bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosecurity in agriculture: an economic analysis of coexistence of professional and hobby production*
Authors: Ceddia Michele Graziano , Heikkilä Jaakko , Peltola Jukka
Published: November 2008

One component of biosecurity is protection against invasive alien species, which are one of the most important threats worldwide to native biodiversity and economic profitability in various sectors, including agriculture. However, agricultural producers are not homogeneous. They may have different objectives and priorities, use different technologies, and occupy heterogeneous parcels of land. If the producers differ in terms of their attitude towards invasive pests and the damages they cause, there are probably external effects in the form of pest spread impacts and subsequent damages caused. We study such impacts in the case of two producer types: profit‐seeking professional producers and utility‐seeking hobby producers. We show that the hobby producer, having first set a breeding ground for the pest, under‐invests in pest control. We also discuss potential policy instruments to correct this market failure and highlight the importance of considering different stakeholders and their heterogeneous incentives when designing policies to control invasive alien species.
Missing markets for storage and the potential economic cost of expanding the spatial scope of water trade
Authors: Brennan Donna
Published: November 2008

A great deal of attention has been given in recent years to the question of externalities associated with water entitlements and how third parties can be protected without restricting opportunities for water trade. Yet one market failure that has received no attention at all is the missing market for storage that arises from the specification of water entitlements, particularly in Victoria where historically all storage decisions were made at the centralised level and where any additional carryover was treated as common property. The economic significance of the missing market for storage is demonstrated using an empirical model that represents the spatial‐temporal pattern of irrigation water demand in the Goulburn Valley and decisions regarding inter‐year storage of water in Lake Eildon. It is shown that, because irrigators have no incentive to trade‐off the benefit of current use (or sale) with the value of water storage, there is an erosion of reliability when opportunities for trade are broadened. The empirical results demonstrate that the loss in economic value associated with reduced reliability are as large as the gains from trade, so there is no net benefit from trade.
Artificial Intelligence Software Engineering in Building Engineering
Authors: POYET PATRICE , DUBOIS ANNE‐MARIE , DELCAMBRE BERTRAND
Published: November 2008

This article provides a review of two main research projects carried out at the French Scientific and Technical Center for Building (CSTB) in the area of artificial intelligence applied to building engineering. We first describe the software engineering techniques used to develop the computer environments. Then we present the architecture of an advanced multiservice computer system offering capabilities comprising retrieval facilities, hypertext editing of documents (e.g., unified codes of practice, regulations), object‐oriented database management, and multifunctional expert systems. Finally we discuss a major multiactor computeraided design project aiming to provide a framework able to combine the sundry contributions of the various actors involved in the building design process. The expected results of such projects are a panel of complementary capabilities either aiming at satisfying multiservice requirements for an isolated designer or at providing a single but cooperative and computer‐assisted process to different actors. Of course, merging the respective capabilities of these tools is a very promising perspective.
Neural Networks in Structural Engineering
Authors: VANLUCHENE R. D. , SUN ROUFEI
Published: November 2008

In the past few years literature on computational civil engineering has concentrated primarily on artificial intelligence (Al) applications involving expert system technology. This article discusses a different Al approach involving neural networks. Unlike their expert system counterparts, neural networks can be trained based on observed information. These systems exhibit a learning and memory capability similar to that of the human brain, a fact due to their simplified modeling of the brain's biological function. This article presents an introduction to neural network technology as it applies to structural engineering applications. Differing network types are discussed. A back‐propagation learning algorithm is presented. The article concludes with a demonstration of the potential of the neural network approach. The demonstration involves three structural engineering problems. The first problem involves pattern recognition; the second, a simple concrete beam design; and the third, a rectangular plate analysis. The pattern recognition problem demonstrates a solution which would otherwise be difficult to code in a conventional program. The concrete beam problem indicates that typical design decisions can be made by neural networks. The last problem demonstrates that numerically complex solutions can be estimated almost instantaneously with a neural network.
Flexible Automation for Servo‐Controlled Testing
Authors: GOPALARATNAM VELLORE S. , YANG GWO‐SYANG
Published: November 2008

