Shengwei Zhu

Far–UVC (222 nm UV–C light) is a promising tool to mitigate aerosol transmission of pathogens indoors. However, recent studies have raised concerns related to ozone (O 3 ) production and secondary chemistry. In this study, we measured indoor O 3 and ultra-fine particle (UFP, 17.5–289 nm) concentrations with and without 222 nm far–UVC (average fluen...

A lack of consideration of outdoor spaces of universities has resulted in lower outdoor thermal comfort in summer. This study investigates the thermal comfort of outdoor spaces of a university in summer and proposes the model’s accuracy and optimization strategies to improve the outdoor thermal environment, including vegetation greening, building m...

Plastic barriers physically separate queuing passengers in airport security check areas as a measure against aerosol transmission. However, this may create “canyons” that interfere with the existing ventilation design: potentially inhibiting airflow, concentrating exhaled viruses, and exacerbating aerosol transmission risk. Accordingly, this study...

This study used Computational Fluid Dynamics (CFD) to investigate air disinfection for SARS-CoV-2 by the Upper-Room Germicidal Ultraviolet (UR-GUV), with focus on ceiling impact. The study includes three indoor settings, i.e., low (airport bus), medium (classroom) and high (rehearsal room) ceilings, which were ventilated with 100% clean air (CA cas...

The exhalation of aerosols during musical performances or rehearsals posed a risk of airborne virus transmission in the COVID‐19 pandemic. Previous research studied aerosol plumes by only focusing on one risk factor, either the source strength or convective transport capability. Furthermore, the source strength was characterized by the aerosol conc...

Airport transportation vehicles, such as buses, aerotrains, and shuttles, provide important passenger transfer services in airports. This study quantitatively investigated COVID-19 aerosol infection risk and identified acceptable operational conditions, such as passenger occupancy rates and duration of rides, given the performance of vehicle ventil...

No PDF available ABSTRACT Outbreaks from choirs showed that singing brings potential risk of COVID-19 infection. There is less known about the risks of airborne infection from other musical performance, such as playing wind instruments or performing theatre. In addition, it is important to understand methods to reduce infection risk. In this study,...

Outbreaks from choir performances, such as the Skagit Valley Choir, showed that singing brings potential risk of COVID-19 infection. There is less known about the risks of airborne infection from other musical performances, such as playing wind instruments or performing theater. In addition, it is important to understand methods that can be used to...

Indoor fungi, as an important group of biological contaminants, are recognized as risk factors for human health. However, limited data are currently available on fungal pollution in houses of China. In this study, fungi in air, in settled dust and on surfaces in urban houses with children are determined in six major cities of China. Aspergillus spp...

To improve the atmospheric environment by optimizing urban morphology, this study develops a random forest (RF) model to investigate the influence of urban morphology on PM2.5 variations via the relative importance of urban morphology and the nonlinear response relationship between urban morphology and PM2.5. Two indices—reduction range (C↓) and ra...

Personal Conditioning Devices (PCD) create a microenvironment around their users and therefore, better satisfy an individual’s thermal comfort than central HVAC systems can. Existing PCDs are categorized into stationary devices and wearable devices. Both types of devices have respective advantages and disadvantages. This paper introduces a novel pe...

The Aviation Public Health Initiative is a joint program of the Harvard School of Public Health and Kennedy School of Government, sponsored for Airlines for America (A4A) member organisations, manufacturers, and airport operators. The intent of the report is to underscore the importance of follwiing the science of SARS-CoV-2 in order to save lives,...

To provide excellent thermal comfort in an energy-efficient manner, the radiant floor cooling and heating system has become an attractive technology. In this work, an intermittently-operated radiant floor heating system combined with a ventilation system for use during the weekdays is proposed via a transient two-dimensional computational fluid dyn...

This paper reported concentration characteristics of thirteen kinds of gaseous carbonyl compounds (CCs) in urban houses with schoolchildren in two different climatic zones of China, estimated schoolchildren’s daily inhalation dose of formaldehyde and acetaldehyde, and then evaluated potential health risks for schoolchildren. Formaldehyde was the mo...

Strategies to protect building occupants from the risk of acute respiratory infection (ARI) need to consider ventilation for its ability to dilute and remove indoor bioaerosols. Prior studies have described an association of increased self-reported colds and influenza-like symptoms with low ventilation but have not combined rigorous characterizatio...

Spatial and temporal variations of traffic-related particulate pollution, e.g. PM1.0, PM2.5, and PM10, were monitored in a university campus in Wuhan, China with mobile and fixed-site approaches. We repeated mobile measurements when there was a high vehicle volume on the major road near the campus and only few traffic in the campus. PM concentratio...

