- Email: [email protected]
An expert system for teaching concrete mix design
0360-1315189 S3.Mlt0.00 Copyright ,c 1989 Pcrgamon Press pk
Compums Edur. Vol. 13, No. 1, pp. 6946, 1989 Printedin Great Bdtatn. All rights reserved
AN EXPERT
SYSTEM FOR TEACHING MIX DESIGN
CONCRETE
SIRIPONG MALASRI* and SANTIAC~ MALDONADO Department of Civil and Architectural Engineering, University of Miami, Coral Gables, FL 33124, U.S.A. (Receired
4 January
1988; in recked form 24 June
1988)
Abstract-An expert system has been developed for teaching concrete mix design using the Personal Consultant Plus expert system development tool. Several useful features for education purposes are discussed. The system is highly interactive and allows the student to ask questions such as WHY an input data is need or HOW a certain parameter or a conclusion is derived. Several graphics images and help messages are incorporated into the system. The system contains answers to several fundamental questions on the mix design process. Programming techniques are also presented. This paper demonstrates that educational software can be easily developed using an expert system development tool.
INTRODUCTION
Computers have been used traditionally in the educational environment as a problem soIving tool. Students have been taught to program computers in various programming languages or to use large application programs. Computers, later, have been used as a teaching tool to enhance the understanding of a certian subject area. A good eductional software should incorporate several features such as the interactive feature, user friendliness, graphical display, and “Glass-box” feature. A considerable amount of time is required to develop such a system using a conventional programming language. A tool could be used to facilitate the development of such software such as the use of LOTUS l-2-3 spreadsheet program[l] as mentioned in a previous work[2]. Recently, the expert system technology has become a new tool in solving problems in various disciplines such as business and engineering. In the past, the development of an expert system was difficult and computer specialists were often needed. The cost to develop a system for educational uses was not justified to many institutions where the educational software development is considered to be a luxury item and of low priority. At present, there are many expert system development tools available commercially[3]. These tools facilitate the development of expert systems. Many of these tools run on low-cost microcomputers. Using expert systems in the educational environment is now justified for both the software development cost and the hardware cost. An expert system has been developed for teaching concrete mix design to civil and architectural engineering undergraduates. The Personal Consultant Plus (PC Plus) [4] expert system development tool was utilized. The first prototype of this system was reported earlier in an American Concrete Institute publication [5]. Many modifications have been made and many educational features have been added to that prototype such as more explanation screens, more help screens, and etc. Some parts were completely rewritten using different programming approaches. This paper first describes useful educational features of the Concrete Mix Designer. Programming techniques are then discussed to show how these educational features were implemented. EDUCATIONAL
FEATURES OF MIX DESIGNER
There are many educational features incorporated This section demonstrates some of these features.
THE
CONCRETE
in the Concrete Mix Designer expert system.
*Present address: Department of Civil Engineering, Christian Brothers College, Memphis, TN 38104-5581, U.S.A.
70
SIRIPONG MALASRI
Logic and know/edge
and SANTIAGO M.ALM~ADO
base transparency
The student can ask WHY an input data is needed, HOW the value of a parameter is computed, or HOW a conclusion is made. The system responds to WHY and HOW questions by displaying the rule it utilized. Figure 1 shows an input screen where the severe exposure condition is needed. The student may want to know why this information is required in the mix design process. Figure 2 shows the response to the WHY question. Figure 3 shows a conclusion screen. The student may want to know how the system determined the water-cement ratio. The system responds to the HOW question by displaying a rule in the window as shown in Fig. 4. The ability to answer such HOW and WHY questions makes the logic used by the system transparent, The student learns by asking the system questions as he or she would ask an instructor. The knowledge base of a typical expert system is stored separately from other parts of the system. PC Plus uses IF-THEN rules for knowledge representation which make the knowledge base transparent. Samples of IF-THEN rules are shown in Figs 2 and 4 which can be easily understood by students who do not have any background in expert systems or PC Plus. HELP facility
PC Plus allows the expert system developer to provide HELP messages for each input parameter. When the system asks for a certain input data, the user simply presses the Fl function key to see help messages. Figure 5 shows a help screen that provides additional information for concrete strength. A help screen could also be replaced by a graphics screen. Graphics help screens are not implemented in the current version of the Concrete Mix Designer since all help messages are relatively short and can be sufficiently described by texts. Using graphics will be discussed in a later section. Questions
and answers
There are several fundamental questions that have been constantly asked by students or those who are new to the concrete technology. Many of these questions were published in an American Concrete Institute publication[6]. Some of these questions and answers were implemented into the system. Figure 6 shows the menu for a list of questions related to the slump determination. Figure 7 shows the answer screen for the first slump question. These questions and answers provide the student with a tutorial on several fundamental concepts in concrete technology. Using LOTUS
123 graphics for obtaining
input data
Water-cement ratio is an important information for the system to determine the proportion of the mix. The system uses a recommended average value suggested in a literature[7]. Depending on types of ingredients used, the value may not follow this recommended average value. Many times the user would like to obtain a more realistic proportion by performing a trial mix in the laboratory. CONCRETE
What
is the
severe
exposure
XIX
DESIGNER
condition
(Version
of the
2.0)
structure?
