Model Calculations Research Articles

Study of the Stress Distribution and a Calculation Model for the Local Bearing Capacity of Concrete Under Headed Bars

In order to obtain the calculation model for the local bearing capacity of concrete Fl under two headed bars, six pull-out concrete specimens were prepared. The effect of the net distance between two headed bars c on Fl was mainly investigated. The test results show that the local bearing capacity of concrete would first decrease and then increase with the increase in c, and the boundary point of the two stages was c = 40 mm. It is determined that the stress transformation from the local compression state to the axial compression state in the stress distribution model is characterized by the variation rate of the vertical stress under individual headed bars, which would infinitely approach a constant value. The constant value under individual headed bars is used as the limit value. The height of the vertical stress under two headed bars is modified, and then the height of the tensile region of the specimen with different c values is determined. Combined with the experimental phenomena and the results, two stages of calculation models are established, respectively: the integral calculation model and the individual calculation model. The integral calculation model focuses on the interaction of the compression region under two headed bars. The individual calculation model mainly focuses on the interaction of the tensile region under two headed bars. The calculation equations considering the influence of the height of the tensile region are established. Two groups of similar test data regarding the local bearing capacity were collected and verified as the integral calculation model and the individual calculation model. The average value of the ratio between the test value and the calculated value is 1.057 and 1.061, the standard deviation is 0.153 and 0.091, and the coefficient of variation is 0.055 and 0.086. It is proved that the calculation model proposed in this paper has a certain accuracy. It can provide a reference for calculating the local bearing capacity of concrete under multiple headed bars.

Conformational Changes and Coordination Stability of Flexible Tripeptides During Ni(II)-mediated Self-assembly.

The rational design of artificial supramolecular structures with specific properties and functions hinges the comprehensive understanding of the coordination and noncovalent interactions driving self-assembly. Herein, the self-assembly of supramolecular systems through octahedral coordination between Ni(II) ions and a flexible tripeptide was theoretically investigated using quantum chemical calculations. These calculations utilized the B3LYP functional with the polarizable continuum model. Our results indicate that tridentate sites have a greater propensity for coordination, and that the presence of chloride anions and conformational shifts enhance bidentate and monodentate coordination. Insights into the effect of counter anions on the stability of octahedral coordination and the prerequisites for self-assembly were gained by determining the stable conformation and potential reaction pathways of the tripeptide before and after adding chloride anions through an efficient automated conformational search. The formation of intramolecular hydrogen bonding interactions during the conformational changes was also studied using model calculations. Possible processes for initial self-assembly of tripeptide were proposed. This study enhances the fundamental understanding of the conformational behavior of building blocks during supramolecular formation and advance the potential for constructing future bioinspired complexes.

A Novel Axial Load Inversion Method for Rock Bolts Based on the Surface Strain of a Bearing Plate

Anchor rock bolts are among the essential support components employed in coal mine support engineering. Measuring the axial load of the supporting anchor bolts constitutes an important foundation for evaluating the support effect and the mechanical state of the surrounding rock. The existing methods for measuring the axial load of rock bolts have difficulty meeting the actual demands in terms of accuracy and means. Therefore, we propose a novel inverse method for determining the axial load of rock bolts. On the basis of the dynamic relationship between the axial load of the anchor bolt and the strain of the plate, a calculation model for the inverse analysis of the axial load from the plate strain is presented, and it is verified and corrected through finite element analysis and indoor physical experiments. By combining the calculation model with the digital image correlation method, a low costinversion of the axial load of the anchor bolt in actual support engineering is achieved. The experimental results demonstrate that the average errors of the load inversion of anchor bolts in three different states via the theory and method proposed in this paper are less than 8.8% (4 kN), 3.6% (3.2 kN), and 14.7% (5.5 kN), respectively, and the average error of the axial load of the rock bolts in the proposed method is only 4.23 kN. It possesses relatively high accuracy and can be effectively applied in the actual production processes of mines.

