Car-following techniques: reconsidering the role of the human factor

Keeping correct distance between vehicles is a fundamental tenet in road traffic. New road signs and markings appearing on motorways aid drivers in determining this distance. However, the ‘Nagoya experiment’ (Sugiyama et al., 2008) revealed correct distance made following safe while also eventually destabilizing traffic flow. When traffic becomes dense, most drivers keep the minimum safety distance and brake when the vehicle ahead decelerates. The resultant chain reaction along the entire line of closely following vehicles causes for no apparent reason a traffic stoppage, known as a ‘phantom’ or ‘shockwave’ jam. The car-following models of Sugiyama et al. found certain speeds, traffic densi…

NAUTILUS Navigator : free search interactive multiobjective optimization without trading-off

We propose a novel combination of an interactive multiobjective navigation method and a trade-off free way of asking and presenting preference information. The NAUTILUS Navigator is a method that enables the decision maker (DM) to navigate in real time from an inferior solution to the most preferred solution by gaining in all objectives simultaneously as (s)he approaches the Pareto optimal front. This means that, while the DM reaches her/his most preferred solution, (s)he avoids anchoring around the starting solution and, at the same time, sees how the ranges of the reachable objective function values shrink without trading-off. The progress of the motion towards the Pareto optimal front is…

NAUTILUS method: An interactive technique in multiobjective optimization based on the nadir point

Most interactive methods developed for solving multiobjective optimization problems sequentially generate Pareto optimal or nondominated vectors and the decision maker must always allow impairment in at least one objective function to get a new solution. The NAUTILUS method proposed is based on the assumptions that past experiences affect decision makers’ hopes and that people do not react symmetrically to gains and losses. Therefore, some decision makers may prefer to start from the worst possible objective values and to improve every objective step by step according to their preferences. In NAUTILUS, starting from the nadir point, a solution is obtained at each iteration which dominates t…

Relación de las fiestas que hizo el Colegio de la Compañía de Iesus de Girona en la canonización de su Patriarca San Ignacio i del Apostol de la Judia San Francisco Xavier, i la beatificacion del angelico Luis Gonzaga : Con el torneo poetico mantenido i premiado por Don Martin de Agullana ... / por Francisco Ruiz ...

La f. de grav. es un frontispici calc.: "C. A. F." La port. i totes les f. orlades Errates tip. a la fol.: de la f. 46 passa a la 45, de la 48 a la 47 Sign.: [ ]1, ýý3, [ ]1, A-L4, M8, N-Z4, Aa-Mm4 (l'últ. en bl.)

On the Use of Preferential Weights in Interactive Reference Point Based Methods

We introduce a new way of utilizing preference information specified by the decision maker in interactive reference point based methods. A reference point consists of aspiration levels for each objective function. We take the desires of the decision maker into account more closely when projecting the reference point to become nondominated. In this way we can support the decision maker in finding the most satisfactory solutions faster. In practice, we adjust the weights in the achievement scalarizing function that projects the reference point. We demonstrate our idea with an example and we summarize results of computational tests that support the efficiency of the idea proposed.

Cambios en la estructura y localización de la población: Una visión de largo plazo (1842-2011)

El período intercensal 2001-2011 ha resultado ser el de mayor crecimiento poblacional en la historia española, tanto en términos absolutos, con un incremento cercano a los seis millones de habitantes, como relativos, con un crecimiento del 14,6%. Esta explosión demográfica no ha sido homogénea. El volumen de extranjeros se ha multiplicado por un factor superior a 3 con un crecimiento absoluto superior al de los españoles: mientras estos crecieron en 2,3 millones entre ambos censos, los extranjeros aumentaron en 3,7 millones. Si bien es cierto que las alteraciones municipales ocurridas entre los censos de 2001 y 2011 han sido escasas –ocho segregaciones–, los profundos cambios metodológicos …

Tumor de células granulares de piel mamaria : Estudio morfológico de dos casos mostrando inmunorreactividad frente a-inhibina

Introducción: El tumor de células granulares (TCG) es una lesión infrecuente en la mama, representando solo el 6-8% de los TCG, comprometiendo a menudo a la piel mamaria. Pacientes y métodos: Se revisa la casuística de TCG mamarios del Hospital Universitario La Fe de Valencia en un período de 19 años, con un total de 8000 especímenes biópsicos mamarios con 2200 diagnósticos de cáncer, realizando de forma retrospectiva un estudio morfológico (óptico, inmunohistoquímico y ultraestructural) a partir de material incluido en parafina. Resultados: Se detectan dos casos de TCG con afectación de piel mamaria con distinta presentación clínica (TCG como nódulo tumoral único y TCG como lesión tumoral …

