Web-Enabled System Dynamics Model for Error and Change Management on Concurrent Design and Construction Projects

Construction projects are uncertain and complex in nature often because of iterative cycles caused by errors and changes. These errors and changes impair project performance and, consequently, cause schedule and cost overruns to be prevalent. Iterative cycles are more detrimental when design and construction are concurrent and often force activities to proceed without complete information. In an effort to address this issue, this paper presents the information technology aspect of the dynamic planning and control methodology (DPM), which provides a mechanism that will analyze the impact of negative iterative cycles on construction performance. In order to guarantee a smooth application of this method to real-world projects, DPM has been developed by integrating several existing methods around a core system dynamic model for quality and change management and then implementing these methods into a web-based collaborative environment. A case project, applying the developed web-based DPM, shows great potential in facilitating on-site decision making by virtue of its support of data analysis as well as real-time information sharing.     

CONSCOM: An OO Construction Scheduling and Change Management System

In a companion paper, an object-oriented (OO) information model was presented for construction scheduling, cost optimization, and change order management (CONSCOM), based on the creation of a domain-specific development framework. The framework architecture is developed using generic software design elements, called patterns, which provide effective low-level solutions for creating, organizing, and maintaining objects. The OO model has been implemented in a prototype software system for management of construction projects, called CONSCOM, using the Microsoft Foundation Class library in Visual C++. CONSCOM is particularly suitable for highway construction change order management. It can be used by the owner as an intelligent decision support system in schedule reviews, progress monitoring, and cost-time trade-off analysis for change order approval. The OO information model for construction scheduling cost management can be integrated into a concurrent engineering model for the architecture, engineering, and construction industry.     

The delay-reduction hypothesis: Extension to three-alternative choice.

Choice was assessed for 2 and 3 VI schedules arranged in the terminal links of concurrent-chains schedules (Exps I–IV) and simple concurrent schedules (Exp IV). Ss were 14 male White King pigeons. When the 3rd VI schedule provided a relatively high rate of reinforcement, its addition resulted in a divergence of the distribution of responses between the 2 other schedules (Exps I and II). When the 3rd VI schedule provided a sufficiently low rate of reinforcement, its addition resulted in a convergence of the distribution of responses between the other schedules. Both sets of results are consistent with the delay-reduction hypothesis but not the constant-ratio rule. In Exp IV, the 3rd VI schedule was selected so that the delay-reduction hypothesis required no change in the distribution of responses between the other 2 schedules. This experiment also assessed the effects of adding a 3rd VI schedule in a simple concurrent schedule. In both cases the distribution of responses between the other 2 schedules was not affected systematically. Results support an extension of the delay-reduction hypothesis to 3-alternative choice. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strategies for resolving the heterogeneity of schizophrenics and their relatives using cognitive measures.

The resolution of heterogeneity of schizophrenics and their relatives using cognitive tasks requires measures of individual differences—usually of differential ability, which is inferred from differential performance. Tasks that are suited for establishing a group's differential ability are often unsuited for measuring individual differences. The problem is that for any group for which Tasks A and B have different mean accuracy, the (A?–?B) difference scores of individual subjects have an artifactual curvilinear relation to (A?+?B) overall accuracy, with the largest (A?–?B) scores occurring at about 50% (A?+?B) overall accuracy for a dichotomously scored free-response task. Two possible solutions are (a) to convert Task B scores to residualized scores, using the regression of Task B scores on Task A scores as determined for normal subjects; or (b) to titrate overall (A?+?B) accuracy of each subject to a constant level by manipulating a variable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

浅谈工程设计中的项目管理

通过对工程设计中项目管理的组织机构、进度控制、质量管理、成本控制的分析,探讨了工程设计过程强化项目管理,提出了加强项目管理控制的建议。     

Reliability and Stability Buffering Approach: Focusing on the Issues of Errors and Changes in Concurrent Design and Construction Projects

