期刊文献+
共找到86,461篇文章
< 1 2 250 >
每页显示 20 50 100
Second-order sensitivity of eigenpairs in multiple parameter structures
1
作者 陈塑寰 郭睿 孟广伟 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第12期1475-1487,共13页
This paper presents methods for computing a second-order sensitivity matrix and the Hessian matrix of eigenvalues and eigenvectors of multiple parameter structures. Second-order perturbations of eigenvalues and eigenv... This paper presents methods for computing a second-order sensitivity matrix and the Hessian matrix of eigenvalues and eigenvectors of multiple parameter structures. Second-order perturbations of eigenvalues and eigenvectors are transformed into multiple parameter forms,and the second-order perturbation sensitivity matrices of eigenvalues and eigenvectors are developed.With these formulations,the efficient methods based on the second-order Taylor expansion and second-order perturbation are obtained to estimate changes of eigenvalues and eigenvectors when the design parameters are changed. The presented method avoids direct differential operation,and thus reduces difficulty for computing the second-order sensitivity matrices of eigenpairs.A numerical example is given to demonstrate application and accuracy of the proposed method. 展开更多
关键词 multiple parameter structures second-order sensitivity of eigenpairs efficient computational method
在线阅读 下载PDF
Second-order correlated interference with multi-wavelength thermal-light beams
2
作者 De-Sheng Wang Yi-Ning Zhao +5 位作者 Lingxin Kong Su-Heng Zhang Chong Wang Cheng Ren Yuehua Su De-Zhong Cao 《Chinese Physics B》 2026年第2期374-382,共9页
A method for correlating thermal light over a wide spectral range is proposed.A multi-wavelength pseudothermal source,prepared by projecting laser beams of multiple wavelengths(650 nm,635 nm,532 nm,and 473 nm)onto a m... A method for correlating thermal light over a wide spectral range is proposed.A multi-wavelength pseudothermal source,prepared by projecting laser beams of multiple wavelengths(650 nm,635 nm,532 nm,and 473 nm)onto a moving thin ground glass plate,is employed in a double-slit interference experiment.The ground glass plate induces random phase differences between light beams of different wavelengths passing through it.This initial random phase difference significantly influences the high-order intensity correlation functions of multi-wavelength thermal beams.Experimentally,second-order correlated interference patterns,including subwavelength interference,of pseudothermal beams with different wavelengths are observed in the intensity correlation measurements.This method facilitates applications of correlated thermal photons in quantum information processing and quantum imaging. 展开更多
关键词 correlated interference multi-wavelength thermal light second-order correlation function
原文传递
A Fine-Grained RecognitionModel based on Discriminative Region Localization and Efficient Second-Order Feature Encoding
3
作者 Xiaorui Zhang Yingying Wang +3 位作者 Wei Sun Shiyu Zhou Haoming Zhang Pengpai Wang 《Computers, Materials & Continua》 2026年第4期946-965,共20页
Discriminative region localization and efficient feature encoding are crucial for fine-grained object recognition.However,existing data augmentation methods struggle to accurately locate discriminative regions in comp... Discriminative region localization and efficient feature encoding are crucial for fine-grained object recognition.However,existing data augmentation methods struggle to accurately locate discriminative regions in complex backgrounds,small target objects,and limited training data,leading to poor recognition.Fine-grained images exhibit“small inter-class differences,”and while second-order feature encoding enhances discrimination,it often requires dual Convolutional Neural Networks(CNN),increasing training time and complexity.This study proposes a model integrating discriminative region localization and efficient second-order feature encoding.By ranking feature map channels via a fully connected layer,it selects high-importance channels to generate an enhanced map,accurately locating discriminative regions.Cropping and erasing augmentations further refine recognition.To improve efficiency,a novel second-order feature encoding module generates an attention map from the fourth convolutional group of Residual Network 50 layers(ResNet-50)and multiplies it with features from the fifth group,producing second-order features while reducing dimensionality and training time.Experiments on Caltech-University of California,San Diego Birds-200-2011(CUB-200-2011),Stanford Car,and Fine-Grained Visual Classification of Aircraft(FGVC Aircraft)datasets show state-of-the-art accuracy of 88.9%,94.7%,and 93.3%,respectively. 展开更多
