The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissip...The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.展开更多
The rationality of using strain energy storage index(Wet)for evaluating rockburst proneness was theoretically verified based on linear energy storage(LES)law in this study.The LES law is defined as the linear relation...The rationality of using strain energy storage index(Wet)for evaluating rockburst proneness was theoretically verified based on linear energy storage(LES)law in this study.The LES law is defined as the linear relationship between the elastic strain energy stored inside the solid material and the input strain energy during loading.It is used to determine the elastic strain energy and dissipated strain energy of rock specimens at various loading/unloading stress levels.The results showed that the Wetvalue obtained from experiments was close to the corresponding theoretical one from the LES law.Furthermore,with an increase in the loading/unloading stress level,the ratio of elastic strain energy to dissipated strain energy converged to the peak-strength strain energy storage index(Wp et).This index is stable and can better reflect the relative magnitudes of the stored energy and the dissipated energy of rocks at the whole pre-peak stage than the strain energy storage index.The peak-strength strain energy storage index can replace the conventional strain energy storage index as a new index for evaluating rockburst proneness.展开更多
A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transf...A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transfer （LET） with a tilted ion beam at the 130？nm technology node is obtained. Tests of tilted angles θ=0 ° , 30 ° and 60 ° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40？MeVcm 2 /mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ , furthermore the effective LET for SOI is more closely in inverse proportion to cosθ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cosθ very well, which is also specifically explained.展开更多
The strain energy storage index WET was widely used to evaluate coal burst liability,but the scientific evidence for selecting the unloading stress level interval(around 80%of peak strength)remains lacking,and WET can...The strain energy storage index WET was widely used to evaluate coal burst liability,but the scientific evidence for selecting the unloading stress level interval(around 80%of peak strength)remains lacking,and WET can not reflect the energy storage and dissipation ratio(ESD ratio)of the whole pre-peak stage for coal materials.In this study,these two key problems in WET calculation and application were solved based on the linear energy storage(LES)law.The LES law was defined as the linear relationship between the elastic strain energy and input strain energy for solid material during loading.Using the LES law,the elastic strain energy and dissipated strain energy of at 10 types of coals were calculated precisely,and ideal ESD ratio and general ESD ratio at any stress level will be obtained subsequently.The results also show that WET is extremely close to the ideal and general ESD ratio,which proves that the selecting stress level of WET calculation is scientific and reasonable.Furthermore,the general ESD ratio converges to the peak ESD ratio(namely peak strain energy storage index WET P)as stress level increases.Compared with WET,Wp ET not only reflects the ESD ratio of coal materials over the whole pre-peak loading stage,but also exhibits excellent stability.Consequently,Wp ET is suggested as a new evaluation index of coal burst liability.展开更多
The single event effect(SEE) is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures. The linear energy transfer(LET) of ions is commonly...The single event effect(SEE) is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures. The linear energy transfer(LET) of ions is commonly investigated in studies of SEE. The use of a thin detector is an economical way of directly measuring the LET in space. An LET telescope consists of a thin detector as the front detector(D1), along with a back detector that indicates whether D1 was penetrated. The particle radiation effect monitor(PREM) introduced in this paper is designed to categorize the LET into four bins of 0.2–0.4, 0.4–1.0, 1.0–2.0 and 2.0–20 Me V·cm^2/mg, and one integral bin of LET>20 Me V·cm^2/mg. After calibration with heavy ions and Geant4 analysis, the LET boundaries of the first four bins are determined to be 0.236, 0.479, 1.196, 2.254, and 17.551 Me V·cm^2/mg, whereas that of the integral bin is determined to be LET>14.790 Me V·cm^2/mg. The acceptances are calculated by Geant4 analysis as 0.452, 0.451, 0.476, 0.446, and 1.334, respectively. The LET accuracy is shown to depend on the thickness of D1; as D1 is made thinner, the accuracy of the measured values increases.展开更多
The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method ...The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method was proposed to calculate the PEECR.The PEECR uses a simplified method to calculate the peak elastic strain energy.To solve this problem accurately,triaxial cyclic loading-unloading compression tests were carried out on shale.Strain energy parameters were calculated from the test curves.The results show that there is a linear relationship between the elastic strain energy and input strain energy,indicating that the linear energy storage law in rock is applicable to triaxial compression state.The universality of the linear energy storage law of rock under triaxial compression is also verified by the data in the published literature.Then,the peak elastic strain energy can be accurately determined using the linear energy storage law,and the PEECR is improved based on this.Finally,the PEECR and the improved PEECR were compared using the triaxial cyclic loading-unloading compression tests on three rocks(shale,red sandstone and granite),and the improved PEECR was compared with 11 existing energy-based brittleness indexes.The results show that the improved PEECR can further reflect the rock brittleness more accurately.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
