232 research outputs found

    Reluplex: An Efficient SMT Solver for Verifying Deep Neural Networks

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    Deep neural networks have emerged as a widely used and effective means for tackling complex, real-world problems. However, a major obstacle in applying them to safety-critical systems is the great difficulty in providing formal guarantees about their behavior. We present a novel, scalable, and efficient technique for verifying properties of deep neural networks (or providing counter-examples). The technique is based on the simplex method, extended to handle the non-convex Rectified Linear Unit (ReLU) activation function, which is a crucial ingredient in many modern neural networks. The verification procedure tackles neural networks as a whole, without making any simplifying assumptions. We evaluated our technique on a prototype deep neural network implementation of the next-generation airborne collision avoidance system for unmanned aircraft (ACAS Xu). Results show that our technique can successfully prove properties of networks that are an order of magnitude larger than the largest networks verified using existing methods.Comment: This is the extended version of a paper with the same title that appeared at CAV 201

    Optimal Relative Path Planning for Constrained Stochastic Space Systems

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    Rendezvous and proximity operations for automated spacecraft systems requires advanced path planning techniques that are capable of generating optimal paths. Real-world constraints, such as sensor noise and actuator errors, complicate the planning process. Operations also require flight safety considerations in order to prevent the spacecraft from potentially colliding with the associated companion spacecraft. This work proposes a new, ground-based trajectory planning approach that seeks an optimal trajectory while meeting all mission constraints and accounting for vehicle performance and safety requirements. This approach uses a closed-loop linear covariance simulation of the relative trajectory coupled with a genetic algorithm to determine fuel optimal trajectories. Spacecraft safety is addressed using statistical data from the linear covariance model to bound the probability of collision

    Fourth Annual Workshop on Space Operations Applications and Research (SOAR 90)

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    The proceedings of the SOAR workshop are presented. The technical areas included are as follows: Automation and Robotics; Environmental Interactions; Human Factors; Intelligent Systems; and Life Sciences. NASA and Air Force programmatic overviews and panel sessions were also held in each technical area

