Copper, iron and cobalt based pre-alloyed powders for diamond tools were prepared by ultrahigh pressure water atomization（UPWA） process. Pre-alloyed powders prepared by different processes including UPWA, convention...Copper, iron and cobalt based pre-alloyed powders for diamond tools were prepared by ultrahigh pressure water atomization（UPWA） process. Pre-alloyed powders prepared by different processes including UPWA, conventional water atomization （CWA） and elemental metal mechanical mixing （EMMM） were sintered to segments and then compared in mechanical properties, holding force between matrix and diamond, fracture morphology of blank and sintering diamond section containing matrix. The results showed that the pre-alloyed powder prepared by UPWA exhibits the best mechanical properties including the relative density, the hardness and the bending strength of matrix sinteredsegment. Sintered segments fractography of UPWA pre-alloyed powder indicatesmechanical mosaic strength and chemical bonding force between the pre-alloyed powder and the diamond, leading to the great increase in the holding force between matrix and diamond. The mechanical performance andthe service life of diamond tools were greatly improved by UPWA pre-alloyed powders.展开更多
Undisturbed soil cores were taken from different slope positions （upslope, backslope and footslope） and soil depths （0-15, 20-35 and 100-115 cm） in a soil catena derived from Quaternary red clay to determine the s...Undisturbed soil cores were taken from different slope positions （upslope, backslope and footslope） and soil depths （0-15, 20-35 and 100-115 cm） in a soil catena derived from Quaternary red clay to determine the spatial changes in soil strength along the eroded slope and to ewluate an indicator to determine soil strength during compaction. Precompression stress, as an indicator of soil strength, significantly increased from topsoil layer to subsoil layer （P 〈0.05） and was affected by slope position. In the subsoil layer （20-35 cm）, the precompression stress at the footslope position was significantly greater than at the backslope and upslope positions （P 〈0.05）, while there were no significant differences at 0-15 and 100-115 cm. Precompression stress followed the spatial wriation of soil clay content with soil depth and had a significant linear relationship with soil porosity （r^2 = 0.40, P 〈 0.01）. Also, soil cohesion increased with increasing soil clay content. The precompression stress was significantly related to the applied stress corresponding to the highest change of pore water pressure （r^2 = 0.69, P 〈 0.01）. These results suggested that soil strength induced by soil erosion and soil management wried spatially along the slope and the maximum change in pore water pressure during compaction could be an easy indicator to describe soil strength.展开更多
Carbon dioxide pressure-broadened ro-vibrational transitions belonging to thev^2＋3v^3 band of H2160 have been measured with a sensitive cavity ring-down spectrometer. Water vapor of relatively low pressures （〈0.5 T...Carbon dioxide pressure-broadened ro-vibrational transitions belonging to thev^2＋3v^3 band of H2160 have been measured with a sensitive cavity ring-down spectrometer. Water vapor of relatively low pressures （〈0.5 Torr） was used to limit the self-collisions among water molecules. After the calibration using the precise atomic transitions of Rb and a thermo- stabilized Fabry-Perot interferometer, 10^-5 cm^-1 frequency accuracy has been achieved. Line parameters are derived from least-squares fitting of the spectra using the ＂soft＂ collision model. The retrieved line parameters can be applied in the study of water absorption in the CO2-rich atmospheres of planets like Venus and Mars.展开更多
Skeletonema tropicum is regarded as a species with an affinity to warm waters and it has never been reported in seas where temperatures drop below 11℃ in winter. Previous studies in China reported that S. tropicum wa...Skeletonema tropicum is regarded as a species with an affinity to warm waters and it has never been reported in seas where temperatures drop below 11℃ in winter. Previous studies in China reported that S. tropicum was restricted to subtropical and warm temperate seas （East and South China Seas）, but the species was recently found during August cruises of 2009 and 2010 in Jiaozhou Bay, Yellow Sea, located several hundred kilometers to the north. Here, winter water temperatures often drop below 5℃. Identification of S. tropicum was confirmed under light and scanning electronic microscopes and maximum cell abundance in Jiaozhou Bay was estimated as 1.73× 10^4 celI/L. This record of S. tropicum in Jiaozhou Bay represents a significant northward expansion in the geographic range of the species. Ship ballast water was identified as a possible carrier of S. tropicum from southern places along Chinese coastline, and in addition, thermal pollution from local power stations and seawater desalination plants may provide suitable conditions for species over-wintering.展开更多
