In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the...In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the relation between active energy E and oxygen concentration c. The reaction order n and active energy E were calculated with this equation based on experiments of static oxygen consumption tests. In addition, we proved the rationality of the E-c equation using a kinetic compensation effect and obtained the isokinetic temperature Tc. The results show that： 1） the gas coal oxidizes easily with increasing temperature and the oxidation tends to be spontaneous at higher temperatures; 2） the oxygen concentration c affects oxygen consumption very much at lower temperatures but has only a small effect at higher temperatures; 3） the isokinetic temperature Tc was 127 ℃ which has been experimentally validated as the key turning point during low-temperature spontaneous combustion of gas coal.展开更多
The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory d...The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.展开更多
Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become ...Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become important. Charging oil shale underground to heat oil shale till kerogen's decomposition temperature, then crude oil and other gases can be generated. The resistance of the oil shale samples was measured by Direct Current (DC) quadripole method to find out the variation rules of resistance value. In the experiments, oil shale presented its semiconductor property. When heated till 350℃-450℃, its resistance changed greatly, optional for heating and cracking. The porosity, oil content, media and composition affected the resistance largely.展开更多
Using proper footwear is crucial to avoid pain, deformations and injuries on foot. For athletes, a pair of good shoes is vital for comfort and may add to performance improvement. The main objective of this study is to...Using proper footwear is crucial to avoid pain, deformations and injuries on foot. For athletes, a pair of good shoes is vital for comfort and may add to performance improvement. The main objective of this study is to study the performance of some commonly used shoes in the takraw games by using experimental tests and thermal measurements. The momentum and kinetic energies that were generated by the takraw shoes were also measured. The methods used in this study included free fall test, impact force analysis and surface thermal assessment. From the outcomes of the experiments, it was found that the prototype FA shoe was better in absorption of momentum and impact force than the other shoes and also with lower surface temperature after the trial game. These outcomes suggested that it was more suitable to be worn by the takraw players for better performance. All the information obtained from this study are particularly useful for improvement on the current design oftakraw shoe.展开更多
Terms of synthesis were defined for the creation of new generation chelate fertilizers and for their experimental testing. Glutamine acid and citric acid containing chelate citrates of the general formulae M.gI.HL＇nH...Terms of synthesis were defined for the creation of new generation chelate fertilizers and for their experimental testing. Glutamine acid and citric acid containing chelate citrates of the general formulae M.gI.HL＇nHO were synthesized, where, M = Mn, Zn, Fe, Co, Cu; n = 0; 1; 1.5; gl-glutamine acid; HL-citric acid anion. Identity and composition of synthesized compounds were determined by microelemental analysis, melting temperature and X-ray diffraction analysis. X-ray diffraction analysis of the compounds and glutamine acid and citric acid （H4L） was used to determine their crystalline structure and roentgen-amorphous and iso-structural orders. Their solubility was studied in various solvents.展开更多
Measurement of the volume of gas adsorbed per unit mass of coal with increasing pressure at a constant temperature produces an isotherm that describes the gas storage capacity of this type of coal. The accurate testin...Measurement of the volume of gas adsorbed per unit mass of coal with increasing pressure at a constant temperature produces an isotherm that describes the gas storage capacity of this type of coal. The accurate testing and interpretation of coal sorption isotherm plays an important role in the areas of coal mine methane drainage, coalbed methane （CBM） reservoir resource assessment, enhanced coalbed methane （ECBM） recovery, as well as the carbon dioxide （CO2） sequestration in deep coal seams or similar geological formations. Different coal sorption isotherm testing apparatus and associated calculation methods are critically reviewed and presented in this paper. These include both volumetric and gravimetric based methods, as well as experimental sorption tests with confining stress and direction sorption methods. The volumetric techniques utilise experimental apparatus with sample cell and injection pump and that with both sample cell and reference cell. Whilst the gravimetric approachesinclude methods with sample cell and suspension magnetic balance and that with both sample cell and reference cell. Different testing methods are compared and discussed in this study. A unique in-house-built coal sorption isotherm testing apparatus at the University of Wollongong was presented together with the calculation method, procedures and experimental results. The isotherm results can be calculated by both Soave-Redlich-Kwong （SRK） equation and calibration cure methods which can be used directly to convert the volume of adsorbed gas in different test conditions to standard condition （NTP）.展开更多
