Spectral Matching Method Research Articles

Rapid Characterization of the Constituents in Shenhua Tablets by UHPLC-Q-Orbitrap-LTQ-MS.

Shenhua Tablet (SHT), a Chinese herbal medicine comprising seven crude drugs, is utilized in the treatment of immunoglobulin A nephropathy (IgAN). However, due to its complex composition, the chemical constituents of SHT in vitro are still incompletely known, which has restricted the comprehensive development and utilization of SHT in clinical practice. In the present study based on ultra-high performance liquid chromatography-quadrupole-orbitrap-linear ion trap mass spectrometry (UHPLC-Q-Orbitrap-LTQ-MS) in data dependent acquisition mode, combining the accurate mass and structural information, the profiling and characterization of chemical constituents in SHT were carried out. The automated spectral matching (of experimental MS2 spectra against library spectra of mzCloud) method with a high mass accuracy (within 5ppm) was used for the rapid identification of compounds. A total of 183 compounds, consisting of 64 flavonoids, 52 terpenoids, 37 organic acids, 6 phenylpropanoids, 5 phenols, and 19 other phytochemicals, were successfully characterized. In addition, the fragmentation pathways and characteristic fragments of some representative compounds were elucidated. The results offered clear insights into its chemical profile, thereby facilitating quality control and advancing pharmacological research.

DEVELOPMENT OF PEAK GROUND ACCELERATION USING A NON-LINEAR APPROACH TO EVALUATE LIQUEFACTION POTENTIAL IN SEI WAMPU BRIDGE, LANGKAT, NORTH SUMATRA, INDONESIA

The design of building structures requires compliance with seismic codes and all their consequences. Based on geotechnical investigation reports, the construction of Sei Wampu Bridge in Langkat, North Sumatra, Indonesia, is located in an area where the soil layers are predominantly sand with shallow water levels because of its proximity to a river and is a high earthquake zone due to the Semangko fault. That condition will affect the potential of liquefaction occurring. This study aims to identify the liquefaction potential in the Sei Wampu Bridge. Based on Indonesian National Standard (SNI) 1726-2019, sites prone to liquefaction are categorized as site class-specific soil (F) and requires site-specific response analysis (SSRA) methods. Non-linear analysis 1-D is chosen to propagate earthquake waves with the software DEEPSOIL V7. The input parameter for soil movement utilizes an average spectral matching method with a minimum of 7 pairs of soil movement selected from the earthquake recording website, PEER Ground Motion Database. The selection of earthquake considers a 1000-year earthquake load return period, or a 7% probability exceeded within 75 years. Site-specific response analysis (SSRA) resulted in a peak ground acceleration (PGA) value for each borehole depth used in liquefaction potential analysis. Using a historical earthquake scenario with a 6.3 Mw shows that the research location has liquefaction potential at 0 m-15 m deep with high vulnerability levels, where the LPI value reaches 36.21.

Spectral Galerkin mode-matching method for applications in photonics.

Many engineered photonic devices can be decomposed into parts where the material properties are independent of one or more spatial variables. Numerical mode-matching methods are widely used to simulate such photonic devices due to the efficiency gained by treating the separated variables analytically. Existing mode-matching methods based on piecewise polynomials are more accurate than those based on the global Fourier basis or low-order finite difference, finite-element schemes, but they may exhibit numerical instability when a large number of eigenmodes are used. To overcome this difficulty, we introduce the spectral Galerkin mode matching method (SGMM) based on a global piecewise-polynomial basis and a Galerkin method to solve the eigenmodes. It is shown that the numerical eigenmodes of SGMM preserve the pseudo-orthogonality of the analytical eigenmodes. This property leads to linear systems that are typically well-conditioned. Numerical examples indicate that SGMM is more stable than other mode matching methods, and gives reliable results even when a large number of eigenmodes are used.

