COMPUTATIONAL METHODS IN ENGINEERING AND SCIENCE
EPMESC X, Aug. 21-23, 2006, Sanya, Hainan, China
2006 Tsinghua University Press & Springer
A Web-Based Data Management and Decision Support System for
Slope Safety Inspection and Evaluation
J. Wang1*, M. C. Hung2
1
2
Department of Civil Engineering, Tamkang University, Tamsui, Taipei County, Taiwan, China
MIS Division, Yosun Industrial Corp., Taipei, Taiwan, China
Email: [email protected]
Abstract This paper examines how artificial intelligence and WWW technologies can be applied to disaster
management to improve the current practice. Using slope safety inspection and evaluation as an example, a
web-empowered database and decision support system was built. The system architecture, knowledge
representation, management procedure and technology issues are presented in this paper. We also discuss
the result of initial test of the prototype paradigm.
Key words: expert systems, data monitoring, Internet, WWW, web programming
INTRODUCTION
Monitoring systems are used in many areas in civil engineering [1], such like deep excavation, slope safety
inspection, reservoir operation, etc. The data collected from monitoring systems can support management
decision-making, which can strengthen the prevention of disasters. Most monitoring systems are
purpose-built hardware and software combinations. The accessibilities of the systems are usually poor,
because users have to manipulate the systems on specific computers at certain locations.
The objective of the project reported is to build a slope safety monitoring data management and decision
support system based on Internet technology for residential communities on hillsides. Users can perform
data management directly through the browser interface without any knowledge of database and query
language. Furthermore, the system is capable of adding communities and instruments, as well as other text
and image information of the communities on-line. As for safety evaluation, rule-based reasoning is used to
decide the safety degree of every monitoring instrument.
The system was implemented with the three-tier software architecture. The web-based environment let users
use standard WWW browsers to enter, inquire and manage monitoring data without installing additional
programs. The inference engine of the system is WebExpert [2], a product of Wise Web Ware Inc., installed
on a MS 2000 server with IIS. Its programming language is based on CLIPS [3], a lisp like and rule-based
language. In addition, the system incorporates dynamic graph generation together with a friendly user
interface implemented in HTML and JavaScript, etc.
The system performs as an efficient tool for the safety inspection and evaluation of hillside residential
communities. It acts as a collaboration portal that collects monitoring data, text and picture information from
field safety inspectors at different locations. Also, it acts as an information and data visualization portal with
various graph generation and decision support functions for government officials to evaluate the safety of the
communities. In the subsequent sections, we will first introduce the background of the project and web
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technologies involved, and discuss the system design issues in details and its impact on the overall operation
of the safety-monitoring project in Taipei County, Taiwan.
BACKGROUND
The disasters of slope collapse at hillside residential communities occur frequently in Taiwan in recent years.
The reasons that cause these disasters can be attributed to many factors, such as soil conservation,
earthquake, design and construction quality, etc. However, the main reason should be attributed to the
overdevelopment of land to release the pressure of population upsurge. As a result, to establish a disaster
prevention system for the hillside communities has become an urgent issue to the residents and Taiwan
government.
To install a monitoring system is a typical solution, which is a good way to prevent the disaster by constantly
inspecting these communities. Unfortunately, the collection, storage, share and analysis of these monitoring
data might become a problem considering the data amount and the timing issue involved when a critical
decision has to be made in time. Every community has dozens of monitoring stations, and the communities
are usually located at dispersive places. Therefore, the collection and management of these monitoring data
are a burden for the inspectors. Furthermore, the timely transmission of emergence on-site inspection
information, such as photos, drawings, measurements and evaluation comments, to the disaster prevention
office is also very important.
The intention of this project was to make use of the technology of Internet to develop a web-based data
management and decision support system for slope safety inspection and evaluation. The system is designed
to collect all the related information into a database and provide convenient tools for both the inspectors and
decision-making government officials to deal with the information entering and analysis tasks. No special
user training and program installation are required since web browser interface was used. Processing all
information on the web also shortens the official document transmitting time. Reports, figures and
documents can be printed from the system, making the running of the safety-monitoring plan more efficient.
In addition, the system is scaleable. New communities and monitoring instruments as well as descriptions
and illustrations can be added and updated on-line. Details of the system design and architecture are given
later.