The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fr...The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fracture after exceeding 107 cycles. Fractographic analysis revealed that there was a transition from fatigue crack initiation at multi-sites to single initiation with decreasing stress levels. The fracture surface can be divided into four areas according to the appearance, associated with fracture mechanics analysis of the corresponding stress intensity factors. The fracture mechanism dominant in each area was disclosed by scanning electron microscope examination and analyzed in comparison with those obtained from the crack growth tests. Subsequently, life prediction modeling was proposed by estimating the crack initiation and propagation stage respectively. It was found that Chan (2003)'s model for initiation life and the Paris law for growth life can provide comparable predictions against the experimental life.展开更多
For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out ...For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out with a temperature-control precision of 0.1℃, and 117 columnar-grained ice specimens were loaded along the direction parallel to ice surface under different test temperatures （-4, -7, -10, -13, -16℃） and strain rates ranging from 10^-6 to 10^-2 s^-1 within which the ductile region, duetile-brittle transition and brittle region are contained. The uniaxial compressive strengths, density and salinity of the ice specmens were measured. The results support the curved-surface relationship between the uniaxial compressive strength and porosity within a wide range of strain rate. The curved-surface relationship gives a quantitative description about the variations of the mechanical behavior transition point with ice porosity, and supplies a uniform mathematical representation of uniaxial compressive strength under different failure modes. Besides, it is deduced that abnormal ice condition in 2009-2010 winter will not result in a change of the uniaxial compressive strength of sea ice in Bohai Sea.展开更多
基金financial support provided by the National Key Technology R&D Program during the 11th Five-Year Period (No. 2006BAK03B05)the National Natural Science Foundation of China (Nos.50534090, 50674090 and 50804047)+1 种基金the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology (Nos.08KF14 and SKLCRSM09X04)the Scien-tific Research Foundation of China University of Mining & Technology (No.2007A001)
文摘In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the relation between active energy E and oxygen concentration c. The reaction order n and active energy E were calculated with this equation based on experiments of static oxygen consumption tests. In addition, we proved the rationality of the E-c equation using a kinetic compensation effect and obtained the isokinetic temperature Tc. The results show that： 1） the gas coal oxidizes easily with increasing temperature and the oxidation tends to be spontaneous at higher temperatures; 2） the oxygen concentration c affects oxygen consumption very much at lower temperatures but has only a small effect at higher temperatures; 3） the isokinetic temperature Tc was 127 ℃ which has been experimentally validated as the key turning point during low-temperature spontaneous combustion of gas coal.
基金Projects(51274099,51474106)supported by the National Natural Science Foundation of China
文摘The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.
文摘Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become important. Charging oil shale underground to heat oil shale till kerogen's decomposition temperature, then crude oil and other gases can be generated. The resistance of the oil shale samples was measured by Direct Current (DC) quadripole method to find out the variation rules of resistance value. In the experiments, oil shale presented its semiconductor property. When heated till 350℃-450℃, its resistance changed greatly, optional for heating and cracking. The porosity, oil content, media and composition affected the resistance largely.
文摘Using proper footwear is crucial to avoid pain, deformations and injuries on foot. For athletes, a pair of good shoes is vital for comfort and may add to performance improvement. The main objective of this study is to study the performance of some commonly used shoes in the takraw games by using experimental tests and thermal measurements. The momentum and kinetic energies that were generated by the takraw shoes were also measured. The methods used in this study included free fall test, impact force analysis and surface thermal assessment. From the outcomes of the experiments, it was found that the prototype FA shoe was better in absorption of momentum and impact force than the other shoes and also with lower surface temperature after the trial game. These outcomes suggested that it was more suitable to be worn by the takraw players for better performance. All the information obtained from this study are particularly useful for improvement on the current design oftakraw shoe.
