Extended Kalman filter and adaptive backstepping for mean temperature control of a three‐way catalytic converter

This contribution is concerned with an adaptive control strategy for the mean temperature of an automotive three‐way catalytic converter. Tailored finite‐dimensional approximations of the complex infinite‐dimensional mathematical model of the catalytic converter serve as a basis for the design of an extended Kalman filter for state profile estimation and of an adaptive backstepping controller for the mean temperature. Although the model used for observer design relies on (semi‐)discretising the infinite‐dimensional model, a simple model for the mean temperature employing a phenomenological approach to describe the reaction heat is used for control design. The observer/controller is tested in simulation scenarios using a validated model of the three‐way catalytic converter. Copyright © 2013 John Wiley & Sons, Ltd.     

Collapse mechanisms of sandwich beams with composite faces and a foam core, loaded in three-point bending. Part I: analytical models and minimum weight design

Analytical predictions are made for the three-point bending collapse strength of sandwich beams with composite faces and polymer foam cores. Failure is by the competing modes of face sheet microbuckling, plastic shear of the core, and face sheet indentation beneath the loading rollers. Particular attention is paid to the development of an indentation model for elastic faces and an elastic–plastic core. Failure mechanism maps have been constructed to reveal the operative collapse mode as a function of geometry of sandwich beam, and minimum weight designs have been obtained as a function of an appropriate structural load index. It is shown that the optimal designs for composite–polymer foam sandwich beams are of comparable weight to sandwich beams with metallic faces and a metallic foam core.     

Plastic collapse of thin-walled frusta and egg-box material under shear and normal loading

The quasi-static plastic collapse of thin-walled frusta is determined for combined shear and out-of-plane compression. Experiments and finite element calculations are conducted on conical metallic frusta with semi-included cone angles of 30^ο and 45° to determine the shear collapse response. Additional finite element predictions are given for compressive loading, and for combined shear-compressive loading. The dependence of strength and energy absorption upon geometry is explored. The predicted response of an array of conical frusta is used to give the overall response of an egg-box material sandwiched between rigid face sheets. Scaling laws are determined for the stiffness and strength as a function of relative density of the egg-box material.     

Birefringence measurements of creep near an electrode tip in transparent PLZT

Birefringence measurements of time-dependent, creep polarization and strain were made in bulk ceramic samples of PLZT 8/65/35. Two specimen configurations were used: a fixed uniform electric field to measure the creep response and correlate birefringence with strain and polarization, and specimens with a partial surface electrode, to study the local behaviour near the tip of a surface electrode. At low values of electric displacement, the electric displacement depended upon the principal strain difference in a quadratic fashion whereas the birefringence varied linearly with the principal strain difference. Three distinct regimes of switching were identified, corresponding to the nucleation of ferroelectric domains, rapid switching and saturation in the process of domain growth. Finally it is shown that the birefringence measurements near an electrode tip give the spatial evolution of principal strain difference.     

Dаmреr with а pоrоus element fоr bearing arrangements

A solution to the problem of damper gain with a porous ring and compressible film of lubricant has been given. A feature of the solution is the combined assumption of a set of variable factors, which were previously only considered for particular cases.     

Hy:Con: A Strategic Tool For Balancing Hydropower Development And Conservation Needs

Hydropower (HP) is an important renewable energy source contributing 65.7% to Austria's national electricity generation. However, HP is also associated with ecosystem degradations jeopardizing the aims of the EU Water Framework Directive (WFD) and Habitats Directive. Based on the EU Renewable Energy Directive (RED), the Austrian Energy Strategy has defined goals to further increase HP production by 3.5 TWh until 2015. Because national strategies for HP development are widely missing, hydropower plants (HPPs) are planned and approved on a local and regional level, often neglecting the overall optimum for energy supply and ecology. Therefore, a decision support tool (Hy:Con) was developed to integrate the energy‐economic characteristics of planned HPPs and conservation needs of ecologically sensible river stretches. Based on 102 planned HPPs in Austria, Hy:Con identified HPPs with high economic attractiveness and low conservation concerns. The results show that owing to the already high HP exploitation in Austria, only a minor number of projects are without conservation conflicts. Upgrading of existing HPPs was associated with least ecological impacts, while HPPs with reservoirs are favoured over run‐of‐river plants. Cumulated ecological effects of numerous small HPPs are significant, whereas their contribution to overall energy production is comparatively small. Hy:Con represents a strategic instrument that can help decision makers to govern the implementation of the RED and WFD in a transparent way to pinpoint the limitations of future HP development and to avoid conflicts and stranded investments. © 2015 The Autors. River Research and Applications Published by John Wiley & Sons Ltd     

Zernike polynomials: a guide

In this paper we review a special set of orthonormal functions, namely Zernike polynomials which are widely used in representing the aberrations of optical systems. We give the recurrence relations, relationship to other special functions, as well as scaling and other properties of these important polynomials. Mathematica code for certain operations are given in the Appendix.     

Nd2O3-Doped Sialons with ZrO2/ZrN Additions Formed by Sintering and Hot Isostatic Pressing

β-sialon and Nd₂O₃-doped α-sialon materials of varying composition were prepared by sintering at 1775° and 1825°C and by glass-encapsulated hot isostatic pressing at 1700°C. Composites were also prepared by adding 2–20 wt% ZrO₂ (3 mol% Nd₂O₃) or 2–20 wt% ZrN to the β-sialon and α-sialon matrix, respectively. Neodymium was found to be a fairly poor α-sialon stabilizer even within the α-phase solid solution area, and addition of ZrN further inhibited the formation of the α-sialon phase. A decrease in Vickers hardness and an increase in toughness with increasing content of ZrO₂(Nd₂O₃) or ZrN were seen in both the HIPed β-sialon/ZrO₂(Nd₂O₃) composites and the HIPed Nd₂O₃-stabiIized α-sialons with ZrN additions.     

Four Studies on How Past and Current Suicidality Relate Even When "Everything But the Kitchen Sink" Is Covaried.

T. E. Joiner's (2004, in press) theory of suicidal behavior suggests that past suicidal behavior plays an important role in future suicidality. However, the mechanism by which this risk is transferred and the causal implications have not been well studied. The current study provides evaluation of the nature and limits of this relationship across 4 populations, with varying degrees of suicidal behavior. Across settings, age groups, and impairment levels, the association between past suicidal behavior and current suicidal symptoms held, even when controlling for strong covariates like hopelessness and symptoms of various Axis I and II syndromes. Results provide additional support for the importance of past suicidality as a substantive risk factor for later suicidal behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)