2,948 research outputs found
A Computational Comparison of Evolutionary Algorithms for Water Resource Planning for Agricultural and Environmental Purposes
The use of water resources for agricultural purposes, particularly in arid and semi-arid regions, is a matter of increasing concern across the world. Optimisation techniques can play an important role in improving the allocation of land to different crops, based on a utility function (such as net revenue) and the water resources needed to support these. Recent work proposed a model formulation for an agricultural region in the Murrumbidgee Irrigation Area of the Murray-Darling River basin in Australia, and found that the well-known NSGA-II technique could produce sensible crop mixes while preserving ground and surface water for environmental purposes. In the present study we apply Differential Evolution using two different solution representations, one of which explores the restricted space in which no land is left fallow. The results improve on those of the prior NSGA-II and demonstrate that a combination of solution representations allows Differential Evolution to more thoroughly explore the multiobjective space of profit versus environment
An Introduction to Temporal Optimisation using a Water Management Problem
Optimisation problems usually take the form of having a single or multiple objectives with a set of constraints. The model itself concerns a single problem for which the best possible solution is sought. Problems are usually static in the sense that they do not consider changes over time in a cumulative manner. Dynamic optimisation problems to incorporate changes. However, these are memoryless in that the problem description changes and a new problem is solved - but with little reference to any previous information. In this paper, a temporally augmented version of a water management problem which allows farmers to plan over long time horizons is introduced. A climate change projection model is used to predict both rainfall and temperature for the Murrumbidgee Irrigation Area in Australia for up to 50 years into the future. Three representative decades are extracted from the climate change model to create the temporal data sets. The results confirm the utility of the temporal approach and show, for the case study area, that crops that can feasibly and sustainably be grown will be a lot fewer than the present day in the challenging water-reduced conditions of the future
Integrating continuous differential evolution with discrete local search for meander line RFID antenna design
The automated design of meander line RFID antennas is a discrete self-avoiding walk(SAW) problem for which efficiency is to be maximized while resonant frequency is to beminimized. This work presents a novel exploration of how discrete local search may beincorporated into a continuous solver such as differential evolution (DE). A prior DE algorithmfor this problem that incorporates an adaptive solution encoding and a bias favoringantennas with low resonant frequency is extended by the addition of the backbite localsearch operator and a variety of schemes for reintroducing modified designs into the DEpopulation. The algorithm is extremely competitive with an existing ACO approach and thetechnique is transferable to other SAW problems and other continuous solvers. The findingsindicate that careful reintegration of discrete local search results into the continuous populationis necessary for effective performance
Increasing CAFE Standards: Still a Very Bad Idea
In a recent Joint Center Working Paper, Gerard and Lave respond to our recent work critiquing proposed increases in existing Corporate Average Fuel Economy (CAFE) standards. Gerard and Laveassert that, at least in the right environment, there is a place for CAFE standards. We suggest, however, that Gerard and Lavehave not really made any dent in our arguments, and have not provided any rationale for the CAFE program to exist. Indeed, much of the Gerard and Lave'sargument is self-contradictory.
