The Ki67 index (KI) is a standard clinical marker for tumor proliferation;however, its application is hindered by intratumoral heterogeneity. In this study, we used digital image analysis to comprehensively analyze Ki...The Ki67 index (KI) is a standard clinical marker for tumor proliferation;however, its application is hindered by intratumoral heterogeneity. In this study, we used digital image analysis to comprehensively analyze Ki67 heterogeneity and distribution patterns in breast carcinoma. Using Smart Pathology software, we digitized and analyzed 42 excised breast carcinoma Ki67 slides. Boxplots, histograms, and heat maps were generated to illustrate the KI distribution. We found that 30% of cases (13/42) exhibited discrepancies between global and hotspot KI when using a 14% KI threshold for classification. Patients with higher global or hotspot KI values displayed greater heterogenicity. Ki67 distribution patterns were categorized as randomly distributed (52%, 22/42), peripheral (43%, 18/42), and centered (5%, 2/42). Our sampling simulator indicated analyzing more than 10 high-power fields was typically required to accurately estimate global KI, with sampling size being correlated with heterogeneity. In conclusion, using digital image analysis in whole-slide images allows for comprehensive Ki67 profile assessment, shedding light on heterogeneity and distribution patterns. This spatial information can facilitate KI surveys of breast cancer and other malignancies.展开更多
Digital rock analysis(DRA)is fundamental for geo-energy research,enabling the characterisation of microstructures for applications like hydrocarbon recovery,carbon storage,and groundwater modelling.Although 2D CT imag...Digital rock analysis(DRA)is fundamental for geo-energy research,enabling the characterisation of microstructures for applications like hydrocarbon recovery,carbon storage,and groundwater modelling.Although 2D CT images provide valuable pore-scale data,the scarcity of real-world datasets limits the effectiveness of advanced analysis.Generative AI presents a promising approach for synthesizing high-quality rock images but faces key challenges,including high computational demands,insufficient evaluation metrics,and the trade-off between image fidelity and diversity.To address these limitations,this study proposes the use of Low-Rank Adaptation(LoRA)for fine-tuning stable diffusion models,significantly reducing computational requirements while maintaining image quality.A systematic investigation was conducted to evaluate the influence of LoRA training parameters,including rank and learning rate,on the quality of generated images.Image outputs were assessed using both standard generative metrics,such as Kernel Inception Distance(KID),and domain-specific metrics,including porosity,pore count,and pore area distributions.The optimised LoRA-enhanced diffusion model achieved a 92.6% reduction in KID relative to baseline models,while also improving inference speed.Building on these advancements,this study demonstrates that the LoRA-enhanced diffusion model significantly improves neural network extrapolation in incomplete data scenarios through statistically consistent synthetic generation.Despite control challenges,this approach reduces costs and enables diverse applications,bridging fundamental rock physics with practical energy research.展开更多
Digital terrain analysis(DTA)is one of the most important contents in the research of geographical information science(GIS).However,on the basis of the digital elevation model(DEM),many problems exist in the current r...Digital terrain analysis(DTA)is one of the most important contents in the research of geographical information science(GIS).However,on the basis of the digital elevation model(DEM),many problems exist in the current research of DTA in geomorphological studies.For instance,the current DTA research appears to be focused more on morphology,phenomenon,and modern surface rather than mechanism,process,and underlying terrain.The current DTA research needs to be urgently transformed from the study of landform morphology to one focusing on landform process and mechanism.On this basis,this study summarizes the current research status of geomorphology-oriented DTA and systematically reviews and analyzes the research about the knowledge of geomorphological ontology,terrain modeling,terrain derivative calculation,and terrain analytical methods.With the help of DEM data,DTA research has the advantage of carrying out geomorphological studies from the perspective of surface morphology.However,the study of DTA has inherent defects in terms of data expression and analytic patterns.Thus,breakthroughs in basic theories and key technologies are necessary.Moreover,scholars need to realize that DTA research must be transformed from phenomenon to mechanism,from morphology to process,and from terrain to landform.At present,the research development of earth science has reached the critical stage in which the DTA research should focus more on geomorphological ontology.Consequently,this study proposes several prospects of geomorphology-oriented DTA from the aspects of value-added DEM data model,terrain derivatives and their spatial relations,and macro-terrain analysis.The study of DTA based on DEM is at a critical period along with the issue on whether the current GIS technology can truly support the development of geography.The research idea of geomorphology-oriented DTA is expected to be an important exploration and practice in the field of GIS.展开更多
BACKGROUND: The accurate assessment of the degree of hepatic fibrosis plays a critical role in guiding the diagnosis, treatment and prognostic assessment of chronic liver diseases. Liver biopsy is currently the most r...BACKGROUND: The accurate assessment of the degree of hepatic fibrosis plays a critical role in guiding the diagnosis, treatment and prognostic assessment of chronic liver diseases. Liver biopsy is currently the most reliable method to evaluate the severity of hepatic fibrosis. However, liver biopsy is an invasive procedure associated with morbidity and mortality, and has several limitations in patients with decompensated cirrhosis. There is no report on the collagen proportionate area (CPA) of liver tissue in the decompensated stage of cirrhosis. This study aimed to determine the CPA of resected liver tissue samples from patients with HBV-related decompensated cirrhosis using digital image analysis, and to analyze the relationship between the CPA and liver functional reserve. METHODS: Fifty-three resected liver tissue samples from liver transplant patients with chronic hepatitis B-induced decompensated cirrhosis were stained with Masson’s trichrome, and the CPA in these samples was quantitatively determined using digital image analysis. The values of relevant liver function just before liver transplantation, the CPA in liver tissue, and their correlation were analyzed. RESULTS: The mean CPA at the decompensated stage of cirrhosis was 35.93±14.42% (11.24%-63.41%). The correlation coefficients of the CPA with a model for end-stage liver disease score, serum total bilirubin and international standard ratio of prothrombin B were 0.553, 0.519 and 0.533, respectively (P<0.001). With increasing CPA values, the three indices reflecting liver functional reserve also changed significantly.CONCLUSIONS: The degree of fibrosis may be correlated with the functional reserve. With the advancement of fibrosis, the liver functional reserve is attenuated accordingly.展开更多
The digital image processing technique was used for the extraction of physical information from the temporal image of phase structure in the process of phase separation in the blend of poly (butylene terephthalate-co-...The digital image processing technique was used for the extraction of physical information from the temporal image of phase structure in the process of phase separation in the blend of poly (butylene terephthalate-co-caprolactone )with polycarbonate. The power spectrum images of the two-dimensional Fourier transformation (2DFT) of the temporal image of phase structure reflect the change of the phase size with time.展开更多