Several chromatography systems with ionic liquids and a mixture of water with the modifier as mobile phase were characterized via the linear solvation energy relationships（LSER） model. The effects of the ionic liqui...Several chromatography systems with ionic liquids and a mixture of water with the modifier as mobile phase were characterized via the linear solvation energy relationships（LSER） model. The effects of the ionic liquids and modifier（methanol） concentrations on the retention of 10 solutes（caffeine, pyridine, aniline, phenol, methylparaben, acetopenone, m-cresol, p-cresol, o-cresol, and benzene） were discussed. The LSER model demonstrated high potential to predict retention factors with high squared correlation coefficients（r^2〉 0.97）. A comparison of predictable and experimental retention factors revealed that LSER can adequately reproduce the experimental retention factors of the solutes under different investigated experimental conditions. This model is a helpful tool to evaluate the retention characteristics of ionic liquid systems and to understand the interactions of solutes and ionic liquids.展开更多
The correlation relationships of apparent extraction equilibrium constant (1gK(ex)) with the electronic effect parameter( Sigma sigma(Phi)) and the steric effect parameter ( Sigma upsilon ) of the substituents in extr...The correlation relationships of apparent extraction equilibrium constant (1gK(ex)) with the electronic effect parameter( Sigma sigma(Phi)) and the steric effect parameter ( Sigma upsilon ) of the substituents in extractant molecules are investigated by linear regression analysis in the extraction of rare earths by various classes and structures of monoacidic organophosphorus extractants. The results indicate that in Linear free energy relationship formula 1gK(ex) = rho Sigma sigma(Phi) + psi Sigma upsilon + h generally follows for this kind of extraction systems. Accordingly, the quantitative structure-behaviour relationships of extractants are discussed. These relationships can be preliminarily applied to predict the 1gK(ex) values of rare earth extraction with definite structures of this class of extractants, and thus can provide some directions for the design of new RE extractants.展开更多
The properties of absorption spectra are presented and the linear correlations of Hammett constants with the 0-0 transition energy(E_(o,o))of S_←S_o, and the ratios of oscillator strength(f/f)are used to probe the in...The properties of absorption spectra are presented and the linear correlations of Hammett constants with the 0-0 transition energy(E_(o,o))of S_←S_o, and the ratios of oscillator strength(f/f)are used to probe the interactions betwee π-electron of aromatic maerocycles or metal ion of complexes with the sub- stituents on β-position of benzene ring for porphyrin-like maerocyclic compounds.展开更多
To evaluate the coal burst proneness more precisely,a new energy criterion namely the residual elastic energy index was proposed.This study begins by performing the single-cyclic loading-unloading uniaxial compression...To evaluate the coal burst proneness more precisely,a new energy criterion namely the residual elastic energy index was proposed.This study begins by performing the single-cyclic loading-unloading uniaxial compression tests with five pre-peak unloading stress levels to explore the energy storage characteristics of coal.Five types of coals from different mines were tested,and the instantaneous destruction process of the coal specimens under compression loading was recorded using a high speed camera.The results showed a linear relationship between the elastic strain energy density and input energy density,which confirms the linear energy storage law of coal.Based on this linear energy storage law,the peak elastic strain energy density of each coal specimen was obtained precisely.Subsequently,a new energy criterion of coal burst proneness was established,which was called the residual elastic energy index(defined as the difference between the peak elastic strain energy density and post peak failure energy density).Considering the destruction process and actual failure characteristics of coal specimens,the accuracy of evaluating coal burst proneness based on the residual elastic energy index was examined.The results indicated that the residual elastic energy index enables reliable and precise evaluations of the coal burst proneness.展开更多
