Effects of different wind directions on ventilation of surrounding areas of two generic building configurations in Hong Kong

2021 ◽  
pp. 1420326X2110160
Author(s):  
Kai Yip Lee ◽  
Cheuk Ming Mak
Keyword(s):  
Wind Velocity ◽  
Natural Ventilation ◽  
Urban Environments ◽  
Air Pressure ◽  
Pressure Distributions ◽  
Air Intake ◽  
Dynamics Simulations ◽  
Surrounding Areas ◽  
Effective Use ◽  
Velocity Zone

This study investigated effects of incident wind angles on wind velocity distributions in wakes of two generic building configurations, namely, ‘T’- and ‘+’-shaped, and the air pressure distributions along their leeward walls by using computational fluid dynamics simulations. Results show that when the wind approaches laterally (90°) (vs. when the wind is direct (0°)), the downwind length and maximum bilateral width of the low-wind velocity zone in the wake of ‘T’-shaped building decrease by 11.5% and 37.9%, respectively. When the incident wind is oblique (45°) (vs. when it is direct), the length and width of this low-wind velocity zone in the wake of ‘+’-shaped building decrease by 15.0% and 30.9%, respectively. Furthermore, results show that the air pressure on the leeward walls of the ‘T’- and ‘+’-shaped buildings gradually decreases along with the building height. The resulting low-wind conditions on upper floors of buildings reduce the fresh air intake of their leeward units utilizing natural ventilation. It is particularly apparent in the case of direct approaching wind. Thus, the appropriate selection of building configurations and their orientations allows for the most effective use of wind to enhance ventilation in indoor and urban environments.

scholarly journals Effect of Pressure Distribution on the Energy Dissipation of Lap Joints under Equal Pre-tension Force

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 320-328
Author(s):  
Delin Sun ◽  
Minggao Zhu
Keyword(s):  
Energy Dissipation ◽  
Pressure Distribution ◽  
Theoretical Basis ◽  
Lap Joints ◽  
Power Exponent ◽  
Lap Joint ◽  
Stick Slip ◽  
Pressure Distributions ◽  
Hysteretic Characteristics ◽  
Effective Use

Abstract In this paper, the energy dissipation in a bolted lap joint is studied using a continuum microslip model. Five contact pressure distributions compliant with the power law are considered, and all of them have equal pretension forces. The effects of different pressure distributions on the interface stick-slip transitions and hysteretic characteristics are presented. The calculation formulation of the energy dissipation is introduced. The energy dissipation results are plotted on linear and log-log coordinates to investigate the effect of the pressure distribution on the energy distribution. It is shown that the energy dissipations of the lap joints are related to the minimum pressure in the overlapped area, the size of the contact area and the value of the power exponent. The work provides a theoretical basis for further effective use of the joint energy dissipation.

scholarly journals Testing the Effect of Hedge Height on Perceived Safety—A Landscape Design Intervention

2021 ◽  
Vol 13 (9) ◽  
pp. 5063
Author(s):  
Katinka H. Evensen ◽  
Helena Nordh ◽  
Ramzi Hassan ◽  
Aslak Fyhri
Keyword(s):  
Field Study ◽  
Field Experiments ◽  
Landscape Design ◽  
Urban Environments ◽  
Space Management ◽  
Perceived Safety ◽  
Urban Green Spaces ◽  
Outdoor Spaces ◽  
Surrounding Areas ◽  
The Impact

Access to safe, green urban environments is important for quality of life in cities. The objective of this study is to explore the impact of a safety-enhancing landscape design measure on visitors’ experiences in an urban park. Additionally, this paper combines the use of field and virtual reality (VR) experiments, contributing methodological insights into how to evaluate safety measures in green space management and research on perceived safety. In a field experiment (n = 266), we explored whether the height of a hedge along a pathway influenced perceived safety among users. The field study showed that cutting down the hedge improved the perceived prospect of the immediate surrounding areas for female users, which again made them feel safer in the park. We developed a VR experiment for an evening scenario in the same environment (n = 19) to supplement the field study and test the effect of the intervention further. The VR experiment also found a gender effect on perceived safety, with females reporting lower perceived safety, but no effect was shown for the height of the hedge. The results in this study show that environmental attributes such as perceived prospect and concealment should be considered in the design and management of urban green spaces. Additionally, this research demonstrates an approach to conducting field experiments to test the effects of actual design interventions and then further developing these experiments using VR technology. Further research on perceived safety in outdoor spaces is needed to make use of this combined method’s potential.

