Composite materials, which consist of organic and inorganic components, are widely used in various fields because of their excellent mechanical properties, resistance to corrosion, low-cost fabrication, etc. Thermal p...Composite materials, which consist of organic and inorganic components, are widely used in various fields because of their excellent mechanical properties, resistance to corrosion, low-cost fabrication, etc. Thermal properties of organic/inorganic composites play a crucial role in some applications such as thermal interface materials for micro-electronic packaging, nano-porous materials for sensor development, thermal insulators for aerospace, and high-performance thermoelectric materials for power generation and refrigeration. In the past few years, many studies have been conducted to reveal the physical mechanism of thermal transport in organic/ inorganic composite materials in order to stimulate their practical applications. In this paper, the theoretical and experimental progresses in this field are reviewed. Besides, main factors affecting the thermal conductivity of organic/ inorganic compositcs are discussed, including the intrinsic properties of organic matrix and inorganic fillers, topolo- gical structure of composites, loading volume fraction, and the interfacial thermal resistance between fillers and organic matrix.展开更多
In situ Synthesized TiC particles and β-Ti dendrites reinforced Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) composite ingots were preapared by the suction cast-ing method. The ingots with diameters from 1 up to 4 mm we...In situ Synthesized TiC particles and β-Ti dendrites reinforced Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) composite ingots were preapared by the suction cast-ing method. The ingots with diameters from 1 up to 4 mm were successfully obtained. It was shown that introducing TiC micro-sized particles into the amorphous matrix did not [(disturb the glass )(f)(orming ability \(GFA\) of the matrix, while)] the yield strength and ductility could be well improved. The phase constitution, microstructure and elements distribution in the composites were studied by OM,XRD,SEM and EDS. It was shown that the in situ synthesized TiC particles acting as heterogeneous nulcleation sites promoted the precipitation of β-Ti dendrites, resulting in the formation of the TiC par-ticles and β-Ti dendrites co-reinforced BMG composites. [(The compressive tests were employed to )(p)(robe the yield)] strength and ductility of BMG composites.展开更多
This research aimed at optimizing the reaction conditions for the catalytic hydrothermal liquefaction (HTL) of water hyacinth using iron oxide/nickel oxide nanocomposite as catalysts. The iron oxide/nickel oxide nanoc...This research aimed at optimizing the reaction conditions for the catalytic hydrothermal liquefaction (HTL) of water hyacinth using iron oxide/nickel oxide nanocomposite as catalysts. The iron oxide/nickel oxide nanocomposite was synthesized by the co-precipitation method and used in the hydrothermal liquefaction of water hyacinth. The composition and structural morphology of the synthesized catalysts were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic absorption spectroscopy (AAS). The particle size distribution of the catalyst nanoparticles was determined by the Image J software. Three reaction parameters were optimized using the response surface methodology (RSM). These were: temperature, residence time, and catalyst dosage. A maximum bio-oil yield of 59.4 wt% was obtained using iron oxide/nickel oxide nanocomposite compared to 50.7 wt% obtained in absence of the catalyst. The maximum bio-oil yield was obtained at a temperature of 320°C, 1.5 g of catalyst dosage, and 60 min of residence time. The composition of bio-oil was analyzed using gas chromatography-mass spectroscopy (GC-MS) and elemental analysis. The GC-MS results showed an increase of hydrocarbons from 58.3% for uncatalyzed hydrothermal liquefaction to 88.66% using iron oxide/nickel oxide nanocomposite. Elemental analysis results revealed an increase in the hydrogen and carbon content and a reduction in the Nitrogen, Oxygen, and Sulphur content of the bio-oil during catalytic HTL compared to HTL in absence of catalyst nanoparticles. The high heating value increased from 33.5 MJ/Kg for uncatalyzed hydrothermal liquefaction to 38.6 MJ/Kg during the catalytic HTL. The catalyst nanoparticles were recovered from the solid residue by sonication and magnetic separation and recycled. The recycled catalyst nanoparticles were still efficient as hydrothermal liquefaction (HTL) catalysts and were recycled four times. The application of iron oxide/ nickel oxide nanocomposites in th展开更多
