Objectives: The aim of this study was to investigate the effect of orthodontic loading on the expression of interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α) in compressed gingiva. Materials and Methods: ...Objectives: The aim of this study was to investigate the effect of orthodontic loading on the expression of interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α) in compressed gingiva. Materials and Methods: Twenty-four male Wistar rats were used with four rats as controls at day 0. In ten rats, corticotomy was performed on either left or right side and the re-maining side was served as control, and killed at 7 and 14 days. In the remaining ten rats, maxillary right and left first molars were moved orthodontically with a constant force of 20 g;appliance and appliance in conjunction with cortictomy (appliance-corticotomy) were sequentially alternated between left and right sides and euthanized at 7 and 14 days. Real time polymerase chain reactions of compressed gingiva excised from the euthanized rats was performed to measure mRNA expressions of IL-1α and TNF-α. Results: There were no significant differences in the expression of IL-1α between all the groups. On the other hand, TNF-α from the pressure side in the ap- pliance group and the appliance in conjunction with corticotomy group showed significant increase on the 7th day compared to that of either control or corticotomy group. Conclusions: Orthodontic loading induced the elevation of TNF-α in compressed展开更多
Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost,however,the strain rate dependent dynamic recrystallization(DRX)and texture evolution in hot deformation proce...Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost,however,the strain rate dependent dynamic recrystallization(DRX)and texture evolution in hot deformation process,which affect the formability of metals,are lack of study.In this work,the DRX behavior and texture evolution of Mg-8Gd-1Er-0.5Zr alloy hot compressed with strain rates of 0.1 s^(−1),1 s^(−1),10 s^(−1) and 50 s^(−1) are studied,and the corresponding dominant mechanisms for DRX and texture weakening are discussed.Results indicated the DRX fraction was 20%and the whole texture intensity was 16.89 MRD when the strain rate was 0.1 s^(−1),but they were 76%and 6.55 MRD,respectively,when the strain rate increased to 50 s^(−1).The increment of DRX fraction is suggested to result from the reduced DRX critical strain and the increased dislocation density as well as velocity,while the weakened whole texture is attributed to the increased DRX grains.At the low strain rate of 0.1 s^(−1),discontinuous DRX(DDRX)was the dominant,but the whole texture was controlled by the deformed grains with the preferred orientation of{0001}⊥CD,because the number of DDRX grains was limited.At the high strain rate of 50 s^(−1),continuous DRX(CDRX)and twin-induced DRX(TDRX)were promoted,and more DRX grains resulted in orientation randomization.The whole texture was mainly weakened by CDRX and TDRX grains,in which CDRX plays a major role.The results of present work are significant for understanding the hot workability of Mg-RE alloys with a high strain rate.展开更多
This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based ...This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based on the dictionary D.We establish that matrices adhering to the block D-NSP_(q)condition are both necessary and sufficient for the exact recovery of block sparse signals via l_(2)/l_(q)-synthesis.Additionally,this condition is essential for the stable recovery of signals that are block-compressible with respect to D.This D-NSP_(q)property is identified as the first complete condition for successful signal recovery using l_(2)/l_(q)-synthesis.Furthermore,we assess the theoretical efficacy of the l2/lq-synthesis method under conditions of measurement noise.展开更多
Neutron time-of-flight(ToF)measurement is a highly accurate method for obtaining the kinetic energy of a neutron by measuring its velocity,but requires precise acquisition of the neutron signal arrival time.However,th...Neutron time-of-flight(ToF)measurement is a highly accurate method for obtaining the kinetic energy of a neutron by measuring its velocity,but requires precise acquisition of the neutron signal arrival time.However,the high hardware costs and data burden associated with the acquisition of neutron ToF signals pose significant challenges.Higher sampling rates increase the data volume,data processing,and storage hardware costs.Compressed sampling can address these challenges,but it faces issues regarding optimal sampling efficiency and high-quality reconstructed signals.This paper proposes a revolutionary deep learning-based compressed sampling(DL-CS)algorithm for reconstructing neutron ToF signals that outperform traditional compressed sampling methods.This approach comprises four modules:random projection,rising dimensions,initial reconstruction,and final reconstruction.Initially,the technique adaptively compresses neutron ToF signals sequentially using three convolutional layers,replacing random measurement matrices in traditional compressed sampling theory.Subsequently,the signals are reconstructed using a modified inception module,long short-term memory,and self-attention.The performance of this deep compressed sampling method was quantified using the percentage root-mean-square difference,correlation coefficient,and reconstruction time.Experimental results showed that our proposed DL-CS approach can significantly enhance signal quality compared with other compressed sampling methods.This is evidenced by a percentage root-mean-square difference,correlation coefficient,and reconstruction time results of 5%,0.9988,and 0.0108 s,respectively,obtained for sampling rates below 10%for the neutron ToF signal generated using an electron-beam-driven photoneutron source.The results showed that the proposed DL-CS approach significantly improves the signal quality compared with other compressed sampling methods,exhibiting excellent reconstruction accuracy and speed.展开更多
