Estimating Perceived Video Quality from Objective Parameters in Video over IP Services

In Video over IP services, perceived video quality heavily depends on parameters such as video coding and network Quality of Service. This paper proposes a model for the estimation of perceived video quality in video streaming and broadcasting services that combines the aforementioned parameters with other that depend mainly on the information contents of the video sequences. These fitting parameters are derived from the Spatial and Temporal Information contents of the sequences. This model does not require reference to the original video sequence so it can be used for online, real-time monitoring of perceived video quality in Video over IP services. Furthermore, this paper proposes a measurement workbench designed to acquire both training data for model fitting and test data for model validation. Preliminary results show good correlation between measured and predicted values.

Perceived Video Quality Estimation from Spatial and Temporal Information Contents and Network Performance Parameters in IPTV

The paper proposes a model for estimation of perceived video quality in IPTV, taking as input both video coding and network Quality of Service parameters. It includes some fitting parameters that depend mainly on the information contents of the video sequences. A method to derive them from the Spatial and Temporal Information contents of the sequences is proposed. The model may be used for near real-time monitoring of IPTV video quality.

A novel monetary incentive for commercial P2P streaming

Today P2P faces two important challenges: design of mechanisms to encourage users’ collaboration in multimedia live streaming services; design of reliable algorithms with QoS provision, to encourage multimedia providers employ the P2P topology in commercial streaming services. We believe that these two challenges are tightly-related and there is much to be done with respect. This paper proposes a novel monetary incentive for P2P multimedia streaming. The incentive model classifies the users in groups according to the perceived video quality. We apply the model to a streaming system’s billing model in order to evaluate its feasibility and visualize its quantitative effect on the users’ motivation and the provider’s profit. We conclude that monetary incentive can boost up users’ cooperation, loyalty and enhance the overall system integrity and performance. Moreover the model defines the constraints for the provider’s cost and profit when the system is leveraged on the cloud. Considering those constraints, a multimedia content provider can adapt the billing model of his streaming service and achieve desirable discount-profit trade-off. This will moreover contribute to better promotion of the service, across the users on the Internet.

The relationship between young people's transit use and their perceptions of equity concepts in transit service provision

This study investigates the effect of price and travel mode fairness and spatial equity in transit provision on the perceived transit service quality, willingness to pay, and habitual frequency of use. Based on the theory of planned behavior, we developed a web-based questionnaire for revealed preferences data collection. The survey was administered among young people in Copenhagen and Lisbon to explore the transit perceptions and use under different economic and transit provision conditions. The survey yielded 499 questionnaires, analyzed by means of structural equation models. Results show that higher perceived fairness relates positively to higher perceived quality of transit service and higher perceived ease of paying for transit use. Higher perceived spatial equity in service provision is associated with higher perceived service quality. Higher perceived service quality relates to higher perceived ease of payment, which links to higher frequency of transit use.

Transit Use by Young People in Times of Financial Austerity: A Cause of Equity Concern?

This study investigates the effect of price and travel time fairness and spatial equity in transit provision on the perceived transit service quality, willingness to pay, and habitual frequency of use. Based on the theory of planned behavior, we developed a web-based questionnaire for revealed preferences data collection. The survey was administered among young people in Copenhagen and Lisbon to explore the transit perceptions and use under different economic and transit provision conditions. The survey yielded 499 questionnaires, analyzed by means of structural equation models. Results show that higher perceived fairness relates positively to higher perceived quality of transit service and higher perceived ease of paying for transit use. Higher perceived spatial equity in service provision is associated with higher perceived service quality. Higher perceived service quality relates to higher perceived ease of payment, which links to higher frequency of transit use.