The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration.The various means used to achieve this objective make use of either continuous or d...The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration.The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data.To map anomalies in a discrete field model of such data,two corrections are required:background correction and downstream dilution correction.Topography and geomorphology are important factors in variations of element content in stream sediments.However,few studies have considered,through the use of digital terrain analysis,the influence of geomorphic features in downstream dilution correction of stream sediment geochemical data.This study proposes and demonstrates an improvement to the traditional downstream dilution correction equation,based on the use of digital terrain analysis to map single-element anomalies in stream sediment geochemical landscapes.Moreover,this study compares the results of analyses using discrete and continuous field models of stream sediment geochemical data from the Xincang area,Xizang.The efficiency of the proposed methodology was validated against known mineral occurrences.The results indicate that catchment-based analysis outperforms interpolation-based analysis of stream sediment geochemical data for anomaly mapping.Meanwhile,the proposed modified downstream dilution correction equation proved more effective than the original equation.However,further testing of this modified downstream dilution correction is needed in other areas,in order to investigate its efficiency further.展开更多
A digital pulse analysis system is an important diagnostic system in nuclear physics experimental research.In response to the demand for reflecting the particle state in a nuclear physics experiment,we have designed a...A digital pulse analysis system is an important diagnostic system in nuclear physics experimental research.In response to the demand for reflecting the particle state in a nuclear physics experiment,we have designed and developed a real-time digital pulse analysis system and applied it to the digital nuclear pulse waveform discrimination of different detectors in the HL-2M tokamak.The system is based on the peripheral component interconnect extensions for instrumentation(PXI)platform,while its software was written in LABVIEW.The key technologies involved in the system implementation include digital pulse analysis technology,digital discrimination technology,pulse height analysis technology,etc.The system has been applied to the plastic scintillator detector at the Neutron Source Lab of the University of Science and Technology of China.And the experimental results indicate that the system can discriminate between neutron(n)particles and gamma(γ)particles well when used to measure the plastic scintillator detector.展开更多
The use of Digital Shoreline Analysis System was used to determine shoreline changes in Ikoli River,Yenagoa,Bayelsa State.Shoreline data were extracted from satellite imagery over thirty years(1991-2021).The basis of ...The use of Digital Shoreline Analysis System was used to determine shoreline changes in Ikoli River,Yenagoa,Bayelsa State.Shoreline data were extracted from satellite imagery over thirty years(1991-2021).The basis of this study is to use Digital Shoreline Analysis System to determine erosion and accretion areas.The result reveals that the average erosion rate in the study area is 1.16 m/year and the accretion rate is 1.62 m/year along the Ikoli River in Ogbogoro Community in Yenagoa,Bayelsa State.The mean shoreline length is 5.24 km with a baseline length of 5.2 km and the area is classified into four zones to delineate properly area of erosion and accretion based on the five class of Linear regression rate,endpoint rate and weighted linear rate of which zone Ⅰ contain very high erosion and high erosion with an area of landmass 255449.93 m^(2) of 38%,zone Ⅱ contain moderate accretion,very high accretion and high accretion with a land area of 1666816.46 m^(2) with 24%,zone Ⅲ has very high erosion and high erosion with an area of landmass 241610.85 m^(2) of 34% and zone Ⅳ contain moderate accretion and high accretion with land area 30888.08 m^(2) with 4%.Out of the four zones,zone Ⅰ and Ⅱ were found to be eroding with 72% and zone Ⅱ and Ⅳ contain accretion with 28%.The result shows that 44% of the area have been eroded.Therefore,coastal engineers,planners,and shoreline zone management authorities can use DSAS to create more appropriate management plans and regulations for coastal zones and other coastal parts of the state with similar geographic features.展开更多
Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from v...Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from various perspectives.Peak intervisibility can provide the potential topographic information implied in the visual connectivity of peaks,however,its application in loess landform analysis remains unexplored.In this study,the interwoven sightlines among peaks,representing peak intervisibility,were extracted from the digital elevation model and simulated into a peak intervisibility network(PIN).Nine indices were proposed to quantify the PIN.Through a case study in Northern Shaanxi,China,three tasks were conducted,including,landform interpretation,spatial pattern mining,and landform classification.The main findings are as follows:(1)PIN responds to terrain morphology and is beneficial for loess landform interpretation.(2)The spatial patterns of PIN indices are heterogeneous and strongly coupled with the terrain morphologies,showing anisotropy and autocorrelation in spatial variations.(3)Using the light gradient boost machine classifier,the PIN index-based classification reaches a mean accuracy of 86.09%,an overall accuracy of 86%and a kappa coefficient of 0.84.These findings shed light on the applicability of PIN in loess landform analysis.Peak intervisibility not only enriches the theories and methodologies of relation-based digital terrain analysis,but also enhances our comprehension of loess landform genesis,morphology,distribution,and evolution.展开更多
The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geog...The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geographical pattern.Understanding the topographic and geomorphological characteristics of the Hengduan Mountains is fundamental and crucial for research in related fields such as ecology,geography,and sustainability.In this study,Digital Elevation Model(DEM)data were utilized to extract and analyze the topography and geomorphology(TG)pattern.TG maps have been developed to quantitatively classify the TG types in the Hengduan Mountains by combining the five factors of elevation,slope,aspect,relief and landform.The spatial distribution and quantitative characteristics of these factors were mapped and investigated using geographic information systems.The results revealed that:(1)The Hengduan Mountains exhibit an elongated north-south distribution,with an average elevation of approximately 3746 m,an average slope of around 25°,and an average relief of about 266 m.(2)The Hengduan Mountains display significant elevation differences,with an overall high elevation,characterized by a trend of lower elevation in the east and higher elevation in the west,as well as irregular orientations of various aspects.(3)The 19 landform types were identified,the landform types of the Hengduan Mountains are primarily composed of low-relief high-mountains(42.0618%),low-relief mid-mountains(22.4624%),and high-elevation hills(20.5839%).The results of the study can provide data and information support for the ecology,environmental protection and sustainable development of the Hengduan Mountains.展开更多
The geomorphic evolution of the Xindiangou small watershed on the Loess Plateau in China is influenced by many factors,resulting in very complex evolutionary characteristics of erosion,morphology,and development.Since...The geomorphic evolution of the Xindiangou small watershed on the Loess Plateau in China is influenced by many factors,resulting in very complex evolutionary characteristics of erosion,morphology,and development.Since 1952,a number of soil and water conservation projects have been implemented in the watershed,especially the largescale project of returning farmland to forest and grass since 1999,which has significant impact on the erosion characteristics of the loess.This paper takes a unique perspective of the watershed geomorphic system and its watershed geomorphic entropy(WGE)and clarifies the geomorphic erosion characteristics of the Xindiangou small watershed.The results show that in the past 45 years,the entropy change of WGE of this watershed has generally shown the characteristics of entropy decrease and local entropy increase.The watershed is dominated by erosion in general,but due to the large-scale implementation of various soil and water conservation projects,especially the Project of Returning Farmland to Forests and Grasslands(RFFG),the landform erosion intensity has been greatly reduced and local increase in the entropy change of WGE has appeared.These projects have achieved good ecological effects after 11 years of implementation.展开更多