BACKGROUND A key cardiac magnetic resonance(CMR)challenge is breath-holding duration,difficult for cardiac patients.AIM To evaluate whether artificial intelligence-assisted compressed sensing CINE(AICS-CINE)reduces im...BACKGROUND A key cardiac magnetic resonance(CMR)challenge is breath-holding duration,difficult for cardiac patients.AIM To evaluate whether artificial intelligence-assisted compressed sensing CINE(AICS-CINE)reduces image acquisition time of CMR compared to conventional CINE(C-CINE).METHODS Cardio-oncology patients(n=60)and healthy volunteers(n=29)underwent sequential C-CINE and AI-CS-CINE with a 1.5-T scanner.Acquisition time,visual image quality assessment,and biventricular metrics(end-diastolic volume,endsystolic volume,stroke volume,ejection fraction,left ventricular mass,and wall thickness)were analyzed and compared between C-CINE and AI-CS-CINE with Bland–Altman analysis,and calculation of intraclass coefficient(ICC).RESULTS In 89 participants(58.5±16.8 years,42 males,47 females),total AI-CS-CINE acquisition and reconstruction time(37 seconds)was 84%faster than C-CINE(238 seconds).C-CINE required repeats in 23%(20/89)of cases(approximately 8 minutes lost),while AI-CS-CINE only needed one repeat(1%;2 seconds lost).AICS-CINE had slightly lower contrast but preserved structural clarity.Bland-Altman plots and ICC(0.73≤r≤0.98)showed strong agreement for left ventricle(LV)and right ventricle(RV)metrics,including those in the cardiac amyloidosis subgroup(n=31).AI-CS-CINE enabled faster,easier imaging in patients with claustrophobia,dyspnea,arrhythmias,or restlessness.Motion-artifacted C-CINE images were reliably interpreted from AI-CS-CINE.CONCLUSION AI-CS-CINE accelerated CMR image acquisition and reconstruction,preserved anatomical detail,and diminished impact of patient-related motion.Quantitative AI-CS-CINE metrics agreed closely with C-CINE in cardio-oncology patients,including the cardiac amyloidosis cohort,as well as healthy volunteers regardless of left and right ventricular size and function.AI-CS-CINE significantly enhanced CMR workflow,particularly in challenging cases.The strong analytical concordance underscores reliability and robustness of AI-CS-CINE as a valuable tool.展开更多
The publisher regrets that the article type for this publication was incorrectly labeled as a Research Article.The correct designation should be Review Article.
Single-shot ultrafast compressed imaging(UCI)is an effective tool for studying ultrafast dynamics in physics,chemistry,or material science because of its excellent high frame rate and large frame number.However,the ra...Single-shot ultrafast compressed imaging(UCI)is an effective tool for studying ultrafast dynamics in physics,chemistry,or material science because of its excellent high frame rate and large frame number.However,the random code(Rcode)used in traditional UCI will lead to low-frequency noise covering high-frequency information due to its uneven sampling interval,which is a great challenge in the fidelity of large-frame reconstruction.Here,a high-frequency enhanced compressed active photography(H-CAP)is proposed.By uniformizing the sampling interval of R-code,H-CAP capture the ultrafast process with a random uniform sampling mode.This sampling mode makes the high-frequency sampling energy dominant,which greatly suppresses the low-frequency noise blurring caused by R-code and achieves high-frequency information of image enhanced.The superior dynamic performance and large-frame reconstruction ability of H-CAP are verified by imaging optical self-focusing effect and static object,respectively.We applied H-CAP to the spatial-temporal characterization of double-pulse induced silicon surface ablation dynamics,which is performed within 220 frames in a single-shot of 300 ps.H-CAP provides a high-fidelity imaging method for observing ultrafast unrepeatable dynamic processes with large frames.展开更多
This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specificall...This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specifically,this paper focuses on both channel modelling and receiver design for interference estimation and mitigation.We propose a delay-calibrated block-wise linear model,which extracts the delay of the dominant tap of each interference as a key parameter and approximates the residual channel coefficients by the recently developed blockwise linear model.Based on the delay-calibrated block-wise linear model and the angle-domain channel sparsity,we further conceive a message passing algorithm to solve the channel estimation problem.Numerical results demonstrate the superior performance of the proposed algorithm over the state-of-the-art algorithms.展开更多
In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure ...In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure design and material development.Underground gas storage can provide a solution to address the intermittency of renewable energy supply.Currently,lined rock caverns(LRCs)are regarded as the best option for compressed air and hydrogen storage,since they have excellent sealing properties and minimum environmental impacts.However,the load transfer,damage,and failure mechanisms of LRCs are not clear.This prevents the design and selection of mechanical structures.Particularly,the gas sealing capacity in specific gas conditions(e.g.,stored hydrogen-induced chemical reaction)remains poorly understood,and advanced materials to adapt the storage conditions of different gases should be developed.This experimental facility aims at providing a solution to these technical issues.This facility has several different types of LRCs,and study of the mechanical behavior of various structures and evaluation of the gas-tight performance of the sealing material can be carried out using a distributed fiberoptic sensing approach.The focus of this study is on the challenges in sealing material development and structure design.This facility facilitates large-scale and long-term energy storage for stable and continuous energy supply,and enables repurposing of underground space and acceleration of the realization of green energy ambitions in the context of Paris Agreement and China's carbon neutralization plan.展开更多
Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy ...Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy consumption and the difficulty of regulating peak-to-valley differences in the power grid are prominent.Compressed air energy storage,as a new large-scale and long-duration physical energy storage technology,has many advantages such as large scale,long lifespan,low cost,and environmental friendliness.It can solve the problem of difficult grid connection for unstable renewable energy generation such as photovoltaic and wind power,and improve energy utilization.In recent years,the industrialization process has been accelerating,demonstrating huge potential and advantages.This article conducts research and analysis on the industrial logic,technological development,industrialization process,industry competition landscape,and market competitiveness of compressed air energy storage,aiming to provide support for optimizing business layout and structural adjustment of enterprises.展开更多
