Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cy...Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cyclic loads.A finite element model is devised,incorporating a singular armor wire,a rigid core,and a damaged sheath.To scrutinize the buckling progression and corresponding deformation,axial compression and bending cyclic loads are introduced.The observations reveal that a reduction in axial compression results in a larger number of cycles before buckling ensues and progressively shifts the buckling position toward the extrados and fixed end.Decreasing the bending radius precipitates a reduction in the buckling cycle number and minimizes the deformation in the armor wire.Furthermore,an empirical model is presented to predict the occurrence of birdcage buckling,providing a means to anticipate buckling events and to estimate the requisite number of cycles leading to buckling.展开更多
Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This s...Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This study develops a fractional-order nonlinear creep constitutive model that incorporates the double damage effect and implements a non-linear creep subroutine for soft rock using the threedimensional finite difference method on the FLAC3D platform.Comparative analysis of the theoretical,numerical,and experimental results reveals that the fractional-order constitutive model,which incorporates the double damage effect,accurately reflects the distinct deformation stages of green mudstone during creep failure and effectively captures the non-linear deformation in the accelerated creep phase.The numerical results show a fitting accuracy exceeding 97%with the creep test curves,significantly outperforming the 61%accuracy of traditional creep models.展开更多
[Objective] The aim was to provide a reference for studying the resistant ability of subtropical forest to freeze disaster and detecting the recovery and evolution of Huodendron biaristatum species after freeze disast...[Objective] The aim was to provide a reference for studying the resistant ability of subtropical forest to freeze disaster and detecting the recovery and evolution of Huodendron biaristatum species after freeze disaster.[Method] Effects of the damage caused by the southern ice storm in early 2008 on Huodendron biaristatum,dominant species of evergreen broad-leaved forest on the Damingshan,were studied in the aspect of population ecology.[Result] Among the 1 090 Huodendron biaristatum individuals （DBH ≥ 1 cm）,697 individuals were victims,accounting for 63.9%.The largest part of the victims was crown breakdown,which took up 37.6%.13.0% of the victims were bent,and 10.2% of the victims were trunk broken.The least part of the victims were uprooted,accounting for only 3.1%.Different types and extent of forestry damage had remarkable differences in diameter class,tree height,crown and taper.Rates of damage and crown breakdown increased with the increase of DBH,while bent rate decreased.Rates of damage,bent and trunk broken declined slowly with the increase of tree height,while crown breakdown rate followed the normal distribution.As the crown level increased,rates of damage and crown breakdown increased,while the rate of trunk broken decreased.Individuals with high taper were more susceptible to crown damage,bending,breaking and uprooted.[Conclusion] The resistant ability of Huodendron biaristatum species to freeze disaster is affected by many factors like DBH,tree height,crown,taper,etc..Huodendron biaristatum species in Damingshan affected by those factors show various kinds of damaged types dominant by mechanical damage,but there is few individual to die.展开更多
High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subject...High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.展开更多
While Araldite adhesives are extensively used in aerospace,maritime,and construction applications and have been well studied for their mechanical properties,their acoustic behavior remains largely unexplored.This stud...While Araldite adhesives are extensively used in aerospace,maritime,and construction applications and have been well studied for their mechanical properties,their acoustic behavior remains largely unexplored.This study investigates the sound absorption of 4 mm and 6 mm Araldite plates under undamaged and damaged conditions(circular,square,triangular damages).Measurements were performed using an ASTM E2611-09 impedance tube in the 100-1000 Hz and 1000-20000 Hz ranges,and results were validated with FEM simulations in COMSOL Multiphysics.Results show that damage has little to no effect on the sound absorption coefficient,with maximum values below 0.26.FEM predictions agreed well with experiments,achieving over 90%accuracy in the mid-frequency range.These findings indicate that Araldite plates’acoustic performance is largely insensitive to small geometrical damage,providing baseline data for marine and structural applications.展开更多
As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced brid...As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced bridges.Numerical examples show that compared with the natural frequencies of first-order modes,the natural frequencies of higher-order modes are more sensitive and can reflect the damage situation and external cable reinforcement effect of T-beam bridges.For damaged bridges,as the damage to the T-beam increases,the natural frequency value of the bridge gradually decreases.When the degree of local damage to the beam reaches 60%,the amplitude of natural frequency change exceeds 10%for the first time.The natural frequencies of the firstorder vibration mode and higher-order vibration mode can be selected as indexes for different degrees of the damaged T-beam bridges.For damaged bridges reinforced with external cables,the traditional natural frequency of the first-order vibration mode cannot be used as the index,which is insensitive to changes in prestress of the external cable.Some natural frequencies of higher-order vibration modes can be selected as indexes,which can reflect the reinforcement effect of externally prestressed damaged T-beam bridges,and its numerical value increases with the increase of external prestressed cable force.展开更多
