scholarly journals Numerical Investigations of Virus Transport Aboard a Commuter Bus

2021 ◽  
Author(s):  
Hamid Rahai ◽  
Jeremy Bonifacio
Keyword(s):  
Ventilation System ◽  
Ventilation Rate ◽  
Solid Particles ◽  
Long Beach ◽  
Risk Of Infection ◽  
Virus Transport ◽  
High Exposure ◽  
Bus Transit ◽  
Bus Stop ◽  
In Transit

The authors performed unsteady numerical simulations of virus/particle transport released from a hypothetical passenger aboard a commuter bus. The bus model was sized according to a typical city bus used to transport passengers within the city of Long Beach in California. The simulations were performed for the bus in transit and when the bus was at a bus stop opening the middle doors for 30 seconds for passenger boarding and drop off. The infected passenger was sitting in an aisle seat in the middle of the bus, releasing 1267 particles (viruses)/min. The bus ventilation system released air from two linear slots in the ceiling at 2097 cubic feet per minute (CFM) and the air was exhausted at the back of the bus. Results indicated high exposure for passengers sitting behind the infectious during the bus transit. With air exchange outside during the bus stop, particles were spread to seats in front of the infectious passenger, thus increasing the risk of infection for the passengers sitting in front of the infectious person. With higher exposure time, the risk of infection is increased. One of the most important factors in assessing infection risk of respiratory diseases is the spatial distribution of the airborne pathogens. The deposition of the particles/viruses within the human respiratory system depends on the size, shape, and weight of the virus, the morphology of the respiratory tract, as well as the subject’s breathing pattern. For the current investigation, the viruses are modeled as solid particles of fixed size. While the results provide details of particles transport within a bus along with the probable risk of infection for a short duration, however, these results should be taken as preliminary as there are other significant factors such as the virus’s survival rate, the size distribution of the virus, and the space ventilation rate and mixing that contribute to the risk of infection and have not been taken into account in this investigation.

scholarly journals Risk of COVID-19 Infection in Public Transportation: The Development of a Model

2021 ◽  
Vol 18 (23) ◽  
pp. 12790
Author(s):  
Junsik Park ◽  
Gurjoong Kim
Keyword(s):  
Public Transportation ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Accurate Information ◽  
Risk Of Infection ◽  
Social Distancing ◽  
Indoor Space ◽  
The Government ◽  
Major Factors ◽  
Indoor Spaces

South Korea’s social distancing policies on public transportation only involve mandatory wearing of masks and prohibition of food intake, similar to policies on other indoor spaces. This is not because public transportation is safe from coronavirus disease 2019 (COVID-19), but because no suitable policies based on accurate data have been implemented. To relieve fears regarding contracting COVID-19 infection through public transportation, the government should provide accurate information and take appropriate measures to lower the risk of COVID-19. This study aimed to develop a model for determining the risk of COVID-19 infection on public transportation considering exposure time, mask efficiency, ventilation rate, and distance. The risk of COVID-19 infection on public transportation was estimated, and the effectiveness of measures to reduce the risk was assessed. The correlation between the risk of infection and various factors was identified through sensitivity analysis of major factors. The analysis shows that, in addition to the general indoor space social distancing policy, ventilation system installation, passenger number reduction in a vehicle, and seat distribution strategies were effective. Based on these results, the government should provide accurate guidelines and implement appropriate policies.

scholarly journals Investigation of the ventilation situation in a lecture room of building 033 at the Universität der Bundeswehr München

2021 ◽  
Author(s):  
Christian J. Kähler ◽  
Thomas Fuchs ◽  
Rainer Hain
Keyword(s):  
Viral Load ◽  
Uv Light ◽  
Aerosol Particles ◽  
Ventilation System ◽  
Armed Forces ◽  
Risk Of Infection ◽  
Free Air ◽  
Lecture Room ◽  
Private And Public ◽  
Public Lives

The SARS-CoV-2 pandemic is limiting both the private and public lives of many people around the world. It is now considered certain that SARS-CoV-2 is transmitted via droplets, smear infection, and aerosol particles. While simple masks, spacing, and hand hygiene significantly reduce the risk of infection via the first two routes mentioned, the risk from aerosol particles remains. These small particles move with the air in the room and spread unhindered throughout it. To reduce the risk of infection from viruses present in aerosol particles, the following options exist. First, good respiratory masks can be worn to reduce the viral load in the inhaled air. Another option is to make the viruses harmless (e.g., by UV light). A third option is to reduce the viral load in the room by bringing in virus-free air and moving contaminated air out or cleaning the air in the room. To investigate how well virus load reduction via ventilation works in a real lecture room, measurements were carried out at the Universität der Bundeswehr München (University of the Federal Armed Forces Munich). The lecture room holds a maximum of approx. 90 people and has a ventilation system as well as 2 windows that can be opened. In the absence of a ventilation system in a comparable room, the effectiveness of a room air cleaner was also investigated.

