The magnetic aftereffect (MAE) and the positron lifetime were measured at room temperature on the Fe_73.5Cu_1 Nb_3Si_13.5 B_9 alloy in as-cast and after annealing at temperature T_a in the range from 450 to 750℃ It w...The magnetic aftereffect (MAE) and the positron lifetime were measured at room temperature on the Fe_73.5Cu_1 Nb_3Si_13.5 B_9 alloy in as-cast and after annealing at temperature T_a in the range from 450 to 750℃ It was found that both the MAE and the positron lifetime decrease with increasing T_a when T_≤600℃. While Ta≥650℃, MAE is essentially suppressed, and two positron lifetimes appear.展开更多
Background:It has been suggested that adaptation to texture density only ever reduces,i.e.,never increases,perceived density,implying that density adaptation is‘uni-directional’and that texture density is coded as a...Background:It has been suggested that adaptation to texture density only ever reduces,i.e.,never increases,perceived density,implying that density adaptation is‘uni-directional’and that texture density is coded as a scalar attribute(Durgin&Huk,1997).However,we have recently shown that simultaneous density contrast,which describes the effect of a surround texture on the perceived density of a centre region,is‘bi-directional’-that is,not only do denser surrounds reduce perceived density of the center but sparser surrounds enhance it(Sun,Baker,&Kingdom,2016).Therefore,we decided to re-examine the directionality of density adaptation.Methods:We measured the density aftereffect in random dot patterns using a 2AFC matching procedure that established a point-of-subjective-equality(PSE)between an adapted test patch and an unadapted match patch.The adaptors and test were presented at the same position,either at top left or bottom right of the fixation.The match was presented at bottom left or top right correspondingly.These positions were fixed within a block and switched between blocks.Then,using sequential presentation,we measured the density aftereffect for a wide range of adaptor and test densities.Results:In the first experiment,we observed a unidirectional density aftereffect when test and match were presented simultaneously as in previous studies.However,when they were presented sequentially,bidirectionality was obtained.This bidirectional aftereffect remained when the presentation order of test and match was reversed(second experiment).In the third experiment,we used sequential presentation to measure the density aftereffect for a wide range of adaptor densities(0-73 dots/deg2)and test densities(1.6,6.4,and 25.6 dots/deg2).We found bidirectionality for all combinations of adaptor and test densities,consistent with our previous SDC results.Conclusions:In three experiments,we found that density adaptation is bidirectional when the test and match stimuli are presented sequentially.The unidirectional density adaptation reported in previous studies might have been due to effects arising from simultaneous presentation of test and match stimuli.Our evidence again supports the idea that there are density-selective channels in the visual system in line with our previous finding in SDC.展开更多
Economic system has phase characteristics during its developments, and certain decisions must be made during each stage, thus forming a multi-stage dynamic decision making economic system. As to this system, previous ...Economic system has phase characteristics during its developments, and certain decisions must be made during each stage, thus forming a multi-stage dynamic decision making economic system. As to this system, previous decisions have some aftereffects on its future developments, which has fundamentally contradicts the presupposition of programming methodology in Operation Research. In order to solve the problems arising from optimized theory research about the economic system, this paper defines the concept of dynamic system with aftereffects, points out the difference between its aftereffects and those of traditional stochastic processes, studies how the past decision effects on the value of optimal utility function, and gives an example on this base to illustrate its application in exploitation of oilfield.展开更多
A new experimental characterization is presented of time-,field-,and temperature-dependent dynamic effects in magnetization of a nanocomposite which displays slow decay.Field and temperature variations of irreversible...A new experimental characterization is presented of time-,field-,and temperature-dependent dynamic effects in magnetization of a nanocomposite which displays slow decay.Field and temperature variations of irreversible susceptibility,χirr,decay coefficient,S,fluctuation field,hf,and activation volume,V,have been calculated for the nanocomposite sample(Co_(80)Ni_(20))using a recently developed modified Preisach–Arrhenius(MPA)model.The sample is composed of non-interacting nanoparticles having negligible reversible magnetization.Non-Arrhenius behavior is observed in both the maximum decay coefficient,Smax,and the fluctuation field,hf,as a function of temperature T.The peak of both temperature curves are identical and occur at a critical temperature Tk of∼50 K,which agrees with our experimental results.Based on the effect of a temperature-dependent chemical potential on energy barrier,hf is studied for T<Tk and T≥Tk,respectively.A more complete MPA model that can predict the magnetization as function of time,field and temperature for a magnetic material with slow decay rates is proposed.This model uses a multi-variable analytical formula,m(ln(t),H,T),which incorporates the characteristic parameters.展开更多
文摘The magnetic aftereffect (MAE) and the positron lifetime were measured at room temperature on the Fe_73.5Cu_1 Nb_3Si_13.5 B_9 alloy in as-cast and after annealing at temperature T_a in the range from 450 to 750℃ It was found that both the MAE and the positron lifetime decrease with increasing T_a when T_≤600℃. While Ta≥650℃, MAE is essentially suppressed, and two positron lifetimes appear.
