The effect of the face thickness to core height ratio on different multi-layer pyramidal core sandwich columns under in-plane compression is investigated theoretically and numerically. Numerical simulation is in good ...The effect of the face thickness to core height ratio on different multi-layer pyramidal core sandwich columns under in-plane compression is investigated theoretically and numerically. Numerical simulation is in good agreement with theory. Results indicate that one specified face thickness to core height ratio corresponds to one optimum layer number of multi-layer pyramidal core sandwich columns in consideration of engineering application. This result can guide the sandwich structure design.展开更多
The in-plane compressive characteristics of the ultra-high molecular weight polyethylene(UHMWPE)fibre(Dyneema█)reinforced composites,both in 0/90°and±45°fibre orientations with respect to the loading d...The in-plane compressive characteristics of the ultra-high molecular weight polyethylene(UHMWPE)fibre(Dyneema█)reinforced composites,both in 0/90°and±45°fibre orientations with respect to the loading direction,have been investigated.The composite made from unidirectional high modulus fibres(volume fraction 83%)and low strength polyurethane matrix(volume fraction 17%)is layered in an orthogonally alternating manner.The different failure mechanisms for the composites with 0/90°and±45°fibre orientations have been detected with the methods of experimental measurement,SEM observation and theoretical analysis.The composites specimens of 0/90°fibre orientation failed with macro-buckling of the high-modulus UHMWEP fibre layers with the matrix damage,whereas the specimens of±45°fibre orientation failed with the shearing of the soft matrix.Hence,the composite specimens in 0/90°fibre orientation had higher stiffness as well as compressive strength than those in±45°fibre orientation.The failure criteria of the composites under in-plane compression was employed to characterize the failure mechanism.Compared with the traditional thermoset matrix,the soft thermoplastic matrix leads to lower strength and higher failure strain of fibre reinforced composites under in-plane compression.In addition,the composite specimens cut by waterjet machine exhibited higher stress levels than those cut by bandsaw that introduced more initial imperfections with the temperature rising and tensile shocking.The comparison between the methodologies for cutting the tough composites can provide a valuable suggestion to obtain required composite structures without reducing the mechanical properties.展开更多
Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluat...Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.展开更多
An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic r...An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.展开更多
Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that...Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that the hydrogen increases the dislocation density,reduces the yield stress,and accelerates the formation and intersection of slip bands,with hydrogen-induced cracks initiating at slip band intersections.X-ray diffraction confirms the absence of martensitic transformation,ruling out the role of martensitic transformation in HE.The micropillar compression technique is highly sensitive for characterizing hydrogen-material interactions,owing to the material’s low hydrogen diffusivity and the small size of its hydrogen-affected zone.These findings align with the hydrogen-enhanced localized plasticity mechanism.展开更多
To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-r...To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.展开更多
In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties ...In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties and acoustic emission(AE)behavior of rocks,this study conducted uniaxial compression experiments on sandstones with varying degrees of wetting under both natural conditions and water-chemical environments.In addition,the study combined AE equipment with digital image correlation(DIC)to monitor the entire failure process.Using the sliding window algorithm,the variation in the variance of AE characteristic parameters during the process of sandstone loading to failure is analyzed from the perspective of critical slowing down.This analysis enables the effective identification of the early warning signal before failure.The experimental findings suggest that an increase in wetting height results in a gradual decrease in peak stress,accompanied by a concomitant increase in the percentage of shear cracks.The characteristic parameters,including energy,amplitude,and ringing count,all exhibit critical slowing phenomena.The waveform of AE characteristic parameters of the same sample is similar,and the mutation time of the precursor signal is roughly the same.All signals appear in the irreversible plastic deformation stage of microcrack initiation.The integration of critical slowing down theory and the b-value early warning method facilitates a more comprehensive evaluation of the stability of rock mass,thereby significantly enhancing the efficiency and safety of disaster prevention measures.展开更多
