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Experimental investigation of discharge coefficient of a converging nozzle for supercritical kerosene 认领 引用
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作者 Zhisheng WANG Yuguang JIANG +3 位作者 Xudong LONG Rongxiao DONG Jintao JIANG Wei FAN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第7期313-330,共18页
In advanced aeroengines,hydrocarbon fuel is used as coolant in the thermal management system,which may turn to supercritical before injected into the combustor.Inside the inj ecting nozzle,supercritical hydrocarbon fu... In advanced aeroengines,hydrocarbon fuel is used as coolant in the thermal management system,which may turn to supercritical before injected into the combustor.Inside the inj ecting nozzle,supercritical hydrocarbon fuel may experience phase transition because of the sharp expansion,which triggers violent variations in fuel thermal properties.Thus,conventional nozzle design is faced with serious challenges.In this work,the discharge coefficient(Ca)of a converging nozzle for the supercritical RP-3 aviation kerosene is experimentally investigated,focusing specifically on the effects of violent phase transition on the flow characteristics in advanced aeroengine fuel systems.A high-temperature,high-pressure experimental platform was developed,enabling precise control of the inj ection pressure(1.0-6.6 MPa),temperature(600-740 K),and mass flux(0.40-1.59 kg·cm-2·s-1).Experimental results demonstrate that Cd firstly increases then decreases in the liquid-two phase-supercritical transition,instead of keeping constant.It is noticed part of Cd values with two-phase outflow even exceeds 1,which proves the limitations of conventional isentropic assumptions.Further thermodynamic analysis reveals that fluid density and isentropic compressibility at the nozzle exit are two critical parameters influencing the discharge coefficient.Particularly,isentropic compressibility shows the strongest correlation and is identified as the dominant factor.Finally,a predictive model of Cd is proposed based on the real-fluid thermophysical data and a modified ideal gas framework,the precision of which has been validated in the following conditions:The reduced injection temperature ranges from 1.02 to 1.22,and the reduced injection pressure ranges from 1.0 to 2.92.It reveals deeper understanding of the flow behavior in the liquid-two phase-supercritical transition and provides enhanced guidance for the nozzle design with supercritical kerosene. 展开更多
关键词 Discharge coefficient Isentropic flow Nozzle design RP-3 aviation kerosene Supercritical state
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Distributed Lagrange Multiplier/Fictitious Domain Finite Element Method for a Transient Stokes Interface Problem with Jump Coefficients 认领 引用 被引量：2
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作者 Andrew Lundberg Pengtao Sun +1 位作者 Cheng Wang Chen-song Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2019年第4期35-62,共28页
The distributed Lagrange multiplier/fictitious domain(DLM/FD)-mixed finite element method is developed and analyzed in this paper for a transient Stokes interface problem with jump coefficients.The semi-and fully disc... The distributed Lagrange multiplier/fictitious domain(DLM/FD)-mixed finite element method is developed and analyzed in this paper for a transient Stokes interface problem with jump coefficients.The semi-and fully discrete DLM/FD-mixed finite element scheme are developed for the first time for this problem with a moving interface,where the arbitrary Lagrangian-Eulerian(ALE)technique is employed to deal with the moving and immersed subdomain.Stability and optimal convergence properties are obtained for both schemes.Numerical experiments are carried out for different scenarios of jump coefficients,and all theoretical results are validated. 展开更多
关键词 Transient Stokes interface problem jump coefficients distributed Lagrange multiplier fictitious domain method mixed finite element an optimal error estimate stability
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Experimental investigation of contour blasting in anisotropic rocks under different lateral stress coefficients 认领 引用
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作者 PENG Si-yu LI Xi-bing +2 位作者 LIU Hui-lin WANG Zhao-wei LIANG Li-sha 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第3期1242-1259,共18页
This study aims to analyze the influence of lateral stress coefficient k and anisotropy on the dynamic response and failure characteristics of deep jointed rock masses under contour blasting.Using phyllite as the test... This study aims to analyze the influence of lateral stress coefficient k and anisotropy on the dynamic response and failure characteristics of deep jointed rock masses under contour blasting.Using phyllite as the test material,local contour blasting-unloading experiments are conducted under biaxial conditions.The analysis focuses on the failure characteristics of the tunnel surrounding rock under different k and joint orientations.Results indicate that when k=1,blasting-induced fractures preferentially propagate along the joint direction.As k decreases,these fractures can deviate from the joint direction and extend toward zones of higher local stress.This tendency is particularly evident when the high-stress direction aligns with the tunnel contour,enabling fracture penetration through closely spaced contour blastholes.During the unloading,blasting-induced circumferential fractures undergo further shear failure,while radial fractures are compacted and closed.The failure of tunnel sidewalls is primarily controlled by circumferential stress concentration and anisotropic compressive strength,whereas failure at the tunnel crown is mainly governed by blasting stresses and the anisotropic tensile strength of the rock mass.This study proposes conditions for the initiation and coalescence of blasting-induced fractures,providing a theoretical basis for contour blasting and support design in anisotropic rock masses. 展开更多