This paper proposes a new buffering approach, reliability and stability buffering, as a means to reduce uncertainty caused by errors and changes, in particular, when concurrent design and construction is applied to an infrastructure project. The proposed buffering provides a proactive mechanism to protect the planned performance of a project with a flexibly located and systemically sized buffer. For its implementation, the reliability and stability buffering is incorporated into a dynamic design and construction project model, which simulates the impacts of errors and changes on design and construction performance and evaluates the effectiveness of the proposed buffers. Applying this buffering approach into the infrastructure project in Massachusetts, this paper concludes that (1) the amount of hidden errors and latent changes was reduced; (2) the flexibly located and distributed buffers helped identify the predecessors’ errors and changes in concurrent design and construction; (3) the impacts of hidden errors and changes were minimized, preventing their ripple effect on the succeeding activities; and (4) the quality of the coordination process was increased. Thus it shows great potential to protect design and construction performance against uncertainty in concurrent design and construction delivery of civil infrastructure projects. Such benefit obtained from the proposed buffering should be relevant to researchers and practitioners because it provides the base for future investigation for the strategic utilization of schedule buffers in an uncertain environment as well as the guideline for their effective use in practice.     

基于多目标满意优化的热轧非对称工作辊设计

热轧非对称工作辊可兼顾板形控制和自由规程轧制,其关键参数通常采用经验设计法,缺乏相应的依据.本文提出了热轧非对称工作辊关键参数的理论设计方法.由于设计过程中无法精确给定已知条件,因此把多目标满意优化引入到非对称工作辊的参数设计中,建立了综合满意度目标函数,并用模拟退火遗传算法进行满意度最优值求解.采用满意解代替最优解,使得辊形参数的优化设计结果更具科学性.在某热连轧生产线上的实际应用表明,优化设计的辊形在板形控制和自由规程轧制方面均取得了理想的效果.      

Causes, Effects, Benefits, and Remedies of Change Orders on Public Construction Projects in Oman

Change orders are usually issued to cover variations in scope of work, material quantities, design errors, and unit rate changes. This paper discusses variations in public construction projects in Oman by investigating causes of variations, studying their effects on the project, identifying the beneficial parties, and suggesting remedies to alleviate related problems. Tasks included an analysis of four actual case studies and conducting a field survey via a questionnaire. It was determined that the client’s additional works and modifications to design were the most important factors causing change orders, followed by the nonavailability of construction manuals and procedures. The most important effects of change orders on the project were found to be the schedule delays, disputes, and cost overruns. The contractor was found to be the party most benefiting from the change orders followed by the consultant and then the client. A set of remedial actions were suggested and respondents viewed that the revision of registration of consulting offices would be the most important action followed by establishing standard documents for design procedures and building a national database about soil conditions and services.     

Automating Schedule Review for Expressway Construction

An expressway project is often divided into subprojects with different tendering packages, and carried out by several general contractors that apply different scheduling practices. Each schedule may contain hundreds of activities, each of which is associated with multiple pay items that determine its earned monetary value. With such huge amount of information, the reviewer can only check a sample piece of information, and the quality of review highly depends on the reviewer’s experience and devotion. Automated schedule review provides a solution to reduce such problems encountered in the industry. This paper presents a module-based schedule generation and review model, which includes a predefined set of network modules, network builder assistant computer system that helps schedulers manage and reuse the modules to build a new schedule, and another computer system network review assistant (NRA) that helps reviewers review schedules. The NRA uses generalized rule forms to represent the schedule critique knowledge collected from the industry. When potential errors are found, the NRA adopts case-based reasoning to suggest possible correction based on similar cases. The evaluation conducted by the practitioners using real projects indicates that NRA reduces review time, and provides more accurate review on finding activities and related pay items not conforming to standards, and reminding users of important but often omitted activities.     