Shake table test and seismic fragility analysis of transmission tower-line system considering duration effect

Although extensive attention has been devoted to the influence of ground motion duration on the seismic performance of various structures, the integration of the duration effect into the seismic analysis of transmission tower-line systems (TTLSs) has been rarely studied, leading to a lack of understanding regarding the relationship between the ground motion duration and the seismic response of TTLSs. This paper aims to quantify the duration effect on the structural performance and seismic fragility of a TTLS through shake table tests and numerical simulations. To achieve this goal, a reduced-scale experimental model of a TTLS is carefully designed and fabricated, and a group of ground motions with contrasting durations is chosen using a spectral matching method. Subsequently, shake table tests are conducted to examine the duration effect on the seismic responses of the TTLS. The recorded data indicates that long-duration ground motions (LDGMs) significantly amplify the seismic responses and have the potential to degrade the structural performance. Furthermore, a validated finite element model of the TTLS is employed to compute its nonlinear responses from elastic behavior to complete plasticity utilizing incremental dynamic analysis. Probabilistic assessments are also conducted to investigate the seismic fragility and loss of the TTLS. The findings reveal higher damage probabilities and more severe losses caused by LDGMs, emphasizing the importance of considering the duration effect in the seismic performance assessment of TTLSs. This investigation contributes to a meaningful exploration for reliably assessing the seismic capacity of TTLSs while accounting for the duration effects.

Numerical comparative study on seismic response of half-span and full-span scaled models of a floating type cable-stayed bridge

This study compares the results of numerical simulations of half-span and full-span cable-stayed bridge models based on the seismic response of the pylons and main girders subjected to earthquake loads. The half-span model represents the most critical condition of the bridge during the construction phase, while the full-span model represents the bridge in operational phase. The three-dimensional finite-element modeling of the two bridge models uses data from the longest existing cable-stayed bridge in Indonesia which was scaled down geometrically to 1/160, using Midas CIVIL software. The Kobe earthquake record from the PEER Strong Motion Database was used in this study by applying the spectral matching method to modify its acceleration according to the location of the existing bridge being analyzed. This study also examines the influence of the directional effects of earthquake load relative to the longitudinal axis of the bridge, namely 0, 45, and 90 degrees. The results of the analysis show that for the half-span bridge model, the maximum acceleration occurs at the top of the pylon due to earthquake excitation at 90 degrees direction, with an amplification factor of 4.658, while the amplification factor in full-span bridge conditions is only 2.44. In addition, in both the half-span and full-span bridge models, the largest acceleration amplification factor occurs in the main girder that is caused by earthquake excitation at 90 degrees direction. The largest transverse displacement occurs at the free ends of the main girder, but not in the full-span model. The results of the study indicate that during the detailed design process the designer has to consider the effect of earthquake on the strength and stability of the bridge during construction especially if the balanced cantilever method applies.

A Numerical Mode Matching (NMM) Method for Optical Fibers With Kerr Nonlinearity

Recently, the reshaping of the transverse light field profile in nonlinear multimode fibers (MMFs) has attracted great attentions. However, the electromagnetic (EM) fields in such nonlinear media cannot be easily and accurately calculated by using the traditional computational electromagnetics methods due to the nonlinearity of Kerr optical materials in graded-index (GRIN) MMFs. The iterative division method based on the 2.5-D spectral element numerical mode matching (SNMM) method is developed to address this problem. The SNMM method is a semi-analytical method, which can effectively reduce the computational costs to obtain highly accurate solutions. Starting from the numerical results of SNMM, the iterative division method solves electromagnetic fields of the linear-to-nonlinear transition process together iteratively. In this work, several improvements are proposed to extend the SNMM for Kerr optical nonlinear MMFs. The governing equations with anisotropic permittivity with Kerr optical nonlinear media are established in the cylindrical coordinate system. The absorbing boundary condition (ABC) is introduced to replace the perfectly matched layer (PML) so that the eigenmodes of a waveguide can be obtained accurately. Numerical results show the validity, accuracy and advantages of the proposed method in simulated MMFs.

Shape correspondence for cel animation based on a shape association graph and spectral matching

We present an effective spectral matching method based on a shape association graph for finding region correspondences between two cel animation keyframes. We formulate the correspondence problem as an adapted quadratic assignment problem, which comprehensively considers both the intrinsic geometric and topology of regions to find the globally optimal correspondence. To simultaneously represent the geometric and topological similarities between regions, we propose a shape association graph (SAG), whose node attributes indicate the geometric distance between regions, and whose edge attributes indicate the topological distance between combined region pairs. We convert topological distance to geometric distance between geometric objects with topological features of the pairs, and introduce Kendall shape space to calculate the intrinsic geometric distance. By utilizing the spectral properties of the affinity matrix induced by the SAG, our approach can efficiently extract globally optimal region correspondences, even if shapes have inconsistent topology and severe deformation. It is also robust to shapes undergoing similarity transformations, and compatible with parallel computing techniques.

