Academic literature on the topic 'Transient shunt model'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Transient shunt model.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Transient shunt model"
1
Venkataraman, Pranav, Samuel R. Browd, and Barry R. Lutz. "A physical framework for implementing virtual models of intracranial pressure and cerebrospinal fluid dynamics in hydrocephalus shunt testing." Journal of Neurosurgery: Pediatrics 18, no. 3 (September 2016): 296–305. http://dx.doi.org/10.3171/2016.2.peds15478.
Full textAbstract:
OBJECTIVE The surgical placement of a shunt designed to resolve the brain's impaired ability to drain excess CSF is one of the most common treatments for hydrocephalus. The use of a dynamic testing platform is an important part of shunt testing that can faithfully reproduce the physiological environment of the implanted shunts. METHODS A simulation-based framework that serves as a proof of concept for enabling the application of virtual intracranial pressure (ICP) and CSF models to a physical shunt-testing system was engineered. This was achieved by designing hardware and software that enabled the application of dynamic model-driven inlet and outlet pressures to a shunt and the subsequent measurement of the resulting drainage rate. RESULTS A set of common physiological scenarios was simulated, including oscillations in ICP due to respiratory and cardiac cycles, changes in baseline ICP due to changes in patient posture, and transient ICP spikes caused by activities such as exercise, coughing, sneezing, and the Valsalva maneuver. The behavior of the Strata valve under a few of these physiological conditions is also demonstrated. CONCLUSIONS Testing shunts with dynamic ICP and CSF simulations can facilitate the optimization of shunts to be more failure resistant and better suited to patient physiology.
2
Poznanski, Roman R. "Transient response in a tapering cable model with somatic shunt." NeuroReport 7, no. 10 (July 1996): 1700. http://dx.doi.org/10.1097/00001756-199607080-00035.
Full text
3
Xiong, Jun Jie, Min Sun, Rui Xiang Fan, Tao Ding, and Luo Jiang Qian. "Research of Digital Simulating Model of Assembling Shunt Capacitor." Advanced Materials Research 605-607 (December 2012): 2413–18. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.2413.
Full textAbstract:
The paper describes numerical base of user defined component model (UDC) for real time digital simulator (RTDS), gives applied method of UDC technique combined with user defined steps of assembling shunt capacitor (ASC), compares transient simulating results of ASC UDC with models from RTDS library, and demonstrates UDC possess higher simulating efficiency and simulating quality is not decreased.
4
Kisielewicz, Tomasz, and Milton Cuenca. "Overview of Transient Simulations of Grounding Systems under Surge Conditions." Energies 15, no. 20 (October 18, 2022): 7694. http://dx.doi.org/10.3390/en15207694.
Full textAbstract:
The present paper gives an overview of modelling methods of standard grounding systems under surge conditions, using the non-uniform transmission line approach. The model presented considers the soil ionization and the frequency dependence of the soil parameters during the current transients. Furthermore, the representation of the non-linear response of the soil is made using a shunt time-variable resistance to simulate the behavior of the grounding resistance when a surge current flows through the system. The model development and analysis are made using ATP-EMTP/ATPDraw transient software.
5
Yang, Guang, Lin Li, Xile Zhang, Qing Jia, and Liqiang Liu. "A Transient Model for Controlled Shunt Reactor Based on Duality Theory." IEEE Transactions on Magnetics 51, no. 3 (March 2015): 1–4. http://dx.doi.org/10.1109/tmag.2014.2359013.
Full text
6
Hoh, Brian L., Shih-Shan Lang, Michael V. Ortiz, Yueh-Yun Chi, Stephen B. Lewis, and David W. Pincus. "LOWER INCIDENCE OF REOPERATION WITH LONGER SHUNT SURVIVAL WITH ADULT VENTRICULOPERITONEAL SHUNTS PLACED FOR HEMORRHAGE-RELATED HYDROCEPHALUS." Neurosurgery 63, no. 1 (July 1, 2008): 70–75. http://dx.doi.org/10.1227/01.neu.0000335072.32105.38.
