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A subspace ensemble regression model based slow feature for soft sensing application 被引量:1
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作者 Qiong Jia Jun Cai +1 位作者 Xinyi Jiang Shaojun Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第12期3061-3069,共9页
A novel adaptive subspace ensemble slow feature regression model was developed for soft sensing application.Compared to traditional single models and random subspace models,the proposed method is improved in three asp... A novel adaptive subspace ensemble slow feature regression model was developed for soft sensing application.Compared to traditional single models and random subspace models,the proposed method is improved in three aspects.Firstly,sub-datasets are constructed through slow feature directions and variables in each subdatasets are selected according to the output related importance index.Then,an adaptive slow feature regression is presented for sub-models.Finally,a Bayesian inference strategy based on a slow feature analysis process that monitors statistics is developed for probabilistic combination.Two industrial examples were used to evaluate the proposed method. 展开更多
关键词 Soft sensing slow feature regression Subspace modeling Ensemble learning
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Randomized autoregressive dynamic slow feature analysis method for industrial process fault monitoring
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作者 Qingmin Xu Peng Li +3 位作者 Aimin Miao Xun Lang Hancheng Wang Chuangyan Yang 《Chinese Journal of Chemical Engineering》 2025年第7期298-314,共17页
Kernel-based slow feature analysis(SFA)methods have been successfully applied in the industrial process fault detection field.However,kernel-based SFA methods have high computational complexity as dealing with nonline... Kernel-based slow feature analysis(SFA)methods have been successfully applied in the industrial process fault detection field.However,kernel-based SFA methods have high computational complexity as dealing with nonlinearity,leading to delays in detecting time-varying data features.Additionally,the uncertain kernel function and kernel parameters limit the ability of the extracted features to express process characteristics,resulting in poor fault detection performance.To alleviate the above problems,a novel randomized auto-regressive dynamic slow feature analysis(RRDSFA)method is proposed to simultaneously monitor the operating point deviations and process dynamic faults,enabling real-time monitoring of data features in industrial processes.Firstly,the proposed Random Fourier mappingbased method achieves more effective nonlinear transformation,contrasting with the current kernelbased RDSFA algorithm that may lead to significant computational complexity.Secondly,a randomized RDSFA model is developed to extract nonlinear dynamic slow features.Furthermore,a Bayesian inference-based overall fault monitoring model including all RRDSFA sub-models is developed to overcome the randomness of random Fourier mapping.Finally,the superiority and effectiveness of the proposed monitoring method are demonstrated through a numerical case and a simulation of continuous stirred tank reactor. 展开更多
关键词 slow feature analysis Random Fourier mapping Bayesian Inference Autoregressive dynamic modeling CSTR Fault detection
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Coulomb stressing rate changes and seismicity dynamics associated with slow slip events in south-central Alaska
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作者 ShanShan Li XingLei Li Bing Xu 《Earth and Planetary Physics》 2025年第2期289-308,共20页
Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter ... Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap. 展开更多
关键词 slow slip events Coulomb stressing rate change seismicity rate change receiver fault rate–state stress transfer model seismogenic zone megathrust failure
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Mutual recombination in slow Si^+ + H^- collisions 被引量:2
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作者 王建国 刘春雷 +2 位作者 Janev R. K 颜君 施建荣 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第11期2651-2656,共6页
This paper studies the process of mutual neutralization of Si^+ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included... This paper studies the process of mutual neutralization of Si^+ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included in the collision dynamics. The cross sections for population of specific final states of product Si atom are calculated in the CM energy range 0.05 e∨/u-5 ke∨/u. Both singlet and triplet states are considered. At collision energies below -10 e∨/u, the most populated singlet state is Si(3p4p, ^1S0), while for energies above -150e∨/u it is the Si(3p, 4p, ^1P1) state. In the case of triplet states, the mixed 3p4p(^3S1 +^3P0) states are the most populated in the entire collision energy range investigated. The total cross section exhibits a broad maximum around 200 300e∨/u and for ECM ≤ 10e∨/u it monotonically increases with decreasing the collision energy, reaching a value of 8 × 10^-13 cm^2 at ECM = 0.05 e∨/u. The ion-pair formation process in Si(3p^2 ^3PJ)+H(1s) collisions has also been considered and its cross section in the considered energy range is very small (smaller than 10^-20 cm^2 in the energy region below 1 ke∨/u). 展开更多
关键词 multi-channel Landau-Zener model slow collision mutual neutralization
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Predicting dynamics of soil organic carbon mineralization with a double exponential model in different forest belts of China 被引量:10
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作者 YANG Li-xia PAN Jian-jun YUAN Shao-feng 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第1期39-43,共5页
The dynamics of soil organic carbon(SOC)was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils deri... The dynamics of soil organic carbon(SOC)was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils derived from Changbai and Qilian Mountain areas.By analyzing and fitting the CO2 evolved rates with SOC mineralization,the results showed that active carbon pools accounted tor 1.0%to 8.5%of SOC with an average of mean resistant times(MRTs)for 24 days,and slow carbon pools accounted for 91%to 99%of SOC with an average of MRTs for 179 years.The sizes and MRTs of slow carbon pools showed that SOC in Qilian Mountain sites was more difficult to decompose than that in Changbai Mountain sites.By analyzing the effects of temperature,soil clay content and elevation on SOC mineralization,results indicated that mineralization of SOC was directly related to temperature and that content of accumulated SOC and size of slow carbon pools from Changbai Mountain and Qilian Mountain sites increased linearly with increasing clay content,respectively,which showed temperature and clay content could make greater effect on mineralization of SOC. 展开更多
关键词 Soil organic carbon Organic carbon mineralization Double exponential model Active carbon pools slow carbon pools Mean resistant times(MRTs)
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Pharmacokinetic-Pharmacodynamic modeling of the analgesic effect of bupredermTM, in mice 被引量:1
