Home About us Contact
|
Home About us Contact | ||
|
|
||
Paper Models (paper + models)
Selected AbstractsPerformance evaluation for asynchronous MC-CDMA systems with a symbol timing offsetINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2009Myonghee Park Abstract This paper models a symbol timing offset (STO) with respect to the guard period and the maximum access delay time for asynchronous multicarrier-code division multiple access systems over frequency-selective multipath fading channels. Analytical derivation shows that STO causes desired signal power degradation and generates self-interferences. This effect of the STO on the average bit error rate (BER) and the effective signal-to-noise ratio (SNR) is evaluated using the semi-analytical method, and the approximated BER and the SNR loss caused by STO are then obtained as closed-form expressions. The tightness between the semi-analytical result and the approximated one is verified for the different STOs and SNRs. Furthermore, the derived analytical results are verified via Monte Carlo simulations. Copyright © 2008 John Wiley & Sons, Ltd. [source] Risk of catastrophic terrorism: an extreme value approachJOURNAL OF APPLIED ECONOMETRICS, Issue 4 2009Hamid Mohtadi This paper models the stochastic behavior of large-scale terrorism using extreme value methods. We utilize a unique dataset composed of roughly 26,000 observations. These data provide a rich description of domestic and international terrorism between 1968 and 2006. Currently, a credible worst-case scenario would involve losses of about 5000 to 10,000 lives. Also, the return time for events of such magnitude is shortening every year. Today, the primary threat is from conventional weapons, rather than from chemical, biological and/or radionuclear weapons. However, pronounced tails in the distribution of these incidents suggest that this threat cannot be dismissed. Copyright © 2009 John Wiley & Sons, Ltd. [source] An extortionary guerrilla movementJOURNAL OF APPLIED ECONOMETRICS, Issue 6 2007Norman Offstein This paper models an extortionary relationship between a pipeline operator and a guerrilla movement. Payment and attack decisions are modeled as an infinite-horizon Markov decision process, where each period the oil company chooses to pay or not pay an extortion demand and the movement decides to attack or not. Decisions depend on the level of single-period payoff and discounted expected future payoffs. We estimate the model with pipeline attack data and compare parameters when the discount factor is changed. We reject a zero discount factor hypothesis, demonstrating that the movement's observed attack pattern is compatible with extortionary behavior. Copyright © 2007 John Wiley & Sons, Ltd. [source] The significance of wing pattern diversity in the Lycaenidae: mate discrimination by two recently diverged speciesJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2002J. A. Fordyce Abstract Closely related species of lycaenid butterflies are determinable, in part, by subtle differences in wing pattern. We found that female wing patterns can act as an effective mate-recognition signal in some populations of two recently diverged species. In field experiments, we observed that males from a Lycaeides idas population and an alpine population of L. melissa preferentially initiate courtship with conspecific females. A morphometric study indicated that at least two wing pattern elements were important for distinguishing the two species: hindwing spots and orange crescent-shaped pattern elements called aurorae. We deceived male L. idas into initiating courtship with computer generated paper models of heterospecific females when these pattern elements were manipulated, indicating that the wing pattern elements that define the diversity of this group can be effective mate recognition signals. [source] The option to change the use of a property when future property values and construction costs are uncertainMANAGERIAL AND DECISION ECONOMICS, Issue 7 2001Åke Gunnelin This paper models the decision to change the use of a property when its value in the current use and the new use, as well as construction costs, are uncertain. In the case of development of vacant land, when cash flows and construction costs are lognormally distributed, the development of the property optimally takes place when the ratio of benefit to cost of development reaches some fixed level. In the redevelopment case, the timing problem is found to be more complex, as the cost of exercising the conversion option consists of two parts, the construction costs and the surrendered value of the property in the current use, which may evolve differently over time. In this case, optimal redevelopment will take place for different benefit,cost ratios, depending on the relative sizes of the property values in the different uses and the construction costs. Also, for a given current benefit,cost