Full textAbstract:
ABSTRACT OBJECTIVE The incidence of reoperation for ventriculoperitoneal shunts (VPS) in adults, although lower than in pediatric patients, is not insignificant. We hypothesize that adult VPS placed for hemorrhage-related hydrocephalus have a lower incidence of reoperation than those placed for other types of hydrocephalus. METHODS We retrospectively reviewed all adult (≥ 20 yr) VPS initially placed from February 2001 to August 2006 at the University of Florida. We determined the incidence and time interval to reoperation. Follow-up was conducted by telephone interview and review of medical records. RESULTS A total of 286 adult VPS were initially placed: 96 (34%) hemorrhage and 190 (66%) nonhemorrhage. A total of 15 (16%) hemorrhage patients underwent 22 shunt reoperations, compared with 50 (27%) nonhemorrhage patients who underwent 82 shunt reoperations (P = 0.0316). A Poisson regression analysis of the number of reoperations, factoring hemorrhage, age, and sex, demonstrated a significantly lower incidence of reoperation in hemorrhage patients (P = 0.0900). A Cox proportional hazards model analysis of time to first reoperation, factoring hemorrhage, age, and sex, demonstrated a significantly longer shunt survival in hemorrhage patients (P = 0.0404). CONCLUSION Adult VPS placed for hemorrhage-related hydrocephalus have a significantly lower incidence of reoperation and significantly longer shunt survival. This result may be related to an incidence of transient shunt dependency in patients with hemorrhage-related hydrocephalus. However, the precise mechanism remains unclear.
7
Guo, Xiaomei, Chongyang Jiang, Heng Qian, Zuchao Zhu, and Changquan Zhou. "Effect of Tip Clearance on the Cavitation Flow in a Shunt Blade Inducer." Energies 15, no. 17 (August 30, 2022): 6330. http://dx.doi.org/10.3390/en15176330.
Full textAbstract:
In order to study the effect of tip clearance on the internal cavitation stability of a shunt blade inducer, an external characteristics experiment of a centrifugal pump with a shunt blade inducer was carried out. Based on the turbulence model and mixture model, the cavitating flow in a centrifugal pump with the inducer was numerically simulated. The influence of tip clearance on the cavitating flow in a shunt inducer was studied and analyzed. Through the research, it was found that tip clearance has a certain influence on the critical cavitation coefficient. The existence of the tip clearance caused a significant leakage vortex near the inducer’s inlet and a strong transient effect was shown. The location and degree of cavitation caused by the tip leakage are clarified in this paper. Tip clearance has a great impact on the pressure distribution on a shunt blade inducer. The influence law of tip clearance on an inducer’s blade load distribution was clarified. The results showed that tip clearance has a significant effect on the cavitation of a shunt blade inducer under low flow rate conditions.
8
Van, Chi Nguyen, and Hoang Dang Danh. "Control shunt active filter based on dq frame using current model prediction." IAES International Journal of Robotics and Automation (IJRA) 8, no. 4 (December 1, 2019): 301. http://dx.doi.org/10.11591/ijra.v8i4.pp301-312.
Full textAbstract:
The nonlinear loads present more in the power systems in the practice today by developing of electronic technology and using the small distributed power sources (solar power, wind power etc.), this causes the increasing the high frequency switch devices etc. in the power network. Nonlinear loads cause non-sinusoidal currents and voltages with harmonic components, increasing the reactive power, overload of power lines and electrical devices, low power factor and affecting badly to the networks. Shunt active filters (SAF) with current controlled voltage source inverters (CCVSI) are used effectively to reduce the harmonics and to balance the phases sinusoidal source currents by generating the currents to compensate the harmonic currents caused by the nonlinear loads. In this paper we suppose a control strategy to generate the compensation currents of SAF by using the current model predictive engineering. This method is better than the control strategy using PI controller in term of transient time. The desired compensation currents can track exactly the reference compensation currents on the dq frame. The simulation results implemented on the nonlinear load, a full bridge rectifier and 3 phase unbalance load, show that the transient period decrease from 0.1s to 0.02s in comparing with PI controller. The experimental results proof that the THD of source currents decrease from 24.8% to 5.4% when using the proposed method.
