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Pseudo channel:time embedding for motor imagery decoding
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作者 MIAO Zhengqing ZHAO Meirong 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2024年第3期308-317,共10页
Motor imagery(MI)based electroencephalogram(EEG)represents a frontier in enabling direct neural control of external devices and advancing neural rehabilitation.This study introduces a novel time embedding technique,te... Motor imagery(MI)based electroencephalogram(EEG)represents a frontier in enabling direct neural control of external devices and advancing neural rehabilitation.This study introduces a novel time embedding technique,termed traveling-wave based time embedding,utilized as a pseudo channel to enhance the decoding accuracy of MI-EEG signals across various neural network architectures.Unlike traditional neural network methods that fail to account for the temporal dynamics in MI-EEG in individual difference,our approach captures time-related changes for different participants based on a priori knowledge.Through extensive experimentation with multiple participants,we demonstrate that this method not only improves classification accuracy but also exhibits greater adaptability to individual differences compared to position encoding used in Transformer architecture.Significantly,our results reveal that traveling-wave based time embedding crucially enhances decoding accuracy,particularly for participants typically considered“EEG-illiteracy”.As a novel direction in EEG research,the traveling-wave based time embedding not only offers fresh insights for neural network decoding strategies but also expands new avenues for research into attention mechanisms in neuroscience and a deeper understanding of EEG signals. 展开更多
关键词 motor imagery(MI) pseudo channel electroencephalogram(EEG) neural networks
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Long‐life lithium batteries enabled by a pseudo‐oversaturated electrolyte
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作者 Youchun Yu Simeng Wang +6 位作者 Juyan Zhang Weiwei Qian Nana Zhang Guangjie Shao Haiyan Bian Yuwen Liu Lan Zhang 《Carbon Energy》 SCIE EI CAS CSCD 2024年第4期115-127,共13页
The specific energy of Li metal batteries(LMBs)can be improved by using high‐voltage cathode materials;however,achieving long‐term stable cycling performance in the corresponding system is particularly challenging f... The specific energy of Li metal batteries(LMBs)can be improved by using high‐voltage cathode materials;however,achieving long‐term stable cycling performance in the corresponding system is particularly challenging for the liquid electrolyte.Herein,a novel pseudo‐oversaturated electrolyte(POSE)is prepared by introducing 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether(TTE)to adjust the coordination structure between diglyme(G2)and lithium bis(trifluoromethanesulfonyl)imide(LiTFSI).Surprisingly,although TTE shows little solubility to LiTFSI,the molar ratio between LiTFSI and G2 in the POSE can be increased to 1:1,which is much higher than that of the saturation state,1:2.8.Simulation and experimental results prove that TTE promotes closer contact of the G2 molecular with Li^(+)in the