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1. chinaXiv:202008.00091 [pdf]

Better Than Reference In Low Light Image Enhancement Conditional Re-Enhancement Networks.pdf

张雨; 遆晓光; 张斌; 季锐航; 王春晖
Subjects: Computer Science >> Computer Application Technology

Low light images suffer from severe noise, low brightness, low contrast, etc. In previous researches, many image enhancement methods have been proposed, but few methods can deal with these problems simultaneously. In this paper, to solve these problems simultaneously, we propose a low light image enhancement method that can combined with supervised learning and previous HSV (Hue, Saturation, Value) or Retinex model based image enhancement methods. First, we analyse the relationship between the HSV color space and the Retinex theory, and show that the V channel (V channel in HSV color space, equals the maximum channel in RGB color space) of the enhanced image can well represent the contrast and brightness enhancement process. Then, a data-driven conditional re-enhancement network (denoted as CRENet) is proposed. The network takes low light images as input and the enhanced V channel as condition, then it can re-enhance the contrast and brightness of the low light image and at the same time reduce noise and color distortion. It should be noted that during the training process, any paired images with different exposure time can be used for training, and there is no need to carefully select the supervised images which will save a lot. In addition, it takes less than 20 ms to process a color image with the resolution 400*600 on a 2080Ti GPU. Finally, some comparative experiments are implemented to prove the effectiveness of the method. The results show that the method proposed in this paper can significantly improve the quality of the enhanced image, and by combining with other image contrast enhancement methods, the final enhancement result can even be better than the reference image in contrast and brightness. (Code will be available at https://github.com/hitzhangyu/image-enhancement-with-denoise)

submitted time 2020-08-26 Hits1403Downloads136 Comment 0

2. chinaXiv:202006.00174 [pdf]

基于ERP的预测性句子加工研究前沿

岳金星; 卜玉伟; 李佳音
Subjects: Psychology >> Physiological Psychology

本文梳理了国际期刊发表的使用事件相关电位(ERP)技术研究人脑开展预测性句子加工所取得的主要成果和重要突破。本文从心理语言学对句子预测的研究逻辑为切入点,接着分别回顾通过N400和前侧正波(frontal positivity)两个ERP效应揭示词形预测和语义预测这两个预测性句子加工主要操作的研究里程碑,并进而总结勾勒出预测性句子加工理论模型。最后,本文指出了现有研究的局限性和未来该课题潜在的方向。

submitted time 2020-06-19 Hits7564Downloads542 Comment 0

3. chinaXiv:202004.00026 [pdf]

Learning an Adaptive Model for Extreme Low-light Raw Image Processing

付清旭; 遆晓光; 张雨1
Subjects: Computer Science >> Computer Application Technology

Low-light images suffer from severe noise and low illumination. Current deep learning models that are trained with real-world images have excellent noise reduction, but a ratio parameter must be chosen manually to complete the enhancement pipeline. In this work, we propose an adaptive low-light raw image enhancement network to avoid parameter-handcrafting and to improve image quality. The proposed method can be divided into two sub-models: Brightness Prediction (BP) and Exposure Shifting (ES). The former is designed to control the brightness of the resulting image by estimating a guideline exposure time t 1 . The latter learns to approximate an exposure-shifting operator ES, converting a low-light image with real exposure time t 0 to a noise-free image with guideline exposure time t 1 . Additionally, structural similarity (SSIM) loss and Image Enhancement Vector (IEV) are introduced to promote image quality, and a new Campus Image Dataset (CID) is proposed to overcome the limitations of the existing datasets and to supervise the training of the proposed model. In quantitative tests, it is shown that the proposed method has the lowest Noise Level Estimation (NLE) score compared with BM3D-based low-light algorithms, suggesting a superior denoising performance. Furthermore, those tests illustrate that the proposed method is able to adaptively control the global image brightness according to the content of the image scene. Lastly, the potential application in video processing is briefly discussed.

submitted time 2020-04-14 Hits8874Downloads612 Comment 0

4. chinaXiv:202003.00048 [pdf]

自监督图像增强网络:仅需低照度图像进行训练

张雨; 遆晓光; 张斌; 王春晖
Subjects: Computer Science >> Other Disciplines of Computer Science