Dao Xuan’s Gantonglu records:“About fifteen kilometers down from the southeast of the Wutai Mountain,there is the ancient Dafu Lingjiu Temple,and there are two Taoist temples in the east and west,where Buddhist matt...Dao Xuan’s Gantonglu records:“About fifteen kilometers down from the southeast of the Wutai Mountain,there is the ancient Dafu Lingjiu Temple,and there are two Taoist temples in the east and west,where Buddhist matters are fulfilled.According to ancient legend,it was made by Emperor Ming of the Han Dynasty”(Daoxuan,Tang Dynasty,p.257).It can be seen that Buddhism has been introduced into Wutai Mountain since the Eastern Han Dynasty,and Buddhist temple murals have been painted on the walls of temples with the introduction of Buddhism,playing the role of spreading scriptures and decorating the walls.The pattern of Buddha’s futon base in the murals reflects the worship and rank differences of Buddhist monks in different periods.As a medium of meditation and worship,futuan is also a ritual instrument in Buddhist legend,which is of great significance.The research on the style of futon from the perspective of the frescoes in the temple of Wutai Mountain mainly focuses on the historical evolution of the frescoes and futon,the research and analysis of the base shape,pattern,composition and color of the futon in the frescoes of the temple.Explore the religious significance and historical and cultural value behind the futon style.展开更多
Terrain texture analysis is an important method of digital terrain analysis in quantitative geomorphological research and in the exploration of the spatial heterogeneity and autocorrelation of terrain features. Howeve...Terrain texture analysis is an important method of digital terrain analysis in quantitative geomorphological research and in the exploration of the spatial heterogeneity and autocorrelation of terrain features. However, a major issue often neglected in previous studies is the calculation unit of the terrain texture, that is, the stability analysis unit. As the test size increases, the derived terrain textures become increasingly similar so that their differences can be ignored. The test size of terrain texture is defined as the stability analysis unit. This study randomly selected 48 areas within the Loess Plateau in northern Shaanxi in China as the study sites and used the gray level co-occurrence matrix to calculate the terrain texture. The stability analysis unit of the terrain texture was then extracted, and its spatial distribution pattern in the Loess Plateau was studiedusing spatial interpolation method. Four terrain texture metrics, i.e., homogeneity, energy, correlation, and contrast, were extracted on the basis of the stability analysis unit, and the spatial variation patterns of these parameters were studied. Results showed that the spatial distribution pattern and the terrain texture metrics reflected a trend of high–low–high from north to south, which correlated with the spatial distribution of the landforms at the Loess Plateau. In addition, the terrain texture measures was significantly correlated with the terrain factors of gully density and slope, and this relationship showed that terrain texture measures based on the stability analysis unit could reflect the basic characteristics of terrain morphology. The stability analysis unit provided a reasonable analytical scale for terrain texture analysis and could be used as a measure of the regional topography to accurately describe basic terrain characteristics.展开更多
A direct digital design method （DDDM） of worm-gear drive is proposed. It is directly based on the simulation of manufacturing process and completely different from the conventional modeling method. The loaded tooth ...A direct digital design method （DDDM） of worm-gear drive is proposed. It is directly based on the simulation of manufacturing process and completely different from the conventional modeling method. The loaded tooth contact analysis （LTCA） method is analyzed, in which the advanced surface to surface searching technique is included. The influence of misalignment errors and contact deformations on contact zone and transmission error （TE） is discussed. Combined modification approach on worm tooth surface is presented. By means of DDDM and LTCA, it is very conven- ient to verify the effect of worm-gear drive＇s modification approach. The analysis results show that, the modification in profile direction reduces the sensitivity of worm-gear drive to misalignment errors and the modification in longitudinal direction decreases the TE. Thus the optimization design of worm-gear drive can be achieved prior to the actual manufacturing process.展开更多
Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide（Ga As：Cr）,as a cathode and an Indiu...Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide（Ga As：Cr）,as a cathode and an Indium–Tin Oxide（ITO） coated glass electrode as an anode,in reverse bias.The planar nature of electrodes provides symmetry in spatial geometry.The discharge behaves oscillatory in the time domain,with single and sometimes multiperiodicities in plasma current and voltage characteristics.In this paper,harmonic frequency generation and transition to chaotic behavior is investigated.The observed current–voltage characteristics of the discharge are discussed in detail.展开更多
BACKGROUND The extraction of maxillary impacted teeth is a common procedure in oral surgery,frequently complicated by oroantral communications.For less-experienced clinicians,accurately assessing the difficulty and as...BACKGROUND The extraction of maxillary impacted teeth is a common procedure in oral surgery,frequently complicated by oroantral communications.For less-experienced clinicians,accurately assessing the difficulty and associated risks of maxillary third molar extractions remain a significant challenge.CASE SUMMARY We present a case involving disparate outcomes following bilateral extraction of maxillary third molars.Using cone-beam computed tomography and three-dimensional software,we conducted a digital assessment of the factors contributing to extraction difficulty and risk,controlling for potential confounders.Key variables analyzed included alveolar bone volume,bone quality,crown-root angulation,and maxillary sinus mucosal thickness.Additionally,we introduce the novel concept of"tegmen bone"to quantitatively evaluate the bone mass between the teeth and the maxillary sinus.This unique case,with differing outcomes on opposite sides of the same patient,provided an opportunity to minimize extraneous variables and focus on the local anatomical factors influencing the procedures,thereby improving the precision of our analysis.CONCLUSION This case highlights the potential utility of predictive analysis in guiding the management of complex tooth extractions.展开更多
Digital elevation model(DEM)plays a fundamental role in the study of the earth system by expressing surface configuration,understanding surface process,and revealing surface mechanism.DEM is widely used in analysis an...Digital elevation model(DEM)plays a fundamental role in the study of the earth system by expressing surface configuration,understanding surface process,and revealing surface mechanism.DEM is widely used in analysis and modeling in the field of geoscience.However,traditional DEM has the defect of single attribute,which is difficult to support the research in earth system science oriented to geoscience process and mechanism mining.Hence,realizing the value-added data model on the basis of traditional DEM is necessary to serve digital elevation modeling and terrain analysis under the background of a new geomorphology research paradigm and earth observation technology.A theoretical framework for value-added DEM that mainly includes concept,connotation,content,and categories,is constructed in this study.The relationship between different types of value-added DEMs as well as the research significance and application category of this theoretical framework are also proposed.The following are different methods of value-added DEMs:(1)value-added methods of DEM space and time dimensions that emphasize the integration of the ground and underground as well as coupling of time and space,(2)attribute-based value-added methods composed of material(including underground,surface,and ground)and morphological properties,and(3)value-added methods of features and physical elements that consider geographical objects and landform features formed by natural processes and artificial effects.The digital terrace,slope,and watershed models are used as examples to illustrate application scenarios of the three kinds of value-added methods.This study aims to improve expression methods of DEMs under the background of new surveying and mapping technologies by adding value to the DEM at three levels of dimensions,attributes,and elements as well as support knowledge-driven digital geomorphological analysis in the era of big data.展开更多