Calorimetric Measurements of a High-Power RF Signal

Development of a high-power RF signal meter based on the method of calorimetric measurements, which in some cases is the only possible one is presented. The device is as a system of elements exchanging either energy or information, the operation and interconnection of which ensures the stability of its functioning. The main elements of the device are: a coordinated load and a two-circuit water-air cooling system that convert RF energy first into thermal electrical energy, and then into internal energy of the coolant (working fluid). The measurement and control system provides information display on the monitor and generation of internal control signals. The work focuses on the process of converting electromagnetic energy into internal energy of the coolant, since the matched RF load is integrated into the cooling system and requires special design and technological solutions to ensure efficient operation. A cooling and measurement system has been designed to test the developed RF absorber with a power of up to 5 kW. The parameters of the cooling system were determined based on minimizing the time to achieve thermal equilibrium (time to establish readings) and the set parameters (input temperature no more than 35 °С, temperature difference no more than 40 °С). Based on calculations of the electrodynamic model constructed by the partial domain method, the geometric dimensions were determined at which the voltage standing wave ratio of the load in the operating frequency range (from DC to 1300 MHz) will be the smallest. The article presents the results of designing a high-frequency wattmeter cooled by a liquid (water), examines the thermophysical processes occurring in it and the influence of the presence of a coolant in the cooling circuit.

StaPep: An Open-Source Toolkit for Structure Prediction, Feature Extraction, and Rational Design of Hydrocarbon-Stapled Peptides.

All-hydrocarbon stapled peptides, with their covalent side-chain constraints, provide enhanced proteolytic stability and membrane permeability, making them superior to linear peptides. However, tools for extracting structural and physicochemical descriptors to predict the properties of hydrocarbon-stapled peptides are lacking. To address this, we present StaPep, a Python-based toolkit for generating 3D structures and calculating 21 features for hydrocarbon-stapled peptides. StaPep supports peptides containing two non-standard amino acids (norleucine and 2-aminoisobutyric acid) and six non-natural anchoring residues (S3, S5, S8, R3, R5, and R8), with customization options for other non-standard amino acids. We showcase StaPep's utility through three case studies. The first generates 3D structures of these peptides with a mean RMSD of 1.62 ± 0.86, offering essential structural insights for drug design and biological activity prediction. The second develops machine learning models based on calculated molecular features to differentiate between membrane-permeable and non-permeable stapled peptides, achieving an AUC of 0.93. The third constructs regression models to predict the antimicrobial activity of stapled peptides against Escherichia coli, with a Pearson correlation of 0.84. StaPep's pipeline spans data retrieval, structure generation, feature calculation, and machine learning modeling for hydrocarbon-stapled peptides. The source codes and data set are freely available on Github: https://github.com/dahuilangda/stapep_package.

Air Attenuation in Octave Bands and How to Normalize Room Acoustic Measurements to a Standard Atmosphere

The air attenuation of pure tones as a function of temperature and humidity is well known and described in ISO and ANSI standards. However, room acoustic measurements are performed in octave bands, which is the reason for the complicated, non-linear behavior of the air attenuation. It is known that room acoustic measurement results depend on air temperature and humidity, and these atmospheric data should always be reported in connection with room acoustic measurements. A calculation model for the air attenuation can make it possible to normalize the room acoustic results. For accurate results, it is possible to apply a summation method on each time sample in the impulse response. An approximation to the air attenuation at and above 1 kHz is possible by linearization using the pure-tone attenuation of two different frequencies, one frequency valid for the early part of the impulse response and another frequency valid for the later part of the impulse response. The purpose of the suggested methods is to make it possible to normalize room acoustic measurements to a standard atmosphere.

Generation of phonon quantum states and quantum correlations among single photon emitters in hexagonal boron nitride

Hexagonal boron nitride exhibits two types of defects with great potential for quantum information technologies: single-photon emitters (SPEs) and one-dimensional grain boundaries hosting topologically-protected phonons, termed as topologically-protected phonon lines (TPL). Here, by means of a simple effective model and density functional theory calculations, we show that it is possible to use these phonons for the transmission of information. Particularly, a single SPE can be used to induce single-, two- and qubit-phonon states in the one-dimensional channel, and (ii) two distant SPEs can be coupled by the TPL that acts as a waveguide, thus exhibiting strong quantum correlations. We highlight the possibilities offered by this material-built-in nano-architecture as a phononic device for quantum information technologies.