POSE.Moreover,it also participates in the formation of electrolyte/electrode interphases.The electrolyte shows outstanding compatibility with both the Li metal anode and typical high‐voltage cathodes.Li||Li symmetric cells show a long life of more than 2000 h at 1 mA cm^(−2),1 mAh cm^(−2).In the meantime,Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cell with the POSE shows a high reversible capacity of 134.8 mAh g^(−1 )after 900 cycles at 4.5 V,1 C rate.The concept of POSE can provide new insight into the Li^(+)solvation structure and in the design of advanced electrolytes for LMBs. 展开更多
关键词 high voltage lithium metal batteries pseudo‐oversaturated electrolyte solid electrolyte interphases(SEI) solvation structure
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Laboratory Implementation of Direct Torque Controller based Speed Loop Pseudo Derivative Feedforward Controller for PMSM Drive
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作者 Prabhakaran Koothu Kesavan Umashankar Subramaniam Dhafer J.Almakhles 《CES Transactions on Electrical Machines and Systems》 EI CSCD 2024年第1期12-21,共10页
This paper,evaluate the effectiveness of a proposed speed loop pseudo derivative feedforward(PDFF)controller-based direct torque controller(DTC)for a PMSM drive against the performance of existing PI speed controller-... This paper,evaluate the effectiveness of a proposed speed loop pseudo derivative feedforward(PDFF)controller-based direct torque controller(DTC)for a PMSM drive against the performance of existing PI speed controller-based DTC and hysteresis current controller(HCC).The proposed PDFF-based speed regulator effectively reduces oscillation and overshoot associated with rotor angular speed,electromagnetic torque,and stator current.Two case studies,one using forward-to-reverse motoring operation and the other involving reverse-to-forward braking operation,has been validated to show the effectiveness of the proposed control strategy.The proposed controller's superior performance is demonstrated through experimental verification utilizing an FPGA controller for a 1.5 kW PMSM drive laboratory prototype. 展开更多
关键词 Direct torque control pseudo derivative feedforward controller Permanent magnet synchronous motor(PMSM)
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Pseudo S-Asymptotically(ω,c)-Periodic Solutions to Fractional Differential Equations of Sobolev Type
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作者 MAO Hang-ning CHANG Yong-kui 《Chinese Quarterly Journal of Mathematics》 2024年第3期295-306,共12页
In this paper,we firstly recall some basic results on pseudo S-asymptotically(ω,c)-periodic functions and Sobolev type fractional differential equation.We secondly investigate some existence of pseudo S-asymptotical... In this paper,we firstly recall some basic results on pseudo S-asymptotically(ω,c)-periodic functions and Sobolev type fractional differential equation.We secondly investigate some existence of pseudo S-asymptotically(ω,c)-periodic solutions for a semilinear fractional differential equations of Sobolev type.We finally present a simple example. 展开更多
关键词 pseudo S-asymptotically(ω c)-periodic functions Evolution equations Sobolev type Fractional differential equations Existence and uniqueness