Modelo multivariante de evolución en el tiempo de la calidad percibida en la educación superior

Las instituciones de educación superior deben gestionar eficaz y eficientemente sus procesos de captación de nuevos estudiantes, y con este objetivo necesitan mejorar su comprensión sobre los antecedentes que inciden en la intención de recomendarlas. Por lo que esta Tesis Doctoral se centra en el estudio y análisis de las componentes de la calidad del servicio de la educación superior, como antecedentes de la intención de recomendación de una institución universitaria. El enfoque que se adopta en esta investigación integra las dimensiones de calidad docente y de calidad de servicio e incorpora en el análisis la valoración global de la carrera. Paralelamente se contempla la moderación de la experiencia y el desempeño académico del estudiante. En esta Tesis Doctoral se hace uso de la Encuesta de Calidad de la Universidad ORT Uruguay cedida a los autores para su explotación con fines de investigación. Los estudiantes cumplimentan la encuesta semestralmente con carácter obligatorio en una plataforma en línea autoadministrada, que permite identificar las valoraciones realizadas por los estudiantes a lo largo de su paso por la universidad. Por lo que la base de datos es un panel no balanceado que consta de 195.058 registros obtenidos, a partir de 7.077 estudiantes en 17 semestres (marzo de 2003 a 2011). La metodología se concreta en los Modelos de Ecuaciones Estructurales, que proporciona una serie de ventajas con respecto a otras aproximaciones. Una de las más importantes es que permite al investigador introducir información a priori y valorar su inclusión, además de reformular las modelizaciones propuestas desde una perspectiva multi-muestra. En esta investigación se estiman los modelos con MPLUS 7. Entre las principales conclusiones de esta Tesis Doctoral cabe señalar que las percepciones de calidad, servicio, docencia y carrera, inciden positivamente en la intención de recomendar la universidad, y que la variable experiencia del estudiante modera dichas relaciones. Los resultados señalan, en general, que a medida que los estudiantes avanzan en su carrera, los efectos totales de la percepción de la calidad del servicio en la calidad global de la carrera y en la intención de recomendar la universidad son mayores que los efectos que tiene la percepción de calidad de la docencia. Estos hallazgos señalan la necesidad que tienen estas instituciones de educación superior de incorporar en su planificación estratégica la segmentación de los estudiantes según su experiencia. ABSTRACT For institutions of higher education to effectively and efficiently manage their processes for attracting new students, they need to understand the influences that activate student intentions to recommend a program and/or college. This Thesis describes research identifying the quality components of a university that serve as antecedents of student intentions to recommend. The research design integrates teaching and service dimensions of higher education, as well as measures of student perceptions of the overall quality of a program. And introduces the student quality and student experience during the program as moderators of these relationships. This Thesis makes use of the Quality Survey of the Universidad ORT Uruguay ceded to the authors for their exploitation for research purposes. The students complete the survey each semester in a self-administered online platform, which allows to identify the assessments conducted by the students throughout its passage by the university. So that the database is an unbalanced panel consisting of 195.058 records obtained from 7.077 students in 17 semesters (march 2003 to 2011). The methodology of analysis incorporated Simultaneous Equation Models, which provides a number of advantages with respect to other approaches. One of the most important is that it allows the researcher to introduce a priori information and assess its inclusion, in addition to reformulate the modellings proposals with a multi-sample approach. In this research the models are estimated with MPLUS 7. Based on the findings, student perceptions of quality, service, teaching and program, impact positively the intent to recommend the university, but the student’s experience during the program moderates these relationships. Overall, the results indicate that as students advance in the program, the full effects of the perception of service quality in the overall quality of the program and in the intention to recommend the university, outweigh the effects of the perceived teaching quality. The results indicate the need for institutions of higher education to incorporate in its strategic planning the segmentation of the students according to their experience during the program.

Estimation of Perceived Quality in Convergent Services

Triple-Play (3P) and Quadruple-Play (4P) services are being widely offered by telecommunication services providers. Such services must be able to offer equal or higher quality levels than those obtained with traditional systems, especially for the most demanding services such as broadcast IPTV. This paper presents a matrix-based model, defined in terms of service components, user perceptions, agent capabilities, performance indicators and evaluation functions, which allows to estimate the overall quality of a set of convergent services, as perceived by the users, from a set of performance and/or Quality of Service (QoS) parameters of the convergent IP transport network

Social Housing in Great Metropolitan Areas: A New Methodology for Integrated Quality Evaluation and Comparison.