During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomen...During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomenon,a numerical simulation framework of the finite volume method and transient embedded discrete fracture model is proposed to establish a new constitutive model that links poroelastoplastic deformation,adsorption-induced swelling,and aperture compression.From this model,anisotropic permeability tensors were derived to further achieve the simulation of coevolution.Meanwhile,our permeability model was verified against the measured permeability data,and the history match of the numerical model showed better results where the mismatch was less than 5%.The results indicate that(1)the long-term permeability evolution clearly showed the competitive effects of multiple deformation mechanisms,which involves three stages:compaction-dominated decline,adsorption-dominated rebound,and creep-controlled loss.(2)The increased number of compressible cleats/fractures accelerated the initial permeability decline,while the increased desorption-induced strain promoted faster rebound and enhancement and higher viscosity coefficients enhanced the creep effect,which led to significant long-term permeability loss.(3)Massive hydraulic fracturing created a larger drainage area,accelerating methane desorption and causing sharp permeability rebound with reduced residual gas,which shows that the permeability remained higher than the initial values even after the extensive extraction via the fractured horizontal wells.The permeability evolution mechanisms displayed varying properties,such as coal rank and burial depth,and distinct characteristics.A precise understanding of multiple competitive stress effects is crucial for optimizing coalbed methane extraction techniques and improving recovery efficiency.展开更多
With the rapid development of digital communication and the widespread use of the Internet of Things,multi-view image compression has attracted increasing attention as a fundamental technology for image data communica...With the rapid development of digital communication and the widespread use of the Internet of Things,multi-view image compression has attracted increasing attention as a fundamental technology for image data communication.Multi-view image compression aims to improve compression efficiency by leveraging correlations between images.However,the requirement of synchronization and inter-image communication at the encoder side poses significant challenges,especially for constrained devices.In this study,we introduce a novel distributed image compression model based on the attention mechanism to address the challenges associated with the availability of side information only during decoding.Our model integrates an encoder network,a quantization module,and a decoder network,to ensure both high compression performance and high-quality image reconstruction.The encoder uses a deep Convolutional Neural Network(CNN)to extract high-level features from the input image,which then pass through the quantization module for further compression before undergoing lossless entropy coding.The decoder of our model consists of three main components that allow us to fully exploit the information within and between images on the decoder side.Specifically,we first introduce a channel-spatial attention module to capture and refine information within individual image feature maps.Second,we employ a semi-coupled convolution module to extract both shared and specific information in images.Finally,a cross-attention module is employed to fuse mutual information extracted from side information.The effectiveness of our model is validated on various datasets,including KITTI Stereo and Cityscapes.The results highlight the superior compression capabilities of our method,surpassing state-of-the-art techniques.展开更多
A Mg−13Gd−4Y−2Zn−0.5Zr(wt.%)alloy was selected as the experimental material.After preheating,initial microstructures with different long-period stacking ordered(LPSO)phase andβ'phase distributions were obtained,a...A Mg−13Gd−4Y−2Zn−0.5Zr(wt.%)alloy was selected as the experimental material.After preheating,initial microstructures with different long-period stacking ordered(LPSO)phase andβ'phase distributions were obtained,and hot compression experiments were conducted.The effects of secondary phases on microstructure and dynamic recrystallization(DRX)behavior were investigated.The results revealed that the average grain size decreased from 70.93 to 31.53μm,and the DRX volume fraction increased from 20.3%to 40.1%after the pre-annealing treatment.The average grain size of Sample S0(pre-aging)decreased to 39.29μm,and the DRX volume fraction increased by 79.8%,whereas the average grain size of Samples S1−S7(pre-annealing+aging)slightly increased,and the DRX volume fraction slightly decreased.With increasing pre-annealing time,the width of the lamellar LPSO phase increased,which generated less dynamic precipitation during deformation and weakened the pinning effect.The DRX mechanism transformed from continuous dynamic recrystallization(CDRX,pre-homogenization sample)to particle-stimulated nucleation(PSN)+discontinuous dynamic recrystallization(DDRX,pre-annealing sample).After the pre-aging treatment,the reticular structure effectively pinned the dislocations and delayed the nucleation and growth of DRX grains.The DRX mechanism changed from the original CDRX+PSN(pre-aging sample)to DDRX(pre-annealing+aging sample).展开更多
High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compress...High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compressed sensing based algorithm for high resolution range imaging and a new minimized ll-norm criterion for motion compensation are proposed. The random hopping of the transmitted carrier frequency is converted to restricted isometry property of the observing matrix. Then practical problems of imaging model solution and signal parameter design are resolved. Due to the particularity of the proposed algorithm, two new indicators of range profile, i.e., average signal to sidelobe ratio and local similarity, are defined. The chamber measured data are adopted to testify the validity of the proposed algorithm, and simulations are performed to analyze the precision of velocity measurement as well as the performance of motion compensation. The simulation results show that the proposed algorithm has such advantages as high precision velocity measurement, low sidelobe and short period imaging, which ensure robust imaging for moving targets when signal-to-noise ratio is above 10 dB.展开更多