Rocks will suffer different degree of damage under freeze-thaw(FT)cycles,which seriously threatens the long-term stability of rock engineering in cold regions.In order to study the mechanism of rock FT damage,energy c...Rocks will suffer different degree of damage under freeze-thaw(FT)cycles,which seriously threatens the long-term stability of rock engineering in cold regions.In order to study the mechanism of rock FT damage,energy calculation method and energy self-inhibition model are introduced to explore their energy characteristics in this paper.The applicability of the energy self-inhibition model was verified by combining the data of FT cycles and uniaxial compression tests of intact and pre-cracked sandstone samples,as well as published reference data.In addition,the energy evolution characteristics of FT damaged rocks were discussed accordingly.The results indicate that the energy self-inhibition model perfectly characterizes the energy accumulation characteristics of FT damaged rocks under uniaxial compression before the peak strength and the energy dissipation characteristics before microcrack unstable growth stage.Taking the FT damaged cyan sandstone sample as an example,it has gone through two stages dominated by energy dissipation mechanism and energy accumulation mechanism,and the energy rate curve of the pre-cracked sample shows a fall-rise phenomenon when approaching failure.Based on the published reference data,it was found that the peak total input energy and energy storage limit conform to an exponential FT decay model,with corresponding decay constants ranging from 0.0021 to 0.1370 and 0.0018 to 0.1945,respectively.Finally,a linear energy storage equation for FT damaged rocks was proposed,and its high reliability and applicability were verified by combining published reference data,the energy storage coefficient of different types of rocks ranged from 0.823 to 0.992,showing a negative exponential relationship with the initial UCS(uniaxial compressive strength).In summary,the mechanism by which FT weakens the mechanical properties of rocks has been revealed from an energy perspective in this paper,which can provide reference for related issues in cold regions.展开更多
Dear Editor,Irreversible retinal damage can occur due to retinal degenerative(RD)diseases as well as injuries caused by accidents or devices.Laser devices can inflict permanent damage to the retina,leading to the loss...Dear Editor,Irreversible retinal damage can occur due to retinal degenerative(RD)diseases as well as injuries caused by accidents or devices.Laser devices can inflict permanent damage to the retina,leading to the loss of photoreceptors(PRs)and underlying retinal pigment epithelium(RPE),culminating in vision impairment.Since there is no effective treatment for permanent retinal injuries,replacing damaged PRs and RPE with corresponding healthy cells can be a suitable therapeutic approach.展开更多
[Objective] The aim of this study was to extract effective feature bands of damaged rice leaves by planthoppers to make identification and classification rapidly from great amounts of imaging spectral data. [Method] T...[Objective] The aim of this study was to extract effective feature bands of damaged rice leaves by planthoppers to make identification and classification rapidly from great amounts of imaging spectral data. [Method] The experiment, using multi-spectral imaging system, acquired the multi-spectral images of damaged rice leaves from band 400 to 720 nm by interval of 5 nm. [Result] According to the principle of band index, it was calculated that the bands at 515, 510, 710, 555, 630, 535, 505, 530 and 595 nm were having high band index value with rich information and little correlation. Furthermore, the experiment used two classification methods and calcu-lated the classification accuracy higher than 90.00% for feature bands and ful bands of damaged rice leaves by planthoppers respectively. [Conclusion] It can be con-cluded that these bands can be considered as effective feature bands to identify damaged rice leaves by planthoppers quickly from a large scale of crops.展开更多
A method was proposed to evaluate the real-time reliability for a single product based on damaged measurement degradation data.Most researches on degradation analysis often assumed that the measurement process did not...A method was proposed to evaluate the real-time reliability for a single product based on damaged measurement degradation data.Most researches on degradation analysis often assumed that the measurement process did not have any impact on the product's performance.However,in some cases,the measurement process may exert extra stress on products being measured.To obtain trustful results in such a situation,a new degradation model was derived.Then,by fusing the prior information of product and its own on-line degradation data,the real-time reliability was evaluated on the basis of Bayesian formula.To make the proposed method more practical,a procedure based on expectation maximization (EM) algorithm was presented to estimate the unknown parameters.Finally,the performance of the proposed method was illustrated by a simulation study.The results show that ignoring the influence of the damaged measurement process can lead to biased evaluation results,if the damaged measurement process is involved.展开更多
Deep underground excavations within hard rocks can result in damage to the surrounding rock mass mostly due to redistribution of stresses.Especially within rock masses with non-persistent joints,the role of the pre-ex...Deep underground excavations within hard rocks can result in damage to the surrounding rock mass mostly due to redistribution of stresses.Especially within rock masses with non-persistent joints,the role of the pre-existing joints in the damage evolution around the underground opening is of critical importance as they govern the fracturing mechanisms and influence the brittle responses of these hard rock masses under highly anisotropic in situ stresses.In this study,the main focus is the impact of joint network geometry,joint strength and applied field stresses on the rock mass behaviours and the evolution of excavation induced damage due to the loss of confinement as a tunnel face advances.Analysis of such a phenomenon was conducted using the finite-discrete element method(FDEM).The numerical model is initially calibrated in order to match the behaviour of the fracture-free,massive Lac du Bonnet granite during the excavation of the Underground Research Laboratory(URL)Test Tunnel,Canada.The influence of the pre-existing joints on the rock mass response during excavation is investigated by integrating discrete fracture networks(DFNs)of various characteristics into the numerical models under varying in situ stresses.The numerical results obtained highlight the significance of the pre-existing joints on the reduction of in situ rock mass strength and its capacity for extension with both factors controlling the brittle response of the material.Furthermore,the impact of spatial distribution of natural joints on the stability of an underground excavation is discussed,as well as the potentially minor influence of joint strength on the stress induced damage within joint systems of a non-persistent nature under specific conditions.Additionally,the in situ stress-joint network interaction is examined,revealing the complex fracturing mechanisms that may lead to uncontrolled fracture propagation that compromises the overall stability of an underground excavation.展开更多
