期刊文献+
共找到9,769篇文章
< 1 2 250 >
每页显示 20 50 100
A digital quartz resonant accelerometer with low temperature drift
1
作者 CHEN Fubin ZHANG Haoyu +1 位作者 YANG Min ZHU Jialin 《中国惯性技术学报》 北大核心 2025年第3期273-278,共6页
In order to suppress the influence of temperature changes on the performance of accelerometers,a digital quartz resonant accelerometer with low temperature drift is developed using a quartz resonator cluster as a tran... In order to suppress the influence of temperature changes on the performance of accelerometers,a digital quartz resonant accelerometer with low temperature drift is developed using a quartz resonator cluster as a transducer element.In addition,a digital intellectual property(IP) is designed in FPGA to achieve signal processing and fusion of integrated resonators.A testing system for digital quartz resonant accelerometers is established to characterize the performance under different conditions.The scale factor of the accelerometer prototype reaches 3561.63 Hz/g in the range of -1 g to +1 g,and 3542.5 Hz/g in the range of-10 g to+10 g.In different measurement ranges,the linear correlation coefficient R~2 of the accelerometer achieves greater than 0.998.The temperature drift of the accelerometer prototype is tested using a constant temperature test chamber,with a temperature change from -20℃ to 80℃.After temperature-drift compensation,the zero bias temperature coefficient falls to 0.08 mg/℃,and the scale factor temperature coefficient is 65.43 ppm/℃.The experimental results show that the digital quartz resonant accelerometer exhibits excellent sensitivity and low temperature drift. 展开更多
关键词 quartz resonant accelerometer temperature drift scale factor signal fusion
在线阅读 下载PDF
DRIFTS与随钻地层孔隙压力监测协同耦合的复杂超压判别方法
2
作者 邱万军 胡益涛 印森林 《录井工程》 2025年第3期58-64,共7页
针对传统地层孔隙压力监测方法在生烃增压作用较强地层中存在的不足,提出一种基于地层孔隙压力监测技术与漫反射红外傅里叶变换光谱(DRIFTS)技术协同耦合的新型地层压力趋势判别方法。在随钻地层压力监测过程中,利用测录井参数(如dc指... 针对传统地层孔隙压力监测方法在生烃增压作用较强地层中存在的不足,提出一种基于地层孔隙压力监测技术与漫反射红外傅里叶变换光谱(DRIFTS)技术协同耦合的新型地层压力趋势判别方法。在随钻地层压力监测过程中,利用测录井参数(如dc指数、声波时差、电阻率等)偏离正常趋势线的特征识别异常压力地层,同时引入DRIFTS技术快速分析岩屑样品的矿物成分、总有机碳含量(TOC)及镜质体反射率(R_(o)),揭示有机质生烃增压效应。以珠江口盆地文昌A凹陷B井为例,通过地层压力技术与DRIFTS技术的协同耦合构建图板,进而识别出该井4350 m为生烃增压拐点,发现地层孔隙压力上升趋势与TOC、R_(o)的升高趋势高度一致,验证了协同判别方法的有效性。与传统模型相比,该方法能够同时量化欠压实与生烃作用的超压贡献,显著提高了复杂超压机制地层的压力判别精度。DRIFTS技术对矿物与有机质的高分辨率分析能力,与随钻压力监测数据的动态结合,为钻井工程提供了更可靠的地层压力预测与安全指导,具有重要现场应用价值。 展开更多
关键词 地层压力 随钻监测技术 driftS 技术 协同耦合 生烃增压 珠江口盆地
在线阅读 下载PDF
N⁃DD: New Approach for Drift Detection Based on Neutrosophic Support Vector Machine
3
作者 Rania Lutfi 《Journal of Harbin Institute of Technology(New Series)》 2025年第3期82-90,共9页
Many real⁃world machine learning applications face the challenge of dealing with changing data over time,known as concept drift,and the issue of data indeterminacy,where all the true labels available are unrealistic.T... Many real⁃world machine learning applications face the challenge of dealing with changing data over time,known as concept drift,and the issue of data indeterminacy,where all the true labels available are unrealistic.This can lead to a decrease in the accuracy of the prediction models.The aim of this study is to introduce a new approach for detecting drift,which is based on