To study the energy storage and dissipation characteristics of deep rock under two-dimensional compression with constant confining pressure,the single cyclic loading-unloading two-dimensional compression tests were pe...To study the energy storage and dissipation characteristics of deep rock under two-dimensional compression with constant confining pressure,the single cyclic loading-unloading two-dimensional compression tests were performed on granite specimens with two height-to-width(H/W)ratios under five confining pressures.Three energy density parameters(input energy density,elastic energy density and dissipated energy density)in the axial and lateral directions of granite specimens under different confining pressures were calculated using the area integral method.The experimental results show that,for the specimens with a specific H/W ratio,these three energy density parameters in the axial and lateral directions increase nonlinearly with the confining pressure as quadratic polynomial functions.Under constant confining pressure compression,the linear energy storage law of granite specimens in the axial and lateral directions was founded.Using the linear energy storage law in different directions,the elastic energy density in various directions(axial elastic energy density,lateral elastic energy density and total elastic energy density)of granite under any specific confining pressures can be calculated.When the H/W ratio varies from 1:1 to 2:1,the lateral compression energy storage coefficient increases and the corresponding axial compression energy storage coefficient decreases,while the total compression energy storage coefficient is almost independent of the H/W ratio.展开更多
Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can ...Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can affect the energy storage, dissipation, and surplus in rock. To explore the influence of temperature on the energy storage and dissipation characteristics and rockburst proneness, the present study has carried out a range of the uniaxial compression(UC) and single-cyclic loading-unloading uniaxial compression(SCLUC) tests on pre-heated granite specimens at 20℃-700℃. The results demonstrate that the rockburst proneness of pre-heated granite initially increases and subsequently decreases with the increase of temperature. The temperature of 300℃ has been found to be the threshold for rockburst proneness. Meanwhile, it is found that the elastic strain energy density increases linearly with the total input strain energy density for the pre-heated granites, confirming that the linear energy property of granite has not been altered by temperature. According to this inherent property, the peak elastic strain energy of pre-heated granites can be calculated accurately. On this basis, utilising the residual elastic energy index, the rockburst proneness of pre-heated granite can be determined quantitatively. The obtained results from high to low are: 317.9 k J/m^(3)(300℃), 264.1 k J/m^(3)(100℃), 260.6 k J/m^(3)(20℃), 235.5 k J/m^(3)(500℃), 158.9 k J/m^(3)(700℃), which are consistent with the intensity of actual rockburst for specimens. In addition, the relationship between temperature and energy storage capacity(ESC) of granite was discussed, revealing that high temperature impairs ESC of rocks, which is essential for reducing the rockburst proneness. This study provides some new insights into the rockburst proneness evaluation in high-temperature rock engineering.展开更多
To examine the effect of bedding angle upon burst proneness in terms of energy,phyllites with seven various bedding angles are selected for conventional uniaxial compression and single-cyclic loading eunloading uniaxi...To examine the effect of bedding angle upon burst proneness in terms of energy,phyllites with seven various bedding angles are selected for conventional uniaxial compression and single-cyclic loading eunloading uniaxial compression tests.The ejection and failure during compression process of phyllites are monitored in real-time by high-speed camera system.The results demonstrate that the phyllites with different bedding angles all consistently follow the linear energy storage and dissipation(LESD)law during compression.The ultimate energy storage of phyllites with varying bedding angles can be calculated precisely via using the LESD law.Based on this,four kinds of energy-based rockburst indices are applied to quantitatively assess the burst proneness for phyllites.Combined with the recorded images of high-speed camera system,ejection distance,and mass of rock fragments and powder,the burst proneness for phyllites with various bedding angles is qualitatively evaluated adopting the far-field ejection mass ratio.Next,burst proneness of anisotropic phyllites is assessed quantitatively and qualitatively.It is found that phyllites with bedding angles of 0°,15°,and 90°have a high burst proneness,and that with bedding angle of 30°has a medium burst proneness,whereas the ones with bedding angles of 45°,60°,and 75°have a low burst proneness.Finally,the published experimental data of shale and sandstone specimens with different bedding angles are extracted,and it is preliminarily verified that the bedding angle does not change the LESD law of rocks.展开更多
In this work,a 4H-SiC-based soft X-ray single photon detector with photon energy resolution capability is demonstrated.The 4H-SiC p-i-n detector with an 80-μm-thick epi-layer and low intrinsic doping exhibits a low l...In this work,a 4H-SiC-based soft X-ray single photon detector with photon energy resolution capability is demonstrated.The 4H-SiC p-i-n detector with an 80-μm-thick epi-layer and low intrinsic doping exhibits a low leakage current of∼1.8 pA at−180 V,guaranteeing superior dark current performance for single photon detection with low electronic noise.An amplification strategy employing an active switch in the charge-sensitive amplifier has also been developed,where feedback-resistance-related thermal noise has been well eliminated,contributing to lower electronic noise in the amplification stage.By tuning the shaping time in the analog-to-digital circuit for precise signal processing,an optimal photon energy resolution has been achieved with a duration time within 6.4µs,achieving an energy analysis standard deviation below 5.7%.Ultimately,superior linearity has been obtained between the output pulse amplitude and the characteristic photon energy by utilizing a series of different metal targets,opening a new opportunity for advanced soft X-ray detection technology based on wide bandgap semiconductors.展开更多
