Julio C. Martinez

General purpose simulation with stroboscope

Stroboscope is a programming language designed for the simulation of processes common to construction engineering. These processes are very complex and involve many different types of resources. As a result, Stroboscope is also an efficient and effective general purpose simulation system. The paper presents an overview of Stroboscope and illustrates how it can be used to model a complex example taken from classic simulation literature.

Methodology for Conducting Discrete-Event Simulation Studies in Construction Engineering and Management

This paper suggests the methodology to follow when conducting discrete-event simulation (DES) studies in construction engineering and management research. Emphasis is made on the steps that, due to the uniqueness of the construction environment, are particularly important yet are not discussed extensively in the general DES literature. Guidelines are provided to determine what aspects of a DES study demand a rigorous application of the theory depending on the purpose of the study. The paper concludes with the importance of properly understanding the probabilistic concepts upon which DES relies and on coupling this understanding with engineering judgment as a key for successful use of DES in construction research.

Validating complex construction simulation models using 3D visualization

One of primary impediments in the use of discrete-event simulation to plan and design construction operations is that decision-makers often do not have the means, the knowledge, and/or the time to check the veracity and the validity of simulation models and thus have little confidence in the results. Visualizing simulated operations in 3D can be of substantial help in the verification, validation, and accreditation of simulation models. In addition, visualization can provide valuable insight into subtleties of modeled operations that are otherwise non-quantifiable and presentable. This paper investigates the efficacy of 3D visualization in verifying and validating discrete-event construction simulation models. The paper presents a case study of a simulation model of an earthmoving operation with fairly complex control logic that was verified and validated by visualizing the operation in 3D. The simulation model for the example was developed using Stroboscope and was visualized using the Dynamic Construction Visualizer.

Earthmover-simulation tool for earthwork planning

The paper presents EarthMover, a discrete event special purpose simulation modeling tool for earthwork planning, geared towards practitioners. The paper explores the capabilities of the system by modeling an earth moving operation of moderate complexity. The operation is initially modeled with default parameters and is sucessively improved based on insights obtained from the static and dynamic outputs of the previous model. The paper also describes the tools and techniques that were used to develop the simulator.

Sustainability analysis of earthmoving operations

Emissions from construction equipment are the main contributor of environmental impacts from construction processes, and mitigating these impacts is an important aspect of operations design and planning. To this end, emission estimation models play an important role in environmental management of construction operations. This paper presents an emission model that integrates with discrete-event simulation (DES) for more accurate emission estimates from construction operations compared to existing models. The paper also presents a case study which analyzes sustainability of an earthmoving operation, to demonstrate the application of DES for estimating emissions.

SCENE GRAPH AND FRAME UPDATE ALGORITHMS FOR SMOOTH AND SCALABLE 3D VISUALIZATION OF SIMULATED CONSTRUCTION OPERATIONS

One of the prime reasons inhibiting the widespread use of discrete-event simulation in construction planning is the absence of appropriate visual communication tools. Visualizing modeled operations in 3D is arguably the best form of communicating the logic and the inner working of simulation models and can be of immense help in establishing the credibility of analyses. New software development technologies emerge at incredible rates that allow engineers and scientists to create novel, domain-specific applications. The authors capitalized on a computer graphics technology based on the concept of the scene graph to design and implement a general-purpose 3D visualization system that is simulation and CAD-software independent. This system, the Dynamic Construction Visualizer, enables realistic visualization of modeled construction operations and the resulting products and can be used in conjunction with a wide variety of simulation tools. This paper describes the scene graph architecture and the frame updating algorithms used in designing the Dynamic Construction Visualizer.

Scalable simulation models for construction operations

Construction operations are often repetitive not only in terms of time (the same tasks are performed over and over) but also in terms of space (the same tasks are repeated at several places, such as different floors in a high-rise building). Thus, construction simulation models in general must be cyclic to represent temporal repetitions, but also scaleable to represent spatial repetitions. This paper presents the mechanisms for preprocessor replacement and automatic code generation that have been designed and implemented to facilitate the development of scaleable simulation models in STROBOSCOPE, a general-purpose discrete-event simulation system developed by the authors. A relatively complex simulation model for the vertical transportation of people serves as an example to illustrate how to develop a completely scaleable model for the operation of an elevator in a building with any number of floors.

Simulation of complex construction processes

Eight successively refined simulation models for the earthmoving operations involved in the construction of a dam provide the foundation for illustrating the ease and effectiveness of modeling complex construction processes by using STROBOSCOPE, a modern simulation system based on a programming language that follows the activity-scanning paradigm. This approach and the use of characterized resources in a stochastic environment make the typical engineering calculations for heavy equipment performance relatively easy to implement and significantly more realistic and accurate.

Discrete-Event Simulation-Based Virtual Reality Environments for Construction Operations: Technology Introduction

The next logical evolution of discrete-event simulation (DES) technology for construction is for simulations and animations to run concurrently and in a manner that allows interaction with the animation to affect the course of events in the simulation. This effectively enables the creation of virtual environments with logic based on DES models, something that recent research efforts have made possible. This paper introduces this technology with the help of a case study. In particular, the paper presents how interactivity can improve the process of model validation in simulation studies, which is a critical step in achieving model credibility. Via a complex earthmoving operation, a construction engineer can use real-time interactivity to create situations of interest and study the model’s response to those, and thus validate that the response is appropriate. These capabilities can significantly enhance the process of model validation, thereby adding to the value of DES for practical use in operations plann...

Enabling smooth and scalable dynamic 3D visualization of discrete-event construction simulations

Visualizing simulated construction operations is an effective means of communicating the logic and the inner working of simulation models in a comprehensive and comprehendible manner. This can facilitate both model verification and validation and help establish credibility of simulation analyses. Due to the inherent working nature of discrete-event simulation systems, visualizing simulated operations in a smooth and continuous manner in 3D virtual worlds presents numerous interesting challenges. This paper describes research being conducted at Virginia Tech to enable smooth and scalable dynamic 3D visualization of discrete-event construction simulations.