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1. Dynamics of Gaussian and Super-Gaussian optical beams in weakly nonlinear nonlocal media

Author

A.J. Tsafack Tatsagoum, E. Tchomgo Felenou, Hermann T. Tchokouansi, A. Djazet, and A. Kenfack Jiotsa

Subjects
Nonlinear nonlocal media, Super-Gaussian beams, Variational method, Numerical Simulations, Physics, QC1-999
Abstract

We investigate the dynamics of Gaussian and Super-Gaussian optical beams in weakly nonlocal nonlinear media with cubic quintic nonlinearities. Through the variational method, a set of internal parameters of beam propagation are constructed and their properties, illustrated from numerical simulations. We discover that Gaussian and Super-Gaussian optical beams generally perform stable propagation with different dynamics depending on whether beams order, quintic nonlinearity and/or nonlocality are taken into account. The evolution of the light beams is periodic due to the competition between nonlinearities and diffraction. The phase front curvature increases with the beams order when the width decreases. The numerical study of the interaction between a Gaussian and Super-Gaussian optical beams, shows that with or without the quintic nonlinearity and/or nonlocality, various behaviours such as repulsion, attraction and soft shock waves are observed. Moreover, new phenomena are exhibited in the case of the Super-Gaussian, according to their shape.

Published
2023
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10. A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Author