The paper presents an efficient method of flexibly automating test control and data acquisition functions for servo‐controlled testing. A systems analysis approach coupled with structured design is used in developing the system. With hardware that includes (a) a personal computer, (b) a servo‐controlled electrohydraulic testing machine equipped with a special type of digital function generator, and (c) a multipurpose data acquisition board, an automated test control and data acquisition system for servo‐controlled materials/structural/mechanical testing has been developed. The servo‐controlled materials/structural/mechanical testing system allows (1) automated control of the test, (2) rapid and reliable acqusition of several channels of data from static or fast‐rate tests subject to periodic or nonperiodic loading, and (3) realtime (or nearly real‐time) graphics of the test characteristics in order to allow the operator to monitor the test. The communication and postprocessing options allow user‐supplied software to be incorporated into the automated system for advanced non‐real‐time functions. These options include noise filtering, signal averaging, mathemtical analyses and processing, report quality graphics, and file transfer features. The system features have been validated through a series of load‐controlled direct tension tests on an aluminum specimen. The system has been used for successfully carrying out an elaborate research program on fracture toughness testing of fiber‐reinforced concrete in a flexural loading configuration.
Scheduling Parallel Computations with Successive CPM Domains
Authors: SCHMIDT RICHARD J. , HORNING DENNIS
Published: November 2008

This paper describes a functional procedure for implementation of structural engineering applications in an asynchronously scheduled multi‐processor environment. A modification to the classical critical path method is proposed that permits scheduling of networks that contain conditional branching or loops. A general outline is presented, describing the functional requirements of two utility procedures that generate a priority list for scheduling tasks for the particular algorithm of interest. These list‐generating utilities, operating with a driver program, work with a modified version of SCHEDULE (a list scheduler) to allocate tasks to processors in an order determined using the weighted‐priority heuristic. Programming difficulties inherent in schedule implementation for both shared memory systems and loosely coupled systems (with emphasis on hypercubes) are discussed. The approach is demonstrated on the subspace iteration algorithm.
Automatic Partitioning of Frame Structures for Concurrent Processing
Authors: KAMAL O. , ADELI H.
Published: November 2008

An efficient 3‐stage algorithm for automatic partitioning of frame structures is presented. Once the input data of the structure is fed into the computer, the domain is partitioned into a number of subdomains equal to the number of the specified processors. The underlying concept is to preprocess the input data in such a manner that subsequent analysis and optimal design steps can be carried out efficiently on multiprocessor computers. Emphasis is directed towards attaining a balance of workload among the processors, minimizing the bandwidth within each subdomain, and minimizing the number of linear equations to be solved for the interface degrees of freedom. All the vectors involved in the partitioning algorithm are integers, requiring a small storage and resulting in calculations that can be processed fast. The algorithm is specially suitable for analysis and design of large structures such as space stations. The algorithm presented is hardware independent. Our applications, however, are limited to the Encore Multimax shared memory computer. The efficiency of the algorithm is demonstrated through partitioning several truss and frame problems, for a variable number of processors.
A Stochastic Decision Model for Contractor Prequalification
Authors: RUSSELL JEFFREY S. , BENSON CRAIG H. , FOX PATRICK J.
Published: November 2008

In the construction industry, contractor prequalification is the process used to determine each contractor's competence to participate in a project bid. Contractors unqualified or overextended should be eliminated prior to the bidding process. Thus, prequalification can conserve resources of both the owner and the participating contractors. This article describes a computer program, QUALIFIER‐1.5, which is based in part on a previously developed prequalification program, QUALIFIER‐1. A brief description of QUALIFIER‐1 is provided for background information. Next, the stochastic decision model incorporated in QUALIFIER‐1.5 and a Monte Carlo simulation procedure are highlighted. An investigation into whether the aggregate rating is normally distributed has been performed and is described. The software is described along with an example application. A comparison of the two programs is also provided. The benefit of this program over prior work is that uncertainty in the prequalification process can be incorporated into the decision‐making process.
Pavement Distress Analysis Using Image Processing Techniques
Authors: Mahler David S. , Kharoufa Zuhair B. , Wong Edward K. , Shaw Leonard G.
Published: November 2008

Abstract: We demonstrate the feasibility of applying image processing techniques to the analysis of pavement distress due to cracking. Pavement image samples were obtained using a custom‐designed data acquisition system called the Automatic Crack Monitor (ACM). The image samples conteining pavement cracks are parameters, are extracted using techniquesw described in this paper. The crack parameters are necessary measures used in calculations of the Pavement Serviceability Index (PSI), which is used by highway maintenance engineers to decide whether a certain pavement section needs to be repaired. Experimental results are shown and the potential harware implementation of the developed techniques is also discussed.
Block Band Matrix Subspace Iteration
Authors: Leung A. Y. T.
Published: November 2008

Abstract: For a microcomputer user in civil engineering, the. major factor of concern is not necessarily the computing time but the incore memory. It is particularly important for dynamic and nonlinear analyses. Solution techniques employing secondary memory to extend the capacity of a microcomputer in solving engineering problems are active research topics. There are many engineering problems which have regular data structures, e.g. tall buildings, long bridges, etc. Band matrix solution techniques are suitable for regular data structures. A partitioned matrix method is introduced for the engineering eigenvalue problem here. Static solutions are included as particular cases. FORTRAN listings are given.
Online Documentation for Engineering Software: A Hypertext Application
Authors: Malarsi S. , Olabe‐Basogain J. C.
Published: November 2008