关键词 Fine-grained recognition feature encoding data augmentation second-order feature discriminative regions
在线阅读 下载PDF
Photo-crosslinked Second-order Nonlinear Optical Polymer Films with Large Nonlinear Optical Effect and High Thermostability
4
作者 Pan-Pan Qiao Qian-Qian Li Zhen Li 《Chinese Journal of Polymer Science》 2026年第4期1007-1016,I0012,共11页
One of the most significant challenges in commercializing organic second-order nonlinear optical(NLO)materials lies in the inherent trade-off between nonlinearity and stability.A key factor in mitigating this compromi... One of the most significant challenges in commercializing organic second-order nonlinear optical(NLO)materials lies in the inherent trade-off between nonlinearity and stability.A key factor in mitigating this compromise is achieving precise temporal synchronization between the formation of the cross-linked network and the establishment of an optimal non-centrosymmetric alignment of the chromophores.Guided by this principle,we developed a series of NLO polymers incorporating multiple ether chains with low rotational energy barriers,which facilitate molecular reorientation during electric field poling,thereby enhancing the NLO response effectively.Combined with an optimized photocrosslinking strategy,the resulting PX4o/PETMP doped film achieved large macroscopic NLO coefficient of 190 pm·V^(-1)and thermal degradation temperature as high as 120℃.This work offers a universal approach to alleviating the“nonlinearity-stability”trade-off in a wide range of polymeric systems. 展开更多
关键词 second-order nonlinear optical effect Thermostability "Nonlinearity-stability"trade-off PHOTO-CROSSLINKING
原文传递
How does Maternal Absence Affect Adolescent Loneliness?The Role of Rejection Sensitivity and Friendship Quality
5
作者 Jiani Zang Jingxin Zhao Shufen Xing 《International Journal of Mental Health Promotion》 2026年第2期18-30,共13页
Objectives:Loneliness among left-behind adolescents is the most frequently reported emotional problem because of parental neglect.The present study explored the relationship between maternal absence and adolescent lon... Objectives:Loneliness among left-behind adolescents is the most frequently reported emotional problem because of parental neglect.The present study explored the relationship between maternal absence and adolescent loneliness as well as its mechanisms.Methods:The study included 305 participants(Meanage=15.99±0.81,48.9%females)in southeast China,and constructed a chain mediation model to test the roles of rejection sensitivity and friendship quality.Parent absence types,rejection sensitivity,friendship quality,and adolescent loneliness were all assessed with questionnaires.Results:The results showed that adolescents with a mother absent(both-parent absent,mother-only absent)experienced higher levels of loneliness than those with a mother not absent(father-only absent,non-parent absent)(β=0.3137,95%CI[0.0849,0.5425],p<0.01).Besides,the mediating roles of rejection sensitivity(β=0.0344,95%CI[0.0020,0.0808])and friendship quality(β=0.1198,95%CI[0.0049,0.2428])and their chain mediating role were found significant between maternal absence and loneliness(β=0.0245,95%CI[0.0015,0.0575]).Conclusions:These findings have revealed the significant impact of maternal absence on adolescent loneliness and provide important practical implications for educators to reduce adolescent loneliness. 展开更多
关键词 Left behind maternal absence LONELINESS rejection sensitivity friendship quality
在线阅读 下载PDF
Detection Sensitivity of Chip Digital PCR for Staphylococcus aureus
6
作者 Yunxia WANG Xiaxia HOU +1 位作者 Xiaoli WU Wang LIU 《Asian Agricultural Research》 2026年第1期46-50,60,共6页