In this work,the microstructural evolution,micro-crack formation,and mechanical anisotropy of the selective laser melted(SLM)carbon-free Mar-M509 Co-based superalloy were systematically studied under different linear ...In this work,the microstructural evolution,micro-crack formation,and mechanical anisotropy of the selective laser melted(SLM)carbon-free Mar-M509 Co-based superalloy were systematically studied under different linear energy densities(LED).Observation shows that the SLM Mar-M509 superalloy possesses a fully dense structure,whereas some microcracks exist along the building direction.The electron backscatter diffraction results reveal that dominant columnar grains tend to elongate along the building direction parallel to the XZ plane.Meanwhile,both a<001>near fiber texture and a{100}<001>near sheet texture are observed in different specimens.For the specimen with fiber texture,a high misorientation angle exists among different columnar grains,which aggravated the generation of micro-cracks under thermal stress.Higher LED results in higher micro-crack density in the SLM specimen due to higher thermal stress.Mar-M509 specimen fabricated under lower LED exhibits higher tensile strength due to more significant grain refinement.More prominent anisotropy of tensile performance was found in the high LED specimen,which can be attributed to the higher density of micro-cracks and crystallographic texture.Furthermore,the SLM Mar-M509 superalloy exhibits better mechanical properties than the traditional cast technique.In summary,this work can contribute to the development and the future application of SLM-fabricated Co-based superalloy.展开更多
The single-event effect（SEE） is the most serious problem in space environment.The modern semiconductor technology is concerned with the feasibility of the linear energy transfer（LET） as metric in characterizing SE...The single-event effect（SEE） is the most serious problem in space environment.The modern semiconductor technology is concerned with the feasibility of the linear energy transfer（LET） as metric in characterizing SEE induced by heavy ions.In this paper,we calibrate the detailed static random access memory（SRAM） cell structure model of an advanced field programmable gate array（FPGA） device using the computer-aided design tool,and calculate the heavy ion energy loss in multi-layer metal utilizing Geant4.Based on the heavy ion accelerator experiment and numerical simulation,it is proved that the metric of LET at the device surface,ignoring the top metal material in the advanced semiconductor device,would underestimate the SEE.In the SEE evaluation in space radiation environment the top-layers on the semiconductor device must be taken into consideration.展开更多
The single event effect of a silicon–germanium heterojunction bipolar transistor(SiGe HBT) was thoroughly investigated. By considering the worst bias condition, the sensitive area of the proposed device was scanned w...The single event effect of a silicon–germanium heterojunction bipolar transistor(SiGe HBT) was thoroughly investigated. By considering the worst bias condition, the sensitive area of the proposed device was scanned with a pulsed laser.With variation of the collector bias and pulsed laser incident energy, the single event transient of the SiGe HBT was studied.Moreover, the single event transient produced by laser irradiation at a wavelength of 532 nm was more pronounced than at a wavelength of 1064 nm. Finally, the impact of the equivalent linear energy transfer of the 1064 nm pulsed laser on the single event transient was qualitatively examined by performing technology computer-aided design simulations, and a good consistency between the experimental data and the simulated outcomes was attained.展开更多
20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the ...20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the experimental data of 20 compounds＇ aquatic photogen toxicity（-lgEC50） are used to perform stepwise regression in order to obtain two predicted -lgEC50 correlation models whose correlation coefficients R^2 are respectively 0.9186 and 0.9567. In addition, parameters of chlorine atom＇s substitutive positions and their correlations （NPCs） are taken as descriptors to obtain another predicted -lgEC50 model with the correlation coefficient R2 of 0.9444. Correlation degree of each independent variable in the three models is verified by using variance inflation factors （VIF） and t value. In the cross-validation method, cross-validation coefficients q^2 of 3 models are respectively 0.8748, 0.9119 and 0.8993, which indicates that the relativity and prediction ability of this model are superior to those of the model obtained by topological and BLYP methods.展开更多
The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-poly...The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans(PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( E _ LUMO ), energy of the highest occupied molecular orbit( E _ HOMO ), the most positive charge on a hydrogen atom( q _+), and the most negative atomic partial charge( q _-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n -octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(52225403)the National Natural Science Foundation of China(42077244).