Brazilian pre-salt reservoirs are renowned for their intricate pore networks and vuggy nature,posing significant challenges in modeling and simulating fluid flow within these carbonate reservoirs.Despite possessing ex...Brazilian pre-salt reservoirs are renowned for their intricate pore networks and vuggy nature,posing significant challenges in modeling and simulating fluid flow within these carbonate reservoirs.Despite possessing excellent petrophysical properties,such as high porosity and permeability,these reservoirs typically exhibit a notably low recovery factor,sometimes falling below 10%.Previous research has indicated that various enhanced oil recovery(EOR)methods,such as water alternating gas(WAG),can substantially augment the recovery factor in pre-salt reservoirs,resulting in improvements of up to 20%.Nevertheless,the fluid flow mechanism within Brazilian carbonate reservoirs,characterized by complex pore geometry,remains unclear.Our study examines the behavior of fluid flow in a similar heterogeneous porous material,utilizing a plug sample obtained from a vugular segment of a Brazilian stromatolite outcrop,known to share analogies with certain pre-salt reservoirs.We conducted single-phase and multi-phase core flooding experiments,complemented by medical-CT scanning,to generate flow streamlines and evaluate the efficiency of water flooding.Subsequently,micro-CT scanning of the core sample was performed,and two cross-sections from horizontal and vertical plates were constructed.These cross-sections were then employed as geometries in a numerical simulator,enabling us to investigate the impact of pore geometry on fluid flow.Analysis of the pore-scale modeling and experimental data unveiled that the presence of dead-end pores and vugs results in a significant portion of the fluid remaining stagnant within these regions.Consequently,the injected fluid exhibits channeling-like behavior,leading to rapid breakthrough and low areal swept efficiency.Additionally,the numerical simulation results demonstrated that,irrespective of the size of the dead-end regions,the pressure variation within the dead-end vugs and pores is negligible.Despite the stromatolite's favorable petrophysical properties,including relatively high porosity and permeability,as well as the presence of interconnected large vugs,the recovery factor during water flooding remained low due to early breakthrough.These findings align with field data obtained from pre-salt reservoirs,providing an explanation for the observed low recovery factor during water flooding in such reservoirs.展开更多
The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the res...The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells,and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone-the method of directional unloading of the reservoir.The digital part of the research included computed tomography(CT)-based computer analysis of the internal structure,pore space characteristics,and filtration properties before and after the tests.According to the results of physical modeling of deformation and filtration processes,it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly,and this influence is reversible.However,when downhole pressure reaches 7-8 MPa,macrocracks in the rock begin to grow,accompanied by irreversible permeability increase.Porosity,geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling.A weak degree of transversal anisotropy of the filtration properties of rocks was detected.Based on the analysis of pore size distribution,pressure field and flow velocities,high homogeneity and connectivity of the rock pore space is shown.The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown.On the basis of geometrical analysis of pore space,the reasons for weak permeability anisotropy were identified.The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements.The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study.The necessary parameters of its application were calculated:bottomhole geometry,stage of operation,stresses and pressure drawdown value.展开更多
Bubble dynamics properties play a crucial and significant role in the design and optimization of gas-solid fluidized beds.In this study,the bubble dynamics properties of four B-particles were investigated in a quasi-t...Bubble dynamics properties play a crucial and significant role in the design and optimization of gas-solid fluidized beds.In this study,the bubble dynamics properties of four B-particles were investigated in a quasi-two-dimensional(quasi-2D)fluidized bed,including bubble equivalent diameter,bubble size distribution,average bubble density,bubble aspect ratio,bubble hold-up,bed expansion ratio,bubble radial position,and bubble velocity.The studies were performed by computational particle fluid dynamics(CPFD)numerical simulation and post-processed with digital image analysis(DIA)technique,at superficial gas velocities ranging from 2u_(mf) to 7u_(mf).The simulated results shown that the CPFD simulation combining with DIA technique post-processing could be used as a reliable method for simulating bubble dynamics properties in quasi-2D gas-solid fluidized beds.However,it seemed not desirable for the simulation of bubble motion near the air distributor at higher superficial gas velocity from the simulated average bubble density distribution.The superficial gas velocity significantly affected the bubble equivalent diameter and evolution,while it had little influence on bubble size distribution and bubble aspect ratio distribution for the same particles.Both time-averaged bubble hold-up and bed expansion ratio increased with the increase of superficial gas velocity.Two core-annular flow structures could be found in the fluidized bed for all cases.The average bubble rising velocity increased with the increasing bubble equivalent diameter.For bubble lateral movement,the smaller bubbles might be more susceptible,and superficial gas velocity had a little influence on the absolute lateral velocity of bubbles.The simulated results presented a valuable and novel approach for studying bubble dynamics properties.The comprehensive understanding of bubble dynamics behaviors in quasi-2D gas-solid fluidized beds would provide support in the design,operation,and optimization of gas-solid fluidized bed reactors.展开更多
文摘The Ki67 index (KI) is a standard clinical marker for tumor proliferation;however, its application is hindered by intratumoral heterogeneity. In this study, we used digital image analysis to comprehensively analyze Ki67 heterogeneity and distribution patterns in breast carcinoma. Using Smart Pathology software, we digitized and analyzed 42 excised breast carcinoma Ki67 slides. Boxplots, histograms, and heat maps were generated to illustrate the KI distribution. We found that 30% of cases (13/42) exhibited discrepancies between global and hotspot KI when using a 14% KI threshold for classification. Patients with higher global or hotspot KI values displayed greater heterogenicity. Ki67 distribution patterns were categorized as randomly distributed (52%, 22/42), peripheral (43%, 18/42), and centered (5%, 2/42). Our sampling simulator indicated analyzing more than 10 high-power fields was typically required to accurately estimate global KI, with sampling size being correlated with heterogeneity. In conclusion, using digital image analysis in whole-slide images allows for comprehensive Ki67 profile assessment, shedding light on heterogeneity and distribution patterns. This spatial information can facilitate KI surveys of breast cancer and other malignancies.
