A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Scalable Rapid Fabrication of Low-Cost, High-Performance, Sustainable Thermal Insulation Foam for Building Energy Efficiency(2024) Siciliano, Amanda Pia; Hu, Liangbing; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bio-based thermal insulation materials offer a promising path towards energy savings in the buildings sector. However, these materials face competitiveness challenges against conventional petroleum-based alternatives due to issues with inferior insulation performance, poor compressive strength, and limited manufacturing scalability. Various fabrication methods such as freeze drying, thermal bonding, and chemical treatment have been proposed to enhance the material’s internal structure by introducing additional pores, creating a more complex path for heat transfer, and improving insulation efficiency. Despite advancements, the manufacturing scalability of these methods and their integration into industrial production remain unachieved.This thesis aims to bridge the gap between laboratory experiments and large-scale production by developing low-cost, sustainable cellulose-based thermal insulation. By investigating both aqueous and non-aqueous-based processing strategies, this work proposes several different fabrication techniques, leading to significant savings in energy, time, and cost. Establishing a comprehensive understanding of the interactions among the fabrication process, insulation foam, manufacturing scalability, and intended product application is imperative. This understanding accounts for variations in processing parameters (e.g., pretreatments, binders, temperature, time) and their impact on the insulation foam’s internal structure and overall performance. By examining the relationship between processing parameters and material structure, this thesis not only advances the fundamental understanding necessary for optimizing fabrication but also provides strategic guidance for selecting and designing scalable bio-based thermal insulation foams. Studying and characterizing commercially viable methods that seamlessly integrate with current industrial infrastructures is crucial for facilitating the transition from small-scale laboratory experimentation to large-scale industrial production. Through various technical strategies, this work illustrates how our understanding can be utilized to offer direction for fabrication method selection, design, and processing, ultimately optimizing the scalable rapid fabrication of low-cost, high-performance sustainable thermal insulation materials for building energy efficiency.Item MECHANICS AND THERMAL TRANSPORT MODELING IN NANOCELLULOSE AND CELLULOSE-BASED MATERIALS(2023) RAY, UPAMANYU; Li, Teng; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cellulose, the abundantly available natural biopolymer, has the potential to be a next generation wonder material. The motivation behind this thesis stems from the efforts to obtain mechanical properties of two novel cellulose-based materials, which were fabricated using top-down (densified engineered wood) and bottoms-up (graphite-cellulose composite) approaches. It was observed that the mechanical properties of both the engineered wood (strength~596 MPa; toughness ~3.9 MJ/m3) and cellulose-graphite composite (strength~715 MPa; toughness ~27.7 MJ/m3) surpassed the equivalent features of other conventional structural materials (e.g., stainless steel, Al alloys etc.). However, these appealing properties are still considerably inferior to individual cellulose fibrils whose diameters are in the order of nanometers. A significant research effort needs to be initiated to effectively transfer the mechanical properties of the hierarchical cellulose fibers from the atomistic level to the continuum. To achieve that, a detailed understanding of the interplay of cellulose molecular chains that affects the properties of the bulk cellulosic material, is needed. Modeling investigations can shed light on such underlying mechanisms that ultimately dictate multiple properties (e.g., mechanics, thermal transport) of these cellulosic materials. To that end, this thesis (1) applies molecular dynamics simulations to decipher why microfibers made of aligned nanocellulose and carbon nanotubes possess excellent mechanical strength, along with understanding the role of water in fully recovering elastic wood under compression; (2) delineates an atomistically informed multi-scale, scalable, coarse grained (CG) modeling scheme to study the effect of cellulose fibers under different representative loads (shearing and opening), and to demonstrate a qualitative guideline for cellulose nanopaper design by understanding its failure mechanism; (3) utilizes the developed multi-scale CG scheme to illustrate the reason why a hybrid biodegradable straw, experimentally fabricated using both nano- and micro-fibers, exhibits higher mechanical strength than individual straws that were built using only nano or microfibers; (4) investigates the individual role of nanocellulose and boron nitride nanotubes in increasing the mechanical properties (tensile strength, stiffness) of the derived nanocellulose/boron-nitride nanotube hybrid material; (5) employs reverse molecular dynamics approach to explore how the boron nitride nanotube based fillers can improve thermal conductivity (k) of a nanocellulose derived material. In addition, this thesis also intends to educate the readers on two perspectives. The common link connecting them is the method of engineering intermolecular bonds. The