As a new kind of air-hardening soil reinforcement material,polymer is being widely applied in river-bank slope reinforcement and ecological slope protection area.Thus,more attention should be paid to study the charact...As a new kind of air-hardening soil reinforcement material,polymer is being widely applied in river-bank slope reinforcement and ecological slope protection area.Thus,more attention should be paid to study the characteristics of reinforced soil after immersion.In this study,water-induced changes in strength characteristics of sand reinforced with polymer and fibers were reported.Several factors,including polymer content(1%,2%,3%and 4%by weight of dry sand),immersion time(6,12,24 and 48 h),dry density(1.40,1.45,1.50,1.55 and 1.60 g/cm^(3),)and fiber content(0.2%,0.4%,0.6%and 0.8%by weight of dry sand)which may influence the strength characteristics of reinforced sand after immersion were analyzed.The microstructure of reinforced sand was analyzed with nuclear magnetic resonance(NMR)and scanning electron microscope(SEM).Experimental results indicate that the compressive strength increases with the increase of polymer content and decreases with the increase of immersion time;the softening coefficients decrease with the increase of the polymer content and immersion time and increase with an increment in density and fiber content.Fiber plays an active role in reducing water-induced loss of strength at 0.6%content.展开更多
A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed...A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed at varying wave heightsunder both conditions of liquefied and stable seabed. The total pressures equal to soilpressures and pore water pressures were measured and analyzed at each depth. Theresults showed that the liquefied seabed had little difference from the stable seabed onthe peak pressures. However, the pressure amplitude of the liquefied soil increased byseveral to 10 times and decreased faster with increasing soil depths, compared with thestable soil. According to the experiments and further analysis, an empirical equationbetween pressure amplitude of the liquefied soil and wave parameters was put forwardunder the flume test. The results provide a valuable reference for engineeringapplications.展开更多
Effects of heat softening on the initiation of slide surface(shear banding) in clayey slopes during fast deformation were discussed.Controlling equations considering heat,pore pressure and mechanical movement were pre...Effects of heat softening on the initiation of slide surface(shear banding) in clayey slopes during fast deformation were discussed.Controlling equations considering heat,pore pressure and mechanical movement were presented.By perturbation method,the instability condition of localized zone(i.e.criterion for initiation of shear banding) for thermal related soils,such as clayey slope,was obtained.It is shown that slide surface initiates once the thermal-softening effects overcome the strain-hardening effects whether it is adiabatic or not.Without strain hardening effects,strain rate hardening obviously plays a role in initiation of shear band.During initiating process,heat is trapped inside the shear band,which leads rapidly to a pore pressure increase and fast loss of strength.The localized shear strain is concentrated in a narrow zone with a width of several centimeters at most and increases fast.This zone forms the sliding surface.Temperature can increase more than 2?C,pore pressure can increase 160% in about 0.1s inside this zone.These changes cause the fast decrease in friction-coefficient by about 36% over the initial value.That is how shear band initiated and developed in clayey slopes.展开更多
