Characterisation of the Etching Quality in Micro-Electro-Mechanical Systems by Thermal Transient Methodology

Our paper presents a non-destructive thermal transient measurement method that is able to reveal differences even in the micron size range of MEMS structures. Devices of the same design can have differences in their sacrificial layers as consequence of the differences in their manufacturing processes e.g. different etching times. We have made simulations examining how the etching quality reflects in the thermal behaviour of devices. These simulations predicted change in the thermal behaviour of MEMS structures having differences in their sacrificial layers. The theory was tested with measurements of similar MEMS devices prepared with different etching times. In the measurements we used the T3Ster thermal transient tester equipment. The results show that deviations in the devices, as consequence of the different etching times, result in different temperature elevations and manifest also as shift in time in the relevant temperature transient curves.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Predicting operator workload during system design

A workload prediction methodology was developed in response to the need to measure workloads associated with operation of advanced aircraft. The application of the methodology will involve: (1) conducting mission/task analyses of critical mission segments and assigning estimates of workload for the sensory, cognitive, and psychomotor workload components of each task identified; (2) developing computer-based workload prediction models using the task analysis data; and (3) exercising the computer models to produce predictions of crew workload under varying automation and/or crew configurations. Critical issues include reliability and validity of workload predictors and selection of appropriate criterion measures

Adaptive finite element analysis based on p-convergence

The results of numerical experiments are presented in which a posteriori estimators of error in strain energy were examined on the basis of a typical problem in linear elastic fracture mechanics. Two estimators were found to give close upper and lower bounds for the strain energy error. The potential significance of this is that the same estimators may provide a suitable basis for adaptive redistribution of the degrees of freedom in finite element models

The Problem of Solving Fracture of the Denture Base in Preedentulous States

The mechanical fatigue resistance of the denture base seems to be a neglected part of treatment planning. Extreme overload can occur, which is only evaluated in the case of fracture. In full or partial edentia the dental base can be exposed to an extreme stress concentration which may be coupled with the incidental source of failure during processing of the denture. The aim of this lecture is to report cases, where we were able to overcome dental base fracture, which had not been foreseen earlier. In the first case a history of several fractures of an upper complete denture is presented. Metal net, framework and incorporation of glass fibres and reline were stages of the instructive problem solving process. In the second case a man wearing an overdenture with ball attachments under implant fixtures is presented. After multiple fractures of the dental base we used glass fibre reinforcement for repair. After this procedure there was an eventless period, which proves the mechanical resistance of the denture base. In the third case presented both the denture base and the acrylic tooth were damaged. The multiple fracture could also be treated with glass fibre reinforcement, which was successful. From these cases we concluded: 1. Careful case history and treatment plan could have helped to overcome the subsequent problems. 2. The clinical implication is that the glass fibre reinforcement can provide effective strength for the denture base. We could not neglect evaluation of the mucosa and bone support. In the following period we reinforced new dentures preventively with fibres in 15 cases. At the same time we also continued the repair the broken dentures of 10 patients. The outcome exceeded our greatest expectations: no fracture was seen. However, further study is needed to extend the observation period

The effect of quantization on the FCIQMC sign problem

The sign problem in Full Configuration Interaction Quantum Monte Carlo (FCIQMC) without annihilation can be understood as an instability of the psi-particle population to the ground state of the matrix obtained by making all off-diagonal elements of the Hamiltonian negative. Such a matrix, and hence the sign problem, is basis dependent. In this paper we discuss the properties of a physically important basis choice: first versus second quantization. For a given choice of single-particle orbitals, we identify the conditions under which the fermion sign problem in the second quantized basis of antisymmetric Slater determinants is identical to the sign problem in the first quantized basis of unsymmetrized Hartree products. We also show that, when the two differ, the fermion sign problem is always less severe in the second quantized basis. This supports the idea that FCIQMC, even in the absence of annihilation, improves the sign problem relative to first quantized methods. Finally, we point out some theoretically interesting classes of Hamiltonians where first and second quantized sign problems differ, and others where they do not.Comment: 4 pages w/ 2 page appendix, 2 figures, 1 tabl

Majority is not Needed: A Counterstrategy to Selfish Mining

In the last few years several papers investigated selfish mine attacks, most of which assumed that every miner that is not part of the selfish mine pool will continue to mine honestly. However, in reality, remaining honest is not always incentivized, particularly when another pool is employing selfish mining or other deviant strategies. In this work we explore the scenario in which a large enough pool capitalises on another selfish pool to gain 100\% of the profit and commit double spending attacks. We show that this counterstrategy can effectively counter any deviant strategy, and that even the possibility of it discourages other pools from implementing deviant strategies