文摘The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.
基金supported by the National Natural Science Foundation of China(Grant Nos.42077244 and 41877272)the Fundamental Research Funds for the Central Universities(Grant No.2242022k30054)。
文摘The rationality of using strain energy storage index(Wet)for evaluating rockburst proneness was theoretically verified based on linear energy storage(LES)law in this study.The LES law is defined as the linear relationship between the elastic strain energy stored inside the solid material and the input strain energy during loading.It is used to determine the elastic strain energy and dissipated strain energy of rock specimens at various loading/unloading stress levels.The results showed that the Wetvalue obtained from experiments was close to the corresponding theoretical one from the LES law.Furthermore,with an increase in the loading/unloading stress level,the ratio of elastic strain energy to dissipated strain energy converged to the peak-strength strain energy storage index(Wp et).This index is stable and can better reflect the relative magnitudes of the stored energy and the dissipated energy of rocks at the whole pre-peak stage than the strain energy storage index.The peak-strength strain energy storage index can replace the conventional strain energy storage index as a new index for evaluating rockburst proneness.
基金Supported by the Key Laboratory of Microsatellites,Chinese Academy of Sciences
文摘A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130？nm CMOS bulk Si and silicon-on-insulator （SOI） technologies. The effectiveness of linear energy transfer （LET） with a tilted ion beam at the 130？nm technology node is obtained. Tests of tilted angles θ=0 ° , 30 ° and 60 ° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40？MeVcm 2 /mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ , furthermore the effective LET for SOI is more closely in inverse proportion to cosθ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cosθ very well, which is also specifically explained.
基金supported by the National Natural Science Foundation of China (Grant No.41877272,42077244).
文摘The strain energy storage index WET was widely used to evaluate coal burst liability,but the scientific evidence for selecting the unloading stress level interval(around 80%of peak strength)remains lacking,and WET can not reflect the energy storage and dissipation ratio(ESD ratio)of the whole pre-peak stage for coal materials.In this study,these two key problems in WET calculation and application were solved based on the linear energy storage(LES)law.The LES law was defined as the linear relationship between the elastic strain energy and input strain energy for solid material during loading.Using the LES law,the elastic strain energy and dissipated strain energy of at 10 types of coals were calculated precisely,and ideal ESD ratio and general ESD ratio at any stress level will be obtained subsequently.The results also show that WET is extremely close to the ideal and general ESD ratio,which proves that the selecting stress level of WET calculation is scientific and reasonable.Furthermore,the general ESD ratio converges to the peak ESD ratio(namely peak strain energy storage index WET P)as stress level increases.Compared with WET,Wp ET not only reflects the ESD ratio of coal materials over the whole pre-peak loading stage,but also exhibits excellent stability.Consequently,Wp ET is suggested as a new evaluation index of coal burst liability.
基金supported by the National Natural Science Foundation of China(Grant No.41374181)the National Key Scientific Instrument and Equipment Development ProjectsChina(Grant No.2012YQ03014207)
文摘The single event effect(SEE) is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures. The linear energy transfer(LET) of ions is commonly investigated in studies of SEE. The use of a thin detector is an economical way of directly measuring the LET in space. An LET telescope consists of a thin detector as the front detector(D1), along with a back detector that indicates whether D1 was penetrated. The particle radiation effect monitor(PREM) introduced in this paper is designed to categorize the LET into four bins of 0.2–0.4, 0.4–1.0, 1.0–2.0 and 2.0–20 Me V·cm^2/mg, and one integral bin of LET>20 Me V·cm^2/mg. After calibration with heavy ions and Geant4 analysis, the LET boundaries of the first four bins are determined to be 0.236, 0.479, 1.196, 2.254, and 17.551 Me V·cm^2/mg, whereas that of the integral bin is determined to be LET>14.790 Me V·cm^2/mg. The acceptances are calculated by Geant4 analysis as 0.452, 0.451, 0.476, 0.446, and 1.334, respectively. The LET accuracy is shown to depend on the thickness of D1; as D1 is made thinner, the accuracy of the measured values increases.
基金supported by the National Natural Science Foundation of China(Grant No.42077244).
