Repetitive Scheduling Research Articles

TEACHING HOW TO USE A REPETITIVE SCHEDULING METHOD WHEN PLANNING A GREEN CONDOMINIUM BUILDING

ABSTRACT This paper aims to present a methodology for use in construction planning named the Repetitive Scheduling Method (RSM). Students on a graduate level construction management program can learn how to create a RSM schedule to be applied to a real project. Typically, the Critical Path Method (CPM) is used to plan general construction projects. This paper presents a case study wherein a CPM diagram is transformed into a RSM schedule for use in the construction of a green condominium. RSM is the most suitable tool for planning repetitive projects like condominium buildings, apartment complexes, or real estate development projects. It utilizes an uninterrupted flow of resource concept in order to eliminate manpower-related resource wastage. As a result, construction productivity can be improved by using the right construction planning tool on the right project. Interested graduate students researching construction engineering can apply RSM on their repetitive projects in the future.

Hierarchical scheduling for real-time agile satellite task scheduling in a dynamic environment

The imaging processes of optical satellites can be easily affected by unexpected environmental changes, such as changes in cloud coverage. Given the difficulty to predict environmental uncertainties, traditional offline scheduling methods need a follow-up re-scheduling process that responds to real-time environmental information. This repetitive scheduling processes make the offline fine scheduling process a waste of computational resources. Additionally, the offline scheduling method is quite complex owing to its lack of a hierarchy mechanism. To solve these problems, we propose a hierarchical scheduling method for the real-time scheduling problem. This method divides the scheduling process into three steps: pre-assignment, rough scheduling, and fine scheduling. A hierarchical scheduling algorithm based on ant colony algorithm is proposed. Tests with 36 scenarios show that the calculation time is efficiently reduced with this new mechanism. With this consideration of the dynamic environment, the re-scheduling process becomes unnecessary, meaning the wasting of computational resources is avoided and the solution profit is improved.

Line-of-balance against linear scheduling: critical comparison

Among alternative scheduling techniques in construction management are linear and repetitive scheduling and line of balance (LOB). They are uniquely different from the dominant network-based technique because they have been developed for projects with repetitive units of work and crew operations. Notably, they feature quantitative measures of both work and time, which no network-based approach offers. However, a study of their origins – for example, the US Navy – reveals that their original use and capabilities deviate from current application, which is limited at best. Indeed, currently, the name-giving LOB is itself omitted. Therefore, this research has the goal to explore these scheduling techniques in detail. Its objectives are to delineate their modelling elements as described by original sources in a structured manner, to compare them in detail and identify any changes over time and to comment on implications for practical use and extract unsolved research questions. Its methodology follows a comparative research approach. Differences are found in how productivity and cyclic crew deployment are expressed, besides the glaring omission of the LOB itself in the construction use of this method. It is found that, historically, LOB was intended for manufacturing, but when introduced to construction, important characteristics of the production plan and progress chart became forgotten. In parallel, linear scheduling was developed for construction, whose similarities to LOB may have added confusion. Clarifying the complete methods by explicitly outlining their analytical capabilities will improve understanding to allow project managers to benefit from these powerful tools. It also enables future research to model LOB with singularity functions to yield a unified formulation of these alternative scheduling techniques.

Repetitive Scheduling Method: Requirements, Modeling, and Implementation

AbstractProjects with repeating activities, such as multistory buildings and highways, present unique scheduling challenges. This paper presents the necessary requirements that scheduling systems should address to meet the needs and complexities of repetitive projects in practice. The repetitive scheduling method (RSM) provides a unified scheduling framework that applies to all types of repetitive projects. In RSM, projects are classified as discrete (vertical) or continuous (horizontal or linear) and then as uniform and nonuniform, depending on whether progress is measured using a counting scale or a dominant-attribute scale. RSM modeling elements include three types of activities (line, block, and bar) and 10 types of relationships (links) between activities. RP2, a computer program developed by the authors to validate the proposed scheduling approach, is used to develop the production diagrams and tabular reports of the target schedule for a complex of four-story apartment buildings for a low-income ho...

반복공구 작업조 동기화 시스템 개발

Repetitive project planning and scheduling method requires complementing the disadvantages of the critical path method (CPM) and the line of balance (LOB) method, which are confined in time-driven and graphical analysis, respectively. CPM is lack of capability to handle repetitive projects. LOB is also lack of analytical qualities of schedule information due to its' dependency on graphical technique. Existing studies attempt to combine CPM and LOB techniques in a system. However, they are mostly graphical methods. A new method integrating CPM and LOB techniques is presented so as to schedule repetitive projects using formula computing schedule information of each and every units of a project schedule. The proposed method perform basic LOB calculations to ensure resource employment continuity. Each and every activity durations at all units, floats and project completion time are computed using CPM method. Test cases are conducted to verify the potential of the proposed method.