We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based im...We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based imaging with sub-micrometer spatial and femtosecond temporal resolution,supported by hydrodynamic and particle-in-cell simulations,we reveal how return current density depends precisely on wire diameter,material properties,and incident laser energy.We identify deviations from simple theoretical predictions due to geometrically influenced electron escape dynamics.These results refine and confirm the scaling laws essential for predictive modeling in high-energy-density physics and inertial fusion research.展开更多
In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC wa...In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC was used to drive the adiabatic compressed air energy storage(ACAES),while the intake air of the GTCC was heated by the compression heat of theACAES.Based on a 67.3MW GTCC,under specific demand load distribution,a CPG system and a benchmark system(BS)were designed,both of which used 9.388% of the GTCC output power to drive the ACAES.The performance of the CPG and the BS without intake air heating was compared.The results show that the load rate of the GTCC in the CPG system during off-peak periods is significantly enhanced,and the average operating efficiency of the GTCC is increased by 1.19 percentage points.However,in the BS system,due to the single collaborativemethod of load shifting,the GTCC operative efficiency is almost increased by 1.00 percentage points under different ambient temperatures.In a roundtrip cycle at an ambient temperature of 288.15K,the systemefficiency of the CPG reaches 0.5010,which is 0.62 percentage points higher than the operative efficiency of 0.4948 in the standalone GTCC;while the system efficiency of the BS is slightly inferior to that of the standalone GTCC.The findings confirm the technical feasibility and performance improvement of the ACAES-GTCC collaborative power generation system.展开更多
The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics ...The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics of frozen sodium sulfate saline sandy soil,a series of uniaxial compression tests were performed by integrating digital image correlation(DIC)technology into the testing apparatus.The evolution law of the uniaxial compression strength(UCS),the failure strain,and the formation of the shear band of the frozen sodium sulfate saline sandy soil were analyzed.The test results show that within the scope of this study,with the increase of salt content,both the UCS and the shear band angle initially decrease with increasing salt content before showing an increase.In contrast,the failure strain and the width of the shear band exhibit an initial increase followed by a decrease in the samples.In addition,to investigate the brittle failure characteristics of frozen sodium sulfate saline sandy soil,two classic brittleness evaluation methods were employed to quantitatively assess the brittleness level for the soil samples.The findings suggest that the failure characteristics under all test conditions in this study belong to the transition stage between brittle and ductile,indicating that frozen sodium sulfate saline sandy soil exhibits certain brittle behavior under uniaxial compression conditions,and the brittleness index basically decreases and then increases with the rise in salt content.展开更多
The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at c...The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at current density of 60 A/mm^(2) and strain rate of 0.1 s^(−1),the ultimate tensile stress shows a significant decrease from approximately 3000 MPa to 1900 MPa with reduction ratio of about 36.7%.However,as current density increases,elongation decreases due to intermediate temperature embrittlement.This is because the current induces Joule effect,which then leads to stress concentration and more defect formation.Moreover,the flow stress is decreased with the increase in strain rate at constant current density.展开更多
The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compressio...The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of aggregates.The mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically analyzed.The results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,respectively.However,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the aggregates.Theσ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite trend.Theε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse aggregates.With increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.展开更多
Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regu...Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength,better durability and environmental friendli-ness,as well as a good engineering application prospect.In this paper,the shear strength of sand column was tested by triaxial compression tests,and the strength index was obtained.In order to further study the micro-strength mechanism and the failure process,based on the discrete element method,a numerical model of MICP cemented sand column was established considering the factors of matrix soil particle gradation,particle mor-phology,content ratio of induced calcium carbonate,pore distribution characteristics,inter-particle cementation and so on.The failure process of MICP cemented sand column under load was analysed by numerical simulation,and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions.The results indicate that compared with the actual triaxial tests of MICP cemented sand column,although there are deviations in stress and strain,cohesion and internal friction angle,the numerical simulation shows similar development law and intensity amplitude,and the same failure trend.The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.展开更多
