A Bibliography of Transonic Dynamics Tunnel (TDT) Publications

The Transonic Dynamics Tunnel (TDT) at the National Aeronautics and Space Administration's (NASA) Langley Research Center began research operations in early 1960. Since that time, over 600 tests have been conducted, primarily in the discipline of aeroelasticity. This paper presents a bibliography of the publications that contain data from these tests along with other reports that describe the facility, its capabilities, testing techniques, and associated research equipment. The bibliography is divided by subject matter into a number of categories. An index by author's last name is provided

Development and Validation of Characterization Method Using Finite Element Numerical Modeling and Advance Laboratory Methods for Western Australia Asphalt Mixes

A quantitative understanding of materials characterization of asphalt mixtures is required to determine the appropriate asphalt mixtures so that pavement distress and deformation can be reduced. Various numerical modeling and laboratory tools are used to assess the asphalt mixtures of flexible pavement and provided a significant and novel contribution to understanding of characterization of asphalt mixtures and design of flexible pavement. The contribution to understanding from this thesis shall be integrated in future body of knowledge

Explanation of the Model Checker Verification Results

Immer wenn neue Anforderungen an ein System gestellt werden, müssen die Korrektheit und Konsistenz der Systemspezifikation überprüft werden, was in der Praxis in der Regel manuell erfolgt. Eine mögliche Option, um die Nachteile dieser manuellen Analyse zu überwinden, ist das sogenannte Contract-Based Design. Dieser Entwurfsansatz kann den Verifikationsprozess zur Überprüfung, ob die Anforderungen auf oberster Ebene konsistent verfeinert wurden, automatisieren. Die Verifikation kann somit iterativ durchgeführt werden, um die Korrektheit und Konsistenz des Systems angesichts jeglicher Änderung der Spezifikationen sicherzustellen. Allerdings ist es aufgrund der mangelnden Benutzerfreundlichkeit und der Schwierigkeiten bei der Interpretation von Verifizierungsergebnissen immer noch eine Herausforderung, formale Ansätze in der Industrie einzusetzen. Stellt beispielsweise der Model Checker bei der Verifikation eine Inkonsistenz fest, generiert er ein Gegenbeispiel (Counterexample) und weist gleichzeitig darauf hin, dass die gegebenen Eingabespezifikationen inkonsistent sind. Hier besteht die gewaltige Herausforderung darin, das generierte Gegenbeispiel zu verstehen, das oft sehr lang, kryptisch und komplex ist. Darüber hinaus liegt es in der Verantwortung der Ingenieurin bzw. des Ingenieurs, die inkonsistente Spezifikation in einer potenziell großen Menge von Spezifikationen zu identifizieren. Diese Arbeit schlägt einen Ansatz zur Erklärung von Gegenbeispielen (Counterexample Explanation Approach) vor, der die Verwendung von formalen Methoden vereinfacht und fördert, indem benutzerfreundliche Erklärungen der Verifikationsergebnisse der Ingenieurin bzw. dem Ingenieur präsentiert werden. Der Ansatz zur Erklärung von Gegenbeispielen wird mittels zweier Methoden evaluiert: (1) Evaluation anhand verschiedener Anwendungsbeispiele und (2) eine Benutzerstudie in Form eines One-Group Pretest-Posttest Experiments.Whenever new requirements are introduced for a system, the correctness and consistency of the system specification must be verified, which is often done manually in industrial settings. One viable option to traverse disadvantages of this manual analysis is to employ the contract-based design, which can automate the verification process to determine whether the refinements of top-level requirements are consistent. Thus, verification can be performed iteratively to ensure the system’s correctness and consistency in the face of any change in specifications. Having said that, it is still challenging to deploy formal approaches in industries due to their lack of usability and their difficulties in interpreting verification results. For instance, if the model checker identifies inconsistency during the verification, it generates a counterexample while also indicating that the given input specifications are inconsistent. Here, the formidable challenge is to comprehend the generated counterexample, which is often lengthy, cryptic, and complex. Furthermore, it is the engineer’s responsibility to identify the inconsistent specification among a potentially huge set of specifications. This PhD thesis proposes a counterexample explanation approach for formal methods that simplifies and encourages their use by presenting user-friendly explanations of the verification results. The proposed counterexample explanation approach identifies and explains relevant information from the verification result in what seems like a natural language statement. The counterexample explanation approach extracts relevant information by identifying inconsistent specifications from among the set of specifications, as well as erroneous states and variables from the counterexample. The counterexample explanation approach is evaluated using two methods: (1) evaluation with different application examples, and (2) a user-study known as one-group pretest and posttest experiment