<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by ...<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by compression heating in compressed air energy storage technology, a novel constant-pressure pumped hydro combined with compressed air energy storage system was proposed. To deepen the understanding of the system and make the analysis closer to reality, this paper adopted an off-design model of the compressor to calculate and analyze the effect of key parameters on system thermodynamics performance. In addition, the results of this paper were compared with previous research results, and it was found that the current efficiency considering the off-design model of compressor was generally 2% - 5% higher than the previous efficiency. With increased preset pressure or with decreased terminal pressure, both the previous efficiency and current efficiency of the system increased. The exergy destruction coefficient of the throttle valve reached 4%. System efficiency was more sensitive to changes in water pump efficiency and hydroturbine efficiency. </div>展开更多
Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a ...Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.展开更多
Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to comp...Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.展开更多
In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the imag...In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the image to its original quality.The challenge lies in regenerating significantly compressed images into a state in which these become identifiable.Therefore,this study focuses on the restoration of JPEG images subjected to substantial degradation caused by maximum lossy compression using Generative Adversarial Networks(GAN).The generator in this network is based on theU-Net architecture.It features a newhourglass structure that preserves the characteristics of the deep layers.In addition,the network incorporates two loss functions to generate natural and high-quality images:Low Frequency(LF)loss and High Frequency(HF)loss.HF loss uses a pretrained VGG-16 network and is configured using a specific layer that best represents features.This can enhance the performance in the high-frequency region.In contrast,LF loss is used to handle the low-frequency region.The two loss functions facilitate the generation of images by the generator,which can mislead the discriminator while accurately generating high-and low-frequency regions.Consequently,by removing the blocking effects frommaximum lossy compressed images,images inwhich identities could be recognized are generated.This study represents a significant improvement over previous research in terms of the image resolution performance.展开更多
With the advent of the information security era,it is necessary to guarantee the privacy,accuracy,and dependable transfer of pictures.This study presents a new approach to the encryption and compression of color image...With the advent of the information security era,it is necessary to guarantee the privacy,accuracy,and dependable transfer of pictures.This study presents a new approach to the encryption and compression of color images.It is predicated on 2D compressed sensing(CS)and the hyperchaotic system.First,an optimized Arnold scrambling algorithm is applied to the initial color images to ensure strong security.Then,the processed images are con-currently encrypted and compressed using 2D CS.Among them,chaotic sequences replace traditional random measurement matrices to increase the system’s security.Third,the processed images are re-encrypted using a combination of permutation and diffusion algorithms.In addition,the 2D projected gradient with an embedding decryption(2DPG-ED)algorithm is used to reconstruct images.Compared with the traditional reconstruction algorithm,the 2DPG-ED algorithm can improve security and reduce computational complexity.Furthermore,it has better robustness.The experimental outcome and the performance analysis indicate that this algorithm can withstand malicious attacks and prove the method is effective.展开更多
The effect of freeze-thaw(F-T)cycles on the mechanical behaviors and internal mechanism of rock mass is a critical research topic.In permafrost or seasonally frozen regions,F-T cycles have adverse effects on the mecha...The effect of freeze-thaw(F-T)cycles on the mechanical behaviors and internal mechanism of rock mass is a critical research topic.In permafrost or seasonally frozen regions,F-T cycles have adverse effects on the mechanical properties of rock mass,leading to many serious disasters in mining and geotechnical operations.In this paper,uniaxial compression tests are carried out on cyan sandstone after different F-T cycles.The failure modes and damage evolution of cyan sandstone under F-T cycles are studied.In addition,from the perspective of fracture and pore volume,the calculation equations of rock strain under frost heaving pressure and F-T cycles are established and verified with the corresponding laboratory tests.Subsequently,based on the classical damage theory,the F-T damage variables of cyan sandstone under different F-T cycles are calculated,and the meso-damage calculation model of cyan sandstone under F-T-loading coupling conditions is derived.Furthermore,through the discrete element numerical simulation software(PFC^(3D)),the microscopic damage evolution process of cyan sandstone under uniaxial compression after F-T cycles is studied,including the change of microcracks number,distribution of microcracks,and the acoustic emission(AE)count.The goal of this study is to investigate the damage evolution mechanism of rock from the mesoscopic and microscopic aspects,which has certain guiding value for accurately understanding the damage characteristics of rock in cold regions.展开更多
文摘Objectives: The aim of this study was to investigate the effect of orthodontic loading on the expression of interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α) in compressed gingiva. Materials and Methods: Twenty-four male Wistar rats were used with four rats as controls at day 0. In ten rats, corticotomy was performed on either left or right side and the re-maining side was served as control, and killed at 7 and 14 days. In the remaining ten rats, maxillary right and left first molars were moved orthodontically with a constant force of 20 g;appliance and appliance in conjunction with cortictomy (appliance-corticotomy) were sequentially alternated between left and right sides and euthanized at 7 and 14 days. Real time polymerase chain reactions of compressed gingiva excised from the euthanized rats was performed to measure mRNA expressions of IL-1α and TNF-α. Results: There were no significant differences in the expression of IL-1α between all the groups. On the other hand, TNF-α from the pressure side in the ap- pliance group and the appliance in conjunction with corticotomy group showed significant increase on the 7th day compared to that of either control or corticotomy group. Conclusions: Orthodontic loading induced the elevation of TNF-α in compressed
基金supported by the Nation Key Research and Development Program of China(No.2021YFB3701100).