文摘The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method was proposed to calculate the PEECR.The PEECR uses a simplified method to calculate the peak elastic strain energy.To solve this problem accurately,triaxial cyclic loading-unloading compression tests were carried out on shale.Strain energy parameters were calculated from the test curves.The results show that there is a linear relationship between the elastic strain energy and input strain energy,indicating that the linear energy storage law in rock is applicable to triaxial compression state.The universality of the linear energy storage law of rock under triaxial compression is also verified by the data in the published literature.Then,the peak elastic strain energy can be accurately determined using the linear energy storage law,and the PEECR is improved based on this.Finally,the PEECR and the improved PEECR were compared using the triaxial cyclic loading-unloading compression tests on three rocks(shale,red sandstone and granite),and the improved PEECR was compared with 11 existing energy-based brittleness indexes.The results show that the improved PEECR can further reflect the rock brittleness more accurately.
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 Center for Advanced Bioseparation Technology, Inha University, Korea
文摘Several chromatography systems with ionic liquids and a mixture of water with the modifier as mobile phase were characterized via the linear solvation energy relationships（LSER） model. The effects of the ionic liquids and modifier（methanol） concentrations on the retention of 10 solutes（caffeine, pyridine, aniline, phenol, methylparaben, acetopenone, m-cresol, p-cresol, o-cresol, and benzene） were discussed. The LSER model demonstrated high potential to predict retention factors with high squared correlation coefficients（r^2〉 0.97）. A comparison of predictable and experimental retention factors revealed that LSER can adequately reproduce the experimental retention factors of the solutes under different investigated experimental conditions. This model is a helpful tool to evaluate the retention characteristics of ionic liquid systems and to understand the interactions of solutes and ionic liquids.
文摘The correlation relationships of apparent extraction equilibrium constant (1gK(ex)) with the electronic effect parameter( Sigma sigma(Phi)) and the steric effect parameter ( Sigma upsilon ) of the substituents in extractant molecules are investigated by linear regression analysis in the extraction of rare earths by various classes and structures of monoacidic organophosphorus extractants. The results indicate that in Linear free energy relationship formula 1gK(ex) = rho Sigma sigma(Phi) + psi Sigma upsilon + h generally follows for this kind of extraction systems. Accordingly, the quantitative structure-behaviour relationships of extractants are discussed. These relationships can be preliminarily applied to predict the 1gK(ex) values of rare earth extraction with definite structures of this class of extractants, and thus can provide some directions for the design of new RE extractants.
文摘The properties of absorption spectra are presented and the linear correlations of Hammett constants with the 0-0 transition energy(E_(o,o))of S_←S_o, and the ratios of oscillator strength(f/f)are used to probe the interactions betwee π-electron of aromatic maerocycles or metal ion of complexes with the sub- stituents on β-position of benzene ring for porphyrin-like maerocyclic compounds.
基金This work was supported by the National Natural Science Foundation of China(No.41877272)the Fundamental Research Funds for the Central Universities of Southeast University(No.2242021R10080).
文摘To evaluate the coal burst proneness more precisely,a new energy criterion namely the residual elastic energy index was proposed.This study begins by performing the single-cyclic loading-unloading uniaxial compression tests with five pre-peak unloading stress levels to explore the energy storage characteristics of coal.Five types of coals from different mines were tested,and the instantaneous destruction process of the coal specimens under compression loading was recorded using a high speed camera.The results showed a linear relationship between the elastic strain energy density and input energy density,which confirms the linear energy storage law of coal.Based on this linear energy storage law,the peak elastic strain energy density of each coal specimen was obtained precisely.Subsequently,a new energy criterion of coal burst proneness was established,which was called the residual elastic energy index(defined as the difference between the peak elastic strain energy density and post peak failure energy density).Considering the destruction process and actual failure characteristics of coal specimens,the accuracy of evaluating coal burst proneness based on the residual elastic energy index was examined.The results indicated that the residual elastic energy index enables reliable and precise evaluations of the coal burst proneness.
基金Projects(41877272,51974359)supported by the National Natural Science Foundation of China。
文摘To study the energy storage and dissipation characteristics of deep rock under two-dimensional compression with constant confining pressure,the single cyclic loading-unloading two-dimensional compression tests were performed on granite specimens with two height-to-width(H/W)ratios under five confining pressures.Three energy density parameters(input energy density,elastic energy density and dissipated energy density)in the axial and lateral directions of granite specimens under different confining pressures were calculated using the area integral method.The experimental results show that,for the specimens with a specific H/W ratio,these three energy density parameters in the axial and lateral directions increase nonlinearly with the confining pressure as quadratic polynomial functions.Under constant confining pressure compression,the linear energy storage law of granite specimens in the axial and lateral directions was founded.Using the linear energy storage law in different directions,the elastic energy density in various directions(axial elastic energy density,lateral elastic energy density and total elastic energy density)of granite under any specific confining pressures can be calculated.When the H/W ratio varies from 1:1 to 2:1,the lateral compression energy storage coefficient increases and the corresponding axial compression energy storage coefficient decreases,while the total compression energy storage coefficient is almost independent of the H/W ratio.