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作者 Min-Hyuk Yun Seung-Wei Jeong +1 位作者 Chaul-Min Pai Sun-Ok Kim 《Health》 2010年第8期824-831,共8页
Purpose: BupredermTM-Buprenorphine transdermal delivery system (BTDS) was developed for the treatment of post-operative and chronic pains. This study examined the relationship between the plasma concentration of bupre... Purpose: BupredermTM-Buprenorphine transdermal delivery system (BTDS) was developed for the treatment of post-operative and chronic pains. This study examined the relationship between the plasma concentration of buprenorphine and its analgesic effect (tail flick test) in order to assess the usefulness of pharmacokinetic-pharmacodynamic (PK-PD) modeling in describing this relationship. Methods: After patch application, plasma concentrations of bu- prenorphine in mice were measured for 72 hours with a validated LC/MS/MS system, and the analgesic effects were assessed by tail flick test for the period of 24 hours. A modified two- compartment open model was used to explain the PK properties of BTDS, and the PD model was characterized by slow receptor binding. Results: The peak buprenorphine level in plasma was achieved at 1-24 h and the effective therapeutic drug concentration was maintained for 72 hours. BupredermTM induced prolongation of tail-flick latency in a dose and time dependent manner. Maximum analgesic effect was attained at 3-6 h and was maintained for 24 h after patch application. Counter-clockwise hysteresis between the plasma concentration and the analgesic efficacy of BTDS was observed after BupredermTM application, indicating there was a delay between plasma concentrations and the effect observed. From the developed PK-PD model, Kd values (0.69-0.82 nM) that were derived from the pharmacodynamic parameters (Kon and Koff) are similar to the reported values (Kd = 0.76 ± 0.14 nM). Good agreement between the predicted and observed values was noted for the rate of change in analgesic effect data (R2 = 0.822, 0.852 and 0.774 for 0.24, 0.8 and 2.4 mg/patch, respectively). Conclusions: The established PK- PD model successfully described the relationship between plasma concentration of buprenorphine and its analgesic efficacy measured by the tail flick test. Our model might be useful in estimation and prediction of onset, magnitude and time course of concentration and pharmacological effects of BTDS and will be useful to simulate PK-PD profiles with clinical regimens. 展开更多
关键词 Pharmacokinetic-Pharmacodynamic modeling BupredermTM BUPRENORPHINE TRANSDERMAL System slow receptor-binding model
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Simulation study of slow extraction for the Shanghai Advanced Proton Therapy facility 被引量:4
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作者 Yu-Hui Yang Man-Zhou Zhang De-Ming Li 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第9期1-7,共7页
The Shanghai Advanced Proton Therapy facility employs third-integer slow extraction. In order to achieve accurate treatment, high-quality spill is needed. Therefore,parameters that may affect slow extraction should be... The Shanghai Advanced Proton Therapy facility employs third-integer slow extraction. In order to achieve accurate treatment, high-quality spill is needed. Therefore,parameters that may affect slow extraction should be investigated by simulation. A computer model of the synchrotron operation slow extraction was constructed with MATLAB~. By simulating the motion of the circulating protons, we could quantify the influence of machine and initial beam parameters on properties of the extracted beam, such as ripple, uniformity, stability, on-and off-time of the spill and spill width in the synchrotron.Suitable design parameters including the horizontal tunes,power supply ripple, longitudinal RF cavity voltage, RFKO and the chromaticities were determined. 展开更多
