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1.
针对迭代软阈值投影算法中的软阈值函数收缩功能较差的问题,提出了迭代p阈值投影算法。用p阈值函数替换迭代软阈值投影算法中的软阈值函数,对小系数的惩罚更大,对大系数产生更小的偏置,以抑制噪声,减少重建误差。为加快算法速度,利用Nesterov梯度加速技术,设计了快速迭代p阈值投影算法,用于磁共振图像重建。在紧标架为平移不变离散小波变换和轮廓波下,将快速迭代p阈值投影算法用于压缩感知磁共振成像。与光滑化的快速迭代软阈值算法、迭代软阈值投影算法和交替方向乘子法进行仿真对比分析的结果表明,快速迭代p阈值投影算法提高了磁共振成像的重建速度和重建质量。分析了p值对算法性能的影响,给出了适合的p值选择方法,以获得较好的收敛速度、减小重构误差。  相似文献   

2.
鲁棒主成分分析(Robust principal component analysis,RPCA)模型中秩函数和 L 0 范数的求解是非确定性多项式(Nondeterministic polynominal,NP)难问题,凸近似模型的求解通常会导致过收缩。本文结合加权方法和 L p 范数提出了一种基于双加权 L p 范数的RPCA模型,利用加权 S p 范数低秩项和加权 L p 范数稀疏项分别对RPCA框架中的低秩恢复问题和稀疏恢复问题进行建模,使其更接近秩函数和 L 0 范数最小化问题的解,提升了矩阵秩估计和稀疏估计的准确性。为了验证模型性能,本文利用图像的非局部自相似性,结合相似图像块组的低秩性与椒盐噪声的稀疏性,将双加权 L p 范数鲁棒主成分分析模型应用于去除椒盐噪声过程中。定量与定性的实验结果表明,本文模型性能优于其他模型,同时奇异值过收缩分析也表明本文模型能够有效抑制秩成分的过度收缩。  相似文献   

3.
文档级关系提取(Document relationship extraction,DRE)旨在多条句子中识别实体间的关系,而实体可能对应于跨越句子边界的多次提及,其中代词实体提及是因句子之间连接而普遍存在的语法现象,也是影响句子推理的一个重要因素。然而,以往的研究大多侧重于普通实体提及之间的关系,却很少关注代词实体提及的共指和关系捕获。本文提出了基于上下文共指实体依赖(Contextual coreference entity dependency,CCED)的文档级关系抽取模型,即通过融合普通实体和代词实体表示来构建共指实体依赖关系的上下文图结构,并在图上进行实体对间的全局交互推理,从而对实体关系的相互依赖进行建模。分别在公共数据集DocRED、DialogRE和MPDD上对CCED模型进行评估,结果显示在DocRED数据集上,与表现最好的基线模型DocuNet-BERT相比,CCED模型在测试集上的Ign F1性能提高0.55%,F1性能提高0.35%。在DialogRE和MPDD数据集上,与表现最好的基线模型COLN相比,CCED模型在DialogRE测试集上的F1性能提高1.02%,在MPDD测试集上的ACC性能提高1.19%。实验结果验证了新模型对于文档级关系抽取的有效性。  相似文献   

4.
卢奇  龚勋 《数据采集与处理》2023,38(5):1048-1057
不同于纹理图像,深度图像中的像素点代表采集设备到场景各点的距离,直接使用通用图像修复方法并不能有效恢复深度图像中缺失区域的场景结构,本文提出一个两阶段编解码结构的生成对抗网络以解决深度图像修复问题。与常见生成对抗网络(Generative adversarial networks,GAN)模型不同,本文的生成器网络包括深度生成G1和深度修复G2两个模块。G1模块从RGB图像得到预测深度,替换待修复深度图像缺失区域,保证修复区域局部结构一致性。G2模块引入RGB图像边缘结构,保证全局结构一致性。针对现有图像修复方法没有考虑到修复区域间的一致性问题,设计结构一致注意力模块(Structure coherent attention,SCA)加入到G2中改善修复效果。本文提出的深度图像修复模型在主流数据集上进行了验证,利用结构约束并经过两阶段的生成器模型和判别器模型的共同作用,有效改善了深度图像修复效果。  相似文献   

5.
突发事件发生后,准确地分析网民的情感状态,实现对网民情感状态演变的引导,对管控突发事件舆情、维护社会稳定有重大的现实意义。依据网民对突发事件的评论特性构建了网民情感状态的完备集,并从突发事件利益相关者和突发事件本身两个角度建立不同情绪集。依据传染病模型的传播方式,建立了基于SIS(Susceptible-infectious-susceptible)传染病模型的网民情感状态演变模型EP-SIS和EO-SIS。利用网民对“新型肺炎病毒”的微博评论对模型进行了实证研究,获取影响因子的权重,模型对网民负面情感转换率为0.72。本文构建的突发事件网民情感演变模型可以从不同角度干预,使突发事件中网民负面情感状态发生演变。  相似文献   