scholarly journals Resilient Schedule Coordination for a Bus Transit Corridor

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiongfei Lai ◽  
Jing Teng ◽  
Paul Schonfeld ◽  
Lu Ling
Keyword(s):  
Bus Transit ◽  
Schedule Coordination ◽  
Operating Environments ◽  
Transit Services ◽  
Passenger Flows ◽  
Transit Agencies ◽  
Transfer Stations ◽  
Link Travel Time ◽  
Bus Schedule ◽  
In Transit

Providing convenient transit services at reasonable cost is important for transit agencies. Timed transfers that schedule vehicles from various routes to arrive at some transfer stations simultaneously (or nearly so) can significantly reduce wait times in transit networks, while stochastic passenger flows and complex operating environments may reduce this improvement. Although transit priority methods have been applied in some high-density cities, operating delays may cause priority failures. This paper proposes a resilient schedule coordination method for a bus transit corridor, which analyzes link travel time, passenger loading delay, and priority signal intersection delay. It maximizes resilience based on realistic passenger flow volume, whether or not transit priority is provided. The data accuracy and result validity are improved with automatically collected data from multiple bus routes in a corridor. The Yan’an Road transit corridor in Shanghai is used as a case study. The results show that the proposed method can increase the system resilience by balancing operation cost and passenger-based cost. It also provides a guideline for realistic bus schedule coordination.

Case Studies of Rising Damp Treatment in Historical Buildings

2017 ◽  
Vol 10 ◽  
pp. 107-119
Author(s):  
A.S. Guimarães ◽  
J.M.P.Q. Delgado ◽  
V.P. de Freitas
Keyword(s):  
Building Materials ◽  
Ventilation System ◽  
Technical Specification ◽  
Residential Building ◽  
Ventilation Rate ◽  
Building Structures ◽  
Practical Application ◽  
Salt Damage ◽  
Building Physics ◽  
Rising Damp

Salt damage can affect the service life of numerous building structures, both historical and contemporary, in a significant way. Therefore, various conservation methods have been developed for the consolidation and protection of porous building materials exposed to the salt attack. As any successful treatment of salt damage requires a multidisciplinary attitude, many different factors such as salt solution transport and crystallization, presence and origin of salts in masonry, and salt-induced deterioration are to be taken into account. The importance of pre-treatment investigations is discussed as well; in a combination with the knowledge of salt and moisture transport mechanisms they can give useful indications regarding treatment options.Another important cause of building pathologies in buildings is the rising damp and this phenomenon it is particularly more severe with the presence of salts in water. The treatment of rising damp in historic building walls is a very complex procedure. At Laboratory of Building Physics (LFC-FEUP) a wall base hygro-regulated ventilation system was developed. This system patented, HUMIVENT, has been submitted to laboratorial monitoring and to in situ validation and a numerical simplified model was developed to facilitate the practical application. Having in mind the practical application of scientific and technological knowledge from Building Physics to practice, this paper presents the design of the system (geometry, ventilation rate and hygrothermal device), the detailing and technical specification of its different components and information about the implementation in three types of buildings: a church, a museum and a residential building.

scholarly journals Exposure Assessment in Nail Salons: An Indoor Air Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Cora Roelofs ◽  
Tuan Do
Keyword(s):  
Carbon Dioxide ◽  
Exposure Assessment ◽  
Indoor Air ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Self Report ◽  
Adequate Ventilation ◽  
The Common ◽  
Traditional Approaches ◽  
Nail Salons

Due to the complexity of the nail salon work environment, traditional approaches to exposure assessment in this context tend to mischaracterize potential hazards as nuisances. For this investigation, a workable “indoor air” approach was devised to characterize potential hazards and ventilation in Boston, Massachusetts area nail salons which are primarily owned and staffed by Vietnamese immigrants. A community-university partnership project recruited salons to participate in a short audit which included carbon dioxide measurements and evaluation of other air quality metrics. Twenty-two salons participated. Seventy-three percent of the salons had spot carbon dioxide measurements in excess of 700 ppm, the level corresponding to a ventilation rate recommended for beauty salons. Fourteen salons (64%) did not have a mechanical ventilation system to provide fresh air and/or exhaust contaminated air. The lack of adequate ventilation is of significant concern because of the presence of potentially hazardous chemicals in salon products and the common self-report of symptoms among nail technicians. Community and worker health may be improved through adoption of recommended ventilation guidelines and reduction in the hazard potential of nail products.

