Bioprotection of transportion and facilities using lumped element model

Abstract

In one embodiment, a ventilation control system includes a processor; a memory; a calculation module to calculate an inverse protection factor for a structure using a lumped element model, the inverse protection factor being an inverse of a protection factor which is a ratio of contaminant which the one or more infected individuals exhale in the structure and contaminant which the uninfected individual inhales in the structure; and a ventilation control module to control a ventilation system to modify air flowing in the structure. The inverse protection factor is calculated based on operating parameters of the ventilation system, arrangement of spaces of the structure, and locations and relative positions of the infected and uninfected individuals in the structure with respect to air flowing in the structure and influenced by the ventilation system. The ventilation control module is configured to control the ventilation system based on the calculated inverse protection factor.

What is claimed is: 
     
         1 . A ventilation control system that influences air flowing in a structure, the ventilation control system comprising:
 a processor;   a memory;   a calculation module configured to calculate an inverse protection factor for the structure using a lumped element model, the inverse protection factor being an inverse of a protection factor which is a ratio of contaminant which the one or more infected individuals exhale in the structure and contaminant which the uninfected individual inhales in the structure; and   a ventilation control module configured to control a ventilation system for the structure to modify air flowing in the structure;   the inverse protection factor being calculated based on operating parameters of the ventilation system, arrangement of spaces of the structure, and locations and relative positions of the infected and uninfected individuals in the structure with respect to the air flowing in the structure and influenced by the ventilation system,   the ventilation control module being configured to control the ventilation system based on the calculated inverse protection factor.   
     
     
         2 . The ventilation control system of  claim 1 ,
 wherein the inverse protection factor is an algebraic expression based on at least one of (i) whether there is airflow between the uninfected individual and the one or more infected individuals, (ii) whether the uninfected individual is upwind or downwind of the one or more infected individuals with respect to airflow in the structure, (iii) air flow rate through a space occupied by the uninfected individual, (iv) fraction of air recirculated in the space occupied by the uninfected individual, (v) transmittance of an air filter used to filter airflow through the space occupied by the uninfected individual, and (vi) breathing rate of the one or more infected individuals.   
     
     
         3 . The ventilation control system of  claim 1 ,
 wherein the inverse protection factor is an algebraic expression based on (i) whether there is airflow between the uninfected individual and the one or more infected individuals, (ii) whether the uninfected individual is upwind or downwind of the one or more infected individuals with respect to airflow in the structure, (iii) air flow rate through a space occupied by the uninfected individual, (iv) fraction of air recirculated in the space occupied by the uninfected individual, and (v) transmittance of an air filter used to filter airflow through the space occupied by the uninfected individual.   
     
     
         4 . The ventilation control system of  claim 1 , having at least one of the following three features:
 wherein if the uninfected individual is upwind of the one or more infected individuals or breathes air directly from the ventilation system, then the inverse protection factor (PF −1 ) is calculated according to   
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         T 
                         ⁢ 
                         η 
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, then the inverse protection factor is calculated according to 
       
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       1 
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       and
 wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, and is located in a space through which only a fraction of the ventilation airflow passes, then the inverse protection factor is calculated according to 
 
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     
                       
                         R 
                         ⁢ 
                         σ 
                       
                       k 
                     
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         1 
                         - 
                         
                           
                             T 
                             ⁢ 
                             η 
                           
                           ( 
                           
                             1 
                             - 
                             
                               σ 
                               k 
                             
                           
                           ) 
                         
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         where
 R=flow rate of the ventilation system, 
 η=fraction of air recirculated, 
 T=Transmittance of an air filter, 
 γ=average breathing rate for a human, 
 σ k =the fraction of ventilation airflow. 
 
       
     
     
         5 . The ventilation control system of  claim 1 ,
 wherein the calculation module is configured to calculate, in real time, a contaminant dose of the uninfected individual in the structure based on the calculated inverse protection factor, according to Dose=(viri exhaled)/(Protection Factor), where the viri exhaled is an amount exhaled by the one or more infected individuals during a time period in which the uninfected individual is in the structure, and compare the calculated contaminant dose with a preset contaminant dose threshold;   wherein if the calculated contaminant dose is greater than the preset contaminant dose threshold, the ventilation control module is configured to change at least one of the arrangement of spaces of the structure, or one or more of the operating parameters of the ventilation system, or locations or relative positions of the infected and uninfected individuals in the structure;   wherein the calculation module is configured to repeat the calculating and comparing, and the ventilation control module is configured to repeat the changing until the calculated contaminant dose is at or below the preset contaminant dose threshold; and   wherein the ventilation control module is configured to control the ventilation system to reduce the contaminant dose based on the changing in real time.   
     
