期刊文献+
共找到3,230篇文章
< 1 2 162 >
每页显示 20 50 100
Gated Neural Network-Based Unsteady Aerodynamic Modeling for Large Angles of Attack
1
作者 DENG Yongtao CHENG Shixin MI Baigang 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第4期432-443,共12页
Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft ... Modeling of unsteady aerodynamic loads at high angles of attack using a small amount of experimental or simulation data to construct predictive models for unknown states can greatly improve the efficiency of aircraft unsteady aerodynamic design and flight dynamics analysis.In this paper,aiming at the problems of poor generalization of traditional aerodynamic models and intelligent models,an intelligent aerodynamic modeling method based on gated neural units is proposed.The time memory characteristics of the gated neural unit is fully utilized,thus the nonlinear flow field characterization ability of the learning and training process is enhanced,and the generalization ability of the whole prediction model is improved.The prediction and verification of the model are carried out under the maneuvering flight condition of NACA0015 airfoil.The results show that the model has good adaptability.In the interpolation prediction,the maximum prediction error of the lift and drag coefficients and the moment coefficient does not exceed 10%,which can basically represent the variation characteristics of the entire flow field.In the construction of extrapolation models,the training model based on the strong nonlinear data has good accuracy for weak nonlinear prediction.Furthermore,the error is larger,even exceeding 20%,which indicates that the extrapolation and generalization capabilities need to be further optimized by integrating physical models.Compared with the conventional state space equation model,the proposed method can improve the extrapolation accuracy and efficiency by 78%and 60%,respectively,which demonstrates the applied potential of this method in aerodynamic modeling. 展开更多
关键词 large angle of attack unsteady aerodynamic modeling gated neural networks generalization ability
下载PDF
Predicting the friction angle of clays using a multi-layer perceptron neural network enhanced by yeo-johnson transformation and coral reefs optimization 被引量:1
2
作者 Libing Yang Trung Nguyen-Thoi Trung-Tin Tran 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第10期3982-4003,共22页
The accurate prediction of the friction angle of clays is crucial for assessing slope stability in engineering applications.This study addresses the importance of estimating the friction angle and presents the develop... The accurate prediction of the friction angle of clays is crucial for assessing slope stability in engineering applications.This study addresses the importance of estimating the friction angle and presents the development of four soft computing models:YJ-FPA-MLPnet,YJ-CRO-MLPnet,YJ-ACOC-MLPnet,and YJCSA-MLPnet.First of all,the Yeo-Johnson(YJ)transformation technique was used to stabilize the variance of data and make it more suitable for parametric statistical models that assume normality and equal variances.This technique is expected to improve the accuracy of friction angle prediction models.The friction angle prediction models then utilized multi-layer perceptron neural networks(MLPnet)and metaheuristic optimization algorithms to further enhance performance,including flower pollination algorithm(FPA),coral reefs optimization(CRO),ant colony optimization continuous(ACOC),and cuckoo search algorithm(CSA).The prediction models without the YJ technique,i.e.FPA-MLPnet,CRO-MLPnet,ACOC-MLPnet,and CSA-MLPnet,were then compared to those with the YJ technique,i.e.YJ-FPA-MLPnet,YJ-CRO-MLPnet,YJ-ACOC-MLPnet,and YJ-CSA-MLPnet.Among these,the YJ-CRO-MLPnet model demonstrated superior reliability,achieving an accuracy of up to 83%in predicting the friction angle of clay in practical engineering scenarios.This improvement is significant,as it represents an increase from 1.3%to approximately 20%compared to the models that did not utilize the YJ transformation technique. 展开更多
关键词 Natural hazards Slope stability Friction angle CLAY Soft computing models Geotechnical engineering
下载PDF
Development of a DFN-based probabilistic block theory approach for bench face angle design in open pit mining
3
作者 Jianhua Yan Xiansen Xing +4 位作者 Zhihai Li Weida Ni Liuyuan Zhao Chun Zhu Yuanyuan He 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3047-3062,共16页
In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face ... In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable mining.This study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks testing.The proposed approach was applied to a granite mine in China.First,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit slopes.Then,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each sector.Finally,a bench face angle was determined commensurate with an acceptable risk level of stability.The simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities. 展开更多