Design Structure Matrix Implementation on a Seismic Retrofit

A void exists in development of design theory methodology within the structural engineering community. This void hampers efforts to resolve performance deficiencies including cost over-runs, unplanned rework, and suboptimal design. In manufacturing, product design and production improvements have resulted from implementation of the design structure matrix (DSM) methodology. DSM offers a means to represent, analyze, and decompose complex systems in order to improve their performance. DSM use within the architecture engineering construction (AEC) industry has been sporadic and focused primarily in the U.K. Where applied, DSM has proven effective at helping AEC design teams streamline processes to address nonlinearity (nonsequential information flows) introduced by iteration and complexity in design. When a DSM reveals iteration and highly dependent work, group brainstorming, collocated design sessions, rapid feedback, set-based design, and collaborative design aids can be used to increase overall team effectiveness. This paper examines a case study where DSM-based planning software was used on a seismic retrofit project to drive process improvement in design management. DSM correctly identified iterative activities central to design and provided the following; (1) a common vocabulary to discuss rework in the context of a multidisciplinary design team; (2) a rational method to schedule team collocation and brainstorming efforts to maximize their benefit; and (3) a means to consider iterative activities (and associated hand-offs) in design work structuring.     

Cognizance of Visual Design Management in Life-Cycle Project Management

This paper presents a unique approach to information management within a life-cycle project management model. Focus is shifted from the delivery of the physical facility to the creation of a business to service the project objectives employing concurrent engineering∕construction approaches. Typical life-cycle objectives are life-cycle cost and net worth, or cost/worth ratio. The definition and broad design of the facility and its components will be a collective responsibility, discharged by composite teams whose members are drawn from the respective participants. Their inputs are evaluated in real time against the above objectives. The traditional responsibility for detailing and conformity to the relevant codes and standards will still reside with the relevant design professionals. This paper introduces a visual design management system that has been developed to reflect the fundamentals of information and design management within the life-cycle project management paradigm.     

Dependency conflicts in high-achieving women: Toward an integration.

Explores the dependency conflicts experienced by women who are in professional training in medicine and other biological sciences. As they become involved in psychotherapy, these high-achieving women find themselves caught in a struggle between their wish to be self-sufficient and to be help givers and their wish to have their needs for affection and nurturance met. Despite their excellent academic performance, they feel inadequate, lonely, and unable to succeed in establishing intimate relationships. Psychotherapy focuses on resolving the dependency conflicts through (1) increased awareness and acceptance of dependency needs, (2) gradual relinquishment of those wishes that are unattainable, and (3) development of an identity in which closeness, support, and emotional expression are better integrated with the needs for striving and self-sufficiency that have dominated the woman's life since childhood. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Representation for Conceptual Design of Buildings

The building representation for storing design solutions adopted in SEED-Config consists of two levels of abstraction models defined on top of the object-oriented data model. The first level is an information model, called the building entity and technology model, which stores design data as they are generated during conceptual design, supports case-based reasoning, and shares data among all design participants. This model represents each building entity as a generic container that encompasses its properties, taxonomy, geometry, composition, relationships, and design knowledge applied in generating it. The second level is a conceptual model that defines the types of objects, relationships, and data needed to fully represent the information in a given design domain. The conceptual model specifies the semantics of the design information for the domain using the syntax defined in the information model. The proposed representation also includes a faceted classification scheme to define the controlled vocabulary from which indexes are obtained. The representation has the following advantages: It integrates multiple views, supports design evolution, supports design exploration, and is extensible.     

Quality and Change Management Model for Large Scale Concurrent Design and Construction Projects

Concurrent design and construction has been lauded for streamlining projects in terms of time. However, such an approach may actually make projects more uncertain and complex than the traditional sequential design and construction process. The main sources of risk that have been identified with concurrent design and construction are iterative cycles that result from unanticipated errors and changes and their subsequent impacts on project performance. As an effort to address these detrimental impacts, a framework for quality and change management that identifies those negative iterative cycles is proposed. The proposed framework is incorporated into the system dynamics model of dynamic planning and control methodology (DPM), which has been developed to evaluate negative impacts of errors and changes on construction performance. Relevant to practitioners and researchers, the potential of DPM as a robust design and construction planning methodology that could effectively deal with errors and changes inherent in the design and construction process is demonstrated through a case study involving the Treble Cove road bridge in Massachusetts.     

Acquisition of intravenous cocaine self-administration with concurrent access to food in cynomolgus monkeys.

