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Funqual: User-Defined, Statically-Checked Call Graph Constraints in C++Nelson, Andrew P 01 June 2018 (has links) (PDF)
Static analysis tools can aid programmers by reporting potential programming mistakes prior to the execution of a program. Funqual is a static analysis tool that reads C++17 code ``in the wild'' and checks that the function call graph follows a set of rules which can be defined by the user. This sort of analysis can help the programmer to avoid errors such as accidentally calling blocking functions in time-sensitive contexts or accidentally allocating memory in heap-sensitive environments. To accomplish this, we create a type system whereby functions can be given user-defined type qualifiers and where users can define their own restrictions on the call graph based on these type qualifiers. We demonstrate that this tool, when used with hand-crafted rules, can catch certain types of errors which commonly occur in the wild. We claim that this tool can be used in a production setting to catch certain kinds of errors in code before that code is even run.
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Determiningeons : a computer program for approximating lie generators admitted by dynamical systemsNagao, Gregory G. 01 January 1980 (has links) (PDF)
As was recognized by same of the most reputable physicists of the world such as Galilee and Einstein, the basic laws of physics must inevitably be founded upon invariance principles. Galilean and special relativity stand as historical landmarks that emphasize this message. It's no wonder that the great developments of modern physics (such as those in elementary particle physics) have been keyed upon this concept.
The modern formulation of classical mechanics (see Abraham and Marsden [1]) is based upon "qualitative" or geometric analysis. This is primarily due to the works of Poincare. Poincare showed the value of such geometric analysis in the solution of otherwise insoluble problems in stability theory. It seems that the insights of Poincare have proven fruitful by the now famous works of Kolmogorov, Arnold, and Moser. The concepts used in this geometric theory are again based upon invariance principles, or symmetries.
The work of Sophus Lie from 1873 to 1893 laid the groundwork for the analysis of invariance or symmetry principles in modern physics. His primary studies were those of partial differential equations. This led him to the study of the theory of transformations and inevitably to the analysis of abstract groups and differential geometry. Here we show same further applications of Lie group theory through the use of transformation groups. We emphasize the use of transformation invariance to find conservation laws and dynamical properties in chemical physics.
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Machine Learning-Based Instruction Scheduling for a DSP Architecture Compiler : Instruction Scheduling using Deep Reinforcement Learning and Graph Convolutional Networks / Maskininlärningsbaserad schemaläggning av instruktioner för en DSP-arkitekturkompilator : Schemaläggning av instruktioner med Deep Reinforcement Learning och grafkonvolutionella nätverkAlava Peña, Lucas January 2023 (has links)
Instruction Scheduling is a back-end compiler optimisation technique that can provide significant performance gains. It refers to ordering instructions in a particular order to reduce latency for processors with instruction-level parallelism. At the present typical compilers use heuristics to perform instruction scheduling and solve other related non-polynomial complete problems. This thesis aims to present a machine learning-based approach to challenge heuristic methods concerning performance. In this thesis, a novel reinforcement learning (RL) based model for the instruction scheduling problem is developed including modelling features of processors such as forwarding, resource utilisation and treatment of the action space. An efficient optimal scheduler is presented to be used for an optimal schedule length based reward function, however, this is not used in the final results as a heuristic based reward function was deemed to be sufficient and faster to compute. Furthermore, an RL agent that interacts with the model of the problem is presented using three different types of graph neural networks for the state processing: graph conventional networks, graph attention networks, and graph attention based on the work of Lee et al. A simple two-layer neural network is also used for generating embeddings for the resource utilisation stages. The proposed solution is validated against the modelled environment and favourable but not significant improvements were found compared to the most common heuristic method. Furthermore, it was found that having embeddings relating to resource utilisation was very important for the explained variance of the RL models. Additionally, a trained model was tested in an actual compiler, however, no informative results were found likely due to register allocation or other compiler stages that occur after instruction scheduling. Future work should include improving the scalability of the proposed solution. / Instruktionsschemaläggning är en optimeringsteknik för kompilatorer som kan ge betydande prestandavinster. Det handlar om att ordna instruktioner i en viss ordning för att minska latenstiden för processorer med parallellitet på instruktionsnivå. För närvarande använder vanliga kompilatorer heuristiker för att utföra schemaläggning av instruktioner och lösa andra relaterade ickepolynomiala kompletta problem. Denna avhandling syftar till att presentera en maskininlärningsbaserad metod för att utmana heuristiska metoder när det gäller prestanda. I denna avhandling utvecklas en ny förstärkningsinlärningsbaserad (RL) modell för schemaläggning av instruktioner, inklusive modellering av processorns egenskaper såsom vidarebefordran, resursutnyttjande och behandling av handlingsutrymmet. En effektiv optimal schemaläggare presenteras för att eventuellt användas för belöningsfunktionen, men denna används inte i de slutliga resultaten. Dessutom presenteras en RL-agent som interagerar med problemmodellen och använder tre olika typer av grafneurala nätverk för tillståndsprocessering: grafkonventionella nätverk, grafuppmärksamhetsnätverk och grafuppmärksamhet baserat på arbetet av Lee et al. Ett enkelt neuralt nätverk med två lager används också för att generera inbäddningar för resursanvändningsstegen. Den föreslagna lösningen valideras mot den modellerade miljön och gynnsamma men inte signifikanta förbättringar hittades jämfört med den vanligaste heuristiska metoden. Dessutom visade det sig att det var mycket viktigt för den förklarade variansen i RL-modellerna att ha inbäddningar relaterade till resursutnyttjande. Dessutom testades en tränad modell i en verklig kompilator, men inga informativa resultat hittades, sannolikt på grund av registerallokering eller andra kompilatorsteg som inträffar efter schemaläggning av instruktioner. Framtida arbete bör inkludera att förbättra skalbarheten hos den föreslagna lösningen.