Numerical simulation of fairing separation test for hypersonic air breathing vehicle

2016 ◽  
Vol 231 (2) ◽  
pp. 319-325 ◽  
Author(s):  
Ankit Raj ◽  
K Anandhanarayanan ◽  
R Krishnamurthy ◽  
Debasis Chakraborty
Keyword(s):  
Structural Integrity ◽  
Test Results ◽  
Air Breathing ◽  
Aerodynamic Loads ◽  
Pressure Distributions ◽  
Ground Test ◽  
Computational Fluid Dynamics Simulations ◽  
Euler Solver ◽  
Dynamics Simulations ◽  
Flight Hardware

Fairings are provided to cover hypersonic air breathing vehicle to protect it from adverse aerodynamic loading and kinetic heating. Separation dynamics of fairings is an important event in the launch of vehicle. Extensive computational fluid dynamics simulations are carried out for the design of fairings and vehicle and selection of time sequences of various separation events. A ground test of fairing separation is conducted in the sled facility to check the structural integrity and functionality of various separation mechanisms and flight hardware. Simulations have been carried out to study the separation dynamics of fairings at test conditions using grid-free Euler solver to get the aerodynamic loads and the loads are integrated to get the trajectory of fairings. The aerodynamic loads are provided to verify the structural integrity of various components and the trajectory of panels is used in the test planning. The pressure distributions on the vehicle are compared with the test results.

scholarly journals Toeholder: a software for automated design and in silico validation of toehold riboswitches

2021 ◽  
Author(s):  
Angel Fernando Cisneros Caballero ◽  
Francois D. Rouleau ◽  
Carla Bautista ◽  
Pascale Lemieux ◽  
Nathan Dumont-Leblond
Keyword(s):  
In Silico ◽  
Dynamic Range ◽  
Regulatory Elements ◽  
Automated Design ◽  
Design And Optimization ◽  
Potential Applications ◽  
Dynamics Simulations ◽  
Effective Use ◽  
Biological Circuits ◽  
High Throughput Experiments

Synthetic biology aims to engineer biological circuits, which often involve gene expression. A particularly promising group of regulatory elements are riboswitches because of their versatility with respect to their targets, but early synthetic designs were not as attractive because of a reduced dynamic range with respect to protein regulators. Only recently, the creation of toehold switches helped overcome this obstacle by also providing an unprecedented degree of orthogonality. However, a lack of automated design and optimization tools prevents the widespread and effective use of toehold switches in high-throughput experiments. To address this, we developed Toeholder, a comprehensive open-source software for toehold design and in silico benchmarking. Toeholder takes into consideration sequence constraints as well as data derived from molecular dynamics simulations of a toehold switch. We describe the software and its in silico validation results, as well as its potential applications and impacts on the management and design of toehold switches.

scholarly journals An OpenFOAM simulation of the natural ventilation system in a university chemical laboratory

2020 ◽  
Vol 167 ◽  
pp. 04003
Author(s):  
M Córdova-Suárez ◽  
O. Tene-Salazar ◽  
F. Tigre-Ortega ◽  
S. Carrillo-Ríos ◽  
D. Córdova-Suárez ◽  
...  
Keyword(s):  
Working Conditions ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Operating Conditions ◽  
Climate Data ◽  
Chemical Laboratory ◽  
Indoor Airflow ◽  
Air Intake ◽  
Air Speed ◽  
Closed Environment

The indoor airflow with a natural ventilation system was numerically calculated using the laminar and turbulent approach. In the chemical laboratory of the Technical University of Ambato, the computational code OpenFoam demonstrated an ability to numerically predict flow patterns. The design contemplated the natural ventilation system considering the laboratories’ working conditions not only in summer, but also in a winter week. These two operating conditions are calculated on a fully open and closed environment. For a room with a capacity of 20 people, the climate data average values were recorded at 14.0 ° C, 81.7%, 1.7 m /s for temperature, relative humidity, and wind speed, respectively. Furthermore, the demonstration has shown that the homogeneous occupancy air speed average is was 0.7 m / s with a facade air intake of 1.0 m / s 0.6 m / s in the room valid for the exchange of air and evacuation of pollutants. The maximum pressures were found in the lower part of the laboratory. This prevents the modification of the thermo-hygrometric conditions.

