不確かさをもつ非線形システムにおける適応ロバスト制御理論とその環境システムへの応用に関する研究

博甲第30号生命システム科学博士県立広島大

On synchronous and asynchronous monitor instrumentation for actor-based systems

We study the impact of synchronous and asynchronous monitoring instrumentation on runtime overheads in the context of a runtime verification framework for actor-based systems. We show that, in such a context, asynchronous monitoring incurs substantially lower overhead costs. We also show how, for certain properties that require synchronous monitoring, a hybrid approach can be used that ensures timely violation detections for the important events while, at the same time, incurring lower overhead costs that are closer to those of an asynchronous instrumentation.peer-reviewe

Evolution ofSh24 Neural Controllers for Autonomous Vision-Based Robots Dario Floreanoand Claudn Mattiussi

WedescrD e a set ofprj9MflHfiM2 experHD2 ts to evolve spikingneurfl contrH4434 for a vision-based mobilerb ot. All the evolutionar experH9j ts ar car4fl4 out on physicalri ots without human inter vention.After discussing how to implement and inter#flD theseneurHM with a physicalri ot, we show that evolution findsrdsHDfl ely quickly functional spiking contrH42M3 capable of navigating inir=#D9HfiM3 texturH envirj#M4 ts without hitting obstacles using a ver simple genetic encoding and fitness function.Neur ethological analysis of the networ activity let usunder4HfiD the functioning of evolved contrHDj3# and tell thereH9fl2 e imporH442 of single neureH independently oftheir obser ed firM2 rM2 Finally, a number of systematic lesion experHD= ts indicate that evolved spiking contrH4#3= ar ver r99j to synaptic strptic decay that typically occur inhar# ar implementations of spikingciringHM 1S1415 Neural Circuits The great majority of biological neurons communicate bysend2] pulses along the axons to other neurons. A pulse is a small current charge that occurs when the voltage potential across the membrane of a neuron exceed itsthreshold The pulse is also known as "spike" toind9=+V its shortand transient nature. After emitting a spike, a neuronneed some time to reestablish its electrochemical equilibriumand therefore cannotimmedzVS]] emit a new spike, no matter how strong its excitatory input is. A typical neuron in the cortex "fires" approximately 10 spikes persecond dcond restingcondg"=++ and can emit up to 300 spikes persecond in operatingcondg"z:49 Other neurons can fire more frequently (for example 500 spikes persecond" clustered in short period of time ("bursting neurons"). In thefield of artificial neural networks wefind twod=2S4S t classes of mod"+ that dat" with re..

SMASIS2010-3811 SPACE APPLICATION OF PIEZOELECTRIC WAFER ACTIVE SENSORS FOR STRUCTURAL HEALTH MONITORING

I. ABSTRACT Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive enablers for a large class of structural health monitoring (SHM) applications. This paper presents and discusses the challenges and opportunities related to the use of PWAS in the structures specific to space applications. The challenges posed by space structures are often different from those encountered in conventional structures. After a review of PWAS principles, the paper discusses the multi-physics power and energy transduction between structurally guided waves and PWAS; predictive modeling results using a simplified analytical approach are presented. Experimental results on space-like specimen structures are presented. Survivability of PWAS transducers under cryogenic space-like conditions are experimentally verified. The paper ends with conclusions and suggestions for further work. II. INTRODUCTION Structural health monitoring (SHM) is an emerging technology with multiple applications in the evaluation of critical structures. The goal of SHM research is to develop a monitoring methodology that is capable of detecting and identifying, with minimal human intervention, various damage types during the service life of the structure. Numerous approaches have been utilized in recent years to perform structural health monitoring; they can be broadly classified into two categories: passive methods and active methods. Passive SHM methods (such as acoustic emission, impact detection, strain measurement, etc.) have been studied longer and are relatively mature; however, they suffer from several drawbacks which limit their utility (need for continuous monitoring, indirect inference of damage existence, etc.). Active SHM methods are currently of greater interest due to their ability to interrogate a structure at will. One of the promising active SHM methods utilizes arrays of piezoelectric wafer active sensors (PWAS) bonded to a structure for both transmitting and receiving ultrasonic waves in order to achieve damage detection [1]. In thin-wall structures, PWAS are effective guided wave transducers by coupling their inplane motion with the guided wave particle motion on the material surface. The in-plane PWAS motion is excited by the applied oscillatory voltage through the d31 piezoelectric coupling. Optimum excitation and detection happens when the PWAS length is in certain ratios with the wavelength of the guided wave modes. The PWAS action as ultrasonic transducers is fundamentally different from that of conventional ultrasonic transducers. Conventional ultrasonic transducers act through surface tapping, i.e., by applying vibration pressure to the structural surface. The PWAS transducers act through surface pinching, and are strain coupled with the structural surface. This allows the PWAS transducers to have a greater efficiency in transmitting and receiving ultrasonic surface and guided waves when compared with the conventional ultrasonic transducers. The present paper presents and discusses the challenges and opportunities related to the use of PWAS in structures specific to space applications. The paper starts with a brief presentation of the challenges posed by space structures, which are often different from those encountered in conventional structures. Then, it reviews the principles of PWAS-based SHM. Subsequently, the paper discusses the analytical challenges of studying the multi-physics power and energy transduction between structurally guided waves and PWAS. Predictive modeling results using a simplified analytical approach are presented and discussed. Experimental results on using PWAS technology to detect damage in spacelike specimen structures are presented. The operability and survivability of PWAS transducers under cryogenic space-lik