Decking, W., Abeghyan, S., Abramian, P., Abramsky, A., Aguirre, A., Albrecht, C., Alou, P., Altarelli, M., Altmann, P., Amyan, K., Anashin, V., Apostolov, E., Appel, K., Auguste, D., Ayvazyan, V., Baark, S., Babies, F., Baboi, N., Bak, P., Balandin, V., Baldinger, R., Baranasic, B., Barbanotti, S., Belikov, O., Belokurov, V., Belova, L., Belyakov, V., Berry, S., Bertucci, M., Beutner, B., Block, A., Blöcher, M., Böckmann, T., Bohm, C., Böhnert, M., Bondar, V., Bondarchuk, E., Bonezzi, M., Borowiec, P., Bösch, C., Bösenberg, U., Bosotti, A., Böspflug, R., Bousonville, M., Boyd, E., Bozhko, Y., Brand, A., Branlard, J., Briechle, S., Brinker, F., Brinker, S., Brinkmann, R., Brockhauser, S., Brovko, O., Brück, H., Brüdgam, A., Butkowski, L., Büttner, T., Calero, J., Castro-Carballo, E., Cattalanotto, G., Charrier, J., Chen, J., Cherepenko, A., Cheskidov, V., Chiodini, M., Chong, A., Choroba, S., Chorowski, M., Churanov, D., Cichalewski, W., Clausen, M., Clement, W., Cloué, C., Cobos, J. A., Coppola, N., Cunis, S., Czuba, K., Czwalinna, M., D’Almagne, B., Dammann, J., Danared, H., de Zubiaurre Wagner, A., Delfs, A., Delfs, T., Dietrich, F., Dietrich, T., Dohlus, M., Dommach, M., Donat, A., Dong, X., Doynikov, N., Dressel, M., Duda, M., Duda, P., Eckoldt, H., Ehsan, W., Eidam, J., Eints, F., Engling, C., Englisch, U., Ermakov, A., Escherich, K., Eschke, J., Saldin, E., Faesing, M., Fallou, A., Felber, M., Fenner, M., Fernandes, B., Fernández, J. M., Feuker, S., Filippakopoulos, K., Floettmann, K., Fogel, V., Fontaine, M., Francés, A., Martin, I. Freijo, Freund, W., Freyermuth, T., Friedland, M., Fröhlich, L., Fusetti, M., Fydrych, J., Gallas, A., García, O., Garcia-Tabares, L., Geloni, G., Gerasimova, N., Gerth, C., Geßler, P., Gharibyan, V., Gloor, M., Głowinkowski, J., Goessel, A., Gołębiewski, Z., Golubeva, N., Grabowski, W., Graeff, W., Grebentsov, A., Grecki, M., Grevsmuehl, T., Gross, M., Grosse-Wortmann, U., Grünert, J., Grunewald, S., Grzegory, P., Feng, G., Guler, H., Gusev, G., Gutierrez, J. L., Hagge, L., Hamberg, M., Hanneken, R., Harms, E., Hartl, I., Hauberg, A., Hauf, S., Hauschildt, J., Hauser, J., Havlicek, J., Hedqvist, A., Heidbrook, N., Hellberg, F., Henning, D., Hensler, O., Hermann, T., Hidvégi, A., Hierholzer, M., Hintz, H., Hoffmann, F., Hoffmann, Markus, Hoffmann, Matthias, Holler, Y., Hüning, M., Ignatenko, A., Ilchen, M., Iluk, A., Iversen, J., Iversen, J., Izquierdo, M., Jachmann, L., Jardon, N., Jastrow, U., Jensch, K., Jensen, J., Jeżabek, M., Jidda, M., Jin, H., Johansson, N., Jonas, R., Kaabi, W., Kaefer, D., Kammering, R., Kapitza, H., Karabekyan, S., Karstensen, S., Kasprzak, K., Katalev, V., Keese, D., Keil, B., Kholopov, M., Killenberger, M., Kitaev, B., Klimchenko, Y., Klos, R., Knebel, L., Koch, A., Koepke, M., Köhler, S., Köhler, W., Kohlstrunk, N., Konopkova, Z., Konstantinov, A., Kook, W., Koprek, W., Körfer, M., Korth, O., Kosarev, A., Kosiński, K., Kostin, D., Kot, Y., Kotarba, A., Kozak, T., Kozak, V., Kramert, R., Krasilnikov, M., Krasnov, A., Krause, B., Kravchuk, L., Krebs, O., Kretschmer, R., Kreutzkamp, J., Kröplin, O., Krzysik, K., Kube, G., Kuehn, H., Kujala, N., Kulikov, V., Kuzminych, V., La Civita, D., Lacroix, M., Lamb, T., Lancetov, A., Larsson, M., Le Pinvidic, D., Lederer, S., Lensch, T., Lenz, D., Leuschner, A., Levenhagen, F., Li, Y., Liebing, J., Lilje, L., Limberg, T., Lipka, D., List, B., Liu, J., Liu, S., Lorbeer, B., Lorkiewicz, J., Lu, H. H., Ludwig, F., Machau, K., Maciocha, W., Madec, C., Magueur, C., Maiano, C., Maksimova, I., Malcher, K., Maltezopoulos, T., Mamoshkina, E., Manschwetus, B., Marcellini, F., Marinkovic, G., Martinez, T., Martirosyan, H., Maschmann, W., Maslov, M., Matheisen, A., Mavric, U., Meißner, J., Meissner, K., Messerschmidt, M., Meyners, N., Michalski, G., Michelato, P., Mildner, N., Moe, M., Moglia, F., Mohr, C., Mohr, S., Möller, W., Mommerz, M., Monaco, L., Montiel, C., Moretti, M., Morozov, I., Morozov, P., Mross, D., Mueller, J., Müller, C., Müller, J., Müller, K., Munilla, J., Münnich, A., Muratov, V., Napoly, O., Näser, B., Nefedov, N., Neumann, Reinhard, Neumann, Rudolf, Ngada, N., Noelle, D., Obier, F., Okunev, I., Oliver, J. A., Omet, M., Oppelt, A., Ottmar, A., Oublaid, M., Pagani, C., Paparella, R., Paramonov, V., Peitzmann, C., Penning, J., Perus, A., Peters, F., Petersen, B., Petrov, A., Petrov, I., Pfeiffer, S., Pflüger, J., Philipp, S., Pienaud, Y., Pierini, P., Pivovarov, S., Planas, M., Pławski, E., Pohl, M., Polinski, J., Popov, V., Prat, S., Prenting, J., Priebe, G., Pryschelski, H., Przygoda, K., Pyata, E., Racky, B., Rathjen, A., Ratuschni, W., Regnaud-Campderros, S., Rehlich, K., Reschke, D., Robson, C., Roever, J., Roggli, M., Rothenburg, J., Rusiński, E., Rybaniec, R., Sahling, H., Salmani, M., Samoylova, L., Sanzone, D., Saretzki, F., Sawlanski, O., Schaffran, J., Schlarb, H., Schlösser, M., Schlott, V., Schmidt, C., Schmidt-Foehre, F., Schmitz, M., Schmökel, M., Schnautz, T., Schneidmiller, E., Scholz, M., Schöneburg, B., Schultze, J., Schulz, C., Schwarz, A., Sekutowicz, J., Sellmann, D., Semenov, E., Serkez, S., Sertore, D., Shehzad, N., Shemarykin, P., Shi, L., Sienkiewicz, M., Sikora, D., Sikorski, M., Silenzi, A., Simon, C., Singer, W., Singer, X., Sinn, H., Sinram, K., Skvorodnev, N., Smirnow, P., Sommer, T., Sorokin, A., Stadler, M., Steckel, M., Steffen, B., Steinhau-Kühl, N., Stephan, F., Stodulski, M., Stolper, M., Sulimov, A., Susen, R., Świerblewski, J., Sydlo, C., Syresin, E., Sytchev, V., Szuba, J., Tesch, N., Thie, J., Thiebault, A., Tiedtke, K., Tischhauser, D., Tolkiehn, J., Tomin, S., Tonisch, F., Toral, F., Torbin, I., Trapp, A., Treyer, D., Trowitzsch, G., Trublet, T., Tschentscher, T., Ullrich, F., Vannoni, M., Varela, P., Varghese, G., Vashchenko, G., Vasic, M., Vazquez-Velez, C., Verguet, A., Vilcins-Czvitkovits, S., Villanueva, R., Visentin, B., Viti, M., Vogel, E., Volobuev, E., Wagner, R., Walker, N., Wamsat, T., Weddig, H., Weichert, G., Weise, H., Wenndorf, R., Werner, M., Wichmann, R., Wiebers, C., Wiencek, M., Wilksen, T., Will, I., Winkelmann, L., Winkowski, M., Wittenburg, K., Witzig, A., Wlk, P., Wohlenberg, T., Wojciechowski, M., Wolff-Fabris, F., Wrochna, G., Wrona, K., Yakopov, M., Yang, B., Yang, F., Yurkov, M., Zagorodnov, I., Zalden, P., Zavadtsev, A., Zavadtsev, D., Zhirnov, A., Zhukov, A., Ziemann, V., Zolotov, A., Zolotukhina, N., Zummack, F., and Zybin, D.