Ductless personalized ventilation (DPV) as a recently developed technique and having the potential to meet the requirement of local thermal comfort and increase a wider thermostat setpoint range. The majority of published studies focused on the performance of DPV combined with convective-dominant HVAC system, while few investigations employed DPV i...

This study conducted a series of computational fluid dynamics simulations to evaluate the thermal comfort performance of a radiant floor cooling system when combined with different ventilation systems, including mixed ventilation (MV), stratum ventilation (SV), displacement ventilation (DV) and ductless personalized ventilation (DPV). A window temp...

Atmospheric particulate matter (PM)pollution is becoming a growing global problem with the rapid process of urbanization. Urban green space (UGS)can effectively alleviate PM; however, few studies have investigated the effects of the UGS morphological pattern on PM, especially from a spatial strategy perspective. This study probed the contribution a...

This study conducted the numerical simulation to evaluate the performance of a ductless personalized ventilation (DPV) combined with radiant floor cooling system (RFCS) and displacement ventilation (DV) system. In the non-DPV cases, DV supplies air at temperature of 16 °C and 20 °C, respectively with a flow rate of 2.4 ACH. In the cases with DPV, D...

Airborne particulate matter (PM) has been a major threat to air quality and public health in major cities in China for more than a decade. Green space has been deemed to be effective in mitigating PM pollution; however, few studies have examined its effectiveness at the neighborhood scale. In this study, the authors probe the contributions from dif...

This paper presents a Scaled Sequential Thresholded Least Squares (S²TLS) algorithm to construct sparse regression models for flight load prediction. The combined use of a sparsification parameter λ and a magnification factor χ is proposed to tune both the model complexity and the regressor complexity. A bumpiness function is introduced to preferen...

A ballast layer is used to facilitate drainage and load transferring in railroad track structure. With tonnage accumulation, fine materials, such as coal dust, clay, locomotive sand, degraded ballast aggregate, and other small particles, will penetrate into the clean and uniformly graded ballast layer causing contamination, usually referred as foul...

This study defined Cooling Efficiency (CE) of a Spot-type Personalized Air-Conditioning (SPAC) device as the ratio of the additional sensible heat removal from human body induced by SPAC and the device's cooling capacity. CE enabled the investigation of SPAC performance on the occupant's sensible heat loss (Qs) and thermal sensation by its quantita...

Field campaigns were conducted in autumn and winter of 2013, respectively, to investigate indoor microclimate and air pollution in four naturally ventilated classrooms for the sixth-grade students at a primary school in Wuhan's urban area. The experimental results showed that indoor air temperature was 13-22°C in autumn and 5-22°C in winter, while...

Recent studies have shown that fine particulate matter (PM2.5 ) is associated with multiple adverse health outcomes and PM2.5 -induced oxidative stress is now commonly known as a proposed mechanism of PM2.5 -mediated toxicity. However, the association between allergic symptoms in children and exposure to PM2.5 has not been fully elucidated, particu...

This investigation quantifies the upper-room ultraviolet germicidal irradiation (UVGI) efficacy in a room with a ceiling-mounted fan that blew air either upwards or downwards at three rotational speeds. The numerical modeling deployed a steady-state passive scalar (Eulerian) and particle tracking (Lagrangian) CFD with a rotating reference frame. Tw...

Particulate matter (PM) air pollution was examined by the field monitoring of PM10 and PM2.5 concentrations in the residential environments of the children around 10-year old in Wuhan, China, in October and December, 2013. According to the results, PM2.5 was the primary respirable particulate air pollutant because the ambient concentration ratio of...

This study investigated the disinfection efficacy of the upper-room ultraviolet germicidal irradiation (UR-UVGI) system with ceiling fans. The investigation used the steady-state Computational Fluid Dynamics (CFD) simulations to solve the rotation of ceiling fan with a rotating reference frame. Two ambient air exchange rates, 2 ACH and 6 ACH (air c...

In order to optimize the use of ceiling fans to improve upper-room UVGI's disinfection efficacy in various indoor settings, this study proposed a validated CFD (Computational Fluid Dynamics) approach for the numerical parametric investigation of the integrated application of ceiling fan and upper-room UVGI. This CFD approach is based on the Euleria...

This study is aimed to numerically investigate the airborne transmission of influenza in a bus microenvironment. A CFD model integrated with the Wells-Riley Equation was developed and used to predict airborne infection probability of influenza in a bus. The commonly used in buses mixing ventilation method was evaluated, and both the effects of air...

Exposure to vehicle-generated ultrafine particles (

In order to evaluate the ventilation characteristics of car interior, a model experiment was performed. Part 1 deals with the air flow properties in a half-scale car model. In this paper, a trace gas experimental method equipped with Flame Ionization Detector (FID) systems is introduced to examine the local ventilation efficiency and inhaled air qu...

