Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical si...Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.展开更多
Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted dru...Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.展开更多
The Microwave Land Surface Emissivity(MLSE)atlas and instantaneous simulation of all-sky/all-surface MLSE are important prerequisites for satellite data assimilation.A ten-day/month synthesized FengYun-3D MLSE atlas(N...The Microwave Land Surface Emissivity(MLSE)atlas and instantaneous simulation of all-sky/all-surface MLSE are important prerequisites for satellite data assimilation.A ten-day/month synthesized FengYun-3D MLSE atlas(New_FY3D)was constructed by the two global MLSE daily product datasets,clear-sky(FY-3D1)and clear/cloudy(FY-3D2),which were retrieved from the same FY-3D MicroWave Radiation Imager(MWRI)Level-1 brightness temperature(BT)data from 2021 to 2022,respectively.Then,a set of global MLSE label samples based on the New_FY3D,including 14 surface geophysical parameters,was obtained for an instantaneous global MLSE simulation at a 0.10°spatial resolution by adopting the extreme gradient boosting(XGBoost)machine learning method.Finally,the FengYun-3F(FY-3F)MWRI-II BT simulations using the Advanced Radiative Transfer Modeling System(ARMS)based on the above different MLSE products were evaluated.The results show that the New_FY3D atlas performs well,and the BT simulation at the top of atmosphere is better than that of FY-3D1,FY-3D2,and the international mainstream TELSEM2(Version 2.0 for a Tool to Estimate Land Surface Emissivities in the Microwaves)atlas.Surface roughness,vegetation coverage,land cover type,and snow cover are vital parameters for MLSE simulation.The XGBoost model can accurately simulate all-sky/all-surface MLSE instantaneously over the frequency range 10.65–89.0 GHz.The average simulation determination coefficients(R^(2))under clear-sky and cloud-sky conditions are 0.925 and 0.901,respectively,and the average root-mean-square errors(RMSEs)are 0.018 and 0.021,respectively.Large simulation errors occur in permanent wetland,ice and snow,and urban and built-up areas.With a standard deviation of 6.6 K,the BT simulation based on an XGBoost simulated MLSE is better than those based on New_FY3D and TELSEM2.展开更多
Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This st...Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This study evaluates the carbon footprint(CF)and economic viability of a liquefied natural gas(LNG)-fueled fishing vessel,using real engine operation simulations to provide precise and dynamic evaluation of fuel consumption and GHG emissions.Operational profiles are obtained through the utilization of onboard monitoring systems,whereas engine performance is simulated using the 1D/0D AVL Boost^(TM)model.Life cycle assessment(LCA)is conducted to quantify the environmental impact,whereas life cycle cost assessment(LCCA)is performed to analyze the profitability of LNG as an alternative fuel.The potential impact of the future fuel price uncertainties is