## Sir graph generator

As the first step in the modeling process, we identify the independent and dependent variables. Renco corporation locations consider two related sets of dependent variables.

The first set of dependent variables counts people in each of the groups, each as a function of time:. The second set of dependent variables represents the fraction of the total population in each of the three categories.

It may seem more natural to work with population counts, but some of our calculations will be simpler if we use the fractions instead.

The two sets of dependent variables are proportional to each other, so either set will give us the same information about the progress of the epidemic. Next we make some assumptions about the rates of change of our dependent variables:. No one is added to the susceptible group, since we are ignoring births and immigration. The only way an individual leaves the susceptible group is by becoming infected. Not all these contacts are with susceptible individuals. Let's see what these assumptions tell us about derivatives of our dependent variables.

Finally, we complete our model by giving each differential equation an initial condition. For this particular virus -- Hong Kong flu in New York City in the late 's -- hardly anyone was immune at the beginning of the epidemic, so almost everyone was susceptible.

Van de graff generator. Board Pattern,11th 12th

We will assume that there was a trace level of infection in the population, say, 10 people. In terms of the scaled variables, these initial conditions are.

The trace level of infection is so small that this won't make any difference. Our complete model is. We emphasize that this is just a guess. In Part 3, we will see how solution curves can be computed even without formulas for the solution functions.

It is common usage in epidemiology to refer to "susceptibles," "infecteds," and "recovereds" rather than always use longer phrases such as "population of susceptible people" or even "the susceptible group. Skip to main content. Search form Search.System Simulation and Analysis. Plant Modeling for Control Design. High Performance Computing. This interactive application explores the classical SIR model for the spread of disease, which assumes that a population can be divided into three distinct compartments - S is the proportion of susceptibles, I is the proportion of infected persons and R is the proportion of persons that have recovered from infection and are now immune against the disease.

Also: View and interact with this app in the MapleCloud! The Classic SIR Model This interactive application explores the classical SIR model for the spread of disease, which assumes that a population can be divided into three distinct compartments - S is the proportion of susceptibles, I is the proportion of infected persons and R is the proportion of persons that have recovered from infection and are now immune against the disease.

Education: Differential Equations.

## Tools and Templates to Create Organizational Charts

Move the slider to rate. Please note that much of the Application Center contains content submitted directly from members of our user community. Although we do our best to monitor for objectionable content, it is possible that we occasionally miss something. If there is something objectionable on this page, please click here to report it.Printer Friendly Version. Many diseases spread from person to person. Some, such as the common cold, are a seasonal nuisance, but others like plague, flu, smallpox, typhus and Ebola have killed thousands and even millions of people.

Yes, millions. During the flu pandemic more than 50 million people died. Also, smallpox killed nearly a half billion people in the centuries before it was eradicated inand the plagues that raced through medieval Europe killed an estimated 25 million people. There has been no major pandemic since but scientists are busy studying how an infectious disease spreads so that they will be prepared to contain the next big outbreak. Spread of some diseases such as malaria is by mosquito bites or other animal to human contacts, but Ebola and other potentially catastrophic diseases spread through transfer of germs from one person to another.

### SIR Epidemic Dynamics

Some contacts â€” and hence exchange of germs - occurs by touching bodily fluids such as sweat, tears, saliva, blood, semen and urine. A more efficient spread occurs by coughing and sneezing that propels germs short distances through the air.

One at a time, person to person contacts might seem a slow way to propagate a disease, but with all the contacts that occur in a large city in a single day the spread can be surprisingly rapid. The way to slow and ultimately stop an infectious disease outbreak is to get people out of contact with each other. How can that happen? We already routinely do it when we get a bad cold. We stay at home, which allows rest to speed up our recovery, and reduces the number of other people who are exposed to us.

## The SIR Model for Spread of Disease - Euler's Method for Systems

In trying to reduce the spread of the enterovirus outbreak some schools closed so that students would not be packed in classrooms where the disease could spread easily. Indeed, the flu killed millions of soldiers, partially because they were near each other in barracks and cramped hospital wards.

Traveling in any public transportation vehicle such as a bus, subway, train or airplane concentrates people into small spaces, making airborne transmission of disease easier, especially if the air is re-circulated. An important way to minimize the spread of a disease within a town is to have people stay home. But also, having people work at home reduces the numbers of customers at cafes and shops so any disease outbreak is also bad for business, as well as for personal health.

