Polyacrylonitrile （PAN）, PAN/cellulose acetate （CA）, and PAN/CA-Ag based activated carbon nanofiber （ACNF） were prepared using electrostatic spinning and further heat treatment. Thermogravimetrylifferential scan...Polyacrylonitrile （PAN）, PAN/cellulose acetate （CA）, and PAN/CA-Ag based activated carbon nanofiber （ACNF） were prepared using electrostatic spinning and further heat treatment. Thermogravimetrylifferential scanning calorimetry （TG-DSC） analysis indicated that the addition of CA or Ag did not have a significant impact on the thermal decomposition of PAN materials but the yields of fibers could be improved. Scanning electron microscopy （SEM） analysis showed that the micromorphologies of produced fibers were greatly influenced by the viscosity and conductivity of precursor solutions. Fourier transform infrared spectroscopy （FT-IR） analysis proved that a cyclized or trapezoidal structure could form and the carbon scaffold composed of C=C bonds appeared in the PAN-based ACNFs. The characteristic dif- fraction peaks in X-ray diffraction （XRD） spectra were the evidence of a turbostratic structure and silver existed in the PAN/CA-Ag based ACNF. Brurmer-Emmett-Teller （BET） analysis showed that the doping of CA and Ag increased surface area and micropore volume of fi- bers; particularly, PAN/CA-Ag based ACNF exhibited the best porosity feature. Furthermore, SO2 adsorption experiments indicated that all the three fibers had good adsorption effects on lower concentrations of SO2 at room temperature; especially, the PAN/CA-Ag based ACNF showed the best adsorption performance, and it may be one of the most promising adsorbents used in the fields of chemical industry and en- vironment protection.展开更多
KMV model is one of the most important credit risk evaluation models in the world. It uses B-S option pricing and Morton formula based on the market value and volatility of the company’s equity, debt maturities, risk...KMV model is one of the most important credit risk evaluation models in the world. It uses B-S option pricing and Morton formula based on the market value and volatility of the company’s equity, debt maturities, risk-free interest rates and the book value of liabilities to estimate the market value of the company’s assets and the volatility of the asset value. In this paper, based on the theory of KMV model, we can derive the listed company’s default rate, and assess credit risk. And the result is reasonable.展开更多
This article aims to discuss the strike two-dimensional wind vector on geostationary satellite imageries. The magnitude and direction of the wind vector are decided by the moving speed of the clouds. First, based on t...This article aims to discuss the strike two-dimensional wind vector on geostationary satellite imageries. The magnitude and direction of the wind vector are decided by the moving speed of the clouds. First, based on the features of the cloud map, we extract the characteristics of clouds and establish matching model for the clouds image. Maximum correlation coefficient between the target modules and tracking module is obtained by using infrared brightness temperature cross-correlation coefficient method. Then, the beginning and end of the wind vector can be ascertained. Using the spherical triangles of the law of cosines, we determine the magnitude and direction of the wind vector.展开更多
Project scheduling problem is mainly to determine the schedule of allocating resources in order to balance the total cost and the completion time. This paper chiefly uses chance theory to introduce project scheduling ...Project scheduling problem is mainly to determine the schedule of allocating resources in order to balance the total cost and the completion time. This paper chiefly uses chance theory to introduce project scheduling problem with uncertain variables. First, two types of single-objective programming models with uncertain variables as uncertain chance-constrained model and uncertain maximization chance-constrained model are established to meet different management requirements, then they are extended to multi-objective programming model with uncertain variables.展开更多
Regarding KMV model identification credit risk profile of small and medium-sized listed companies, at present, domestic scholars has made some achievements in the process of the KMV model combined with China’s nation...Regarding KMV model identification credit risk profile of small and medium-sized listed companies, at present, domestic scholars has made some achievements in the process of the KMV model combined with China’s national conditions. In this paper, we will amend the model by using uncertain interest rate instead of fixed rate on the basis of existing research. Comparing the uncertain KMV model to traditional KMV model with ST-listed companies and non-ST-listed companies in Shanghai and Shenzhen stock exchange, we find that it performs slightly better as a predictor in uncertain KMV model and in out of sample forecasts.展开更多
The self-centring brace is recognized as one of the practical solutions for mitigating catastrophic consequences caused by earthquakes and improving structural resilience.Compared to the current methods where self-cen...The self-centring brace is recognized as one of the practical solutions for mitigating catastrophic consequences caused by earthquakes and improving structural resilience.Compared to the current methods where self-centring capacity is typically provided by pre-stressed steel rods or disc springs,carbon fiber-reinforced polymer(CFRP)material of higher tensile strength and deformation capacity is emerging as a preferred alternative to traditional materials.Based on that,this study mainly aims to propose a novel self-centring buckling-restrained brace(SC-BRB)by using pre-stressed CFRP rods as self-centring components,named the CFRP-SC-BRB.First,component-level analysis was conducted by experimental and numerical methods,to verify the feasibility of the designed configuration.Cyclic and ultra-low-cycle fatigue tests on the specimen demonstrated the excellent performance of the CFRP-SC-BRB,with the peak force of the brace at the drift ratio of 1/120 over 2900 kN and a residual drift ratio controlled below 0.5%.Finite element models in refined and simplified methods were validated by the experimental results and theoretical prediction.Then,a series of system-level analyses are carried out on a prototype frame incorporating the proposed CFRP-SC-BRBs.Compared to the original design with conventional BRBs,seismic responses of the frame fully or partially replaced by the SC-BRBs show a competitive advantage in seismic performance.Especially for the SC-BRB frame with full replacement,the median residual inter-storey drift ratios are reduced by 29.3%and 50.5%under design basis and maximum considered earthquakes,respectively,compared to the conventional BRB frame.In conclusion,it is demonstrated that the proposed CFRP-SC-BRB is effective in improving seismic resilience both at component and system levels.Practical suggestions are also provided to address potential challenges in promoting the novel product in actual application.展开更多
