Scouring at Bed Sills as a Response to Flash Floods

The temporal development of clear-water local scour depth at bed sills in uniform gravel beds is considered. Experiments are presented on the development of scour holes under unsteady hydraulic conditions, with the triangular-shaped hydrographs tested being of different durations and different rates of flow variation. Based on the experimental results and a theoretical framework, a method is given for the definition and prediction of the scouring process under unsteady flows in terms of a dimensionless temporal parameter. A “flash flood” is here defined as an event for which the scour doesn’t attain its potential magnitude, i.e., the equilibrium value for the peak hydrograph flow rate. This flood nature is dependent on both the characteristics of the flood event itself and the characteristics of the stream. A quantitative measure of what constitutes a flash flood is given in terms of the identified temporal parameter. Results show that the ratio between the final scour depth and the potential scour depth at a bed sill for a given hydrograph can be estimated as a function of the identified temporal parameter.     

A speed sensorless control based on a MRAS applied to a double fed induction machine drive

This paper proposes a new MRAS method to estimate the mechanical quantities in a double fed induction machine. In the traditional formulation the integral term, introduced by the PI MRAS regulator, is canceled in the transfer function between the estimated and the real speed. As a novelty, an additional term depending on the reference rotor flux through a constant gain g is introduced in the adjustable model of the MRAS. This innovation restores the integral term in the transfer function. As a consequence, during the closed loop operation, the estimated speed does not exhibit anymore a steady state error. The influence of the inverter non-linearities and of the non-linear rotor brush resistance on the speed estimation is also discussed. Some experimental tests validate the proposed method.     

Study of a proton exchange membrane fuel cells catalyst subjected to anodic operating conditions, by synchrotron-based scanning photoelectron microscopy (SPEM) and high lateral-resolution X-ray photoelectron spectroscopy

In this paper we report an investigation of the degradation of the Pt/C electrocatalyst of an anodic membrane-electrode assembly (MEA) after 1000 h of operation in a laboratory single-cell PEMFC, using synchrotron-based space-resolved photoelectron spectroscopy. This study is complemented by the analysis of a pristine MEA and reference materials, as well as by electrochemical measurements, SEM imaging and energy-dispersive X-ray fluorescence spectroscopy (EDX). Catalyst ageing correlates with a corrugation of morphology, as observed by SEM and scanning photoelectron microscopy (SPEM), corresponding to Pt nanoparticle agglomeration. Moreover - on the basis of high lateral resolution SPEM, X-ray photoelectron spectroscopy (XPS) and EDX analyses, - we found that, after operation, Pt is transported onto the fibres of the gas-diffusion layer (GDL). Space-resolved XPS shows a peak shift of the Pt 4f_7/2 level to higher and lower binding energies with respect to Pt(1 1 1) and pristine Pt black, respectively, corresponding to nanocrystallinity in the first case and agglomeration in the second one. No oxidised Pt was found in any location of the anodically used MEA.     

Nuclear reactor dynamics on-line estimation by Locally Recurrent Neural Networks

In this paper, the Causal Recursive Back-Propagation (CRBP) algorithm is employed to train on-line an Infinite Impulse Response–Locally Recurrent Neural Network (IIR–LRNN) for modelling the dynamics of a next-generation nuclear reactor. The results demonstrate the advantages of the on-line training over the batch-mode learning in the reconstruction of complex nonlinear dynamic relationships.     

Formulation optimisation of vegetable flour–loaded functional bread. Part II: effect of the flour hydration on the bread quality

In this work, the hydration process of durum wheat–based functional bread loaded with yellow pepper flour was optimised. In particular, the investigated vegetable flour and durum wheat semolina were mixed after they were separately hydrated. Three different amounts of water added to the yellow pepper flour were studied for assessing the effect of vegetable flour hydration level on the dough development and overall quality of bread. The bread formulation investigated in a previous work, based on 25% of yellow pepper and 2% of guar seed as structuring agent where the vegetable flour was directly added to the hydrated durum wheat semolina dough, was chosen as control sample. Results highlighted that dough samples with yellow pepper flour hydrated at highest water content showed a rheological behaviour similar to the durum wheat dough. Moreover, creep analysis showed that the sample added with no‐hydrated yellow pepper flour recorded the greatest resistance to deformation. Same results were obtained for the dough tensile and bread compression tests. The use of the hydrated yellow pepper flour also improved all sensorial attributes.     

