In order to improve the efficiency of heating and the uniformity of temperature distribution in recycling asphalt mixtures, a pyramidal radiation heater is designed. The principles of designing horn surface size and a...In order to improve the efficiency of heating and the uniformity of temperature distribution in recycling asphalt mixtures, a pyramidal radiation heater is designed. The principles of designing horn surface size and antenna length are established according to the law of energy conservation and microwave antenna radiation theory. Modeling and simulation are carried out using IE3D software. The simulation results demonstrate that, with a fixed horn surface size, the shortened electric antenna length is the main factor leading to the improved heating uniformity. On the other hand, with a fixed antenna length and diminished surface size, the standing wave ratio decreases with the improved radiation efficiency. Furthermore, the efficiency of radiation drops with increased distance between the horn surface and the asphalt pavement. Microwave heating experiments are carried out using this type of heater. The temperature distribution of asphalt samples is obtained by the grid temperature measurement method, and Matlab simulation is performed. The experimental results are in good agreement with the simulation.展开更多
Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures and thus a great deal of research has been focused on the development of a rheo...Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures and thus a great deal of research has been focused on the development of a rheological parameter that would address the rutting susceptibility of both unmodified and modified bituminous binders. In this research, three warm mix additives(Sasobit, Rheofalt and Zycotherm) were used to modify 60-70 penetration grade base binder. The rutting potential of both modified and unmodified binders were evaluated through the multiple stress creep recovery(MSCR)-based parameter, nonrecoverable compliance(Jnr) and recovery parameter(R). Several performance tests carried on stone matrix asphalt(SMA) mixtures comprising different nominal maximum aggregate sizes(NMASs, 9.5, 12.5 and 19 mm), like Marshall stability, dynamic and static creep and Hamburg wheel tracking tests to evaluate their rutting performance. The objective of this work is to correlate MSCR test results to performance. Results indicate that for the range of the gradations investigated in this work, increasing the nominal maximum aggregate size of the gradation would increase the permanent deformation resistance of the SMA mixture. Addition of 3% sasobit to base binder leads an increase in Jnr100 about 82%. Addition of 2% rheofalt to base binder leads an recovery increase of about 9.76 % and 27.44% in stress levels of 100 and 3200 Pa, respectively. The results reveal that rutting resistance of mixtures improves as Jnr decreases. The use of the MSCR test in the rutting characterization of bituminous binders is highly recommended based on the results of this work.展开更多
The characteristic evaluation of aluminum oxide （A1203）/carbon nanotubes （CNTs） hybrid composites for micro-electrical discharge machining （EDM） was described. Alumina matrix composites reinforced with CNTs were...The characteristic evaluation of aluminum oxide （A1203）/carbon nanotubes （CNTs） hybrid composites for micro-electrical discharge machining （EDM） was described. Alumina matrix composites reinforced with CNTs were fabricated by a catalytic chemical vapor deposition method. A1203 composites with different CNT concentrations were synthesized. The electrical characteristic of A1203/CNTs composites was examined. These composites were machined by the EDM process according to the various EDM parameters, and the characteristics of machining were analyzed using field emission scanning electron microscope （FESEM）. The electrical conductivity has a increasing tendency as the CNTs content is increased and has a critical point at 5% A1203 （volume fraction）. In the machining accuracy, many tangles of CNT in A1203/CNTs composites cause violent spark. Thus, it causes the poor dimensional accuracy and circularity. The results show that conductivity of the materials and homogeneous distribution of CNTs in the matrix are important factors for micro-EDM of A1203/CNTs hybrid composites.展开更多
Aluminum alloy base surface hybrid composites were fabricated by incorporating with mixture of （SiC＋Gr） and （SiC＋Al2O3） particles of 20 μm in average size on an aluminum alloy 6061-T6 plate using friction stir ...Aluminum alloy base surface hybrid composites were fabricated by incorporating with mixture of （SiC＋Gr） and （SiC＋Al2O3） particles of 20 μm in average size on an aluminum alloy 6061-T6 plate using friction stir processing （FSP）. Microstructures of both the surface hybrid composites revealed that SiC, Gr and Al2O3 are uniformly dispersed in the nugget zone （NZ）. It was observed that the addition of Gr particles rather than Al2O3 particles with SiC particles, decreases the microhardness but immensely increases the dry sliding wear resistance of aluminum alloy 6061-T6 surface hybrid composite. The observed microhardness and wear properties are correlated with microstructures and worn micrographs.展开更多
Multiferroic bi-layer Fe/BaTiO3 （BTO） thin films were successfully deposited on Pt（200）/MgO（100） substrates using ion beam sputter deposition （1BSD）, and the mutiferroic properties were studied at room tempera...Multiferroic bi-layer Fe/BaTiO3 （BTO） thin films were successfully deposited on Pt（200）/MgO（100） substrates using ion beam sputter deposition （1BSD）, and the mutiferroic properties were studied at room temperature. X-ray diffraction （XRD） analyses showed that BTO films were c-axis oriented and epitaxially grown on platinum coated MgO substrates, and （110） epitaxial Fe films were subsequently grown on （001） BTO films. Fe/BTO bi-layer films showed good ferroelectric and ferromagnetic properties at room temperature and the multiferroic coupling was observed, which should be attributed to the hybridization of Fe and Ti occurring at the ferromagnetic-ferroelectric interface.展开更多
