All the elements of a transportation system model generally suffer from some approximation. Normally the demand vector is considered the most crucial and problematic element to be simulated, and traffic counts are thu...
详细信息
ISBN:
(纸本)9781845640873
All the elements of a transportation system model generally suffer from some approximation. Normally the demand vector is considered the most crucial and problematic element to be simulated, and traffic counts are thus generally used to update it so that the whole model system is able to reproduce the observed link flows. Updating demand vectors using traffic counts has received considerable attention in recent years. In this paper the methodology proposed by Cascetta and Postorino (Fixed point models for the estimation of O-D matrices using traffic counts on congested networks. Transportation Science, Vol. 35, 2001) for updating the demand vector using traffic counts on congested networks is applied to a real case: the OD demand vectors for the city of Naples (Italy). The results show the good capacity of this methodology to reproduce the traffic counts measured. Furthermore, through the estimated OD vectors it was possible to make a structural analysis of transportation demand in Naples.
In this paper, a bi-level game-theoretic model is proposed to investigate the effects of governmental financial intervention on green supply chain. This problem is formulated as a bi-level program for a green supply c...
详细信息
In this paper we addressed supply chain network (SCN) as bi-level programming problem in which the primary objective is to determine optimal order allocation of products where the customer's demands and supply for...
详细信息
In this paper we addressed supply chain network (SCN) as bi-level programming problem in which the primary objective is to determine optimal order allocation of products where the customer's demands and supply for the products are fuzzy. In the proposed SCN model, we suppose that the first level (leader) and second level (follower) operate two separate groups of SCN. The leader, who moves first, determines quantities shipped to retailers, and then, the follower decides his quantities rationally. The leader's objective is to minimize the total transportation costs, and similarly, the follower's objective is to minimize the total delivery time of the SCN and at the same time balancing the optimal order allocation from each source, plant, retailer and warehouse respectively. The fuzzy goal programming approach has been used to achieve the highest degree of the membership goals by minimizing the deviational variables so that most satisfactory or the preferred solution for both the levels to be obtained. A numerical example is given to demonstrate the proposed methodology.
This paper proposes an adding-runs strategy to alleviate in-vehicle crowding for peak-hour bus services. Passengers' departure time choices under user equilibrium and system optimum conditions are investigated wit...
详细信息
This paper proposes an adding-runs strategy to alleviate in-vehicle crowding for peak-hour bus services. Passengers' departure time choices under user equilibrium and system optimum conditions are investigated with and without adding-runs strategy. A bi-levelprogramming model is developed to determine the optimal adding-runs strategy. An artificial bee colony algorithm is adopted to solve the proposed bi-levelproblem. Numerical examples show that the adding-runs strategy is effective in alleviating crowding effects and reducing schedule delay in peak-hour bus services. The total system cost can be reduced by more than 8% with the optimal adding-runs strategy.
Aiming at the problems of insufficient power system regulation capacity and lack of flexible resources caused by source-load uncertainty, the flexible resource planning of power systems is studied with the goal of imp...
详细信息
Aiming at the problems of insufficient power system regulation capacity and lack of flexible resources caused by source-load uncertainty, the flexible resource planning of power systems is studied with the goal of improving flexibility. Uncertainty and flexibility are combined in this article, and a probability index of an insufficiently flexible supply-demand ratio is proposed based on the probability characteristics of flexibility. A bi-levelprogramming model of power system flexibility resources considering the probability of an insufficiently flexible supply demand ratio is constructed. Optimal economics is used as the objective function of the planning layer, and the proposed minimum probability index of the flexible supply-demand ratio is used as the objective function of the operations layer. Economics and flexibility are studied, taking the power system in a certain area in Northeast China as the research object. A flexible resource planning scheme that meets different flexibility expectations is obtained, and the scheme is discussed in detail from the aspects of system flexibility, economic cost, and new energy consumption capacity. The effectiveness of quantitative indicators and planning methods are verified.
The optimal participation of wind-based power resources within electricity markets confronts serious challenges due to the inherent uncertainty of wind speed. Accordingly, these units are forced to make take-or-pay co...
详细信息
The optimal participation of wind-based power resources within electricity markets confronts serious challenges due to the inherent uncertainty of wind speed. Accordingly, these units are forced to make take-or-pay contracts that are typically lower than market-clearing prices. Hence, wind power plants are not able to obtain the maximum possible amount of profit. One of the most promising solutions to deal with this matter is the coordination of wind-based units with flexible resources like energy storage systems. Therefore, this study presents a novel offering strategy of multiple Wind Producers (WPs) coordinated with a Battery Energy Storage System (BESS) in the form of a strategic Virtual Power Plant (VPP). To this end, a bi-levelprogramming framework is proposed in which the VPP's expected profit is maximized at the upper-level (UL) through solving a two-stage stochastic problem. At the first stage, the VPP's optimal offers to the day-ahead (DA) market are determined before the realization of stochastic variables. At the second stage, this participant's real-time (RT) imbalance cost is optimized after determining the true value of uncertain parameters. On the contrary, at the lower-level (LL), the DA market-cleaning process is performed in the presence of conventional power producers. Moreover, this article aims to calculate the amount of net power trading of the VPP's components with the market and with one another. Ultimately, to assess the effectiveness of the provided framework, a sensitivity analysis is conducted by investigating the effect of the BESS presence on the wind-based VPP's optimal operation and expected benefit.
with the onboard diesel generators and energy storage system to meet the propulsion and service load, the all-electric ship (AES) can be viewed as a mobile microgrid'. Nowadays, photovoltaic (PV) generation is gra...
详细信息
with the onboard diesel generators and energy storage system to meet the propulsion and service load, the all-electric ship (AES) can be viewed as a mobile microgrid'. Nowadays, photovoltaic (PV) generation is gradually integrated into the AES for a greener' voyage. To fully utilise the PV energy, this paper proposes a joint generation and voyage scheduling method for the PV integrated AES. The overall model is formulated as a bi-level programming problem and solved by column-and-constraint generation method. The simulation results manifest that, the integration of PV into AES leads to reductions on both the fuel consumption and CO2 emission.
The purpose of this study is to determine the optimum subsidy rate for the glass recycling industry in *** hierarchical and interactive nature between the agency and the industry is modeled by bi-levelprogramming, wh...
详细信息
The purpose of this study is to determine the optimum subsidy rate for the glass recycling industry in *** hierarchical and interactive nature between the agency and the industry is modeled by bi-levelprogramming, where the agency plays the upper-level decision unit while the recycling industry is the lower-level *** order to solve the problem by optimization software,the bi-level formulation is transformed to a single levelproblem via Karush-Kuhn-Tucker(KKT) optimality conditions and is further transformed to a 0-1 non-linear programming *** problem is solved with real-world data,and the obtained solutions are analyzed and compared with current operations.
暂无评论