[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk(the ...[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk(the stick and the root)and on the traverse direction(the cuticle,cortex and medulla).[Result] Cotton stalk is a material of uneven and irregular texture,and there are great differences in the structure of all these parts on the longitudinal and traverse directions,especially in the contents of different components in each layer.The reaction in the stick and root becomes violent along with the increase in the rising rate of temperature,and carbon yield rate decreases in turn.Besides with the same rising rate of temperature,carbon yield rate of cotton stick is higher than the one of cotton root.Carbon yield rates of cuticle,cortex and medulla decrease in turn while the violence of the reaction in cuticle is less severe than in cortex and medulla.[Conclusion] It has provided theoretical basis for obtaining activated carbon technology of cotton stick.展开更多
The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and...The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influencing mechanism of chromium on the oxidation resistance of Ti-Cr alloys was discussed. The results show that the oxidation resistance of the alloys decreases with Cr below a critical chromium content wC and increases above wC; above 1000 K, the oxidation kinetics obeys parabolic rule and titanium dominates the oxidation process; after oxidation, the oxygen-diffusing layer is present in the alloy matrix, the oxide scale is mainly composed of rutile whose internal layer is rich in chromium, and chromium oxides separated out from TiO2 near the alloy-oxide interface improve the oxidation resistance. Ignition of metals and alloys is a fast non-isothermal oxidation process and the oxidation mechanism of Ti-Cr alloys during ignition is predicted.展开更多
We report a simple preparation method of a renewable superhydrophobic surface by thermally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluoride (PVDF) membranes with hierarchical ...We report a simple preparation method of a renewable superhydrophobic surface by thermally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluoride (PVDF) membranes with hierarchical structures were prepared by a TIPS process under different cooling conditions, which were confirmed by scanning electron microscopy and mercury intrusion porosimetry. After peeling off the top layer, rough structures with hundreds of nanometers to several microns were obtained. A digital microscopy determines that the surface roughness of peeled PVDF membranes is much higher than that of the original PVDF membrane, which is important to obtain the superhydrophobicity. Water contact angle and sliding angle measurements demonstrate that the peeled membrane surfaces display super- hydrophobicity with a high contact angle (152°) and a low sliding angle (7.2°). Moreover, the superhydrophobicity can be easily recovered for many times by a simple mechanical peeling, identical to the original superhydrophobicity. This simple preparation method is low cost, and suitable for large-scale industrialization, which may offer more opportunities for practical applications.展开更多
According to the data characteristics of Landsat thematic mapper (TM) and MODIS, a new fu sion algorithm about thermal infrared data has been proposed in the article based on improving wave let reconstruction. Under...According to the data characteristics of Landsat thematic mapper (TM) and MODIS, a new fu sion algorithm about thermal infrared data has been proposed in the article based on improving wave let reconstruction. Under the domain of neighborhood wavelet reconstruction, data of TM and MO DIS are divided into three layers using wavelet decomposition. The texture information of TM data is retained by fusing highfrequency information. The neighborhood correction coefficient method (NC CM) is set up based on the search neighborhood of a certain size to fuse lowfrequency information. Thermal infrared value of MODIS data is reduced to the space value of TM data by applying NCCM. The data with high spectrum, high spatial and high temporal resolution, are obtained through the al gorithm in the paper. Verification results show that the texture information of TM data and high spec tral information of MODIS data could be preserved well by the fusion algorithm. This article could provide technical support for high precision and fast extraction of the surface environment parame ters.展开更多
The effective conductivity (aeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes re...The effective conductivity (aeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes recon- structed numerically by packing spherical particles in a computational domain, followed by a dilation process to simulate the sintering procedure. The effects of various parameters on the effective conductivity of the electrodes are investigated, including material composition, porosity, particle size and contact angle. Results show that the effective conductivity ratio (aeff/ao) of the computed con- ducting phase is mainly affected by its total volume frac- tion (VF) in electrode (including the porosity). The effective conductivity can be improved by increasing the VF, electrode particle size or the contact angle between electrode particles. Based on the numerical results, the conventional percolation model for the calculation of O'eft is improved by adjusting the Bruggeman factor from 1.5 to 2.7. The results are useful for understanding the microstructure properties of SOFC composite electrode and for subsequent electrode optimization.展开更多
Based on the characteristics of the internal structure of closed-cell aluminum foam, this paper attempts to illus- trate the process of reconstructing the internal structures of closed-cell aluminum foam in Monte-Carl...Based on the characteristics of the internal structure of closed-cell aluminum foam, this paper attempts to illus- trate the process of reconstructing the internal structures of closed-cell aluminum foam in Monte-Carlo method and the fractal characteristics of the reconstructed model. Furthermore, Binary Array Method is proposed by analyzing the reconstructed model and the thermal conductivity model of closed-cell aluminum foam is established. At the same time, the thermal conductivity of the foam materials with different porosity is calculated by Binary Array Method, and the calculated value coincides with the experimental results in the reference, which proves the correctness of these methods.展开更多
A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connect...A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connected to the backbone of tetracene.This compound was characterized by single crystal X-ray structure analysis,thermogravimetric analysis,absorption spectra and electrochemical measurements.Unlike rubrene,DTTDO exhibited excellent film forming ability by normal vacuum deposition,indicating its promising applications in organic thin film transistors.展开更多
文摘[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk(the stick and the root)and on the traverse direction(the cuticle,cortex and medulla).[Result] Cotton stalk is a material of uneven and irregular texture,and there are great differences in the structure of all these parts on the longitudinal and traverse directions,especially in the contents of different components in each layer.The reaction in the stick and root becomes violent along with the increase in the rising rate of temperature,and carbon yield rate decreases in turn.Besides with the same rising rate of temperature,carbon yield rate of cotton stick is higher than the one of cotton root.Carbon yield rates of cuticle,cortex and medulla decrease in turn while the violence of the reaction in cuticle is less severe than in cortex and medulla.[Conclusion] It has provided theoretical basis for obtaining activated carbon technology of cotton stick.
