Subject: Re: hvac for small house
From: mrcoolu@xanadu2.net
Date: Wed, 11 Dec 1996 13:41:12 -0600
In article <32a8aae0.869765913@newshost.ccsi.com>,
larry@ccsi.com (Larry Marshall) wrote:
>
> I am building a small one bedroom house (640 sq ft) in central TX.
> Central A/C & Heat seems like overkill. Am considering a wood stove
> for heating but would like recomendations for A/C
A 640 square foot house should take a 1.5 ton unit. However,
of the house has little insulation or several large windows
then you may want to go with a 2.0 ton. If you are in doubt
about the size of unit you can call your local electric
company and have them run a load on their computer. In south
Texas they do not charge for this service. They probably
won't charge in your area but be sure to ask them first.
For the best buy on air conditioning units be sure to see our
website at http://mrcoolu.com
Ginther Sales Inc.
1301 E. Oklahoma
Harlingen, Tx 78550
1-800-mrcoolu
(210)428-9380
fax (210)428-9390
mrcoolu@xanadu2.net
http://mrcoolu.com
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Subject: Re: Good Technical Books?
From: billmcc
Date: Wed, 11 Dec 1996 12:42:57 -0800
Christian Campbell wrote:
>
> I am a buyer of technical books at Brown University. So, I thought I'd go
> to the people who read these books to find out which books are "must
> have's!" If you have any suggestions, please e-mail me. I am
> particularly interested in recent non-computer titles, but I also stock a
> number of technical classics.
>
> Thank you,
I collect what I call bibles fromt the various areas I have worked in,
it is not a big list:
Handbook of steel construction
Fluid Dynamic Drag (and Lift) by Hoerner
Analysis and Design of Flight Vehicle Strauctures, by Bruhn
Marks' Standard Handbook for Mechanical Engineers
Formulas for Stess and Strain, Roarke & Young
Precision Machine design by Slocum
Low Speed Aerodynamics, Plotkin and Katz
The Finite Element Method by Zienkiewicz & Taylor
Machine Design by Schigley (Rothbart is pretty good as well)
Bill McEachern
Subject: Re: waterjet cutting
From: abudaka@planet.edu (Dr. M. Abudaka)
Date: 11 Dec 1996 20:53:40 GMT
In article <584307$f6l@news00.btx.dtag.de>, Martin.Tanja.Schmidt@t-online.de (Martin Rudolf Schmidt) writes:
> Hello!
> Does anybody have some experiance in cutting wood with a waterjet? The
> wood is up to 50 mm thick. It is rubber-tree-wood, not a laminate.
> Some engineers of the waterjet cut industry say it works with
> problems, some say, it doesn´t work.
>
> Thanks in advance, Martin
>
> Dipl.-Ing Martin Rudolf Schmidt
> Germany
> 0235121842-2@t-online.de
>
If you require a clean cut, then it is not suitable, but it will cut it if the jet contains abrasive material
Subject: Re: FEA theory needed for FEA software?
From: rizzo@hogpb.ho.att.com (-A.RIZZO)
Date: 10 Dec 1996 16:33:10 GMT
In article <58jmds$19t@usenet.rpi.edu>,
Mark Beall wrote:
>In article <58ddve$5k7@newsb.netnews.att.com>,
>-A.RIZZO wrote:
>>
>>If we accept (100), and if (110) exists, then we must conclude
>>that no software can deliberately solve an engineering problem.
>>
>>So why do we keep chasing this golden fleece?
>>
>>Tony Rizzo
>>
>I'm not sure that your argument matters. My calculator doesn't "understand"
>mathematics, however I find it a useful tool when solving many problems.
>
>Why does my finite element software have to "understand" anything to be
>a useful tool? At some point in the solution of this engineering
>problem (you really need to define what you mean by this), if I'm
>planning on using FEA then I will have idealized the problem I'm
>solving in terms of some mathematical description (e.g. linear elasticity)
>and I use FEA to solve that. The connection between my idealized
>mathematical description and the original problem is something
>that I have to know.
