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Extreme Attitude Prediction of Amphibious Vehicles Based on Improved Transformer Model and Extreme Loss Function
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作者 Qinghuai Zhang Boru Jia +3 位作者 Zhengdao Zhu Jianhua Xiang Yue Liu Mengwei Li 《哈尔滨工程大学学报(英文版)》 2026年第1期228-238,共11页
Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instabili... Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics. 展开更多
关键词 Amphibious vehicle Attitude prediction Extreme value loss function Enhanced transformer architecture External information embedding
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基于PyConv-Transformer的锂离子电池剩余寿命预测
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作者 吴忠强 吴江浩 《计量学报》 北大核心 2026年第1期102-110,共9页
锂离子电池的剩余使用寿命(RUL)是电池健康管理的重要参数。电池在实际使用过程中会出现容量再生现象,而且在电池数据采集过程中,通常难以避免噪声干扰,影响数据质量。针对以上问题提出一种基于Transformer结合金字塔卷积网络的电池RUL... 锂离子电池的剩余使用寿命(RUL)是电池健康管理的重要参数。电池在实际使用过程中会出现容量再生现象,而且在电池数据采集过程中,通常难以避免噪声干扰,影响数据质量。针对以上问题提出一种基于Transformer结合金字塔卷积网络的电池RUL预测模型,选取容量作为健康因子,利用金字塔卷积网络中不同大小的卷积核提取容量序列的特征信息,利用Transformer中的多头注意力机制进一步学习序列的时序特征。采用加权Huber损失函数,提高模型的鲁棒性;采用Dropout技术,提高模型的泛化能力,防止训练过程中出现过拟合。将所提预测模型在NASA和CALCE数据集上实验,并与其他模型比较。实验结果表明,所提模型的预测精度更高,在NASA和CALCE数据集上的相对误差分别为0.008 6、0.019 3;平均绝对误差分别为0.011 5、0.012 6;均方根误差分别为0.017 3、0.018 9。 展开更多
关键词 电学计量 剩余使用寿命 锂电池容量 金字塔卷积网络 transformER 加权Huber损失函数 DROPOUT
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Multi-Scale Vision Transformer with Dynamic Multi-Loss Function for Medical Image Retrieval and Classification
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作者 Omar Alqahtani Mohamed Ghouse +2 位作者 Asfia Sabahath Omer Bin Hussain Arshiya Begum 《Computers, Materials & Continua》 2025年第5期2221-2244,共24页
This paper introduces a novel method for medical image retrieval and classification by integrating a multi-scale encoding mechanism with Vision Transformer(ViT)architectures and a dynamic multi-loss function.The multi... This paper introduces a novel method for medical image retrieval and classification by integrating a multi-scale encoding mechanism with Vision Transformer(ViT)architectures and a dynamic multi-loss function.The multi-scale encoding significantly enhances the model’s ability to capture both fine-grained and global features,while the dynamic loss function adapts during training to optimize classification accuracy and retrieval performance.Our approach was evaluated on the ISIC-2018 and ChestX-ray14 datasets,yielding notable improvements.Specifically,on the ISIC-2018 dataset,our method achieves an F1-Score improvement of+4.84% compared to the standard ViT,with a precision increase of+5.46% for melanoma(MEL).On the ChestX-ray14 dataset,the method delivers an F1-Score improvement of 5.3%over the conventional ViT,with precision gains of+5.0% for pneumonia(PNEU)and+5.4%for fibrosis(FIB).Experimental results demonstrate that our approach outperforms traditional CNN-based models and existing ViT variants,particularly in retrieving relevant medical cases and enhancing diagnostic accuracy.These findings highlight the potential of the proposedmethod for large-scalemedical image analysis,offering improved tools for clinical decision-making through superior classification and case comparison. 展开更多
关键词 Medical image retrieval vision transformer multi-scale encoding multi-loss function ISIC-2018 ChestX-ray14
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Establishment of control equations and adjoint equations using block-pulse functions for optimal control of linear systems with time delays
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作者 WANG Xingtao(王兴涛) 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2002年第3期267-269,共3页
Control equation and adjoint equation are established by using block pulse functions, which transforms the linear time varying systems with time delays into a system of algebraic equations and the optimal control prob... Control equation and adjoint equation are established by using block pulse functions, which transforms the linear time varying systems with time delays into a system of algebraic equations and the optimal control problems are transformed into an optimization problem of multivariate functions thereby achieving the optimal control of linear systems with time delays. 展开更多