addressed using Monte Carlo simulations.The LCA findings indicate that LNG has the potential to reduce the CF of the vessel by 14%to 16%,in comparison to a diesel power system configuration that serves as the baseline scenario.The LCCA results further indicate that the total cost of an LNG-powered ship is lower by 9.5%-13.8%,depending on the share of LNG and pilot fuels.This finding highlights the potential of LNG to produce considerable environmental benefits while addressing economic challenges under diverse operational and fuel price conditions.展开更多
Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results ...Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results demonstrate that biases in the range 1.62 to 1.98V influence DSET current shape greatly and total collected charge weakly. Peak current and charge collection within 2ns decreases as temperature increases,and temperature has a stronger influence on SET currents than on total charge. Typical variation of substrate concentration in modern VDSM processes has a negligible effect on SEEs. Both peak current and total collection charge increases as LET increases.展开更多
Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this stud...Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.展开更多
目的探讨不同严重程度急性呼吸窘迫征(ARDS)患者血清1,25-二羟维生素D3[1,25-(OH)_(2)D_(3)]水平变化及其与预后的关系。方法将150例ARDS患者根据氧合指数分为轻度组(200 mm Hg<氧合指数≤300 mm Hg,54例)、中度组(100 mm Hg<氧...目的探讨不同严重程度急性呼吸窘迫征(ARDS)患者血清1,25-二羟维生素D3[1,25-(OH)_(2)D_(3)]水平变化及其与预后的关系。方法将150例ARDS患者根据氧合指数分为轻度组(200 mm Hg<氧合指数≤300 mm Hg,54例)、中度组(100 mm Hg<氧合指数≤200 mm Hg,50例)、重度组(氧合指数≤100 mm Hg,46例)。根据预后情况再将其分为预后良好组(98例)与预后不良组(52例)。收集所有患者的一般资料、临床资料及实验室检查指标并分组进行比较。采用多元线性回归分析不同严重程度组ARDS患者1,25-(OH)_(2)D_(3)与炎症反应指标的相关性。采用多因素logistic回归分析评估影响ARDS患者预后的相关因素。采用共线性诊断检验自变量间的共线性。采用cox比例风险模型调整混杂变量后,分析1,25-(OH)_(2)D_(3)与炎症反应指标对ARDS患者预后的交互作用。采用logistic回归模型结合限制性立方样条模型(RCS)评估1,25-(OH)_(2)D_(3)和不同严重程度的ARDS患者预后的剂量-反应关系。结果轻度组、中度组、重度组患者1,25-(OH)_(2)D_(3)水平依次降低,急性生理和慢性疾病(APACHEⅡ)评分、脓毒症相关器官衰竭(SOFA)评分、降钙素原(PCT)、N末端B型脑钠肽前体(NT-proBNP)、C反应蛋白(CRP)、WBC计数、碱性成纤维细胞生长因子2(FGF2)、肿瘤坏死因子-α(TNF-α)、IL-6、IL-1β水平均依次升高(P<0.05)。多元线性回归分析结果显示,调整了相关因素后不同严重程度组ARDS患者TNF-α、IL-6、IL-1β均与1,25-(OH)_(2)D_(3)呈独立负相关(P<0.05)。预后不良组患者氧合指数及1,25-(OH)_(2)D_(3)水平均低于预后良好组,APACHEⅡ评分、SOFA评分、PCT、NT-proBNP、CRP、WBC计数、FGF2、TNF-α、IL-6、IL-1β水平均高于预后良好组(P<0.05)。多因素logistic回归分析结果显示,APACHEⅡ评分、氧合指数、FGF2、PCT、NT-proBNP、SOFA评分、1,25-(OH)_(2)D_(3)、TNF-α、IL-6、IL-1β均是影响ARDS患者预后的独立因素(P<0.05)。共线性诊断检验结果提示变量之间相互独立,不存在共线性。交互作用分析结果显示,相加及相乘模型中,1,25-(OH)_(2)D_(3)与TNF-α、IL-6、IL-1β对ARDS患者预后的影响均存在交互作用。RCS模型分析结果显示,1,25-(OH)_(2)D_(3)水平与轻度组、中度组、重度组ARDS患者预后不良发生风险均呈非线性相关(P_(非线性)=0.046、0.042、0.048)。结论血清1,25-(OH)_(2)D_(3)水平能够用来判断ARDS患者的病情严重程度,且1,25-(OH)_(2)D_(3)对ARDS患者预后具有一定的预测价值。展开更多
基金financially supported by the National Key Research and Development Program of China (2022YFB3706802)。
文摘Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.
文摘Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.
基金supported by the National Natural Science Foundation of China(Grant No.U2242211)the Hunan Provincial Natural Science Foundation Major Project(Grant No.2021JC0009).