关键词 Open pit mine Bench face angle Block theory Probabilistic approach Discrete fracture network modeling Fractured rock slope
下载PDF
Contact Angle Prediction Model for Underwater Oleophobic Surfaces Based on Multifractal Theory
4
作者 Jiang Huayi You Yanzhen +4 位作者 Hu Juan Tian Dongmei Qi Hongyuan Sun Nana Liu Mei 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第3期37-48,共12页
Traditional microstructure scale parameters have difficulty describing the structure and distribution of a roughmaterial’s surface morphology comprehensively and quantitatively. This study constructs hydrophilic and ... Traditional microstructure scale parameters have difficulty describing the structure and distribution of a roughmaterial’s surface morphology comprehensively and quantitatively. This study constructs hydrophilic and underwateroleophobic surfaces based on polyvinylidene fluoride (PVDF) using a chemical modification method, and the fractaldimension and multifractal spectrum are used to quantitatively characterize the microscopic morphology. A new contactangle prediction model for underwater oleophobic surfaces is established. The results show that the fractal dimension ofthe PVDF surface first increases and then decreases with the reaction time. The uniformity characterized by the multifractalspectrum was generally consistent with scanning electron microscope observations. The contact angle of water droplets onthe PVDF surface is negatively correlated with the fractal dimension, and oil droplets in water are positively correlated.When the fractal dimension is 2.0975, the new contact angle prediction model has higher prediction accuracy. Themaximum and minimum relative deviations of the contact angle between the theoretical and measured data are 18.20%and 0.72%, respectively. For water ring transportation, the larger the fractal dimension and spectral width of the materialsurface, the smaller the absolute value of the spectral difference, the stronger the hydrophilic and oleophobic properties, andthe better the water ring transportation stability. 展开更多
关键词 contact angle hydrophilic-oleophobic surface polyvinylidene fluoride MULTIFRACTAL prediction model
下载PDF
Numerical Stability and Accuracy of Contact Angle Schemes in Pseudopotential Lattice Boltzmann Model for Simulating Static Wetting and Dynamic Wetting
5
作者 Dongmin Wang Gaoshuai Lin 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第10期299-318,共20页
There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity sch... There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity scheme(IVD scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall(MPB-C scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes(MPB-W scheme)and the geometric formulation scheme(GF scheme).But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the past.In this paper,the numerical stability and accuracy of these schemes are clarified for the first time,by applying the five widely used contact angle schemes to simulate a two-dimensional(2D)sessile droplet on wall and capillary imbibition in a 2D channel as the examples of static wetting and dynamic wetting simulations respectively.(i)It is shown that the simulated contact angles by the GF scheme are consistent at different density ratios for the same prescribed contact angle,but the simulated contact angles by the PB scheme,IVD scheme,MPB-C scheme and MPB-W scheme change with density ratios for the same fluid-solid interaction strength.The PB scheme is found to be the most unstable scheme for simulating static wetting at increased density ratios.(ii)Although the spurious velocity increases with the increased liquid/vapor density ratio for all the contact angle schemes,the magnitude of the spurious velocity in the PB scheme,IVD scheme and GF scheme are smaller than that in the MPB-C scheme and MPB-W scheme.(iii)The fluid density variation near the wall in the PB scheme is the most significant,and the variation can be diminished in the IVD scheme,MPB-C scheme andMPBWscheme.The variation totally disappeared in the GF scheme.(iv)For the simulation of capillary imbibition,the MPB-C scheme,MPB-Wscheme and GF scheme simulate the dynamics of the liquid-vapor interface well,with the GF scheme being the most accurate.The accuracy of the IVD scheme is low at a small contact angle(44 degrees)but gets high at a large contact angle(60 degrees).However,the PB scheme is the most inaccurate in simulating the dynamics of the liquid-vapor interface.As a whole,it is most suggested to apply the GF scheme to simulate static wetting or dynamic wetting,while it is the least suggested to use the PB scheme to simulate static wetting or dynamic wetting. 展开更多
关键词 Pseudopotential lattice Boltzmann model contact angle scheme static wetting dynamic wetting capillary imbibition
下载PDF
Wide angle reflections in OBC seismic physical model experiment
6
作者 杨正华 黄翼坚 吴永新 《Applied Geophysics》 SCIE CSCD 2012年第2期207-212,236,共7页
Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable (OBC) seismic wide angle reflections ... Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable (OBC) seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don't support theoretical conclusions. The main experimental conclusions are: 1. Wide angle reflection energies are stronger than non-wide-angle reflections (up to twice as strong) but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the non- wide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than non- wide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor. 展开更多
关键词 ocean bottom cable physical model wide angle refection model experiment
下载PDF
Modified GIT model for predicting wind-speed behavior of low-grazing-angle radar sea clutter 被引量:3
7
作者 张玉石 张金鹏 +1 位作者 黎鑫 吴振森 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第10期587-592,共6页
A modified GIT model for describing the variational trend of mean clutter reflectivity as a function of wind speed is proposed. It uses two slope adjustment factors and two critical wind-speed factors to define and ad... A modified GIT model for describing the variational trend of mean clutter reflectivity as a function of wind speed is proposed. It uses two slope adjustment factors and two critical wind-speed factors to define and adjust the increasing slope of reflectivity with respect to wind speed. In addition, it uses a constant factor to compensate the overall amplitude of clutter reflectivity. The performance of the modified GIT model has been verified on the basis of the L-band low-grazing-angle radar sea clutter data. The results are in good agreement with the experimental data, indicating that the model is more effective in predicting the wind-speed behavior of clutter reflectivity than the conventional GIT model, especially for lower and higher wind speeds. We believe that the proposed model can provide deeper insights into the relationship between radar sea clutter reflectivity and sea state conditions. 展开更多
关键词 GIT model low grazing angle radar sea clutter
下载PDF
Development of 3D top coal caving angle model for fully mechanized extra-thick coal seam mining 被引量:4
8
作者 Hongfei Duan Lijuan Zhao +2 位作者 Haiyan Yang Yao Zhang Hongchun Xia 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第5期1145-1152,共8页
During high-intensity,fully mechanized mining of extra-thick coal seam,the top coal would cave to a certain 3D form.Based on the data collected during drilling,a 3D model of top coal caving surface space was establish... During high-intensity,fully mechanized mining of extra-thick coal seam,the top coal would cave to a certain 3D form.Based on the data collected during drilling,a 3D model of top coal caving surface space was established to determine the relationship between the location of the stope roof and the caving surface,enabling the mathematical computation of the top caving angle(φ).The drilling method was employed to measure the top caving angle on two extra-thick fully mechanized coal caving faces under the conditions of three geological structures,namely,no geological structure,igneous rock structure,and fault structure.The results show that the value of top caving angle could be accurately estimated on-site with the 9-parameter 3D top coal caving surface model built with the drilling method.This method is a novel on-site measurement that can be easily applied.Our findings reveal that the characteristics of the coal-rock in the two mining faces are different;yet their caving angles follow the ruleφ_(igneous rock structure)<φ_(no geological structure)<φ_(fault structure).Finally,through the data fitting with two indexes(the top coal uniaxial compressive strength and the top caving angle),it is found that the relationship between the two indexes satisfies an exponential decay function. 展开更多
关键词 Space model Field measurement Top coal caving angle Uniaxial compressive strength Exponential decay function
下载PDF
A new diagnostic model of primary open angle glaucoma based on FD-OCT parameters 被引量:1
9
作者 Ya-Jie Zheng Ying-Zi Pan +4 位作者 Xue-Ying Li Yuan Fang Mei Li Rong-Hua Qia Yu Cai 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2018年第6期951-957,共7页
AIM: To build a clinical diagnostic model of primary open angle glaucoma (POAG) using the normal probability chart of frequency-domain optical coherence tomography (FD-OCT). METHODS: This is a cross-sectional ... AIM: To build a clinical diagnostic model of primary open angle glaucoma (POAG) using the normal probability chart of frequency-domain optical coherence tomography (FD-OCT). METHODS: This is a cross-sectional study. Total 133 eyes from 133 healthy subjects and 99 eyes from 99 early POAG patients were included in the study. The retinal nerve fibre layer (RNFL) thickness parameters of optic nerve head (ONH) and RNFL3.45 scan were measured in one randomly selected eye of each subject using RTVue-100 FD-OCT. Then, we used these parameters