[Objectives]This study aimed to evaluate the detection sensitivity of Staphylococcus aureus in dairy products utilizing the chip digital PCR(cdPCR)technique.[Methods]Specific primers and probes were designed and synth... [Objectives]This study aimed to evaluate the detection sensitivity of Staphylococcus aureus in dairy products utilizing the chip digital PCR(cdPCR)technique.[Methods]Specific primers and probes were designed and synthesized based on the conserved sequence of the heat-resistant nuclease gene nuc of S.aureus.cdPCR was employed to detect S.aureus,and the sensitivity of this technique was systematically assessed in samples exhibiting low levels of contamination.[Results]cdPCR demonstrated precise quantification when the initial concentration of the sample enrichment solution was equal to or greater than 50 CFU/mL.The detection dynamic range extended across at least five orders of magnitude,with a minimum DNA detection limit of 0.2304 pg/μL.In artificially contaminated cheese samples,the method s lower limit of quantification for detecting S.aureus was 8×10^(2) CFU/g.Regression analysis demonstrated that the gene copy number concentration measured by cdPCR exhibited a strong linear correlation with bacterial contamination concentration across a broad range.[Conclusions]The cdPCR method developed in this study demonstrates high sensitivity and robust quantitative capabilities,offering a reliable technical approach for the precise detection of low-level S.aureus contamination in dairy products. 展开更多
关键词 Staphylococcus aureus Chip digital PCR (cdPCR) sensitivity
在线阅读 下载PDF
Multi-Scale Modelling and Simulation of Graphene–PDMS and CNT–PDMS Flexible Capacitive Pressure Sensors for Enhanced Sensitivity
7
作者 Rama Gautam Nikhil Marriwala +1 位作者 Reeta Devi Dhariya Singh Arya 《Computers, Materials & Continua》 2026年第5期330-346,共17页
In this study,the multi-scale(meso and macro)modelling was used to predict the electric response of the material.Porosity was introduced through a sugar-templating process to enhance compressibility and sensitivity.Me... In this study,the multi-scale(meso and macro)modelling was used to predict the electric response of the material.Porosity was introduced through a sugar-templating process to enhance compressibility and sensitivity.Mean-field homogenization was employed to predict the electrical conductivity of the nanocomposites,which was validated experimentally through I–V characterisation,confirming stable Ohmic behavior.The homogenised material parameters were incorporated into COMSOLMultiphysics to simulate diaphragmdeflection and capacitance variation under applied pressure.Experimental results showed a linear and stable capacitance response at the force magnitude of 0–7 N.The Graphene nanoplatelets(GnP)–Polydimethylsiloxane(PDMS)sensor demonstrated superior sensitivity(0.0032 pF/N)compared to the CNT–PDMS sensor(0.0019 pF/N),attributed to improved filler dispersion and higher effective surface area of GnP.Finite element simulations were further conducted to evaluate stress distribution in a GnP–PDMS-based capacitive sensor integrated into a shoe insole for gait analysis.The results correlated well with experimental capacitance changes,validating the sensor’s mechanical reliability and pressure sensitivity.This comparative study establishes the GnP–PDMS composite as a more effective candidate for low-cost,biocompatible,and high-performance flexible pressure sensors in wearable biomedical and gait monitoring applications. 展开更多
关键词 sensitivity COMSOL simulation GRAPHENE POLYDIMETHYLSILOXANE carbon nanotube pressure sensor gait analysis
在线阅读 下载PDF
Coupled TM-damage modeling and global sensitivity analysis of thermal spalling in heterogeneous rocks
8
作者 Liyuan Liu Mingshan Shi +4 位作者 Derek Elsworth Tao Wang Hongguang Ji Le Zhang Yaohui Li 《International Journal of Mining Science and Technology》 2026年第3期535-552,共18页
Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorpo... Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorporates Weibull distributed heterogeneity to a single fracture in rock,and validate it against ceramic quenching and granite acoustic emission experiments.Distance based generalized sensitivity analysis(DGSA)is applied to quantify the influence and interactions of key parameters,revealing the dominant controls on spalling onset,severity,and damage morphology.The results demonstrate that thermal stress dominates crack initiation and propagation,that lateral constraints can significantly delay and suppress spalling,and that material heterogeneity markedly influences peak stress and damage modes within a certain range of thermal expansion coefficient and has multiple effects on thermal spalling.This study provides a theoretical basis for quantitative assessment and parameter optimization of thermal spalling processes in rock masses. 展开更多