     
         6 . The ventilation control system of  claim 5 ,
 wherein the preset contaminant dose threshold is about 3 viri in presence of an infected individual exhaling at approximately 1200 viri per hour.   
     
     
         7 . The ventilation control system of  claim 5 ,
 wherein in order to reduce the contaminant dose, the ventilation control module is configured to perform in real time at least one of increasing the flow rate R of the ventilation system, decreasing the fraction of air recirculated n, or decreasing the transmittance of the air filter.   
     
     
         8 . The ventilation control system of  claim 1 ,
 wherein the ventilation control module is configured to perform at least one of adjusting a flow rate R of the ventilation system, changing a fraction of air recirculated ri, or modifying a transmittance of an air filter.   
     
     
         9 . A ventilation control method for a structure having air flowing therein which is influenced by a ventilation system, the ventilation control method comprising:
 calculating an inverse protection factor for the structure using a lumped element model, the inverse protection factor being an inverse of a protection factor which is a ratio of contaminant which the one or more infected individuals exhale in the structure and contaminant which the uninfected individual inhales in the structure, the inverse protection factor being calculated based on operating parameters of the ventilation system, arrangement of spaces of the structure, and locations and relative positions of the infected and uninfected individuals in the structure with respect to the air flowing in the structure and influenced by the ventilation system; and   controlling the ventilation system based on the calculated inverse protection factor to modify air flowing in the structure.   
     
     
         10 . The ventilation control method of  claim 9 ,
 wherein the inverse protection factor is an algebraic expression based on at least one of (i) whether there is airflow between the uninfected individual and the one or more infected individuals, (ii) whether the uninfected individual is upwind or downwind of the one or more infected individuals with respect to airflow in the structure, (iii) air flow rate through a space occupied by the uninfected individual, (iv) fraction of air recirculated in the space occupied by the uninfected individual, (v) transmittance of an air filter used to filter airflow through the space occupied by the uninfected individual, and (vi) breathing rate of the one or more infected individuals.   
     
     
         11 . The ventilation control method of  claim 9 ,
 wherein the inverse protection factor is an algebraic expression based on (i) whether there is airflow between the uninfected individual and the one or more infected individuals, (ii) whether the uninfected individual is upwind or downwind of the one or more infected individuals with respect to airflow in the structure, (iii) air flow rate through a space occupied by the uninfected individual, (iv) fraction of air recirculated in the space occupied by the uninfected individual, and (v) transmittance of an air filter used to filter airflow through the space occupied by the uninfected individual.   
     
     
         12 . The ventilation control method of  claim 9 , having at least one of the following three features:
 wherein if the uninfected individual is upwind of the one or more infected individuals or breathes air directly from the ventilation system, then the inverse protection factor (PF −1 ) is calculated according to   
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         T 
                         ⁢ 
                         η 
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, then the inverse protection factor is calculated according to 
       
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       1 
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       and
 wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, and is located in a space through which only a fraction of the ventilation airflow passes, then the inverse protection factor is calculated according to 
 
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     
                       
                         R 
                         ⁢ 
                         σ 
                       
                       k 
                     
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         1 
                         - 
                         
                           
                             T 
                             ⁢ 
                             η 
                           
                           ( 
                           
                             1 
                             - 
                             
                               σ 
                               k 
                             
                           
                           ) 
                         
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         where
 R=flow rate of the ventilation system, 
 η=fraction of air recirculated, 
 T=Transmittance of an air filter, 
 γ=average breathing rate for a human, 
 σ k =the fraction of ventilation airflow. 
 
       
     
     
         13 . The ventilation control method of  claim 9 , further comprising:
 calculating, in real time, a contaminant dose of the uninfected individual in the structure based on the calculated inverse protection factor, according to Dose=(viri exhaled)/(Protection Factor), where the viri exhaled is an amount exhaled by the one or more infected individuals during a time period in which the uninfected individual is in the structure;   comparing the calculated contaminant dose with a preset contaminant dose threshold; and   if the calculated contaminant dose is greater than the preset contaminant dose threshold, changing at least one of the arrangement of spaces of the structure, or one or more of the operating parameters of the ventilation system, or locations or relative positions of the infected and uninfected individuals in the structure, and repeating the calculating, the comparing, and the changing until the calculated contaminant dose is at or below the preset contaminant dose threshold, and controlling the ventilation system to reduce the contaminant dose based on the changing in real time.   
     