关键词 laboratory experiment contour blasting excavation unloading failure characteristics lateral stress coefficient anisotropic rocks
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Combined value of apparent diffusion coefficient-standardized uptake value max in evaluation of post-treated locally advanced rectal cancer 认领 引用 被引量：5
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作者 Davide Ippolito Davide Fior +5 位作者 Chiara Trattenero Elena De Ponti Silvia Drago Luca Guerra Cammillo Talei Franzesi Sandro Sironi 《World Journal of Radiology》 2015年第12期509-520,共12页
AIM:To assess the clinical diagnostic value of functional imaging,combining quantitative parameters of apparent diffusion coefficient(ADC) and standardized uptake value(SUV)max,before and after chemo-radiation therapy... AIM:To assess the clinical diagnostic value of functional imaging,combining quantitative parameters of apparent diffusion coefficient(ADC) and standardized uptake value(SUV)max,before and after chemo-radiation therapy,in prediction of tumor response of patients with rectal cancer,related to tumor regression grade at histology.METHODS:A total of 31 patients with biopsy proven diagnosis of rectal carcinoma were enrolled in our study.All patients underwent a whole body 18FDG positron emission tomography(PET)/computed tomography(CT) scan and a pelvic magnetic resonance(MR)examination including diffusion weighted(DW) imaging for staging(PET1,RM1) and after completion(6.6 wk)of neoadjuvant treatment(PET2,RM2).Subsequently all patients underwent total mesorectal excision and the histological results were compared with imaging findings.The MR scanning,performed on 1.5 T magnet(Philips,Achieva),included T2-weighted multiplanar imaging and in addition DW images with b-value of 0 and 1000 mm^2/s.On PET/CT the SUVmax of the rectal lesion were calculated in PET1 and PET2.The percentage decrease of SUVmax(△SUV) and ADC(△ADC) values from baseline to presurgical scan were assessed and correlated with pathologic response classified as tumor regression grade(Mandard's criteria;TRG1 = complete regression,TRG5 = no regression).RESULTS:After completion of therapy,all the patients were submitted to surgery.According to the Mandard's criteria,22 tumors showed complete(TRG1) or subtotal regression(TRG2) and were classified as responders;9tumors were classified as non responders(TRG3,4 and5).Considering all patients the mean values of SUVmax in PET 1 was higher than the mean value of SUVmax in PET 2(P < 0.001),whereas the mean ADC values was lower in RM1 than RM2(P < 0.001),with a △SUV and △ADC respectively of 60.2%and 66.8%.The best predictors for TRG response were SUV2(threshold of4.4) and ADC2(1.29 × 10-3 mm^2/s) with high sensitivity and specificity.Combining in a single analysis both the obtained median value,the positive predictive value,in predicting the different group category response in related to TRG system,presented R^2 of 0.95.CONCLUSION:The functional imaging combining ADC and SUVmax in a single analysis permits to detect changes in cellular tissue structures useful for the assessment of tumour response after the neoadjuvant therapy in rectal cancer,increasing the sensitivity in correct depiction of treatment response than either method alone. 展开更多
关键词 Advanced rectal cancer Functional imaging FDG-PET/CT Magnetic resonance imaging Apparent diffusion coefficient Neoadjuvant treatment Tumor regression grade
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Effect of Curing Age on Chloride Diffusion Coefficient of Recycled Aggregate Concrete Subjected to Compressive Stresses 认领 引用 被引量：2
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作者 Tang Jinzhi Wu Jin +2 位作者 Wang Wenjian Wang Zhe Wu Guanzheng 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2018年第2期326-333,共8页
The effect of curing age on chloride diffusion coefficient of recycled aggregate concrete subjected to different compressive stresses was investigated.A compression loading setup was both designed and fabricated.The c... The effect of curing age on chloride diffusion coefficient of recycled aggregate concrete subjected to different compressive stresses was investigated.A compression loading setup was both designed and fabricated.The chloride diffusion coefficients of recycled aggregate concrete under compressive stresses were measured by the rapid chloride ion migration(RCM)method.The experimental results show that the chloride diffusion coefficients of recycled aggregate concrete(RAC)under different compressive stress ratios generally decrease with the increase of curing age.For RAC subjected to the same compressive stress ratios,the chloride diffusion coefficients approximately have power functions with curing ages and the relationship models are proposed.Moreover,the influence of curing age on chloride diffusion coefficient firstly decreases and then increases as the compressive stress ratio increases. 展开更多