基金funding from Innovate UK(reference number:10003208)the China Scholarship Council(Grant No.CSC 202408420030).
文摘Digital rock analysis(DRA)is fundamental for geo-energy research,enabling the characterisation of microstructures for applications like hydrocarbon recovery,carbon storage,and groundwater modelling.Although 2D CT images provide valuable pore-scale data,the scarcity of real-world datasets limits the effectiveness of advanced analysis.Generative AI presents a promising approach for synthesizing high-quality rock images but faces key challenges,including high computational demands,insufficient evaluation metrics,and the trade-off between image fidelity and diversity.To address these limitations,this study proposes the use of Low-Rank Adaptation(LoRA)for fine-tuning stable diffusion models,significantly reducing computational requirements while maintaining image quality.A systematic investigation was conducted to evaluate the influence of LoRA training parameters,including rank and learning rate,on the quality of generated images.Image outputs were assessed using both standard generative metrics,such as Kernel Inception Distance(KID),and domain-specific metrics,including porosity,pore count,and pore area distributions.The optimised LoRA-enhanced diffusion model achieved a 92.6% reduction in KID relative to baseline models,while also improving inference speed.Building on these advancements,this study demonstrates that the LoRA-enhanced diffusion model significantly improves neural network extrapolation in incomplete data scenarios through statistically consistent synthetic generation.Despite control challenges,this approach reduces costs and enables diverse applications,bridging fundamental rock physics with practical energy research.
基金National Natural Science Foundation of China,No.41930102,No.41971333,No.41771415。
文摘Digital terrain analysis(DTA)is one of the most important contents in the research of geographical information science(GIS).However,on the basis of the digital elevation model(DEM),many problems exist in the current research of DTA in geomorphological studies.For instance,the current DTA research appears to be focused more on morphology,phenomenon,and modern surface rather than mechanism,process,and underlying terrain.The current DTA research needs to be urgently transformed from the study of landform morphology to one focusing on landform process and mechanism.On this basis,this study summarizes the current research status of geomorphology-oriented DTA and systematically reviews and analyzes the research about the knowledge of geomorphological ontology,terrain modeling,terrain derivative calculation,and terrain analytical methods.With the help of DEM data,DTA research has the advantage of carrying out geomorphological studies from the perspective of surface morphology.However,the study of DTA has inherent defects in terms of data expression and analytic patterns.Thus,breakthroughs in basic theories and key technologies are necessary.Moreover,scholars need to realize that DTA research must be transformed from phenomenon to mechanism,from morphology to process,and from terrain to landform.At present,the research development of earth science has reached the critical stage in which the DTA research should focus more on geomorphological ontology.Consequently,this study proposes several prospects of geomorphology-oriented DTA from the aspects of value-added DEM data model,terrain derivatives and their spatial relations,and macro-terrain analysis.The study of DTA based on DEM is at a critical period along with the issue on whether the current GIS technology can truly support the development of geography.The research idea of geomorphology-oriented DTA is expected to be an important exploration and practice in the field of GIS.
基金upported by a grant from the Technology and Plan of Guangdong Province, China (2009B030801006)
文摘BACKGROUND: The accurate assessment of the degree of hepatic fibrosis plays a critical role in guiding the diagnosis, treatment and prognostic assessment of chronic liver diseases. Liver biopsy is currently the most reliable method to evaluate the severity of hepatic fibrosis. However, liver biopsy is an invasive procedure associated with morbidity and mortality, and has several limitations in patients with decompensated cirrhosis. There is no report on the collagen proportionate area (CPA) of liver tissue in the decompensated stage of cirrhosis. This study aimed to determine the CPA of resected liver tissue samples from patients with HBV-related decompensated cirrhosis using digital image analysis, and to analyze the relationship between the CPA and liver functional reserve. METHODS: Fifty-three resected liver tissue samples from liver transplant patients with chronic hepatitis B-induced decompensated cirrhosis were stained with Masson’s trichrome, and the CPA in these samples was quantitatively determined using digital image analysis. The values of relevant liver function just before liver transplantation, the CPA in liver tissue, and their correlation were analyzed. RESULTS: The mean CPA at the decompensated stage of cirrhosis was 35.93±14.42% (11.24%-63.41%). The correlation coefficients of the CPA with a model for end-stage liver disease score, serum total bilirubin and international standard ratio of prothrombin B were 0.553, 0.519 and 0.533, respectively (P<0.001). With increasing CPA values, the three indices reflecting liver functional reserve also changed significantly.CONCLUSIONS: The degree of fibrosis may be correlated with the functional reserve. With the advancement of fibrosis, the liver functional reserve is attenuated accordingly.
文摘The digital image processing technique was used for the extraction of physical information from the temporal image of phase structure in the process of phase separation in the blend of poly (butylene terephthalate-co-caprolactone )with polycarbonate. The power spectrum images of the two-dimensional Fourier transformation (2DFT) of the temporal image of phase structure reflect the change of the phase size with time.
