Production System Loading–Cycle Time Relationship in Residential Construction

Production home building possesses characteristics similar to manufacturing processes, such as the construction of more or less similar houses repeatedly and a growing demand for mass customization of homes. As a result of these similarities, larger homebuilders often attempt to view their production system as an assembly line process. However, the management tools generally utilized by these home builders are those used in other sectors of the construction industry, such as critical path method scheduling, cost estimating, and earned value analysis. These management tools do not provide an explanation or control/prediction tools for many undesirable situations that arise during home building, such as increasing cycle time which slows delivery of product to consumers and increases project capital costs, and increasing amounts of work in process that increases capital investment and thereby decreases company financial performance. In order to bring better management tools to the residential construction industry, this study examines relationships between cycle time, work in process, system throughput, new construction starts, and the capacity of the production system using building permit data for new single family homes in Chandler, Ariz. The applicability of Little’s law, a basic equation used in factory production management models, to a residential production system is examined. This study shows a definite, predictable relationship between cycle time, work in process, and production system throughput. It provides a pathway for further study of production system characteristics that have historically not been included in construction management models, with the expectation of developing new construction management tools that will account for more of the characteristics of construction production systems that affect project performance and company financial performance.     

Multiple Device Collaborative and Real Time Analysis System for Project Management in Civil Engineering

Complexity in civil engineering projects has increased over the years, which has led to an increase in the number of organizations involved in those projects. In today’s environment, these organizations operate in different parts of the world requiring their personnel to be geographically distributed. However, current project management practices require project personnel to be geographically collocated and, thus, are unable to provide the infrastructure to support geographically distributed project management teams. In addition, current project management practices require access to personal computer (PC) based resources for project information, which is not always a feasible alternative for on-site project personnel, as it requires certain hardware and office configurations. Thus, alternatives to PC-based resources such as personal digital assistants (PDA) or phones are needed for information access. Moreover, once project information has been conveyed to all project personnel, the system should aid them in terms of providing data analysis tools and presenting technical or management solutions to the problems encountered by the project personnel. This paper presents a collaborative project management system with a knowledge repository, analysis resources, and multiple device access to support the infrastructure of distributed project management teams in complex architecture/engineering/construction projects. The primary goal for such a system would be to provide a platform where project information can be effectively shared with any of the project management personnel from anywhere and with a very few limitations on the computing device.     

Resource Allocation for Concrete Batch Plant Operation: Case Study

A concrete batch plant is an important element in any concrete construction process, whether it is working as a central mixing plant onsite or is offsite supplying ready mixed concrete to a project. This study tackles the problem of optimizing plant production to maximize profit and, if possible, revenue. A linear programming model has been designed to optimize the plant operation. The maximum production rate for each type of concrete can be obtained by solving the model under the given constraints. A sensitivity analysis is conducted to provide management with a flexible range of prices per cubic yard (cubic meter) and material storage limits. In addition, a model has been designed to determine the optimal number of transit mixers based upon the required quantity of concrete. A chart has been developed to determine the quantities of concrete ingredient materials required daily to organize the available storage space and to plan their delivery.     

HKCONSIM: A Practical Simulation Solution to Planning Concrete Plant Operations in Hong Kong

Newly developed approaches for construction simulation have been used to model the one-plant-multisite ready mixed concrete (RMC) production system, validated by real-life operations data in Hong Kong. HKCONSIM—a computer system for simulation modeling and analysis of Hong Kong’s RMC production operations was developed in-house. The system is suitable for the resource provision planning and the production planning of a RMC plant, so as to meet given demands at a number of sites for concrete over a working day. The emphasis of the simulation modeling is on the interactions of multiple sites with the plant, and the objective is to improve the supply service levels and the utilization of plant resources. One significant improvement achieved via the research is that to simulate the RMC production operations with HKCONSIM does not require familiarity by the user with any software-specific terminology and modeling schematics, in contrast with existing simulation methods; the process of constructing a simulation model is reduced to specifying the attributes for each pour and site and providing the plant and truckmixer resources available on self-explanatory on-screen forms. Therefore, by experimenting on a HKCONSIM produced model the user, being a practitioner in the concreting industry, can readily study complicated relationships between the pattern of demand for concrete, the resources available to the system, and the service levels achieved together with the utilization levels achieved for the resources involved. Conclusions are given on the research and recommendations for future work made.     

