Turbulent flame shape switching at conditions relevant for gas turbines

Abstract A numerical investigation is conducted in this work to shed light on the reasons leading to different flame configurations in gas turbine combustion chambers of aeronautical interest. Large eddy simulations (LES) with a flamelet-based combustion closure are employed for this purpose to simulate the DLR-AT Big Optical Single Sector (BOSS) rig fitted with a Rolls-Royce developmental lean burn injector. The reacting flow field downstream this injector is sensitive to the intricate turbulent-combustion interaction and exhibits two different configurations: (i) a penetrating central jet leading to an M-shape lifted flame; or (ii) a diverging jet leading to a V-shaped flame. First, the LES results are validated using available BOSS rig measurements, and comparisons show that the numerical approach used is consistent and works well. The turbulent-combustion interaction model terms and parameters are then varied systematically to assess the flame behavior. The influences observed are discussed in the paper from physical and modelling perspectives to develop physical understanding on the flame behavior in practical combustors for both scientific and design purposes.Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 686332

Analysis of agribusiness value chains servicing small-holder dairy farming communities in Punjab, Pakistan: three case studies

The agriculture sector in Pakistan, as in most developing countries, is dominated by smallholder producers. Pakistan has the world’s third largest dairy industry, and milk is efficiently collected and distributed chiefly by informal value chains that market the raw product with minimal cool chain infrastructure. Formal processors have a small market share of 5%. Interview data from farmers, milk collectors and consumers from three rural-urban case study value chains were analysed to study opportunities and challenges faced by the dairy industry. Compositional analysis of milk samples (n=84) collected along these chains identified the fact that in Pakistan informal milk chains provide a cheaper source of calories for the final consumer than industrialised milk chains (USD 0.12 compared USD 0.15 per 100 calories). These three chains created an estimated 4,872 jobs from farm to market and provided access to interest-free credit for the farmers. The existing government price setting mechanism at the retail end and collusion by large processors to set farm gate prices provided significant limitations to the profitability of small-holder farms providing the product. The absence of quality and quantity standards, amid the exchange of huge numbers of small volumes of milk along these chains, are major impediments to industry growth

Hybrid active focusing with adaptive dispersion for higher defect sensitivity in guided wave inspection of cylindrical structures

This is an Accepted Manuscript of an article published by Taylor & Francis in Nondestructive Testing and Evaluation on 23/11/2015, available online: https://www.tandfonline.com/doi/full/10.1080/10589759.2015.1093628.Ultrasonic guided wave inspection is widely used for scanning prismatic structures such as pipes for metal loss. Recent research has investigated focusing the sound energy into predetermined regions of a pipe in order to enhance the defect sensitivity. This paper presents an active focusing technique which is based on a combination of numerical simulation and time reversal concept. The proposed technique is empirically validated using a 3D laser vibrometry measurement of the focal spot. The defect sensitivity of the proposed technique is compared with conventional active focusing, time reversal focusing and synthetic focusing through an empirically validated finite element parametric study. Based on the results, the proposed technique achieves approximately 10 dB improvement of signal-to-coherent-noise ratio compared to the conventional active focusing and time reversal focusing. It is also demonstrated that the proposed technique to have an amplitude gain of around 5 dB over synthetic focusing for defects <0.5λs. The proposed technique is shown to have the potential to improve the reliably detectable flaw size in guided wave inspection from 9% to less than 1% cross-sectional area loss.TWI Ltd and the Center for Electronic System Research (CESR) of Brunel University

Hybrid active focusing with adaptive dispersion for higher defect sensitivity in guided wave inspection of cylindrical structures

This is an Accepted Manuscript of an article published by Taylor & Francis in Nondestructive Testing and Evaluation on 23/11/2015, available online: https://www.tandfonline.com/doi/full/10.1080/10589759.2015.1093628.Ultrasonic guided wave inspection is widely used for scanning prismatic structures such as pipes for metal loss. Recent research has investigated focusing the sound energy into predetermined regions of a pipe in order to enhance the defect sensitivity. This paper presents an active focusing technique which is based on a combination of numerical simulation and time reversal concept. The proposed technique is empirically validated using a 3D laser vibrometry measurement of the focal spot. The defect sensitivity of the proposed technique is compared with conventional active focusing, time reversal focusing and synthetic focusing through an empirically validated finite element parametric study. Based on the results, the proposed technique achieves approximately 10 dB improvement of signal-to-coherent-noise ratio compared to the conventional active focusing and time reversal focusing. It is also demonstrated that the proposed technique to have an amplitude gain of around 5 dB over synthetic focusing for defects <0.5λs. The proposed technique is shown to have the potential to improve the reliably detectable flaw size in guided wave inspection from 9% to less than 1% cross-sectional area loss.TWI Ltd and the Center for Electronic System Research (CESR) of Brunel University