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IgG4 Coronary Arteritis Presenting as a Cardiac Pseudo-Tumour
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作者 Elaine Mo-Chee Chau Catherine Yuet-Hung Wong Raymond Hin-Suen Liang 《Case Reports in Clinical Medicine》 2024年第9期345-352,共8页
We report on an unusual case presenting with a cardiac pseudo-tumour on echocardiogram, which corresponded to a large soft tissue mural thickening around the mid-right coronary artery. There were similar but not as th... We report on an unusual case presenting with a cardiac pseudo-tumour on echocardiogram, which corresponded to a large soft tissue mural thickening around the mid-right coronary artery. There were similar but not as thick mural lesions around other parts of the coronary arteries. The so-called “pigs-in-a-blanket” sign on computed tomography (CT) scan was pathognomonic of IgG4 coronary arteritis. The IgG4 level was grossly elevated at more than 10 times the upper limit of normal. Positron emission tomography (PET)-CT scans with 18F-fluoro-deoxy-glucose (FDG) and 68Ga-Fibroblast Activation Protein Inhibitor (FAPI) were performed to assess the extent of organ involvement of the IgG4-related disease. The patient was treated with 8 injections of rituximab with good serological response. However, the coronary arteritis findings on CT scan remained unchanged. 展开更多
关键词 IgG4-Related Disease Coronary Arteritis Cardiac pseudo-Tumour “Pigs-in-a-Blanket” Sign
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Pseudo-Semi-Overlap Functions-Based Fuzzy Rough Sets Applied to Image Edge Extraction
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作者 Ran Yin Minge Chen +2 位作者 Yu Liu Yafei Zhao Jianwei Li 《Journal of Applied Mathematics and Physics》 2024年第7期2347-2366,共20页
As an extension of overlap functions, pseudo-semi-overlap functions are a crucial class of aggregation functions. Therefore, (I, PSO)-fuzzy rough sets are introduced, utilizing pseudo-semi-overlap functions, and furth... As an extension of overlap functions, pseudo-semi-overlap functions are a crucial class of aggregation functions. Therefore, (I, PSO)-fuzzy rough sets are introduced, utilizing pseudo-semi-overlap functions, and further extended for applications in image edge extraction. Firstly, a new clustering function, the pseudo-semi-overlap function, is introduced by eliminating the symmetry and right continuity present in the overlap function. The relaxed nature of this function enhances its applicability in image edge extraction. Secondly, the definitions of (I, PSO)-fuzzy rough sets are provided, using (I, PSO)-fuzzy rough sets, a pair of new fuzzy mathematical morphological operators (IPSOFMM operators) is proposed. Finally, by combining the fuzzy C-means algorithm and IPSOFMM operators, a novel image edge extraction algorithm (FCM-IPSO algorithm) is proposed and implemented. Compared to existing algorithms, the FCM-IPSO algorithm exhibits more image edges and a 73.81% decrease in the noise introduction rate. The outstanding performance of (I, PSO)-fuzzy rough sets in image edge extraction demonstrates their practical application value. 展开更多
关键词 pseudo-Semi-Overlap Functions Fuzzy Rough Set Fuzzy Mathematical Morphology Image Edge Extraction
