Variable notation and descriptions
| Variables | Notation | Short description of variables |
|---|---|---|
| SIR and SIV Loops | ||
| Susceptible Population | S | The number of people susceptible to infection |
| Infectious Population | I | The number of susceptible people get infected |
| Recovered Population | R | The number of people recovered from infection |
| Contact Rate | CR | The number of Infectious people contact with susceptible people |
| Average Duration of Infectivity | D | The average length of time people are infectious |
| Infection Rate | IR | Total number of contacts |
| Infectivity | IF | The likelihood of a person contracting an infection |
| Recovery Rate | RR | Total number of people recover from an infection |
| Vaccinated Population | V | The number of vaccinated people |
| Vaccination Rate | VR | Total number of vaccinated people |
| Average Duration of Inoculation | DI | The average length of time people are inoculated |
| VSC Order Fulfillment Loop | ||
| Vaccine Demand | VD | Population eligible for receiving vaccines |
| Vaccine Order Rate | VOR | The total number of vaccine orders for vaccination |
| Vaccine Order Backlog | VOB | Unsatisfied/ unfulfilled vaccine orders |
| Desired Supply Rate for Vaccine | DSRV | Vaccination site's target supply rate |
| Target Delivery Delay | TDD | A certain amount of time required to fill the vaccine orders |
| Vaccine Inventory | VI | Vaccine inventory on hand |
| Vaccine Supply Rate | VSR | The total number of vaccine orders supplied |
| Vaccine Order Fulfillment Ratio | VOFR | A function of maximum vaccine supply rate and desired vaccine supply rate |
| Vaccine Delivery Delay | VDD | The average delay between the placement and the receipt of the vaccination order |
| Inventory Control Loop | ||
| Maximum Vaccine Supply Rate | MVSR | The maximum number of supplies given the VI in stock and VMOPT |
| Vaccine Minimum Order Processing Time | VMOPT | The amount of time it takes between the vaccine order being placed and shipped |
| Vaccine Inventory Coverage Ratio | VICR | The number of days the vaccination site could supply (service level of the vaccination site) |
| Desired Vaccine Inventory | DVI | The volume of inventory required to keep a vaccination site's desired service level of full and dependable delivery |
| Expected Vaccination Demand | EVD | Expected/forecasted demand |
| Vaccine Safety Stock | VSS | Additional vaccine inventory in stock to prevent stockouts |
| Change in Vaccination Demand | CVD | The discrepancy between EVD and the vaccination site’s VOR over a period determined by the TAOR |
| Time to Average Order Rate | TAOR | The time between vaccine orders |
| Vaccine Inventory Gap | VIG | The disparity between DVI and VI |
| Vaccine Inventory Adjustment Time | VIAT | The time required to take the inventory to the desired level |
| Order Placement Loop | ||
| Desired Vaccine Order | DVO | The vaccination site's desired vaccine order |
| Vaccination Site's Order Rate | VSOR | The total number of vaccine orders placed |
| Vaccine Transhipment Rate | VTR | The number of vaccines shipped to vaccination site via transshipment |
| Vaccine Transhipment Delivery Rate | VTDR | The total number of vaccines delivered to vaccination site via transshipment |
| Production Loop | ||
| Desired Production | DP | Desired number of vaccines to be produced |
| Expected Vaccination Site's Demand | EVSD | Expected/forecasted vaccination site's demand |
| Production Release Rate | PRR | The total number of vaccines released for manufacturing |
| Work In Process Inventory | WIPI | The number of vaccines accumulated by difference between PRR and PC |
| Product Completion | PC | The total number of vaccines produced |
| Work in Process Gap | WIPG | The pending production line (the difference between DWIP and WIPAT) |
| Desired Work In Process | DWIP | Desired number of vaccines to be accumulated in the production line |
| Work In Process Adjustment Time | WIPAT | The time it takes to modify WIPG in line with the desired level |
| Manufacturing Lead Time | MLT | The average cycle time for the vaccine production |
| Manufacturer's Inventory | MI | Manufacturer's vaccine inventory on hand |
| Manufacturer's Inventory Gap | MIG | The disparity between DMI and MI |
| Maximum Manufacturer Shipment Rate | MMSR | The maximum number of shipments given the MI in stock and MMOPT |
| Manufacturer Shipment Rate | MSR | The total number of vaccines shipped from Manufacturer |
| Manufacturer Minimum Order Processing Time | MMOPT | The amount of time it takes between the vaccine order being placed and shipped at the manufacturer |
| Closing the Loop | ||
| Vaccine Usage Duration | VUD | Vaccine usage until expiration or expired vaccines which depends on the vaccine’s shelf life |
| Used Vaccine | UV | Used or expired vaccines |
| Uncontrollable Vaccine Disposal | UVD | The flow of used vaccines to disposal due to the limited collection capacity |
| Uncontrollably Disposed Vaccines | UDV | A variable that accumulates the uncontrollably disposed vaccines |
| Collection | ||
| Vaccine Collection Rate | VCR | The flow of used vaccines to the collection and inspection facilities |
| Collected Vaccines | CV | The inventory of collected reused vaccines |