文摘The Microwave Land Surface Emissivity(MLSE)atlas and instantaneous simulation of all-sky/all-surface MLSE are important prerequisites for satellite data assimilation.A ten-day/month synthesized FengYun-3D MLSE atlas(New_FY3D)was constructed by the two global MLSE daily product datasets,clear-sky(FY-3D1)and clear/cloudy(FY-3D2),which were retrieved from the same FY-3D MicroWave Radiation Imager(MWRI)Level-1 brightness temperature(BT)data from 2021 to 2022,respectively.Then,a set of global MLSE label samples based on the New_FY3D,including 14 surface geophysical parameters,was obtained for an instantaneous global MLSE simulation at a 0.10°spatial resolution by adopting the extreme gradient boosting(XGBoost)machine learning method.Finally,the FengYun-3F(FY-3F)MWRI-II BT simulations using the Advanced Radiative Transfer Modeling System(ARMS)based on the above different MLSE products were evaluated.The results show that the New_FY3D atlas performs well,and the BT simulation at the top of atmosphere is better than that of FY-3D1,FY-3D2,and the international mainstream TELSEM2(Version 2.0 for a Tool to Estimate Land Surface Emissivities in the Microwaves)atlas.Surface roughness,vegetation coverage,land cover type,and snow cover are vital parameters for MLSE simulation.The XGBoost model can accurately simulate all-sky/all-surface MLSE instantaneously over the frequency range 10.65–89.0 GHz.The average simulation determination coefficients(R^(2))under clear-sky and cloud-sky conditions are 0.925 and 0.901,respectively,and the average root-mean-square errors(RMSEs)are 0.018 and 0.021,respectively.Large simulation errors occur in permanent wetland,ice and snow,and urban and built-up areas.With a standard deviation of 6.6 K,the BT simulation based on an XGBoost simulated MLSE is better than those based on New_FY3D and TELSEM2.
文摘Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This study evaluates the carbon footprint(CF)and economic viability of a liquefied natural gas(LNG)-fueled fishing vessel,using real engine operation simulations to provide precise and dynamic evaluation of fuel consumption and GHG emissions.Operational profiles are obtained through the utilization of onboard monitoring systems,whereas engine performance is simulated using the 1D/0D AVL Boost^(TM)model.Life cycle assessment(LCA)is conducted to quantify the environmental impact,whereas life cycle cost assessment(LCCA)is performed to analyze the profitability of LNG as an alternative fuel.The potential impact of the future fuel price uncertainties is addressed using Monte Carlo simulations.The LCA findings indicate that LNG has the potential to reduce the CF of the vessel by 14%to 16%,in comparison to a diesel power system configuration that serves as the baseline scenario.The LCCA results further indicate that the total cost of an LNG-powered ship is lower by 9.5%-13.8%,depending on the share of LNG and pilot fuels.This finding highlights the potential of LNG to produce considerable environmental benefits while addressing economic challenges under diverse operational and fuel price conditions.
文摘Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results demonstrate that biases in the range 1.62 to 1.98V influence DSET current shape greatly and total collected charge weakly. Peak current and charge collection within 2ns decreases as temperature increases,and temperature has a stronger influence on SET currents than on total charge. Typical variation of substrate concentration in modern VDSM processes has a negligible effect on SEEs. Both peak current and total collection charge increases as LET increases.
基金financially supported by the National Key R&D Program of China(Grant No.2023YFC3081200)the National Natural Science Foundation of China(Grant Nos.U21A20159 and 52179117).
文摘Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.
