Rare earth elements are strategic commodities in many countries, and an important resource for the growing modern technology industry. As such, there is an increasing interest for development of rare earth element pro...Rare earth elements are strategic commodities in many countries, and an important resource for the growing modern technology industry. As such, there is an increasing interest for development of rare earth element processing, and this work is a part of further development of chromatography as a rare earth element separation process method. Process optimization is pivotal for process development, and it is common that several competing objectives must be regarded. Chromatographic separation processes often consider competing objectives, such as productivity, yield, pool concentration and modifier consumption, which leads to Pareto optimal solutions. Adding robustness to a process is of great importance to account for process disturbances and uncertainties but generally comes with reduced performance of the other process objectives as a trade off. In this study, a model-based robust multi-objective optimization was carried out for batch-wise chromatographic separation of the rare earth elements samarium, europium and gadolinium, which was considered highly un-robust due to the neighbouring peaks proximity to the product pooling horizon. The results from the robust optimization were used to chart the required operation point changes for keeping the amount of failed batches at an acceptable level when a certain level of process disturbance was introduced. The loss of process performance due to the gained robustness was found to be in the range of 10% - 20% reduced productivity when comparing the robust and un-robust Pareto solutions at Pareto points with identical yield. The methodology presented shows how to increase robustness to a highly un-robust system while still keeping multiple objectives at their optima.展开更多
It is well-known that the asteroids in the main belt trapped in the 3：1 Mean Motion Resonance （MMR） with Jupiter （at semi-major axes -2.5 AU） are few in number, forming one of the so-called Kirkwood Gaps. Wisdom ...It is well-known that the asteroids in the main belt trapped in the 3：1 Mean Motion Resonance （MMR） with Jupiter （at semi-major axes -2.5 AU） are few in number, forming one of the so-called Kirkwood Gaps. Wisdom pointed out that chaotic motion of such aster- oids can increase their eccentricities and make them approach and cross the orbit of Mars （or even the Earth）. We numerically investigated the orbital evolution of the asteroids involved in 3：1 MMR （NEOs） over millions of years and revisited the dynamical mechanisms of trasporitng such asteroids into the NEO region. The results show that the dynamical evolution of the asteroids around 2.5 AU is mainly dominated by the 3：1 resonance, the v5 and v6 secular resonances and the Kozai resonance, and these bodies can evolve into NEOs through several of the dynamical mechanisms, so indicating possible dynamical origin of the NEOs.展开更多
Under the framework of observational campaigns organized by the GAIA Follow Up Network for Solar System Objects, three near Earth asteroids, 367943 Duende, 99942 Apophis and 2013 TV135, were observed with the Lijiang ...Under the framework of observational campaigns organized by the GAIA Follow Up Network for Solar System Objects, three near Earth asteroids, 367943 Duende, 99942 Apophis and 2013 TV135, were observed with the Lijiang 2.4m telescope administered by Yunnan Observatories. The software package PRISM was used to calibrate the CCD fields and measure the positions of 99942 Apophis and 2013 TV135, and our own software was used for 367943 Duende. A comparison of the results show that the ephemerides of INPOP10a and JPL are consistent for 99942 Apophis and 2013 TV135, however, they are quite inconsistent for 367943 Duende. Moreover, we have found that differences between the mean values in the ephemerides of INPOP10a and JPL are about 72＂ and -199＂ in right ascension and declination respectively for 367943 Duende. Moreover, the ephemeris published by JPL is reliable in terms of the mean observed-minus-calculated （O - C） residuals in right ascension and declination of about 2.72＂ and 1.49＂ respectively.展开更多
The French astronomer Charles Messier (1730- 1817) compiled a catalogue [1] of astronomical objects which reached109 innumber after additions by later astronomers were added. The catalogue contains galaxies, emission ...The French astronomer Charles Messier (1730- 1817) compiled a catalogue [1] of astronomical objects which reached109 innumber after additions by later astronomers were added. The catalogue contains galaxies, emission nebulae, a supernova remnant, a double star, globular clusters, open clusters, an asterism, a star cloud, and planetary nebulae. While the objective of Messier in compiling the catalogue was to guide comet hunters not to be confused by his objects which he thought looked like comets [2], the Messier Catalogue as it later became known became a standard guide to astronomers for a study of the sky’s “greatest hits” or the best samples of objects which can be observed and studied. This paper explores the value of the Messier Catalogue in the teaching of Astronomy and Earth Science. The range of objects is wide and contains some of the best examples of their type. The teaching method I propose is the actual observations of the objects through a telescope, with the corresponding explanation. Some principles which will be covered through this process are stellar evolution from the birth and death of stars, galaxy types, formation of galaxies, galactic interactions, life in the Universe, cosmology, and our place in the Universe.展开更多