关键词 recycled aggregate concrete(RAC) chloride diffusion coefficient curing age compressive stress ratio rapid chlorideion migration(RCM) method
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Adaptive implementation of multi-branch convolution with fusion coefficients based on reconfigurable array 认领 引用
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作者 Liu Dongyue Jiang Lin +2 位作者 Wang Mei Li Yuancheng Hao Juan 《High Technology Letters》 EI CAS 2026年第1期39-48,共10页
Reconfigurable array architecture has become an important hardware platform for edge-side deployment of convolutional neural networks due to their high parallelism and flexible programmability.However,traditional mult... Reconfigurable array architecture has become an important hardware platform for edge-side deployment of convolutional neural networks due to their high parallelism and flexible programmability.However,traditional multi-branch convolutional networks suffer from computational redundancy,high memory access overhead,and inefficient branch fusion.Therefore,this paper proposes an adaptive multi-branch convolutional module(AMBC)that integrates software-hardware co-optimization.During training,the learnable fusion coefficients are introduced to enable adaptive fusion of multi-scale features,while in the inference phase,the multiple branches and their normalization parameters are merged with the fusion coefficients into a single 3×3 convolutional kernel through operator fusion.On the SIREA-288 reconfigurable platform,compared with unoptimized multi-branch networks,the proposed AMBC reduces external memory accesses by 47.91%and inference latency by 47.20%,achieving a 1.90×speedup.This approach maximizes the utilization of the reconfigurable logic while minimizing both reconfiguration and data-movement overheads in edge inference. 展开更多
关键词 reconfigurable array processor structural re-parameterization model compression fusion coefficients edge-side inference acceleration hardware-software co-optimization
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Apparent diffusion coefficient of kidneys with non-contrast magnetic resonance angiography for functional and anatomical assessment in renal artery stenosis 认领 引用
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作者 Hira Lal Surabhi Agarwal +7 位作者 Kaushik Ponmalai Raghunandan Prasad Dharmendra S Bhadauria Sanjay Gambhir Swagata Mandal Sandeep Kumar Priyank Yadav Pinky Jowel 《World Journal of Methodology》 2026年第1期198-210,共13页
BACKGROUND Renal artery stenosis(RAS)is a vascular disorder linked to secondary hypertension,chronic kidney disease,and renal failure due to interstitial fibrosis.Early diagnosis is crucial as RAS-induced hypertension... BACKGROUND Renal artery stenosis(RAS)is a vascular disorder linked to secondary hypertension,chronic kidney disease,and renal failure due to interstitial fibrosis.Early diagnosis is crucial as RAS-induced hypertension responds well to angioplasty.Non-invasive imaging techniques,including non-contrast magnetic resonance angiography(NC-MRA),help assess RAS without contrast-related risks.Diffusion-weighted MR imaging(DW-MRI)has emerged as a promising method for evaluating kidney function by measuring the apparent diffusion coefficient(ADC),which correlates with renal pathology.AIM To compare ADC values in hypertensive,RAS,and healthy kidneys,assess the correlation between ADC and stenosis severity,and evaluate its relationship with split glomerular filtration rate(GFR).METHODS This prospective observational study which included 86 patients with suspected RAS and twenty normal healthy controls underwent NC-MRA on a 3T-MR-Scanner followed by DW-MRI at b values of 0 and 1000 seconds/mm2 in the transverse plane.ADC maps were created using Functool.ADC values were measured in the cortex and medulla of each kidney's upper,middle,and lower pole,and the average ADC(ADCavg)for cortex and medulla calculated.In patients with RAS,degree of stenosis(DOS)was calculated on NC-MRA.The ADC of 212 kidneys was compared,and the relationship between DOS and ADC was established.In addition,split GFR was calculated in 30 kidneys using 99mTc-DTPA,and correlated with ADC value.The ADC values of kidneys with and without RAS were compared using the Student’s t-test.The correlation between ADC and stenosis severity was assessed by Spearman’s test,while the relationship between ADC and split GFR was evaluated using Pearson’s test.A P value<0.05 was considered statistically significant.RESULTS RAS was detected in 58 of 86(67.44%)hypertensive patients(81 of 172 kidneys),and the ADCavg(P=0.044)was significantly lower in RAS kidneys than in kidneys with normal arteries and essential hypertension and healthy controls.CONCLUSION DW-MRI can be a useful non-invasive technique to estimate the kidney’s functional status in RAS patients.It can be used as a complementary assessment tool with NC-MRA to triage patients in need of interventional management. 展开更多