Wind Catcher Technology: The Impact of Tower Cross Section and Turbine on Wind Power Harnessing

2019 ◽  
Author(s):  
Jonathan C. Corbett ◽  
Navid Goudarzi ◽  
Mohammadamin Sheikhshahrokhdehkordi
Keyword(s):  
Wind Power ◽  
Wind Turbines ◽  
Cross Sections ◽  
Natural Ventilation ◽  
Performance Metrics ◽  
Urban Environments ◽  
Ducted Turbine ◽  
And Performance ◽  
Turbine Design ◽  
The Impact

Abstract This research explores utilizing distributed wind turbines in the built environment computationally. The targeted wind turbine design is an unconventional ducted turbine, called Wind Tower technology that its operation and performance metrics have been studied in earlier works in the team. Wind Tower is an established architectural technology that operates by catching wind and directing it into buildings, providing natural ventilation to support HVAC systems, and thus reducing cooling costs in urban environments. Wind power has long struggled to meet expectations in built (urban) environments. By combining wind towers at different cross sections with wind turbines, one might develop a device which provides natural ventilation and produces power in spite of a hostile wind environment. The preliminary results suggest that the maximum potential for a wind tower-turbine combination appears to be 700-1.46 kW under idealized conditions with a 4 m/s site dominant wind speed. This suggests that wind towers might be viable for power harvesting in both remote and grid connected regions. Further analysis suggested that additional turbine performance enhancements are needed to bring the turbine real power production closer to that ideal.

scholarly journals Innovative HVAC System Using an Integrated Greenhouse for a Virtual Low Energy Office Building

2019 ◽  
Vol 111 ◽  
pp. 04011
Author(s):  
Catalin Lungu ◽  
Florin Baltaretu
Keyword(s):  
Natural Ventilation ◽  
Energy Use ◽  
Ventilation System ◽  
Office Building ◽  
Treatment Unit ◽  
Heating And Cooling ◽  
Venturi Effect ◽  
Innovative System ◽  
Air Intake ◽  
Air Humidification

In this paper the authors describe a HVAC innovative system using an integrated greenhouse for heating and cooling an office building. The ventilation system allows natural (night) or mechanical ventilation and the passive cooling during the summer, including cold storage in the building structure and the PCM plywood and the refrigeration energy use during the day. Natural ventilation occurs when the wind or the Venturi effect, created by the « hat » that supports the photovoltaic panels, is strong enough; otherwise, a variable speed exhaust fan mounted on top of the building is used. The plants inside the greenhouse can produce O2 under certain conditions necessary for refreshing the ventilation air. The environment of the greenhouse allows air humidification naturally, without the use of humidifiers. If the greenhouse is sufficiently insulated in winter, it can be used in the ventilation process: the air intake from offices through the greenhouse, humidified and enriched in O2 (premixed, if necessary, with fresh air) reaches the general air treatment unit, and then sent back. The process is similar in the summer, but without recirculation, due to the humidity of the air extracted from offices. Stale air humidification enhances the thermal transfer process from the desiccant collector.

scholarly journals The long-term effects of meteorological parameters on pertussis infections in Chongqing, China, 2004–2018

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yongbin Wang ◽  
Chunjie Xu ◽  
Jingchao Ren ◽  
Yingzheng Zhao ◽  
Yuchun Li ◽  
...  
Keyword(s):  
Regression Model ◽  
Wind Velocity ◽  
Meteorological Parameters ◽  
Negative Binomial ◽  
Air Pressure ◽  
Weather Variability ◽  
Monthly Average ◽  
Weather Parameters ◽  
Cointegration Testing

Abstract Evidence on the long-term influence of climatic variables on pertussis is limited. This study aims to explore the long-term quantitative relationship between weather variability and pertussis. Data on the monthly number of pertussis cases and weather parameters in Chongqing in the period of 2004–2018 were collected. Then, we used a negative binomial multivariable regression model and cointegration testing to examine the association of variations in monthly meteorological parameters and pertussis. Descriptive statistics exhibited that the pertussis incidence rose from 0.251 per 100,000 people in 2004 to 3.661 per 100,000 persons in 2018, and pertussis was a seasonal illness, peaked in spring and summer. The results from the regression model that allowed for the long-term trends, seasonality, autoregression, and delayed effects after correcting for overdispersion showed that a 1 hPa increment in the delayed one-month air pressure contributed to a 3.559% (95% CI 0.746–6.293%) reduction in the monthly number of pertussis cases; a 10 mm increment in the monthly aggregate precipitation, a 1 °C increment in the monthly average temperature, and a 1 m/s increment in the monthly average wind velocity resulted in 3.641% (95% CI 0.960–6.330%), 19.496% (95% CI 2.368–39.490%), and 3.812 (95% CI 1.243–11.690)-fold increases in the monthly number of pertussis cases, respectively. The roles of the mentioned weather parameters in the transmission of pertussis were also evidenced by a sensitivity analysis. The cointegration testing suggested a significant value among variables. Climatic factors, particularly monthly temperature, precipitation, air pressure, and wind velocity, play a role in the transmission of pertussis. This finding will be of great help in understanding the epidemic trends of pertussis in the future, and weather variability should be taken into account in the prevention and control of pertussis.

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