Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two t...Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two typical HCP metals,zirconium,and titanium,were applied to reactive materials(RMs)to prepare Zr/PTFE/W RMs and Ti/PTFE/W RMs,validating the feasibility of HCP metal/PTFE/W RMs.The impact response process of typical HCP metal/PTFE/W RMs under high-velocity dynamic loads was studied using shock equations of state(EOS)based on porous mixtures and chemical reaction kinetics equations.An improved hemispherical quasi-sealed test chamber was employed to measure the energy release characteristic curves of 10 types of Zr/PTFE/W RMs and Ti/PTFE/W RMs under impact velocities ranging from 500 m/s to 1300 m/s.The datasets of the impact-induced energy release characteristics of HCP metal/PTFE/W RMs were established.Additionally,the energy release efficiency of HCP metal/PTFE/W RMs under impact was predicted using the support vector regression(SVR)kernel function model.The datasets of Zr/PTFE/W RMs and Ti/PTFE/W RMs with W contents of 0%,25%,50%,and 75%were used as test sets,respectively.The model predictions showed a high degree of agreement with the experimental data,with mean absolute errors(MAE)of 4.8,6.5,4.6,and 4.1,respectively.展开更多
为探讨固化硫酸盐渍土在冻融循环作用下的强度劣化机理,采用室内正交试验,考虑冻融循环周期、固化剂掺量、含盐量等影响因素,借助三轴试验、X射线衍射(diffraction of X-rays, XRD)衍射试验及电镜扫描试验。对粉煤灰、氯化钙固化硫酸盐...为探讨固化硫酸盐渍土在冻融循环作用下的强度劣化机理,采用室内正交试验,考虑冻融循环周期、固化剂掺量、含盐量等影响因素,借助三轴试验、X射线衍射(diffraction of X-rays, XRD)衍射试验及电镜扫描试验。对粉煤灰、氯化钙固化硫酸盐渍土在不同冻融循环周期作用下的强度劣化指标及微观结构演化规律进行了研究。结果表明:冻融循环作用对固化硫酸盐渍土强度劣化影响较大,且对黏聚力影响相较内摩擦角更显著;衍射分析表明固化效果越好,固化剂反应物的低矮峰越多,同时电镜扫描分析也表明:土体结构越紧密,强度更优;在处理盐渍土地基时,从抑制盐胀及提高土体耐久性效果来看,单掺氯化钙优于单掺粉煤灰,且复掺优于单掺。不同含盐量的最佳配合比:含盐量为2%时,10%粉煤灰+4%氯化钙;含盐量为5%时,10%粉煤灰+6%氯化钙;含盐量为8%时,15%的粉煤灰+6%的氯化钙。固化后土体的强度指标劣化程度较低。从微观角度出发对冻融循环下硫酸盐渍土的强度劣化进行研究,旨在为长期冻融的硫酸盐渍土提出理论依据,以减少不必要的经济损失。展开更多
A new method for image fusion based on Contourlet transform and cycle spinning is proposed. Contourlet transform is a flexible multiresolution, local and directional image expansion, also provids a sparse representati...A new method for image fusion based on Contourlet transform and cycle spinning is proposed. Contourlet transform is a flexible multiresolution, local and directional image expansion, also provids a sparse representation for two-dimensional piece-wise smooth signals resembling images. Due to lack of translation invariance property in Contourlet transform, the conventional image fusion algorithm based on Contourlet transform introduces many artifacts. According to the theory of cycle spinning applied to image denoising, an invariance transform can reduce the artifacts through a series of processing efficiently. So the technology of cycle spinning is introduced to develop the translation invariant Contourlet fusion algorithm. This method can effectively eliminate the Gibbs-like phenomenon, extract the characteristics of original images, and preserve more important information. Experimental results show the simplicity and effectiveness of the method and its advantages over the conventional approaches.展开更多
A new fault tolerant control（FTC） via a controller reconfiguration approach for general stochastic nonlinear systems is studied.Different from the formulation of classical FTC methods,it is supposed that the measure...A new fault tolerant control（FTC） via a controller reconfiguration approach for general stochastic nonlinear systems is studied.Different from the formulation of classical FTC methods,it is supposed that the measured information for the FTC is the probability density functions（PDFs） of the system output rather than its measured value.A radial basis functions（RBFs） neural network technique is proposed so that the output PDFs can be formulated in terms of the dynamic weighings of the RBFs neural network.As a result,the nonlinear FTC problem subject to dynamic relation between the input and the output PDFs can be transformed into a nonlinear FTC problem subject to dynamic relation between the control input and the weights of the RBFs neural network approximation to the output PDFs.The FTC design consists of two steps.The first step is fault detection and diagnosis（FDD）,which can produce an alarm when there is a fault in the system and also locate which component has a fault.The second step is to adapt the controller to the faulty case so that the system is able to achieve its target.A linear matrix inequality（LMI） based feasible FTC method is applied such that the fault can be detected and diagnosed.An illustrated example is included to demonstrate the efficiency of the proposed algorithm,and satisfactory results have been obtained.展开更多