    Analysis and simulation of emergent architectures for internet of things

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    The Internet of Things (IoT) promises a plethora of new services and applications supported by a wide range of devices that includes sensors and actuators. To reach its potential IoT must break down the silos that limit applications' interoperability and hinder their manageability. These silos' result from existing deployment techniques where each vendor set up its own infrastructure, duplicating the hardware and increasing the costs. Fog Computing can serve as the underlying platform to support IoT applications thus avoiding the silos'. Each application becomes a system formed by IoT devices (i.e. sensors, actuators), an edge infrastructure (i.e. Fog Computing) and the Cloud. In order to improve several aspects of human lives, different systems can interact to correlate data obtaining functionalities not achievable by any of the systems in isolation. Then, we can analyze the IoT as a whole system rather than a conjunction of isolated systems. Doing so leads to the building of Ultra-Large Scale Systems (ULSS), an extension of the concept of Systems of Systems (SoS), in several verticals including Autonomous Vehicles, Smart Cities, and Smart Grids. The scope of ULSS is large in the number of things and complex in the variety of applications, volume of data, and diversity of communication patterns. To handle this scale and complexity in this thesis we propose Hierarchical Emergent Behaviors (HEB), a paradigm that builds on the concepts of emergent behavior and hierarchical organization. Rather than explicitly program all possible situations in the vast space of ULSS scenarios, HEB relies on emergent behaviors induced by local rules that define the interactions of the "things" between themselves and also with their environment. We discuss the modifications to classical IoT architectures required by HEB, as well as the new challenges. Once these challenges such as scalability and manageability are addressed, we can illustrate HEB's usefulness dealing with an IoT-based ULSS through a case study based on Autonomous Vehicles (AVs). To this end we design and analyze well-though simulations that demonstrate its tremendous potential since small modifications to the basic set of rules induce different and interesting behaviors. Then we design a set of primitives to perform basic maneuver such as exiting a platoon formation and maneuvering in anticipation of obstacles beyond the range of on-board sensors. These simulations also evaluate the impact of a HEB deployment assisted by Fog nodes to enlarge the informational scope of vehicles. To conclude we develop a design methodology to build, evaluate, and run HEB-based solutions for AVs. We provide architectural foundations for the second level and its implications in major areas such as communications. These foundations are then validated through simulations that incorporate new rules, obtaining valuable experimental observations. The proposed architecture has a tremendous potential to solve the scalability issue found in ULSS, enabling IoT deployments to reach its true potential.El Internet de las Cosas (IoT) promete una plétora de nuevos servicios y aplicaciones habilitadas por una amplia gama de dispositivos que incluye sensores y actuadores. Para alcanzar su potencial, IoT debe superar los silos que limitan la interoperabilidad de las aplicaciones y dificultan su administración. Estos silos son el resultado de las técnicas de implementación existentes en las que cada proveedor instala su propia infraestructura y duplica el hardware, incrementando los costes. Fog Computing puede servir como la plataforma subyacente que soporte aplicaciones del IoT evitando así los silos. Cada aplicación se convierte en un sistema formado por dispositivos IoT (por ejemplo sensores y actuadores), una infraestructura (como Fog Computing) y la nube. Con el fin de mejorar varios aspectos de la vida humana, diferentes sistemas pueden interactuar para correlacionar datos obteniendo funcionalidades que no pueden lograrse por ninguno de los sistemas de forma aislada. Entonces, podemos analizar el IoT como un único sistema en lugar de una conjunción de sistemas aislados. Esta perspectiva conduce a la construcción de Ultra-Large Scale Systems (ULSS), una extensión del concepto de Systems of Systems (SoS), en varios verticales, incluidos los vehículos autónomos, Smart Cities y Smart Grids. El alcance de ULSS es vasto debido a la cantidad de dispositivos y complejo en la variedad de aplicaciones, volumen de datos y diversidad de patrones de comunicación. Para manejar esta escala y complejidad, en esta tesis proponemos Hierarchical Emergent Behaviors (HEB), un paradigma que se basa en los conceptos de comportamientos emergente y organización jerárquica. En lugar de programar explícitamente todas las situaciones posibles en el vasto espacio de escenarios presentes en los ULSS, HEB se basa en comportamientos emergentes inducidos por reglas locales que definen las interacciones de las "cosas" entre ellas y también con su entorno. Discutimos las modificaciones a las arquitecturas clásicas de IoT requeridas por HEB, así como los nuevos desafíos. Una vez que se abordan estos desafíos, como la escalabilidad y la capacidad de administración, podemos ilustrar la utilidad de HEB cuando se ocupa de un ULSS basado en IoT a través de un caso de estudio basado en Vehículos Autónomos (AV). Con este fin, diseñamos y analizamos simulaciones que demuestran su enorme potencial, ya que pequeñas modificaciones en el conjunto básico de reglas inducen comportamientos diferentes e interesantes. Luego, diseñamos un conjunto de primitivas para realizar una maniobra básica, como salir de un pelotón y maniobrar en anticipación de obstáculos más allá del alcance de los sensores de a bordo. Estas simulaciones también evalúan el impacto de una implementación de HEB asistida por nodos de Fog Computing para ampliar el alcance sensorial de los vehículos. Para concluir, desarrollamos una metodología de diseño para construir, evaluar y ejecutar soluciones basadas en HEB para AV. Brindamos fundamentos arquitectónicos para el segundo nivel de HEB y sus implicaciones en áreas importantes como las comunicaciones. Estas bases se validan a través de simulaciones que incorporan nuevas reglas, obteniendo valiosas observaciones experimentales. La arquitectura propuesta tiene un enorme potencial para resolver el problema de escalabilidad que presentan los ULSS, permitiendo que las implementaciones de IoT alcancen su verdadero potencial.Postprint (published version

