1,721,018 research outputs found
Is accessibility relevant in trip generation? Modelling the interaction between trip generation and accessibility taking into account spatial effects
No full textThe influence of accessibility to opportunities in trip generation continues to be debated in the specialised literature given its relevance to simulate phenomena such as induced demand. This article estimates multiple linear regression models (MLR), spatial autoregressive models (SAR), spatial autoregressive models in the error term (SEM) and spatially filtered Poisson regression models (SPO) to discover whether or not accessibility is a significant factor in trip generation using data from the urban area of Santander (Spain). The results obtained provide evidence which shows that, on an intraurban scale, more accessibility to opportunities decreases trip production in private vehicle for work purpose, whereas it increases trip production in other transport modes for non—mandatory purposes. For the correct interpretation of the estimated parameters it was important to consider the direct and indirect effects of the independent variables in the SAR production models. Finally, the validation of the models showed that the SAR and SEM models had a mean squared error slightly lower than the MLR models in predicting overall trip production. This was because the spatial models reduced the correlation of the residuals present in the MLR models. Furthermore, the SPO models performed better in validation mode than all the continuous model
Modelling the spatial interactions between workplace and residential location
Full text linkThe use of Multinomial Logit (MNL) models specification for the simulation of residential
location have been often criticised due to the Independence of Irrelevant Alternatives
hypothesis (IIA) which does not allow for the existence of spatial correlation between residential
zones. Moreover, it is not clear when and to what extent the influence of the workplace
zone and accessibility to employment affect the residential location choices made by
households; in other word, whether the residing choice is conditional to the workplace, or
vice versa; or if such choices (residence and work place) are joint.
In this paper, Nested Logit (NL) and Cross-Nested Logit models of residential location
choice are specified and compared to MNL, to investigate the existence of spatial correlation
between different locations. Furthermore, different assumptions are tested, considering
the choice of residential zone and the joint choice of residential zone and work place
zone.
The models were estimated for the urban area of Santander (Spain). The results indicate
that the inclusion in the model specification, of the spatial correlation between zones fit
the data significantly better. Home-work journey times were a statistically significant factor
in household location choice, whereas accessibility to employment had the correct sign
but it was not statistically significant
Chattering-free robust finite-time output feedback control scheme for a class of uncertain non-linear systems
Full text linkIn this study, an innovative technique to design an observer-based finite-time output feedback controller (FT-OFC) is proposed for a class of non-linear systems. This controller aims to make the state variables converge to a small bound around the origin in a finite time. The main innovation of this study is to transform the non-linear system into a new time-varying form to achieve the finite-time boundedness criteria using the asymptotic stability methods. Moreover, without any prior knowledge of the upper bounds of the system uncertainties and/or disturbances, and only based on the output measurements, a novel timevarying extended state observer is designed to estimate the states of the non-linear system as well as the uncertainties and disturbances in a finite time. In this way, the time-varying gains of the extended state observer are designed to converge the observation error to a neighbourhood of zero while remaining uniformly bounded in finite time. Subsequently, an observer-based time-varying control law is designed to make the system globally uniformly bounded in finite time. Finally, the efficiency of the proposed FT-OFC for a disturbed double integrator system with unknown measurement noise is illustrated by numerical simulations
Una evaluación de las relaciones entre las condiciones de transporte y los precios inmobiliarios mediante el uso de modelos hedónicos espaciales
No full textEn la presente ponencia se especifica un modelo hedónico de regresión lineal múltiple (MLR), un modelo hedónico autoregresivo espacial (SAR), un modelo hedónico autoregresivo espacial en el término de error (SEM) y un modelo hedónico espacial Durbin (SDM) para estimar los precios inmobiliarios de una serie de viviendas. Los cuatro tipos de modelos han sido aplicados al área metropolitana de Santander (Cantabria, España) con el objetivo de obtener una estimación de los impactos provocados en el precio de los inmuebles por cambios en las condiciones de transporte. Se comparará además la bondad de ajuste de los distintos modelos y se contrastarán una serie de hipótesis metodológicas sobre el rendimiento de las especificaciones que consideran la existencia de relaciones espaciales entre observaciones.
En el caso de Santander, el uso de modelos que consideran la dependencia espacial entre observaciones permitió ofrecer un mayor grado de ajuste en un escenario donde se detectó una fuerte correlación espacial en los residuos de los modelos MLR derivados, seguramente, de problemas de especificación. El modelo SEM combinado con una matriz de vecindad con contigüidad tipo reina ofreció un buen ajuste a los datos a la vez que presentó parámetros significativos y signos teóricamente coherentes. Este modelo permitió estimar incrementos medios de más del 1% por cada línea adicional de bus presente en las cercanías de los inmuebles, así como reducciones del 1% en el precio de éstos por cada minuto adicional de tiempo de viaje al centro urbano. La cercanía a estaciones de tren supuso sin embargo una reducción en el precio de los inmuebles lo que seguramente se debió a las externalidades negativas derivadas de este tipo de equipamientos
Modeling The Effects of Environmental Impacts and Accessibility on Real Estate Prices in Industrial Cities
Full text linkThis article presents hedonic Multiple Linear Regression models (MLR) to estimate real estate price variations in metropolitan areas as a result of changing environmental and accessibility conditions. The goodness of fit of the model has been compared along with a series of hypotheses about the performance of the specifications considering spatial relationships between observations. The case study for such analysis is the metropolitan area of Taranto (Southern Italy). The models which considered spatial dependence between observations offered a greater degree of fit in a scenario showing strong spatial correlation in MLR residual
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
STOP: A Short term Transit Occupancy Prediction tool for APTIS and real time transit management systems
No full textThe paper presents a Short term Transit Occupancy Predictor tool (STOP), which allows to evaluate and predict the number of on-board passengers for each vehicle of the transit system using also real-time information on passenger counts, if available. The first part describes the user needs and the logical architecture of the tool. The second part deals with the modeling framework implemented to provide the best real time vehicle occupancy predictions. Finally, the results of a preliminary real case application are presented
Impactos de la accesibilidad mediante transporte público en los valores inmobiliarios: una comparación entre las ciudades de Roma y Santander
Full text linkExiste evidencia empírica que avala la hipótesis de que incrementos en la accesibilidad a oportunidades pueden impactar positivamente en los valores inmobiliarios. Sin embargo, esta capitalización de los beneficios de la accesibilidad puede ser desigual en distintas áreas de estudio. En esta investigación se estiman modelos hedónicos y modelos hedónicos espaciales en dos áreas urbanas para comparar si existen diferencias en los impactos de la accesibilidad utilizando transporte público. Las dos áreas de estudio seleccionadas han sido una ciudad media sin grandes problemas de movilidad (Santander, España) y una gran ciudad con elevados problemas de congestión (Roma, Italia). Los modelos hedónicos estimados han considerado la posible existencia de efectos espaciales, habitualmente presentes en los datos inmobiliarios, que pueden generar dependencia en los residuos de los modelos hedónicos. La accesibilidad se ha medido utilizando dos tipos de indicadores: de accesibilidad relativa y gravitatoria. Los resultados permiten afirmar que la accesibilidad fue un factor positivo en el precio de los valores inmobiliarios de ambas ciudades, si bien en el caso de Santander únicamente de forma relativa al centro urbano. Estos resultados son relevantes de cara a implementar políticas de captura del valor que permitan financiar nuevos proyectos de transporte públic
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