A Navigational Role-Centric Model Oriented Web Approach MoWebA

[ES] Entre los grandes desafíos actuales de las aplicaciones Web podemos citar la portabilidad, adaptabilidad y evolución. Estos desafíos se dan tanto en el ambiente en que operan así como en su desarrollo, ya que a menudo requieren de diferentes lenguajes, frameworks, herramientas, entornos, plataformas, etc. El Desarrollo Dirigido por Modelos (MDD) y en particular, la Arquitectura Dirigida por Modelos (MDA) contemplan estos desafíos proponiendo distintos niveles de abstracción para las diferentes fases de modelado, partiendo de modelos más orientados al problema, que no deberían contemplar aspectos de implementación (CIM, PIM), hasta llegar a los modelos más orientados a la solución planteada (PSM, ISM). Sin embargo, encarar adecuadamente este tema puede depender del grado de independencia que adquieren los modelos. Este trabajo de Tesis presenta un método que considera el problema de la evolución y portabilidad hacia diferentes entornos o arquitecturas en el diseño y desarrollo de aplicaciones Web. La propuesta se denomina MoWebA (del inglés, Model Oriented Web Approach). Durante el desarrollo de la tesis, hemos identificado una serie de aspectos que podrían tener un impacto positivo sobre los problemas de portabilidad y adaptabilidad que son: i) incorporación de un modelo específico de la arquitectura ASM (del inglés, Architecture Specific Model), que permita la portabilidad de los PIMs con respecto a la arquitectura (por ejemplo, RIA, SOA, Mobile); ii) clara separación de la capa de presentación con respecto a las capas navegacionales y de comportamiento; iii) definición de la estructura navegacional de acuerdo a un mecanismo orientado al comportamiento, que prevenga la modificación del diseño navegacional causada por cambios en la implementación; iv) uso de estándares para facilitar la independencia de las herramientas. Se ha llevado a cabo una revisión del estado de la literatura teniendo en cuenta los fundamentos de la Ingeniería Dirigida por Modelos MDE (Model Driven Engineering), las propuestas metodológicas para el desarrollo de Aplicaciones Web, las tendencias actuales, analizando en forma especial de qué manera las propuestas Web las contemplan, y las evidencias empíricas tanto en la academia como en la Industria. Presentamos así la propuesta MoWebA a partir de una serie de consideraciones sobre las aplicaciones Web que han sido identificadas durante el proceso de revisión del estado del arte. Posteriormente, detallamos cada una de las etapas del proceso de modelado, incluyendo los diagramas y notaciones propuestos, sus definiciones a través de sus metamodelos y ejemplos de uso. Seguidamente, presentamos el proceso de transformación adoptado por MoWebA, con los mecanismos de transformación Modelo-A-Modelo y Modelo-A-Código. Hemos dedicado un importante esfuerzo en la validación de la propuesta. Se realizó una primera validación, adoptando los modelos de MoWebA y en algunos casos generando aplicaciones para diferentes dominios. Con estas primeras experiencias de validación hemos podido identificar fortalezas y debilidades de la propuesta PIM de MoWebA, además de determinar en qué grado la misma cubre las necesidades de diferentes dominios. Como segunda experiencia, hemos realizado una validación preliminar con un grupo de estudiantes de último año de la carrera de Ingeniería Informática de la Universidad Católica "Nuestra Señora de la Asunción" (Paraguay), que consistió en la definición de ASM para tres arquitecturas diferentes. Finalmente, como tercera experiencia de validación, hemos llevado a cabo un Caso de Estudio que consistió en la definición de tres extensiones para MoWebA. Dicha validación fue desarrollada como parte de un proyecto de investigación liderado por la Universidad Católica "Nuestra Señora de la Asunción". La experiencia ha permitido analizar el grado de adaptabilidad de MoWebA y automatización en las transformacinoes PIM-ASM, así como el grado de independiencia del PIM.[CA] Entre els grans desafiaments actuals de les aplicacions Web podem citar la portabilitat, adaptabilitat i evolució. El Desenvolupament Dirigit per Models (MDD) contemple aquests desafiaments proposant diferents nivells d'abstracció per a les diferents fases de modelatge. No obstant això, encarar adequadament aquest tema pot dependre del grau d'independència que adquireixen els models. Aquest treball de Tesi presenta un mètode que considera el problema de l'evolució i la portabilitat, en diferents entorns o arquitectures, per al disseny i desenvolupament d'aplicacions Web. La proposta s'anomena MoWebA (Model Oriented Web Approach). Durant el desenvolupament de la tesi hem identificat una sèrie d'aspectes que podrien tenir un impacte positiu sobre els problemes de portabilitat i adaptabilitat. Aquestos són: i) la incorporació d'un model específic d'arquitectura ASM (Architecture Specific Model), que permet la portabilitat dels models PIM respecte a l'arquitectura (per exemple, RIA, SOA, Mobile); ii) la clara separació de la capa de presentació respecte a les capes navegacionals i de comportament; iii) la definició de l'estructura navegacional d'acord amb un mecanisme orientat al comportament, que restringisca la modificació del disseny navegacional causada per canvis en la implementació; i per últim, iv) l'ús d'estàndards per tal de facilitar la independència de les eines. S'ha realitzat una revisió de l'estat de la literatura considerant els fonaments de l'Enginyeria Dirigida per Models MDE (Model Driven Engineering), les propostes metodològiques per al desenvolupament d'Aplicacions Web, les tendències actuals (analitzant de forma especial la manera en que les propostes Web les consideren), i les