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Defect image segmentation using multilevel thresholding based on firefly algorithm with opposition-learning 被引量:3
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作者 陈恺 戴敏 +2 位作者 张志胜 陈平 史金飞 《Journal of Southeast University(English Edition)》 EI CAS 2014年第4期434-438,共5页
To segment defects from the quad flat non-lead QFN package surface a multilevel Otsu thresholding method based on the firefly algorithm with opposition-learning is proposed. First the Otsu thresholding algorithm is ex... To segment defects from the quad flat non-lead QFN package surface a multilevel Otsu thresholding method based on the firefly algorithm with opposition-learning is proposed. First the Otsu thresholding algorithm is expanded to a multilevel Otsu thresholding algorithm. Secondly a firefly algorithm with opposition-learning OFA is proposed.In the OFA opposite fireflies are generated to increase the diversity of the fireflies and improve the global search ability. Thirdly the OFA is applied to searching multilevel thresholds for image segmentation. Finally the proposed method is implemented to segment the QFN images with defects and the results are compared with three methods i.e. the exhaustive search method the multilevel Otsu thresholding method based on particle swarm optimization and the multilevel Otsu thresholding method based on the firefly algorithm. Experimental results show that the proposed method can segment QFN surface defects images more efficiently and at a greater speed than that of the other three methods. 展开更多
关键词 quad flat non-lead QFN surface defects opposition-learning firefly algorithm multilevel Otsu thresholding algorithm
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Acute Colonic Pseudo-Obstruction (ACPO): An Expanding Colon with Unusual Risk Factors
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作者 Kelly Schulte Alyson Terry +1 位作者 Grace Boyle Dmitriy Scherbak 《Open Journal of Internal Medicine》 2024年第2期167-174,共8页
The distention of the colon without mechanical or anatomical obstruction, Acute Colonic Pseudo-obstruction (ACPO), is a common condition occurring in the critically ill. ACPO in the setting of an acute pulmonary embol... The distention of the colon without mechanical or anatomical obstruction, Acute Colonic Pseudo-obstruction (ACPO), is a common condition occurring in the critically ill. ACPO in the setting of an acute pulmonary embolism and embolic stroke is a rarity. A 76-year-old female with shortness of breath, left hemiparesis and right-sided paresthesias presented with acute pulmonary embolism and acute infarcts of the left caudate nucleus, thalamus and occipital lobe. Her hospitalization was complicated with persistent distention of the large bowel without dilation of the small bowel. Empiric antibiotics were initiated without improvement and laboratory studies including Clostridium difficile were negative. She underwent nasogastric decompression and two decompressive colonoscopies with a resolution of her symptoms. This case illustrates an example of acute abdominal distension, without underlying etiology, in the setting of acute embolism of the pulmonary and cerebral vasculature. Early identification and action with decompressive colonoscopy were key to preventing further bowel damage or rupture. 展开更多