Wet continuously and exposed to freezing and thaving. Wet frequently and exposed to freezing and thawing. Exposed to sea water. Exposed to sulfates.
1. Use the arrow keys 2. Press RETURN/ENTER
or first letter to continue.
o f item
Fig. 1. An input screen.
to position
the
cursor.
Expert system far teaching concrete mix design CONCRETE fhat is the severe
HIX DESIGNER
exposure
condition
uet continuously and exposed _1J+..r‘ 1 Exposure condition is needed for axpooura condition “,.I
.
(Version
71
2.0)
of the structure?
to freezing
and thawing.
~
maximum
to determine
water-cement
ratio
/
RULE010 I) If
question for severe exposure is YES, and sire of strxture is All other structures., and 1) exposure condition is Wet continuously and exposed to 31 freezing and thevmq., or 2) exposure condition is Wet frequently and exposed to freezing and thawing., Then it is definite (100%) that maximum water-cemmt ratio for exposure condition is 0.5. 2)
I
i* End - RETURN/ENTER
l
2.
Press RETURN/ENTER
to continue to continue.
Fig.2. Response to the WHY question.
CONCRETE Conclusiono: 1 Maximum recommended recommended
Hinimum
MIX DESIGNER
slump
inches
is
slump
inches
is as follows:
of water
Amount
of cement
in lb/cu.yd.
Rmount
of coarse
aggregate
Amount
of
in lb/cu.yd.
The Note is es folloua: moisture in the aggregates. measurable
l *
of
amount
of
***
concrete
In
1
as follows:
concrete
270 566.95652 113913
is as follows:
is as folloVs:
1863.
1185.55890431074
ere
practice, l
3
is as follows:
of
corrections
moisture.
End - RETURN/ENTER
is
of concrete
in lb/cu.yd.
sand in lb/cu.yd.
2.0)
folIous:
concrete
of
Amount
as
(Version
needed to compensate aggregates vi11 contain
for coma
**
to continue
Fig. 3. A conclusion screen.
CONCRETE
MIX DESIGNER
(VOrSiOn
2.0)
elusions: imum recommended water-cement
slump
inches
is
as
follows:
3
ratio
Determined to be: 0.46 -.. by using RULE027 If
maximum
permisible
vatar-cement
ratio is greater
than
or
equal to
0,
Then 1) it is definite
floor) that maximum pena. waeer-cement r?ItfO, used as goal in the SLUMP frame is maxflaum permisible vater-cement ratio, and ratio is maximum perm. 2) it is definite (1002) that water-cement vat4r-cement ratio, used 1~s goal in the SLUMP frame.
**
End
- RETURN/ENTER
t0
Continue
Fig. 4. Response to the HOW question.
72
SIRIPOSC MALASRI
CONCRETB %t is the specified
and SANTIAGOMALDONAW
KIX DESIGNER
compressive
(version 2.0)
strength
psi 7
The knowledge system was developed for normal weight concrete with the strength ranging from 2500 psi to 5000 psi without any admixture. l * End - RETURN/ENTER to continue
1. Enter a positive number. 2. Press P.BTUP.N/ENTER to continue.
Fig. 5. A HELP screen.
A graph of the strength of concrete vs the water-cement ratio is plotted from laboratory results. With this graph, a proper value of water-cement ratio can be read for a desired strength. In the previous system[5], the student has to plot this graph manually to get the water-cement ratio. In the current system, however, the system uses a spreadsheet program where input data from !aboratory can be directly input. The spreadsheet program, then, plots the graph as shown in Fig. 8. The value of water-cement ratio can be read and passed back to the system. This automates the derivation of an input data directly from the laboratory data. The student can also see the effect of the water-cement ratio to the strength of concrete directly from this graph which is a very important concept in the concrete technology. Using graphics for explanation
Some explanations are better described using pictures than using texts. For each major operation in the Concrete Mix Designer, a graphics screen is displayed. Figure 9 is a graphics screen that explains how a slump is determined in the laboratory. PROGRAMMING
This section describes some programming of the Concrete Mix Designer. CONCRETE Please select
a SLUMP-frame
MIX
CONSIDERATIONS
techniques used in implementing educational features
DESIGNER
(Version
2.0)
question:
What iS meant by CONSISTENCY ? What is meant by PLASTIC MIXTURE 7 What is meant by WORKABILITY ? What is the result of having dry and very fluid consistancias Is proper consistency important ? What part does air entrainment play in workability ? Is the slump test a good guide to consistency 1 When is the slump test a useful indication of workability 7 How do we make the slump test ?