     
         14 . The ventilation control method of  claim 13 ,
 wherein the preset contaminant dose threshold is about 3 viri in presence of an infected individual exhaling at approximately 1200 viri per hour.   
     
     
         15 . The ventilation control method of  claim 13 , further comprising:
 in order to reduce the contaminant dose, performing in real time at least one of increasing the flow rate R of the ventilation system, decreasing the fraction of air recirculated n, or decreasing the transmittance of the air filter.   
     
     
         16 . The ventilation control method of  claim 9 ,
 wherein controlling the ventilation system comprises performing at least one of adjusting a flow rate R of the ventilation system, changing a fraction of air recirculated n, or modifying a transmittance of an air filter.   
     
     
         17 . A computer program product for controlling a ventilation system that influences air flowing in a structure, the computer program product embodied on a non-transitory tangible computer readable medium, comprising:
 computer-executable code for calculating an inverse protection factor for the structure using a lumped element model, the inverse protection factor being an inverse of a protection factor which is a ratio of contaminant which the one or more infected individuals exhale in the structure and contaminant which the uninfected individual inhales in the structure, the inverse protection factor being calculated based on operating parameters of the ventilation system, arrangement of spaces of the structure, and locations and relative positions of the infected and uninfected individuals in the structure with respect to the air flowing in the structure and influenced by the ventilation system; and   computer-executable code for controlling the ventilation system based on the calculated inverse protection factor to modify air flowing in the structure.   
     
     
         18 . The computer program product of  claim 17 , having at least one of the following three features:
 wherein if the uninfected individual is upwind of the one or more infected individuals or breathes air directly from the ventilation system, then the inverse protection factor (PF −1 ) is calculated according to   
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         T 
                         ⁢ 
                         η 
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, then the inverse protection factor is calculated according to 
       
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     R 
                   
                   ⁢ 
                   
                     ( 
                     
                       1 
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       and
 wherein if the uninfected individual is downwind of the one or more infected individuals or does not breathe air directly from the ventilation system, and is located in a space through which only a fraction of the ventilation airflow passes, then the inverse protection factor is calculated according to 
 
       
         
           
             
               
                 
                   PF 
                   
                     - 
                     1 
                   
                 
                 = 
                 
                   
                     γ 
                     
                       
                         R 
                         ⁢ 
                         σ 
                       
                       k 
                     
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         1 
                         - 
                         
                           
                             T 
                             ⁢ 
                             η 
                           
                           ( 
                           
                             1 
                             - 
                             
                               σ 
                               k 
                             
                           
                           ) 
                         
                       
                       
                         1 
                         - 
                         
                           T 
                           ⁢ 
                           η 
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
         where
 R=flow rate of the ventilation system, 
 η=fraction of air recirculated, 
 T=Transmittance of an air filter, 
 γ=average breathing rate for a human, 
 σ k =the fraction of ventilation airflow. 
 
       
     
     
         19 . The computer program product of  claim 17 , further comprising:
 computer-executable code for calculating, in real time, a contaminant dose of the uninfected individual in the structure based on the calculated inverse protection factor, according to Dose=(viri exhaled)/(Protection Factor), where the viri exhaled is an amount exhaled by the one or more infected individuals during a time period in which the uninfected individual is in the structure;   computer-executable code for comparing the calculated contaminant dose with a preset contaminant dose threshold; and   computer-executable code for, if the calculated contaminant dose is greater than the preset contaminant dose threshold, changing at least one of the arrangement of spaces of the structure, or one or more of the operating parameters of the ventilation system, or locations or relative positions of the infected and uninfected individuals in the structure, and repeating the calculating, the comparing, and the changing until the calculated contaminant dose is at or below the preset contaminant dose threshold, and controlling the ventilation system to reduce the contaminant dose based on the changing in real time.   
     
     
         20 . The computer program product of  claim 19 , wherein the preset contaminant dose threshold is about 3 viri in the presence of an infected individual exhaling at approximately 1200 viri per hour, the computer program product further comprising:
 computer-executable code for, in order to reduce the contaminant dose, performing in real time at least one of increasing the flow rate R of the ventilation system, decreasing the fraction of air recirculated η, or decreasing the transmittance of the air filter.