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Design and Code Optimization for Systems with Next-generation Racetrack MemoriesKhan, Asif Ali 16 June 2022 (has links)
With the rise of computationally expensive application domains such as machine learning, genomics, and fluids simulation, the quest for performance and energy-efficient computing has gained unprecedented momentum. The significant increase in computing and memory devices in modern systems has resulted in an unsustainable surge in energy consumption, a substantial portion of which is attributed to the memory system. The scaling of conventional memory technologies and their suitability for the next-generation system is also questionable. This has led to the emergence and rise of nonvolatile memory ( NVM ) technologies. Today, in different development stages, several NVM technologies are competing for their rapid access to the market.
Racetrack memory ( RTM ) is one such nonvolatile memory technology that promises SRAM -comparable latency, reduced energy consumption, and unprecedented density compared to other technologies. However, racetrack memory ( RTM ) is sequential in nature, i.e., data in an RTM cell needs to be shifted to an access port before it can be accessed. These shift operations incur performance and energy penalties. An ideal RTM , requiring at most one shift per access, can easily outperform SRAM . However, in the worst-cast shifting scenario, RTM can be an order of magnitude slower than SRAM .
This thesis presents an overview of the RTM device physics, its evolution, strengths and challenges, and its application in the memory subsystem. We develop tools that allow the programmability and modeling of RTM -based systems. For shifts minimization, we propose a set of techniques including optimal, near-optimal, and evolutionary algorithms for efficient scalar and instruction placement in RTMs . For array accesses, we explore schedule and layout transformations that eliminate the longer overhead shifts in RTMs . We present an automatic compilation framework that analyzes static control flow programs and transforms the loop traversal order and memory layout to maximize accesses to consecutive RTM locations and minimize shifts. We develop a simulation framework called RTSim that models various RTM parameters and enables accurate architectural level simulation.
Finally, to demonstrate the RTM potential in non-Von-Neumann in-memory computing paradigms, we exploit its device attributes to implement logic and arithmetic operations. As a concrete use-case, we implement an entire hyperdimensional computing framework in RTM to accelerate the language recognition problem. Our evaluation shows considerable performance and energy improvements compared to conventional Von-Neumann models and state-of-the-art accelerators.
