bluuebunny/crossref_metadata_2025 huggingface dataset:
Demand under product differentiation: an empirical analysis of the US wine market*
Authors: Davis Timothy R. , Ahmadi‐Esfahani Fredoun Z. , Iranzo Susana
Published: November 2008

Oversupply has led to a number of perplexities for the Australian wine industry in recent times. When disaggregated from the industry level, however, the problem can be better described as a range of attribute‐specific disequilibria. To date, the solutions to this problem have predominantly revolved around supply‐side policies of reducing output through crop thinning or vine pulling. By contrast, this paper focuses on the demand side and argues that the disequilibria may be reduced by gaining a better understanding of the demand for Australian wine. A discrete choice model of product differentiation is used to estimate the demand for wine in Australia's second largest export market, the United States. Implications of the analysis are explored.
Classical decision rules and adaptation to climate change*
Authors: Harry Clarke
Published: November 2008

One approach to rationalising policies for addressing potentially catastrophic climate change when such policies may prove unnecessary is to suppose the policies provide a form of social insurance even in the presence of pure uncertainty. Then, provided the policies are effective, such insurance can be justified as a precautionary or minimax response. Even if the policies are potentially ineffective however, intervention can be justified as an attempt to minimise the regret experienced by future generations. This reasoning extends to justify ‘all weather’ policies provided such policies always reduce policy costs. If, however, policy decisions provide ‘all weather’ benefits in only certain states of the world, this rationale breaks down. Minimising regret can establish a case for ‘mixed’ policy responses provided adopting a policy mix precludes the chance that intervention will fail altogether. Precautionary policies and policies which minimise regret are computed for a simple, dynamic, adaptive climate change planning problem and sufficient conditions for policy maker pessimism provided.
Exchange rates and foreign direct investment: theoretical models and empirical evidence*
Authors: Phillips Shauna , Ahmadi‐Esfahani Fredoun Z.
Published: November 2008

Over the past decades, growth in foreign direct investment (FDI) has stimulated significant attempts at developing theories that explain this trend. One line of this research explores the relationship between exchange rates and FDI. There is no consensus about the nature of this relationship in either the theoretical or empirical work. In this article, we critically appraise this body of work, and find the theoretical studies to be making ground in exploring the complexities of FDI, but the empirical evidence to be constrained by data problems.
Wheat breeding, productivity and slow variety change: evidence from the Punjab of India after the Green Revolution*
Authors: Smale Melinda , Singh Joginder , Di Falco Salvatore , Zambrano Patricia
Published: November 2008

Variety change and genetic diversity are important means of combating crop losses from pests and diseases in modern agricultural systems. Since the Green Revolution, genetic diversity among wheat varieties released in India has increased but variety change on farms continues to be slow. In this article, we define and summarise indices of variety change and genetic diversity for the wheat varieties released and grown in Indian Punjab during the post‐Green Revolution period. We evaluate the effect of each index on technical efficiency with a Cobb‐Douglas yield model after testing for exogeneity. Findings support the hypothesis that slow variety change has offset the positive productivity effects of diversifying the genetic base in wheat breeding during the post‐Green Revolution period. Policies that speed the rate of variety change and contribute to a more equitable spatial distribution of modern varieties could support wheat productivity in the Punjab of India, reinforcing plant breeding successes.
On the economics of agricultural production*
Authors: Chavas Jean‐Paul
Published: November 2008

Agriculture is in the business of using ecosystem services to produce food. Examining how agro‐ecosystems function provides useful insights into the economics of agriculture. Of special interest are the presence and nature of scale effects, complementarity effects and convexity effects in ecosystem functioning. Implications for agricultural productivity and the economics of agriculture are evaluated. At the farm level, this helps to better understand the current trend toward greater specialisation. Current challenges for agricultural contracts, markets and policy are explored.
Applications of Variance Reduction Techniques in Construction Simulation
Authors: ABOURIZK SIMAAN M. , GONZALEZ‐QUEVEDO ANTONIO A. , HALPIN DANIEL W.
Published: November 2008

A technique that can be used to reduce the variance of a stochastic simulation output is reviewed. This technique allows the user to reduce the number of simulation runs without sacrificing the level of confidence of the output. This technique entails inducing an artificial correlation between the various runs. The specific technique presented uses common random numbers (CRN). The use of CRN can be applied to the comparison of alternative systems. Using CRN when comparing alternatives insures that the comparison is properly conducted. A sample simulation is presented in order to illustrate these two applications of CRN.
Computer Aided Configuration of Pipe Systems in Buildings
Authors: Hsu Liyen , Mohan Satish
Published: November 2008

Abstract: The combined configuration of the various pipe systems in hospitals, laboratories and plants can be very complicated. They are designed by different professionals and presented on separate drawings, generally by single lines. Location of Pipe systems has to satisfy constraints on clear distances between different kinds of pipes, negative spaces for installation and maintenance, and, in some cases, minimum and maximum slopes. The single lines presentations may pose unexpected interference problems during construction, impairing the quality, cost and schedule of the project. To cope with the difficulty, allowing more flexible space is usually considered, but this approach neglects the economic factor, and interference problems may still occur.

