The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioac...The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioactive substances,such as radioactive 129I and 131I.The transportation of radioactive iodine poses a significant threat to both the environment and human health.Nevertheless,effectively,rapidly removing iodine ion from water using porous adsorbents remains a crucial challenge.In this work,three kinds of multiple sites porous organic polymers(POPs,POP-1,POP-2,and POP-3)have been developed using a monomer pre-modification strategy for highly efficient and fast I_(3) absorption from water.It is found that the POPs exhibited exceptional performance in terms of I3 adsorption,achieving a top-performing adsorption capacity of 5.25 g g^(-1) and the fastest average adsorption rate(K_(80%)=4.25 g g^(-1) h^(-1))with POP-1.Moreover,POP-1 exhibited exceptional capacity for the removal of I3 fromflowing aqueous solutions,with 95%removal efficiency observed even at 0.0005 mol L^(-1).Such results indicate that this material has the potential to be utilized for the emergency preparation of potable water in areas contaminated with radioactive iodine.The adsorption process can be effectively characterized by the Freundlich model and the pseudo-second-order model.The exceptional I_(3) absorption capacity is primarily attributed to the incorporation of a substantial number of active adsorption sites,including bromine,carbonyl,and amide groups.展开更多
High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for t...High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.展开更多
The wireless full-duplex(FD) nodes can transmit and receive at the same time using the same frequency-band. Currently, the latest FD media access control(MAC) protocols mainly focus on how to convert the physical laye...The wireless full-duplex(FD) nodes can transmit and receive at the same time using the same frequency-band. Currently, the latest FD media access control(MAC) protocols mainly focus on how to convert the physical layer gains of FD nodes to the throughput gain of wireless FD networks, but pay little attention to the energy consumptions of FD nodes. In this paper, we propose an energy efficient FD MAC protocol. According to the values of self-interference cancellation coefficients corresponding to the nodes of each FD pair and the signal propagation attenuation, the proposed protocol can adaptively select the communication mode of the FD pair between the full-duplex and half-duplex. Also, the minimum transmit power for FD nodes can be obtained to achieve high energy efficiency. We develop an analytical model to characterize the performance of our protocol. The numerical results show that the proposed MAC protocol can optimize the system throughput and reduce the transmission energy consumptions of nodes simultaneously as compared with those of the existing works.展开更多
The hydrogen abstraction reaction F+CH3OH has two possible reaction pathways: HF+CH3O and HF+CH2OH. Despite the absence of intrinsic barriers for both channels, the former has a branching ratio comparable to the latte...The hydrogen abstraction reaction F+CH3OH has two possible reaction pathways: HF+CH3O and HF+CH2OH. Despite the absence of intrinsic barriers for both channels, the former has a branching ratio comparable to the latter, which is far from the statistical limit of 0.25 (one out of four available H atoms). Furthermore, the measured branching ratio of the two abstraction channels spans a large range and is not quantitatively reproduced by previous theoretical predictions based on the transition-state theory with the stationary point information calculated at the levels of MФller-Plesset perturbation theory and G2. This work reports a theoretical investigation on the kinetics and the associated branching ratio of the two competing channels of the title reaction using a quasi-classical trajectory approach on an accurate full-dimensional potential energy surface (PES) fitted by the permutation invariant polynomial-neural network approach to ca. 1.21x10^5 points calculated at the explicitly correlated (F12a) version of coupled cluster singles doubles and perturbative triples (CCSD(T)) level with the aug-cc-pVDZ basis set. The calculated room temperature rate coeffcient and branching ratio of the HF+CH3O channel are in good agreement with the available experimental data. Furthermore, our theory predicts that rate coeffcients have a slightly negative temperature dependence, consistent with barrierless nature of the reaction.展开更多
In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of ...In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.展开更多