| Collection Capacity | CC | The maximum volume of vaccines handled by the collection and inspection facilities per week |
| Vaccines Accepted for Reuse | VAR | The flow of used products that have passed inspection and are appropriate to be remanufactured |
| Vaccines Rejected for Reuse | VRFR | The flow of used products that have not passed inspection and are appropriate to be remanufactured |
| Inspection Time | IT | The time inspect calculated based on several reuses (remaining non-expired doses) and remaining shelf life |
| Failure Percentage | FR | A percentage of failing in inspection |
| Remanufacturing | ||
| Remanufacturing Capacity | RC | The maximum volume of reused products that can be remanufactured per week |
| Vaccine Remanufacturing Rate | VRR | The flow of remanufactured vaccines |
| Reusable Vaccines | RV | The inventory of used products that passed inspection and are ready to be remanufactured |
| Controllable Vaccine Disposal | CVD | The flow of surplus stock of used vaccines to prevent costly accumulation if there is not enough remanufacturing capacity to handle them |
| Uncontrollable Disposal | UCD | The flow of used vaccines to disposal due to the limited collection capacity |
| Reusable Stock Keeping Time | RST | Unused vaccines for some time |
| Reuse Ratio | RR | The ratio of ERR to the number of EUV |
| Expected Remanufacturing Rate | ERR | The forecast of remanufacturing rate |
| Expected Used Vaccines | EUV | The forecast of used products |
| Vehicle Capacity | ||
| Desired Number of Vehicles | DNV | The desired number of vehicles to transport vaccines |
| Average Capacity of Vehicles | ACV | The average amount of vaccines can be transported by vehicles |
| Vehicle Capacity | VC | The maximum vaccine transshipment rate that is restricted by ACV |
| Number of Available Vehicles | NAV | The discrepancy between VC and VUT |
| Vehicle Used for Transportation | VUT | The number of vehicles used for transshipment |
| Vehicle Adjustment Time | VAT | The time required to prepare the vehicles |
| Transshipment | ||
| Vaccine Transshipment Rate | VTR | The total number of vaccines shipped from vaccine site n to vaccine site k |
| Aggregate Inventory Level | AIL | The total number of the available inventory across all vaccination sites |
| Allocate Inventory | AI | Allocation decision of inventory from available inventory stock at vaccination site n to vaccination site k based on vaccination site k's DVO, MDBV, and AFR |
| Allocation Fill Rate | AFR | If the vaccination site n has available inventory to allocate, the AFR score becomes one, else it is zero |
| Minimum Distance Between Vaccination Sites | MDBV | Ensures the minimum distanced vaccination site k is matched to vaccination site n to allocate vaccines |
| Transshipment Lead Time | TLT | The time that elapses between vaccine transshipment allocation and the delivery at vaccination site k |
| Variables | Notation | Short description of variables |
|---|---|---|
| Susceptible Population | S | The number of people susceptible to infection |
| Infectious Population | I | The number of susceptible people get infected |
| Recovered Population | R | The number of people recovered from infection |
| Contact Rate | CR | The number of Infectious people contact with susceptible people |
| Average Duration of Infectivity | D | The average length of time people are infectious |
| Infection Rate | IR | Total number of contacts |
| Infectivity | IF | The likelihood of a person contracting an infection |
| Recovery Rate | RR | Total number of people recover from an infection |
| Vaccinated Population | V | The number of vaccinated people |
| Vaccination Rate | VR | Total number of vaccinated people |
| Average Duration of Inoculation | DI | The average length of time people are inoculated |
| Vaccine Demand | VD | Population eligible for receiving vaccines |
| Vaccine Order Rate | VOR | The total number of vaccine orders for vaccination |
| Vaccine Order Backlog | VOB | Unsatisfied/ unfulfilled vaccine orders |
| Desired Supply Rate for Vaccine | DSRV | Vaccination site's target supply rate |
| Target Delivery Delay | TDD | A certain amount of time required to fill the vaccine orders |
| Vaccine Inventory | VI | Vaccine inventory on hand |
| Vaccine Supply Rate | VSR | The total number of vaccine orders supplied |
| Vaccine Order Fulfillment Ratio | VOFR | A function of maximum vaccine supply rate and desired vaccine supply rate |
| Vaccine Delivery Delay | VDD | The average delay between the placement and the receipt of the vaccination order |
| Maximum Vaccine Supply Rate | MVSR | The maximum number of supplies given the VI in stock and VMOPT |
| Vaccine Minimum Order Processing Time | VMOPT | The amount of time it takes between the vaccine order being placed and shipped |
| Vaccine Inventory Coverage Ratio | VICR | The number of days the vaccination site could supply (service level of the vaccination site) |
| Desired Vaccine Inventory | DVI | The volume of inventory required to keep a vaccination site's desired service level of full and dependable delivery |
| Expected Vaccination Demand | EVD | Expected/forecasted demand |
| Vaccine Safety Stock | VSS | Additional vaccine inventory in stock to prevent stockouts |
| Change in Vaccination Demand | CVD | The discrepancy between EVD and the vaccination site’s VOR over a period determined by the TAOR |
