@article{MTMT:34742505, title = {Statistical assessment of the concentration fluctuations in street canyons via time-resolved wind tunnel experiments}, url = {https://m2.mtmt.hu/api/publication/34742505}, author = {Papp, Bálint and Istók, Balázs and Koren, Márton and Balczó, Márton and Kristóf, Gergely}, doi = {10.1016/j.jweia.2024.105665}, journal-iso = {J WIND ENG IND AEROD}, journal = {JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS}, volume = {246}, unique-id = {34742505}, issn = {0167-6105}, abstract = {Time-resolved wind tunnel experiments are performed for three periodic street canyon configurations: one of uniform (H/W = 1) and two of variable building height (consisting of 0.5H and 1.5H tall towers in aligned and staggered arrangements) for perpendicular wind direction. The velocity field is mapped using Laser Doppler Anemometry (LDA), and the tracer gas concentration is sampled using Fast Flame Ionization Detection (FFID). The concentration field is characterized by the mean concentration and the characteristic percentiles of the concentration-time series, such as the median and the peak, represented by the 99th percentile, in a total of 1138 sampling points. The probability distribution of the concentration in each point is modeled using the gamma distribution, which is fitted based on the mean and the variance of the measured time series. The results show that the mean pedestrian exposure to air pollutants is significantly lower in the case of heterogeneous roof height, although the mean concentration at the leeward corner of the source canyon can locally exceed those of the uniform street canyons for both tower arrangements of variable building height. Moreover, it is shown that the concentration peaks for both tower configurations can significantly exceed those of the uniform canyons case, especially near the sources. © 2024 The Authors}, keywords = {Probability distributions; Time series; Classifiers; Gamma distribution; Gamma distribution; Air quality; Doppler effect; Anemometers; Roofs; CONCENTRATION FLUCTUATIONS; Wind tunnels; Urban air quality; Urban air quality; Non-uniform; Wind tunnel measurements; street canyon; street canyon; concentration fluctuation; Laser doppler anemometry; Laser Doppler velocimeters; flame ionization detection; Peak concentrations; Peak concentrations; Building height; Fast Flame Ionization Detection (FFID); Laser Doppler Anemometry (LDA); Non-uniform building height; Variable roof height; Wind tunnel measurement; Fast flame ionization detection; Laser dopple anemometry; Non-uniform building height; Variable roof height}, year = {2024}, eissn = {1872-8197}, orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Istók, Balázs/0000-0002-0248-0074; Balczó, Márton/0000-0002-1273-3047; Kristóf, Gergely/0000-0001-7572-6875} } @inproceedings{MTMT:33113557, title = {Statistical assessment of the ventilation of street canyons based on time-resolved wind tunnel experiments}, url = {https://m2.mtmt.hu/api/publication/33113557}, author = {Papp, Bálint and Istók, Balázs and Koren, Márton and Balczó, Márton and Kristóf, Gergely}, booktitle = {PHYSMOD 2022 - International Workshop on Physical Modeling of Flow and Dispersion Phenomena}, unique-id = {33113557}, year = {2022}, pages = {143-155}, orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Istók, Balázs/0000-0002-0248-0074; Balczó, Márton/0000-0002-1273-3047; Kristóf, Gergely/0000-0001-7572-6875} } @article{MTMT:32132140, title = {Monitoring Multi-respiratory Indices via a Smart Nanofibrous Mask Filter Based on a Triboelectric Nanogenerator}, url = {https://m2.mtmt.hu/api/publication/32132140}, author = {He, Haijun and Guo, Jian and Illés, Balázs György and Géczy, Attila and Istók, Balázs and Hliva, Viktor and Török, Dániel and Kovács, József Gábor and Harmati, István and Molnár, Kolos}, doi = {10.1016/j.nanoen.2021.106418}, journal-iso = {NANO ENERGY}, journal = {NANO ENERGY}, volume = {89}, unique-id = {32132140}, issn = {2211-2855}, year = {2021}, eissn = {2211-3282}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074; Hliva, Viktor/0000-0002-1286-5787; Török, Dániel/0000-0003-4521-2771; Kovács, József Gábor/0000-0002-7391-7085; Molnár, Kolos/0000-0002-9331-4652} } @article{MTMT:31806292, title = {Measurement-driven Large Eddy Simulation of dispersion in