Heat transfer in a recirculation zone at steady-state and oscillating conditions - the back facing step test case

Steady state and transient heat transfer is a very important aspect of any combustion process. To properly simulate gas to wall heat transfer in a turbulent flow, an accurate prediction of the flow and the thermal boundary layer is required. A typical gas turbine combustion chamber flow presents similarities with the academic backward facing step case, especially in the near wall regions where the heat transfer phenomena take place. For this reason, due to its simple geometry and the availability of well documented experiments, the backward facing step with wall heat transfer represents an interesting validation case. Results of steady-state and transient calculations with the use of various turbulence models are compared here with available experimental data

Artificial neural network for tilting pad journal bearing characterization

Tilting pad journal bearings (TPJBs) are modeled with Reynold-based models or computational fluid dynamics (CFD) approach. In both cases, the estimation of the dynamic coefficients of the oil-film forces and the static characteristic, can be computationally expensive and time consuming. Artificial Intelligence (AI) is assuming a key role in engineering but is rarely applied in fluid film bearing analysis. A properly trained Deep Learning (DL) model can perform very fast predictions of TPJB behavior with accuracy comparable to more time-consuming models. In this case, the main drawback is the time required to build the training dataset. In this work, an Artificial Neural Network (ANN) is trained to predict the dynamic stiffness and damping coefficients along with the main static quantities of TPJBs, such as minimum oil-film thickness and inlet flowrate. At first, a design of experiment is performed to build an appropriate training dataset. Secondly, a Reynolds-based thermo-hydrodynamic (THD) model is used to populate the training dataset and an appropriate test dataset. Then, a feedforward ANN is trained with Levenberg–Marquardt backpropagation and its architecture is optimized to increase accuracy. Finally, the accuracy of the ANN is tested using the test dataset and experimental data. The time and computational effort required by the ANN regression are much less than those required by the THD model. Therefore, the trained ANN is an effective and efficient tool for the characterization of TPJBs

A synthetic cytokinin primes photosynthetic and growth response in grapevine under ion-independent salinity stress

Aiding optimal plant–environment interaction would favor plant resilience against environmental constrains including salt stress. We test the hypothesis that 6-Benzylaminopurine (BAP) primes grapevine’s salt tolerance in vines (Vitis vinifera) received salt water (NaCl 100 mM) through the modulation of gene expression of BAP (AHK4, AHP1) and salt-stress (CAT, APX) inducible genes and morpho-physiological traits. A subgroup of vines had previously (48 h) been primed with BAP (80 mg/L) before salt stress. The gene expressions were 30% (CAT) and 56% (APX) lower in primed salt-stressed vines than that in un-primed. Salt treatment did not increase leaf Na+ but it lowered stomatal conductance (g s), photosynthesis (A), stem water potential (less negative) and photosystem-II efficiency (F v/F m). Chlorophyll-a concentrations were 30% higher in BAP-primed compared to un-primed. Adverse effects of salt were significantly reduced, maintaining high A/g s, F v/F m and growth. After the relief of the stress, the BAP primed vines had a fast recovery

The fusion approach – applications for understanding local government and European integration

The article explores the theoretical capabilities of the fusion approach as a conceptual ‘kit’ to explain the ‘bigger picture’ of European integration from a local government perspective. Fusion addresses the rationales and methods facilitating the transfer of policy-making competences to the European level. It understands European integration as a merging of public resources and policy instruments from multiple levels of government, whereby accountability and responsibilities for policy outcomes become blurred. The article argues that the fusion approach is useful to explain the systemic linkages between macro-trajectories and the corresponding change at the local level; the fusion dynamics of the local and European levels in a common policy-cycle; and the attitudes of local actors towards the EU. Although the article concludes that local government is rather modestly ‘fused’ into the EU, fusion approaches allow examining the extent to which the local level has become integrated into the European governance system

Why we need signed poetry in bilingual education

A truly bilingual and bicultural education for deaf children requires them to learn about the deaf art-form of sign language poetry. In this article I outline the advantages and challenges of doing this. Reviewing the scarce literature on teaching deaf children signed poetry, whether translated or original, I relate it to the use of literature in L2-learning settings. Reflections of deaf teacher-poets from the UK show that deaf children readily relate to signed poetry, and with informed language focus from teachers it helps them to develop a range of language skills, and express their emotions. Barriers to this, however, include lack of training and awareness for both deaf and hearing teachers - even when the teachers are poets