Social assistance performance in Central and Eastern Europe: A pre-transfer post-transfer comparison

The anti-poverty impact of national social assistance programmes in eight Central and Eastern European countries is examined using data from the European Union-Survey of Income and Living Conditions (EU-SILC). Results indicate that social assistance programmes achieve only limited poverty reduction, while spending a significant amount of their resources on the non-poor. The more extensive and generous programmes achieve higher effectiveness in reducing poverty. Efficiency on the other hand appears to be linked only to programme size and not to benefit levels. Unlike Western Europe, no trade-off between effectiveness and efficiency could be detected

Energy Consumption Characterization and Reduction Strategies for Milling Machine Tool Use

Since machine tools are used extensively throughout their functional life and consequently consuming valuable natural resources and emitting harmful pollutants during this time, this study reviews strategies for characterizing and reducing the energy consumption of milling machine tools during their use. The power demanded by a micromachining center while cutting low carbon steel under varied material removal rates was measured to model the specific energy of the machine tool. Thereafter the power demanded was studied for cutting aluminum and polycarbonate work pieces for the purpose of comparing the difference in cutting power demand relative to that of steel

Atmospheric mixing ratios of methyl ethyl ketone (2-butanone) in tropical, boreal, temperate and marine environments

Methyl ethyl ketone (MEK) enters the atmosphere following direct emission from vegetation and anthropogenic activities, as well as being produced by the gas-phase oxidation of volatile organic compounds (VOCs) such as n-butane. This study presents the first overview of ambient MEK measurements at six different locations, characteristic of forested, urban and marine environments. In order to understand better the occurrence and behaviour of MEK in the atmosphere, we analyse diel cycles of MEK mixing ratios, vertical profiles, ecosystem flux data, and HYSPLIT back trajectories, and compare with co-measured VOCs. MEK measurements were primarily conducted with proton-transfer-reaction mass spectrometer (PTR-MS) instruments. Results from the sites under biogenic influence demonstrate that vegetation is an important source of MEK. The diel cycle of MEK follows that of ambient temperature and the forest structure plays an important role in air mixing. At such sites, a high correlation of MEK with acetone was observed (e.g. r2 = 0.96 for the SMEAR Estonia site in a remote hemiboreal forest in Tartumaa, Estonia, and r2 = 0.89 at the ATTO pristine tropical rainforest site in central Amazonia). Under polluted conditions, we observed strongly enhanced MEK mixing ratios. Overall, the MEK mixing ratios and flux data presented here indicate that both biogenic and anthropogenic sources contribute to its occurrence in the global atmosphere

Transcriptional regulation of the urokinase receptor (u-PAR) - A central molecule of invasion and metastasis

The phenomenon of tumor-associated proteolysis has been acknowledged as a decisive step in the progression of cancer. This short review focuses on the urokinase receptor (u-PAR), a central molecule involved in tumor-associated invasion and metastasis, and summarizes the transcriptional regulation of u-PAR. The urokinase receptor (u-PAR) is a heavily glycosylated cell surface protein and binds the serine protease urokinase specifically and with high affinity. It consists of three similar cysteine-rich repeats and is anchored to the cell membrane via a GPI-anchor. The u-PAR gene comprises 7 exons and is located on chromosome 19q13. Transcriptional activation of the u-PAR promoter region can be induced by binding of transcription factors (Sp1, AP-1, AP-2, NF-kappaB). One current study gives an example for transcriptional downregulation of u-PAR through a PEA3/ets transcriptional silencing element. Knowledge of the molecular regulation of this molecule in tumor cells could be very important for diagnosis and therapy in the near future