Subject: Re: Your Most Often Used References
From: Mark Thornton
Date: Mon, 30 Sep 1996 10:02:47 +0100
I am surprised that, so far, no-one has mentioned:
"The Metals Black Book (Ferrous Metals)", ed. Bringas, pub. CASTI
publishing, Canada
Mark
--
Mark Thornton Tel: +44 1223 332760
Cambridge University Eng. Dept. Fax: +44 1223 332662
Trumpington Street E-mail: mht11@eng.cam.ac.uk
CAMBRIDGE CB2 1PZ, UK
http://www2.eng.cam.ac.uk/~mht11/
Subject: Re: Combustion efficiency based on ambient temperatures?
From: kirchweg@sztms.tu-graz.ac.at (Gerhild Kirchweger)
Date: 30 Sep 1996 12:04:16 GMT
Victor Smith (vicsmith@ripco.com) wrote:
:
: Whoa, stop right there. Will Stewart wrote no such thing.
: That was somebody else. Who's on first?
Yes there was a quote between, I've probably deleted the wrong line. Sorry.
: Ok, so you won't answer the question. I'll try, though I am not an
: engineer. But I was a boilerman. And I have a few questions.
:
: 1. Every car I've had uses more gas in the winter. (weak, but hey)
Yes, that's easy (gasoline I presume): There's the feature, that the fuel
has has to be suspended (or whatever it's called) in the air to be able to
be burnt (liquid gasoline doesn't burn, it's the gases that do). When the
engine is cold, quite a lot of the gasoline decides to stay at whatever wall
is just nearby (just like the water in your bathroom, when you just finished
your shower and want to look at your shining face in the mirror, and the
mirror just shows you a blurr). In order to keep your engine going (or
to make it start in the first place) more fuel is added, that some time,
when the engine is warmer, somehow gets into the cylinder and burns
uncontrollable (you can't gain it anymore).
: 2. A car engine wants to operate at @195F degrees, if only for purposes
: of lubrication. The thermostat will make this wish come true.
: 3. At low temps heat flows from the engine more rapidly than at high temps,
: requiring more BTU's (substitute your favorite unit of heat) to
: maintain those 195F degrees.
that's why the heating from your engines works worse when you need it most:
first the engine has to be warmed, then the passengers.
: 4. Where does this heat come from? Yep. Right through the cylinder walls.
: 5. I believe that a heat-insulated engine would be more efficient than
: those currently in use, but is impractical.
Then you's need a bigger heat excchanger. No, the problem is materials.
: 6. Since ICE's are burning their fuel so cleanly of late, isn't the last
: major improvement remaining one of heat conservation? Does anyone
: know what percentage of ICE fuel energy is lost to waste heat?
Roughly 2/3. 1/3 power output (your 1hundredsomething horsepower), 1/3
exhaust, 1/3 cooling (heat exchanger + engine walls).
: 7. How can we capture that waste heat and make it work for us?
That's the interesting part: You'd want that heat from one driving to the
next, for warming up the cooling water and the catalyst. This would require
a long-time heat storage, whcih, unfortunately aren't satisfying.
: 8. The newer home heating units burning NG shed so little waste heat
: that ceramic or firebrick lined chimneys are replaced by PVC pipe.
:
: 9. I can still roast chickens all day on my exhaust manifold.
: 9. ( 10. would mess up the indentation). What am I missing here? Why are
: we still saddled with these heat wasting contraptions?
1. (I hope I'll stay well under 10., so I can leave the indentation) Home
heating units are steady-state, that makes things a lot easier
2. They never have to accelerate, so the can be as heavy as they want.
3. They heat up to about 100 deg. Celsius, that's way lower than any
gasoline engine.
4. And that's the crucial part: They are not reciprocating engines expected
to have some power output. A 2-or 4-stroke engine is expected to get all the
cyliner empty and clean, before the next fresh air comes in, so all the
available space can be used for a new cycle. As the engine rotates rather
fast, there isn't much time for that task, so the exhaust gas has to rush
out in a hurry. It does that only if it's eager to expand (i.e. hot and
under high pressure).