The Mathematical Model Based on the Parameters of Simulation Results Predicts the Fire Extinguishing Resource Demand of Naval Fires

In recent years, due to the diversity of fire scenes in ports and ships, the problem of fire command is complicated. In the case of power failure, the original command platform and fire extinguishing system will not be able to be used normally, or the fire extinguishing resources carried by the ship when it is on fire cannot be used. In the traditional firefighting ability research, there is no clear measure of firefighting ability, resulting in inaccurate calculation results. By corresponding to the quantity and composition of resources for the study of fire extinguishing capability, the combination of the fire dynamics simulation software PyroSim2020 and a calculation model that converts its resources into the total amount and flow of fire extinguishing agent can be provided. Based on the analytic hierarchy process (AHP), a firefighting demand grade calculation and judgment model was established, which included five factors: fire scale, combustion material characteristics, foam extinguishing agent performance, firefighting object characteristics, and external factors. It concluded that the demand assignment values of each index element were 2, 5, 6, 9, and 10, and further proposed the grade judgment criteria for the calculation results of comprehensive fire demand. Through the quantitative simulation of firefighting demand based on the fire scenario and calculation model test of the consumption prediction of cooperative firefighting equipment, it can also provide a strategic reference for related cooperative fire rescue.

Prediction and assessment of meteorological drought in southwest China using long short-term memory model

Abstract Drought prediction is crucial for mitigating risks and designing measures to alleviate its impact. Machine learning models have been widely applied in the field of drought prediction in recent years. This study concentrated on predicting meteorological droughts in southwest China, a region prone to frequent and severe droughts, particularly in areas with sparse meteorological station coverage. The long short-term memory (LSTM) predictive model, which is a deep learning model, was constructed by calculating standardized precipitation evapotranspiration index (SPEI) values based on 144 weather station observations from 1980 to 2020. The 5-fold cross-validation method was used for the hyperparameter optimization of the model. The LSTM model underwent comprehensive assessment and validation through multiple methods. This included the use of several accuracy assessment indicators and a comparison of results. The comparison covered different drought characteristics among the LSTM predictive model, the benchmark random forest (RF) predictive model, the historical drought situations, and the calculated SPEI values based on observations from 144 weather stations. The results showed that the training results of the LSTM predictive model basically agreed with the SPEI values calculated from weather station observations. The model-predicted variation trend of SPEI values for 2020 was similar to the variation in SPEI values calculated based on weather station observations. On the test set, the coefficient of determination (R 2), the root mean square error, the explained variance score, the Nash–Sutcliffe efficiency, and the Kling–Gupta efficiency were 0.757, 0.210, 0.802, 0.761, and 0.212, respectively. The total consistency rate of the drought grade was 59.26%. The spatial correlation distribution of SPEI values between LSTM model prediction and calculation from meteorological stations in 2020 was more than 0.5 for most regions. The correlation coefficients exceeded 0.6 in western Tibet and Chengdu Plains. Compared to the RF model, the LSTM model excelled in all five performance evaluation metrics and demonstrated a higher overall consistency rate for drought categories. The Kruskal–Wallis test for both the LSTM and RF models all indicated no significant difference in the distributions between the predicted and observed data. Scatter plots revealed that the prediction accuracy for both models in 2020 was suboptimal, with the SPEI showing a comparatively narrow range of values. Nonetheless, the LSTM model significantly outperformed the RF model in terms of prediction accuracy. In summary, the LSTM model demonstrated good overall performance, accuracy, and applicability. It has the potential to enhance dynamic drought prediction in regions with complex terrain, diverse climatic factors, and sparse weather station networks.

Vibronic coherent quantum beat in four-layer platinum carbonyl cluster.

Vibronic coherence has been studied for years, but direct comparisons between the rich experimental features and theory remain rare. In this work, we investigate the vibronic coherent quantum beat of a four-layer platinum carbonyl cluster [Pt3(CO)6]42- in a solution utilizing femtosecond vis-pump/vis-probe transient absorption spectroscopy. By varying the excitational wavelength, quantum beats coupled to either the electronic ground state or the excited state are selectively prepared. A 41cm-1 beat at the ground state with a phase flip at 615nm and a 28cm-1 beat at the excited state with a phase node at 735nm are observed. The beat amplitudes are asymmetric, stronger on the red side for ground state beats but weaker for excited state beats. Quantum chemistry calculations suggest that these beats result from coupling between the [Pt3(CO)6] layer motions and the electronic excitation. Theoretical model calculations for quantum beats at both electronic states are performed following the doorway-window approach. The calculations explain the oscillation frequency difference, the node positions, and the asymmetry. The beats with different frequencies result from vibronic coupling with different electronic states with the Herzberg-Teller (ground) or Franck-Condon term (excited) involved. The theoretical nodes occur at absorption and fluorescence centers, respectively, although experimental results show a slight blueshift. Quantum window operator calculations link the beat amplitude asymmetry to the Franck-Condon factor matrix imbalances, with the number of nodes dependent on the electronic dephasing rate. The theoretical insights for quantum beats are expected to be general, potentially helpful for the interpretation of observations in other systems.