to establish the diagnostic models. Four different diagnostic models based on two different area partition strategies on ONH and RNFL3.45 parameters, including ONH traditional area partition model (ONH-T), ONH new area partition model (ONH-N), RNFL3.45 traditional area partition model (RNFL3.45-T) and RNFL3.45 new area partition model (RNFL3.45-N), were built and tested by cross-validation. RESULTS: The new area partition models had higher area under the receiver operating characteristic (AROC; ONH-N: 0.990; RNFL3.45-N: 0.939) than corresponding traditional area partition models (ONH-T: 0.979; RNFL3.45-T: 0.881). There was no statistical difference among AROC of ONH-T, ONH-N, and RNFL3.45-N. Nevertheless, ONH-N was the simplest model. CONCLUSION: The new area partition models had higher diagnostic accuracy than corresponding traditional area partition models, which can improve the diagnostic ability of early POAG. In particular, the simplest ONH-N diagnostic model may be convenient for clinical application. 展开更多
关键词 primary open angle glaucoma opticalcoherence tomography ethnic-specific database diagnostic model
下载PDF
Suggestion of advanced regression model on friction angle of fault gouge in South Korea 被引量:2
10
作者 Seong-Woo Moon Hyun-Seok Yun Yong-Seok Seo 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2021年第6期1368-1379,共12页
Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than th... Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low strength.Therefore,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression analysis.Whereas most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657. 展开更多
关键词 Fault gouge Friction angle Simple regression analysis Structural equation model analysis Multiple regression analysis
下载PDF
Automatic measurement of three-phase contact angles in pore throats based on digital images
11
作者 ZANG Chuanzhen WANG Lida +3 位作者 ZHOU Kaihu YU Fuwei JIANG Hanqiao LI Junjian 《Petroleum Exploration and Development》 SCIE 2023年第2期442-449,共8页
With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flood... With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil. 展开更多
关键词 microfluidic model water flooding experiment digital image processing three-phase contact angle measure-ment method flow regime of the remaining oil
下载PDF
Clinical Effect of Tip-Edge plus Appliance in Children with Angle Ⅱ1 Malocclusion 被引量:5
12
作者 徐璐璐 陈莉莉 +2 位作者 杜星颜 高振洋 刘洪臣 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2013年第6期886-891,共6页
The effects of Tip-Edge plus appliance in the treatment of Angle Ⅱ1 malocclusion and the mechanism were investigated. Fifty-two Angle Ⅱ1 children, aged from 12.3-14.2 years, with mandibu- lar retrusion in permanent ... The effects of Tip-Edge plus appliance in the treatment of Angle Ⅱ1 malocclusion and the mechanism were investigated. Fifty-two Angle Ⅱ1 children, aged from 12.3-14.2 years, with mandibu- lar retrusion in permanent dentition were selected and treated with Tip-Edge plus appliance. Lateral cephalometric films taken before and after treatment were analyzed. The arithmetic mean and standard deviation were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change. Results showed that the average treatment time was 16 months. Normal overjet and overbite were established with retroclination of upper incisors and proclination of lower incisors. U1-NA was decreased by 15.4° (P〈0.01). ANB and Y axial angle were decreased significantly (P〈0.05) Soft tissue measurements showed that FCA and UL-E were decreased dramatically (P〈0.05), and LL-E was increased significantly (P〈0.05). Remarkable soft tissue change was noted after the treatment and convex facial profile changed to the straight profile. In conclusion, Tip-Edge plus technique can quickly and efficiently correct anterior bite and lateral outlook. 展开更多
关键词 tip-Edge plus appliance angle Ⅱ1 malocclusion mandibular retrusion cephalometric measurements
下载PDF
Modeling Locking Angle of the Multi-layered Biaxial Weft Knitted Fabric in Shear Deformation 被引量:1
13
作者 张艳明 姜亚明 邱冠雄 《Journal of Donghua University(English Edition)》 EI CAS 2006年第1期130-135,共6页
This paper introduces the construction of the multi-layered biaxial weft knitted fabric (MBWK fabric) and studies the locking angle of this kind of fabric. Moreover, a locking angle model of the MBWK fabric is estab... This paper introduces the construction of the multi-layered biaxial weft knitted fabric (MBWK fabric) and studies the locking angle of this kind of fabric. Moreover, a locking angle model of the MBWK fabric is established for the first time according to its unique construction. Two kinds of locking angles are considered under different restraint conditions: the locking angle θ1 controlled by the inserting yarns and the locking angle θ2 controlled by the stitch yarns. It is concluded that the ultimate value of the locking angle θ is the larger one of the two angles. 展开更多
关键词 locking angle model multi-layered biaxial weft knitted fabrics.
