Comparative analysis of meta-analysis methods: when to use which?

Background: Several meta-analysis methods can be used to quantitatively combine the results of a group of experiments, including the weighted mean difference, statistical vote counting, the parametric response ratio and the non-parametric response ratio. The software engineering community has focused on the weighted mean difference method. However, other meta-analysis methods have distinct strengths, such as being able to be used when variances are not reported. There are as yet no guidelines to indicate which method is best for use in each case. Aim: Compile a set of rules that SE researchers can use to ascertain which aggregation method is best for use in the synthesis phase of a systematic review. Method: Monte Carlo simulation varying the number of experiments in the meta analyses, the number of subjects that they include, their variance and effect size. We empirically calculated the reliability and statistical power in each case Results: WMD is generally reliable if the variance is low, whereas its power depends on the effect size and number of subjects per meta-analysis; the reliability of RR is generally unaffected by changes in variance, but it does require more subjects than WMD to be powerful; NPRR is the most reliable method, but it is not very powerful; SVC behaves well when the effect size is moderate, but is less reliable with other effect sizes. Detailed tables of results are annexed. Conclusions: Before undertaking statistical aggregation in software engineering, it is worthwhile checking whether there is any appreciable difference in the reliability and power of the methods. If there is, software engineers should select the method that optimizes both parameters.

On the practicality of global flow analysis of logic programs

This paper addresses the issue of the practicality of global flow analysis in logic program compilation, in terms of both speed and precision of analysis. It discusses design and implementation aspects of two practical abstract interpretation-based flow analysis systems: MA3, the MOO Andparallel Analyzer and Annotator; and Ms, an experimental mode inference system developed for SB-Prolog. The paper also provides performance data obtained from these implementations. Based on these results, it is concluded that the overhead of global flow analysis is not prohibitive, while the results of analysis can be quite precise and useful.

Data-Flow analysis of prolog programs with extra-logical features

Abstract interpretation-based data-flow analysis of logic programs is at this point relatively well understood from the point of view of general frameworks and abstract domains. On the other hand, comparatively little attention has been given to the problems which arise when analysis of a full, practical dialect of the Prolog language is attempted, and only few solutions to these problems have been proposed to date. Such problems relate to dealing correctly with all builtins, including meta-logical and extra-logical predicates, with dynamic predicates (where the program is modified during execution), and with the absence of certain program text during compilation. Existing proposals for dealing with such issues generally restrict in one way or another the classes of programs which can be analyzed if the information from analysis is to be used for program optimization. This paper attempts to fill this gap by considering a full dialect of Prolog, essentially following the recently proposed ISO standard, pointing out the problems that may arise in the analysis of such a dialect, and proposing a combination of known and novel solutions that together allow the correct analysis of arbitrary programs using the full power of the language.

Using quantitative descriptive analysis and temporal dominance of sensations analysis as complementary methods for profiling commercial blackcurrant squashes

Quantitative descriptive analysis (QDA) is used to describe the nature and the intensity of sensory properties from a single evaluation of a product, whereas temporal dominance of sensation (TDS) is primarily used to identify dominant sensory properties over time. Previous studies with TDS have focused on model systems, but this is the first study to use a sequential approach, i.e. QDA then TDS in measuring sensory properties of a commercial product category, using the same set of trained assessors (n = 11). The main objectives of this study were to: (1) investigate the benefits of using a sequential approach of QDA and TDS and (2) to explore the impact of the sample composition on taste and flavour perceptions in blackcurrant squashes. The present study has proposed an alternative way of determining the choice of attributes for TDS measurement based on data obtained from previous QDA studies, where available. Both methods indicated that the flavour profile was primarily influenced by the level of dilution and complexity of sample composition combined with blackcurrant juice content. In addition, artificial sweeteners were found to modify the quality of sweetness and could also contribute to bitter notes. Using QDA and TDS in tandem was shown to be more beneficial than each just on its own enabling a more complete sensory profile of the products.