The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The spec...The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The specimens were deformed under varying degrees of IPS strain(γ12=0.05,0.10,and 0.15)using a customized jig.Electron backscatter diffraction(EBSD)observations revealed profuse tensile twinning(TTW)even at an IPS strain of 0.05,with its intensity continuously increased as the IPS strain increased.The TTWs progressively engulfed parent grains with increasing shear strain,evolving into an unusual deformation twin morphology.Furthermore,VPSC model predictions confirmed basal slip as the dominant deformation mode at low IPS strains,transitioning to prismatic slip dominance at higher IPS strains.The activity of the TTW mode was significantly higher during the initial stages of IPS strain and saturated to lower values at higher strains.VPSC simulation results also indicated preferential shear accumulation on a single twin system,explaining the phenomenon of a single twin variant engulfing a parent grain.Additionally,the influence of individual slip and twin modes on texture evolution was evaluated through orientation tracking of representative grains at various shear strain increments using VPSC simulation.The simulation results quantitatively highlighted the activities of basal slip,prismatic slip,and tensile twinning,establishing a correlation between texture evolution and the underlying deformation mechanisms.展开更多
AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the...AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the interface was investigated.Moreover,the interface bonding mechanisms of the AZ31/Al/Ta composites during the VHCB process were explored.The results demonstrate that as the VHCB temperature increases,the phase composition of the interface between Mg and Al changes from the Mg-Al brittle intermetallic compounds(Al_(12)Mg_(17)and Al_(3)Mg_(2))to the Al-Mg solid solution.Meanwhile,the width of the Al/Ta interface diffusion layer at 450℃increases compared to that at 400℃.The shear strengths are 24 and 46 MPa at 400 and 450℃,respectively.The interfacial bonding mechanism of AZ31/Al/Ta composites involves the coexistence of diffusion and mechanical meshing.Avoiding the formation of brittle phases at the interface can significantly improve interfacial bonding strength.展开更多
Data compression plays a vital role in datamanagement and information theory by reducing redundancy.However,it lacks built-in security features such as secret keys or password-based access control,leaving sensitive da...Data compression plays a vital role in datamanagement and information theory by reducing redundancy.However,it lacks built-in security features such as secret keys or password-based access control,leaving sensitive data vulnerable to unauthorized access and misuse.With the exponential growth of digital data,robust security measures are essential.Data encryption,a widely used approach,ensures data confidentiality by making it unreadable and unalterable through secret key control.Despite their individual benefits,both require significant computational resources.Additionally,performing them separately for the same data increases complexity and processing time.Recognizing the need for integrated approaches that balance compression ratios and security levels,this research proposes an integrated data compression and encryption algorithm,named IDCE,for enhanced security and efficiency.Thealgorithmoperates on 128-bit block sizes and a 256-bit secret key length.It combines Huffman coding for compression and a Tent map for encryption.Additionally,an iterative Arnold cat map further enhances cryptographic confusion properties.Experimental analysis validates the effectiveness of the proposed algorithm,showcasing competitive performance in terms of compression ratio,security,and overall efficiency when compared to prior algorithms in the field.展开更多
Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-p...Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-power spintronic devices.Intriguingly,the rare earth tritelluride(RTe3)materials have attracted great attention due to their unique magnetic structure,exotic electronic properties,multiple charge density wave(CDW),and superconductivity under pressure.Here,we report the successful synthesis of high-quality DyTe_(3)single crystals using a self-flux method.DyTe_(3)shows an antiferromagnetic transition at 4.5 K and demonstrates the magnetic field-induced ferromagnetism.The high-quality DyTe_(3)single crystal demonstrates outstanding transport properties,featuring a high carrier mobility of approximately1.4×10^(4)cm^(2)·V^(-1)·s^(-1)and large linear magnetoresistance of 1300%.Furthermore,distinct Shubnikov-de Haas(SdH)oscillations are observed in DyTe_(3),revealing a small Fermi pocket and an effective mass of 0.24 me.Remarkably,the unconventional in-plane negative magnetoresistances appear along the a-axis below 2 T and c-axis until 9 T from 2 K to17 K,which are attributed to the complex helimagnetic structures caused by CDW coupling and weak single-ion anisotropy.Our findings offer a significant platform for understanding the complex magnetoresistance behavior and quantum transport effects in RTe3-type materials,holding great promise for advancing applications in electronic and spintronic devices.展开更多
Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(elec...Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(electron/hole),balancing the catalytic efficiency between hydrogen and oxygen evolution remains challenging for achieving bifunctional electrocatalysts.Here,we report a locally-doped MoS_(2)monolayer with an in-plane heterostructure acting as a bifunctional electrocatalyst and apply it to the overall water splitting.In this heterostructure,the core region contains Mo/S vacancies,while the ring region was doped by Fe atoms(in two substitution configurations:1FeMo and 3FeMo-VS clusters)with a p-type conductive characteristic.Our micro-cell measurements,combined with density functional theory(DFT)calculations,reveal that the vacancies-rich core region presents remarkable hydrogen evolution reaction(HER)activity while the Fe-doped ring gives an excellent oxygen evolution reaction(OER)activity,thus forming an in-plane bifunctional electrocatalyst.Finally,as a proof-of-concept for overall water splitting,we constructed a full-cell configuration based on a locally-doped MoS_(2)monolayer,which achieved a cell voltage of 1.87 V at 10 mA·cm^(-2),demonstrating outstanding performance in strong acid electrolytes.Our work provides insight into the hetero-integration of bifunctional electrocatalysts at the atomic level,paving the way for designing transition metal dichalcogenide catalysts with activity-manipulated regions capable of multiple reactions.展开更多
The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperat...The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.展开更多
With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored ha...With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored has increased dramatically. The use of compression techniques for these bitstream files is emerging as a key strategy to alleviate the burden on storage resources. Due to the severe resource constraints of space-based electronics and the unique application environment, the simplicity, efficiency and robustness of the decompression circuitry is also a key design consideration. Through comparative analysis current bitstream file compression technologies, this research suggests that the Lempel Ziv Oberhumer (LZO) compression algorithm is more suitable for satellite applications. This paper also delves into the compression process and format of the LZO compression algorithm, as well as the inherent characteristics of configuration bitstream files. We propose an improved algorithm based on LZO for bitstream file compression, which optimises the compression process by refining the format and reducing the offset. Furthermore, a low-cost, robust decompression hardware architecture is proposed based on this method. Experimental results show that the compression speed of the improved LZO algorithm is increased by 3%, the decompression hardware cost is reduced by approximately 60%, and the compression ratio is slightly reduced by 0.47%.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 11432004
文摘The effect of the face thickness to core height ratio on different multi-layer pyramidal core sandwich columns under in-plane compression is investigated theoretically and numerically. Numerical simulation is in good agreement with theory. Results indicate that one specified face thickness to core height ratio corresponds to one optimum layer number of multi-layer pyramidal core sandwich columns in consideration of engineering application. This result can guide the sandwich structure design.
基金Funded by the National Natural Science Foundation of China(No.11305138)the Jiangsu Science and Technology Department Support Program(No.BY2019188)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(No.14KJD540004).
文摘The in-plane compressive characteristics of the ultra-high molecular weight polyethylene(UHMWPE)fibre(Dyneema█)reinforced composites,both in 0/90°and±45°fibre orientations with respect to the loading direction,have been investigated.The composite made from unidirectional high modulus fibres(volume fraction 83%)and low strength polyurethane matrix(volume fraction 17%)is layered in an orthogonally alternating manner.The different failure mechanisms for the composites with 0/90°and±45°fibre orientations have been detected with the methods of experimental measurement,SEM observation and theoretical analysis.The composites specimens of 0/90°fibre orientation failed with macro-buckling of the high-modulus UHMWEP fibre layers with the matrix damage,whereas the specimens of±45°fibre orientation failed with the shearing of the soft matrix.Hence,the composite specimens in 0/90°fibre orientation had higher stiffness as well as compressive strength than those in±45°fibre orientation.The failure criteria of the composites under in-plane compression was employed to characterize the failure mechanism.Compared with the traditional thermoset matrix,the soft thermoplastic matrix leads to lower strength and higher failure strain of fibre reinforced composites under in-plane compression.In addition,the composite specimens cut by waterjet machine exhibited higher stress levels than those cut by bandsaw that introduced more initial imperfections with the temperature rising and tensile shocking.The comparison between the methodologies for cutting the tough composites can provide a valuable suggestion to obtain required composite structures without reducing the mechanical properties.