    Analysis and simulation of emergent architectures for internet of things

    Get PDF
    The Internet of Things (IoT) promises a plethora of new services and applications supported by a wide range of devices that includes sensors and actuators. To reach its potential IoT must break down the silos that limit applications' interoperability and hinder their manageability. These silos' result from existing deployment techniques where each vendor set up its own infrastructure, duplicating the hardware and increasing the costs. Fog Computing can serve as the underlying platform to support IoT applications thus avoiding the silos'. Each application becomes a system formed by IoT devices (i.e. sensors, actuators), an edge infrastructure (i.e. Fog Computing) and the Cloud. In order to improve several aspects of human lives, different systems can interact to correlate data obtaining functionalities not achievable by any of the systems in isolation. Then, we can analyze the IoT as a whole system rather than a conjunction of isolated systems. Doing so leads to the building of Ultra-Large Scale Systems (ULSS), an extension of the concept of Systems of Systems (SoS), in several verticals including Autonomous Vehicles, Smart Cities, and Smart Grids. The scope of ULSS is large in the number of things and complex in the variety of applications, volume of data, and diversity of communication patterns. To handle this scale and complexity in this thesis we propose Hierarchical Emergent Behaviors (HEB), a paradigm that builds on the concepts of emergent behavior and hierarchical organization. Rather than explicitly program all possible situations in the vast space of ULSS scenarios, HEB relies on emergent behaviors induced by local rules that define the interactions of the "things" between themselves and also with their environment. We discuss the modifications to classical IoT architectures required by HEB, as well as the new challenges. Once these challenges such as scalability and manageability are addressed, we can illustrate HEB's usefulness dealing with an IoT-based ULSS through a case study based on Autonomous Vehicles (AVs). To this end we design and analyze well-though simulations that demonstrate its tremendous potential since small modifications to the basic set of rules induce different and interesting behaviors. Then we design a set of primitives to perform basic maneuver such as exiting a platoon formation and maneuvering in anticipation of obstacles beyond the range of on-board sensors. These simulations also evaluate the impact of a HEB deployment assisted by Fog nodes to enlarge the informational scope of vehicles. To conclude we develop a design methodology to build, evaluate, and run HEB-based solutions for AVs. We provide architectural foundations for the second level and its implications in major areas such as communications. These foundations are then validated through simulations that incorporate new rules, obtaining valuable experimental observations. The proposed architecture has a tremendous potential to solve the scalability issue found in ULSS, enabling IoT deployments to reach its true potential.El Internet de las Cosas (IoT) promete una plétora de nuevos servicios y aplicaciones habilitadas por una amplia gama de dispositivos que incluye sensores y actuadores. Para alcanzar su potencial, IoT debe superar los silos que limitan la interoperabilidad de las aplicaciones y dificultan su administración. Estos silos son el resultado de las técnicas de implementación existentes en las que cada proveedor instala su propia infraestructura y duplica el hardware, incrementando los costes. Fog Computing puede servir como la plataforma subyacente que soporte aplicaciones del IoT evitando así los silos. Cada aplicación se convierte en un sistema formado por dispositivos IoT (por ejemplo sensores y actuadores), una infraestructura (como Fog Computing) y la nube. Con el fin de mejorar varios aspectos de la vida humana, diferentes sistemas pueden interactuar para correlacionar datos obteniendo funcionalidades que no pueden lograrse por ninguno de los sistemas de forma aislada. Entonces, podemos analizar el IoT como un único sistema en lugar de una conjunción de sistemas aislados. Esta perspectiva conduce a la construcción de Ultra-Large Scale Systems (ULSS), una extensión del concepto de Systems of Systems (SoS), en varios verticales, incluidos los vehículos autónomos, Smart Cities y Smart Grids. El alcance de ULSS es vasto debido a la cantidad de dispositivos y complejo en la variedad de aplicaciones, volumen de datos y diversidad de patrones de comunicación. Para manejar esta escala y complejidad, en esta tesis proponemos Hierarchical Emergent Behaviors (HEB), un paradigma que se basa en los conceptos de comportamientos emergente y organización jerárquica. En lugar de programar explícitamente todas las situaciones posibles en el vasto espacio de escenarios presentes en los ULSS, HEB se basa en comportamientos emergentes inducidos por reglas locales que definen las interacciones de las "cosas" entre ellas y también con su entorno. Discutimos las modificaciones a las arquitecturas clásicas de IoT requeridas por HEB, así como los nuevos desafíos. Una vez que se abordan estos desafíos, como la escalabilidad y la capacidad de administración, podemos ilustrar la utilidad de HEB cuando se ocupa de un ULSS basado en IoT a través de un caso de estudio basado en Vehículos Autónomos (AV). Con este fin, diseñamos y analizamos simulaciones que demuestran su enorme potencial, ya que pequeñas modificaciones en el conjunto básico de reglas inducen comportamientos diferentes e interesantes. Luego, diseñamos un conjunto de primitivas para realizar una maniobra básica, como salir de un pelotón y maniobrar en anticipación de obstáculos más allá del alcance de los sensores de a bordo. Estas simulaciones también evalúan el impacto de una implementación de HEB asistida por nodos de Fog Computing para ampliar el alcance sensorial de los vehículos. Para concluir, desarrollamos una metodología de diseño para construir, evaluar y ejecutar soluciones basadas en HEB para AV. Brindamos fundamentos arquitectónicos para el segundo nivel de HEB y sus implicaciones en áreas importantes como las comunicaciones. Estas bases se validan a través de simulaciones que incorporan nuevas reglas, obteniendo valiosas observaciones experimentales. La arquitectura propuesta tiene un enorme potencial para resolver el problema de escalabilidad que presentan los ULSS, permitiendo que las implementaciones de IoT alcancen su verdadero potencial