ratio, the option value will vary significantly, depending on the relative size of the state variables. Copyright © 2001 John Wiley & Sons, Ltd. [source] A Vector Autoregressive Analysis Of An Oil-Dependent Emerging Economy , NigeriaOPEC ENERGY REVIEW, Issue 4 2000O. Felix Ayadi This paper models the interrelationship among a variety of macroeconomic variables representing the financial, as well as the energy, sectors of the Nigerian economy from 1975 through 1994. The attempt is to investigate the impact of the energy sector on the functioning of the Nigerian economy, including the financial markets. The investigation is explored within a vector autoregressive (VAR) system. The results reveal that the energy sector exerts a significant influence on the Nigerian economy by acting as a prime mover. More importantly, Nigeria seems to find itself in a vicious circle, because of its inability to exercise control over the price of its main export and its imports. Thus, the strength and autonomy exhibited by Nigerias macroeconomic managers during the oil boom era appears to have been barren. [source] Modeling the effects of health status and the educational infrastructure on the cognitive development of Tanzanian schoolchildrenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2005Alok Bhargava This paper models the proximate determinants of school attendance and scores on cognitive and educational achievement tests and on school examinations of over 600 schoolchildren from the Control group of a randomized trial in Tanzania, where children in the Intervention group heavily infected with hookworm and schistosomiasis received treatment. The modeling approach used a random effects framework and incorporated the inter-relationships between school attendance and performance on various tests, controlling for children's health status, socioeconomic variables, grade level, and the educational infrastructure. The empirical results showed the importance of variables such as children's height and hemoglobin concentration for the scores, especially on educational achievement tests that are easy to implement in developing countries. Also, teacher experience and work assignments were significant predictors of the scores on educational achievement tests, and there was some evidence of multiplicative effects of children's heights and work assignments on the test scores. Lastly, some comparisons were made for changes in test scores of treated children in the Intervention group with the untreated children in the Control group. Am. J. Hum. Biol. 17:280,292, 2005. © 2005 Wiley-Liss, Inc. [source] A Cournot,Nash Model of Family Decision MakingTHE ECONOMIC JOURNAL, Issue 474 2001Zhiqi Chen This paper models a two-person family. Each family member is utility maximising, yet family members are interdependent because of caring and public goods within the family. The two family members' interdependent utility maximisation problems are first solved using a non-cooperative, or Cournot,Nash, game theoretic framework. The Cournot,Nash equilibrium is then used as a threat point in a bargaining game. The paper provides a rigorous derivation of the properties of household demands, a full analysis of the determinants of intra-household resource allocation, including the effect of varying household bargaining power, and consideration of policy implications. [source] Optimal model for warehouse location and retailer allocationAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 3 2007Avninder Gill Abstract Warehouse location and retailer allocation is a high-level strategic decision problem that is commonly encountered by logisticians and supply chain managers, especially during the supply chain design phase. Considering the product distribution cost and warehouse capital cost trade-offs, this paper models the warehouse location and retailer allocation problem as a 0,1 integer programming problem and provides an efficient two-stage set covering heuristic algorithm to solve large-sized problems. Finally, concluding remarks and some recommendations for further research are also presented. Copyright © 2007 John Wiley & Sons, Ltd. [source] PRIVATISATION AND TIMING IN A MIXED OLIGOPOLY WITH BOTH FOREIGN AND DOMESTIC FIRMS,AUSTRALIAN ECONOMIC PAPERS, Issue 4 2009JOHN S. HEYWOOD This paper models a mixed oligopoly with both a domestic and a foreign private firm and examines the resulting timing in the quantity setting game. We demonstrate that with a single simultaneous pre-game delay stage, the resulting endogenous timing has either the public firm leading or the two private firms leading. An alternative characterisation of the pre-game stage results in the single timing in which the two private firms lead and the public firm follows. For all timings that emerge endogenously, we show that privatisation will always lower domestic welfare but its influence on global welfare is ambiguous. [source] | |||||||||||||