基金supported by the National Natural Science Foundation of China(Grant No.42277147)Ningbo Public Welfare Research Program(Grant No.2024S081)Ningbo Natural Science Foundation(Grant No.2024J186).
文摘Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.
基金supported by the National Natural Science Foundation of China(U2341288 and 12302492)。
文摘An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.
基金support from the National Natural Science Foundation of China(Grant No.U24A20105 and 52071209)the Major Scientific and Technological Innovation Project of CITIC Group(Grant No.2022ZXKYA06100,with Hongzhou Lu as the principal grant recipient)the Program of Shanghai Academic and Technology Research Leader(Grant No.18XD1402200).
文摘Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that the hydrogen increases the dislocation density,reduces the yield stress,and accelerates the formation and intersection of slip bands,with hydrogen-induced cracks initiating at slip band intersections.X-ray diffraction confirms the absence of martensitic transformation,ruling out the role of martensitic transformation in HE.The micropillar compression technique is highly sensitive for characterizing hydrogen-material interactions,owing to the material’s low hydrogen diffusivity and the small size of its hydrogen-affected zone.These findings align with the hydrogen-enhanced localized plasticity mechanism.
基金supported by the National Natural Science Foundation of China(Grant No.52339001).
文摘To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.
基金support from the National Natural Science Foundation of China(Grant Nos.52104207 and 52374214)the Shandong Provincial Youth Innovation Team Development Program for Higher Education Institutions(Grant No.2023KJ305).
文摘In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties and acoustic emission(AE)behavior of rocks,this study conducted uniaxial compression experiments on sandstones with varying degrees of wetting under both natural conditions and water-chemical environments.In addition,the study combined AE equipment with digital image correlation(DIC)to monitor the entire failure process.Using the sliding window algorithm,the variation in the variance of AE characteristic parameters during the process of sandstone loading to failure is analyzed from the perspective of critical slowing down.This analysis enables the effective identification of the early warning signal before failure.The experimental findings suggest that an increase in wetting height results in a gradual decrease in peak stress,accompanied by a concomitant increase in the percentage of shear cracks.The characteristic parameters,including energy,amplitude,and ringing count,all exhibit critical slowing phenomena.The waveform of AE characteristic parameters of the same sample is similar,and the mutation time of the precursor signal is roughly the same.All signals appear in the irreversible plastic deformation stage of microcrack initiation.The integration of critical slowing down theory and the b-value early warning method facilitates a more comprehensive evaluation of the stability of rock mass,thereby significantly enhancing the efficiency and safety of disaster prevention measures.
基金partially supported by the Center for Advanced Systems Understanding(CASUS)financed by Germany’s Federal Ministry of Education and Research(BMBF)+2 种基金the Saxon State Government out of the State Budget approved by the Saxon State Parliamentfunding from the European Union’s Just Transition Fund(JTF)within the project Röntgenlaser-Optimierung der Laserfusion(ROLF),Contract No.5086999001co-financed by the Saxon State Government out of the State Budget approved by the Saxon State Parliament.
文摘We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based imaging with sub-micrometer spatial and femtosecond temporal resolution,supported by hydrodynamic and particle-in-cell simulations,we reveal how return current density depends precisely on wire diameter,material properties,and incident laser energy.We identify deviations from simple theoretical predictions due to geometrically influenced electron escape dynamics.These results refine and confirm the scaling laws essential for predictive modeling in high-energy-density physics and inertial fusion research.