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Type-Safety for Inverse Imaging ProblemsMoghadas, Maryam 10 1900 (has links)
<p>This thesis gives a partial answer to the question: “Can type systems detect modeling errors in scientific computing, particularly for inverse problems derived from physical models?” by considering, in detail, the major aspects of inverse problems in Magnetic Resonance Imaging (MRI). We define a type-system that can capture all correctness properties for MRI inverse problems, including many properties that are not captured with current type-systems, e.g., frames of reference. We implemented a type-system in the Haskell language that can capture the errors arising in translating a mathe- matical model into a linear or nonlinear system, or alternatively into an objective function. Most models are (or can be approximated by) linear transformations, and we demonstrate the feasibility of capturing their correctness at the type level using what is arguably the most difficult case, the (discrete) Fourier transformation (DFT). By this, we mean that we are able to catch, at compile time, all known errors in ap- plying the DFT. The first part of this thesis describes the Haskell implementation of vector size, physical units, frame of reference, and so on required in the mathemat- ical modelling of inverse problems without regularization. To practically solve most inverse problems, especially those including noisy data or ill-conditioned systems, one must use regularization. The second part of this thesis addresses the question of defining new regularizers and identifying existing regularizers the correctness of which (in our estimation) can be formally verified at the type level. We describe such Bayesian regularization schemes based on probability theory, and describe a novel simple regularizer of this type. We leave as future work the formalization of such regularizers.</p> / Master of Science (MSc)
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AN INQUIRY INTO THE APPLICABILITY OF KANTOROVICH'S APPROACH TO THE THERMODYNAMIC OPTIMIZATIONDai, Cong 10 1900 (has links)
<p>The purpose of this research has been to reassess the Ag-Mg system using the CALPHAD technique. Compared with previous assessments, we carry out the optimization by fitting calculations to the original data instead of second-hand information. Moreover, we use a two sub-lattice model and a four sub-lattice model based on compound energy formalism to simulate both first-order and second-order transformations between the FCC phase and the L1<sub>2</sub> phase. Undoubtedly, the CALPHAD technique has achieved a degree of maturity, but its deficiencies are regularly ignored.</p> <p>In this thesis, we develop an interval method based on Kantorovich’s idea to overcome the shortcomings of the CALPHAD technique. Both advantages and disadvantages of the interval method are discussed. We also present an example of the interval approach on thermodynamic optimization of the Ag-Mg melt. The results suggest that this method would be helpful as a pre-optimization tool.</p> / Master of Applied Science (MASc)
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Automatic synthesis of application-specific processorsMutigwe, Charles January 2012 (has links)
Thesis (D. Tech. (Engineering: Electrical)) -- Central University of technology, Free State, 2012 / This thesis describes a method for the automatic generation of appli- cation speci_c processors. The thesis was organized into three sepa- rate but interrelated studies, which together provide: a justi_cation for the method used, a theory that supports the method, and a soft- ware application that realizes the method. The _rst study looked at how modern day microprocessors utilize their hardware resources and it proposed a metric, called core density, for measuring the utilization rate. The core density is a function of the microprocessor's instruction set and the application scheduled to run on that microprocessor. This study concluded that modern day microprocessors use their resources very ine_ciently and proposed the use of subset processors to exe- cute the same applications more e_ciently. The second study sought to provide a theoretical framework for the use of subset processors by developing a generic formal model of computer architecture. To demonstrate the model's versatility, it was used to describe a number of computer architecture components and entire computing systems. The third study describes the development of a set of software tools that enable the automatic generation of application speci_c proces- sors. The FiT toolkit automatically generates a unique Hardware Description Language (HDL) description of a processor based on an application binary _le and a parameterizable template of a generic mi- croprocessor. Area-optimized and performance-optimized custom soft processors were generated using the FiT toolkit and the utilization of the hardware resources by the custom soft processors was character- ized. The FiT toolkit was combined with an ANSI C compiler and a third-party tool for programming _eld-programmable gate arrays (FPGAs) to create an unconstrained C-to-silicon compiler.
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Math in the Dark: Tools for Expressing Mathematical Content by Visually Impaired StudentsMcDermott-Wells, Patricia M. 01 January 2015 (has links)
Blind and visually impaired students are under-represented in the science, technology, engineering, and mathematics disciplines of higher education and the workforce. This is due primarily to the difficulties they encounter in trying to succeed in mathematics courses. While there are sufficient tools available to create Braille content, including the special Nemeth Braille used in the U.S. for mathematics constructs, there are very few tools to allow a blind or visually impaired student to create his/her own mathematical content in a manner that sighted individuals can use. The software tools that are available are isolated, do not interface well with other common software, and may be priced for institutional use instead of individual use. Instructors are unprepared or unable to interact with these students in a real-time manner. All of these factors combine to isolate the blind or visually impaired student in the study of mathematics. Nemeth Braille is a complete mathematical markup system in Braille, containing everything that is needed to produce quality math content at all levels of complexity. Blind and visually impaired students should not have to learn any additional markup languages in order to produce math content.
This work addressed the needs of the individual blind or visually impaired student who must be able to produce mathematical content for course assignments, and who wishes to interact with peers and instructors on a real-time basis to share mathematical content. Two tools were created to facilitate mathematical interaction: a Nemeth Braille editor, and a real-time instant messenger chat capability that supports Nemeth Braille and MathML constructs. In the Visually Impaired view, the editor accepts Nemeth Braille input, displays the math expressions in a tree structure which will allow sub-expressions to be expanded or collapsed. The Braille constructs can be translated to MathML for display within MathType. Similarly, in the Sighted view, math constructs entered in MathType can be translated into Nemeth Braille. Mathematical content can then be shared between sighted and visually impaired users via the instant messenger chat capability.
