7,170 research outputs found
Intertemporal and Spatial Location of Disposal Facilities
The optimal capacity and location of a sequence of landfills are studied, and the interactions between both decisions are pointed out. Deciding the capacity of a landfill has some spatial implications, because it effects the feasible region for the rest of the landfills, and some temporal implications because the capacity determines the lifetime of the landfill and hence the instant of time where the next landfills will need to be constructed. Some general mathematical properties of the solution are provided and interpreted from an economic point of view. The resulting problem turns out to be nonconvex and, therefore, it can not be solved by conventional optimization techniques. Some global optimization methods are used to solve the problem in a particular case to illustrate the behavior of the solution depending on the parameter values.Landfilling, Optimal Capacity, Optimal Location, Global Optimization.
Improving Third-Party Relaying for LTE-A: A Realistic Simulation Approach
In this article we propose solutions to diverse conflicts that result from
the deployment of the (still immature) relay node (RN) technology in LTE-A
networks. These conflicts and their possible solutions have been observed by
implementing standard-compliant relay functionalities on the Vienna simulator.
As an original experimental approach, we model realistic RN operation, taking
into account that transmitters are not active all the time due to half-duplex
RN operation. We have rearranged existing elements in the simulator in a manner
that emulates RN behavior, rather than implementing a standalone brand-new
component for the simulator. We also study analytically some of the issues
observed in the interaction between the network and the RNs, to draw
conclusions beyond simulation observation.
The main observations of this paper are that: ) Additional time-varying
interference management steps are needed, because the LTE-A standard employs a
fixed time division between eNB-RN and RN-UE transmissions (typical relay
capacity or throughput research models balance them optimally, which is
unrealistic nowadays); ) There is a trade-off between the time-division
constraints of relaying and multi-user diversity; the stricter the constraints
on relay scheduling are, the less flexibility schedulers have to exploit
channel variation; and ) Thee standard contains a variety of parameters
for relaying configuration, but not all cases of interest are covered.Comment: 17 one-column pages, 9 figures, accepted for publication in IEEE ICC
2014 MW
DOES SERVICE QUALITY MATTER IN MEASURING PERFORMANCE OF WATER UTILITIES?
Quality is a dimension of water services that has been repeatedly omitted in the study of performance of water utilities. In this paper, we make use of Data Envelopment Analysis techniques (DEA) to compute both conventional quantity-based and quality-adjusted indicators of technical efficiency for a sample of Spanish water utilities. The key assumptions are that a lack of quality (bad quality) can be regarded as a bad output, and the existence of a trade-off between quantity and quality. Our main results indicate that quality matters in measuring technical performance, the difference between conventional and quality-adjusted evaluations representing the opportunity cost of maintaining quality. Averages and distribution functions significantly differ between both assessments of performance, although water utilities do not seem to rank differently.water utilities; quality; Data Envelopment Analysis.
Does it pay to be socially responsible? Evidence from Spanish retail banking sector
This paper presents a theoretical and empirical analysis of strategic competition in retail banking when some of the financial firms are non-profit organisations that invest in social activities. Banking literature about competition is fairly large, but the strategic interaction between profit maximizing and non profit maximizers has not been extensively analysed except for Purroy and Salas (1999). In this paper, a completely different approach is taken. An adaptation of Hotellingâs two stage model of spatial competition is developed to take into account consumer perceptions respect to the two different types of financial institutions. The empirical analysis confirms that consumers take into account other features different from the price, such as social contribution or closer service to make a deposit or mortgage decision. These conclusions are of interest in the debate about a firmâs social or ethical activities. It is shown that if consumers value social activities, firms can improve their results by behaving socially responsible.Strategic competition; HotellingÂŽs model; Spanish banking; Corporate social responsibility
Can we be satisfied with our football team? Evidence from spanish professional football.
This paper assesses the sporting performance of Spanish professional football teams at competition level, namely, League, Kingâs Cup and European competitions (Champions League and UEFA Cup). Then, the gap between the result obtained by a team in a given competition and that expected according to its potential is used as a proxy of the degree of satisfaction that fans should feel: the narrower the gap the greater the level of satisfaction. Regarding methodology, Data Envelopment Analysis techniques and directional distance functions are used. Results reveal that most teams perform rather differently across competitions, the lower average performance corresponding to the Kingâs CupSpanish football League; specific-competition performance; Data Envelopment Analysis.
Resurrection of the sea pen genus Ptilella Gray, 1870 and description of Ptilella grayi n. sp. from the NE Atlantic (Octocorallia: Pennatulacea)
The order Pennatulacea covers a group of specialized and morphologically distinct octocorals found in all oceans from intertidal areas to more than 6000 m in depth. Sea pens constitute an important structural component in marine soft-bottom communities by increasing the complexity of these environments. Despite being both morphologically distinctive and ecologically important, the taxonomy and systematics of sea pens is still poorly understood. Recent molecular studies have shown the existence of convergent morphological features, making the current familial distribution of genera unstable. The genus Pennatula Linnaeus, 1758 was one of the first described octocoral genera. It is the type genus of its family, Pennatulidae. Colonies of this genus have a characteristic morphology. Recent sampling efforts in the northeastern Atlantic have provided a number of colonies initially attributable to the genus Pennatula. Both morphological and molecular (mtMutS, Cox1 and 28S genes) study of this material supports the polyphyletic nature of this genus and the need to resurrect the genus Ptilella Gray, 1870 to accommodate these and other species. A new species, Ptilella grayi n. sp., is described and illustrated. The species Pennatula bayeri is proposed to be a junior synonym of Pennatula bellissima (here also considered in the genus Ptilella)
Antonio Ignacio MOLINA MARĂN, Geographica: ciencia del espacio y tradiciĂłn narrativa de Homero a Cosmas Indicopleustes, Murcia, Universidad de Murcia, 2010 (AntigĂŒedad y cristianismo. MonografĂas histĂłricas sobre la AntigĂŒedad TardĂa, XXVII), 525 pp. ISSN
Reseña de Antonio Ignacio Molina MarĂn, Geographica: ciencia del espacio y tradiciĂłn narrativa de Homero a Cosmas Indicopleustes, Murcia, Universidad de Murcia, 2010 (AntigĂŒedad y cristianismo. MonografĂas histĂłricas sobre la AntigĂŒedad TardĂa, XXVII), 525 pp. ISSN 0214-7165
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