in order to evaluate the capacity of reinforced concrete （RC） structures subjected to blast Ioadings, the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC st...in order to evaluate the capacity of reinforced concrete （RC） structures subjected to blast Ioadings, the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC structures, and all three failure modes were numerically simulated by the finite element software ABAQUS. Simulation results agree with the experimental observations. It is demonstrated that the damaged plasticity model for concrete in the finite element software ABAQUS can predict dynamic responses and typical flexure, flexure-shear and direct shear failure modes of the blast-loaded RC structures.展开更多
Excavation Damaged Zone(EDZ)scope is important for optimizing excavation and support schemes in deep underground caverns.However,accurately predicting the full EDZ scope within the surrounding rock masses of deep unde...Excavation Damaged Zone(EDZ)scope is important for optimizing excavation and support schemes in deep underground caverns.However,accurately predicting the full EDZ scope within the surrounding rock masses of deep underground caverns during excavation remains a pressing problem.This study presents a comprehensive EDZ scope prediction approach(CESPA)for the brittle surrounding rock masses of deep underground caverns by coupling numerical simulation with quantitative analysis of borehole wall images and ultrasonic test results.First,the changes in both P-velocity(V_(p))and joint distribution of the surrounding rock masses before and after excavation damage are captured using ultrasonic tests and borehole digital cameras.Second,the quality Q-parameters of the surrounding rock mass before and after excavation damage are preliminarily rated with the rock mass descriptions provided by borehole wall images,and the rock mass V_(p)-parameter values are determined according to the V_(p)-borehole depth curves.Third,the Q-parameter ratings are further finely adjusted by updating the related Q-values to be similar with the Q-values estimated by V_(p)-parameter values.Fourth,the initial and residual mechanical parameters for the rock mass deterioration model(RDM)are estimated by the adjusted Q-parameter ratings based on the modified Q-based relations,and the elastic modulus deterioration index(EDI)threshold to describe the EDZ boundary is determined with the V_(p)-parameter values.Finally,EDZ scope is predicted using the elastoplastic numerical simulation with RDM and EDI based on the mechanical parameter estimates and EDI threshold.Analyses of applications in Sub-lab D1 in Jinping II project show that CESPA can provide a reliable and operable solution for predicting full EDZ scopes within the brittle surrounding rock masses of deep underground caverns.展开更多
After the excavation of the roadway,the original stress balance is destroyed,resulting in the redistribution of stress and the formation of an excavation damaged zone(EDZ)around the roadway.The thickness of EDZ is the...After the excavation of the roadway,the original stress balance is destroyed,resulting in the redistribution of stress and the formation of an excavation damaged zone(EDZ)around the roadway.The thickness of EDZ is the key basis for roadway stability discrimination and support structure design,and it is of great engineering significance to accurately predict the thickness of EDZ.Considering the advantages of machine learning(ML)in dealing with high-dimensional,nonlinear problems,a hybrid prediction model based on the random forest(RF)algorithm is developed in this paper.The model used the dragonfly algorithm(DA)to optimize two hyperparameters in RF,namely mtry and ntree,and used mean absolute error(MAE),rootmean square error(RMSE),determination coefficient(R^(2)),and variance accounted for(VAF)to evaluatemodel prediction performance.A database containing 217 sets of data was collected,with embedding depth(ED),drift span(DS),surrounding rock mass strength(RMS),joint index(JI)as input variables,and the excavation damaged zone thickness(EDZT)as output variable.In addition,four classic models,back propagation neural network(BPNN),extreme learning machine(ELM),radial basis function network(RBF),and RF were compared with the DA-RF model.The results showed that the DARF mold had the best prediction performance(training set:MAE=0.1036,RMSE=0.1514,R^(2)=0.9577,VAF=94.2645;test set:MAE=0.1115,RMSE=0.1417,R^(2)=0.9423,VAF=94.0836).The results of the sensitivity analysis showed that the relative importance of each input variable was DS,ED,RMS,and JI from low to high.展开更多
Rhythmic oscillatory patterns sustain cellular dynamics,driving the concerted action of regulatory molecules,microtubules,and molecular motors.We describe cellular microtubules as oscillators capable of synchronizatio...Rhythmic oscillatory patterns sustain cellular dynamics,driving the concerted action of regulatory molecules,microtubules,and molecular motors.We describe cellular microtubules as oscillators capable of synchronization and swarming,generating mechanical and electric patterns that impact biomolecular recognition.We consider the biological relevance of seeing the inside of cells populated by a network of molecules that behave as bioelectronic circuits and chromophores.We discuss the novel perspectives disclosed by mechanobiology,bioelectromagnetism,and photobiomodulation,both in term of fundamental basic science and in light of the biomedical implication of using physical energies to govern(stem)cell fate.We focus on the feasibility of exploiting atomic force microscopy and hyperspectral imaging to detect signatures of nanomotions and electromagnetic radiation(light),respectively,generated by the stem cells across the specification of their multilineage repertoire.The chance is reported of using these signatures and the diffusive features of physical waves to direct specifically the differentiation program of stem cells in situ,where they already are resident in all the tissues of the human body.We discuss how this strategy may pave the way to a regenerative and precision medicine without the needs for(stem)cell or tissue transplantation.We describe a novel paradigm based upon boosting our inherent ability for self-healing.展开更多
Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, an...Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, analytical solutions of stress and strain of the roadway surrounding rock were obtained, in which the creep deformation and strain softening were considered. Using the MTS815 rock mechanics testing system and a gas permeability testing system, permeability tests were conducted in the complete stress-strain process, and the evolution characteristics of permeability and strain were studied over the whole loading process. Based on the analytical solutions of stress and strain and the governing equation of gas seepage flow, this paper proposes a hydro-mechanical(HM) model, which considers three different zones around the roadway. Then the gas flow process in the roadway surrounding rock in three different zones was simulated according to the engineering geological conditions, thus obtaining the permeability and pressure distribution characteristics of the roadway surrounding rock in three different zones. These results show that the surrounding rock around the roadway can be divided into four regions-the full flow zone(FFZ), flow-shielding zone(FSZ), transitive flow zone(TFZ), and in-situ rock flow zone(IRFZ). These results could provide theoretical guidance for the improvement of gas extraction and gas control technology.展开更多
The damaged and strain subsurface layers of semi insulating(SI) GaAs substrate were characterized non destructively by Raman back scattering.The study shows that the thicknesses of the damaged and strain layers are...The damaged and strain subsurface layers of semi insulating(SI) GaAs substrate were characterized non destructively by Raman back scattering.The study shows that the thicknesses of the damaged and strain layers are less than 3μm.The damaged and strain layer can be removed after being etched in H 2SO 4·H 2O 2·H 2O for 1.5 min.展开更多
Transplantation of neuronal precursors derived from human pluripotent stem cells is a promising therapy for the treatment of neurological disorders associated with neuronal loss,such us neurodegenerative diseases,brai...Transplantation of neuronal precursors derived from human pluripotent stem cells is a promising therapy for the treatment of neurological disorders associated with neuronal loss,such us neurodegenerative diseases,brain trauma and stroke.The functional integration of grafted neurons differentiated from stem cells into the host injured neuronal circuitry has been a major challenge in cell therapy strategies for brain repair(Palma-Tortosa et al.,2021).Even though other cell types or mechanisms may provide modest clinical improvements,neuronal replacement and reconstruction of the damaged area are crucial for an optimal and long-term recovery.展开更多
The author, in a series of previous articles, designed the “AB Dome” made of transparent thin film supported by a small additional air overpressure for the purpose of covering a city or other important large install...The author, in a series of previous articles, designed the “AB Dome” made of transparent thin film supported by a small additional air overpressure for the purpose of covering a city or other important large installations or sub-regions. In present article the author offers a variation in which a damaged nuclear station can be quickly covered by such a cheap inflatable dome. By containing the radioactive dust from the damaged nuclear station, the danger zone is reduced to about 2 km2 rather than large regions which requires the resettlement of huge masses of people and which stops indus-try in large areas. If there is a big city (as Tokyo) near the nuclear disaster or there is already a dangerous amount of radioactive dust near a city, the city may also be covered by a large inflatable transparent Dome. The building of a gi-gantic inflatable AB Dome over an empty flat surface is not difficult. The cover is spread on a flat surface and a venti-lator (fan system) pumps air under the film cover and lifts the new dome into place but inflation takes many hours. However, to cover a city, garden, forest or other obstacle course in contrast to an empty, mowed field, the thin film cannot be easily deployed over building or trees without risking damage to it by snagging and other complications. This article proposes a new method which solves this problem. The design is a double film blanket filled by light gas such as, methane, hydrogen, or helium - although of these, methane will be the most practical and least likely to leak. Sections of this AB Blanket are lighter than air and will rise in the atmosphere. They can be made on a flat area serving as an as-sembly area and delivered by dirigible or helicopter to station at altitude over the city. Here they connect to the already assembled AB Blanket subassemblies, cover the city in an AB Dome and protect it from bad weather, chemical, bio-logical and radioactive fallout or particulates. After assembly of the dome is completed, the light gas can be replaced by (heavier but cheaper) air. Two projects for Tokyo (Japan) and Moscow (Russia) are used in this paper for sample computation.展开更多
The quarry and damaged mountain in peri-urban have an important influence to ecological environment. They have had a series of serious environmental -geological problems to the socio-economic development and urban mod...The quarry and damaged mountain in peri-urban have an important influence to ecological environment. They have had a series of serious environmental -geological problems to the socio-economic development and urban modernization process, such as increased environmental pollution and soil erosion,destruction of landscape aesthetic。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52471301)the Fujian Province Transportation Science and Technology Project(Grant No.JC202302)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY24E090003).