基金financially supported by the National Natural Science Foundation of China(NNSFC,Project No.42002298)the Chinese Geological Survey(Project Nos.DD20201181,DD20211403)+1 种基金the National Key Research and Development Program of China(NKRDPC,Project No.2017YFC0601501)funded by The Project of"Big Data Analysis and Major Project Evaluation of Strategic Mineral Resources"from the Chinese Geological Survey。
文摘The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration.The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data.To map anomalies in a discrete field model of such data,two corrections are required:background correction and downstream dilution correction.Topography and geomorphology are important factors in variations of element content in stream sediments.However,few studies have considered,through the use of digital terrain analysis,the influence of geomorphic features in downstream dilution correction of stream sediment geochemical data.This study proposes and demonstrates an improvement to the traditional downstream dilution correction equation,based on the use of digital terrain analysis to map single-element anomalies in stream sediment geochemical landscapes.Moreover,this study compares the results of analyses using discrete and continuous field models of stream sediment geochemical data from the Xincang area,Xizang.The efficiency of the proposed methodology was validated against known mineral occurrences.The results indicate that catchment-based analysis outperforms interpolation-based analysis of stream sediment geochemical data for anomaly mapping.Meanwhile,the proposed modified downstream dilution correction equation proved more effective than the original equation.However,further testing of this modified downstream dilution correction is needed in other areas,in order to investigate its efficiency further.
基金supported by National Natural Science Foundation of China(No.1157518)
文摘A digital pulse analysis system is an important diagnostic system in nuclear physics experimental research.In response to the demand for reflecting the particle state in a nuclear physics experiment,we have designed and developed a real-time digital pulse analysis system and applied it to the digital nuclear pulse waveform discrimination of different detectors in the HL-2M tokamak.The system is based on the peripheral component interconnect extensions for instrumentation(PXI)platform,while its software was written in LABVIEW.The key technologies involved in the system implementation include digital pulse analysis technology,digital discrimination technology,pulse height analysis technology,etc.The system has been applied to the plastic scintillator detector at the Neutron Source Lab of the University of Science and Technology of China.And the experimental results indicate that the system can discriminate between neutron(n)particles and gamma(γ)particles well when used to measure the plastic scintillator detector.
文摘The use of Digital Shoreline Analysis System was used to determine shoreline changes in Ikoli River,Yenagoa,Bayelsa State.Shoreline data were extracted from satellite imagery over thirty years(1991-2021).The basis of this study is to use Digital Shoreline Analysis System to determine erosion and accretion areas.The result reveals that the average erosion rate in the study area is 1.16 m/year and the accretion rate is 1.62 m/year along the Ikoli River in Ogbogoro Community in Yenagoa,Bayelsa State.The mean shoreline length is 5.24 km with a baseline length of 5.2 km and the area is classified into four zones to delineate properly area of erosion and accretion based on the five class of Linear regression rate,endpoint rate and weighted linear rate of which zone Ⅰ contain very high erosion and high erosion with an area of landmass 255449.93 m^(2) of 38%,zone Ⅱ contain moderate accretion,very high accretion and high accretion with a land area of 1666816.46 m^(2) with 24%,zone Ⅲ has very high erosion and high erosion with an area of landmass 241610.85 m^(2) of 34% and zone Ⅳ contain moderate accretion and high accretion with land area 30888.08 m^(2) with 4%.Out of the four zones,zone Ⅰ and Ⅱ were found to be eroding with 72% and zone Ⅱ and Ⅳ contain accretion with 28%.The result shows that 44% of the area have been eroded.Therefore,coastal engineers,planners,and shoreline zone management authorities can use DSAS to create more appropriate management plans and regulations for coastal zones and other coastal parts of the state with similar geographic features.
基金supported by the National Natural Science Foundation of China(Grant No.41771423)the Natural Science Foundation of Fujian Province(Grant No.2023J01421).
文摘Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from various perspectives.Peak intervisibility can provide the potential topographic information implied in the visual connectivity of peaks,however,its application in loess landform analysis remains unexplored.In this study,the interwoven sightlines among peaks,representing peak intervisibility,were extracted from the digital elevation model and simulated into a peak intervisibility network(PIN).Nine indices were proposed to quantify the PIN.Through a case study in Northern Shaanxi,China,three tasks were conducted,including,landform interpretation,spatial pattern mining,and landform classification.The main findings are as follows:(1)PIN responds to terrain morphology and is beneficial for loess landform interpretation.(2)The spatial patterns of PIN indices are heterogeneous and strongly coupled with the terrain morphologies,showing anisotropy and autocorrelation in spatial variations.(3)Using the light gradient boost machine classifier,the PIN index-based classification reaches a mean accuracy of 86.09%,an overall accuracy of 86%and a kappa coefficient of 0.84.These findings shed light on the applicability of PIN in loess landform analysis.Peak intervisibility not only enriches the theories and methodologies of relation-based digital terrain analysis,but also enhances our comprehension of loess landform genesis,morphology,distribution,and evolution.
基金funded by the Yunnan Provincial Basic Research Joint Special Fund Project(2019FH001(-052))Cangshan Mountain Synthetic Scientific Expeditions Fund.
文摘The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geographical pattern.Understanding the topographic and geomorphological characteristics of the Hengduan Mountains is fundamental and crucial for research in related fields such as ecology,geography,and sustainability.In this study,Digital Elevation Model(DEM)data were utilized to extract and analyze the topography and geomorphology(TG)pattern.TG maps have been developed to quantitatively classify the TG types in the Hengduan Mountains by combining the five factors of elevation,slope,aspect,relief and landform.The spatial distribution and quantitative characteristics of these factors were mapped and investigated using geographic information systems.The results revealed that:(1)The Hengduan Mountains exhibit an elongated north-south distribution,with an average elevation of approximately 3746 m,an average slope of around 25°,and an average relief of about 266 m.(2)The Hengduan Mountains display significant elevation differences,with an overall high elevation,characterized by a trend of lower elevation in the east and higher elevation in the west,as well as irregular orientations of various aspects.(3)The 19 landform types were identified,the landform types of the Hengduan Mountains are primarily composed of low-relief high-mountains(42.0618%),low-relief mid-mountains(22.4624%),and high-elevation hills(20.5839%).The results of the study can provide data and information support for the ecology,environmental protection and sustainable development of the Hengduan Mountains.