1. Use the arrow keys or first letter of item to position 2. Press RETURN/ENTER to continue.
Fig. 6. A questions list of the questions/answers.
1
the cursor.
Expert system for teaching concrete mix design CONCRETE
CONSISTENCY is defined freshly aixed concrete slump. l * End - RETD?&/ENTER
MIX DESIGNER
73
(Version 2.0)
as the fluidity of to flow. The Usual
It is the ability of CONSISTENCY is
Concrete. measure
to continue
Fig. 7. An answer screen of the questions’answers
Water- cement ratio vs strength
z t 'Z $ k E s
4.2 4.4 3.6 3.6 3.4 3.2 3.0 -
I 0.35
0.45
0.55
Water -cement
0.65
0.75
ratio
Fig. 8. Spreadsheet graph.
The goal
the
slump
of the of
the
SLUMP frame concrete.
is to determine
1Slum?
test
Fig. 9. A graphics explanation screen.
procedure:
of its
SIRPONG MALASRIand SANTIAGOMALDONADO RULE015 ----___
[WC-RULES]
IF: THEN:
DATA
= “available”
DOS-CALL "C:\LOTUS\123.COM" "123.SET" AND DOS-CALL "GWBASIC.EXE" "A:RENAME" AND READ-FROM-FILE "A:WCRATIO" MAXWCt
Fig. 10. External program interface.
Integrating external programs into the system PC Plus allows the external program execution External programs can be written in any language as long as they are in the executable form. Concrete Mix Designer executes the LOTUS l-2-3 speadsheet program so that the laboratory data can be plotted and the water-cement ratio can be read as mentioned earlier. Figure 10 shows the rule that performs this task. DOS-CALL is the system function for the external program execution. The external program in this case is the spreadsheet program 1-2-3.COM. The water-cement ratio from the spreadsheet program is then read back to the system using the READ-FROM-FILE system function. Details of interfacing LOTUS l-2-3 spreadsheet program to PC Plus can be found in another work[8]. It should be noted that the rule shown in Fig. 10 is implemented by the developer using the Abbreviated Rule Language (ARL) as opposed to the English translation for the end-user as previously shown in Figs 2 and 4. Integrating text jile into the system In the previous version of the system[5], several questions/answers modules were implemented using the external program interfacing technique. These external programs were written in BASIC. Based on a recent experience in developing another expert system for a building code[9], a new better technique has been used. A word processor is used to create ASS11 text files. These text files are read back into the system. Since a text file is treated as a data file to the expert system, it can be later updated, modified, and maintained by the end-user without changing the internal structure of the expert system. Figure 11 shows a sample of a data file named SLUMP1 . RD. This provides an answer to a question related to the slump determination. PC Plus requires the extension RD for all data files. Since PC Plus is a LISP based expert system, all values must be parenthesized. Double quotes differentiate the character type data from the numeric type data. Figure 12 shows a rule that brings up this data file. The READ-FROM-FILE function is used to read the text file into the system which is displayed with the PRINT function. Integrating graphics into the system PC Plus allows several ways of incorporating graphics. Graphics can be easily created using a graphics editor, such as TelePaint[lO], PC Palette[ll] etc., or a drafting software, such a AutoCAD [12] etc. A PC Plus utility program is used to capture this picture and store it in a picture file on disk. This graphics screen can be brought up in the system. This picture can be integrated into the expert system as a title screen, an explanation screen, an help screen, an input screen, or a conclusion screen. In the current version of the Concrete Mix Designer, pictures are used only as explanation screens. The Concrete Mix Designer is divided into several parts, each part (or frame) performs a specified task. When a part is entered, an explanation screen is displayed to explain general background related to that particular part. The picture, as shown in Fig. 9, is brought up using a frame property, GPROMPTEVER (graphics prompt). A frame can have several properties in which GPROMPTEVER is a property to display a graphics screen when the frame is activated. Figure 13 shows SLUMP frame properties, where the “SLUMP.GRI” picture type slumpl.rd ("CONSISTENCY is defined as the fluidity of concrete. It is the ability of freshly mixed concrete to flow. The usual measure of CONSISTENCY is its slump.")
Fig. I I. A sample of an ASCII text file.