基金supported by the National Natural Science Foundation of China (Grant No. 41877272)the Fundamental Research Funds for the Central Universities (Grant No.2242022k30054)the Fundamental Research Funds for the Central Universities of Central South University (Grant No.2021zzts0861)。
文摘Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can affect the energy storage, dissipation, and surplus in rock. To explore the influence of temperature on the energy storage and dissipation characteristics and rockburst proneness, the present study has carried out a range of the uniaxial compression(UC) and single-cyclic loading-unloading uniaxial compression(SCLUC) tests on pre-heated granite specimens at 20℃-700℃. The results demonstrate that the rockburst proneness of pre-heated granite initially increases and subsequently decreases with the increase of temperature. The temperature of 300℃ has been found to be the threshold for rockburst proneness. Meanwhile, it is found that the elastic strain energy density increases linearly with the total input strain energy density for the pre-heated granites, confirming that the linear energy property of granite has not been altered by temperature. According to this inherent property, the peak elastic strain energy of pre-heated granites can be calculated accurately. On this basis, utilising the residual elastic energy index, the rockburst proneness of pre-heated granite can be determined quantitatively. The obtained results from high to low are: 317.9 k J/m^(3)(300℃), 264.1 k J/m^(3)(100℃), 260.6 k J/m^(3)(20℃), 235.5 k J/m^(3)(500℃), 158.9 k J/m^(3)(700℃), which are consistent with the intensity of actual rockburst for specimens. In addition, the relationship between temperature and energy storage capacity(ESC) of granite was discussed, revealing that high temperature impairs ESC of rocks, which is essential for reducing the rockburst proneness. This study provides some new insights into the rockburst proneness evaluation in high-temperature rock engineering.
基金supported by the National Natural Science Foundation of China(Grant No.42077244).
文摘To examine the effect of bedding angle upon burst proneness in terms of energy,phyllites with seven various bedding angles are selected for conventional uniaxial compression and single-cyclic loading eunloading uniaxial compression tests.The ejection and failure during compression process of phyllites are monitored in real-time by high-speed camera system.The results demonstrate that the phyllites with different bedding angles all consistently follow the linear energy storage and dissipation(LESD)law during compression.The ultimate energy storage of phyllites with varying bedding angles can be calculated precisely via using the LESD law.Based on this,four kinds of energy-based rockburst indices are applied to quantitatively assess the burst proneness for phyllites.Combined with the recorded images of high-speed camera system,ejection distance,and mass of rock fragments and powder,the burst proneness for phyllites with various bedding angles is qualitatively evaluated adopting the far-field ejection mass ratio.Next,burst proneness of anisotropic phyllites is assessed quantitatively and qualitatively.It is found that phyllites with bedding angles of 0°,15°,and 90°have a high burst proneness,and that with bedding angle of 30°has a medium burst proneness,whereas the ones with bedding angles of 45°,60°,and 75°have a low burst proneness.Finally,the published experimental data of shale and sandstone specimens with different bedding angles are extracted,and it is preliminarily verified that the bedding angle does not change the LESD law of rocks.
基金supported by the Innovation Program for Quantum Science and Technology(No.2021ZD0303400)the National Natural Science Foundation of China(Nos.62374084,61921005,62104102,U2141241,and U21A20496)+1 种基金the Jiangsu Provincial Key Research and Development Program(No.BE2023018)the Fundamental Research Funds for the Central Universities.
