Analogue Mixed Signal Test Development – Continuous Improvement Exercise in Quality, Reliability, and Reduction in Test Cost of Semiconductor Devices

学位記番号：理工博乙11

Towards an automatic approach for hardware verification according to ISO 26262 functional safety standard

The Failure Mode, Effect and Diagnostic Analysis (FMEDA) is a technique widely adopted by automotive industry to assess the level of reliability of hardware designs. Although very useful, it has the problem of taking a long time to complete and requires experts with extensive knowledge of the circuit under consideration. In this paper, it is presented a comparison between the analysis results obtained from an automatic tool developed by the authors with respect to the ones obtained by hand from a team of experts, followed by a critical review of the strengths and weaknesses, about the rules for automatic classification of the faults effects

An automatic approach to perform the verification of hardware designs according to the ISO26262 functional safety standard

With the increasing adoption of embedded systems in critical automotive applications, the verification of hardware designs reliability is becoming a strictly regulated process where the ISO26262 standard plays a key role. Today crucial verification activities such as failure analysis and FMEA are still relying heavily on reliability engineer expertise, as automatic methods supporting them are still lacking. In this paper, we introduce a novel approach that allows to automatically perform failure analysis considering the hardware schematic of the item under analysis, or safety-element-out-of-context, and a behavioral model of the software the hardware executes. An automotive case study is presented to illustrate the approach, and some preliminary results are discussed

Time-averaged paleomagnetic field and secular variation: predictions from dynamo solutions based on lower mantle seismic tomography

We compare three dynamo solutions incorporating laterally varying boundary heat flux with paleomagnetic models and data. The boundary condition is defined by the D seismic shear-wave velocity and the three solutions have boundary anomalies with different amplitudes. The generated fields appear to divide into a stationary, boundary-locked part and a time-varying part with persistent centres of activity. Both parts contribute to the time average. A very long averaging time can be needed for nearly-locked solutions, but a rough time average that remains within the threshold set by the accuracy of paleomagnetic data is achieved in a fewdiffusion times. The locked part dominates for larger amplitude boundary anomalies. In previous work the locked field was shown to have strong similarities with the modern geomagnetic field. Previous dynamo solutions that were not locked to the boundary show similarities with our solutions with weak boundary forcing. The axisymmetric time average has small g0 2 and larger g0 3 components and peaks in inclination anomaly in high latitudes (associated with the locked field) and low latitudes (associated with the time average of the time-varying fields). The non-axisymmetric time average displays a striking longitudinal variation in inclination anomaly, with a large negative anomaly in the Pacific region in agreement with observations. None of the dominant geomagnetic coefficients are axisymmetric and g0 2 negligible in all three models. Secular variation is concentrated in equatorial latitudes, as in some recent paleomagnetic models. The locked field agrees with the inclination difference found between Hawai’i and Réunion, in agreement with paleomagnetic averages. The locked field agrees with the paleomagnetic time average rather better than the fields with less boundary variations.We conclude that, because the locked field agrees with the modern field aswell as some aspects of the long-term time average, the geomagnetic field spends a considerable time in the present four-lobe configuration: it is not a coincidence that the present field resembles the time average. Longitudinal variations are likely to be at least as important as latitudinal variations in the paleomagnetic time average. This presents a challenge for dynamo theory, since a move to more geophysically realistic parameters would appear to destroy the locked solutions