Expert system for teaching concrete mix design RULE007 ---s-e_
[SLIJMP-RULES:
IF:
THEN
75
AND
SLUM?-QVESTION Q-SLL%P = ‘%%a:
AND
READ-FROM-FILE PRINT (VALS’E
:
=
“yes”
is meant
by
CONSISTS’NCY
7‘
“A: SLUMPl” AN.5SLIJMPl)
Fig. 12. ASCII text file interface
CONCRET2
rframe
“IX
DESIGNER
(V.raion
2.0)
fruns MIHSWYP
*“cs‘“up
propsrttaa:SL”“P
determination PIS‘UWP YAY.SL.““P
TRANSLATION co*‘9
::
Slump
INITIALDATA CPROwT2YER IDENTIFIER
:: : : : :
PASLVMP “SLUMP” “SLUMP-”
IPurp0.e
ok-
::
description
or
the
YAXK
. . .
rrame
I
Fig. 13. Frame properties.
file is displayed as a prompt when the frame is entered. Details of how a picture is created and how the utility program is used to capture and store the picture can be found elsewhere[l3]. Creating help messages
Help messages are created as a parameter property. A parameter could have several properties similar to frame properties. HELP is a property to display help messages when the student presses the Fl function key. Figure 14 shows the STRENGTH parameter properties where help messages are assigned to the HELP property. The help messages are displayed when requested as shown previously in Fig. 5. DISCUSSION
AND CONCLUSION
Several educational features of the Concrete Mix Designer as well as programming techniques were presented. Using expert system development tools, such as PC Plus, facilitates the development of an expert system. There are, however, limitations which come with each tool. This is true with the PC Plus package. PC Plus is not designed to handle complex numerical computation CONCBET2 -Parameter:FCP TRANSLATION PROMPT HELP
EXPECT RANGE TTPE
:: :: ::
:: :: ::
MIX
specified
Ih.t Ihe
ia
DESIGNER
compressive the specified
ho.led2e POSITIVE-NUMBER 2500 5000 SINGLEVALUED
sy,te”,
(Version
2.0)
strength (psi) compressive stren;th ..s
developed
Fig. 14. Parameter properties.
f-or
norsal
(-.. . .
76
SIRIFONG MALASRI and SANTIAGO MALWNADO
which are important in many engineering applications. This limitation, however, can be overcome by using the external program interface as mentioned earlier so that the complex computations can be performed in the external program written in a conventional programming language. The graphics interface mentioned allows only predrawn pictures. These pictures are static. The same external program interface could be used to overcome this limitation such as the use of the spreadsheet graph in the Concrete Mix Designer. This spreadsheet graph is dynamic and changed according to the laboratory data entered by the student. Another limitation of PC Plus is the speed. This limitation will be, however, improved with the advancement of the hardware. PC Plus has several built-in functions for accessing dBASE[13] databases. Records could be added, updated, or retrieved. To use the feature, the user must have an access to the dBASE software. PC Plus does not have its own database management features. It only executes the dBASE software and transfers the data back to the system. This feature, however, is not currently used in the Concrete Mix Designer. Details of the database access can be found elsewhere[ 151. Good education software can be developed in a relatively short time and therefore with a reasonable cost if proper tool and technology are utilized. REFERENCES 1. Lotus development Corp., L0TLi.S 123 Release 2.0 (1985). 2. Malasri S. and Syed-Mohammad-Ridzuan S., Education software development using spreadsheet program. Int. J. Appl. Engng Educ. 3(l), 55-58 (1987). 3. Harmon P., Maus R. and Morrissey W., Erperr Systems Tools and Applications. Wiley, New York (1988). 4. Texas Instruments. Personal Consultant Plus Version 2.UI (1985). 5. Malasri S. and Maldonado S., Concrete Mix Designer. Stare-of-(he-Art Computer Applications in Concrete Technology (Edited by Fagundo F.). American Concrete Institute (1988/1989). (In press). 6. McMillan F. R. and Tuthill L. H., Concrete Primer. AC1 Publication SP-I (1987). 7. Portland Cement Association, Design and Control of Concrete Mixtures. 12th edn (1979). 8. Malasri S., PC Plus + LOTUS 123. Microcomputer Knowledge-based Expert Systems in Civil Engineering (Edited by Adeli H.), pp. 79-87. American Society of Civil Engineers (1988). 9. Malasri S., A prototype expert system for South Florida building code. Proc. 1988 Floridu Sections Meeting of the American Sociery of Cicil Engineers (1988). IO. LCS/Telegraphics., TelePaint Version 2.2 (1985). Il. IBM., PC Paliette Version 1.00 (1984). 12. AutoDesk Inc., AufoCAD Version 2.52 (1986). 13. Malasri S. and Kengskool K., Graphics interface of an expert system shell. Proc. NCGA’88, National Compufer Graphics Associafion, Vol. III, pp. 556562 (1988). 14. Ashton-Tate, dBASE III Plus Version I.0 (1986). 15. Malasri S., Data base access using an expert system shell. ICES’88 Post Conference Seminar (Edited by Yamada Y. and Atluri S. N.), pp. l-10 (1988).
