144,518 research outputs found
A Mechanized Semantic Framework for Real-Time Systems
International audienceConcurrent systems consist of many components which may execute in parallel and are complex to design, to analyze, to verify, and to implement. The complexity increases if the systems have real-time constraints, which are very useful in avionic, spatial and other kind of embedded applications. In this paper we present a logical framework for defining and validating real-time formalisms as well as reasoning methods over them. For this purpose, we have implemented in the Coq proof assistant well known semantic domains for real-time systems based on labelled transitions systems and timed runs. We experiment our framework by considering the real-time CSP-based language fiacre, which has been defined as a pivot formalism for modeling languages (aadl, sdl, ...) used in the TOPCASED project. Thus, we define an extension to the formal semantic models mentioned above that facilitates the modeling of fine-grained time constraints of fiacre. Finally, we implement this extension in our framework and provide a proof method environment to deal with real-time system in order to achieve their formal certification
MacFormer: Map-Agent Coupled Transformer for Real-time and Robust Trajectory Prediction
Predicting the future behavior of agents is a fundamental task in autonomous
vehicle domains. Accurate prediction relies on comprehending the surrounding
map, which significantly regularizes agent behaviors. However, existing methods
have limitations in exploiting the map and exhibit a strong dependence on
historical trajectories, which yield unsatisfactory prediction performance and
robustness. Additionally, their heavy network architectures impede real-time
applications. To tackle these problems, we propose Map-Agent Coupled
Transformer (MacFormer) for real-time and robust trajectory prediction. Our
framework explicitly incorporates map constraints into the network via two
carefully designed modules named coupled map and reference extractor. A novel
multi-task optimization strategy (MTOS) is presented to enhance learning of
topology and rule constraints. We also devise bilateral query scheme in context
fusion for a more efficient and lightweight network. We evaluated our approach
on Argoverse 1, Argoverse 2, and nuScenes real-world benchmarks, where it all
achieved state-of-the-art performance with the lowest inference latency and
smallest model size. Experiments also demonstrate that our framework is
resilient to imperfect tracklet inputs. Furthermore, we show that by combining
with our proposed strategies, classical models outperform their baselines,
further validating the versatility of our framework.Comment: Accepted by IEEE Robotics and Automation Letters. 8 Pages, 9 Figures,
9 Tables. Video: https://www.youtube.com/watch?v=XY388iI6sP
Incremental Latency Analysis of Heterogeneous Cyber-Physical Systems
REACTION 2014. 3rd International Workshop on Real-time and Distributed Computing in Emerging Applications. Rome, Italy. December 2nd, 2014.Cyber-Physical Systems, as used in automotive, avionics, or aerospace domains, have critical real-time require-ments. Time-related issues might have important impacts and, as these systems are becoming extremely software-reliant, validate and enforcing timing constraints is becoming difficult. Current techniques are mainly focused on validating these constraints late by using integration tests and tracing the system execution. Such methods are time-consuming and labor-intensive and, discovering timing issue late in the development process might incur significant rework efforts. In this paper, we propose an incremental model-based ap-proach to analyze and validate timing requirements of cyber-physical systems. We first capture the system functions, its related latency requirements and validate the end-to-end latency at a high level. This functional architecture is then refined into an implementation deployed on an execution platform. As system description is evolving, the latency analysis is being refined with more precise values. Such an approach provide latency analysis from a high level specification without having to implement the system, saving potential re-engineering efforts. It also helps engineers to select appropriate execution platform components or change the deployment strategy of system functions to ensure that latency requirements will be met when implementing the system.This material is based upon work funded and supported by the Department of Defense under Contract No. FA8721-05-C-0003 with Carnegie Mellon University for the operation of
the Software Engineering Institute, a federally funded research and development center
Towards Certain Fixes with Editing Rules and Master Data
A variety of integrity constraints have been studied for data cleaning. While these constraints can detect the presence of errors, they fall short of guiding us to correct the errors. Indeed, data repairing based on these constraints may not find
certain fixes
that are absolutely correct, and worse, may introduce new errors when repairing the data. We propose a method for finding certain fixes, based on master data, a notion of
certain regions
, and a class of
editing rules
. A certain region is a set of attributes that are assured correct by the users. Given a certain region and master data, editing rules tell us what attributes to fix and how to update them. We show how the method can be used in data monitoring and enrichment. We develop techniques for reasoning about editing rules, to decide whether they lead to a unique fix and whether they are able to fix all the attributes in a tuple,
relative
to master data and a certain region. We also provide an algorithm to identify minimal certain regions, such that a certain fix is warranted by editing rules and master data as long as one of the regions is correct. We experimentally verify the effectiveness and scalability of the algorithm.