This paper presents a methodology for a three‐dimensional (3‐D) configuration of pipe systems which satisfies given constraints and which avoids interference problems during construction. The data on the building and the initial single‐line piping layout can be fed into the process either directly from the blueprints or by using AutoCAD™. The process presented in this paper then calculates the existence of any interference problems, using analytic geometry and computer graphics. If any interferences are found, a computer simulation process incrementally modifies the initial layout until all of the constraints are satisfied. The modified data are then transferred to AutoCAD™ which configures a 3‐D presentation of the pipe system. An example application, using the proposed methodology, is presented in this paper.

In addition to time and cost savings during construction, the work presented in this paper has the potential of: reducing storey heights, reducing underground excavations, ensuring reasonable space for maintenance personnel, better scheduling of piping activities, and the economic benefit of considering the possibilities of the penetration of pipes through structural beams closed to the nautral lines.
A Computer simulatin Interface
Authors: Riggs Leland S. , Han Choong‐Hee
Published: November 2008

Abstract: Computer simulation can be a powerful analytical tool. Often, however, practitioners who know most about the problem domain may have limited knowledge of the simulation software. Recent research has concentrated on bridging the gap between the practitioner and the simulatin software by designing interfaces to make computer simulation more accessible for the infrequent or inexperienced user. Emerging artificial intelligence techniques sch as knowledge‐based expert systems offer some promise for an interface. This paper describes a prototype interface which converts information on a process to be simulated into computer input for an existing computer simulation system. The elements of the interface include a domain knowledge processor using a small knowledge‐based system to establish types of activities and resources based on minimal user input, a model logic builder to identify moves between activities and to establish network logic, and a computer code translator to convert the network into CYCLONE computer source code. Recommendations for future research are included.
Modeling Air‐Void Systems in Hydrated Cement Paste
Authors: Snyder K. A. , Hover K. C. , Natesaiyer K. , Simon M. J.
Published: November 2008

Abstract: Multiple techniques for modeling the air‐void system in hydrated cement paste are proposed based on uniformly dispersed spheres following a given diameter distribution. The model is developed for the analysis of air voids intersecting a random plane passed through the volume. the model is then modified for the calculation of the protected paste volume, which is the fraction of the volume contained within a given distribution of overlapping spheres. Applications of this model to other fields of study are suggested.
Developments in Multiprocessor Scheduling
Authors: Schmidt Richard J. , Horning Dannis
Published: November 2008

Abstract: Effecient use of multiprocessor computers requires some consideration for formal processor shcheguling. The evolution of formal sheduling, as if relates to multiprocessor computing, is reviewd. The focus is placed on techniques which which are appropriate for numerically intensive computions, such as structural mechanics applications. Both static and dynamic scheduling tech techniques are reviewed and compared. As machine‐indepennde development environments mature, it is likely that the additional computational efficiencies available with formal scheduling will be exploited.
Computer‐Aided Design Using Object‐Oriented Programming Paradigm and Blackboard Architecture
Authors: Yu George , Adeli Hojjat
Published: November 2008

Abstract: Object‐oriented programming characteristics of abstraction, inheritance, and encapsulation of data and operations support three desirable features in the development of complicated engineering software systems: modularity, reusability, and ease of maintenance. This paper presents computer‐aided design (CAD) of structures using the object‐oriented programming paradigm and a blackboard architecture for management of input/output data as well as intermediate data created during a consultation with the CAD system.
Partial Hybrid Stress Element for Mindlin Laminated Plates Theory
Authors: Tseng Yi‐Ping , Wu Tzu‐Chiang
Published: November 2008

Abstract: The partial hybrid stress method is applied to the Mindlin plate theory for orthotropic composite plates. The displacement formulation is adopted in the flexurel part and the hybrid formulation in the transverse shear part. Since the interface traction discontinuity is overcome, the present element performs much better than the displacement‐based method. Although only the stress parameters in transverse shear part are required, the accuracy approaches that of the conventional hybrid method, The governing equations of plate are also derived from the modified Hellinger‐Reissner variational principle.
Three‐Dimensional Nonlinear Dynamic Analysis of Complex High‐Rise Building Structures
Authors: Saitoh Yasuo , Horii Masahiro , Teramoto Takayuki
Published: November 2008

Abstract: Recently, designs of high‐rise buildings have become more complex. Various types of buildings result, such as buildings with a semicircular plan, and buildings in which the upper floors are larger than the lower floors.

