Synthetic aperture radar (SAR) is portrayed as a multiple access channel. An information theory approach is applied to the SAR imaging system, and the information content about a target that can be extracted from its ...Synthetic aperture radar (SAR) is portrayed as a multiple access channel. An information theory approach is applied to the SAR imaging system, and the information content about a target that can be extracted from its radar image is evaluated by the average mutual information measure. A conditional (transition) probability density function (PDF) of the SAR imaging system is derived by analyzing the system and a closed form of the information content is found. It is shown that the information content obtained by the SAR imaging system from an independent sample of echoes will decrease and the total information content obtained by the SAR imaging system will increase with an increase in the number of looks. Because the total average mutual information is also used to define a measure of radiometric resolution for radar images, it is shown that the radiometric resolution of a radar image of terrain will be improved by spatial averaging. In addition, the imaging process and the data compression process for SAR are each treated as an independent generalized communication channel. The effects of data compression upon radiometric resolution for SAR are studied and some conclusions are obtained.展开更多
新词识别作为自然语言处理的基础任务之一,为构建中文词典、分析词语情感倾向等提供了支持。然而,目前的新词识别方法没有考虑针对谐音新词的识别,导致谐音新词识别的准确率不高。为了解决这一问题,提出一种基于拼音相似度的中文谐音新...新词识别作为自然语言处理的基础任务之一,为构建中文词典、分析词语情感倾向等提供了支持。然而,目前的新词识别方法没有考虑针对谐音新词的识别,导致谐音新词识别的准确率不高。为了解决这一问题,提出一种基于拼音相似度的中文谐音新词发现方法,引入新旧词拼音比较来提高谐音新词识别的准确率。首先,对文本进行预处理,计算平均互信息(AMI)以判定候选词的内部结合度,并使用改进邻接熵确定候选新词的边界;然后,将保留下的词转换成发音相近的汉语拼音与中文词典中的旧词拼音进行相似度比较,并保留最相似的比较结果;最后,若比较结果超过阈值,则将结果中的新词作为谐音新词,对应的旧词即为谐音新词的原有词。在自建的微博数据集上的实验结果表明,与BNshCNs(Blended Numeric and symbolic homophony Chinese Neologisms)、依存句法与语义信息结合的相似性计算模型(DSSCNN)相比,所提方法的准确率、召回率和F1分数分别提高了0.51和5.27个百分点、2.91和6.31个百分点以及1.75和5.81个百分点。可见所提方法具有更好的中文谐音新词识别效果。展开更多
This paper first describes a binary Low-Density Parity-Check(LDPC)-coded Probabilistic Shaping(PS)scheme for Multiple-Input Multiple-Output(MIMO)systems based on Signal Space Diversity(SSD).Second,a Nonbinary(NB)LDPC-...This paper first describes a binary Low-Density Parity-Check(LDPC)-coded Probabilistic Shaping(PS)scheme for Multiple-Input Multiple-Output(MIMO)systems based on Signal Space Diversity(SSD).Second,a Nonbinary(NB)LDPC-coded PS scheme for MIMO systems based on SSD is proposed.The first scheme can be used to obtain a shaping gain,whereas the second can also realize a coding gain.The theoretical average mutual information of the optimized rotated quadrature amplitude modulation constellations is analyzed and the simulated error per-formance with 22 and 44 MIMO schemes is investigated.The theoretical average mutual information analysis and simulation results show that the proposed NB LDPC-coded PS scheme for MIMO systems based on SSD is reliable and robust,and is therefore suitable for future wireless communication systems.展开更多
文摘Synthetic aperture radar (SAR) is portrayed as a multiple access channel. An information theory approach is applied to the SAR imaging system, and the information content about a target that can be extracted from its radar image is evaluated by the average mutual information measure. A conditional (transition) probability density function (PDF) of the SAR imaging system is derived by analyzing the system and a closed form of the information content is found. It is shown that the information content obtained by the SAR imaging system from an independent sample of echoes will decrease and the total information content obtained by the SAR imaging system will increase with an increase in the number of looks. Because the total average mutual information is also used to define a measure of radiometric resolution for radar images, it is shown that the radiometric resolution of a radar image of terrain will be improved by spatial averaging. In addition, the imaging process and the data compression process for SAR are each treated as an independent generalized communication channel. The effects of data compression upon radiometric resolution for SAR are studied and some conclusions are obtained.
文摘新词识别作为自然语言处理的基础任务之一,为构建中文词典、分析词语情感倾向等提供了支持。然而,目前的新词识别方法没有考虑针对谐音新词的识别,导致谐音新词识别的准确率不高。为了解决这一问题,提出一种基于拼音相似度的中文谐音新词发现方法,引入新旧词拼音比较来提高谐音新词识别的准确率。首先,对文本进行预处理,计算平均互信息(AMI)以判定候选词的内部结合度,并使用改进邻接熵确定候选新词的边界;然后,将保留下的词转换成发音相近的汉语拼音与中文词典中的旧词拼音进行相似度比较,并保留最相似的比较结果;最后,若比较结果超过阈值,则将结果中的新词作为谐音新词,对应的旧词即为谐音新词的原有词。在自建的微博数据集上的实验结果表明,与BNshCNs(Blended Numeric and symbolic homophony Chinese Neologisms)、依存句法与语义信息结合的相似性计算模型(DSSCNN)相比,所提方法的准确率、召回率和F1分数分别提高了0.51和5.27个百分点、2.91和6.31个百分点以及1.75和5.81个百分点。可见所提方法具有更好的中文谐音新词识别效果。
基金supported by Fundamental Research Program of Shanxi Province(202203021212159).
文摘This paper first describes a binary Low-Density Parity-Check(LDPC)-coded Probabilistic Shaping(PS)scheme for Multiple-Input Multiple-Output(MIMO)systems based on Signal Space Diversity(SSD).Second,a Nonbinary(NB)LDPC-coded PS scheme for MIMO systems based on SSD is proposed.The first scheme can be used to obtain a shaping gain,whereas the second can also realize a coding gain.The theoretical average mutual information of the optimized rotated quadrature amplitude modulation constellations is analyzed and the simulated error per-formance with 22 and 44 MIMO schemes is investigated.The theoretical average mutual information analysis and simulation results show that the proposed NB LDPC-coded PS scheme for MIMO systems based on SSD is reliable and robust,and is therefore suitable for future wireless communication systems.