neutrosophic set theory.This approach takes into account uncertainty in the prediction model and is able to handle indeterminate information,considering its impact on the models performance.The proposed method reads data into windows and calculates a set of values based on the concept of neutrosophic membership.These values are then used in the Neutrosophic Support Vector Machine(N⁃SVM).To address the issue of indeterminate true label data,the values issued by N⁃SVM are expressed as entropy and used as input for the ADWIN(Adaptive Windowing)change detector.When a drift is detected,the prediction model is retrained by including only the most recent instances with the original training data set.The proposed method gives promising results in terms of drift detection accuracy compared to the state of existing drift detection methods such as KSWIN,ADWIN,and DWM. 展开更多
关键词 drift detection indeterminate labels UNCERTAINTY neutrosophic set theory data stream
在线阅读 下载PDF
INEQUALITIES FOR EIGENVALUES OF POLYNOMIAL OPERATOR OF THE DRIFTING LAPLACIAN ON THE CIGAR SOLITON
4
作者 YUAN Yuan SUN He-jun 《数学杂志》 2025年第4期293-306,共14页
In this paper,we investigate the weighted Dirichlet eigenvalue problem of polynomial operator of the drifting Laplacian on the cigar soliton■as follows■where is a positive continuous function on,denotes the outward ... In this paper,we investigate the weighted Dirichlet eigenvalue problem of polynomial operator of the drifting Laplacian on the cigar soliton■as follows■where is a positive continuous function on,denotes the outward unit normal to the boundary,and are two nonnegative constants.We establish some universal inequalities for eigenvalues of this problem. 展开更多
关键词 drifting Laplacian Cigarsoliton EIGENVALUE
在线阅读 下载PDF
Cluster counting algorithm for the CEPC drift chamber using LSTM and DGCNN
5
作者 Zhe-Fei Tian Guang Zhao +7 位作者 Ling-Hui Wu Zhen-Yu Zhang Xiang Zhou Shui-Ting Xin Shuai-Yi Liu Gang Li Ming-Yi Dong Sheng-Sen Sun 《Nuclear Science and Techniques》 2025年第7期14-23,共10页
The particle identification(PID)of hadrons plays a crucial role in particle physics experiments,especially in flavor physics and jet tagging.The cluster counting method,which measures the number of primary ionizations... The particle identification(PID)of hadrons plays a crucial role in particle physics experiments,especially in flavor physics and jet tagging.The cluster counting method,which measures the number of primary ionizations in gaseous detectors,is a promising breakthrough in PID.However,developing an effective reconstruction algorithm for cluster counting remains challenging.To address this challenge,we propose a cluster counting algorithm based on long short-term memory and dynamic graph convolutional neural networks for the CEPC drift chamber.Experiments on Monte Carlo simulated samples demonstrate that our machine learning-based algorithm surpasses traditional methods.It improves the K/πseparation of PID by 10%,meeting the PID requirements of CEPC. 展开更多
关键词 Particle identification Cluster counting Machine learning drift chamber
在线阅读 下载PDF
Leveraging Safe and Secure AI for Predictive Maintenance of Mechanical Devices Using Incremental Learning and Drift Detection