: BTW, I recall reading about the attempted development of ceramic engines,
: which would be super-efficient. Anyone know of progress on that front?
Didn't hear much lately, it's not likely to be used in next years
models.
--
oo_oo_oo_oo_oo_oo_oo_oo_oo Gerhild Kirchweger oo_oo_oo_oo_oo_oo_oo_oo_oo
|____ Department of Internal Combustion Engines and Thermodynamics ____|
|__ Graz University of Technology/ Austria ___Tel. ++43 316 873 7212___|
oo_oo_oo_o http://fvkma.tu-graz.ac.at/~gerhild/gerhild.html _oo_oo_oo_oo
Subject: Re: Combustion efficiency based on ambient temperatures?
From: kirchweg@sztms.tu-graz.ac.at (Gerhild Kirchweger)
Date: 30 Sep 1996 12:18:58 GMT
Robin van Spaandonk (rvanspaa@netspace.net.au) wrote:
: Sorry for jumping in in the middle of this thread, but this is
: actually a very significant point.
: If fuel is still being burned when the exhaust port opens (and the
: presence of unburned hydrocarbons in the exhaust is an indicator that
: that is usually the case), then the temperature will still be quite
Output of CO2 is roughly 1000 times that of unburnt Hydrocarbons. Even if
you consider, that CO2 is heavier (then though you also have to take into
account, the H2O that comes from the combustion of Hydrocarbons), only
rougly 0.1percent of the fuel does not get burnt. And that's usually not an
indicator that the fuel wanted to burn but couldn't because the valve
opened, but that there was generally or locally not enough O2 available for
combustion.
: high. Much higher in fact than if all the fuel had been burnt at the
: beginning of the power stroke, and the gasses had cooled due to
: expansion. Consequently the efficiency of the engine will vary hugely,
: depending on exactly at what stage in the power stroke the fuel is
: burnt.
: Thus high efficiency is attained when all fuel is burnt early on in
: the power stroke. This is most easily achieved by burning a fuel that
: oxidises rapidly. Wouldn't this generally be a "small molecule" fuel?
Yes, but these fuels tend to explode before they should (I guess it's called
"knocking" in English).
Diesels work that way, although they don't use small-molecule-fuels but
higher pressure/temperature.
--
oo_oo_oo_oo_oo_oo_oo_oo_oo Gerhild Kirchweger oo_oo_oo_oo_oo_oo_oo_oo_oo
|____ Department of Internal Combustion Engines and Thermodynamics ____|
|__ Graz University of Technology/ Austria ___Tel. ++43 316 873 7212___|
oo_oo_oo_o http://fvkma.tu-graz.ac.at/~gerhild/gerhild.html _oo_oo_oo_oo
Subject: Not a CADL but *.CDL file ! Maybe a CNC program. Can you help please ? >:(
From: istvan@acay.com.au (Istvan Toth)
Date: 30 Sep 1996 12:40:37 GMT
The following text is stored in a * .CDL format file !
At the first look I think it isn't a so called CADKEY's format CADL, but more like a CNC program for
sheetmetal punch !
Would anybody recognise and/or help us convert these files to a common DXF format. ?
Please contact us on the above E-mail address ASAP !