| Time to Average Order Rate | TAOR | The time between vaccine orders |
| Vaccine Inventory Gap | VIG | The disparity between DVI and VI |
| Vaccine Inventory Adjustment Time | VIAT | The time required to take the inventory to the desired level |
| Desired Vaccine Order | DVO | The vaccination site's desired vaccine order |
| Vaccination Site's Order Rate | VSOR | The total number of vaccine orders placed |
| Vaccine Transhipment Rate | VTR | The number of vaccines shipped to vaccination site via transshipment |
| Vaccine Transhipment Delivery Rate | VTDR | The total number of vaccines delivered to vaccination site via transshipment |
| Desired Production | DP | Desired number of vaccines to be produced |
| Expected Vaccination Site's Demand | EVSD | Expected/forecasted vaccination site's demand |
| Production Release Rate | PRR | The total number of vaccines released for manufacturing |
| Work In Process Inventory | WIPI | The number of vaccines accumulated by difference between PRR and PC |
| Product Completion | PC | The total number of vaccines produced |
| Work in Process Gap | WIPG | The pending production line (the difference between DWIP and WIPAT) |
| Desired Work In Process | DWIP | Desired number of vaccines to be accumulated in the production line |
| Work In Process Adjustment Time | WIPAT | The time it takes to modify WIPG in line with the desired level |
| Manufacturing Lead Time | MLT | The average cycle time for the vaccine production |
| Manufacturer's Inventory | MI | Manufacturer's vaccine inventory on hand |
| Manufacturer's Inventory Gap | MIG | The disparity between DMI and MI |
| Maximum Manufacturer Shipment Rate | MMSR | The maximum number of shipments given the MI in stock and MMOPT |
| Manufacturer Shipment Rate | MSR | The total number of vaccines shipped from Manufacturer |
| Manufacturer Minimum Order Processing Time | MMOPT | The amount of time it takes between the vaccine order being placed and shipped at the manufacturer |
| Vaccine Usage Duration | VUD | Vaccine usage until expiration or expired vaccines which depends on the vaccine’s shelf life |
| Used Vaccine | UV | Used or expired vaccines |
| Uncontrollable Vaccine Disposal | UVD | The flow of used vaccines to disposal due to the limited collection capacity |
| Uncontrollably Disposed Vaccines | UDV | A variable that accumulates the uncontrollably disposed vaccines |
| Vaccine Collection Rate | VCR | The flow of used vaccines to the collection and inspection facilities |
| Collected Vaccines | CV | The inventory of collected reused vaccines |
| Collection Capacity | CC | The maximum volume of vaccines handled by the collection and inspection facilities per week |
| Vaccines Accepted for Reuse | VAR | The flow of used products that have passed inspection and are appropriate to be remanufactured |
| Vaccines Rejected for Reuse | VRFR | The flow of used products that have not passed inspection and are appropriate to be remanufactured |
| Inspection Time | IT | The time inspect calculated based on several reuses (remaining non-expired doses) and remaining shelf life |
| Failure Percentage | FR | A percentage of failing in inspection |
| Remanufacturing Capacity | RC | The maximum volume of reused products that can be remanufactured per week |
| Vaccine Remanufacturing Rate | VRR | The flow of remanufactured vaccines |
| Reusable Vaccines | RV | The inventory of used products that passed inspection and are ready to be remanufactured |
| Controllable Vaccine Disposal | CVD | The flow of surplus stock of used vaccines to prevent costly accumulation if there is not enough remanufacturing capacity to handle them |
| Uncontrollable Disposal | UCD | The flow of used vaccines to disposal due to the limited collection capacity |
| Reusable Stock Keeping Time | RST | Unused vaccines for some time |
| Reuse Ratio | RR | The ratio of ERR to the number of EUV |
| Expected Remanufacturing Rate | ERR | The forecast of remanufacturing rate |
| Expected Used Vaccines | EUV | The forecast of used products |
| Desired Number of Vehicles | DNV | The desired number of vehicles to transport vaccines |
| Average Capacity of Vehicles | ACV | The average amount of vaccines can be transported by vehicles |
| Vehicle Capacity | VC | The maximum vaccine transshipment rate that is restricted by ACV |
| Number of Available Vehicles | NAV | The discrepancy between VC and VUT |
| Vehicle Used for Transportation | VUT | The number of vehicles used for transshipment |
| Vehicle Adjustment Time | VAT | The time required to prepare the vehicles |
| Vaccine Transshipment Rate | VTR | The total number of vaccines shipped from vaccine site |
| Aggregate Inventory Level | AIL | The total number of the available inventory across all vaccination sites |
| Allocate Inventory | AI | Allocation decision of inventory from available inventory stock at vaccination site |
| Allocation Fill Rate | AFR | If the vaccination site |
| Minimum Distance Between Vaccination Sites | MDBV | Ensures the minimum distanced vaccination site k is matched to vaccination site |
| Transshipment Lead Time | TLT | The time that elapses between vaccine transshipment allocation and the delivery at vaccination site k |
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