期刊文献+
共找到13,333篇文章
< 1 2 250 >
每页显示 20 50 100
Pseudo channel:time embedding for motor imagery decoding
1
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
下载PDF
Long‐life lithium batteries enabled by a pseudo‐oversaturated electrolyte
2
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
下载PDF
Laboratory Implementation of Direct Torque Controller based Speed Loop Pseudo Derivative Feedforward Controller for PMSM Drive
3
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)
下载PDF
Pseudo S-Asymptotically(ω,c)-Periodic Solutions to Fractional Differential Equations of Sobolev Type
4
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
下载PDF
IgG4 Coronary Arteritis Presenting as a Cardiac Pseudo-Tumour
5
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
下载PDF
Pseudo-Semi-Overlap Functions-Based Fuzzy Rough Sets Applied to Image Edge Extraction
6
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
下载PDF
Acute Colonic Pseudo-Obstruction (ACPO): An Expanding Colon with Unusual Risk Factors
7
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
下载PDF
Does sevoflurane sedation in pediatric patients lead to“pseudo”leptomeningeal enhancement in the brain on 3 Tesla magnetic resonance imaging? 被引量:1
8
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
下载PDF
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
9
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
下载PDF
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
10
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
下载PDF
2021-2023年河南部分地区猪场猪瘟、猪繁殖与呼吸综合征和猪伪狂犬病抗体检测与分析 被引量:1
11
作者 王军 韩亚楠 +2 位作者 李月勤 张利卫 彭永帅 《动物医学进展》 北大核心 2024年第10期68-71,共4页
为了解河南省猪场主要病毒性疾病抗体水平,于2021-2023年共采集8014份血清样品,采用酶联免疫吸附试验(ELISA)对所采集的样品进行猪瘟病毒(CSFV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪伪狂犬病病毒gE(PRV-gE)、猪伪狂犬病病毒gB(PRV-gB)... 为了解河南省猪场主要病毒性疾病抗体水平,于2021-2023年共采集8014份血清样品,采用酶联免疫吸附试验(ELISA)对所采集的样品进行猪瘟病毒(CSFV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪伪狂犬病病毒gE(PRV-gE)、猪伪狂犬病病毒gB(PRV-gB)的抗体水平进行检测。结果显示,CSFV抗体的总阳性率为85.70%(6868/8014),PRRSV抗体的总阳性率为81.83%(6558/8014),PRV-gE抗体的总阳性率为11.08%(888/8014),PRV-gB抗体的总阳性率为83.10%(6660/8014)。研究表明,CSFV总体疫苗免疫抗体水平良好,能够有效地控制该病在猪场的发生与流行,但猪群仍存在PRRSV和PRV的感染风险,需要完善免疫方案、加强防控。研究结果可为猪场制定合理的免疫程序提供参考,促进养猪行业的健康发展。 展开更多
关键词 猪瘟 猪繁殖与呼吸综合征 猪伪狂犬病 抗体 检测
下载PDF
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:3
12
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
下载PDF
