96,212 research outputs found
Multisensor Data Fusion Implementation for a Sensor Based Fertilizer Application System
"Mapping systems" (“mapping approach”), real-time sensor-actuator systems ("sensor
approach") or the combination of both (“Real-time approach with map overlay”) determine the
process control in mobile application systems for spatially variable fertilization. Within the
integrated research project “Information Systems Precision Farming Duernast” (IKB Duernast)
the implementation of the “Real-time approach with map overlay” was done for intensive
nitrogen fertilization. The bottom line of this sophisticated approach is a comprehensive situation
assessment, a typical multisensor data fusion task. Based on a functional and procedural
modelling of the multisensor data fusion and decision making process, it could be pointed out
that an expert system is an adequate fusion paradigm and algorithm. Therefore, a software
simulation with an expert system as core element was implemented to fuse on-line sensor
technology measurements (REIP), maps (yield, EM38, environmental constraints, draft force)
and user inputs in order to derive an application set point in real-time. The development of an
expert system can be viewed as a structured transformation in five levels from the “specification
level”, the “task level”, the “problem solving level” and the “knowledge base level” to the “tool
level”. In the “tool level” the hybrid expert system shell JESS (Java Expert System Shell) was
selected for implementation due to the results of preceding levels. Knowledge acquisition was
done within another IKB-subproject by the means of data mining. Typical and maximal times of
10 ms and 60 ms for one fusion cycle were measured running this application on a 32-bit
processor hardware (Intel Pentium III Mobile, 1 GHz)
Verified Correctness and Security of mbedTLS HMAC-DRBG
We have formalized the functional specification of HMAC-DRBG (NIST 800-90A),
and we have proved its cryptographic security--that its output is
pseudorandom--using a hybrid game-based proof. We have also proved that the
mbedTLS implementation (C program) correctly implements this functional
specification. That proof composes with an existing C compiler correctness
proof to guarantee, end-to-end, that the machine language program gives strong
pseudorandomness. All proofs (hybrid games, C program verification, compiler,
and their composition) are machine-checked in the Coq proof assistant. Our
proofs are modular: the hybrid game proof holds on any implementation of
HMAC-DRBG that satisfies our functional specification. Therefore, our
functional specification can serve as a high-assurance reference.Comment: Appearing in CCS '1
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Using formal methods to support testing
Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent
years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing
Formalization and Validation of Safety-Critical Requirements
The validation of requirements is a fundamental step in the development
process of safety-critical systems. In safety critical applications such as
aerospace, avionics and railways, the use of formal methods is of paramount
importance both for requirements and for design validation. Nevertheless, while
for the verification of the design, many formal techniques have been conceived
and applied, the research on formal methods for requirements validation is not
yet mature. The main obstacles are that, on the one hand, the correctness of
requirements is not formally defined; on the other hand that the formalization
and the validation of the requirements usually demands a strong involvement of
domain experts. We report on a methodology and a series of techniques that we
developed for the formalization and validation of high-level requirements for
safety-critical applications. The main ingredients are a very expressive formal
language and automatic satisfiability procedures. The language combines
first-order, temporal, and hybrid logic. The satisfiability procedures are
based on model checking and satisfiability modulo theory. We applied this
technology within an industrial project to the validation of railways
requirements
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