Visible light communication(VLC) shows great potential in Internet of Vehicle applications. A single-input multi-output VLC system for Vehicle to Everything is proposed and demonstrated. A commercial car headlight is ...Visible light communication(VLC) shows great potential in Internet of Vehicle applications. A single-input multi-output VLC system for Vehicle to Everything is proposed and demonstrated. A commercial car headlight is used as transmitter. With a self-designed 2 × 2 positive-intrinsic-negative(PIN) array, four independent signals are received and equalized by deep-neural-network post-equalizers, respectively. Maximum-ratio combining brings high signal-to-noise ratio and data rate gain. The transmission data rate reaches 1.25 Gb/s at 1 m and exceeds 1 Gb/s at 4 m. To the best of our knowledge, it is the first-time demonstration of beyond 1 Gb/s employing a commercial car headlight.展开更多
相对密实度是影响砂土力学性质的重要指标,密实的砂土呈现强度软化,松散的砂土却呈现强度硬化,而测定最大、最小孔隙比是计算相对密实度的前提。砂土的最小及最大孔隙比是通过直接测定的相应最大、最小干密度换算得到的,但目前常忽略了...相对密实度是影响砂土力学性质的重要指标,密实的砂土呈现强度软化,松散的砂土却呈现强度硬化,而测定最大、最小孔隙比是计算相对密实度的前提。砂土的最小及最大孔隙比是通过直接测定的相应最大、最小干密度换算得到的,但目前常忽略了试验方法对其试验结果的影响,也忽略了黏粒含量对砂样密实度的影响。现取细、中、粗砂3种砂样,进行了干密度测试试验并测定了不同黏粒及黏粒掺量下砂样的最大、最小孔隙比。研究结果表明：采用量筒慢转法测量砂土最小干密度较为合理;采用振动锤击法测定砂土最大干密度时,建议细砂采用容积为250 m L击实筒,中、粗砂采用1000 m L击实筒;掺入粉粒、黏粒后砂样的最小孔隙比均随黏粒掺量（≤30%）增加而减小,且两者之间存在一定的线性关系;砂样最大孔隙比随粉粒、黏粒掺量增加逐渐减小,而随高岭土黏粒掺量增加呈缓慢增大趋势。展开更多
为了提高基于拍摄方式的文档图像的二值化效果,降低光学字符识别(optical character recognition,OCR)系统的文字识别错误率,提出了一种全局阈值与局部阈值相结合的二值化算法——VFCM。该算法使用最大方差比方法产生全局阈值,使用FCM(F...为了提高基于拍摄方式的文档图像的二值化效果,降低光学字符识别(optical character recognition,OCR)系统的文字识别错误率,提出了一种全局阈值与局部阈值相结合的二值化算法——VFCM。该算法使用最大方差比方法产生全局阈值,使用FCM(FuzzyC-Means)聚类方法产生局部阈值。这两种方法的结合能够较好地保留字符的笔画细节,并能有效地消除伪影。实验结果表明,该算法可以取得比较好的二值化效果,并能带来OCR系统识别率的有效提高。展开更多
基金partially supported by the National Key Research and Development Program of China(No. 2017YFB0403603)the National Natural Science Foundation of China (NSFC)(No. 61925104)the Visible Light Communication Technology Development Project by Huawei Company (No. YBN2019085097)。
文摘Visible light communication(VLC) shows great potential in Internet of Vehicle applications. A single-input multi-output VLC system for Vehicle to Everything is proposed and demonstrated. A commercial car headlight is used as transmitter. With a self-designed 2 × 2 positive-intrinsic-negative(PIN) array, four independent signals are received and equalized by deep-neural-network post-equalizers, respectively. Maximum-ratio combining brings high signal-to-noise ratio and data rate gain. The transmission data rate reaches 1.25 Gb/s at 1 m and exceeds 1 Gb/s at 4 m. To the best of our knowledge, it is the first-time demonstration of beyond 1 Gb/s employing a commercial car headlight.
文摘相对密实度是影响砂土力学性质的重要指标,密实的砂土呈现强度软化,松散的砂土却呈现强度硬化,而测定最大、最小孔隙比是计算相对密实度的前提。砂土的最小及最大孔隙比是通过直接测定的相应最大、最小干密度换算得到的,但目前常忽略了试验方法对其试验结果的影响,也忽略了黏粒含量对砂样密实度的影响。现取细、中、粗砂3种砂样,进行了干密度测试试验并测定了不同黏粒及黏粒掺量下砂样的最大、最小孔隙比。研究结果表明：采用量筒慢转法测量砂土最小干密度较为合理;采用振动锤击法测定砂土最大干密度时,建议细砂采用容积为250 m L击实筒,中、粗砂采用1000 m L击实筒;掺入粉粒、黏粒后砂样的最小孔隙比均随黏粒掺量（≤30%）增加而减小,且两者之间存在一定的线性关系;砂样最大孔隙比随粉粒、黏粒掺量增加逐渐减小,而随高岭土黏粒掺量增加呈缓慢增大趋势。
文摘为了提高基于拍摄方式的文档图像的二值化效果,降低光学字符识别(optical character recognition,OCR)系统的文字识别错误率,提出了一种全局阈值与局部阈值相结合的二值化算法——VFCM。该算法使用最大方差比方法产生全局阈值,使用FCM(FuzzyC-Means)聚类方法产生局部阈值。这两种方法的结合能够较好地保留字符的笔画细节,并能有效地消除伪影。实验结果表明,该算法可以取得比较好的二值化效果,并能带来OCR系统识别率的有效提高。