Regards
Istvan Toth
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
MM/MM
GSIZE/X0/Y0/NX1/NY1
P1/X0/Y0
P2/X1435/Y162,P1
P3,P1,P2
P4,P2,P1
P5/X15,P1
P6/X1405/Y40,P5
P7/I-125.6,P6/I0,P5/S10
P8/X7.2/Y10,P7
P9/X7.2/Y10,P8
P11/X1/Y40,P5
P12/I-54.4,P11/I0,P5/S10
P13/X-7.2/Y10,P12
P14/X-7.2/Y10,P13
P16/Y38,P5
P17/Y168,P5
P18/X1406/Y38,P5
P19,P18,P17
P20/X95/Y52.5,P5
P21/X-98,P22/Y0,P20
P22/X703/Y-10,P5
P23/X98,P22/Y0,P24
P24/X-95/Y52.5,P27
P10/I-54.4,P11/I0,P5
P15/X-12,P26/Y0,P25
P25/X-19,P19/Y116,P5
P26/Y182,P22
P27,P18,P4
TOOL/4
LOAD/X1524/Y350
PUN/20,21,23,24/
TOOL/12
INDEX/P6/P7/L
TOOL/13
INDEX/P12/P11/L
TOOL/27
LH/R12/I180,P25/57
LH/R12/I180,P15/57
TOOL/1
PUN/LD/12,13,14,11/
TRIM/P16/P17/L
PUN/RD/7,8,9,6/
TRIM/P18/P19/R
TOOL/11
TRIM/P22/P26
Subject: 7th Int. Conf. on Rapid Prototyping
From: Mukesh Agarwala
Date: Mon, 30 Sep 1996 10:18:10 -0400
Conference Announcement and Call for Abstracts
The Seventh International Conference on Rapid Prototyping
March 31 - April 3, 1997.
Hyatt Regency, San Francisco Airport
California, U.S.A.
Co-sponsored by University of Dayton and Stanford University
After enthusiastic response and success in its first six years
(1990-1995), the ICRP is back for 1997. The ICRP is jointly organized
and sponsored by University of Dayton and Stanford University, both
leaders in the Rapid Prototyping Research and Technology. The Seventh
ICRP will be held in the San Francisco Bay area, first major RP
conference of its kind on the west coast. The ICRP will continue its
successful tradition of providing a forum for everyone interested in the
exciting field of RP and offer a rare opportunity to learn and exchange
NEW information on all aspects of the field and interact with
participants from all over the world. The Conference features:
· Technical Sessions on Research & Development and Applications
· Special Topic Workshops and Tutorials
· A Trade Show Exhibition
· Management Issues and Case Study Presentations
The focus of the technical sessions will include, but not limited to,
the following topics:
· Rapid Prototyping Processes state-of-the art
· Novel RP processes; new developments in existing RP processes
· Precision and resolution in RP
· Advanced process control
· Rapid Tooling & direct tooling fabrication
· 3D CAD Modeling
· Alternatives to CAD for process/design inputs
· Advances in computer interfaces for RP
· Applications of RP
· Case studies & management issues in RP
· Use of RP in engineering and business strategies
· Materials development for RP
· RP process modeling
· Functional prototyping and manufacturing
· Medical modeling and applications
· Other novel applications and experiences with RP technologies
Abstracts are invited for technical sessions in any of the above topics
or any other RP related topic. The abstracts should be limited to 250
words. Include title, authors, and their complete affiliations, and
submit by mail, FAX or e-mail before October 17, 1996 to:
The International Conference on Rapid Prototyping
Conference Coordinator
The University of Dayton
300 College Park, Dayton, OH 45469-0150, U.S.A.
FAX: (513) 229-3433
e-mail: ICRP@udri.udayton.edu
Keeping in tradition with the past ICRP, conference proceedings will be
made available to conference participants at the Conference on March 31,
1997. To allow time for the review process, complete manuscripts of the
abstracts accepted for technical sessions will be due no later than
Jan.10, 1997.
Conference registration forms and further information will be available
shortly. A limted block of rooms have been reserved for the Conference
at the Hyatt Regency San Francisco Airport, the Conference headquarters,
at low conference rates. Hotel reservation forms and other materials on
travel will also be available soon. For further information on the
Conference, trade show exposition, and hotel reservations, please refer
to web site http://www.udri.udayton.edu/conf/rapidpro/ or send e-mail to
ICRP@udri.udayton.edu
Subject: Re: Is Mechanics of Materials misleading ?