A level set approach for the analysis of flow and compaction during resin infusion in composite materials

Fluid flow and fabric compaction during vacuum assisted resin infusion (VARI) of composite materials was simulated using a level set-based approach. Fluid infusion through the fiber preform was modeled using Darcy���s equations for the fluid flow through a porous media. The stress partition between the fluid and the fiber bed was included by means of Terzaghi���s effective stress theory. Tracking the fluid front during infusion was introduced by means of the level set method. The resulting partial differential equations for the fluid infusion and the evolution of flow front were discretized and solved approximately using the finite differences method with a uniform grid discretization of the spatial domain. The model results were validated against uniaxial VARI experiments through an [0]8 E-glass plain woven preform. The physical parameters of the model were also independently measured. The model results (in terms of the fabric thickness, pressure and fluid front evolution during filling) were in good agreement with the numerical simulations, showing the potential of the level set method to simulate resin infusion

Global analysis of constraint logic programs

This article presents and illustrates a practical approach to the dataow analysis of constraint logic programming languages using abstract interpretation. It is rst argued that from the framework point of view it suces to propose relatively simple extensions of traditional analysis methods which have already been proved useful and practical and for exist. This is shown by proposing a simple extension of Bruynooghes traditional framework which allows it to analyze constraint logic programs. Then and using this generalized framework two abstract domains and their required abstract functions are presented the rst abstract domain approximates deniteness information and the second one freeness. Finally an approach for cobining those domains is proposed The two domains and their combination have been implemented and used in the analysis of CLP and Prolog III applications. Results from this implementation showing its performance and accuracy are also presented

Global flow analysis as a practical compilation tool

This paper addresses the issue of the practicality of global flow analysis in logic program compilation, in terms of speed of the analysis, precisi��n, and usefulness of the information obtained. To this end, design and implementation aspects are discussed for two practical abstract interpretation-based flow analysis systems: MA , the MCC And-parallel Analyzer and Annotator; and Ms, an experimental mode inference system developed for SB-Prolog. The paper also provides performance data obtained (rom these implementations and, as an example of an application, a study of the usefulness of the mode information obtained in reducing run-time checks in independent and-parallelism.Based on the results obtained, it is concluded that the overhead of global flow analysis is not prohibitive, while the results of analysis can be quite precise and useful.

Effectiveness of global analysis in strict independence-based automatic program parallelization

This paper presents a study of the effectiveness of global analysis in the parallelization of logic programs using strict independence. A number of well-known approximation domains are selected and tlieir usefulness for the application in hand is explained. Also, methods for using the information provided by such domains to improve parallelization are proposed. Local and global analyses are built using these domains and such analyses are embedded in a complete parallelizing compiler. Then, the performance of the domains (and the system in general) is assessed for this application through a number of experiments. We arg��e that the results offer significant insight into the characteristics of these domains, the demands of the application, and the tradeoffs involved.

A practical approach to the global analysis of CLP programs

This paper presents and illustrates with an example a practical approach to the dataflow analysis of programs written in constraint logic programming (CLP) languages using abstract interpretation. It is first argued that, from the framework point of view, it sufnces to propose relatively simple extensions of traditional analysis methods which have already been proved useful and practical and for which efncient fixpoint algorithms have been developed. This is shown by proposing a simple but quite general extensi��n of Bruynooghe's traditional framework to the analysis of CLP programs. In this extensi��n constraints are viewed not as "suspended goals" but rather as new information in the store, following the traditional view of CLP. Using this approach, and as an example of its use, a complete, constraint system independent, abstract analysis is presented for approximating definiteness information. The analysis is in fact of quite general applicability. It has been implemented and used in the analysis of CLP(R) and Prolog-III applications. Results from the implementation of this analysis are also presented.

Estudio de las formas de aplicaci��n de la fotograf��a sobre los materiales p��treos para la arquitectura = Study of photography application methods over architectural stony materials

