In this paper we show that, paradoxically, what looks like a “universal improvement” or a “straight-forward improvement” which enables better security and better reliability on a theoretical level, may in fact, within certain operational contexts, introduce new exposures and attacks, resulting in a weaker operational cryptosystem. We demonstrate a number of such dangerous “improvements”. This i...

This paper investigates the unknown input observability problem in the nonlinear case under the assumption that the unknown inputs are differentiable functions of time (up to a given order). The goal is not to design new observers but to provide simple analytic conditions in order to check the weak local observability of the state. The analysis starts by extending the observability rank conditi...

The controllability and the observability of fuzzy dynamical system are studied. The uncertainty of the fuzzy dynamical system is due to the initial condition. The available information on the uncertainty can be described via a membership function. In this paper, we propose a systematic approach to investigate the controllability and the observability of fuzzy dynamical system via the use of th...

This paper is concerned with the analysis of the observability of the discrete event systems (DES) modeled by interpreted Petri nets (IPN). This paper presents three major contributions on the field of the observability of DES. First, an observability definition for IPN is proposed. This definition is more precise than previous ones because it deals with the possibility of determining the syste...

The present paper extends some results recently developed for the analysis of observability in nonlinear dynamical systems. The aim of the paper is to address the problem of embedding an attractor using more than one observable. A multivariate nonlinear observability matrix is proposed which includes the monovariable nonlinear and linear observability matrices as particular cases. Using the dev...

Hybrid systems are powerful abstractions for modeling complex systems so that they have been used in a number of applications to provide models better reflecting the nature of control problems such as the ones related to embedded system design where discrete controls are routinely applied to continuous processes. Their theoretical properties are still the subject of intense research: in particu...

Abstract: In this paper we study the boundary observability estimate of time discrete Schrödinger equations in a bounded domain. By means of a time discrete version of the classical multiplier technique, we prove the uniform observability inequality of the solutions in an appropriate filtered space in which the high frequency components have been filtered. In this way, the well-known boundary o...

Five type II kerogens, shown by elemental analysis and Rock-Eval pyrolysis to represent a gradient of thermal maturity, were further characterized using a range of solid-state 13C NMR spectroscopic techniques. 13C cross polarization (CP) NMR spectra of the kerogens confirmed the well-established pattern of increasing aromaticity with increasing thermal maturity. Spin counting showed that CP obs...