关键词 block-pulse functions control EQUATIONS ADJOINT EQUATIONS
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Activin A enhances neurofunctional recovery following traumatic spinal cord injury by inhibiting autophagy
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作者 Liqun Yu Zhaoyang Yin +12 位作者 Ruiqi Huang Zhibo Liu Yuchen Liu Xinxin Zheng Simin Song Zhaojie Wang Xiaolie He Yuxin Bai Li Yang Xu Xu Bairu Chen Jian Yin Yanjing Zhu 《Neural Regeneration Research》 2026年第6期2485-2494,共10页
In the early stages of traumatic spinal cord injury,extensive accumulation of autophagosomes creates a neurotoxic microenvironment,exacerbating neuronal cell death and worsening tissue damage,ultimately hindering neur... In the early stages of traumatic spinal cord injury,extensive accumulation of autophagosomes creates a neurotoxic microenvironment,exacerbating neuronal cell death and worsening tissue damage,ultimately hindering neurofunctional recovery.Activin A is a critical growth factor necessary for the development of the embryonic nervous system and for maintaining neuronal function in the adult cerebral cortex.It can inhibit excessive autophagy in ischemic stroke to reduce neuronal damage.However,the specific mechanism through which Activin A functions in the spinal cord remains poorly understood.In this study,we administered different concentrations of Activin A to neural stem cells from the spinal cord and found that Activin A stimulated the proliferation and neuronal differentiation of neural stem cells.Then,we established an in vitro oxidative stress model by using hydrogen peroxide to stimulate the neural stem cells-induced neurons.We found that Activin A could reduce apoptosis caused by oxidative stress.Subsequently,we treated a mouse model of spinal cord contusion with intrathecal injection of Activin A.Behavioral and electrophysiological results showed that Activin A promoted recovery of motor function and reconstruction of neural circuits in the model mice.Finally,RNA sequencing indicated that Activin A inhibited autophagy by activating the PI3K/AKT/mTOR pathway and upregulating the expression of synaptogenesis-related factor Sema3A in the spinal cord.These results suggest that Activin A may mediate the excessive autophagic response after spinal cord injury,promote the reconstruction of damaged neural circuits,and restore neurological function in the injured spinal cord. 展开更多
关键词 Activin A AUTOPHAGY cell differentiation motor function recovery neural regeneration neural stem cell NEUROPROTECTION phosphoinositide 3-kinase/protein kinase B pathway spinal cord injury transforming growth factor-βsuperfamily
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基于Transformer的无人机故障检测研究
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作者 张自旺 沈剑 +3 位作者 王晓光 刘繁 曹卓 贺斌娜 《机械设计与制造工程》 2026年第1期82-86,共5页
无人机故障检测作为保障飞行安全的核心技术,当前研究多依赖于仿真实验数据,并且传统方法难以有效捕捉飞行数据中的长程时空依赖关系。针对这些挑战,提出了一种基于Transformer架构的无人机故障检测方法,通过可学习位置编码和多头自注... 无人机故障检测作为保障飞行安全的核心技术,当前研究多依赖于仿真实验数据,并且传统方法难以有效捕捉飞行数据中的长程时空依赖关系。针对这些挑战,提出了一种基于Transformer架构的无人机故障检测方法,通过可学习位置编码和多头自注意力机制,构建传感器数据的时空依赖关系;同时结合焦点损失函数缓解类别不平衡问题。实验结果表明,该方法在真实飞行数据集上准确率达95%、F1分数达94%,相比基于LSTM和随机森林的故障检测方法展现更优的综合性能,并且在实时检测模拟中具有良好的可靠性,充分验证了其在真实飞行场景中的工程适用性。 展开更多
关键词 无人机 故障检测 transformER 焦点损失函数 实时检测模拟
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The Similarity Transformation of Regularizing Functionals and Simularity Property of Their Fourier Transformations
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作者 祝同江 《Journal of Beijing Institute of Technology》 EI CAS 1995年第2期105+99-105,共8页
Let and denote respectively the functionswhere λ≥1, The author discusses the similarity transformation of the regularizing functionals of these functions and the similar property of their Fourier transformation.
