Search found 11 matches
- Wed Dec 24, 2003 7:37 pm
- Forum: SD Mailing List Archive
- Topic: Time Series for Innovations
- Replies: 2
- Views: 6543
Time Series for Innovations
Dear Rutger check http://www.cesaremarchetti.org/dev He is a physicist & system analyst at IIASA and has done a lot of work on the subject I have developed a SW package to analyze time series, also useful best Roberto Vacca, Rome, Italy see also http://www.robertovacca.com From: "Roberto Va...
- Sun Apr 15, 2001 9:57 am
- Forum: SD Mailing List Archive
- Topic: Unwarranted Criticism
- Replies: 16
- Views: 21636
unwarranted criticism
Dear John Sterman: thank you for your SD3408 - very sharp, honest, informative. I used to be a member of the Club of Rome [resigned in 1981, objecting to lack of quality control over current reports) and I did analysis work on WD and on the Mesarovic-Pestel model. Fews people recognized that the lat...
- Sat Apr 15, 2000 3:56 am
- Forum: SD Mailing List Archive
- Topic: Epidemic and S-Shaped
- Replies: 11
- Views: 12235
Epidemic and S-Shaped
Dear John Hayward epidemics are very often modeled very exactly with Volterra-Lotka equations The number x of people who get sick varies proportionally to the product of itself times the number of people who are not sick and are not immune. Call N the total number at the end of the epidemics: dx/dt ...
- Tue Apr 27, 1999 2:10 pm
- Forum: SD Mailing List Archive
- Topic: Modelling a city
- Replies: 3
- Views: 3713
Modelling a city
Dear Gustav: we made a number of math models of cities You can have them from DGXII of the Eur Commission in Brussells. The study was called ACT-VILL and our group is ISIS. If you have trouble locsting the stuff I can send you an abstract and possibly the goods best Roberto Vacca Rome, Italy From: &...
- Mon Apr 26, 1999 5:03 pm
- Forum: SD Mailing List Archive
- Topic: The Participation of Women in Science and Technology
- Replies: 1
- Views: 2490
The Participation of Women in Science and Technology
Dear Dawn: one useful thing for your research is a database. Yoiu may be interested = in looking up Rebi=E8re, A. - LES FEMMES DANS LA SCIENCE. Librairies Nony, Paris 1897 which gives alphabetically the biographies of about 1,000 women in scienc= e, I happen to have a copy. best Roberto Vacca From: ...
- Mon Apr 12, 1999 6:28 pm
- Forum: SD Mailing List Archive
- Topic: Technology Product Obsolescence
- Replies: 1
- Views: 2276
Technology Product Obsolescence
Dear Jerry: s-shaped Volterra-Lotka curves can certainly be used provided one has = available low-noise long time series of data. I have developed a SW package to get best fitting. If you want to try = and send me time series (possibly with @ least a few dozen items AND = showing definite growth or ...
- Wed Apr 29, 1998 7:26 pm
- Forum: SD Mailing List Archive
- Topic: Forecasting accuracy
- Replies: 14
- Views: 31776
Forecasting accuracy
Rome October 29, 1998 Dear John: as I told you when we met in Rome, I think that for any forecasting to = have significance [perhaps to 2011] you need to have accurate and ample = time series on the variables you are considering. Car populations, passen= ger.km, traffic flows and densities, breakdow...
- Fri Apr 24, 1998 4:27 pm
- Forum: SD Mailing List Archive
- Topic: Management Transients
- Replies: 5
- Views: 3526
Management Transients
Rome, March 24, 1998 Dear Tom: Alans last name is Sokal, not Sokol. Appreciate your views on modelling integrity. We are working on a paper on quality of data and grievous consequences on forecasting of quality being low; also methods for assessing noise. In chaos theory one can tell noise from chao...
- Sat Apr 18, 1998 1:25 pm
- Forum: SD Mailing List Archive
- Topic: Energy 2020
- Replies: 11
- Views: 30156
Energy 2020
Many thanks to Tom Fiddaman for the various refs [especially Lindzen]. He is right I standardise time on a scale that has: 1900 =3D 1 2000 =3D 2 2050 =3D 2.5 I dissent on the comment of Maunaloa CO2 data showing a lot of noise: the= RMS errors of the order of 5E-04 in the fit appear to indicate the ...
- Mon Apr 13, 1998 10:28 am
- Forum: SD Mailing List Archive
- Topic: Energy 2020
- Replies: 11
- Views: 30156
Energy 2020
Please find enclosed my answer to JSterman SD1528 and GBackus SD1532 The aim of my note [SD1524] was to call attention to the 1976 DISCONTINUI= TY in atmospheric CO2 [average yearly growth of .95 ppm from 1959 to 76 = and of 1.522 ppm from 76 to 95 --- but I hear now from Mauna Loa that = growth fro...
- Tue Apr 07, 1998 7:34 am
- Forum: SD Mailing List Archive
- Topic: Work on Urban Dynamics
- Replies: 3
- Views: 2816
Work on Urban Dynamics
Rome, Italy March 7, 1998 Dear Gerald: In 1996 we at ISIS [Istituto di Studi per l Informatica e i Sistemi - mc8263@mclink.it] have carried out a modelling study for DGXII of the European Commission in Brussels. The study [called ACT-VILL] analysed [mostly for Rome, but also for Paris and Hamburg]: ...