Exercises 25—30 refer to a situation in which models similar to the predator-prey population models arise. Suppose A and B represent two substances that can combine to form a new substance C (chemists would write A + B
25. Write a system of differential equations that models the evolution of a(t) and b(t). Be sure to identify and describe any parameters you introduce.
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Chapter 2 Solutions
Differential Equations
- 23. Consider a simple economy with just two industries: farming and manufacturing. Farming consumes 1/2 of the food and 1/3 of the manufactured goods. Manufacturing consumes 1/2 of the food and 2/3 of the manufactured goods. Assuming the economy is closed and in equilibrium, find the relative outputs of the farming and manufacturing industries.arrow_forwardConsider the dynamical system Yk=1 = log (yk) + Yk- Which of the following statements is true about the dynamical system? O The dynamical system has infinite fixed points. The dynamical system has only one fixed points. The dynamical system has.no fixed points.arrow_forwardIndicate which of the statement(s) below is(are) true: (a) y(t) = 3 x(t) is a linear expression %3D (b) y(t) = r(t+2) is a causal system %3D (c) y(t) = K- (t – 2) is memoryless and causal %3D O a. All of them are TRUE O b. (a) is the only TRUE statement O c. (a) and (b) are TRUE O d. (b) and (c) are TRUEarrow_forward
- Denote the owl and wood rat populations at time k by xk Ok Rk and R is the number of rats (in thousands). Suppose Ok and RK satisfy the equations below. Determine the evolution of the dynamical system. (Give a formula for xx.) As time passes, what happens to the sizes of the owl and wood rat populations? The system tends toward what is sometimes called an unstable equilibrium. What might happen to the system if some aspect of the model (such as birth rates or the predation rate) were to change slightly? Ok+ 1 = (0.1)0k + (0.6)RK Rk+1=(-0.15)0k +(1.1)Rk Give a formula for XK- = XK C +0₂ , where k is in months, Ok is the number of owls,arrow_forwardAn ecologist models the interaction between the tree frog (P) and insect (N) populations of a small region of a rainforest using the Lotka-Volterra predator prey model. The insects are food for the tree frogs. The model has nullclines at N=0, N=500, P=0, and P=75. Suppose the small region of the rainforest currently has 800 insects and 50 tree frogs. In the short term, the model predicts the insect population will • and the tree frog population will At another point time, a researcher finds the region has 300 insects and 70 tree frogs. In the short term, the model predicts the insect population will * and the tree frog population willarrow_forwardConsider the discrete-time dynamical system modeling the concentration of a chemical in a lung. (Note: round all values at the end of the calculations and use 4 decimal places.)ct+1 = (1-p)ct + pβLet V = 2 L, W = 1 L, and β = 6 mmol/LIf c0 = 7 mmol/L, iterate to find the following values:c1 = ____mmol/Lc2 = ____mmol/Lc3 = ____mmol/Lc4 = ____mmol/LFind the equilibrium of this system:c* = ____mmol/Larrow_forward
- Consider the example of injection moulding of a rubber component as shown in Figure Q3(b). The process engineer would like to optimise the strength of the component by optimising the following factors: temperature = 190°C and 210°C, pressure = 50 MPa and 100 MPa, and speed of injection = 10 mm/s and 50 mm/s. What type of mathematical model that the engineer can develop if the relationship is linear and no interactions are significant? Write down the general equation that relates the strength of the component with the process factors.arrow_forwardHermann Ebbinghaus (1850–1909) pioneered the study of memory. A 2011 article in the Journal of Mathematical Psychology presents the mathematical model R(t) = a + b(1 + ct)−? for the Ebbinghaus forgetting curve, where R(t) is the fraction of memory retained t days after learning a task; a, b, and c are experimentally determined constants between 0 and 1; ? is a positive constant; and R(0) = 1. The constants depend on the type of task being learned. (a) What is the rate of change of retention t days after a task is learned?arrow_forwardSection 3.1 1. Rewrite the specified linear system in matrix form. 2. Rewrite the specified linear system in component form. dx = 2x + y dt dx dt dy dy = x +y dt dtarrow_forward
- Consider the discrete-time dynamical system modeling the concentration of a chemical in a lung. (Note: round all values at the end of the calculations and use 4 decimal places.) ct+1 = (1 - p)ct + pβ Let V = 2 L, W = 1 L, and β = 6 mmol/L If c0 = 7 mmol/L, iterate to find the following values: c1 = ____mmol/Lc2 = ____mmol/Lc3 = ____mmol/Lc4 = ____mmol/Larrow_forwardTwo very large tanks A and B are partially filled with 100 gallons of brine each. Initially, 100 pounds of salt are dissolved in the solution in tank A and 50 pounds of salt are dissolved in the solution in tank B. The system is closed, since the well-mixed liquid is pumped only between the tanks as shown in the figure. 1. Use the information in the figure to construct a mathematical model for the number of pounds of salt x1(t) and x2(t) at time "t" in tanks A and B, respectively. 2. Find a relationship between the variables x1(t) and x2(t) that holds at time «t». 3. Explain why this relationship makes intuitive sense. 4. Use this relationship to help find the amount of salt in tank B at t = 30 min.arrow_forwardQ.4 Baiji north Refinery use kirkuk crude oil(API=36) with total flowrate 150000 BBL/ Day(the price of one BBI of crude oil=87000 Iraqi Dinar).It has the following products: Gasoline 20%(one litre price=450 Iraqi Dinar),Kerosine 15% (one litre price=150 Iraqi Dinar),Gas oil 20%(one litre price-400 Iraqi Dinar).and 45% remaining is Black oil(one litre price-50 Iraqi Dinar). Is this Refinery Win or Lose?arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage LearningCalculus For The Life SciencesCalculusISBN:9780321964038Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.Publisher:Pearson Addison Wesley,
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