Este artículo expone la primera aplicación experimental de un método para el análisis y la comparación de experiencias de vivienda social internacional en el contexto de las grandes áreas metropolitanas. El método, desarrollado en la Universidad Politécnica Universidad Politécnica de Madrid (UPM) desde 2009, se basa en la utilización de códigos gráficos y numéricos comunes y la integración de diferentes escalas de aproximación al entorno construido, de la vivienda y su arquitectura, a sus materiales de construcción y llegando más lejos, la ciudad. Además, los datos están vinculados a tres conceptos clave estrechamente relacionados con las condiciones específicas de las grandes áreas metropolitanas: la economía, la densidad y la diversidad. El objetivo final de la investigación es proporcionar una herramienta para la evaluación de la calidad de las viviendas sociales, optimización de recursos y un diseño innovador.

Urban transport interchanges: Importance-Performance analysis for evaluating perceived quality

As the world becomes more urbanised, public transport in cities must seek to provide viable alternatives to individual car transport. At an urban level, interchanges in public transport networks provide easy transfers between and within different transport modes and facilitate seamless travel. This study proposes a methodological framework with which to identify the factors that travellers view as key elements of an urban transport interchange. An attitudinal survey was undertaken in order to collect information about users? needs and perceptions in the Moncloa interchange in Madrid, Spain. The results obtained from an Importance-Performance Analysis (IPA) show that aspects related to the signposting of different facilities and transport services, the internal design of the interchange and the surrounding area, and safety and security are the greatest strengths of the interchange.

Analysis, monitoring, and management of quality of experience in video delivery services over IP

Esta tesis estudia la monitorización y gestión de la Calidad de Experiencia (QoE) en los servicios de distribución de vídeo sobre IP. Aborda el problema de cómo prevenir, detectar, medir y reaccionar a las degradaciones de la QoE desde la perspectiva de un proveedor de servicios: la solución debe ser escalable para una red IP extensa que entregue flujos individuales a miles de usuarios simultáneamente. La solución de monitorización propuesta se ha denominado QuEM(Qualitative Experience Monitoring, o Monitorización Cualitativa de la Experiencia). Se basa en la detección de las degradaciones de la calidad de servicio de red (pérdidas de paquetes, disminuciones abruptas del ancho de banda...) e inferir de cada una una descripción cualitativa de su efecto en la Calidad de Experiencia percibida (silencios, defectos en el vídeo...). Este análisis se apoya en la información de transporte y de la capa de abstracción de red de los flujos codificados, y permite caracterizar los defectos más relevantes que se observan en este tipo de servicios: congelaciones, efecto de “cuadros”, silencios, pérdida de calidad del vídeo, retardos e interrupciones en el servicio. Los resultados se han validado mediante pruebas de calidad subjetiva. La metodología usada en esas pruebas se ha desarrollado a su vez para imitar lo más posible las condiciones de visualización de un usuario de este tipo de servicios: los defectos que se evalúan se introducen de forma aleatoria en medio de una secuencia de vídeo continua. Se han propuesto también algunas aplicaciones basadas en la solución de monitorización: un sistema de protección desigual frente a errores que ofrece más protección a las partes del vídeo más sensibles a pérdidas, una solución para minimizar el impacto de la interrupción de la descarga de segmentos de Streaming Adaptativo sobre HTTP, y un sistema de cifrado selectivo que encripta únicamente las partes del vídeo más sensibles. También se ha presentado una solución de cambio rápido de canal, así como el análisis de la aplicabilidad de los resultados anteriores a un escenario de vídeo en 3D. ABSTRACT This thesis proposes a comprehensive approach to the monitoring and management of Quality of Experience (QoE) in multimedia delivery services over IP. It addresses the problem of preventing, detecting, measuring, and reacting to QoE degradations, under the constraints of a service provider: the solution must scale for a wide IP network delivering individual media streams to thousands of users. The solution proposed for the monitoring is called QuEM (Qualitative Experience Monitoring). It is based on the detection of degradations in the network Quality of Service (packet losses, bandwidth drops...) and the mapping of each degradation event to a qualitative description of its effect in the perceived Quality of Experience (audio mutes, video artifacts...). This mapping is based on the analysis of the transport and Network Abstraction Layer information of the coded stream, and allows a good characterization of the most relevant defects that exist in this kind of services: screen freezing, macroblocking, audio mutes, video quality drops, delay issues, and service outages. The results have been validated by subjective quality assessment tests. The methodology used for those test has also been designed to mimic as much as possible the conditions of a real user of those services: the impairments to evaluate are introduced randomly in the middle of a continuous video stream. Based on the monitoring solution, several applications have been proposed as well: an unequal error protection system which provides higher protection to the parts of the stream which are more critical for the QoE, a solution which applies the same principles to minimize the impact of incomplete segment downloads in HTTP Adaptive Streaming, and a selective scrambling algorithm which ciphers only the most sensitive parts of the media stream. A fast channel change application is also presented, as well as a discussion about how to apply the previous results and concepts in a 3D video scenario.