关键词 治疗设备 模拟 质子 提取 上海 装置 MATLAB 光束参数
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Similarities and differences in inherent mechanism and characteristic frequency between the one-dimensional poroelastic model and the layered White model
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作者 Li-Ming Zhao Cai-Ping Lu +1 位作者 Yang Liu Chao-Chao Li 《Petroleum Science》 SCIE EI CAS CSCD 2024年第4期2383-2392,共10页
The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D)poroelastic model and the layered White model were investigated.This investigation was conducted under ... The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D)poroelastic model and the layered White model were investigated.This investigation was conducted under the assumption that the rock was homogenous and isotropic at the mesoscopic scale.For the inherent mechanism,both models resulted from quasi-static flow in a slow P-wave diffusion mode,and the differences between them originated from saturated fluids and boundary conditions.On the other hand,for the characteristic frequencies of the models,the characteristic frequency of the 1D poroelastic model was first modified because the elastic constant and formula for calculating it were misused and then compared to that of the layered White model.Both of them moved towards higher frequencies with increasing permeability and decreasing viscosity and diffusion length.The differences between them were due to the diffusion length.The diffusion length for the 1D poroelastic model was determined by the sample length,whereas that for the layered White model was determined by the length of the representative elementary volume(REV).Subsequently,a numerical example was presented to demonstrate the similarities and differences between the models.Finally,published experimental data were interpreted using the 1D poroelastic model combined with the Cole-Cole model.The prediction of the combined model was in good agreement with the experimental data,thereby validating the effectiveness of the 1D poroelastic model.Furthermore,the modified characteristic frequency in our study was much closer to the experimental data than the previous prediction,validating the effectiveness of our modification of the characteristic frequency of the 1D poroelastic model.The investigation provided insight into the internal relationship between wave-induced fluid flow(WIFF)models at macroscopic and mesoscopic scales and can aid in a better understanding of the elastic modulus dispersion and attenuation caused by the WIFF at different scales. 展开更多
关键词 1D poroelastic model Layered White model Quasi-static flow slow P-wave diffusion Characteristic frequency Diffusion length
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Effects of switching frequency and leakage inductance on slow-scale stability in a voltage controlled flyback converter 被引量:2
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作者 王发强 马西奎 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第12期133-140,共8页