A physics‐based spectral matching (PBSM) method for generating fully site‐related ground motions

AbstractThe response spectrum is generally adopted in the seismic design to represent the seismic fortification level, but the structural dynamic analysis requires the ground motions as an input. However, ground motions generated by the traditional spectral matching methods do not have site‐related physical backgrounds for the target site. In this study, a physics‐based spectral matching (PBSM) method is developed to generate fully site‐related broadband ground motions (i.e., the generated ground motions have real physical backgrounds for the target site, including the source process, propagation path, and local site conditions) that are compatible to the target spectrum. In this method, the three‐dimensional (3D) numerical model around the target site is constructed to calculate the strain Green's tensors of all potential source locations using adjoint simulations. The variable space dimension of the seismic source is significantly reduced by applying the self‐similar feature of the multidimension source model, so that the optimization algorithm can be used to search for the rupture process that generates the physics‐based and spectrum‐matched ground motions (abbreviated to PBSM ground motions). The proposed method is applied to the Xiluodu dam in China. Compared with the traditional techniques, the generated ground motions have fully site‐related physical backgrounds and are compatible to the target spectrum. Additionally, as this method generates broadband ground motions based on the deterministic rupture process, any features of ground motions, such as large velocity pulses, can be taken into account throughout the optimization process. This study introduces the deterministic physical backgrounds of earthquakes to performance‐based seismic design and analysis. The proposed method may have a significant application potential in earthquake engineering.

Comparative study of the simulation ground motion by amplitude scale and spectral matching

Dynamic analysis is more accurate than static analysis in determining a response of structure due to earthquake loads. The limitation of this analysis is the lack of recorded ground motion data of an earthquake for the entire territory of Indonesia. Therefore, according to the Indonesian Code, it is permitted to use seismic data from other locations that have similar seismic characteristics. In application, ground motions need to be modified to match the Indonesia design code. There are two modification methods, which are amplitude scaling and spectral matching. Thus, the purpose of this study is to determine the reliability of these two methods. As the result, the response spectra of the ground motion modified by the spectral matching method present a similar pattern to the target response spectra compared to the amplitude scaling method. Ground motions modified by the spectral matching method generate Peak Ground Acceleration (PGA) values almost the same as the target PGA values. In contrast, the modified motions with amplitude scaling provide diverse PGA values that are not the same as the target PGA. From this study, the utilization of the spectral matching method is recommended in modifying ground motion data for dynamic analysis.

Seismic Hazard Maps of Bengkulu City, Indonesia, Considering Probabilistic Spectral Response for Medium and Stiff Soils

Background: This paper presents the extended work of a seismic hazard map for Bengkulu City, Indonesia. In this current study, seismic hazard maps are generated by considering site variations in Bengkulu City, Indonesia. Methods: First, site investigation data is collected. Furthermore, the probabilistic spectral response for Bengkulu City is analysed. The spectral matching method is implemented to obtain appropriate ground motion considering the most dominant earthquake scenario that occurred. A seismic ground response analysis is conducted to obtain several ground motion parameters, such as peak ground acceleration, spectral acceleration values at 0.2 s and 1 s, and ground motion amplification. Results: The results show that peak ground acceleration in the study area is generally within the range of 0.5 to 0.6g. It indicates that most sites in Bengkulu city could undergo strong motion. Spectral accelerations at 0.2 s and 1 s are also dominantly found in the range of 0.9 to 1.2g and the range of 0.5 to 0.7g. Generally, ground motion in the study area could amplify up to 1.1 to 1.5. Conclusion: Spectral acceleration curve for site classes in Bengkulu City shows a similar trend to other spectral accelerations. It indicates that the spectral acceleration proposed in this study could be implemented in the study area.

Chemical Composition of B-type Stars from LAMOST DR5

We present detailed criteria for the classification of subtypes of B-type supergiants and apply them to 97 supergiants chosen manually from the LAMOST DR5 data set. We obtained the physical parameters (effective temperature, surface gravity, projected rotational velocity) and chemical abundances of C and Si for 103 B-type stars, including 62 supergiants. Non-LTE TLUSTY atmospheric models are employed in our analysis. Projected rotational velocities of B-type stars are found to be systematically smaller than those of the old clusters in the Milky Way. The spectral types and luminosity classes of our manually classified B-type stars are consistent with their effective temperatures and surface gravities derived from the model spectral matching method, respectively. The obtained C and Si abundances for most of our B-type stars are subsolar. Our results indicate that a silicon abundance gradient is −0.0419 ± 0.0226 dex kpc−1 in the region of 7.1 kpc ≤ R g ≤ 14.1 kpc, which is in agreement with previous studies.