Compums Edur. Vol. 13, No. 1, pp. 6946, 1989 Printedin Great Bdtatn. All rights reserved
AN EXPERT
SYSTEM FOR TEACHING MIX DESIGN
CONCRETE
SIRIPONG MALASRI* and SANTIAC~ MALDONADO Department of Civil and Architectural Engineering, University of Miami, Coral Gables, FL 33124, U.S.A. (Receired
4 January
1988; in recked form 24 June
1988)
Abstract-An expert system has been developed for teaching concrete mix design using the Personal Consultant Plus expert system development tool. Several useful features for education purposes are discussed. The system is highly interactive and allows the student to ask questions such as WHY an input data is need or HOW a certain parameter or a conclusion is derived. Several graphics images and help messages are incorporated into the system. The system contains answers to several fundamental questions on the mix design process. Programming techniques are also presented. This paper demonstrates that educational software can be easily developed using an expert system development tool.
INTRODUCTION
Computers have been used traditionally in the educational environment as a problem soIving tool. Students have been taught to program computers in various programming languages or to use large application programs. Computers, later, have been used as a teaching tool to enhance the understanding of a certian subject area. A good eductional software should incorporate several features such as the interactive feature, user friendliness, graphical display, and “Glass-box” feature. A considerable amount of time is required to develop such a system using a conventional programming language. A tool could be used to facilitate the development of such software such as the use of LOTUS l-2-3 spreadsheet program[l] as mentioned in a previous work[2]. Recently, the expert system technology has become a new tool in solving problems in various disciplines such as business and engineering. In the past, the development of an expert system was difficult and computer specialists were often needed. The cost to develop a system for educational uses was not justified to many institutions where the educational software development is considered to be a luxury item and of low priority. At present, there are many expert system development tools available commercially[3]. These tools facilitate the development of expert systems. Many of these tools run on low-cost microcomputers. Using expert systems in the educational environment is now justified for both the software development cost and the hardware cost. An expert system has been developed for teaching concrete mix design to civil and architectural engineering undergraduates. The Personal Consultant Plus (PC Plus) [4] expert system development tool was utilized. The first prototype of this system was reported earlier in an American Concrete Institute publication [5]. Many modifications have been made and many educational features have been added to that prototype such as more explanation screens, more help screens, and etc. Some parts were completely rewritten using different programming approaches. This paper first describes useful educational features of the Concrete Mix Designer. Programming techniques are then discussed to show how these educational features were implemented. EDUCATIONAL
FEATURES OF MIX DESIGNER
There are many educational features incorporated This section demonstrates some of these features.
THE
CONCRETE
in the Concrete Mix Designer expert system.
*Present address: Department of Civil Engineering, Christian Brothers College, Memphis, TN 38104-5581, U.S.A.
70
SIRIPONG MALASRI
Logic and know/edge
and SANTIAGO M.ALM~ADO
base transparency
The student can ask WHY an input data is needed, HOW the value of a parameter is computed, or HOW a conclusion is made. The system responds to WHY and HOW questions by displaying the rule it utilized. Figure 1 shows an input screen where the severe exposure condition is needed. The student may want to know why this information is required in the mix design process. Figure 2 shows the response to the WHY question. Figure 3 shows a conclusion screen. The student may want to know how the system determined the water-cement ratio. The system responds to the HOW question by displaying a rule in the window as shown in Fig. 4. The ability to answer such HOW and WHY questions makes the logic used by the system transparent, The student learns by asking the system questions as he or she would ask an instructor. The knowledge base of a typical expert system is stored separately from other parts of the system. PC Plus uses IF-THEN rules for knowledge representation which make the knowledge base transparent. Samples of IF-THEN rules are shown in Figs 2 and 4 which can be easily understood by students who do not have any background in expert systems or PC Plus. HELP facility
PC Plus allows the expert system developer to provide HELP messages for each input parameter. When the system asks for a certain input data, the user simply presses the Fl function key to see help messages. Figure 5 shows a help screen that provides additional information for concrete strength. A help screen could also be replaced by a graphics screen. Graphics help screens are not implemented in the current version of the Concrete Mix Designer since all help messages are relatively short and can be sufficiently described by texts. Using graphics will be discussed in a later section. Questions
and answers
There are several fundamental questions that have been constantly asked by students or those who are new to the concrete technology. Many of these questions were published in an American Concrete Institute publication[6]. Some of these questions and answers were implemented into the system. Figure 6 shows the menu for a list of questions related to the slump determination. Figure 7 shows the answer screen for the first slump question. These questions and answers provide the student with a tutorial on several fundamental concepts in concrete technology. Using LOTUS
123 graphics for obtaining
input data
Water-cement ratio is an important information for the system to determine the proportion of the mix. The system uses a recommended average value suggested in a literature[7]. Depending on types of ingredients used, the value may not follow this recommended average value. Many times the user would like to obtain a more realistic proportion by performing a trial mix in the laboratory. CONCRETE
What
is the
severe
exposure
XIX
DESIGNER
condition
(Version
of the
2.0)
structure?