文摘In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC was used to drive the adiabatic compressed air energy storage(ACAES),while the intake air of the GTCC was heated by the compression heat of theACAES.Based on a 67.3MW GTCC,under specific demand load distribution,a CPG system and a benchmark system(BS)were designed,both of which used 9.388% of the GTCC output power to drive the ACAES.The performance of the CPG and the BS without intake air heating was compared.The results show that the load rate of the GTCC in the CPG system during off-peak periods is significantly enhanced,and the average operating efficiency of the GTCC is increased by 1.19 percentage points.However,in the BS system,due to the single collaborativemethod of load shifting,the GTCC operative efficiency is almost increased by 1.00 percentage points under different ambient temperatures.In a roundtrip cycle at an ambient temperature of 288.15K,the systemefficiency of the CPG reaches 0.5010,which is 0.62 percentage points higher than the operative efficiency of 0.4948 in the standalone GTCC;while the system efficiency of the BS is slightly inferior to that of the standalone GTCC.The findings confirm the technical feasibility and performance improvement of the ACAES-GTCC collaborative power generation system.
基金supported by the National Natural Science Foundation of China(Grant Nos.42372312,and 42172299)the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(Grant No.JDYC20220807).
文摘The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics of frozen sodium sulfate saline sandy soil,a series of uniaxial compression tests were performed by integrating digital image correlation(DIC)technology into the testing apparatus.The evolution law of the uniaxial compression strength(UCS),the failure strain,and the formation of the shear band of the frozen sodium sulfate saline sandy soil were analyzed.The test results show that within the scope of this study,with the increase of salt content,both the UCS and the shear band angle initially decrease with increasing salt content before showing an increase.In contrast,the failure strain and the width of the shear band exhibit an initial increase followed by a decrease in the samples.In addition,to investigate the brittle failure characteristics of frozen sodium sulfate saline sandy soil,two classic brittleness evaluation methods were employed to quantitatively assess the brittleness level for the soil samples.The findings suggest that the failure characteristics under all test conditions in this study belong to the transition stage between brittle and ductile,indicating that frozen sodium sulfate saline sandy soil exhibits certain brittle behavior under uniaxial compression conditions,and the brittleness index basically decreases and then increases with the rise in salt content.
基金National Natural Science Foundation of China(52305349)Heilongjiang Touyan Team(HITTY-20190036)+2 种基金Heilongjiang Provincial Natural Science Foundation of China(LH2023E033)CGN-HIT Advanced Nuclear and New Energy Research Institute(CGN-HIT202305)Natural Science Basic Research Program of Shaanxi Province(2023-JC-QN-0518)。
文摘The effect of deformation resistance of AlCr_(1.3)TiNi_(2) eutectic high-entropy alloys under various current densities and strain rates was investigated during electrically-assisted compression.Results show that at current density of 60 A/mm^(2) and strain rate of 0.1 s^(−1),the ultimate tensile stress shows a significant decrease from approximately 3000 MPa to 1900 MPa with reduction ratio of about 36.7%.However,as current density increases,elongation decreases due to intermediate temperature embrittlement.This is because the current induces Joule effect,which then leads to stress concentration and more defect formation.Moreover,the flow stress is decreased with the increase in strain rate at constant current density.
基金financially supported by the National Natural Science Foundation of China(Nos.52174092,51904290,and 52374147)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the National Key Research and Development Program of China(No.2023YFC3804204)the Major Program of Xinjiang Uygur Autonomous Region S cience and Technology(No.2023A01002)。
文摘The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of aggregates.The mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically analyzed.The results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,respectively.However,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the aggregates.Theσ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite trend.Theε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse aggregates.With increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.
基金sponsored by the National Natural Science Foundation of China(Grant No.12002173,12262027)Research start-up project of Inner Mongolia University of Technology(No.2200000924)key Lab.of University of Geological Hazards and Geotechnical Engineering Defense in Sandy and Drought Regions,Inner Mongolia Autonomous.
文摘Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength,better durability and environmental friendli-ness,as well as a good engineering application prospect.In this paper,the shear strength of sand column was tested by triaxial compression tests,and the strength index was obtained.In order to further study the micro-strength mechanism and the failure process,based on the discrete element method,a numerical model of MICP cemented sand column was established considering the factors of matrix soil particle gradation,particle mor-phology,content ratio of induced calcium carbonate,pore distribution characteristics,inter-particle cementation and so on.The failure process of MICP cemented sand column under load was analysed by numerical simulation,and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions.The results indicate that compared with the actual triaxial tests of MICP cemented sand column,although there are deviations in stress and strain,cohesion and internal friction angle,the numerical simulation shows similar development law and intensity amplitude,and the same failure trend.The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.