文摘Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cyclic loads.A finite element model is devised,incorporating a singular armor wire,a rigid core,and a damaged sheath.To scrutinize the buckling progression and corresponding deformation,axial compression and bending cyclic loads are introduced.The observations reveal that a reduction in axial compression results in a larger number of cycles before buckling ensues and progressively shifts the buckling position toward the extrados and fixed end.Decreasing the bending radius precipitates a reduction in the buckling cycle number and minimizes the deformation in the armor wire.Furthermore,an empirical model is presented to predict the occurrence of birdcage buckling,providing a means to anticipate buckling events and to estimate the requisite number of cycles leading to buckling.
基金support from the National Natural Science Foundation of China(No.52308316)the Scientific Research Foundation of Weifang University(Grant No.2024BS42)+2 种基金China Postdoctoral Science Foundation(No.2022M721885)the Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province(No.ZJRMG-2022-01)supported by Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(NO.SKLGME023017).
文摘Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This study develops a fractional-order nonlinear creep constitutive model that incorporates the double damage effect and implements a non-linear creep subroutine for soft rock using the threedimensional finite difference method on the FLAC3D platform.Comparative analysis of the theoretical,numerical,and experimental results reveals that the fractional-order constitutive model,which incorporates the double damage effect,accurately reflects the distinct deformation stages of green mudstone during creep failure and effectively captures the non-linear deformation in the accelerated creep phase.The numerical results show a fitting accuracy exceeding 97%with the creep test curves,significantly outperforming the 61%accuracy of traditional creep models.
基金Support by National Natural Science Foundation of China(30860059)~~
文摘[Objective] The aim was to provide a reference for studying the resistant ability of subtropical forest to freeze disaster and detecting the recovery and evolution of Huodendron biaristatum species after freeze disaster.[Method] Effects of the damage caused by the southern ice storm in early 2008 on Huodendron biaristatum,dominant species of evergreen broad-leaved forest on the Damingshan,were studied in the aspect of population ecology.[Result] Among the 1 090 Huodendron biaristatum individuals （DBH ≥ 1 cm）,697 individuals were victims,accounting for 63.9%.The largest part of the victims was crown breakdown,which took up 37.6%.13.0% of the victims were bent,and 10.2% of the victims were trunk broken.The least part of the victims were uprooted,accounting for only 3.1%.Different types and extent of forestry damage had remarkable differences in diameter class,tree height,crown and taper.Rates of damage and crown breakdown increased with the increase of DBH,while bent rate decreased.Rates of damage,bent and trunk broken declined slowly with the increase of tree height,while crown breakdown rate followed the normal distribution.As the crown level increased,rates of damage and crown breakdown increased,while the rate of trunk broken decreased.Individuals with high taper were more susceptible to crown damage,bending,breaking and uprooted.[Conclusion] The resistant ability of Huodendron biaristatum species to freeze disaster is affected by many factors like DBH,tree height,crown,taper,etc..Huodendron biaristatum species in Damingshan affected by those factors show various kinds of damaged types dominant by mechanical damage,but there is few individual to die.
基金supported by the CHN Energy Investment Group,grant numbers GJNY-23-86 and GJNY-23-92.
文摘High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.
文摘While Araldite adhesives are extensively used in aerospace,maritime,and construction applications and have been well studied for their mechanical properties,their acoustic behavior remains largely unexplored.This study investigates the sound absorption of 4 mm and 6 mm Araldite plates under undamaged and damaged conditions(circular,square,triangular damages).Measurements were performed using an ASTM E2611-09 impedance tube in the 100-1000 Hz and 1000-20000 Hz ranges,and results were validated with FEM simulations in COMSOL Multiphysics.Results show that damage has little to no effect on the sound absorption coefficient,with maximum values below 0.26.FEM predictions agreed well with experiments,achieving over 90%accuracy in the mid-frequency range.These findings indicate that Araldite plates’acoustic performance is largely insensitive to small geometrical damage,providing baseline data for marine and structural applications.
基金supported by Henan Province Science and Technology Research Funding Project(No.222102320129)the Key Research Project of Henan Higher Education Institutions(Grant Nos.22A560004,22A56005).
文摘As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced bridges.Numerical examples show that compared with the natural frequencies of first-order modes,the natural frequencies of higher-order modes are more sensitive and can reflect the damage situation and external cable reinforcement effect of T-beam bridges.For damaged bridges,as the damage to the T-beam increases,the natural frequency value of the bridge gradually decreases.When the degree of local damage to the beam reaches 60%,the amplitude of natural frequency change exceeds 10%for the first time.The natural frequencies of the firstorder vibration mode and higher-order vibration mode can be selected as indexes for different degrees of the damaged T-beam bridges.For damaged bridges reinforced with external cables,the traditional natural frequency of the first-order vibration mode cannot be used as the index,which is insensitive to changes in prestress of the external cable.Some natural frequencies of higher-order vibration modes can be selected as indexes,which can reflect the reinforcement effect of externally prestressed damaged T-beam bridges,and its numerical value increases with the increase of external prestressed cable force.