6
作者 Prashanth B.S Manoj Kumar M.V. +1 位作者 Nasser Almuraqab Puneetha B.H 《Computers, Materials & Continua》 2025年第6期4979-4998,共20页
Ever since the research in machine learning gained traction in recent years,it has been employed to address challenges in a wide variety of domains,including mechanical devices.Most of the machine learning models are ... Ever since the research in machine learning gained traction in recent years,it has been employed to address challenges in a wide variety of domains,including mechanical devices.Most of the machine learning models are built on the assumption of a static learning environment,but in practical situations,the data generated by the process is dynamic.This evolution of the data is termed concept drift.This research paper presents an approach for predictingmechanical failure in real-time using incremental learning based on the statistically calculated parameters of mechanical equipment.The method proposed here is applicable to allmechanical devices that are susceptible to failure or operational degradation.The proposed method in this paper is equipped with the capacity to detect the drift in data generation and adaptation.The proposed approach evaluates the machine learning and deep learning models for their efficacy in handling the errors related to industrial machines due to their dynamic nature.It is observed that,in the settings without concept drift in the data,methods like SVM and Random Forest performed better compared to deep neural networks.However,this resulted in poor sensitivity for the smallest drift in the machine data reported as a drift.In this perspective,DNN generated the stable drift detection method;it reported an accuracy of 84%and an AUC of 0.87 while detecting only a single drift point,indicating the stability to performbetter in detecting and adapting to new data in the drifting environments under industrial measurement settings. 展开更多
关键词 Incremental learning drift detection real-time failure prediction deep neural network proactive machine health monitoring
在线阅读 下载PDF
A Fine-Grained Defect Prediction Method Based on Drift-Immune Graph Neural Networks
7
作者 Fengyu Yang Fa Zhong +1 位作者 Xiaohui Wei Guangdong Zeng 《Computers, Materials & Continua》 2025年第2期3563-3590,共28页
The primary goal of software defect prediction (SDP) is to pinpoint code modules that are likely to contain defects, thereby enabling software quality assurance teams to strategically allocate their resources and manp... The primary goal of software defect prediction (SDP) is to pinpoint code modules that are likely to contain defects, thereby enabling software quality assurance teams to strategically allocate their resources and manpower. Within-project defect prediction (WPDP) is a widely used method in SDP. Despite various improvements, current methods still face challenges such as coarse-grained prediction and ineffective handling of data drift due to differences in project distribution. To address these issues, we propose a fine-grained SDP method called DIDP (drift-immune defect prediction), based on drift-immune graph neural networks (DI-GNN). DIDP converts source code into graph