An Ontology for Relating Features with Activities to Calculate Costs

It is the cost estimator’s task to determine how the building design influences construction costs. Estimators must recognize the design conditions that effect construction costs and adjust the project’s activities, resources, and resource productivity rates accordingly to create a cost estimate for a particular design. Current tools and methodologies help estimators to establish relationships between product and cost information to calculate quantities automatically. However, they do not provide a common vocabulary to represent estimators’ rationale for relating product and cost information. This paper presents the ontology we formalized to represent estimators’ rationale for relating features of building product models to construction activities and associated construction resources to calculate construction costs. A software prototype that implements the ontology enables estimators to generate activities that know what feature requires their execution, what resources are being used and why, and how much the activities’ execution costs. Validation studies of use of the prototype system provide evidence that the ontology enabled estimators to generate and maintain construction cost estimates more completely, consistently, and expeditiously than traditional tools.     

Application of the Theory of Inventive Problem Solving in Tunnel Construction

Despite the importance of innovation in construction, there is no structured approach to systematically support innovation. The theory of inventive problem solving (TRIZ) provides a unique approach for structuring the development of innovative solutions for technical problems and has the potential for substantial results in construction innovation if used properly. This paper describes TRIZ and introduces its tools through applications in the field of utility tunnel construction. This paper describes how TRIZ tools can be used to generate conceptual solutions to a number of tunnel construction problems. In order to assess the practicality of the TRIZ analysis, the proposed solutions are compared to recent innovations in the field and actual solutions developed by experts. The comparison shows that although TRIZ tools were used by nonexperts in the tunneling field they included most of the features that exist in solutions developed by experts and were also able to point to technologies that are not yet widely used in the tunneling industry. The use of TRIZ in these applications showed that despite the advantages of the theory, further research and supporting tools are required to facilitate its day-to-day use in the construction industry.     

炼钢多流仿真系统的设计与开发

炼钢多流仿真系统是可为用户提供"物质、能量、成本"一体化优化的炼钢生产整体解决方案的辅助工具。在确定系统的设计目标和设计原则基础上,设计和开发了炼钢多流仿真系统,并详细介绍了该系统的总体结构、功能模块和计算流程。以某钢厂生产条件为输入进行了实例仿真,验证了仿真系统的有效性,该系统可向用户提供物流、能量、成本相关指标的分析,用于辅助炼钢生产管理决策。     

Managing Construction Projects Using the Advanced Programmatic Risk Analysis and Management Model

Risk management is an important part of construction management, yet the risk-based decision support tools available to construction managers fail to adequately address risks relating to cost, schedule, and quality together in a coherent framework. This paper demonstrates the usefulness of the Advanced Programmatic Risk Analysis and Management Model (APRAM) originally developed for the aerospace industry, for managing schedule, cost, and quality risks in the construction industry. The usefulness of APRAM for construction projects is demonstrated by implementing APRAM for an example based on an actual building construction project and comparing the results with other risk analysis techniques. The results show that APRAM simultaneously addresses cost, schedule, and quality risk together in a coherent, probabilistic framework that provides the information needed to support decision making in allocating scarce project resources.     

Productivity Analysis of Construction Operations

An interactive system for analysis of construction operations is proposed. The analysis is carried out in the context of various work modules which address quantity development, resource definition, and production and cost analysis. The quantity work module generates quantities based on information available in the design documents. The resource definition module receives and stores data regarding the labor∕equipment combination to be used to execute work tasks. This module provides the user with a set of standard useful construction process models. For each construction operation to be analyzed, the terminal describes the standard models. The user makes input of a set of parameters for process keyname, quantity, work task durations, number of resources, production capacity of each unit, and cost per hour of each unit to the standard model to be used. Using input from the resource definition module, the productivity and cost analysis module generates production rates and unit costs based on process simulation using CYCLONE methodology.     

