this blagojevich scandal is a mess now....i always question these scandals where all the blame games are functional on just one actor i.e. the person under the microscope of media. In this scandal that is governor blagojevich....I wonder was he the only person playing bad....i am afraid by just blaming him for everything we might be trying to clap with only one hand which is not only impossible but also so unfair.
If blagojevich took bribe-offers...the other side of this crime scene would show us exactly who offered him bribe.
If blagojevich was asking for a price tag on a senate seat...who was willing to bid higher...
if he was talking crap on phone...who was on the otherside of the phone...
i believe for a fair trial's sake we must see other names tagged to this corruption scandal than just mr. blagojevich.
Saturday, December 13, 2008
Thursday, December 11, 2008
route choice and genetic algortihm based simulations for control optimization
route choice is a system derived component where it could depend on many variables starting from a synchronic option available to users through advanced ITS devices or through external factros.
For example, a set of competing objectives will always encounter when we try to design and implement a framework using a complex system based on any heuristic approach. Be it a game theory problem, a problem initiated by operations management theory, or a simple logit math where we use utilities to compute the probablities, the competing objectives will always add complexities to the script in hand.
Another good example of competing objective problem is global air traffic system where the operations manager would optimize the system based on what is best for all the operators in the air traffic system. On the other hand, the traveler may choose his route regardless of what is best for the whole traffic system. Instead the traveler may opt for the route that is most congested, but shortest for him. It appears that there is a parallel existence of user equilibrium and susytem optimum here.
The question then would be if the equilibrium state would exist in a given traffic system; this question may open a bundle of many unanswered questions that are only theoretically investogated in the past by researchers. Some key questions that come to my mind at least include
1. Does the equilibrium state exist in global network of air traffic system?
2. Is there existence of User Equilibrium, and System Optimum? Do they co-exist?
3. Can a real life air traffic system be simulated to get these equilibrium conditions, and how do we regress the benefits of this equilibrium?
4. How the equilibrium system can take of the burden of high air traffic off of some of the nation's busiest airports...or may be in some cases world's busiest airports?
5. How does it help in terms of golbal environment, and energy savings?
6. Are we expecing a change in technology in near future?
In any case real life simulation of these airtraffic conditions are necessary to understand the benefits of UE and SO flows which are being tested on theoretical levels right now by the researchers.
It could be agood research extension of my doctoral research work.
For example, a set of competing objectives will always encounter when we try to design and implement a framework using a complex system based on any heuristic approach. Be it a game theory problem, a problem initiated by operations management theory, or a simple logit math where we use utilities to compute the probablities, the competing objectives will always add complexities to the script in hand.
Another good example of competing objective problem is global air traffic system where the operations manager would optimize the system based on what is best for all the operators in the air traffic system. On the other hand, the traveler may choose his route regardless of what is best for the whole traffic system. Instead the traveler may opt for the route that is most congested, but shortest for him. It appears that there is a parallel existence of user equilibrium and susytem optimum here.
The question then would be if the equilibrium state would exist in a given traffic system; this question may open a bundle of many unanswered questions that are only theoretically investogated in the past by researchers. Some key questions that come to my mind at least include
1. Does the equilibrium state exist in global network of air traffic system?
2. Is there existence of User Equilibrium, and System Optimum? Do they co-exist?
3. Can a real life air traffic system be simulated to get these equilibrium conditions, and how do we regress the benefits of this equilibrium?
4. How the equilibrium system can take of the burden of high air traffic off of some of the nation's busiest airports...or may be in some cases world's busiest airports?
5. How does it help in terms of golbal environment, and energy savings?
6. Are we expecing a change in technology in near future?
In any case real life simulation of these airtraffic conditions are necessary to understand the benefits of UE and SO flows which are being tested on theoretical levels right now by the researchers.
It could be agood research extension of my doctoral research work.
Wednesday, December 3, 2008
activity based route choice solutions
i wonder how activity based aggregate models could be useful?...Activity based models are data intensive; we dont have that kind of data available...similarly, even if some region in the united states used activity based models, my question to them would be how much of a difference it made to their projections as compared to when they used regular gravity model or any other combination of route choice model. If thedifference is not much, then how do they justify activity based models?
My personal thought on this issue is that Activity based models are only good in combined traffic assignment and control framework (CTAC), and that too only if we use dynamic assignment process. Otherwise, activity based models will get stale soon and the researchers will have to come up with some new idea to do projections.
My personal thought on this issue is that Activity based models are only good in combined traffic assignment and control framework (CTAC), and that too only if we use dynamic assignment process. Otherwise, activity based models will get stale soon and the researchers will have to come up with some new idea to do projections.
complex aggregate route choice models and the calibration issues
I was involved in a technical review of adjusted projections for a region. To my surprise, some of the technical users were expecting higher numbers for some of the assigned functional classes. One of the common suggestions tend to dis like differential projections stating the projections from the calibrated models should be higher. Well, there are many questions that come to mind when we look at this assumption. Some of them include:
1) What is the average annual growth rate of demographics especially related to the model inputs for the region where lower forecasts are observed?
2) How about some of the newer infrastructure development projects added to the existing landuse; some of those projects if large enough may change the framework of the trip generation process.
3) How about the synchronic inertia that exists between the mutual interaction of these new projects, diverse route choice, and socio-economic characteristics.
In any case, throwing the blames on mathematical models always sound easy; in reality the picture may show something different.
It is therefore important to have validated input data; especially the demographics should be validated thorougly. The complex models though calibrated and validated, are heavily dependent on input data.....
I hope we will be able to explain this to the people in professional practice one day where they will not expect model to be the "solution generator", in stead they would take it as one of the many available tools used in the infrastructure planning process.
1) What is the average annual growth rate of demographics especially related to the model inputs for the region where lower forecasts are observed?
2) How about some of the newer infrastructure development projects added to the existing landuse; some of those projects if large enough may change the framework of the trip generation process.
3) How about the synchronic inertia that exists between the mutual interaction of these new projects, diverse route choice, and socio-economic characteristics.
In any case, throwing the blames on mathematical models always sound easy; in reality the picture may show something different.
It is therefore important to have validated input data; especially the demographics should be validated thorougly. The complex models though calibrated and validated, are heavily dependent on input data.....
I hope we will be able to explain this to the people in professional practice one day where they will not expect model to be the "solution generator", in stead they would take it as one of the many available tools used in the infrastructure planning process.
Subscribe to:
Posts (Atom)