representations and uses DI-GNN to mitigate data drift at the model level. It also analyses key statements leading to file defects for a more detailed SDP approach. We evaluated the performance of DIDP in WPDP by examining its file-level and statement-level accuracy compared to state-of-the-art methods, and by examining its cross-project prediction accuracy. The results of the experiment show that DIDP showed significant improvements in F1-score and Recall@Top20%LOC compared to existing methods, even with large software version changes. DIDP also performed well in cross-project SDP. Our study demonstrates that DIDP achieves impressive prediction results in WPDP, effectively mitigating data drift and accurately predicting defective files. Additionally, DIDP can rank the risk of statements in defective files, aiding developers and testers in identifying potential code issues. 展开更多
关键词 Software defect prediction data drift graph neural networks information bottleneck
在线阅读 下载PDF
Dynamic domain analysis for predicting concept drift in engineering AI-enabled software
8
作者 Murtuza Shahzad Hamed Barzamini +2 位作者 Joseph Wilson Hamed Alhoori Mona Rahimi 《Journal of Data and Information Science》 2025年第2期124-151,共28页
Purpose:This research addresses the challenge of concept drift in AI-enabled software,particularly within autonomous vehicle systems where concept drift in object recognition(like pedestrian detection)can lead to misc... Purpose:This research addresses the challenge of concept drift in AI-enabled software,particularly within autonomous vehicle systems where concept drift in object recognition(like pedestrian detection)can lead to misclassifications and safety risks.This study introduces a proactive framework to detect early signs of domain-specific concept drift by leveraging domain analysis and natural language processing techniques.This method is designed to help maintain the relevance of domain knowledge and prevent potential failures in AI systems due to evolving concept definitions.Design/methodology/approach:The proposed framework integrates natural language processing and image analysis to continuously update and monitor key domain concepts against evolving external data sources,such as social media and news.By identifying terms and features closely associated with core concepts,the system anticipates and flags significant changes.This was tested in the automotive domain on the pedestrian concept,where the framework was evaluated for its capacity to detect shifts in the recognition of pedestrians,particularly during events like Halloween and specific car accidents.Findings:The framework demonstrated an ability to detect shifts in the domain concept of pedestrians,as evidenced by contextual changes around major events.While it successfully identified pedestrian-related drift,the system’s accuracy varied when overlapping with larger social events.The results indicate the model’s potential to foresee relevant shifts before they impact autonomous systems,although further refinement is needed to handle high-impact concurrent events.Research limitations:This study focused on detecting concept drift in the pedestrian domain within autonomous