The paper attempts to analyze full load characteristics of over 500 combustion engines. Using statistical tools, the author determined the value of the coe cient of flexibility. Engine flexibility is the capability of...The paper attempts to analyze full load characteristics of over 500 combustion engines. Using statistical tools, the author determined the value of the coe cient of flexibility. Engine flexibility is the capability of the engine to adapt to varying loads. Importantly, in the investigations, the author took into account the parameters calculated in the course of the investigations on a chassis dynamometer, i.e., actual, not taken from technical specifications of brand new vehicles. Di erent stages of operating wear allow a better characterization of the population. Subsequent utilization of the results in tractive calculations is more reliable. The engines were divided into in six groups, depending on the type of fuel system: fuel injected gasoline and turbocharged gasoline, spark ignition LPG, naturally aspirated diesel and turbocharged diesel. However, engines running on alternative fuels are characterized with a greater flexibility than the fuel injected base engines. Conformity of flexibility of fuel injected and LPG IV generation engines have been observed,which confirms the appropriateness of engine adaptation to alternative fueling. Gasoline engine supercharging allowed a reduction of the maximum engine speed of the maximum torque, which extends the range of analyzable speeds for flexibility and consequently, the flexibility as such.展开更多
A Wireless Sensor Network(WSN)becomes a newer type of real-time embedded device that can be utilized for a wide range of applications that make regular networking which appears impracticable.Concerning the energy prod...A Wireless Sensor Network(WSN)becomes a newer type of real-time embedded device that can be utilized for a wide range of applications that make regular networking which appears impracticable.Concerning the energy produc-tion of the nodes,WSN has major issues that may influence the stability of the system.As a result,constructing WSN requires devising protocols and standards that make the most use of constrained capacity,especially the energy resources.WSN faces some issues with increased power utilization and an on going devel-opment due to the uneven energy usage between the nodes.Clustering has proven to be a more effective strategy in this series.In the proposed work,a hybrid meth-od is used for reducing the energy consumption among CHs.A Fuzzy Logic-based clustering protocol FLUC(unequally clustered)and Fuzzy Clustering with Energy-Efficient Routing Protocol(FCERP)are used.A Fuzzy Clustering with Energy Efficient Routing Protocol(FCERP)reduces the WSN power usage and increases the lifespan of the network.FCERP has created a novel cluster-based fuzzy routing mechanism that uses a limit value to combine the clustering and multi-hop routing capabilities.The technique creates uneven groups by using fuz-zy logic with a competitive range to choose the Cluster Head(CH).The input variables include the distance of the nodes from the ground station,concentra-tions,and remaining energy.The proposed FLUC-FCERP reduces the power usage and improves the lifetime of the network compared with the existing algorithms.展开更多
The Wireless Sensor Network(WSN)is a network of Sensor Nodes(SN)which adopt radio signals for communication amongst themselves.There is an increase in the prominence of WSN adaptability to emerging applications like t...The Wireless Sensor Network(WSN)is a network of Sensor Nodes(SN)which adopt radio signals for communication amongst themselves.There is an increase in the prominence of WSN adaptability to emerging applications like the Internet of Things(IoT)and Cyber-Physical Systems(CPS).Data secur-ity,detection of faults,management of energy,collection and distribution of data,network protocol,network coverage,mobility of nodes,and network heterogene-ity are some of the issues confronted by WSNs.There is not much published information on issues related to node mobility and management of energy at the time of aggregation of data.Towards the goal of boosting the mobility-based WSNs’network performance and energy,data aggregation protocols such as the presently-used Mobility Low-Energy Adaptive Clustering Hierarchy(LEACH-M)and Energy Efficient Heterogeneous Clustered(EEHC)scheme have been exam-ined in this work.A novel Artificial Bee Colony(ABC)algorithm is proposed in this work for effective election of CHs and multipath routing in WSNs so as to enable effective data transfer to the Base Station(BS)with least energy utilization.There is avoidance of the local optima problem at the time of solution space search in this proposed technique.Experimentations have been conducted on a large WSN network that has issues with mobility of nodes.展开更多
To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concret...To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.展开更多
Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;howev...Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;however,achieving ultrahigh precision and ultralow damage machining of functional devices using traditional techniques such as grinding and polishing is extremely challenging.Consequently,nanocutting has emerged as an efficient means to fabricate monocrystalline materials with complex surface characteristics and high surface integrity.Nevertheless,the macroscopic cutting theory of metal materials cannot be applied to nanocutting.Accordingly,in this paper,both simulations and experiments were conducted to examine the chip deformation mechanisms of monocrystalline Cu.First,large-scale molecular dynamics(MD)simulations were conducted to gain a comprehensive understanding of the deformation behavior during nanocutting.This included examining the influencing factors and the variation patterns of the chip deformation coefficient,cutting force,and minimum cutting thickness.Subsequently,nanocutting experiments were performed using a specially designed nanocutting platform with high-resolution online observation by scanning electron microscopy.The experimental results served to verify the accuracy and reliability of theMDmodeling,as they exhibited excellent consistency with the simulated results.Although this work considered monocrystalline Cu,it is believed that the elucidated chip deformation mechanisms could also be applied to other face-centered-cubic metals.These results are of great value for advancing the understanding of the mechanisms of ultraprecision cutting.展开更多
目的:探讨超声黏弹性成像技术在乳腺肿瘤良恶性鉴别中的应用价值。方法:连续纳入2023年2月至2023年8月期间,上海交通大学医学院附属瑞金医院收治的经手术病理证实为乳腺肿瘤的717例患者,其中471例为恶性,246例为良性。所有患者均在治疗...目的:探讨超声黏弹性成像技术在乳腺肿瘤良恶性鉴别中的应用价值。方法:连续纳入2023年2月至2023年8月期间,上海交通大学医学院附属瑞金医院收治的经手术病理证实为乳腺肿瘤的717例患者,其中471例为恶性,246例为良性。所有患者均在治疗前进行乳腺超声检查,包括灰阶超声、超声应变弹性成像、超声剪切波弹性成像、超声黏性成像。超声黏弹性成像技术包括测量肿瘤及其周围组织的黏性系数、频散系数和剪切波弹性模量、应变比等4组参数,以4组参数中的较佳预测指标,分别构建多种预测模型,包括黏性系数单变量模型、频散系数单变量模型、黏性组合模型(Shell/T-Vmean+Shell/T-Dmean)、剪切波单变量模型、应变单变量模型、乳腺影像报告和数据系统(Breast Imaging Reporting and Data System,BI-RADS)、BI-RADS联合黏性组合模型,评估每种模型在乳腺肿瘤良恶性鉴别中的效能。结果:超声黏弹性成像的黏性系数、频散系数、弹性模量及应变比等参数均可有效地区分乳腺良恶性肿瘤,其中肿瘤边缘2 mm区域与瘤体的参数比值Shell/T-Vmean、Shell/T-Dmean、Shell/T-Emean、Strain Ratio A为较佳预测指标,曲线下面积分别为0.742、0.745、0.726、0.705,而BI-RADS模型预测乳腺肿瘤良恶性的0.822。将Shell/T-Vmean、Shell/T-Dmean分别与BI-RADS分类联合时,受试者操作特征曲线的曲线下面积高达0.895(95%CI为0.868~0.917),高于BI-RADS。结论:超声黏弹性成像的黏弹性参数中,肿瘤边缘2 mm区域与瘤体的黏性系数、频散系数及弹性模量均值比为关键诊断指标;Shell/T-Vmean、Shell/T-Dmean联合BI-RADS后,可为术前无创精准诊断提供了新策略。展开更多
基金support from the National Natural Science Foundation of China(No.22273016,22273017,22233006)Plan for Henan Province University Science and Technology Innovation Team(No.25IRTSTHN002)+1 种基金Young Backbone Teacher Training Program of Henan Province(2023GGJS036)the 111 project(No.D17007).
文摘The utilization of nuclear power will persist as a prominent energy source in the foreseeable future.However,it presents substantial challenges concerning waste disposal and the potential emission of untreated radioactive substances,such as radioactive 129I and 131I.The transportation of radioactive iodine poses a significant threat to both the environment and human health.Nevertheless,effectively,rapidly removing iodine ion from water using porous adsorbents remains a crucial challenge.In this work,three kinds of multiple sites porous organic polymers(POPs,POP-1,POP-2,and POP-3)have been developed using a monomer pre-modification strategy for highly efficient and fast I_(3) absorption from water.It is found that the POPs exhibited exceptional performance in terms of I3 adsorption,achieving a top-performing adsorption capacity of 5.25 g g^(-1) and the fastest average adsorption rate(K_(80%)=4.25 g g^(-1) h^(-1))with POP-1.Moreover,POP-1 exhibited exceptional capacity for the removal of I3 fromflowing aqueous solutions,with 95%removal efficiency observed even at 0.0005 mol L^(-1).Such results indicate that this material has the potential to be utilized for the emergency preparation of potable water in areas contaminated with radioactive iodine.The adsorption process can be effectively characterized by the Freundlich model and the pseudo-second-order model.The exceptional I_(3) absorption capacity is primarily attributed to the incorporation of a substantial number of active adsorption sites,including bromine,carbonyl,and amide groups.
基金the National Key Research and Development Program of China(Grant No.2021YFB2012100)the Major Science and Technology Projects in Fujian Province(Grant No.2023HZ021005)+1 种基金the Open Project Program of Fujian Key Laboratory of Special Intelligent Equipment Measurement and Control(Grant No.FJIES2023KF06)the Industry-University-Research Co-operation Fund of the Eighth Research Institute of China Aerospace Science and Technology Corporation(Grant No.SAST2023-061).
文摘High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.
