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41.
The problems of assigning planes to flights and of fleet maintenance operations scheduling are considered in this paper. While recent approaches make use of artificial intelligence techniques running on main frame computers to solve combinatorial optimization problems for nominal operations, a dynamic approach is proposed here to face on-line operation conditions. The proposed solution mixes a Dynamic Programming approach (to cope with the fleet assignment problem) and a heuristic technique (to solve the embedded maintenance schedule problem). When applied to a medium charter airline, this approach shows acceptability characteristics for operational staffs, while providing efficient solutions. The proposed solution scheme can be considered as the basis for the development of an on-line decision support system for fleet operations management within airlines. 相似文献
42.
Walid M. Abdelwahab 《Transportation Research Part E: Logistics and Transportation Review》1998,34(4):257-266
This paper presents empirical estimates of market elasticities of demand and elasticities of mode choice probabilities in the intercity freight transport market. Results are derived from a mixed discrete/continuous choice model of mode and shipment size. The mode choice component of the full model was specified as a binary probit function. The two modes considered were rail and regulated common carriers (full truck load). Data was drawn from the US Commodity Transportation Survey consisting of individual shipments of manufactured goods identified at the most disaggregate level. Results obtained in this study are compared with those obtained in previous studies, and areas of similarities and dissimilarities in the magnitude as well as interpretation of the results are highlighted. The own-price and cross-price elasticities of mode choice probabilities were found to vary from 1.44 to 1.88, and from 1.54 to 1.75, respectively. The market price elasticities of demand were found to vary significantly across commodity groups and geographic territories. Among the 40 market segments considered, the truck price elasticity of demand ranged between −0.749 and −2.525; the rail price elasticity of demand was slightly larger, ranging between −0.956 and −2.489; and the rail–truck cross-price elasticity of demand ranged between 0.904 and 2.532. 相似文献
43.
Elhaj Mabrouk Walid 《Asia-Pacific Financial Markets》2009,16(1):33-50
This paper examines whether the cross-sectional variations in stock returns are better described by systematic risk factors
or by firm characteristics such as book-to-market ratios and market capitalization. It provides new evidence from the Japanese
stock market based on the recent sample period from 2002 to 2007, which is not addressed in the existing literature. Also,
the new results are derived from the generalized method of moments applied to daily returns. The evidence suggests that both
the firm size and book-to-market ratio are significantly related to average return premiums. There is mixed evidence, which
tends to lend stronger support to the characteristic model rather than the Fama-French three-factor model as more reflective
of the return dynamics in the Japanese stock market. 相似文献
44.
Walid Hejazi 《Atlantic Economic Journal》2005,33(4):423-436
A substantial amount of evidence has emerged indicating that a majority of the world's largest multinational enterprises concentrate
activities in their home region. However, there are relatively few studies which test whether such concentrations are consistent
with economic theory. This paper works to fill the void. It tests whether regional concentrations of OECD exports and outward
FDI are consistent with predictions of a gravity model. The empirical evidence provided here indicates that exports are far
more regional than the model predicts. As for FDI, the empirical evidence shows that intra-regional FDI in Europe is larger
than the model predicts, whereas intra-regional FDI patterns within North America are consistent with gravity. Overall, this
paper provides further support for Rugman's thesis that MNEs are best described as regional as opposed to global actors. 相似文献
45.
We investigate the effect of mandatory IFRS adoption on trade credit. We document that firms in countries that adopt IFRS receive more trade credit from their suppliers, consistent with improved financial reporting quality and comparability playing a role in facilitating informal financing. This increase is larger for countries with a low level of societal trust, a poor pre‐IFRS‐adoption information environment, and stronger legal enforcement. These cross‐sectional results suggest that the conditions under which higher‐quality information is made publicly available affect suppliers' decisions to provide trade credit. This increase is also larger for firms with greater exposure to foreign markets, a finding that highlights the importance of more comparable international financial reporting standards in facilitating cross‐country trade credit. We also find that IFRS adoption has a stronger positive effect on trade credit for firms with greater liquidity needs. Finally, we find that firms in countries that adopt IFRS also extend more trade credit to their customers. Overall, our results support the notion that financial reporting can have a causal effect on trade credit. 相似文献
46.