A multi-objective extremal optimisation approach applied to RFID antenna design
Extremal Optimisation (EO) is a recent nature-inspired meta-heuristic whose search method is especially suitable to solve combinatorial optimisation problems. This paper presents the implementation of a multi-objective version of EO to solve the real-world Radio Frequency IDentification (RFID) antenna design problem, which must maximise efficiency and minimise resonant frequency. The approach we take produces novel modified meander line antenna designs. Another important contribution of this work is the incorporation of an inseparable fitness evaluation technique to perform the fitness evaluation of the components of solutions. This is due to the use of the NEC evaluation suite, which works as a black box process. When the results are compared with those generated by previous implementations based on Ant Colony Optimisation (ACO) and Differential Evolution (DE), it is evident that our approach is able to obtain competitive results, especially in the generation of antennas with high efficiency. These results indicate that our approach is able to perform well on this problem; however, these results can still be improved, as demonstrated through a manual local search process.Full Tex
Information, Liquidity, Asset Prices and Monetary Policy, Second Version
What determines which assets are used in transactions? We develop a framework where the extent to which assets are recognizable determines the extent to which they are acceptable in exchange - i.e., their liquidity. We analyze the effects of monetary policy on asset markets. Recognizability and liquidity are endogenized by allowing agents to invest in information. There can be multiple equilibria with different transaction patterns. These transaction patterns are not invariant to policy. We show small changes in information that may generate large responses in prices, allocations and welfare. We also discuss issues in international economics, including exchange rates and dollarization.Money, Asset Pricing, Liquidity
Health Care Savings from Personalizing Medicine Using Genetic Testing: The Case of Warfarin
Progress towards realizing a vision of personalized medicine - drugs and drug doses that are safer and more effective because they are chosen based on an individual's genetic makeup - has been slower than once forecast. The Food and Drug Administration has a key role to play in facilitating the use of genetic information in drug therapies because it approves labels, and labels influence how doctors use drugs. Here we evaluate one example of how using genetic information in drug therapy may improve public health and lower health care costs. Warfarin, an anticoagulant commonly used to prevent and control blood clots, is complicated to use because the optimal dose varies greatly among patients. If the dose is too strong the risk of serious bleeding increases and if the dose is too weak, the risk of stroke increases. We estimate the health benefits and the resulting savings in health care costs by using personalized warfarin dosing decisions based on appropriate genetic testing. We estimate that formally integrating genetic testing into routine warfarin therapy could allow American warfarin users to avoid 85,000 serious bleeding events and 17,000 strokes annually. We estimate the reduced health care spending from integrating genetic testing into warfarin therapy to be 100 million to $2 billion.
Report on the Workshop on Refugee and Asylum Policy in Practice in Europe and North America
Western nations have struggled to accomplish the dual goals of refugee and asylum policies: (1) identifying and protecting Convention refugees as well as those fleeing civil conflict; and (2) controlling for abuse. The Workshop on Refugee and Asylum Policy in Practice in Europe and North America was organized to facilitate a transatlantic dialogue to explore just how well these asylum systems are balancing the dual goals. The workshop exa!llined key elements of the U.S. and European asylum systems: decision making on claims, deterrence of abuse, independent review, return of rejected asylum seekers, scope of the refugee concept, social rights and employment, international cooperation, and data and evaluation.
The Workshop was convened by the Institute for the Study of International Migration (ISIM) of Georgetown University and the Center for the Study of Immigration, Integration and Citizenship Policies (CEPIC) of the Centre Nationale de Recherche Scientifique, with the support of the German Marshall Fund of the United States. It was held on July 1-3, 1999, at Oxford University. Workshop participants included government officials, scholars, and representatives from non-governmental organizations (NGOs) actively involved in analyzing and implementing refugee and asylum policies.
This report outlines the major points of discussion and the areas of consensus at the Workshop, and emphasizes the issues in need of further analysis and agreement. Through this report, the Workshop seeks to encourage further discussion on refugee and asylum policies in practice in order to clarify, develop, and improve the existing mechanisms for protection
Principals as Promoters of Teacher Retention: A Study of the Four Dimensions of Principal Leadership
Principals as Promoters of Teacher Retention: A Study of the Four Dimensions of Principal Leadershi
A perceived gap between invasive species research and stakeholder priorities
Information from research has an important role to play in shaping policy and management responses to biological invasions but concern has been raised that research focuses more on furthering knowledge than on delivering practical solutions. We collated 449 priority areas for science and management from 160 stakeholders including practitioners, researchers and policy makers or advisors working with invasive species, and then compared them to the topics of 789 papers published in eight journals over the same time period (2009–2010). Whilst research papers addressed most of the priority areas identified by stakeholders, there was a difference in geographic and biological scales between the two, with individual studies addressing multiple priority areas but focusing on specific species and locations. We hypothesise that this difference in focal scales, combined with a lack of literature relating directly to management, contributes to the perception that invasive species research is not sufficiently geared towards delivering practical solutions. By emphasising the practical applications of applied research, and ensuring that pure research is translated or synthesised so that the implications are better understood, both the management of invasive species and the theoretical science of invasion biology can be enhanced
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