evidències empíriques tant en l'acadèmia com en la Indústria. Presentem així la proposta MoWebA a partir d'una sèrie de consideracions sobre les aplicacions Web que són identificades durant el procés de revisió de l'estat de l'art. Posteriorment, detallem cadascuna de les etapes del procés de modelatge, incloent els diagrames i les notacions proposades, les seues definicions (a través dels seus metamodels), i alguns exemples d'ús. Seguidament, presentem el procés de transformació adoptat per MoWebA, emprant mecanismes de transformació Model-a-Model i Model-a-Codi. Hem dedicat un esforç considerable en la validació de la proposta. Es realitzà una primera validació adoptant els models de MoWebA, i en alguns casos es generaren aplicacions per a diferents dominis. Aquestes experiències van ser realitzades per modeladors amb poca experiència, així com també per modeladors i desenvolupadors experimentats. Les experiències van ser desenvolupades en ambients tant acadèmics com industrials. Amb aquestes primeres experiències de validació s'identificaren fortaleses i febleses de la proposta PIM de MoWebA. També permeteren determinar fins quin grau la proposta respon a les necessitats dels diferents dominis. Com a segona experiència es realitzà una validació preliminar amb un grup d'estudiants d'últim curs de la carrera d'Enginyeria Informàtica de la Universitat Catòlica "Nuestra Señora de la Asunción" (Paraguai), que va consistir en la definició del model d'arquitectura ASM per a tres arquitectures diferents. Amb aquesta segona experiència de validació s'aconseguí valorar com de factible és d'adaptar la proposta a altres arquitectures. Finalment, com a tercera experiència de validació, es dugué a terme un Cas d'Estudi que va consistir en la definició de tres extensions per a MoWebA. L'experiència permeté analitzar el grau d'adaptabilitat i d'automatització en les transformacions PIM-ASM que s'obté amb MoWebA, així com el grau de independència del PIM amb respecte als altres models. Durant aquesta validació, s'han realitzat a més experiències de satisfacció d'usuaris amb un grup de modeladors i desenvolupadors.[EN] Some of the major challenges facing Web applications today are those of portability, adaptability and evolution, not only in the environment in which they run, but also in the way in which they must be developed, often requiring different languages, frameworks, tools, environments, platforms, etc. MDD and MDA take into account these issues. However, to achieve portability, adaptability and evolution depends to some extent on the degree of independence that the models adopt. This Thesis presents a method that take into account the problem of evolution and portability towards different environments. The approach is called MoWebA (Model Oriented Web Approach). Some key aspects of MoWebA that could have a positive impact in the portability and adaptability are:i) incorporation of an Architecture Specific Model (ASM) as a new modeling layer, in order to keep the portability of the Platform Independent Model (PIM) regarding the different architectures (e.g., RIA, SOA, Mobile); ii) clear separation of the presentation layer with regard to the navigation and behavior layers; iii) definition of the navigational structure according to a function-oriented approach, which prevents the modification of the navigation design caused by implementation changes; iv) and use of standards in order to facilitate the independence from the tools. We justify MoWebA by highlighting a series of concerns for Web applications development. We present an overview of the method including the dimensions and the diagrams that we propose. Subsequently, we present each step in the modeling process, including the diagrams and notation, its definition (metamodels) and examples of use. Afterwards, we present the transformation process adopted by MoWebA, which includes model-to-model and model-to-code transformations. We have devoted special attention to the validation of the approach. As a first validation, MoWebA has been used for modelling and generating different types of applications by both novice and experienced modellers and developers. These experiences were done in academic and industrial contexts. The experiences have allowed to identify strengths and weaknesses of the PIM proposal, and to verify that the proposed notation covers the needs of different domains. Next, we present a preliminary validation of the ASM proposal, considering an experience of different ASM definitions made by a group of computer science students at the Catholic University "Nuestra Señora de la Asunción" (Paraguay). This preliminary validation has allowed us to determine how feasible is to adapt the proposal to other architectures. The analysis of the validation sought to answer the following questions: Can the same PIM model be used for different architectures?; Is it possible to specify clear limits between platform independent models (PIM) and architectural specific models (ASM)?; How does an architectural specific model facilitate the transformation rules definition?. Finally, we present a Case Study to validate the extensions of MoWebA to three different architectures. The experience was structured taking into account the framework of Runeson et al. This experience have allowed to carry out three complete extensions. In such extensions we could analysed the grade of adaptability of MoWebA and of automation PIM-ASM, as well as the grade of independence of the PIM metamodel. We have also conducted some user's satisfaction experiences with modelers and developers.González Toñánez, M. (2022). A Navigational Role-Centric Model Oriented Web Approach MoWebA [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181470TESI