Absorption and distribution of etoricoxib in plasma, CSF, and wound tissue in patients following hip surgery—a pilot study

The perioperative administration of selective cyclooxygenase-2 (COX-2)-inhibitors to avoid postoperative pain is an attractive option: they show favorable gastro-intestinal tolerability, lack inhibition of blood coagulation, and carry a low risk of asthmatic attacks. The purpose of this study was to determine the cerebrospinal fluid (CSF), plasma, and tissue pharmacokinetics of orally administered etoricoxib and to compare it with effect data, i.e., COX-2-inhibition in patients after hip surgery. The study was performed in a blinded, randomized, parallel group design. A total of 12 adult patients were included who received 120 mg etoricoxib (n = 8) or placebo (n = 4) on day 1 post-surgery. Samples from plasma, CSF, and tissue exudates were collected over a period of 24 h post-dosing and analyzed for etoricoxib and prostaglandin E2 (PGE2) using liquid chromatography-tandem mass spectrometry and immuno-assay techniques. CSF area under the curve (AUC) [AUCs(O–24h)] for etoricoxib amounted to about 5% of the total AUC in plasma (range: 2–7%). Individual CSF lag times with respect to (50%) peak plasma concentration were ≤2 h in all but one case (median: 1 h). PGE2 production in tissue was significantly blocked by the COX-2 inhibitor starting with the appearance of etoricoxib in tissue and lasting for the whole observation period of 24 h (P < 0.01). In conclusion, etoricoxib reaches the CSF and site of surgery at effective concentrations and reduces PGE2 production at the presumed site of action

Local government in the 2013 constitution of Zimbabwe: Defining the boundaries of local autonomy

The 2013 Constitution of Zimbabwe recognises local government as the lowest tier of government in a three tier arrangement. Thus, local government, composed by urban and rural local authorities, now owes its existence directly to the Constitution and not to legislation as was the case under the previous constitutional order. The Constitution assigns to local authorities the responsibility to ‘manage’ and ‘represent’ the affairs of people in their respective areas. Every local authority is given the ‘right to govern’ its jurisdiction with ‘all’ the necessary powers to do so, including devolved powers. Thus, the Constitution recognises that, for the benefits associated with decentralisation to be realised, local authorities require a certain measure of local autonomy. The autonomy which this Constitution affords to local government is however unknown and unexplored, especially from a constitutional law point of view. In this article, we measure the degree of local autonomy guaranteed by the 2013 Constitution

Por que precisamos de poesia sinalizada em educação bilíngue

Uma verdadeira educação bilíngue e bicultural para crianças surdas requer que elas aprendam a forma de arte surda de poesia em língua de sinais. Neste artigo apresento as vantagens e desvantagens de se fazer isto. Revisando a escassa literatura sobre o ensino de poesia sinalizada para crianças surdas, seja traduzida ou original, eu a relaciono ao uso de literatura em cenários de aprendizagem de L2. Reflexões de professores-poetas surdos do Reino Unido mostram que a criança surda prontamente se simpatiza com a poesia sinalizada, e com o foco linguístico adequado dos professores, isto as ajuda a desenvolver uma gama de habilidades linguísticas e a expressar suas emoções. Barreiras para isto, contudo, incluem a falta de treinamento e apreensão de professores surdos e ouvintes - mesmo quando os professores são poetas

Investigation on Pivot Rolling Motion Effect on the Behavior of Rocker Back Tilting Pad Journal Bearings

The rolling motion of the pads with rocker back (RB) and ball and socket pivots is normally neglected in common software programs for the study of the rotor dynamic behavior of tilting pad journal bearings (TPJB). In other words, the theoretical contact point of the pivot is considered fixed. The aim of this work is to provide a novel way to implement in commercial software the effect of the variation of the circumferential coordinate of the theoretical contact point due to the pad rolling motion in RB TPJB. This is done by introducing an equivalent pivot rotational stiffness evaluated with an analytically derived formula, validated through finite element analysis. Such a stiffness is a function of the pad load and the radii of the contact pair, increasing with the load, the radii, and the degree of conformity of the contact. The static and dynamic characteristics of a five pad RB TPJB are then evaluated with a commercial software with and without the rotational stiffness contribution for two different pivot geometries. Non-negligible differences were found, particularly regarding the cross-coupled dynamic coefficients that show the higher sensitivity to the rotational stiffness. The inclusion of a pivot rotational stiffness among the data of commercial software for simulation of RB TPJB could contribute to fill the gap between numerical and experimental results