ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Displaying 21 - 30 of 97
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- Creators: Mobasher, Barzin
Description
Concrete design has recently seen a shift in focus from prescriptive specifications to performance based specifications with increasing demands for sustainable products. Fiber reinforced composites (FRC) provides unique properties to a material that is very weak under tensile loads. The addition of fibers to a concrete mix provides additional ductility and reduces the propagation of cracks in the concrete structure. It is the fibers that bridge the crack and dissipate the incurred strain energy in the form of a fiber-pullout mechanism. The addition of fibers plays an important role in tunnel lining systems and in reducing shrinkage cracking in high performance concretes. The interest in most design situations is the load where cracking first takes place. Typically the post crack response will exhibit either a load bearing increase as deflection continues, or a load bearing decrease as deflection continues. These behaviors are referred to as strain hardening and strain softening respectively. A strain softening or hardening response is used to model the behavior of different types of fiber reinforced concrete and simulate the experimental flexural response. Closed form equations for moment-curvature response of rectangular beams under four and three point loading in conjunction with crack localization rules are utilized. As a result, the stress distribution that considers a shifting neutral axis can be simulated which provides a more accurate representation of the residual strength of the fiber cement composites. The use of typical residual strength parameters by standards organizations ASTM, JCI and RILEM are examined to be incorrect in their linear elastic assumption of FRC behavior. Finite element models were implemented to study the effects and simulate the load defection response of fiber reinforced shotcrete round discrete panels (RDP's) tested in accordance with ASTM C-1550. The back-calculated material properties from the flexural tests were used as a basis for the FEM material models. Further development of FEM beams were also used to provide additional comparisons in residual strengths of early age samples. A correlation between the RDP and flexural beam test was generated based a relationship between normalized toughness with respect to the newly generated crack surfaces. A set of design equations are proposed using a residual strength correction factor generated by the model and produce the design moment based on specified concrete slab geometry.
ContributorsBarsby, Christopher (Author) / Mobasher, Barzin (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2011
Description
Ultra-concealable multi-threat body armor used by law-enforcement is a multi-purpose armor that protects against attacks from knife, spikes, and small caliber rounds. The design of this type of armor involves fiber-resin composite materials that are flexible, light, are not unduly affected by environmental conditions, and perform as required. The National Institute of Justice (NIJ) characterizes this type of armor as low-level protection armor. NIJ also specifies the geometry of the knife and spike as well as the strike energy levels required for this level of protection. The biggest challenges are to design a thin, lightweight and ultra-concealable armor that can be worn under street clothes. In this study, several fundamental tasks involved in the design of such armor are addressed. First, the roles of design of experiments and regression analysis in experimental testing and finite element analysis are presented. Second, off-the-shelf materials available from international material manufacturers are characterized via laboratory experiments. Third, the calibration process required for a constitutive model is explained through the use of experimental data and computer software. Various material models in LS-DYNA for use in the finite element model are discussed. Numerical results are generated via finite element simulations and are compared against experimental data thus establishing the foundation for optimizing the design.
ContributorsVokshi, Erblina (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2012
Description
Increased priority on the minimization of environmental impacts of conventional construction materials in recent years has motivated increased use of waste materials or bi-products such as fly ash, blast furnace slag with a view to reduce or eliminate the manufacturing/consumption of ordinary portland cement (OPC) which accounts for approximately 5-7% of global carbon dioxide emission. The current study explores, for the first time, the possibility of carbonating waste metallic iron powder to develop carbon-negative sustainable binder systems for concrete. The fundamental premise of this work is that metallic iron will react with aqueous CO2 under controlled conditions to form complex iron carbonates which have binding capabilities. The compressive and flexural strengths of the chosen iron-based binder systems increase with carbonation duration and the specimens carbonated for 4 days exhibit mechanical properties that are comparable to those of companion ordinary portland cement systems. The optimal mixture proportion and carbonation regime for this non-conventional sustainable binder is established based on the study of carbonation efficiency of a series of mixtures using thermogravimetric analysis. The pore- and micro-structural features of this novel binding material are also evaluated. The fracture response of this novel binder is evaluated using strain energy release rate and measurement of fracture process zone using digital image correlation (DIC). The iron-based binder system exhibits significantly higher strain energy release rates when compared to those of the OPC systems in both the unreinforced and glass fiber reinforced states. The iron-based binder also exhibits higher amount of area of fracture process zone due to its ability to undergo inelastic deformation facilitated by unreacted metallic iron particle inclusions in the microstructure that helps crack bridging /deflection. The intrinsic nano-mechanical properties of carbonate reaction product are explored using statistical nanoindentation technique coupled with a stochastic deconvolution algorithm. Effect of exposure to high temperature (up to 800°C) is also studied. Iron-based binder shows significantly higher residual flexural strength after exposure to high temperatures. Results of this comprehensive study establish the viability of this binder type for concrete as an environment-friendly and economical alternative to OPC.
