Multiobjective Tradeoff Analysis Research Articles

Rethinking Environmental Flows for the Yellow River Estuary by Trading Off Crop Yield and Ecological Benefits

To solve the water use conflicts between agriculture and ecosystems in arid and semiarid areas, a multi-objective trade-off analysis method was applied to determine the environmental flows (e-flows) for the Yellow River Estuary, by considering the temporal and spatial discrepancies in water allocation. The results showed that during average years, a loss of 3.7 × 108 yuan was caused with every 1 × 108 m3 of e-flows under the baseline scenario. The crop growth stages of April–July are sensitive periods for water requirements, and over 5000 yuan/ha production losses were caused by prioritizing e-flows during this time in dry years. The stages from July–October require more water by ecosystems than other stages, and the recommended e-flows during this time accounted for 57% of the e-flows during the total year. Under scenarios 1–3, which represent the short-term, medium-term and long-term scenarios, more water resources were supplied by underground water and water diversion projects; however, alleviating the water use contradiction remained difficult in dry years. During average years, e-flows between 148 and 168 × 108 m3 are recommended to meet the ecological objectives of survival, reproduction and biological integrity of species for the Yellow River Estuary. The recommended e-flows in wet years could meet higher ecological objectives but still barely achieve the targets of sediment transport and ecosystem dynamic balance. In dry years, the economic losses may be beyond the acceptance of irrigation stakeholders if more water is allocated to improve e-flows. In this case, 71 × 108 yuan would be paid to them to compensate for their losses. This study proposes an e-flow recommendation framework that is economically and ecologically optimal in areas with irreconcilable water-use contradictions.

Entropy-STEP Multiobjective Trade-Off Analysis Method for Optimal Transportation Investment Decisions

AbstractThe transportation decision-making process is complicated in that it often involves conflicting interests and expectations of different stakeholders. To ensure achieving sound decisions, va...

Multi-objective trade-off analysis of an integrated cold gas propulsion system

The overall design of cold gas propulsion systems is pretty complicated when considering the mission requirements, operating constraints and functional limitations imposed by the mechanical components. To address this complication, a precise design process is proposed, which attempts to optimize the cost of operation as well as to minimize the waste volume and weight by using multi-objective trade-off analysis. This analysis is based on a set of ordinary differential equations that are solved iteratively to describe the optimal behavior of the system. Therefore, a numerical code is being developed to give insight on the design sensitivity with respect to uncertainties on the design variables. Consequently, the most favorite operating media, nozzle inlet pressure and tank charging pressure are determined. Moreover, the advantages of electric heater for the storage tank are studied for a specified mission. A three-dimensional computational fluid dynamics analysis is employed to accurately simulate the flow conditions inside the nozzle. The accuracy of the simulation is verified by correlation with experimental results obtained from a non-vacuum test set-up. The experimental results have revealed acceptable performance and agreement with the simulation, within 7% in error.

Cost–benefit functions for the allocation of security sensors for air contaminants

In this paper, we study various functional forms of the cost–benefit function in a context of risk analysis and multi-objective decision-making for the allocation of hazard protection. An approach of benefit–cost analysis under uncertainty is used. The study identifies measures of hazard intensity and population exposure as well as additional parameters that influence assessments of benefits and costs. Parameter uncertainties are propagated by numerical interval analysis. Several tiers of the uncertainty of the benefit-to-cost ratio are generated to compare hazard intensity and population exposure in multi-objective tradeoff analysis. We develop an example application with the allocation of chemical, biological, and radiological air contaminant sensors throughout a region. The sensors provide local protection to non-identical sectors of the population that are exposed to non-identical intensities of the hazard. The results illuminate the significance of the cost–benefit function for the allocation of sensors. The paper has implications for anti-terrorism, disaster preparedness, transportation safety, and other areas of public safety.

Influence Diagrams With Multiple Objectives and Tradeoff Analysis

Influence diagrams have been important models for decision problems because of their ability to both model a problem rigorously at its mathematical level and depict its high-level structure graphically. Once the structure and numerical details of an influence diagram have been specified, it can be evaluated to determine the optimal decision policy. However, when evaluating multiple objectives, in the past this determination was based on the assumption that utility functions that commensurate the objectives are available. This paper extends the structure and solution algorithm for influence diagrams to allow for the inclusion of noncommensurate objectives using multiobjective tradeoff analysis instead of utility theory. This eliminates the need to specify any preference information before the influence diagram is solved. The proposed multiobjective-based methodology is also useful for decision makers who either do not want to accept the assumptions of utility theory for a particular problem, or are confronted with a problem in which it is neither practical nor viable to construct a utility function. Additionally, this paper establishes the relationship between multiobjective influence diagrams and multiobjective decision trees. This relationship is important because it allows a decisionmaker to utilize the advantages of both representations. An example problem is presented to introduce both the extended multiobjective influence diagram methodology and the relationship linking multiobjective decision trees to multiobjective influence diagrams.

Risk modeling, assessment, and management of lahar flow threat.

The 1991 eruption of Mount Pinatubo in the Philippines is considered one of the most violent and destructive volcanic activities in the 20th century. Lahar is the Indonesian term for volcanic ash, and lahar flows resulting from the massive amount of volcanic materials deposited on the mountain's slope posed continued post-eruption threats to the surrounding areas, destroying lives, homes, agricultural products, and infrastructures. Risks of lahar flows were identified immediately after the eruption, with scientific data provided by the Philippine Institute of Volcanology, the U.S. Geological Survey, and other research institutions. However, competing political, economic, and social agendas subordinated the importance of scientific information to policy making. Using systemic risk analysis and management, this article addresses the issues of multiple objectives and the effective integration of scientific techniques into the decision-making process. It provides a modeling framework for identifying, prioritizing, and evaluating policies for managing risk. The major considerations are: (1) applying a holistic approach to risk analysis through hierarchical holographic modeling, (2) applying statistical methods to gain insight into the problem of uncertainty in risk assessment, (3) using multiobjective trade-off analysis to address the issue of multiple decisionmakers and stakeholders in the decision-making process, (4) using the conditional expected value of extreme events to complement and supplement the expected value in quantifying risk, and (5) assessing the impacts of multistage decisions. Numerical examples based on ex post data are formulated to illustrate applications to various problems. The resulting framework from this study can serve as a general baseline model for assessing and managing risks of natural disasters, which the Philippines' lead agency-the National Disaster Coordinating Council (NDCC)-and other related organizations can use for their decision-making processes.

Multiobjective tradeoff analysis of deregulated electricity transactions : Niimura, T. and Nakashima, T. International Journal of Electrical Power & Energy Systems, 2003, 25, (3), 179–185

Multiobjective tradeoff analysis of deregulated electricity transactions : Niimura, T. and Nakashima, T. International Journal of Electrical Power & Energy Systems, 2003, 25, (3), 179–185

Multiobjective tradeoff analysis of deregulated electricity transactions

This paper analyzes the tradeoff relationships between the differing goals of power system operation and the influence of social policies, such as environmental impact minimization, upon deregulated electricity trade. An optimization procedure to reach a coordinated solution between different objectives is presented based on fuzzy interactive multiobjective optimization. Numerical examples are demonstrated on an IEEE 30 bus system. From the simulation, it has been found that the additional goals may reduce the volume of free trade of electricity, but the fuzzy multiobjective optimization can reach a good balance between conflicting goals.