Simulation Approach to Evaluating Cost Efficiency of Selective Demolition Practices: Case of Hong Kong’s Kai Tak Airport Demolition

This research resorted to the use of construction operations simulation modeling to investigate the cost efficiency of waste-handling practices on the Kai Tak Airport demolition project in Hong Kong. By modeling the site operation of sieving and stockpiling broken concrete, the well-established construction simulation methodology of CYCLONE was contrasted with the newly developed simplified discrete event simulation approach (SDESA). Further, the SDESA model was readily extended to include (1) raw demolition waste collecting and sorting; (2) broken concrete sieving and stockpiling; (3) steel bar recycling; and (4) debris disposal at the landfill. The production rate derived from simulation was indicative of a close match between the simulation model and the actual site system. The resulting simulation model provided a basis for evaluating the cost efficiency of actual site operations and alternative resource provision scenarios being postulated. Through computer simulation, the actual site operation was found smooth and efficient with utilization rates for resources of different types ranging from 79 to 99%. In addition, the cost–time reduction ratios were calculated for four alternatives of resource provisions in comparison with the original base case. The research findings suggested that provided the project budget had satisfied the higher cash flow requirement, doubling the resource provision on site would potentially cut the project duration by half and not increase the total direct cost.     

�������ݿ���к��������Ϣ�����ݴ���

In order to improve the management level of plate enterprises, ERP, MES and process control system (PCS) were used coordinately for the information management. Stable information exchange was the most important condition for the best using of information management. According to the plate production process, the specific content and trigger time for the data exchange between PCS and MES were designed. Intermediary database was used for date exchange implement. The information data exchange technology developed for the PCS and MES was applied successfully for several domestic plate plant lines. The logistics and information flow for the plate line have been running smoothly. It also can provide a reference for the information construction of similar production lines.     

Multiobjective Linear Programming Model for Scheduling Linear Repetitive Projects

Linear repetitive construction projects require large amounts of resources which are used in a sequential manner and therefore effective resource management is very important both in terms of project cost and duration. Existing methodologies such as the critical path method and the repetitive scheduling method optimize the schedule with respect to a single factor, to achieve minimum duration or minimize resource work breaks, respectively. However real life scheduling decisions are more complicated and project managers must make decisions that address the various cost elements in a holistic way. To respond to this need, new methodologies that can be applied through the use of decision support systems should be developed. This paper introduces a multiobjective linear programming model for scheduling linear repetitive projects, which takes into consideration cost elements regarding the project’s duration, the idle time of resources, and the delivery time of the project’s units. The proposed model can be used to generate alternative schedules based on the relative magnitude and importance of the different cost elements. In this sense, it provides managers with the capability to consider alternative schedules besides those defined by minimum duration or maximizing work continuity of resources. The application of the model to a well known example in the literature demonstrates its use in providing explicatory analysis of the results.     

Dynamic Layout Planning Using a Hybrid Incremental Solution Method

Efficiently using site space to accommodate resources throughout the duration of a construction project is a critical problem. It is termed the “dynamic layout planning” problem. Solving it involves creating a sequence of layouts that span the entire project duration, given resources, the timing of their presence on site, their changing demand for space over time, constraints on their location, and costs for their relocation. A dynamic layout construction procedure is presented here. Construction resources, represented as rectangles, are subjected to two-dimensional geometric constraints on relative locations. The objective is to allow site space to all resources so that no spatial conflicts arise, while keeping distance-based adjacency and relocation costs minimal. The solution is constructed stepwise for consecutive time frames. For each resource, selected heuristically one at a time, constraint satisfaction is used to compute sets of feasible positions. Subsequently, a linear program is solved to find the optimal position for each resource so as to minimize all costs. The resulting sequence of layouts is suboptimal in terms of the stated global objective, but the algorithm helps the layout planner explore better alternative solutions.     