Abstract:This article describes the use of ‘hypertext’ as a means to document engineering software online. An extensive hypertext document can be built with relative ease using an authoring tool. Hypertext documents enhance the learning process through the association of facts. The user has the freedom to arrange his/her own study sequence in a particular session. The article provides a brief introduction to the hypertext technology and authoring tools, and describes a Mohr's Circle program, which has been developed to explore the use of hypertext for online users' manuals. The strengths and weaknesses of the software tool, KnowledgePro, as well as the development techniques, are discussed.
Measuring Productivity and Validating Microcomputer Simulation
Authors: AbouRizk Simaan M. , Halpin Daniel W. , Hill Stephen L.
Published: November 2008

Abstract: Computer simulation can provide an eficient and cost‐effective method of analyzing project alternatives, resource constraints and potential progress. It is frequently performed to study the behavior of a system in an attempt to improve performance. There are many different analytical methods that can be used to plan or analyze a construction operation. However, in most cases, analytical techniques require abstractions which tend to reduce confidence in model predictions. These methods do, however, offer a basis for validating simulation results. This paper illustrates how Micro CYCLONE, a microcomputer‐based simulation language, can be used to measure job productivity in construction. It also illustrates how BetaFit, a microcomputer‐based program, can be used to model accurately and eficiently random processes for use in the simulation experiments. The paper also presents a framework for validating construction simulation by reviewing the application of two analytical methods. A roof truss process is modeled using the CYCLONE methodology and then validated using queueing theory and method productivity delay modeling to illustrate the various procedures.
Computer‐Assisted Welding Robot for Steel Structures
Authors: Nakagomi Tadao , Karube Masahiko , Yamamoto Kiyoshi , Iwata Mamoru
Published: November 2008

Abstract: This paper introduces the application of a robot to CO2 gas shielded arc welding in the construction of steel structures. In shop welding, using horizontal position welding makes the construction process easier and more efficient. Technically, however, horizontal position welding is more difficult than the flat position one. So we have developed a horizontal position multilayer welding system by introducing a robot to the CO2 gas shielded arc welding of steel structures where semiautomatic welding has been used. The situation where we can use this welding robot is in a single beveled horizontal position butt weld in a steel structure. In this paper, first we explain the structure of a welding robot system, followed by the results of a mechanical property test consisting of a tensile, impact test (based on the Japan Industrial Standard) and a full‐size three‐point bending test. These results were as good as those for semiautomatic welding. Using this horizontal position multilayer welding robot system, the burden of the welding operator will be reduced, and we will be able to obtain more easily constant high‐performance horizontal position welding.
Graffiti: A Computer‐Aided Construction Process Knowledge‐Based System
Authors: Paul Jean Claude , Gertsch Damien , Pytel Laurent
Published: November 2008

Abstract: This paper presents a computer‐aided construction process program based on a heuristic research knowledge‐based system, logical procedures for constraints propagation, as well as on operational research algorithms. The system is interactive: it is the user, not the program, who controls the heuristic research. Furthermore, it is graphics oriented: a reflexive architecture between the knowledge‐based system and a geometrical modeller allows permanent graphic visualization of the work in progress. The application presented includes a variety of operations, ranging from the geometric modelling of the architectural project to the intelligent analysis of its structure, its division into component types (e.g. shuttering posts, beams, floors, walls) and the planning of the construction process (production cycles, tasks scheduling).

Tested by engineers of a private international building company, the system has now received new implementations, which allow us to simulate different technologies and modify very rapidly many various parameters, thus giving to the users a real computer‐aided construction process environment.
A Case Study in Spatial Configuration by a PDP Model
Authors: Yokozawa Masto , Watanabe Hitoshi
Published: November 2008

Abstract: This paper describes a classflcation learning system and its application. A PDP learning program (parallel distributed processing, or neural nets) learns from sample data and makes predictions for new cases. This inductive inference is capable of dealing with messy, real world data in architectural design. The authors report on experiments in which the PDP model was used to synthesis design generative rules for certain aspects of the spatial configuration of Japanese tea houses. The possibility of the PDP model as a design descriptive framework is explored.
A Local Database Manager for Engineering Analysis Systems
Authors: Stark Rudolf F.
Published: November 2008