基于频率响应与图像特征提取的动车组变压器绕组状态诊断方法研究 被引量:1
13
作者 郭蕾 蔡育宏 +3 位作者 张俊 赵晨 王东阳 周利军 《铁道学报》 EI CAS CSCD 北大核心 2024年第4期47-56,共10页
动车组变压器是保障高速铁路稳定运行的核心设备,频率响应法是目前检测变压器绕组状态的有效方法。为提升车载变压器绕组状态诊断的准确性,结合暂态信号与频率响应法提出基于频率响应与图像特征提取的动车组变压器绕组状态诊断方法。搭... 动车组变压器是保障高速铁路稳定运行的核心设备,频率响应法是目前检测变压器绕组状态的有效方法。为提升车载变压器绕组状态诊断的准确性,结合暂态信号与频率响应法提出基于频率响应与图像特征提取的动车组变压器绕组状态诊断方法。搭建试验车载变压器绕组故障模拟平台,获取不同故障类型和故障位置的频响曲线,利用类Gram矩阵结合幅频和相频曲线信息,再利用密度分层法转换为伪彩色图,提取对应的灰度共生矩阵和灰度差分矩阵特征值,根据鹈鹕优化支持向量机方法对绕组故障进行诊断。试验结果表明:车载变压器绕组故障发生时,伪彩色图能够反映出故障信息,有利于图像分析和特征提取,采用基于频率响应与图像特征提取的动车组变压器绕组状态诊断方法能够识别车载变压器绕组的典型故障类型和位置。 展开更多
关键词 车载变压器 绕组故障 频率响应 伪彩色图 图像特征 支持向量机 鹈鹕算法
下载PDF
Sub-Differential Characterizations of Non-Smooth Lower Semi-Continuous Pseudo-Convex Functions on Real Banach Spaces
14
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
下载PDF
选择置信伪标签的迁移学习
15
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
下载PDF
政府购买公共服务承接主体选择的伪竞争风险识别与防范 被引量:2
16
作者 周义程 《扬州大学学报(人文社会科学版)》 2024年第3期43-54,共12页
政府购买公共服务要实现增进效率、提高质量和降低成本的购买目标,一个基本前提是在选择承接主体时存在较为充分的竞争。然而,立足主体、行为和方式维度的分析表明,潜在承接主体数量的有限性、关系型购买行为的常发性、对竞争运用的失... 政府购买公共服务要实现增进效率、提高质量和降低成本的购买目标,一个基本前提是在选择承接主体时存在较为充分的竞争。然而,立足主体、行为和方式维度的分析表明,潜在承接主体数量的有限性、关系型购买行为的常发性、对竞争运用的失当性等主客观因素时常引发承接主体选择时有意识的虚假竞争和无意识的形式化竞争等伪竞争风险。为了防范政府购买公共服务承接主体选择的伪竞争风险,需要从培育公共服务的承接主体、运用公共服务项目分解策略、探索公共服务供给的公私混合方式、通过准市场方式选择承接主体等方面针对性地设计风险防范进路。 展开更多
关键词 政府购买公共服务 承接主体选择 伪竞争风险 风险防范
下载PDF
Boundedness for Multilinear Operators of Pseudo-Differential Operators
17
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
下载PDF
数论函数方程Z(n^(2))=φe(SL(n^(2)))的可解性研究 被引量:1
18
作者 贺艳峰 李勰 +1 位作者 韩帆 薛媛媛 《湖北大学学报(自然科学版)》 CAS 2024年第5期667-674,共8页
运用初等与解析的方法,结合伪Smarandache函数、Smarandache LCM函数以及广义欧拉函数的基本性质,研究了当e∈{3,4}时,数论函数方程Z(n^(2))=φe(SL(n^(2)))的整数解情况,证明该方程无整数解。
关键词 伪SMARANDACHE函数 Smarandache LCM函数 广义欧拉函数
下载PDF
预制拼装铁路重力式桥墩的抗震性能研究 被引量:1
19
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
下载PDF
喷涂聚氨酯弹性体加固砌体墙抗震性能试验研究
20
作者 刘洋 刘阳 +2 位作者 田颖 黄群贤 张艺欣 《工程力学》 EI CSCD 北大核心 2024年第4期174-183,共10页
为提高村镇砖砌体墙结构抗震性能,采用喷涂聚氨酯技术对其进行加固。设计并制作了一片未加固砌体墙与两片加固后砌体墙,进行水平低周往复加载试验,主要研究加固形式(单面喷涂及双面喷涂)对砌体墙破坏形态、滞回特性、骨架曲线、变形性... 为提高村镇砖砌体墙结构抗震性能,采用喷涂聚氨酯技术对其进行加固。设计并制作了一片未加固砌体墙与两片加固后砌体墙,进行水平低周往复加载试验,主要研究加固形式(单面喷涂及双面喷涂)对砌体墙破坏形态、滞回特性、骨架曲线、变形性能、耗能能力和刚度退化等的影响。试验结果表明:喷涂聚氨酯弹性体可有效限制墙体开裂并延缓刚度退化,显著提高墙体的变形性能及耗能能力,而对墙体承载力及刚度影响有限。相较于单面喷涂加固,双面喷涂加固可更有效限制裂缝发展,维持墙体整体性,进一步提高墙体滞回性能、变形能力及耗能能力。 展开更多
关键词 砖砌体墙 聚氨酯弹性体 拟静力试验 抗震性能 加固
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部