The spread of disease from city to city and country to country depends on transportation. Today, the spread of disease across the globe takes only hours or days because spread is largely tied to airplane travel. You may remember that in some countries refused to accept airline passengers who came from parts of Africa where Ebola was rampant.

In addition to these demographic factors, the virulence of the disease itself has to be included in models of disease spread. If a disease makes a lot of people sick, but very few die, as is common with mild winter flu, then the main concern is how the flu will affect work and school â€” how the economy will be impacted by missed days. But for a flu that is deadly, the stakes are much higher, and modeling the disease spread may predict how many hospital beds will be needed, how long the epidemic will last, how many people will become sick, and how many will die.

The models can also evaluate the effectiveness of actions that can be taken to interrupt the spread - for example, vaccinations, school closings, and transportation restrictions. The SIR model is a widely used simple mathematical analysis that provides great insight into an infectious disease outbreak. Three parameters determine how fast and how many people move from category to category: infection rate, recovery rate, and death rate.

The X axis plots time, specifically the number of days since the beginning of the outbreak. The Y axis plots the number of people in each of four categories for each day.In Part 3, we displayed solutions of an SIR model without any hint of solution formulas.

This suggests the use of a numerical solution method, such as Euler's Method, which we assume you have seen in the context of a single differential equation. Nevertheless, we review the basic idea here. Recall the idea of Euler's Method: If we have a "slope formula," i. That is. Thus we have three Euler formulas of the form. In this part we explore the adequacy of these formulas for generating solutions of the SIR model. If your helper application has Euler's Method as an option, we will use that rather than construct the formulas from scratch.

Login Join Give Shops. Halmos - Lester R. Ford Awards Merten M. Author s :. In your helper application CAS worksheet, you will find commands to use the built-in differential equations solver.

Now generate Euler's Method solutions for the three sectors of the population. Superimpose these solutions on the "exact" solutions from Step 1. Do you think the Euler solutions closely track true solutions of the system? Why or why not? What characteristic of Euler's Method causes the approximate solutions to behave the way they do? Now do they closely track true solutions of the system? Find a step size for which the Euler solutions appear to closely track true solutions of the system.Hotel organizational chart for a tourist hotel management of how the hierarchy of a hotel is represented.

You can use as a template to create hotel org charts. The account mapping is nothing but collecting all the customer information needed to sell your products or services, for e.

Tagged: block,account plan,account mapping,account mapping template,account planning tools,account map template. The account mapping is about collecting all the customer information needed to sell your products or services, for ex. Improving workflow is a project in itself.

Therefore a competent team is necessary to monitor and carry out the different tasks. Use an organizational chart listing the job roles and department.

You can use it to highlight the reporting relationships between the team members during the project. Editable matrix org chart template to quickly visualize your cross functional teams. You can customize it online to reflect your organization. Many exporting options to add to PowerPoint or your company website. Tagged: org,chart,tree,structure,hierarchy,org chart templates,org chart examples,organizational cahrt,org chart,matrix org chart,matrix.

A hierarchical organizational structure is the top to bottom chain of command that runs a company or an organization. Edit org chart hierarchy to include your company structure. Embed this org chart in your PowerPoint presentations and in business documentation. Tagged: org,chart,tree,structure,hierarchy,hiearachical,hierachy,hierarchical org structure,org structure.

Organizational structure to highlight the company structure and the hierarchy of the reporting relationships. An effective way to present your organizational structure and management in your business plan. An organizational structure chart template to categorize and list stakeholders. Edit the template and customize it according to your needs.

### Epidemiology: The SIR model

Tagged: stakeholder org chart, stakeholder chart, stakeholder map, stakeholder analysis, organizational structure chart. Stakeholder hierarchy chart to score the influence and the interest of stakeholders.Modeling Infectious Disease Spread with Excel.

Medical researchers and mathematicians have developed a series of sophisticated mathematical models to describe the spread of infectious diseases. But even a simple model is useful to predict how long an outbreak of a disease, for example the flu, will last and how many people will be sickened by it. The oldest and most common model is the SIR model which considers every person in a population to be in one of three conditions:.