In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive effectiveness.As a new type of reactive material,r...In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive effectiveness.As a new type of reactive material,reactive alloy contains a large portion of reactive metal elements(Al,Mg,Ti,Zr,etc.),which breaks up under high-velocity impact conditions,generating a large number of high-temperature combustible fragments,which undergo a violent combustion reaction with air.Compared with traditional metal polymers(Al-PTFE)and other reactive composites,it has higher density and strength,excellent mechanical properties and broader application prospects.Currently,researchers have mainly investigated the impact energy release mechanism of reactive alloys through impact tests,and found that there are several important stages in the process of the material from fragmentation to reaction,i.e.,impact fragmentation of the material,rapid heating and combustion reaction.This paper focuses on three problems that need to be solved in the impact-induced energy release process of reactive alloys,namely:the fragmentation mechanism and size distribution law of the fragments produced by the impact of the material on the target,the relationship between the transient temperatures and the size of the fragments,and the reaction temperatures and size thresholds of the fragments to undergo the chemical reaction.The current status of the research of the above problems is reviewed,some potential directions to reveal the impact induced reaction mechanism of reactive alloy is discussed.展开更多
The fault diagnosis problem is investigated for a class of nonlinear neutral systems with multiple disturbances.Time-varying faults are considered and multiple disturbances are supposed to include the unknown disturba...The fault diagnosis problem is investigated for a class of nonlinear neutral systems with multiple disturbances.Time-varying faults are considered and multiple disturbances are supposed to include the unknown disturbance modeled by an exo-system and norm bounded uncertain disturbance.A nonlinear disturbance observer is designed to estimate the modeled disturbance.Then,the fault diagnosis observer is constructed by integrating disturbance observer with disturbance attenuation and rejection performances.The augmented Lyapunov functional approach,which involves the tuning parameter and slack variable,is applied to make the solution of inequality more flexible.Finally,applications for a two-link robotic manipulator system are given to show the efficiency of the proposed approach.展开更多
OBJECTIVE To investigate the beneficial effect of berberine(BBR)on atherosclerosisin Apo^(-/-) E mice and explore the underlying mechanisms based on attenuating vascular inflammation and modulating calcification in hu...OBJECTIVE To investigate the beneficial effect of berberine(BBR)on atherosclerosisin Apo^(-/-) E mice and explore the underlying mechanisms based on attenuating vascular inflammation and modulating calcification in human umbilical vein endothelial cells(HUVECs) and smooth muscle cells(SMCs).METHODS 48 Apo-/-E mice,at 6-8 weeks old,were randomly allocated into 4 groups:normal,model,bbr and atorvastatin(positive control) groups with 12 mice in each group.They were fed with high-fat diet for 4 weeks except those in Normal group and then treated with indicated drugs orsolvent for another 4 weeks.The morphology and inflammation infiltration of aortic were examined with HE staining.The expression of BMP-2 in aortic was examined by immumohistochemical staining.Blood lipid levels were examined by automatic biochemical analyzer.The expression of IL-6,TNF-α and BMP-2 in serum and tissues was detected by ELISA method.The expression of ALP and the content of calcium were detected by commercially-available kits.HUVEC cells were stimulated with TNF-α and incubated with various concentrations of BBR for 24 h.The contents of intercellular cell adhesion molecule-1(ICAM-1),vascular cell adhesion molecule(VCAM-1),matrix metalloprotein-9(MMP-9) in the