Based on the analysis of monitoring data on six pollution indexes of SO2, NO2, CO, O3, PM10 and PM2.5 from 53 monitoring points in 7 cities, including Beijing, Tianjin, Shijiazhuang, etc., from April 8 of 2014 to July...Based on the analysis of monitoring data on six pollution indexes of SO2, NO2, CO, O3, PM10 and PM2.5 from 53 monitoring points in 7 cities, including Beijing, Tianjin, Shijiazhuang, etc., from April 8 of 2014 to July 23 of 2014, this article adopted Pearson correlation coefficient method to determine the relevance among each pollutant of these cities with the help of SPSS. The results showed that such three leading indexes as SO2, PM10 and PM2.5 had strong correlation in Beijing, Tianjin and main cities of Hebei. Finally, some suggestions and preventive measures for the cooperative governance of air pollution in Beijing-Tianjin-Hebei Region were put forward, hoping this can help them.展开更多
The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two mai...The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.展开更多
By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using rese...By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth.展开更多
[Objective] Taking the characteristic of flower diameter of Tagetes L.as an example,this study aimed to select example varieties used in the DUS Test Guideline of Tagetes L.[Method] Two continuous years of measurement...[Objective] Taking the characteristic of flower diameter of Tagetes L.as an example,this study aimed to select example varieties used in the DUS Test Guideline of Tagetes L.[Method] Two continuous years of measurements of flower diameter of 25 varieties were collected and then analyzed by using the box plot to illustrate the uniformity and stability of flower diameter of each variety.[Result] According to the information of variability,distribution symmetry of measurements and outliers of flower diameter of varieties provided by box plots,variety 16,2 and 4 were selected as the example varieties for the three expression states with respective flower diameter of 3.0-4.4,6.0-7.4 and 9.0-10.4 cm.[Conclusion] The box plot is an efficient method for the general analysis of varieties,which provides information covering the actual and possible expression range,median and outliers of measurements of flower diameter of each variety.It also provides references for selecting example varieties for other quantitative characteristics and evaluating the quality of varieties.展开更多
To determine the effect of agricultural management on the dynamics and functional diversity of soil nematode communities in a carrot field at Kibbutz Ramat Hakovesh, Israel, soil samples from 0-10 cm and 10-20 cm dept...To determine the effect of agricultural management on the dynamics and functional diversity of soil nematode communities in a carrot field at Kibbutz Ramat Hakovesh, Israel, soil samples from 0-10 cm and 10-20 cm depths were collected during the growing season of carrot. Indices were used to compare and assess the response of soil free-living nernatode communities to agricultural management. Eighteen nematode families and 20 genera were observed during the growing period, with Cephalobus, Rhabditidae, Aphelenchus, Tylenchus, and Dorylaimus being the dominant genera/families. During the planting, mid-season and post-harvest periods the total number of nematodes at both depths was significantly lower (P < 0.01) in the carrot treatment than in the control plots, while during the harvest period at both depths total nematodes and bacterivores were significantly higher in the treatment plots (P < 0.01). The values of the maturity index (MI) at both depths were found to be significantly lower in the treatment plots than in the control plots during the pre-planting period (P < 0.05). Overall, WI, MI and PPI were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to agricultural management in a Mediterranean agroecosystem展开更多
Nematode communities were monitored in a field study at depths of 0～10 cmand 10～20 cm throughout a corn (Zea mays L.) growing season in the black soil region of NortheastChina. Plots were cropped corn with (IF) and ...Nematode communities were monitored in a field study at depths of 0～10 cmand 10～20 cm throughout a corn (Zea mays L.) growing season in the black soil region of NortheastChina. Plots were cropped corn with (IF) and without (NF) nitrogen fertilization. Fifteen familiesand 16 genera were observed in the nematode suspensions. Cephalobidae, Rhabditidae, Aphelenchus,Filenchus, and Helicotylenchus were found to be dominant genera/families in both plots at bothdepths. Significant differences were found between treatments and corn growing stages in the totalnumbers of nematodes during the study period. The total numbers of nematodes at the 0～10 cm depthwere higher in the inorganic fertilizer plot than in the control plot (no fertilizer applications)across jointing, filling, and mature stages. Bacterivores were the most abundant trophic groupsunder two treatments and at both depths, and the relative abundance averaged 42.8%.Omuivores-predators at both depths were lower in the inorganic fertilizer plot than in the controlplot during the study period, excluding corn jointing stage. Maturity index (MI) and plant parasiteindex (PPI) were used to detect the differences between the two treatments, MI and PPI wereeffective in distinguishing differences in nematode communities during corn growing season. The roleof nematode communities as bioindicators of ecosystem disturbance due to fertilization is noted.展开更多