Research on intelligent cutting control technology of transverse moving machine for large cross-section roadheader

With the continuous development of the coal mine industry in our country, the cross-section of the roadway is getting larger and larger. The widely used EBZ series roadheader cannot complete the roadway cutting operation with a large cross-section at one time, so it usually needs to move the equipment left and right to complete all its cutting tasks. This paper studies the intelligent control technology of large cross-section roadway cutting, which mainly solves the positioning and attitude determination technology of roadheader in the large cross-section, and offers an accurate shape-cutting control technology and a path planning technology using a lateral moving machine. This paper proposes to combine the signals of laser sensor and fiber-optic inertial navigation system to form a combined positioning and attitude determination system, so as to make use of the advantages and avoid the disadvantages of their respective systems, and improve the accuracy of roadheader positioning and attitude determination. A swing kinematics model of the cutting arm is established, based on which the precise motion control of the first roadway section cutting and the second roadway section cutting can be realized. A key parameter calculation model of roadheader lateral moving machine is put forward to calculate the operation parameters for roadheader lateral moving machine path planning. Finally, the experimental research on intelligent cutting control technology of large cross-section roadheader is carried out in 12307 intelligent heading face of Wangjialing Coal Mine. The results show that the positioning error of the combined positioning and attitude determination system proposed in this paper is between 50-90 mm in the X-axis direction and between 25-45 mm in the Y-axis direction. The average attitude measurement error of heading angle is between 0.5 and 1.5°. This makes the technology appropriate for engineering use. The studied cutting control system achieves a cutting error of 25-50 mm for the first section, and a cutting error of 40-90 mm for the complete section. The complete section cutting error meets the ±100 mm cutting error requirement required in engineering. The intelligent cutting control technology of the lateral moving machine of the large-section tunnel boring machine studied in this paper can realize accurate cutting of the large-section tunnel of 5.6 meters. The research results of this paper provide a reference for the intelligent construction of heading faces.

Heat transfer characteristics of petroleum coke particle packed bed: An experimental and CFD simulation study

AbstractDue to the complexity of the internal pore structure of petroleum coke loose particle‐packed beds, measuring their thermal conductivity has always been a challenging problem. This work independently developed an experimental apparatus for testing the thermal conductivity of petroleum coke particle‐packed beds and constructed a forward calculation model for the heat transfer process, which was based on one‐dimensional unsteady heat transfer. Using the Sparse Nonlinear OPTimizer (SNOPT) algorithm, a mathematical relationship between the thermal conductivity λ of the coke bed, temperature T, and equivalent particle diameter dp was established through inverse modeling. Concurrently, a digital model of the petroleum coke particle packed bed was derived utilizing three‐dimensional computed tomography (CT) scanning technology, and a pore‐scale gas–solid radiation heat transfer model was formulated based on CFD simulation technology, thereby further elucidating the heat transfer mechanism within the petroleum coke particle packed bed. The research results indicate that the temperature predicted by the established thermal conductivity model aligns well with experimental data. Further CFD simulation studies demonstrate that a smaller particle size leads to a larger temperature difference between the wall and the center of the packed bed, while a higher gas velocity results in a smaller temperature difference, with a linear correlation observed between these two factors. At high temperatures, thermal radiation between particles in the porous petroleum coke‐packed bed plays a dominant role. The research outcomes can offer significant theoretical support for a profound analysis of the heat transfer behavior of petroleum coke‐packed beds within a vertical shaft calciner.

Precise Geoid Determination in the Eastern Swiss Alps Using Geodetic Astronomy and GNSS/Leveling Methods