E-recruiting and fairness: the applicant’s point of view

More and more companies currently recruit online, partly because of cost savings and competitive pressure, and partly because it is the best way to reach their target group of applicants. In our study, applicants’ perceptions of procedural fairness were examined in e-recruiting contexts. Using an adapted form of the Social Process Questionnaire on Selection, we found that 1,373 participants’ expectations regarding fairness were mediocre and always lower than the perceived importance of five procedural fairness aspects. Based on an experimental manipulation, we showed that feedback was particularly important in online application procedures, whereas participation had smaller effects. Furthermore, participants tend to rate procedural fairness for offline application procedures as fairer than for online procedures although they reported generally positive experiences with online applications in the past. Based on our results, we discuss practical implications and limitations.     

Co-doped willemite ceramic pigments: Technological behaviour,crystal structure and optical properties

Cobalt-doped willemite is a promising blue ceramic pigment, but some important aspects concerning crystal structure, optical properties and technological behaviour are still undisclosed. In order to get new insight on these features, willemite pigments (Zn_2?xCo_xSiO₄, 0 < x < 0.3) were synthesized by the ceramic route and characterized from the structural (XRPD with Rietveld refinement), optical (DRS and colorimetry), microstructural (SEM, STEM, TEM, EDX, EELS) and technological (simulation of the ceramic process) viewpoints. The incorporation of cobalt in the willemite lattice, taking preferentially place in the Zn1 tetrahedral site, induces an increase of unit-cell parameters, metal–oxygen distances, and inter-tetrahedral tilting. It causes shifting and enhanced splitting of spin-allowed bands of Co²⁺ in tetrahedral coordination, implying slight changes of crystal field strength Dq and Racah B parameter, but increasing spin-orbit coupling parameter λ. Willemite pigments impart deep blue hue to ceramic glazes and glassy coatings with a colouring performance better than commercial Co-bearing colorants in the 800–1200 °C range. Detailed SEM-TEM investigation and microanalysis proved that no diffusion phenomena occur at the pigment–glassy coating interface and that willemite pigments are chemically inert during firing at 1050 °C.     

Adaptive transform skipping for improved coding of motion compensated residuals

New generations of video compression algorithms, such as those included in the under development High Efficiency Video Coding (HEVC) standard, provide substantially higher compression compared to their ancestors. The gain is achieved by improved prediction of pixels, both within a frame and between frames. Novel coding tools that contribute to the gain provide highly uncorrelated prediction residuals for which classical frequency decomposition methods, such as the discrete cosine transform, may not be able to supply a compact representation with few significant coefficients. To further increase the compression gains, this paper proposes transform skip modes which allow skipping one or both 1-D constituent transforms (i.e., vertical and horizontal), which is more suitable for sparse residuals. The proposed transform skip mode is tested in the HEVC codec and is able to provide bitrate reductions of up to 10% at the same objective quality when compared with the application of 2-D block transforms only. Moreover, the proposed transform skip mode outperforms the full transform skip currently investigated for possible adoption in the HEVC standard.     

Relationship Between Chemical Markers and Sensory Score of Traditional Balsamic Vinegars Using a Screening Approach Combined with Rapid Assessment Methods

In this study, 200 samples of traditional balsamic vinegar (TBV) of Reggio-Emilia, a typical Italian “aged dressing” with Protected Denomination of Origin, were analyzed to model the relationship between sensory scores with some pre-selected compounds/parameters, such as Brix value, water activity (a _w), titratable acidity, color, polymeric compounds, and electronic nose signal. Statistical techniques, such as nonlinear regression and Principal Component Analysis (PCA) were used to model the relationship among vinegars composition. The sensory score of panelists was mainly correlated with Brix (r?=?0.85) followed by brown color at 445 nm (r?=?0.74) and water activity (a _w) (r?=??0.79), whereas the polymeric compounds content showed a negative correlation with water activity (r?=?–0.73). In particular, the water activity of TBVs at different Brix values followed a nonlinear trend with good fitting (r?=?0.857) with K?=?3.10 that was consistent with the value reported in the literature for fructose and glucose. Electronic nose (enose) data from TBVs and six marker compounds (acetic acid, butyric acid, vanillin, ethyl-phenylacetate, phenylethyl alcohol, and furfural) combined with PCA revealed a pattern related to the ageing of TBVs.