文摘The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The specimens were deformed under varying degrees of IPS strain(γ12=0.05,0.10,and 0.15)using a customized jig.Electron backscatter diffraction(EBSD)observations revealed profuse tensile twinning(TTW)even at an IPS strain of 0.05,with its intensity continuously increased as the IPS strain increased.The TTWs progressively engulfed parent grains with increasing shear strain,evolving into an unusual deformation twin morphology.Furthermore,VPSC model predictions confirmed basal slip as the dominant deformation mode at low IPS strains,transitioning to prismatic slip dominance at higher IPS strains.The activity of the TTW mode was significantly higher during the initial stages of IPS strain and saturated to lower values at higher strains.VPSC simulation results also indicated preferential shear accumulation on a single twin system,explaining the phenomenon of a single twin variant engulfing a parent grain.Additionally,the influence of individual slip and twin modes on texture evolution was evaluated through orientation tracking of representative grains at various shear strain increments using VPSC simulation.The simulation results quantitatively highlighted the activities of basal slip,prismatic slip,and tensile twinning,establishing a correlation between texture evolution and the underlying deformation mechanisms.
基金National Natural Science Foundation of China(52275308,52301146)Fundamental Research Funds for the Central Universities(2023JG007)Supported by Shi Changxu Innovation Center for Advanced Materials(SCXKFJJ202207)。
文摘AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the interface was investigated.Moreover,the interface bonding mechanisms of the AZ31/Al/Ta composites during the VHCB process were explored.The results demonstrate that as the VHCB temperature increases,the phase composition of the interface between Mg and Al changes from the Mg-Al brittle intermetallic compounds(Al_(12)Mg_(17)and Al_(3)Mg_(2))to the Al-Mg solid solution.Meanwhile,the width of the Al/Ta interface diffusion layer at 450℃increases compared to that at 400℃.The shear strengths are 24 and 46 MPa at 400 and 450℃,respectively.The interfacial bonding mechanism of AZ31/Al/Ta composites involves the coexistence of diffusion and mechanical meshing.Avoiding the formation of brittle phases at the interface can significantly improve interfacial bonding strength.
基金the Deanship of Graduate Studies and Scientific Research at Qassim University for financial support(QU-APC-2025).
文摘Data compression plays a vital role in datamanagement and information theory by reducing redundancy.However,it lacks built-in security features such as secret keys or password-based access control,leaving sensitive data vulnerable to unauthorized access and misuse.With the exponential growth of digital data,robust security measures are essential.Data encryption,a widely used approach,ensures data confidentiality by making it unreadable and unalterable through secret key control.Despite their individual benefits,both require significant computational resources.Additionally,performing them separately for the same data increases complexity and processing time.Recognizing the need for integrated approaches that balance compression ratios and security levels,this research proposes an integrated data compression and encryption algorithm,named IDCE,for enhanced security and efficiency.Thealgorithmoperates on 128-bit block sizes and a 256-bit secret key length.It combines Huffman coding for compression and a Tent map for encryption.Additionally,an iterative Arnold cat map further enhances cryptographic confusion properties.Experimental analysis validates the effectiveness of the proposed algorithm,showcasing competitive performance in terms of compression ratio,security,and overall efficiency when compared to prior algorithms in the field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62488201 and 1240041502)the Ministry of Science and Technology of China(Grant No.2022YFA1204100)+1 种基金the Chinese Academy of Sciences(Grant No.XDB33030100)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-power spintronic devices.Intriguingly,the rare earth tritelluride(RTe3)materials have attracted great attention due to their unique magnetic structure,exotic electronic properties,multiple charge density wave(CDW),and superconductivity under pressure.Here,we report the successful synthesis of high-quality DyTe_(3)single crystals using a self-flux method.DyTe_(3)shows an antiferromagnetic transition at 4.5 K and demonstrates the magnetic field-induced ferromagnetism.The high-quality DyTe_(3)single crystal demonstrates outstanding transport properties,featuring a high carrier mobility of approximately1.4×10^(4)cm^(2)·V^(-1)·s^(-1)and large linear magnetoresistance of 1300%.Furthermore,distinct Shubnikov-de Haas(SdH)oscillations are observed in DyTe_(3),revealing a small Fermi pocket and an effective mass of 0.24 me.Remarkably,the unconventional in-plane negative magnetoresistances appear along the a-axis below 2 T and c-axis until 9 T from 2 K to17 K,which are attributed to the complex helimagnetic structures caused by CDW coupling and weak single-ion anisotropy.Our findings offer a significant platform for understanding the complex magnetoresistance behavior and quantum transport effects in RTe3-type materials,holding great promise for advancing applications in electronic and spintronic devices.