Quality assurance systems in the production and marketing of fresh peaches.

Due to the fast rate of peach post-harvest ripening, damage due to mechanical handling, externally appreciated as bruises and soft areas, is a real problem that leads to an early harvesting and poor quality of the fruits, as perceived by the consumers. More and more, the European consumer asks for good taste and freshness of fruits and vegetables, and these quality factors are not included in standards, nor in most of the producers' practices. Fruit processing and marketing centres (co-operatives) are increasingly interested in adopting quality controls in their processes. ISO 9000 procedures are being applied in some food areas, primarily milk and meat processors, but no generalised procedures have been developed until the present time to be applied to fresh product processes. All different peach and nectarine varieties that are harvested and handled in Murcia cooperatives and sold in a large supermarket in Madrid were analysed during the whole 1997 season (early May to late August). A total number of 78 samples of 25 fruits (co-operative) or 10 fruits (market), were tested in the laboratory for mechanical, optical, chemical and tasting quality. The variability and relationships between all these quality parameters are presented and discussed, and sampling unit sizes which would be advisable for quality control are calculated.

Key quality factors and travellers profiles at interurban interchanges

La planificación y las políticas de transporte no pueden descuidar la calidad del servicio, considerando que influye notablemente en el cambio modal del coche hacia otros medios de transporte más sostenibles. El concepto se aplica también a los intercambiadores de transporte público, los nodos del sistema donde se cruzan las distintas redes del transporte público y privado. Aunque se han logrado numerosos avances para medir y evaluar la calidad en el sector del transporte público, se han dedicado relativamente pocos esfuerzos a investigar estos aspectos relacionados con la calidad de los intercambiadores del transporte público. Este trabajo de investigación se concentra en la calidad del servicio de la transferencia modal en los intercambiadores interurbanos, según la perspectiva de los viajeros. Su objetivo es identificar los factores clave de la calidad del servicio y los perfiles de los viajeros en los intercambiadores. La investigación es exploratoria y ofrece información acerca de la percepción de los viajeros intermodales relacionada con los aspectos de la calidad, aportando nuevos elementos y datos para adentrarse en estudios más detallados. La metodología del trabajo combina técnicas de análisis estadístico multivariante para analizar los datos de las encuestas sobre la satisfacción de los clientes y se subdivide en tres etapas. En primer lugar, se ha implementado el análisis de correspondencias múltiples para explorar los constructos latentes relacionados con la satisfacción de las características cualitativas de los intercambiadores interurbanos, identificando así los factores clave de la calidad. En segundo lugar, se ha aplicado un análisis de conglomerados de k-medias sobre los factores clave de calidad para clasificar a los viajeros en grupos de usuarios de transportes homogéneos, de acuerdo con su percepción de satisfacción, identificando de este modo los perfiles de los viajeros. Por último, se han formulado sugerencias y recomendaciones sobre la calidad para respaldar la formulación de políticas, estableciendo las prioridades para los intercambiadores interurbanos. La metodología se aplicó en cuatro intercambiadores interurbanos (estaciones de ferrocarriles o de autobuses ) en Madrid, Zaragoza, Gothenburg y Lion, analizando los datos recogidos mediante una encuesta de satisfacción del cliente llevada a cabo en 2011 en los cuatro casos de estudio, donde se interconectan distintos medios de transporte público y privado, de corta y larga distancia. Se recogieron datos sobre la satisfacción de los viajeros con 26 criterios de calidad, así como información sobre aspectos socio-económicos y pautas de comportamiento de viajes. Mediante el análisis de correspondencias múltiples se identificaron 4-5 factores clave de calidad en cada intercambiador, que se asocian principalmente con el sistema de emisión de billetes, el confort y la interconexión, mientras que los viajeros no perciben los temas clásicos como la información. Mediante el análisis de conglomerados