This is a compartmental model, with S, I and R being compartments. Every person starts off in a compartment and many move to others over time. Graphically the compartment model looks like the figure below with the rates of movement between compartments given as Greek letters above the arrows indicating direction of movement.

This is a steady-state model with no one dying or being born, to change the total number of people. More sophisticated models allow re-infections. The model also assumes that a disease is passed from person to person. How do you know the values of these parameters? The number of susceptible people S can be the population of a city or town where the outbreak occurs. The number of initially infected people I is a guess unless it is known, for example, that a single traveller brought the disease into a community.

With these parameters, the number of people at any time who are Susceptible, Infected, or Recovered can be calculated with these equations:. The subscript n means the number in one time interval, and n-1 means the number in the previous interval.

So with a time interval of one day, then the first equation:. The number of susceptible people today equals the number who were susceptible yesterday minus the number who become infected today. As long as the disease is spreading, the number not yet infected â€” the remaining susceptibles â€” decreases every day. The reason is that the rate of infection is for each infected person. If 3 people are infected the chance of anyone else becoming infected is 3 times as high as when only 1 person is infected.

So any estimate of the rate of spread of the disease requires knowledge of the infection rate and the numbers of initially infected and initially susceptible people. The number of infected people today I n equals the number who were infected yesterday I n-1PLUS the number of susceptible people who became infected today, MINUS the number of infected yesterday who recovered. At the beginning of an outbreak the number of people getting infected every day is probably larger than the number recovering, so the number of infected will keep rising until more people recover than get infected.A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate electric charge on a hollow metal globe on the top of an insulated column, creating very high electric potentials.

It produces very high voltage direct current DC electricity at low current levels.

It was invented by American physicist Robert J. Van de Graaff in A tabletop version can produce on the order ofvolts and can store enough energy to produce a visible spark.

Small Van de Graaff machines are produced for entertainment, and for physics education to teach electrostatics ; larger ones are displayed in some science museums. The Van de Graaff generator was developed as a particle accelerator for physics research; its high potential is used to accelerate subatomic particles to great speeds in an evacuated tube. It was the most powerful type of accelerator of the s until the cyclotron was developed.

Van de Graaff generators are still used as accelerators to generate energetic particle and X-ray beams for nuclear research and nuclear medicine. Particle-beam Van de Graaff accelerators are often used in a " tandem " configuration: first, negatively charged ions are injected at one end towards the high potential terminal, where they are accelerated by attractive force towards the terminal.

When the particles reach the terminal, they are stripped of some electrons to make them positively charged and are subsequently accelerated by repulsive forces away from the terminal. This configuration results in two accelerations for the cost of one Van de Graaff generator, and has the added advantage of leaving the complicated ion source instrumentation accessible near ground potential.

The voltage produced by an open-air Van de Graaff machine is limited by arcing and corona discharge to about 5 megavolts. Most modern industrial machines are enclosed in a pressurized tank of insulating gas; these can achieve potentials of as much as about 25 megavolts.

A simple Van de Graaff generator consists of a belt of rubber or a similar flexible dielectric material moving over two rollers of differing material, one of which is surrounded by a hollow metal sphere. Comb 2 is connected to the sphere, and comb 7 to ground. The method of charging is based on the triboelectric effectsuch that simple contact of dissimilar materials causes the transfer of some electrons from one material to the other. For example see the diagramthe rubber of the belt will become negatively charged while the acrylic glass of the upper roller will become positively charged.

The belt carries away negative charge on its inner surface while the upper roller accumulates positive charge. Next, the strong electric field surrounding the positive upper roller 3 induces a very high electric field near the points of the nearby comb 2.

At the points, the field becomes strong enough to ionize air molecules, and the electrons are attracted to the outside of the belt while positive ions go to the comb. At the comb 2 they are neutralized by electrons that were on the comb, thus leaving the comb and the attached outer shell 1 with fewer net electrons.

By the principle illustrated in the Faraday ice pail experimenti. Electrostatic induction by this method continues, building up very large amounts of charge on the shell. In the example, the lower roller 6 is metal, which picks negative charge off the inner surface of the belt.

The lower comb 7 develops a high electric field at its points that also becomes large enough to ionize air molecules.