street canyons of variable building height}, url = {https://m2.mtmt.hu/api/publication/31806292}, author = {Papp, Bálint and Kristóf, Gergely and Istók, Balázs and Koren, Márton and Balczó, Márton and Balogh, Miklós}, doi = {10.1016/j.jweia.2020.104495}, journal-iso = {J WIND ENG IND AEROD}, journal = {JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS}, volume = {211}, unique-id = {31806292}, issn = {0167-6105}, year = {2021}, eissn = {1872-8197}, orcid-numbers = {Papp, Bálint/0000-0001-8043-5271; Kristóf, Gergely/0000-0001-7572-6875; Istók, Balázs/0000-0002-0248-0074; Balczó, Márton/0000-0002-1273-3047} } @inproceedings{MTMT:3423019, title = {Lézerscannelt 3D felszínmodell alkalmazása csatornakiöntések modelljének pontosítására}, url = {https://m2.mtmt.hu/api/publication/3423019}, author = {Istók, Balázs}, booktitle = {Országos Települési Csapadékvíz-gazdálkodási Konferencia tanulmányai}, unique-id = {3423019}, abstract = {Extrém csapadékvíz terhelés az egyesített rendszerű vagy a csapadékvíz elvezető hálózat túlterhelődéséhez vezethet, az elvezetendő víz a hálózatból kilépve, fedlapokon, árkok peremén átbukva, a környező utcákra, területekre folyhat. A kiöntés modellezése segít megérteni a jelenség folyamatát, rámutat a probléma okára és lehetőséget nyújt megelőző intézkedések várható hatásának a számításában. Hagyományos csatornahidraulikai modellek alkalmazása esetén az elvezető hálózatból kilépő víz egy virtuális tárolóba kerül, amelynek kapacitása a modell paramétere, jellemzően a környező területek méretéből határozható meg. A kiáramlás akadálytalanul történik meg, a virtuális tárolóban a túlterhelést okozó víz tározódik és az árhullám elvonulását követően a kiöntés helyén visszafolyik az elvezető hálózatba. A hálózaton kívüli, felszíni vízmozgás pontos meghatározása a legtöbb modellező szoftverben nem megoldott vagy korlátozott mértékben elérhető. Jelen dolgozat célja, hogy egy szintetikus és egy valós csatornahálózat modelljével végzett számításon keresztól bemutassa a felszíni vízmozgás modellezésének új lehetőségeit a felszíni vízáramlás és az elöntési képek pontos meghatározásával. A számítások és a modellezés egy repülőgéppel végzett terepszkennelés alapján felépített, nagy felbontású terepmodell-lel történik. Hagyományos dinamikus csatornahidraulikai modellezéssel meghatározásra került a vízmozgás a csatornahálózatban. Ez alapján a felszínmodell-lel megjeleníthetővé válik a kiöntés folyamata, az elárasztott terület, a felszíni vízmozgás és a csatornahálózatba történő visszaáramlás.}, year = {2019}, pages = {180-189}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074} } @mastersthesis{MTMT:2856292, title = {Egyesített rendszerű csatornahálózatok környezeti kibocsátásainak elemzése}, url = {https://m2.mtmt.hu/api/publication/2856292}, author = {Istók, Balázs}, publisher = {BME Áramlástan Tanszék}, unique-id = {2856292}, year = {2014}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074} } @article{MTMT:2696094, title = {Dispersion and travel time of dissolved and floating tracers in urban sewers}, url = {https://m2.mtmt.hu/api/publication/2696094}, author = {Istók, Balázs and Kristóf, Gergely}, doi = {10.2478/sjce-2014-0001}, journal-iso = {SLOVAK J CIV ENG}, journal = {SLOVAK JOURNAL OF CIVIL ENGINEERING}, volume = {22}, unique-id = {2696094}, issn = {1210-3896}, abstract = {Environmental impacts of oil spills affecting urban sewage networks can be eliminated if timely intervention is taken. Design of such actions requires the knowledge of transport of surface pollutants in open channels. In this study we investigated travel time and dispersion by means of tracer experiments in sewage networks and in a creek. Travel time of surface tracers has been found to be significantly shorter than that of the bulk flow tracer. The ratio of travel times of bulk flow tracer and surface tracers agreed with known correlations obtained for rivers. An increasing tendency of the ratio of travel times has been observed for increasing bulk flow velocity. A segment-wise dispersion model was implemented in the existing hydraulic model of the sewer system. Simulation results were compared with experimental observations. Dispersion rate of the bulk flow tracer has been found to obey Taylor’s mixing theory for long channels and was more intensive than that of surface tracers in community sewage channels.