The effects of both the switching frequency and the leakage inductance on the slow-scale stability in a voltage controlled flyback converter are investigated in this paper. Firstly, the system description and its math... The effects of both the switching frequency and the leakage inductance on the slow-scale stability in a voltage controlled flyback converter are investigated in this paper. Firstly, the system description and its mathematical model are presented. Then, the improved averaged model, which covers both the switching frequency and the leakage inductance, is established, and the effects of these two parameters on the slow-scale stability in the system are analyzed. It is found that the occurrence of Hopf bifurcation in the system is the main reason for losing its slow-scale stability and both the switching frequency and the leakage inductance have an important effect on this slow-scale stability. Finally, the effectiveness of the improved averaged model and that of the corresponding theoretical analysis are confirmed by the simulation results and the experimental results. 展开更多
关键词 flyback converter slow-scale stability improved averaged model Hopf bifurcation
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Ising Model on an Infinite Ladder Lattice
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作者 GAO Xing-Ru 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第3X期553-562,共10页
In this paper we propose an Ising model on an infinite ladder lattice, which is made of two infinite Ising spin chains with interactions. It is essentially a quasi-one-dimessional Ising model because the length of the... In this paper we propose an Ising model on an infinite ladder lattice, which is made of two infinite Ising spin chains with interactions. It is essentially a quasi-one-dimessional Ising model because the length of the ladder lattice is infinite, while its width is finite. We investigate the phase transition and dynamic behavior of Ising model on this quasi-one-dimessional system. We use the generalized transfer matrix method to investigate the phase transition of the system. It is found that there is no nonzero temperature phase transition in this system. At the same time, we are interested in Glauber dynamics. Based on that, we obtain the time evolution of the local spin magnetization by exactly solving a set of master equations. 展开更多
关键词 Ising model general transfer matrix phase transition Glauber dynamics critical slow down
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Modeling Neuromorphic Persistent Firing Networks
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作者 Ning Ning Guoqi Li +5 位作者 Wei He Kejie Huang Li Pan Kiruthika Ramanathan Rong Zhao Luping Shi 《International Journal of Intelligence Science》 2015年第2期89-101,共13页
Neurons are believed to be the brain computational engines of the brain. A recent discovery in neurophysiology reveals that interneurons can slowly integrate spiking, share the output across a coupled network of axons... Neurons are believed to be the brain computational engines of the brain. A recent discovery in neurophysiology reveals that interneurons can slowly integrate spiking, share the output across a coupled network of axons and respond with persistent firing even in the absence of input to the soma or dendrites, which has not been understood and could be very important for exploring the mechanism of human cognition. The conventional models are incapable of simulating the important newly-discovered phenomenon of persistent firing induced by axonal slow integration. In this paper, we propose a computationally efficient model of neurons through modeling the axon as a slow leaky integrator, which captures almost all-known neural behaviors. The model controls the switching of axonal firing dynamics between passive conduction mode and persistent firing mode. The interplay between the axonal integrated potential and its multiple thresholds in axon precisely determines the persistent firing dynamics of neurons. We also present a persistent firing polychronous spiking network which exhibits asynchronous dynamics indicating that this computationally efficient model is not only bio-plausible, but also suitable for large scale spiking network simulations. The implications of this network and the analog circuit design for exploring the relationship between working memory and persistent firing enable developing a spiking network-based memory and bio-inspired computer systems. 展开更多