vehicles,with results varying across domains.To assess generalizability,we tested the framework for airplane-related incidents and demonstrated adaptability.However,unpredictable events and data biases from social media and news may obscure domain-specific drifts.Further evaluation across diverse applications is needed to enhance robustness in evolving AI environments.Practical implications:The proactive detection of concept drift has significant implications for AI-driven domains,especially in safety-critical applications like autonomous driving.By identifying early signs of drift,this framework provides actionable insights for AI system updates,potentially reducing misclassification risks and enhancing public safety.Moreover,it enables timely interventions,reducing costly and labor-intensive retraining requirements by focusing only on the relevant aspects of evolving concepts.This method offers a streamlined approach for maintaining AI system performance in environments where domain knowledge rapidly changes.Originality/value:This study contributes a novel domain-agnostic framework that combines natural language processing with image analysis to predict concept drift early.This unique approach,which is focused on real-time data sources,offers an effective and scalable solution for addressing the evolving nature of domain-specific concepts in AI applications. 展开更多
关键词 AI-enable software system Concept drift detection Applied machine learning Autonomous vehicles Natural language processing
在线阅读 下载PDF
A Real-Time Deep Learning Approach for Electrocardiogram-Based Cardiovascular Disease Prediction with Adaptive Drift Detection and Generative Feature Replay
9
作者 Soumia Zertal Asma Saighi +2 位作者 Sofia Kouah Souham Meshoul Zakaria Laboudi 《Computer Modeling in Engineering & Sciences》 2025年第9期3737-3782,共46页
Cardiovascular diseases(CVDs)continue to present a leading cause ofmortalityworldwide,emphasizing the importance of early and accurate prediction.Electrocardiogram(ECG)signals,central to cardiac monitoring,have increa... Cardiovascular diseases(CVDs)continue to present a leading cause ofmortalityworldwide,emphasizing the importance of early and accurate prediction.Electrocardiogram(ECG)signals,central to cardiac monitoring,have increasingly been integratedwithDeep Learning(DL)for real-time prediction of CVDs.However,DL models are prone to performance degradation due to concept drift and to catastrophic forgetting.To address this issue,we propose a realtime CVDs prediction approach,referred to as ADWIN-GFR that combines Convolutional Neural Network(CNN)layers,for spatial feature extraction,with Gated Recurrent Units(GRU),for temporal modeling,alongside adaptive drift detection and mitigation mechanisms.The proposed approach integratesAdaptiveWindowing(ADWIN)for realtime concept drift detection,a fine-tuning strategy based on Generative Features Replay(GFR)to preserve previously acquired knowledge,and a dynamic replay buffer ensuring variance,diversity,and data distribution coverage.Extensive experiments conducted on the MIT-BIH arrhythmia dataset demonstrate that ADWIN-GFR outperforms standard fine-tuning techniques,achieving an average post-drift accuracy of 95.4%,amacro F1-score of 93.9%,and a remarkably low forgetting score of 0.9%.It also exhibits an average drift detection delay of 12 steps and achieves an adaptation gain of 17.2%.These findings underscore the potential of ADWIN-GFR for deployment in real-world cardiac monitoring systems,including wearable ECG devices and hospital-based patient monitoring platforms. 展开更多
