Development of an Electrical Resistance Tomography Reactor for Pharmaceutical Processes

A review of tomography systems suitable for industrial implementation and design considerations for tomographic sensors has allowed the design of an ERT sensor compatible with stringent process requirements. In conjunction with a data acquisition system, ITS P2000, this sensor was applied to processes considered typical of Active Pharmaceutical Ingredients (API) chemical development. Experimental results are described where variations in conductivity measurements were monitored in a stirred tank. The data were compared with spectroscopic on‐line monitoring and kinetic information. The results obtained demonstrate that this approach shows promise for on‐line control of mixing process performance and efficiency evaluation and optimisation of reactor geometries.     

Transient 3D magnetic field simulations with combined space and time mesh adaptivity for lowest order whitney finite element formulations

Transient quasistatic magnetic fields are described by a degenerate parabolic initial?boundary value problems which can be considered as dynamical systems of non-linear differential?algebraic equations (DAE) of index 1. A common approach in established simulation tools for solving this problem is the method of lines where the space is adaptively discretised at the beginning of the simulation and then kept fixed within the adaptive time integration of the time-dependent equation. This approach, however, fails to take into account changes of the solution when eddy currents may appear or vanish depending on the external current excitation. Here, for this type of problem adaptive strategies in space and time are considered.     

The Reactions of Bromide with Ozone Towards Bromate and the Hypobromite Puzzle: A Density Functional Theory Study

Taking the solvent water into account, the energetics of the reactions of O₃ with Br^? leading to BrO₃ ^? have been calculated by Density Functional Theory at the B3LYP/6–311+G(d)/SCRF =COSMO level. Br^? reversibly forms an adduct, BrOOO^?, (ΔG?=?+6 kJ mol^?1) that decays spin allowed into BrO^? and O₂(¹Δ_g) (ΔG?=?+13 kJ mol^?1). BrO^? undergoes an oxidation to BrO₂ ^? and a reduction to Br^?. This may be accounted for if two different adducts, OBrOOO^? and BrOOOO^?, decay into BrO^? plus O₂ and Br^? plus 2 O₂. After cyclization, OBrOOO^? may also lead to Br^? plus 2 O₂.     

Suspended solids transport: an analysis based on turbidity measurements and event based fully calibrated hydrodynamic models.

Modelling suspended solids transport is a key issue for predicting the pollution load discharged by CSOs. Nonetheless, there is still much debate on the main drivers for suspended solids transport and on the modelling approach to be adopted. Current sewer models provide suspended solids transport models. These models, however, rely upon erosion-deposition criteria developed in fluvial environments, therewith oversimplifying the sewer sediment characteristics. Consequently, the performance of these models is poor from a theoretical point of view. To get an improved understanding of the temporal and spatial variations in suspended solids transport, a measuring network was installed in the sewer system of Loenen in conjunction with a hydraulic measuring network from June through December 2001. During the measuring period, 15 storm events rendered high-quality data on both the hydraulics and the turbidity. For each storm event, a hydrodynamic model was calibrated using the Clemens' method. The conclusion of the paper is that modelling of suspended solids transport has been and will be one of the challenges in the field of urban drainage modelling. A direct relation of either shear stress or flow velocity with turbidity could not be found, likely because of the time varying characteristics of the suspended solids.     

A new investigation of the system Ni–P

The binary system Ni–P is one of the constituents of the ternary system Ni–P–Sn which provides the basic knowledge for understanding the interactions between Sn-based solders and common Ni(P) metallization. In this study a new version of the Ni–P phase diagram was established based on XRD, EPMA and DTA measurements. The present diagram differs in some important details from the literature version. For the phases Ni₅P₂ high temperature (HT) and Ni₁₂P₅ HT the existence of a considerable homogeneity range is proposed. In Ni₅P₂ the transformation between HT and low temperature (LT) modification comprises a peritectic and a eutectoid reaction, whereas for the transition in Ni₁₂P₅ two eutectoids are proposed. Unfortunately, the high temperature phases cannot be stabilized by quenching, so that all data have to rely on the results of thermal analyses. Furthermore, Ni₅P₄ was found to be formed by a peritectic reaction, and a eutectic was observed between Ni₅P₄ and NiP. The phase NiP_1.22 that had been reported in the literature could not be found at all. Although the experimental work was complicated by the high vapor pressure of phosphorus at P concentrations higher than 40 at.% (which caused the explosion of quartz tubes and prevented the preparation of equilibrium samples at higher temperatures), it could still be shown that the phase NiP₃ is probably stable down to room temperature in contrast to the literature reports.     