Astrogeodetic deflections of the vertical (DoVs) are close indicators of the slope of the geoid. Thus, DoVs observed along horizontal profiles may be integrated to create geoid undulation profiles. In this study, we collected DoV data in the Eastern Swiss Alps using a Swiss Digital Zenith Camera, the COmpact DIgital Astrometric Camera (CODIAC), and two total station-based QDaedalus systems. In the mountainous terrain of the Eastern Swiss Alps, the geoid profile was established at 15 benchmarks over a two-week period in June 2021. The elevation along the profile ranges from 1185 to 1800 m, with benchmark spacing ranging from 0.55 km to 2.10 km. The DoV, gravity, GNSS, and levelling measurements were conducted on these 15 benchmarks. The collected gravity data were primarily used for corrections of the DoV-based geoid profiles, accounting for variations in station height and the geoid-quasigeoid separation. The GNSS/levelling and DoV data were both used to compute geoid heights. These geoid heights are compared with the Swiss Geoid Model 2004 (CHGeo2004) and two global gravity field models (EGM2008 and XGM2019e). Our study demonstrates that absolute geoid heights derived from GNSS/leveling data achieve centimeter-level accuracy, underscoring the precision of this method. Comparisons with CHGeo2004 predictions reveal a strong correlation, closely aligning with both GNSS/leveling and DoV-derived results. Additionally, the differential geoid height analysis highlights localized variations in the geoid surface, further validating the robustness of CHGeo2004 in capturing fine-scale geoid heights. These findings confirm the reliability of both absolute and differential geoid height calculations for precise geoid modeling in complex mountainous terrains.

Construction of a deterministic mathematical model for the spatial-mass distribution of random fragments produced by cased charge explosion

To evaluate the destructive effects of fragment impacts on structures or personnel, it is crucial to assess the velocity, mass, size, and impact location of the fragments, as well as establish the correlation between these factors. This paper presents the experimental measurement of fragment velocities produced by the explosion of a cased charge, the fragments resulting from the explosion are collected and steel plates are used to record the impact locations and sizes of the fragments. Based on the experimental results, the calculation models of fragment velocity, fragment mass distribution and fragment scattering angle are corrected, the spatial distribution models of fragment size and number are established, and the functional relationship between fragment mass and size is constructed. Given the aforementioned research findings, the fragment spatial-mass distribution models based on the size distribution function and based on the mass distribution function are constructed, and the fragment space-mass distributions corresponding to the number of impact regions of 1, 5 and 10 are analyzed, and the effect of the number of impact location divisions on the fragment space-mass distribution is explored. The research results show that, for the current test charge, the fragment spatial-mass distribution model based on the size distribution function aligns most accurately with experimental results when the impact regions is divided into 10. The number of impact locations designated within each region is directly proportional to the number of fragments in that specific region. Notably, the impact location of the largest fragment occurs at 0.8 times the length of the impact region, whereas the peak fragment impact density occurs at 0.743 times the length of the impact region. The spatial-mass distribution model proposed in this paper successfully correlates the velocity, mass, size and impact location of the fragments, providing a realistic theoretical representation of the spatial geometric distribution of the fragments.

Research Progress and Prospects of Oil Saturation Evaluation Methods in Shale Oil Reservoirs

The core of the exploration and development of unconventional oil and gas resources, such as shale oil, lies in the effective identification and scale utilization of the sweet spot. Oil saturation is an important parameter in evaluating the sweet spot. Aiming to solve the many current problems of oil saturation logging evaluations of shale oil reservoirs, this study outlines the research progress of oil saturation logging evaluations of shale oil from the three aspects, namely, the electrical method, non-electrical method, and machine learning, through researching the literature and practical applications. At the same time, several typical saturation models are applied to shale oil reservoirs in the Qingshankou Formation of the Gulong Depression, and applicability analyses are conducted. Lastly, the advantages and disadvantages of each oil saturation calculation model are summarized, and suggestions are given for conducting research using each type of method. This study has certain significance in the selection of oil saturation logging evaluation methods for shale oil reservoirs and provides directions for improvement.

Development and optimization of ultimate performance self-levelling epoxy asphalt concrete (USEA) for prefabricated deck pavement

Developing prefabricated bridge deck pavement systems can fundamentally avoid the drawbacks caused by traditional on-site construction such as poor continuity of the construction process and significant differences in pavement layer performance. Prefabricated bridge deck pavement requires that the bridge pavement is completed with the steel deck together in the factory indoors thus it needs the concrete has better self-leveling characteristics which is rare for existing pavement materials. This article develops the ultimate performance self-levelling epoxy asphalt concrete (USEA) which both have excellent self-leveling properties and comprehensive performance. The study initially established the self-leveling asphalt concrete rolling model based on asphalt film thickness theory and Hertz contact theory and the critical rolling mechanical calculation results states that the aggregate particles and the skeleton amounts are the key elements for fluidity of concrete. Comprehensive the analysis of rolling model and research on the curing reaction process of epoxy resin, the study raises the material configuration of USEA and determine the gradation by the Bailey’s method. To guarantee the better pavement performance of USEA, the study designs the orthogonal test and establish the Entropy-TOPSIS model to optimize the details mortar schemes of concrete. Through the model calculation, the epoxy resin content and the SBS modified asphalt oil-stone ratio are determined as 20 % and 8.0 % respectively. In this scheme, the high temperature stability is 2805 times·mm-1, the low temperature bending strain is 3662με and the fatigue life can reach 1.200 million times. The study provides a material selection for the development of prefabricated bridge pavement system and the technical reference for the development of other self-leveling materials which has constructive practical significance.