Construction spatial modeling and scheduling with three-dimensional singularity functions

Previous approaches for construction project scheduling have been limited to one dimension of time for bar charts and two dimensions for linear and repetitive scheduling approaches, which added a measure of work quantity. The question therefore arises if and how it is possible to derive a three-dimensional and ultimately multi-dimensional model. Reviewing mathematical theory finds that traditional functions lack the capability to express intervals for activities. Singularity functions are therefore chosen to newly derive stationary and directional activities in a Cartesian coordinate system, wherein the two dimensions of the floor plan area plus one dimension of time are explicitly modeled in an integrated manner. They are implemented into a conflict-avoiding heuristic scheduling algorithm that minimizes total project duration, which is computerized and validated with example calculations.

Batch-Size Based Repetitive Scheduling Method (BRSM)

Repetitive construction projects require trade contractors to repeat construction processes in multiple units (or locations). Several repetitive scheduling methods have been developed and used for repetitive projects. However, in many cases, trade contractors in repetitive construction projects produce their products in batches, not singly. Batch production in construction projects is not rare and management of batch size has been of interest to researchers. However, there is no scheduling method for repetitive projects under batch production. Therefore, the Batch-size based Repetitive Scheduling Method (BRSM) was developed. The BRSM includes new approaches to find start time and finish time of each batch in activities and allows us to compare trade-off between time reduction and work continuity. Also, it includes an algorithm to find the better option between early schedule and late schedule. The application of this method is demonstrated by a simple example project. The BRSM can benefit construction practitioners by allowing an option to accommodate different batch sizes for repetitive scheduling in a mathematical and heuristic approach.

An Algorithm for Scheduling Repetitive Projects with Resource Continuity and Different Batch Sizes

Batch production is common in repetitive construction projects, and it is not unusual for different batch sizes to be used by contractors in one project. While several scheduling methods, such as the Linear Scheduling Method (LSM) and the Repetitive Scheduling Method (RSM) have been proposed and used, no mathematical method for repetitive construction projects has been developed, and it is difficult to consider different batch sizes with the existing methods. An original mathematical algorithm for scheduling repetitive projects with different batch sizes is proposed in this study. This algorithm is illustrated with assumptions of resource continuity and single path in a project and introduces new terms, control batch and critical batch. The algorithm logics and mathematical equations are validated by comparison with the outcomes from a graphical scheduling approach through a simple and practical hypothetic project. As a result, it is expected that the proposed algorithm can be easily adapted and extended to computer software for scheduling, and can be a starting point for research on batch size management in repetitive construction projects.

Resource Continuity Constraints in Repetitive Project Scheduling

In projects with repeating activities and in which the duration of activity unit has been influenced by resource-constrained, Repetitive Scheduling Method (RSM) can be combined to ensure uninterrupted usage of resources between similar activities in different units. The reason for this approach is that in practice the application of RSM may be hindered by several considerations, in this paper we present a cloud genetic algorithm for repetitive project scheduling, in which considering Resource continuity constraints in Repetitive Project scheduling to solve the problem. An example application is presented to illustrate implementation and features of the proposed model. Finally, the relationship of duration and limited amount of resources have been analyzed.

Equilibrium at a bottleneck when long-run and short-run scheduling preferences diverge

We consider the use of a Vickrey road bottleneck in the context of repetitive scheduling choices, distinguishing between long-run and short-run scheduling preferences. The preference structure reflects that there is a distinction between the (exogenous) ‘long-run preferred arrival time’, which would be relevant if consumers were unconstrained in the scheduling of their activities, and the ‘short-run preferred arrival time’, which is the result of an adaptation of travel routines in the face of constraints caused by, in particular, time-varying congestion levels. We characterize the unpriced equilibrium, the social optimum as well as second-best situations where the availability of the pricing instruments is restricted. All of them entail a dispersed distribution of short-run preferred arrival times. We obtain the intriguing results that the dispersion is lower in the social optimum than in the unpriced equilibrium, and that the application of first-best short-run tolls does not induce efficient long-run choices of travel routines.