本文提出了一种基于深度学习的自监督低照度图像增强方法。受信息熵理论和Retinex模型的启发,我们提出了一种基于信息熵最大的Retinex模型。利用该模型,一个非常简单的网络可以将照度图和反射图分离开来,且仅用低照度图像就可以进行训练。为了实现自监督学习,我们在模型中引入了一个约束条件:反射图的最大值通道与低照度图像的最大值通道一致,且其熵最大。我们的模型非常简单,不依赖任何精心设计的数据集(即使是一张低照度图像也能完成网络的训练),网络仅需进行分钟级的训练即可实现图像增强。实验证明,该方法在处理速度和效果上均达到了当前最新水平。

submitted time 2020-03-06 Hits16878Downloads774 Comment 1

5. chinaXiv:202002.00009 [pdf]

一种新型冠状病毒肺炎(COVID-19)药物与天然产物快速发现的计算药理学方法

全源; 梁峰吉; 熊江辉
Subjects: Biology >> Virology

新发传染病爆发流行期间,亟需提出候选药物功效与机制的科学假说。疫苗或新药研发均需要一定时间,因而药物重定位(老药新用)策略有其独特价值。但是新发疾病其病原体、宿主反应的临床数据不充分,制约了候选药物假设的提出。此阶段常根据病人临床特征进行广谱抗病毒药物的尝试。本文借鉴人工智能领域常见的启发式搜索思路,提出一种新方法(aCODE),基于前期有一定疗效提示的广谱抗病毒药,获得其宿主靶蛋白集合,在全基因组尺度上搜索与之相关性最高的基因模块组合,进而对候选化合物(如已批准上市药物、天然产物)进行模式匹配与统计检验排序。本方法可根据临床实践的进展更新输入药物,迭代输出更精准结果,输出的天然产物或中药、药食同源成分结合其它信息后可实施快速测试,形成敏捷研发测试闭环。本方法的第二版更新及其与文献证据的比对分析请参考:http://chinaxiv.org/abs/202002.00024。

submitted time 2020-02-21 Hits25494Downloads2254 Comment 0

6. chinaXiv:202002.00024 [pdf]

新冠肺炎(COVID-19)中药天然产物计算筛选与文献证据集成分析

高敏; 朱月星; 熊江辉
Subjects: Medicine, Pharmacy >> Other Disciplines of Medicine and Pharmacology

药物重定位(老药新用)策略在新发传染病中具有独特应用前景。我们前期提出了一种新的药物重定位系统——aCODE,可以基于疾病流行早期有限信息对潜在有效的天然产物进行预测。本文基于计算工具与文献证据,对可能在新冠病毒肺炎(COVID-19)防治中发挥作用的中药天然产物进行理论研究,发现:(1)文献调研共发现56种经过实验验证具有抗冠状病毒活性的天然产物成分,可靶向冠状病毒的结构蛋白和非结构蛋白;(2)将aCODE系统所预测的抗冠状病毒天然产物成分与文献证据对比,发现交集有大黄素、甘草酸、人参皂苷R1、利血平和杨梅素等。大黄素可破坏冠状病毒S蛋白与宿主ACE2相互作用,阻止病毒入侵宿主细胞;同时具有抑制3a蛋白离子通道、阻止病毒释放的作用。甘草酸或其衍生物也是国内相关团队在新冠病毒肺炎治疗研究中重点关注的候选药物,已进入临床试验。(3)针对中药预测结果中大量出现的芳香化合物,aCODE系统增加芳香植物提取物数据源,计算发现氨基肉桂酸、肉桂醛、茴香烯、紫苏醇、芳樟醇、柠檬烯具有潜在的抗病毒效应。提示“芳香避秽”的细胞分子学机理值得进一步深入研究。

submitted time 2020-02-17 Hits19278Downloads1764 Comment 0

7. chinaXiv:201910.00071 [pdf]

Sparse Representation Based Efficient Radiation Symmetry Analysis Method for Cylindrical Model of Inertial Confinement Fusion