文摘In this work,a 4H-SiC-based soft X-ray single photon detector with photon energy resolution capability is demonstrated.The 4H-SiC p-i-n detector with an 80-μm-thick epi-layer and low intrinsic doping exhibits a low leakage current of∼1.8 pA at−180 V,guaranteeing superior dark current performance for single photon detection with low electronic noise.An amplification strategy employing an active switch in the charge-sensitive amplifier has also been developed,where feedback-resistance-related thermal noise has been well eliminated,contributing to lower electronic noise in the amplification stage.By tuning the shaping time in the analog-to-digital circuit for precise signal processing,an optimal photon energy resolution has been achieved with a duration time within 6.4µs,achieving an energy analysis standard deviation below 5.7%.Ultimately,superior linearity has been obtained between the output pulse amplitude and the characteristic photon energy by utilizing a series of different metal targets,opening a new opportunity for advanced soft X-ray detection technology based on wide bandgap semiconductors.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0705300)the Chinese National Science and Technology Major Project“Aeroengine and Gas Turbine”(No.2017-VII0008-0102)+4 种基金the Shanghai Science and Technology Committee(No.19DZ1100704)Shanghai Shuguang Program(No.20SG42)Shanghai Sailing Program(No.19YF1415900)the National Natural Science Foundation of China(No.52001191)the Shanghai Rising-Star Program(No.20QA1403800)。
文摘In this work,the microstructural evolution,micro-crack formation,and mechanical anisotropy of the selective laser melted(SLM)carbon-free Mar-M509 Co-based superalloy were systematically studied under different linear energy densities(LED).Observation shows that the SLM Mar-M509 superalloy possesses a fully dense structure,whereas some microcracks exist along the building direction.The electron backscatter diffraction results reveal that dominant columnar grains tend to elongate along the building direction parallel to the XZ plane.Meanwhile,both a<001>near fiber texture and a{100}<001>near sheet texture are observed in different specimens.For the specimen with fiber texture,a high misorientation angle exists among different columnar grains,which aggravated the generation of micro-cracks under thermal stress.Higher LED results in higher micro-crack density in the SLM specimen due to higher thermal stress.Mar-M509 specimen fabricated under lower LED exhibits higher tensile strength due to more significant grain refinement.More prominent anisotropy of tensile performance was found in the high LED specimen,which can be attributed to the higher density of micro-cracks and crystallographic texture.Furthermore,the SLM Mar-M509 superalloy exhibits better mechanical properties than the traditional cast technique.In summary,this work can contribute to the development and the future application of SLM-fabricated Co-based superalloy.
文摘The single-event effect（SEE） is the most serious problem in space environment.The modern semiconductor technology is concerned with the feasibility of the linear energy transfer（LET） as metric in characterizing SEE induced by heavy ions.In this paper,we calibrate the detailed static random access memory（SRAM） cell structure model of an advanced field programmable gate array（FPGA） device using the computer-aided design tool,and calculate the heavy ion energy loss in multi-layer metal utilizing Geant4.Based on the heavy ion accelerator experiment and numerical simulation,it is proved that the metric of LET at the device surface,ignoring the top metal material in the advanced semiconductor device,would underestimate the SEE.In the SEE evaluation in space radiation environment the top-layers on the semiconductor device must be taken into consideration.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61574171, 61704127, 11875229,51872251, and 12027813)。
文摘The single event effect of a silicon–germanium heterojunction bipolar transistor(SiGe HBT) was thoroughly investigated. By considering the worst bias condition, the sensitive area of the proposed device was scanned with a pulsed laser.With variation of the collector bias and pulsed laser incident energy, the single event transient of the SiGe HBT was studied.Moreover, the single event transient produced by laser irradiation at a wavelength of 532 nm was more pronounced than at a wavelength of 1064 nm. Finally, the impact of the equivalent linear energy transfer of the 1064 nm pulsed laser on the single event transient was qualitatively examined by performing technology computer-aided design simulations, and a good consistency between the experimental data and the simulated outcomes was attained.
基金973 National Basic Research Program of China (2003CB415002)
文摘20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the experimental data of 20 compounds＇ aquatic photogen toxicity（-lgEC50） are used to perform stepwise regression in order to obtain two predicted -lgEC50 correlation models whose correlation coefficients R^2 are respectively 0.9186 and 0.9567. In addition, parameters of chlorine atom＇s substitutive positions and their correlations （NPCs） are taken as descriptors to obtain another predicted -lgEC50 model with the correlation coefficient R2 of 0.9444. Correlation degree of each independent variable in the three models is verified by using variance inflation factors （VIF） and t value. In the cross-validation method, cross-validation coefficients q^2 of 3 models are respectively 0.8748, 0.9119 and 0.8993, which indicates that the relativity and prediction ability of this model are superior to those of the model obtained by topological and BLYP methods.
基金TheNationalKeyBasicResearchFoundationofChina (No .G1 9990 4 571 1 )
文摘The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans(PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( E _ LUMO ), energy of the highest occupied molecular orbit( E _ HOMO ), the most positive charge on a hydrogen atom( q _+), and the most negative atomic partial charge( q _-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n -octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.