    Doctor of Philosophy

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    dissertationIn computer science, functional software testing is a method of ensuring that software gives expected output on specific inputs. Software testing is conducted to ensure desired levels of quality in light of uncertainty resulting from the complexity of software. Most of today's software is written by people and software development is a creative activity. However, due to the complexity of computer systems and software development processes, this activity leads to a mismatch between the expected software functionality and the implemented one. If not addressed in a timely and proper manner, this mismatch can cause serious consequences to users of the software, such as security and privacy breaches, financial loss, and adversarial human health issues. Because of manual effort, software testing is costly. Software testing that is performed without human intervention is automatic software testing and it is one way of addressing the issue. In this work, we build upon and extend several techniques for automatic software testing. The techniques do not require any guidance from the user. Goals that are achieved with the techniques are checking for yet unknown errors, automatically testing object-oriented software, and detecting malicious software. To meet these goals, we explored several techniques and related challenges: automatic test case generation, runtime verification, dynamic symbolic execution, and the type and size of test inputs for efficient detection of malicious software via machine learning. Our work targets software written in the Java programming language, though the techniques are general and applicable to other languages. We performed an extensive evaluation on freely available Java software projects, a flight collision avoidance system, and thousands of applications for the Android operating system. Evaluation results show to what extent dynamic symbolic execution is applicable in testing object-oriented software, they show correctness of the flight system on millions of automatically customized and generated test cases, and they show that simple and relatively small inputs in random testing can lead to effective malicious software detection