>
>Mark Beall (mbeall@scorec.rpi.edu)
The situation where FEA is a tool in the hands of a knowledgeable
engineer, such as you describe, is precisely the kind of situation
that makes good sense. The original posting discussed software that
could, by itself, solve engineering problems. My proof addresses
this non sensical application of FEA.
Tony Rizzo
Subject: Re: active vibration control
From: Greg Reich
Date: Wed, 11 Dec 1996 15:19:31 -0700
Diane
I would suggest searching the library and/or internet with the words
(active) vibration control, or active isolation, or smart structures, or
vibration isolation. The Journal of Sound and Vibration sometimes has
articles on structural vibration control.
Good luck!
Greg
--
Gregory W. Reich University of Colorado
Aerospace Engineering Sciences (303)-492-0517
Diane Carlson wrote:
>
> Hi. I'm a sophomore at the University of Illinois Urbana-Champaign. I
> currently belong to the Society of Women Engineers and I am part of Team
> Tech. In Team Tech, the group is given an interdisciplinary problem by
> industry to solve. We solve the problem, write a paper, and present it
> at Engineering Open House here at school and then again at SWE
> nationals. This years project is to develop an active vibration control
> system for industry standard PC 3.5" disk drives. I was wondering if
> anyone knew of good papers, journals, or home pages with info on AVC or
> if anyone could send me more info on this topic. Any help you could give
> me would be much appreciated. Thanks.
>
> Diane Carlson
> dmcarlso@students.uiuc.edu
>
>
Subject: Re: What's in a Job Title ?
From: moorehed@interlog.com (Chris Moorehead)
Date: Wed, 11 Dec 1996 22:52:52 GMT
"G. Shane J. Lafreniere" wrote:
>Well, good thing you not in Ontario, Canada, or any other province for
>that matter.
>
>Within Canada, it is a provincial and federal offence to use the term
>'engineer' in your job title unless you are a licenced practioner.
I only wish this was true! Actually, it's only an offence to use the
term "professional engineer" or the abbreviation "P. Eng." unless you
are a licensed professional engineer. However, many organizations,
such as Ontario Hydro and the Government of Ontario, limit the use of
"engineer" in job titles to licensed professional engineers.
>Canada passed the Professional Engineers Act in 1990, and along with the
>Ritual Calling of an Engineer, (if you notice a Canadian engineer with a
>battered Iron ring on their working hand...) the job title, whether
>working for a company, or on your own private business card will not
>allow you or your company to use those terms.
The Iron Ring is only given to those who graduate from a Canadian
engineering school. Having an iron ring only means that one has a
Canadian engineering degree, not that they are a licensed professional
engineer. It is possible to obtain a professional engineering licence
without having a Canadian (or any) engineering degree; however, it
requires many years of engineering experience as well as writing a
series of exams so onerous that it would in fact be easier to get an
engineering degree instead.
>As well, being a self-governing, self regulated (within provincial
>boundaries), there are also different levels of 'Service' or licences
>that can be obtained. These range from a Temp Licence, to a "Consulting
>Engineer" title.
The hierarchy is as follows (from lowest to highest):
Engineering Graduate
Engineer-in -Training
Professional Engineer
Professional Engineer providing services to the public
Consulting Engineer
The temporary or limited licence is usually issued to persons who have
acquired enough engineering expertise to practice in an extremely
narrow field, or to licensed professional engineers (or US P.E.'s)
from other jurisdictions who require a licence for a specific period
of time (ie - a project).
A professional engineer responsible for providing services to the
public (ie - a principal in an engineering firm) is required to hold a
Certificate of Authorization from the association, as well as
Professional Liability (Errors & Omissions) Insurance & engineering
experience above & beyond what is required for licensure.
