OperationsResearch.com

Posts Tagged ‘Model’

Product Description
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
The vehicle scheduling problem, arising in public transport bus companies, addresses the task of assigning buses to cover a given set of timetabled trip… More >>

A time-space network based exact optimization model for multi-depot bus scheduling

Product Description
High Quality Content by WIKIPEDIA articles! In queueing theory, a queueing model is used to approximate a real queueing situation or system, so the queueing behaviour can be analysed mathematically. Queueing models allow a number of useful steady state performance measures to be determined, including: * the average number in the queue, or the system, * the average time spent in the queue, or the system, * the statistical distribution of those numbers or… More >>

Queing Model: Queueing Theory, Kendall’s Notation, Markov Property, Erlang Distribution, Degenerate Distribution, Phase-Type Distribution, Markov Chain, Stochastic

Due to the number of inquiries after my first posting “Website traffic estimation: is there…” I’ve decided to share my forecasting excel model.

To download: http://www.scribd.com/doc/7668443/Traffic-Estimation-Model-1

IMPORTANT

1) Linear Function: y = 8E+09x + 49771
2) 2nd degree polinomic function: y = -1E+13×2 + 1E+10x – 3272,2
3) For the part of the curve that corresponds to websites with an Alexa traffic rank below 100.000, the function used is an average of the polinomic and linear functions

Two functions are used to calculate traffic. This could be upgraded, corrected and improved with more data points or sources of datapoints.

Please if you know any public source of reliable data of historic data on traffic, or have any comments email me at pedroneiraf@gmail.com

4) Cells with yellow background ARE NOT Alexa’s 3 month average reach. This input was distorted, so before inputing the data directly from Alexa, it has to be corrected
5) The way in which this data is “corrected” is by a simple cross-multiplication aproximation to the nearest upper value in the list (the closest upper white cell).
6) This function will not work well for recently created websites.
7) This material is for non-commercial use only. Any usage of these functions or part of this excel sheet should quote the source.

The results I’ve got so far with this function have an average error of 7%, although it has to be said that in some cases, the error might be up to 40%. It has worked for me so far 80% of the time with an error of less than 15%, which is more than acceptable considdering the errors wound in other tools like the web Traffic Estimate. If you have a website and know your numbers, just compare and see the difference.

Please, this model is just a starting point, that needs to be upgraded, corrected and improved with all your comments…. Any suggestions ???

Town A is 30 kms east of town B. “Jo” drives to A twice a week, and B once a week. Where is the best place to have a house built so that travelling time will be minimised?
Assuming that house can be built anywhere on the straight line between A and B, I need to devise a formula, differentiate and set to 0 so that I can find the optimum place to build. The problem is, my formulas either differentiate to a number value or involve “speed” which is unknown. I’m missing something somewhere and would appreciate any suggestions!
Once I’ve solved this, I then have to take into account two journeys to town C situated 50kms north of town B, so the house would be built somwhere in the right angled triangle ABC.
Thanks in advance to anyone who could point me in the right direction!

Dear all, Please send me if you have a pdf format or scanned attachment or text that shows the Optimization Model for Operation of Aswan High Dam Reservoir. While surfing the internet, I noted there is a book on this issue. I need to know the process of formulating an optimization model for the operation of the Aswan High Dam Reservior.

A tutorial video clip describing model building in Management Science.

Astrophysicists using supercomputers to simulate the Big Bang have a new mathematical tool to model the early universe. Researchers have built a computer model of the “Dark Ages.” The model — successfully tested on two supercomputers — tightly couples physical processes present during cosmic reionization. Resulting simulations when scientists model various scenarios are highly accurate, numerically stable and computationally scalable to the largest supercomputers.

View full post on ScienceDaily: Mathematical Modeling News

A multiple linear regression model is developed and assessed. SPSS output is provided (not generated). The model uses NHL data from the 200708 season to determine factors that may explain the players performance.

Scientists have found a unified model of human insurgency that can estimate the timing and strength of insurgent attacks in present and future wars.

View full post on ScienceDaily: Mathematical Modeling News

Researchers have developed a computer model that explains why those drugs (which include rapamycin and its analogs as well as paclitaxel) can accumulate in the arteries and cause blood clots.

View full post on ScienceDaily: Mathematical Modeling News

Using a new mathematical model of heart cells, investigators have shown how activation of a critical enzyme, calmodulin kinase II (CaM kinase), disrupts the electrical activity of heart cells. By targeting this enzyme’s activity, it may be possible to prevent or treat heart disease and associated electrical rhythm disturbances.

View full post on ScienceDaily: Mathematical Modeling News

Recent bank failures point to the continuing need for vigilance by regulators and investors. Now, a new report discusses the possibility of an early-warning system that spots the outliers before they fail.

View full post on ScienceDaily: Mathematical Modeling News

The human brain is made up of 100 billion neurons — live wires that must be kept in delicate balance to stabilize the world’s most magnificent computing organ. Too much excitement and the network will slip into an apoplectic, uncomprehending chaos. Too much inhibition and it will flatline. A new mathematical model describes how the trillions of interconnections among neurons could maintain a stable but dynamic relationship that leaves the brain sensitive enough to respond to stimulation without veering into a blind seizure.

View full post on ScienceDaily: Mathematical Modeling News

What does it mean when expert psychiatric witnesses in a court case reach opposing conclusions on the same sets of evidence? A new study suggests via mathematical modeling that both analyses can be completely accurate.

View full post on ScienceDaily: Mathematical Modeling News

Researchers have developed the first mathematical model in cardiology and emergency medicine to more quickly and reliably diagnose acute heart failure in emergency room patients. Research findings have been shown to help physicians diagnose AHF with greater accuracy.

View full post on ScienceDaily: Mathematical Modeling News

Researchers are utilizing computational models to study how the brain’s chemicals and synaptic mechanisms, or connections between neurons, react to cocaine addiction and what this could mean for future therapies.

View full post on ScienceDaily: Mathematical Modeling News