下载PDF
具有非平稳参数的二维肿瘤模型的B-tipping分析
14
作者 袁娅茹 邱志鹏 《赣南师范大学学报》 2024年第3期1-7,共7页
本文建立了一个参数是非平稳变化过程的CD8+T细胞与肿瘤细胞相互作用的数学模型.首先对固定参数条件下的系统进行动力学分析,理论结果表明系统存在双稳态现象和鞍结点分岔.其后引入函数s(t)描述CD8+T细胞输入率的非平稳参数变化过程,发... 本文建立了一个参数是非平稳变化过程的CD8+T细胞与肿瘤细胞相互作用的数学模型.首先对固定参数条件下的系统进行动力学分析,理论结果表明系统存在双稳态现象和鞍结点分岔.其后引入函数s(t)描述CD8+T细胞输入率的非平稳参数变化过程,发现系统在非平稳参数变化下存在B-tipping现象:系统轨迹随着时变参数s(t)的缓慢增加跟踪固定参数系统的轨迹,在分岔点处达到临界状态并经历突变趋向另一个稳定状态.在癌症治疗过程中,通过调节CD8+T细胞的输入率将患者状态移到tipping point可以有效地控制肿瘤生长. 展开更多
关键词 肿瘤模型 B-tipping point 双稳态 鞍结点
下载PDF
A new model for the formation of contact angle and contact angle hysteresis
15
作者 公茂刚 刘远越 许小亮 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第10期390-395,共6页
The formation mechanism of the contact angle and the sliding angle for a liquid drop on a solid surface plays an important role in producing hydrophobic surfaces. A new half soakage model is established in this paper ... The formation mechanism of the contact angle and the sliding angle for a liquid drop on a solid surface plays an important role in producing hydrophobic surfaces. A new half soakage model is established in this paper as a substitute for Wenzel (complete soakage) and Cassie (no soakage) models. The model is suited to many solid surfaces, whether they are hydrophilic or hydrophobic, or even superhydrophobic. Based on the half soakage model, we analyse two surfaces resembling lotus, i.e. taper-like surface and corona-like surface. Furthermore, this new model is used to establish a quantitative relationship between the sliding angle and the parameters of surface morphology. 展开更多
关键词 contact angle half soakage model contact angle hysteresis
下载PDF
Reference Modelof Desired Yaw Anglefor Automated Lane Changing Behavior of Vehicle
16
作者 Dianbo Ren Guanzhe Zhang Hangzhe Wu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2016年第1期23-33,共11页
In this paper,it studies the problem of trajectory planning and tracking for lane changing behavior of vehicle in automatic highway systems. Based on the model of yaw angle acceleration with positive and negative trap... In this paper,it studies the problem of trajectory planning and tracking for lane changing behavior of vehicle in automatic highway systems. Based on the model of yaw angle acceleration with positive and negative trapezoid constraint,by analyzing the variation laws of yaw motion of vehicle during a lane changing maneuver,the reference model of desired yaw angle and yaw rate for lane changing is generated. According to the yaw angle model,the vertical and horizontal coordinates of trajectory for vehicle lane change are calculated. Assuming that the road curvature is a constant,the difference and associations between two scenarios are analyzed,the lane changing maneuvers occurred on curve road and straight road,respectively. On this basis,it deduces the calculation method of desired yaw angle for lane changing on circular road. Simulation result shows that,it is different from traditional lateral acceleration planning method with the trapezoid constraint,by applying the trapezoidal yaw acceleration reference model proposed in this paper, the resulting expected yaw angular acceleration is continuous,and the step tracking for steering angle is not needed to implement. Due to the desired yaw model is direct designed based on the variation laws of raw movement of vehicle during a lane changing maneuver, rather than indirectly calculated from the trajectory model for lane changing, the calculation steps are simplified. 展开更多
关键词 intelligent transportation systems lane changing yaw angle model trajectory planning
下载PDF
Angle of Attack between Blood Flow and Mitral Valve Leaflets in Hypertrophic Obstructive Cardiomyopathy: An In Vivo Multipatient CT-based FSI Study
17
作者 Long Deng Xueying Huang +4 位作者 Heng Zuo Yuan Zheng Chun Yang Yunhu Song Dalin Tang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2018年第8期115-125,共11页
The mechanisms of systolic anterior motion(SAM)of the mitral valve in hypertrophic obstructive cardiomyopathy(HOCM)remain unclear.To investigate the angle of attack between blood flow and mitral valve leaflets at pre-... The mechanisms of systolic anterior motion(SAM)of the mitral valve in hypertrophic obstructive cardiomyopathy(HOCM)remain unclear.To investigate the angle of attack between blood flow and mitral valve leaflets at pre-SAM time point,patient-specific CT-based computational models were constructed for 5 patients receiving septal myectomy surgery to obtain pre-and post-operative 2D vector flow mapping.The comparisons between pre-and post-operative angles of attack based on 2D vector flow mapping of 5 patients were performed.It was found that there was no statistically significant difference between pre-and post-operative angles of attack(61.1±t wa o vs.56.2±56.o,p=0.306,n=5).Therefore,we propose that the angle of attack might not play an important role in the initiation of SAM. 展开更多
