Passive mixing control for innovative air diffusion terminal devices for buildings

This paper presents an innovative concept for optimized air diffusion in buildings. The method uses passive control of air jet through lobed diffusers. An analysis is done experimentally at different scales for a lobed shaped geometry. A cross-shaped jet is characterized first through an isolated orifice and then at the scale of one perforated panel. An intermediary analysis of two coalescent and a row of cross-shaped jets is also proposed. All the results lead to the same conclusion. The lobed diffuser favors the self-induction compared to a reference conventional circular perforated diffuser. The air flow induced in the case of the lobed perforated panel is in average twice as the one of the circular perforated panel. Despite the consequent gain in air induction for the lobed perforated panel flow, the streamwise maximum velocities display comparable values in the far field which signifies comparable throws for the two flows. Consequently, the presented lobed perforated panel concept can be generalized to different type of diffusers to improve mixing ventilation in buildings.     

MALDI matrices for biomolecular analysis based on functionalized carbon nanomaterials

When used in small molar ratios of matrix to analyte, derivatized fullerenes and single wall nanotubes are shown to be efficient matrices for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The mixing of an acidic functionalized fullerene with a solution of bioanalyte, depositing a dried droplet, and irradiating with a pulsed nitrogen laser yields protonated or cationized molecular ions. Derivatized fullerenes could offer several advantages over conventional MALDI matrices: a high analyte ionization efficiency, a small molar ratios (less than 1) of matrix/analyte, and a broader optical absorption spectrum, which should obviate specific wavelength lasers for MALDI acquisitions. The major disadvantage to the use of fullerenes is the isobaric interference between matrix and analyte ions; however, it is overcome by using MALDI-ion mobility time-of-flight (IM-oTOF) mass spectrometry to preseparate carbon cluster ions from bioanalyte ions prior to TOF mass analysis. However, an alternative to the dried droplet preparation of fullerene MALDI samples is the aerosolization of matrix-analyte solutions (or slurries) followed by impacting the aerosol onto a stainless surface. We also demonstrate that the fullerene matrices can be used to acquire spectra from rat brain tissue.     

The Cognitive Interview: A meta-analytic review and study space analysis of the past 25 years.

The Cognitive Interview (CI) is a well-established protocol for interviewing witnesses. The current article presents a study space analysis of laboratory studies of the CI together with an empirical meta-analysis summarizing the past 25 years of research. The study space comprises 57 published articles (65 experiments) on the CI, providing an assessment of the boundary conditions underlying the analysis and application of this interview protocol. The current meta-analysis includes 46 published articles, including 20 articles published since the last meta-analysis conducted a decade earlier (K?hnken, Milne, Memon, & Bull, 1999). Reassuringly for practitioners, the findings of the original meta-analysis were replicated with a large and significant increase in correct details and a small increase in errors. In addition we found that there were no differences in the rate at which details are confabulated. Importantly, the effect sizes were unaffected by the inclusion of recent studies using modified versions of the CI. The CI appeared to benefit older adult witnesses even more than younger adults. We highlight trends and gaps in research and discuss how our findings can inform policy and training decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the "general acceptance" of eyewitness testimony research: A new survey of the experts.

In light of recent advances, this study updated a prior survey of eyewitness experts (S. M. Kassin, P. C. Ellsworth, & V. L. Smith, 1989). Sixty-four psychologists were asked about their courtroom experiences and opinions on 30 eyewitness phenomena. By an agreement rate of at least 80%, there was a strong consensus that the following phenomena are sufficiently reliable to present in court: the wording of questions, lineup instructions, confidence malleability, mug-shot-induced bias, postevent information, child witness suggestibility, attitudes and expectations, hypnotic suggestibility, alcoholic intoxication, the cross-race bias, weapon focus, the accuracy–confidence correlation, the forgetting curve, exposure time, presentation format, and unconscious transference. Results also indicate that these experts set high standards before agreeing to testify. Despite limitations, these results should help to shape expert testimony so that it more accurately represents opinions in the scientific community. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of a redox-modified clay mineral with respect to its suitability as a barrier in radioactive waste confinement

