Sleep apnea affects quality of life and health seriously. PolySomnoGraphy (PSG) is the “gold standard” for diagnosis of sleep apnea, but it is expensive and inconvenient for long-term monitoring. Based on the above, a new method based on universal smart wristband was proposed to detect sleep apnea conveniently. In the method, by analyzing heart rate, blood oxygen saturation, and sleep state data collected by the wristband, an adaptive physiological data reconstruction method and a data interpolation method were used to achieve noise filtering; in feature engineering, continuous physiological variables and categorical variables were fused to extract sleep state features deeply; in the classification module, a lightweight Gated Recurrent Unit (GRU) model was used to simplify the training process and reduce the risk of overfitting. Experimental results show that the proposed method obtains 93.68% accuracy and 93.97% recall on a 23-person dataset. Correlation analysis shows that blood oxygen saturation, body mass index, and age are confirmed as key features for sleep apnea detection. Compared with PSG, the proposed method is more suitable for long-term monitoring in a home environment.
To solve the problem that the current graph summarization methods have high compression ratios and the graph compression algorithms cannot be directly used in downstream tasks, a fusion algorithm of graph summarization and graph compression was proposed, which called Graph Summarization algorithm based on Node Similarity grouping and graph Compression (GSNSC). Firstly, the nodes were initialized as super nodes, and the super nodes were grouped according to the similarity. Secondly, the super nodes of each group were merged until the specified number of times or nodes were reached. Thirdly, super edges and corrected edges were added between the super nodes for reconstructing the original graph. Finally, for the graph compression part, the cost of compressing and summarizing the adjacent edges of each super node were judged, and the less expensive one in these two was selected to execute. Experiments of graph compression ratio and graph query were conducted on six datasets such as Web-NotreDame, Web-Google and Web-Berkstan. Experimental results on six datasets show that, the proposed algorithm has the compression ratio reduced by at least 23 percentage points compared with SLUGGER (Scalable Lossless sUmmarization of Graphs with HiERarchy) algorithm, and the compression ratio decreased by at least 13 percentage points compared with SWeG (Summarization of Web-scale Graphs) algorithm. Experimental results on Web-NotreDame dataset show that the degree error of the proposed algorithm is reduced by 41.6% compared with that of SWeG algorithm. The above verifies that the proposed algorithm has better graph compression ratio and graph query accuracy.
Loop program has a significant amount of execution time in digital signal processing software, temporary storage of loop code with instruction buffer can reduce the number of program memory access to improve the performance of processor. A loop instruction buffer was added in the instruction pipeline. It could store and dispatch instructions of loop program in the software pipelining manner. The instructions of loop program needed to be accessed from program memory only once but executed many times, so the number of memory access was reduced. During the loop instructions were dispatched from buffer, the program memory could be signaled to sleep to reduce the power consumption of processor. In the typical application program, the instruction pipeline can be idle above 90%, and the performance of processor is improved about 10%, the overhead of loop buffer is 9% of the instruction pipeline.