基金supported by the National Natural Science Foundation of China (No. 61401330)Natural Science Foundation of Shaanxi Province of China (No. 2016JQ6027)
文摘The wireless full-duplex(FD) nodes can transmit and receive at the same time using the same frequency-band. Currently, the latest FD media access control(MAC) protocols mainly focus on how to convert the physical layer gains of FD nodes to the throughput gain of wireless FD networks, but pay little attention to the energy consumptions of FD nodes. In this paper, we propose an energy efficient FD MAC protocol. According to the values of self-interference cancellation coefficients corresponding to the nodes of each FD pair and the signal propagation attenuation, the proposed protocol can adaptively select the communication mode of the FD pair between the full-duplex and half-duplex. Also, the minimum transmit power for FD nodes can be obtained to achieve high energy efficiency. We develop an analytical model to characterize the performance of our protocol. The numerical results show that the proposed MAC protocol can optimize the system throughput and reduce the transmission energy consumptions of nodes simultaneously as compared with those of the existing works.
基金supported by the National Natural Science Foundation of China (No.21573027 to Jun Li)the US Department of Energy (DE-SC0015997 to Hua Guo)
文摘The hydrogen abstraction reaction F+CH3OH has two possible reaction pathways: HF+CH3O and HF+CH2OH. Despite the absence of intrinsic barriers for both channels, the former has a branching ratio comparable to the latter, which is far from the statistical limit of 0.25 (one out of four available H atoms). Furthermore, the measured branching ratio of the two abstraction channels spans a large range and is not quantitatively reproduced by previous theoretical predictions based on the transition-state theory with the stationary point information calculated at the levels of MФller-Plesset perturbation theory and G2. This work reports a theoretical investigation on the kinetics and the associated branching ratio of the two competing channels of the title reaction using a quasi-classical trajectory approach on an accurate full-dimensional potential energy surface (PES) fitted by the permutation invariant polynomial-neural network approach to ca. 1.21x10^5 points calculated at the explicitly correlated (F12a) version of coupled cluster singles doubles and perturbative triples (CCSD(T)) level with the aug-cc-pVDZ basis set. The calculated room temperature rate coeffcient and branching ratio of the HF+CH3O channel are in good agreement with the available experimental data. Furthermore, our theory predicts that rate coeffcients have a slightly negative temperature dependence, consistent with barrierless nature of the reaction.
文摘In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.
基金financed from the funding allocated for science by the Ministry of Science and Higher Education–Poland
文摘The paper attempts to analyze full load characteristics of over 500 combustion engines. Using statistical tools, the author determined the value of the coe cient of flexibility. Engine flexibility is the capability of the engine to adapt to varying loads. Importantly, in the investigations, the author took into account the parameters calculated in the course of the investigations on a chassis dynamometer, i.e., actual, not taken from technical specifications of brand new vehicles. Di erent stages of operating wear allow a better characterization of the population. Subsequent utilization of the results in tractive calculations is more reliable. The engines were divided into in six groups, depending on the type of fuel system: fuel injected gasoline and turbocharged gasoline, spark ignition LPG, naturally aspirated diesel and turbocharged diesel. However, engines running on alternative fuels are characterized with a greater flexibility than the fuel injected base engines. Conformity of flexibility of fuel injected and LPG IV generation engines have been observed,which confirms the appropriateness of engine adaptation to alternative fueling. Gasoline engine supercharging allowed a reduction of the maximum engine speed of the maximum torque, which extends the range of analyzable speeds for flexibility and consequently, the flexibility as such.
文摘A Wireless Sensor Network(WSN)becomes a newer type of real-time embedded device that can be utilized for a wide range of applications that make regular networking which appears impracticable.Concerning the energy produc-tion of the nodes,WSN has major issues that may influence the stability of the system.As a result,constructing WSN requires devising protocols and standards that make the most use of constrained capacity,especially the energy resources.WSN faces some issues with increased power utilization and an on going devel-opment due to the uneven energy usage between the nodes.Clustering has proven to be a more effective strategy in this series.In the proposed work,a hybrid meth-od is used for reducing the energy consumption among CHs.A Fuzzy Logic-based clustering protocol FLUC(unequally clustered)and Fuzzy Clustering with Energy-Efficient Routing Protocol(FCERP)are used.A Fuzzy Clustering with Energy Efficient Routing Protocol(FCERP)reduces the WSN power usage and increases the lifespan of the network.FCERP has created a novel cluster-based fuzzy routing mechanism that uses a limit value to combine the clustering and multi-hop routing capabilities.The technique creates uneven groups by using fuz-zy logic with a competitive range to choose the Cluster Head(CH).The input variables include the distance of the nodes from the ground station,concentra-tions,and remaining energy.The proposed FLUC-FCERP reduces the power usage and improves the lifetime of the network compared with the existing algorithms.