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A new model for solution of complex distributed constrained problems
In this paper we describe an original computational model for solving
different types of Distributed Constraint Satisfaction Problems (DCSP). The
proposed model is called Controller-Agents for Constraints Solving (CACS). This
model is intended to be used which is an emerged field from the integration
between two paradigms of different nature: Multi-Agent Systems (MAS) and the
Constraint Satisfaction Problem paradigm (CSP) where all constraints are
treated in central manner as a black-box. This model allows grouping
constraints to form a subset that will be treated together as a local problem
inside the controller. Using this model allows also handling non-binary
constraints easily and directly so that no translating of constraints into
binary ones is needed. This paper presents the implementation outlines of a
prototype of DCSP solver, its usage methodology and overview of the CACS
application for timetabling problems
Toward a Unified Performance and Power Consumption NAND Flash Memory Model of Embedded and Solid State Secondary Storage Systems
This paper presents a set of models dedicated to describe a flash storage
subsystem structure, functions, performance and power consumption behaviors.
These models cover a large range of today's NAND flash memory applications.
They are designed to be implemented in simulation tools allowing to estimate
and compare performance and power consumption of I/O requests on flash memory
based storage systems. Such tools can also help in designing and validating new
flash storage systems and management mechanisms. This work is integrated in a
global project aiming to build a framework simulating complex flash storage
hierarchies for performance and power consumption analysis. This tool will be
highly configurable and modular with various levels of usage complexity
according to the required aim: from a software user point of view for
simulating storage systems, to a developer point of view for designing, testing
and validating new flash storage management systems
Moving from Data-Constrained to Data-Enabled Research: Experiences and Challenges in Collecting, Validating and Analyzing Large-Scale e-Commerce Data
Widespread e-commerce activity on the Internet has led to new opportunities
to collect vast amounts of micro-level market and nonmarket data. In this paper
we share our experiences in collecting, validating, storing and analyzing large
Internet-based data sets in the area of online auctions, music file sharing and
online retailer pricing. We demonstrate how such data can advance knowledge by
facilitating sharper and more extensive tests of existing theories and by
offering observational underpinnings for the development of new theories. Just
as experimental economics pushed the frontiers of economic thought by enabling
the testing of numerous theories of economic behavior in the environment of a
controlled laboratory, we believe that observing, often over extended periods
of time, real-world agents participating in market and nonmarket activity on
the Internet can lead us to develop and test a variety of new theories.
Internet data gathering is not controlled experimentation. We cannot randomly
assign participants to treatments or determine event orderings. Internet data
gathering does offer potentially large data sets with repeated observation of
individual choices and action. In addition, the automated data collection holds
promise for greatly reduced cost per observation. Our methods rely on
technological advances in automated data collection agents. Significant
challenges remain in developing appropriate sampling techniques integrating
data from heterogeneous sources in a variety of formats, constructing
generalizable processes and understanding legal constraints. Despite these
challenges, the early evidence from those who have harvested and analyzed large
amounts of e-commerce data points toward a significant leap in our ability to
understand the functioning of electronic commerce.Comment: Published at http://dx.doi.org/10.1214/088342306000000231 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Proof Generation from Delta-Decisions
We show how to generate and validate logical proofs of unsatisfiability from
delta-complete decision procedures that rely on error-prone numerical
algorithms. Solving this problem is important for ensuring correctness of the
decision procedures. At the same time, it is a new approach for automated
theorem proving over real numbers. We design a first-order calculus, and
transform the computational steps of constraint solving into logic proofs,
which are then validated using proof-checking algorithms. As an application, we
demonstrate how proofs generated from our solver can establish many nonlinear
lemmas in the the formal proof of the Kepler Conjecture.Comment: Appeared in SYNASC'1
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