关键词 Fourier transform generalized functions/similarity transformation regularizing functionals
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The Fourier Transform of a Sort of Generalized Function
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作者 祝同江 《Journal of Beijing Institute of Technology》 EI CAS 1996年第2期106+101-106,共7页
The Fourier transforms of functions X ln e are given. where λ is a complex constant (λ≠-1,-2. …), a is a complex number. m=0. 1. 2,…,and
关键词 Fourier transform generalized function analytic exextension
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基于小波变换增强位置编码Transformer的空域流量预测 被引量:2
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作者 唐卫贞 刘波 +1 位作者 黄洲升 田齐齐 《现代电子技术》 北大核心 2025年第8期127-132,共6页
随着全球化进程的加快和航空技术的发展,对空中交通流量预测的精度要求也越来越高。为提高空中交通流量预测精度,减轻空中交通管制员的压力,提出一种增强位置编码的Transformer模型。利用小波变换对原始空域流量数据进行分析,通过信噪... 随着全球化进程的加快和航空技术的发展,对空中交通流量预测的精度要求也越来越高。为提高空中交通流量预测精度,减轻空中交通管制员的压力,提出一种增强位置编码的Transformer模型。利用小波变换对原始空域流量数据进行分析,通过信噪比选出性能最优的小波基函数,再进一步计算出小波系数并将其融入位置编码,以增强模型对时间序列数据的理解能力。实验结果表明,所提模型能够准确捕捉空中交通流量数据中的非平稳性和突变特征,其RMSE和MAPE评估指标较原始Transformer模型分别降低了29.9与2.9%,较LSTM模型分别降低了34.5与3.4%。该模型不仅提升了空域流量预测的准确性,也证实了小波变换在增强模型时间序列数据理解中的有效性,且为交通流量管理提供了一种新的技术方案。 展开更多
关键词 空域流量预测 增强位置编码 transformer模型 小波变换 LSTM模型 小波基函数
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电网N-1下融合CNN与Transformer的综合能源系统静态安全校核 被引量:1
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作者 陈厚合 丁唯一 +2 位作者 刘光明 李雪 张儒峰 《电力自动化设备》 北大核心 2025年第5期1-9,18,共10页
风光等新能源高比例渗透衍生出大量的源-荷场景,电-气综合能源系统(IEGS)的N-1安全校核面临计算挑战。深度学习技术在处理大量数据时具备显著优势,为解决该问题提供了新的思路。将评价电力系统安全性的Hyper-box和Hyper-ellipse判据推... 风光等新能源高比例渗透衍生出大量的源-荷场景,电-气综合能源系统(IEGS)的N-1安全校核面临计算挑战。深度学习技术在处理大量数据时具备显著优势,为解决该问题提供了新的思路。将评价电力系统安全性的Hyper-box和Hyper-ellipse判据推广到天然气系统,并形成IEGS综合安全指标以划分子系统的运行状态;构建卷积神经网络(CNN)-Transformer神经网络以适应量测数据与校核目标的非线性关系,实现快速校核;考虑到系统数据的量纲和数值差异大以及系统状态离散化的特点,分别对数据进行Z-score标准化和独热编码数值化以提升校核精度,并设计改进焦点损失函数以进一步提取不同的场景下天然气系统运行状态的变化规律。以含高比例新能源的综合能源系统(E5G5、E39G20系统)为算例,验证所提方法的高效性和准确性。 展开更多
关键词 电-气综合能源系统 N-1安全校核 深度学习 卷积神经网络 transformer神经网络 改进焦点损失函数
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REFINEMENTS OF TRANSFORMATION INEQUALITIES FOR ZERO-BALANCED HYPERGEOMETRIC FUNCTIONS 被引量:9
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作者 王淼坤 褚玉明 《Acta Mathematica Scientia》 SCIE CSCD 2017年第3期607-622,共16页
In the article, we present some refinements of three classes of transformation inequalities for zero-balanced hypergeometric functions by use of the updated monotonicity criterion for the quotient of power series.