关键词 Renal artery stenosis Diffusion weighted imaging Apparent diffusion coefficient Magnetic resonance imaging Non-contrast renal magnetic resonance angiography Hypertension
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Bridging machine learning and CosMo-SAC for accurate prediction of infinite dilute activity coefficients of binary mixtures 认领 引用 被引量：1
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作者 Yuxin Qiu Guzhong Chen +3 位作者 Qian Liu Zhiwen Qi Kake Zhu Zhen Song 《ENGINEERING Chemical Engineering》 SCIE EI CAS CSCD 2026年第1期55-65,共11页
Infinite dilution activity coefficient(γ∞)is a key thermodynamic parameter in solvent design for chemical processes.Although conductor-like screening model for segment activity coefficient(COSMO-SAC)exhibits stro... Infinite dilution activity coefficient(γ∞)is a key thermodynamic parameter in solvent design for chemical processes.Although conductor-like screening model for segment activity coefficient(COSMO-SAC)exhibits strong prior predictive capabilities,its estimations are sometimes only qualitative rather than quantitative.Another limitation of COSMO-SAC arises from the reliance on time-intensive quantum chemistry calculations,which restricts its scalability for large-scale solvent screening.To overcome these issues,this study integrates COSMO-SAC with machine learning for accurate γ∞ prediction of binary mixtures.By bypassing the necessity for quantum chemistry calculations,the multi-task machine learning model could rapidly predict the surface charge density distribution(o-profiles)and molecular cavity volume(Vcosmo)of molecules and ions,while accurately distinguishing isomers.Four adjustable parameters of COSMO-SAC are optimized using more than 20000 experimental data points of γ,and residual systematic errors are further corrected with the boosting ensemble strategy to improve the model performance.The resulting hybrid model reduces the mean absolute error from 0.944 to 0.102(R2=0.969),representing an 89%improvement,while preserving the physicochemical interpretability of model.This accurate and efficient approach broadens the practical applicability of o-profiles and Vcosmo prediction,as well as γ∞ calculations based on COSMO-SAC,facilitating the high-throughput solvent screening for diverse chemical engineering applications. 展开更多
关键词 infinite dilution activity coefficient COSMO-SAC machine learning solvent design multitask learning
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Prediction of pressure coefficient distributions for basic aerodynamic configurations via point cloud characterization 认领 引用 被引量：1
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作者 Qiming Guan Weiwei Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第7期19-35,共17页
Data-driven approaches have shown great advantage in rapidly and accurately predicting pressure coefficient distributions,which is of crucial importance to efficient aircraft design.Nevertheless,most data-driven appro... Data-driven approaches have shown great advantage in rapidly and accurately predicting pressure coefficient distributions,which is of crucial importance to efficient aircraft design.Nevertheless,most data-driven approaches still encounter limitations in characterizing diverse aerodynamic configurations and adapting to varying grid densities,which have hindered their engineering applicability.In response to these challenges,this work adopts point clouds,a specific type of geometric data structure that is inherently suitable for uniformly characterizing diverse 2D/3D geometric shapes as the input for deep learning-based prediction of pressure coefficient distribution.By augmenting the dimensions of point cloud coordinates for local feature enhancement and utilizing the symmetric function“max pooling”to extract global features,the proposed aerodynamic model establishes the mapping between point cloud coordinates and pressure coefficients.Basic aerodynamic configurations like airfoils and wings are employed as test cases,the results demonstrate that the proposed model achieves both high accuracy and robust generalizability across variable geometries.For class-shape transformation-perturbed airfoils,the prediction error can be reduced to one-third of that of the conventional parameterization-based model.For airfoils selected in the University of Illinois Urbana-Champaign airfoil dataset,among which airfoil profiles are widely distributed,the average error of the proposed approach remains approximately 1.5%,whereas the parameterization-based model may fail.For wings,the prediction error still stays below 2.5%.Finally,the model exhibits strong robustness and generalizability across different point cloud densities.In conclusion,this work makes a breakthrough in predicting pressure coefficient distribution for variable geometric configurations,establishing the foundational framework for designing a large model capable of predicting distributed aerodynamic loads in aerospace applications. 展开更多
关键词 Data-driven Deep learning Pressure coefficient distribution prediction Point cloud Point cloud-based machine learning
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Determination of Potential Runoff Coefficient Using GIS and Remote Sensing 认领 引用 被引量：2
