Visual and interactive exploration of point data

Point data, such as Unit Postcodes (UPC), can provide very detailed information at fine scales of resolution. For instance, socio-economic attributes are commonly assigned to UPC. Hence, they can be represented as points and observable at the postcode level. Using UPC as a common field allows the concatenation of variables from disparate data sources that can potentially support sophisticated spatial analysis. However, visualising UPC in urban areas has at least three limitations. First, at small scales UPC occurrences can be very dense making their visualisation as points difficult. On the other hand, patterns in the associated attribute values are often hardly recognisable at large scales. Secondly, UPC can be used as a common field to allow the concatenation of highly multivariate data sets with an associated postcode. Finally, socio-economic variables assigned to UPC (such as the ones used here) can be non-Normal in their distributions as a result of a large presence of zero values and high variances which constrain their analysis using traditional statistics. This paper discusses a Point Visualisation Tool (PVT), a proof-of-concept system developed to visually explore point data. Various well-known visualisation techniques were implemented to enable their interactive and dynamic interrogation. PVT provides multiple representations of point data to facilitate the understanding of the relations between attributes or variables as well as their spatial characteristics. Brushing between alternative views is used to link several representations of a single attribute, as well as to simultaneously explore more than one variable. PVT’s functionality shows how the use of visual techniques embedded in an interactive environment enable the exploration of large amounts of multivariate point data

Usability testing for improving interactive geovisualization techniques

Usability describes a product’s fitness for use according to a set of predefined criteria. Whatever the aim of the product, it should facilitate users’ tasks or enhance their performance by providing appropriate analysis tools. In both cases, the main interest is to satisfy users in terms of providing relevant functionality which they find fit for purpose. “Testing usability means making sure that people can find and work with [a product’s] functions to meet their needs” (Dumas and Redish, 1999: 4). It is therefore concerned with establishing whether people can use a product to complete their tasks with ease and at the same time help them complete their jobs more effectively. This document describes the findings of a usability study carried out on DecisionSite Map Interaction Services (Map IS). DecisionSite, a product of Spotfire, Inc.,1 is an interactive system for the visual and dynamic exploration of data designed for supporting decisionmaking. The system was coupled to ArcExplorer (forming DecisionSite Map IS) to provide limited GIS functionality (simple user interface, basic tools, and data management) and support users of spatial data. Hence, this study set out to test the suitability of the coupling between the two software components (DecisionSite and ArcExplorer) for the purpose of exploring spatial data. The first section briefly discusses DecisionSite’s visualization functionality. The second section describes the test goals, its design, the participants and data used. The following section concentrates on the analysis of results, while the final section discusses future areas of research and possible development

On Prices in Myrdal's Monetary Theory

The aim of this paper is to show how Myrdal monetary theory can contribute to the study of the behaviour of prices in disequilibrium. The analysis explains the existence of a cumulative process based on the capacity of the entrepreneur to anticipate price variations. The variation in prices explains the persistence of the cumulative process. This, we argue, represents an opposite view of the one contained in Wicksell's theory. Myrdal's theory leads to the rejection of the quantity theory of money based on Wicksell's approach. This comes as a surprising result knowing Wicksell believed his results confirmed this theory.Myrdal; monetary equilibrium; cumulative process; prices; profit

Un mecanismo de precios para la teoría del valor

Este artículo tiene como objetivo mostrar la aplicación que tiene la regla Cantillon-Smith en la teoría marxista de la plusvalía y en la teoría del equilibrio general. En ambas, la regla actúa como un mecanismo de formación de precios de mercado monetarios. Para tal fin, explicamos dos modelos. El primero es un modelo Benetti-Cartelier con relaciones capitalistas, y el segundo, un modelo de equilibrio general walrasiano sin subastador. Luego de mostrar la operatividad de la regla en los dos, señalamos algunas de las ventajas y desventajas que ofrece su utilización como expresión de la compatibilidad de las decisiones descentralizadas de los agentes en una economía abstracta.valor; dinero; plusvalía; salario; precio; desequilibrio

Earmarking government revenues in Colombia

This paper has two broad objectives. The first is the examination of the trends in the size and structure of earmarking since 1970, illuminating the major changes and their causes. The second is an evaluation of the major examples of earmarking with a view toward making recommendations for change. In making recommendations for reducing the scope of earmarking in Colombia, several principles should be used for guidance: (a) is there a substantial overlap between the beneficiaries and the tax/price payers for any given government service; (b) do the tax/price arrangements appear to be leading to appropriate levels of the service over time; and (c) are resources being utilized effectively for the purpose intended. The remainder of the paper is divided into four parts: (a) time series data on the size and structure of earmarking during the last two decades; (b) factors behind the popularity of earmarking in Colombia and a review of the findings and recommendations of two major government commissions which have examined the subject; (c) a critical review of the major examples which make up over 90% of total earmarking; and (d) a summary of major findings and recommendations for changes.Economic Theory&Research,Public Sector Economics&Finance,Environmental Economics&Policies,National Governance,Banks&Banking Reform