9
Oramus, Piotr, Tomasz Chmielewski, Tomasz Kuczek, Wojciech Piasecki, and Marcin Szewczyk. "Transient recovery voltage analysis for various current breaking mathematical models: shunt reactor and capacitor bank de-energization study." Archives of Electrical Engineering 64, no. 3 (September 1, 2015): 441–58. http://dx.doi.org/10.2478/aee-2015-0034.
Full textAbstract:
Abstract Electric arc is a complex phenomenon occurring during the current interruption process in the power system. Therefore performing digital simulations is often necessary to analyse transient conditions in power system during switching operations. This paper deals with the electric arc modelling and its implementation in simulation software for transient analyses during switching conditions in power system. Cassie, Cassie-Mayr as well as Schwarz-Avdonin equations describing the behaviour of the electric arc during the current interruption process have been implemented in EMTP-ATP simulation software and presented in this paper. The models developed have been used for transient simulations to analyse impact of the particular model and its parameters on Transient Recovery Voltage in different switching scenarios: during shunt reactor switching-off as well as during capacitor bank current switching-off. The selected simulation cases represent typical practical scenarios for inductive and capacitive currents breaking, respectively.
10
Poznanski, Roman R. "Transient response in a somatic shunt cable model for synaptic input activated at the terminal." Journal of Theoretical Biology 127, no. 1 (July 1987): 31–50. http://dx.doi.org/10.1016/s0022-5193(87)80159-5.
Full textDissertations / Theses on the topic "Transient shunt model"
1
Bukvišová, Zuzana. "Modelování rychlých přechodných dějů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316921.
Full textAbstract:
This thesis deals with the high speed transient modelling in the electrical networks. The introduction of this work discusses mathematical models of the individual devices used in the system and focuses on the line representation. It also contains a more detailed description of Bergeron and frequency dependent line model. The objective of this thesis is to design a network model using ATP-EMTP simulation program. In this model, the switching overvoltage caused by shunt reactor switching and lightning overvoltage are simulated. The thesis thoroughly describes the settings of the components used in the model of analysed network and in conclusion evaluates obtained simulation results in a relation to the insulation coordination.
Conference papers on the topic "Transient shunt model"
1
Saigal, Anil, Robert Greif, and Jane Ng. "Methodology for Modeling of Passive Shunt Damping of Systems With Bonded Piezocomposites." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79338.
Full textAbstract:
An aluminum cantilever beam bonded with 1-3 piezocomposite dampers is modeled by means of ANSYS finite element and SIMULINK simulation softwares. ANSYS currently cannot account for heat dissipation in piezoelectric materials. As such, ANSYS is used to obtain strain energies to be input into the SIMULINK model to investigate the dynamic behavior of the system and calculate the damping ratio. The impact of two different shunting arrangements, a damper in conjunction with a simple resistive electrical circuit in series and parallel, is investigated. In addition, a simply supported beam and a simply supported straight pipe are also analyzed for their wide applications in industry, and as an indication of the utility of this methodology to analyze complex structural configurations. For a typical cantilever beam, energy dissipation and transient analysis are used to calculate the tip displacement as a function of time and the damping ratio. Then using ANSYS, with the parameter BETAD to incorporate damping as a stiffness multiplier, a comparison of the transient results is used to quantify the damping response of aluminum beams with bonded 1-3 piezocomposite dampers. The system loss factor due to the piezoelectric damping is also compared to the inherent loss factor of different beam materials. The results show that circuits in series provides a better damping ratio (0.000581) as compared to circuits in parallel (0.000374). In addition, for different boundary conditions (cantilever, simply supported), the damping ratios (0.000581, 0.000202) and the BETAD values (6.3 E-6, 0.7 E-6), respectively, are functions of the boundary conditions and are not directly related to each other. Finally, damping using 1-3 piezocomposites effectively increases the overall system loss factor by at least 100% to almost 300% as compared to the inherent material damping. In general, this methodology of combining finite element method (ANSYS) and transient modeling tools (SIMULINK) can be used to study damping characteristics of any structural system damped with 1-3 piezocomposites.