Using Math in the Dark software, blind and visually impaired students can work math problems fully in Nemeth Braille and can seamlessly convert their work into MathML for viewing by sighted instructors. The converted output has the quality of professionally produced math content. Blind and VI students can also communicate and share math constructs with a sighted partner via a real-time chat feature, with automatic translation in both directions, allowing VI students to obtain help in real-time from a sighted instructor or tutor. By eliminating the burden of translation, this software will help to remove the barriers faced by blind and VI students who wish to excel in the STEM fields of study.
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A Predictive Modeling System: Early identification of students at-risk enrolled in online learning programsFonti, Mary L. 01 January 2015 (has links)
Predictive statistical modeling shows promise in accurately predicting academic performance for students enrolled in online programs. This approach has proven effective in accurately identifying students who are at-risk enabling instructors to provide instructional intervention. While the potential benefits of statistical modeling is significant, implementations have proven to be complex, costly, and difficult to maintain. To address these issues, the purpose of this study is to develop a fully integrated, automated predictive modeling system (PMS) that is flexible, easy to use, and portable to identify students who are potentially at-risk for not succeeding in a course they are currently enrolled in. Dynamic and static variables from a student system (edX) will be analyzed to predict academic performance of an individual student or entire class. The PMS model framework will include development of an open-source Web application, application programming interface (API), and SQL reporting services (SSRS). The model is based on knowledge discovery database (KDD) approach utilizing inductive logic programming language (ILP) to analyze student data. This alternative approach for predicting academic performance has several unique advantages over current predictive modeling techniques in use and is a promising new direction in educational research.
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[en] X-SMIL: IMPROVING REUSE AND EXPRESSIVENESS IN HYPERMEDIA AUTHORING LANGUAGES / [pt] X-SMIL: AUMENTANDO REUSO E EXPRESSIVIDADE EM LINGUAGENS DE AUTORIA HIPERMÍDIAHERON VILELA DE OLIVEIRA E SILVA 26 August 2005 (has links)
[pt] Este trabalho está inserido no contexto de ambientes de
autoria e execução
hipermídia, sendo as linguagens declarativas para autoria
de documentos o seu
foco principal. Tendo-se como objetivo aumentar a
expressividade e o reuso na
especificação de documentos hipermídia, este trabalho
introduz as linguagens XSMIL
e NCL - Nested Context Language - versão 2.1. Utilizando-
se o conceito de
templates, X-SMIL permite a definição de novas semânticas
para composições
SMIL, além dos tradicionais elementos seq, par e excl.
Templates, em X-SMIL,
são especificados em um perfil de XTemplate, que estende a
idéia original da
linguagem XTemplate de NCL. Com base nas novas facilidades
para definição de
templates, esse perfil foi usado para especificar a
linguagem NCL 2.1. X-SMIL
também permite a especificação de conectores hipermídia,
tratando relações
hipermídia como entidades de primeira classe -
funcionalidade incorporada em XSMIL
pelo uso do módulo XConnector de NCL. Outro objetivo deste
trabalho é o
de apresentar um framework para o processamento de
documentos XML.
Utilizando-se esse framework, diversos compiladores foram
implementados, o
que possibilitou, entre outras funcionalidades, a
conversão de documentos NCL
em especificações SMIL ou X-SMIL e vice-versa. / [en] This work is related to hypermedia authoring and execution
environments,
and its main focus is declarative document authoring.
Aiming at improving the
expressiveness and reuse in the specification of
hypermedia documents, this work
introduces the hypermedia authoring languages X-SMIL and
NCL - Nested
Context Language - version 2.1. Exploiting the concept of
templates, X-SMIL
allows the definition of new semantics for SMIL
compositions, besides its usual
seq, par and excl elements. X-SMIL templates are specified
using an XTemplate
profile, which extends the original idea of the NCL
XTemplate language.
Bringing new facilities for template definitions, this new
profile is used to further
improve the NCL language. X-SMIL also offers support for
handling hypermedia
relations as first-class entities, through the use of
hypermedia connectors - brought
to X-SMIL via the NCL XConnector module. Another important
goal of this work
is to present a framework to facilitate the development of
XML documents
parsing and processing tools. Based on this framework,
several compilers were
implemented, permitting, among other features, the
conversion of NCL
documents into SMIL or X-SMIL specifications and vice-
versa.
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