With the trend of multiple energies or flexible demand in power systems,binary variables appear in systemwide constraints,which are the foundation of marginal pricing currently in markets.An appropriate pricing method...With the trend of multiple energies or flexible demand in power systems,binary variables appear in systemwide constraints,which are the foundation of marginal pricing currently in markets.An appropriate pricing method incentivizes compliance of market participants;otherwise,compliance can be incentivized by paying discriminatory uplift payments which jeopardize transparency of markets.This paper proposes two theorems to examine whether the binary variables brought by multiple energies and flexible demand will impact compliance under marginal pricing.The first theorem shows sufficient conditions with which marginal pricing with fixed binary variables incentivizes compliance,while the second theorem shows sufficient conditions to require uplift payments.To improve transparency by reducing uplift payments under cases which fall into the second theorem,this paper further proposes a pricing method by combining 1)designed constraints to price binary variables in system-wide constraints,and 2)convex hull pricing to price binary variables in private constraints.Effectiveness of the proposed theorems and pricing method is verified in an electricity-gas case(consisting of the IEEE 30-bus system and the NGS 10-node system)and the IEEE 118-bus test system.展开更多
We present the results of a time-series CCD photometric survey of variable stars in the field of the open cluster NGC 7789. In a field of about one degree centering on the cluster, a total of 28 new variable stars are...We present the results of a time-series CCD photometric survey of variable stars in the field of the open cluster NGC 7789. In a field of about one degree centering on the cluster, a total of 28 new variable stars are discovered (14 W UMa systems, nine EA-type eclipsing binaries, one RR Lyr star, and four unclassified). In addition, we recovered 11 old variables previously discovered by other authors. Preliminary parameters are given for some of these variables.展开更多
GSC 4560-02157 is a new eclipsing cataclysmic variable with an orbital period of 0.265359 days. By using the published V- and R-band data together with our observations, we discovered that the O - C curve of GSC 4560-...GSC 4560-02157 is a new eclipsing cataclysmic variable with an orbital period of 0.265359 days. By using the published V- and R-band data together with our observations, we discovered that the O - C curve of GSC 4560-02157 may show a cyclic variation with a period of 3.51 years and an amplitude of 1.40 min. If this variation is caused by a light travel-time effect via the existence of a third body, then its mass can be derived as M3 sin i1≈ 91.08 Mjup, and it should be a low-mass star. In addition, several physical parameters were measured. The color of the secondary star was determined to be V - R = 0.77（±0.03） which corresponds to a spectral type of K2-3. The secondary star＇s mass was estimated as M2 = 0.73（±0.02） Mo by combing the derived V - R value around phase 0 with the assumption that it obeys the mass-luminosity relation for main sequence stars. This mass is consistent with the mass-period relation for CV donor stars. For the white dwarf, the eclipse durations and contacts of the white dwarf yield an upper limit on the white dwarf＇s radius corresponding to a lower limit on mass of M1 ≈ 0.501 M⊙. The overestimated radius and previously published spectral data indicate that the boundary layer may have a very high temperature.展开更多
In this paper,we introduce the separable task assignment problem(STAP)in which n separable tasks are assigned to m agents subject to agents’capacity constraints.The objective is to minimize the costs that occur durin...In this paper,we introduce the separable task assignment problem(STAP)in which n separable tasks are assigned to m agents subject to agents’capacity constraints.The objective is to minimize the costs that occur during the manufacturing and the communication between agents.A task is separable if it can be divided into two pieces,and both of them can be assigned individually or together to any agents.A separable task is considered as being assigned if and only if its two pieces are both assigned.Since several discrete(ternary)variables may be involved in STAP modeling,computing the problem in a reasonable time period is not an easy work.We replace the ternary variables by binary and continuous variables through extending the logarithmic method introduced by Li et al.(INFORMS J Comput 25(4):643–653,2012)and Vielma et al.(Oper Res 58(2):303–315,2010).Our numerical experiments demonstrate that the newly generated model performs well in solving difficult separable task-assignment problems for pretty large scale of instance sizes.展开更多
基金supported by the National Natural Science Foundation of China(52177072).