文摘Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost,however,the strain rate dependent dynamic recrystallization(DRX)and texture evolution in hot deformation process,which affect the formability of metals,are lack of study.In this work,the DRX behavior and texture evolution of Mg-8Gd-1Er-0.5Zr alloy hot compressed with strain rates of 0.1 s^(−1),1 s^(−1),10 s^(−1) and 50 s^(−1) are studied,and the corresponding dominant mechanisms for DRX and texture weakening are discussed.Results indicated the DRX fraction was 20%and the whole texture intensity was 16.89 MRD when the strain rate was 0.1 s^(−1),but they were 76%and 6.55 MRD,respectively,when the strain rate increased to 50 s^(−1).The increment of DRX fraction is suggested to result from the reduced DRX critical strain and the increased dislocation density as well as velocity,while the weakened whole texture is attributed to the increased DRX grains.At the low strain rate of 0.1 s^(−1),discontinuous DRX(DDRX)was the dominant,but the whole texture was controlled by the deformed grains with the preferred orientation of{0001}⊥CD,because the number of DDRX grains was limited.At the high strain rate of 50 s^(−1),continuous DRX(CDRX)and twin-induced DRX(TDRX)were promoted,and more DRX grains resulted in orientation randomization.The whole texture was mainly weakened by CDRX and TDRX grains,in which CDRX plays a major role.The results of present work are significant for understanding the hot workability of Mg-RE alloys with a high strain rate.
基金Supported by The Featured Innovation Projects of the General University of Guangdong Province(2023KTSCX096)The Special Projects in Key Areas of Guangdong Province(ZDZX1088)Research Team Project of Guangdong University of Education(2024KYCXTD018)。
文摘This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based on the dictionary D.We establish that matrices adhering to the block D-NSP_(q)condition are both necessary and sufficient for the exact recovery of block sparse signals via l_(2)/l_(q)-synthesis.Additionally,this condition is essential for the stable recovery of signals that are block-compressible with respect to D.This D-NSP_(q)property is identified as the first complete condition for successful signal recovery using l_(2)/l_(q)-synthesis.Furthermore,we assess the theoretical efficacy of the l2/lq-synthesis method under conditions of measurement noise.
基金supported by the National Defense Technology Foundation Program of China(No.JSJT2022209A001-3)Sichuan Science and Technology Program(No.2021JDRC0011)+1 种基金Nuclear Energy Development Research Program of China(Research on High Energy X-ray Imaging of Nuclear Fuel)Scientific Research and Innovation Team Program of Sichuan University of Science and Engineering(No.SUSE652A001).
文摘Neutron time-of-flight(ToF)measurement is a highly accurate method for obtaining the kinetic energy of a neutron by measuring its velocity,but requires precise acquisition of the neutron signal arrival time.However,the high hardware costs and data burden associated with the acquisition of neutron ToF signals pose significant challenges.Higher sampling rates increase the data volume,data processing,and storage hardware costs.Compressed sampling can address these challenges,but it faces issues regarding optimal sampling efficiency and high-quality reconstructed signals.This paper proposes a revolutionary deep learning-based compressed sampling(DL-CS)algorithm for reconstructing neutron ToF signals that outperform traditional compressed sampling methods.This approach comprises four modules:random projection,rising dimensions,initial reconstruction,and final reconstruction.Initially,the technique adaptively compresses neutron ToF signals sequentially using three convolutional layers,replacing random measurement matrices in traditional compressed sampling theory.Subsequently,the signals are reconstructed using a modified inception module,long short-term memory,and self-attention.The performance of this deep compressed sampling method was quantified using the percentage root-mean-square difference,correlation coefficient,and reconstruction time.Experimental results showed that our proposed DL-CS approach can significantly enhance signal quality compared with other compressed sampling methods.This is evidenced by a percentage root-mean-square difference,correlation coefficient,and reconstruction time results of 5%,0.9988,and 0.0108 s,respectively,obtained for sampling rates below 10%for the neutron ToF signal generated using an electron-beam-driven photoneutron source.The results showed that the proposed DL-CS approach significantly improves the signal quality compared with other compressed sampling methods,exhibiting excellent reconstruction accuracy and speed.
基金Supported by James Russell Hornsby and Jun Xiong Fund and United Imaging Healthcare.
文摘BACKGROUND A key cardiac magnetic resonance(CMR)challenge is breath-holding duration,difficult for cardiac patients.AIM To evaluate whether artificial intelligence-assisted compressed sensing CINE(AICS-CINE)reduces image acquisition time of CMR compared to conventional CINE(C-CINE).METHODS Cardio-oncology patients(n=60)and healthy volunteers(n=29)underwent sequential C-CINE and AI-CS-CINE with a 1.5-T scanner.Acquisition time,visual image quality assessment,and biventricular metrics(end-diastolic volume,endsystolic volume,stroke volume,ejection fraction,left ventricular mass,and wall thickness)were analyzed and compared between C-CINE and AI-CS-CINE with Bland–Altman analysis,and calculation of intraclass coefficient(ICC).RESULTS In 89 participants(58.5±16.8 years,42 males,47 females),total AI-CS-CINE acquisition and reconstruction time(37 seconds)was 84%faster than C-CINE(238 seconds).C-CINE required repeats in 23%(20/89)of cases(approximately 8 minutes lost),while AI-CS-CINE only needed one repeat(1%;2 seconds lost).AICS-CINE had slightly lower contrast but preserved structural clarity.Bland-Altman plots and ICC(0.73≤r≤0.98)showed strong agreement for left ventricle(LV)and right ventricle(RV)metrics,including those in the cardiac amyloidosis subgroup(n=31).AI-CS-CINE enabled faster,easier imaging in patients with claustrophobia,dyspnea,arrhythmias,or restlessness.Motion-artifacted C-CINE images were reliably interpreted from AI-CS-CINE.CONCLUSION AI-CS-CINE accelerated CMR image acquisition and reconstruction,preserved anatomical detail,and diminished impact of patient-related motion.Quantitative AI-CS-CINE metrics agreed closely with C-CINE in cardio-oncology patients,including the cardiac amyloidosis cohort,as well as healthy volunteers regardless of left and right ventricular size and function.AI-CS-CINE significantly enhanced CMR workflow,particularly in challenging cases.The strong analytical concordance underscores reliability and robustness of AI-CS-CINE as a valuable tool.