基金supported by the National Natural Science Foundation of China(Nos.22175060 and 22376062)JSPS Grant-in-Aid for Scientific Research(Nos.JP21H05235,JP22H05478 and JP22F22358)+1 种基金China Postdoctoral Science Foundation(No.2022M722867)the Key Research Project of Higher Education Institutions in Henan Province(No.23A530001).
文摘Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(electron/hole),balancing the catalytic efficiency between hydrogen and oxygen evolution remains challenging for achieving bifunctional electrocatalysts.Here,we report a locally-doped MoS_(2)monolayer with an in-plane heterostructure acting as a bifunctional electrocatalyst and apply it to the overall water splitting.In this heterostructure,the core region contains Mo/S vacancies,while the ring region was doped by Fe atoms(in two substitution configurations:1FeMo and 3FeMo-VS clusters)with a p-type conductive characteristic.Our micro-cell measurements,combined with density functional theory(DFT)calculations,reveal that the vacancies-rich core region presents remarkable hydrogen evolution reaction(HER)activity while the Fe-doped ring gives an excellent oxygen evolution reaction(OER)activity,thus forming an in-plane bifunctional electrocatalyst.Finally,as a proof-of-concept for overall water splitting,we constructed a full-cell configuration based on a locally-doped MoS_(2)monolayer,which achieved a cell voltage of 1.87 V at 10 mA·cm^(-2),demonstrating outstanding performance in strong acid electrolytes.Our work provides insight into the hetero-integration of bifunctional electrocatalysts at the atomic level,paving the way for designing transition metal dichalcogenide catalysts with activity-manipulated regions capable of multiple reactions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62074036, 61674038, and 11574302)Foreign Cooperation Project of Fujian Province (Grant No. 2023I0005)+2 种基金Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (Grant No. KF202108)the National Key Research and Development Program (Grant No. 2016YFB0402303)the Foundation of Fujian Provincial Department of Industry and Information Technology of China (Grant No. 82318075)。
文摘The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.
基金supported in part by the National Key Laboratory of Science and Technology on Space Microwave(Grant Nos.HTKJ2022KL504009 and HTKJ2022KL5040010).
文摘With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored has increased dramatically. The use of compression techniques for these bitstream files is emerging as a key strategy to alleviate the burden on storage resources. Due to the severe resource constraints of space-based electronics and the unique application environment, the simplicity, efficiency and robustness of the decompression circuitry is also a key design consideration. Through comparative analysis current bitstream file compression technologies, this research suggests that the Lempel Ziv Oberhumer (LZO) compression algorithm is more suitable for satellite applications. This paper also delves into the compression process and format of the LZO compression algorithm, as well as the inherent characteristics of configuration bitstream files. We propose an improved algorithm based on LZO for bitstream file compression, which optimises the compression process by refining the format and reducing the offset. Furthermore, a low-cost, robust decompression hardware architecture is proposed based on this method. Experimental results show that the compression speed of the improved LZO algorithm is increased by 3%, the decompression hardware cost is reduced by approximately 60%, and the compression ratio is slightly reduced by 0.47%.