Wet continuously and exposed to freezing and thaving. Wet frequently and exposed to freezing and thawing. Exposed to sea water. Exposed to sulfates.
1. Use the arrow keys 2. Press RETURN/ENTER
or first letter to continue.
o f item
Fig. 1. An input screen.
to position
the
cursor.
Expert system far teaching concrete mix design CONCRETE fhat is the severe
HIX DESIGNER
exposure
condition
uet continuously and exposed _1J+..r‘ 1 Exposure condition is needed for axpooura condition “,.I
.
(Version
71
2.0)
of the structure?
to freezing
and thawing.
~
maximum
to determine
water-cement
ratio
/
RULE010 I) If
question for severe exposure is YES, and sire of strxture is All other structures., and 1) exposure condition is Wet continuously and exposed to 31 freezing and thevmq., or 2) exposure condition is Wet frequently and exposed to freezing and thawing., Then it is definite (100%) that maximum water-cemmt ratio for exposure condition is 0.5. 2)
I
i* End - RETURN/ENTER
l
2.
Press RETURN/ENTER
to continue to continue.
Fig.2. Response to the WHY question.
CONCRETE Conclusiono: 1 Maximum recommended recommended
Hinimum
MIX DESIGNER
slump
inches
is
slump
inches
is as follows:
of water
Amount
of cement
in lb/cu.yd.
Rmount
of coarse
aggregate
Amount
of
in lb/cu.yd.
The Note is es folloua: moisture in the aggregates. measurable
l *
of
amount
of
***
concrete
In
1
as follows:
concrete
270 566.95652 113913
is as follows:
is as folloVs:
1863.
1185.55890431074
ere
practice, l
3
is as follows:
of
corrections
moisture.
End - RETURN/ENTER
is
of concrete
in lb/cu.yd.
sand in lb/cu.yd.
2.0)
folIous:
concrete
of
Amount
as
(Version
needed to compensate aggregates vi11 contain
for coma
**
to continue
Fig. 3. A conclusion screen.
CONCRETE
MIX DESIGNER
(VOrSiOn
2.0)
elusions: imum recommended water-cement
slump
inches
is
as
follows:
3
ratio
Determined to be: 0.46 -.. by using RULE027 If
maximum
permisible
vatar-cement
ratio is greater
than
or
equal to
0,
Then 1) it is definite
floor) that maximum pena. waeer-cement r?ItfO, used as goal in the SLUMP frame is maxflaum permisible vater-cement ratio, and ratio is maximum perm. 2) it is definite (1002) that water-cement vat4r-cement ratio, used 1~s goal in the SLUMP frame.
**
End
- RETURN/ENTER
t0
Continue
Fig. 4. Response to the HOW question.
72
SIRIPOSC MALASRI
CONCRETB %t is the specified
and SANTIAGOMALDONAW
KIX DESIGNER
compressive
(version 2.0)
strength
psi 7
The knowledge system was developed for normal weight concrete with the strength ranging from 2500 psi to 5000 psi without any admixture. l * End - RETURN/ENTER to continue
1. Enter a positive number. 2. Press P.BTUP.N/ENTER to continue.
Fig. 5. A HELP screen.
A graph of the strength of concrete vs the water-cement ratio is plotted from laboratory results. With this graph, a proper value of water-cement ratio can be read for a desired strength. In the previous system[5], the student has to plot this graph manually to get the water-cement ratio. In the current system, however, the system uses a spreadsheet program where input data from !aboratory can be directly input. The spreadsheet program, then, plots the graph as shown in Fig. 8. The value of water-cement ratio can be read and passed back to the system. This automates the derivation of an input data directly from the laboratory data. The student can also see the effect of the water-cement ratio to the strength of concrete directly from this graph which is a very important concept in the concrete technology. Using graphics for explanation
Some explanations are better described using pictures than using texts. For each major operation in the Concrete Mix Designer, a graphics screen is displayed. Figure 9 is a graphics screen that explains how a slump is determined in the laboratory. PROGRAMMING
This section describes some programming of the Concrete Mix Designer. CONCRETE Please select
a SLUMP-frame
MIX
CONSIDERATIONS
techniques used in implementing educational features
DESIGNER
(Version
2.0)
question:
What iS meant by CONSISTENCY ? What is meant by PLASTIC MIXTURE 7 What is meant by WORKABILITY ? What is the result of having dry and very fluid consistancias Is proper consistency important ? What part does air entrainment play in workability ? Is the slump test a good guide to consistency 1 When is the slump test a useful indication of workability 7 How do we make the slump test ?