关键词 Real-time cardiovascular disease prediction concept drift detection catastrophic forgetting fine-tuning electrocardiogram convolutional neural networks gated recurrent units adaptive windowing generative feature replay
在线阅读 下载PDF
Beam test results of the prototype of the multi wire drift chamber for the CSR external-target experiment
10
作者 Zhi Qin Zhou-Bo He +18 位作者 Zhe Cao Tao Chen Zhi Deng Li-Min Duan Dong Guo Rong-Jiang Hu Jie Kong Can-Wen Liu Peng Ma Tian-Lei Pu Yi Qian Xiang-Lun Wei Shi-Hai Wen Xiang-Jie Wen Jun-Wei Yan He-Run Yang Zuo-Qiao Yang Yu-Hong Yu Zhi-Gang Xiao 《Nuclear Science and Techniques》 2025年第4期171-180,共10页
A half-size prototype of the multi wire drift chamber for the cooling storage ring external-target experiment(CEE)was assembled and tested in the 350 MeV/u Kr+Fe reactions at the heavy-ion research facility in Lanzhou... A half-size prototype of the multi wire drift chamber for the cooling storage ring external-target experiment(CEE)was assembled and tested in the 350 MeV/u Kr+Fe reactions at the heavy-ion research facility in Lanzhou.The prototype consists of six sense layers,where the sense wires are stretched in three directions X,U,and V;meeting 0?,30?,and-30?,respectively,with respect to the vertical axis.The sensitive area of the prototype is 76 cm×76 cm.The amplified and shaped signals from the anode wires were digitized in a serial capacity array.When operating at a high voltage of 1500 V on the anode wires,the efficiency for each layer is greater than 95%.The tracking residual is approximately 301±2μm.This performance satisfies the requirements of CEE. 展开更多
关键词 Multi wire drift chamber(MWDC) CSR external-target experiment(CEE) Tracking
在线阅读 下载PDF
Concept Drift Detection and Adaptation Method for IoT Security Framework
11
作者 Yin Jie Xie Wenwei +2 位作者 Liang Guangjun Zhang Lanping Zhang Xixi 《China Communications》 2025年第12期137-147,共11页
With the gradual penetration of the internet of things(IoT)into all areas of life,the scale of IoT devices shows an explosive growth trend.The era of internet of everything is coming,and the important position of IoT ... With the gradual penetration of the internet of things(IoT)into all areas of life,the scale of IoT devices shows an explosive growth trend.The era of internet of everything is coming,and the important position of IoT security is becoming increasingly prominent.Due to the large number types of IoT devices,there may be different security vulnerabilities,and unknown attack forms and virus samples are appear.In other words,large number of IoT devices,large data volumes,and various attack forms pose a big challenge of malicious traffic identification.To solve these problems,this paper proposes a concept drift detection and adaptation(CDDA)method for IoT security framework.The AI model performance is evaluated by verifying the effectiveness of IoT traffic for data drift detection,so as to select the best AI model.The experimental test are given to confirm that the feasibility of the framework and the adaptive method in practice,and the effect on the performance of IoT traffic identification is also verified. 展开更多