    Detection of Feature Interactions in Automotive Active Safety Features

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    With the introduction of software into cars, many functions are now realized with reduced cost, weight and energy. The development of these software systems is done in a distributed manner independently by suppliers, following the traditional approach of the automotive industry, while the car maker takes care of the integration. However, the integration can lead to unexpected and unintended interactions among software systems, a phenomena regarded as feature interaction. This dissertation addresses the problem of the automatic detection of feature interactions for automotive active safety features. Active safety features control the vehicle's motion control systems independently from the driver's request, with the intention of increasing passengers' safety (e.g., by applying hard braking in the case of an identified imminent collision), but their unintended interactions could instead endanger the passengers (e.g., simultaneous throttle increase and sharp narrow steering, causing the vehicle to roll over). My method decomposes the problem into three parts: (I) creation of a definition of feature interactions based on the set of actuators and domain expert knowledge; (II) translation of automotive active safety features designed using a subset of Matlab's Stateflow into the input language of the model checker SMV; (III) analysis using model checking at design time to detect a representation of all feature interactions based on partitioning the counterexamples into equivalence classes. The key novel characteristic of my work is exploiting domain-specific information about the feature interaction problem and the structure of the model to produce a method that finds a representation of all different feature interactions for automotive active safety features at design time. My method is validated by a case study with the set of non-proprietary automotive feature design models I created. The method generates a set of counterexamples that represent the whole set of feature interactions in the case study.By showing only a set of representative feature interaction cases, the information is concise and useful for feature designers. Moreover, by generating these results from feature models designed in Matlab's Stateflow translated into SMV models, the feature designers can trace the counterexamples generated by SMV and understand the results in terms of the Stateflow model. I believe that my results and techniques will have relevance to the solution of the feature interaction problem in other cyber-physical systems, and have a direct impact in assessing the safety of automotive systems

    Advances in Spacecraft Systems and Orbit Determination

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    "Advances in Spacecraft Systems and Orbit Determinations", discusses the development of new technologies and the limitations of the present technology, used for interplanetary missions. Various experts have contributed to develop the bridge between present limitations and technology growth to overcome the limitations. Key features of this book inform us about the orbit determination techniques based on a smooth research based on astrophysics. The book also provides a detailed overview on Spacecraft Systems including reliability of low-cost AOCS, sliding mode controlling and a new view on attitude controller design based on sliding mode, with thrusters. It also provides a technological roadmap for HVAC optimization. The book also gives an excellent overview of resolving the difficulties for interplanetary missions with the comparison of present technologies and new advancements. Overall, this will be very much interesting book to explore the roadmap of technological growth in spacecraft systems