The present study used a concurrent schedule of food and drug delivery in socially housed male cynomolgus monkeys (Macaca fascicularis; N?=?15) to study variables that influence cocaine acquisition. Each monkey was implanted with subcutaneous vascular access ports, and responding was maintained under a concurrent food, saline schedule with the lever associated with each stimulus presentation varied daily. Next, increasing cocaine doses (0.003–0.3 mg/kg/inj) were concurrently available with food for at least 5 consecutive sessions per dose. Under these conditions, an unexpected lever bias emerged in all 15 monkeys. The development of the lever bias could not be predicted on the basis of cocaine dose or total intake and was not related to social rank. These findings suggest that in monkeys, concurrent fixed-ratio schedules of food and cocaine presentation may result in persistent biased responding that overshadows cocaine preference in studies of acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Managing Tipping Point Dynamics in Complex Construction Projects

Complex construction projects are vulnerable to tipping points. Tipping points are conditions that, when crossed, cause system behaviors to radically change performance. Previous research identified tipping point dynamics as capable of explaining the failure of some nuclear power plant construction projects. These dynamics can also threaten the success of other large, complex construction projects. The current work uses a dynamic project model to test policies for managing tipping point dynamics. The Limerick Unit 2 nuclear power plant project is used to test model usefulness. Sensitivity analysis reveals the rework fraction, strength of subsystem interdependence, and sensitivity of the project to schedule pressure as potential high-leverage points for policy design. The model is used to test policies for managing tipping points that were used to complete the Limerick Unit 2 nuclear power plant after a tipping point threatened project completion. Implications for construction project design and management and research opportunities are discussed.     

Construction Scheduling and Progress Control Using Geographical Information Systems

Traditional scheduling and progress control techniques such as bar charts and the critical path method (CPM) fail to provide information pertaining to the spatial aspects of a construction project. A system called PMS-GIS (Progress Monitoring System with Geographical Information Systems) was developed to represent construction progress not only in terms of a CPM schedule but also in terms of a graphical representation of the construction that is synchronized with the work schedule. In PMS-GIS, the architectural design is executed using a computer-aided drafting (CAD) program (AutoCAD), the work schedule is generated using a project management software (P3), the design and schedule information (including percent complete information) are plugged into a GIS package (ArcViewGIS), and for every update, the system produces a CPM-generated bar chart alongside a 3D rendering of the project marked for progress. The GIS-based system developed in this study helps to effectively communicate the schedule∕progress information to the parties involved in the project, because they will be able to see in detail the spatial aspects of the project alongside the schedule.     

SPROUT—A Modeling Language for SEED

An important capability of the SEED system is rapid generation of internal design representations, including design alternatives, that can be evaluated in terms of a broad range of criteria. It consists of modules that must communicate with each other and remain extensible. From a software engineering perspective, there exists no single programming language or database management system, commercial or research-based, that provides all the needed support. In this paper, we describe the SPROUT modeling language, the cornerstone of efforts to bridge this gap. It supports the specification of a system information model, which contains a building product model as a subset. Developments are discussed that lead to the current language design as well as the support for case-based design, persistent storage of objects, management of versions and alternatives, and communication between different SEED modules (i.e., agents). Emphasis is placed on the automatic generation of computer programs and database schemas from a SPROUT specification. Lastly, this effort is compared to other comparable efforts including PDES∕STEP.     

Childhood family antecedents of dependency and self-criticism: Implications for depression.

Presents an etiologic model of how relationships with parents in childhood influence differential vulnerability to distinctive depressive experiences associated with issues of dependency or self-criticism. 86 female undergraduates were administered a battery of measures, including the Depressive Experiences Questionnaire, to measure Ss' current experiences of dependency and self-criticism. These were correlated with their retrospective reports of parental behavior in childhood. It was predicted that Ss high on dependency would report the mother as being the more dominant parent and as emphasizing strict control, expressing inconsistent affection, and expecting conformity to authority rather than achievement. Individuals high on self-criticism, in contrast, would report the father as more dominant and both parents as emphasizing strict control, expressing inconsistent affection, and expecting achievement and success rather than passive conformity. Results generally support these predictions and complement the findings of other recent studies of depressed individuals' memories of their parents' childrearing practices. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)