The authors have developed a three‐dimensional (3‐D) dynamic analysis system, ‘Super DYNAMICS’, which considers the nonlinear behavior of each structural member in order to analyze the structural behavior of such complex steel buildings under severe earthquakes.

This system is mainly operated on a supercomputer because of the large number of calculations required for the member level dynamic analysis.

This paper first describes the general concepts of the system and the 3‐D dynamic response analysis methods, based on the nonlinear behavior of each member under axial force and biaxial bending moments, and then examines and demonstrates the precision of the yield surface of steel members created by multispring models, and the ability of the system to trace the behavior of members and frames after yielding. It shows, in addition, actual examples of a static and a dynamic analysis by three‐direction ground motion applied to a 19‐story steel‐framed office building.
A Model for Simulating Human Behavior During Emergency Evacuation Based on Classificatory Reasoning and Certainty Value Handling
Authors: Ebihara Manabu , Ohtsuki Akira , Iwaki Hideaki
Published: November 2008

Abstract: A computational model that simulates human behavior under fire and earthquake emergencies has been developed, using the object‐oriented language Smalltalk‐80. The present model consists of a space model, a scenario model and a human model. In the space model, the spaces in which people can move are represented by nodes connected by links. The nodes incorporate exit, guidelight and staircase facility data. Also, they feature environmental data including the darkness of the lighting system and the density of smoke. Seismic hazards such as a power failure and occurrence and expansion of fire and smoke are represented in the scenario model. This kind of information is then furnished from the scenario model to the space model as obstruction information. In the human model, a suitable knowledge‐based model has been constructed for representing evacuation behavior: people choose the evacuation path based on the production rules with certainty values, and move to the target exit along the evacuation links. The present simulation model is experimentally applied to examine the behavior which masses of people take in an underground structure under an emergency condition caused by an earthquake, and the results obtained confirm that the model is able to simulate correctly the principal human behavior enacted in an emergency evacuation.
Automous Construciton Robots
Authors: Krom Ronald P. , Tolman Frits P.
Published: November 2008

Abstract: This paper describes some of the results of the authors' research on autonomous construction robotics. The objective of our research is to find out whether autonomous construction robots are feasible or not, and how autonomous construction robotics might be achieved. The paper presents the information technologies required and an initial (simulated) example of an autonomous tiling robot.
Critical Analysis of Strucutres by Qualitative Reasoning
Authors: Kawamura H. , Tani A. , Naknao H. , Yamada M.
Published: November 2008

Abstract: In the critical analysis of fracture and unstable behavior of structures, the uniqueness of solution is no longer assured. Such critical states can be analyzed by recognizing their deformation‐ and forcespaces which are not considered in the usual numerical matrix analysis. The purpose of this paper is to show the applicability of qualitative reasoning, which has been recently developed as a method of artificial intelligence, to the above‐mentioned critical analysis of structures. To recognize multi‐dimensional spaces, qualitative reasoning is performed using reasoning rules described with production rules ‘if ∼ then ∼’ and qualitative values +, 0 and −. As a case study, qualitative reasoning is applied to some kind of truss units subjected to combined axial force, bending moment and shear force. Its mechanical behavior can be illustrated in the three‐dimensional deformation‐ and force‐spaces. Here, the LISP language, which is suitable for processing lists, is employed.
Simulation of Demolition of Reinforeced Concrete Buildings by Controlled Explosion
Authors: Utagawa Noriyuki , Kondo Ippei , Yoshida Naoto , Itho Mamoru , Yoshida Nozomu
Published: November 2008

Abstract: A system for simulating the behavior of a reinforced concrete building being demolished by controlled explosion is developed. The purpose for developing the system is to examine the effects of blast location, blast size, blast sequence, delay time of blasts and other factors on a planning of blast demolition. It consists of a numerical analysis part to simulate the blast demolition of a space‐framed structure and a visualizing system to show the dynamic behavior obtained from the numerical analysis. The numerical analysis is based on the distinct element method, which is improved for consideration of the bending behavior of beams and columns. The elastoplastic behavior of the structural members up to the collapse are modeled in the analysis. The numerical data display system ‘AVS’ is employed, in addition to the computer code developed by the authors, to make the visualization system for three‐dimensional dynamic problems. In this report the method of numerical analysis, the visualizing system, and a comparison between the experiment and analysis are presented.
Debugging Finite Element Programs Input Data with Machine Learning
Authors: Yeh Yi‐Cherng , Kuo Yau‐Hwaug , Hsu Deh‐Shiu
Published: November 2008