文摘The publisher regrets that the article type for this publication was incorrectly labeled as a Research Article.The correct designation should be Review Article.
基金supported by the National Science Foundation of China(No.12127806,No.62175195 and No.12304382)the International Joint Research Laboratory for Micro/Nano Manufacturing and Measurement Technologies.
文摘Single-shot ultrafast compressed imaging(UCI)is an effective tool for studying ultrafast dynamics in physics,chemistry,or material science because of its excellent high frame rate and large frame number.However,the random code(Rcode)used in traditional UCI will lead to low-frequency noise covering high-frequency information due to its uneven sampling interval,which is a great challenge in the fidelity of large-frame reconstruction.Here,a high-frequency enhanced compressed active photography(H-CAP)is proposed.By uniformizing the sampling interval of R-code,H-CAP capture the ultrafast process with a random uniform sampling mode.This sampling mode makes the high-frequency sampling energy dominant,which greatly suppresses the low-frequency noise blurring caused by R-code and achieves high-frequency information of image enhanced.The superior dynamic performance and large-frame reconstruction ability of H-CAP are verified by imaging optical self-focusing effect and static object,respectively.We applied H-CAP to the spatial-temporal characterization of double-pulse induced silicon surface ablation dynamics,which is performed within 220 frames in a single-shot of 300 ps.H-CAP provides a high-fidelity imaging method for observing ultrafast unrepeatable dynamic processes with large frames.
基金supported in part by the National Key Research and Development Program of China under Grant 2020YFB1804800。
文摘This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specifically,this paper focuses on both channel modelling and receiver design for interference estimation and mitigation.We propose a delay-calibrated block-wise linear model,which extracts the delay of the dominant tap of each interference as a key parameter and approximates the residual channel coefficients by the recently developed blockwise linear model.Based on the delay-calibrated block-wise linear model and the angle-domain channel sparsity,we further conceive a message passing algorithm to solve the channel estimation problem.Numerical results demonstrate the superior performance of the proposed algorithm over the state-of-the-art algorithms.
基金Basic Research Program of Jiangsu Province,Grant/Award Numbers:BK20221135,BK20243024,BM2022009National Key Research and Development Program of China,Grant/Award Number:2022YFC3003300+2 种基金National Natural Science Foundation of China,Grant/Award Numbers:42230704,42307202Young Elite Scientists Sponsorship Program by CAST,Grant/Award Number:2023QNRC001Xuzhou Science and Technology Program,Grant/Award Numbers:KC23383,KC23427。
文摘In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure design and material development.Underground gas storage can provide a solution to address the intermittency of renewable energy supply.Currently,lined rock caverns(LRCs)are regarded as the best option for compressed air and hydrogen storage,since they have excellent sealing properties and minimum environmental impacts.However,the load transfer,damage,and failure mechanisms of LRCs are not clear.This prevents the design and selection of mechanical structures.Particularly,the gas sealing capacity in specific gas conditions(e.g.,stored hydrogen-induced chemical reaction)remains poorly understood,and advanced materials to adapt the storage conditions of different gases should be developed.This experimental facility aims at providing a solution to these technical issues.This facility has several different types of LRCs,and study of the mechanical behavior of various structures and evaluation of the gas-tight performance of the sealing material can be carried out using a distributed fiberoptic sensing approach.The focus of this study is on the challenges in sealing material development and structure design.This facility facilitates large-scale and long-term energy storage for stable and continuous energy supply,and enables repurposing of underground space and acceleration of the realization of green energy ambitions in the context of Paris Agreement and China's carbon neutralization plan.
文摘Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy consumption and the difficulty of regulating peak-to-valley differences in the power grid are prominent.Compressed air energy storage,as a new large-scale and long-duration physical energy storage technology,has many advantages such as large scale,long lifespan,low cost,and environmental friendliness.It can solve the problem of difficult grid connection for unstable renewable energy generation such as photovoltaic and wind power,and improve energy utilization.In recent years,the industrialization process has been accelerating,demonstrating huge potential and advantages.This article conducts research and analysis on the industrial logic,technological development,industrialization process,industry competition landscape,and market competitiveness of compressed air energy storage,aiming to provide support for optimizing business layout and structural adjustment of enterprises.
基金support of the National Natural Science Foundation of China(U23B6004 and 52404045)the CAST Young Talent Support Program,Doctoral Student Special Project.