文摘Rare earth elements are strategic commodities in many countries, and an important resource for the growing modern technology industry. As such, there is an increasing interest for development of rare earth element processing, and this work is a part of further development of chromatography as a rare earth element separation process method. Process optimization is pivotal for process development, and it is common that several competing objectives must be regarded. Chromatographic separation processes often consider competing objectives, such as productivity, yield, pool concentration and modifier consumption, which leads to Pareto optimal solutions. Adding robustness to a process is of great importance to account for process disturbances and uncertainties but generally comes with reduced performance of the other process objectives as a trade off. In this study, a model-based robust multi-objective optimization was carried out for batch-wise chromatographic separation of the rare earth elements samarium, europium and gadolinium, which was considered highly un-robust due to the neighbouring peaks proximity to the product pooling horizon. The results from the robust optimization were used to chart the required operation point changes for keeping the amount of failed batches at an acceptable level when a certain level of process disturbance was introduced. The loss of process performance due to the gained robustness was found to be in the range of 10% - 20% reduced productivity when comparing the robust and un-robust Pareto solutions at Pareto points with identical yield. The methodology presented shows how to increase robustness to a highly un-robust system while still keeping multiple objectives at their optima.
基金Supported by the National Natural Science Foundation of China.
文摘It is well-known that the asteroids in the main belt trapped in the 3：1 Mean Motion Resonance （MMR） with Jupiter （at semi-major axes -2.5 AU） are few in number, forming one of the so-called Kirkwood Gaps. Wisdom pointed out that chaotic motion of such aster- oids can increase their eccentricities and make them approach and cross the orbit of Mars （or even the Earth）. We numerically investigated the orbital evolution of the asteroids involved in 3：1 MMR （NEOs） over millions of years and revisited the dynamical mechanisms of trasporitng such asteroids into the NEO region. The results show that the dynamical evolution of the asteroids around 2.5 AU is mainly dominated by the 3：1 resonance, the v5 and v6 secular resonances and the Kozai resonance, and these bodies can evolve into NEOs through several of the dynamical mechanisms, so indicating possible dynamical origin of the NEOs.
基金Supported by the National Natural Science Foundation of China
文摘Under the framework of observational campaigns organized by the GAIA Follow Up Network for Solar System Objects, three near Earth asteroids, 367943 Duende, 99942 Apophis and 2013 TV135, were observed with the Lijiang 2.4m telescope administered by Yunnan Observatories. The software package PRISM was used to calibrate the CCD fields and measure the positions of 99942 Apophis and 2013 TV135, and our own software was used for 367943 Duende. A comparison of the results show that the ephemerides of INPOP10a and JPL are consistent for 99942 Apophis and 2013 TV135, however, they are quite inconsistent for 367943 Duende. Moreover, we have found that differences between the mean values in the ephemerides of INPOP10a and JPL are about 72＂ and -199＂ in right ascension and declination respectively for 367943 Duende. Moreover, the ephemeris published by JPL is reliable in terms of the mean observed-minus-calculated （O - C） residuals in right ascension and declination of about 2.72＂ and 1.49＂ respectively.
文摘The French astronomer Charles Messier (1730- 1817) compiled a catalogue [1] of astronomical objects which reached109 innumber after additions by later astronomers were added. The catalogue contains galaxies, emission nebulae, a supernova remnant, a double star, globular clusters, open clusters, an asterism, a star cloud, and planetary nebulae. While the objective of Messier in compiling the catalogue was to guide comet hunters not to be confused by his objects which he thought looked like comets [2], the Messier Catalogue as it later became known became a standard guide to astronomers for a study of the sky’s “greatest hits” or the best samples of objects which can be observed and studied. This paper explores the value of the Messier Catalogue in the teaching of Astronomy and Earth Science. The range of objects is wide and contains some of the best examples of their type. The teaching method I propose is the actual observations of the objects through a telescope, with the corresponding explanation. Some principles which will be covered through this process are stellar evolution from the birth and death of stars, galaxy types, formation of galaxies, galactic interactions, life in the Universe, cosmology, and our place in the Universe.