From: thiel@euclid.endicott.ibm.com (George H. Thiel)
Date: 30 Sep 1996 14:50:46 GMT
In article <01bbad19$a48b4980$279615a5@Singnet.singnet.com.sg>, "DR. JOHN CHEUNG" writes:
|> I am having heated debate with a colleague in my university's mechanical
|> engineering department. In planning a new Elective subject relating to
|> advanced aspects of buckling, plastic collapse, as well as plates, shells,
|> etc. I give the subject the established name of Advanced Mechanics of
|> Materials.
|> He strongly object to this title. It should be called something like
|> mechanics of structures, or structural mechanics. Struts, beams, plates,
|> shells are structures, he said. Mechanics of materials is to do with
|> elasticity, plasticity, fracture, creep, etc. They concern study of the
|> mechanics of solid materials.
|> No, struts and beams are load bearing component, I said. They may be
|> structural components, but may also be machine components subjected to
|> loads. And structural elements are components of structures and are not
|> structures, like gears and bearings are components of machinery and are not
|> machinery. The name mechanics of materials may be misleading in terms of
|> language use, but it is the acceptable term for such study of beams and
|> struts in the English speaking mechanical engineering community.
|> The arguement is still going on, as my colleague does not give up easily.
|> And I am exasperated.
|>
Why not call the course "Advanced Mechanics of Materials and Structures" ? You will probably
include elements from both "subjects"
Finally a qusetion on this forum I could answer :)
George
(thiel@vnet.ibm.com)
Subject: BASstar and PDAS Web Site Announcement
From: gorrino@mecsvi.trn.dec.com (mauro)
Date: 30 Sep 1996 16:32:15 GMT
Digital Equipment Corporation is pleased to announce a new web page for the
BASEstar and PDAS, Digital's manufacturing integration software products.
The URL is: http://www.digital/com/info/manufacturing.
BASEstar software facilitates the integration of manufacturing applications
and plant equipment, and through its architecture, encourages consistency of
application development. BASEstar is a realtime, distributed platform
capable of providing these facilities on a plantwide manufacturing network.
PDAS is Digital's plant floor integration software that links realtime
process control systems and laboratory systems with the SAP R/3 PP-PI
module. Based on the ISA SP88 Standard, PDAS seamlessly integrates
even-based and transaction-based applications and devices, creating a
totally integrated process planning and execution environment across the
corporation.
BASEstar is currently available on following platforms:
- Microsoft WNT (Intel & Alpha)
_ Digital Unix
- OpenVMS (VAX & Alpha)
- HP-UX
- Windows 3.11 and Windows 95 (Client part only)
PDAS is currently available and SAP certified on following platforms:
- Microsoft WNT (Intel & Alpha)
_ Digital Unix
- HP-UX
- Windows 3.11 and Windows 95 (Client part only)
For more information on BASEstar or PDAS, consult the web page or send
e-mail to manufacturing@digital.com.
Subject: Straightening of Hot-Rolled Beams
From: Steven Hughes
Date: Mon, 30 Sep 1996 11:51:00 -0500
Hello,
My name is Steven Hughes and I am a mechanical engineer for Chaparral
Steel located just south of Dallas, TX.
I am currently working on a project that centers around the
straightener. The straightener that I am referring to is used to
straighten bars as they are coming off the cooling bed. We are rolling
light structural shapes from 3" channel up to 14" beams.
What I ultimately want to accomplish is establishing an electronic
feedback loop from a system that measures sweep, camber, and squareness
to a system that controls the straightener/cooling bed. In the process,
I want to develop a system that can take multiple variables surrounding
the straightener (such as bar temp, pressures of the strnr. rolls,
location of the strnr. rolls, ambient temp, bar grade, shape being
rolled, etc.) and develop a system that can correlate the impact of the
variables on the resulting straightness of the bar.
The major problem is finding a standard way of measuring camber, sweep,
and sqareness of the bar w/o interfering with production.
If there is anyone out there that is interested in discussing such a
topic or if there is someone out there trying to develop/use such a
system, I would greatly appreciate all comments. You can email me
directly, post a reply, or call me.
