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Trade-off Model (trade-off + model)

Distribution by Scientific Domains

Engineering	42%

Selected Abstracts

Trade-offs and the evolution of life-histories during range expansion

ECOLOGY LETTERS, Issue 10 2010
Olivia J. Burton
Ecology Letters (2010) Abstract During range-advance, individuals on the expanding edge of the population face a unique selective environment. In this study, we use a three-trait trade-off model to explore the evolution of dispersal, reproduction and competitive ability during range expansion. We show that range expansion greatly affects the evolution of life-history traits due to differing selection pressures at the front of the range compared with those found in stationary and core populations. During range expansion, dispersal and reproduction are selected for on the expanding population front, whereas traits associated with fitness at equilibrium density (competitive ability) show dramatic declines. Additionally, we demonstrate that the presence of a competing species can considerably reduce the extent to which dispersal is selected upwards at an expanding front. These findings have important implications for understanding both the rate of spread of invasive species and the range-shifting dynamics of native species in response to climate change. [source]

Coexistence in a metacommunity: the competition,colonization trade-off is not dead

ECOLOGY LETTERS, Issue 8 2006
V. Calcagno
Abstract The competition,colonization trade-off model is often used to explain the coexistence of species. Yet its applicability has been severely criticized, mainly because the original model assumed a strict competitive hierarchy of species and did not allow for any preemptive effect. We considered the impact of relaxing both of these limitations on coexistence. Relaxing trade-off intensity makes coexistence less likely and introduces a minimum colonization rate below which any coexistence is impossible. Allowing for preemption introduces a limit to dissimilarity between species. Surprisingly, preemption does not impede coexistence as one could presume from previous studies, but can actually increase the likelihood of coexistence. Its effect on coexistence depends on whether or not species in the regional pool are strongly limited in their colonization ability. Preemption is predicted to favour coexistence when: (i) species are not strongly limited in their colonization ability; and (ii) the competitive trade-off is not infinitely intense. [source]

The Determinants and Implications of Mutual Fund Cash Holdings: Theory and Evidence

FINANCIAL MANAGEMENT, Issue 2 2006
Xuemin (Sterling) Yan
In this article, I examine the determinants and implications of equity mutual fund cash holdings. In cross-sectional tests, I find evidence generally supportive of a static trade-off model developed in the article. In particular, small-cap funds and funds with more-volatile fund flows hold more cash. However, I do not find that fund managers with better stock-picking skills hold less cash. Aggregate cash holdings by equity mutual funds are persistent and positively related to lagged aggregate fund flows. Aggregate cash holdings do not forecast future market returns, suggesting that equity funds as a whole do not have market timing skills. [source]

Accelerating adaptive trade-off model using shrinking space technique for constrained evolutionary optimization

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2009
Yong Wang
Abstract Adaptive trade-off model (ATM) is a constraint-handling mechanism proposed recently. The main advantages of this model are its simplicity and adaptation. Moreover, it can be easily embedded into evolutionary algorithms for solving constrained optimization problems. This paper proposes a novel method for constrained optimization, which aims at accelerating the ATM using shrinking space technique. Eighteen benchmark test functions and five engineering design problems are used to test the performance of the method proposed. Experimental results suggest that combining the ATM with the shrinking space technique is very beneficial. The method proposed can promptly converge to competitive results without loss of the quality and the precision of the final results. Performance comparisons with some other state-of-the-art approaches from the literature are also presented. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Pollution and Cost in the Coke-Making Supply Chain in Shanxi Province, China

JOURNAL OF INDUSTRIAL ECOLOGY, Issue 3-4 2002
Applying an Integrated System Model to Siting, Transportation Trade-Offs
Summary An integrated system trade-off model has been developed to assess costs and pollution associated with transportation in the coke-making supply chain in Shanxi Province, China. A transportation-flow, cost-minimization solver is combined with models for calculating coke-making plant costs, estimating transportation costs from a geographic information system road and rail database, and aggregating coke-making capacity among plants. Model outputs of economic cost, nitrogen oxides (NOx) emissions, and transport distributions are visualized using an Internet-based graphic user interface. Data for the model were collected on survey trips to Shanxi Province as well as from secondary references and proxies. The modularity and extensibility of the system trade-off model facilitate introduction of new data sets in order to examine various planning scenarios. Scenarios of coke-making plant aggregation, rail infrastructure improvement, and technology transfer were evaluated using the model. Costs and pollution emissions can be reduced by enlarging coke-making plants near the rail stations and closing down other plants. Preferential minimization of transportation costs gives a lower total cost than simply minimizing plant costs. Therefore, policy makers should consider transportation costs when planning the reallocation of coke-making capacity in Shanxi Province. Increasing rail-transport capacity is less effective than aggregating plant capacity. On the other hand, transfer of low-pollution truck technology results in a large emission reduction, however, reflecting the importance of truck transportation in the Shanxi Province coke-making industry. [source]

COMPETITIVE PRIORITIES: INVESTIGATING THE NEED FOR TRADE-OFFS IN OPERATIONS STRATEGY

PRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2002
KENNETH K. BOYER
A heated debate continues over the need for trade-offs in operations strategy. Some researchers call for plants to focus on a single manufacturing capability and devote their limited resources accordingly, while others claim that advanced manufacturing technology (amt) enables concurrent improvements in quality, cost, flexibility, and delivery. Yet there is little empirical evidence for or against the trade-off model. In response, this study addresses the question: "To what extent do manufacturing plants view competitive priorities as trade-offs?" We employ survey data collected from managers and operators in 110 plants that have recently implemented AMT. Our findings suggest that trade-offs remain. However, perceived differences in competitive priorities are subtle and may vary across levels of the plant hierarchy. [source]