Abstract: A local database manager (LDBM) is presented. It is a software development tool consisting of a set of easy‐to‐use in‐core data management subroutines written in FORTRAN 77. One of the main motivations for the development of this LDBM was to enhance the eflcient use of core memory which seems to be obvious with respect to a PC programming environment. However, even on virtual machines, high performance achieved by minimizing page faults is strongly based on a sophisticated database management system (DBMS). In order to accomplish this objective, the LDBM allows the use of different data types according to the requirements of the actual situation and to the existing programming environment. Integer, short integer, real, double precision, complex, double complex and character data can be handled. Moreover, a two‐level hierarchical data structure is used which groups related data in a different and more economic way rather than by means of increasing the number of levels in the DIMENSION statement. Of course, old, no longer used data may be deleted, leaving room for the allocation of new data. Using a technique of ‘flexible garbage collection’, i.e. the ensuing gap after the deletion of a data block is not automatically closed, the time consumed by the LDBM during a deletion operation is actually not affected by the length of data blocks.
A Large Matrix Reducgtion Method for Multiprocessors
Authors: Suto Fukuzo , Asayama Syuichi
Published: November 2008

Abstract: This paper treats a basic study on a methodology of large reduction of the huge stiffness matrix equation with many unknowns for application on very high speed supercomputer or connection machines. Until recently the substructured method according to the Neumann‐type single processing has been used for the above purpose, whereas the method described here differs from its predecessor as pertaining to non‐Neumann‐type plural processing by the system of multilinked computers. The characteristics of the method exist in an algebraic and mechanical idea for the very large structural matrix equation, to make it constitute a properly decided number of independently blocked‐in submatrix equations so as to be able to utilize the supercomputer or connection machines in the most eficient way. For this purpose, the method presented in this paper shows how to relocate and add rows and columns in the original structural stiffness matrix equation, taking the effective stiffnesses of intersected boundary members into proper consideration. Next, this method is applied to a simple rectangular frame as the first step, this time to consider and verifv its adequacy. Finally, some remarks are made on the comparative state between analytical results by this parallel processing for substructured matrices on it, and by the usual direct processing for its original matrix. It is concluded that the method presented here may be thought suficiently appropriate and useful for the object.
Optimum Design System for Steel Cable‐Stayed Bridges Dealing with Shape, Sizing Variables and Cable Prestresses
Authors: Ohkubo Sadaji , Taniwaki Kazuhiro , Yamano Nagahiro
Published: November 2008

Abstract: A general‐purpose, rigorous and efficient optimum design system for steel cable‐stayed bridges is developed, in which not only can the cable anchor positions on the main girder and pylon, and the crosssectional dimensions of the member elements be dealt with as design variables, but also the pseudo‐loads applied to the cables. A powerful two‐stage optimum design method is proposed to determine the optimum values of design variables for the cost minimization problem under stress constraints. At the first‐stage optimization process, the cable arrangement and sizing variables are optimized by using the approximate concept and dual method with mixed direct/inverse design variables. Then the optimum values of pseudoloads, which induce the optimum prestresses into the cables, and the optimum sizing variables are determined so as to minimize the total cost of the bridge further by utilizing the sensitivities with respect to the pseudo‐loads and a modified linear programming algorithm. The rigorousness, eficiency and practical usefulness of the proposed optimum design system are demonstrated by giving numerical design examples and the investigations of the optimum solutions at various design conditions. The significances of dealing with cable anchor positions and pseudo‐loads as design variables are also emphasized.
Generation of Hybrid Finite Element Mesh
Authors: Lo S. H. , Lau T. S.
Published: November 2008

Abstract: An algorithm is proposed for the generation of ‘hybrid’ finite element meshes composed of quadrilateral and triangular elements over any arbitrary planar domain. Although more complicated hybrid meshes are to be generated, the new meshing strategy does not require more input data than a correct representation of the domain boundary. Mesh generation is started by constructing as many square elements as possible in the interior part of the domain, leaving a relatively small region around the boundary which is to be tliscretized into triangular elements by standard triangulation procedures. As a result, only the quality of the triangular elements near the boundary will be affected by the irregularity of the domain. The extraction of the interior part and forming of square elements of an irregular domain will be discussed in detail. Examples of meshes generated over simply connected and multiconnected domains are given.
Fractals by Multigenerators
Authors: Leung A. Y. T. , Chaojun Luo
Published: November 2008

Abstract: Non‐classical fractals generated by many generators are of interest. Random fractals caused by the random action of given generators and by random generrrtors are discussed The generators may have different scales. The fractal spectral function, the generalized fractal dimensions and scaling index are derived explicitly. Examples include the cracking patterns of concrete mix.
Dynamic Intelligent Buildings Analytical Simulator
Authors: Kobori Takuji , Kamagata Shuichi
Published: November 2008