To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous comb...To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.展开更多
This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model,which is the interconnection of a linear delayed dynamic syste...This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model,which is the interconnection of a linear delayed dynamic system and a bounded static nonlinear operator,and covers several well-known neural networks,such as Hopfield neural networks,cellular neural networks(CNNs),bidirectional associative memory(BAM)networks,recurrent multilayer perceptrons(RMLPs).By virtue of Lyapunov-Krasovskii stability theory and linear matrix inequality(LMI)technique,some exponential synchronization criteria are derived.Using the drive-response concept,hybrid feedback controllers are designed to synchronize two identical chaotic neural networks based on those synchronization criteria.Finally,detailed comparisons with existing results are made and numerical simulations are carried out to demonstrate the effectiveness of the established synchronization laws.展开更多
AIM:To investigate the diagnostic accuracy of acoustic radiation force impulse (ARFI) imaging as a noninvasive method for the assessment of liver fibrosis in chronic hepatitis C (CHC) patients.METHODS:We performed a p...AIM:To investigate the diagnostic accuracy of acoustic radiation force impulse (ARFI) imaging as a noninvasive method for the assessment of liver fibrosis in chronic hepatitis C (CHC) patients.METHODS:We performed a prospective blind com-parison of ARFI elastography,APRI index and FibroMax in a consecutive series of patients who underwent liver biopsy for CHC in University Hospital Bucharest. His-topathological staging of liver fibrosis according to the METAVIR scoring system served as the reference. A to-tal of 74 patients underwent ARFI elastography,APRI index,FibroMax and successful liver biopsy. RESULTS:The noninvasive tests had a good correlation with the liver biopsy results. The most powerful test in predicting fibrosis was ARFI elastography. The diagnostic accuracy of ARFI elastography,expressedas area under receiver operating characteristic curve (AUROC) had a validity of 90.2% (95% CI AUROC = 0.831-0.972,P < 0.001) for the diagnosis of significant f ibrosis (F ≥ 2). ARFI sonoelastography predicted even better F3 or F4 fibrosis (AUROC = 0.993,95% CI = 0.979-1).CONCLUSION:ARFI elastography had very good accuracy for the assessment of liver fibrosis and was superior to other noninvasive methods (APRI Index,FibroMax) for staging liver fibrosis.展开更多
There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from th...There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.展开更多
Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a goo...Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.展开更多
The quasi-biweekly oscillation (QBWO) is a major intraseasonal variability (ISV) in the tropics. Based on bandpass-filtered outgoing longwave radiation (OLR) and wind field data, the predictability limits of the QBWO ...The quasi-biweekly oscillation (QBWO) is a major intraseasonal variability (ISV) in the tropics. Based on bandpass-filtered outgoing longwave radiation (OLR) and wind field data, the predictability limits of the QBWO in boreal summer and boreal winter are investigated using the nonlinear local Lyapunov exponent (NLLE) approach The analysis shows that the evolution of the mean error growth of the QBWO in boreal summer and the evolution of the mean error growth in boreal winter are comparable Both curves exhibit rapid growth in the initial stage followed by a slowly fluctuating, ascending trend before saturation is reached. As a result, the potential predictability limits for the boreal summer QBWO are very close to those for the boreal winter QBWO, with a lead time of approximately three weeks. Given the current limitations in the simulation and prediction of ISV, including the QBWO, the results of this study provide a useful reference for assessing the predictability of the QBWO using model simulations.展开更多
文摘Based on the analysis of monitoring data on six pollution indexes of SO2, NO2, CO, O3, PM10 and PM2.5 from 53 monitoring points in 7 cities, including Beijing, Tianjin, Shijiazhuang, etc., from April 8 of 2014 to July 23 of 2014, this article adopted Pearson correlation coefficient method to determine the relevance among each pollutant of these cities with the help of SPSS. The results showed that such three leading indexes as SO2, PM10 and PM2.5 had strong correlation in Beijing, Tianjin and main cities of Hebei. Finally, some suggestions and preventive measures for the cooperative governance of air pollution in Beijing-Tianjin-Hebei Region were put forward, hoping this can help them.
