Bromate Ion Formation: Impact of Ozone Contactor Hydraulics And Operating Conditions

This paper presents a simplified kinetic reaction rate model which enables the evaluation of various contactor hydraulics on bromate ion formation. Two extreme reactor types are presented: completely stirred tank (CSTR) and plug flow reactors (PFR). The kinetic modeling has been based on reactions and rate constants for molecular ozone mechanisms. At this stage, the work presented does not take into account the formation and reaction of hydroxyl radicals in the reaction pathway. However, for further in-depth modeling consideration, it is questionable that no hydroxyl radicals are formed. Similar bromate ion levels were predicted with a PFR and a CSTR for similar operating conditions in the case of predominantly molecular ozone reactions. However in most cases, a CSTR will require a much higher Cτ (product of the residual ozone concentration and the hydraulic residence time) than a plug flow reactor in order to achieve similar treated water quality goals.     

Structure and thermal stability of zinc–nickel electrodeposits

ZnNi alloys were electrodeposited from a chloride bath on steel substrates. The effect of nickel bath concentration on chemical composition, structure and microstructure of the deposits is demonstrated. From 0 to 13 nickel, the phases obtained do not correspond to that reported on the thermodynamic phase diagram. It is shown that the substitution of zinc by nickel is responsible for the formation of distorted _d and _d phases corresponding to the supersaturated hexagonal phase of zinc and to the unsaturated cubic phase of Zn–Ni alloy, respectively. Differential scanning calorimetry indicates that the thermal instability of the alloys containing up to 13 wt of nickel, results from the crystallization of the phase from the _d and _d phases at around 200 °C and 250 °C, respectively.     

A passivity-based controller for coordination of converters in a fuel cell system

The problem of converters coordination of a fuel cell system involving a hydrogen fuel cell with super-capacitors for applications with high instantaneous dynamic power is addressed in this paper. The problem is solved by using a non-linear controller based on passivity. The controller design is based on the interconnection and damping assignment approach, where the proof of the local system stability of the whole closed-loop system is shown. Simulation and experimental results on a reduced scale system prove the feasibility of the proposed approach for a real electrical vehicle.     

Experimental results and analytical film thickness predictions in EHD rolling point contacts

In this work, we consider several types of lubricants—including non-Newtonian fluids—that were studied in EHD pure rolling point contacts under various operating conditions, leading us to explore a wide range of dimensionless parameters. The experimental results are compared with predictions given by the usual analytical EHL relationships and by more recently developed models. This broad comparison conducted with particular emphasis on minimum film thickness (h_m) showed a fair agreement between experimental data and a few predictions including some obtained from extended models. Commonly used elastohydrodynamic lubrication (EHL) models did not systematically give accurate h_m estimation, whereas minimum film thickness not only is a yield value but also serves as a key parameter in estimating lubrication regimes.     

Static thermal conductivity methods for solid materials

Various experimental arrangements for the determination of steady-state thermal conductivities, as adopted for different situations, are reviewed. The case where the sample geometry and dimensions are imposed is treated distinctly from that where they may be chosen by the experimenter. In the latter case, it is shown that the set-up adopted may vary significantly according to the magnitude of the conductivity, the temperature range investigated, the geometry, and the dimensions of the samples available. Some devices which were recently developed in the author's laboratory are taken as illustrative examples and briefly discussed.     

Shear force microscopy with a nanoscale resolution

This paper presents a shear force microscope having a nanometric resolution at high scan rates. Current techniques were reviewed and tested, and a design based on the use of a tuning fork is described. The use of a low quality factor enabled us to decrease the response time and increase the stability of the tracking. The microscope was coupled with a tunneling current detection, in order to study the interactions between the sample and the probe during scanning. As an example, a sharp nickel nanotip was used to image a gold surface, showing details down to a few nanometers, even at scanning rates of 4Hz.     

Nickel pigmented anodized aluminium as solar selective absorbers

The effect of various impregnation parameters on the structural features and optical properties of solar absorbing nickel pigmented anodic alumina coatings has been studied. The impregnation starts from a threshold voltage. A correlation between microstructural features and the optical properties of these coatings has been established. Stable coating with low emissivity (0.14 at 70°C) and high solar absorptivity (>0.90) have been prepared by anodizing in a phosphoric acid solution.     

Natural faecal fluorophores and the potential of chlorophyll based markers to optimise fluorescence as a real-time solution for the detection of faecal contamination on carcasses

More accurate and sensitive visualisation of faecal contamination in the abattoir would significantly reduce the risk posed by harbouring pathogenic micro-organisms. We carried out a preliminary investigation of the range of fluorophores found naturally in faeces from typical ruminant diets. Sixteen ewes were offered either: i) fresh forage (FF), ii) grass silage (GS), iii) grass hay (GH) or iv) concentrate and barley straw (CB). Animals offered FF diets had a greater concentration (P < 0.001) of chlorophyll based compounds in their faeces and subsequent fluorescent emission spectra. In a second experiment we investigated a range of fluorescent markers against a basal concentrate and barley straw diet. Ten Cheviot sheep were split into five treatment groups during a duplicate 5 × 5 Latin square design. Four of the groups received a chlorophyll based marker at a rate of 2 g/d: i) Mg–Chlorophyllin (MgC), ii) Fe–Chlorophyllin (FeC), iii) Zn–Chlorophyllin (ZnC) or iv) Spirulina (Chlorophyll a extract from blue green algae, Sp). The last group received no supplement as the control (Con). The appearance of chlorophyllin markers and their derivatives in faeces was similar with mean concentrations of 3.1 and 7.2 μg/g DM, respectively. The most intense fluorescent signal was shown with MgC followed by ZnC, FeC, Sp and Con at 685 nm. The use of markers in pre-slaughter diets would improve the accuracy of faecal detection as a result of greater fluorescence and specific emission wavelengths which do not overlap with natural meat components to help with visualisation.     

Sequential environmental stresses tests qualification for automotive components

The purpose is to create a new qualification methodology for plastic encapsulated electronic components used in an automotive environment at high temperature. It is based on the acceleration of failure mechanisms like ball bond lift (due to intermetallic Au–Al thickness growth), by combination of environmental stresses. The delamination measurement was used as an indicator of potential assembly weaknesses. An optimized package sequential qualification test flow is proposed.