Based on cavity resonance and sandwich composite plate （3D） theoretical model for frequency dispersion characterization theory, this paper presents a universal three-dimensional and displacement profile shapes of th...Based on cavity resonance and sandwich composite plate （3D） theoretical model for frequency dispersion characterization theory, this paper presents a universal three-dimensional and displacement profile shapes of the film bulk acoustic resonator （FBARs）. This model provides results of FBAR excited thickness-extensional and flexure modes, and the result of frequency dispersion is proposed in which the thicknesses and impedance of the electrodes and the piezoelectric material are taken into consideration; its further simplification shows good agreement with the modified Butterworth-Van-Dyke （MBVD） model. The displacement profile reflects the vibration stress distribution of electrode shapes and the lateral resonance effect, which depends on the axis ratio of the electrode shapes a/b. The results are consistent with the 3D finite element method modeling and laser interferometry measurement in general.展开更多
ZrB2 -SiC composite ceramic has been successfully introduced as heating element in super high temperature .field. This paper further investigated the microstructure of ZrB2 - SiC composite ceramic heating element an...ZrB2 -SiC composite ceramic has been successfully introduced as heating element in super high temperature .field. This paper further investigated the microstructure of ZrB2 - SiC composite ceramic heating element and the relationship between electric properties and temperature. SEM photos show that the heating element consists of SiC grains and ZrBz grains smaller than 10 μm. The voltage and current gradually increase and the furnace tempera- ture rises lineally with heating time prolonging. The electric resistance increases linearly with the temperature rising. The service temperatltre of the heating element can reach 1 800 ℃ and 2 150 ℃ in air and argon at- mosphere, respectively.展开更多
The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireles...The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN and cellular network is introduced, adding several models to the original systems. Furthermore, new radio access schemes for different types of Mobile Terminals (MTs) are proposed. Particularly, Spectrum Sharing (SS) between WLAN and cellular networks is discussed. Here, a new radio access scheme and channel assignment mechanism with code-division duplex (CDD) and Frequency Hopping (FH) technologies are raised, for the purpose of avoiding interference between heterogeneous networks. Finally, the performance of the above radio access schemes is analyzed, and simulation results proved its validation.展开更多
In this paper, we shall discuss the homogenization problem of boundary value problems for the systems of linear elasticity with the quasi-periodic microstruc-tures, and give several basic estimations for displacement,...In this paper, we shall discuss the homogenization problem of boundary value problems for the systems of linear elasticity with the quasi-periodic microstruc-tures, and give several basic estimations for displacement,stress and strain en-ergy,which are the basis of finite element computing.展开更多
文摘Composite materials, which consist of organic and inorganic components, are widely used in various fields because of their excellent mechanical properties, resistance to corrosion, low-cost fabrication, etc. Thermal properties of organic/inorganic composites play a crucial role in some applications such as thermal interface materials for micro-electronic packaging, nano-porous materials for sensor development, thermal insulators for aerospace, and high-performance thermoelectric materials for power generation and refrigeration. In the past few years, many studies have been conducted to reveal the physical mechanism of thermal transport in organic/ inorganic composite materials in order to stimulate their practical applications. In this paper, the theoretical and experimental progresses in this field are reviewed. Besides, main factors affecting the thermal conductivity of organic/ inorganic compositcs are discussed, including the intrinsic properties of organic matrix and inorganic fillers, topolo- gical structure of composites, loading volume fraction, and the interfacial thermal resistance between fillers and organic matrix.
文摘In situ Synthesized TiC particles and β-Ti dendrites reinforced Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) composite ingots were preapared by the suction cast-ing method. The ingots with diameters from 1 up to 4 mm were successfully obtained. It was shown that introducing TiC micro-sized particles into the amorphous matrix did not [(disturb the glass )(f)(orming ability \(GFA\) of the matrix, while)] the yield strength and ductility could be well improved. The phase constitution, microstructure and elements distribution in the composites were studied by OM,XRD,SEM and EDS. It was shown that the in situ synthesized TiC particles acting as heterogeneous nulcleation sites promoted the precipitation of β-Ti dendrites, resulting in the formation of the TiC par-ticles and β-Ti dendrites co-reinforced BMG composites. [(The compressive tests were employed to )(p)(robe the yield)] strength and ductility of BMG composites.