Published
2020
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15. Commissioning of the OPG1 plasma wind tunnel

Author

Chang, EWK, Schaefer, J, Valeinis, O, Buquet, M, and Hermann, T

Abstract

This work presents the commissioning of the new Osney Plasma Generator 1 (OPG1) plasma wind tunnel at the University of Oxford. The OPG1 facility is equipped with a thermal arc-jet plasma generator to supply high-enthalpy flows, replicating atmospheric re-entry environments. The small-scale and low operating cost of the arc-jet make it ideal for preliminary screening of material samples, testing new plasma diagnostics, and utilising it as a model pre-heating device. The paper outlines an overview of the facility and summarises the experimental results obtained during the facility commissioning, particularly regarding flow condition characterisation.

Published
2023

17. Development of small scale arc-jet facility OPG1

Author

Hermann, T, Chang, EWK, Schaefer, J, Joglekar, C, and Boehrk, H

Abstract

A small-scale thermal arc-jet facility based on a 21.5 kW tungsten inert gas welding power supply has been developed. The design and simulations are presented here. The plasma generator is situated inside a vacuum vessel forming an Argon plasma with a mass flow rate of approximately 0.2 g/s. The vessel is evacuated by a series of pumps providing sufficient suction to keep the vessel below 125 Pa during continuous operation. The system is designed with regards to heat transfer and vacuum performance with the goal of keeping component temperatures pressures below critical values to prevent material failure and enable adequate vacuum. The thermal design of the plasma generator includes a water cooling circuit which keeps the copper anode below melting temperatures. A viscous reacting 2D axisymmetric simulation is carried out using Eilmer4 simulating the nozzle flow including the stagnation chamber and the free jet impinging onto a 40mm diameter sphere-cone model. The simulations predict a maximum heat flux on the model surface of approximately 800 kW/m2 when a plasma total temperature of 7400 K is assumed.

Published
2023
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18. Integration of arc-jet in impulse facility for hypervelocity aerothermal testing with ablation

Author

Chang, EWK, Joglekar, C, McGilvray, M, and Hermann, T

Abstract

Arc-jets and impulse facilities have been extensively used to investigate the flow physics of planetary re-entry, but they each address different aspects of re-entry flow-fields. This work presents a conceptual design of a dual-facility setup, utilising an arc-jet as a model preheating device in the impulse test facility. This novel preheating apparatus will replicate realistic ablation coupling effects in hypervelocity flows. This paper outlines the major challenges and key considerations for the system integration of arc-jet in the T6 Stalker Tunnel. A small-scale arc-jet facility, OPG1, is currently being developed at the University of Oxford to test the plasma generator, model movement system, and sub-components for the expansion tube testing. Analyses were performed to examine the thermal and structural loads on the model movement system exposed to both plasma and hypervelocity flow. The results showcased that the model movement system will effectively serve dual-facility operations.

Published
2023
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19. Author Correction: A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Author