关键词 NEURON model Neuromorphic PERSISTENT FIRING slow Integration SPIKING Network Working Memory
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高校技术转移对地方企业自主创新能力的影响——基于Slow模型的实证分析
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作者 阚洪乾 《特区经济》 2015年第6期46-48,共3页
知识经济时代科学技术对经济增长的作用日益突出,中国新一轮的深化改革也提出要把科技作为经济增长的内生动力。本文构建Slow模型,综合考虑高校技术转移指标,利用全国31个省市2006-2013年面板数据进行分析,结果显示:1高校技术转移综合... 知识经济时代科学技术对经济增长的作用日益突出,中国新一轮的深化改革也提出要把科技作为经济增长的内生动力。本文构建Slow模型,综合考虑高校技术转移指标,利用全国31个省市2006-2013年面板数据进行分析,结果显示:1高校技术转移综合指标和区域自主创新能力之间存在着显著的正相关关系,高校技术转移综合指标每增长1%,地方出口总额增长2.650466%;2地方专利数和国家科技园区数每增长1%,地方出口总额分别增长4.03081%和2.080536%。 展开更多
关键词 高校技术转移 slow模型 综合指标 自主创新
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低慢小无人机红外辐射特性工程计算模型
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作者 唐晗 曾兴容 +10 位作者 刘传明 罗亚江 李宗峰 何实 杨林 夏丽昆 刘炼 李晓君 袁小春 洪闻青 张应旭 《红外技术》 北大核心 2025年第10期1226-1233,共8页
低慢小无人机飞行高度低、飞行速度慢、尺寸体积小,反射环境辐射情况复杂,导致对其红外辐射特性仿真计算困难。本文引入双向反射分布函数,构建低慢小无人机的自身辐射、反射环境辐射的工程计算模型,开发低慢小无人机红外辐射特性计算程... 低慢小无人机飞行高度低、飞行速度慢、尺寸体积小,反射环境辐射情况复杂,导致对其红外辐射特性仿真计算困难。本文引入双向反射分布函数,构建低慢小无人机的自身辐射、反射环境辐射的工程计算模型,开发低慢小无人机红外辐射特性计算程序,并结合美国中佛罗里达大学对大疆精灵4Pro无人机的红外辐射强度实测数据,从不同观测角度、不同波段(中波、长波)对该模型进行验证及分析。验证结果表明该模型计算数据与实测数据一致性较好,能够满足实际工程使用。 展开更多
关键词 低慢小无人机 双向反射分布函数 红外辐射特性 工程计算模型
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以多相T2弛豫时间模型解释表观弥散系数对T2弛豫时间的高度依赖性
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作者 王毅翔 《新发传染病电子杂志》 2025年第2期54-62,共9页
在体内弥散加权成像时,表观弥散系数(apparent diffusion coefficient,ADC)可以反映组织弥散程度。ADC在感染性病变影像学等临床影像学中广泛使用。一般假设肿瘤的弥散会受限,而水分多的组织弥散更加自由。然而,实际临床工作得到的ADC... 在体内弥散加权成像时,表观弥散系数(apparent diffusion coefficient,ADC)可以反映组织弥散程度。ADC在感染性病变影像学等临床影像学中广泛使用。一般假设肿瘤的弥散会受限,而水分多的组织弥散更加自由。然而,实际临床工作得到的ADC值常常与预期的组织弥散情况相背离。比如脓肿内脓肿液测得的ADC一般非常低;而一些硬质组织如软骨、椎间盘的ADC非常高。虽然脓肿液可能有一定黏度,但黏液瘤却表现为高ADC。文献认为肝细胞癌ADC相对于肝脏弥散受限。然而,由于肝细胞癌大多血供增加、动脉血液供应比例增高并伴有水肿,因此,肝细胞癌不太可能具有真正的弥散受限。相反,按照慢速弥散系数(slow diffusion coefficient,SDC)计算方法,结果显示肝细胞癌的弥散快于周围肝脏组织。最近提出的体内ADC测量值与T_(2)弛豫时间密切相关。T_(2)弛豫时间可分为短T_(2)段(<60ms)、中等T_(2)段(60~80ms)和长T_(2)段(>80ms,3.0T磁场值)。对于短T_(2)段,T_(2)弛豫时间与ADC之间为负相关;对于长T_(2)段,T_(2)弛豫时间与ADC之间为正相关。本文通过体素内不相干运动模型的概念来解释ADC的T_(2)弛豫时间依赖性。我们建议在解释临床高b值弥散加权成像图像和ADC图像时不再常规使用“弥散受限”一词。 展开更多
关键词 表观弥散系数 慢速弥散系数 体素内不相干运动模型 弥散受限
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基于数据驱动的遥测缓变参数快速全局K-Means聚类异常检测包络模型 被引量:1
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作者 胡健 刘学 《舰船电子工程》 2025年第2期129-132,181,共5页
遥测参数是反映飞行器状态和环境的重要参数,为了实现对遥测缓变参数异常的快速识别和检测,改进传统设定单一上下界值进行遥测参数异常判定的方法,论文提出了一种基于数据驱动的遥测缓变参数快速全局K-Means聚类异常检测包络模型,通过... 遥测参数是反映飞行器状态和环境的重要参数,为了实现对遥测缓变参数异常的快速识别和检测,改进传统设定单一上下界值进行遥测参数异常判定的方法,论文提出了一种基于数据驱动的遥测缓变参数快速全局K-Means聚类异常检测包络模型,通过利用快速全局K-Means聚类算法计算样本数据的聚类中心,然后考虑噪声特性利用动态变步长计算包络上下界,得到遥测缓变参数异常检测包络模型。通过算例仿真分析,验证了论文方法能够有效实现对遥测缓变参数异常的快速检测。 展开更多
关键词 遥测缓变参数 数据驱动 K-MEANS聚类 包络模型 异常检测
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冠状动脉慢血流的危险因素分析及预测模型构建
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作者 高渊博 赵思玉 +2 位作者 李群星 冯松涛 陶艾彬 《江苏大学学报(医学版)》 2025年第6期504-511,共8页