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作者 Ragab Khalil 《Journal of Geographic Information System》 2017年第6期752-762,共11页
Flash floods in arid environments are a major hazard feature to human and to the infrastructure. Shortage of accurate environmental data is main reason for inaccurate prediction of flash flooding characteristics. The ... Flash floods in arid environments are a major hazard feature to human and to the infrastructure. Shortage of accurate environmental data is main reason for inaccurate prediction of flash flooding characteristics. The curve number (CN) is a hydrologic number used to describe the storm water runoff potential for drainage area. This study introduces an approach to determine runoff coefficient in Jeddah, Saudi Arabia using remote sensing and GIS. Remote sensing and geographic information system techniques were used to obtain and prepare input data for hydrologic model. The land cover map was derived using maximum likelihood classification of a SPOT image. The soil properties (texture and permeability) were derived using the soil maps published my ministry of water and agriculture in Saudi Arabia. These soil parameters were used to classify the soil map into hydrological soil groups (HSG). Using the derived information within the hydrological modelling system, the runoff depth was predicted for an assumed severe storm scenario. The advantages of the proposed approach are simplicity, less input data, one software used for all steps, and its ability to be applied for any site. The results show that the runoff depth is directly proportional to runoff coefficient and the total volume of runoff is more than 136 million cubic meters for a rainfall of 103.6 mm. 展开更多
关键词 Potential Runoff Coefficient (PRC) GIS Remote Sensing Hydrological Soil Group (HSG) Digital Elevation Model (DEM) Land Use
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A predictive modeling for the variation of orifice throttling coefficient of hydraulic spool valve caused by erosion behavior 认领 引用
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作者 Xiaochao Liu Dingbo Li +4 位作者 Honghui Liao Peiyao Hou Rui Nie Pengyuan Qi Zongxia Jiao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2026年第2期323-332,共10页
Hydraulic spool valves are crucial components of hydraulic systems.Solid pollution particles mixed in hydraulic oil could result erosion wear of the valve orifice,then lead to a decrease in the performance of valves.M... Hydraulic spool valves are crucial components of hydraulic systems.Solid pollution particles mixed in hydraulic oil could result erosion wear of the valve orifice,then lead to a decrease in the performance of valves.Most studies focused on analyzing the influencing factors and mechanism of erosion wear,while a few considered its evolution,which is the basis for predicting orifice throttling coefficient.According to the variation of orifice throttling coefficient,compensating control could be applied to the hydraulic valves to improve its control performance,and the service life of the spool could also be predicted.In this study,an orifice erosion rate model using finite element analysis(FEA) simulation was firstly established based on the E/CRC erosion model,which mainly consisted of two easily obtainable parameters in hydraulic systems:spool opening and pressure difference.The orifice throttling coefficient prediction model was further established by combining orifice erosion rate model and worn profile model,which model could predict the throttling coefficient and output flow of hydraulic spool valves in real time.The erosion experiments were carried out,and the worn morphologies of orifice positions were also characterized and analyzed,the results showed that the model could accurately predict the orifice erosion rate and the orifice throttling coefficient,the maximum relative error between the prediction model and the experimental measurements is 9.11%.The findings of this study ensure the accurate prediction of the impact of erosion wear and provide guidance for improving the control performance of hydraulic valves. 展开更多
关键词 Erosion wear Valve orifice Orifice throttling coefficient Finite element analysis
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Experimental and numerical investigation on the evolution of Taylor-Quinney coefficient in 42CrMo steel 认领 引用
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作者 Wei Qi Longkang Li +4 位作者 Shengxin Zhu Jianguo Li Manxi Chen Qinglei Zeng Hao-Sen Chen 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第5期239-254,共16页
42CrMo steel was studied in this paper on its thermomechanical behavior when subjected to dynamic compression,utilizing in-situ dynamic tests and crystal plasticity finite element method(CPFEM)simulations.A split Hopk... 42CrMo steel was studied in this paper on its thermomechanical behavior when subjected to dynamic compression,utilizing in-situ dynamic tests and crystal plasticity finite element method(CPFEM)simulations.A split Hopkinson pressure bar,combined with high-speed infrared thermography,was employed to simultaneously record the mechanical response and corresponding temperature evolution,enabling the derivation of the Taylor-Quinney coefficient(TQC).To explore the impact of texture orientation on thermomechanical behavior,a dislocation density-based CPFEM model was applied to analyze the plastic deformation process.The findings demonstrate a satisfactory consistency between numerical predictions and experimental results achieved by the dislocation density-based CPFEM.Simulations of four typical textures demonstrated that texture,through changes in the activated slip systems,significantly influences the evolution of the TQC.These findings contribute valuable insights to the TQC database,enhancing our understanding of material behavior under dynamic loading conditions. 展开更多