2
Van Tiem, Ryan A., Craig J. Hoff, and K. Joel Berry. "Modeling of a Fuel Cell Hybrid Electric Vehicle." In ASME 2005 3rd International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2005. http://dx.doi.org/10.1115/fuelcell2005-74139.
Full textAbstract:
This paper explains the method by which a small “Neighborhood” fuel cell hybrid electric vehicle (FCHEV) was modeled using Matlab/Simulink and validated using National Instruments Data Acquisition equipment and a chassis dynamometer. The vehicle is a modified four-passenger Global Electric Motorcar (GEM), which was designed for city or neighborhood operation where maximum speed limits do not exceed 35 mph. The stock 72-Volt shunt wound GE motor is powered by six 12-Volt Trojan lead-acid batteries. The vehicle was converted to a FCHEV by integrating a Ballard Nexa™ fuel cell module and a Spectrodyne Systems DC-DC converter. These devices act as a constant current range extending supplemental power source. The goals of the creation of the model include predicting motor and battery performance while driving under transient conditions and predicting the range of the vehicle while using one or several fuel cell stacks.
3
Thorat, Manish R., Hanxiang Jin, and Brian Pettinato. "Influence of Shunt Injection on Predicted Rotordynamic Coefficients of a Labyrinth Seal Using Transient CFD." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15820.
Full textAbstract:
Abstract Shunt injection is one of the methods used to improve rotordynamic stability of centrifugal compressors. It involves eliminating swirl by injecting fluid in an intermediate cavity of a seal. The fluid injection is usually directed from the discharge volute or diffuser section of the compressor. In this paper, shunt injection is modeled for a center seal in a back-to-back compressor arrangement. The test case is from an actual machine which was shown to be unstable during a factory loaded mechanical test (as per API standard 617) without shunt injection and stable with shunt injection. The center seal is a tooth-on-rotor type of labyrinth seal. Impeller back-face cavity passages at the entrance and exit of the seal are also modeled. To investigate the influence on shunt injection, models with and without shunt injection geometry are considered. Steady state Computational Fluid Dynamics (CFD) is used to study the influence on steady state characteristics such as leakage rate and swirl ratio. The CFD analysis shows a significant swirl reduction with shunt injection at the injection location. The estimated swirl ratio is 0.55 at the injection location without shunt injection and approximately 0 with shunt injection. Frequency dependent seal rotordynamic coefficients are evaluated using transient CFD. Both translational and moment coefficients are evaluated for the seal and impeller passages. For the case without shunt injection, CFD results show negative (destabilizing) effective damping from the seal at the rotor first damped natural frequency. Shunt injection case shows a positive (stabilizing) estimated effective damping at the frequency of interest. The CFD results are shown to be consistent with the factory test case observations.
4
Okungbowa, Norense, and Trent Brown. "Strategies for Isothermal, Real-Time, Transient Pipeline Models in Shut-In Conditions." In 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78548.
Full textAbstract:
Onshore, liquid pipelines are often modeled with isothermal models. Ignoring thermal effects is justified because thermal effects are of secondary importance and because the data, such as burial depth, soil thermal conductivity, soil heat capacity, and soil density, required to accurately predict thermal behavior in buried pipelines is not known accurately. In addition, run speeds are faster for isothermal models than for rigorous thermal models, which is particularly important in real-time models. One condition where thermal effects become important is when a pipeline is shut-in. Pumps increase the temperature of the fluid, so the fluid temperature is, on average, greater than ambient temperature. When a pipeline is shut-in, the temperature decreases causing a corresponding decrease in pressure. Since an isothermal model does not account for this behavior, the decreasing pressure can be misinterpreted as a leak. This paper discusses a strategy for correcting the model to properly account for the behavior in shut-in conditions. The strategy is applied to real-time pipeline models using Synergi Pipeline Simulator (SPS), although the method is applicable to any isothermal model.