Desde que el Hombre era morador de las cavernas ha sido manifiesto su deseo innato por grabar y reproducir "instant��neas con las que perpetuarse o sobre las que mirarse ". La aparici��n y desarrollo de la fotograf��a como medio para poder captar y fijar "la imagen directa de la realidad circundante " pronto se convierte en un nuevo lenguaje est��tico y po��tico que permite al artista la interpretaci��n y reflexi��n de lo observado. Se imprime a la imagen el car��cter de la mirada del fot��grafo, estableciendo un di��logo conceptual con el juego de luces. La presente Tesis plantea la creaci��n de una nueva piel de arquitectura mediante la impresi��n fotogr��fica sobre materiales p��treos. La b��squeda de la expresividad de los materiales como soporte de expresi��n art��stica implica un cambio de escala al trasladar la instant��nea fotogr��fica a la arquitectura y la aplicaci��n de un nuevo soporte al imprimir la fotograf��a sobre materiales arquitect��nicos. Se justifica la elecci��n del dispositivo l��ser CO2 como sistema de impresi��n fotogr��fica sobre los materiales p��treos arquitect��nicos, como la t��cnica que permite la uni��n f��sica de la imagen y el proyecto arquitect��nico, generando un valor a��adido a trav��s del arte de la fotograf��a. Se justifica la elecci��n de los materiales investigados, Silestone�� Blanco Zeus y GRC�� con TX Active�� Aria, de forma que la investigaci��n de esta nueva piel de arquitectura abarca tanto la envolvente del edificio como su volumen interior, permitiendo cerrar el c��rculo arquitect��nico "in&out" y dota al proyecto arquitect��nico de un valor a��adido al introducir conceptos sostenibles de car��cter est��tico y medioambiental. Se realiza una consulta a las empresas del sector arquitect��nico relacionadas directamente con la producci��n y distribuci��n de los materiales Silestone�� y GRC��, as�� como a las empresas especializadas en sistemas de impresi��n fotogr��fica sobre materiales, acerca del estado del arte. Se recorre la Historia de la fotograf��a desde sus or��genes hasta el desarrollo de la era digital y se analiza su condici��n art��stica. Se recopilan los sistemas de impresi��n fotogr��fica que han evolucionado en paralelo con los dispositivos de captura de la instant��nea fotogr��fica y se describe en profundidad el sistema de impresi��n fotogr��fica mediante dispositivo l��ser CO2. Se describen los procesos de fabricaci��n, las caracter��sticas t��cnicas, cualidades y aplicaciones de los materiales p��treos arquitect��nicos Silestone�� Blanco Zeus y GRC�� con TX Active�� Aria. Se explica la t��cnica utilizada para la captaci��n de la imagen fotogr��fica, su justificaci��n art��stica y su proceso de impresi��n mediante dispositivo l��ser CO2 bajo diferentes par��metros sobre muestras de los materiales arquitect��nicos investigados. Se comprueba la viabilidad de desarrollo de la nueva piel de arquitectura sobre Silestone�� Blanco Zeus y GRC�� con TX Active�� Aria sometiendo a las piezas impresas bajo diferentes par��metros a tres ensayos de laboratorio. En cada uno de ellos se concreta el objetivo y procedimiento del ensayo, la enumeraci��n de las muestras ensayadas y los par��metros bajo los que han sido impresas, el an��lisis de los resultados del ensayo y las conclusiones del ensayo. Ensayo de amplitud t��rmica. Se determina el grado de afectaci��n de las im��genes impresas bajo la acci��n de contrastes t��rmicos. Series de muestras de Silestone�� Blanco Zeus y GRC�� con TX Active�� Aria impresas con l��ser CO2 se someten a ciclos de contraste fr��o-calor de 12 horas de duraci��n para una amplitud t��rmica total de 102��C. Se realiza una toma sistem��tica de fotograf��as microsc��picas con lupa de aumento de cada pieza antes y despu��s de los ciclos fr��o-calor y la observaci��n de las transformaciones que experimentan los materiales bajo la acci��n del l��ser CO2. Ensayo de exposici��n a la acci��n de la radiaci��n ultravioleta (UV). Se determina el grado de afectaci��n de las im��genes impresas al activar la capacidad autolimpiante de part��culas org��nicas. Una serie de muestras de GRC�� con TX Active�� Aria impresa con l��ser CO2 se someten a ciclos de exposici��n de radiaci��n ultravioleta de 26 horas de duraci��n. Se somete la serie a un procedimiento de activaci��n del aditivo TX Active��. Se simula la contaminaci��n org��nica mediante la aplicaci��n controlada de Rodamina B, tinte org��nico, y se simula la radiaci��n UV mediante el empleo de una bombilla de emisi��n de rayos ultravioleta. Se realiza una toma sistem��tica de fotograf��as macrosc��picas de la serie de muestras ensayadas: antes de aplicaci��n de la Rodamina B, momento 00:00h, momento 04:00h y momento 26:00h del ensayo. Se procede a la descarga y an��lisis del histograma de las fotograf��as como registro de la actividad fotocatal��tica. Ensayo de la capacidad autodescontaminante del GRC�� con TX Active�� impreso con l��ser CO2. Se comprueba si la capacidad autodescontaminante del GRC�� con TX Active�� se ve alterada como consecuencia de la impresi��n de la imagen fotogr��fica impresa con l��ser CO2. Serie de muestras de GRC�� con TX Active�� Aria impresa con l��ser CO2 se someten a test de capacidad autodescontaminante: atm��sfera controlada y contaminada con ��xidos de nitr��geno en los que se coloca cada pieza ensayada bajo la acci��n de una l��mpara de emisi��n de radiaci��n ultravioleta (UV). Se registra la actividad fotocatal��tica en base a la variaci��n de concentraci��n de ��xido de nitr��geno. Se recopila el an��lisis e interpretaci��n de los resultados de los ensayos de