This field study focused on the investigation of air quality in the Harvard University shuttle bus system. Passenger exposures to carbon monoxide (CO), carbon dioxide (CO2), and particulate matter (PM) were monitored using continuous air sampling methods. Additionally, a passenger questionnaire was administered in order to access passenger percepti...

In this paper the thermal adaptive effect and thermal characteristics of positional adjustment of a seated human body was simulated by changing the human model's position relative to the cooled spot airflow by means of coupled simulation of convection, radiation, moisture transport, and Fanger's neutral model. However, the human thermal models of F...

In order to develop a computational thermal manikin to enable the prediction of the thermal sensation of an occupant in a non-uniform environment, in a previous paper (Zhu et al. 2007) we proposed and examined a simulation method combining Smith's human thermal physiological model with convective and radiant simulation by applying the proposed meth...

This study aimed at investigating the thermal comfort for the whole body as well as for certain local areas, skin temperatures, and sensible heat losses in various asymmetric radiant fields. Human subject experiments were conducted to assess the overall comfort sensation and local discomfort, and local skin temperatures were measured. Through therm...

To predict the thermal sensation of people located in a nonuniform environment, it is very important to clarify the local heat transfer in detail. In this context, the coupled simulation of convection, radiation, and the multi-element thermal physiological model established by Smith is investigated. The sensible heat transfer from the surface of a...

In this paper, the thermal adaptive effect of postural regulation was examined by simulating the heat discharge from a sitting human body dressed as an office worker in summer, which was exposed in the spot airflow supplied by a personal air-conditioner. At first, the experiments using a thermal manikin were carried out to measure the distributions...

In this paper, the transport characteristics of saliva droplets produced by coughing are examined in a calm indoor environment. Three subjects are studied, with results indicating that more than 6.7 mg of saliva is expelled at speeds of up to 22 m/s during each individual cough, and that saliva droplets can travel further than 2 m. In addition, the...

The validity of thermal indices expressed in local environmental temperature, which signify the influences of plural local thermal factors, such as partial operative temperature, local equivalent temperature, etc. was investigated in order to evaluate the non-uniform thermal environment. It was ascertained that due to a variety of heat transfer rat...

Computational fluid dynamics (CFD) analysis using a low Reynolds number k–ε model was performed to examine the inhalation region of a human body in a stagnant environment. To account for the influence of the three-dimensional form of the human body, a model that replicated the actual forms of a real human body was used. CFD analysis was applied fir...

In this paper, the dispersion process of coughed air in a stagnant indoor environment is visualized by the experiment using flour as tracer, and the transient CFD analysis coupled with concentration simulation. Moreover, the instant flow field in breathing zone immediately after coughing is visualized and measured by PIV. It shows that coughed air...

In this paper, the transmission characteristics of the spits excelled through coughing are examined in a calm environment. Three subject experiments were performed, and it shows that there are about 6.7mg spits expelled at a high speed up to 22m/s when coughing, and the spits can arrive further than 2m. Then the transmitting processes of the coughe...

In this paper, the flow field in human's respiration area was examined through the PIV (Particle Image Velocimetry) experiment using an experimental thermal manikin and CFD analysis, with the assumption of steady inhalation and unsteady breath. In the CFD analysis, the variation of the air-velocity distribution, and the influence of the exhaustion...

For a person exposed to spot airflow, his thermal sensation is considered to be greatly influenced by his posture relative to the spot airflow because of the change of the velocity distributions around his body caused by the posture adjustments. On the other hand, as one of the usual thermal adaptive activities, an office worker unconsciously alter...

In this paper, airborne infection caused by coughed airflow is investigated in a calm environment using transient CFD analysis on the dispersion of the coughed airflow. The dispersion phenomena of the airflows generated by coughing and exhaling in a calm room with two occupants were reproduced using the CFD analysis based on the unsteady models of...

In this paper, a personal air-conditioning system (PACS) considering the human thermal adaptability is analyzed. Although the conventional personal air-conditioner was proofed to be satisfactory in providing for the thermal comfort, it is being questioned on the term of its energy efficiency. Therefore, it is important and urgent to develop new typ...

This research aims to use a highly accurate thermal comfort prediction method that links non-uniform environments to the body's thermal sensation by numerical simulation. In order to predict the thermal sensation of an occupant in non-uniform environments with floor heating and air conditioning, we performed local and whole body thermal comfort eva...

In this paper, we propose a new mathematical model that allows us to determine the ventilation rate and airflow velocity in spaces between the clothing and the body. The model takes into account the distribution of tracer gas concentration in the spaces. We assessed the performance of this model by applying it to a heated cylinder covered with cott...