文摘During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomenon,a numerical simulation framework of the finite volume method and transient embedded discrete fracture model is proposed to establish a new constitutive model that links poroelastoplastic deformation,adsorption-induced swelling,and aperture compression.From this model,anisotropic permeability tensors were derived to further achieve the simulation of coevolution.Meanwhile,our permeability model was verified against the measured permeability data,and the history match of the numerical model showed better results where the mismatch was less than 5%.The results indicate that(1)the long-term permeability evolution clearly showed the competitive effects of multiple deformation mechanisms,which involves three stages:compaction-dominated decline,adsorption-dominated rebound,and creep-controlled loss.(2)The increased number of compressible cleats/fractures accelerated the initial permeability decline,while the increased desorption-induced strain promoted faster rebound and enhancement and higher viscosity coefficients enhanced the creep effect,which led to significant long-term permeability loss.(3)Massive hydraulic fracturing created a larger drainage area,accelerating methane desorption and causing sharp permeability rebound with reduced residual gas,which shows that the permeability remained higher than the initial values even after the extensive extraction via the fractured horizontal wells.The permeability evolution mechanisms displayed varying properties,such as coal rank and burial depth,and distinct characteristics.A precise understanding of multiple competitive stress effects is crucial for optimizing coalbed methane extraction techniques and improving recovery efficiency.
基金supported by the National Natural Science Foundation of China(Key Program)(No.11932013)the Tianjin Science and Technology Plan Project(No.22PTZWHZ00040)。
文摘With the rapid development of digital communication and the widespread use of the Internet of Things,multi-view image compression has attracted increasing attention as a fundamental technology for image data communication.Multi-view image compression aims to improve compression efficiency by leveraging correlations between images.However,the requirement of synchronization and inter-image communication at the encoder side poses significant challenges,especially for constrained devices.In this study,we introduce a novel distributed image compression model based on the attention mechanism to address the challenges associated with the availability of side information only during decoding.Our model integrates an encoder network,a quantization module,and a decoder network,to ensure both high compression performance and high-quality image reconstruction.The encoder uses a deep Convolutional Neural Network(CNN)to extract high-level features from the input image,which then pass through the quantization module for further compression before undergoing lossless entropy coding.The decoder of our model consists of three main components that allow us to fully exploit the information within and between images on the decoder side.Specifically,we first introduce a channel-spatial attention module to capture and refine information within individual image feature maps.Second,we employ a semi-coupled convolution module to extract both shared and specific information in images.Finally,a cross-attention module is employed to fuse mutual information extracted from side information.The effectiveness of our model is validated on various datasets,including KITTI Stereo and Cityscapes.The results highlight the superior compression capabilities of our method,surpassing state-of-the-art techniques.
基金supported by the Graduate Education Innovation Program of Shanxi Province,China(No.2024KY575)the National Natural Science Foundation of China(No.52075501)。
文摘A Mg−13Gd−4Y−2Zn−0.5Zr(wt.%)alloy was selected as the experimental material.After preheating,initial microstructures with different long-period stacking ordered(LPSO)phase andβ'phase distributions were obtained,and hot compression experiments were conducted.The effects of secondary phases on microstructure and dynamic recrystallization(DRX)behavior were investigated.The results revealed that the average grain size decreased from 70.93 to 31.53μm,and the DRX volume fraction increased from 20.3%to 40.1%after the pre-annealing treatment.The average grain size of Sample S0(pre-aging)decreased to 39.29μm,and the DRX volume fraction increased by 79.8%,whereas the average grain size of Samples S1−S7(pre-annealing+aging)slightly increased,and the DRX volume fraction slightly decreased.With increasing pre-annealing time,the width of the lamellar LPSO phase increased,which generated less dynamic precipitation during deformation and weakened the pinning effect.The DRX mechanism transformed from continuous dynamic recrystallization(CDRX,pre-homogenization sample)to particle-stimulated nucleation(PSN)+discontinuous dynamic recrystallization(DDRX,pre-annealing sample).After the pre-aging treatment,the reticular structure effectively pinned the dislocations and delayed the nucleation and growth of DRX grains.The DRX mechanism changed from the original CDRX+PSN(pre-aging sample)to DDRX(pre-annealing+aging sample).
基金Project(61171133) supported by the National Natural Science Foundation of ChinaProject(CX2011B019) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(B110404) supported by Innovation Foundation for Outstanding Postgraduates of National University of Defense Technology,China
文摘High resolution range imaging with correlation processing suffers from high sidelobe pedestal in random frequency-hopping wideband radar. After the factors which affect the sidelobe pedestal being analyzed, a compressed sensing based algorithm for high resolution range imaging and a new minimized ll-norm criterion for motion compensation are proposed. The random hopping of the transmitted carrier frequency is converted to restricted isometry property of the observing matrix. Then practical problems of imaging model solution and signal parameter design are resolved. Due to the particularity of the proposed algorithm, two new indicators of range profile, i.e., average signal to sidelobe ratio and local similarity, are defined. The chamber measured data are adopted to testify the validity of the proposed algorithm, and simulations are performed to analyze the precision of velocity measurement as well as the performance of motion compensation. The simulation results show that the proposed algorithm has such advantages as high precision velocity measurement, low sidelobe and short period imaging, which ensure robust imaging for moving targets when signal-to-noise ratio is above 10 dB.