基金Project(52174088)supported by the National Natural Science Foundation of ChinaProject(104972024JYS0007)supported by the Independent Innovation Research Fund Graduate Free Exploration,Wuhan University of Technology,China。
文摘Rocks will suffer different degree of damage under freeze-thaw(FT)cycles,which seriously threatens the long-term stability of rock engineering in cold regions.In order to study the mechanism of rock FT damage,energy calculation method and energy self-inhibition model are introduced to explore their energy characteristics in this paper.The applicability of the energy self-inhibition model was verified by combining the data of FT cycles and uniaxial compression tests of intact and pre-cracked sandstone samples,as well as published reference data.In addition,the energy evolution characteristics of FT damaged rocks were discussed accordingly.The results indicate that the energy self-inhibition model perfectly characterizes the energy accumulation characteristics of FT damaged rocks under uniaxial compression before the peak strength and the energy dissipation characteristics before microcrack unstable growth stage.Taking the FT damaged cyan sandstone sample as an example,it has gone through two stages dominated by energy dissipation mechanism and energy accumulation mechanism,and the energy rate curve of the pre-cracked sample shows a fall-rise phenomenon when approaching failure.Based on the published reference data,it was found that the peak total input energy and energy storage limit conform to an exponential FT decay model,with corresponding decay constants ranging from 0.0021 to 0.1370 and 0.0018 to 0.1945,respectively.Finally,a linear energy storage equation for FT damaged rocks was proposed,and its high reliability and applicability were verified by combining published reference data,the energy storage coefficient of different types of rocks ranged from 0.823 to 0.992,showing a negative exponential relationship with the initial UCS(uniaxial compressive strength).In summary,the mechanism by which FT weakens the mechanical properties of rocks has been revealed from an energy perspective in this paper,which can provide reference for related issues in cold regions.
基金supported by the National Eye Institute,National Institute of Health,Bethesda,Maryland,USA[CIRM DISC1-09912(BBT),NIH EY031144(BBT),R01 EY031834,EY-017337]the USC Ophthalmology Core(NIH P30EY029220,an unrestricted grant to the USC Department of Ophthalmology from RPB)+1 种基金the BrightFocus Foundation(M2016186,BBT)support from a Research to Prevent Blindness(RPB,New York,NY,USA)unrestricted grant to the UCI Department of Ophthalmology.
文摘Dear Editor,Irreversible retinal damage can occur due to retinal degenerative(RD)diseases as well as injuries caused by accidents or devices.Laser devices can inflict permanent damage to the retina,leading to the loss of photoreceptors(PRs)and underlying retinal pigment epithelium(RPE),culminating in vision impairment.Since there is no effective treatment for permanent retinal injuries,replacing damaged PRs and RPE with corresponding healthy cells can be a suitable therapeutic approach.
基金Supported by National Natural Science Foundation of China under Grant(No.60968001,61168003)Natural Science Foundation of Yunnan Province under Grant(No.2011FZ079,2009CD047)National Training Programs of Innovation and Entrepreneurship for Undergraduates under Grant(No.201210681005,201310681004)~~
文摘[Objective] The aim of this study was to extract effective feature bands of damaged rice leaves by planthoppers to make identification and classification rapidly from great amounts of imaging spectral data. [Method] The experiment, using multi-spectral imaging system, acquired the multi-spectral images of damaged rice leaves from band 400 to 720 nm by interval of 5 nm. [Result] According to the principle of band index, it was calculated that the bands at 515, 510, 710, 555, 630, 535, 505, 530 and 595 nm were having high band index value with rich information and little correlation. Furthermore, the experiment used two classification methods and calcu-lated the classification accuracy higher than 90.00% for feature bands and ful bands of damaged rice leaves by planthoppers respectively. [Conclusion] It can be con-cluded that these bands can be considered as effective feature bands to identify damaged rice leaves by planthoppers quickly from a large scale of crops.
基金Project(60904002)supported by the National Natural Science Foundation of China
文摘A method was proposed to evaluate the real-time reliability for a single product based on damaged measurement degradation data.Most researches on degradation analysis often assumed that the measurement process did not have any impact on the product's performance.However,in some cases,the measurement process may exert extra stress on products being measured.To obtain trustful results in such a situation,a new degradation model was derived.Then,by fusing the prior information of product and its own on-line degradation data,the real-time reliability was evaluated on the basis of Bayesian formula.To make the proposed method more practical,a procedure based on expectation maximization (EM) algorithm was presented to estimate the unknown parameters.Finally,the performance of the proposed method was illustrated by a simulation study.The results show that ignoring the influence of the damaged measurement process can lead to biased evaluation results,if the damaged measurement process is involved.