Abstract: Dynamic Intelligent Buildings (DIB) are the active seismic response controlled structures which replace the ordinary seismic structural elements with active controllers (AC). In this system the computer acts as the control unit for the AC. For the feasibility study of the DIB the authors develop a DIB analytical simulator and define the DIB response spectra, the AC performance spectra, and the DIB performance response surface from the analytical results. The DIB response properties of an active adustable stiffness system (A2S2) and an active counter force system (ACFS) are illustrated.
A GIS‐Based Traffic Signal Coordination and Information Management System
Authors: Sarasua Wayne A.
Published: November 2008

Abstract: This paper discusses research conducted at the Georgia Institute of Technology that investigated the use of geographic information system (GIS) technology as a tool in traffic signal information management and signalized intersection coordination. TRANSYT‐7F is the most widely used and respected computer model for optimizing the coordination of traffic signals. Unfortunately, creating an optimal TRANSYT‐7F model is very costly. The hypothesis of this research was that using a specialized GIS in conjunction with TRANSYT‐7F could enhance the process of coordinating a traffic signal system. The research resulted in the development of a GIS‐based traffic signal coordination and information system that operates on a microcomputer. This system is an improvement over existing TRANSYT‐7F models because relationships between intersections do not have to be encoded manually. Instead, the system takes advantage of the GIS's topologic data structure, which provides these relationships. The process of analyzing different network optimization scenarios is simplified with this system because the user need only to select intersections to be coordinated from the GIS graphic display rather than cutting and pasting from existing input files. Alternatively, the system can serve as a multipurpose signal information system and play a vital role in decision support. It can provide improved access to signal data and allows for swift identification of intersections that experience excessive delays or unacceptable levels of service.
An Approach for Integrating GIS and Watershed Analysis Models
Authors: DePinto Joseph V. , Calkins Hugh W. , Densham Paul J. , Atkinson Joseph F. , Guan Weihe , Lin Hui , Rodgers Paul W.
Published: November 2008

Abstract: The application of a dynamic watershed model requires efficient management and manipulation of large spatial and temporal data sets. Today's geographic information systems (GISs) offer many tools that can greatly facilitate the modeling process. The intention to link GIS and watershed analysis models has led to the design of an integrated system which is called GEO‐WAMS (Geographically Based Watershed Analysis and Modeling System).

GEO‐WAMS has been designed as a modeling support system. It consists of five components: a GIS‐based spatial/temporal data management system, an integrated watershed modeling system, a data‐model management interface, an analyst support toolkit, and an interactive user interface.

This paper introduces the general design of GEO‐WAMS as well as a more specific description of some of the capabilities that have been built into the GEO‐WAMS prototype system. The prototype couples a GIS (ARC/INFO) with a watershed loading model as well as a modified version of EPA's WASP4 model for simulation of dissolved oxygen in a receiving water body.
Finite‐Element Modeling of Storm Water Runoff Using GRASS GIS
Authors: Vieux Baxter E. , Gauer Nalneesh
Published: November 2008

Abstract: This paper presents methodologies used in the model r.water.fea for simulating storm water runoff using the finite‐element method and a raster geographic information system (GIS). The internally integrated model r.water.fea simulates storm water runoff by interfacing the raster data structure with the finite‐element solution of the kinematic wave equations. The integrated system offers many advantages because the GIS and simulation model exchange input and output data internally. Distributed simulation of the spatially and temporally variable hydrologic process is possible with r.water.fea. Storm water runoff simulated with r.water.fea compares favorably with analytic solutions for a simple domain. An example simulation of a catchment demonstrates the capabilities of r.water.fea.
GIS in Seismic Evaluation of Essential Facilities
Authors: Chang Tzyy‐Shiou , Kung Hsiang‐te , Pezeshk Shahram
Published: November 2008

Abstract: This research used PC ARC/INFO, a geographic information system (GIS), to assess the potential seismic vulnerability of essential facilities in Memphis and Shelby County, Tennessee. The GIS is a powerful tool for spatial operations. It offers a link between spatial data in a computerized map form and related nonspatial attribute files. It has the ability to overlay, compare, and analyze several maps in digital form with speed and efficiency. In order to assess the potential vulnerability of essential facilities, evaluation criteria with rational weighting (including soil type, liquefaction potential, slope, foundation, structural conditions, and important elements of bridges such as detour length and average daily traffic) were identified. This research proved that GIS is a reliable and efficient tool for vulnerability assessment of essential facilities in an earthquake‐prone area. The GIS is convenient and productive in data management. It is easy to produce special‐purpose maps at selected scale and tabular analysis reports in desired format. Results of the study are important for future facility maintenance and improvement and earthquake preparedness /response planning.
GIS‐Based Groundwater Modeling
Authors: Camp Charles V. , Outlaw James E. , Brown Michael C.
Published: November 2008

