The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Monica Moroni - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the daytime planetary boundary layer over an idealized urban area influence of surface properties anthropogenic Heat flux and geostrophic wind intensity
Journal of Applied Meteorology and Climatology, 2016Co-Authors: Serena Falasca, Franco Catalano, Monica MoroniAbstract:AbstractLarge-eddy simulations of an idealized diurnal urban Heat island are performed using the Weather Research and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering the anthropogenic Heat contribution and the differences of thermal and mechanical properties between urban and rural surfaces. Several cases are simulated together with a reference case, considering different values of the control parameters: albedo, thermal inertia, roughness length, anthropogenic Heat Emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in the lower half of the PBL, the shear in the upper half, and t...
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numerical study of the daytime planetary boundary layer over an idealized urban area influence of surface properties anthropogenic Heat flux and geostrophic wind intensity
Journal of Applied Meteorology and Climatology, 2016Co-Authors: Serena Falasca, Franco Catalano, Monica MoroniAbstract:AbstractLarge-eddy simulations of an idealized diurnal urban Heat island are performed using the Weather Research and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering the anthropogenic Heat contribution and the differences of thermal and mechanical properties between urban and rural surfaces. Several cases are simulated together with a reference case, considering different values of the control parameters: albedo, thermal inertia, roughness length, anthropogenic Heat Emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in the lower half of the PBL, the shear in the upper half, and t...
Maria Wedzony - One of the best experts on this subject based on the ideXlab platform.
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stress related variation in antioxidative enzymes activity and cell metabolism efficiency associated with embryogenesis induction in isolated microspore culture of triticale x triticosecale wittm
Plant Cell Reports, 2009Co-Authors: Iwona żur, Elżbieta Golemiec, Magdalena Szechynskahebda, Maria Wedzony, Ewa Dubas, Gabriela GolebiowskaAbstract:Isolated microspore cultures of two spring triticale (x Triticosecale Wittm.) cultivars were used to examine the effect of various stress treatments (either high—32°C or low—5°C temperature with or without nitrogen/carbohydrate starvation) applied to excised anthers on the effectiveness of microspore embryogenesis induction. To quantify the effects of pretreatment conditions, the activity of antioxidative enzymes (catalase, peroxidase and superoxide dismutase) together with respiration rate and Heat Emission were measured. It was observed that Heat shock treatment applied as the only one stress factor increased the activity of antioxidative enzymes which suggests intensive generation of reactive oxygen species. Such pretreatment effectively triggered microspore reprogramming but drastically decreased microspore viability. After low temperature treatment, the activity of antioxidative enzymes was similar to the control subjected only with the stress originated from the transfer to in vitro culture conditions. This pretreatment decreased the number of microspores entering embryogenesis but sustained cell viability and this effect prevailed in the final estimation of microspore embryogenesis effectiveness. For both, low- and high-temperature treatments, interaction with starvation stress was beneficial increasing microspore viability (at 5°C) or efficiency of embryogenesis induction (at 32°C). The latter treatment significantly reduced cell metabolic activity. Physiological background of these effects seems to be different and some hypothetical explanations have been discussed. Received data indicate that in triticale, anther preculture conditions could generate oxidative stress and change the cell metabolic activity which could next be reflected in the cell viability and the efficiency of microspore embryogenesis.
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stress induced changes important for effective androgenic induction in isolated microspore culture of triticale triticosecale wittm
Plant Cell Tissue and Organ Culture, 2008Co-Authors: Iwona Żur, Elżbieta Golemiec, Magdalena Szechynskahebda, Maria Wedzony, Ewa Dubas, Franciszek JanowiakAbstract:The accumulation of abscisic acid (ABA) and the activities of antioxidative enzymes along with cell metabolic activity were monitored during androgenesis induction in triticale (×Triticosecale Wittm.). Tested cultivars ‘Mieszko’ and ‘Wanad’ were selected due to their significantly different responses to androgenic induction. Significant variation was observed in respect of superoxide dismutase activity and endogenous ABA content in anthers isolated from freshly cut tillers. For both cultivars, tillers pretreatment with low temperature decreased peroxidase activity by 36%, highly accelerated respiration rate and reduced Heat production. At the same time, the level of ABA in ‘Mieszko’ was increased to the level measured in ‘Wanad’. This effect was associated with higher microspore culture viability and increased stress tolerance in ‘Mieszko’. Low temperature and metabolic starvation during 4-day anther preculture did not influence activities of antioxidative enzymes, while it resulted in slight decrease in respiration rate and Heat Emission. The importance of these changes for effective androgenesis induction is discussed.