文摘This research aimed at optimizing the reaction conditions for the catalytic hydrothermal liquefaction (HTL) of water hyacinth using iron oxide/nickel oxide nanocomposite as catalysts. The iron oxide/nickel oxide nanocomposite was synthesized by the co-precipitation method and used in the hydrothermal liquefaction of water hyacinth. The composition and structural morphology of the synthesized catalysts were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic absorption spectroscopy (AAS). The particle size distribution of the catalyst nanoparticles was determined by the Image J software. Three reaction parameters were optimized using the response surface methodology (RSM). These were: temperature, residence time, and catalyst dosage. A maximum bio-oil yield of 59.4 wt% was obtained using iron oxide/nickel oxide nanocomposite compared to 50.7 wt% obtained in absence of the catalyst. The maximum bio-oil yield was obtained at a temperature of 320°C, 1.5 g of catalyst dosage, and 60 min of residence time. The composition of bio-oil was analyzed using gas chromatography-mass spectroscopy (GC-MS) and elemental analysis. The GC-MS results showed an increase of hydrocarbons from 58.3% for uncatalyzed hydrothermal liquefaction to 88.66% using iron oxide/nickel oxide nanocomposite. Elemental analysis results revealed an increase in the hydrogen and carbon content and a reduction in the Nitrogen, Oxygen, and Sulphur content of the bio-oil during catalytic HTL compared to HTL in absence of catalyst nanoparticles. The high heating value increased from 33.5 MJ/Kg for uncatalyzed hydrothermal liquefaction to 38.6 MJ/Kg during the catalytic HTL. The catalyst nanoparticles were recovered from the solid residue by sonication and magnetic separation and recycled. The recycled catalyst nanoparticles were still efficient as hydrothermal liquefaction (HTL) catalysts and were recycled four times. The application of iron oxide/ nickel oxide nanocomposites in th
基金supported by the National Natural Science Foundation of China(Grant No.61275081)
文摘Based on cavity resonance and sandwich composite plate （3D） theoretical model for frequency dispersion characterization theory, this paper presents a universal three-dimensional and displacement profile shapes of the film bulk acoustic resonator （FBARs）. This model provides results of FBAR excited thickness-extensional and flexure modes, and the result of frequency dispersion is proposed in which the thicknesses and impedance of the electrodes and the piezoelectric material are taken into consideration; its further simplification shows good agreement with the modified Butterworth-Van-Dyke （MBVD） model. The displacement profile reflects the vibration stress distribution of electrode shapes and the lateral resonance effect, which depends on the axis ratio of the electrode shapes a/b. The results are consistent with the 3D finite element method modeling and laser interferometry measurement in general.
文摘ZrB2 -SiC composite ceramic has been successfully introduced as heating element in super high temperature .field. This paper further investigated the microstructure of ZrB2 - SiC composite ceramic heating element and the relationship between electric properties and temperature. SEM photos show that the heating element consists of SiC grains and ZrBz grains smaller than 10 μm. The voltage and current gradually increase and the furnace tempera- ture rises lineally with heating time prolonging. The electric resistance increases linearly with the temperature rising. The service temperatltre of the heating element can reach 1 800 ℃ and 2 150 ℃ in air and argon at- mosphere, respectively.
文摘The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN and cellular network is introduced, adding several models to the original systems. Furthermore, new radio access schemes for different types of Mobile Terminals (MTs) are proposed. Particularly, Spectrum Sharing (SS) between WLAN and cellular networks is discussed. Here, a new radio access scheme and channel assignment mechanism with code-division duplex (CDD) and Frequency Hopping (FH) technologies are raised, for the purpose of avoiding interference between heterogeneous networks. Finally, the performance of the above radio access schemes is analyzed, and simulation results proved its validation.
文摘In this paper, we shall discuss the homogenization problem of boundary value problems for the systems of linear elasticity with the quasi-periodic microstruc-tures, and give several basic estimations for displacement,stress and strain en-ergy,which are the basis of finite element computing.