Abstract: Debugging of the input data of a structural analysis program is a troublesome task which is heavily dependent on empirical knowledge. The paper describes an effort that applies machine learning to build an expert system for debugging faults in structural analysis program input data. ID3 decision tree induction algorithm is employed to build the automatic learning mechanism. This method Oflkrs an attractive potential for knowledge acquisition in the civil engineering domain in which expertise plays a dominant role. This paper is novel in at least three aspects: (1) machine learning is employed to build expert systems automatically; (2) a novel impurity function is proposed for splitting the decision tree; (3) a formulated comparison is proposed for evaluating learning results.
A Knowledge‐based Expert System for Natural Disaster Prediction Using Geomorphological and Geological Information
Authors: Kashiyama Kazuo , Ohashi Masakazu , Suzuki Takasuke
Published: November 2008

Abstract: A knowledge‐based expert system for the prediction of natural disaster potential is presented in this paper. The key feature of this system is that it predicts the natural disaster potential using the information of geomorphological and geological features of the examined site. The input data are obtained from topographic maps, geological maps, aerial photographs and other sources available. This system is developed for use with the personal computer and users can operate this system interactively. The results obtained are compared with actual disasters. These comparative studies indicate that the present system provides a useful tool for the prediction of natural disaster potential at the arbitrary sites.
Development and Utilization of Computer Systems for Building Maintenance and Operation
Authors: Shimodaira Hisashi
Published: November 2008

Abstract: This paper describes the outline of major systems for building maintenance and operation in the NTT Building Engineering Department; CAD, commonuse database, CAFM database, and the building diagnosis and maintenance planning system. By means of the building diagnosis and maintenance planning system, we have achieved highly reduced labor and work times. However, because the utilization of computers in this field has only just begun and is behind other fields, we have much room for improvement. We have considered the current issues and presented the following measures for solving them: (i) develop more application programs; (ii) complementarily use alphanumeric and graphic data; (iii) automate tasks by using standardized knowledge; (iv) automate more tasks by using a building product model instead of drawings; and (v) develop a lvelong database by using a building product model. In conclusion, we need to develop an integrated system based on a combination of a building product model and various databases to automate tasks and achieve smooth communication of information.
A Group Technology Based Classification and Coding System for Reinforced Concrete Structures
Authors: Sacchetti Joseph F. , Sanvido Victor E. , Kumara Soundar R. T.
Published: November 2008

Abstract: This paper presents an application of Group Technology, a technique used in the manifacturing industry, to code and classifv the components of a reinforced concrete building structure. Given this classification scheme, a designer can search the database for design components that are similar and standardize them, retrieve previous similar design solutions and minimize the constructed cost of the structure. This paper reviews current construction classification schemes, provides an overview of group technology, and develops a classification and coding scheme for mid rise reinforced concrete building structural components. The scheme is implemented on software and a case study illustrates the utility of such a system to the industry.
Information‐Oreinted Construction System for Reclamation Work
Authors: Matsumoto Takashi , Satoh Makoto , Hashimoto Akio
Published: November 2008

Abstract: An information‐oriented construction system is developed for the management of construction work on the airport island for Kansai International Airport. In this system, virtual grids are placed in the objective operating area. Work result data, which include coordinates, azimuth angle, earth volume, etc., are converted into ‘the deposition earth volume’ per grid. The consolidation calculation and the earth volume management are also performed. The system comprises the following five subsystems: work result management, deposition configuration management, reclamation configuration management, measurement/survey process and earth volume management. The system also utilizes the computer network connected between the personal computers installed at the site and a large‐sized computer at the headquarters ofice to process heavy load calculations.
Log‐Linear Models in Expert Systems
Authors: Castillo E. , Mora E. , Alvarez E.
Published: November 2008

Abstract: The paper describes how log‐linear models can be used to deal with uncertainty in expert systems, avoiding the common problems of many probability‐based expert systems. After a general introduction to log‐linear models, including hierarchical models, maximum likelihood estimation for poissonian and multinomial sampling is described and parametric and structural learning methods are illustrated by simple examples. Finally, a traffic engineering example is given.
Collaborative Knowledge‐integration Systems: A Tool for AEC Design, Management, and Coordination
Authors: El‐Bibany Hossam , Paulson Boyd C.
Published: November 2008

Abstract: This paper describes a formal, unified methodology for design and management in order to facilitate AEC collaboration. Issues related to the AEC industry pave the way for a description of the collaborative AEC environment and its requirements for supporting information systems. Next, constraint management is described as the core of the unified methodology. A system architecture is briefly presented with an illustrative example. A discussion of integration philosophies and a comparison with parallel research in the area of system integration in the civil engineering domain conclude the paper.
Effect of Representation on the Performance of Neural Networks in Structural Engineering Applications
Authors: Gunaratnam D. J. , Gero J. S.
Published: November 2008