Development of a Framework for Monitoring the Long-Term Performance of Perpetual Pavements

Perpetual pavements represent a significant investment to an owner who has committed to spending additional dollars at initial construction in order to benefit from potential long-term savings from the enhanced performance of this asset. This makes the monitoring of a perpetual pavement critical to ensure that this asset is optimally preserved and maintained in order to meet the expectations of service for the design life and potentially beyond. This Thesis research involved investigation of methods of completing the long-term monitoring of a perpetual asphalt pavement including the development of a testing protocol using a falling weight deflectometer (FWD) as well as a framework for the monitoring of long term perpetual pavement performance. The project site used for the research consisted of one perpetual pavement section (with rich bottom mix (RBM)) which was constructed and instrumented at the Capitol Paving Plant in Guelph, Ontario. It was constructed by a consortium that included the Ontario Ministry of Transportation (MTO), Ontario Hot Mix Producers Association (OHMPA), the University of Waterloo Centre for Pavement and Transportation Technology (CPATT), the Natural Science and Engineering Research Council of Canada (NSERC), Stantec Inc., and McAsphalt Industries Limited. An initial testing program was required to accurately locate the embedded sensors within the test section. This testing program was completed with an array of FWD testing completed within the test section followed by analysis of the response of the embedded sensors to the testing in order to determine their location. This initial testing was successful in determining the embedded sensor locations and the locations were marked in the field for use in future testing programs. The next step consisted of validation of the performance of the embedded sensors. This involved predicting the expected strains using mechanistic design software (Kenpave) followed by a comparison with the strains recorded with the embedded sensors on the site. A significant discrepancy was found between these results and supplemental testing was completed to attempt to isolate and mitigate the source of the variability. The in-situ resilient modulus values were backcalculated using and the FWD results which were adjusted in order to obtain design deflections similar to the deflections measured using the FWD. The resilient modulus of the asphalt concrete layer was adjusted for temperature and the expected strains recalculated using the mechanistic design software. While the results showed signs of converging, the known sources of variability had been evaluated and the remaining difference between the predicted and calculated strain values were considered to be due to a change in the calibration factor of the gauges. New calibration factors were calculated for the gauges and the new calibration factors applied to the sensors and checked using the FWD in order to validate the new calibration factors. The additional testing showed that the embedded sensors were now within the tolerance expected for the types of monitoring equipment used at the site and the new calibration factors were considered to be suitable. Finally, a framework was developed to provide guidance for the long-term monitoring of perpetual pavements using the knowledge and experience gained during the research

