2,744,209 research outputs found

    Global search algorithm for optimal control

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    Random-search algorithm employs local and global properties to solve two-point boundary value problem in Pontryagin maximum principle for either fixed or variable end-time problems. Mixed boundary value problem is transformed to an initial value problem. Mapping between initial and terminal values utilizes hybrid computer

    A study of interface support mechanisms for interactive information retrieval

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    Advances in search technology have meant that search systems can now offer assistance to users beyond simply retrieving a set of documents. For example, search systems are now capable of inferring user interests by observing their interaction, offering suggestions about what terms could be used in a query, or reorganizing search results to make exploration of retrieved material more effective. When providing new search functionality, system designers must decide how the new functionality should be offered to users. One major choice is between (a) offering automatic features that require little human input, but give little human control; or (b) interactive features which allow human control over how the feature is used, but often give little guidance over how the feature should be best used. This article presents a study in which we empirically investigate the issue of control by presenting an experiment in which participants were asked to interact with three experimental systems that vary the degree of control they had in creating queries, indicating which results are relevant in making search decisions. We use our findings to discuss why and how the control users want over search decisions can vary depending on the nature of the decisions and the impact of those decisions on the user's search

    Search, Effort, and Locus of Control

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    We test the hypothesis that locus of control – one's perception of control over events in life – influences search by affecting beliefs about the efficacy of search effort in a laboratory experiment. We find that reservation offers and effort are increasing in the belief that one's efforts influence outcomes when subjects exert effort without knowing how effort influences the generation of offers but are unrelated to locus of control beliefs when subjects are informed about the relationship between effort and offers. These effects cannot be explained by locus of control's correlation with unmeasured human capital, personality traits, and the costs of search – alternative explanations for the relationships between locus of control and search behavior that cannot be ruled out using survey data – as the search task does not vary across treatments, which leads us to conclude that locus of control influences search through beliefs about the efficacy of search effort. Our findings provide evidence that locus of control measures can be used to identify job seekers at risk of becoming "discouraged" and abandoning search.locus of control, reservation wages, labor market search, experiment

    Search complexity and resource scaling for the quantum optimal control of unitary transformations

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    The optimal control of unitary transformations is a fundamental problem in quantum control theory and quantum information processing. The feasibility of performing such optimizations is determined by the computational and control resources required, particularly for systems with large Hilbert spaces. Prior work on unitary transformation control indicates that (i) for controllable systems, local extrema in the search landscape for optimal control of quantum gates have null measure, facilitating the convergence of local search algorithms; but (ii) the required time for convergence to optimal controls can scale exponentially with Hilbert space dimension. Depending on the control system Hamiltonian, the landscape structure and scaling may vary. This work introduces methods for quantifying Hamiltonian-dependent and kinematic effects on control optimization dynamics in order to classify quantum systems according to the search effort and control resources required to implement arbitrary unitary transformations

    Applying search theory to determine the feasibility of eradicating an invasive population in natural environments

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    The detectability of invasive organisms influences the feasibility of eradicating an infestation. Search theory offers a framework for defining and measuring detectability, taking account of searcher ability, biological factors and the search environment. In this paper, search theory concepts are incorporated into a population model, and the costs of search and control are calculated as functions of the amount of search effort (the decision variable). Simulations are performed on a set of weed scenarios in a natural environment, involving different combinations of plant longevity, seed longevity and plant fecundity. Results provide preliminary estimates of the cost and duration of eradication programs to assist in prioritising weeds for control. The analysis shows that the success of an eradication program depends critically on the detectability of the target plant, the effectiveness of the control method, the labour requirements for search and control, and the germination rate of the plant.bioeconomics, invasive species, operations research, population dynamics, weed control, Resource /Energy Economics and Policy,

    Locus of Control and Job Search Strategies

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    Standard job search theory assumes that unemployed individuals have perfect information about the effect of their search effort on the job offer arrival rate. In this paper, we present an alternative model which assumes instead that each individual has a subjective belief about the impact of his or her search effort on the rate at which job offers arrive. These beliefs depend in part on an individual's locus of control, i.e., the extent to which a person believes that future outcomes are determined by his or her own actions as opposed to external factors. We estimate the impact of locus of control on job search behavior using a novel panel data set of newly-unemployed individuals in Germany. Consistent with our theoretical predictions, we find evidence that individuals with an internal locus of control search more and that individuals who believe that their future outcomes are determined by external factors have lower reservation wages.job search behavior, search effort, reservation wage, locus of control, unemployment duration

    Locus of Control and Job Search Strategies

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    Standard job search theory assumes that unemployed individuals have perfect information about the effect of their search effort on the job offer arrival rate. In this paper, we present an alternative model which assumes instead that each individual has a subjective belief about the impact of his or her search effort on the rate at which job offers arrive. These beliefs depend in part on an individual's locus of control, i.e., the extent to which a person believes that future outcomes are determined by his or her own actions as opposed to external factors. We estimate the impact of locus of control on job search behavior using a novel panel data set of newly-unemployed individuals in Germany. Consistent with our theoretical predictions, we find evidence that individuals with an internal locus of control search more and that individuals who believe that their future outcomes are determined by external factors have lower reservation wages.Job search behavior, search effort, reservation wage, locus of control, unemployment duration

    Weed Search and Control: Theory and Application

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    The detectability of invasive organisms influences the costs and benefits of alternative control strategies, and the feasibility of eradicating an infestation. Search theory offers a mathematically rigorous framework for defining and measuring detectability, taking account of searcher ability, biological factors and the search environment. To demonstrate the application of search theory to invasive species control, invasive species detectability is incorporated into a population simulation model. The model is applied to a base set of parameter values that represent reasonable values for a hypothetical weed. The analysis shows the effects of detectability and search time on the duration of an eradication program. Furthermore, for a given level of detectability and search time, the analysis shows that the variables with the greatest influence on the duration of the eradication effort are search speed, kill efficiency and seed longevity. A series of Monte Carlo simulations are performed on a set of five scenarios, involving different combinations of plant longevity, seed longevity and plant fecundity. Results of these simulations are presented as probability distributions and allow us to calculate how the probability of eradication will be affected by search strategy.search and control, search theory, weed control, stage matrix, impedance factors, population dynamics, stochastic model, Farm Management,
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