Decking, W., Abeghyan, S., Abramian, P., Abramsky, A., Aguirre, A., Albrecht, C., Alou, P., Altarelli, M., Altmann, P., Amyan, K., Anashin, V., Apostolov, E., Appel, K., Auguste, D., Ayvazyan, V., Baark, S., Babies, F., Baboi, N., Bak, P., Balandin, V., Baldinger, R., Baranasic, B., Barbanotti, S., Belikov, O., Belokurov, V., Belova, L., Belyakov, V., Berry, S., Bertucci, M., Beutner, B., Block, A., Blöcher, M., Böckmann, T., Bohm, C., Böhnert, M., Bondar, V., Bondarchuk, E., Bonezzi, M., Borowiec, P., Bösch, C., Bösenberg, U., Bosotti, A., Böspflug, R., Bousonville, M., Boyd, E., Bozhko, Y., Brand, A., Branlard, J., Briechle, S., Brinker, F., Brinker, S., Brinkmann, R., Brockhauser, S., Brovko, O., Brück, H., Brüdgam, A., Butkowski, L., Büttner, T., Calero, J., Castro-Carballo, E., Cattalanotto, G., Charrier, J., Chen, J., Cherepenko, A., Cheskidov, V., Chiodini, M., Chong, A., Choroba, S., Chorowski, M., Churanov, D., Cichalewski, W., Clausen, M., Clement, W., Cloué, C., Cobos, J. A., Coppola, N., Cunis, S., Czuba, K., Czwalinna, M., D’Almagne, B., Dammann, J., Danared, H., de Zubiaurre Wagner, A., Delfs, A., Delfs, T., Dietrich, F., Dietrich, T., Dohlus, M., Dommach, M., Donat, A., Dong, X., Doynikov, N., Dressel, M., Duda, M., Duda, P., Eckoldt, H., Ehsan, W., Eidam, J., Eints, F., Engling, C., Englisch, U., Ermakov, A., Escherich, K., Eschke, J., Saldin, E., Faesing, M., Fallou, A., Felber, M., Fenner, M., Fernandes, B., Fernández, J. M., Feuker, S., Filippakopoulos, K., Floettmann, K., Fogel, V., Fontaine, M., Francés, A., Martin, I. Freijo, Freund, W., Freyermuth, T., Friedland, M., Fröhlich, L., Fusetti, M., Fydrych, J., Gallas, A., García, O., Garcia-Tabares, L., Geloni, G., Gerasimova, N., Gerth, C., Geßler, P., Gharibyan, V., Gloor, M., Głowinkowski, J., Goessel, A., Gołębiewski, Z., Golubeva, N., Grabowski, W., Graeff, W., Grebentsov, A., Grecki, M., Grevsmuehl, T., Gross, M., Grosse-Wortmann, U., Grünert, J., Grunewald, S., Grzegory, P., Feng, G., Guler, H., Gusev, G., Gutierrez, J. L., Hagge, L., Hamberg, M., Hanneken, R., Harms, E., Hartl, I., Hauberg, A., Hauf, S., Hauschildt, J., Hauser, J., Havlicek, J., Hedqvist, A., Heidbrook, N., Hellberg, F., Henning, D., Hensler, O., Hermann, T., Hidvégi, A., Hierholzer, M., Hintz, H., Hoffmann, F., Hoffmann, Markus, Hoffmann, Matthias, Holler, Y., Hüning, M., Ignatenko, A., Ilchen, M., Iluk, A., Iversen, J., Iversen, J., Izquierdo, M., Jachmann, L., Jardon, N., Jastrow, U., Jensch, K., Jensen, J., Jeżabek, M., Jidda, M., Jin, H., Johansson, N., Jonas, R., Kaabi, W., Kaefer, D., Kammering, R., Kapitza, H., Karabekyan, S., Karstensen, S., Kasprzak, K., Katalev, V., Keese, D., Keil, B., Kholopov, M., Killenberger, M., Kitaev, B., Klimchenko, Y., Klos, R., Knebel, L., Koch, A., Koepke, M., Köhler, S., Köhler, W., Kohlstrunk, N., Konopkova, Z., Konstantinov, A., Kook, W., Koprek, W., Körfer, M., Korth, O., Kosarev, A., Kosiński, K., Kostin, D., Kot, Y., Kotarba, A., Kozak, T., Kozak, V., Kramert, R., Krasilnikov, M., Krasnov, A., Krause, B., Kravchuk, L., Krebs, O., Kretschmer, R., Kreutzkamp, J., Kröplin, O., Krzysik, K., Kube, G., Kuehn, H., Kujala, N., Kulikov, V., Kuzminych, V., La Civita, D., Lacroix, M., Lamb, T., Lancetov, A., Larsson, M., Le Pinvidic, D., Lederer, S., Lensch, T., Lenz, D., Leuschner, A., Levenhagen, F., Li, Y., Liebing, J., Lilje, L., Limberg, T., Lipka, D., List, B., Liu, J., Liu, S., Lorbeer, B., Lorkiewicz, J., Lu, H. H., Ludwig, F., Machau, K., Maciocha, W., Madec, C., Magueur, C., Maiano, C., Maksimova, I., Malcher, K., Maltezopoulos, T., Mamoshkina, E., Manschwetus, B., Marcellini, F., Marinkovic, G., Martinez, T., Martirosyan, H., Maschmann, W., Maslov, M., Matheisen, A., Mavric, U., Meißner, J., Meissner, K., Messerschmidt, M., Meyners, N., Michalski, G., Michelato, P., Mildner, N., Moe, M., Moglia, F., Mohr, C., Mohr, S., Möller, W., Mommerz, M., Monaco, L., Montiel, C., Moretti, M., Morozov, I., Morozov, P., Mross, D., Mueller, J., Müller, C., Müller, J., Müller, K., Munilla, J., Münnich, A., Muratov, V., Napoly, O., Näser, B., Nefedov, N., Neumann, Reinhard, Neumann, Rudolf, Ngada, N., Noelle, D., Obier, F., Okunev, I., Oliver, J. A., Omet, M., Oppelt, A., Ottmar, A., Oublaid, M., Pagani, C., Paparella, R., Paramonov, V., Peitzmann, C., Penning, J., Perus, A., Peters, F., Petersen, B., Petrov, A., Petrov, I., Pfeiffer, S., Pflüger, J., Philipp, S., Pienaud, Y., Pierini, P., Pivovarov, S., Planas, M., Pławski, E., Pohl, M., Polinski, J., Popov, V., Prat, S., Prenting, J., Priebe, G., Pryschelski, H., Przygoda, K., Pyata, E., Racky, B., Rathjen, A., Ratuschni, W., Regnaud-Campderros, S., Rehlich, K., Reschke, D., Robson, C., Roever, J., Roggli, M., Rothenburg, J., Rusiński, E., Rybaniec, R., Sahling, H., Salmani, M., Samoylova, L., Sanzone, D., Saretzki, F., Sawlanski, O., Schaffran, J., Schlarb, H., Schlösser, M., Schlott, V., Schmidt, C., Schmidt-Foehre, F., Schmitz, M., Schmökel, M., Schnautz, T., Schneidmiller, E., Scholz, M., Schöneburg, B., Schultze, J., Schulz, C., Schwarz, A., Sekutowicz, J., Sellmann, D., Semenov, E., Serkez, S., Sertore, D., Shehzad, N., Shemarykin, P., Shi, L., Sienkiewicz, M., Sikora, D., Sikorski, M., Silenzi, A., Simon, C., Singer, W., Singer, X., Sinn, H., Sinram, K., Skvorodnev, N., Smirnow, P., Sommer, T., Sorokin, A., Stadler, M., Steckel, M., Steffen, B., Steinhau-Kühl, N., Stephan, F., Stodulski, M., Stolper, M., Sulimov, A., Susen, R., Świerblewski, J., Sydlo, C., Syresin, E., Sytchev, V., Szuba, J., Tesch, N., Thie, J., Thiebault, A., Tiedtke, K., Tischhauser, D., Tolkiehn, J., Tomin, S., Tonisch, F., Toral, F., Torbin, I., Trapp, A., Treyer, D., Trowitzsch, G., Trublet, T., Tschentscher, T., Ullrich, F., Vannoni, M., Varela, P., Varghese, G., Vashchenko, G., Vasic, M., Vazquez-Velez, C., Verguet, A., Vilcins-Czvitkovits, S., Villanueva, R., Visentin, B., Viti, M., Vogel, E., Volobuev, E., Wagner, R., Walker, N., Wamsat, T., Weddig, H., Weichert, G., Weise, H., Wenndorf, R., Werner, M., Wichmann, R., Wiebers, C., Wiencek, M., Wilksen, T., Will, I., Winkelmann, L., Winkowski, M., Wittenburg, K., Witzig, A., Wlk, P., Wohlenberg, T., Wojciechowski, M., Wolff-Fabris, F., Wrochna, G., Wrona, K., Yakopov, M., Yang, B., Yang, F., Yurkov, M., Zagorodnov, I., Zalden, P., Zavadtsev, A., Zavadtsev, D., Zhirnov, A., Zhukov, A., Ziemann, V., Zolotov, A., Zolotukhina, N., Zummack, F., and Zybin, D.