Improving the accuracy of hydrothermal alteration mapping based on image fusion of ASTER and Sentinel-2A data: a case study of Pulang Cu deposit, Southwest China

Mapping hydrothermal alteration is an important means of mineral exploration, therefore, effective improvement of the accuracy of identification of hydrothermal alteration minerals is a hot topic. In this study, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Sentinel-2A data were selected for the Pulang copper deposit, to improve the accuracy of hydrothermal alteration mineral mapping. Three data fusion methods of Principal Component Analysis (PCA), Gram–Schmidt (GS) and High-Pass Filtering (HPF) were employed, and method of spectral matching was introduced to obtain high spatial resolution and high spectral fidelity fused data. The comparison showed that the HPF fusion method had the best effect. The fused data by the HPF fusion method were then implemented to map hydrothermal alteration minerals by using a multifractal-based method of PCA + Spectrum–Area. Through the verification of a field investigation, the results exhibited a similar hydrothermal alteration distribution, compared with the results obtained from the original ASTER data, but with higher identification accuracy. Therefore, the case study strongly suggests that the image fusion method with spectral matching is an effective tool to increase spatial resolution, while maintaining high spectral fidelity. Thus, it is a valuable and economic method for improving the identification accuracy of hydrothermal alteration minerals. HIGHLIGHTS The spectral matching method was introduced to unify the surface reflectance of ASTER and Sentinel-2A data. Principal Component Analysis (PCA), Gram-Schmidt (GS) and High-Pass Filtering (HPF) methods were employed to fuse AST ER and Sentinel-2A data. The results show that the extraction accuracy of hydrothermal alteration minerals based on AST ER - Sentinel-2A fused data has 6.98% higher than that of original ASTER data.

Analysis and Comparison of Mouse and Human Brain Gangliosides via Two-Stage Matching of MS/MS Spectra.

Glycosphingolipids (GSLs), including gangliosides, are essential components of the cell membrane. Because of their vital biological functions, a facile method for the analysis and comparison of GSLs in biological issues is desired. To this end, a new method for GSL analysis was developed based on two-stage matching of the carbohydrate and glycolipid product ions of experimental and reference MS/MS spectra of GSLs. The applicability of this method to the analysis of gangliosides in biological tissues was verified using human plasma and mouse brains spiked with standards. The method was then used to characterize endogenous gangliosides in mouse and human brains. It was shown that each endogenous ganglioside species had varied lipid forms and that mouse and human brains had different compositions of ganglioside species and lipid forms. Moreover, a 36-carbon ceramide is found to represent the major lipid form for mouse brain gangliosides, while the major lipid form for most human brain gangliosides is a 38-carbon ceramide. This study has verified that the two-stage MS/MS spectral matching method could be used to study gangliosides or GSLs and their lipid forms in complex biological samples, thereby having a broad application.

Method for geostationary satellite thermal infrared data simulation from polar-orbiting MODIS sensors

Simulation of thermal images plays an important role in the pre-evaluation of the data acquisition characteristics of sensors. This work addressed an operational method for the time-series thermal infrared (TIR) data of geostationary satellite simulated from polar-orbiting MODerate resolution Imaging Spectroradiometer (MODIS) sensors based on Radiative Transfer Model (RTM) under cloud-free conditions. The data procedure, including the land surface emissivity (LSE), time-series land surface temperature (LST), time-series atmospheric parameters, sensor performance, can be described as follows. Firstly, MODIS LST product filtering rules are developed due to its data quality. Then, a Diurnal Temperature Cycle (DTC) model with four parameters is used to acquire the time-series LSTs. The spatial and spectral matching method are adopted from MODIS LST&LSE product. A temporal interpolation method is used to obtain the time-series atmospheric parameters from the atmospheric profile provided by European Centre for Medium-Range Weather Forecasts (ECMWF). Then, the time-series TIR data at sensors were modeled using this method. Compared with the time-series TOA brightness temperature of MSG/ SEVIRI geostationary satellite, the results show that the modeling accuracy is achieved with root mean square errors (RMSEs) 2.39K, 2.81K, 1.06K, and 1.29K at MODIS overpass times, and the mean and RMSE are -0.09K and 1.61K for all cloud-free pixels at the UTC time spanning from 08:00 to 05:00, which can be well reconstruct the time-series real scenes using the proposed method.