基金the Natural Sciences and Engineering Research Council of Canadathe Ministry of National Defensethe RMC Green Team for providing the funding and the resources
文摘Deep underground excavations within hard rocks can result in damage to the surrounding rock mass mostly due to redistribution of stresses.Especially within rock masses with non-persistent joints,the role of the pre-existing joints in the damage evolution around the underground opening is of critical importance as they govern the fracturing mechanisms and influence the brittle responses of these hard rock masses under highly anisotropic in situ stresses.In this study,the main focus is the impact of joint network geometry,joint strength and applied field stresses on the rock mass behaviours and the evolution of excavation induced damage due to the loss of confinement as a tunnel face advances.Analysis of such a phenomenon was conducted using the finite-discrete element method(FDEM).The numerical model is initially calibrated in order to match the behaviour of the fracture-free,massive Lac du Bonnet granite during the excavation of the Underground Research Laboratory(URL)Test Tunnel,Canada.The influence of the pre-existing joints on the rock mass response during excavation is investigated by integrating discrete fracture networks(DFNs)of various characteristics into the numerical models under varying in situ stresses.The numerical results obtained highlight the significance of the pre-existing joints on the reduction of in situ rock mass strength and its capacity for extension with both factors controlling the brittle response of the material.Furthermore,the impact of spatial distribution of natural joints on the stability of an underground excavation is discussed,as well as the potentially minor influence of joint strength on the stress induced damage within joint systems of a non-persistent nature under specific conditions.Additionally,the in situ stress-joint network interaction is examined,revealing the complex fracturing mechanisms that may lead to uncontrolled fracture propagation that compromises the overall stability of an underground excavation.
基金Supported by National Natural Science Foundation of China (No.50638030 and 50525825)National Science and Technology Support Program (No.2006BAJ13B02).
文摘in order to evaluate the capacity of reinforced concrete （RC） structures subjected to blast Ioadings, the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC structures, and all three failure modes were numerically simulated by the finite element software ABAQUS. Simulation results agree with the experimental observations. It is demonstrated that the damaged plasticity model for concrete in the finite element software ABAQUS can predict dynamic responses and typical flexure, flexure-shear and direct shear failure modes of the blast-loaded RC structures.
基金funded by the National Natural Science Foundation of China under Grant Nos.51979268,U1765206,41877256。
文摘Excavation Damaged Zone(EDZ)scope is important for optimizing excavation and support schemes in deep underground caverns.However,accurately predicting the full EDZ scope within the surrounding rock masses of deep underground caverns during excavation remains a pressing problem.This study presents a comprehensive EDZ scope prediction approach(CESPA)for the brittle surrounding rock masses of deep underground caverns by coupling numerical simulation with quantitative analysis of borehole wall images and ultrasonic test results.First,the changes in both P-velocity(V_(p))and joint distribution of the surrounding rock masses before and after excavation damage are captured using ultrasonic tests and borehole digital cameras.Second,the quality Q-parameters of the surrounding rock mass before and after excavation damage are preliminarily rated with the rock mass descriptions provided by borehole wall images,and the rock mass V_(p)-parameter values are determined according to the V_(p)-borehole depth curves.Third,the Q-parameter ratings are further finely adjusted by updating the related Q-values to be similar with the Q-values estimated by V_(p)-parameter values.Fourth,the initial and residual mechanical parameters for the rock mass deterioration model(RDM)are estimated by the adjusted Q-parameter ratings based on the modified Q-based relations,and the elastic modulus deterioration index(EDI)threshold to describe the EDZ boundary is determined with the V_(p)-parameter values.Finally,EDZ scope is predicted using the elastoplastic numerical simulation with RDM and EDI based on the mechanical parameter estimates and EDI threshold.Analyses of applications in Sub-lab D1 in Jinping II project show that CESPA can provide a reliable and operable solution for predicting full EDZ scopes within the brittle surrounding rock masses of deep underground caverns.
基金funded by the National Science Foundation of China(42177164)the Distinguished Youth Science Foundation of Hunan Province of China(2022JJ10073)the Innovation-Driven Project of Central South University(2020CX040).
文摘After the excavation of the roadway,the original stress balance is destroyed,resulting in the redistribution of stress and the formation of an excavation damaged zone(EDZ)around the roadway.The thickness of EDZ is the key basis for roadway stability discrimination and support structure design,and it is of great engineering significance to accurately predict the thickness of EDZ.Considering the advantages of machine learning(ML)in dealing with high-dimensional,nonlinear problems,a hybrid prediction model based on the random forest(RF)algorithm is developed in this paper.The model used the dragonfly algorithm(DA)to optimize two hyperparameters in RF,namely mtry and ntree,and used mean absolute error(MAE),rootmean square error(RMSE),determination coefficient(R^(2)),and variance accounted for(VAF)to evaluatemodel prediction performance.A database containing 217 sets of data was collected,with embedding depth(ED),drift span(DS),surrounding rock mass strength(RMS),joint index(JI)as input variables,and the excavation damaged zone thickness(EDZT)as output variable.In addition,four classic models,back propagation neural network(BPNN),extreme learning machine(ELM),radial basis function network(RBF),and RF were compared with the DA-RF model.The results showed that the DARF mold had the best prediction performance(training set:MAE=0.1036,RMSE=0.1514,R^(2)=0.9577,VAF=94.2645;test set:MAE=0.1115,RMSE=0.1417,R^(2)=0.9423,VAF=94.0836).The results of the sensitivity analysis showed that the relative importance of each input variable was DS,ED,RMS,and JI from low to high.