关键词 Gauss hypergeometric function complete elliptic integrals quadratic transfor-mation Ramanujan cubic transformation
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Changes in Transformation of Soil Organic C and Functional Diversity of Soil Microbial Community Under Different Land Uses 被引量:22
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作者 LI Zhong-pei WU Xiao-chen CHEN Bi-yun 《Agricultural Sciences in China》 CAS CSCD 2007年第10期1235-1245,共11页
Changes in soil biological and biochemical properties under different land uses in the subtropical region of China were investigated in order to develop rational cultivation and fertilization management. A small water... Changes in soil biological and biochemical properties under different land uses in the subtropical region of China were investigated in order to develop rational cultivation and fertilization management. A small watershed of subtropical region of China was selected for this study. Land uses covered paddy fields, vegetable farming, fruit trees, upland crops, bamboo stands, and forestry. Soil biological and biochemical properties included soil organic C and nutrient contents, mineralization of soil organic C, and soil microbial biomass and community functional diversity. Soil organic C and total N contents, microbial biomass C and N, and respiration intensity under different land uses were changed in the following order: paddy fields (and vegetable farming) 〉 bamboo stands 〉 fruit trccs (and upland). The top surface (0-15 cm) paddy fields (and vegetable farming) were 76.4 and 80.8% higher in soil organic C and total N contents than fruit trees (and upland) soils, respectively. Subsurface paddy soils (15-30 cm) were 59.8 and 67.3% higher in organic C and total N than upland soils, respectively. Soil microbial C, N and respiration intensity in paddy soils (0-15 cm) were 6.36, 3.63 and 3.20 times those in fruit tree (and upland) soils respectively. Soil microbial metabolic quotient was in the order: fruit trees (and upland) 〉 forestry 〉 paddy fields. Metabolic quotient in paddy soils was only 47.7% of that in fruit tree (and upland) soils. Rates of soil organic C mineralization during incubation changed in the order: paddy fields 〉 bamboo stands 〉 fruit trees (and upland) and soil bacteria population: paddy fields 〉 fruit trees (and upland) 〉 forestry. No significant difference was found for fungi and actinomycetes populations. BIOLOG analysis indicated a changing order of paddy fields 〉 fruit trees (and upland) 〉 forestry in values of the average well cell development (AWCD) and functional diversity indexes of microbial community. Results also showed that the conversion from paddy fields to vegetable farming for 5 years resulted in a dramatic increase in soil available phosphorus content while insignificant changes in soil organic C and total N content due to a large inputs of phosphate fertilizers. This conversion caused 53, 41.5, and 41.3% decreases in soil microbial biomass C, N, and respiration intensity, respectively, while 23.6% increase in metabolic quotient and a decrease in soil organic C mineralization rate. Moreover, soil bacteria and actinomycetes populations were increased slightly, while fungi population increased dramatically. Functional diversity indexes of soil microbial community decreased significantly. It was concluded that land uses in the subtropical region of China strongly affected soil biological and biochemical properties. Soil organic C and nutrient contents, mineralization of organic C and functional diversity of microbial community in paddy fields were higher than those in upland and forestry. Overuse of chemical fertilizers in paddy fields with high fertility might degrade soil biological properties and biochemical function, resulting in deterioration of soil biological quality. 展开更多
关键词 land use patterns transformation of soil organic carbon functional diversity of soil microbial community
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Analysis of Ocean Wave Characteristic Distributions Modeled by Two Different Transformed Functions 被引量:2
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作者 Duanfeng Han Ting Cui +3 位作者 Yingfei Zan Lihao Yuan Song Ding Zhigang Li 《Journal of Marine Science and Application》 CSCD 2019年第3期247-259,共13页
The probability distributions of wave characteristics from three groups of sampled ocean data with different significant wave heights have been analyzed using two transformation functions estimated by non-parametric a... The probability distributions of wave characteristics from three groups of sampled ocean data with different significant wave heights have been analyzed using two transformation functions estimated by non-parametric and parametric methods. The marginal wave characteristic distribution and the joint density of wave properties have been calculated using the two transformations, with the results and accuracy of both transformations presented here. The two transformations deviate slightly between each other for the calculation of the crest and trough height marginal wave distributions, as well as the joint densities of wave amplitude with other wave properties. The transformation methods for the calculation of the wave crest and trough height distributions are shown to provide good agreement with real ocean data. Our work will help in the determination of the most appropriate transformation procedure for the prediction of extreme values. 展开更多
