Crowding Perception in a Tourist City: A Question of Preference

Two main topics are analysed in this paper: a crowding model for an urban destination is tested by the use of a binary logistic model in order to identify the variables influencing crowding perception; and the inherent negativity of the crowding concept, as is often assumed, is examined through association statistics. The results confirmed that personal and behavioural variables have a larger effect on the perception of crowding than use-level. Furthermore, the relationship between crowding and experience, while significantly negative, could only be found in respondents with a preference for low, and a perception of high, use levels, while for the majority of individuals the perception of a certain crowding level did not lead to a negative evaluation of the conditions. This proves that the concept of crowding cannot be assumed to be implicitly negative, and needs individual preferences to be fully understood.status: publishe

The preemptive repeat hybrid server interruption model

We analyze a discrete-time queueing system with server interruptions and a hybrid preemptive repeat interruption discipline. Such a discipline encapsulates both the preemptive repeat identical and the preemptive repeat different disciplines. By the introduction and analysis of so-called service completion times, we significantly reduce the complexity of the analysis. Our results include a.o. the probability generating functions and moments of queue content and delay. Finally, by means of some numerical examples, we assess how performance measures are affected by the specifics of the interruption discipline

An approximation approach for the deviation matrix of continuous-time Markov processes with application to Markov decision theory

We present an update formula that allows the expression of the deviation matrix of a continuous-time Markov process with denumerable state space having generator matrix Q* through a continuous-time Markov process with generator matrix Q. We show that under suitable stability conditions the algorithm converges at a geometric rate. By applying the concept to three different examples, namely, the M/M/1 queue with vacations, the M/G/1 queue, and a tandem network, we illustrate the broad applicability of our approach. For a problem in admission control, we apply our approximation algorithm toMarkov decision theory for computing the optimal control policy. Numerical examples are presented to highlight the efficiency of the proposed algorithm. © 2010 INFORMS

Distributed Synthesis in Continuous Time

We introduce a formalism modelling communication of distributed agents strictly in continuous-time. Within this framework, we study the problem of synthesising local strategies for individual agents such that a specified set of goal states is reached, or reached with at least a given probability. The flow of time is modelled explicitly based on continuous-time randomness, with two natural implications: First, the non-determinism stemming from interleaving disappears. Second, when we restrict to a subclass of non-urgent models, the quantitative value problem for two players can be solved in EXPTIME. Indeed, the explicit continuous time enables players to communicate their states by delaying synchronisation (which is unrestricted for non-urgent models). In general, the problems are undecidable already for two players in the quantitative case and three players in the qualitative case. The qualitative undecidability is shown by a reduction to decentralized POMDPs for which we provide the strongest (and rather surprising) undecidability result so far

A differential equation for a class of discrete lifetime distributions with an application in reliability: A demonstration of the utility of computer algebra

YesIt is shown that the probability generating function of a lifetime random variable T on a finite lattice with polynomial failure rate satisfies a certain differential equation. The interrelationship with Markov chain theory is highlighted. The differential equation gives rise to a system of differential equations which, when inverted, can be used in the limit to express the polynomial coefficients in terms of the factorial moments of T. This then can be used to estimate the polynomial coefficients. Some special cases are worked through symbolically using Computer Algebra. A simulation study is used to validate the approach and to explore its potential in the reliability context

Urban tourist complexes as Multi-product companies: Market segmentation and product differentiation in Amsterdam

The purpose of this study is to investigate and model the way touristic agents in Amsterdam design and organize their products in order to satisfy the needs of tourists with different geographic origins, characteristics, motivations and purposes. Applying the concept of a multi-product firm to a city, Amsterdam is presented as a multi-product touristic city, where different suppliers offer different services to visitors and are getting benefits from the economies of scope that are generated collectively. The use of the multi-product metaphor aims to analyse how the differentiation of products contributes to meet the needs and motivations of the tourist demand.   A systematic model is designed comprising the various forces as attractions with the city. The model will be fed with available tourism data, both at a micro and a meso scale of observation. A micro-simulation model will next be developed and used, in order to analyse the individual characteristics and behaviour of tourists in Amsterdam. After this first step, a path-analysis will be developed, trying to identify the empirical forces and constraints that shape the conditions for the matching between the needs and motivations of the tourists and the services provided by the touristic agents

M/M/∞\infty queues in semi-Markovian random environment

In this paper we investigate an M/M/$\infty$ queue whose parameters depend on an external random environment that we assume to be a semi-Markovian process with finite state space. For this model we show a recursive formula that allows to compute all the factorial moments for the number of customers in the system in steady state. The used technique is based on the calculation of the raw moments of the measure of a bidimensional random set. Finally the case when the random environment has only two states is deeper analyzed. We obtain an explicit formula to compute the above mentioned factorial moments when at least one of the two states has sojourn time exponentially distributed.Comment: 17 pages, 2 figure