Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of t...Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of Al-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in Al-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two Al-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for Al-12Si-1.7Fe alloy. And they are 82% and 18% for Al-12Si-3.4Fe alloy, respectively.展开更多
To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoir...To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.展开更多
A desulphurization experimental study under the effects of compounding physical force fields has been de- scribed for < 0.5 mm fine particles of high sulfur coal. A statistical test using the Box-Behnken Design of ...A desulphurization experimental study under the effects of compounding physical force fields has been de- scribed for < 0.5 mm fine particles of high sulfur coal. A statistical test using the Box-Behnken Design of experiments was conducted to evaluate the effects of individual operating variables and their interactions on desulfurization of fine coal using an enhanced centrifugal gravity separator. A model describing the relation between desulphurization effi- ciency of pyrite sulfur and different operating variables has been designed. The interactions between different factors on the pyrite sulfur desulphurization efficiency have been analysed. The optimal test conditions for desulfarization are ex- tracted from the Design-Expert 6.0 software. Finally, the advantage of centrifugal gravity separation for fine coal is pointed out.展开更多
The main faults of dish centrifugal separator's helical gear are described inthis paper. In order to diagnose the DRJ-460 dish centrifugal separator correctly, the vibration istested with a helical gear under both...The main faults of dish centrifugal separator's helical gear are described inthis paper. In order to diagnose the DRJ-460 dish centrifugal separator correctly, the vibration istested with a helical gear under both normal and abnormal conditions. After comparing severalgeneral methods of the gear's fault feature extraction, a new convenient and effective method ispresented on the basis of analyzing the vibration spectrum under different rotary velocities.展开更多
Annular centrifugal contactors (ACCs) have many advantages and are recognized as key solvent-extraction equipment for the future reprocessing of spent nuclear fuel (RSNF). To successfully design and operate ACCs for R...Annular centrifugal contactors (ACCs) have many advantages and are recognized as key solvent-extraction equipment for the future reprocessing of spent nuclear fuel (RSNF). To successfully design and operate ACCs for RSNF, it is necessary to understand the hydrodynamic characteristics of the extraction systems in ACCs. The phase ratio (R = Vaq/Vorg, A/O) and liquid holdup volume (V) of the ACC are important hydrodynamic characteristics. In this study, a liquid-fast-separation method was used to systematically investigate the effects of the operational and structural parameters on the V and R (A/O) of a φ20 ACC by using a 30%TBP/kerosene- HNO3 solution system. The results showed that the operational and structural parameters had different effects on the V and R (A/O) of the mixing and separating zones of the ACC, respectively. For the most frequently used structural parameters of the φ20 ACC, when the rotor speed was 3500 r/min, the total flow rate was 2.0 L/h, and the flow ratio (A/O) was 1, the liquid holdup volumes in the mixing zone and rotor were 8.03 and 14.0 mL, respectively, and the phase ratios (A/O) of the mixing zone and separating zone were 0.96 and 1.43, respectively.展开更多
The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydrox...The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydroxyapatite nanoparticles （HAP） are doped with the luminescent rare earth elemeat Europium （Eu）, the panicle size becomes larger compared to pure HAP. Hence, a panicle size reduction is necessary to achieve similar experimental conditions when stbstituting pure HAP with luminescent HAP ： Eu nanoparticles to investigate particlecell-interactions in cell culture experiments. While the sedimentation process of particles in liquids and gels has been well described in literature, the separation of particles in dispersed colloids has not been studied, yet. In this study, the size depending separation and particle size redaction of a homogeneous dispersed nanoparticle sol by gravity and centrifugation were investigated. As the results showed, shorter time of centrifugation at higher speed can reduce the average particle size compared to the decline of the panicle concentation in the upper sol layer most efficiently. This ceatrifugation method has some similarity to the overspeeding technique which is commonly used to lower the transient time to reach the equilibrium of sedimentation.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(No.2012R1A1A2007476)the authors express their gratitude for the financial support from Korea University of Technology and Education
文摘Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of Al-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in Al-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two Al-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for Al-12Si-1.7Fe alloy. And they are 82% and 18% for Al-12Si-3.4Fe alloy, respectively.
基金EU Fifth Framework Program: Environment, Energy and Sustainable Development Research and Technological Development Activity of Generic Nature: The Fight Against Natural and Technological Hazards, Research Project QUAKER Under Contract No. EVG1–CT–2002–00064
文摘To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.
文摘A desulphurization experimental study under the effects of compounding physical force fields has been de- scribed for < 0.5 mm fine particles of high sulfur coal. A statistical test using the Box-Behnken Design of experiments was conducted to evaluate the effects of individual operating variables and their interactions on desulfurization of fine coal using an enhanced centrifugal gravity separator. A model describing the relation between desulphurization effi- ciency of pyrite sulfur and different operating variables has been designed. The interactions between different factors on the pyrite sulfur desulphurization efficiency have been analysed. The optimal test conditions for desulfarization are ex- tracted from the Design-Expert 6.0 software. Finally, the advantage of centrifugal gravity separation for fine coal is pointed out.
基金paper is sponsored by the Foundation of Donghua University
文摘The main faults of dish centrifugal separator's helical gear are described inthis paper. In order to diagnose the DRJ-460 dish centrifugal separator correctly, the vibration istested with a helical gear under both normal and abnormal conditions. After comparing severalgeneral methods of the gear's fault feature extraction, a new convenient and effective method ispresented on the basis of analyzing the vibration spectrum under different rotary velocities.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(No.IRT13026)the National 863 Program for Nuclear Fuel Cycling and Nuclear Safety Technology Project(No.2009AA050703)
文摘Annular centrifugal contactors (ACCs) have many advantages and are recognized as key solvent-extraction equipment for the future reprocessing of spent nuclear fuel (RSNF). To successfully design and operate ACCs for RSNF, it is necessary to understand the hydrodynamic characteristics of the extraction systems in ACCs. The phase ratio (R = Vaq/Vorg, A/O) and liquid holdup volume (V) of the ACC are important hydrodynamic characteristics. In this study, a liquid-fast-separation method was used to systematically investigate the effects of the operational and structural parameters on the V and R (A/O) of a φ20 ACC by using a 30%TBP/kerosene- HNO3 solution system. The results showed that the operational and structural parameters had different effects on the V and R (A/O) of the mixing and separating zones of the ACC, respectively. For the most frequently used structural parameters of the φ20 ACC, when the rotor speed was 3500 r/min, the total flow rate was 2.0 L/h, and the flow ratio (A/O) was 1, the liquid holdup volumes in the mixing zone and rotor were 8.03 and 14.0 mL, respectively, and the phase ratios (A/O) of the mixing zone and separating zone were 0.96 and 1.43, respectively.
文摘The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydroxyapatite nanoparticles （HAP） are doped with the luminescent rare earth elemeat Europium （Eu）, the panicle size becomes larger compared to pure HAP. Hence, a panicle size reduction is necessary to achieve similar experimental conditions when stbstituting pure HAP with luminescent HAP ： Eu nanoparticles to investigate particlecell-interactions in cell culture experiments. While the sedimentation process of particles in liquids and gels has been well described in literature, the separation of particles in dispersed colloids has not been studied, yet. In this study, the size depending separation and particle size redaction of a homogeneous dispersed nanoparticle sol by gravity and centrifugation were investigated. As the results showed, shorter time of centrifugation at higher speed can reduce the average particle size compared to the decline of the panicle concentation in the upper sol layer most efficiently. This ceatrifugation method has some similarity to the overspeeding technique which is commonly used to lower the transient time to reach the equilibrium of sedimentation.