Abstract: A geographic information system (GIS) interface to the U.S. Geological Survey (USGS) groundwater flow model MODFLOW is developed. Geologic and hydrologic information is interpolated from borehole geophysical logs and associated pump tests to form a GIS well‐log database. The GIS‐MODFLOW interface targets a modeling area and interpolates the well database to create a three‐dimensional representation of the subsurface environment. An attribute mesh is developed which represents the geometric discretization of the study area and provides a means of relating hydrologic model parameters to each cell in the mesh. Information required for each simulation is automatically extracted from the attribute mesh. A brief introduction to the GIS program ARC/INFO emphasizing the characteristics of the data structure and the macro language is given. A groundwater flow model for a portion of Shelby County, Tennessee, is developed illustrating the advantages of the GIS‐MODFLOW interface and the attribute mesh system.
GIS‐Based Subsurface Data Management
Authors: Adams Teresa M.
Published: November 2008

Abstract: Effective subsurface data management is essential for economical and accurate site characterization. Subsurface data are directly related to specific locations on the earth's surface and thus appear to be well suited for GIS‐based management. However, subsurface data differ from traditional GIS data in that each sampled location includes information associated with multiple z coordinates below the surface. This paper describes the computational aspects of implementing a GIS‐based workbench for managing subsurface data and supporting site characterization. The scope of data management includes modeling, structure, standards, queries, sources, conversion, and integration. The concepts presented may assist application developers to fully utilize GIS technology as a major software component for effective subsurface data management.
Causal Network Models in Expert Systems
Authors: Castillo E. , Cobo A. , Gutiérrez J. M. , Iglesias A. , Sagástegui H.
Published: November 2008

Abstract:The paper describes causal network models, giving a detailed discussion of their basic assumptions and their associated algorithms for marginalization and updating. Conditional probability tables are shown to be the basis for the aggregation formulas of if‐then rules allowing for deriving the uncertainty of conclusions from that of premises. Examples of a pressure tank and a power system are used for illustrating the concepts and all steps of explained algorithms.
A Reasoning Method in Damage Assessment of Buildings
Authors: Liu Xila , Li Zhongfu
Published: November 2008

Abstract: This paper discusses sources of uncertainties in damage assessment of buildings and classifies reasoning methods (for two‐valued or continuous‐valued problems) and reasoning characteristics (certainty or uncertainty). Some new concepts, such as the variable‐independence and the characteristic factors, are defined to describe the damage assessment. A reasoning method called the combination function method is introduced to model the hierarchy inference process.
Linear Programming and Expert Systems
Authors: Jubete F. , Castillo E.
Published: November 2008

Abstract:This paper describes an expert system shell based on linear programming. The knowledge base consists of the parametric equations of the feasible set, which is obtained from upper and lower bounds of probabilities of given sets. The inference engine consists of an algorithm that gives the parametric equations of the feasible set and works in an incremental manner; any previously calculated feasible set is modified when new information becomes available, using all previous calculations. This allows for rapid updating of the knowledge base and permits a very quick solution of the optimization problems (finding of lower and upper bounds of the probability of any set) to be obtained. Finally, three civil engineering examples are included.
Uncertainty Measures in Expert Systems
Authors: Alvarez E. , Castillo E.
Published: November 2008

Abstract: In classic logic, premises, conclusions, and rules are treated deterministically, i.e., they are considered as either true or false. However, when dealing with reality, one finds that all these elements must be considered as uncertain. Thus classic logic must be extended to cover real situations. One possible extension is given by uncertainty measures together with aggregation formulas that combine the uncertainty of premises with that of the rules to obtain the uncertainty of conclusions. This paper describes different uncertainty measures, giving the physical meaning of the implied axioms and their limitations, illustrated by some examples. Finally, a classification of some of the well‐known uncertainty measures, such as belief and plausibility functions, probabilities, necessities, and possibilities, is given.
Comparing Uncertainty Management Techniques
Authors: Saffiotti Alessandro , Umkehrer Elisabeth , Parsons Simon
Published: November 2008

Abstract:Several formalisms for representing and reasoning with uncertain knowledge have been proposed in the artificial intelligence literature. Unfortunately, analyses of the adequacy of each formalism to different types of problems have seldom appeared, and designers are often forced to make arbitrary choices about how to model uncertainty in their domain. In this paper, we present an experimental approach to comparing uncertainty management techniques in the light of a specific problem to solve. We model a problem tailored on a real‐world application using three major techniques, namely, probability theory, Dempster‐Shafer's theory, and possibility theory, and discuss the results. We also propose a new qualitative way of analyzing the behavior of the three techniques that highlights some interesting assumptions. The experiment has been performed using PULCINELLA, a tool for propagating uncertainty based on the local computation technique of Shafer and Shenoy that can be specialized to each of our target uncertainty formalisms.
An Object‐Oriented Model of Building Procurement
Authors: Aouad G. F. , Kirkham J. A. , Child T. , Cooper G. S. , Ford S. , Brandon P. S. , Brown F. E. , Oxman R. E. , Young B.
Published: November 2008