first discussion presents a few novel mechanical design strategies to fabricate high-performance, cellulose-based functional materials. All these strategies are categorized under a few broad themes (interface engineering, topology engineering, structural engineering etc.). Another discussion has been included by branching out to other materials that, like nanocellulose, can also be tuned by intermolecular bonds engineering to achieve unique applications. Avenues for future work have been suggested which, hopefully, can act as a knowledge base for future researchers and help them formulate their own research ideas. This thesis extends the fundamental knowledge of nanocellulose-based polymer sciences and aims to facilitate the design of sustainable and programmable nanomaterials.Item Development of Risk-Based Measurements and Metrics for Sustainability Quantification of Manufactured and Constructed Systems(2018) Webb, David Harry; Ayyub, Bilal M; Reliability Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Sustainability has been an important topic of study for several decades; however, its importance has escalated with the signing of the Paris Agreement. One issue that has always hindered implementing sustainability research in practice has been the difficulty in measuring performance. While methods such as life-cycle assessment are available to enable a comparison with alternatives, sustainable performance cannot be related to larger environmental goals. Additionally, such methods often omit uncertainty considerations. The proposed research herein provides foundational measurement science and metrics to bridge the gap between the theories of sustainability and the application. The metrics enable tracking of measurable progress in all aspects of sustainability within a risk-based framework. This dissertation opens by reviewing and analyzing the literature on sustainability definitions and existing metrics in order to determine the current state of the practice, and to inform the development of the proposed metrics. Next, in order to demonstrate the capacity of risk-based approaches in measuring sustainability performance, a methodology is proposed to calculate the probability of a structure or product meeting sustainability requirements. Last, the methodology is validated using the National Institute of Standards and Technology’s Building Industry Reporting and Design for Sustainability. The validation procedure demonstrated that the methodology was capable of reproducing results from a well-vetted database. The proposed methodology serves as the first step in a “sustainability reliability” metric that is practical, accurate and comprehensive in its coverage.Item SIMULATION AND ANALYSIS OF ENERGY CONSUMPTION FOR TWO COMPLEX AND ENERGY-INTENSIVE BUILDINGS ON UMD CAMPUS(2017) Savage, Dana Mason; Ohadi, Michael M; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Microbiology Building and Hornbake Library are two multi-purpose and complex buildings, and are among the highest energy-intensive buildings on the University of Maryland College Park Campus. This thesis details the energy analysis and energy consumption models developed to identify energy savings opportunities for these two buildings. Three reports are given per building: one – a comprehensive summarization of relevant building information; two – a utility analysis, including an energy benchmarking study, evaluating the relative performance of each facility; three – a detailed energy model to replicate current operation and simulate potential energy savings resulting from no-and-low cost energy conservation measures. In total, 11 of the 12 measures simulated are strongly recommended for implementation. The predicted combined energy and utility savings are respectively 18,648.4 MMBtu and $436,128 annually. These actionable proposals to substantially reduce the buildings’ energy consumption contribute to the University’s commitment to achieve greater energy efficiency throughout campus.Item Planning for Integration of Wind Power Capacity in Power Generation Using Stochastic Optimization(2013) Aliari Kardehdeh, Yashar; Haghani, Ali; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The demand for energy is constantly rising in the world while most of the conventional sources of energy are getting more scarce and expensive. Additionally, environmental issues such as dealing with excessive greenhouse gas emissions (especially CO2) impose further constraints on energy industry all over the globe. Therefore, there is an increasing need for the energy sector to raise the share of clean and renewable sources of energy in power generation. Wind power has specifically attracted large scale investment in recent years since it is ample, widely distributed and has minimal environmental impact. Wind flow and consequently wind-generated power have a stochastic nature. Therefore, wind power should be used in combination with more reliable and fuel-based power generation methods. As a result, it is important to investigate how much capacity from each source of energy should be installed in order to meet electricity demand at the desired reliability level while considering cost and environmental implications. For this purpose, a probabilistic optimization model is proposed where demand and wind power generation are both assumed stochastic. The stochastic model uses a combination of recourse and chance-constrained approaches and is capable of assigning optimal production levels for different sources of energy while considering the possibility of importation, exportation and storage of electricity in the network.Item SUSTAINABLE INFRASTRUCTURE MODELING AND POLICY ANALYSES: CONSTRUCTION, ENERGY AND TRANSPORTATION INDUSTRIES(2013) Avetisyan, Hakob; Gabriel, Steven A.; Miller-Hooks, Elise D.