The existence of an intra-day seasonality component in financial market variables (volatility, volume, activity, etc.) has been highlighted in many previous studies. To remove this cyclical component from raw data, many researchers use the intra-day average observations model (IAOM) and/or some smoothing techniques (e.g. the kernel method). When the seasonality is related to the first moment (the conditional expectation) and involves only a deterministic component, the IAOM method succeeds in estimating the periodicity almost perfectly. However, when seasonality affects the first or the second moment (the conditional variance) of the data and contains both deterministic and stochastic components, both IAOM and the kernel method fail to capture it. We introduce self-organizing maps (SOM) as a solution. SOM are based on neural network learning and nonlinear projections. Their flexibility allows seasonality to be captured even in the presence of stochastic cycles. 相似文献
47.
48.
The large correlation between domestic savings and investment is well documented and is known as the Feldstein–Horioka puzzle. We demonstrate that estimates of the FH coefficients using the standard framework are biased upward in the presence of highly positively correlated inward and outward capital flows. Using data for the 14 OECD countries, the analysis shows that the significant home bias documented by FH and others is also consistent with much higher levels of capital mobility when capital outflows and inflows are highly positively correlated. Taking account for these correlations reduces the estimated home bias somewhere between 45% and 90%. 相似文献
49.
This paper examines the relationship between board of directors' effectiveness and voluntary climate change disclosures. Since risk management and reporting fall under the board's responsibility, we relate board effectiveness to the firm's decision to voluntarily respond to the Carbon Disclosure Project (CDP) annual questionnaire as well as the quality of disclosures about climate‐change‐related risks and strategies to mitigate them. Our results show a positive association between board effectiveness and the firm's decision to answer the CDP questionnaire as well as its carbon disclosure quality. The paper contributes to the ongoing debate on the determinants of voluntary climate change disclosures. Our findings highlight the importance of the board of directors' role in enhancing the transparency and relevance of voluntary disclosures of climate change business impacts. Copyright © 2014 John Wiley & Sons, Ltd and ERP Environment 相似文献
50.
Walid Hichri 《Experimental Economics》2007,10(2):185-186
The work undertook is located between Public Economic Theory and Experimental Economics. The object of the thesis consists
in analysing the aggregate behavior and the individual heterogeneity in a voluntary contribution game. The thesis defended
here is that overcontribution in comparison to the Nash equilibrium of the game, can not be explained neither by judgement
errors, nor by the information on the individual behaviour of the members in a one given group. The level of contribution
observed remains nevertheless inferior to the one simulated using the E.W.A. learning model.
The dissertation is composed of three parts and six chapters. The first chapter expresses the various theoretical mechanisms
of production of a public good, while the second one presents an overview of the experimental literature using voluntary contribution
mechanisms.
The second part carries on the introduction of an interior solution in a public good game in order to distinguish an explanation
of overcontribution in terms of mistakes or strategies. While chapter three presents the most important works in literature
that use an interior solution, the fourth chapter constitutes a personal contribution consisting in an experiment with an
interior optimum. Our main result is that individuals contribute a constant part of their social optimum and that overcontribution
is not explained by error. We test then the simple learning model R.L. using the observed data on the aggregate level. This
model predicts well the observed behaviour.
The third part is composed of two experiments where the environment of players is modified. We introduce in chapter five promises
as cheap talk and find that they increase contributions at the aggregate level. In chapter six, various conditions of information
on individual contributions are tested. The parameter tested is the level of information on “neighbours” contributions given
to players. One of the treatments presents full information about individual contributions of the members of the group, while
this information is incomplete in the other treatments. Our results show that information has no effect on the level of contribution.
We simulate then the EWA learning model both at the aggregate and the individual levels and compare the simulated data to
the experimental one. These simulations predict a level of contribution that is higher that the one observed in the experiment.
JEL Classification C91, C92, H41
Dissertation Committee:
Alan Kirman (Ph.D. Advisor), Université d’Aix-Marseille III
Marie-Claire Villeval (Chair), GATE, Lyon, France
Jordi Brandts, Universitat Autonoma Barcelona, Spain
Charles Noussair, Emory University, Alanta, GA, U.S.A.
Sylvie Thoron, GREQAM & Université du Var, France
Marc Willinger, Université de Montpellier I, France 相似文献