culture supernatant were detected by ELISA method.Calcification was induced with β-glycerophosphatein SMC cells and the effect of BBR on the content of calcium was examined.RESULTS 4-week berberine treatment markedly lowered serum TC and LDL-c levels and improved the plaque stability in Apo-/-E mice fed with a high-fat diet(P<0.05 or P<0.01) which was comparable with the effect of atorvastatin.Berberineal so significantly decreased the levels of IL-6 and TNF-α in mice serum and aortic tissues(P<0.05 or P<0.001).Berberine tended to decrease ALP,BMP-2 levels and the content of calcium in mice serum and aortic tissues(P<0.05,P<0.01 or P<0.001) which were not observed in atorvastatin group.Berberine significantly lowered the levels of ICAM-1,VCAM-1,and MMP-9 in TNF-α-stimulated HUVECs.It can also lowered the content of calcium in SMCs.CONCLUSION BBR can profitably regulate the levels of blood lipid in mice fed with a high-fat diet,decrease the injury caused by inflammation,and attenuate vascular calcification.It may improve atherosclerosis and play a role in cardiovascular protection.展开更多
OBJECTIVE To evaluate whether the IDO1 inhibitor 1-methyl-L-tryptophan(1-MT)combine calcium influx inhibitor carboxyamidotriazole(CAI)could further enhance the suppression of programmed death 1(PD-1)in CD8^+T cells an...OBJECTIVE To evaluate whether the IDO1 inhibitor 1-methyl-L-tryptophan(1-MT)combine calcium influx inhibitor carboxyamidotriazole(CAI)could further enhance the suppression of programmed death 1(PD-1)in CD8^+T cells and investigate the curative effect of the combined use.METHODS CD8^+T cells were isolated from normal mice spleen by negative selection using magnetic cell separation.The isolated CD8^+T cells were cultured in RPMI 1640 medium containing 10%FBS and 100 U·mL^(-1)IL-2 and activated by the addition of anti-CD3 and anti-CD28(1 g·L^(-1) each mabs).CD8^+T cells were pretreated for 48 h with drug and the fluo-3 as a marker of intracellular calcium concentration was detected by flow cytometry.The calcineurin(Ca N)levels were assayed with ELISA in CD8^+T cells after 48 h incubation with 10μm CAI.The nuclear translocations of NFAT and AHR were detected by immunofluorescent staining after 48 h of drug treatment.The expression of PD-1 in CD8^+T cells was analyzed by flow cytometry.RESULTS Intracellular fluorescent intensity was markedly debase due to CAI treatment(P<0.01).Meanwhile,the changes of CaN content had a resembled correlation(P<0.01).Immunofluorescence experiment showed that after combination therapy the transfer of NFAT and AHR in nuclear substantially reduced.Flow cytometry revealed that after the combination caused a significant decrease in PD-1 expression in CD8^+T cells.CONCLUSION CAI and 1-MT could inhibit markedly the expression of PD-1 in CD8^+T cells by inhibiting the nuclear translocation of NFAT and AHR,respectively and the combination of them has synergetic effect.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant Nos.U2241285,62201267)。
文摘Zirconium,titanium,and other hexagonally close-packed(HCP)metals and their alloys are representative high specific strength,high reaction enthalpy,and high thermal conductivity structural materials.In this study,two typical HCP metals,zirconium,and titanium,were applied to reactive materials(RMs)to prepare Zr/PTFE/W RMs and Ti/PTFE/W RMs,validating the feasibility of HCP metal/PTFE/W RMs.The impact response process of typical HCP metal/PTFE/W RMs under high-velocity dynamic loads was studied using shock equations of state(EOS)based on porous mixtures and chemical reaction kinetics equations.An improved hemispherical quasi-sealed test chamber was employed to measure the energy release characteristic curves of 10 types of Zr/PTFE/W RMs and Ti/PTFE/W RMs under impact velocities ranging from 500 m/s to 1300 m/s.The datasets of the impact-induced energy release characteristics of HCP metal/PTFE/W RMs were established.Additionally,the energy release efficiency of HCP metal/PTFE/W RMs under impact was predicted using the support vector regression(SVR)kernel function model.The datasets of Zr/PTFE/W RMs and Ti/PTFE/W RMs with W contents of 0%,25%,50%,and 75%were used as test sets,respectively.The model predictions showed a high degree of agreement with the experimental data,with mean absolute errors(MAE)of 4.8,6.5,4.6,and 4.1,respectively.