Published
2020
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20. Transpiration-cooling heat transfer experiments in laminar and turbulent hypersonic flows

Author

Naved, I, Hermann, T, Hambidge, C, Ifti, HS, Falsetti, C, McGilvray, M, Tirichenko, IS, and Vandeperre, L

Subjects
Fluid Flow and Transfer Processes, Space and Planetary Science, Mechanical Engineering, Aerospace Engineering, Condensed Matter Physics
Abstract

The design of a transpiration-cooled system requires detailed local heat transfer information on and in the vicinity of the porous injector; however, limited spatially resolved experimental studies exist, particularly in hypersonic flows. In this work, experiments were conducted in the University of Oxford’s high-density tunnel at Mach 6.1 in both laminar and turbulent regimes. Spatially resolved two-dimensional surface heat transfer measurements were acquired by imaging directly on and downstream of two microporous transpiration-cooled injectors (METAPOR® CE170 and zirconia) using high-speed infrared thermography. Whereas injection in the laminar regime results in a steady, monotonic reduction in heat transfer from the start of the injector, a flatter profile is present for the turbulent cases where turbulent mixing inhibits surface heat transfer reduction. It was found that a modification to existing relations from film theory successfully correlates the streamwise heat transfer distribution on the injector for different blowing rates of nitrogen and helium. A key result is that helium performs much better than reported in previous experiments. Finally, the downstream thermal effectiveness is characterized for turbulent flows. A collapse of the thermal effectiveness is achieved and a modified analytical correlation proposed.