}, year = {2014}, eissn = {1338-3973}, pages = {1-8}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074; Kristóf, Gergely/0000-0001-7572-6875} } @article{MTMT:2695655, title = {Rain model for investigating overflow in combined sewer systems under regular operating conditions}, url = {https://m2.mtmt.hu/api/publication/2695655}, author = {Istók, Balázs and Kristóf, Gergely}, doi = {10.7323/ijaet}, journal-iso = {IJAEST}, journal = {INTERNATIONAL JOURNAL OF ADVANCES IN ENGINEERING SCIENCE AND TECHNOLOGY}, volume = {6}, unique-id = {2695655}, abstract = {In combined sewer systems, even regularly occurring heavy rainfall can cause overflows to occur under regular operating conditions. These overflows result in a mixture of rainfall and raw wastewater being transported to the receiving water body. Though hydraulic models provide a means for calculating the amount of overflow resulting from a given rain event, correct estimations for the annual amount of pollution can only be made after processing multiple year’s worth of rain event data. In order to reduce the time needed to complete the numerical simulations, a method is proposed for correctly modeling the overflow of a long series of historical rainfall data, using a reduced input dataset. Based on rainfall intensity measurements, a series of rain events was divided into block rains. The complete series of block rains was then replaced with 9 representative (weighted) block rains, each of equal rainfall. The method was tested on the hydraulic model of a 7500 ha catchment of the Budapest combined sewer system. When compared to overflow results attained by processing 3 years worth of rainfall data, sampled in 10 minute intervals, the overflow results of the 9 element numerical model deviated by less than 12%. The time necessary to complete the hydraulic simulations of the latter was 1/27th of the former. These faster numerical models will enable designers to search for optimal technological solutions from both an environmental as well as economic point of view.}, year = {2013}, eissn = {2231-1963}, pages = {1967-1976}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074; Kristóf, Gergely/0000-0001-7572-6875} } @article{MTMT:2693354, title = {Method for identification of the initial loss of combined sewer catchments}, url = {https://m2.mtmt.hu/api/publication/2693354}, author = {Istók, Balázs and Kristóf, Gergely}, doi = {10.3311/PPci.7173}, journal-iso = {PERIOD POLYTECH CIV ENG}, journal = {PERIODICA POLYTECHNICA-CIVIL ENGINEERING}, volume = {57}, unique-id = {2693354}, issn = {0553-6626}, abstract = {Intense, short periods of rainfall cause the greatest number of operational overflows, leading to the discharge of untreated sewage in combined sewerage systems of large cities. The annual amount of pollution can be estimated based on meteorological, orographic, surface coverage and hydraulic information, by using a detailed hydraulic model of the sewerage system. The most widely used hydrological models require input for the initial loss in order to define the amount of water remaining in the catchment, which decreases the load of the sewer and potentially, the amount of overflow. Earlier measurements of the initial loss were made only in rainwater channels. The results range from 0-6 mm in urban territory, which makes the case-by-case identification of this model parameter very important. A methodology is presented in this paper for calculating the amount of initial loss in a combined system catchment without any on-site measurements. The initial loss was identified for a 4500 ha catchment of Budapest. In addition, the dependence of the initial loss on the environmental temperature was analysed.}, keywords = {HYDROLOGICAL MODEL; surface runoff; Combined sewer; Initial loss}, year = {2013}, eissn = {1587-3773}, pages = {185-190}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074; Kristóf, Gergely/0000-0001-7572-6875} } @CONFERENCE{MTMT:2691148, title = {Egyesített rendszer környezeti hatásainak elemzése. Környezeti kihívások - Hazai megoldások}, url = {https://m2.mtmt.hu/api/publication/2691148}, author = {Istók, Balázs}, booktitle = {VII. Szennyvízágazati Konferencia}, unique-id = {2691148}, year = {2010}, orcid-numbers = {Istók, Balázs/0000-0002-0248-0074} }