关键词 Rock heterogeneity Thermal spalling Microstructure evolution sensitivity analysis Parameter interaction effect
在线阅读 下载PDF
The application of multi-combinatorial approach in sensitivity improvement of lipid photoacoustic imaging
9
作者 Yi Tan Dongjian Wu +4 位作者 Xiatian Wang Chengbo Liu Mingjian Sun Xiaojing Gong Zhihua Xie 《Journal of Innovative Optical Health Sciences》 2026年第1期96-109,共14页
The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-effic... The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-efficiency excitation and detection elements may improve the imaging sensitivity to a certain extent,the application of the elements is inevitably subject to various limitations in practical applications,particularly during in vivo imaging and endoscopic imaging.In this study,we propose a multi-combinatorial approach to enhance the sensitivity of lipid photoacoustic imaging.The approach involves wavelet transform processing of one-dimensional A-line signals,gradient-based denoising of two-dimensional B-scan images,and finally,threedimensional spatial weighted averaging of the data processed by the previous two steps.This method not only significantly improves the signal-to-noise ratio(SNR)in distinguished feature regions of the image by around 10 dB,but also efficiently extracts weak signals with no distinct features in the original image.After processing with this method,the images acquired under single scanning were compared with those obtained under multiple scanning.The results showed highly consistent image features,with the structural similarity index increasing from 0.2 to 0.8,confirming the accuracy and reliability of the multi-combinatorial approach. 展开更多
关键词 Multi-combinatorial approach extraction of weak signals imaging sensitivity photoacoustic lipid imaging
原文传递
Multi-source validation of ecological sensitivity in the Toraja Highlands,South Sulawesi,Indonesia
10
作者 RIJAL Syamsu WOOF Josua Prayoga F. +5 位作者 DAWA Klara Tasik SAMSURI MASRUROH Heni NURSAPUTRA Munajat A.CHAIRIL AFRILLA Fian 《Journal of Mountain Science》 2026年第2期531-544,共14页
The Toraja Highlands,encompassing Tana Toraja and North Toraja,form the strategic upper reaches of the Saddang Watershed in South Sulawesi,where steep terrain,active land-cover change,and high ecological sensitivity c... The Toraja Highlands,encompassing Tana Toraja and North Toraja,form the strategic upper reaches of the Saddang Watershed in South Sulawesi,where steep terrain,active land-cover change,and high ecological sensitivity converge.This study addresses the need for an objective and validated ecological sensitivity map to support sustainable mountain watershed management.We construct an ecological sensitivity index based on principal component analysis using four key indicators:land cover,vegetation density(NDVI),slope,and rainfall,and evaluate its reliability through multi-source validation.Inputs integrate national elevation models,Landsat 8 imagery,and satellite-derived rainfall.Rainfall represents a multi-year climatology for 2015–2024,whereas land cover and NDVI reflect recent surface conditions derived from a cloud-free 2024 composite.The resulting sensitivity zonation indicates that 41.10%of Tana Toraja and 67.11%of North Toraja fall into the very high sensitivity class,concentrated on steep slopes and intensively converted landscapes.Eventbased spatial cross-validation against independent landslide records yields overall accuracies of 67.65%and 66.67%,while field verification produces Kappa values of 0.847 and 0.871.Stakeholder appraisal further corroborates the mapped patterns.Together,these convergent lines of evidence identify priority areas for reforestation,soil conservation,slope stabilization,and sustainable watershed management.The transparent and reproducible workflow supports evidence-based risk reduction and resilience building in the upper reaches of the Saddang Watershed. 展开更多
关键词 Ecological sensitivity Principal component analysis NDVI Land cover Toraja Highlands Saddang Watershed
原文传递