Ground object information extraction from hyperspectral remote sensing images using deep learning algorithm

Mining and utilizing coal resources play an influential role in economic development. In this regard, the feature information extraction in the area is researched to accurately and efficiently assist the production arrangement and deployment in the mining area. First, the detection ability of Hyperspectral Remote Sensing Image (HRSI) technology is analyzed. It has high spectral resolution and many bands. Specific bands can be extracted as needed to highlight target features. According to the characteristics of HRSIs, the data spectrum information and spatial information are comprehensively utilized, and the Convolutional Neural Network (CNN) based on deep learning is employed for feature extraction. CNN allows the machine to automatically obtain data features by learning and guide the classification of features. Taking the Liuyuan research area in Gansu as an example, three CNN models are used to extract and classify the ground features in the area. The VGG-19 model can provide the highest classification accuracy rate, reaching 87.3%; the VGG-16 model has the highest classification accuracy rate of the ground in the mining area, reaching 95.2%. ResNet model has the best effect on road classification. Then, the lithology classification is applied based on Thermal Airborne Hyperspectral Imager (TASI) data. The noise level of the first 20 bands is comparatively stable; afterward, it increases exponentially, showing a higher noise level, and the spectrum curve of the data after denoising becomes smoother. The end-member extraction method is employed to extract 25 end-member spectra of almost all lithology in the research area from the image. The similarity coefficient clustering analysis is employed to group the curves, which are divided into six categories in total. The separability of similar categories can be constrained by the objective function using the dictionary learning method, and the accuracy of the sparse representation of the category spectrum can be improved. The spectral matching method is used to subdivide each group of mapping results, suggesting that in the research area, granite is the most widely distributed, followed by diorite, andesite, and quartzite. Deep learning algorithms are applied to extract ground feature information, which is of great significance to the safety production in the mining area. The hyperspectral remote sensing rock and mineral thematic information extraction module is developed, which preliminarily realizes the quantitative acquisition and high-precision identification of typical mineral information, and provides technical support for the research of remote sensing geological evaluation technology of resource exploration in the new era.

Generating high spectral consistent endurance time excitations by a modified time-domain spectral matching method

Endurance time acceleration functions (ETAFs) are the intensified acceleration time series whose spectral responses match time-varying targets in order to evaluate multiple-level structural seismic performances with few dynamic analyses. However, the matching precision of the ETAFs generated by the existing frequency-domain method is not satisfactory enough and thus still needs three or more ETAFs to reach an acceptable accuracy. In this study, a high-precision and efficient ETAF generation method is proposed to obtain highly spectral consistent ETAFs. Considering the time-varying characteristic of ETAFs, the time-domain spectral matching technique is modified and extended to improve the spectral fitness of ETAFs for multiple durations. Taking the multi-duration response spectra as the matching targets, the matching procedure is conducted, and several ETAFs are generated in accord with seismic design codes. The matching precision is controlled by a specified tolerance and the number of iterations. The results show that the proposed method can successfully generate high-accuracy ETAFs, so that a sufficient accuracy of seismic performance analysis can be reached with only one single ETAF. The ETAFs generated by the proposed method are compared with those generated by an existing method in the matching precision, computational time, time variation trend, and the ETAF duration. Compared with the existing method, the proposed method can achieve remarkably higher matching precision and requires considerably less computational time, especially for long-duration ETAFs. The proposed method can also match average acceleration spectra from real ground motions and accurately predict the seismic responses in the structural nonlinear analysis.

Characteristics of Spectral Matched Ground Motions Time Histories According to Seed Ground Motion Selection

According to several seismic design standards, a ground motion time history should be selected similar to the design response spectrum, or a ground motion time history should be modified by matching procedure to the design response spectrum through the time-domain method. For the response spectrum matching procedure, appropriate seed ground motions need to be selected to maintain recorded earthquake accelerogram characteristics. However, there are no specific criteria for selecting the seed ground motions for applying this methodology. In this study, the characteristics of ground motion time histories between seed motions and spectral matched motions were compared. Intensity measures used in the design were compared, and their change by spectral matching procedure was quantified. In addition, the seed ground motion sets were determined according to the response spectrum shape, and these sets analyzed the response of nonlinear and equivalent linear single degrees of freedom systems to present the seed motion selection conditions for spectral matching. As a result, several considerations for applying the time domain spectral matching method were presented.