In this research,a commercial CFD code ＂Fluent＂ was applied to optimization of bulbous bow shape for a non ballast water ships（NBS）.The ship was developed at the Laboratory of the authors in Osaka Prefecture Unive...In this research,a commercial CFD code ＂Fluent＂ was applied to optimization of bulbous bow shape for a non ballast water ships（NBS）.The ship was developed at the Laboratory of the authors in Osaka Prefecture University,Japan.At first,accuracy of the CFD code was validated by comparing the CFD results with experimental results at towing tank of Osaka Prefecture University.In the optimizing process,the resistances acting on ships in calm water and in regular head waves were defined as the object function.Following features of bulbous bow shapes were considered as design parameters： volume of bulbous bow,height of its volume center,angle of bow bottom,and length of bulbous bow.When referring to the computed results given by the CFD like resistance,pressure and wave pattern made by ships in calm water and in waves,an optimal bow shape for ships was discovered by comparing the results in the series of bow shapes.In the computation on waves,the ship is in fully captured condition because shorter waves,λ/Lpp 0.6,are assumed.展开更多
Compressed Sensing （CS） offers a method to solve the channel estimation problems for an underwater acoustic system, based on the existence of a sparse representation of the treated signal and an overcomplete diction...Compressed Sensing （CS） offers a method to solve the channel estimation problems for an underwater acoustic system, based on the existence of a sparse representation of the treated signal and an overcomplete dictionary with a set of non-orthogonal bases. In this paper, we proposed a new approach to optimize dictionaries by decreasing the average measure of the mutual coherence of the effective dictionary. A fixed link between the average mutual coherence and the CS perforrmnce is indicated by designing three factors： operating bandwidth, the number of pilot subcarriers, and coherence bandwidth. Both the Orthogonal Matching Pursuit （OMP） and the Basis Pursuit De-Noising （BPDN） are compared to the Dantzig Selector （DS） for different Signal Noise Ratio （SNR） and shown to benefit from the newly designed dictionary. Nurnerical sinmlations and experimental data of an OFDM receiver are used to evaluate the proposed method in comparison with the conventional LeastSquare （LS） estirmtor. The results show that the dictionary with a better condition considerably improves the perforrmnce of the channel estimation.展开更多
The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 ...The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 °C were systematically investigated.The dissolution property of high-ferrite gibbsitic bauxite is increased by increasing the dissolution temperature and the Na OH concentration or decreasing the particle size of bauxite,which is easy to dissolve under atmospheric pressure.The kinetic equations of gibbsitic bauxites with different ferrite contents during the dissolution process at different temperatures for different times were established,and the corresponding activation energies were calculated.The ferrite in the gibbsitic bauxite reduces the dissolution speed and increases the activation energy of dissolution,the diffusion process of which is the rate-controlling step.展开更多
Abstract： This article introduces the development and application of the medium-pressure hydro-upgrading （MHUG） tech- nology developed by the Research Institute of Petroleum Processing （RIPP）. The MHUG technology...Abstract： This article introduces the development and application of the medium-pressure hydro-upgrading （MHUG） tech- nology developed by the Research Institute of Petroleum Processing （RIPP）. The MHUG technology based on the chemistry of diesel hydro-upgrading reactions has the advantages of flexible product slate and excellent product quality that can in- crease the cetane rating of diesel fuel up to more than 15 units. The hydrotreating and hydro-upgrading catalysts associated with the MHUG technology have outstanding performance to meet the demand of MHUG technology for hydro-saturation and selective ring-opening of aromatic rings. New MHUG process flow scheme can further increase the yield and selectivity of target products. Commercial application of multiple MHUG units has revealed that the MHUG technology designated for clean diesel production features good feedstock adaptability and operating stability.展开更多
Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix...Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix polymer of coating. In order to obtain such information, the authors investigated the penetration of active substances to the polymer from cross section of specimens introduced by SAICAS （surface and interracial cutting analysis system）, followed by FT-IR-ATR （Fourier transform infrared and attenuated total reflectance） spectroscopy analysis from Z direction of cross section. The corrosion test of coating panels by these active substances （control as artificial seawater） has been conducted for 120 days. The results show that the depth profile of each active substance is around few dozens of micrometers from coating surface. The criteria of corrosion test cannot be determined by these results due to lacking in actual corrosion data immersed for 15 years under active substances. However, the authors evaluated the effect on ballast tank coating systems by active substances using analytical methods of SAICAS and FT-IR-ATR spectroscopy.展开更多
The surface feature of contaminative oil is analysed and the theory of carrier purification technology for hydraulic oil is put forward. Experiments have been done in laboratory. The main performance of the purified o...The surface feature of contaminative oil is analysed and the theory of carrier purification technology for hydraulic oil is put forward. Experiments have been done in laboratory. The main performance of the purified oil has got to a level of new oil.展开更多
The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of soun...The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of sound and altered rock, as well as to inhomogeneous soil layers that range from permeable gravel to soft clay sediments along the same tunnel. This article focuses on past experiences with tunnel-boring machines （TBMs） in Switzerland, and specifically on the aspects of soil conditioning during a passage through inhomogeneous soft soils. Most tunnels in the past were drilled using the slurry mode （SM）, in which the application of different additives was mainly limited to difficult zones of high permeability and stoppages for tool change and modification. For drillings with the less common earth pressure balanced mode （EPBM）, continuous foam conditioning and the additional use of polymer and bentonite have proven to be successful. The use of conditioning additives led to new challenges during separation of the slurries （for SM） and disposal of the excavated soil （for EPBM）. If the disposal of chemically treated soft soil mate- rial from the earth pressure balanced （EPB） drive in a manner that is compliant with environmental legislation is considered early on in the design and evaluation of the excavation mode, the EPBM can be beneficial for tunnels bored in glacial deposits.展开更多
Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the ...Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.展开更多
As the source of life,water is indispensable to human beings.Being aware of the water stress imposed by population growth,climate change,rapid urbanization,pollution,many scholars and decision makers argue that the es...As the source of life,water is indispensable to human beings.Being aware of the water stress imposed by population growth,climate change,rapid urbanization,pollution,many scholars and decision makers argue that the establishment of water rights and their system is the primary measure to tackle the water crisis problem.However,no consensus has been reached regarding the definition,nature and content of water rights both practically and academically.By examining the existing theories regarding water rights,this article tries to redefine the entitlements from the aspect of civil law.Meanwhile,it provides a system which classifies various rights by the four functions of usufruct.展开更多
In this research, determination of final slope for Maiduk copper mine of Kerman is investigated according to destabilizing factors of the mine. The development of the Maiduk Mine caused the extension of the mine area ...In this research, determination of final slope for Maiduk copper mine of Kerman is investigated according to destabilizing factors of the mine. The development of the Maiduk Mine caused the extension of the mine area and also withdrawal of its wall. So, optimizing possibility of mine slope is essential. Finally,the magnitude of optimized slopes for different walls of the mine in association with executive commands with better factors of safety is provided. The results show that the most important destabilizer factors are the presence of water and pore pressure in the faults and the main joints. With the omission of pore pressure, mine wall for the designed depth is quite stable. This requires a drainage pattern in the lifetime of the mine. In an optimistic point of view, the minimum factor of safety of the wall will be 2.81 even without drainage. This conclusion allows optimizing the slope to its maximum magnitude of 51 degree. With the pessimistic engineering judgment and with the higher SF, the magnitude of the slope is optimized to 47 degree.展开更多