Sincerely, Steven Hughes
email--------- hughes@iamerica.net
phone-------- (972) 775-8241 ext 4080 7am-3pm (Central Time Zone)
Subject: CAN-Tor MECHANICAL DESIGN ENGINEER
From: Pro Tec Technical Services
Date: Mon, 30 Sep 1996 14:49:27 -0700
Pro Tec Technical Services wrote:
>
___________________________________________________________________________________
PRO TEC TECHNICAL SERVICES
____________________________________________________________________________________
A Global Engineering and Technical Employment Service, headquartered in Toronto, Ontario, Canada
MECHANICAL DESIGN ENGINEER
The ideal candidate will be a graduate Mechanical Engineer with course
work in machine design and stress analysis, with 3-5 years experience in
manufacturing practices and processes used in the production of large
rotating equipment. The candidate must have working knowledge in the use
of computer based analytical tools including electromagnetic Finite
Element Analysis as well as strong interpersonal skills and ability to
work effectively in a team environment . The candidate must be proficient
in the use of PC based computer software.The position is permanent. The
location is East Toronto. Salary will be very competitive.
Please reply in Confidence to Mike Slimkowich, Pro Tec Technical
Services, 2255 Sheppard Avenue E., Suite
W-414, Willowdale, Ontario, CAN, M2J 4Y1.
E-mail: protec@dis.on.ca Fax: (416) 496-8729
Web: http://www.dis.on.ca/ProTec Telephone: (416)
496-8595
Subject: Re: Is Mechanics of Materials misleading ?
From: jmsche01@starbase.spd.louisville.edu (James M. Scherer)
Date: 30 Sep 1996 17:40:07 GMT
DR. JOHN CHEUNG (stcheung@singnet.com.sg) wrote:
: I am having heated debate with a colleague in my university's mechanical
: engineering department. In planning a new Elective subject relating to
: advanced aspects of buckling, plastic collapse, as well as plates, shells,
: etc. I give the subject the established name of Advanced Mechanics of
: Materials.
: He strongly object to this title. It should be called something like
: mechanics of structures, or structural mechanics. Struts, beams, plates,
: shells are structures, he said. Mechanics of materials is to do with
: elasticity, plasticity, fracture, creep, etc. They concern study of the
: mechanics of solid materials.
Whip out your text and show your colleague all the variables in those equations
that stand for material properties such as elastic modulus. Mechanics of
Materials involves deformation which is dependent on material properties.
Mitch
Subject: Air Compressors
From: Mike Clapperton
Date: Mon, 30 Sep 96 21:38:35 PDT
I am currently looking into replacing the two compressors houses at my company
with one central site, complete with a new reticulation ring main distributing
to the three separate factory areas. As a requirement for the majority of the
processes is dry, oil free-air, I have considered centrifugal compressors.
However they do not handle load fluctuations very well, being more suited to
continuous flow operation. I am therefore considering (as one of my options)
centrifugals to handle the base load, and screws to handle any increases in
flow above this base load, due to their better unloading characteristics.
If anyone has any experience in this type of arrangement, or has any other
suggestions, your comments would be greatly appreciated.
Regards
Mike Clapperton
Subject: Re: Hydraulic cylinder
From: wmartin@sdd.hp.com (William Martin (Temp))
Date: 30 Sep 1996 19:33:08 GMT
In article <324D452A.5C2C@clearlight.com>, Allen Redmond writes:
|> Is anyone familiar with a composite tube that will work in a Hydrdraulic
|> tube application as a cylinder.
|> --
Yes, I have some literature at home from a company that filament-winds
pressure vessels and composite pressure tubing. the tubing id finish is
something like 15 micro-inch, as I recall. They are located in Wisconsin,
I think...don't recall the name just now, but if you want to contact them,
e-mail me and I'll dig out the literature/address.
Bill
|> ======================================================
|> "Do not follow where the path may lead...
|> Go instead where there is no path and leave a trail"
|> Author Unknown
|> Al Redmond allen@starnetinc.com
|> ======================================================
|> http://WWW.clearlight.com/midwestcomposites
|> ======================================================
Subject: Re: Which FEA Package?
From: luho@luho.ac.eunet.de (Luis Hoeks)
Date: Mon, 30 Sep 1996 20:56:21 GMT
Grant Moyer wrote:
>Our company (mostly my boss and I) has been struggling on which FEA
>package, if any, to purchase. I will be the one to use the package and
>my, like many people I imagine, primary job function IS NOT to use FEA.
