The Experts below are selected from a list of 19248 Experts worldwide ranked by ideXlab platform
Guangyu Cao - One of the best experts on this subject based on the ideXlab platform.
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CFD study of the air distribution and occupant draught sensation in a patient ward equipped with Protected Zone ventilation
Building and Environment, 2019Co-Authors: Amar Aganovic, Marie Steffensen, Guangyu CaoAbstract:Abstract Effective ventilation in general hospital wards is important for controlling the transmission of airborne infectious agents that may cause respiratory diseases. Recently, a new ventilation concept called Protected occupied Zone ventilation (POV) has been shown to have the ability to improve the quality of inhaled air compared to that of traditional ventilation strategies. This study numerically investigates the percentage of people dissatisfied due to draught close to the health-care worker (HCW) and patient in a single-bed isolation room equipped with POV. The CFD validation results showed that out of the three examined turbulence models, the SST k–ω models predicted the velocity and temperature profiles agreeably according to the experimental findings. The SST k–ω model was further used to visualize the airflow distribution in the patient ward and investigate the influence of the supply velocity and temperature on the draught risk. Supply velocities of 1.0, 1.5 and 2.0 m/s did not exceed the suggested comfort criterion of 20% even at lower supply temperatures. The draught risk at ankle level of the sitting patient exceeded the maximum allowed value at supply velocities of 2.5 and 3.0 m/s at both lower and higher supply temperatures.
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Experimental study of the transverse diffusion of pollutants through a downward plane jet in a room
International Journal of Ventilation, 2017Co-Authors: Guangyu Cao, Simo Kilpelainen, Kai SirenAbstract:Recently, a new type of ventilation method known as Protected Zone ventilation has been studied for application to the prevention of indoor contaminants transported from one Zone to another. The us...
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Protected Zone ventilation and reduced personal exposure to airborne cross-infection
Indoor air, 2014Co-Authors: Guangyu Cao, Peter V Nielsen, Rasmus Lund Jensen, Per Heiselberg, Li Liu, Jorma HeikkinenAbstract:The main objective of this study was to examine the performance of Protected Zone ventilation (PZV) and hybrid Protected Zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne cross-infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a Protected Zone from indoor pollutants emitted in a source Zone.
Xuemin Shen - One of the best experts on this subject based on the ideXlab platform.
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max min secrecy rate for noma based uav assisted communications with Protected Zone
Global Communications Conference, 2019Co-Authors: Zhisheng Yin, Min Jia, Wei Wang, Nan Cheng, Feng Lyu, Xuemin ShenAbstract:In this paper, we study the secrecy provisioning downlink transmission in an aerial-assisted network, where the unmanned aerial vehicle (UAV) serves as an aerial platform to provide secure transmission for the mobile users (MUs) with coexist of Internet of Things (IoT) nodes (INs). Specifically, secure transmission is required for MUs to combat eavesdropping attacks and a desired successful transmission probability should be ensured for INs to receive the public instruction massages. To improve the secrecy rates (SRs) for MUs, we consider an eavesdropper-free area, i.e., Protected Zone, surrounding the UAV. With non-orthogonal multiple access (NOMA) for MUs, the power allocation to each MU is optimized to maximize the minimum secrecy rate of MUs within the Protected Zone, under the constraints of successful receiving probability requirements for INs. To solve this problem, we first prove that the max-min SR can be obtained when SRs of all users are equal, and then a dichotomy-based successive power allocation policy is proposed. Numerical results show that higher max-min secrecy rate can be achieved by our proposed power allocation policy than the traditional policy.
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GLOBECOM - Max-Min Secrecy Rate for NOMA-Based UAV-Assisted Communications with Protected Zone
2019 IEEE Global Communications Conference (GLOBECOM), 2019Co-Authors: Zhisheng Yin, Min Jia, Wei Wang, Nan Cheng, Feng Lyu, Xuemin ShenAbstract:In this paper, we study the secrecy provisioning downlink transmission in an aerial-assisted network, where the unmanned aerial vehicle (UAV) serves as an aerial platform to provide secure transmission for the mobile users (MUs) with coexist of Internet of Things (IoT) nodes (INs). Specifically, secure transmission is required for MUs to combat eavesdropping attacks and a desired successful transmission probability should be ensured for INs to receive the public instruction massages. To improve the secrecy rates (SRs) for MUs, we consider an eavesdropper-free area, i.e., Protected Zone, surrounding the UAV. With non-orthogonal multiple access (NOMA) for MUs, the power allocation to each MU is optimized to maximize the minimum secrecy rate of MUs within the Protected Zone, under the constraints of successful receiving probability requirements for INs. To solve this problem, we first prove that the max-min SR can be obtained when SRs of all users are equal, and then a dichotomy-based successive power allocation policy is proposed. Numerical results show that higher max-min secrecy rate can be achieved by our proposed power allocation policy than the traditional policy.
Jorma Heikkinen - One of the best experts on this subject based on the ideXlab platform.
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Protected Zone ventilation and reduced personal exposure to airborne cross infection
Indoor Air, 2015Co-Authors: Peter V Nielsen, Rasmus Lund Jensen, Per Heiselberg, Jorma HeikkinenAbstract:: The main objective of this study was to examine the performance of Protected Zone ventilation (PZV) and hybrid Protected Zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne cross-infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a Protected Zone from indoor pollutants emitted in a source Zone.