Investigation of the impact of grain boundary hydrogen concentration on hydrogen embrittlement sensitivity of polycrystalline Fe:Molecular dynamics insights
11
作者 Qiaoyun Tang Wei Gao 《Smart Molecules》 2026年第1期134-144,共11页
This study investigates the influence of hydrogen concentration at grain boundaries on the sensitivity of polycrystalline iron to hydrogen embrittlement using molecular dynamics simulations.These simulations reveal th... This study investigates the influence of hydrogen concentration at grain boundaries on the sensitivity of polycrystalline iron to hydrogen embrittlement using molecular dynamics simulations.These simulations reveal the diffusion behavior of hydrogen atoms at grain boundaries and their consequential impact on the hydrogen embrittlement sensitivity of iron alloys.The findings indicate that as the hydrogen concentration increases,both the yield strength and ultimate tensile strength of Fe-H alloys exhibit a declining trend.Moreover,the capture of hydrogen atoms at the grain boundaries significantly influences the fracture toughness of the material and promotes the formation and propagation of cracks.This study provides a novel theoretical basis for understanding and predicting the hydrogen embrittlement behavior of iron-based materials in hydrogen-rich environments,offering valuable insights for the design and development of Fe alloys with enhanced resistance to hydrogen embrittlement. 展开更多
关键词 grain boundary hydrogen atom concentration hydrogen embrittlement sensitivity molecular dynamics simulation
在线阅读 下载PDF
Exploring patterns and impacts of farmland and construction land upslope in China:based on an integrated slope spectrum and sensitivity model
12
作者 ZHOU Yifan CHAI Ji +2 位作者 JIN Gui ZHANG Hongwei LI Qingbiao 《Journal of Mountain Science》 2026年第2期755-774,共20页
As demand for land resources is rapidly growing nowadays,developing on slope lands has become a way to relieve pressure on flat lands.Although some studies use the concept of slope spectrum to explore the trend of lan... As demand for land resources is rapidly growing nowadays,developing on slope lands has become a way to relieve pressure on flat lands.Although some studies use the concept of slope spectrum to explore the trend of land use upslope,relying solely on the slope spectrum is too broad and prevents deeper research.Therefore,using China's land use and DEM data from 2000 to 2020,our study integrated the slope spectrum and the slope sensitivity coefficient(SSC)calculated by the land use transfer matrix as a new approach and method for understanding the underlying formations and impacts of upslope in farmland and construction land,supporting regional management strategies.The results show that:1)Farmlands were upslope in the South and developed horizontally in the North,and construction lands were upslope nationwide.2)Using the land use transfer matrix and SSC,we classified farmland upslope as passive and active patterns,and construction land upslope as saturation and avoidance patterns based on their land use transfer mechanisms in slope space.Provinces with passive and saturation patterns are mainly located near the east coast.3)Different patterns of upslope have distinct impacts on sustainable development.The passive pattern harms food security while the active pattern can relieve pressure on food security but increases ecological risks.Saturation pattern damages food security,ecological protection,and city livability,but avoidance pattern can promote food security and ecological protection.The findings will serve as an essential reference for developing land use strategies aimed at sustainable development. 展开更多
关键词 Slope spectrum Land use transfer Slope climbing Sustainable land use Spatial heterogeneity sensitivity
原文传递
Dynamic characteristics and sensitivity of water hammer problems in liquid propulsion system using lattice Boltzmann method with entropy limiter
13
作者 Yuqi WEI Xianggeng WEI +4 位作者 Guoqiang HE Xiao ZHAO Jinying YE Xueren WANG Hongyu CHEN 《Chinese Journal of Aeronautics》 2026年第1期18-34,共17页