关键词 42CrMo Taylor-Quinney coefficient Crystal plasticity Texture effect
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High-precision color crosstalk coefficient calibration method based on phase error estimation 认领 引用
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作者 FENG Lu-yuan LIANG Jian +3 位作者 WANG Xiang-jun ZHAO Zong-yang CHEN Yi-fan WU Bin 《中国光学（中英文）》 EI CAS CSCD 北大核心 2026年第3期745-753,共9页
Color-coded fringe patterns have emerged as a key technique for enabling real-time three-dimen-sional(3D)shape measurement in fringe projection profilometry(FPP).However,color crosstalk inherent in color cameras remai... Color-coded fringe patterns have emerged as a key technique for enabling real-time three-dimen-sional(3D)shape measurement in fringe projection profilometry(FPP).However,color crosstalk inherent in color cameras remains a significant factor limiting measurement accuracy.To mitigate this issue,a high-pre-cision calibration method for color crosstalk coefficients is proposed to enable effective correction in this pa-per.Specifically,a crosstalk coefficient estimator is developed based on orthogonal phase-shifted fringe pat-terns,and the theoretical relationship between the crosstalk coefficients and phase error is derived.The color orthogonal fringes are then designed to project onto a standard planar target to acquire separated R,G,and B channel patterns.Finally,a particle swarm optimization(PSO)algorithm is introduced to optimize the crosstalk-induced phase errors and calibrate the crosstalk coefficients with high precision.Experimental val-idation based on a standard dual-sphere calibration plate shows that the diameter fitting errors of the two spheres are 0.0191 mm and 0.0160 mm,respectively,and the error in the calculated center-to-center distance is as low as 0.0120 mm,which demonstrate that the proposed method can effectively enhance the measure-ment accuracy and applicability of color cameras in fringe projection technology. 展开更多
关键词 fringe projection profilometry color crosstalk coefficient phase error orthogonal fringe pattern
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Gain-Based Neural Secure Protection Control for Feedforward Nonlinear Systems With Unknown Control Coefficients and Impulsive FDI Attacks 认领 引用
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作者 Debao Fan Qingrong Liu +2 位作者 Rong Su Xianfu Zhang Wenjie Zhang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2026年第5期1068-1081,共14页
This paper proposes a gain-based neural secure protection(GBNSP)control scheme for feedforward nonlinear systems subject to unknown control coefficients and impulsive false data injection(FDI)attacks.Notably,the nonli... This paper proposes a gain-based neural secure protection(GBNSP)control scheme for feedforward nonlinear systems subject to unknown control coefficients and impulsive false data injection(FDI)attacks.Notably,the nonlinear functions of the systems are relaxed to any continuous functions and the control coefficients are permitted to be constants with both unknown sizes and signs,a scenario not covered in existing works.Furthermore,the uncertain abrupt changes in system states caused by impulsive FDI attacks inevitably exacerbate the challenges in control design.To this end,this paper integrates the neural network technique and the gain control method to propose a novel GBNSP control scheme.Specifically,the neural network technique effectively compensates for strong nonlinearities and uncertainties,while the gain control method quantifies the tolerable frequency of impulsive FDI attacks and avoids the tedious design procedures.It is shown that,under the designed GBNSP controller,all closed-loop signals remain bounded and the system states eventually converge to an adjustable neighborhood near the origin.Moreover,an enhanced GBNSP control scheme incorporates an improved gain scaling mechanism to withstand unknown external disturbances.In the end,the effectiveness and practicality of the proposed scheme are validated by a theoretical example and a practical example. 展开更多
关键词 Feedforward nonlinear systems gain scaling control impulsive FDI attacks neural secure protection control unknown control coefficients
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Azimuthal elastic impedance-based Fourier coefficient variation with angle inversion for fracture weakness 认领 引用 被引量：14
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作者 Lin Li Jia-Jia Zhang +1 位作者 Xin-Peng Pan Guang-Zhi Zhang 《Petroleum Science》 SCIE CAS CSCD 2020年第1期86-104,共19页