Jarek Kurnitski - One of the best experts on this subject based on the ideXlab platform.
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Experimental determination of radiator, underfloor and air Heating Emission losses due to stratification and operative temperature variations
Energy and Buildings, 2018Co-Authors: Mikk Maivel, Andrea Ferrantelli, Jarek KurnitskiAbstract:Thermal comfort and Emission efficiency are important factors when choosing Heat Emission systems in low energy buildings. In this study, we consider the context of northern low-energy buildings, and compare the three most popular Heat Emission systems: radiator, underfloor and air Heating systems with upper distribution. With an analysis based on laboratory measurements performed in Tallinn, Estonia (Northern European climate), we determine the vertical temperature gradient and quantify Heat Emission losses in a typical low energy building with mechanical Heat recovery ventilation. Compared to a reference ideal Heater, ventilation-supplied air Heating with upper distribution induced a vertical temperature gradient of about 1 K/m, which together with operative temperature variation increased the energy use by 9.9%. Regarding radiator and underfloor Heating, the losses amounted instead to 2.3% and to 5.5%–7.9% respectively. Using our air and surface temperature measurements, we also verified experimentally the operative temperature variations previously determined for radiator and floor Heating, and extended this concept to air Heating. In conclusion, it is proposed to add operative temperature variation to the Heat Emission standard in order to enable fair comparison of Heat emitters. Both vertical temperature gradient and operative temperature variations determined in this study provide a solid extension of the EN 15316-2:2017 methodology.
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Radiator and floor Heating operative temperature and temperature variation corrections for EN 15316-2 Heat Emission standard
Energy and Buildings, 2015Co-Authors: Mikk Maivel, Jarek KurnitskiAbstract:In this paper new draft standard prEN 15316:2-2014 was tested against detailed dynamic simulation and an operative temperature corrections were developed in order to enable fair comparison of Heat emitters to provide equal thermal comfort for occupants. Simple one room model with different number of external envelope elements and two occupant positions were used to analyze operative temperature effects. Operative temperature corrections and comparative analyses with the tabulated values of the standard were conducted with two low energy reference building simulation models in two climates. The use of the operative temperature set-point increased the temperature variation in the case of radiator Heating by 0.2-0.3 K and decreased it in the case of floor Heating by 0.1 K. However, in the case of floor Heating the occupant location effect provided an additional increase of 0.1 K which compensated the operative temperature effect, i.e. no correction is needed for floor Heating. For the radiator Heating the operative temperature variation of 0.25 K is to be added, but this increase falls well within the safety margin of about 0.35 K of existing tabulated values. The comparison of the Emission efficiency of the radiator and floor Heating revealed equally efficient by the PI controller.
Serena Falasca - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the daytime planetary boundary layer over an idealized urban area influence of surface properties anthropogenic Heat flux and geostrophic wind intensity
Journal of Applied Meteorology and Climatology, 2016Co-Authors: Serena Falasca, Franco Catalano, Monica MoroniAbstract:AbstractLarge-eddy simulations of an idealized diurnal urban Heat island are performed using the Weather Research and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering the anthropogenic Heat contribution and the differences of thermal and mechanical properties between urban and rural surfaces. Several cases are simulated together with a reference case, considering different values of the control parameters: albedo, thermal inertia, roughness length, anthropogenic Heat Emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in the lower half of the PBL, the shear in the upper half, and t...
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numerical study of the daytime planetary boundary layer over an idealized urban area influence of surface properties anthropogenic Heat flux and geostrophic wind intensity
Journal of Applied Meteorology and Climatology, 2016Co-Authors: Serena Falasca, Franco Catalano, Monica MoroniAbstract:AbstractLarge-eddy simulations of an idealized diurnal urban Heat island are performed using the Weather Research and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering the anthropogenic Heat contribution and the differences of thermal and mechanical properties between urban and rural surfaces. Several cases are simulated together with a reference case, considering different values of the control parameters: albedo, thermal inertia, roughness length, anthropogenic Heat Emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in the lower half of the PBL, the shear in the upper half, and t...