Abstract: The pattern‐mapping, pattern‐classification, and optimization capabilities of neural networks have been used to solve a number of structural analysis and design problems. Most applications exploit the pattern‐mapping capability and are based on the back‐propagation paradigm for neural networks. There are a number of factors that influence the performance of these networks. This paper initially discusses these factors and the domain‐dependent and ‐independent techniques presently available for improving performance. The paper then considers the effect of representation, selected for the input/output pattern pairs, on the performance of these networks and demonstrates that representations based on dimensionless terms, derived from dimensional analysis, lead to improved performance. It is shown that dimensional analysis provides a representational framework, with reduced dimensionality and embedded domain knowledge, within which effective learning can take place and that this representational change can be used to enhance the domain‐independent and ‐dependent techniques presently available for improving performance of these networks.
Machine Learning User Preferences for Structural Design
Authors: Thurston Deborah L. , Sun Ruofei
Published: November 2008

Abstract: The design process often proceeds through iterative stages of design configuration, analysis, evaluation, and redesign with the ultimate goal of optimization. Numerical methods for structural design optimization of only one attribute such as weight, strength, or cost are well known. However, these methods do not reflect the fact that designs are evaluated by the user in terms of their performance in several attributes. It has been extremely difficult to incorporate multiple attributes into design optimization algorithms because the acceptable tradeoffs between these attributes vary significantly between users.

This paper presents a new method for learning user‐specific preferences and integrating them into the design evaluation, analysis, and optimization process in a meaningful way. The approach is a synthesis of formal decision theoretic methods with conventional design analysis techniques. The overall design objective is optimization of multiattribute utility from the viewpoint of the user.

A user‐interactive computer‐aided Multiattribute Structural Design Evaluation and Optimization System (MSDEOS) is presented. It enables machine learning of the user's willingness to make tradeoffs between performance attributes. With this system, it is feasible to integrate site‐specific consideration of multiple attributes directly into computer aids for structural design optimization. Two examples are presented: seismic design, where tradeoffs are made between cost and damage index, and design of a three‐story steel frame structure, where attributes are cost and drift index. The system learns the preferences of different users and reflects those preferences through the identification of a different optimal solution for each user.
Graphic Interactive Input System for High‐Rise Building Structures in CAD
Authors: Chan H. C. , Cheung Y. K. , Shang S. P.
Published: November 2008

Abstract: A graphic interactive input system developed for use in computer‐aided design (CAD) of high‐rise building structures is presented. In this system, the primitive information is input to computer through graphic display. The input object appears on the screen as an image and is directly visible. With the interactive operation, the designer can carry out the input rapidly and efficiently by moving the cursor on the screen, and the graph that represents the information about the structure can be modified easily.

Using multicolor graphics, animated cartoons, multiple windows, and multiple‐level menus, autogeneration and autonumbering of the members are performed, and the geometric and loading information can be input conveniently.

In this paper, some basic conceptions and algorithms of graphic input and screen data collection are described.
An Educational Mobile Robot
Authors: Scott Wesley , Berrios Ivan , Boles Walter
Published: November 2008

Abstract:The need for construction automation instruction in the civil engineering curriculum is reviewed. A mobile robot suitable for use as a laboratory teaching device was developed. Obstacle sensing and avoidance were performed using ultrasonic sensors and a fuzzy logic controller. Experiences of the students who developed the robot are discussed. It is concluded that a class project provides valuable hands‐on experience that reinforces the students' understanding of theory. A background on microcontrollers is provided.
Improving Pareto Optimal Designs Using Genetic Algorithms
Authors: Gero John S. , Louis Sushil J.
Published: November 2008

Abstract: Pareto optimal designs are the best designs that can be produced for a given problem formulation for a given set of criteria when the criteria are not combined in any way. If the goal is to improve the performance in those criteria, then it is possible to manipulate the problem formulation to achieve an improvement. The approach adopted is to encode the formulation in a genetic algorithm and to allow the formulation to evolve in the direction of improving Pareto optimal designs. A set of rules (in the form of a shape grammar), the execution of which produces a design, is encoded as the genes in a genetic algorithm. However, the rule set is allowed to evolve, not just the order of execution of rules. We present an example demonstrating both the approach and its utility in improving Pareto optimal designs.
Multiobjective Optimal Design of Welded Box Beams
Authors: Farkas J. , Jármai K.
Published: November 2008