Evaluating Schedule Uncertainty in Unit-Based Repetitive Building Projects

Various risk factors affect construction projects. Due to the uncertainties created by risk factors, actual activity durations frequently deviate from the estimated durations in either favorable or adverse direction. For this reason, evaluation of schedule uncertainty is required to make decisions accurately when managing construction projects. In this regard, this paper presents a new computer simulation model - the Repetitive Schedule Risk Analysis Model (RSRAM) - to evaluate unit-based repetitive building project schedules under uncertainty when activity durations and risk factors are correlated. The proposed model utilizes Monte Carlo Simulation and a Critical Path Method based repetitive scheduling procedure. This new procedure concurrently provides the utilization of resources without interruption and the maintenance of network logic through successive units. Furthermore, it enables assigning variable production rates to the activities from one unit to another and any kind of relationship type with or without lag time. Details of the model are described and an example application is presented. The findings show that the model produces realistic results regarding the extent of uncertainty inherent in the schedule.

Criticality Comparison between the Repetitive Scheduling Method and the Network Model

Although the repetitive scheduling method (RSM) is more visual and straightforward and is easier to use, the network model is more commonly accepted by both owners and contractors as a means for modeling repetitive projects. In this paper, a method for converting an RSM into an equivalent network model is proposed, and the cause of differing makespans and critical paths in the relevant literature is examined. Using the proposed method for converting an RSM into a network model enables the transfer of both resource continuity requirements and distance constraints. For three different distinguishing cases, a comparison of critical paths and activity criticality is made between an RSM and a network model, with the results showing that the RSM coincides completely with the network in terms of the makespan, critical path, and activity criticality. From this comparison, variances in makespan and criticality in existing literature are caused by the conversion of backward-controlling RSM segments containing two or more subactivities, without maintaining resource continuity. This paper can help researchers to better understand the relationship between these two methodologies. It offers practitioners a method for easily and accurately converting an RSM to a network model when contractually required, and practitioners can accrue the benefits of both methodologies.

Design of a Resource Scheduling Tool for Production Project Management

Production planning is clearly needed in all manufacturing systems, and that is also the case for job shops. When dealing with a small number of products or jobs repetitive scheduling becomes a major issue. In this situation, the same tasks are performed sequentially and repeated from job to job. To help with this problem, a resource scheduling tool is developed that would work alongside Microsoft Project. This tool should act as a front end to Microsoft Project and allow for the creation of a schedule with a minimal amount of work for the scheduling manager. Due to the repetitive nature of production processes, the tool should be able to eliminate most of the manual scheduling currently done exclusively in MS Project.

Controlling Path and Controlling Segment Analysis in Repetitive Scheduling Method

AbstractThe controlling path and controlling segment are the basis for repetitive project scheduling. In this paper the controlling path is defined as the longest path in duration that determines the minimum project duration, including the controlling segments and controlling constraints on it. The controlling segments are defined as the subactivities on the controlling path. A method to identify the controlling path and controlling segments is proposed, on the basis of the technology of identifying the potential controlling points. To investigate how the project duration is determined, three types of controlling segments are defined and analyzed, namely, the forward controlling segment, the point controlling segment, and the backward controlling segment. This paper presents a convenient and correct way to identify the controlling path and controlling segments conforming to the constraints of projects.

Fuzzy Repetitive Scheduling Method for Projects with Repeating Activities

In projects with repeating activities (such as multistory buildings, highways, or pipelines consisting of reiterating identical or similar units) and in which the activity unit production rates are characterized by uncertainty or imprecision, fuzzy set theory and the well-established repetitive scheduling method (RSM) can be combined to ensure uninterrupted usage of resources between similar activities in different units. The reason for this approach is that in practice the application of RSM may be hindered by several considerations, for example, repetitive units may be slightly different from each other, the performance of construction crews may vary, and there may be complex resource matching and sharing between activities and work sites. The proposed methodology is termed fuzzy repetitive scheduling method (F-RSM), and it requires a generalization of RSM in which schedules are represented by two- or three-dimensional graphs and whereby the concepts of a control segment and the controlling sequence area are introduced. The resulting methodology addressing the original RSM scheduling problem is presented in this paper.