The output flexibility optimization control of load-side wind turbine considering client demand response

Abstract This study focuses on optimizing the output flexibility control of load-side wind turbines considering client demand response. Considering the potential and role of client demand response, a load-side wind turbine output objective function was constructed, client demand response constraints were designed, and a two-layer model for flexible optimization control of load-side wind turbine output was constructed. The top is the power allocation hierarchy, and the core objective of this layer is to achieve power optimization distribution of wind turbines under various constraint conditions. The lower layer is the frequency control layer, which optimizes and controls the dynamic frequency of load-side wind turbine output. The experimental results show that the optimized control strategy not only enhances the efficiency of wind turbines, but also effectively reduces energy loss and enhances the stability and reliability of the power grid. Through precise calculation and real-time adjustment of the double-layer model, we can more accurately predict and control the output of wind turbines, thereby ensuring the supply-demand balance of the power grid and reducing potential risks caused by frequency fluctuations and power offsets.

Mental health effects of government transfer payments in urban China—An empirical study based on CFPS panel data

BackgroundGovernment transfer payments play a crucial role in redistributing wealth and alleviating relative poverty. However, the mental health effects of government transfers remain to be explored. This study aims to explore the internal mechanisms of the mental health effects of government transfer payments by examining individuals' subjective evaluations and attitudes. MethodsBased on panel data from the 2016 and 2018 China Family Panel Studies (CFPS) urban sample composition (N = 6645), the PSM-DID model was used to investigate the mental health effects of government transfer payments. Based on the calculation of the PSM-DID model, this study examined the effects of social security satisfaction and subjective social status on the mental health effects of government transfer payments through the mediation model and moderation model. ResultsThe study found that, overall, receiving government transfer payments can significantly reduce the level of individual depression. In examining the mechanism linking government transfer payments and mental health, it was discovered that social security satisfaction partially mediates this relationship. Additionally, subjective social status was identified as a negative moderating factor in this relationship, meaning that the alleviating effect of government transfer payments on depression diminishes as subjective social status increases. ConclusionsTherefore, in future policy optimization, firstly, the size and scope of urban government transfer payments should be expanded to directly improve the living standards of recipients. Secondly, social security programs should be strengthened. Thirdly, implementing the targeted interventions to address disparities in subjective social status should be considered.

The 540° Magnetic Buncher

Generation of short electron bunches with high peak current is of great importance for different research and technological applications. Such generation requires a special bunching magnetic system. The paper is an overview of the development of a new magnetic buncher. It consists of the buncher scheme description, the results of magnetic field modeling and reference particle trajectory calculation for the relativistic electrons, and of the description of bending magnets. The buncher provides a strong dependence of the time of flight on the particle energy and thus is capable to bunch relatively long bunches to short ones. Another feature of the buncher is that all electron-optical elements has been made of permanent magnets.

Charge radii of 11−16C, 13−17N and 15−18O determined from their charge-changing cross-sections and the mirror-difference charge radii

Charge-changing cross-sections (CCCSs) of 11−16C, 13−17N and 15−18O on a carbon target have been determined at energies around 300 MeV/nucleon. A nucleon separation energy-dependent correction factor has been introduced to the Glauber model calculation for extracting the nuclear charge radii from the experimental CCCSs. The charge radii of 11C, 13,16N and 15O thus were determined for the first time. With the new radii, we studied the experimental mirror-difference charge radii (ΔRchmirror) of 11B-11C, 13C-13N, 15N-15O, 17N-17Ne pairs for the first time. We find that the ΔRchmirror values of 13C-13N and 15N-15O pairs follow well the empirical relation to the isospin asymmetry predicted by the abinitio calculations, while ΔRchmirror of 11B-11C and 17N-17Ne pairs deviate from such relation by more than two standard deviations.