5
Ekweribe, Chiedozie, and Faruk Civan. "Transient Wax Gel Formation Model for Shut-In Subsea Pipelines." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-80046.
Full textAbstract:
Physics of wax gel formation during shut-in is analyzed and described over a cross-section of a typical subsea pipeline. Two regions are identified during this process: the liquid and gel regions. Phase transition is assumed to occur at the liquid-gel interface. Unsteady-state heat and mass transfer models are proposed for each region. Two diffusion streams are evaluated: the dissolved wax molecules moving from the pipe center towards the wall due to temperature gradient and subsequently concentration gradient and the wax molecules diffusing from the liquid-gel interface into the gel deposit. This model is essentially the modification of the model given by Bhat et al [1] which considered transient heat transfer and neglected mass transfer of wax molecules through the gel deposit and the model by Singh et al [2] which considered transient mass transfer of molecules with carbon numbers higher than the critical carbon number (CCN) necessary for wax diffusion into gel deposit but did not consider transient heat transfer effects during the cooling process. This paper presents a transient-state formulation circumventing the limitations of these previous models and better represents the true cooling and gelation process occurring in a shut-in subsea pipeline filled with waxy crude.
6
Hildebrandt, Andre, Magnus Genrup, and Mohsen Assadi. "Steady-State and Transient Compressor Surge Behavior Within a SOFC-GT-Hybrid System." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53892.
Full textAbstract:
Future pressurized Solid Oxide Fuel Cell (SOFC) Gas Turbine Hybrid Systems (HS) promise high efficiency at both full- and part-load on account of the upper and lower SOFC temperature limit and the compressor surge line [1]. The compressor surge constraint is also evident in transient HS operation, caused by the slow transients of SOFC temperature imposed by large SOFC plenum, and fast turbo-machinery transients. This paper presents steady-state and unsteady-state HS modeling and calculation results with regard to surge. The transient compressor and SOFC models have been validated against literature. Calculation results of the coupled SOFC-GT-HS reveal a small operational window in case of unmatched turbine and the critical transient characteristics for HS shut-down.
7
Rancruel, Diego, and Michael von Spakovsky. "Investigation of Control Strategy Development Using an Integrated Model of a SOFC Based APU Under Transient Conditions." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62372.
Full textAbstract:
A typical approach to the synthesis/design optimization of energy systems is to only use steady state operation and high efficiency (or low total life cycle cost) at full load as the basis for the synthesis/design. Transient operation as reflected by changes in power demand, shut-down, and start-up are left as secondary tasks to be solved by system and control engineers once the synthesis/design is fixed. However, start-up and shut-down may be events that happen quite often and, thus, may be quite important in the creative process of developing the system. This is especially true for small power units used in transportation applications or for domestic energy supplies, where the load demand changes frequently and peaks in load of short duration are common. The duration of start-up is, of course, a major factor which must be considered since rapid system response is an important factor in determining the feasibility of solid oxide fuel cell (SOFC) based auxiliary power units (APUs). Start-up and shut-down may also significantly affect the life span of the system due to thermal stresses on all system components. Therefore, a proper balance must be struck between a fast response and the costs of owning and operating the system so that start-up or any other transient process can be accomplished in as short a time as possible yet with a minimum in fuel consumption. In this research work we have been studying the effects of control laws and strategies and transients on system performance. The results presented in this paper are based on a set of transient models developed and implemented for the components of a 5 kW net power SOFC based APU and for the high-fidelity system which results from their integration. The simulation results given below are for two different start-up approaches: one with steam recirculation and component preheating and the second without either. These start-up simulations were performed for fixed values of a number of system-level parameters (e.g., fuel utilization, steam to methane ratio, etc.) and were used to generate sufficient information to permit the development of appropriate control strategies for this critical operating point. These strategies are based on a balance between fuel consumption and response time. In addition, energy buffering hardware was added to the system configuration in order to minimize the effect of transients on fuel cell stack performance and lifetime.