关键词 Acute Colonic pseudo-Obstruction ACPO Ogilvie’s Syndrome Colonic Dilation Acute Embolic Infarcts Cerebrovascular Accident Pulmonary Embolism PE
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Does sevoflurane sedation in pediatric patients lead to“pseudo”leptomeningeal enhancement in the brain on 3 Tesla magnetic resonance imaging? 被引量:1
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作者 Kiran Hilal Kumail Khandwala +2 位作者 Saima Rashid Faheemullah Khan Shayan Sirat Maheen Anwar 《World Journal of Radiology》 2023年第4期127-135,共9页
BACKGROUND Prominent leptomeningeal contrast enhancement(LMCE)in the brain is observed in some pediatric patients during sedation for imaging.However,based on clinical history and cerebrospinal fluid analysis,the pati... BACKGROUND Prominent leptomeningeal contrast enhancement(LMCE)in the brain is observed in some pediatric patients during sedation for imaging.However,based on clinical history and cerebrospinal fluid analysis,the patients are not acutely ill and do not exhibit meningeal signs.Our study determined whether sevoflurane inhalation in pediatric patients led to this pattern of‘pseudo’LMCE(pLMCE)on 3 Tesla magnetic resonance imaging(MRI).AIM To highlight the significance of pLMCE in pediatric patients undergoing enhanced brain MRI under sedation to avoid misinterpretation in reports.METHODS A retrospective cross-sectional evaluation of pediatric patients between 0-8 years of age was conducted.The patients underwent enhanced brain MRI under inhaled sevoflurane.The LMCE grade was determined by two radiologists,and interobserver variability of the grade was calculated using Cohen’s kappa.The LMCE grade was correlated with duration of sedation,age and weight using the Spearman rho rank correlation.RESULTS A total of 63 patients were included.Fourteen(22.2%)cases showed mild LMCE,48(76.1%)cases showed moderate LMCE,and 1 case(1.6%)showed severe LMCE.We found substantial agreement between the two radiologists in detection of pLMCE on post-contrast T1 imaging(kappa value=0.61;P<0.001).Additionally,we found statistically significant inverse and moderate correlations between patient weight and age.There was no correlation between duration of sedation and pLMCE.CONCLUSION pLMCE is relatively common on post-contrast spin echo T1-weighted MRI of pediatric patients sedated by sevoflurane due to their fragile and immature vasculature.It should not be misinterpreted for meningeal pathology.Knowing pertinent clinical history of the child is an essential prerequisite to avoid radiological overcalling and the subsequent burden of additional investigations. 展开更多
关键词 BRAIN Pediatrics Gadolinium contrast pseudo leptomeningeal enhancement 3 Tesla magnetic resonance imaging SEVOFLURANE
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以假性Bartter综合征为主要表现的囊性纤维化患儿3例并文献复习 被引量:1
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作者 张继燕 孙林军 +4 位作者 段效军 张子敏 肖政辉 陈艳萍 游洁玉 《中国当代儿科杂志》 CAS CSCD 北大核心 2024年第5期506-511,共6页
