Formal methods for functional verification of cache-coherent systems-on-chip

State-of-the-art System-on-Chip (SoC) architectures integrate many different components, such as processors, accelerators, memories, and I/O blocks. Some of those components, but not all, may have caches. Because the effort of validation with simulation-based techniques, currently used in industry, grows exponentially with the complexity of the SoC, this thesis investigates the use of formal verification techniques in this context. More precisely, we use the CADP toolbox to develop and validate a generic formal model of a heterogeneous cache-coherent SoC compliant with the recent AMBA 4 ACE specification proposed by ARM. We use a constraint-oriented specification style to model the general requirements of the specification. We verify system properties on both the constrained and unconstrained model to detect the cache coherency corner cases. We take advantage of the parametrization of the proposed model to produce a comprehensive set of counterexamples of non-satisfied properties in the unconstrained model. The results of formal verification are then used to improve the industrial simulation-based verification techniques in two aspects. On the one hand, we suggest using the formal model to assess the sanity of an interface verification unit. On the other hand, in order to generate clever semi-directed test cases from temporal logic properties, we propose a two-step approach. One step consists in generating system-level abstract test cases using model-based testing tools of the CADP toolbox. The other step consists in refining those tests into interface-level concrete test cases that can be executed at RTL level with a commercial Coverage-Directed Test Generation tool. We found that our approach helps in the transition between interface-level and system-level verification, facilitates the validation of system-level properties, and enables early detection of bugs in both the SoC and the commercial test-bench.Les architectures des systèmes sur puce (System-on-Chip, SoC) actuelles intègrent de nombreux composants différents tels que les processeurs, les accélérateurs, les mémoires et les blocs d'entrée/sortie, certains pouvant contenir des caches. Vu que l'effort de validation basée sur la simulation, actuellement utilisée dans l'industrie, croît de façon exponentielle avec la complexité des SoCs, nous nous intéressons à des techniques de vérification formelle. Nous utilisons la boîte à outils CADP pour développer et valider un modèle formel d'un SoC générique conforme à la spécification AMBA 4 ACE récemment proposée par ARM dans le but de mettre en œuvre la cohérence de cache au niveau système. Nous utilisons une spécification orientée contraintes pour modéliser les exigences générales de cette spécification. Les propriétés du système sont vérifié à la fois sur le modèle avec contraintes et le modèle sans contraintes pour détecter les cas intéressants pour la cohérence de cache. La paramétrisation du modèle proposé a permis de produire l'ensemble complet des contre-exemples qui ne satisfont pas une certaine propriété dans le modèle non contraint. Notre approche améliore les techniques industrielles de vérification basées sur la simulation en deux aspects. D'une part, nous suggérons l'utilisation du modèle formel pour évaluer la bonne construction d'une unité de vérification d'interface. D'autre part, dans l'objectif de générer des cas de test semi-dirigés intelligents à partir des propriétés de logique temporelle, nous proposons une approche en deux étapes. La première étape consiste à générer des cas de tests abstraits au niveau système en utilisant des outils de test basé sur modèle de la boîte à outils CADP. La seconde étape consiste à affiner ces tests en cas de tests concrets au niveau de l'interface qui peuvent être exécutés en RTL grâce aux services d'un outil commercial de génération de tests dirigés par les mesures de couverture. Nous avons constaté que notre approche participe dans la transition entre la vérification du niveau interface, classiquement pratiquée dans l'industrie du matériel, et la vérification au niveau système. Notre approche facilite aussi la validation des propriétés globales du système, et permet une détection précoce des bugs, tant dans le SoC que dans les bancs de test commerciales

FAA Center of Excellence for Alternative Jet Fuels & Environment: Annual Technical Report 2021: For the Period October 1, 2020 - September 30, 2021: Volume 2

FAA Award Number 13-C.This report covers the period October 1, 2020, through September 30, 2021. The Center was established by the authority of FAA solicitation 13-C-AJFE-Solicitation. During that time the ASCENT team launched a new website, which can be viewed at ascent.aero. The next meeting will be held April 5-7, 2022, in Alexandria, VA

Interrupt-generating active data objects

An investigation is presented into an interrupt-generating object model which is designed to reduce the effort of programming distributed memory multicomputer networks. The object model is aimed at the natural modelling of problem domains in which a number of concurrent entities interrupt one another as they lay claim to shared resources. The proposed computational model provides for the safe encapsulation of shared data, and incorporates inherent arbitration for simultaneous access to the data. It supplies a predicate triggering mechanism for use in conditional synchronization and as an alternative mechanism to polling. Linguistic support for the proposal requires a novel form of control structure which is able to interface sensibly with interrupt-generating active data objects. The thesis presents the proposal as an elemental language structure, with axiomatic guarantees which enforce safety properties and aid in program proving. The established theory of CSP is used to reason about the object model and its interface. An overview is presented of a programming language called HUL, whose semantics reflect the proposed computational model. Using the syntax of HUL, the application of the interrupt-generating active data object is illustrated. A range of standard concurrent problems is presented to demonstrate the properties of the interrupt-generating computational model. Furthermore, the thesis discusses implementation considerations which enable the model to be mapped precisely onto multicomputer networks, and which sustain the abstract programming level provided by the interrupt-generating active data object in the wider programming structures of HUL