laboratorio y se elaboran las conclusiones generales de la investigaci��n. Se sintetizan las futuras l��neas de investigaci��n que, a partir de las investigaciones realizadas y de sus conclusiones generales, podr��an desarrollarse en el ��mbito de la impresi��n fotogr��fica sobre materiales arquitect��nicos. Se describe el rendimiento tecnol��gico y art��stico generado por las investigaciones previas que han dado origen y desarrollo a la Tesis Doctoral. ABSTRACT Since ancient time, humanity has been driven by an innate wish to reproduce and engrave "snapshots that could help to perpet��ate or to look at one self". Photography's birth and its development as a mean to capture and fix "the direct image of the surrounding reality" quickly becomes a new aesthetical and poetical language allowing the artist to interpret and think over what has been observed. The photographer's eye is imprinted onto the image, and so the conceptual dialogue between the artist and the light beams begins. The current thesis suggests the creation of a new architectural skin through photography imprinting over stony materials. The search for material's expressiveness as a medium of artistic expression involves a change of scale as it transfers photographic snapshot into architecture and the use of a new photographic printing support over architectural materials. CO2 laser is the chosen printing system for this technique as it allows the physical union of the image and the architectonic project, generating an added value through the art of photography. The researched materials selected were Silestone��, Blanco Zeus and GRC�� with TX Active�� Aria. This new architectural skin contains the building surrounding as well as its interior volume, closing the architectonic "in & out" circle and adding a value to the project by introducing aesthetical and environmental sustainable concepts. Architecture companies related to the production and distribution of materials like Silestone�� and GRC��, as well as companies specialized in photography printing over materials were consulted to obtain a State of the Art. A thorough analysis of photography's History from its origins to the digital era development was made and its artistic condition was studied in this thesis. In this study the author also makes a compilation of several photographic printing systems that evolved together with photographic snapshot devices. The CO2 laser-based photographic printing system is also described in depth. Regarding stony materials of architecture like Silestone��, Blanco Zeus and GRC�� with TX Active�� Aria, the present study also describes their manufacture processes as well as technical features, quality and application. There is also an explanation about the technique to capture the photographic image, its artistic justification and its CO2 laser-based printing system over the researched materials under different parameters. We also tested the feasibility of this new architectural skin over Silestone�� Blanco Zeus and GRC�� with TX Active�� Aria. The pieces were tested under different parameters in three laboratory trials. Each trial comprises of an explanation of its objective and its process, the samples were numbered and the printing parameters were specified. Finally, with the analysis of the results some conclusions were drawn. In the thermal amplitude trial we tried to determine how printed images were affected as a result of the action of thermal contrasts. Series of samples of Silestone�� Blanco Zeus and GRC�� with TX Active�� Aria printed with CO2 laser were subjected to several 12h warm-cold cycles for thermal total amplitude of 102oc. Each sample was captured systematically with microscopic enhanced lenses before and after cold-warm cycles. The changes experienced by these materials under the effect of CO2 laser were observed and recorded. Trial regarding the Ultraviolet Radiation (UR) effect on images. We determined to which extent printed images were affected once the self-cleaning organic particles were activated. This time GRC�� with TX Active�� Aria samples printed with CO2 laser were exposed to a 26h UR cycle. The samples were subjected to the activation of TX Active�� additive. Through the controlled application of Rodamine B and organic dye we were able to simulate the organic contamination process. UR was simulated using an ultraviolet beam emission bulb. A systematic capture of macroscopic pictures of the tested sample series was performed at different time points: before Rodamine B application, at moment 00:00h, moment 04:00h and moment 26:00h of the trial. Picture's histogram was downloaded and analyzed as a log of photocatalytic activity. Trial regarding the self-decontaminating ability of GRC�� with TX Active�� printed with CO2 laser. We tested if this self-decontaminating ability is altered as a result of CO2 laser printed image. GRC�� with TX Active�� Aria samples printed with CO2 laser, were subject to self-decontaminating ability tests with controlled and nitrogen oxide contaminated atmosphere. Each piece was put under the action of an UR emission lamp. Photocatalytic activity was recorded according to the variation in nitrogen oxide concentration. The results of the trial and their interpretation as well as the general conclusions of the research are also compiled in the present study. Study conclusions enable to draw future research lines of potential applications of photographic printing over architecture materials. Previous research generated an artistic and technological outcome that led to the development of this doctoral thesis.

