Re: Elementary Math for the Traffic ProblemsRe: Mr. Sonnet

["DiemQuynh Nguyen" <diemquynhng@hotmail.com>]

Cha`o ba'c Sonnet,
DDe^` nghi. ba'c vie^'t tie^'ng Vie^.t ddi, tie^'ng Anh to^i vo^'n do^'t ma` 
ddo.c ba'c vie^'t tie^'ng Anh sai ve^` ca(n ba?n nhu* the^' na`y to^i kho^ng 
hie^?u ba'c vie^'t gi` ca?!
Ba'c la`m o*n vie^'t la.i giu'p nhe'
DX


From: Sonnet Nguyen <sonnet@white.cft.edu.pl>
>Reply-To: vnsa@list-server.net
>To: Aiviet Nguyen <aiviet2@YAHOO.COM>
>CC: VNSA <vnsa@List-Server.net>
>Subject: Re: Elementary Math for the Traffic Problems
>Date: Wed, 27 Oct 1999 14:50:52 +0200 (CEST)
>
>Hi d/c AV & lovers of Games,
>
>I'd like to infor that Mr. Aiviet has gived a constructive model
                                   ^^^^^^^^^
DX: DDo.c dde^'n dda^y to^i pha?i ngu*`ng va` go'p y' vo*'i ba'c vi` kho^ng 
pha?i la` lo^~i typo , ne^n kho^ng bie^'t ba'c vie^'t co' nghie^m tu'c 
kho^ng?.

>(plus speculation for the next) /quoted below/ and he wins 1/2
>champagne bottle plus a title "smart guy" from me :-))  Why only
>1/2 bottle ?
>Not only because his model is still too primitive, requires further
>developments, but also his designing style is unproper :-))
>   Speculations of TA are out of the context, so no further comments
>of mine on it are needed :-)
>  Only Aiviet's second model is worth for my comments because the first
>model (namely social, V.H.L, banana, B.A.V. or whatever you want:-)
>is impractical and ... very dangerous. Why it is dangerous?
>Well, there always exists something called "reaction time"
>(I define it as a necessary time for a dviver to notice the break
>lights of the car in the front of him), so for the safety and
>INDEPENDENTLY OF MODELS, the safe distance between cars always
>must be larger than :
>       (Reation Time) * (Your Actual Velocity).
>It means that the safe distance must increase quickerly (or equally)
>than linearly to the velocity.  So for a flow of limit velocity
>moving cars (typically: 65 mph in USA, 130 kmph in Europe) the
>public safety requires that the car's density must be very small
>(it's true, you can drive very quickely & safely when you do not
>see any car in the front of you) and therefore, the road's
>passibility does not increase when (almost) each driver on the road
>increases his/her car's velocity, as at the first sight.
>   The main idea in the second AV's model is based on the simple
>obsevation that car's flow could be regarded as ... laminar
>car-liquid flow.   Obviously there are also few natural
>requirements on this car-liquid :
>
>  1) Conservative law: The number of cars is conserved.
>  2) No car-car collision: There exists a characteristic safe
>     distance between cars.
>
>Reading 1) people with good back ground in Physics & Engineering
>must remind themself about famous continuity equation and here
>in the simple day-life's problem, they could learn how to apply
>effectively it into the life.  Life is too boring if there are
>only some poor applications in the Univ. Text-Books !! :-)
>
>However AV's model is unrealistic, because he did know how to
>implement 2) properly.  Anyway he could implement 2) a bit better,
>make his model becoming more realistic and helpfull, if he knows
>at least which parameters are important (consider time reaction,
>car's technical data: like car's acceleration, etc.) and ready to
>pay a little more time "playing" on it.  Hope that some of you can
>improve the model or develope completely new one.  Use a chance
>to learn (freely) sth news from others.  It's boring game that
>I post a simple problems first and later Mrs Iga post a simplest
>solutions :-)
>
>Cheers,
>SN
>------------------------------------------------------------------
>On Tue, 26 Oct 1999, Aiviet Nguyen wrote:
>
> > Tu+` model 2 tro+? ddi ba`i toa'n thu+.c cha^'t la`
> > set speed limit cho DMV.
> >
> > Model 1 (For VHL) Speed limit la` 55 mile/h.
> >    Solution: cha.y vo+'i va^.n to^'c 55miles/h. Lo+`i
> > gia?i kho^ng phu. thuo^.c va`o model va` ra^'t
> > realistic.
> >
> > Model 2 ( Elementary problem for 8th grade)
> >      Model high way gio^'ng nhu+ mo^.t ca'i o^'ng
> > mo^.t dda^`u va`o va` mo^.t dda^`u ra. Ca^u ho?i ta
> > co' the^? cho dda^`u va`o vo+'i rate nhu+ the^' na`o
> > dde^? so^' lu+o+.ng dda^`u ra tre^n ddo+n vi. tho+`i
> > gian la` max.
> > Simplification: kho^ng co`n  mo^.t dda^`u na`o kha'c
> > tre^n o^'ng. Gia? thie^'t kho^ng co' hie^.u u+'ng skin
> > (va^.n to^'c o+? ca'c la`n kha'c nhau la` nhu+ nhau
> > va` kho^ng co' ddo^?i lane...stb....). Ca'c
> > simplication kha'c thi` student co' the^? gia? ddi.nh
> > the^m mie^~n la` gia?i ddu+o+.c
> >
> >    Solution:
> >             Lu+u lu+o+.ng  va`o  \rho v  ( v la` va^.n
> > to^'c  cu?a  ca'c xe , \rho la` ma^.t ddo^. xe trong
> > o^'ng =N/l ). Lu+u lu+o+ng ra to^'i dda ba(`ng lu+u
> > lu+o+ng va`o va` ta chi? ca^`n ddo`i ho?i kho^ng co'
> > collision. Quy ta('c  na`y co' the^? la^'y tu+` thumb
> > rules: dde^? an toa`n ca^`n khoa?ng ca'ch mo^.t tha^n
> > xe cho va^.n to^'c 10 miles/h.  Tu+'c la` cha.y vo+'i
> > va^.n to^'c v ta ca^`n (v/10 +1) X h cho mo^~i xe ( h
> > la` chie^`u da`i cu?a xe). Ma^.t ddo^.  la` nghi.ch
> > dda?o cu?a dda.i lu+o+.ng na`y
> >          Va^.y lu+u lu+o+.ng va`o dde^? kho^ng co'
> > collision ( = LLl ra) la`
> > v/ h(v/10+1). Lu+o+.ng na`y dda.t to^'i dda thi` pha/i
> > ho?i ho.c sinh lo+'p 10 :-))
> >
> > Model 3: Should be more difficult with a lot of exit
> > and entrance. It should be model as nested queues.....
> > (need further realistic formulation)
>
>

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