关键词 concept drift detection and adaptive(CDDA)method IoT security malicious traffic identification
在线阅读 下载PDF
Data Analysis and Modeling of Fiber Optic Gyroscope Drift 被引量:17
12
作者 缪玲娟 张方生 +1 位作者 沈军 刘伟 《Journal of Beijing Institute of Technology》 EI CAS 2002年第1期50-55,共6页
A data gathering system is designed for the interferometric fiber optic gyroscope (IFOG) of land strapdown inertial system. IFOG is tested and the testing curve is given. The test data of IFOG are analyzed with Allan ... A data gathering system is designed for the interferometric fiber optic gyroscope (IFOG) of land strapdown inertial system. IFOG is tested and the testing curve is given. The test data of IFOG are analyzed with Allan variance method and each error coefficient is identified. Furthermore, a random drift error model for IFOG is built by the method of time series analysis. The conclusion provides supports for improving IFOG design and compensating for errors of IFOG in practice. 展开更多
关键词 fiber optic gyroscope random drift Allan variance MODELING
在线阅读 下载PDF
SO_2在CaCO_3颗粒表面转化的DRIFTS研究 被引量:17
13
作者 李雷 陈忠明 +2 位作者 丁杰 朱彤 张远航 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2004年第12期1556-1559,共4页
碳酸钙 (CaCO3 )是大气中矿物颗粒物的重要组分 ,其非均相大气化学行为很不清楚。利用原位漫反射红外傅里叶变换光谱 (DiffuseReflectanceInfraredFourierTransformSpectroscopy ,DRIFTS)研究了二氧化硫(SO2 )在CaCO3 颗粒物表面的转化... 碳酸钙 (CaCO3 )是大气中矿物颗粒物的重要组分 ,其非均相大气化学行为很不清楚。利用原位漫反射红外傅里叶变换光谱 (DiffuseReflectanceInfraredFourierTransformSpectroscopy ,DRIFTS)研究了二氧化硫(SO2 )在CaCO3 颗粒物表面的转化情况。通过比较不同条件下 ,亚硫酸盐和硫酸盐的原位光谱 ,探讨了SO2在CaCO3 表面氧化中臭氧 (O3 )所起的作用。结果表明 ,利用DRIFTS原位分析反应器研究CaCO3 表面硫酸盐的生成是可行的。在存在O3 条件下 ,SO2 在CaCO3 表面能够被氧化成硫酸盐 ,反应分为吸附和氧化两个步骤进行。 展开更多
关键词 CACO3 颗粒表面 非均相 矿物颗粒 二氧化硫(SO2) 碳酸钙 反应器 SO2 硫酸盐 颗粒物
在线阅读 下载PDF
高岭石/甲酰胺插层的Raman和DRIFT光谱 被引量:16
14
作者 王林江 吴大清 +3 位作者 袁鹏 林种玉 刁桂仪 彭金莲 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2002年第10期1948-1951,共4页
用 Raman和漫反射红外光谱研究高岭石
关键词 甲酰胺 高岭石 插层复合物 RAMAN光谱 DRIRFT光谱 插层反应机理 微结构
在线阅读 下载PDF
原位DRIFTS研究CH_4部分氧化和CO_2重整的耦合 被引量:5
15
作者 纪红兵 许建华 +1 位作者 谢俊锋 陈清林 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2008年第6期1246-1250,共5页
8%Ru-5%Ce/γ-Al2O3催化剂对于甲烷的低温活化具有较好的催化活性,在500℃下甲烷、二氧化碳和氧气的耦合反应中,吸热反应二氧化碳重整和放热反应甲烷部分氧化进行耦合强化,使得耦合反应中的甲烷转化率为38.8%。用原位漫反射傅里叶红外... 8%Ru-5%Ce/γ-Al2O3催化剂对于甲烷的低温活化具有较好的催化活性,在500℃下甲烷、二氧化碳和氧气的耦合反应中,吸热反应二氧化碳重整和放热反应甲烷部分氧化进行耦合强化,使得耦合反应中的甲烷转化率为38.8%。用原位漫反射傅里叶红外光谱法对钌系催化剂耦合甲烷部分氧化和二氧化碳重整反应体系机理进行研究。CO在8%Ru-5%Ce/γ-Al2O3上吸附,表明CO在催化剂表面上波数为2 167 cm-1(2 118 cm-1)和2031 cm-1(2 034 cm-1)处形成孪生态Ru(CO)2和Ce(CO)2吸附物种,而且高温下CO吸附物种很容易从催化剂表面脱附出来。原位漫反射红外实验结果表明甲烷部分氧化反应时催化剂表面上有吸附物种碳酸根、甲酰基(甲酸盐)和一氧化碳的形成,其中表面的甲酰基和甲酸盐物种是甲烷部分氧化反应的主要活性中间物,这些中间活性中间体由甲烷吸附态CHx和催化剂表面的氧吸附态结合而形成的,随后这种中间物种再分解为CO产物;甲烷和二氧化碳重整反应时没有新的吸附物种产生,由此提出重整反应的机理是吸附态的甲烷和二氧化碳在催化剂活性中心上进行活化解离而生成合成气;甲烷、二氧化碳和氧气耦合反应过程中出现新的羟基物种(桥式羟基Ru-(OH)2),耦合反应机理复杂可能是由部分氧化和重整两类反应机理的复合,其中桥式羟基Ru-(OH)2参与了反应的进行。 展开更多
关键词 原位漫反射红外光谱 耦合反应 反应机理
在线阅读 下载PDF