文摘为探讨固化硫酸盐渍土在冻融循环作用下的强度劣化机理,采用室内正交试验,考虑冻融循环周期、固化剂掺量、含盐量等影响因素,借助三轴试验、X射线衍射(diffraction of X-rays, XRD)衍射试验及电镜扫描试验。对粉煤灰、氯化钙固化硫酸盐渍土在不同冻融循环周期作用下的强度劣化指标及微观结构演化规律进行了研究。结果表明:冻融循环作用对固化硫酸盐渍土强度劣化影响较大,且对黏聚力影响相较内摩擦角更显著;衍射分析表明固化效果越好,固化剂反应物的低矮峰越多,同时电镜扫描分析也表明:土体结构越紧密,强度更优;在处理盐渍土地基时,从抑制盐胀及提高土体耐久性效果来看,单掺氯化钙优于单掺粉煤灰,且复掺优于单掺。不同含盐量的最佳配合比:含盐量为2%时,10%粉煤灰+4%氯化钙;含盐量为5%时,10%粉煤灰+6%氯化钙;含盐量为8%时,15%的粉煤灰+6%的氯化钙。固化后土体的强度指标劣化程度较低。从微观角度出发对冻融循环下硫酸盐渍土的强度劣化进行研究,旨在为长期冻融的硫酸盐渍土提出理论依据,以减少不必要的经济损失。
基金supported by the National Natural Science Foundation of China (60802084)
文摘A new method for image fusion based on Contourlet transform and cycle spinning is proposed. Contourlet transform is a flexible multiresolution, local and directional image expansion, also provids a sparse representation for two-dimensional piece-wise smooth signals resembling images. Due to lack of translation invariance property in Contourlet transform, the conventional image fusion algorithm based on Contourlet transform introduces many artifacts. According to the theory of cycle spinning applied to image denoising, an invariance transform can reduce the artifacts through a series of processing efficiently. So the technology of cycle spinning is introduced to develop the translation invariant Contourlet fusion algorithm. This method can effectively eliminate the Gibbs-like phenomenon, extract the characteristics of original images, and preserve more important information. Experimental results show the simplicity and effectiveness of the method and its advantages over the conventional approaches.
基金supported by the UK Leverhulme Trust (F/00 120/BC)the National Natural Science Foundation of China (6082800760974029)
文摘A new fault tolerant control（FTC） via a controller reconfiguration approach for general stochastic nonlinear systems is studied.Different from the formulation of classical FTC methods,it is supposed that the measured information for the FTC is the probability density functions（PDFs） of the system output rather than its measured value.A radial basis functions（RBFs） neural network technique is proposed so that the output PDFs can be formulated in terms of the dynamic weighings of the RBFs neural network.As a result,the nonlinear FTC problem subject to dynamic relation between the input and the output PDFs can be transformed into a nonlinear FTC problem subject to dynamic relation between the control input and the weights of the RBFs neural network approximation to the output PDFs.The FTC design consists of two steps.The first step is fault detection and diagnosis（FDD）,which can produce an alarm when there is a fault in the system and also locate which component has a fault.The second step is to adapt the controller to the faulty case so that the system is able to achieve its target.A linear matrix inequality（LMI） based feasible FTC method is applied such that the fault can be detected and diagnosed.An illustrated example is included to demonstrate the efficiency of the proposed algorithm,and satisfactory results have been obtained.
文摘In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive effectiveness.As a new type of reactive material,reactive alloy contains a large portion of reactive metal elements(Al,Mg,Ti,Zr,etc.),which breaks up under high-velocity impact conditions,generating a large number of high-temperature combustible fragments,which undergo a violent combustion reaction with air.Compared with traditional metal polymers(Al-PTFE)and other reactive composites,it has higher density and strength,excellent mechanical properties and broader application prospects.Currently,researchers have mainly investigated the impact energy release mechanism of reactive alloys through impact tests,and found that there are several important stages in the process of the material from fragmentation to reaction,i.e.,impact fragmentation of the material,rapid heating and combustion reaction.This paper focuses on three problems that need to be solved in the impact-induced energy release process of reactive alloys,namely:the fragmentation mechanism and size distribution law of the fragments produced by the impact of the material on the target,the relationship between the transient temperatures and the size of the fragments,and the reaction temperatures and size thresholds of the fragments to undergo the chemical reaction.The current status of the research of the above problems is reviewed,some potential directions to reveal the impact induced reaction mechanism of reactive alloy is discussed.
基金supported by the National Natural Science Foundation of China(6077401360925012)+1 种基金the National High Technology Research and Development Program of China(863 Program) (2008AA12A216)the National Basic Research Program of China (973 Program)(2009CB 724002)
文摘The fault diagnosis problem is investigated for a class of nonlinear neutral systems with multiple disturbances.Time-varying faults are considered and multiple disturbances are supposed to include the unknown disturbance modeled by an exo-system and norm bounded uncertain disturbance.A nonlinear disturbance observer is designed to estimate the modeled disturbance.Then,the fault diagnosis observer is constructed by integrating disturbance observer with disturbance attenuation and rejection performances.The augmented Lyapunov functional approach,which involves the tuning parameter and slack variable,is applied to make the solution of inequality more flexible.Finally,applications for a two-link robotic manipulator system are given to show the efficiency of the proposed approach.