East Asian summer rainfall is affected by both the continental northern East Asian low （NEAL） and the western North Pacific subtropical high （WNPSH） in the lower troposphere. This study investigates the joint effe...East Asian summer rainfall is affected by both the continental northern East Asian low （NEAL） and the western North Pacific subtropical high （WNPSH） in the lower troposphere. This study investigates the joint effect of the two circulation factors on East Asian summer rainfall. It is found that the rainfall in East Asia behaves differently in the years with in-phase and out-of-phase variation between the NEAL and WNPSH. When the NEAL and WNPSH vary in phase, i.e. when they are both stronger, the rainfall anomaly shows a dipole pattern in East Asia and displays opposite changes between north and south of 30°N. When the two circulation factors vary out of phase, the rainfall anomaly is concentrated in the Yangtze River valley.展开更多
基金Projects(2010SK3172,2015JC3005)supported by the Key Program of Science and Technology Project of Hunan Province,China
文摘Copper, iron and cobalt based pre-alloyed powders for diamond tools were prepared by ultrahigh pressure water atomization（UPWA） process. Pre-alloyed powders prepared by different processes including UPWA, conventional water atomization （CWA） and elemental metal mechanical mixing （EMMM） were sintered to segments and then compared in mechanical properties, holding force between matrix and diamond, fracture morphology of blank and sintering diamond section containing matrix. The results showed that the pre-alloyed powder prepared by UPWA exhibits the best mechanical properties including the relative density, the hardness and the bending strength of matrix sinteredsegment. Sintered segments fractography of UPWA pre-alloyed powder indicatesmechanical mosaic strength and chemical bonding force between the pre-alloyed powder and the diamond, leading to the great increase in the holding force between matrix and diamond. The mechanical performance andthe service life of diamond tools were greatly improved by UPWA pre-alloyed powders.
基金Project supported by the Chinese Academy of Sciences and Max-Planck Foundation (No. 40071055) and the National Natural Science Foundation of China (No. 40071044)
文摘Undisturbed soil cores were taken from different slope positions （upslope, backslope and footslope） and soil depths （0-15, 20-35 and 100-115 cm） in a soil catena derived from Quaternary red clay to determine the spatial changes in soil strength along the eroded slope and to ewluate an indicator to determine soil strength during compaction. Precompression stress, as an indicator of soil strength, significantly increased from topsoil layer to subsoil layer （P 〈0.05） and was affected by slope position. In the subsoil layer （20-35 cm）, the precompression stress at the footslope position was significantly greater than at the backslope and upslope positions （P 〈0.05）, while there were no significant differences at 0-15 and 100-115 cm. Precompression stress followed the spatial wriation of soil clay content with soil depth and had a significant linear relationship with soil porosity （r^2 = 0.40, P 〈 0.01）. Also, soil cohesion increased with increasing soil clay content. The precompression stress was significantly related to the applied stress corresponding to the highest change of pore water pressure （r^2 = 0.69, P 〈 0.01）. These results suggested that soil strength induced by soil erosion and soil management wried spatially along the slope and the maximum change in pore water pressure during compaction could be an easy indicator to describe soil strength.
基金ACKNOWLEDGMENTS This work is supported by the National Natural Science Foundation （No.21225314 and No.20903085）, the National Basic Research Program of China （No.2013CB834602） and the Fundamental Research Funds for the Central Universities.
文摘Carbon dioxide pressure-broadened ro-vibrational transitions belonging to thev^2＋3v^3 band of H2160 have been measured with a sensitive cavity ring-down spectrometer. Water vapor of relatively low pressures （〈0.5 Torr） was used to limit the self-collisions among water molecules. After the calibration using the precise atomic transitions of Rb and a thermo- stabilized Fabry-Perot interferometer, 10^-5 cm^-1 frequency accuracy has been achieved. Line parameters are derived from least-squares fitting of the spectra using the ＂soft＂ collision model. The retrieved line parameters can be applied in the study of water absorption in the CO2-rich atmospheres of planets like Venus and Mars.