Quantitative inversion of fracture weakness plays an important role in fracture prediction.Considering reservoirs with a set of vertical fractures as horizontal transversely isotropic media,the logarithmic normalized ... Quantitative inversion of fracture weakness plays an important role in fracture prediction.Considering reservoirs with a set of vertical fractures as horizontal transversely isotropic media,the logarithmic normalized azimuthal elastic impedance(EI)is rewritten in terms of Fourier coefficients(FCs),the 90°ambiguity in the azimuth estimation of the symmetry axis is resolved by judging the sign of the second FC,and we choose the FCs with the highest sensitivity to fracture weakness and present a feasible inversion workflow for fracture weakness,which involves:(1)the inversion for azimuthal EI datasets from observed azimuthal angle gathers;(2)the prediction for the second FCs and azimuth of the symmetry axis from the estimated azimuthal EI datasets;and(3)the estimation of fracture weakness combining the extracted second FCs and azimuth of the symmetry axis iteratively,which is constrained utilizing the Cauchy sparse regularization and the low-frequency regularization in a Bayesian framework.Tests on synthetic and field data demonstrate that the 90°ambiguity in the azimuth estimation of the symmetry axis has been removed,and reliable fracture weakness can be obtained when the estimated azimuth of the symmetry axis deviates less than 30°,which can guide the prediction of fractured reservoirs. 展开更多
关键词 Fracture weakness Azimuth of the symmetry axis Azimuthal Fourier coefficients HTI Azimuthal elastic impedance
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Soliton Interactions and Collision Dynamics in a Variable-Coefficient Coupled Nonlocal Nonlinear Schrödinger Systems 认领 引用 被引量：1
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作者 Xinnan Cui Zhiyang Zhang +2 位作者 Muwei Liu Fenghua Qi Wenjun Liu 《Chinese Physics Letters》 SCIE EI CAS CSCD 2025年第10期68-74,共7页
The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations ... The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations are first obtained.By assigning different functions to the variable coefficients,we obtain V-shaped,Y-shaped,wave-type,exponential solitons,and so on.Next,we reveal the influence of the real and imaginary parts of the wave numbers on the double-hump structure based on the soliton solutions.Finally,by setting different wave numbers,we can change the distance and transmission direction of the solitons to analyze their dynamic behavior during collisions.This study establishes a theoretical framework for controlling the dynamics of optical fiber in nonlocal nonlinear systems. 展开更多
关键词 two soliton solutions soliton interactions assigning different functions collision dynamics nonstandard hirota bilinear methodthe nonstandard hirota bilinear method variable coefficient coupled nonlocal nonlinear schr dinger systems coupled nonlocal nonlinear schr dinger equations variable coefficients
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Role of diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient in subtyping renal cell carcinoma 认领 引用
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作者 Hira Lal Pinky Jowel +9 位作者 Pragati Verma Athar Shamim Raghunandan Prasad Anuradha Singh Uday P Singh Sanjoy K Sureka Farhana Siddiqui Manoj Jain Aneesh Srivastava Priyank Yadav 《World Journal of Radiology》 2026年第5期67-76,共10页
BACKGROUND Diffusion-weighted magnetic resonance imaging(DWI)has emerged as a noncontrast functional imaging technique for renal mass characterization.Its role in differentiating histopathological subtypes of renal ce... BACKGROUND Diffusion-weighted magnetic resonance imaging(DWI)has emerged as a noncontrast functional imaging technique for renal mass characterization.Its role in differentiating histopathological subtypes of renal cell carcinoma(RCC)remains an area of active investigation.AIM To evaluate the role of DWI and apparent diffusion coefficient(ADC)values in differentiating histopathological subtypes of RCC.METHODS In this prospective observational study,127 patients with histopathologically proven RCC who underwent preoperative magnetic resonance imaging(MRI)including DWI were analyzed.Diffusion-weighted imaging was performed using b values of 0 second/mm2 and 1000 seconds/mm2,and ADC maps were generated.ADC values were measured from solid tumor components and compared among RCC subtypes.Statistical analysis included subgroup comparisons and receiver operating characteristic curve analysis to assess the ability of ADC values to differentiate clear cell RCC(ccRCC)from non-ccRCC.RESULTS Of the 127 RCCs,97(76.4%)were ccRCC,24(18.9%)papillary RCC,and 6(4.7%)chromophobe RCC.The mean ADC value of ccRCC[(1.391±0.271)×10-3mm2/second]was significantly higher than that of papillary RCC[(0.876±0.293)×10-3mm2/second;P<0.001]and chromophobe RCC[(1.059±0.369)×10-3mm2/second;P=0.04].No significant difference was observed between papillary and chromophobe RCC(P=0.396).When grouped,ccRCC demonstrated a significantly higher mean ADC value compared with non-ccRCC[(1.391±0.271)×10-3mm2/second vs(0.915±0.312)×10-3mm2/second;P<0.001].Receiver operating characteristic analysis yielded an area under the curve of 0.889(95%confidence interval:0.804-0.975).An ADC threshold of 1.08×10-3mm2/second achieved 90%sensitivity and 83%specificity for identifying ccRCC.CONCLUSION DWI with quantitative ADC analysis reliably differentiates clear cell from non-ccRCC and demonstrates significant correlation with RCC subtype and tumor grade.DWI serves as a valuable adjunct to conventional MRI,particularly in patients with contraindications to contrast administration. 展开更多