基金financially supported by the Natural Science Foundation of China (Nos. 21076028 and 50802010)
文摘Polyacrylonitrile （PAN）, PAN/cellulose acetate （CA）, and PAN/CA-Ag based activated carbon nanofiber （ACNF） were prepared using electrostatic spinning and further heat treatment. Thermogravimetrylifferential scanning calorimetry （TG-DSC） analysis indicated that the addition of CA or Ag did not have a significant impact on the thermal decomposition of PAN materials but the yields of fibers could be improved. Scanning electron microscopy （SEM） analysis showed that the micromorphologies of produced fibers were greatly influenced by the viscosity and conductivity of precursor solutions. Fourier transform infrared spectroscopy （FT-IR） analysis proved that a cyclized or trapezoidal structure could form and the carbon scaffold composed of C=C bonds appeared in the PAN-based ACNFs. The characteristic dif- fraction peaks in X-ray diffraction （XRD） spectra were the evidence of a turbostratic structure and silver existed in the PAN/CA-Ag based ACNF. Brurmer-Emmett-Teller （BET） analysis showed that the doping of CA and Ag increased surface area and micropore volume of fi- bers; particularly, PAN/CA-Ag based ACNF exhibited the best porosity feature. Furthermore, SO2 adsorption experiments indicated that all the three fibers had good adsorption effects on lower concentrations of SO2 at room temperature; especially, the PAN/CA-Ag based ACNF showed the best adsorption performance, and it may be one of the most promising adsorbents used in the fields of chemical industry and en- vironment protection.
文摘KMV model is one of the most important credit risk evaluation models in the world. It uses B-S option pricing and Morton formula based on the market value and volatility of the company’s equity, debt maturities, risk-free interest rates and the book value of liabilities to estimate the market value of the company’s assets and the volatility of the asset value. In this paper, based on the theory of KMV model, we can derive the listed company’s default rate, and assess credit risk. And the result is reasonable.
文摘This article aims to discuss the strike two-dimensional wind vector on geostationary satellite imageries. The magnitude and direction of the wind vector are decided by the moving speed of the clouds. First, based on the features of the cloud map, we extract the characteristics of clouds and establish matching model for the clouds image. Maximum correlation coefficient between the target modules and tracking module is obtained by using infrared brightness temperature cross-correlation coefficient method. Then, the beginning and end of the wind vector can be ascertained. Using the spherical triangles of the law of cosines, we determine the magnitude and direction of the wind vector.
文摘Project scheduling problem is mainly to determine the schedule of allocating resources in order to balance the total cost and the completion time. This paper chiefly uses chance theory to introduce project scheduling problem with uncertain variables. First, two types of single-objective programming models with uncertain variables as uncertain chance-constrained model and uncertain maximization chance-constrained model are established to meet different management requirements, then they are extended to multi-objective programming model with uncertain variables.
文摘Regarding KMV model identification credit risk profile of small and medium-sized listed companies, at present, domestic scholars has made some achievements in the process of the KMV model combined with China’s national conditions. In this paper, we will amend the model by using uncertain interest rate instead of fixed rate on the basis of existing research. Comparing the uncertain KMV model to traditional KMV model with ST-listed companies and non-ST-listed companies in Shanghai and Shenzhen stock exchange, we find that it performs slightly better as a predictor in uncertain KMV model and in out of sample forecasts.
基金Shanghai Science and Technology Plan Funding Project(No.20DZ2253000)the Shanghai Sailing Program(No.24YF2751000)the CSCEC Technology R&D Program(No.CSCEC-2022-Z-8).
文摘The self-centring brace is recognized as one of the practical solutions for mitigating catastrophic consequences caused by earthquakes and improving structural resilience.Compared to the current methods where self-centring capacity is typically provided by pre-stressed steel rods or disc springs,carbon fiber-reinforced polymer(CFRP)material of higher tensile strength and deformation capacity is emerging as a preferred alternative to traditional materials.Based on that,this study mainly aims to propose a novel self-centring buckling-restrained brace(SC-BRB)by using pre-stressed CFRP rods as self-centring components,named the CFRP-SC-BRB.First,component-level analysis was conducted by experimental and numerical methods,to verify the feasibility of the designed configuration.Cyclic and ultra-low-cycle fatigue tests on the specimen demonstrated the excellent performance of the CFRP-SC-BRB,with the peak force of the brace at the drift ratio of 1/120 over 2900 kN and a residual drift ratio controlled below 0.5%.Finite element models in refined and simplified methods were validated by the experimental results and theoretical prediction.Then,a series of system-level analyses are carried out on a prototype frame incorporating the proposed CFRP-SC-BRBs.Compared to the original design with conventional BRBs,seismic responses of the frame fully or partially replaced by the SC-BRBs show a competitive advantage in seismic performance.Especially for the SC-BRB frame with full replacement,the median residual inter-storey drift ratios are reduced by 29.3%and 50.5%under design basis and maximum considered earthquakes,respectively,compared to the conventional BRB frame.In conclusion,it is demonstrated that the proposed CFRP-SC-BRB is effective in improving seismic resilience both at component and system levels.Practical suggestions are also provided to address potential challenges in promoting the novel product in actual application.
