Sustainability at Research Day 2017

SMU students are invited and encouraged to present results of ongoing and completed SMU-based research. The goal of this event is to foster communication between students in different disciplines, give students the opportunity to present their work in a professional setting, and share the outstanding research being conducted at SMU with their peers and industry professionals from the greater Dallas community. The abstracts below highlight the sustainability related research done by SMU graduate and undergraduate students in the past year.

ON-DEMAND RIDE-SHARING TAXI SERVICES FOR ENHANCED MOBILITY: PROBLEM FORMULATION AND SOLUTION METHODOLOGY

There are increasing calls to develop alternative modes of transportation to enhance mobility in congested urban areas. One emerging transportation mode with potential to achieve this goal is the on-demand rideshare taxi services (e.g., uberPOOl). Passengers can request a taxi for a trip while being willing to share the ride with other passengers along their ways in return of reduced fares. Passengers are also willing to transfer allowing their trips to be covered by multiple taxis. Optimizing the operation of this service involves solving a complex pickup and delivery vehicle routing problem with time windows constraints and transfer (PD-VRP-TW-T). The solution to this problem gives the time-dependent vehicle routes and associated passenger itineraries. This paper presents mathematical formulation and solution methodology for the PDVRP-TW-T in the context of on-demand ride-share taxi services. Preliminary results that examine the performance of the solution methodology under different operational scenarios are presented. 

RAPID SOIL CLASSIFICATION USING NEURAL NETWORKS AND STUDYING THE EFFECT OF MIX DESIGN ON CEB PERFORMANCE 

Compressed earth blocks (CEBs) represent a cost-effective, sustainable, and environmentally-friendly building alternative to traditional masonry elements. CEB construction comprises low-cement, compressed local soil brick units that are rapidly and efficiently manufactured on site. CEB construction uses local soil as the primary component, which provides advantages over traditional masonry elements including lower cost, increased energy efficiency, and lower environmental impact. One significant challenge with prolific CEB construction is the lack of standardization both in the United States and internationally. This can be largely attributed to CEB as a construction material having a relatively small knowledge base. Traditional masonry elements such as CMU and fired clay bricks are very well understood and are thus comprehensively standardized. This project seeks to help grow the CEB by studying the performance of CEB and how it is affected by different soil types and mix designs. The first step of the project was to develop a system which is capable of rapidly classifying soils based on rudimentary soil analysis tests performed in the field. The second step of the project was to perform strength testing on CEBs with varying mix designs to study the effect of mix design on block performance. 

EVALUATION OF NANOMATERIALS ON THE FLUORIDE REMOVAL IN GREEN INFRASTRUCTURE FOR STORMWATER MANAGEMENT 

As population continues to rise, urbanization grows, increasing impermeable and semipermeable surfaces. These surfaces contribute to faster flows and higher volumes of stormwater runoff that can contaminate drinking water sources. Fluoride is one of many pollutants that can be found in stormwater run off, as it is a widespread environmental contaminant. Green infrastructure (GI) has become a promising technology for the effective management of stormwater. However, there is a need for cost-effective filter materials to remove fluoride. The main objective of this study is to assess the sorptive capacity of various nanomaterials for fluoride removal. Among the thirteen types of nanomaterial evaluated in this study, ferrihydrite (Fe(OH)3), hydroxyapaite (Ca5(PO4)3OH), and brucite (Mg(OH)2) showed the highest efficiency for fluoride removal in both batch and columns tests. The results indicated that these three nanomaterials have the potential to be implemented in GI matrices for fluoride removal. <

NETWORK DESIGN FOR IN-MOTION WIRELESS CHARGING OF ELECTRIC VEHICLES IN URBAN AREAS 

We present a model to optimize the location and power capacity of in-motion electric charging stations. We formulate the problem as a MIP and we propose a Benders-decomposition-based algorithm to solve it efficiently. We present the computational results of testing the algorithm on large-scale grid networks. 

ENERGY HARVESTER 

STRESS DROP ESTIMATES FROM POSSIBLE INDUCED SEISMIC EVENTS IN THE FORT WORTH BASIN, TEXAS 

Since gas and oil production began in the Fort Worth Basin, there have been five earthquake sequences (DFW Airport, Cleburne, Azle, Dallas/Irving and Venus) associated with the Barnett shale development. These earthquake sequences are suggested to be induced by disposal of recovered wastewater by previous studies. Previous studies suggest average stress drops of 10 bars and 43 bars for DFW and Cleburne earthquakes, respectively. The aim of this study is to calculate stress drops using absolute estimation based on Brune model in the other three sequences (Azle, Dallas/Irving and Venus). To do this, path correction including attenuation and geometrical spreading are applied prior to making the source estimates. A second time domain procedure is also used to estimate the stress drop and is found to estimates slightly higher stress drops than the frequency domain estimates. This study suggests that stress drop estimates are in agreement with global average intra-plate earthquakes including previous average stress drops estimated for the Fort Worth Basin. The stress drops suggest a breakdown in self-similarity with increasing moment magnitude. However, because of the limited magnitude range of the data analyzed this conclusion need further study. 

COMMON GOODS IN UNCOMMON TIMES: WATER, DROUGHTS, AND THE SUSTAINABILITY OF ANCESTRAL PUEBLO COMMUNITIES IN THE JEMEZ MOUNTAINS, NEW MEXICO (AD 1100-1700) 

The Jemez and Pajarito Plateaus of the Jemez Mountains, New Mexico share similar cultural, environmental, and climatic contexts, yet large Ancestral Pueblo communities of the Pajarito abandoned mesa-tops for lowlands of the Rio Grande during the 16th century while occupations of the Jemez Plateau persisted until the 17th century. Droughts are hypothesized as a driver of depopulation of the Pajarito Plateau, but if so why wasn’t the Jemez abandoned as well? I conducted interdisciplinary geoarchaeological investigations to evaluate if different strategies of water management impacted community-level resilience to climate change. In this presentation I present a paleohydrological model of hydrological sensitivities to prehistoric droughts, and a region-wide analysis of how droughts may have impacted water acquisition costs. <