Published
2022

21. Quantifying the surface heat transfer on transpiration cooled porous materials in laminar and turbulent hypersonic boundary layers

Author

Naved, I, Hermann, T, Hambidge, C, Ifti, HS, McGilvray, M, Tirichenko, IS, and Vandeperre, L

Abstract

The design of a transpiration cooled system requires detailed local heat transfer information on and in the vicinity of the porous injector; however, limited spatially resolved experimental studies exist, particularly in hypersonic flows. In this work experiments were conducted on a flat plate model in the Oxford High Density Tunnel at Mach 6.1 in both laminar and turbulent regimes. Spatially resolved 2D surface heat transfer measurements were acquired by imaging directly on and downstream of two micro-porous transpiration cooled injectors (METAPOR CE170 and Zirconia) using high-speed infra-thermography. Whilst injection in the laminar regime results in a steady, monotonic reduction in heat transfer from the start of the injector, a flatter profile is present for the turbulent cases where turbulent mixing inhibits surface heat transfer reduction. It was found that a modification to existing relations from film theory successfully correlates the stream-wise heat transfer distribution on the injector for different blowing rates of Nitrogen and Helium injection. A key result is that Helium performs much better than reported in previous experiments for a turbulent boundary layer.

Published
2022

24. Recent advances in metal oxide-biochar composites for water and soil remediation: A review

Author

Hermann Tamaguelon Dzoujo, Victor Odhiambo Shikuku, Sylvain Tome, Aurelle Clandy Ntinkam Simo, Emily C. Ng'eno, Zachary M. Getenga, Marie Annie Etoh, and David Daniel Joh Dina

Subjects
Environmental applications, Functionalization, Physicochemical properties, Metal/biochar composites, Metal oxides, Technology
Abstract

During the last decades, biochar (BC) has proven to be an innovative candidate in various environmental applications. Nevertheless, the use of biochar in improving soil fertility, immobilizing contaminants and treating wastewater has presented many limitations. Nanomaterial technology has been used to improve the physicochemical properties of biochars, including emerging methods such as chemical precipitation, direct pyrolysis and impregnation of biochars with metals (Fe, Zn, Ce, Cu, Zr, Ti etc) or their oxides. This review discusses recent advancements on the potential, limitations, and prospects of using metal-biochar composites for wastewater treatments and soil remediation. Functionalization of biochar with metal oxides can exacerbate the specific surface area up to 98 %, and diminish the porosity structure up to 89 %. The performance of these metal-biochar composites, which depends on the raw material/precursor of the biochar, the identity of the metal/guest ion, the preparation conditions and the activation method, has shown that the removal rates for inorganic and organic contaminants in the aqueous phase vary from 80.5 to 100 % and from 52.90 to 100 % respectively and that the immobilization rates for heavy metals in soils vary from 16 to 100 %. Remediation mechanisms for various adsorbates in aqueous media and soils generally include electrostatic attraction, oxidation/reduction, complexation and precipitation. Life cycle assessment (LCA), pilot-scale, cost analysis, potential environmental risks, and machine learning modelling studies are found to be lacking for metal-biochar composites and provide areas for future research.

Published
2024
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29. Internet-based Land Valuation System Powered by a GIS of 1:10,000 Soil Maps.

Author

TÓTH, T., NÉMETH, T., FÁBIÁN, T., HERMANN, T., HORVÁTH, E., PATOCSKAI, Z., SPEISER, F., VINOGRADOV, SZ., and TÓTH, G.

Abstract

An internet-based land valuation system is being developed to replace the scientifically obsolete Hungarian land valuation system, the so-called AK ("Gold Crown") ratings. The new system is supported by a GIS and it is unique in its capability of providing an up-to-date index of soil quality and land value. The geographical information is provided by national map databases on genetic soil maps and soil attributes at the scale of 1:10.000, combined with cadastral maps, digital terrain model, topographic map, orthophotos of aerial photographs and agronomic field records. The automated algorithms are easy to update, can be made legally binding and can provide a transparent system for land taxation, calculation of subsidies, appropriation. Given that detailed (1:10,000 or finer) soil map coverage will be completed for all lands of Hungary (at date only 60% of the croplands have soil maps), this way a multifunctional system will be available that promotes an optimum use of land resources. The presented work was supported financially by the National Research and Development Programme (OM-4/015/2004 NKFP and GVOP (AKF) - 2004 - 3.1.1 grants). [ABSTRACT FROM AUTHOR]

Published
2022

30. Use of Soil Water Retention Capacity and Hydraulic Conductivity Estimation in the Preparation of Soil Water Management Maps.

Author

TÓTH, B., MAKÓ, A., RAJKAI, K., KELE, G. SZ., HERMANN, T., and MARTH, P.

Abstract

According to the Hungarian Soil Information and Monitoring System's (HSIMS) database a group estimation method was developed to predict the mean soil hydrophysical properties. The estimation efficiency of the worked out prediction procedures was controlled on a test database, and on a dataset of a study area. It can be established that the water retention and the hydraulic conductivity of soils are sufficiently predictable from the category data of soil maps. The 10-digit map codes of the PWW mapping method were created by different estimation methods, and as a result the PWW map was drawn. However, it is not always possible to estimate the necessary soil hydrophysical properties from the available map information for preparing the PWW map. Sometimes the knowledge gained from the field reports is needed as well. Further studies are planned for integrating these morphological information into our estimations. The present work was supported by the National Scientific Research Fund (OTKA) under grant No. T048302. [ABSTRACT FROM AUTHOR]

Published
2022

32. Conservation of migratory fishes in the Amazon basin

Author

Duponchelle, Fabrice, Isaac, V. J., Doria, C., Van Damme, P. A., Herrera, G. A., Anderson, E. P., Cruz, R. E. A., Hauser, M., Hermann, T. W., Agudelo, E., Bonilla-Castillo, C., Barthem, R., Freitas, C. E. C., Garcia-Davila, C., Garcia-Vasquez, A., Renno, Jean-François, and Castello, L.