Abstract: The cost, mass, and maximal deflection are selected as objective functions. In the cost function, the material and fabrication costs are included. The variables are the four plate dimensions of a symmetrical welded box beam. The design constraints relate to the bending stress and local buckling of plate elements. The shear‐stress constraint and size limitations are also considered. The optimal beam dimensions are computed using several single‐ and multiobjective optimization methods. The results of an illustrative numerical example show the effect of yield stress of steel and that of the weighting coefficients.
Multiobjective Design of Laminated Cylindrical Shells for Maximum Pressure and Buckling Load
Authors: Adali S. , Richter A. , Verijenko V. E.
Published: November 2008

Abstract: Multiobjective design of a laminated cylindrical shell is obtained with the objectives defined as the maximization of axial load and external and internal pressures subject to a strength constraint. The failure under axial load and external pressure may occur by buckling. The ply angle is taken as the design variable. The weighted global criterion method is employed to solve the vector‐optimization problem, which involves minimization of the distance to ideal solution vector in L2 metric. A symmetrically laminated and balanced shell is considered as an example. Pareto optimal solutions are given for two‐ and three‐objective design problems, and numerical results are presented in the form of tradeoff curves and surfaces. The effects of problem parameters are investigated, and the results are given for various weighting factors and shape parameters.
Compound Scaling Algorithm for Multiobjective Functions
Authors: Grandhi Ramana V. , Bharatram Geetha
Published: November 2008

Abstract: In this paper the possibility of using compound scaling algorithm for solving the multiobjective optimization problem is demonstrated. The algorithm treats the objective functions similar to behavior constraints during the intermediate iterations of optimization. The algorithm generates a partial Pareto curve while solving the problem. Truss and plate structures are used as example problems.
Autonomous Navigation of Heavy Construction Equipment
Authors: III Carl D. Crane , II David G. Armstrong , Rankin Arturo L.
Published: November 2008

Abstract: A John Deere model 690 excavator, mounted on a Standard Manufacturing Company wheeled undercarriage, has been automated for the purpose of autonomously uncovering and removing unexploded buried ordnance. This paper describes the development effort, with emphasis placed on the autonomous navigation of the excavator system. Accurate navigation is required in order to properly position the excavator system so that it can uncover and remove the target buried munition. Autonomous navigation is accomplished by use of an A* search algorithm for path planning, an inertial navigation system (INS) integrated with a global positioning system (GPS) for vehicle positioning, and proportional control for path‐following. Data gathered from eight navigation test runs show that the excavator, on average, can navigate to within 0.67 m of a goal position and to within 0.021 rad of a goal orientation.
RCCS: Rebar CAD/CAM System
Authors: Navon Ronie , Rubinovitz Yacov , Coffler Mendi
Published: November 2008

Abstract: A CAD/CAM system that automates the design and manufacturing of rebars is described. The CAD‐based design module of the system permits a semiautomated design alongside the conventional one. The uniqueness of the system resides in its ability to extract automatically the data needed for manufacturing from the graphic design database, process these data, and transfer them to the rebar‐manufacturing machine. Thus all the manual data manipulation stages of traditional rebar design and production (detailing, documentation, data extraction, etc.) are avoided. In many cases the multistage manual data manipulation is a source of errors and is moreover labor‐intensive. Consequently, the CAD/CAM system described here leads to cost reduction together with increased quality. This paper describes the principles underlying the development of the system and the system's structure, which is based on a design module, a data extraction module, and a data processing and transfer module.
Construction Robotics and Automation Research at Taisei
Authors: Fujinami Yasuo , Mitsuoka Hiroshi , Suzuki Aketo , Kimura Takahiko
Published: November 2008

Abstract: The aim of this paper is to focus on special items of research and development (R&D) areas in which Taisei Corporation is active, to discuss some of the issues involved in automation research and the importance of information management in automation and robotics, and to delve into the possible future of construction robotics and automation. In the first section we break automation and robotics down into four levels: simple mechanization, robots, mechanized construction systems, and fully automated construction. Each is discussed separately and, with the exception of fully automated construction, examples of R&D in each category are described. This gives the reader a glimpse of what a general contractor in Japan is currently doing. In the second section we describe information‐integrated construction (IIC), which can be defined as the use of computer technology to collect, store, manipulate, enhance, and display construction information and expertise as a way to streamline the construction process.
Application of Genetic Algorithm to Aesthetic Design of Bridge Structures
Authors: Furuta Hitoshi , Maeda Kenji , Watanabe Eiichi
Published: November 2008

Abstract: In this paper, paying attention to the steps of making a master plan and evaluating configurations and views for aesthetic design of bridge structures, an attempt is made to develop a decision‐making supporting system. The present system is based on a genetic algorithm and computer graphics. Genetic algorithms are applicable to produce many design alternatives, whereas computer graphics are useful to prepare their view simulations. In order to evaluate the alternatives, the concept of a psychovector is used to quantify the aesthetic factors of bridge structures. A numerical example of choosing the type and shape of an arched bridge is presented to demonstrate the applicability of the system developed here.
Hybrid Control of Structures Using Fuzzy Logic
Authors: Subramaniam Ravi S. , Reinhorn Andrei M. , Riley Michael A. , Nagarajaiah Satish
Published: November 2008