Chao Yuan - One of the best experts on this subject based on the ideXlab platform.
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analytical and numerical study on transient urban street air warming induced by anthropogenic Heat Emission
Energy and Buildings, 2021Co-Authors: Shuojun Mei, Chao YuanAbstract:Abstract Anthropogenic Heat Emission is an important factor for street air warming. In this study, the transient street air warming process caused by anthropogenic Heat is investigated by both the analytical model and Large-Eddy Simulation (LES). A new analytical model is developed based on the empirical exchange velocity modelling and Heat exchange rate estimation. In the model, the buoyancy effect is included by introducing a buoyancy coefficient. With the new analytical model, both transient time and steady-state street air temperature increment ( Θ c ) can be easily estimated in urban areas. This new model is calibrated and validated by cross-comparing with LES results. A good agreement is found between the results after including the buoyancy coefficient into the analytical model. Modelling results indicate that Θ c could be limited because the buoyancy effect increases the exchange velocity between the urban canopy layer and overlying atmosphere. Furthermore, the buoyancy is also important to the transient air exchange process. A transformation of the urban canopy layer flow structure is found in the transient period, suggesting a large scale turbulence structure induced by anthropogenic Heat. Lastly, the air temperature increment in the residential areas of Singapore is estimated with GIS (Geography Information System) tool to show the application of the analytical model in practice.
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mitigating intensity of urban Heat island by better understanding on urban morphology and anthropogenic Heat dispersion
Building and Environment, 2020Co-Authors: Chao Yuan, Ayu Sukma Adelia, Xianxiang Li, Wenhui He, Leslie K NorfordAbstract:Abstract Anthropogenic Heat is one of the key factors that causes intensive Urban Heat Island (UHI) due to its direct impact on ambient temperature in urban areas. Stagnated airflow due to closely packed tall buildings causes weak dilution and removal of anthropogenic Heat. Consequently, research is critically needed to investigate the effect of urban morphology on anthropogenic Heat dispersion and provide effective planning strategies to reduce UHI intensity, especially at the extreme scenarios, such as with very low wind speed and high Heat Emission. This study provides scientific understanding and develops a Geographic Information System (GIS)-based modelling tool to support decision-making in urban planning practice. We start from a computational parametric study at the neighbourhood scale to investigate the impact of urban morphology on Heat dispersion. Site coverage ratio and frontal area density are two urban morphological parameters. Ten parametric cases with two Heat Emission scenarios are designed to study representative urban areas. Furthermore, based on the energy conservation within urban canopy layers, we develop a semi-empirical model to estimate spatially-averaged in-canopy air temperature increment, in which the exchange velocity between street canyons and overlaying atmosphere is estimated by the Bentham and Britter model. The performance of new model is validated by cross-comparing with Computational Fluid Dynamics (CFD) results from the parametric study. By applying this new model, the impact of anthropogenic Heat on air temperature is mapped in residential areas of Singapore for both long-term annually averaged and short-term extreme low wind speed to improve urban climate sustainability and resilience.
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effects of urban morphology on anthropogenic Heat dispersion in tropical high density residential areas
Energy and Buildings, 2019Co-Authors: Ayu Sukma Adelia, Chao Yuan, R Q ShanAbstract:Abstract Anthropogenic Heat is constantly emitted to the urban environment in which could trigger a vicious cycle: risen the air temperature, subsequently increase the cooling-energy consumption and further intensify the urban Heat island effect. While extensive studies had been conducted to estimate the magnitude of anthropogenic Heat Emission in urban areas, research that investigates the behaviour of anthropogenic Heat dispersion in the outdoor environment is limited. This research aims to understand the interaction between the airflow and the flux of Heat rejected from the high-rise residential buildings, and effects of Heat flux on the air temperature in the street canyon. Parametric study is performed by using Computational Fluid Dynamics (CFD) simulation method, and the results indicate that, Emission position and building porosity play an important role in anthropogenic Heat removal from the street canyon. Single strategy, such as building height variance, can help to reduce the street canyon temperature to some extents, but the impact can be more significant when it is coupled with other strategies. At the end, a case study is conducted to evaluate the practicability of the suggested mitigation strategies in real urban design practice. This study bridges the knowledge gap between the complex aerodynamic physics and the real urban planning and design practices.