目的总结以假性Bartter综合征(pseudo-Bartter syndrome,PBS)为主要表现的囊性纤维化(cystic fibrosis,CF)(CF-PBS)患儿的临床特征和基因变异,以提高对CF-PBS的认识。方法回顾性分析2018年1月—2023年8月在湖南省儿童医院确诊的3例CF-PB... 目的总结以假性Bartter综合征(pseudo-Bartter syndrome,PBS)为主要表现的囊性纤维化(cystic fibrosis,CF)(CF-PBS)患儿的临床特征和基因变异,以提高对CF-PBS的认识。方法回顾性分析2018年1月—2023年8月在湖南省儿童医院确诊的3例CF-PBS患儿的临床资料并文献复习。结果3例患儿均在婴儿期起病,入院后检验示低钠、低钾、低氯血症和代谢性碱中毒,基因检测示CFTR基因存在复合杂合变异,均诊断为CF。文献检索33例CF-PBS中国患儿,起病年龄和诊断年龄分别为1~36月龄、3~144月龄,伴有反复呼吸道感染或持续肺炎29例(88%)、营养不良26例(79%)、发育落后23例(70%)、胰腺炎或可疑胰腺外分泌功能不全18例(55%);c.2909G>A是CFTR基因最常见的变异位点,等位基因变异频率为23%(15/66)。结论CF早期无典型的呼吸道症状,对于反复出现的低钠、低钾、低氯血症和代谢性碱中毒的婴儿,特别是同时存在营养不良、发育落后,需警惕CF-PBS可能,应尽早进行CFTR基因检测协助诊断CF。 展开更多
关键词 囊性纤维化 假性Bartter综合征 CFTR基因 儿童
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Rapid, accurate and serotype independent pipeline for in silico epitope mapping of SARS-CoV-2 antigens: a combined machine learning and Chou’s pseudo amino acid composition method
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作者 Arash Rahmani Mokhtar Nosrati 《Medical Data Mining》 2023年第3期1-9,共9页
Here,a new integrated machine learning and Chou’s pseudo amino acid composition method has been proposed for in silico epitope mapping of severe acute respiratorysyndrome-like coronavirus antigens.For this,a training... Here,a new integrated machine learning and Chou’s pseudo amino acid composition method has been proposed for in silico epitope mapping of severe acute respiratorysyndrome-like coronavirus antigens.For this,a training dataset including 266 linear B-cell epitopes,1,267 T-cell epitopes and 1,280 non-epitopes were prepared.The epitope sequences were then converted to numerical vectors using Chou’s pseudo amino acid composition method.The vectors were then introduced to the support vector machine,random forest,artificial neural network,and K-nearest neighbor algorithms for the classification process.The algorithm with the highest performance was selected for the epitope mapping procedure.Based on the obtained results,the random forest algorithm was the most accurate classifier with an accuracy of 0.934 followed by K-nearest neighbor,artificial neural network,and support vector machine respectively.Furthermore,the efficacies of predicted epitopes by the trained random forest algorithm were assessed through their antigenicity potential as well as affinity to human B cell receptor and MHC-I/II alleles using the VaxiJen score and molecular docking,respectively.It was also clear that the predicted epitopes especially the B-cell epitopes had high antigenicity potentials and good affinities to the protein targets.According to the results,the suggested method can be considered for developing specific epitope predictor software as well as an accelerator pipeline for designing serotype independent vaccine against the virus. 展开更多
关键词 severe acute respiratory syndrome-like coronavirus machine learning Chou’s pseudo amino acid composition epitope based vaccine
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单跨两层含减震外挂墙板装配式混凝土框架拟静力试验研究 被引量:2
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作者 种迅 霍璞 +4 位作者 沙慧玲 蒋庆 李浩然 侯林兵 冯玉龙 《工程力学》 EI CSCD 北大核心 2024年第1期114-123,共10页
该文在对一个含减震外挂墙板平面框架(简称减震结构)以及一个作为对比的纯框架(简称抗震结构)进行混合试验的基础上,进一步对其单跨2层试验子结构进行了拟静力试验,研究了两结构在水平地震作用下的受力过程、损伤模式及减震外挂墙板对... 该文在对一个含减震外挂墙板平面框架(简称减震结构)以及一个作为对比的纯框架(简称抗震结构)进行混合试验的基础上,进一步对其单跨2层试验子结构进行了拟静力试验,研究了两结构在水平地震作用下的受力过程、损伤模式及减震外挂墙板对主体结构抗震性能的影响。研究结果表明:减震结构和抗震结构的破坏机制均为梁端和柱底出现塑性铰的梁铰机制,减震外挂墙板未改变主体结构的破坏模式;减震结构中,在最大层间位移角达到1/55之前,消能器呈预期的履带式滚动变形,此后由于外挂墙板的面内转动变形,消能器水平剪切变形值增加不大,且圆弧段产生明显变形;试验过程中减震外挂墙板未出现裂缝;墙板与框架间上部线连接处裂缝宽度较小,连接钢筋应变也较小,表明连接可靠;两试件均具有较好的变形能力和耗能能力;在相同位移级别下,减震结构的刚度、极限承载力和耗能能力均更好。 展开更多