> But there are many instances where it would be very useful and at this
>moment we just don't have the time to wait for the prototypes to be
>made, break them, re-design, wait, etc. I would be nice to only have to
>make, say, 3 prototype iterations. The product line that were mostly
>interested in using FEA is a product made with turned metal pieces, but
>we also have a product line that is a composite made of urethane and
>polyester.
A Finite Element analysis for composite materials are very
complicated. A very good understaning of material behavior is
necessary. In many cases were you have polyester or rubber you have
also contact and friction, what makes the subject even worse. Even
with a FE-package like ABAQUS, which is brilliant for composites ,
other nonlinear materials and contact you have to carry out a lot of
test and prediction work to correlate your analysis. But the needed
CPU time and the necessary disk space makes the analysis nearly
impossible for big FE-models, specialy on PCs.
However, if you have a good understanding of your boundary conditions
and you are not interested in the exact stress and strain in your
structure, it should be possible to carry out some simple predictions
like linear static analysis to find critical regions. Together with
your test work, which you have to do on your first prototype, you can
determine if a predicted stress peak gets worse. Then you have the
possibility to implement design changes to your FE-Model and verify
the improvements. You can compare different design changes and
determine which one you will implement in your next prototype. This
should help you to decrease your design loops and save some
prototypes. At least it will give you a better understanding of your
product.
>I am leaning towards Ansys's AutoFEA 2D/3D package. I know I would be
>giving up a lot of control and complexity of the analysis, but I just
>can't believe that I'll have the time to do the job correctly with a
>full blown package. Of course, I might just be wimping out too :-)
>I still think that the AutoFEA package with some simplified models will
>speed up the process and I wondering if I'm kidding myself or
>underestimating what I can do. It also helps that AutoFEA is AutoCAD
>based, but I would probaly jump to ACAD's Mechanical Desktop for the
>ease of 3D editing.
This is what I would suggest:
- Simplify your FE-Analysis as much as possible.
- Use an easy to use FEA-package, which has a very good link to CAD.
(I am sorry, but I don't know AutoFEA)
- Don't look to much in to detail of nonlinear FE-analysis.
- Use the FE-analysis not to determine exact stress and strain,
but use it for comparison and design optimisation.
- Use always your engineering backround together with FEM
>Any helpful feedback would be greatly appreciated,
>Grant
Don't be afraid to get you feet into FEM as a designer. There are to
many specialists out there who are spending an imensous time to
predict highly nonlinear stuff and come up with result, when the
design is already in production.
Best regards
Dipl.-Ing. Luis Hoeks
mech@luho.ac.eunet.de
CAE specialist
Subject: Re: Comma versus decimal point
From: systech@polarnet.com (Ken Irving)
Date: Mon, 30 Sep 1996 22:21:48 GMT
In article <52oad0$76c@fstgal00.tu-graz.ac.at>, kirchweg@sztms.tu-graz.ac.at
says...
>
>By the way, what's a lot more annoying is the way you (Americans) write
>dates. Why do you put moths first, days second and year last?
>
>That's illogical as hell.
>
Now, wait a minute, I'm American (well, Alaskan, but that's close :-))
and I write dates like 30sep96. Of course, numerically I've got to use
9/30/96 (as you accuse) to communicate with others around here...
And I've got no great problem with what arbitrary symbol is used for any
iven purpose, so long as the choices used are clear in context.
--
Ken
Subject: Re: Paints and Coating Systems
From: handreas@msmail4.hac.com (Andreas, Harry A)
Date: 30 Sep 1996 18:33:20 GMT
In article <528kst$lf3@niven.ksc.nasa.gov>, Greg Praino
wrote:
> I'm looking for alternative coating systems that can be used on mobile
equipment (tanker
>trucks, trailers, carts, etc...). The system we currently use consists
of an inorganic zinc
>primer, epoxy midcoat and polyurethane topcoat. If anyone has any ideas
or suggestions, I'd
>appreciate whatever you can come up with. The main concerns are the life
of the coating and
>ease of maintenance.