La crítica de Hicks al Tratado del Dinero de Keynes

El objetivo de este artículo es mostrar que la crítica que hace Hicks al Tratado del Dinero de Keynes es incorrecta. Para ello, presentamos el modelo de Keynes, mostrando que la igualdad entre la inversión y el ahorro es una condición de equilibrio monetario y no una identidad. Este resultado no puede ser obtenido en el análisis de Hicks.Keynes; Hicks; precios; beneficios; ahorro; inversión

CNC Machine Tool's wear diagnostic and prognostic by using dynamic bayesian networks.

International audienceThe failure of critical components in industrial systems may have negative consequences on the availability, the productivity, the security and the environment. To avoid such situations, the health condition of the physical system, and particularly of its critical components, can be constantly assessed by using the monitoring data to perform on-line system diagnostics and prognostics. The present paper is a contribution on the assessment of the health condition of a Computer Numerical Control (CNC) tool machine and the estimation of its Remaining Useful Life (RUL). The proposed method relies on two main phases: an off-line phase and an on-line phase. During the first phase, the raw data provided by the sensors are processed to extract reliable features. These latter are used as inputs of learning algorithms in order to generate the models that represent the wear's behavior of the cutting tool. Then, in the second phase, which is an assessment one, the constructed models are exploited to identify the tool's current health state, predict its RUL and the associated confidence bounds. The proposed method is applied on a benchmark of condition monitoring data gathered during several cuts of a CNC tool. Simulation results are obtained and discussed at the end of the paper

A mixture of gaussians hidden markov model for failure diagnostic and prognostic.

International audienceThis paper deals with a data-driven diagnostic and prognostic method based on a Mixture of Gaussians Hidden Markov Model. The prognostic process of the proposed method is made in two steps. In the first step, which is performed offline, the monitoring data provided by sensors are processed to extract features, which are then used to learn different models that capture the time evolution of the degradation and therefore of the system's health state. In the second step, performed online, the learned models are exploited to do failure diagnostic and prognostic by estimating the asset's current health state, its remaining useful life and the associated confidence degree. The proposed method is tested on a benchmark data related to several bearings and simulation results are given at the end of the paper

Hidden Markov models for failure diagnostic and prognostic.

International audienceThis paper deals with an estimation of the Remaining Useful Life of bearings based on the utilization of Mixture of Gaussians Hidden Markov Models (MoG-HMMs). The raw signals provided by the sensors are first processed to extract features, which permit to model the physical component and its degradation. The prognostic process is done in two phases: a learning phase and an evaluation phase. During the first phase, the sensors' data are processed in order to extract appropriate and useful features, which are then used as inputs of dedicated learning algorithms in order to estimate the parameters of a MoG-HMM. The obtained model represents the behavior of the component including its degradation. In addition, the model contains the number of health states and the stay durations in each state. Once the learning phase is done, the generated model is exploited during the second phase, where the extracted features are continuously injected to the learned model to assess the current health state of the physical component and to estimate its remaining useful life and the associated confidence. The proposed method is tested on a benchmark data taken from the "NASA prognostic data repository" related to bearings used under several operating conditions. Moreover, the developed method is compared to two methods: the first using traditional HMMs with exponential time durations and the second using regular Hidden Semi Markov Model (HSMM). Finally, simulation results are given and discussed at the end of the paper

CNC machine tool health assessment using Dynamic Bayesian Networks.

International audienceThe failure of critical components in physical systems may have negative consequences on the availability, the productivity, their security and on the environment. Thus, the assessment of the critical component's health condition, which can be done in the diagnostic and prognostic framework, should be constantly ensured. In this paper, a contribution on the assessment of the health condition of the cutting tool from a Computer Numerical Control (CNC) machine tool and the prediction of its remaining useful life before its complete failure is addressed. The proposed method is based on the use of monitoring data and relies on two main phases: an off-line phase and an on-line phase. During the first phase, the raw data provided by the sensors are processed to extract reliable features. These latter are then fed as inputs to the learning algorithms in order to generate relevant models that best represent the behavior of the cutting tool. The second phase is an assessment one, which uses the constructed models to identify the current health state and to compute the remaining useful life and the associated confidence value. The method is applied on monitoring data gathered during several cuts of the CNC tool and simulation results are given and discussed