Piglets’ alactation stress with diarrhea as a main symptom is a serious problem in pig farming. The experiment indicates that the complex premix additive Huzikang duannaibao can be used to control ablactation stress ...Piglets’ alactation stress with diarrhea as a main symptom is a serious problem in pig farming. The experiment indicates that the complex premix additive Huzikang duannaibao can be used to control ablactation stress syndromes and its effects are better than that of the common antibiotic ligomycin.展开更多
New route of the utilization of products obtained by waste plastic pyrolysis has been investigated. ct-olefin-succinic-anhydride intermediate based on new experimental additives has been developed and used for achievi...New route of the utilization of products obtained by waste plastic pyrolysis has been investigated. ct-olefin-succinic-anhydride intermediate based on new experimental additives has been developed and used for achieving the better properties of carbon fibre reinforced polymer composites. Hydrocarbon fractions were produced by the pure thermal pyrolysis of waste polymers in a tube reactor using 550 ℃ in the absence of oxygen. Selected compounds （C30-C50） from pyrolysis products have been used as raw materials in the additive synthesis step. Polymer composite specimens have been investigated among others by universal tensile machine, SEM （scanning electron microscopy） and FTIR （fourier transformed infrared spectroscopy） methods. The tensile strength could be increased by 29.9%, the E-modulus by 24.2% and the Charpy impact strength by 13.3% in the presence of the experimental additive. Fibre-matrix interaction has been studied on SEM micrographs of the fractured face of composites. The results of mechanical testes have been supported by the SEM micrographs and possible shames of the coupling have been proposed.展开更多
A new pressurized feed system of the dual-thrust hybrid rocket motor for flight is presented in this paper.The feed system supplies 90% hydrogen peroxide (90%H 2 O 2) with two different flows of 4.5 and 2 kg s 1.The o...A new pressurized feed system of the dual-thrust hybrid rocket motor for flight is presented in this paper.The feed system supplies 90% hydrogen peroxide (90%H 2 O 2) with two different flows of 4.5 and 2 kg s 1.The oxidizer flow is changed through regulating the mass flow of the high-pressure gas and switching the performance modes of the unique oxidizer flow control valve simultaneously.The models of the gas storage container,pressure regulator valve,control orifice,propellant tank,oxidizer flow control valve and cavitating venturi are generated and used to compute the instantaneous pressure,temperature and mass flow rate.There is a good agreement between the simulated and experimental results.Parameter sensitivity analysis is also conducted.It is found that the throat diameter of the cavitating venturi in feed line 1 is the main factor affecting the mass flow in both boost and sustaining phase.Other parameters have limited effects on the mass flow rate and the transition time of the system.展开更多
基金The Key Project of Science and Technology of Ministry of Education(No.03081,105085)the SciTech Achievements Transformation Program of Jiangsu Province(No.BA2006068)
文摘In order to improve the efficiency of heating and the uniformity of temperature distribution in recycling asphalt mixtures, a pyramidal radiation heater is designed. The principles of designing horn surface size and antenna length are established according to the law of energy conservation and microwave antenna radiation theory. Modeling and simulation are carried out using IE3D software. The simulation results demonstrate that, with a fixed horn surface size, the shortened electric antenna length is the main factor leading to the improved heating uniformity. On the other hand, with a fixed antenna length and diminished surface size, the standing wave ratio decreases with the improved radiation efficiency. Furthermore, the efficiency of radiation drops with increased distance between the horn surface and the asphalt pavement. Microwave heating experiments are carried out using this type of heater. The temperature distribution of asphalt samples is obtained by the grid temperature measurement method, and Matlab simulation is performed. The experimental results are in good agreement with the simulation.
文摘Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures and thus a great deal of research has been focused on the development of a rheological parameter that would address the rutting susceptibility of both unmodified and modified bituminous binders. In this research, three warm mix additives(Sasobit, Rheofalt and Zycotherm) were used to modify 60-70 penetration grade base binder. The rutting potential of both modified and unmodified binders were evaluated through the multiple stress creep recovery(MSCR)-based parameter, nonrecoverable compliance(Jnr) and recovery parameter(R). Several performance tests carried on stone matrix asphalt(SMA) mixtures comprising different nominal maximum aggregate sizes(NMASs, 9.5, 12.5 and 19 mm), like Marshall stability, dynamic and static creep and Hamburg wheel tracking tests to evaluate their rutting performance. The objective of this work is to correlate MSCR test results to performance. Results indicate that for the range of the gradations investigated in this work, increasing the nominal maximum aggregate size of the gradation would increase the permanent deformation resistance of the SMA mixture. Addition of 3% sasobit to base binder leads an increase in Jnr100 about 82%. Addition of 2% rheofalt to base binder leads an recovery increase of about 9.76 % and 27.44% in stress levels of 100 and 3200 Pa, respectively. The results reveal that rutting resistance of mixtures improves as Jnr decreases. The use of the MSCR test in the rutting characterization of bituminous binders is highly recommended based on the results of this work.