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Protected Zone ventilation and reduced personal exposure to airborne cross-infection
Indoor air, 2014Co-Authors: Guangyu Cao, Peter V Nielsen, Rasmus Lund Jensen, Per Heiselberg, Li Liu, Jorma HeikkinenAbstract:The main objective of this study was to examine the performance of Protected Zone ventilation (PZV) and hybrid Protected Zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne cross-infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a Protected Zone from indoor pollutants emitted in a source Zone.
H. K. Trimbake - One of the best experts on this subject based on the ideXlab platform.
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$$\hbox {PM}_{2.5}$$ PM 2.5 , $$\hbox {PM}_{10}$$ PM 10 and surface oZone over Lumbini Protected Zone, Nepal, during monsoon season of 2012
Journal of Earth System Science, 2019Co-Authors: Kaushar Ali, D.k. Trivedi, D. M. Chate, Gufran Beig, Prodip Acharja, H. K. TrimbakeAbstract:Physical characterisation of $$\hbox {PM}_{2.5}$$ , $$\hbox {PM}_{10}$$ and surface oZone measured during the period from 17 July to 21 August 2012 at four strategic locations in and around the Lumbini Protected Zone, Nepal, is done to assess air quality of the region and understand qualitatively source mechanisms of these pollutants. The measurement locations are Panditarama Lumbini International Vipassana Meditation Centre, Parsahawa, Bhairahawa and Tilaurakot, representing monastic, industrial, urban and control areas, respectively. The overall average concentration of $$\hbox {PM}_{2.5}$$ at these locations is $${\sim }19\pm 12$$ , $$35\pm 13$$ , $$35\pm 11$$ and $$25\pm 6~ \upmu \hbox {g/m}^{3}$$ and of $$\hbox {PM}_{10}$$ is $${\sim }25\pm 11$$ , $$103\pm 41$$ , $$58\pm 15$$ and $$32\pm 7~ \upmu \hbox {g/m}^{3}$$ , respectively. $$\hbox {PM}_{2.5}$$ never crosses the safe limit of the National Ambient Air Quality Standards of Nepal (NNAAQS) in the monastic and control areas but either crosses the NNAAQS occasionally or remains in its vicinity at the other two locations. The $$\hbox {PM}_{10}$$ concentration frequently exceeds the safe limit in the industrial area but not in the other remaining areas. The analysis indicates the dominance of the impact of local sources and boundary layer thickness on the atmospheric loadings of the particulate matter. The daily average mixing ratio of surface oZone remains normally low at all the four observational sites although the mixing ratio of oZone at Panditarama Lumbini International Vipassana Meditation Centre is much lower than the NNAAQS but higher than that observed at Tilaurakot.
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hbox pm _ 2 5 pm 2 5 hbox pm _ 10 pm 10 and surface oZone over lumbini Protected Zone nepal during monsoon season of 2012
Journal of Earth System Science, 2019Co-Authors: Kaushar Ali, D.k. Trivedi, D. M. Chate, Gufran Beig, Prodip Acharja, H. K. TrimbakeAbstract:Physical characterisation of $$\hbox {PM}_{2.5}$$ , $$\hbox {PM}_{10}$$ and surface oZone measured during the period from 17 July to 21 August 2012 at four strategic locations in and around the Lumbini Protected Zone, Nepal, is done to assess air quality of the region and understand qualitatively source mechanisms of these pollutants. The measurement locations are Panditarama Lumbini International Vipassana Meditation Centre, Parsahawa, Bhairahawa and Tilaurakot, representing monastic, industrial, urban and control areas, respectively. The overall average concentration of $$\hbox {PM}_{2.5}$$ at these locations is $${\sim }19\pm 12$$ , $$35\pm 13$$ , $$35\pm 11$$ and $$25\pm 6~ \upmu \hbox {g/m}^{3}$$ and of $$\hbox {PM}_{10}$$ is $${\sim }25\pm 11$$ , $$103\pm 41$$ , $$58\pm 15$$ and $$32\pm 7~ \upmu \hbox {g/m}^{3}$$ , respectively. $$\hbox {PM}_{2.5}$$ never crosses the safe limit of the National Ambient Air Quality Standards of Nepal (NNAAQS) in the monastic and control areas but either crosses the NNAAQS occasionally or remains in its vicinity at the other two locations. The $$\hbox {PM}_{10}$$ concentration frequently exceeds the safe limit in the industrial area but not in the other remaining areas. The analysis indicates the dominance of the impact of local sources and boundary layer thickness on the atmospheric loadings of the particulate matter. The daily average mixing ratio of surface oZone remains normally low at all the four observational sites although the mixing ratio of oZone at Panditarama Lumbini International Vipassana Meditation Centre is much lower than the NNAAQS but higher than that observed at Tilaurakot.
Irene Vänninen - One of the best experts on this subject based on the ideXlab platform.
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The Importance of Maintaining Protected Zone Status against Bemisia tabaci
Insects, 2015Co-Authors: Andrew G. S. Cuthbertson, Irene VänninenAbstract:The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a major pest of economically important crops worldwide. Both the United Kingdom (UK) and Finland hold Protected Zone status against this invasive pest. As a result B. tabaci entering these countries on plants and plant produce is subjected to a policy of eradication. The impact of B. tabaci entering, and becoming established, is that it is an effective vector of many plant viruses that are not currently found in the Protected Zones. The Mediterranean species is the most commonly intercepted species of B. tabaci entering both the UK and Finland. The implications of maintaining Protected Zone status are discussed.