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Sustainable infrastructure operation assumes consideration of interrelated elements and problems within interacting industries in which the decisions made for one industry may affect those in interrelated industries. Problems related to global climate change and resource scarcity are main concerns for a society trying to build a sustainable infrastructure. These problems are targeted from many perspectives, including government-enforced policies and regulations that call for energy efficiency and transportation efficiency to build a sustainable infrastructure. There is a growing interest among engineers in accounting for sustainability under the impact of climate change policies that limit the amount of pollutants being released from projects and facilities. While specific problems can be targeted by specialists in each industry or field, an optimal sustainable solution will be very difficult to find if considered separately. Despite that directions for improvement are defined, the methods and techniques for reaching these specified goals are not yet well developed. Decision-makers do not have the necessary models to evaluate the impact of proposed carbon policies supporting sustainable infrastructure development. Yet, it is important to analyze the problem in a systematic fashion to find cost-efficient, technically well-designed and constructed and sustainable solutions. In this dissertation, an interdisciplinary approach is used with the aim of analyzing programs geared at reducing emissions and costs, and determining optimal allocation of resources along with profit maximization by developing and employing optimization, regression and game-theoretic models for the construction, energy and transportation industries. These models can be used by national, state, local and private agencies for assessing carbon-mitigation policies and low-cost carbon policy developments. Concepts from integer programming, multi-objective decision-making, bi-level programming, simulation and regression are employed in the development of models to support informed decision-making and policy analyses in the construction, transportation and energy sectors. The models incorporate industry-specific details covering engineering, economic and environmental aspects of sustainable practices. The application of these models to real-world case studies provides insights that will allow defined specific goals to be achieved in a cost-efficient way. Results of case studies were optimal and most importantly not intuitive.Item GOVERNANCE STRATEGIES FOR ENTERPRISE APPLICATION SYSTEM IMPLEMENTATIONS(2013) Ghosh, Saumyendu N.; Skibniewski, Miroslaw J; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Enterprise application system implementations are highly complex implementations that automate several business functions, such as financials, accounting, supply chain, customer services management, human resources management and reporting among others. This study aims at providing an alternative view of organization's enterprise application system (EAS) acceptance. Despite the large body of literature, there are still empirical inquiries to investigate the EAS system implementation from adopters' perspectives and how to identify risks in a multi-stakeholder and dynamic environment. The thesis consists of three essays on various aspects of relationship between enterprise application implementation in a multi-stakeholder environment and project governance. Valid measurement scales for predicting organization's acceptance of enterprise systems are in short supply. The first essay develops and validates new scales for two specific variables, integration and inter-dependency risks. These variables are hypothesized as key determinant for organizational success of enterprise application implementations by mitigating risks involved in a multi-stakeholder environment. A model of organization acceptance of enterprise systems was developed using these two scales and then tested for reliability from a total of 365 users and nine application groups. The measures were validated using ten different direct measures with reliabilities between 0.72 and 0.96. Integration risk was significantly related with perceived ease of use, consultant's product knowledge and training provided to the end users. Inter-dependency risk was significantly correlated with perceived usefulness, consultant's industry and product knowledge. Both integration and inter-dependency risks are significantly related with success of the new enterprise application. This study would benefit project executives by offering valuable managerial insights that enable them to appreciate and improve integration and inter-dependency of stakeholders. Implications for theory and practice are discussed for two sub-groups: that less experienced resources treat risks differently than more experienced resources, and business applications compared to technical enterprise applications. Academic community has not addressed governance of enterprise application projects that involve dynamic environments and how to mitigate integration and inter-dependency risks. In the second essay it is argued that acceptance of the system from end users is not enough? Adopters of new enterprise wide information technology solutions