Design,Processing, Microstructure,Properties, and Applications of Advanced Intermetallic TiAl Alloys

After almost three decades of intensive fundamental research and development activities, intermetallic titanium aluminides based on the ordered γ‐TiAl phase have found applications in automotive and aircraft engine industry. The advantages of this class of innovative high‐temperature materials are their low density and their good strength and creep properties up to 750 °C as well as their good oxidation and burn resistance. Advanced TiAl alloys are complex multi‐phase alloys which can be processed by ingot or powder metallurgy as well as precision casting methods. Each process leads to specific microstructures which can be altered and optimized by thermo‐mechanical processing and/or subsequent heat treatments. The background of these heat treatments is at least twofold, i.e., concurrent increase of ductility at room temperature and creep strength at elevated temperature. This review gives a general survey of engineering γ‐TiAl based alloys, but concentrates on β‐solidifying γ‐TiAl based alloys which show excellent hot‐workability and balanced mechanical properties when subjected to adapted heat treatments. The content of this paper comprises alloy design strategies, progress in processing, evolution of microstructure, mechanical properties as well as application‐oriented aspects, but also shows how sophisticated ex situ and in situ methods can be employed to establish phase diagrams and to investigate the evolution of the micro‐ and nanostructure during hot‐working and subsequent heat treatments.     

Effects of rheology on the interface of Pb(Zr,Ti)O3 monofilament composites obtained by co-extrusion

The production of lead zirconate titanate (PZT) fibres, 1-3, 3-1 and 2-2 composites for actuator and sensor applications through the thermoplastic co-extrusion process can be achieved by using a macro-scale preform shaped by two different extrudable mixtures. The main challenge of this method is the optimization of materials that can be co-extruded and at the same time maintain the preform geometry in the final product, without axial and cross-sectional deformation. In this work, rheological characterizations of PZT/polyethylene and carbon black/polyethylene feedstocks were carried out to produce monofilament composites by the co-extrusion process. To explore the interface instabilities resulting from the viscosity mismatch between the processed materials, the co-extrusion tests were performed varying the velocity of the piston during extrusion. Successful co-extrusion, with well preserved fibre morphologies and defined interface between the co-extruded materials, was achieved for viscosity ratios between the feedstocks ranging from 0.98 to 1.16. Outside of this range, interface distortions were observed.     

Performance assessment of an integrated free cooling and solar powered single-effect lithium bromide-water absorption chiller

In this study, performance assessment of an integrated cooling plant having both free cooling system and solar powered single-effect lithium bromide–water absorption chiller in operation since August 2002 in Oberhausen, Germany, was performed. A floor space of 270 m² is air-conditioned by the plant. The plant includes 35.17 kW cooling (10-RT) absorption chiller, vacuum tube collectors’ aperture area of 108 m², hot water storage capacity of 6.8 m³, cold water storage capacity of 1.5 m³ and a 134 kW cooling tower. The results show that free cooling in some cooling months can be up to 70% while it is about 25% during the 5 years period of the plant operation. For sunny clear sky days with equal incident solar radiation, the daily solar heat fraction ranged from 0.33 to 0.41, collectors’ field efficiency ranged from 0.352 to 0.492 and chiller COP varies from 0.37 to 0.81, respectively. The monthly average value of solar heat fraction varies from 31.1% up to 100% and the five years average value of about 60%. The monthly average collectors’ field efficiency value varies from 34.1% up 41.8% and the five-year average value amounts about 28.3%. Based on the obtained results, the specific collector area is 4.23 (m²/kW_cold) and the solar energy system support of the institute heating system for the duration from August 2002 to November 2007 is 8124 kWh.     

Characteristics of the tensile flow behavior of Ti–46Al–9Nb sheet material – Analysis of thermally activated processes of plastic deformation

Flow behavior, strain hardening and activation parameters, i.e. activation volume, stress exponents and normalized free enthalpy of activation, of Ti–46Al–9Nb sheet with near-gamma microstructure have been investigated in tension tests between 700 and 1000 °C. The dependence of yield stress on temperature and strain rate, the course of the strain hardening curves and the values of activation parameters show that thermally activated dislocation mechanisms are mainly involved in the tensile deformation process of the investigated material. At constant temperature the value of the activation volume depends both on plastic strain and strain rate. The activation volume generally decreases with increasing strain. The decrease is particularly well observable for higher strain rates, thus indicating a growing role of thermally activated climb mechanisms governing the process of dynamic recovery. The activation volume calculated for a constant plastic strain (2% in case of this study) is a function of temperature and strain rate. At lower deformation rates, or alternatively at higher temperatures, the activation volume increases. Such behavior indicates a decrease in dislocation density due to the onset of dynamic recrystallization. The analysis of stress exponents and the obtained free enthalpy of activation confirm that different thermally activated processes are acting during deformation under the tensile test conditions studied.