关键词 Wave characteristic DISTRIBUTIONS transformed GAUSSIAN process transformed function PARAMETRIC METHOD NON-PARAMETRIC METHOD Crossing-density function
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Local Extrema of Periodic Function’s Wavelet Transform 被引量:3
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作者 FAN Qi-bin SONG Xiao-yan 《Wuhan University Journal of Natural Sciences》 EI CAS 2005年第6期949-952,共4页
The theory of detecling ridges in the modulus of the continuous wavelet transform is presented as well as reconstructing signal by using information on ridges,To periodic signal we suppose Morlet wavelet as basic wave... The theory of detecling ridges in the modulus of the continuous wavelet transform is presented as well as reconstructing signal by using information on ridges,To periodic signal we suppose Morlet wavelet as basic wavelet, and research the local extreme point and extrema of the wavelet transform on periodic function for the collection of signal' s instantaneous amplitude and period. 展开更多
关键词 extrema periodic function wavelet transform time-frequency analysis
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Transforming growth factor beta 1,a cytokine with regenerative functions 被引量:10
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作者 Wale Sulaiman Doan H.Nguyen 《Neural Regeneration Research》 SCIE CAS CSCD 2016年第10期1549-1552,共4页
We review the biology and role of transforming growth factor beta 1(TGF-β1)in peripheral nerve injury and regeneration,as it relates to injuries to large nerve trunks(i.e.,sciatic nerve,brachial plexus),which often l... We review the biology and role of transforming growth factor beta 1(TGF-β1)in peripheral nerve injury and regeneration,as it relates to injuries to large nerve trunks(i.e.,sciatic nerve,brachial plexus),which often leads to suboptimal functional recovery.Experimental studies have suggested that the reason for the lack of functional recovery resides in the lack of sufficient mature axons reaching their targets,which is a result of the loss of the growth-supportive environment provided by the Schwann cells in the distal stump of injured nerves.Using an established chronic nerve injury and delayed repair animal model that accu-rately mimics chronic nerve injuries in humans,we summarize our key findings as well as others to better understand the pathophysiology of poor functional recovery.We demonstrated that 6 month TGF-β1 treat-ment for chronic nerve injury significantly improved Schwann cell capacity to support axonal regeneration.When combined with forskolin,the effect was additive,as evidenced by a near doubling of regenerated axons proximal to the repair site.We showed that in vivo application of TGF-β1 and forskolin directly onto chronically injured nerves reactivated chronically denervated Schwann cells,induced their proliferation,and upregulated the expression of regeneration-associated proteins.The effect of TGF-β1 and forskolin on old nerve injuries is quite impressive and the treatment regiment appears to mediate a growth-supportive milieu in the injured peripheral nerves.In summary,TGF-β1 and forskolin treatment reactivates chronical-ly denervated Schwann cells and could potentially be used to extend and prolong the regenerative responses to promote axonal regeneration. 展开更多
关键词 chronic nerve injuries transforming growth factor Schwann cells axonal regeneration regeneration-associatedproteins functional recovery
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ANALYSIS OF REMOTE SENSING ARCHAEOLOGY ON TRAFFIC FUNCTION TRANSFORMATION OF TONGJI GRAND CANAL IN SUI AND TANG DYNASTIES 被引量:6
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作者 WANG Xin-yuan HE Hui +2 位作者 ZHOU Ying-qiu GAO Chao HAN Shuang-wang 《Chinese Geographical Science》 SCIE CSCD 2006年第2期95-101,共7页
In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route.... In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route. Canals should be dug so as to make up the lack of north-south river. Tongji Grand Canal, dug in the first year of Daye (605 A.D.) in the Sui Dynasty, was the important component of north-south system of Grand Canals in China. It promoted economic and social development of the Sui, Tang and Song dynasties (605 A.D.-1279 A.D.). As Tongji Canal (i.e. Tongji Grand Canal) flowed across the Huaibei Plain, which is aggraded by abundant mud and sand deposit resulted from the Huanghe (Yellow) River flooding, many traces (such as old channel) and human culture heritages were buried under mud-sand. Tongji Canal was silted up, and disappeared in the Jin Dynasty (1115 A.D.-1234 A.D.). From then on, there were many different stories about the flowing route of the canal in historical literature. Based on space-bone and air-bone remote sensing imagery, we attempt to search the old channel of Tongji Canal, and supplement historical record. The paper discusses transformation process of Tongji Canal’s traffic function, and resumptively summarizes the reasons of the transformation, which results from synthetic function of physical geographical, political, economic, and social conditions. 展开更多
关键词 Tongji Canal Traffic Geography functional transformation remote sensing archaeology
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An extended functional transformation method and its application in some evolution equations 被引量:2
