN(T-λI)<∞}. If σ_a(T)\σ_ea(T)=π₀₀^a(T), we say that T satisfies a-Weyl's theorem. In this note, by using the characteristics of semi-Fredholm domain of the diagonal of the upper triangular operator matrix, we investigate the stability of a-Browder's theorem and a-Weyl's theorem for the upper triangular operator matrices under compact perturbations.

We develop a novel data assimilation approach for the prediction of algal blooms in Lake Taihu. Our approach is based on a 2D ecological model which combines a physical model, 250 m MODIS inversion chlorophyll-a data, and an ensemble Kalman filter (EnKF) analysis scheme. Our results indicate that the data assimilation approach is reliable for predicting algal blooms in these complex waters.

In this work, Wuhu City in China was selected as the studied area. NDWI, MNDWI, LBV_B, KT₃+TM₄>TM₂+TM₇, and a new model KT₃+TM₂>TM₄+TM₃ were used to extract water body information based on Landsat TM data. Qualitative and quantitative comparisons were made. The results show that the new water information extraction model, KT₃+TM₂>TM₄+TM₃, is the most accurate(with a total accuracy of 93%), and its accuracy is less affected by vegetation and buildings.

Narrowband interference (NBI) may lead to failure of the time-domain cross-correlation (TDCC) weak signal detection approach since NBI is mistakenly detected as the desired signal. In order to solve this problem, a detection approach based on frequency-domain cross-correlation (FDCC) is proposed. The entire spectrum band is divided into multiple sub-bands, and the corresponding statistical characteristic of each sub-band is derived. Then according to the criterion of one-sided test, a one-bit decision is made in each sub-band. Finally, the decisions of all the sub-bands are processed jointly via the n-out-of-m fusion rule to make the final decision. Simulation results show that the proposed approach is promising for suppressing NBI and it distinctively outperforms the TDCC detection approach.

A 50-day anaerobic digestion test is conducted by mixing raw pig manure with maize straw at dry matter mass ratios of 1:1 and 2:1 at the temperature of (35±1) ℃. The fractions of Cu and Zn of the co-digestion fermentation materials and the biogas residues are measured by modified BCR extraction and 0.01 mol·L^-1 CaCl₂ extraction processes, respectively. The results showed that the concentrations of leachable fraction and the percentages of bioavailability (sum percentages of exchangeable and reducible fractions) of Cu and Zn all decreased in biogas residues, and the stability (sum percentages of oxidizable and residual fractions) of Cu and Zn all increased in biogas residues during anaerobic co-digestion.