基金supported by National Science Foundation of China(81402943)CAMS Major Collaborative Innovation Project(2016-I2M-1-011)PUMC Youth Fund(3332015168)
文摘OBJECTIVE To investigate the beneficial effect of berberine(BBR)on atherosclerosisin Apo^(-/-) E mice and explore the underlying mechanisms based on attenuating vascular inflammation and modulating calcification in human umbilical vein endothelial cells(HUVECs) and smooth muscle cells(SMCs).METHODS 48 Apo-/-E mice,at 6-8 weeks old,were randomly allocated into 4 groups:normal,model,bbr and atorvastatin(positive control) groups with 12 mice in each group.They were fed with high-fat diet for 4 weeks except those in Normal group and then treated with indicated drugs orsolvent for another 4 weeks.The morphology and inflammation infiltration of aortic were examined with HE staining.The expression of BMP-2 in aortic was examined by immumohistochemical staining.Blood lipid levels were examined by automatic biochemical analyzer.The expression of IL-6,TNF-α and BMP-2 in serum and tissues was detected by ELISA method.The expression of ALP and the content of calcium were detected by commercially-available kits.HUVEC cells were stimulated with TNF-α and incubated with various concentrations of BBR for 24 h.The contents of intercellular cell adhesion molecule-1(ICAM-1),vascular cell adhesion molecule(VCAM-1),matrix metalloprotein-9(MMP-9) in the culture supernatant were detected by ELISA method.Calcification was induced with β-glycerophosphatein SMC cells and the effect of BBR on the content of calcium was examined.RESULTS 4-week berberine treatment markedly lowered serum TC and LDL-c levels and improved the plaque stability in Apo-/-E mice fed with a high-fat diet(P<0.05 or P<0.01) which was comparable with the effect of atorvastatin.Berberineal so significantly decreased the levels of IL-6 and TNF-α in mice serum and aortic tissues(P<0.05 or P<0.001).Berberine tended to decrease ALP,BMP-2 levels and the content of calcium in mice serum and aortic tissues(P<0.05,P<0.01 or P<0.001) which were not observed in atorvastatin group.Berberine significantly lowered the levels of ICAM-1,VCAM-1,and MMP-9 in TNF-α-stimulated HUVECs.It can also lowered the content of calcium in SMCs.CONCLUSION BBR can profitably regulate the levels of blood lipid in mice fed with a high-fat diet,decrease the injury caused by inflammation,and attenuate vascular calcification.It may improve atherosclerosis and play a role in cardiovascular protection.
基金supported by National Natural Science Foundation of China(81402943)CAMS Major Collaborative Innovation Project(2016-I2M-1-011)PUMC Youth Fund(3332015168)
文摘OBJECTIVE To evaluate whether the IDO1 inhibitor 1-methyl-L-tryptophan(1-MT)combine calcium influx inhibitor carboxyamidotriazole(CAI)could further enhance the suppression of programmed death 1(PD-1)in CD8^+T cells and investigate the curative effect of the combined use.METHODS CD8^+T cells were isolated from normal mice spleen by negative selection using magnetic cell separation.The isolated CD8^+T cells were cultured in RPMI 1640 medium containing 10%FBS and 100 U·mL^(-1)IL-2 and activated by the addition of anti-CD3 and anti-CD28(1 g·L^(-1) each mabs).CD8^+T cells were pretreated for 48 h with drug and the fluo-3 as a marker of intracellular calcium concentration was detected by flow cytometry.The calcineurin(Ca N)levels were assayed with ELISA in CD8^+T cells after 48 h incubation with 10μm CAI.The nuclear translocations of NFAT and AHR were detected by immunofluorescent staining after 48 h of drug treatment.The expression of PD-1 in CD8^+T cells was analyzed by flow cytometry.RESULTS Intracellular fluorescent intensity was markedly debase due to CAI treatment(P<0.01).Meanwhile,the changes of CaN content had a resembled correlation(P<0.01).Immunofluorescence experiment showed that after combination therapy the transfer of NFAT and AHR in nuclear substantially reduced.Flow cytometry revealed that after the combination caused a significant decrease in PD-1 expression in CD8^+T cells.CONCLUSION CAI and 1-MT could inhibit markedly the expression of PD-1 in CD8^+T cells by inhibiting the nuclear translocation of NFAT and AHR,respectively and the combination of them has synergetic effect.