Incorporating preference information in interactive reference point methods for multiobjective optimization

In this paper, we introduce new ways of utilizing preference information specified by the decision maker in interactive reference point based methods. A reference point consists of desirable values for each objective function. The idea is to take the desires of the decision maker into account more closely when projecting the reference point onto the set of nondominated solutions. In this way we can support the decision maker in finding the most satisfactory solutions faster. In practice, we adjust the weights in the achievement scalarizing function that projects the reference point. We identify different cases depending on the amount of additional information available and demonstrate the c…

E-NAUTILUS: A decision support system for complex multiobjective optimization problems based on the NAUTILUS method

Interactive multiobjective optimization methods cannot necessarily be easily used when (industrial) multiobjective optimization problems are involved. There are at least two important factors to be considered with any interactive method: computationally expensive functions and aspects of human behavior. In this paper, we propose a method based on the existing NAUTILUS method and call it the Enhanced NAUTILUS (E-NAUTILUS) method. This method borrows the motivation of NAUTILUS along with the human aspects related to avoiding trading-off and anchoring bias and extends its applicability for computationally expensive multiobjective optimization problems. In the E-NAUTILUS method, a set of Pareto…

Designing empirical experiments to compare interactive multiobjective optimization methods

Interactive multiobjective optimization methods operate iteratively so that a decision maker directs the solution process by providing preference information, and only solutions of interest are generated. These methods limit the amount of information considered in each iteration and support the decision maker in learning about the trade-offs. Many interactive methods have been developed, and they differ in technical aspects and the type of preference information used. Finding the most appropriate method for a problem to be solved is challenging, and supporting the selection is crucial. Published research lacks information on the conducted experiments’ specifics (e.g. questions asked), makin…

Typology and Representation of Alterations in Territorial Units: A Proposal

Abstract This article proposes a typology of boundary changes in territorial units at two points in time. The different types of changes are organized in a hierarchy and represented homogeneously, independently of the number of territorial units involved and of the changes to them. Each alteration is described precisely and unambiguously, and it is codified to allow the information to be treated automatically. In addition to providing efficient storage of the information about these changes, a canonical representation facilitates the automatic detection of inconsistencies in the database. At the same time, the typology allows us to define backward and forward equivalence rules, which helps …

A two-slope achievement scalarizing function for interactive multiobjective optimization

The use of achievement (scalarizing) functions in interactive multiobjective optimization methods is very popular, as indicated by the large number of algorithmic and applied scientific papers that use this approach. Key parameters in this approach are the reference point, which expresses desirable objective function values for the decision maker, and weights. The role of the weights can range from purely normalizing to fully preferential parameters that indicate the relative importance given by the decision maker to the achievement of each reference value. Technically, the influence of the weights in the solution generated by the achievement scalarizing function is different, depending on …

Organometallic Nickel(II) Complexes Containing Thiolate and Dithiocarbamate Ligands

A new preference handling technique for interactive multiobjective optimization without trading-off

Because the purpose of multiobjective optimization methods is to optimize conflicting objectives simultaneously, they mainly focus on Pareto optimal solutions, where improvement with respect to some objective is only possible by allowing some other objective(s) to impair. Bringing this idea into practice requires the decision maker to think in terms of trading-off, which may limit the ability of effective problem solving. We outline some drawbacks of this and exploit another idea emphasizing the possibility of simultaneous improvement of all objectives. Based on this idea, we propose a technique for handling decision maker’s preferences, which eliminates the necessity to think in terms of t…

NAUTILUS framework : towards trade-off-free interaction in multiobjective optimization

In this paper, we present a framework of different interactive NAUTILUS methods for multiobjective optimization. In interactive methods, the decision maker iteratively sees solution alternatives and provides one’s preferences in order to find the most preferred solution. We question the widely used setting that the solutions shown to the decision maker should all be Pareto optimal which implies that improvement in any objective function necessitates allowing impairment in some others. Instead, in NAUTILUS we enable the decision maker to make a free search without having to trade-off by starting from an inferior solution and iteratively approaching the Pareto optimal set by allowing all obje…

Assessing the Performance of Interactive Multiobjective Optimization Methods

Interactive methods are useful decision-making tools for multiobjective optimization problems, because they allow a decision-maker to provide her/his preference information iteratively in a comfortable way at the same time as (s)he learns about all different aspects of the problem. A wide variety of interactive methods is nowadays available, and they differ from each other in both technical aspects and type of preference information employed. Therefore, assessing the performance of interactive methods can help users to choose the most appropriate one for a given problem. This is a challenging task, which has been tackled from different perspectives in the published literature. We present a …