基金funded by the National Natural Science Foundation of China(Grant No.42271417)the financial support from the National Natural Science Foundation of China。
文摘The geomorphic evolution of the Xindiangou small watershed on the Loess Plateau in China is influenced by many factors,resulting in very complex evolutionary characteristics of erosion,morphology,and development.Since 1952,a number of soil and water conservation projects have been implemented in the watershed,especially the largescale project of returning farmland to forest and grass since 1999,which has significant impact on the erosion characteristics of the loess.This paper takes a unique perspective of the watershed geomorphic system and its watershed geomorphic entropy(WGE)and clarifies the geomorphic erosion characteristics of the Xindiangou small watershed.The results show that in the past 45 years,the entropy change of WGE of this watershed has generally shown the characteristics of entropy decrease and local entropy increase.The watershed is dominated by erosion in general,but due to the large-scale implementation of various soil and water conservation projects,especially the Project of Returning Farmland to Forests and Grasslands(RFFG),the landform erosion intensity has been greatly reduced and local increase in the entropy change of WGE has appeared.These projects have achieved good ecological effects after 11 years of implementation.
基金This study was supported by the“2019 Planning Fund Project for Humanities and Social Science Research,Ministry of Education,China”.Project title:“Research on the Image of Utensils in the Remains of Ancient Murals in Shanxi-From Song and Jin to Ming and Qing”(approval number:19YJA760066)This study was supported by the“Teaching Reform and Innovation Project of Higher Education Institutions in Shanxi Province in 2022”,Project title:“Teaching System Reform and Nurturing Practice of Visual Communication Design Major under the View of Double First-class”(Project No.J20220002).
文摘Dao Xuan’s Gantonglu records:“About fifteen kilometers down from the southeast of the Wutai Mountain,there is the ancient Dafu Lingjiu Temple,and there are two Taoist temples in the east and west,where Buddhist matters are fulfilled.According to ancient legend,it was made by Emperor Ming of the Han Dynasty”(Daoxuan,Tang Dynasty,p.257).It can be seen that Buddhism has been introduced into Wutai Mountain since the Eastern Han Dynasty,and Buddhist temple murals have been painted on the walls of temples with the introduction of Buddhism,playing the role of spreading scriptures and decorating the walls.The pattern of Buddha’s futon base in the murals reflects the worship and rank differences of Buddhist monks in different periods.As a medium of meditation and worship,futuan is also a ritual instrument in Buddhist legend,which is of great significance.The research on the style of futon from the perspective of the frescoes in the temple of Wutai Mountain mainly focuses on the historical evolution of the frescoes and futon,the research and analysis of the base shape,pattern,composition and color of the futon in the frescoes of the temple.Explore the religious significance and historical and cultural value behind the futon style.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41471316, 41571383, 41671389)the Priority Academic Program Development of Jiangsu Higher Education Institutions-PAPD (Grant No. 164320H101)the Key Project of Natural Science Research of Anhui Provincial Department of Education (Grant No. KJ2015A171)
文摘Terrain texture analysis is an important method of digital terrain analysis in quantitative geomorphological research and in the exploration of the spatial heterogeneity and autocorrelation of terrain features. However, a major issue often neglected in previous studies is the calculation unit of the terrain texture, that is, the stability analysis unit. As the test size increases, the derived terrain textures become increasingly similar so that their differences can be ignored. The test size of terrain texture is defined as the stability analysis unit. This study randomly selected 48 areas within the Loess Plateau in northern Shaanxi in China as the study sites and used the gray level co-occurrence matrix to calculate the terrain texture. The stability analysis unit of the terrain texture was then extracted, and its spatial distribution pattern in the Loess Plateau was studiedusing spatial interpolation method. Four terrain texture metrics, i.e., homogeneity, energy, correlation, and contrast, were extracted on the basis of the stability analysis unit, and the spatial variation patterns of these parameters were studied. Results showed that the spatial distribution pattern and the terrain texture metrics reflected a trend of high–low–high from north to south, which correlated with the spatial distribution of the landforms at the Loess Plateau. In addition, the terrain texture measures was significantly correlated with the terrain factors of gully density and slope, and this relationship showed that terrain texture measures based on the stability analysis unit could reflect the basic characteristics of terrain morphology. The stability analysis unit provided a reasonable analytical scale for terrain texture analysis and could be used as a measure of the regional topography to accurately describe basic terrain characteristics.
基金This project is supported by National Natural Science Foundation of China (No.E50575234).
文摘A direct digital design method （DDDM） of worm-gear drive is proposed. It is directly based on the simulation of manufacturing process and completely different from the conventional modeling method. The loaded tooth contact analysis （LTCA） method is analyzed, in which the advanced surface to surface searching technique is included. The influence of misalignment errors and contact deformations on contact zone and transmission error （TE） is discussed. Combined modification approach on worm tooth surface is presented. By means of DDDM and LTCA, it is very conven- ient to verify the effect of worm-gear drive＇s modification approach. The analysis results show that, the modification in profile direction reduces the sensitivity of worm-gear drive to misalignment errors and the modification in longitudinal direction decreases the TE. Thus the optimization design of worm-gear drive can be achieved prior to the actual manufacturing process.
基金supported by the Scientific Research Project Fund of Middle East Technical University,under project # BAP-08-11-2016-044
文摘Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide（Ga As：Cr）,as a cathode and an Indium–Tin Oxide（ITO） coated glass electrode as an anode,in reverse bias.The planar nature of electrodes provides symmetry in spatial geometry.The discharge behaves oscillatory in the time domain,with single and sometimes multiperiodicities in plasma current and voltage characteristics.In this paper,harmonic frequency generation and transition to chaotic behavior is investigated.The observed current–voltage characteristics of the discharge are discussed in detail.
文摘BACKGROUND The extraction of maxillary impacted teeth is a common procedure in oral surgery,frequently complicated by oroantral communications.For less-experienced clinicians,accurately assessing the difficulty and associated risks of maxillary third molar extractions remain a significant challenge.CASE SUMMARY We present a case involving disparate outcomes following bilateral extraction of maxillary third molars.Using cone-beam computed tomography and three-dimensional software,we conducted a digital assessment of the factors contributing to extraction difficulty and risk,controlling for potential confounders.Key variables analyzed included alveolar bone volume,bone quality,crown-root angulation,and maxillary sinus mucosal thickness.Additionally,we introduce the novel concept of"tegmen bone"to quantitatively evaluate the bone mass between the teeth and the maxillary sinus.This unique case,with differing outcomes on opposite sides of the same patient,provided an opportunity to minimize extraneous variables and focus on the local anatomical factors influencing the procedures,thereby improving the precision of our analysis.CONCLUSION This case highlights the potential utility of predictive analysis in guiding the management of complex tooth extractions.