基金Supported by the National Natural Science Foundation of China (Nos.40976097, 41006040)the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05130703)the Marine Special Scientific Fund for Non-profit Public Industry (No. 200805031)
文摘Skeletonema tropicum is regarded as a species with an affinity to warm waters and it has never been reported in seas where temperatures drop below 11℃ in winter. Previous studies in China reported that S. tropicum was restricted to subtropical and warm temperate seas （East and South China Seas）, but the species was recently found during August cruises of 2009 and 2010 in Jiaozhou Bay, Yellow Sea, located several hundred kilometers to the north. Here, winter water temperatures often drop below 5℃. Identification of S. tropicum was confirmed under light and scanning electronic microscopes and maximum cell abundance in Jiaozhou Bay was estimated as 1.73× 10^4 celI/L. This record of S. tropicum in Jiaozhou Bay represents a significant northward expansion in the geographic range of the species. Ship ballast water was identified as a possible carrier of S. tropicum from southern places along Chinese coastline, and in addition, thermal pollution from local power stations and seawater desalination plants may provide suitable conditions for species over-wintering.
基金Project(41472241)supported by the National Natural Science Foundation of ChinaProject(KJXM2019028)supported by the Natural Resources Science and Technology Project of Jiangsu Province,ChinaProject(2019B17314)supported by the Fundamental Research Funds for the Central Universities,China。
文摘As a new kind of air-hardening soil reinforcement material,polymer is being widely applied in river-bank slope reinforcement and ecological slope protection area.Thus,more attention should be paid to study the characteristics of reinforced soil after immersion.In this study,water-induced changes in strength characteristics of sand reinforced with polymer and fibers were reported.Several factors,including polymer content(1%,2%,3%and 4%by weight of dry sand),immersion time(6,12,24 and 48 h),dry density(1.40,1.45,1.50,1.55 and 1.60 g/cm^(3),)and fiber content(0.2%,0.4%,0.6%and 0.8%by weight of dry sand)which may influence the strength characteristics of reinforced sand after immersion were analyzed.The microstructure of reinforced sand was analyzed with nuclear magnetic resonance(NMR)and scanning electron microscope(SEM).Experimental results indicate that the compressive strength increases with the increase of polymer content and decreases with the increase of immersion time;the softening coefficients decrease with the increase of the polymer content and immersion time and increase with an increment in density and fiber content.Fiber plays an active role in reducing water-induced loss of strength at 0.6%content.
基金supported by National Natural Science Foundation of China (Grant No.41576039)the Scientific Research Projects of Marine Public Welfare Industry (Grant No.201305026)
文摘A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed at varying wave heightsunder both conditions of liquefied and stable seabed. The total pressures equal to soilpressures and pore water pressures were measured and analyzed at each depth. Theresults showed that the liquefied seabed had little difference from the stable seabed onthe peak pressures. However, the pressure amplitude of the liquefied soil increased byseveral to 10 times and decreased faster with increasing soil depths, compared with thestable soil. According to the experiments and further analysis, an empirical equationbetween pressure amplitude of the liquefied soil and wave parameters was put forwardunder the flume test. The results provide a valuable reference for engineeringapplications.
基金funded by the National Natural Science Foundation of China (Grant No. 11272314 No. 51239010)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20133514110004)the Research Project of Chinese Ministry of Transport (Grant No. 201331849A130)
文摘Effects of heat softening on the initiation of slide surface(shear banding) in clayey slopes during fast deformation were discussed.Controlling equations considering heat,pore pressure and mechanical movement were presented.By perturbation method,the instability condition of localized zone(i.e.criterion for initiation of shear banding) for thermal related soils,such as clayey slope,was obtained.It is shown that slide surface initiates once the thermal-softening effects overcome the strain-hardening effects whether it is adiabatic or not.Without strain hardening effects,strain rate hardening obviously plays a role in initiation of shear band.During initiating process,heat is trapped inside the shear band,which leads rapidly to a pore pressure increase and fast loss of strength.The localized shear strain is concentrated in a narrow zone with a width of several centimeters at most and increases fast.This zone forms the sliding surface.Temperature can increase more than 2?C,pore pressure can increase 160% in about 0.1s inside this zone.These changes cause the fast decrease in friction-coefficient by about 36% over the initial value.That is how shear band initiated and developed in clayey slopes.