关键词 减震外挂墙板 装配式混凝土框架 U型钢板消能器 拟静力试验 抗震性能
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Sub-Differential Characterizations of Non-Smooth Lower Semi-Continuous Pseudo-Convex Functions on Real Banach Spaces
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作者 Akachukwu Offia Ugochukwu Osisiogu +4 位作者 Theresa Efor Friday Oyakhire Monday Ekhator Friday Nkume Sunday Aloke 《Open Journal of Optimization》 2023年第3期99-108,共10页
In this paper, we characterize lower semi-continuous pseudo-convex functions f : X → R ∪ {+ ∞} on convex subset of real Banach spaces K  ⊂ X with respect to the pseudo-monotonicity of its Clarke-Rockafellar Su... In this paper, we characterize lower semi-continuous pseudo-convex functions f : X → R ∪ {+ ∞} on convex subset of real Banach spaces K  ⊂ X with respect to the pseudo-monotonicity of its Clarke-Rockafellar Sub-differential. We extend the results on the characterizations of non-smooth convex functions f : X → R ∪ {+ ∞} on convex subset of real Banach spaces K  ⊂ X with respect to the monotonicity of its sub-differentials to the lower semi-continuous pseudo-convex functions on real Banach spaces. 展开更多
关键词 Real Banach Spaces pseudo-Convex Functions pseudo-Monotone Maps Sub-Differentials Lower Semi-Continuous Functions and Approximate Mean Value Inequality
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选择置信伪标签的迁移学习
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作者 滕少华 周德根 +1 位作者 滕璐瑶 张巍 《江西师范大学学报(自然科学版)》 CAS 北大核心 2024年第1期31-44,共14页
域适应旨在将标签丰富的源域知识迁移到无标签的目标域.选择性伪标签和标签传播都是域适应的常用方法.然而传统的选择性伪标签以最大类的预测概率标记样本,忽视了其他概率;而且传统的标签传播同等对待不同置信度的标签,这可能导致错误标... 域适应旨在将标签丰富的源域知识迁移到无标签的目标域.选择性伪标签和标签传播都是域适应的常用方法.然而传统的选择性伪标签以最大类的预测概率标记样本,忽视了其他概率;而且传统的标签传播同等对待不同置信度的标签,这可能导致错误标签.因此,该文提出了一种选择置信伪标签(TL-SCP)的迁移学习.首先,在评估伪标签的置信度时兼顾了最大类的预测概率和其他类预测概率;其次,在标签传播过程中尽量保留高置信度标签,并据此指导低置信度标签的更新,借此减少错误标签传播;最后,在4个基准数据集上进行的大量实验验证了提出的模型(TL-SCP)优于现有的模型. 展开更多
关键词 置信伪标签 域适应 伪标签 迁移学习 标签传播
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Boundedness for Multilinear Operators of Pseudo-Differential Operators
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作者 Jiasheng Zeng Rongping Chen +2 位作者 Jiangang Liu Xiaojing Wang Chunsheng Liu 《Advances in Pure Mathematics》 2023年第7期449-462,共14页
In this paper, we establish a sharp function estimate for the multilinear integral operators associated to the pseudo-differential operators. As the application, we obtain the L<sup>p</sup> (1 p norm ... In this paper, we establish a sharp function estimate for the multilinear integral operators associated to the pseudo-differential operators. As the application, we obtain the L<sup>p</sup> (1 p norm inequalities for the multilinear operators. 展开更多
关键词 Multilinear Operator pseudo-Differential Operator Sharp Function Estimate BMO
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预制拼装铁路重力式桥墩的抗震性能研究 被引量:1
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作者 丁明波 邹诚 +3 位作者 鲁锦华 李竞宇 邢斯宇 王芳军 《中国铁道科学》 EI CAS CSCD 北大核心 2024年第1期79-88,共10页