Resource Optimization Using Combined Simulation and Genetic Algorithms

This paper presents a new approach for resource optimization by combining a flow-chart based simulation tool with a powerful genetic optimization procedure. The proposed approach determines the least costly, and most productive, amount of resources that achieve the highest benefit/cost ratio in individual construction operations. To further incorporate resource optimization into construction planning, various genetic algorithms (GA)-optimized simulation models are integrated with commonly used project management software. Accordingly, these models are activated from within the scheduling software to optimize the plan. The result is a hierarchical work-breakdown-structure tied to GA-optimized simulation models. Various optimization experiments with a prototype system on two case studies revealed its ability to optimize resources within the real-life constraints set in the simulation models. The prototype is easy to use and can be used on large size projects. Based on this research, computer simulation and genetic algorithms can be an effective combination with great potential for improving productivity and saving construction time and cost.     

Simplified Discrete-Event Simulation Approach for Construction Simulation

The methodology of discrete-event simulation provides a promising alternative solution to designing and analyzing dynamic, complicated, and interactive construction systems. In this paper, an attempt is made to extend the previous work of simplifying construction simulation by delving into the fundamental approaches for discrete-event simulation. A new simplified discrete-event simulation approach (SDESA) is presented through extracting the constructive features from the existing event/activity-based simulation methods; both the algorithm and the model structure of simulation are streamlined such that simulating construction systems is made as easy as applying the critical path method (CPM). Two applications based on real road construction projects in Hong Kong serve as case studies to illustrate the methodology of simulation modeling with SDESA and reveal the simplicity and effectiveness of SDESA in modeling complex construction systems and achieving the preset objectives of such modeling. They are a granular base-course construction system featuring both cyclic and linear processes and an asphalt paving construction system with complicated technological/logical constraints. As a general-purpose method for construction planning, SDESA enables practitioners to deal with what the CPM-based network analysis method fails to solve by offering discrete-event simulation capabilities. Furthermore, the SDESA can potentially be adapted to special-purpose simulation tools to tackle large and complicated construction systems of practical size that have yet to find convenient solutions with existing simulation methods.     

基于AutoCAD的露天矿三维建模与应用研究

露天矿三维地质模型是数字矿山建设中的信息平台,对露天矿的工程设计、生产管理有重要的指导意义。在AutoCAD平台下,以某露天矿为例,建立地质数据库,根据断层线构建断层线框模型,根据采场现状图和地形等高线构建地形模型,根据钻孔数据和内插点构建煤岩实体模型,实现了露天矿三维地质模型的可视化显示;根据煤岩实体模型建立块体模型,对块体模型添加属性、赋值,并将其应用到露天矿采剥工程量计算中,与传统算量方法相比,该方法操作简单,提高了计算的速度与精度。     

强化管理 节能降耗

近几年来山东铝业公司铝加工厂,强化内部管理,健全节能管理制度和完善能源统计网络及机构;依靠科技进步,采用三项新技术,探索节能工作的新方法,在推进节能技术进步方面取得了一些成效。为提高能源利用率、降低生产成本、提高企业经济效益创造了有利条件。     

Theatre utilization analysis

A method of analysing operating theatre utilization is presented as a management information system applicable to medical administration.The operating theatre plant represents an item of considerable expenditure in a hospital budget. This aspect of hospital activity requires maximized utilization to ensure an appropriate cost benefit. Extraction of information in such a form provides a basis for exact comparisons of performance of the personnel involved and determining needs for additional resources.     

Iconic Animation for Activity-based Construction Simulation

This paper discusses the development of an animation tool for the activity-based construction (ABC) modeling and simulation system. The tool uses an activity-based network diagram, i.e., ABC simulation model, as the animation background image, and uses precreated two-dimensional (2D) iconic images for simulation entities (e.g., resources). The animation process displays the queuing status and dynamic movements of 2D iconic images on the background. It also distinguishes active and idle states of resources and activities. Dynamic reports are available for selected activities with graphs including the production rate and utilization of involved resources. From visualizing the change of status of a simulation process and dynamic interaction between simulation entities in the process, the user can better understand the dynamic nature of the construction process. Animation provides an avenue to demonstrate how dynamic operations are simulated. It also provides an effective tool for the user to verify a simulation model and to validate the obtained simulation results. Compared to other systems, the ABC animation does not require any extra effort in addition to the ABC simulation model constructed for simulation purposes. Therefore, the presented technology greatly reduces the time and cost for achieving animation. A variety of useful information can be observed through animation, and is illustrated using two construction examples.