Subjects
hydroelectric dams, threats, fisheries management, overexploitation, biodiversity, societal importance
Abstract

1. The Amazon basin hosts the Earth's highest diversity of freshwater fish. Fish species have adapted to the basin's size and seasonal dynamics by displaying a broad range of migratory behaviour, but they are under increasing threats; however, no study to date has assessed threats and conservation of Amazonian migratory fishes. 2. Here, the available knowledge on the diversity of migratory behaviour in Amazonian fishes is synthesized, including the geographical scales at which they occur, their drivers and timing, and life stage at which they are performed. 3. Migratory fishes are integral components of Amazonian society. They contribute about 93% (range 77-99%) of the fisheries landings in the basin, amounting to -US$436 million annually. 4. These valuable fish populations are mainly threatened by growing trends of overexploitation, deforestation, climate change, and hydroelectric dam development. Most Amazonian migratory fish have key ecological roles as apex predators, ecological engineers, or seed-dispersal species. Reducing their population sizes could induce cascading effects with implications for ecosystem stability and associated services. 5. Conserving Amazonian migratory fishes requires a broad portfolio of research, management, and conservation actions, within an ecosystem-based management framework at the basin scale. This would require trans-frontier coordination and recognition of the crucial importance of freshwater ecosystems and their connectivity. 6. Existing areas where fishing is allowed could be coupled with a chain of freshwater protected areas. Management of commercial and subsistence species also needs fisheries activities to be monitored in the Amazonian cities and in the floodplain communities to allow assessments of the status of target species, and the identification of management units or stocks. Ensuring that existing and future fisheries management rules are effective implies the voluntary participation of fishers, which can be achieved by increasing the effectiveness and coverage of adaptive community-based management schemes.

Published
2021

37. Enhanced mobilization of the bone marrow–derived circulating progenitor cells by intracoronary freshly isolated bone marrow cells transplantation in patients with acute myocardial infarction

Author

Turan, R. G., Bozdag-T, I., Turan, C. H., Ortak, J., Akin, I., Kische, S., Schneider, H., Rauchhaus, M., Rehders, T. C., Kleinfeldt, T., Belu, C., Amen, S., Hermann, T., Yokus, S., Brehm, M., Steiner, S., Chatterjee, T., Sahin, K., Nienaber, C. A., and Ince, H.

Published
2012
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42. Characterisation of internal heat transfer mechanisms in transpiring porous media using optical diagnostics

Author

Chakravarthy, K, Le Page, L, Hermann, T, Hermann, M, and Williams, B

Abstract

This paper presents a methodology to infer the internal heat transfer characteristics of a porous Ultra High Temperature Ceramic (UHTC) for use in transpiration cooling. Heated carbon dioxide (CO2 ) is effused through a porous zirconium diboride (ZrB2 ) sample into static atmosphere. Polariseddepolarised Rayleigh Scattering (PDRS) is used to obtain simultaneous planar composition and temperature distributions of the gas delivered above the sample. Surface temperature measurements are concurrently obtained using an infrared (IR) camera. The transient rise in temperature for both solid and fluid phases is then compared to a theoretical rise in temperature, obtained via an impulse response convolution method, allowing the evaluation of volumetric heat transfer coefficients. Gas properties above the UHTC porous sample were found to be uniform, as a result of its high porosity and small pore size. Heat transfer coefficients derived from both optical diagnostics were in good agreement, and supported existing results found in the literature for similar materials, with values ranging from 5.9 × 103 to 7.1 × 104 Wm−3K−1 for mass fluxes ranging from 133 to 400 gm−2 s −1 . Finally, the value of PDRS for future studies of designed large scale porosity materials is illustrated.

Published
2019

43. Studying the film effectiveness of transpiration cooled walls using pressure sensitive paint

Author

Ewenz Rocher, M, Hermann, T, McGilvray, M, Ifti, H, and Quinn, M

Abstract

This paper presents the performance of pressure sensitive paint (PSP) for the direct investigation of a transpiration cooled surface. This technique allows the quantification of the pressure distribution on a porous surface with blowing. Additionally, it can be used to detect where the coolant is on the surface, thus measuring the transport of molecular oxygen to a transpiration cooled surface. For highly turbulent flows, it can also be used to evaluate the film effectiveness. A porous aluminium sample was anodised and dip coated in a PSP luminophore solution. It was fitted into a flat plate model and exposed to a Mach 5 cross-flow in the Oxford High Density Tunnel. Tests were conducted with no coolant injection, air injection and with nitrogen injection at increasing blowing ratios. The film effectiveness of the transpiration cooled surface was obtained for several conditions at Re = 15.5 - 31.5 10^6/m and F = 0.001 - 0.002. The film effectiveness increases as the Reynolds number decreases and the blowing ratio increases, which is in good qualitative agreement with the literature. Furthermore, it shows the same features as a velocity map of the outflow.