Abstract: This investigation examined the application of control algorithms based on fuzzy logic to a class of hybrid structural control systems. The investigation included both analytical and experimental verification of the fuzzy control algorithm. The objective of the hybrid system under investigation is to obtain an ideal sliding system with perfect base isolation. As the hybrid system approaches the state of ideal isolation, the effects of imperfections, signal noise, uncertainties, modeling errors, and compensation errors start to play a dominant role in the control performance. Fuzzy logic (or fuzzy set theory) provides a simple framework to capture the effects of nonlinearities and uncertainties in a real problem without an explicit model of the plant or controller.

The applicability of this approach was first investigated analytically and then verified using a benchmark experimental model consisting of a 1:4 scale sliding‐base isolated system controlled at its base by a servohydraulic actuator with a digital computer to provide the control signal. The fuzzy controller used feedback from either the acceleration of the moving foundation or the force at the interface to produce control forces in a series of shaking‐table tests. The results from this study show the feasibility of the implementation of fuzzy logic to highly nonlinear problems.
Calibration of Structural Models Using Fuzzy Mathematics
Authors: Wadia‐Fascetti Sara , Smith H. Allison
Published: November 2008

Abstract: A calibration model is presented that quantifies the uncertainties associated with structural free vibration analysis. System identification objectives and fuzzy set mathematics are integrated to formulate an analysis methodology that enables the a priori prediction of the most probable sources of modeling error. By first developing fundamental fuzzy sets defining uncertainty in structural parameters such as stiffness and design loading, higher‐level fuzzy sets governing dynamic behavior are obtained using the vertex method. Uncertainty in the dynamic parameters (natural frequency, frequency ratio, and structural response) are each represented using fuzzy mathematics, where membership functions are determined by performing multiple dynamic analyses involving confidence levels of model assumptions. A numerical example is presented to demonstrate the calibration model for a 13‐story steel structure located in San Jose, California. Results show that the calibration model is capable of quantifying uncertainties in structural properties and behavior without requiring the measured data necessary for conventional system identification procedures.
System for Scheduling Highway Construction Projects
Authors: Arditi D. , Bentotage S. N.
Published: November 2008

Abstract: The type and number of activities involved in highway construction, the precedence relationships between them, and their estimated durations depend on a multitude of factors. When considered under different conditions, the number of options available in this regard is found to be very high. Computerized support for the generation of construction schedules is currently limited to creating networks for manually defined and sequenced activities. This paper describes a system called ROAD PLANNER that generates activity networks and computes estimated activity durations. Eleven main activities that are present in the majority of highway construction projects have been defined at the root level. Based on information provided by the user, the system generates the precedence relationships between these main activities. It then generates subactivities and estimates their duration by interacting with 14 rule bases. Lead and lag times between activities are also calculated by the system. The rule bases contain expert information on various construction methods and different technologies. They interface with 27 databases that contain productivity information regarding a multitude of construction equipment.
A Knowledge‐Based Expert System for Innovative Transportation Financing Techniques
Authors: Faghri Ardeshir , Hoel Lester A. , Joshua Sarath C.
Published: November 2008

Abstract: This paper discusses the development of a medium‐sized knowledge‐based expert system for selection of appropriate innovative financing technique(s) for transportation projects by several state and local governments. The steps involved in the development of the expert system, namely, problem identification, conceptualization, knowledge acquisition, knowledge representation, implementation, and testing and evaluation, are discussed. The process of organizing the available knowledge of innovative financing techniques, as well as the process leading to the selection of one or more of them for a particular project, is encoded in the knowledge base of the expert system developed for the purpose. The working system was tested and validated by comparing the output of the system against the recommendations made by transportation professionals in counties and cities in various states. The tests indicate favorable results for the system. The operational system can be used as a decision support system as well as a teaching tool for transportation engineers, planners, private developers, and government officials.
Interactive Evolution: A Prototyping Framework for Engineering
Authors: Graf Jeanine
Published: November 2008

Abstract:Interactive evolution is a powerful method combining the strength of simulated evolution with the judgment of a human user. This technique can serve as a useful tool for achieving flexibility and complexity in architectural design and civil engineering applications. Operators such as recombination, mutation, and expansion are used to evolve variations and improvements on an existing set of models with only a moderate amount of user input and detailed knowledge. One of the main advantages of this method is that it has the potential to optimize a preferred model and to produce many variations from a limited dataset of models. In addition, since it generates constrained variants reflecting the user's preferences, it provides both the architect and engineer with a creative design tool. I present the IDEA system, an interactive X‐window tool, for this purpose. This method is exemplified within an architectural design situation through the design of houses, bridges, and urban planning.
Identification of Fuzzy Relations with Multiple Hyperplanes by Genetic Algorithm in Structural Design
Authors: Ohmachi Yasutaka , Kawamura Hiroshi , Tani Akinori , Yoneda Hajime
Published: November 2008