基金Supported by National Science and Technology Support Plan during the Eleventh Five-year Plan(2006BAD01A08-02)Hubei Agricultural Innovation Program(2007-620-004-003)Special Fund for Modern Pig Production Technology Construction(NYCYTX-009)~~
文摘The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.
文摘By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest(200903008-14)the National "948" Project(2009-Z11)~~
文摘[Objective] Taking the characteristic of flower diameter of Tagetes L.as an example,this study aimed to select example varieties used in the DUS Test Guideline of Tagetes L.[Method] Two continuous years of measurements of flower diameter of 25 varieties were collected and then analyzed by using the box plot to illustrate the uniformity and stability of flower diameter of each variety.[Result] According to the information of variability,distribution symmetry of measurements and outliers of flower diameter of varieties provided by box plots,variety 16,2 and 4 were selected as the example varieties for the three expression states with respective flower diameter of 3.0-4.4,6.0-7.4 and 9.0-10.4 cm.[Conclusion] The box plot is an efficient method for the general analysis of varieties,which provides information covering the actual and possible expression range,median and outliers of measurements of flower diameter of each variety.It also provides references for selecting example varieties for other quantitative characteristics and evaluating the quality of varieties.
基金Project partly supported by the Fred and Barbara Kort Sino-Israel Postdoctoral Fellowship
文摘To determine the effect of agricultural management on the dynamics and functional diversity of soil nematode communities in a carrot field at Kibbutz Ramat Hakovesh, Israel, soil samples from 0-10 cm and 10-20 cm depths were collected during the growing season of carrot. Indices were used to compare and assess the response of soil free-living nernatode communities to agricultural management. Eighteen nematode families and 20 genera were observed during the growing period, with Cephalobus, Rhabditidae, Aphelenchus, Tylenchus, and Dorylaimus being the dominant genera/families. During the planting, mid-season and post-harvest periods the total number of nematodes at both depths was significantly lower (P < 0.01) in the carrot treatment than in the control plots, while during the harvest period at both depths total nematodes and bacterivores were significantly higher in the treatment plots (P < 0.01). The values of the maturity index (MI) at both depths were found to be significantly lower in the treatment plots than in the control plots during the pre-planting period (P < 0.05). Overall, WI, MI and PPI were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to agricultural management in a Mediterranean agroecosystem
基金the National Key Basic Research Support Foundation(NKBRSF)of China(G1999011804-04) the Foundation of Knowledge Innovation Program of IAE-CAS(Institute of Applied Ecology,the Chinese Academy of Science).
文摘Nematode communities were monitored in a field study at depths of 0～10 cmand 10～20 cm throughout a corn (Zea mays L.) growing season in the black soil region of NortheastChina. Plots were cropped corn with (IF) and without (NF) nitrogen fertilization. Fifteen familiesand 16 genera were observed in the nematode suspensions. Cephalobidae, Rhabditidae, Aphelenchus,Filenchus, and Helicotylenchus were found to be dominant genera/families in both plots at bothdepths. Significant differences were found between treatments and corn growing stages in the totalnumbers of nematodes during the study period. The total numbers of nematodes at the 0～10 cm depthwere higher in the inorganic fertilizer plot than in the control plot (no fertilizer applications)across jointing, filling, and mature stages. Bacterivores were the most abundant trophic groupsunder two treatments and at both depths, and the relative abundance averaged 42.8%.Omuivores-predators at both depths were lower in the inorganic fertilizer plot than in the controlplot during the study period, excluding corn jointing stage. Maturity index (MI) and plant parasiteindex (PPI) were used to detect the differences between the two treatments, MI and PPI wereeffective in distinguishing differences in nematode communities during corn growing season. The roleof nematode communities as bioindicators of ecosystem disturbance due to fertilization is noted.