6.
本文采用惩罚逻辑回归方法,利用威斯康星大学的乳腺癌数据对乳腺肿瘤进行预测。首先选取与乳腺癌相关的10个指标作为自变量,接着采用逻辑回归、LASSO惩罚逻辑回归、L2惩罚逻辑回归和弹性网惩罚逻辑回归作为分类器,利用75%的数据集作为训练集建立模型,最后利用25%的测试集、混淆矩阵和ROC曲线评估不同模型的预测精度。结果表明,LASSO惩罚逻辑回归的预测表现最好,预测精度达到97.18%;弹性网惩罚逻辑回归的预测表现随着α的增大发生变化,特别当α=0.9时,预测精度达到97.18%,与LASSO惩罚逻辑回归的预测表现一样好;L2惩罚逻辑回归的预测表现排第3,逻辑回归表现最差。因此,在乳腺肿瘤诊断中可借助LASSO惩罚逻辑回归和弹性网惩罚逻辑回归提高诊断精度。  相似文献   

7.
针对无人驾驶场景下行人多尺度、小尺度造成漏检率升高,检测精度下降的问题,本文提出一种融合深浅层特征和级联动态选择机制的行人检测方法。首先,在YOLO v3-tiny的基础上基于密集连接的卷积神经网络改进特征提取部分,融合行人的深层特征和浅层特征加强网络对行人的识别能力;其次,在改进的主干网络上级联具有动态选择机制的注意力模块,使检测网络更加适应动态的行人尺度变化;最后,本文选择BDD 100K数据集和Caltech加州理工学院行人数据集进行实验,在保证实时性的前提下(25 ms/张),本文模型在BDD 100K数据集行人漏检率降低11.4%,平均检测精度提高11.7%,在Caltech行人漏检率降低10.1%,平均检测精度提高6.7%,适用于无人驾驶行人检测领域。  相似文献   

8.
现有的非负矩阵分解方法往往聚焦于数据全局结构信息的学习,在很多情况下忽略了对数据局部信息的学习,而局部学习的方法也通常局限于流行学习,存在一些缺陷。为解决这一问题,提出了一种基于数据局部相似性学习的鲁棒非负矩阵分解算法(Robust nonnegative matrix factorization with local similarity learning, RLS-NMF)。采用一种新的数据局部相似性学习方法,它与流形方法存在显著区别,能够同时学习数据的全局结构信息,从而能挖掘数据类内相似和类间相离的性质。同时,考虑到现实应用中的数据存在异常值和噪声,该算法还使用l2,1范数拟合特征残差,过滤冗余的噪声信息,保证了算法的鲁棒性。多个基准数据集上的实验结果显示了该算法的最优性能,进一步证明了该算法的有效性。  相似文献   

9.
设计了一种基于现场可编程门阵列(Field programmable gate array, FPGA)的低硬件成本256点快速傅里叶变换(Fast Fourier transform, FFT)处理器的IP核。采用按频率抽取的基-24算法和单路延迟负反馈(Single-path delay feedback, SDF)流水线架构用于减少旋转因子的复数乘法运算复杂度。为了降低硬件成本,提出了一种串接正则有符号数(Canonical signed digit, CSD)常数乘法器取代常用的布斯乘法器用来完成旋转因子W256i与对应序列的复数乘法运算,同时这种乘法器还能够移除存储旋转因子系数的只读存储器(Read only memory, ROM)。该处理器IP核基于QUARTUS PRIME平台进行综合,在Cyclone 10LP FPGA上实现。结果显示,该FFT处理器最高工作频率为100 MHz,对于24位符号数FFT运算,逻辑单元(Logic elements, LEs)使用量与记忆体位(Memory bits, MBs)使用量仅为3 978 LEs和6 456 MBs。  相似文献   

10.
血流和血氧是生物体重要的生理参数,反映了生物体的机能状态。对于起病急且变化迅速的颅脑损伤,将脑血流和血氧作为监测颅脑损伤的参数,有利于颅脑损伤的诊疗和评估。论文采用光谱分析和激光散斑成像技术构建的联合测量系统,监测脂多糖诱导小鼠颅脑损伤过程中的血流血氧,并进一步分析了高渗盐水和甘露醇两种药物治疗脑损伤效果的一致性和差异性。实验结果显示,与对照组血氧血流值(1.09±0.075,0.75±0.019)相比,脂多糖能引起小鼠的脑血流(1.36±0.080)升高和脑血氧(0.62±0.021)降低,具有显著性差异。在治疗后血氧和血流逐渐恢复,且高渗盐水治疗后的恢复更加明显。研究发现,颅脑损伤后血流和血氧呈现相反变化趋势,侧面反映了颅脑损伤后血脑屏障改变导致的血脑供养失衡,而治疗剂改善后的血流血氧情况恢复,说明血流血氧可作为疗效评估的重要参数。因此采用光谱分析技术和激光散斑成像技术对血氧和血流进行联合检测为脑损伤的实时监测和药物疗效评估提供了一种技术方案。  相似文献   

11.
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.  相似文献   

12.
European Community policy and the market   总被引:1,自引:0,他引:1  
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.  相似文献   

13.
融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。  相似文献   

14.
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.  相似文献   

15.
This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.  相似文献   

16.
Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   

17.
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.  相似文献   

18.
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.  相似文献   

19.
基于复小波噪声方差显著修正的SAR图像去噪   总被引:4,自引:1,他引:3  
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。  相似文献   

20.
蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。  相似文献   

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