科研成果

An inexact chance-constrained linear programming (ICCLP) model for optimal water pollution management at the watershed scale was developed. We selected the net expenditures of the alternative strategies, including initial capital investment and operating costs, as the objectives of water pollution management. The total environmental capacity of the water bodies at different probability levels (q(i)) was considered a key constraint; other constraints included in the model were government minimum requirements on farmland area, land cover, treatment rate of domestic wastewater and rural wastes, and certain technical constraints. The ICCLP model was applied to Lake Qionghai watershed in China for water quality improvement with the goal of achieving a minimum total cost. Alternative strategies were incorporated following discussions with shareholders and experts. A three-period optimization was conducted based on the alternative strategies; the model parameters were based on field investigations. Five probability levels were considered in the model: q(i)=0.01, 0.25, 0.50. 0.90, and 0.99. The model results showed that the total optimized costs were between US\$[55,710.86,80,691.81] x 10(4) and US\$[72,151.39,101,338.6] x 10(4) under different probability levels. The model results indicate that soil erosion treatment, nonpoint source control measures, and rural waste treatment have much higher costs than other strategies, and our findings indicate that the ICCLP model can effectively deal with optimal water pollution management under uncertainty at the watershed scale.

This paper presents a further numerical study of the interaction dynamics for solitary waves in a nonlinear Dirac model with scalar self-interaction, the Soler model, by using a fourth order accurate Runge-Kutta discontinuous Galerkin method. The phase plane method is employed for the first time to analyze the interaction of Dirac solitary waves and reveals that the relative phase of those waves may vary with the interaction. In general, the interaction of Dirac solitary waves depends on the initial phase shift. If two equal solitary waves are in-phase or out-of-phase initially, so are they during the interaction; if the initial phase shift is far away from 0 and π, the relative phase begins to periodically evolve after a finite time. In the interaction of out-of-phase Dirac solitary waves, we can observe: (a) full repulsion in binary and ternary collisions, depending on the distance between initial waves; (b) repulsing first, attracting afterwards, and then collapse in binary and ternary collisions of initially resting two-humped waves; (c) one-overlap interaction and two-overlap interaction in ternary collisions of initially resting waves.

Interval linear programming (ILP) was developed by Huang and Moore (1993) and was widely applied in environmental and resources management. However, the feasibility of optimal solutions for affect directly in generating several decision alternatives, thus a modified interval linear programming (MILP) model is developed to assure its solution space could be absolutely feasible, and its solution algorithm is proposed to incorporates the associated extra constraints into the upper- and lower- bounds submodels. Moreover, the proofs for determining A and B in corresponding constraints are refined in this study. The results of numeric example and its application in water-quality management of Lake Qionghai Basin (China) further indicated the feasibility and effectiveness of the developed MILP model.

Air borne measurements carried out in the summer of 2004 in the lower Great Lakes region as part of the ICARTT 2004 study are used to examine the effects of clouds on the carbonyls in the atmosphere. Concentrations of seven carbonyl species in bulk cloudwater samples were measured with concurrent gas phase HCHO measurements. In the cloudwater, the most abundant carbonyl was HCHO with a median value of 11.9 mu mol L-1, followed by acetaldehyde (4.3 mu mol L-1), acetone (1.9 mu mol L-1), pentanal (1.4 mu mol L-1), benzaldehyde (0.5 mu mol L-1), butanal (0.4 mu mol L-1), and propanal (0.2 mu mol L-1). The relative abundance of propanal to acetaldehyde in the cloudwater was substantially lower than estimates from primary emissions. The cloudwater abundance of HCHO relative to the sum of the other carbonyls was found to increase with altitude in the clouds that penetrated the boundary layer. During most flights, the total in-cloud HCHOt (cloudwater + interstitial gas phase) was similar to cloud base HCHOg, suggesting that HCHO was distributed between the two phases through partitioning governed by Henry's law. However, during at least one flight, HCHOt was significantly depleted in the cloud. Finally, the equilibrium gas phase mixing ratios predicted from the cloudwater for all carbonyls but HCHO were much higher than previously measured in the gas phase.