The Consulting Engineer designation is a non-legal designation that
the holder of a Certificate of Authorization can acquire after
offering services to the public for several years. It has no legal
meaning (the Certificate itself is the legal authorization), and the
only additional benefit over & above a Certificate holder is the right
to put "Consulting Engineer(s)" on the name of one's firm. Plans are
in the works to abolish this particular designation, since it doesn't
actually mean much.
>There is a rather lengthy, formal process to be followed to obtain a
>licence (which I'm currently doing) and be able to practice within
>Canada as a Professional Engineer.
> With this extra work, comes extra responsibility. All practicing
>Engineers have special Certificates and Liability insurance either at
>the personal level, or at the employer-company level.
The Certificate of Authorization & liability insurance is only
required for those responsible for offering professional engineering
services to the public. As I have only recently acquired a
Certificate of Authorization, I have just gone through the red tape
involved - not fun!
Alas, with extra work comes extra responsibility, but very rarely
extra compensation...
>Hence, not only can a skilled person who may do a similiar job in
>Canada NOT use an Engineering title, but those who do need special
>Licences to practice.
Unfortunately, we don't enforce our legal right to this title nearly
as well as doctors & lawyers do. Perhaps if we did, our incomes would
be as high as theirs.
good luck,
chris
--
CHRISTOPHER J. MOOREHEAD, P. Eng.
Environmental & Manufacturing Consultant
Toronto, Ontario
Subject: Re: FEM / FEA for Composites?
From: chrisw@skypoint.com (Christopher Wright)
Date: Wed, 11 Dec 1996 18:14:02 -0600
In article <32AEDDD0.33ED@compuserve.com>, 100015.132@compuserve.com wrote:
>We are looking for finite element modeling (FEM) and finite element
>analysis software systems which can handle or are specialized for fiber
>reinforced plastics / composites. What is the most used system? What
>runs on PCs, what on Apple Macintosh? What other platforms are there?
COSMOS/M has this capability and runs on Windoze and the Mac. The Mac
installation is good for a vertical market program--a little quirky for us
die-hard Mac bigots, but 100% better that ANSYS on WinNT, which I've also
used. The COSMOS modeller is better than ANSYS, but the post processing
not as good. You might also want to check out LapFEA which is the old
MSC/pal.
Christopher Wright P.E. |"They couldn't hit an elephant from
chrisw@skypoint.com | this distance" (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/subscribers/chrisw
Subject: Re: FEA theory needed for FEA software?
From: rizzo@hogpb.ho.att.com (-A.RIZZO)
Date: 11 Dec 1996 03:08:15 GMT
In article <01bbe702$785c8220$06eabbc0@leehpc2>,
Lee Harding wrote:
> ... snip ...
>To address Mr. Rizzo's posting: We continue to chase that proverbial fleece
>because we are engineers. As such, we are not in the habit of concluding
>that a problem can't be solved simply because it hasn't been solved.
> ... snip ...
>Lee Harding
>Autodesk, Inc.
>MCAD
During the 1980s, most of the engineers who wanted to solve
a problem even slightly more complicated than a plate with
a centrally located hole had to spend a good deal of their
time defining the geometry of their problems. Then, the FEA
suppliers incorporated a number of useful features that made
the definition of the geometries of problems much easier. By
so doing, the FEA suppliers overcame what at that time was
the "bottleneck" in the process by which design information
was produced.
Now, the process by which the geometries of most problems are
defined is no longer _the_ bottleneck in the greater process
by which design information is produced. The new bottleneck
is the ability of design engineers to answer the few difficult
questions about the workings of their designs. This new
bottleneck is not overcome by further advances in the speed
and ease with which one defines the geometry of an
engineering problem. Any such further advances provide
continued improvements to those parts of the information
production process that are non bottlenecks.
To overcome this new bottlneck, engineers need tools that
let them explore multi-dimensional design spaces efficiently.
They also need tools that let them solve non linear problems
reliably, because the bottleneck problems are nearly all
highly non linear and very multi-dimensional. In addition to
these tools, design engineers need to fully understand
the PHYSICS of the problems that they need to solve.
