Events Calendar

Astani Civil and Environmental Engineering Ph.D. Seminar

Speaker: Ali Kazemian and Mohammad Motie Share , Astani CEE Graduate Students

Talk Title: A Performance-based Framework for Laboratory Testing of Cementitious Materials for Construction-Scale 3D Printing and A Vacation Queue Approach to Queue Size Computation for a Signalized Traffic Intersection

Abstract: During recent decades,construction industry has been criticized for limited use of innovative methods and slow adoption of cutting edge technologies. However,it seems that a transformation is about to happen and construction industry is getting ready for some revolutionary changes. Employing and scaling up additive manufacturing techniques for automated construction of whole buildings is a novel idea which has been topic of discussion for several years. A review of related projects and research works reveals that Portland cement concrete is the most viable option as the material to be used in automated construction processes in near future. However,the performance requirements for a cementitious printing mixture have not been clearly defined.
In this presentation,a framework for performance based laboratory testing of cementitious mixtures for construction scale 3D printing in fresh state will be discussed,in which workability of a fresh printing mixture is described in terms of print quality, shape stability, and printability window. In order to elaborate on the proposed framework and suggested test methods, an experimental program was carried out using four different mixtures. The results of several conventional test methods, as well as proposed tests, will also be presented and performance of different mixtures will be compared. Finally, ongoing research related to real-time quality monitoring of cementitious materials during the concrete 3D printing process will be discussed.

Abstract by Mohammad Motie Share

Analyzing queues of vehicles at signalized intersections reveals useful insight about the performance of arterial networks. Typically, the average evolution of these queues is studied under deterministic conditions, fixed time policies, and simplifying assumptions. We propose an approach to probabilistically characterize the dynamics of these queues by incorporating the uncertain and dynamic nature of traffic streams and intersection management policy. We consider a vacation queue model for a signalized traffic intersection to elucidate intra-cycle queue size variations. In particular, we study two one-way single-lane streets interacting at a signalized intersection. Vehicles arrive at the intersection according to two independent Poisson processes with different intensities. We approximate queues of vehicles on each intersection leg by simple queuing systems that their server becomes unavailable during red phases. Motivated by vacation queues, an embedded Markov chain corresponding to queue sizes at the end of cycles is considered, whose transition probabilities are computed from analytical transient solutions of vacation queues.

Location: Waite Phillips Hall Of Education (WPH) - B27

Audiences: Everyone Is Invited

Contact: Evangeline Reyes