文摘Rhythmic oscillatory patterns sustain cellular dynamics,driving the concerted action of regulatory molecules,microtubules,and molecular motors.We describe cellular microtubules as oscillators capable of synchronization and swarming,generating mechanical and electric patterns that impact biomolecular recognition.We consider the biological relevance of seeing the inside of cells populated by a network of molecules that behave as bioelectronic circuits and chromophores.We discuss the novel perspectives disclosed by mechanobiology,bioelectromagnetism,and photobiomodulation,both in term of fundamental basic science and in light of the biomedical implication of using physical energies to govern(stem)cell fate.We focus on the feasibility of exploiting atomic force microscopy and hyperspectral imaging to detect signatures of nanomotions and electromagnetic radiation(light),respectively,generated by the stem cells across the specification of their multilineage repertoire.The chance is reported of using these signatures and the diffusive features of physical waves to direct specifically the differentiation program of stem cells in situ,where they already are resident in all the tissues of the human body.We discuss how this strategy may pave the way to a regenerative and precision medicine without the needs for(stem)cell or tissue transplantation.We describe a novel paradigm based upon boosting our inherent ability for self-healing.
基金financially supported by the Natural Science Foundation of Jiangsu Province,China(No.BK20140189)the Postdoctoral Science Foundation of China(No.2014M550315)
文摘Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone(EDZ) is beneficial for the development of gas control technology. In this study, analytical solutions of stress and strain of the roadway surrounding rock were obtained, in which the creep deformation and strain softening were considered. Using the MTS815 rock mechanics testing system and a gas permeability testing system, permeability tests were conducted in the complete stress-strain process, and the evolution characteristics of permeability and strain were studied over the whole loading process. Based on the analytical solutions of stress and strain and the governing equation of gas seepage flow, this paper proposes a hydro-mechanical(HM) model, which considers three different zones around the roadway. Then the gas flow process in the roadway surrounding rock in three different zones was simulated according to the engineering geological conditions, thus obtaining the permeability and pressure distribution characteristics of the roadway surrounding rock in three different zones. These results show that the surrounding rock around the roadway can be divided into four regions-the full flow zone(FFZ), flow-shielding zone(FSZ), transitive flow zone(TFZ), and in-situ rock flow zone(IRFZ). These results could provide theoretical guidance for the improvement of gas extraction and gas control technology.
文摘The damaged and strain subsurface layers of semi insulating(SI) GaAs substrate were characterized non destructively by Raman back scattering.The study shows that the thicknesses of the damaged and strain layers are less than 3μm.The damaged and strain layer can be removed after being etched in H 2SO 4·H 2O 2·H 2O for 1.5 min.
基金supported by Ministerio de Ciencia e Innovación(Spain),under project No.PID2020-118120RB-I00European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No.813851European Union’s FET-Open program grant agreement,No.9648877(to DT).
文摘Transplantation of neuronal precursors derived from human pluripotent stem cells is a promising therapy for the treatment of neurological disorders associated with neuronal loss,such us neurodegenerative diseases,brain trauma and stroke.The functional integration of grafted neurons differentiated from stem cells into the host injured neuronal circuitry has been a major challenge in cell therapy strategies for brain repair(Palma-Tortosa et al.,2021).Even though other cell types or mechanisms may provide modest clinical improvements,neuronal replacement and reconstruction of the damaged area are crucial for an optimal and long-term recovery.
文摘The author, in a series of previous articles, designed the “AB Dome” made of transparent thin film supported by a small additional air overpressure for the purpose of covering a city or other important large installations or sub-regions. In present article the author offers a variation in which a damaged nuclear station can be quickly covered by such a cheap inflatable dome. By containing the radioactive dust from the damaged nuclear station, the danger zone is reduced to about 2 km2 rather than large regions which requires the resettlement of huge masses of people and which stops indus-try in large areas. If there is a big city (as Tokyo) near the nuclear disaster or there is already a dangerous amount of radioactive dust near a city, the city may also be covered by a large inflatable transparent Dome. The building of a gi-gantic inflatable AB Dome over an empty flat surface is not difficult. The cover is spread on a flat surface and a venti-lator (fan system) pumps air under the film cover and lifts the new dome into place but inflation takes many hours. However, to cover a city, garden, forest or other obstacle course in contrast to an empty, mowed field, the thin film cannot be easily deployed over building or trees without risking damage to it by snagging and other complications. This article proposes a new method which solves this problem. The design is a double film blanket filled by light gas such as, methane, hydrogen, or helium - although of these, methane will be the most practical and least likely to leak. Sections of this AB Blanket are lighter than air and will rise in the atmosphere. They can be made on a flat area serving as an as-sembly area and delivered by dirigible or helicopter to station at altitude over the city. Here they connect to the already assembled AB Blanket subassemblies, cover the city in an AB Dome and protect it from bad weather, chemical, bio-logical and radioactive fallout or particulates. After assembly of the dome is completed, the light gas can be replaced by (heavier but cheaper) air. Two projects for Tokyo (Japan) and Moscow (Russia) are used in this paper for sample computation.
文摘The quarry and damaged mountain in peri-urban have an important influence to ecological environment. They have had a series of serious environmental -geological problems to the socio-economic development and urban modernization process, such as increased environmental pollution and soil erosion,destruction of landscape aesthetic。