7th International Conference on Higher Education Advances (HEAd'21)

Information and communication technologies together with new teaching paradigms are reshaping the learning environment.The International Conference on Higher Education Advances (HEAd) aims to become a forum for researchers and practitioners to exchange ideas, experiences,opinions and research results relating to the preparation of students and the organization of educational systems.Doménech I De Soria, J.; Merello Giménez, P.; Poza Plaza, EDL. (2021). 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. https://doi.org/10.4995/HEAD21.2021.13621EDITORIA

Repetition avoidance in human language

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2007.Includes bibliographical references (p. 208-225).Repetition is avoided in countless human languages and at a variety of grammatical levels. In this dissertation I ask what it is that makes repetition so bad. I propose that at least three distinct biases against repetition exist. First, repetition of articulatory gestures is relatively difficult. This difficulty results in phonetic variation that may lead to categorical phonological avoidance. I call this set of claims the Biomechanical Repetition Avoidance Hypothesis (BRAH), and support it with evidence from cross-linguistic patterns in repetition avoidance phenomena, articulatory data from music performance, and a series of phonetic experiments that document the proposed types of phonetic variation. Based on these data, I give an evolutionary account for antigemination in particular. The second anti-repetition bias is a perceptual deficit causing speakers not to perceive one of a sequence of repeated items, of any conceptual category. This bias is already well-documented, as are the grammatical effects (primarily haplology). I provide here the evidence of gradient variation in production bridging the two, from avoidance of homophone sequences in English corpora. The third factor is a principle disallowing the repetition of syntactic features in certain configurations within a phase domain. I document categorical effects of it in Semitic syntax of possession and relativization. These elicit repair strategies superficially similar to those of phonology (specifically, deletion and epenthesis/insertion). Repetition effects, then, are traceable to a variety of independent, functional biases. This argues against a unitary, innate constraint against repetition. Rather, multiple anti-repetition biases result in particular avoidance patterns, with their intersection producing additional asymmetries. Possible categorical repairs are further constrained by the nature of the formal grammatical system.by Mary Ann Walter.Ph.D

Model of Classroom Learning for Eighth Grade and High School Students Based on the Relationship Between Student Ability, Perceived Classroom Climate and Their Interaction

The study was to determine relationships between general ability (A), classroom averages of classroom environment (CE), and classroom learning (CL) and retention (Rtn) of eighth grade and high school students (S). A model of CL was proposed to investigate this problem. CL = f(A) + f(CE) + f(A X CE). This model was tested for two groups using analysis of partial variance (APV): an experimental group (E), and a control group (R). Both groups were taught the same unit of instruction (T). Focus was on representativeness of instructional treatment (T) - external validity, while maintaining internal validity. The T that S received was an average of 11.0 days of instruction on acid-base theory. Teachers (Trs) were instructed to teach using normal methods and materials. S taught by different Trs received different amounts and types of instruction. These differences were controlled by APV. Nine Trs volunteered. Trs were assigned to E and R. Trs taught 27 classes containing 541 S (375 high school and 166 eighth grade). Trs selected a unit on acid-base theory as the T. Sixteen independent variables (IV) were collected three weeks before T began. Trs administered three A tests (Cattell's Culture Fair Test: 4 scales), and a vocabulary (2 scales) and an induction test (I-1) (from Kit of Factor References Tests). Next, Trs administered the Classroom Environment Scale (CES: 9 scales). Two unit tests (UT) were designed by the author measuring CL and Rtn. A UT was administered to R as a pretest on the first day of T. AUT was administered to both the E and the R on the last day of the T. The T took 11.0 class periods to complete. After 15.3 days of the posttest, a UT was given to the E to measure Rtn. The 15 IV .were reduced to 5 factors (F) by a likelihood factor analysis and varimax rotation. Two A Fs were named verbal and nonverbal ability; three CE Fs were named: student centered environments (Env), high structure Env, and high discipline Env. The A set accounted for 13.8% (E) and 17.6% (R) of the covariate (COV) adjusted (Ad) CL variance (V). The CE set accounted for 8.5% (E) and 5.3% (R) of the Cov Ad Cl V. The (Grade level X CE) set accounted for 0.0% (E) and 4.5% (R) of the Cov Ad Cl V. The A set accounted for 11.8% (E) of the Cov Ad retention V. The CE set accounted for 13.6% of the Cov Ad Rtn V. The (A X CE) set accounted for 8.3% (E) of the Cov Ad Rtn V, and the (Grade level X CE) set accounted for 0.1% (E) of the Cov Ad Rtn V. The best model of Cl and Rtn only contained an A and a CE set. This model accounted for 23.6% (E), and 22.2% (R) of the Cov Ad Cl V, and 23.7% (E) of the Cov Ad Rtn V. There is a great deal of room for improvement. This model accounted for 45.8% (E) and 60.0% (R) of the total CL V, and 36.2% of the total Rtn V.Educational Psycholog