文摘Background:It has been suggested that adaptation to texture density only ever reduces,i.e.,never increases,perceived density,implying that density adaptation is‘uni-directional’and that texture density is coded as a scalar attribute(Durgin&Huk,1997).However,we have recently shown that simultaneous density contrast,which describes the effect of a surround texture on the perceived density of a centre region,is‘bi-directional’-that is,not only do denser surrounds reduce perceived density of the center but sparser surrounds enhance it(Sun,Baker,&Kingdom,2016).Therefore,we decided to re-examine the directionality of density adaptation.Methods:We measured the density aftereffect in random dot patterns using a 2AFC matching procedure that established a point-of-subjective-equality(PSE)between an adapted test patch and an unadapted match patch.The adaptors and test were presented at the same position,either at top left or bottom right of the fixation.The match was presented at bottom left or top right correspondingly.These positions were fixed within a block and switched between blocks.Then,using sequential presentation,we measured the density aftereffect for a wide range of adaptor and test densities.Results:In the first experiment,we observed a unidirectional density aftereffect when test and match were presented simultaneously as in previous studies.However,when they were presented sequentially,bidirectionality was obtained.This bidirectional aftereffect remained when the presentation order of test and match was reversed(second experiment).In the third experiment,we used sequential presentation to measure the density aftereffect for a wide range of adaptor densities(0-73 dots/deg2)and test densities(1.6,6.4,and 25.6 dots/deg2).We found bidirectionality for all combinations of adaptor and test densities,consistent with our previous SDC results.Conclusions:In three experiments,we found that density adaptation is bidirectional when the test and match stimuli are presented sequentially.The unidirectional density adaptation reported in previous studies might have been due to effects arising from simultaneous presentation of test and match stimuli.Our evidence again supports the idea that there are density-selective channels in the visual system in line with our previous finding in SDC.
文摘Economic system has phase characteristics during its developments, and certain decisions must be made during each stage, thus forming a multi-stage dynamic decision making economic system. As to this system, previous decisions have some aftereffects on its future developments, which has fundamentally contradicts the presupposition of programming methodology in Operation Research. In order to solve the problems arising from optimized theory research about the economic system, this paper defines the concept of dynamic system with aftereffects, points out the difference between its aftereffects and those of traditional stochastic processes, studies how the past decision effects on the value of optimal utility function, and gives an example on this base to illustrate its application in exploitation of oilfield.
基金supported by National Science Foundation under Contract no.0733526 and no.1031619.
文摘A new experimental characterization is presented of time-,field-,and temperature-dependent dynamic effects in magnetization of a nanocomposite which displays slow decay.Field and temperature variations of irreversible susceptibility,χirr,decay coefficient,S,fluctuation field,hf,and activation volume,V,have been calculated for the nanocomposite sample(Co_(80)Ni_(20))using a recently developed modified Preisach–Arrhenius(MPA)model.The sample is composed of non-interacting nanoparticles having negligible reversible magnetization.Non-Arrhenius behavior is observed in both the maximum decay coefficient,Smax,and the fluctuation field,hf,as a function of temperature T.The peak of both temperature curves are identical and occur at a critical temperature Tk of∼50 K,which agrees with our experimental results.Based on the effect of a temperature-dependent chemical potential on energy barrier,hf is studied for T<Tk and T≥Tk,respectively.A more complete MPA model that can predict the magnetization as function of time,field and temperature for a magnetic material with slow decay rates is proposed.This model uses a multi-variable analytical formula,m(ln(t),H,T),which incorporates the characteristic parameters.