WEB-BASED INFERENCE
Common Gateway Interface [4], CGI, is a standard interface for external programs and applications to
communicate with HTTP servers. The operation of our system is mostly based on the CGI technique. The
user interface of the system is composed of HTML, DHTML, JavaScript, etc. Through the Common
Gateway Interface, the system gives responses via WebExpert, the inference engine installed on the server.
The data management and decision support system was implemented with the C Language Integrated
Production System (CLIPS) language [3, 5] and WebExpert [2] extensions for web-based access.
WebExpert offers a collection of web-related functions built on top of CLIPS. Both tools feature a
declarative knowledge representation, offer forward-chaining reasoning through a match-recognize-act
cycle, and use Forgey’s RETE algorithm to optimize pattern matching. The web-based operating
environment let users use Internet browsers to enter, inquire and manage monitoring data without installing
other systems or programs.
Furthermore, WebExpert has the following features that are important to this project:
y WebExpert operates in a CGI mode and is compatible with many operation systems, such as
Macintosh, UNIX, LINUX, or Windows, etc. It can be used with many popular HTTP servers, such
as IIS, Apache, etc.
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y WebExpert provides several methods to save the system states, such as facts, cookies, templates, or
database, etc. These help resolve the persisting state problem, which enable the working memory of
facts of concurrent users be differentiated and passed from one browser session to another.
y WebExpert is capable of generating dynamic figures on the fly. Basic graphic functions are
included to draw new and modify existing GIF files.
y WebExpert supports ODBC database access. It provides database connections to several relational
databases, such as MS Access, MS SQL Server, etc.
In fact, other solutions were explored at the beginning of the project, such as ASP, JSP, PHP, etc.
Nevertheless, rule-based expert system technology has great advantages. With its declarative representation,
it is very flexible and easy to maintain. Its powerful rule-based reasoning and pattern-matching algorithm
capabilities are essential for further expansion of the decision support requirement.
SYSTEM REQUIREMENT ANALYSIS
There are three types of perspective users for the system, the site inspectors, the government officials and
community residents as shown in Figure 1. Their needs are diverse. The different functional requirements
are analyzed in the following subsections.
1. Site inspectors Using the conventional approach, all the information, including monitoring data,
document reports and image files, has to be entered into the computer and database by MIS engineers. The
benefit of the new web-based system is that the inspectors can enter the monitoring data and other
information directly in web browsers through network. This avoids a lot of paper works and document
travel, which makes the inspection work possible under insufficient government budgets. Also, the
monitoring data can be updated in a timely immediate manner.
2. Government officials In the past, conventional decision support and monitoring programs usually
operated on self-contained proprietary systems because of the limitation of the software and hardware. In
this situation, the disaster control center or the decision-making office has to operate the system on particular
computers at particular location when they need to analyze the data and make tactical decisions. Using the
new Internet technology and web-based interface, users can operate the system anywhere via popular web
browsers, most likely Netscape Browsers or Internet Explorers. Officials at different government offices can
access the same database and knowledge base, and work together in a collaborative manner.
Figure 1: Overview of the slope monitoring system
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3. Community residents In general, conventional decision support and database systems run on some
specific servers or workstations. However, the web-based interface and associated database of the system
can provide much wider services to different users at different locations. For example, it can provide safety
information to the residents of the community being inspected, which satisfies the knowing right of the
citizen and make the government’s operation transparent and under supervision.
SYSTEM IMPLEMENTATION AND DESIGN
The system runs on a Windows 2000 server with IIS4.0 and connects to the external database through
ODBC. The users interface is developed using DHTML and JavaScript. User inputs and requests are sent to
WebExpert on the server by Common Gateway Interface (CGI). Figure 1 shows the overall architecture of
the system.
The relational database system adopted should support ODBC and SQL [6]. Our database now stores data of
thirty-six communities in Taipei County. There are six tables in the database schema and their relations are
shown in Figure 2.
The system design concept is based upon the requirements of different user groups described in the previous
section. Basically, the system consists of three major functions, data query, data management and decision
support. These functions can be further divided into seven modules as shown in Figure 3. Their descriptions
are as follows:
Figure 2. Database schema
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Figure 3: System architecture
1. Communities information module This module contains information about the general description of
the communities, safety inspection plans, instrument location maps, pictures and history of special incidents.