基金Projects(51304238,51534008)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.
基金Project supported in part by the National Natural Science Foundationof China (No. 60504024)the Specialized Research Fund for theDoctoral Program of Higher Education,China (No. 20060335022)+1 种基金theNatural Science Foundation of Zhejiang Province (No. Y106010),China the "151 Talent Project" of Zhejiang Province (Nos.05-3-1013 and 06-2-034),China
文摘This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model,which is the interconnection of a linear delayed dynamic system and a bounded static nonlinear operator,and covers several well-known neural networks,such as Hopfield neural networks,cellular neural networks(CNNs),bidirectional associative memory(BAM)networks,recurrent multilayer perceptrons(RMLPs).By virtue of Lyapunov-Krasovskii stability theory and linear matrix inequality(LMI)technique,some exponential synchronization criteria are derived.Using the drive-response concept,hybrid feedback controllers are designed to synchronize two identical chaotic neural networks based on those synchronization criteria.Finally,detailed comparisons with existing results are made and numerical simulations are carried out to demonstrate the effectiveness of the established synchronization laws.
基金Supported by Grant 41066/2007, financed by the Ministry of Education and Research
文摘AIM:To investigate the diagnostic accuracy of acoustic radiation force impulse (ARFI) imaging as a noninvasive method for the assessment of liver fibrosis in chronic hepatitis C (CHC) patients.METHODS:We performed a prospective blind com-parison of ARFI elastography,APRI index and FibroMax in a consecutive series of patients who underwent liver biopsy for CHC in University Hospital Bucharest. His-topathological staging of liver fibrosis according to the METAVIR scoring system served as the reference. A to-tal of 74 patients underwent ARFI elastography,APRI index,FibroMax and successful liver biopsy. RESULTS:The noninvasive tests had a good correlation with the liver biopsy results. The most powerful test in predicting fibrosis was ARFI elastography. The diagnostic accuracy of ARFI elastography,expressedas area under receiver operating characteristic curve (AUROC) had a validity of 90.2% (95% CI AUROC = 0.831-0.972,P < 0.001) for the diagnosis of significant f ibrosis (F ≥ 2). ARFI sonoelastography predicted even better F3 or F4 fibrosis (AUROC = 0.993,95% CI = 0.979-1).CONCLUSION:ARFI elastography had very good accuracy for the assessment of liver fibrosis and was superior to other noninvasive methods (APRI Index,FibroMax) for staging liver fibrosis.
基金Project supported by the National Natural Science Foundation of China (No. 30472139)the Education Commission for the First Batch of Excellent Young Teachers in Universities of Chongqing City, China
文摘There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.
基金Project （51171125） supported by the National Natural Science Foundation of China Project （20110321051 ） supported by the Science and Technology Key Project of Shanxi Province, China
文摘Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.
基金funded by the National Natural Science Foundation of China (41175069)the National Basic Research Program of China (973 program, 2010CB950400)
文摘The quasi-biweekly oscillation (QBWO) is a major intraseasonal variability (ISV) in the tropics. Based on bandpass-filtered outgoing longwave radiation (OLR) and wind field data, the predictability limits of the QBWO in boreal summer and boreal winter are investigated using the nonlinear local Lyapunov exponent (NLLE) approach The analysis shows that the evolution of the mean error growth of the QBWO in boreal summer and the evolution of the mean error growth in boreal winter are comparable Both curves exhibit rapid growth in the initial stage followed by a slowly fluctuating, ascending trend before saturation is reached. As a result, the potential predictability limits for the boreal summer QBWO are very close to those for the boreal winter QBWO, with a lead time of approximately three weeks. Given the current limitations in the simulation and prediction of ISV, including the QBWO, the results of this study provide a useful reference for assessing the predictability of the QBWO using model simulations.
