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81.
Transport problems typically involve at least two types of constraints, on income and on time. Therefore, the indirect utility
function depends either on the income available after having subtracted the cost of the discrete alternative and on the free
time left after having worked and travelled by each competing option. In the typical linear-in-the-attributes and in-the-parameters
specification, that represents the first grade approximation of the indirect utility function, the effect of income and time
constraints cancel out and only the cost and time of the alternatives matter in the comparison between them. From a microeconomic
point of view this is equivalent to assume that income and time effects could be disregarded; which is not always the case.
To account for these effects the utility function should include second order attributes; however, in non-linear utility functions
it may not be easy to distinguish among several effects that could be relevant: direct preferences for good and leisure, and
simple interactions between attributes other than income and time effects. This paper analyses these effects from a theoretical
point of view focusing on the possible confounding problem in detecting income and time effects. We use a dataset collected
for a modal choice context and containing both revealed and stated preference data, and estimate several NL models examining
the effect of the different second-order terms on detecting income and time effects. We compared specifications including
square cost and time attributes, interactions between time and cost, cost divided by the income available to be spent on free
time, and time multiplied by free time. Our results confirm the strong effect of direct preferences for goods and leisure
time on choice, and the potential confounding effect between quadratic attributes and other non-linear omitted terms. Finally,
we also found that care should be taken in highlighting income and time effects using mixed data sources, since confounding
effects can occur when non-linearities are accounted for in both data sets. 相似文献
82.
83.
84.
Russomanno D.J. de Jongh Curry A.L. Atanasova G.S. Hunt L.C. Goodwin J.C. 《IEEE transactions on information technology in biomedicine》2008,12(1):76-86
DefibViz is a software application developed for defibrillation simulation and visualization. It exploits both surface techniques and methods for the interactive exploration of volumetric datasets for the analysis of transthoracic defibrillation simulation results. DefibViz has a graphical user interface for the specification of the shape, size, position, and applied voltage of a defibrillator's electrodes. An option is provided for using 3D slice plane widgets, which operate on the volumetric datasets, such that the distribution of the voltage gradient induced by an electric shock can be visually inspected in various tissues throughout the myocardium and torso. One goal of DefibViz is to enhance understanding of how electrode parameters relate to the change of the voltage gradient distribution throughout the heart, which may help lead to optimal defibrillator design. DefibViz is significant, in that, it is built by using an open-source graphics and visualization framework providing a platform for subsequent modifiability and extensibility. Moreover, it integrates simulation and visualization techniques, which previously required the running of several independent software executables, into an enhanced, seamless, and comprehensive software application. 相似文献
85.
86.
Amit Chourasia Steve Cutchin Yifeng Cui Reagan W Moore Kim Olsen Steven M Day J Bernard Minster Philip Maechling Thomas H Jordan 《Computer Graphics and Applications, IEEE》2007,27(5):28-34
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries. 相似文献
87.
Talita Moreira de Oliveira Nilda de Fátima Ferreira Soares Rodrigo Magela Pereira Kátia de Freitas Fraga 《Packaging Technology and Science》2007,20(2):147-153
Conservation of food products depends on product quality and packaging suitability. The objective of this work was to develop and evaluate the antimicrobial efficiency of natamycin‐incorporated film in the production process of Gorgonzola cheese. It aims to optimize the production process and increase shelf‐life and food safety for the consumer. Films with different concentrations of natamycin were produced and tested in Gorgonzola cheeses to evaluate its efficiency against Penicillium roqueforti on the cheese surface. Films with 2 and 4% natamycin presented satisfactory results for fungus inhibition and the amount of natamycin released to the cheese was below that allowed by the legislation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
88.
An efficient method for computing the fields of large scatterers is presented. The current is expanded in terms of modes defined as complex exponential functions. The modes are represented efficiently by means of spline functions. Analytical expressions have been obtained to compute efficiently the fields due to the current modes. 相似文献
89.
A model material approach to the study of fracture process zone of quasi-brittle materials 总被引:1,自引:0,他引:1
A new approach to study the fracture of quasi-brittle materials is introduced: the design and testing of model materials. By model material is understood a material with enlarged microstructure and which material parameters, such as stacking and mechanical properties of particles and cohesion force, can be fully controlled. In this paper a first example to the model materials approach is presented, consisting in 5 mm steel particles bonded in a precise stacking with an epoxy-based glue. It is shown how it is possible to correlate the different fracture mechanisms and ultimate peak load of the model material to the particle pair force and to the fracture process zone size. It is also seen how a quasi-brittle behaviour is produced in the presence of mechanisms that induced the crack to shift fracture planes, that is, in presence of energy dissipative mechanisms. 相似文献
90.
Dam H.H. Nordholm S. Cantoni A. de Haan J.M. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2004,51(11):581-586
Multirate adaptive filters have numerous advantages such as low computational load, fast convergence, and parallelism in the adaptation. Drawbacks when using multirate processing are mainly related to aliasing and reconstruction effects. These effects can be minimized by introducing appropriate problem formulation and employing sophisticated optimization techniques. In this paper, we propose a formulation for the design of a filter bank which controls the distortion level for each frequency component directly and minimizes the inband aliasing and the residual aliasing between different subbands. The advantage of this problem formulation is that the distortion level can be weighted for each frequency depending on the particular practical application. A new iterative algorithm is proposed to optimize simultaneously over both the analysis and the synthesis filter banks. This algorithm is shown to have a unique solution for each iteration. For a fixed distortion level, the proposed algorithm yields a significant reduction in both the inband aliasing and the residual aliasing levels compared to existing methods applied to the numerical examples. 相似文献