Chenmin Ni

The upper bound estimate for the convergence rate of two-stage sampling distribution regression is investigated. The excess risk is decomposed as the two-stage sample error and the approximation error, the approximation error is bounded by a [ ]-functional. The two-stage sample error is bounded with a convex analysis method whose advantage lies separating the two-stage optimal solution and the one-stage optimal solution from the mean optimal solution. On this basis, the two-stage sample error is attributed to the decay of a modulus of smoothness whose convergence rate has been investigated in approximation theory. Finally, a kind of explicit capacity independent convergence rate for the excess risk is provided. The feature of the investigation lies that the usual regularity condition is replaced by a decay assumption related to the modulus of smoothness.

Flood disasters occur worldwide, and flood risk prediction is conducive to protecting human life and property safety. Influenced by topographic changes and rainfall, the water level fluctuates randomly and violently during the flood, introducing many noises and directly increasing the difficulty of flood prediction. A data-driven flood forecasting method is proposed based on data preprocessing and a two-layer BiLSTM-Attention network to improve forecast accuracy. First, the Variational Mode Decomposition (VMD) is used to decompose the data for reducing noise and produce suitable Intrinsic Mode Functions (IMFs); Then, an optimized two-layer attention-based Bidirectional Long Sshort-Term memory (BiLSTM-Attention) network is constructed to predict each IMF. Finally, two optimization algorithms are used to obtain the optimized parameters of VMD and BiLSTM intelligently, increasing the self-adaptability. The inertia factor of particle swarm optimization is improved and then used to optimize the five hyperparameters of BiLSTM. The proposed model reduces storage errors for smaller training sets and can achieve good performance. Three water level data sets from the Yangtze River in China are used for comparative experiments. Numerical results show that the peak height absolute error is within 2 cm, and the relative error of peak time arrival is within 30%. Compared with LSTM, BiLSTM, CNN-BiLSTM-attention, etc., the proposed model reduces the root mean square error by at least 50% and has advantages for high-risk forecasting when the water level exceeds the defense line and fluctuates prominently.

As climates change globally, water-related disasters increase, causing substantial economic losses and safety risks. During floods, river water levels show unpredictable fluctuations, introducing substantial noise that complicates accurate prediction. A hybrid model that uses eight-dimensional input data from hydrological and meteorological stations is proposed to address these challenges. Initially, the Variational Mode Decomposition preprocesses and denoises water level data, resulting in decomposed Intrinsic Mode Functions (IMFs). Then, the Pearson correlation coefficient between each IMF and input characteristics is computed, and the fluctuation factor for each IMF is defined. IMFs are categorized based on a threshold, leading to a hybrid prediction model. This model integrates convolutional neural networks (CNNs) for spatial information and bidirectional long short-term memory (BiLSTM) networks with an attention mechanism for learning from past and future data points. Comparative evaluations of mean absolute percentage error, root mean square error, mean absolute error, and goodness of fit (R2) show that the proposed model outperforms existing LSTM and CNN–BiLSTM frameworks, reducing RMSE by at least 20% and increasing R2 by approximately 10% on average. The model's practical significance lies in improving the accuracy and efficiency of meteorological forecasting and flood warning systems, contributing substantially to global disaster preparedness and response strategies.

GPS monitoring systems and the development of driverless vehicles are almost inseparable from camera images. The images taken by traffic cameras often contain certain sky areas and noise, the traditional dark channel prior (DCP) algorithm easily produces color distortion and halo effect, when processing the hazy traffic images with sky and high brightness areas. An optimized Retinex model and dark channel prior algorithm (ORDCP) is proposed in this paper. Firstly by adjusting the calculation method of dark channel image, the proportion of dark channel is improved; Then, the transmittance image is corrected and smoothed by guided filtering and mean filtering. Finally, the Retinex model is fused to save the details.ORDCP corrects the inaccurate calculation of scene transmittance value in DCP algorithm,and modifies some dehazing problems, such as the loss of details, halo effect, contrast and color distortion,etc. Using information entropy (IE) as the objective evaluation index, combined with the subjective evaluation, it is concluded that the algorithm proposed in this paper can effectively retain the detailed information of the image, and eliminate the halo effect. Meanwhile, it meets the visual characteristics of human eyes better, and has some practicality and applicability in traffic control and intelligent detection.

Xiamen Park Expo Garden, full name is Xiamen international expo garden, is located in Jimei Zhongzhou Island, Xinglin Bay Xiamen, the hometown of Mr. Chen Jiageng, the vast Xinglin Bay water area is the background. The planning area covers a total area of 10.82 square kilometers, including 5.55 square kilometers of land area and 5.27 square kilometers of water area. It is composed of 9 islands and 2 peninsulas. Since its construction in 2007, Xiamen Park Expo Garden has greatly promoted the development of tourism, ecological services and real estate in Jimei District of Xiamen City, and also greatly promoted the development of the surrounding economy. Using the method of ecological economics and mathematics analysis, such as carbon tax law, afforestation cost method, market value method, industrial oxygen production method, expense method, shadow engineering method, conditional value method and achievement reference method etc, some ecological services of Xiamen Park Expo Garden are valued, such as fixed carbon dioxide, release oxygen, air purification, water storage, tourism and leisure, education and scientific research, the real estate value. The total value is about 484 million, of which the value of tourism and leisure is the largest, it is 375.9766 million yuan, and occupies the proportion of 77.71%. By analyzing the total value of the marginal effect of main components, some suggestions are proposed for the construction and development of Xiamen Park Expo Garden.