为适应中国铁路建设向高烈度震区快速发展的需要,解决传统预制拼装桥墩墩柱及承台连接位置薄弱等问题,提出一种灌浆波纹管连接的模块化预制拼装桥墩体系,通过设置承台与墩身塑性区域共同浇筑及墩底局部无黏结段增强桥墩的抗震性能。制作... 为适应中国铁路建设向高烈度震区快速发展的需要,解决传统预制拼装桥墩墩柱及承台连接位置薄弱等问题,提出一种灌浆波纹管连接的模块化预制拼装桥墩体系,通过设置承台与墩身塑性区域共同浇筑及墩底局部无黏结段增强桥墩的抗震性能。制作1个局部无黏结整体现浇铁路重力式桥墩模型和1个局部无黏结预制拼装铁路重力式桥墩模型开展拟静力试验,并结合有限元分析,进行预制拼装铁路重力式桥墩抗震性能研究。结果表明:局部无黏结预制拼装桥墩整体连接性能稳定,可通过墩底塑性区域破坏与墩身及节段间的摇摆实现共同消能,其破坏模式表现为墩底塑性区域的弯曲破坏,未发生破坏位置转移现象;局部无黏结预制拼装桥墩等效塑性区域高度比整体现浇桥墩降低,抗侧向水平承载力与耗能能力提升显著,位移延性能力良好,可适应更大加载位移,最终累积耗能增长64.3%;结构接缝位置连接稳定可靠,同等加载位移下等效刚度基本一致,抗震性能得到明显提高;预制节段划分对预制拼装铁路重力式桥墩抗震性能的影响不大。 展开更多
关键词 铁路 重力式桥墩 预制 拼装 局部无黏结 抗震性能 破坏模式 拟静力试验
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基于虚拟激励法的磁浮车桥耦合系统随机振动分析
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作者 刘伟 赵春发 +2 位作者 娄会彬 冯洋 彭也也 《西南交通大学学报》 EI CSCD 北大核心 2024年第4期823-831,共9页
为探讨随机轨道不平顺作用下中低速磁浮列车和桥梁的动力响应,将虚拟激励法引入磁浮车桥振动分析中,提出中低速磁浮车辆-悬浮控制系统-桥梁耦合系统随机振动分析方法.将中低速磁浮列车简化为弹簧阻尼器连接的多刚体,悬浮系统中电流使用... 为探讨随机轨道不平顺作用下中低速磁浮列车和桥梁的动力响应,将虚拟激励法引入磁浮车桥振动分析中,提出中低速磁浮车辆-悬浮控制系统-桥梁耦合系统随机振动分析方法.将中低速磁浮列车简化为弹簧阻尼器连接的多刚体,悬浮系统中电流使用比例-微分(PD)控制方法进行主动控制,采用有限元方法对桥梁进行建模,将随机轨道不平顺转换为一系列简谐波构成的虚拟激励;编制中低速磁浮车桥动力系统随机振动分析程序,自动生成系统随机振动方程,利用分离迭代方法对磁浮车辆控制方程和桥梁动力方程进行求解计算.研究结果表明:虚拟激励法能够高效计算中低速磁浮车桥系统随机动力响应,其计算效率约为蒙特卡洛方法的1/11,基于虚拟激励法能够获得中低速磁浮车桥动力系统均值、标准差和时变功率谱密度等统计结果. 展开更多
关键词 磁浮车辆 车桥相互作用 随机振动 虚拟激励法
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电弧喷涂Zn-Al伪合金涂层耐腐蚀性能研究进展
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作者 张敏 丁玉萍 +1 位作者 王淞 刘施峰 《表面技术》 EI CAS CSCD 北大核心 2024年第10期1-15,共15页
通过在钢基体表面制备涂层可以很好地延长钢铁材料的服役时间,减少因腐蚀造成的重大事故和人员伤亡。相较于传统的纯Zn涂层、纯Al涂层以及Zn-Al合金涂层,Zn-Al伪合金涂层能够为基体材料提供长久有效的腐蚀防护,在钢铁材料的腐蚀防护中... 通过在钢基体表面制备涂层可以很好地延长钢铁材料的服役时间,减少因腐蚀造成的重大事故和人员伤亡。相较于传统的纯Zn涂层、纯Al涂层以及Zn-Al合金涂层,Zn-Al伪合金涂层能够为基体材料提供长久有效的腐蚀防护,在钢铁材料的腐蚀防护中具有巨大的应用潜力。简述了Zn-Al伪合金涂层电弧喷涂制备工艺的特点;介绍了Zn、Al、Zn-Al合金及Zn-Al伪合金涂层在模拟海洋环境下的腐蚀防护原理;在此基础上从组分、喷涂工艺参数(喷涂距离、喷涂电流和喷涂电压)、元素掺杂(Mg、Si及Re)及后处理工艺(封孔、激光重熔)等角度,论述了其对Zn-Al伪合金涂层耐蚀性的影响;讨论了Zn-Al伪合金涂层防腐体系在桥梁、海洋钢结构件、地下运输管道中的应用现状;最后总结了目前研究工作中存在的挑战,提出了电弧喷涂Zn-Al伪合金涂层尚需深入研究的重点问题,为提高钢铁材料使用寿命提供了参考。 展开更多
关键词 Zn-Al伪合金 电弧喷涂 涂层 耐蚀性
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基于虚拟激励法的大跨度桥梁非平稳随机振动分析闭合解
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作者 赵岩 张亚辉 林家浩 《计算力学学报》 CAS CSCD 北大核心 2024年第1期202-208,共7页
针对大跨度结构考虑地面空间运动的非一致地震响应分析问题,结合虚拟激励法,应用傅里叶分析建立了结构非平稳随机振动响应演变功率谱分析的频域方法。建立的方法完全基于频域执行,给出了响应演变功率谱的闭合解表达式。由于实现了确定... 针对大跨度结构考虑地面空间运动的非一致地震响应分析问题,结合虚拟激励法,应用傅里叶分析建立了结构非平稳随机振动响应演变功率谱分析的频域方法。建立的方法完全基于频域执行,给出了响应演变功率谱的闭合解表达式。由于实现了确定性调制过程与随机过程的有效分离,应用离散傅里叶变换进行计算不需要较高的采样分析频率就可以获得较好精度的数值结果。数值算例研究了某斜拉桥的考虑地面运动空间效应非平稳随机地震响应,与通常时频分析方法进行对比,验证了本文频域方法的正确性和有效性。 展开更多
关键词 多点输入 非平稳 随机振动 虚拟激励法 闭合解
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高阶伪随机信号在对地通讯中的应用
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作者 杨洋 王林 +2 位作者 张衡 李小平 黄敏 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2024年第8期3173-3183,共11页
对地通讯(Through-The-Earth Communication,TTEC)以大地为传播介质,使用低频电磁波来传输信息,在地下工程建设调度、预警、救援中有着重要作用.高阶伪随机信号可同时包含数十个频率,其具有易于实现、频率可控、抗干扰能力强的特点,有... 对地通讯(Through-The-Earth Communication,TTEC)以大地为传播介质,使用低频电磁波来传输信息,在地下工程建设调度、预警、救援中有着重要作用.高阶伪随机信号可同时包含数十个频率,其具有易于实现、频率可控、抗干扰能力强的特点,有应用于对地通讯的潜力和价值.鉴于此,本文提出一种基于高阶伪随机信号的对地通讯新方法.通过在高阶伪随机信号中设置静态频组和动态频组,利用静态频组保证多个主频的平均幅值以维持发射稳定性,利用动态频组对通讯信息编码,传输有效信息.在实际工作时,发射端将通讯信息编码转换为高阶伪随机信号,利用长导线源向大地发射,接收端利用电极或者线圈接收电磁信号,经模式识别、时频变换、反向解码转换为有效通讯信息.通过仿真测试和在济南市某煤矿井下试验,完成有效通讯信息的发射、传输、解译等过程,实现了基于高阶伪随机信号的对地通讯方法,验证了方法在地下工程通讯的可行性和可靠性. 展开更多
关键词 对地通讯 高阶伪随机信号 多频 信号编码 信号解码
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