8
R. Ribeiro, Jan Augusto, Maria Leonor S. de Almeida, and Guilherme Gomes dos Santos. "Uma Modelagem Alternativa de Reatores Shunt para Aplicação de Faltas Internas." In Simpósio Brasileiro de Sistemas Elétricos - SBSE2020. sbabra, 2020. http://dx.doi.org/10.48011/sbse.v1i1.2243.
Full textAbstract:
Com base na importância dos reatores shunt para controle das sobretensões no sistema elétrico de potência, este artigo propõe um modelo de reator shunt, por meio do qual é possível aplicar tanto faltas internas do tipo espira-terra quanto entre espiras. Para avaliar o modelo apresentado, o software Alternative Transient Program (ATP) é usado para simular uma linha de transmissão de 230 kV e 380 km com 50% de compensação shunt. Considerando esse sistema, o reator shunt utilizado é submetido a diferentes curtos-circuitos, obtidos pela variação do valor do fator de dispersão e do número de espiras envolvidas na falta. Os resultados obtidos revelam que o modelo proposto figura como uma alternativa apropriada para modelagem do reator shunt, uma vez que por meio dele é possível reproduz corretamente o comportamento das correntes.
9
Gan, Jiaye, Ahmed Abdelwahab, and Viktor Kilchyk. "A Model for System Instability Analysis in a Multi-Stage Intercooled Industrial Compressor." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90098.
Full textAbstract:
Abstract Compression equipment used for industrial applications are typically comprised of multi-stage intercooled compressor stages. The presence of large volume intercoolers between individual stages adds a layer of complexity currently not present in publicly available surge models both in terms of system behavior and recovery analysis. In this work a compressible, temporal, and spatial model is developed in which the conservation equations are solved numerically for each of the system components, i.e. pipes, plenums and heat exchangers, valves, and individual compressor stages. The model can identify the onset of instability on an individual stage basis as well as the switching that can occur between the controlling stages of the instability onset when the operating conditions change, e.g. changes in inlet conditions, intercooler fouling or cooling tower performance reduction, and speed or guide vane changes. The model is therefore used both as a stage stacking model during the compressor stable operation as well as a model of the transient behavior of the system past the stable operation. An inertial model of the compressor drive train is also incorporated to analyze the effects of power transients, e.g. emergency shut down (ESD), on the system behavior. In this article details of the developed model are provided. Several test cases are presented. The model is then used to demonstrate the proper sizing of a vent valve of a base load compressor to meet the required system response specification in a surge event. The developed model represents an improvement over available transient system models in terms of predicting the post stable behavior of multi-stage intercooled compressors.
10
Fang, Tao, Yigang Liu, Jianhua Bai, Huaxing Chen, Shunchao Zhao, Yanyue Li, Ming Pang, Yufei Wang, and Peng Dong. "Transient Heat Transfer Model for Wellbore and Formation of Shut-In Offshore Oil Wells." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. Society of Petroleum Engineers, 2019. http://dx.doi.org/10.2118/196277-ms.
Full textReports on the topic "Transient shunt model"
1
Tawfik, Aly, Deify Law, Juris Grasis, Joseph Oldham, and Moe Salem. COVID-19 Public Transportation Air Circulation and Virus Mitigation Study. Mineta Transportation Institute, June 2022. http://dx.doi.org/10.31979/mti.2021.2036.