Abstract: This paper reports on an object‐oriented building procurement model being developed at the University of Salford as part of an integrated database for the construction industry (ICON). The model is based on a top‐down approach using the information engineering method (IEM), object‐oriented method (OOM), and an object‐oriented CASE (computer‐aided software/system engineering) tool. This paper illustrates the way the information requirements of the building procurement process are identified and stored as graphic representations using activity, object, and process models. Ultimately, code is generated from these graphic representations, and a physical object‐oriented database (OODB) for the building procurement process is established.

The object‐oriented approach to information modeling will be described in detail with an illustration of how the use of a CASE tool can help the analysis phase. Various features of the object‐oriented paradigm will be described within the building procurement context. In addition, examples will be given to help the reader understand the recent developments in the object‐oriented field. Finally, the different modeling techniques used within the object‐oriented method such as object and event schemas will be presented and analyzed.
An Object‐Oriented Approach to Integrating Design Information
Authors: Ford S. , Aouad G. F. , Kirkham J. A. , Cooper G. S. , Brandon P. S. , Child T.
Published: November 2008

Abstract: This paper reports on the conceptual modeling of design information that is being undertaken to provide a framework into which information from different disciplines within the construction industry will fit. The information modeling, which is being undertaken using object‐oriented analysis and design techniques, will allow information to be viewed from different perspectives and different levels of abstraction depending on the requirements of the particular user. To permit sharing of the information, it is necessary to have fully integrated models. This paper describes the models that were produced and the way in which integration was achieved in order not to force any participant to compromise in terms of viewing information from an unfamiliar perspective.
A User‐Oriented Approach to Construction Simulation of Buildings
Authors: Oloufa Amr A.
Published: November 2008

Abstract: This paper describes a modeling approach for construction operations that uses a Form metaphor rather than the familiar network‐based icons. The objective is to facilitate the construction of simulation models by nonprogrammers. This paper discusses object orientation in modeling and how the technology may be used to help the user (a nonprogrammer) by facilitating the modeling process and to translate the object‐based model into a simulation program. The simulation model development is facilitated by the creation of company‐wide “construction operation libraries” limiting model development to the specification of resource interactions. An example demonstrating the application of this approach to a complex construction project and a comparison with CYCLONE are presented.
Adaptive Control for Robotic Rebar Bending
Authors: Dunston Phillip S. , Bernold Leonhard E.
Published: November 2008

Abstract: Computers are becoming essential tools for integrating design, planning, fabrication, and construction. Computer‐controlled construction equipment is poised to receive information from data generated in the design phase. The robotic execution of construction operations, however, depends on complex models for autonomous and intelligent control. This paper introduces a strategy for the robotic bending of rebar and presents the results of experimental work with an actual testing facility. Mechanical properties and behavior of rebar are examined to develop rules for control. Focus is placed on exploring the dynamics between the bender and steel bars. The concepts of impedance, admittance, and compliance of both the machine and the environment will be discussed in the context of control strategy development.
A Structural Damage Neural Network Monitoring System
Authors: Elkordy M. F. , Chang K. C. , Lee G. C.
Published: November 2008

Abstract: Traditional methods for structural monitoring and damage assessment have been implemented largely through visual inspection and on‐site tests. A system for automating this process should be able to record the various signatures of the structure to be monitored and issue a warning signal if there is a damage‐related change in those signatures. In this paper, a general system for structural damage monitoring is proposed based on observations of other researchers and the results obtained from a case study of a physical and analytical model of a five‐story steel frame. The proposed diagnostic system utilizes neural networks for identifying the damage associated with changes in structural signatures. The system is independent of the type of signatures used for monitoring. Two sets of neural networks were developed. The first set was trained with the results of a series of shaking‐table experiments, while the second set was trained with the output produced from a finite‐element model of the same test structure. The results show that the proposed system provides a suitable framework for automatic structural monitoring.
StructNet: A Neural Network for Structural System Selection
Authors: Messner John I. , Sanvido Victor E. , Kumara Soundar R. T.
Published: November 2008