Application of noise analysis for sensor surveillance in Trillo NPP

It is a known fact that noise analysis is a suitable method for sensor performance surveillance. In particular, controlling the response time of a sensor is an efficient way to anticipate failures and to have the opportunity to prevent them. In this work the response times of several sensors of Trillo NPP are estimated by means of noise analysis. The procedure applied consists of modeling each sensor with autoregressive methods and getting the searched parameter by analyzing the response of the model when a ramp is simulated as the input signal. Core exit thermocouples and in core self-powered neutron detectors are the main sensors analyzed but other plant sensors are studied as well. Since several measurement campaigns have been carried out, it has been also possible to analyze the evolution of the estimated parameters during more than one fuel cycle. Some sensitivity studies for the sample frequency of the signals and its influence on the response time are also included. Calculations and analysis have been done in the frame of a collaboration agreement between Trillo NPP operator (CNAT) and the School of Mines of Madrid.

A Structure of Problem Solving Methods for Real Time Decision Support in Traffic Control

This article describes a knowledge-based application in the domain of road traffic management that we have developed following a knowledge modeling approach and the notion of problem-solving method. The article presents first a domain-independent model for real-time decision support as a structured collection of problem solving methods. Then, it is described how this general model is used to develop an operational version for the domain of traffic management. For this purpose, a particular knowledge modeling tool, called KSM (Knowledge Structure Manager), was applied. Finally, the article shows an application developed for a traffic network of the city of Madrid and it is compared with a second application developed for a different traffic area of the city of Barcelona.

Methodology of image analysis for study of the vertisols moisture content

The main problem to study vertical drainage from the moisture distribution, on a vertisol profile, is searching for suitable methods using these procedures. Our aim was to design a digital image processing methodology and its analysis to characterize the moisture content distribution of a vertisol profile. In this research, twelve soil pits were excavated on a ba re Mazic Pellic Vertisols ix of them in May 13/2011 and the rest in May 19 /2011 after a moderate rainfall event. Digital RGB images were taken from each vertisol pit using a Kodak? camera selecting a size of 1600x945 pixels. Each soil image was processed to homogenized brightness and then a spatial filter with several window sizes was applied to select the optimum one. The RGB image obtained were divided in each matrix color selecting the best thresholds for each one, maximum and minimum, to be applied and get a digital binary pattern. This one was analyzed by estimating two fractal scaling exponents box counting dimension D BC) and interface fractal dimension (D) In addition, three pre-fractal scaling coefficients were determinate at maximum resolution: total number of boxes intercepting the foreground pattern (A), fractal lacunarity (?1) and Shannon entropy S1). For all the images processed the spatial filter 9x9 was the optimum based on entropy, cluster and histogram criteria. Thresholds for each color were selected based on bimodal histograms.

Post-�����occupancy monitoring of two flats in Madrid: development and assessment of a mixed methods methodology

Recent research has shown large differences between the expected and the actual energy consumption in buildings. The differences have been attributed partially, to the assumptions made during the design phase of buildings when simulation methods are employed. More accurate occupancy profiles on building operation could help to carry out more precise building performance calculations. This study focuses on the post-occupancy evaluation of two apartments, one renovated and one non renovated, in Madrid within the same building complex. The aim of this paper is to present an application of the mixed-methods methodology (Creswell, 2007) to assess thermal comfort and occupancy practices used in the case studies, and to discuss the shortcomings and opportunities associated with it. The mixed-methods methodology offers strategies for integrating qualitative and quantitative methods to investigate complex phenomena. This approach is expected to contribute to the growing knowledge of occupants��� behaviour and building performance by explaining the differences observed between energy consumption and thermal comfort in relation to people���s saving and comfort practices and the related experiences, preferences and values.

Usability Planner: A Tool to Support the Process of Selecting Usability Methods

There is increasing pressure on developers to produce usable systems, which requires the use of appropriate methods to support user centred design during development. There is currently no consistent advice on which methods are appropriate in which circumstances, so the selection of methods relies on individual experience and expertise. Considerable effort is required to collate information from various sources and to understand the applicability of each method in a particular situation. Usability Planner is a tool aimed to support the selection of the most appropriate methods depending on project and organizational constraints. Many of the rules employed are derived from ISO standards, complemented with rules from the authors��� experience.