基金We thank Science ＆ Technology Center in Ukraine and Shota Rustaveli National Science Foundation. The work was implemented with the support of Science ＆ Technology Center in Ukraine Project Proposal #5461 and Shota Rustaveli National Science Foundation Grant #30/06.
文摘Terms of synthesis were defined for the creation of new generation chelate fertilizers and for their experimental testing. Glutamine acid and citric acid containing chelate citrates of the general formulae M.gI.HL＇nHO were synthesized, where, M = Mn, Zn, Fe, Co, Cu; n = 0; 1; 1.5; gl-glutamine acid; HL-citric acid anion. Identity and composition of synthesized compounds were determined by microelemental analysis, melting temperature and X-ray diffraction analysis. X-ray diffraction analysis of the compounds and glutamine acid and citric acid （H4L） was used to determine their crystalline structure and roentgen-amorphous and iso-structural orders. Their solubility was studied in various solvents.
文摘Measurement of the volume of gas adsorbed per unit mass of coal with increasing pressure at a constant temperature produces an isotherm that describes the gas storage capacity of this type of coal. The accurate testing and interpretation of coal sorption isotherm plays an important role in the areas of coal mine methane drainage, coalbed methane （CBM） reservoir resource assessment, enhanced coalbed methane （ECBM） recovery, as well as the carbon dioxide （CO2） sequestration in deep coal seams or similar geological formations. Different coal sorption isotherm testing apparatus and associated calculation methods are critically reviewed and presented in this paper. These include both volumetric and gravimetric based methods, as well as experimental sorption tests with confining stress and direction sorption methods. The volumetric techniques utilise experimental apparatus with sample cell and injection pump and that with both sample cell and reference cell. Whilst the gravimetric approachesinclude methods with sample cell and suspension magnetic balance and that with both sample cell and reference cell. Different testing methods are compared and discussed in this study. A unique in-house-built coal sorption isotherm testing apparatus at the University of Wollongong was presented together with the calculation method, procedures and experimental results. The isotherm results can be calculated by both Soave-Redlich-Kwong （SRK） equation and calibration cure methods which can be used directly to convert the volume of adsorbed gas in different test conditions to standard condition （NTP）.
基金Project supported by the National Natural Science Foundation of China (Nos 10872105 and 51071094)the Mitsubishi Heavy Industries, Ltd, Japan
文摘The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fracture after exceeding 107 cycles. Fractographic analysis revealed that there was a transition from fatigue crack initiation at multi-sites to single initiation with decreasing stress levels. The fracture surface can be divided into four areas according to the appearance, associated with fracture mechanics analysis of the corresponding stress intensity factors. The fracture mechanism dominant in each area was disclosed by scanning electron microscope examination and analyzed in comparison with those obtained from the crack growth tests. Subsequently, life prediction modeling was proposed by estimating the crack initiation and propagation stage respectively. It was found that Chan (2003)'s model for initiation life and the Paris law for growth life can provide comparable predictions against the experimental life.
基金supported by the National Natural Science Foundation of China(Grant Nos.50921001,50879008)State Key Laboratory of Fro-zen Soil Engineering(Grant No.SKLFSE200904)+1 种基金Vilho,Yrj and Kalle Visl Fund of the Finnish Academy of Sciences and Lettersthe Norwegian Research Council Project AMORA(Grant No.193592/S30)
文摘For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out with a temperature-control precision of 0.1℃, and 117 columnar-grained ice specimens were loaded along the direction parallel to ice surface under different test temperatures （-4, -7, -10, -13, -16℃） and strain rates ranging from 10^-6 to 10^-2 s^-1 within which the ductile region, duetile-brittle transition and brittle region are contained. The uniaxial compressive strengths, density and salinity of the ice specmens were measured. The results support the curved-surface relationship between the uniaxial compressive strength and porosity within a wide range of strain rate. The curved-surface relationship gives a quantitative description about the variations of the mechanical behavior transition point with ice porosity, and supplies a uniform mathematical representation of uniaxial compressive strength under different failure modes. Besides, it is deduced that abnormal ice condition in 2009-2010 winter will not result in a change of the uniaxial compressive strength of sea ice in Bohai Sea.