基金National Natural Science Foundation of China,No.41930102。
文摘Digital elevation model(DEM)plays a fundamental role in the study of the earth system by expressing surface configuration,understanding surface process,and revealing surface mechanism.DEM is widely used in analysis and modeling in the field of geoscience.However,traditional DEM has the defect of single attribute,which is difficult to support the research in earth system science oriented to geoscience process and mechanism mining.Hence,realizing the value-added data model on the basis of traditional DEM is necessary to serve digital elevation modeling and terrain analysis under the background of a new geomorphology research paradigm and earth observation technology.A theoretical framework for value-added DEM that mainly includes concept,connotation,content,and categories,is constructed in this study.The relationship between different types of value-added DEMs as well as the research significance and application category of this theoretical framework are also proposed.The following are different methods of value-added DEMs:(1)value-added methods of DEM space and time dimensions that emphasize the integration of the ground and underground as well as coupling of time and space,(2)attribute-based value-added methods composed of material(including underground,surface,and ground)and morphological properties,and(3)value-added methods of features and physical elements that consider geographical objects and landform features formed by natural processes and artificial effects.The digital terrace,slope,and watershed models are used as examples to illustrate application scenarios of the three kinds of value-added methods.This study aims to improve expression methods of DEMs under the background of new surveying and mapping technologies by adding value to the DEM at three levels of dimensions,attributes,and elements as well as support knowledge-driven digital geomorphological analysis in the era of big data.
基金the support of EPIC-Energy Production Innovation Center,hosted by the University of Campinas(UNICAMP)sponsored by FAPESP-Sao Paulo Research Foundation(2017/15736e3 process).
文摘Brazilian pre-salt reservoirs are renowned for their intricate pore networks and vuggy nature,posing significant challenges in modeling and simulating fluid flow within these carbonate reservoirs.Despite possessing excellent petrophysical properties,such as high porosity and permeability,these reservoirs typically exhibit a notably low recovery factor,sometimes falling below 10%.Previous research has indicated that various enhanced oil recovery(EOR)methods,such as water alternating gas(WAG),can substantially augment the recovery factor in pre-salt reservoirs,resulting in improvements of up to 20%.Nevertheless,the fluid flow mechanism within Brazilian carbonate reservoirs,characterized by complex pore geometry,remains unclear.Our study examines the behavior of fluid flow in a similar heterogeneous porous material,utilizing a plug sample obtained from a vugular segment of a Brazilian stromatolite outcrop,known to share analogies with certain pre-salt reservoirs.We conducted single-phase and multi-phase core flooding experiments,complemented by medical-CT scanning,to generate flow streamlines and evaluate the efficiency of water flooding.Subsequently,micro-CT scanning of the core sample was performed,and two cross-sections from horizontal and vertical plates were constructed.These cross-sections were then employed as geometries in a numerical simulator,enabling us to investigate the impact of pore geometry on fluid flow.Analysis of the pore-scale modeling and experimental data unveiled that the presence of dead-end pores and vugs results in a significant portion of the fluid remaining stagnant within these regions.Consequently,the injected fluid exhibits channeling-like behavior,leading to rapid breakthrough and low areal swept efficiency.Additionally,the numerical simulation results demonstrated that,irrespective of the size of the dead-end regions,the pressure variation within the dead-end vugs and pores is negligible.Despite the stromatolite's favorable petrophysical properties,including relatively high porosity and permeability,as well as the presence of interconnected large vugs,the recovery factor during water flooding remained low due to early breakthrough.These findings align with field data obtained from pre-salt reservoirs,providing an explanation for the observed low recovery factor during water flooding in such reservoirs.
基金supported by the Russian Science Foundation(Grant No.22-11-00273).
文摘The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells,and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone-the method of directional unloading of the reservoir.The digital part of the research included computed tomography(CT)-based computer analysis of the internal structure,pore space characteristics,and filtration properties before and after the tests.According to the results of physical modeling of deformation and filtration processes,it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly,and this influence is reversible.However,when downhole pressure reaches 7-8 MPa,macrocracks in the rock begin to grow,accompanied by irreversible permeability increase.Porosity,geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling.A weak degree of transversal anisotropy of the filtration properties of rocks was detected.Based on the analysis of pore size distribution,pressure field and flow velocities,high homogeneity and connectivity of the rock pore space is shown.The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown.On the basis of geometrical analysis of pore space,the reasons for weak permeability anisotropy were identified.The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements.The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study.The necessary parameters of its application were calculated:bottomhole geometry,stage of operation,stresses and pressure drawdown value.
基金the financial support provided by National Key R&D Project of China(grant No.2020YFB0606303)the technical supports received from Sam Clark in CPFD Software,LLC of USA,and from Hi-Key Technology Incorporated of China.
文摘Bubble dynamics properties play a crucial and significant role in the design and optimization of gas-solid fluidized beds.In this study,the bubble dynamics properties of four B-particles were investigated in a quasi-two-dimensional(quasi-2D)fluidized bed,including bubble equivalent diameter,bubble size distribution,average bubble density,bubble aspect ratio,bubble hold-up,bed expansion ratio,bubble radial position,and bubble velocity.The studies were performed by computational particle fluid dynamics(CPFD)numerical simulation and post-processed with digital image analysis(DIA)technique,at superficial gas velocities ranging from 2u_(mf) to 7u_(mf).The simulated results shown that the CPFD simulation combining with DIA technique post-processing could be used as a reliable method for simulating bubble dynamics properties in quasi-2D gas-solid fluidized beds.However,it seemed not desirable for the simulation of bubble motion near the air distributor at higher superficial gas velocity from the simulated average bubble density distribution.The superficial gas velocity significantly affected the bubble equivalent diameter and evolution,while it had little influence on bubble size distribution and bubble aspect ratio distribution for the same particles.Both time-averaged bubble hold-up and bed expansion ratio increased with the increase of superficial gas velocity.Two core-annular flow structures could be found in the fluidized bed for all cases.The average bubble rising velocity increased with the increasing bubble equivalent diameter.For bubble lateral movement,the smaller bubbles might be more susceptible,and superficial gas velocity had a little influence on the absolute lateral velocity of bubbles.The simulated results presented a valuable and novel approach for studying bubble dynamics properties.The comprehensive understanding of bubble dynamics behaviors in quasi-2D gas-solid fluidized beds would provide support in the design,operation,and optimization of gas-solid fluidized bed reactors.