Aeronautical engineering: A continuing bibliography with indexes (supplement 301)

This bibliography lists 1291 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Sustainable pavement applications utilizing quarry by-products and recycled/nontraditional aggregate materials

Quarry By-products (QB), usually less than 0.25 in. (6 mm) in size, are the residual deposits from the production of required grades of aggregates and are often stockpiled in excess quantities at the quarries. More than 175 million US tons of QB are produced every year from the 3,000 operating quarries around the US. QB pose environmental and economic challenges as they accumulate in large quantities in landfills or interfere with quarry operations. With recent focus on sustainable construction practices and the scarcity of natural resources, more common and sustainable uses of by-product materials such as QB are becoming imperative. This dissertation focuses on the introduction and evaluation of new sustainable applications of QB and/or QB mixed with other marginal, virgin or recycled aggregate materials in pavements. The selected QB applications were evaluated through the construction of full-scale pavement test sections utilizing QB in targeted sustainable applications, and testing them with heavy wheel loads through Accelerated Pavement Testing (APT). The QB applications studied included both unbound and bound (chemically stabilized) pavement subsurface/foundation layers. The studied QB pavement applications were in five categories: (1) Using QB for filling voids between large stones as aggregate subgrade on soft subgrades; (2) increased fines content (e.g. 15% QB fines passing No. 200 sieve) in dense-graded aggregate subbase over soft subgrade soils; (3) using QB as a cement or fly ash-treated subbase (e.g., in inverted pavements); (4) using QB as a cement-treated base material; and (5) for base course applications, blending QB with coarse aggregate fractions of recycled materials and stabilizing the blends with 3% cement or 10% class C fly ash. In preparation for the field evaluations, several laboratory studies were conducted to finalize the designs of intended QB applications. The main laboratory studies were: (1) A packing study of QB with recycled coarse aggregates to determine the optimum blending ratio; (2) a packing study to aid the construction of large aggregate subgrade with QB materials filling the inherent voids; and, (3) Unconfined Compressive Strength (UCS) tests for chemically stabilized QB samples. Fifteen full-scale pavement test sections utilizing QB applications and one conventional flexible section were constructed in three ‘Test Cells.’ Cell 1 had four paved and four unpaved test sections to study construction platforms and low volume road applications of QB. Cells 2 and 3 studied chemically stabilized QB applications for base and subbase layers. Construction activities included engineering the top 305 mm (12 in.) of existing subgrade to a California Bearing Ratio (CBR) = 1% for Cell 1 test sections and to a CBR = 6% for all the pavement test sections in Cells 2 and 3. Subgrade modification was achieved through moisture adjustment and compaction. The construction of the QB layers were successfully achieved and extensively monitored. The data for nuclear density measurements and moisture contents indicated that nearly all the test sections were constructed at or near the targeted optimum moisture contents and achieved proper densities. A Lightweight Deflectometer (LWD) was used to assess the stiffness of the constructed layers after the construction of each lift. It was also used to monitor the increase in stiffness of the chemically stabilized layers. The increase in stiffness of the chemically stabilized layers was the highest for cement-stabilized test sections and usually lower for fly ash-stabilized sections. Following the paving of test sections with Hot Mix Asphalt (HMA), Falling Weight Deflectometer (FWD) tests were conducted on all finished surfaces. Significantly low deflection values were measured for the sections with cement-stabilized QB and QB blends with recycled aggregates. APT was conducted using the Advanced Transportation Loading Assembly (ATLAS). A constant unidirectional wheel load of 10 kips (44.5 kN), a tire pressure of 110 psi (760 kPa), and a constant speed of 5 mph (8 km/h) were assigned. The exceptionally good performance of some of the stabilized QB applications in Cells 2 and 3 necessitated trafficking in excess of 100,000 passes; an increased wheel load/tire pressure combination of 14 kip (62.3 kN)/ 125 psi (862 kPa) was adopted for the additional 35,000 passes. Four of the test sections in Cells 2 and 3 were instrumented with soil pressure cells on top of the engineered CBR = 6% subgrade. Data collected from these pressure cells showed that significantly low vertical pressures were transmitted to the subgrade for sections with stabilized bases/subbases. Measurements for rutting progression for the construction platform and HMA-paved test sections in Cell 1 showed good performance for the sections constructed with 15% nonplastic fines and with blends of large aggregate subgrade rocks with QB. Measurements of rutting progression in Cells 2 and 3 indicated exceptionally good performance of sections with blends of QB and recycled coarse aggregates stabilized with cement. Generally, sections stabilized with cement accumulated lower rutting than those stabilized with fly ash. No significant differences in rutting performance were detected for sections with QB from two different aggregate sources. For the inverted section with a cement-stabilized QB subbase, measured rut amounts were significantly lower than those in the test section with the fly ash-stabilized QB subbase. None of the stabilized sections showed any signs of cracks. Additional testing and forensic analyses were conducted after the APT study to better assess the performance of the constructed sections. These tests included: (1) FWD testing before and after APT; (2) HMA coring; (3) Dynamic Cone Penetrometer (DCP) testing for the aggregate subbase/base layers; (4) flooded tests for the aggregate subgrade/QB test sections; and (5) trenching to assess uniformity of construction and determine as-constructed layer thicknesses. Results from these forensic tests further supported the conclusions from the APT study indicating the overall quite satisfactory performance for the studied sustainable QB applications. Mechanistic analysis was conducted using GT-PAVE axisymmetric finite-element program to analyze the FWD results, and to calculate response benefits based on resilient FWD deflection for various design thicknesses and material properties. Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) studies were conducted to assess the environmental impacts and cost benefits for the studied QB applications. LCA and LCCA results for three scenarios, i.e. as-constructed and as-designed pavement thicknesses studied though APT and newly proposed pavement sections for low volume pavement alternatives, indicated that chemically stabilized QB and QB blended with recycled coarse aggregates could be successfully used to construct sustainable, resilient, and low cost pavements. Particularly, pavement structures with a low 3% cement-stabilized QB applications created high stiffness base/subbase layers in this study; they exhibited significant response benefits due to low FWD measured and predicted surface deflections and can withstand higher traffic volumes over pavement life