目的:分析与冠状动脉慢血流(coronary slow flow, CSF)相关的危险因素并构建临床预测模型。方法:选取2018年1月至2023年12月就诊于江苏大学附属人民医院及连云港市第一人民医院接受冠状动脉造影(coronary angiography, CAG)检查结果为... 目的:分析与冠状动脉慢血流(coronary slow flow, CSF)相关的危险因素并构建临床预测模型。方法:选取2018年1月至2023年12月就诊于江苏大学附属人民医院及连云港市第一人民医院接受冠状动脉造影(coronary angiography, CAG)检查结果为冠状动脉狭窄≤40%、且存在CSF的患者201例作为观察组,同时选择同期CAG检查结果为冠状动脉狭窄≤40%、无CSF的患者153例作为对照组。比较两组患者的一般临床资料、心脏超声检查结果及血常规、生化和炎症指标,采用LASSO回归初步筛选变量,多因素Logistic回归进一步分析CSF的危险因素,R软件构建Nomogram预测模型并绘制列线图,采用ROC曲线、校准曲线和决策曲线分析(DCA)评估预测模型的区分度、校准度和临床适用性。结果:LASSO回归结果表明,高血压、吸烟、血红蛋白、HDL-C、三酰甘油-葡萄糖(TyG)指数、血小板与淋巴细胞比值(PLR)以及左室舒张期内径为预测发生CSF的特征变量。多因素回归分析表明,高血压、吸烟、TyG指数升高、PLR升高、左室舒张期内径增加是CSF的独立危险因素,HDL-C升高是CSF的保护因素。基于以上指标绘制列线图预测模型,ROC曲线显示,预测模型的曲线下面积(AUC)为0.793(95%CI:0.747~0.838)。校准曲线对模型一致性进行评价,Hosmer-Lemeshow检验显示模型拟合良好(P=0.151),提示模型实际预测能力与理想的预测能力较为接近。DCA结果同样表明预测模型具有较好的临床适用性,能带来临床获益。结论:高血压、吸烟、TyG指数升高、PLR升高、左室舒张期内径增加是CSF的独立危险因素,HDL-C升高是CSF的保护因素,以上述因素为依据构建的预测模型在预测CSF的发生时具有良好的效能。 展开更多
关键词 冠状动脉慢血流 危险因素 预测模型
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基于快慢车模式的市域(郊)列车越行点选择模型研究
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作者 宋唯维 叶玉玲 +3 位作者 刘楷 陈聪聪 朱资岳 周文涛 《铁道标准设计》 北大核心 2025年第1期7-14,共8页
越行点的设置对于实现市域(郊)铁路快慢车组合运营至关重要。在对市域(郊)铁路越行点设置方式和越行点选择影响因素进行综述的基础上,针对国内建设一定数量的有越行功能中间站的市域(郊)列车,提出一种越行点选择模式。该模式考虑到发线... 越行点的设置对于实现市域(郊)铁路快慢车组合运营至关重要。在对市域(郊)铁路越行点设置方式和越行点选择影响因素进行综述的基础上,针对国内建设一定数量的有越行功能中间站的市域(郊)列车,提出一种越行点选择模式。该模式考虑到发线或越行线的建设条件、越行点的数量以及车站间隔时间。为了实现全体乘客出行时间的最小化,构建市域(郊)列车越行点选择的优化模型,并采用该模型计算列车在各个车站的到发时间,并确定越行点的位置。同时,为了有效分析和确定越行点的位置,提出一种基于优化模型的列车到发时间的计算方法和列车运行图的铺画手段。以上海机场联络线为实例,应用提出的优化模型计算上下行列车在各个车站的停站时间,并绘制相应的列车运行图。研究结果表明,在远期规划的上海机场联络线高峰小时,假设开行6对站站停列车、大站停列车和城际列车,根据优化模型的计算,仅需设置一座具有越行功能中间站,即张江站。为市域(郊)铁路越行点的设置提供了一种优化模型和计算方法,在减少越行点数量的同时,实现全体乘客的出行时间最小化。 展开更多
关键词 市域(郊)铁路 快慢车模式 越行点 选择优化模型 停站时间
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持续缺氧对闭环呼吸系统的影响及其动力学机制研究
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作者 夏露源 段利霞 王智慧 《力学学报》 北大核心 2025年第3期782-800,共19页
呼吸控制系统精确控制呼吸节律的生成和维持,以适应机体在不同生理和病理状态下的需求.当机体动脉血中的氧分压低于正常范围时,可能引发病理性呼吸急促.Pre-Bötzinger复合体作为呼吸节律起源的关键部位,其中包含呼气神经元、吸气... 呼吸控制系统精确控制呼吸节律的生成和维持,以适应机体在不同生理和病理状态下的需求.当机体动脉血中的氧分压低于正常范围时,可能引发病理性呼吸急促.Pre-Bötzinger复合体作为呼吸节律起源的关键部位,其中包含呼气神经元、吸气神经元和跨时相神经元,这些神经元通过神经调节和化学调节等多种机制协同工作,共同调控呼吸节律.呼吸过程涉及神经元网络的放电活动、肺泡的扩张与收缩、以及血液中氧气的传输等多个时间尺度的相互作用.在一定的缺氧条件下,闭环系统可以实现自我恢复.文章主要研究在不同的初始放电状态时,持续性缺氧干扰后系统的自我恢复能力.研究结果表明,系统的恢复情况可分为:完全恢复至常氧水平、部分恢复至轻度缺氧水平或完全无法恢复.基于方波电流的简洁性,简化了模型并应用动力学分析方法,探讨了产生不同缺氧反应的动力学机制.分岔分析表明,系统在施加持续缺氧前、缺氧过程中、移除缺氧后以及再次达到稳定状态的各个阶段的分岔结构变化是影响系统恢复能力的关键因素,并且只有缺氧前后分岔结构不发生改变的情形下,系统才具备自我恢复至常氧的能力.本研究增进了持续缺氧干扰对呼吸节律影响的理解,研究节律恢复的外部因素和生理条件的联系,以及节律恢复的内在动力学机制. 展开更多
关键词 呼吸节律 闭环呼吸控制模型 分岔分析 快慢变量分离 簇放电
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缩孔对含铝浇注炸药慢烤特性的影响
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作者 董啸 智小琦 +1 位作者 肖游 于永利 《弹箭与制导学报》 北大核心 2025年第5期675-683,共9页
为了深入研究缩孔对慢烤特性的影响,对装填含铝浇注炸药的烤燃弹进行了带缩孔和不带缩孔且多点测温的慢烤试验,记录炸药在升温过程中的温度变化和响应烈度,试验结果表明,无论是否带缩孔,两发烤燃弹的最终响应表现均为燃烧反应。在试验... 为了深入研究缩孔对慢烤特性的影响,对装填含铝浇注炸药的烤燃弹进行了带缩孔和不带缩孔且多点测温的慢烤试验,记录炸药在升温过程中的温度变化和响应烈度,试验结果表明,无论是否带缩孔,两发烤燃弹的最终响应表现均为燃烧反应。在试验的基础上,基于炸药的通用烤燃模型(universal cook-off model,UCM),建立了含铝浇注炸药的烤燃计算模型,并研究了缩孔变化对烤燃特性的影响。结果表明,缩孔置于不同区域时对点火温度无明显影响。但是,随着缩孔体积的增加,点火时刻炸药的反应度和点火时刻的压力呈指数趋势增大,这表明缩孔体积的不同对响应时刻炸药的内部压力及炸药反应度具有重要影响。因此,为提高弹药的热安全性,应限制装药缩孔的产生。 展开更多
关键词 预制缩孔 慢速烤燃 通用烤燃模型 含铝浇注炸药
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考虑平台慢漂运动影响的顶张力立管涡激振动特性研究
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作者 黄鹏 金言 +2 位作者 张伟峻 吕林 宋志伟 《水动力学研究与进展(A辑)》 北大核心 2025年第3期488-500,共13页
基于绝对节点坐标方法(Absolute Nodal Coordinate Formulation,ANCF)和Van der Pol尾流振子模型,该文建立了考虑平台慢漂运动影响的立管涡激振动(Vortex-induced vibration,VIV)数值模型。通过该数值模型,该文研究了平台慢漂运动和均... 基于绝对节点坐标方法(Absolute Nodal Coordinate Formulation,ANCF)和Van der Pol尾流振子模型,该文建立了考虑平台慢漂运动影响的立管涡激振动(Vortex-induced vibration,VIV)数值模型。通过该数值模型,该文研究了平台慢漂运动和均匀流共同作用下顶张力立管的横流向VIV特性,以及慢漂幅值和周期变化产生的影响。结果表明:立管横流向VIV表现出慢漂周期性的振幅、振动频率、固有频率和模态变化;振动形态在行波和驻波之间交替切换,并存在多模态相互竞争,部分时段内行波的频率、方向和传播速度随时间变化;立管横流向位移均方根相比于平台固定工况时减小,并随慢漂幅值增大或慢漂周期减小而减小;立管弯曲应力最大值相比于平台固定工况时增大,并随着慢漂的幅值增大或周期减小而增大。 展开更多
关键词 深海立管 涡激振动 平台慢漂运动 绝对节点坐标方法 尾流振子模型
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