get most benefit when the solution continues to be adaptable when business, environment or other organizational priorities change - therefore making an implementation sustainable. The second essay discussed characteristics of sustainability of enterprise application implementation from organizational perspective. A case study was used to validate the characteristics of sustainability. The thesis sought to demonstrate the causal relationship between the organization's preparedness for sustainability and the emergence of implementation problems. The study extracted insight into the criticality of certain factors and the type of problems making decisions under weak governance situation. The third essay develops determinants for project governance success of enterprise application implementations by mitigating risks in a multi-stakeholder environment. This essay develops and validates new scales for five specific variables. Definitions of five variables were used to develop a model that was presented for content validity and then tested for reliability from a total of 117 project executives globally. The measures were validated with reliabilities between 0.73 and 0.94. Relationships between five measures were broken down to meaningful components and a three tier project governance structure was proposed to mitigate integration and inter-dependency risks in a multi-stakeholder environment.Item ENVRIZ: A Methodology for Resolving Conflicts between Product Functionality and Environmental Impact(2011) Fitzgerald, Daniel Patrick; Herrmann, Jeffrey; Schmidt, Linda; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Product development organizations are facing more pressure now than ever before to become sustainable. However, organizations are reluctant to compromise product functionality in order to create products that have less environmental impact than that required by regulations. Thus, engineers may face a conflict between improving product functionality and reducing environmental impact. The design for environment (DfE) tools currently available are inadequate with respect to helping engineers determine how to resolve this conflict during the conceptual design phase. The Theory of Inventive Problem Solving (TRIZ) which is based on Design by Analogy provides a promising conceptual design approach for this problem. Examples of products that simultaneously reduce environmental impact and improve product functionality can inspire engineers to do likewise. This research consists of 1.) Finding products and patents that overcome a contradiction between product functionality and environmental impact; 2.) Analyzing and determining the functionality parameter, environmental parameter, and TRIZ principle demonstrated by each example; 3.) Organizing this knowledge into an accessible DfE tool (matrices); and 4.) Developing a methodology for using the tool. The combination of the tool and methodology is named ENVRIZ, a merge of environment and TRIZ. After ENVRIZ was complete, an effectiveness study was completed to understand whether the new tool provided better solutions than TRIZ. Results of the study support that utilizing specific product examples from ENVRIZ provides better solutions compared to utilizing engineering principles from either ENVRIZ and TRIZ. Although the use of the tool on its own does not guarantee a reduction in a product's overall sustainability, the ENVRIZ methodology provides design engineers with a useful conceptual design tool to help overcome contradictions between improving product functionality and reducing environmental impact. Moreover, despite the limited number of examples identified to date, this research provides a framework and prototype that can be extended to incorporate new solutions to these contradictions.Item Modeling Vehicle Ownership Decisions in Maryland: A Preliminary Stated Preference Survey and Model(2010) Maness, Michael; Cirillo, Cinzia; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the near future, the culmination of new vehicle technologies, greater competition in the energy markets, and government policies to fight pollution and reduce energy consumption will result in changes in the United States' vehicle marketplace. This project proposes to create a stated preference (SP) survey along with discrete choice models to predict future demand for electric, hybrid, alternative fuel, and gasoline vehicles. The survey is divided into three parts: socioeconomics, revealed preference (RP), and SP sections. The socioeconomics portion asks respondents about themselves and their households. The RP portion asks about household's current vehicles. The SP section presents respondents with various hypothetical scenarios over a future five-year period using one of three game designs. The designs correspond to: changing vehicle technology, fuel pricing and availability, and taxation policy. With these changes to the vehicle marketplace, respondents are asked whether they will keep or replace their current vehicles and if he will purchase a new vehicle and its type. To facilitate the design and administering of the survey, a web survey framework, JULIE, was created specifically for creating stated preference surveys. A preliminary trial of the survey was conducted in September and October 2010 with a sample size of 141 respondents. Using the SP results from this preliminary trial, a multinomial logit model is used to estimate future vehicle ownership by vehicle type. The models show that the survey design allows for estimation of important parameters in vehicle choice.