> Thanks in advance for any help. You can post your responses here or
e-mail them to me at
>gregory.praino-1@ksc.nasa.gov
My personal favorite is the self-priming topcoat developed by the Navy for
aircraft use, TT-P-2756.
It is a polyurethane that can be applied by several methods, has low VOC,
and does not require the base coat[s]. We have qualified it for airborne
use on both exposed and protected surfaces, applied on aluminum, steel and
SS, and Ti. Didn't work so good on Magnesium, but we don't use it anymore
anyway. Seems to last many years in the service we've been using it for
with little or no touchup required.
If you are having abrasion problems due to road dirt, etc. try an
elastomeric primer coat underneath it, TT-P-2760. This was specifically
created for erosion applications.
I won't comment on relative cost other than to say it's very application
specific and depends on the amount of VOCs you want emitted from the
number of coats you apply, and the local labor costs per coat.
good luck and let me know what you decide. curious minds at work.
Harry
--
A professional is a person who can do his best at a time when he doesn't
particularly feel like it. -Alistair Cooke
Subject: HVACcalc software - simplifies many HVAC design problems
From: Jerold Griffiths
Date: 1 Oct 1996 02:40:51 GMT
HVACcalc is a software simulation of a hardware calculator with specific
aids for use in HVAC design work. Entering data is as simple as clicking
on, e.g. numeric keys and observing the display.
Features:
Built-in formulas:
* Displays duct size in inches given friction loss and volume of air
or velocity of air
* Displays flow rate in gallons per minute given heat capacity and
temperature drop
Built-in tables :
* Rectangular duct equivalents - ASHRAE table
* Copper tubing dimensions and properties - ASHRAE table
* Furnace fan data - displays horsepower and RPM given pressure and
volume of air
* Ampacity for any size wire - NEC tables 310-16 and 310-17
* Grounding conductor sizes - NEC table 250-96
* Number of conductors for any size wire and any size conduit -
NEC table 3B
40 instant Metric conversions -
* Length, area, volume, weight, heat, pressure, temperature, power,
density, volume of air and velocity of air
Printing mode -
* Use computer printer as a printing calculator
Use as a standard decimal, Metric(millimeters), or feet-inches-fractions
calculator with 9 memories
* Calculate directly in feet-inches-sixteenths using the unique 0 - 15
keypad
DOS application that also works in Windows 3.1 or 95
Illustrated flyer available by fax
**** ORDER COD ! ****
Price : $39.95, includes shipping and COD charges to anywhere in USA
Foreign customers just send an International Money Order for $39.95
payable in US dollars.
Contact: JB Software
6611 Burkett St.
Houston, texas 77021
Voice: 713-747-8315, fax: 713-747-5569
Subject: Re: Combustion efficiency based on ambient temperatures?
From: pbarnes@iserv.net (P Barnes)
Date: Tue, 01 Oct 1996 05:24:27 GMT
onielsen@bart.nl@mail.bart.nl wrote:
>>
>>Ok, so you won't answer the question. I'll try, though I am not an
>>engineer. But I was a boilerman. And I have a few questions.
>>
>>1. Every car I've had uses more gas in the winter. (weak, but hey)
>>2. A car engine wants to operate at @195F degrees, if only for purposes
>>...
>Your higher fuel consumption in winter is not necessarily caused by lower
>engine efficiency but by higher aerodynamic drag on the car. If the air is
>say 30 degrees C colder in the winter it will be about 10% denser. This means
>10% higher drag that must be compensated by higher power output from
>the engine.
Ok so if the air is denser, then more O2 in the intake, so engine is
slightly more efficient. I don't know by how much, but shouldn't this
offset the "higher drag?"
One factor in lower fuel mileage in winter is the fact that the engine
is run richer during warm up. Especially if short trip driving occurs
often.