Full textAbstract:
COVID-19 may have forever changed our world. Given the limited space and air circulation, potential infections on public transportation could be concerningly high. Accordingly, this study has two objectives: (1) to understand air circulation patterns inside the cabins of buses; and (2) to test the impact of different technologies in mitigating viruses from the air and on surfaces inside bus cabins. For the first objective, different devices, metrics and experiments (including colored smoke; videotaping; anemometers; pressure differentials; particle counts; and 3D numerical simulation models) were utilized and implemented to understand and quantify air circulation inside different buses, with different characteristics, and under different operating conditions (e.g. with windows open and shut). For the second objective, three different live prokaryotic viruses were utilized: Phi6, MS2 and T7. Various technologies (including positive pressure environment inside the cabin, HEPA filters with different MERV ratings, concentrated UV exposure with charged carbon filters in the HVAC systems, center point photocatalytic oxidation technology, ionization, and surface antiviral agents) were tested to evaluate the potential of mitigating COVID-19 infections via air and surfaces in public transportation. The effectiveness of these technologies on the three live viruses was tested in both the lab and in buses in the field. The results of the first objective experiments indicated the efficiency of HVAC system designs, where the speed of air spread was consistently much faster than the speed of air clearing. Hence, indicating the need for additional virus mitigation from the cabin. Results of the second objective experiments indicated that photocatalytic oxidation inserts and UVC lights were the most efficient in mitigating viruses from the air. On the other hand, positive pressure mitigated all viruses from surfaces; however, copper foil tape and fabrics with a high percentage of copper mitigated only the Phi6 virus from surfaces. High-temperature heating was also found to be highly effective in mitigating the different viruses from the vehicle cabin. Finally, limited exploratory experiments to test possible toxic by-products of photocatalytic oxidation and UVC lights inside the bus cabin did not detect any increase in levels of formaldehyde, ozone, or volatile organic compounds. Implementation of these findings in transit buses, in addition to the use of personal protective equipment, could be significantly valuable for protection of passengers and drivers on public transportation modes, possibly against all forms of air-borne viruses.
2
Tawfik, Aly, Deify Law, Juris Grasis, Joseph Oldham, and Moe Salem. COVID-19 Public Transportation Air Circulation and Virus Mitigation Study. Mineta Transportation Institute, June 2022. http://dx.doi.org/10.31979/mti.2022.2036.
Full textAbstract:
COVID-19 may have forever changed our world. Given the limited space and air circulation, potential infections on public transportation could be concerningly high. Accordingly, this study has two objectives: (1) to understand air circulation patterns inside the cabins of buses; and (2) to test the impact of different technologies in mitigating viruses from the air and on surfaces inside bus cabins. For the first objective, different devices, metrics and experiments (including colored smoke; videotaping; anemometers; pressure differentials; particle counts; and 3D numerical simulation models) were utilized and implemented to understand and quantify air circulation inside different buses, with different characteristics, and under different operating conditions (e.g. with windows open and shut). For the second objective, three different live prokaryotic viruses were utilized: Phi6, MS2 and T7. Various technologies (including positive pressure environment inside the cabin, HEPA filters with different MERV ratings, concentrated UV exposure with charged carbon filters in the HVAC systems, center point photocatalytic oxidation technology, ionization, and surface antiviral agents) were tested to evaluate the potential of mitigating COVID-19 infections via air and surfaces in public transportation. The effectiveness of these technologies on the three live viruses was tested in both the lab and in buses in the field. The results of the first objective experiments indicated the efficiency of HVAC system designs, where the speed of air spread was consistently much faster than the speed of air clearing. Hence, indicating the need for additional virus mitigation from the cabin. Results of the second objective experiments indicated that photocatalytic oxidation inserts and UVC lights were the most efficient in mitigating viruses from the air. On the other hand, positive pressure mitigated all viruses from surfaces; however, copper foil tape and fabrics with a high percentage of copper mitigated only the Phi6 virus from surfaces. High-temperature heating was also found to be highly effective in mitigating the different viruses from the vehicle cabin. Finally, limited exploratory experiments to test possible toxic by-products of photocatalytic oxidation and UVC lights inside the bus cabin did not detect any increase in levels of formaldehyde, ozone, or volatile organic compounds. Implementation of these findings in transit buses, in addition to the use of personal protective equipment, could be significantly valuable for protection of passengers and drivers on public transportation modes, possibly against all forms of air-borne viruses.