文摘In this research,a commercial CFD code ＂Fluent＂ was applied to optimization of bulbous bow shape for a non ballast water ships（NBS）.The ship was developed at the Laboratory of the authors in Osaka Prefecture University,Japan.At first,accuracy of the CFD code was validated by comparing the CFD results with experimental results at towing tank of Osaka Prefecture University.In the optimizing process,the resistances acting on ships in calm water and in regular head waves were defined as the object function.Following features of bulbous bow shapes were considered as design parameters： volume of bulbous bow,height of its volume center,angle of bow bottom,and length of bulbous bow.When referring to the computed results given by the CFD like resistance,pressure and wave pattern made by ships in calm water and in waves,an optimal bow shape for ships was discovered by comparing the results in the series of bow shapes.In the computation on waves,the ship is in fully captured condition because shorter waves,λ/Lpp 0.6,are assumed.
基金Acknowledgements This work was supported by the National Science Foundation of China under Grant No. 60976065. The authors would like to thank the anonymous reviewers for comments that helped improve the paper.
文摘Compressed Sensing （CS） offers a method to solve the channel estimation problems for an underwater acoustic system, based on the existence of a sparse representation of the treated signal and an overcomplete dictionary with a set of non-orthogonal bases. In this paper, we proposed a new approach to optimize dictionaries by decreasing the average measure of the mutual coherence of the effective dictionary. A fixed link between the average mutual coherence and the CS perforrmnce is indicated by designing three factors： operating bandwidth, the number of pilot subcarriers, and coherence bandwidth. Both the Orthogonal Matching Pursuit （OMP） and the Basis Pursuit De-Noising （BPDN） are compared to the Dantzig Selector （DS） for different Signal Noise Ratio （SNR） and shown to benefit from the newly designed dictionary. Nurnerical sinmlations and experimental data of an OFDM receiver are used to evaluate the proposed method in comparison with the conventional LeastSquare （LS） estirmtor. The results show that the dictionary with a better condition considerably improves the perforrmnce of the channel estimation.
基金Projects(51104041,51174054,51374065)supported by the National Natural Science Foundation of ChinaProject(N130402010)supported by the Fundamental Research Funds for the Central Universities of China
文摘The dissolution property of high-ferrite gibbsitic bauxite and the effect of ferrite content on the dissolution kinetics of gibbsitic bauxites in sodium hydroxide solution under atmospheric pressure from 50 to 90 °C were systematically investigated.The dissolution property of high-ferrite gibbsitic bauxite is increased by increasing the dissolution temperature and the Na OH concentration or decreasing the particle size of bauxite,which is easy to dissolve under atmospheric pressure.The kinetic equations of gibbsitic bauxites with different ferrite contents during the dissolution process at different temperatures for different times were established,and the corresponding activation energies were calculated.The ferrite in the gibbsitic bauxite reduces the dissolution speed and increases the activation energy of dissolution,the diffusion process of which is the rate-controlling step.
文摘Abstract： This article introduces the development and application of the medium-pressure hydro-upgrading （MHUG） tech- nology developed by the Research Institute of Petroleum Processing （RIPP）. The MHUG technology based on the chemistry of diesel hydro-upgrading reactions has the advantages of flexible product slate and excellent product quality that can in- crease the cetane rating of diesel fuel up to more than 15 units. The hydrotreating and hydro-upgrading catalysts associated with the MHUG technology have outstanding performance to meet the demand of MHUG technology for hydro-saturation and selective ring-opening of aromatic rings. New MHUG process flow scheme can further increase the yield and selectivity of target products. Commercial application of multiple MHUG units has revealed that the MHUG technology designated for clean diesel production features good feedstock adaptability and operating stability.