文摘目的探讨不同严重程度急性呼吸窘迫征(ARDS)患者血清1,25-二羟维生素D3[1,25-(OH)_(2)D_(3)]水平变化及其与预后的关系。方法将150例ARDS患者根据氧合指数分为轻度组(200 mm Hg<氧合指数≤300 mm Hg,54例)、中度组(100 mm Hg<氧合指数≤200 mm Hg,50例)、重度组(氧合指数≤100 mm Hg,46例)。根据预后情况再将其分为预后良好组(98例)与预后不良组(52例)。收集所有患者的一般资料、临床资料及实验室检查指标并分组进行比较。采用多元线性回归分析不同严重程度组ARDS患者1,25-(OH)_(2)D_(3)与炎症反应指标的相关性。采用多因素logistic回归分析评估影响ARDS患者预后的相关因素。采用共线性诊断检验自变量间的共线性。采用cox比例风险模型调整混杂变量后,分析1,25-(OH)_(2)D_(3)与炎症反应指标对ARDS患者预后的交互作用。采用logistic回归模型结合限制性立方样条模型(RCS)评估1,25-(OH)_(2)D_(3)和不同严重程度的ARDS患者预后的剂量-反应关系。结果轻度组、中度组、重度组患者1,25-(OH)_(2)D_(3)水平依次降低,急性生理和慢性疾病(APACHEⅡ)评分、脓毒症相关器官衰竭(SOFA)评分、降钙素原(PCT)、N末端B型脑钠肽前体(NT-proBNP)、C反应蛋白(CRP)、WBC计数、碱性成纤维细胞生长因子2(FGF2)、肿瘤坏死因子-α(TNF-α)、IL-6、IL-1β水平均依次升高(P<0.05)。多元线性回归分析结果显示,调整了相关因素后不同严重程度组ARDS患者TNF-α、IL-6、IL-1β均与1,25-(OH)_(2)D_(3)呈独立负相关(P<0.05)。预后不良组患者氧合指数及1,25-(OH)_(2)D_(3)水平均低于预后良好组,APACHEⅡ评分、SOFA评分、PCT、NT-proBNP、CRP、WBC计数、FGF2、TNF-α、IL-6、IL-1β水平均高于预后良好组(P<0.05)。多因素logistic回归分析结果显示,APACHEⅡ评分、氧合指数、FGF2、PCT、NT-proBNP、SOFA评分、1,25-(OH)_(2)D_(3)、TNF-α、IL-6、IL-1β均是影响ARDS患者预后的独立因素(P<0.05)。共线性诊断检验结果提示变量之间相互独立,不存在共线性。交互作用分析结果显示,相加及相乘模型中,1,25-(OH)_(2)D_(3)与TNF-α、IL-6、IL-1β对ARDS患者预后的影响均存在交互作用。RCS模型分析结果显示,1,25-(OH)_(2)D_(3)水平与轻度组、中度组、重度组ARDS患者预后不良发生风险均呈非线性相关(P_(非线性)=0.046、0.042、0.048)。结论血清1,25-(OH)_(2)D_(3)水平能够用来判断ARDS患者的病情严重程度,且1,25-(OH)_(2)D_(3)对ARDS患者预后具有一定的预测价值。
文摘目的探索人工智能辅助压缩感知(artificial intelligence-assisted compressed sensing,ACS)技术加速颅内血管壁高分辨率三维T1加权黑血成像(three-dimensional T1-weighted black blood imaging,3D T1_HRVWI)的可行性,并与临床常规采用的并行采集技术(parallel imaging,PI)进行对比分析。方法前瞻性纳入47例脑血管疾病患者,行ACS加速(实验组)和PI加速(对照组)的3D T1_HRVWI扫描。客观比较ACS组和PI组的序列扫描时长、图像中血管壁的信噪比以及相对于血管腔的对比噪声比,主观评估两组图像总体质量、颅内血管显示情况及病灶诊断价值,并进行统计分析。结果相较于PI 3D T1_HRVWI,ACS 3D T1_HRVWI的扫描时长缩短43%;ACS 3D T1_HRVWI图像中颈内动脉、基底动脉、椎动脉、大脑前动脉、大脑中动脉、大脑后动脉血管壁的信噪比均显著升高(P<0.001);两组图像的总体质量评分和颅内血管的显示评分均未见显著差异(P>0.05);两组图像的病灶诊断价值相当(P>0.05)。结论ACS技术实现了3D T1_HRVWI序列更快的采集速度,同时保持了较好的成像质量,为开发兼顾扫描效率与诊断精度的脑血管影像扫描方案提供了循证依据,在脑血管疾病的精准诊断中展现出重要价值。