scholarly journals Ventilation conditions and air-borne bacteria and particles in operating theatres: proposed safe economies

1985 ◽  
Vol 95 (2) ◽  
pp. 325-335 ◽  
Author(s):  
R. P. Clark ◽  
P. J. Reed ◽  
D. V. Seal ◽  
M. L. Stephenson
Keyword(s):  
Ventilation Rate ◽  
Hospital Environment ◽  
Positive Pressure ◽  
Risk Of Infection ◽  
Flow Conditions ◽  
Increased Risk ◽  
Operating Theatres ◽  
Cleaning Procedures ◽  
Mechanical Cleaning ◽  
Zero Flow

SUMMARYConcentrations of air-borne bacteria and particles have been measured in turbulently ventilated operating theatres in full flow, half flow and zero flow conditions. Increased air-borne challenge produced by human activity and by mechanical cleaning procedures is demonstrated: die-away of this contamination is shown to be related to the ventilation rate. Ventilation can be reduced or turned off at night and during weekends, and cleaning can also be carried out, without increased risk of infection if full flow is restored one hour prior to preparation for surgery. Areas surrounding the theatres should remain at positive pressure with regard to the general hospital environment during low or no flow periods. The implementation of such energy-saving policies will substantially reduce theatre running costs without introducing infection hazards.

scholarly journals Effects of Lateral Window Position and Wind Direction on Wind-Driven Natural Cross Ventilation of a Building: A Computational Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
M. Z. I. Bangalee ◽  
J. J. Miau ◽  
S. Y. Lin ◽  
M. Ferdows
Keyword(s):  
Wind Direction ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Experimental Investigations ◽  
Original Design ◽  
Lateral Direction ◽  
Window Position ◽  
Ventilation Performance ◽  
Moderate Range

Energy is saved when an effective natural ventilation system can provide comfort air to the occupants in a building by replacing a mechanical ventilation system. It also minimizes the risk of the environmental pollution and the global warming. A one story, full scale building was considered to carry out a comparative study of three different cases of wind-driven natural (WDN) cross ventilation with the help of computational fluid dynamics (CFD). In each case, the location of window was changed in lateral direction to predict the probable position for optimum ventilation performance and the angle of wind was varied to check the sensitivity of the wind direction on the flow field. After validating the current methodology through two satisfactory comparisons with the experimental investigations, the governing equations subjected to the corresponding boundary conditions were solved using commercial software and then the results were analyzed. A better location for the windows in each case was proposed. The ventilation purpose was served quite well even if the wind angle was changed in a moderate range from the original design. Furthermore, the velocity components, ventilation rate, surface pressure, ventilation time, and so forth in each case were investigated and compared extensively with those in other cases.

Complexity analysis on public transport networks of 97 large- and medium-sized cities in China

2018 ◽  
Vol 32 (09) ◽  
pp. 1850108 ◽  
Author(s):  
Zhanwei Tian ◽  
Zhuo Zhang ◽  
Hongfei Wang ◽  
Li Ma
Keyword(s):  
Public Transport ◽  
Urban Areas ◽  
Complexity Analysis ◽  
Small World ◽  
Similar Distribution ◽  
Transport Networks ◽  
Transit Network ◽  
Bus Transit ◽  
Bus Stop ◽  
Line Network

The traffic situation in Chinese urban areas is continuing to deteriorate. To make a better planning and designing of the public transport system, it is necessary to make profound research on the structure of urban public transport networks (PTNs). We investigate 97 large- and medium-sized cities’ PTNs in China, construct three types of network models — bus stop network, bus transit network and bus line network, then analyze the structural characteristics of them. It is revealed that bus stop network is small-world and scale-free, bus transit network and bus line network are both small-world. Betweenness centrality of each city’s PTN shows similar distribution pattern, although these networks’ size is various. When classifying cities according to the characteristics of PTNs or economic development level, the results are similar. It means that the development of cities’ economy and transport network has a strong correlation, PTN expands in a certain model with the development of economy.

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