基金Project(2010-0008-277) supported by Program of Establishment of an Infrastructure for Public Usepartly by NCRC (National Core Research Center) through the National Research Foundation of Korea funded by the Ministry of Education
文摘The characteristic evaluation of aluminum oxide （A1203）/carbon nanotubes （CNTs） hybrid composites for micro-electrical discharge machining （EDM） was described. Alumina matrix composites reinforced with CNTs were fabricated by a catalytic chemical vapor deposition method. A1203 composites with different CNT concentrations were synthesized. The electrical characteristic of A1203/CNTs composites was examined. These composites were machined by the EDM process according to the various EDM parameters, and the characteristics of machining were analyzed using field emission scanning electron microscope （FESEM）. The electrical conductivity has a increasing tendency as the CNTs content is increased and has a critical point at 5% A1203 （volume fraction）. In the machining accuracy, many tangles of CNT in A1203/CNTs composites cause violent spark. Thus, it causes the poor dimensional accuracy and circularity. The results show that conductivity of the materials and homogeneous distribution of CNTs in the matrix are important factors for micro-EDM of A1203/CNTs hybrid composites.
文摘Aluminum alloy base surface hybrid composites were fabricated by incorporating with mixture of （SiC＋Gr） and （SiC＋Al2O3） particles of 20 μm in average size on an aluminum alloy 6061-T6 plate using friction stir processing （FSP）. Microstructures of both the surface hybrid composites revealed that SiC, Gr and Al2O3 are uniformly dispersed in the nugget zone （NZ）. It was observed that the addition of Gr particles rather than Al2O3 particles with SiC particles, decreases the microhardness but immensely increases the dry sliding wear resistance of aluminum alloy 6061-T6 surface hybrid composite. The observed microhardness and wear properties are correlated with microstructures and worn micrographs.
基金Project supported by the Yeungnam University Research Grant in 2010Project (507111403888) supported by the National Science Foundation of China for International Communication and CooperationProject (50672034) supported by the National Natural Science Foundation of China
文摘Multiferroic bi-layer Fe/BaTiO3 （BTO） thin films were successfully deposited on Pt（200）/MgO（100） substrates using ion beam sputter deposition （1BSD）, and the mutiferroic properties were studied at room temperature. X-ray diffraction （XRD） analyses showed that BTO films were c-axis oriented and epitaxially grown on platinum coated MgO substrates, and （110） epitaxial Fe films were subsequently grown on （001） BTO films. Fe/BTO bi-layer films showed good ferroelectric and ferromagnetic properties at room temperature and the multiferroic coupling was observed, which should be attributed to the hybridization of Fe and Ti occurring at the ferromagnetic-ferroelectric interface.
文摘Piglets’ alactation stress with diarrhea as a main symptom is a serious problem in pig farming. The experiment indicates that the complex premix additive Huzikang duannaibao can be used to control ablactation stress syndromes and its effects are better than that of the common antibiotic ligomycin.
文摘New route of the utilization of products obtained by waste plastic pyrolysis has been investigated. ct-olefin-succinic-anhydride intermediate based on new experimental additives has been developed and used for achieving the better properties of carbon fibre reinforced polymer composites. Hydrocarbon fractions were produced by the pure thermal pyrolysis of waste polymers in a tube reactor using 550 ℃ in the absence of oxygen. Selected compounds （C30-C50） from pyrolysis products have been used as raw materials in the additive synthesis step. Polymer composite specimens have been investigated among others by universal tensile machine, SEM （scanning electron microscopy） and FTIR （fourier transformed infrared spectroscopy） methods. The tensile strength could be increased by 29.9%, the E-modulus by 24.2% and the Charpy impact strength by 13.3% in the presence of the experimental additive. Fibre-matrix interaction has been studied on SEM micrographs of the fractured face of composites. The results of mechanical testes have been supported by the SEM micrographs and possible shames of the coupling have been proposed.
文摘A new pressurized feed system of the dual-thrust hybrid rocket motor for flight is presented in this paper.The feed system supplies 90% hydrogen peroxide (90%H 2 O 2) with two different flows of 4.5 and 2 kg s 1.The oxidizer flow is changed through regulating the mass flow of the high-pressure gas and switching the performance modes of the unique oxidizer flow control valve simultaneously.The models of the gas storage container,pressure regulator valve,control orifice,propellant tank,oxidizer flow control valve and cavitating venturi are generated and used to compute the instantaneous pressure,temperature and mass flow rate.There is a good agreement between the simulated and experimental results.Parameter sensitivity analysis is also conducted.It is found that the throat diameter of the cavitating venturi in feed line 1 is the main factor affecting the mass flow in both boost and sustaining phase.Other parameters have limited effects on the mass flow rate and the transition time of the system.