A pixel-based spectral matching method for mapping high-resolution irrigated areas using EVI time series

ABSTRACT A pixel-based spectral matching method using enhanced vegetation index (EVI) time series from GaoFen-1 (GF-1) Satellite was developed based on spectral similarity value (SSV) and iterative thresholding to map irrigated areas for varying and scattered croplands at high resolution in order to improve understanding of dynamic irrigation pattern. The approach was tested in a typical irrigation district in Northwest China, resulting in 16-m irrigated area maps of the major crops (wheat and maize) for 2015–2018. The results showed an overall accuracy of 92.67% with a Kappa Coefficient of 0.89, producer’s accuracy of 97.42%, and user’s accuracy of 92.65% for the irrigated area. This method does not require a large number of ground-truth data as training samples, resulting in fast calculation speed, which is different from other supervised classification methods. After obtaining the standard spectrum of the study area, the irrigated areas can be continuously mapped for multi-years. Comparing with the existing global products, these high-resolution maps can depict small and fragmented irrigated croplands effectively with higher accuracy, which benefit local water management, food security analysis, and drought impact assessment, providing the prototype for the regions with fragmented croplands which requires high-resolution products.

Evaluation of the Radiometric Calibration of FY4A-AGRI Thermal Infrared Data Using Lake Qinghai

The absolute radiometric accuracy of thermal infrared channels of the Advanced Geosynchronous Radiation Imager (AGRI) onboard the FengYun-4A (FY4A) satellite was assessed with field experiment data in a vicarious calibration on 18, 2019, and August 20, 2019, in Lake Qinghai. Continuous water temperature records were collected by an unmanned surface vehicle equipped with a radiometer during the experimental period. We proposed a spectral matching method based on atmospheric transfer code to create consistent equivalent spectral radiance, and the results predicted by atmospheric transfer simulation were convolved with instrument response functions to obtain predicted brightness temperature for comparison with satellite-derived temperature. Our results indicated that AGRI had an average temperature bias of 0.12 K with an RMSE of 0.17 and 0.61 K with an RMSE of 0.22 K in band 12 and band 13 on August 18, while these biases decreased to -0.01 K with an RMSE of 0.13 and -0.48 K with an RMSE of 0.17 K on August 20, respectively. This radiometric accuracy indicated that AGRI TIR bands are well functional compared with their preflight requirement of less than 1 K. The uncertainty analysis also suggested that atmospheric conditions would alter the calibration accuracy by influencing the transmittance and path thermal radiance. Meanwhile, cloud cover also requires more attention to select the appropriate concurrent satellite pixels to reduce the possible cloud edge effects. It is important and necessary for FY4A AGRI to conduct more intense automatic observations and obtain more data to improve the accuracy of radiometric calibration and monitor the operational status of satellite instruments.

A Novel Spectral Matching Approach for Pigment: Spectral Subsection Identification Considering Ion Absorption Characteristics

Background: Hyperspectral technology has made it possible to perform completely non-invasive investigations on pigment analysis, in particular, on pigment identification. The most commonly used method of pigment identification is to compare the spectral similarity between ones of unknown target and ones in spectral library, which requires a comprehensive and complete spectral library and is based on overall shape of the spectrum. To a certain extent, it may ignore some of the key absorption characteristics of the spectrum. Methods: A novel spectral matching method was proposed based on the spectrum divided into subsections for identification according to the main ion absorption characteristics. Main works: (1) establishing a spectral library suitable for typical pigment identification of painting; (2) discussing the main components, as well as the absorption positions of the ions and functional groups contained in pigments frequently used by artists; (3) presenting a novel spectral matching algorithm carried on spectral subsections for pigment identification; (4) verifying the feasibility and applicability of proposed method by a Chinese painting and a fresco. Conclusions: The proposed method can correctly identify the main pigments or components contained in the mixed area, which is better than the traditional method and more convenient than the unmixing method, except for some limitations in detecting white and black pigments.