Published
2019

44. Numerical simulation of transpiration cooling with a two-dimensional substructure

Author

Naved, I, McGilvray, M, and Hermann, T

Abstract

This paper presents a numerical model which assesses the coupled effect when transpiration cooling is applied to the external skin of a thermal protection system and the substructure of a high speed flight vehicle. The PIRATE transpiration cooling code has been extended and validated to account for quasi-two-dimensional lateral conduction effects allowing for analysis of more complex geometries. This enables very fast calculations of the two dimensional transient temperature response of a transpiration cooled thermal protection system, ideally suitable for large scale systems studies. To solve for the coupled transpiration cooled material and two-dimensional substructure, PIRATE has been coupled with the commercial finite element package COMSOL. This enables modelling of the longer term thermal effects of the integrated heat load over a flight trajectory. Transpiration cooling has been applied to a simplified blunt body model with an aluminium substructure. Results for the substructure temperature history for the Space Shuttle trajectory are obtained showing that transpiration cooling can lead to a 40% reduction in peak substructure temperature as well as a reduction in thermal stresses near the stagnation point.

Published
2019

48. Constructed wetland technology for the treatment and reuse of urban household greywater under conditions of Africa's Sahel region

Author

Cheik Omar Tidiane Compaoré, Ynoussa Maiga, Mahamadi Nikiéma, Oumarou Mien, Issa Nagalo, Hermann Tambila Panandtigri, James R. Mihelcic, and Aboubakar Sidiki Ouattara

Subjects
greywater reuse, pathogens, restrictive irrigation, sub-saharan africa, sustainable development goals, water scarcity, Water supply for domestic and industrial purposes, TD201-500, River, lake, and water-supply engineering (General), TC401-506
Abstract

Three pilot systems of a constructed wetland were assessed to advance the urban reuse of greywater for household gardening in areas of the world representative of Africa's Sahel (one unplanted and two planted with local species, namely Andropogon gayanus and Chrysopogon zizanioides). Principal component analysis showed planted systems provided higher removal efficiencies than the unplanted system and A. gayanus performed better for treating most water quality parameters. As expected, removal efficiencies for suspended solids (SS) and chemical oxygen demand (COD) were greater than 90% in all filters. The removal of five-day biochemical oxygen demand (BOD5) was, however, significantly greater in the filter planted with A. gayanus than in the unplanted control. For plant-beneficial parameters such as nutrients (NO3−, NO2−, NH4+, and PO43−), the removal in the planted filters was significantly higher than in the unplanted filter (>90% versus 73%–78%). The reduction of fecal coliforms was significantly greater in the two planted systems and exceeded 2.5 log10 removal. Analysis of the microbial water quality characteristics showed the concentration of fecal microbial indicators would achieve WHO guidelines for restricted irrigation with retention of some embedded nutrients, thus reducing pressures on areas experiencing climate variability, water scarcity, and land degradation. HIGHLIGHTS Planted filters produced treated greywater compliant with the WHO reuse guidelines for restricted irrigation.; Reduction of fecal coliforms was highest in the two planted systems, exceeding 2.5 log10 removal.; Filter planted with A. gayanus exhibited higher removal efficiencies of organic matter than the filter planted with C. zizanioides.; A. gayanus performed better than C. zizanioides for most water quality effluent parameters.;

Published
2023
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49. Human Resource Management across Generations within the Context of World of Work 4.0

Author

Renta Skýpalová, Hana Stojanová, Hermann Troger, and Zdeněk Caha

Subjects
generation cohort, the kruskal-wallis test, employee expectations, work environment., Technology (General), T1-995, Social sciences (General), H1-99
Abstract

The aim of the paper is to evaluate the expectations of cohorts of workers from Generations X, Y, and Z with regards to their perceptions of what a "good workplace" is. Two research questions were formulated accordingly. Respondents representing workers from Generations X, Y, and Z, from Italy and Austria, were asked to consider and rate (on a 1-5 scale) eighteen criteria on work environment and managerial approach. Multi-sample testing was applied during processing with the ANOVA and Shapiro-Wilk and the Kruskal-Wallis test was subsequently used for multi-sample testing. The findings show that the most popular criterion for all three generational cohorts is "good work atmosphere", followed by "all employees are valued, treated, and rewarded fairly". Interestingly, generational differences were observed for "customer orientation", which was more important for Generation X, and "autonomous organization of work (time)", which was more important for Generations Y and Z. The most surprising result was the significance of corporate image, with less than 4% identifying this as an important issue across all three generations. These findings can help human resource managers create appropriate working environments and motivational tools that meet the real expectations of employees. Doi: 10.28991/ESJ-2023-07-03-013 Full Text: PDF

Published
2023
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