关键词 HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY SYSTOLIC anterior motion mitralvalve LEAFLETS computational model angle of attack
下载PDF
Precisely controlling the twist angle of epitaxial MoS_(2)/graphene heterostructure by AFM tip manipulation
18
作者 Jiahao Yuan Mengzhou Liao +7 位作者 Zhiheng Huang Jinpeng Tian Yanbang Chu Luojun Du Wei Yang Dongxia Shi Rong Yang Guangyu Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第8期173-177,共5页
Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability... Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability to precisely and reproducibly manipulate the twist angle hinders the further development of twistronics.Here,we demonstrated an atomic force microscope(AFM)tip manipulation method to control the interlayer twist angle of epitaxial MoS_(2)/graphene heterostructure with an ultra-high accuracy better than 0.1°.Furthermore,conductive AFM and spectroscopic characterizations were conducted to show the effects of the twist angle on moirépattern wavelength,phonons and excitons.Our work provides a technique to precisely control the twist angle of 2D moirématerials,enabling the possibility to establish the phase diagrams of moiréphysics with twist angle. 展开更多
关键词 AFM tip manipulation MoS_(2)/graphene heterostructure twist angle moirésuperlattice
下载PDF
An extended smart driver model considering electronic throttle angle changes with memory
19
作者 Congzhi Wu Hongxia Ge Rongjun Cheng 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第1期192-198,共7页
Based on the fact that the electronic throttle angle effect performs well in the traditional car following model,this paper attempts to introduce the electronic throttle angle into the smart driver model(SDM)as an acc... Based on the fact that the electronic throttle angle effect performs well in the traditional car following model,this paper attempts to introduce the electronic throttle angle into the smart driver model(SDM)as an acceleration feedback control term,and establish an extended smart driver model considering electronic throttle angle changes with memory(ETSDM).In order to show the practicability of the extended model,the next generation simulation(NGSIM)data was used to calibrate and evaluate the extended model and the smart driver model.The calibration results show that,compared with SDM,the simulation value based on the ETSDM is better fitted with the measured data,that is,the extended model can describe the actual traffic situation more accurately.Then,the linear stability analysis of ETSDM was carried out theoretically,and the stability condition was derived.In addition,numerical simulations were explored to show the influence of the electronic throttle angle changes with memory and the driver sensitivity on the stability of traffic flow.The numerical results show that the feedback control term of electronic throttle angle changes with memory can enhance the stability of traffic flow,which shows the feasibility and superiority of the proposed model to a certain extent. 展开更多
关键词 smart driver model(SDM) electronic throttle angle changes with memory(ETSDM) parameter calibration stability analysis
下载PDF
The Disagreement between Anisotropic-Isotropic Diffuse Solar Radiation Models as a Function of Solar Declination: Computing the Optimum Tilt Angle of Solar Panels in the Area of Southern-Italy
20
作者 Emanuele Calabrò 《Smart Grid and Renewable Energy》 2012年第4期253-259,共7页
In this paper a simulation to maximize the global solar radiation on a sloped collecting surface was applied to typical latitudes in the area of southern Italy, to calculate the optimum tilt angle of solar panels on b... In this paper a simulation to maximize the global solar radiation on a sloped collecting surface was applied to typical latitudes in the area of southern Italy, to calculate the optimum tilt angle of solar panels on building structures or large photovoltaic power plants located in that geographical area. Indeed, the area of southern Italy and in particular Sicily and Calabria are the top of European locations for acquiring solar energy. Some models of diffuse solar irradiance were taken into account to determine panels inclinations that maximized the impinging solar radiation by means of global horizontal solar radiation data provided from the Italian Institute of ENEA (Italy). An algorithm was used for the simulation providing a set of tilt angles for each latitude. The optimum tilt angle values obtained from the simulation resulted to be strictly related to the model of diffuse solar radiation that was used. Indeed, the disagreement between the values obtained using anisotropic models of diffuse solar radiation and those obtained from the isotropic model resulted to decrease significantly with increasing solar declination, showing that the isotropic model can be reliable only in summer months. 展开更多
关键词 Global SOLAR Radiation DIFFUSE SOLAR Irradiance ISOTROPIC model Optimum Tilt angle SOLAR Panel
下载PDF
上一页 1 2 162 下一页 到第
使用帮助 返回顶部