Open Skies

This open access book on the history of the National Radio Astronomy Observatory covers the scientific discoveries and technical innovations of late 20th century radio astronomy with particular attention to the people and institutions involved. The authors have made extensive use of the NRAO Archives, which contain an unparalleled collection of documents pertaining to the history of radio astronomy, including the institutional records of NRAO as well as the personal papers of many of the pioneers of U.S. radio astronomy. Technical details and extensive citations to original sources are given in notes for the more technical readers, but are not required for an understanding of the body of the book. This book is intended for an audience ranging from interested lay readers to professional researchers studying the scientific, technical, political, and cultural development of a new science, and how it changed the course of 20th century astronomy

Open Skies

This open access book on the history of the National Radio Astronomy Observatory covers the scientific discoveries and technical innovations of late 20th century radio astronomy with particular attention to the people and institutions involved. The authors have made extensive use of the NRAO Archives, which contain an unparalleled collection of documents pertaining to the history of radio astronomy, including the institutional records of NRAO as well as the personal papers of many of the pioneers of U.S. radio astronomy. Technical details and extensive citations to original sources are given in notes for the more technical readers, but are not required for an understanding of the body of the book. This book is intended for an audience ranging from interested lay readers to professional researchers studying the scientific, technical, political, and cultural development of a new science, and how it changed the course of 20th century astronomy