    Analysis and simulation of emergent architectures for internet of things

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    The Internet of Things (IoT) promises a plethora of new services and applications supported by a wide range of devices that includes sensors and actuators. To reach its potential IoT must break down the silos that limit applications' interoperability and hinder their manageability. These silos' result from existing deployment techniques where each vendor set up its own infrastructure, duplicating the hardware and increasing the costs. Fog Computing can serve as the underlying platform to support IoT applications thus avoiding the silos'. Each application becomes a system formed by IoT devices (i.e. sensors, actuators), an edge infrastructure (i.e. Fog Computing) and the Cloud. In order to improve several aspects of human lives, different systems can interact to correlate data obtaining functionalities not achievable by any of the systems in isolation. Then, we can analyze the IoT as a whole system rather than a conjunction of isolated systems. Doing so leads to the building of Ultra-Large Scale Systems (ULSS), an extension of the concept of Systems of Systems (SoS), in several verticals including Autonomous Vehicles, Smart Cities, and Smart Grids. The scope of ULSS is large in the number of things and complex in the variety of applications, volume of data, and diversity of communication patterns. To handle this scale and complexity in this thesis we propose Hierarchical Emergent Behaviors (HEB), a paradigm that builds on the concepts of emergent behavior and hierarchical organization. Rather than explicitly program all possible situations in the vast space of ULSS scenarios, HEB relies on emergent behaviors induced by local rules that define the interactions of the "things" between themselves and also with their environment. We discuss the modifications to classical IoT architectures required by HEB, as well as the new challenges. Once these challenges such as scalability and manageability are addressed, we can illustrate HEB's usefulness dealing with an IoT-based ULSS through a case study based on Autonomous Vehicles (AVs). To this end we design and analyze well-though simulations that demonstrate its tremendous potential since small modifications to the basic set of rules induce different and interesting behaviors. Then we design a set of primitives to perform basic maneuver such as exiting a platoon formation and maneuvering in anticipation of obstacles beyond the range of on-board sensors. These simulations also evaluate the impact of a HEB deployment assisted by Fog nodes to enlarge the informational scope of vehicles. To conclude we develop a design methodology to build, evaluate, and run HEB-based solutions for AVs. We provide architectural foundations for the second level and its implications in major areas such as communications. These foundations are then validated through simulations that incorporate new rules, obtaining valuable experimental observations. The proposed architecture has a tremendous potential to solve the scalability issue found in ULSS, enabling IoT deployments to reach its true potential.El Internet de las Cosas (IoT) promete una plétora de nuevos servicios y aplicaciones habilitadas por una amplia gama de dispositivos que incluye sensores y actuadores. Para alcanzar su potencial, IoT debe superar los silos que limitan la interoperabilidad de las aplicaciones y dificultan su administración. Estos silos son el resultado de las técnicas de implementación existentes en las que cada proveedor instala su propia infraestructura y duplica el hardware, incrementando los costes. Fog Computing puede servir como la plataforma subyacente que soporte aplicaciones del IoT evitando así los silos. Cada aplicación se convierte en un sistema formado por dispositivos IoT (por ejemplo sensores y actuadores), una infraestructura (como Fog Computing) y la nube. Con el fin de mejorar varios aspectos de la vida humana, diferentes sistemas pueden interactuar para correlacionar datos obteniendo funcionalidades que no pueden lograrse por ninguno de los sistemas de forma aislada. Entonces, podemos analizar el IoT como un único sistema en lugar de una conjunción de sistemas aislados. Esta perspectiva conduce a la construcción de Ultra-Large Scale Systems (ULSS), una extensión del concepto de Systems of Systems (SoS), en varios verticales, incluidos los vehículos autónomos, Smart Cities y Smart Grids. El alcance de ULSS es vasto debido a la cantidad de dispositivos y complejo en la variedad de aplicaciones, volumen de datos y diversidad de patrones de comunicación. Para manejar esta escala y complejidad, en esta tesis proponemos Hierarchical Emergent Behaviors (HEB), un paradigma que se basa en los conceptos de comportamientos emergente y organización jerárquica. En lugar de programar explícitamente todas las situaciones posibles en el vasto espacio de escenarios presentes en los ULSS, HEB se basa en comportamientos emergentes inducidos por reglas locales que definen las interacciones de las "cosas" entre ellas y también con su entorno. Discutimos las modificaciones a las arquitecturas clásicas de IoT requeridas por HEB, así como los nuevos desafíos. Una vez que se abordan estos desafíos, como la escalabilidad y la capacidad de administración, podemos ilustrar la utilidad de HEB cuando se ocupa de un ULSS basado en IoT a través de un caso de estudio basado en Vehículos Autónomos (AV). Con este fin, diseñamos y analizamos simulaciones que demuestran su enorme potencial, ya que pequeñas modificaciones en el conjunto básico de reglas inducen comportamientos diferentes e interesantes. Luego, diseñamos un conjunto de primitivas para realizar una maniobra básica, como salir de un pelotón y maniobrar en anticipación de obstáculos más allá del alcance de los sensores de a bordo. Estas simulaciones también evalúan el impacto de una implementación de HEB asistida por nodos de Fog Computing para ampliar el alcance sensorial de los vehículos. Para concluir, desarrollamos una metodología de diseño para construir, evaluar y ejecutar soluciones basadas en HEB para AV. Brindamos fundamentos arquitectónicos para el segundo nivel de HEB y sus implicaciones en áreas importantes como las comunicaciones. Estas bases se validan a través de simulaciones que incorporan nuevas reglas, obteniendo valiosas observaciones experimentales. La arquitectura propuesta tiene un enorme potencial para resolver el problema de escalabilidad que presentan los ULSS, permitiendo que las implementaciones de IoT alcancen su verdadero potencial.Postprint (published version

    Terrain Representation And Reasoning In Computer Generated Forces : A Survey Of Computer Generated Forces Systems And How They Represent And Reason About Terrain

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    Report on a survey of computer systems used to produce realistic or intelligent behavior by autonomous entities in simulation systems. In particular, it is concerned with the data structures used by computer generated forces systems to represent terrain and the algorithmic approaches used by those systems to reason about terrain
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