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作者 丁海勇 徐西祥 杨宏祥 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第9期1687-1690,共4页
In this paper, an extended functional transformation is given to solve some nonlinear evolution equations. This function, in fact, is a solution of the famous KdV equation, so this transformation gives a transformatio... In this paper, an extended functional transformation is given to solve some nonlinear evolution equations. This function, in fact, is a solution of the famous KdV equation, so this transformation gives a transformation between KdV equation and other soliton equations. Then many new exact solutions can be given by virtue of the solutions of KdV equation. 展开更多
关键词 extended functional transformation exact solution KdV equation
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Generic functional modelling of multi-pulse auto-transformer rectifier units for more-electric aircraft applications 被引量:1
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作者 Tao YANG Serhiy BOZHKO +2 位作者 Patrick WHEELER Shaoping WANG Shuai WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第5期883-891,共9页
The Auto-Transformer Rectifier Unit(ATRU) is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, t... The Auto-Transformer Rectifier Unit(ATRU) is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, the ATRU has become a preferred AC/DC solution to supply power to the electric environment control system on-board future aircraft. In this paper, a general modelling method for ATRUs is introduced. The developed model is based on the fact that the DC voltage and current are strongly related to the voltage and current vectors at the AC terminals of ATRUs. In this paper, we carry on our research in modelling symmetric 18-pulse ATRUs and develop a generic modelling technique. The developed generic model can study not only symmetric but also asymmetric ATRUs. An 18-pulse asymmetric ATRU is used to demonstrate the accuracy and efficiency of the developed model by comparing with corresponding detailed switching SABER models provided by our industrial partner. The functional models also allow accelerated and accurate simulations and thus enable whole-scale more-electric aircraft electrical power system studies in the future. 展开更多
关键词 Asymmetric transformer functional modelling More-Electric Aircraft Multi-pulse rectifier transformer rectifier unit
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Steganography based on wavelet transform and modulus function 被引量:1
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作者 Kang Zhiwei Liu Jing He Yigang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2007年第3期628-632,共5页
In order to provide larger capacity of the hidden secret data while maintaining a good visual quality of stego-image, in accordance with the visual property that human eyes are less sensitive to strong texture, a nove... In order to provide larger capacity of the hidden secret data while maintaining a good visual quality of stego-image, in accordance with the visual property that human eyes are less sensitive to strong texture, a novel steganographic method based on wavelet and modulus function is presented. First, an image is divided into blocks of prescribed size, and every block is decomposed into one-level wavelet. Then, the capacity of the hidden secret data is decided with the number of wavelet coefficients of larger magnitude. Finally, secret information is embedded by steganography based on modulus function. From the experimental results, the proposed method hides much more information and maintains a good visual quality of stego-image. Besides, the embedded data can be extracted from the stego-image without referencing the original image. 展开更多
关键词 STEGANOGRAPHY capacity wavelet transform modulus function HVS.
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Mechanisms of Transforming CH_x to CO on Ni(111) Surface by Density Functional Theory 被引量:1
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作者 Yingzhe Yu Hao Lei +1 位作者 Lingguang Wang Minhua Zhang 《Transactions of Tianjin University》 EI CAS 2019年第4期330-339,共10页
To elucidate feasible routes of producing CO from CH 3 and unravel the eff ect of adsorbed O on CH x transformation, the reactivity of CH x ( x = 1-3) with and without the assistance of adsorbed atomic O on Ni(111) wa... To elucidate feasible routes of producing CO from CH 3 and unravel the eff ect of adsorbed O on CH x transformation, the reactivity of CH x ( x = 1-3) with and without the assistance of adsorbed atomic O on Ni(111) was explored using density functional theory calculations. The adsorption energies of CH x ( x = 0-3) were found to be signifi cantly reduced on an O-preadsorbed Ni(111) surface compared to a pure surface. Furthermore, O-assisted one-step dehydrogenation of CH x ( x = 1-3) features energy barriers and thus is diffi cult to proceed. In terms of energy, the direct dissociation of CH 3 is favorable, except for the last CH dehydrogenation, which is energy intensive. Interestingly, in O-assisted two-step CH transformation to CO via CHO intermediate, the barrier is dramatically lowered. The successive dehydrogenations of CH x O ( x = 1-3) were also found to be a route for CO formation. Finally, two possible pathways from CH 3 to CO are proposed:(a) CH 3 → CH 2 → CH → CHO → CO;(b) CH 3 → CH 3 O → CH 2 O → CHO → CO. 展开更多
关键词 Density functional theory CH X transformation CO Ni(111)
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