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2023年农业干旱风险预警服务质量评估
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作者 姜蓝齐 吕佳佳 +2 位作者 闫平 曲辉辉 庞云超 《黑龙江气象》 2024年第4期29-33,共5页
本文对2023年发布的农业干旱风险预警服务产品进行质量评估,以期为农业气象灾害预警体系的完善提供科学依据。通过对预警产品及时性、准确率和服务质量进行综合评估,揭示了当前农业干旱风险预警技术的问题与挑战。研究结果表明,目前预... 本文对2023年发布的农业干旱风险预警服务产品进行质量评估,以期为农业气象灾害预警体系的完善提供科学依据。通过对预警产品及时性、准确率和服务质量进行综合评估,揭示了当前农业干旱风险预警技术的问题与挑战。研究结果表明,目前预警技术在玉米干旱风险预警方面表现较好,准确率为87%,在大豆干旱风险预警方面存在不足;干旱风险预警产品服务及时性尚可,但整体预报时效性较短;此外,预警技术的精细化水平、预报准确率和覆盖面等方面亟待提升,需进一步提升农业干旱风险预警服务产品质量,建议加大科研投入,优化预警模型,提高数据采集密度,并延长预报时效,以更好地服务于农业生产。 展开更多
关键词 农业干旱 风险预警 质量评估 黑龙江
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An Algorithm of Voice Activity Detection Based on EMD and Wavelet Entropy Ratio
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作者 Xiao-Bing Zhang Ting-Ting Sun yan-ping 《Journal of Electronic Science and Technology》 CAS CSCD 2017年第1期64-68,共5页
A new method was proposed to identify speech-segment endpoints based on the empirical mode decomposition(EMD) and a new wavelet entropy ratio with improving the accuracy of voice activity detection.With the EMD, the... A new method was proposed to identify speech-segment endpoints based on the empirical mode decomposition(EMD) and a new wavelet entropy ratio with improving the accuracy of voice activity detection.With the EMD, the noise signals can be decomposed into several intrinsic mode functions(IMFs). Then the proposed wavelet energy entropy ratio can be used to extract the desired feature for each IMFs component. In view of the question that the method of voice endpoint detection based on the original wavelet entropy ratio cannot adapt to the low signal-to-noise ratio(SNR)condition, an appropriate positive constant was introduced to the basic wavelet energy entropy ratio with effectively improved discriminability between the speech and noise. After comparing the traditional wavelet energy entropy ratio with the proposed wavelet energy entropy ratio, the experiment results show that the proposed method is simple and fast. The speech endpoints can be accurately detected in low SNR environments. 展开更多
关键词 wavelet entropy decomposed Wavelet adapt environments Voice noisy empirical desired
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