利用Excel实现快速整理CG-5型重力仪静态试验数据和计算漂移常量DRIFT 被引量:2
16
作者 高鹏 李增涛 +2 位作者 于峰丹 张旭 刘生荣 《物探与化探》 CAS 北大核心 2019年第1期209-214,共6页
重力仪静态试验是重力勘探工作开始之前对仪器性能检查的必要环节,由于原理简单,其数据整理常不被人们重视,没有系统的方法,但整理的计算过程却又繁琐复杂,初学者在面对大量数据和多重目标时或顾此失彼,或重复计算,往往要耗费较多的工... 重力仪静态试验是重力勘探工作开始之前对仪器性能检查的必要环节,由于原理简单,其数据整理常不被人们重视,没有系统的方法,但整理的计算过程却又繁琐复杂,初学者在面对大量数据和多重目标时或顾此失彼,或重复计算,往往要耗费较多的工作时间。Excel电子表格具有强大的数学计算、图形显示功能,且应用广泛,易于操作,可系统整理CG-5型重力仪静态试验的原始观测记录,快速获取静态试验数据表、零点位移曲线及其拟合直线图等直观要素,同时计算得到静态零点位移曲线与直线偏差、平均零点位移率等结果参数,Excel的散点图趋势线功能也改进了静态零点位移校正参数漂移常量DRIFT的计算方法与准确度。这种静态试验数据的整理方法具有快速、准确和直观的优点。 展开更多
关键词 CG-5型重力仪 EXCEL 静态试验 数据整理 drift
在线阅读 下载PDF
Insitu DRIFTS研究NO在Cu-ZSM-5上的表面吸附及选择性催化还原 被引量:7
17
作者 张平 王乐夫 陈永亨 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2007年第6期1102-1105,共4页
Cu-ZSM-5分子筛催化剂选择性催化还原NO具有较好的低温活性,在613K时NO还原成N2的转化率达70·6%。原位漫反射红外光谱(Insitu DRIFTS)是研究催化剂表面吸附物种及催化机理的重要方法,应用该方法在298~773K范围原位考察了以C3H6为... Cu-ZSM-5分子筛催化剂选择性催化还原NO具有较好的低温活性,在613K时NO还原成N2的转化率达70·6%。原位漫反射红外光谱(Insitu DRIFTS)是研究催化剂表面吸附物种及催化机理的重要方法,应用该方法在298~773K范围原位考察了以C3H6为还原剂及富O2条件下,NO在Cu-ZSM-5催化剂上的表面吸附及选择性催化还原。认为NO在Cu-ZSM-5催化剂上还原为N2的过程中,NO以一系列NOx吸附态形式与丙稀的活化物种(CxHy或CxHyOz)反应,生成有机中间体,再进一步反应,最终生成N2。有机中间体存在一个明显的从有机胺物种到腈(或—CN)再到有机氮氧物种(R—NO2或R—ONO)的过程,催化剂表面形成有机中间物种是关键步骤,Cu的作用是促进NOx形成,O2的作用是促进C3H6活化,并且是有效产生有机-氮氧化物不可缺少的条件。 展开更多
关键词 原位漫反射红外光谱 Cu-ZSM-5催化剂 NO 表面吸附 选择性催化还原 反应机理
在线阅读 下载PDF
(VO)_2P_2O_7催化剂上正丁烷选择氧化反应路径的原位瞬态DRIFTS研究 被引量:4
18
作者 梁日忠 李英霞 +1 位作者 李成岳 陈标华 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2004年第11期1309-1314,共6页
在钒磷复合氧化物(VO)2P2O7催化剂上,运用脉冲反应和反应物组成序贯切换的瞬态反应技术,对正丁烷和C4烯烃(1丁烯、1,3丁二烯)选择氧化制顺酐过程进行了瞬态原位DRIFTS研究,考察了正丁烷选择氧化反应体系的反应网络和基元过程序列结构。... 在钒磷复合氧化物(VO)2P2O7催化剂上,运用脉冲反应和反应物组成序贯切换的瞬态反应技术,对正丁烷和C4烯烃(1丁烯、1,3丁二烯)选择氧化制顺酐过程进行了瞬态原位DRIFTS研究,考察了正丁烷选择氧化反应体系的反应网络和基元过程序列结构。获得了含羰基的非环状饱和与不饱和物种都可能是正丁烷选择氧化制顺酐过程的中间物的证据,在1丁烯和1,3丁二烯的原位瞬态DRIFTS研究中检测到了呋喃。推断中间物呋喃在生成顺酐前可能经历了开环形成含羰基的非环状不饱和物种的过程。基于实验结果及与文献的比较,提出了正丁烷在VPO催化剂上选择氧化可能的反应路径。 展开更多
关键词 正丁烷 选择氧化 顺酐 1-丁烯 反应路径 催化剂 丁二烯 脉冲反应 呋喃 复合氧化物
在线阅读 下载PDF
新概念多模态航行器翼板参数对各模态航行性能影响
19
作者 陈云赛 逄浩震 +2 位作者 姜清华 王奥博 张栋 《哈尔滨工程大学学报》 北大核心 2026年第1期193-202,共10页
为探究不同折叠翼参数对航行器性能的影响,本文提出一种新概念多模态航行器,可实现水面漂航太阳能补充、水下滑翔以及螺旋桨推进等功能,并通过折叠翼形态的改变实现不同模态的转换,从而满足不同剖面的水下探测需求。建立不同翼展的水动... 为探究不同折叠翼参数对航行器性能的影响,本文提出一种新概念多模态航行器,可实现水面漂航太阳能补充、水下滑翔以及螺旋桨推进等功能,并通过折叠翼形态的改变实现不同模态的转换,从而满足不同剖面的水下探测需求。建立不同翼展的水动力模型,并通过流场分析解释水动力差异的原因。展长增大引起流场变化和湿表面积增加,导致推进模态航行器阻力的增大;在漂航模态航行器受到波浪的竖向作用力随展长增大而增大,纵摇角度随展长增大而减小;滑翔模态航行器的最大升阻比随展长的增大而增大,最大升阻比可达4.69,拥有更好的水动力性能。研究结果有助于提升对折叠翼附体的理解,并为新概念航行器的设计提供一定理论指导。 展开更多
关键词 多模态航行器 水动力性能 流场分析 滑翔机 折叠翼 升阻比 漂航 展长
在线阅读 下载PDF
基于贝叶斯网络的百年混凝土框架结构损伤评估
20
作者 刘卉 王征 +2 位作者 刘明 杨昕天 刘杰 《地震研究》 北大核心 2026年第2期334-343,共10页
为评估百年混凝土框架结构抗震性能,利用Netica软件构建自学习贝叶斯网络模型,对混凝土框架结构的损伤程度进行评估。该模型在碳化时间(t)为50 a和100 a的情况下,以层间位移角限值等级(Level)为评估标准,研究了地震动峰值加速度(PGA)、... 为评估百年混凝土框架结构抗震性能,利用Netica软件构建自学习贝叶斯网络模型,对混凝土框架结构的损伤程度进行评估。该模型在碳化时间(t)为50 a和100 a的情况下,以层间位移角限值等级(Level)为评估标准,研究了地震动峰值加速度(PGA)、地震作用次数(n)、结构高度(H)对混凝土框架结构抗震损伤的影响。模型以上述5个关键节点为变量,经数据处理、变量定义、网络结构与参数学习完成构建,运用概率推理和敏感性分析评估结构损伤概率。结果表明:①在多遇地震下,建筑物小震不坏标准可沿用现有规范。但在基本和罕遇地震下,百年建筑需加强中震可修、大震不倒的构造措施。②以H为变量时,现有抗震设防规律对百年建筑适用,结构破坏模式不变,但需考虑建筑高度对设计优化的影响。③重复地震对轻微破坏无显著影响,中等破坏随地震次数增加逐渐减弱,严重破坏先升后降,完全破坏概率急剧降低,显示累积地震损伤的非线性特征。 展开更多
关键词 自学习贝叶斯网络 百年混凝土结构 层间位移角 地震累积损伤 抗震性能评估
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部