文摘Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix polymer of coating. In order to obtain such information, the authors investigated the penetration of active substances to the polymer from cross section of specimens introduced by SAICAS （surface and interracial cutting analysis system）, followed by FT-IR-ATR （Fourier transform infrared and attenuated total reflectance） spectroscopy analysis from Z direction of cross section. The corrosion test of coating panels by these active substances （control as artificial seawater） has been conducted for 120 days. The results show that the depth profile of each active substance is around few dozens of micrometers from coating surface. The criteria of corrosion test cannot be determined by these results due to lacking in actual corrosion data immersed for 15 years under active substances. However, the authors evaluated the effect on ballast tank coating systems by active substances using analytical methods of SAICAS and FT-IR-ATR spectroscopy.
文摘The surface feature of contaminative oil is analysed and the theory of carrier purification technology for hydraulic oil is put forward. Experiments have been done in laboratory. The main performance of the purified oil has got to a level of new oil.
文摘The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of sound and altered rock, as well as to inhomogeneous soil layers that range from permeable gravel to soft clay sediments along the same tunnel. This article focuses on past experiences with tunnel-boring machines （TBMs） in Switzerland, and specifically on the aspects of soil conditioning during a passage through inhomogeneous soft soils. Most tunnels in the past were drilled using the slurry mode （SM）, in which the application of different additives was mainly limited to difficult zones of high permeability and stoppages for tool change and modification. For drillings with the less common earth pressure balanced mode （EPBM）, continuous foam conditioning and the additional use of polymer and bentonite have proven to be successful. The use of conditioning additives led to new challenges during separation of the slurries （for SM） and disposal of the excavated soil （for EPBM）. If the disposal of chemically treated soft soil mate- rial from the earth pressure balanced （EPB） drive in a manner that is compliant with environmental legislation is considered early on in the design and evaluation of the excavation mode, the EPBM can be beneficial for tunnels bored in glacial deposits.
基金Project(2011GH561685)supported by the China Torch Program
文摘Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.
基金supported by the Projects of Southwestern University of Finance and Economics (Grant No 2010XG026)the Innovative Talents Training Fund of Southwestern University of Finance and Economics
文摘As the source of life,water is indispensable to human beings.Being aware of the water stress imposed by population growth,climate change,rapid urbanization,pollution,many scholars and decision makers argue that the establishment of water rights and their system is the primary measure to tackle the water crisis problem.However,no consensus has been reached regarding the definition,nature and content of water rights both practically and academically.By examining the existing theories regarding water rights,this article tries to redefine the entitlements from the aspect of civil law.Meanwhile,it provides a system which classifies various rights by the four functions of usufruct.
文摘In this research, determination of final slope for Maiduk copper mine of Kerman is investigated according to destabilizing factors of the mine. The development of the Maiduk Mine caused the extension of the mine area and also withdrawal of its wall. So, optimizing possibility of mine slope is essential. Finally,the magnitude of optimized slopes for different walls of the mine in association with executive commands with better factors of safety is provided. The results show that the most important destabilizer factors are the presence of water and pore pressure in the faults and the main joints. With the omission of pore pressure, mine wall for the designed depth is quite stable. This requires a drainage pattern in the lifetime of the mine. In an optimistic point of view, the minimum factor of safety of the wall will be 2.81 even without drainage. This conclusion allows optimizing the slope to its maximum magnitude of 51 degree. With the pessimistic engineering judgment and with the higher SF, the magnitude of the slope is optimized to 47 degree.
基金supported by the National Natural Science Foundation of China[grant number 41375086]
文摘East Asian summer rainfall is affected by both the continental northern East Asian low （NEAL） and the western North Pacific subtropical high （WNPSH） in the lower troposphere. This study investigates the joint effect of the two circulation factors on East Asian summer rainfall. It is found that the rainfall in East Asia behaves differently in the years with in-phase and out-of-phase variation between the NEAL and WNPSH. When the NEAL and WNPSH vary in phase, i.e. when they are both stronger, the rainfall anomaly shows a dipole pattern in East Asia and displays opposite changes between north and south of 30°N. When the two circulation factors vary out of phase, the rainfall anomaly is concentrated in the Yangtze River valley.
