Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in th...Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in the present work.Detailed design for pilot DWC was performed and five control structures,i.e.composition control(CC),temperature control(TC),composition-temperature control(CC-TC),temperature difference control(TDC),double temperature difference control(DTDC)were proposed to circumvent feed disturbance.Sensitivity analysis and singular value decomposition(SVD)were used as criterion to select the controlled temperature locations in TC,CC-TC,TDC and DTDC control loops.The steady simulation result demonstrates that 25.7% and 30.2% duty can be saved for condenser and reboiler by substituting conventional column sequence with DWC,respectively.As for control structure selection,TC and TDC perform better than other three control schemes with smaller maximum deviation and shorter settling time.展开更多
Animal species are delimited by reproductive isolation mechanisms （RIMs）. Postzygotic RIMs are mainly products of genetic differences and thus their strength increases with elapsed divergence time. The relationship ...Animal species are delimited by reproductive isolation mechanisms （RIMs）. Postzygotic RIMs are mainly products of genetic differences and thus their strength increases with elapsed divergence time. The relationship between postzygotic repro- ductive isolation and genetic divergence, however, differs considerably among major clades of vertebrates. We reviewed the available literature providing empirical evidence of natural and/or experimental hybridization between distinct species of lizards （squamates except snakes）. We found that hybridization events are widely distributed among nearly all major lizard clades. The majority of research focuses on parthenogenetic species and/or polyploid hybrids in families Lacertidae, Teiidae and Gekkonidae. Homoploid bisexual hybrids are mainly reported within Lacertidae and Iguania groups. As a proxy of genetic divergence of the hybridizing taxa we adopted nucleotide sequence distance （HKY85） of mitochondrial cyt b gene. The upper limit of genetic di- vergence was similar with regard to both parthenogenetic and bisexual hybrids. Maximum values of these distances between hy- bridizing species of lizards approached 18%-21%, which is comparable to or even exceeds the corresponding values reported for other principal clades of vertebrates. In spite of this, F1 hybrids are typically at least partially fertile in lizards and thus genetic introgression between highly divergent species is possible. The relationship between the genetic distance and hybrid fertility was not found [Current Zoology 61 （1）： 155-180, 2015].展开更多
Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability o...Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability of divergent selection to pro- duce reproductive isolation in sympatry. Recombination breaks up favorable combinations of traits （＂adaptive suites＂） if indivi- dual traits are affected by different loci. Recombination also breaks up any association between traits under divergent selection and traits contributing to reproductive isolation. Thus, ecological speciation in the absence of preexisting barriers to gene flow is more likely when pleiotropy minimizes the number of loci involved. Here, we revisit research conducted by Carl Hubbs in the early 1900s on the effects of developmental rate on morphological traits in fishes. Hubbs＇ work provides a mechanism to explain how sympatric divergence by trophic polymorphism can occur despite the challenges of recombination. We consider the implica- tions of Hubbs＇ observations for ecological speciation with gene flow in fishes, as well as rapid evolution in captive fish popula- tions [Current Zoology 58 （1）： 21-34, 2012].展开更多
基金Supported by Open Research Project of State Key Laboratory of Chemical Engineering(Grant No.SKL-Ch E-16B06)
文摘Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in the present work.Detailed design for pilot DWC was performed and five control structures,i.e.composition control(CC),temperature control(TC),composition-temperature control(CC-TC),temperature difference control(TDC),double temperature difference control(DTDC)were proposed to circumvent feed disturbance.Sensitivity analysis and singular value decomposition(SVD)were used as criterion to select the controlled temperature locations in TC,CC-TC,TDC and DTDC control loops.The steady simulation result demonstrates that 25.7% and 30.2% duty can be saved for condenser and reboiler by substituting conventional column sequence with DWC,respectively.As for control structure selection,TC and TDC perform better than other three control schemes with smaller maximum deviation and shorter settling time.
文摘Animal species are delimited by reproductive isolation mechanisms （RIMs）. Postzygotic RIMs are mainly products of genetic differences and thus their strength increases with elapsed divergence time. The relationship between postzygotic repro- ductive isolation and genetic divergence, however, differs considerably among major clades of vertebrates. We reviewed the available literature providing empirical evidence of natural and/or experimental hybridization between distinct species of lizards （squamates except snakes）. We found that hybridization events are widely distributed among nearly all major lizard clades. The majority of research focuses on parthenogenetic species and/or polyploid hybrids in families Lacertidae, Teiidae and Gekkonidae. Homoploid bisexual hybrids are mainly reported within Lacertidae and Iguania groups. As a proxy of genetic divergence of the hybridizing taxa we adopted nucleotide sequence distance （HKY85） of mitochondrial cyt b gene. The upper limit of genetic di- vergence was similar with regard to both parthenogenetic and bisexual hybrids. Maximum values of these distances between hy- bridizing species of lizards approached 18%-21%, which is comparable to or even exceeds the corresponding values reported for other principal clades of vertebrates. In spite of this, F1 hybrids are typically at least partially fertile in lizards and thus genetic introgression between highly divergent species is possible. The relationship between the genetic distance and hybrid fertility was not found [Current Zoology 61 （1）： 155-180, 2015].
文摘Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability of divergent selection to pro- duce reproductive isolation in sympatry. Recombination breaks up favorable combinations of traits （＂adaptive suites＂） if indivi- dual traits are affected by different loci. Recombination also breaks up any association between traits under divergent selection and traits contributing to reproductive isolation. Thus, ecological speciation in the absence of preexisting barriers to gene flow is more likely when pleiotropy minimizes the number of loci involved. Here, we revisit research conducted by Carl Hubbs in the early 1900s on the effects of developmental rate on morphological traits in fishes. Hubbs＇ work provides a mechanism to explain how sympatric divergence by trophic polymorphism can occur despite the challenges of recombination. We consider the implica- tions of Hubbs＇ observations for ecological speciation with gene flow in fishes, as well as rapid evolution in captive fish popula- tions [Current Zoology 58 （1）： 21-34, 2012].