文摘With the trend of multiple energies or flexible demand in power systems,binary variables appear in systemwide constraints,which are the foundation of marginal pricing currently in markets.An appropriate pricing method incentivizes compliance of market participants;otherwise,compliance can be incentivized by paying discriminatory uplift payments which jeopardize transparency of markets.This paper proposes two theorems to examine whether the binary variables brought by multiple energies and flexible demand will impact compliance under marginal pricing.The first theorem shows sufficient conditions with which marginal pricing with fixed binary variables incentivizes compliance,while the second theorem shows sufficient conditions to require uplift payments.To improve transparency by reducing uplift payments under cases which fall into the second theorem,this paper further proposes a pricing method by combining 1)designed constraints to price binary variables in system-wide constraints,and 2)convex hull pricing to price binary variables in private constraints.Effectiveness of the proposed theorems and pricing method is verified in an electricity-gas case(consisting of the IEEE 30-bus system and the NGS 10-node system)and the IEEE 118-bus test system.
基金Supported by the National Natural Science Foundation of China.
文摘We present the results of a time-series CCD photometric survey of variable stars in the field of the open cluster NGC 7789. In a field of about one degree centering on the cluster, a total of 28 new variable stars are discovered (14 W UMa systems, nine EA-type eclipsing binaries, one RR Lyr star, and four unclassified). In addition, we recovered 11 old variables previously discovered by other authors. Preliminary parameters are given for some of these variables.
基金partly supported by the National Natural Science Foundation of China(Nos.11133007 and 11325315)the Key Research Program of the Chinese Academy of Sciences(Grant No.KGZD-EW-603)+1 种基金the Science Foundation of Yunnan Province(Nos.2012HC011 and 2013FB084)by the Strategic Priority Research Program The Emergence of Cosmological Structures of the Chinese Academy of Sciences(No.XDB09010202)
文摘GSC 4560-02157 is a new eclipsing cataclysmic variable with an orbital period of 0.265359 days. By using the published V- and R-band data together with our observations, we discovered that the O - C curve of GSC 4560-02157 may show a cyclic variation with a period of 3.51 years and an amplitude of 1.40 min. If this variation is caused by a light travel-time effect via the existence of a third body, then its mass can be derived as M3 sin i1≈ 91.08 Mjup, and it should be a low-mass star. In addition, several physical parameters were measured. The color of the secondary star was determined to be V - R = 0.77（±0.03） which corresponds to a spectral type of K2-3. The secondary star＇s mass was estimated as M2 = 0.73（±0.02） Mo by combing the derived V - R value around phase 0 with the assumption that it obeys the mass-luminosity relation for main sequence stars. This mass is consistent with the mass-period relation for CV donor stars. For the white dwarf, the eclipse durations and contacts of the white dwarf yield an upper limit on the white dwarf＇s radius corresponding to a lower limit on mass of M1 ≈ 0.501 M⊙. The overestimated radius and previously published spectral data indicate that the boundary layer may have a very high temperature.
基金the National Natural Science Foundation of China(No.11201333).
文摘In this paper,we introduce the separable task assignment problem(STAP)in which n separable tasks are assigned to m agents subject to agents’capacity constraints.The objective is to minimize the costs that occur during the manufacturing and the communication between agents.A task is separable if it can be divided into two pieces,and both of them can be assigned individually or together to any agents.A separable task is considered as being assigned if and only if its two pieces are both assigned.Since several discrete(ternary)variables may be involved in STAP modeling,computing the problem in a reasonable time period is not an easy work.We replace the ternary variables by binary and continuous variables through extending the logarithmic method introduced by Li et al.(INFORMS J Comput 25(4):643–653,2012)and Vielma et al.(Oper Res 58(2):303–315,2010).Our numerical experiments demonstrate that the newly generated model performs well in solving difficult separable task-assignment problems for pretty large scale of instance sizes.