张雁峰
Subjects: Mathematics >> Modeling and Simulation

Radiation symmetry evaluation is critical to the laser driven Inertial Confinement Fusion (ICF), which is usually done by solving a view-factor equation model. The model is nonlinear, and the number of equations can be very large when the size of discrete mesh element is very small to achieve a prescribed accuracy, which may lead to an intensive equation solving process. In this paper, an efficient radiation symmetry analysis approach based on sparse representation is presented, in which, 1) the Spherical harmonics, annular Zernike polynomials and Legendre-Fourier polynomials are employed to sparsely represent the radiation flux on the capsule and cylindrical cavity, and the nonlinear energy equilibrium equations are transformed into the equations with sparse coefficients, which means there are many redundant equations, 2) only a few equations are selected to recover such sparse coefficients with Latin hypercube sampling, 3) a Conjugate Gradient Subspace Thresholding Pursuit (CGSTP) algorithm is then given to rapidly obtain such sparse coefficients equation with as few iterations as possible. Finally, the proposed method is validated with two experiment targets for Shenguang II and Shenguang III laser facility in China. The results show that only one tenth of computation time is required to solve one tenth of equations to achieve the radiation flux with comparable accuracy. Further more, the solution is much more efficient as the size of discrete mesh element decreases, in which, only 1.2% computation time is required to obtain the accurate result.

submitted time 2019-10-23 Hits11928Downloads599 Comment 0

8. chinaXiv:201903.00067 [pdf]

基于谐波注入PWM的高速永磁同步电机纹波电流抑制方法

于吉坤; 李立毅; 杜鹏程; 张江鹏
Subjects: Dynamic and Electric Engineering >> Electrical Engineering

在高速永磁同步电机调速系统中,PWM 逆变器的低载波比和高速永磁同步 电机的小电感使得电机绕组中存在较大的纹波电流。为有效抑制纹波电流,提出一种 谐波注入 PWM 调制方式,即在 SPWM 正弦信号波中注入 3 次和 9 次谐波,通过优化 PWM 逆变器供电电压脉冲序列宽度,达到减小高速永磁同步电机纹波电流的目的。首 先,基于规则采样高速永磁同步电机控制系统,论述谐波注入 PWM 原理和实现方法; 其次,推导纹波电流谐波成分的计算公式,根据纹波电流谐波频谱分布的特点,引入 纹波电流谐波群畸变率定量描述纹波电流大小,以弥补纹波电流总畸变率的不足,对 谐波注入 PWM 的纹波电流抑制效果计算分析;最后,对谐波注入 PWM 方法进行实 验验证,实验结果表明,所提谐波注入 PWM 方法可以有效抑制高速永磁同步电机纹 波电流。

submitted time 2019-03-05 From cooperative journals:《电气工程学报》 Hits886Downloads659 Comment 0

9. chinaXiv:201812.00136 [pdf]

未折叠蛋白质的普遍初始热力学亚稳态

马晓亮; 侯成宇; 史丽萍; 李隆; 李佳成; 叶林; 杨霖; 赫晓东
Subjects: Biology >> Molecular Biology

探索和理解蛋白质折叠问题一直是分子生物学的挑战。未折叠的蛋白质应该存在一种普遍初始热力学亚稳态,否则无法解释蛋白质是如何在剧烈的热振动干扰下完成精确折叠的。文章通过分析水溶液环境和蛋白质折叠的相关性,揭示了一种由水分子屏蔽效应引起的未折叠蛋白质的普遍初始热力学亚稳态,该亚稳态的存在是环境中水分子的物理性质决定的并被认为是蛋白质正确折叠的必要条件。我们通过研究已发表的实验数据和建立分子模型,找到了该普遍初始热力学亚稳态存在的相关证据,通过理论分析初步探索了该热力学亚稳态导致蛋白质精确折叠的相关物理机制。

submitted time 2018-12-10 Hits8697Downloads1145 Comment 0

10. chinaXiv:201802.00090 [pdf]

有限温度SixGe1-x合金介电函数第一性原理模拟

杨家跃1 刘林 华1,2 谭建宇2
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics

基础辐射物性介电函数在热辐射研究中扮演了重要的角色。本文通过运用第一性原理分子动力学(AIMD)方法研究了SixGe1-x合金的介电函数随温度变化的规律。以热平衡构型作为输入结构,AIMD方法可有效计算不同温度下固体材料的电子能带结构,进而得到介电函数。研究表明,在300 K温度下SixGe1-x合金介电函数的理论计算值与对应的实验结果吻合;且随着合金中Si/Ge比例的增加,合金的禁带宽度增大,介电函数虚部主峰位置呈现红移且幅值增强。

submitted time 2018-02-01 From cooperative journals:《工程热物理学报》 Hits912Downloads582 Comment 0

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