Productivity Scheduling Method Compared to Linear and Repetitive Project Scheduling Methods

The analysis of project schedules is among the central tasks of construction managers. Parallel to the well-known critical path method, linear scheduling techniques have been researched. The two most fully developed existing methods, the linear scheduling model and the repetitive scheduling method, are reviewed. Based on a discussion of a published example, the new mathematical analysis method for linear and repetitive schedules is introduced. The productivity scheduling method is based on singularity functions that provide a flexible and powerful mathematical model for construction activities and their buffers that are characterized by their linear or repetitive nature. The steps of formulating initial equations, stacking and consolidating them, and deriving information about their criticality are described in detail. The mathematical approach of the new method allows an integrated treatment of activities regardless of the number of changes in productivity within them and does not depend on the graphical representation of the schedule.

A GA optimization model for workgroup-based repetitive scheduling (WoRSM)

Most construction repetitive scheduling methods developed so far have been based on the premise that a repetitive project is comprised of many identical production units. Recently Huang and Sun [Huang RY, Sun KS. Non-unit based planning and scheduling of repetitive construction project. J Constr Eng Manage ASCE 2006;132(6):585–97] developed a workgroup-based repetitive scheduling method that takes the view that a repetitive construction project consists of repetitive activities of workgroups. Instead of repetitive production units, workgroups with repetitive or similar activities in a repetitive project are identified and employed in the planning and scheduling. The workgroup-based approach adds more flexibility to the planning and scheduling of repetitive construction projects and enhances the effectiveness of repetitive scheduling. This work builds on previous research and develops an optimization model for workgroup-based repetitive scheduling. A genetic algorithm (GA) is employed in model formation for finding the optimal solution. A chromosome representation, as well as specification of other parameters for GA analysis, is described in the paper. A sample case study is used for model validation and demonstration. Results and findings are reported.

Efficient Repetitive Scheduling for High-Rise Construction

A new scheduling and cost optimization model for high-rise construction is presented in this paper. The model has been formulated with a unique representation of the activities that form the building's structural core, which need to be dealt with carefully to avoid scheduling errors. In addition, the model has been formulated incorporating: 1 the logical relationships within each floor and among floors of varying sizes; 2 work continuity and crew synchronization; 3 optional estimates and seasonal productivity factors; 4 prespecified deadline, work interruptions, and resource constraints; and 5 a genetic algorithms-based cost optimization that determines the combination of construction methods, number of crews, and work interruptions that meet schedule constraints. A computer prototype was then developed to demonstrate the model's usefulness on a case study high-rise project. The model is useful to both researchers and practitioners as it better suits the environment of high-rise construction, avoids scheduling errors, optimizes cost, and provides a legible presentation of resource assignments and progress data.

Compositionality of Statically Scheduled IP

Timing Closure in presence of long global wire interconnects is one of the main current issues in System-on-Chip design. One proposed solution to the Timing Closure problem is Latency-Insensitive Design (LID) [Luca Carloni, Kenneth McMillan, and Alberto Sangiovanni-Vincentelli. Theory of latency-insensitive design. IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, vol. 20(no. 9):pp. 1059–1076, 2001; Mario R. Casu and Luca Macchiarulo. A new approach to latency insensitive design. In DAC'04: Proceedings of the 41st annual conference on Design automation, pages 576–581, New York, NY, USA, 2004. ACM Press].It was noticed in [Mario R. Casu and Luca Macchiarulo. A new approach to latency insensitive design. In DAC '04: Proceedings of the 41st annual conference on Design automation, pages 576–581, New York, NY, USA, 2004. ACM Press] that, in many cases, the dynamically scheduled synchronisations introduced by latency-insensitive protocols could be computed off-line as a static periodic schedule. We showed in [Julien Boucaron, Jean-Vivien Millo, and Robert De Simone. Latency-insensitive design and central repetitive scheduling. In Formal Methods and Models for Co-Design, 2006. MEMOCODE'06. Proceedings. Fourth ACM and IEEE International Conference on, pages 175–183, Piscataway, NJ, USA, 2006. IEEE Press; Julien Boucaron, Jean-Vivien Millo, and Robert De Simone. Formal methods of scheduling for latency-insensitive designs. EURASIP journal on embedded system, 2007 (not yet published)] how this schedule could then be used to further optimize the protocol resources when they are found redundant. The purpose of the present paper is to study how the larger blocks, obtained as synchronous components interconnected by LID protocols optimized by static schedule informations, can be again made to operate with an environment that provides also I/O connections at its own (synchronous or GALS) rate.We also consider the case of multirate SoC, using results from SDF (Synchronous DataFlow) theory [Edward A. Lee and David G. Messerschmitt. Synchronous data flow. Proceeding of the IEEE, vol. 75(no. 9):pp. 1235–1245, 1987].

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.