The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant ... The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant feedlines.The dynamic characteristics of valve-closing water hammer and filling water hammer are investigated by this method,and the sensitivity of filling water hammer is analyzed with a single factor sensitivity analysis with 8 factors and 9 levels and a multi-factor sensitivity analysis with L_(27)(3^(13))orthogonal experiment based on range method.It is found that the solving result of LBM with entropy limiter is basically in good agreement with finite volume method,and using the entropy limiter can eliminate numerical oscillations when solving valve-closing water hammer problems and solve the numerical"blow up"when solving filling water hammer problems.It can be seen that the dynamic characteristics of valve-closing water hammer are relatively simple,while there are many factors that affect the filling water hammer and the degree of these effects varies.The effects on the maximum water hammer pressure are relatively uniform,but those on the water hammer response time vary greatly through the skewness analysis. 展开更多
关键词 Dynamic analysis Lattice Boltzmann method Liquid propulsion system Propellant transfer sensitivity analysis Water hammer
原文传递
Multiparameter hierarchical sensitivity analysis of tilt-to-length coupling noise in Taiji science interferometer
14
作者 Fei Xie Xiaodong Peng +2 位作者 Wenlin Tang Mengyuan Zhao Xiaoshan Ma 《Chinese Physics B》 2026年第1期399-408,共10页
Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant paramete... Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant parameters.To address this challenge,we develop a simulation model of the Taiji scientific interferometer,generating noise datasets under multiparameter conditions.Given the uniqueness of the telescope as well as the convergence behavior of the algorithm,the analysis is structured hierarchically:(i)the telescope level and(ii)the optical bench level.A hierarchical framework combining XGBoost and SHapley Additive exPlanations(SHAP)values is employed to model the intricate relationships between parameters and TTL coupling noise,supplemented by sensitivity analysis.Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level,while the angles of the plane mirrors and beam splitters are most influential at the optical bench level.The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy.This approach offers actionable insights for optimizing the Taiji interferometer design. 展开更多
关键词 space-based gravitational wave detection intrasatellite science interferometer tilt-to-length coupling noise sensitivity analysis
原文传递
EB-Guided Optimization of Heliostat Fields with Validated Projection Losses and HFLCAL Sensitivity
15
作者 Zichang Meng Na Chen +2 位作者 Qi Li Qingyi Liu Hongfei Jiang 《Energy Engineering》 2026年第4期134-153,共20页
Heliostat field design for tower solar thermal plants must jointly address solar geometry,optical losses,and layout optimization under engineering constraints.We develop an end-to-end workflow that(i)adopts a consiste... Heliostat field design for tower solar thermal plants must jointly address solar geometry,optical losses,and layout optimization under engineering constraints.We develop an end-to-end workflow that(i)adopts a consistent East–North–Up(ENU)convention for all plant-and sun-related vectors;(ii)integrates cosine efficiency,projection-based shading and blocking(SB),atmospheric transmittance,and an HFLCAL(heliostat field local calculation)truncation model into a single optical chain;and(iii)couples an Eliminate-Blocking(EB)layout prior with an improved“Cheetah”metaheuristic to search ring topology,mirror sizes,and heights while enforcing spacing,kinematics,and rated-power requirements.Projection-based SB is calibrated against Monte-Carlo ray tracing at representative sun positions,and the HFLCAL truncation model is used to quantify sensitivities to sunshape and error-budget parameters.In a three-phase study(fixed-size baseline,uniform sizing,heterogeneous sizing),the EB-guided optimizer improves annual per-area output relative to a radial baseline and reliably attains a 60 MW target.Under equal evaluation budgets,the proposed optimizer converges faster and with lower variance than GA-and PSO-based baselines,while respecting panel-level peak-flux limits through a smooth penalization of flux violations.The resulting layouts exhibit outward-increasing azimuthal spacing and ring-wise size sharing that are consistent with recent heliostat-field deployment experience.The framework is modular,auditable,and readily adaptable to alternative receivers,sites,and cost-aware objectives. 展开更多