Abstract: This paper proposes a method for formulation and quantification of human subjective evaluations and uncertain numerical values by using multiple hyperplanes based on the results of questionnaires distributed to structural designers that are composed of four questions about structural design and planning, i.e., (Q1) structural damage, (Q2) structural economy in a macroscopic sense, (Q3) structural safety, and (Q4) opening patterns in facade. In this paper, some hyperplanes in multidimensional spaces are used as a method to identify fuzzy relations (states) in intelligent fuzzy networks for seismic structural planning. A genetic algorithm is employed as a search method for optimal formulations and is proved to be very effective as a method for such an identification.
Fractal Two‐Level Finite‐Element Method for Two‐Dimensional Cracks
Authors: Leung A. Y. T. , Su R. K. L.
Published: November 2008

Abstract: Fractal two‐level finite‐element method has been extended to mode II crack problems. In order to encourage the use of this versatile tool on crack problems, some user guidelines for evaluating the stress intensity factor and for improving the convergence of stress intensity factors are suggested for structural engineers. The study is focused on (1) the effect of the numerical integration scheme on the convergency of stress intensity factors, (2) the configuration of fractal meshes, and (3) the influence of the aspect ratio of the fractal mesh on the accuracy of stress intensity factors. Both mode I and mode II two‐dimensional crack problems are discussed. Examples for both the lagrangian and the serendipity types of elements are used to demonstrate the numerical efficiency and accuracy of the present method. In summary, it is not difficult to achieve accuracy within 3% error on stress intensity factors with a personal computer in a few seconds of execution time.
Toward a Practical Design Optimization Tool
Authors: Rajan S. D. , Chin S.‐W. , Gani L.
Published: November 2008

Abstract: Design optimization methodologies for sizing and shape optimal design have undergone an evolutionary process over the last two decades. The motivation behind the changes is to develop a methodology with no practical limitations on the nature and size of the problem that can be solved. In this research, a personal computer‐based shape optimal design system is developed with particular attention to robustness, generality, efficiency, and pre‐ and postprocessing. To achieve these objectives, the hybrid natural shape optimization approach is developed and used with adequate control over the velocity field matrix generation. User control over model creation and mesh generation makes it possible to minimize mesh distortion and the need for remeshing. Design sensitivity expressions using the implicit differentiation method are derived. It is shown that the analytical derivatives can be computed efficiently for a variety of functions. Numerical examples are solved to illustrate the developed methodology using a software system developed under the MS‐DOS operating system.
Bridge Condition Rating Using an Eigenvector of Priority Settings
Authors: Melhem Hani G. , Aturaliya Senaka
Published: November 2008

Abstract: To circumvent possible inconsistencies in inspection and rating of highway bridges, two models based on fuzzy logic have been proposed in the literature. These models combine the condition rating of the various elements of the main bridge components to evaluate the overall condition of these components. The first method uses fuzzy weighted average, and the second uses the fuzzy computational technique known as resolution identity of fuzzy sets. A third model proposed by the authors and implemented in a knowledge‐based expert system environment is presented in detail. The fuzzy inference model is based on a priority setting obtained through the solution of an eigenvector problem involving a pairwise comparison matrix of importance. This method and the associated solution technique were developed originally for general use in multiattribute decision making but were never used in a bridge engineering application. The proposed model is superior to other models for bridge rating previously developed because it provides priority settings of the individual elements of a bridge component in addition to the final rating of that component. The computer program was tested using actual bridge inspection data.
Artificial Intelligence in Bridge Engineering
Authors: Reich Yoram
Published: November 2008

Abstract: The idea to use artificial intelligence (AI) in civil engineering is as old as AI itself. Since the 1950s, studies on AI applications in civil or bridge engineering have proliferated. Most of these studies have dealt with specialized isolated engineering subtasks. Few of the applications have been delivered to practitioners and were used to advance their work. This paper presents a model of the life‐cycle flow of information in bridge engineering as an organizing framework for reviewing previous work on AI applications in bridge engineering. Several common patterns that emerge from the studies are summarized. A subsequent analysis of the status of the bridge stock in many countries suggests that a more integrated approach to AI applications may have a larger practical impact. Several practical areas that can benefit significantly from AI techniques are identified, and several studies are proposed including the AI technology needed and the methodology according to which these applications should be developed.