文摘The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influencing mechanism of chromium on the oxidation resistance of Ti-Cr alloys was discussed. The results show that the oxidation resistance of the alloys decreases with Cr below a critical chromium content wC and increases above wC; above 1000 K, the oxidation kinetics obeys parabolic rule and titanium dominates the oxidation process; after oxidation, the oxygen-diffusing layer is present in the alloy matrix, the oxide scale is mainly composed of rutile whose internal layer is rich in chromium, and chromium oxides separated out from TiO2 near the alloy-oxide interface improve the oxidation resistance. Ignition of metals and alloys is a fast non-isothermal oxidation process and the oxidation mechanism of Ti-Cr alloys during ignition is predicted.
基金This work is supported by the National Natural Science Foundation of China (No.51403107), the Natural Science Foundation of Ningbo (No.2015A610014), the Key Laboratory of Marine Materials and Related Tech- nologies (No.2016K07), and K. C. Wong Magna Fund in Ningbo University.
文摘We report a simple preparation method of a renewable superhydrophobic surface by thermally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluoride (PVDF) membranes with hierarchical structures were prepared by a TIPS process under different cooling conditions, which were confirmed by scanning electron microscopy and mercury intrusion porosimetry. After peeling off the top layer, rough structures with hundreds of nanometers to several microns were obtained. A digital microscopy determines that the surface roughness of peeled PVDF membranes is much higher than that of the original PVDF membrane, which is important to obtain the superhydrophobicity. Water contact angle and sliding angle measurements demonstrate that the peeled membrane surfaces display super- hydrophobicity with a high contact angle (152°) and a low sliding angle (7.2°). Moreover, the superhydrophobicity can be easily recovered for many times by a simple mechanical peeling, identical to the original superhydrophobicity. This simple preparation method is low cost, and suitable for large-scale industrialization, which may offer more opportunities for practical applications.
基金Supported by the National Natural Science Foundation of China(No.41101503)the National Social Science Foundation of China(No.11&ZD161)Graduate Innovative Scientific Research Project of Chongqing Technology and Business University(No.yjscxx2014-052-29)
文摘According to the data characteristics of Landsat thematic mapper (TM) and MODIS, a new fu sion algorithm about thermal infrared data has been proposed in the article based on improving wave let reconstruction. Under the domain of neighborhood wavelet reconstruction, data of TM and MO DIS are divided into three layers using wavelet decomposition. The texture information of TM data is retained by fusing highfrequency information. The neighborhood correction coefficient method (NC CM) is set up based on the search neighborhood of a certain size to fuse lowfrequency information. Thermal infrared value of MODIS data is reduced to the space value of TM data by applying NCCM. The data with high spectrum, high spatial and high temporal resolution, are obtained through the al gorithm in the paper. Verification results show that the texture information of TM data and high spec tral information of MODIS data could be preserved well by the fusion algorithm. This article could provide technical support for high precision and fast extraction of the surface environment parame ters.
基金supported by a grant from Research Grant CouncilUniversity Grants CommitteeHong Kong SAR(Poly U 152127/14E)
文摘The effective conductivity (aeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes recon- structed numerically by packing spherical particles in a computational domain, followed by a dilation process to simulate the sintering procedure. The effects of various parameters on the effective conductivity of the electrodes are investigated, including material composition, porosity, particle size and contact angle. Results show that the effective conductivity ratio (aeff/ao) of the computed con- ducting phase is mainly affected by its total volume frac- tion (VF) in electrode (including the porosity). The effective conductivity can be improved by increasing the VF, electrode particle size or the contact angle between electrode particles. Based on the numerical results, the conventional percolation model for the calculation of O'eft is improved by adjusting the Bruggeman factor from 1.5 to 2.7. The results are useful for understanding the microstructure properties of SOFC composite electrode and for subsequent electrode optimization.
文摘Based on the characteristics of the internal structure of closed-cell aluminum foam, this paper attempts to illus- trate the process of reconstructing the internal structures of closed-cell aluminum foam in Monte-Carlo method and the fractal characteristics of the reconstructed model. Furthermore, Binary Array Method is proposed by analyzing the reconstructed model and the thermal conductivity model of closed-cell aluminum foam is established. At the same time, the thermal conductivity of the foam materials with different porosity is calculated by Binary Array Method, and the calculated value coincides with the experimental results in the reference, which proves the correctness of these methods.
基金support of the National Natural Science Foundation of China (60771031,60736004,20571079,20721061 and 50725311)National Basic Research Program of China (973 Program,2006CB806200 & 2006CB932100)Chinese Academy of Sciences
文摘A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connected to the backbone of tetracene.This compound was characterized by single crystal X-ray structure analysis,thermogravimetric analysis,absorption spectra and electrochemical measurements.Unlike rubrene,DTTDO exhibited excellent film forming ability by normal vacuum deposition,indicating its promising applications in organic thin film transistors.