关键词 Heliostat field shading and blocking HFLCAL truncation eliminate-blocking layout metaheuristics solar tower sensitivity analysis
在线阅读 下载PDF
Sensitivity analysis of vibration characteristics and dynamic responses of a tracked vehicle
16
作者 Xun Wang Xue Rui +3 位作者 Jinghong Wang Xiaoting Rui Guoping Wang Pingxin Wang 《Defence Technology(防务技术)》 2026年第3期323-348,共26页
This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation m... This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation method(DDM)with the linear multibody system transfer matrix method(linear MSTMM).The rigid-flexible coupled multibody system dynamics model of a tracked vehicle is established using the linear MSTMM and validated through the modal test.Building upon the existing DDM-based eigenvalue sensitivity analysis method within the linear MSTMM,the DDM is embedded into it to enable programmable and efficient computation of dynamic response sensitivities for mechanical systems.The proposed approach is used to quantitatively evaluate the sensitivities of both natural vibration characteristics(e.g.,natural frequencies and mode shapes)and transient dynamic responses of the tracked vehicle with respect to system parameters,successfully identifying critical structural parameters.Compared to conventional finite difference methods,the developed methodology eliminates sensitivity to perturbation step sizes.The contributions of this work lie in establishing a unified theoretical foundation and analysis framework for guiding dynamics optimization and design of mechanical systems,and extending the applicability of the linear MSTMM to sensitivity analysis of transient dynamic responses. 展开更多
关键词 Tracked vehicle sensitivity analysis Vibration characteristics Dynamic responses Direct differentiation method Linear multibody system transfer matrix method
在线阅读 下载PDF
A novel approach to identify the spatial characteristics of ozone-precursor sensitivity based on interpretable machine learning
17
作者 Huiling He Kaihui Zhao +6 位作者 Zibing Yuan Jin Shen Yujun Lin Shu Zhang Menglei Wang Anqi Wang Puyu Lian 《Journal of Environmental Sciences》 2026年第1期54-63,共10页
To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) po... To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies. 展开更多
关键词 O_(3)-precursor sensitivity Machine learning Extreme gradient boosting model Shapley algorithm Greater bay area
原文传递
Second-Order Adjoint Sensitivity Analysis Methodology for Computing Exactly Response Sensitivities to Uncertain Parameters and Boundaries of Linear Systems: Mathematical Framework 被引量:3
18
作者 Dan Gabriel Cacuci 《American Journal of Computational Mathematics》 2020年第3期329-354,共26页
This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2<sup>nd</sup>-CASAM)” for the efficient and exact computation of 1<sup>st</sup>- and 2<sup>... This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2<sup>nd</sup>-CASAM)” for the efficient and exact computation of 1<sup>st</sup>- and 2<sup>nd</sup>-order response sensitivities to uncertain parameters and domain boundaries of linear systems. The model’s response (<em>i.e.</em>, model result of interest) is a generic nonlinear function of the model’s forward and adjoint state functions, and also depends on the imprecisely known boundaries and model parameters. In the practically important particular case when the response is a scalar-valued functional of the forward and adjoint state functions characterizing a model comprising N parameters, the 2<sup>nd</sup>-CASAM requires a single large-scale computation using the First-Level Adjoint Sensitivity System (1<sup>st</sup>-LASS) for obtaining all of the first-order response sensitivities, and at most N large-scale computations using the Second-Level Adjoint Sensitivity System (2<sup>nd</sup>-LASS) for obtaining exactly all of the second-order response sensitivities. In contradistinction, forward other methods would require (<em>N</em>2/2 + 3 <em>N</em>/2) large-scale computations for obtaining all of the first- and second-order sensitivities. This work also shows that constructing and solving the 2<sup>nd</sup>-LASS requires very little additional effort beyond the construction of the 1<sup>st</sup>-LASS needed for computing the first-order sensitivities. Solving the equations underlying the 1<sup>st</sup>-LASS and 2<sup>nd</sup>-LASS requires the same computational solvers as needed for solving (<em>i.e.