Sintering of α-alumina for highly transparent ceramic applications

In this paper we present our results on the sintering of α alumina ceramics by hot isostatic pressing. It describes a simple method for obtaining precise relative density values on our almost 100% dense samples. Then, transparency results are discussed with respect to grain size and residual porosity measurements, comparing them to scattering calculations. Our results are not far from the best reported transmission values: almost 60% for a 1 mm thick sample. The other 40% diffuse light comes from the birefringence of alumina for the most part. However, they are transparent enough to see detailed structures at several kilometers through them.     

Water hydraulic manipulator for fail safe and fault tolerant remote handling operations at ITER

Department of Intelligent Hydraulics and Automation (IHA) of Tampere University of Technology has been involved in the European Fusion program since 1994 within the ITER reactor maintenance activities. In this paper we discuss the design and development of a six degrees of freedom water hydraulic manipulator with a force feedback for teleoperation tasks. The manipulator is planned to be delivered to Divertor Test Platform 2 (DTP2) during year 2008. The paper also discusses the possibility to improve the fail safe and redundant operation of the manipulator. During the design of the water hydraulic manipulator, special provisions have been made in order to meet the safety requirements such as servo valve block for redundant operation and safety vane brakes for fail safe operation.     

Industrial Plant for Olive Mill Wastewater from Two-Phase Treatment by Chemical Oxidation

Olive-oil production generates high and variable amounts of wastewaters from the olives and olive-oil washing (OMW), resulting to great environmental impact. These waters are normally stored in large holding ponds for evaporation during the summer. The present study examines the chemical-oxidation process using ferric chloride catalyst for the activation of H2O2 (Fenton reaction). Tests have been made on an industrial scale. The final average value of chemical oxygen demand (COD) was close to 371?mg?O2?L?1 (%CODremoval = 86%, CODinitial = 2684?mg?O2?L?1), and the water produced can be used for irrigation or can be discharged directly into the municipal wastewater system for tertiary treatment.     

Root cause analysis during process development using Joint-Y PLS

The original purpose of the JYPLS model was to aid product transfer and scale-up. This work demonstrates that the JYPLS model is also well suited to analyze data from a process in development where the number and type of sensors and sensor locations are also being decided. The specific application in this case was to determine the root cause for a bias found during the development of a multivariate calibration model for a Near Infrared (NIR) instrument. The calibration model was built in parallel with the development of the manufacturing process itself. Each time the calibration model was tested with data from a new batch run, a non-explained bias was observed. Laboratory results on samples gathered from the process show that the NIR signal itself was biased and not the actual concentration of the constituent. Data on the processing conditions were collected for all the batches and included in the JYPLS model along with NIR and lab results. The loadings and scores from the JYPLS model were interpreted to isolate the root cause of the observed drift in the calibration model. This work discusses the general approach and presents the sequence of diagnostics used to analyze the different campaigns during process development. This should be applicable to other scenarios in process development where the data has the same architecture.     

Structural analysis and transistor properties of hetero-molecular bilayers

We examined the film morphologies and transistor properties of hetero-molecular bilayer consisting of N, N’-dioctyl-3, 4, 9, 10-perylenedicarboximide (PTCDI-C₈) and quaterrylene. First, the structure and carrier conduction of PTCDI-C₈ films were studied, followed by an analysis of the carrier accumulation process in a PTCDI-C₈/quaterrylene hetero-bilayer transistor. Based on the displacement current measurement (DCM), we stress the potential of the hetero-bilayer for tuning carrier accumulation like carrier doping techniques in field-effect transistors.     

On the efficient computation of robust regression estimators

The problem of providing efficient and reliable robust regression algorithms is considered. The impact of global optimization methods, such as stopping conditions and clustering techniques, in the calculation of robust regression estimators is investigated. The use of stopping conditions permits us to devise new algorithms that perform as well as the existing algorithms in less time and with adaptive algorithm parameters. Clustering global optimization is shown to be a general framework encompassing many of the existing algorithms.     

Model reduction by the Modal Identification Method in forced convection: Application to a heated flow over a backward-facing step

This numerical study focuses on the use of the Modal Identification Method to build reduced models for problems of heat convection and diffusion. The principle is to minimize a cost function based on the difference between the outputs (velocity and/or temperature) of a detailed model and the outputs of a reduced one. The reduced model structure is defined from the partial differential equations governing fluid mechanics and heat transfer in the physical system. In this paper, an advection–diffusion problem is studied: forced heat convection is considered with an incompressible, stationary, laminar 2D flow. Physical properties of the fluid are temperature independent, hence velocity is independent of temperature. The system under consideration is a channel flow over a backward-facing step with a time-varying heat flux density applied upstream of the step. Three types of reduced models have been investigated: steady fluid mechanics only, unsteady heat transfer for a given constant Reynolds number, and unsteady heat transfer for any constant Reynolds number within the range [100:800]. In this last case, the thermal reduced model is weakly coupled to the fluid reduced one. Results show that reduced models fit very well with detailed ones, and allow a large decrease of computing time.