If you create and market tools that address the current
bottleneck in the information production process, then
your company is destined for success. These are the tools
that bring the greatest value to your customer organizations,
because with them the engineers of your customer organizations
can bring their employers' products to market sooner and
with higher quality. If you don't create and market such
tools, then your company is exposed to the violence of
the marketplace.
But this is only my opinion, of course.
Tony Rizzo
Subject: Re: Bearing Design References?
From: bsw@cris.com (bsw)
Date: Thu, 12 Dec 1996 06:57:44 GMT
"Paul D. Altpeter" wrote:
>Can anyone suggest a good reference for the design of sleeve bearings? In
>particular I am trying to understand the relative merits of different
>materials for main and crankpin bearings as well as crosshead bushings in
>large (>2000HP) reciprocating compressors. US compressor suppliers use
>bronze, aluminum, steel-thick babbitt and tri-metal (all apparently with
>good success). I'm not very familiar with what European or Asian
>compressor manufacturers use. Net references are preferred but paper
>references would be welcome as well.
>Thanks,
>Paul D. Altpeter
>Principal Machinery Engineer
>Air Products and Chemicals, Inc.
Try Garlock bearings/bushings, made of steel housing, pwdermetal
bronze carrier filled with a PTFE solid lubricant.
Subject: Re: FEA theory needed for FEA software?
From: Tapio Leino
Date: Thu, 12 Dec 1996 12:48:51 -0800
Steven D. Wix wrote:
> ... Also, with
> all of the packages, the user needs to apply boundary conditions, and
> without some experience and knowledge in the analysis area, the
> boundary conditions can be applied incorrectly.
I think the whole subject of this discussion sucks!
It is quite clear that nobody can use commercial FEM programs
without the basic knowledge of the FEM theory. Any such person
using a program would end up having a singularity of some sort
at the first time.
Well, while studying the manuals finding the reason for the
singularity he/she'll finally get to know the basics of FEM!
But having ACCURATE results is another story!
Tapio Leino
VTT Building technology
Subject: Re: FEA theory needed for FEA software?
From: beallm@rcs-1.scorec.rpi.edu (Mark Beall)
Date: 12 Dec 1996 13:11:30 GMT
In article <32ADB248.70C1@mail.utexas.edu>,
Erik Loehr wrote:
>
>Very true! But what you have described, the idealization of a problem into a mathematical
>description, is what I would refer to as "engineering". This is the part of the problem that most
>engineers (if acting judiciously) should have a handle on whether or not the problem is being
>analyzed with the finite element method.
>
I certainly agree with you here.
>An equally important point in the current context is that the finite element method is an
>APPROXIMATE method for solving the idealized mathematical description. Just as an engineer must
>have a background in the theory of the "mathematical idealization", an engineer employing the
>finite element method must have a background in the theory of finite elements so that the method
>can be properly applied and the consequences of the approximation understood.
>
>-Erik Loehr
Using today's commercially available software, I agree. However, given
the idealized mathematical description (not a finite element model)
it is quite possible to write software to automatically solve that
description to an accuracy dictated by the engineer. With such software
there would be no need for the engineer to understand what technique
is used (I believe that this is the "golden fleece" that Tony Rizzo
referred to). It would still be the engineers responsiblity to
make sure that he modeled the correct problem, he still would have
to do the engineering.
Mark Beall
Subject: Re: FEA theory needed for FEA software?
From: beallm@rcs-1.scorec.rpi.edu (Mark Beall)
Date: 12 Dec 1996 13:13:46 GMT
In article <58k3c6$2lv@newsa.netnews.att.com>,
-A.RIZZO wrote:
>
>The situation where FEA is a tool in the hands of a knowledgeable
>engineer, such as you describe, is precisely the kind of situation
>that makes good sense. The original posting discussed software that
>could, by itself, solve engineering problems. My proof addresses
>this non sensical application of FEA.
>
>Tony Rizzo
>
I think we're agreeing about two different things, see my other post
in response to Erik Loehr.
Mark Beall