se identificaron 2-5 perfiles de viajeros en cada intercambiador. Se reconocieron dos grupos de viajeros en casi todos los casos de estudio: viajeros de cercanía/trabajadores y turistas. Por lo que concierne a las prioridades para apoyar a las partes interesadas en la formulación de políticas, la expedición de billetes es el factor clave para los intercambiadores interurbanos españoles, mientras que la interconexión y los aspectos temporales se destacan en los intercambiadores de Francia y Suecia. Quality of Service can not be neglected in public transport planning and policy making, since it strongly influences modal shifts from car to more sustainable modes. This concept is also related to Public Transport interchanges, the nodes of the transport system where the different sub-systems of public passenger transport and personal vehicles meet. Although a lot of progress has been generally done to measure and assess quality in public transport sector, relatively little investigation has been conducted on quality at PT interchanges. This research work focusses on Quality of Service in the use of transfer facilities at interurban interchanges, according to current travellers’ perspective. It aims at identifying key quality factors and travellers profiles at interurban interchanges. The research is exploratory and offers insight into intermodal travellers’ perception on quality aspects, providing new elements and inputs for more definitive investigation. The methodology of the work combines multivariate statistical techniques to analyse data from customer satisfaction surveys and is subdivided in three steps. Firstly, multiple correspondence analysis was performed to explore latent constructs as concern satisfaction of quality attributes at interurban interchanges, thus identifying the so-called Key Quality Factor. Secondly, k-means cluster analysis was implemented on the key quality factors to classify travellers in homogeneous groups of transport users, according to their perception of satisfaction, thus identifying the so-called Travellers Profiles. Finally, hints and recommendations on quality were identified to support policy making, setting priorities for interurban interchanges. The methodology was applied at four interurban interchanges in Madrid, Zaragoza, Gothenburg and Lyon, analysing the data collected through a customer satisfaction survey carried out in 2011 at the four railway or bus stations where different modes of public and private transport are interconnected covering both short and long trips. Data on travellers’ satisfaction with 26 quality attributes were collected, as well as information on socio-economical and travel patterns. Through multiple correspondence analysis were identified 4-5 key quality factors per interchange. They are mainly related to ticketing, comfort and connectivity, while classical issues, as information, are not perceived as important by travellers’. Through cluster analysis were identified 2-5 travellers profiles per interchange. Two groups of travellers can be found in almost all case studies: commuter / business travellers and holiday travellers. As regards the priorities to support stakeholders in policy making, ticketing is the key-issue for the Spanish interurban interchanges, while connectivity and temporal issues emerge in the French and Swedish case studies.

Validation of a novel approach to subjective quality evaluation of conventional and 3D broadcasted video services

Transmission errors are the main cause of degradation of the quality of real broadcasted video services. Therefore, knowing their impact on the quality of experience of the end users is a crucial issue. For instance, it would help to improve the performance of the distribution systems, and to develop monitoring tools to automatically estimate the quality perceived by the end users. In this paper we validate a subjective evaluation approach specifically designed to obtain meaningful results of the effects of degradations caused by transmission errors. This methodology has been already used in our previous works with monoscopic and stereoscopic videos. The validation is done by comparing the subjective ratings obtained for typical transmission errors with the proposed methodology and with the standard method Absolute Category Rating. The results show that the proposed approach could provide more representative evaluations of the quality of experience perceived by end users of conventional and 3D broadcasted video services.