Engineered barriers for high-level nuclear waste (HLW) consist of excavated repositories in sub-surface rock formations where canisters holding the radionuclide are stored. Clay minerals, particularly the swelling 2:1 types, are used as backfill material, both in the canisters and in the bore hole, in order to prevent radionuclide transport to surrounding groundwater. One of the most important risks that can occur is the corrosion of the canister, which could be coupled with reduction of iron (Fe) in the clay structure. Such changes could greatly decrease the long-term stability of the clay and, consequently, of the barriers themselves. In order to test the potential effects of such redox interactions, an Fe-bearing clay mineral from a commercial source located in the Kutch region, India, was selected for study. This particular mineral is one of the candidate clay minerals to serve as such a barrier material, and is the one with the largest structural Fe content. Results from it should, therefore, provide maximum insight into the potential effects of redox interactions between the barrier and its surroundings. The unaltered clay was characterized by X-ray powder diffractometry (XRD), thermal gravimetric analysis (TGA/DTGA), Fourier-transform infrared (FTIR) spectroscopy, and variable-temperature Mössbauer spectroscopy. The chemically reduced and reoxidized forms of the clay were characterized by variable-temperature Mössbauer spectroscopy and chemical analysis. In the unaltered state the clay is comprised of smectite, maghemite, superparamagnetic goethite, and hematite, with a possible trace of kaolinite. In the reduced state the Fe (oxyhydr)oxides were dissolved. Upon reoxidation no six-line pattern was observed, indicating that the Fe remained only in the structure of the silicates. The final structure of the reduced–reoxidized clay contained more defects than the original clay, as revealed by greater quadrupole splitting values for structural Fe(III) in the clay. These findings indicate that upon exposure to natural redox cycles the Kutch clay could undergo permanent changes in its mineralogical composition and clay mineral structure, but further study is required to ascertain the effects that such changes would have on its long-term stability as a barrier material.     

Advanced Measures to Characterize Mechanical Properties of Refractories

The thermomechanical modelling method is becoming an important tool nowadays for the refractory researchers,suppliers and end-users. On one hand,applications focus on the post-mortem thermomechanical analysis to interpret the occurred failure phenomena of refractories in service. On the other hand,a priori investigation is very helpful for the design of refractory lining concepts before putting them into effect; as a result it will minimize the probability of refractory lining premature failure and save costs for the refractory suppliers as well as for the end-users. For both investigation routines,suitable material constitutive models and testing approaches are of relevance. Existing material constitutive models often used for refractories are the fictitious crack model acting for tensile failure,the Mohr-Coulomb or Drucker-Prager model describing shear failure,and the Norton-Bailey model representing creep. To characterize the tensile and shear failure of refractories at room temperature and elevated temperatures,a wedge splitting test and a modified shear test can be applied,respectively. The creep behavior and corresponding creep parameters of refractories can be determined with an appropriate creep testing device at elevated loads. The proper application of material constitutive models and testing approaches allows for improving the thermo-mechanical modelling and the optimization of the lining design.     

A comparison of three turbulence models for the prediction of parallel lobed jets in perforated panel optimization

The general context of the present study is the design of high induction HVAC air diffusers by means of passive jet control. When the diffuser is a perforated panel with lobed orifices (Meslem et al. 2010), the optimization of jet induction consists in improving the orifice’s geometry, the spacing between orifices and their arrangement on the panel. In this study, the flow field of a turbulent twin cross-shaped jet is investigated numerically using the standard k-ε model, the Shear Stress Transport (SST) k-ω model and the Reynolds Stress Model (RSM). The results are compared with PIV measurements. The objective is to assess their capability and limitations to predict the significant features of twin jet flow when the flow is numerically resolved through a lobed diffuser. It is shown that the k-ε and RSM models are more appropriate for predicting potential jet core length, the change in jet centreline streamwise velocity, and flow expansion in the symmetry plane of the twin jet flow. However, these models overestimate the overall flow expansion and the jet volumetric flow rate. The SST k-ω model seems more appropriate for the prediction of such dynamic integral quantities. A high level of turbulent kinetic energy predicted by the k-ε and RSM models in the near field of jets is probably the reason for this overestimation of jet induction. The SST k-ω model would appear to be the most appropriate tool for optimizing orifice design, orifice to orifice spacing and relative orifice orientation on a perforated panel diffuser.