关键词 Renal cell carcinoma Diffusion-weighted imaging Apparent diffusion coefficient Magnetic resonance imaging Tumor subtyping
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The Asymptotics of Fourier Coefficients Associated to Automorphic Representations over a Certain Sparse Sequence 认领 引用
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作者 Guodong HUA 《Journal of Mathematical Research with Applications》 CSCD 2026年第3期313-332,共20页
In the present paper,we investigate the asymptotics of Fourier coefficients associated to automorphic representations on a specific sparse sequence.For any fixed integer k≥2,we establish the asymptotic distribution o... In the present paper,we investigate the asymptotics of Fourier coefficients associated to automorphic representations on a specific sparse sequence.For any fixed integer k≥2,we establish the asymptotic distribution of absolute values of Fourier coefficients arising from the automorphic representations on the sequence of k-free integers.These results refine and generalize the previous work in this direction. 展开更多
关键词 automorphic representations automorphic L-functions Fourier coefficients functo-riality
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A variable coefficient second-degree Abel equation method for the complex Ginzburg-Landau equation with anti-cubic nonlinearity 认领 引用
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作者 Harun Biçer 《Communications in Theoretical Physics》 SCIE CAS CSCD 2026年第6期39-51,共13页
This paper introduces a novel analytical technique called the "Variable Coefficient Second Degree Generalized Abel equation Method"(VCSDGAE),designed to tackle the complex Ginzburg-Landau equation.Unlike con... This paper introduces a novel analytical technique called the "Variable Coefficient Second Degree Generalized Abel equation Method"(VCSDGAE),designed to tackle the complex Ginzburg-Landau equation.Unlike conventional methods that depend on constant coefficient ordinary differential equations(ODEs) and auxiliary ODEs,our approach employs variable coefficient ODEs within a sub-equation framework.We demonstrate the versatility of this method by successfully applying it to the complex Ginzburg-Landau equation.Through the presentation of analytical solutions,we showcase the method's effectiveness and efficiency,positioning it as a valuable resource for addressing complex nonlinear partial differential equations in fields such as fluid dynamics and wave propagation.The stability of the obtained soliton solutions is established through a linear stability analysis,confirming their robustness against small perturbations.This research not only broadens the spectrum of available analytical techniques but also contributes significantly to the advancement of solutions for various mathematical physics models. 展开更多
关键词 complex Ginzburg-Landau equation variable coefficient second degree generalized Abel equation method analytical solutions nonlinear partial differential equations stability analysis
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Application of Equality Test of Coefficients of Variation to the Heteroskedasticity Test 认领 引用
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作者 Josoa Michel Tovohery André Totohasina Feno Daniel Rajaonasy 《American Journal of Computational Mathematics》 2020年第1期73-89,共17页
The presence of heteroskedasticity in a considered regression model may bias the standard deviations of parameters obtained by the Ordinary Least Square (OLS) method. In this case, several hypothesis tests on the mode... The presence of heteroskedasticity in a considered regression model may bias the standard deviations of parameters obtained by the Ordinary Least Square (OLS) method. In this case, several hypothesis tests on the model under consideration may be biased, for example, CHOW’s coefficient stability test (or structural change test), Student’s t-test and Fisher’s F-test. Most of the heteroscedasticity tests in the literature are based on the comparison of variances. Despite the multiplication of equality tests of coefficients of variation (CVs) that have appeared in the literature, to our knowledge, the first and only use of the coefficient of variation in the detection of heteroskedasticity was offered by Li and Yao in 2017. Thus, this paper offers an approach to determine the existence of heteroskedasticity by a test of equality of coefficients of variation. We verify by a Monte Carlo robustness and performance test that our method seems even better than some tests in the literature. The results of this study contribute to the exploitation of the statistical measurement of CV dispersion. They help technicians economists to better verify their hypotheses before making a scientific decision when making a necessary forecast, in order to contribute effectively to the economic and sustainable development of a company or enterprise. 展开更多
关键词 Heteroskedasticity Tests Equality Test Coefficients of Variation Ordinary Least Square (OLS) Method Linear Regression Analysis of Variance (ANOVA)
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