I have a MSc in physics from the University of Oslo and a PhD in control engineering from NTNU in Trondheim (mainly modelling, I am not much of a control engineer). My main interests are mathematical modelling, numerical methods, and thermodynamics. I worked in the petroleum and chemical process industries for some 35 years and I am now semi-retired

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Increasing precision of second order boundary value problem

Your asymptotic expansion solution seems to have zero slope at y = 0. This implies that the second derivative is zero and the s...

Increasing precision of second order boundary value problem

Your asymptotic expansion solution seems to have zero slope at y = 0. This implies that the second derivative is zero and the s...

ongeveer 15 uur ago | 0

Solved

Place wastewater treatment processes in the correct order

There are many technologies for treating wastewater. For example, grit chambers are used to remove heavy solids, filtration is u...

6 dagen ago

Solved

Maximize the production in a plant within equipment capacity

The goal of a certain manufacturing company is to maximize its production of goods per day. In the production flow, there is a s...

7 dagen ago

Solved

Trace the path of a harmful chemical in an ecological network

An ecological network consists of the cycles of nature, such as the water cycle, the carbon cycle, the oxygen cycle, etc. Due to...

7 dagen ago

Solved

Count the number of reaction chains achievable in T mins

This problem is related to Problem <45467>. Let's denote a list of *N* compounds as 1, 2, ..., *N*. You are then given a list...

8 dagen ago

Solved

Find the fastest reaction chain to reach a target compound

This problem is related to Problem <45470>. Let's denote a list of *N* compounds as 1, 2, ..., *N*. You are then given a list...

10 dagen ago

Solved

List the households affected by leaks in water distribution

Consider the following water distribution network, where water is pumped uni-directionally from left to right: 8...

11 dagen ago

Solved

Design a minimum-cost cable network for a power grid

You are given the 2-D point locations ( _xi_ , _yi_ ) of *N* _components_ of a power grid. These _components_ include power sour...

13 dagen ago

Solved

Propagate the effects of a blockage in a chemical plant

From the perspective of flow, a chemical plant can be described by a collection of _nodes_ and _edges_. _Nodes_ are points where...

14 dagen ago

Solved

Pitting corrosion on a metal plate: Find the largest pit

You are given an N x M matrix of _ones_ and _zeros_, which represents an image of a rectangular metal plate taken from the hull ...

15 dagen ago

Solved

Pitting corrosion on a metal plate: Count the number of pits

You are given an N x M matrix of _ones_ and _zeros_, which represents an image of a rectangular metal plate taken from the hull ...

15 dagen ago

Solved

Better Index Number

Let's say you want to save many, many files and append these files with a certain sortable index number. As you probably know, y...

17 dagen ago

Solved

Smallest n, for n! to have m trailing zero digits

For given positive integer n, its factorial often has many trailing zeros, in other words many factors of 10s. In order for n! t...

17 dagen ago

Solved

Whole Number Un-Concatenator

Write a function that accepts an integer and an index digit and returns a vector containing two integers which are the leading a...

19 dagen ago

Solved

Whole Number Concatenator

Write a function that concatenates whole numbers. For example: numcat(111,222) should return 111222 numcat(1,2,3,4,5) s...

19 dagen ago

Solved

The number of trailing zero digit of a factorial

For given positive integer n, take factorial of that number. How many trailing zeros does it have? Example: factorial(11) = 3...

20 dagen ago

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The last non-zero digit of a factorial

For given positive integer n, what is the last non-zero digit of n!? Example: factorial(11) = 39916800 Last non-zero d...

21 dagen ago

Solved

Permutation Via Multiplication

Given two numbers a and b, determine if the product ab is a permutation of the digits of a. For example, this is always true for...

21 dagen ago

Solved

Lunar Arithmetic (Multiplication)

<https://oeis.org/A087061 OEIS link for a description of lunar arithmetic> Simply take the larger digit when adding and take ...

22 dagen ago

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Lunar Arithmetic (Addition)

<https://oeis.org/A087061 OEIS link for a description of lunar arithmetic> Simply take the larger digit. Example 1: ...

22 dagen ago

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Muphry's Law of MATLAB

You're running some simple multiplication problems through MATLAB for error checking purposes, but nothing seems to come up with...

23 dagen ago

Solved

Convert from Base 10 to base 5

Convert the input number from base 10 into base 5: for example: if a(in base 10)= 5 then a(in base 5)= 10

23 dagen ago

Solved

Expand 10^n to Powers of 4

Given an integer n, return the coefficients c = [c_n,c_n-1,...,c_0] Such that 10^n = c_n*4^(n) + c_n-1*4^(n-1...

23 dagen ago

Solved

Numbers on 7-segment

This is a 7-segment: _ |_| |_| It's a 3-by-3 char matrix.It has made by 3 characters: '_' , '|' and ' ' (space...

24 dagen ago

Solved

Pattern Sum

Write a function which receives two single digit positive integers, (k and m) as parameters and calculates the total sum as: k...

27 dagen ago

Solved

Still more miles to go before I sleep

It's time for more odometer fun. Last problem, my car's odometer hit 56789. It's coming up on 111111 now, which (barring a maj...

27 dagen ago

Solved

Find the next prime number

Find the next prime number or numbers for given n. For example: n = 1; out = 2; or n = [5 7]; out = [7 11]; ...

29 dagen ago

Solved

Make a vector of prime numbers

Input(n) - length of vector with prime numbers Output(v) - vector of prime numbers Example: * n=1; v=2 * n=3; v=[2 3 5...

29 dagen ago

Solved

Largest Twin Primes

<http://en.wikipedia.org/wiki/Twin_prime Twin primes> are primes p1, p2 = p1 + 2 such that both p1 and p2 are prime numbers. Giv...

29 dagen ago

Solved

Mersenne Primes

A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

29 dagen ago