1. Use the arrow keys or first letter of item to position 2. Press RETURN/ENTER to continue.
Fig. 6. A questions list of the questions/answers.
1
the cursor.
Expert system for teaching concrete mix design CONCRETE
CONSISTENCY is defined freshly aixed concrete slump. l * End - RETD?&/ENTER
MIX DESIGNER
73
(Version 2.0)
as the fluidity of to flow. The Usual
It is the ability of CONSISTENCY is
Concrete. measure
to continue
Fig. 7. An answer screen of the questions’answers
Water- cement ratio vs strength
z t 'Z $ k E s
4.2 4.4 3.6 3.6 3.4 3.2 3.0 -
I 0.35
0.45
0.55
Water -cement
0.65
0.75
ratio
Fig. 8. Spreadsheet graph.
The goal
the
slump
of the of
the
SLUMP frame concrete.
is to determine
1Slum?
test
Fig. 9. A graphics explanation screen.
procedure:
of its
SIRPONG MALASRIand SANTIAGOMALDONADO RULE015 ----___
[WC-RULES]
IF: THEN:
DATA
= “available”
DOS-CALL "C:\LOTUS\123.COM" "123.SET" AND DOS-CALL "GWBASIC.EXE" "A:RENAME" AND READ-FROM-FILE "A:WCRATIO" MAXWCt
Fig. 10. External program interface.
Integrating external programs into the system PC Plus allows the external program execution External programs can be written in any language as long as they are in the executable form. Concrete Mix Designer executes the LOTUS l-2-3 speadsheet program so that the laboratory data can be plotted and the water-cement ratio can be read as mentioned earlier. Figure 10 shows the rule that performs this task. DOS-CALL is the system function for the external program execution. The external program in this case is the spreadsheet program 1-2-3.COM. The water-cement ratio from the spreadsheet program is then read back to the system using the READ-FROM-FILE system function. Details of interfacing LOTUS l-2-3 spreadsheet program to PC Plus can be found in another work[8]. It should be noted that the rule shown in Fig. 10 is implemented by the developer using the Abbreviated Rule Language (ARL) as opposed to the English translation for the end-user as previously shown in Figs 2 and 4. Integrating text jile into the system In the previous version of the system[5], several questions/answers modules were implemented using the external program interfacing technique. These external programs were written in BASIC. Based on a recent experience in developing another expert system for a building code[9], a new better technique has been used. A word processor is used to create ASS11 text files. These text files are read back into the system. Since a text file is treated as a data file to the expert system, it can be later updated, modified, and maintained by the end-user without changing the internal structure of the expert system. Figure 11 shows a sample of a data file named SLUMP1 . RD. This provides an answer to a question related to the slump determination. PC Plus requires the extension RD for all data files. Since PC Plus is a LISP based expert system, all values must be parenthesized. Double quotes differentiate the character type data from the numeric type data. Figure 12 shows a rule that brings up this data file. The READ-FROM-FILE function is used to read the text file into the system which is displayed with the PRINT function. Integrating graphics into the system PC Plus allows several ways of incorporating graphics. Graphics can be easily created using a graphics editor, such as TelePaint[lO], PC Palette[ll] etc., or a drafting software, such a AutoCAD [12] etc. A PC Plus utility program is used to capture this picture and store it in a picture file on disk. This graphics screen can be brought up in the system. This picture can be integrated into the expert system as a title screen, an explanation screen, an help screen, an input screen, or a conclusion screen. In the current version of the Concrete Mix Designer, pictures are used only as explanation screens. The Concrete Mix Designer is divided into several parts, each part (or frame) performs a specified task. When a part is entered, an explanation screen is displayed to explain general background related to that particular part. The picture, as shown in Fig. 9, is brought up using a frame property, GPROMPTEVER (graphics prompt). A frame can have several properties in which GPROMPTEVER is a property to display a graphics screen when the frame is activated. Figure 13 shows SLUMP frame properties, where the “SLUMP.GRI” picture type slumpl.rd ("CONSISTENCY is defined as the fluidity of concrete. It is the ability of freshly mixed concrete to flow. The usual measure of CONSISTENCY is its slump.")
Fig. I I. A sample of an ASCII text file.