Abstract: This paper describes StructNet, a computer application developed to select the most effective structural member materials given a building project's attributes. The system analyzes 15 parameters of a building project (e.g., available site space, budget, height) and determines the most appropriate structural system for the beam, column, and slab structural members. This paper first describes the process for selecting a structural system for a building. It was very important to understand this process before determining the best type and structure for the computer application. Then a comparison between a neural network approach and a rule‐based expert‐system approach for this application is presented. A discussion of the reasons for selecting a neural network approach is given. The StructNet application is described in detail, including the testing of the network. Along with the testing of the network is a discussion of how varying the learning rate and error limit affect the performance of the neural network application. The testing of the network shows that the program can reasonably select the same structural system types as the expert used to collect the training project data. Since the system will be used only as a preliminary tool to limit the number of possible structural systems for a project, the accuracy of the system is acceptable. However, additional experimentation needs to be conducted to determine the accuracy and practical use of this application. The final sections of the paper discuss the lack of adequate testing procedures for neural networks used in applications for unstructured or ill‐defined decision making. The use of these types of networks and their relevance to the civil engineering computer field are also discussed.
Developing Practical Neural Network Applications Using Back‐Propagation
Authors: Hegazy T. , Fazio P. , Moselhi O.
Published: November 2008

Abstract:In the past few years, neural networks have emerged as a problem‐solving technique with capabilities suited to many civil engineering problems. Among the various neural network paradigms available, back‐propagation is by far the most utilized for its relatively simple mathematical proofs and good generalization capabilities. Despite its capabilities, back‐propagation suffers from several problems that hinder the development of practical neural network applications. These include slow training, ill‐defined knowledge representation and problem structuring, and nonguided design of an optimal network configuration for adequate generalization. This paper represents an effort to guide the process of developing practical neural network applications using back‐propagation. The paper starts with a brief description of back‐propagation mathematics. Some of the heuristics and techniques used to overcome back‐propagation problems, particularly lack of generalization, are identified and outlined, along with areas of potential improvements to the paradigm. An application development methodology is proposed utilizing the identified heuristics and techniques. The methodology provides a structured framework for designing and implementing practical neural network applications with less effort.
Visual Construction Operation Simulation: The DISCO Approach
Authors: Huang Rong‐Yau , Halpin Daniel W.
Published: November 2008

Abstract: Despite the great deal of attention given to project‐level management tools (e.g., CPM, PERT, etc.) in recent years, the analysis of construction operations (processes) using computer simulation techniques has generated considerable attention commencing with the introduction of the CYCLONE methodology. Recently, the application of visual simulation (VS) techniques to assist in the planning and analysis of construction operations has directed further attention at the need to better understand the interaction of resources at the process level. Visual simulation takes advantage of advanced modern computer graphics techniques and facilitates the development and application of simulation experiments. Benefits of applying VS have been reported in several publications. Nevertheless, the effort required to design and construct an “appropriate” VS display for the system to be analyzed is usually time and data demanding. The magnitude of model definition is often increased due to certain characteristics of construction operations, such as their complexity and the distribution of work over large areas. An alternative approach, DISCO (Dynamic Interface Simulation for Construction Operations), which employs a schematic modeling format demonstrating the system dynamics on the computer screen during simulation run, is presented in this paper.
A Knowledge‐Based Design Tool to Assist in Preliminary Seismic Design
Authors: Berrais A. , Watson A. S.
Published: November 2008

Abstract: Many structural engineers only rarely need to be concerned with seismic design. It is a relatively difficult process that can involve advanced analytical techniques and concepts such as ductility which are not normally encountered except in this context. A prototype Seismic Design Assistant (SDA) has been developed specifically to assist, advise, and guide design engineers engaged in the preliminary seismic design of reinforced concrete buildings (with coupled shear walls). Available seismic design methods are reviewed, and a particular method is outlined that incorporates sophisticated analytical procedures to enable ductility requirements to be satisfied. This method provides the basis of the knowledge base employed within the SDA. The prototype design tool has been implemented on a Sun workstation using Quintec‐Prolog, Quintec‐Flex, and Fortran 77. Details are presented of the architecture of the SDA, of the knowledge representation that has been employed, and of the integration of traditional procedural software within a knowledge‐based approach.
Neural Network Approaches to Aid Simple Truss Design Problems
Authors: Kang Hyeong‐Taek , Yoon C. John
Published: November 2008

Abstract:Diverse problems in engineering may be solved accurately with computers. In structural engineering, many solution techniques exist. Over the past few years, neural networks have evolved as a new computing paradigm, and many engineering applications have been studied. This paper describes configuring and training of a neural network for a truss design application and explores the possible roles for neural networks in structural design problems. The specific problem considered is a simple truss design where, given a geometry and a loading, economical cross‐sectional areas of all the members are to be selected. For this problem, a two‐layer neural network is trained using the back‐propagation algorithm with patterns representing optimal designs for diverse loading conditions. The performance of the trained neural network is evaluated with a sample problem.