文摘<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by compression heating in compressed air energy storage technology, a novel constant-pressure pumped hydro combined with compressed air energy storage system was proposed. To deepen the understanding of the system and make the analysis closer to reality, this paper adopted an off-design model of the compressor to calculate and analyze the effect of key parameters on system thermodynamics performance. In addition, the results of this paper were compared with previous research results, and it was found that the current efficiency considering the off-design model of compressor was generally 2% - 5% higher than the previous efficiency. With increased preset pressure or with decreased terminal pressure, both the previous efficiency and current efficiency of the system increased. The exergy destruction coefficient of the throttle valve reached 4%. System efficiency was more sensitive to changes in water pump efficiency and hydroturbine efficiency. </div>
基金supported by the National Natural Science Foundation of China(No.42272321)Hubei Provincial Key Research Projects(Nos.2022BAA093 and 2022BAD163)+1 种基金Major Scientific and Technological Special Project of Jiangxi Province(No.2023ACG01004)WSGRI Engineering&Surveying Incorporation Limited(No.6120230256)。
文摘Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.
基金the financial support from the Natural Science Foundation of China (Nos.52179118,52209151 and 42307238)the Science and Technology Project of Jiangsu Provincial Department of Science and Technology-Carbon Emissions Peak and Carbon Neutrality Science and Technology Innovation Specia Fund Project (No.BK20220025)+3 种基金the Excellent Postdoctoral Program of Jiangsu Province (No.2023ZB602)the China Postdoctora Science Foundation (Nos.2023M733773 and 2023M733772)Xuzhou City Science and Technology Innovation Special Basic Research Plan (KC23045)State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining&Technology (No SKLGDUEK1916)。
文摘Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.
基金supported by the Technology Development Program(S3344882)funded by the Ministry of SMEs and Startups(MSS,Korea).
文摘In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the image to its original quality.The challenge lies in regenerating significantly compressed images into a state in which these become identifiable.Therefore,this study focuses on the restoration of JPEG images subjected to substantial degradation caused by maximum lossy compression using Generative Adversarial Networks(GAN).The generator in this network is based on theU-Net architecture.It features a newhourglass structure that preserves the characteristics of the deep layers.In addition,the network incorporates two loss functions to generate natural and high-quality images:Low Frequency(LF)loss and High Frequency(HF)loss.HF loss uses a pretrained VGG-16 network and is configured using a specific layer that best represents features.This can enhance the performance in the high-frequency region.In contrast,LF loss is used to handle the low-frequency region.The two loss functions facilitate the generation of images by the generator,which can mislead the discriminator while accurately generating high-and low-frequency regions.Consequently,by removing the blocking effects frommaximum lossy compressed images,images inwhich identities could be recognized are generated.This study represents a significant improvement over previous research in terms of the image resolution performance.
基金This work was supported in part by the National Natural Science Foundation of China under Grants 71571091,71771112the State Key Laboratory of Synthetical Automation for Process Industries Fundamental Research Funds under Grant PAL-N201801the Excellent Talent Training Project of University of Science and Technology Liaoning under Grant 2019RC05.
文摘With the advent of the information security era,it is necessary to guarantee the privacy,accuracy,and dependable transfer of pictures.This study presents a new approach to the encryption and compression of color images.It is predicated on 2D compressed sensing(CS)and the hyperchaotic system.First,an optimized Arnold scrambling algorithm is applied to the initial color images to ensure strong security.Then,the processed images are con-currently encrypted and compressed using 2D CS.Among them,chaotic sequences replace traditional random measurement matrices to increase the system’s security.Third,the processed images are re-encrypted using a combination of permutation and diffusion algorithms.In addition,the 2D projected gradient with an embedding decryption(2DPG-ED)algorithm is used to reconstruct images.Compared with the traditional reconstruction algorithm,the 2DPG-ED algorithm can improve security and reduce computational complexity.Furthermore,it has better robustness.The experimental outcome and the performance analysis indicate that this algorithm can withstand malicious attacks and prove the method is effective.
基金Projects(52474167,52104109)supported by the National Natural Science Foundation of ChinaProject(2022JJ40602)supported by the Natural Science Foundation of Hunan Province,China。
文摘The effect of freeze-thaw(F-T)cycles on the mechanical behaviors and internal mechanism of rock mass is a critical research topic.In permafrost or seasonally frozen regions,F-T cycles have adverse effects on the mechanical properties of rock mass,leading to many serious disasters in mining and geotechnical operations.In this paper,uniaxial compression tests are carried out on cyan sandstone after different F-T cycles.The failure modes and damage evolution of cyan sandstone under F-T cycles are studied.In addition,from the perspective of fracture and pore volume,the calculation equations of rock strain under frost heaving pressure and F-T cycles are established and verified with the corresponding laboratory tests.Subsequently,based on the classical damage theory,the F-T damage variables of cyan sandstone under different F-T cycles are calculated,and the meso-damage calculation model of cyan sandstone under F-T-loading coupling conditions is derived.Furthermore,through the discrete element numerical simulation software(PFC^(3D)),the microscopic damage evolution process of cyan sandstone under uniaxial compression after F-T cycles is studied,including the change of microcracks number,distribution of microcracks,and the acoustic emission(AE)count.The goal of this study is to investigate the damage evolution mechanism of rock from the mesoscopic and microscopic aspects,which has certain guiding value for accurately understanding the damage characteristics of rock in cold regions.