Expert system for teaching concrete mix design RULE007 ---s-e_
[SLIJMP-RULES:
IF:
THEN
75
AND
SLUM?-QVESTION Q-SLL%P = ‘%%a:
AND
READ-FROM-FILE PRINT (VALS’E
:
=
“yes”
is meant
by
CONSISTS’NCY
7‘
“A: SLUMPl” AN.5SLIJMPl)
Fig. 12. ASCII text file interface
CONCRET2
rframe
“IX
DESIGNER
(V.raion
2.0)
fruns MIHSWYP
*“cs‘“up
propsrttaa:SL”“P
determination PIS‘UWP YAY.SL.““P
TRANSLATION co*‘9
::
Slump
INITIALDATA CPROwT2YER IDENTIFIER
:: : : : :
PASLVMP “SLUMP” “SLUMP-”
IPurp0.e
ok-
::
description
or
the
YAXK
. . .
rrame
I
Fig. 13. Frame properties.
file is displayed as a prompt when the frame is entered. Details of how a picture is created and how the utility program is used to capture and store the picture can be found elsewhere[l3]. Creating help messages
Help messages are created as a parameter property. A parameter could have several properties similar to frame properties. HELP is a property to display help messages when the student presses the Fl function key. Figure 14 shows the STRENGTH parameter properties where help messages are assigned to the HELP property. The help messages are displayed when requested as shown previously in Fig. 5. DISCUSSION
AND CONCLUSION
Several educational features of the Concrete Mix Designer as well as programming techniques were presented. Using expert system development tools, such as PC Plus, facilitates the development of an expert system. There are, however, limitations which come with each tool. This is true with the PC Plus package. PC Plus is not designed to handle complex numerical computation CONCBET2 -Parameter:FCP TRANSLATION PROMPT HELP
EXPECT RANGE TTPE
:: :: ::
:: :: ::
MIX
specified
Ih.t Ihe
ia
DESIGNER
compressive the specified
ho.led2e POSITIVE-NUMBER 2500 5000 SINGLEVALUED
sy,te”,
(Version
2.0)
strength (psi) compressive stren;th ..s
developed
Fig. 14. Parameter properties.
f-or
norsal
(-.. . .
76
SIRIFONG MALASRI and SANTIAGO MALWNADO
which are important in many engineering applications. This limitation, however, can be overcome by using the external program interface as mentioned earlier so that the complex computations can be performed in the external program written in a conventional programming language. The graphics interface mentioned allows only predrawn pictures. These pictures are static. The same external program interface could be used to overcome this limitation such as the use of the spreadsheet graph in the Concrete Mix Designer. This spreadsheet graph is dynamic and changed according to the laboratory data entered by the student. Another limitation of PC Plus is the speed. This limitation will be, however, improved with the advancement of the hardware. PC Plus has several built-in functions for accessing dBASE[13] databases. Records could be added, updated, or retrieved. To use the feature, the user must have an access to the dBASE software. PC Plus does not have its own database management features. It only executes the dBASE software and transfers the data back to the system. This feature, however, is not currently used in the Concrete Mix Designer. Details of the database access can be found elsewhere[ 151. Good education software can be developed in a relatively short time and therefore with a reasonable cost if proper tool and technology are utilized. REFERENCES 1. Lotus development Corp., L0TLi.S 123 Release 2.0 (1985). 2. Malasri S. and Syed-Mohammad-Ridzuan S., Education software development using spreadsheet program. Int. J. Appl. Engng Educ. 3(l), 55-58 (1987). 3. Harmon P., Maus R. and Morrissey W., Erperr Systems Tools and Applications. Wiley, New York (1988). 4. Texas Instruments. Personal Consultant Plus Version 2.UI (1985). 5. Malasri S. and Maldonado S., Concrete Mix Designer. Stare-of-(he-Art Computer Applications in Concrete Technology (Edited by Fagundo F.). American Concrete Institute (1988/1989). (In press). 6. McMillan F. R. and Tuthill L. H., Concrete Primer. AC1 Publication SP-I (1987). 7. Portland Cement Association, Design and Control of Concrete Mixtures. 12th edn (1979). 8. Malasri S., PC Plus + LOTUS 123. Microcomputer Knowledge-based Expert Systems in Civil Engineering (Edited by Adeli H.), pp. 79-87. American Society of Civil Engineers (1988). 9. Malasri S., A prototype expert system for South Florida building code. Proc. 1988 Floridu Sections Meeting of the American Sociery of Cicil Engineers (1988). IO. LCS/Telegraphics., TelePaint Version 2.2 (1985). Il. IBM., PC Paliette Version 1.00 (1984). 12. AutoDesk Inc., AufoCAD Version 2.52 (1986). 13. Malasri S. and Kengskool K., Graphics interface of an expert system shell. Proc. NCGA’88, National Compufer Graphics Associafion, Vol. III, pp. 556562 (1988). 14. Ashton-Tate, dBASE III Plus Version I.0 (1986). 15. Malasri S., Data base access using an expert system shell. ICES’88 Post Conference Seminar (Edited by Yamada Y. and Atluri S. N.), pp. l-10 (1988).