1. E

    Problem finding explicit formulation of series coefficient

    Hi, I am currently working on gas diffusion through membranes and I am having issues finding a coefficient for the ODE's solution, based on the method presented here. My problem concerns the coefficient lambda, appearing after developping Fick's law, given by eq.16 : tan(λn) = (k*SR − δRλn(λn...
  2. S

    linear program formulation

    Hi everyone, Could you help me to model the following constraint in a LP z=1 if x!=y z=0 if x=y knowing that x,y and z are binary decision variables (0/1) we can also express it as: z=x+y case1 z=x-y case2 Thank you in advance
  3. S

    Mathematical formulation of Linear Programming Problem

    A ship has three cargo loads -forward, centre and after. The capacity limits are given: Commodity Weight (in tonne) Volume (in cu. feet) Forward 2000 100000 Centre 3000 135000 After...
  4. M

    Must all models of ZFC (in a standard formulation) be at least countable?

    Must all models of ZFC (in a standard formulation) be at least countable? Why I think this: there are countably many instances of Replacement, and so, if a model is to satisfy Replacement, it must have at least countably many satisfactions of it. Does my question only apply to first-order...
  5. P

    Dif. between analytical solution, mathematical derivation and analytical formulation?

    Hi, I'm doing an assignment and I just want to know the difference between an analytical solution, a mathematical derivation and an analytical formulation. Thanks
  6. S

    Need help writing the logical formulation of statements

    I am needing some help writing the logical formulation of statements. For example, here are some statements: 1. Between any two real numbers there is at least one rational number and one irrational number. 2. If r1 and r2 are any real numbers satisfying r1 < r2, then r1+a < r2+a for each...
  7. M

    Formulation of a min cut problem

    Hello, I am very new to integer linear programming and trying to solve a classical problem at the moment, yet I couldn't find anything similar on the web really. I am working with AMPL (or actually ZIMPL, a subset). I want to calculate the minimum cut of a simple network, by actually...
  8. S

    Variational formulation problem

    Please help me to solve the attached problem
  9. B

    Linear Program constraint formulation

    I need some help in mathematically formulating the following constraint in a LP: machine i must be serviced once every k days The binary variable I'm using is x_{i,j} = 1 if machine i starts service on day j. Thanks
  10. L

    Linear Programming Formulation

    Hi. I need help with this formation of this problem. A highly unethical taxi company is trying to determine the number of staff it requires to cover demand - they are most interested in keeping the number of staff to the barest of minimums to cover projected demand. They are also interested in...
  11. J

    variational formulation of poisson equation

    I am trying to show that a smooth function u:\Omega \rightarrow \mathbb{R} satisfying the poisson equation and a "mixed" boundary condition \alpha u + \frac{\partial u}{\partial n} = 0 on the boundary \partial \Omega where \alpha > 0 is a constant, also satisfies the variational formulation...
  12. V

    I want to the formulation of monent of inertia

    1) moment of inertia of circular cylinder. can u please give me the formulation 2) how to covert MPa into kg. Thank.
  13. J

    finite element formulation of BVP

    I have the weak formulation of a boundary value problem a(u,v)=l(v) (attached in picture form).. How can i construct the finite element approximation to the BVP based on piecewise elements on the subdivision a=X0<X1<...<Xn=b., with uniform spacing h, and show that this gives n+1 equations in...
  14. J

    Weak formulation of Boundary Value Problem

    I have been trying to complete the following question (attached) however I can not find any similar examples anywhere. Does anyone know how I can go about formulating the weak problem from the differential equation??
  15. L

    Differential equation formulation

    Hey all, just had a question about any approach to this problem I have: Find a function f(y) with the property that: for each solution y(x) of dy/dx = f(y), the limiting value lim (x approaches infinity) y(x)=3 if y(0) > 0. I'm not exactly too sure of where to start or go with this. Any help...
  16. D

    dual problem formulation??

    Maximise Z = 2X1 + X2 subject to: X1 + 3X2 <= 25 3X1 + 3X2 = 15 2X1 + X2 >= 4 X1, X2 >= 0