2. Monitoring data inquire module The main function of this module is to query the database for
instrument readings. Readings of a single instrument or multiple instruments during a particular period can
be queried and listed. Historical data can also be illustrated on diagrams to show the trend of changes.
Examples of the user interfaces for this module are given in Figure 4.
3. Monitoring data management module The data management functions include the entering, deletion,
and updating of the readings. A very user-friendly feature is that the users can manage the data directly on
the drawing diagrams by clicking on the data points on the diagrams. Following the popup window’s
instruction, data in the database can be updated. Two web interface windows for this module are shown in
Figure 5.
4. Image management module Besides the monitoring data, the image data let users realize the
surroundings of the communities and inspection stations easily. A picture is worth a thousand words. Slope
safety problems can be easily explained and documented with pictures. The inspectors can upload the most
recent images onto the server directly through the web interface (Figure 6). Image file management is also
provided through the web interface.
5. Community management module One design goal of the system is to make it expandable. Adding new
communities and monitoring instruments do not have to be done at the database side. Community
information management can be carried out by users with proper authorization, which include updating
existing community information, and adding new communities and monitoring instruments online through
the easy-to-use web interface.
6. Emergency report module When special evidence is discovered on site, the inspector has to compose a
report and send it through the conventional government document process channel. This is not very efficient.
The executive officials may not get the first-hand information in time to make a timely decision. The system
offers three different processes to expedite the report. Figure 7 explains its features and process procedure.
Figure 8 is example of its online interface.
7. Safety evaluation module The module provides a convenient utility for the user to overlook hundreds of
monitoring instruments quickly. Statistics calculations and inference rules are used to classify the safety
degree of the communities based on safety index thresholds, critical limits, monthly-accumulated deviations
and daily-average changes. These have predefined settings and can be adjusted on the web interface
according to the condition of individual communities. The results of the evaluation will be shown on the
community map using different colors to represent different safety degrees. It is very clear to the users what
the safety situation of the community under supervision is. Figure 9 shows its typical operations.
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Figure 4: Monitoring data query and charting windows
Figure 5: Data management interfaces
DISCUSSIONS AND FUTURE WORKS
There are a lot of incentives to use web browsers as the user interface as mentioned earlier in the paper.
However, its programming techniques and considerations are different from conventional applications
development in Civil Engineering.
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Figure 6: Image management interfaces
Figure 7: Emergency reporting process
Figure 8: Emergency incidents reporting and query
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Figure 9: Safety evaluation features
The database connections are easy to solve with the current technology. The most serious problem comes
from browser compatibility. In order to develop a GUI with interactive features, DHTML and client-side
script language have to be used to improve efficiency. An important decision was make at the beginning of
the project, which is the system development have to maintain cross-platform compatibility both on the
server and client sides. Therefore, the system can be develop once and accessed on different computing
platforms through the standard HTTP protocols. Nevertheless, the incompatibility of Netscape and Internet
Explorer in JavaScript make the implementation difficult. Actually, IE use JScript, and Netscape use
JavaScript. What makes the problem worse is that even with the same product line, different version of the
browser may have different behavior. We spent a lot of time searching for compatibility solutions and
sometimes the page codes have to be composed into different versions for different web browsers. Our
conclusion is that user-side environment is very hard to control. Server-side solutions like JSP may be a
better direction to go.
Because of the budget and development timetable, the system did not include the precise geographic
information. It is possible in the future to extend the system’s architecture to link to a GIS with additional
data in its database. Wireless and mobile site data entry devices, like PDAs, handheld PCs and tablet PCs, are
also under evaluation to fully exploit the mobility of the system architecture and to benefit from the
cross-platform and web-based approach.
Acknowledgements
Financial support for this project from Taipei County Government of Taiwan is gratefully acknowledged.
REFERENCES
1. Wang Ryan Sheng-ming, 921 Chi-Chi Earthquake Database Analysis and Management System.
Science Development, 2000; 29: 9-13.
2. WebExpert Technical Reference Manual, Wise Web Ware, Inc., 2001.
3. Riley G. CLIPS: A Tool for Building Expert Systems. http://www.ghg.net/clips/CLIPS.html, accessed
March 2006.
4. Hamilton JD. CGI Programming 101, 1998.
5. Giarratano J, Riley G. Expert Systems: Principles and Programming. PWS Publishing Company, 1998.
6. Date CJ. An Introduction to Database Systems. 6th Edition, Addison-Wesley, 1995.
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