Key quality factors at urban interchanges.

Quality of service should not be overlooked in public transport planning and policy making, as it influences modal shift from car use to more sustainable means. Little research has been conducted on the quality of public transport interchanges from the perspective of current travellers (i.e. perceived quality). This work is thus aimed at identifying key quality factors in urban interchanges, through an exploratory approach (multiple correspondence analysis) that provides novel elements for further research. The methodology was applied at interchanges in Madrid and Gothenburg and the data used in the analysis were collected through customer satisfaction surveys conducted in 2011. The analysis identified five key quality factors per interchange. Ticketing plays a key role at both interchanges while physical and environmental issues emerged at Avenida de America in Madrid, and services, temporal issues and interconnectivity characterise Gothenburg central station. Compared with other quality aspects, classical issues such as safety/security and information are not perceived as important by intermodal travellers.

Normalizar la utopía: Un proyecto de sistematización de la normativa en vivienda social = Normalizing Utopia: A Project of Systematization of Regulations on Social Housing

La presente tesis doctoral aborda el estudio del proyecto de vivienda colectiva social desde la noción de norma, entendida desde la sistematización o normalización de los instrumentos del proyecto arquitectónico de vivienda protegida. Esto es, desde una idea de tipificación taxonómica en cuanto ajuste a un conjunto de reglas comunes productoras de sistemas normativos. La hipótesis de partida se basa en la consideración de la vivienda pública como un laboratorio de estudio histórico de los ideales de confort y calidad de vida. Este campo de pruebas ha constituido una sólida base que ha servido como punto de encuentro muy particular entre proyecto y normativa desde las primeras vanguardias europeas hasta la actualidad. El principal objetivo de la investigación es la revalorización de una normativa de vivienda que ha producido ejemplos de innegable calidad en el contexto nacional e internacional, así como un intento de actualización de su codificación. La investigación se sirve de los instrumentos específicos de la disciplina arquitectónica para explicar una disociación detectada desde la segunda mitad del siglo pasado entre la utopía del proyecto social de vivienda y el pragmatismo de la norma que lo regula, más allá de los aspectos sociales y culturales asociados a las nuevas composiciones familiares, las tecnologías cambiantes, los ritos domésticos contemporáneos o el valor creciente del tiempo libre. La propuesta de una nueva terminología que aborde nuevas relaciones en el acercamiento al proyecto de vivienda desde la normativa española deriva en un conjunto de estrategias de proyecto desde las que proponer sistemas normativos. Dichas estrategias se basan principalmente en mecanismos de cualificación espacial que permitan un nuevo acercamiento entre dichas normas y las formas de habitar actuales. ABSTRACT This doctoral thesis deals with the study of the project of social collective housing from the notion of rule, understanding it from the systematization or standardization of the instruments of architectural project for social housing. Thus, it deals with an idea of taxonomic typification as an adjustment to a set of common rules which produce regulation systems. The initial hypothesis is based on the consideration of public housing as a laboratory for studying the historical ideals of comfort and quality of life. This testing ground has been a solid base that has served as a very specific meeting point between project and regulations from the first European avant‐garde to nowadays. The main objective of this research is the revaluation of housing regulations, which have produced examples of undeniable quality in the national and international stage, as well as an attempt to update their codification. The research assumes the specific tools of the discipline of architecture for explaining a dissociation detected between the utopia of the project for social housing and the pragmatism of the regulations from the second half of last century, beyond social and cultural aspects associated to the new family arrangements, the changing technologies, the contemporary domestic rituals or the rising value of leisure time. The proposal of a new terminology that tackles new relations in the approach to housing project from the Spanish legislation results in a set of strategies to propose regulation systems. Those strategies are mainly based on mechanisms for spatial qualification which allow a new approach between these rules and the current ways of living.