Subject: Re: 4 cycle vs. 2 cycle engine
From: clwhitney@berlen.bdsnet.com (Chris Whitney)
Date: Tue, 01 Oct 1996 03:03:10 GMT
The erudite mind of rrs@saba.kuentos.guam.net (Rey Ramirez Sangueza)
having written:
>as far as standby generators are concerned....could anyone out there
>explain to me the difference between a 4 cycle diesel engine versus a 2
>cycle diesel engine??? (comparing fuel efficiency, emissions, which is heavier
>duty, which is more reliable)
You specifically have indicated a "standby" generator, which I presume
to be small - say less than 1000 kW size. In this instance, whether
or not it is a 2 stroke or 4 stroke is not so important. 2 strokes
are basically Detroit diesels these days, almost everyone else makes 4
strokes. 2 strokes are typically somewhat lighter for a given output,
and simpler, without the overhead valves of a 4 stroke. They
typically have somewhat poorer fuel consumption, and somewhat poorer
emissions, but these days the differences are not so great. For a
standby machine, I would say it wouldn't make too much difference.
If in fact you are referring to large diesels, say sized 5,000 -
60,000 kW, rather than the small standby sets, you are in a different
regime of engines. In this arena, 2 strokes are MUCH larger and
heavier than 4 strokes and are available in higher output levels,
today up to about 60 MW or so. These 2 strokes are also known as
slow-speed diesels, typically operating at 70-200 RPM. 4 stroke
medium speed engines (400-900 RPM) are available today up to about 25
MW or so.
The two strokes have the advantage of slightly better fuel
consumption, and are perceived to have better reliability (very
debate-able). They are more expensive and take longer to deliver than
4 stroke medium speeds, and they have worse emissions. Far more
medium speed, 4 stroke engines are sold for power plant use than slow
speed 2 strokes.
I work for an engine builder.....
Subject: nd source: industrial locks
From: cokin@primenet.com (Darren Cokin)
Date: 30 Sep 1996 21:21:02 -0700
I am a mechanical engineer/inventor. I've got an idea for a new type of
bike lock, and would like to build a prototype. (It won't compete
directly with Kryptonite type devices, it would suppliment them.)
One key to the devices success will be its size. It must be as small as
possible. Therefore it must be designed around the locking mechanism.
But I can't find one to design too! It'll need one of those locks with
the pins arranged in a circle, not inline, like those used on vending
machines and Kryptonite style bike locks. You can't find locks like that
in your local locksmith shop. I would like to find a company that sells
such locks, preferably not as part of any device, just the lock itself.
If the prototype is successful, I might return and purchase a large number
of these locks, so hopefully they will be cheap when ordered in bulk.
If anyone could point me to a reputable supplier, I would be thankfull.
If there is one a convinient distance from my home in Santa Monica, CA,
all the better. Thanks.
Darren
Subject: Solving system of nonlinear equations for Multibody Simulation
From: Joel Shellman
Date: Tue, 01 Oct 1996 14:45:51 +0900
Thanks for all the help so far on this topic. I've got the equations
now, i think, but the Newton Rhapson method using LU decomposition (or
Gaussian Elimination) isn't converging for me.
my equations are:
For each body: (3D vectors: X, acurrent is current angle vector)
Xcurrent - ( (Fbody+Fjoints)*dt*dt/(2*mass) + Velocity*dt + Xinitial ) =
0.0
acurrent - ( (Tbody+Tjoints)*dt*dt/(2*mass) + AngVelocity*dt + ainitial
) = 0.0
For each Joint: ( Alow is lower body rotational matrix; X.fromCM is
vector from center of mass to joint in relative coords )
( Xlow.CM + ( Alow * Xlow.fromCM ) ) - ( Xup + ( Aup * Xup.fromCM ) ) =
0.0
My coordinates are all the position coords, angle coords ( three
rotations about X, Y, Z axes in that order ) and the joint forces.
For the two body problem I'm working on, it's a 15 x 15 Jacobian matrix
that i solved for symbolically using the above equations and so use that
to get ther jacobian.
Can anyone suggest what might be going wrong? I'm not sure if it's just
because the inaccuracy of double floating points or because my equations
or what is wrong. The joint forces used to alternate between 4
different values but after changing some stuff (using LU decomposition
instead of Gaussian) now they're getting large.
I realize it could be lots of things. I've been fighting with it for a
while now, but... Any special considerations that i might not know?
any help is appreciated.
thank you,
-joel