文摘The Wireless Sensor Network(WSN)is a network of Sensor Nodes(SN)which adopt radio signals for communication amongst themselves.There is an increase in the prominence of WSN adaptability to emerging applications like the Internet of Things(IoT)and Cyber-Physical Systems(CPS).Data secur-ity,detection of faults,management of energy,collection and distribution of data,network protocol,network coverage,mobility of nodes,and network heterogene-ity are some of the issues confronted by WSNs.There is not much published information on issues related to node mobility and management of energy at the time of aggregation of data.Towards the goal of boosting the mobility-based WSNs’network performance and energy,data aggregation protocols such as the presently-used Mobility Low-Energy Adaptive Clustering Hierarchy(LEACH-M)and Energy Efficient Heterogeneous Clustered(EEHC)scheme have been exam-ined in this work.A novel Artificial Bee Colony(ABC)algorithm is proposed in this work for effective election of CHs and multipath routing in WSNs so as to enable effective data transfer to the Base Station(BS)with least energy utilization.There is avoidance of the local optima problem at the time of solution space search in this proposed technique.Experimentations have been conducted on a large WSN network that has issues with mobility of nodes.
文摘To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.
基金support of the National Natural Science Foundation of China(Grant No.51805371)the Innovation and Entrepreneurship Training Program of Tianjin University of Commerce(Grant No.202310069067).
文摘Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;however,achieving ultrahigh precision and ultralow damage machining of functional devices using traditional techniques such as grinding and polishing is extremely challenging.Consequently,nanocutting has emerged as an efficient means to fabricate monocrystalline materials with complex surface characteristics and high surface integrity.Nevertheless,the macroscopic cutting theory of metal materials cannot be applied to nanocutting.Accordingly,in this paper,both simulations and experiments were conducted to examine the chip deformation mechanisms of monocrystalline Cu.First,large-scale molecular dynamics(MD)simulations were conducted to gain a comprehensive understanding of the deformation behavior during nanocutting.This included examining the influencing factors and the variation patterns of the chip deformation coefficient,cutting force,and minimum cutting thickness.Subsequently,nanocutting experiments were performed using a specially designed nanocutting platform with high-resolution online observation by scanning electron microscopy.The experimental results served to verify the accuracy and reliability of theMDmodeling,as they exhibited excellent consistency with the simulated results.Although this work considered monocrystalline Cu,it is believed that the elucidated chip deformation mechanisms could also be applied to other face-centered-cubic metals.These results are of great value for advancing the understanding of the mechanisms of ultraprecision cutting.
文摘目的:探讨超声黏弹性成像技术在乳腺肿瘤良恶性鉴别中的应用价值。方法:连续纳入2023年2月至2023年8月期间,上海交通大学医学院附属瑞金医院收治的经手术病理证实为乳腺肿瘤的717例患者,其中471例为恶性,246例为良性。所有患者均在治疗前进行乳腺超声检查,包括灰阶超声、超声应变弹性成像、超声剪切波弹性成像、超声黏性成像。超声黏弹性成像技术包括测量肿瘤及其周围组织的黏性系数、频散系数和剪切波弹性模量、应变比等4组参数,以4组参数中的较佳预测指标,分别构建多种预测模型,包括黏性系数单变量模型、频散系数单变量模型、黏性组合模型(Shell/T-Vmean+Shell/T-Dmean)、剪切波单变量模型、应变单变量模型、乳腺影像报告和数据系统(Breast Imaging Reporting and Data System,BI-RADS)、BI-RADS联合黏性组合模型,评估每种模型在乳腺肿瘤良恶性鉴别中的效能。结果:超声黏弹性成像的黏性系数、频散系数、弹性模量及应变比等参数均可有效地区分乳腺良恶性肿瘤,其中肿瘤边缘2 mm区域与瘤体的参数比值Shell/T-Vmean、Shell/T-Dmean、Shell/T-Emean、Strain Ratio A为较佳预测指标,曲线下面积分别为0.742、0.745、0.726、0.705,而BI-RADS模型预测乳腺肿瘤良恶性的0.822。将Shell/T-Vmean、Shell/T-Dmean分别与BI-RADS分类联合时,受试者操作特征曲线的曲线下面积高达0.895(95%CI为0.868~0.917),高于BI-RADS。结论:超声黏弹性成像的黏弹性参数中,肿瘤边缘2 mm区域与瘤体的黏性系数、频散系数及弹性模量均值比为关键诊断指标;Shell/T-Vmean、Shell/T-Dmean联合BI-RADS后,可为术前无创精准诊断提供了新策略。