</em>, “inverting”) either the forward or the adjoint linear operators underlying the initial model. Therefore, the same computer software and “solvers” used for solving the original system of equations can also be used for solving the 1<sup>st</sup>-LASS and the 2<sup>nd</sup>-LASS. Since neither the 1<sup>st</sup>-LASS nor the 2<sup>nd</sup>-LASS involves any differentials of the operators underlying the original system, the 1<sup>st</sup>-LASS is designated as a “<u>first-level</u>” (as opposed to a “first-order”) adjoint sensitivity system, while the 2<sup>nd</sup>-LASS is designated as a “<u>second-level</u>” (rather than a “second-order”) adjoint sensitivity system. Mixed second-order response sensitivities involving boundary parameters may arise from all source terms of the 2<sup>nd</sup>-LASS that involve the imprecisely known boundary parameters. Notably, the 2<sup>nd</sup>-LASS encompasses an automatic, inherent, and independent “solution verification” mechanism of the correctness and accuracy of the 2nd-level adjoint functions needed for the efficient and exact computation of the second-order sensitivities. 展开更多
关键词 second-order Comprehensive Adjoint sensitivity Analysis Methodology (2nd-CASAM) First-Level Adjoint sensitivity System (1st-LASS) Second-Level Adjoint sensitivity System (2nd-LASS) Operator-Type Response second-order sensitivities to Uncertain Model Boundaries second-order sensitivities to Uncertain Model Parameters
在线阅读 下载PDF
Machine learning approaches for predicting impact sensitivity and detonation performances of energetic materials 被引量:3
19
作者 Wei-Hong Liu Qi-Jun Liu +1 位作者 Fu-Sheng Liu Zheng-Tang Liu 《Journal of Energy Chemistry》 2025年第3期161-171,共11页
Excellent detonation performances and low sensitivity are prerequisites for the deployment of energetic materials.Exploring the underlying factors that affect impact sensitivity and detonation performances as well as ... Excellent detonation performances and low sensitivity are prerequisites for the deployment of energetic materials.Exploring the underlying factors that affect impact sensitivity and detonation performances as well as exploring how to obtain materials with desired properties remains a long-term challenge.Machine learning with its ability to solve complex tasks and perform robust data processing can reveal the relationship between performance and descriptive indicators,potentially accelerating the development process of energetic materials.In this background,impact sensitivity,detonation performances,and 28 physicochemical parameters for 222 energetic materials from density functional theory calculations and published literature were sorted out.Four machine learning algorithms were employed to predict various properties of energetic materials,including impact sensitivity,detonation velocity,detonation pressure,and Gurney energy.Analysis of Pearson coefficients and feature importance showed that the heat of explosion,oxygen balance,decomposition products,and HOMO energy levels have a strong correlation with the impact sensitivity of energetic materials.Oxygen balance,decomposition products,and density have a strong correlation with detonation performances.Utilizing impact sensitivity of 2,3,4-trinitrotoluene and the detonation performances of 2,4,6-trinitrobenzene-1,3,5-triamine as the benchmark,the analysis of feature importance rankings and statistical data revealed the optimal range of key features balancing impact sensitivity and detonation performances:oxygen balance values should be between-40%and-30%,density should range from 1.66 to 1.72 g/cm^(3),HOMO energy levels should be between-6.34 and-6.31 eV,and lipophilicity should be between-1.0 and 0.1,4.49 and 5.59.These findings not only offer important insights into the impact sensitivity and detonation performances of energetic materials,but also provide a theoretical guidance paradigm for the design and development of new energetic materials with optimal detonation performances and reduced sensitivity. 展开更多
关键词 Energetic materials Machine learning Impact sensitivity Detonation performances Feature descriptors Balancing strategy
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部