ContributorsDas, Sumanta (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, S.D. (Committee member) / Mobasher, Barzin (Committee member) / Marzke, Robert (Committee member) / Chawla, Nikhilesh (Committee member) / Stone, David (Committee member) / Arizona State University (Publisher)
Created2015
Description
Health is among the most basic needs of the people and driving force of social and economic development. The health nutrition & wellness industry is gradually becoming a global sunrise industry . However, the industry is faced many problems and challenges including weaknesses in the industry structure, fragmentations of supply chain, low
efficiency in resources allocation, and lacking in quality on personnel training. To achieve core competitiveness and value creation, it is important that the health nutrition & wellness industry must meet the needs of Chinese market and its customers with a customer centric perspective to design a firm’s organization strucrture and management processes. This thesis is based on an analysis of the competitive landscape faced by the nutrition & wellness industry as exemplified by By-Health.Ltd. The investigation begins with an analysis and synthsis of the common industry practices on sales & distribution channels for their underlying similarities and differences in product strategies, branding strategies, and agency models on incentive design and profit sharing mechanisms. Through an empirical survey, this thesis also investigate customer’s demand for nutritious and healthy products. The results through factor analysis reveal that such demands are driven by individual factor, product factor, enterprise factor and environmental factor. The study concludes with a proposed framework to link customer value through three innovative designs in sales and distribution: community marketing model, sharing marketing model and Internet factory marketing model.
efficiency in resources allocation, and lacking in quality on personnel training. To achieve core competitiveness and value creation, it is important that the health nutrition & wellness industry must meet the needs of Chinese market and its customers with a customer centric perspective to design a firm’s organization strucrture and management processes. This thesis is based on an analysis of the competitive landscape faced by the nutrition & wellness industry as exemplified by By-Health.Ltd. The investigation begins with an analysis and synthsis of the common industry practices on sales & distribution channels for their underlying similarities and differences in product strategies, branding strategies, and agency models on incentive design and profit sharing mechanisms. Through an empirical survey, this thesis also investigate customer’s demand for nutritious and healthy products. The results through factor analysis reveal that such demands are driven by individual factor, product factor, enterprise factor and environmental factor. The study concludes with a proposed framework to link customer value through three innovative designs in sales and distribution: community marketing model, sharing marketing model and Internet factory marketing model.
ContributorsGong, Binghui (Author) / Pei, Ker-Wei (Thesis advisor) / Cui, Haitao (Thesis advisor) / Gu, Bin (Committee member) / Arizona State University (Publisher)
Created2018
Description
Concrete is relatively brittle, and its tensile strength is typically only about one-tenth of its compressive strength. Regular concrete is therefore normally uses reinforcement steel bars to increase the tensile strength. It is becoming increasingly popular to use random distributed fibers as reinforcement and polymeric fibers is once such kind. In the case of polymeric fibers, due to hydrophobicity and lack of any chemical bond between the fiber and matrix, the weak interface zone limits the ability of the fibers to effectively carry the load that is on the matrix phase. Depending on the fiber’s surface asperity, shape, chemical nature, and mechanical bond characteristic of the load transfer between matrix and fiber can be altered so that the final composite can be improved. These modifications can be carried out by means of thermal treatment, mechanical surface modifications, or chemical changes The objective of this study is to measure and document the effect of gamma ray irradiation on the mechanical properties of macro polymeric fibers. The objective is to determine the mechanical properties of macro-synthetic fibers and develop guidelines for treatment and characterization that allow for potential positive changes due to exposure to irradiation. Fibers are exposed to various levels of ionizing radiation and the tensile, interface and performance in a mortar matrix are documented. Uniaxial tensile tests were performed on irradiated fibers to study fiber strength and failure pattern. SEM tests were carried out in order to study the surface characteristic and effect of different radiation dose on polymeric fiber. The interaction of the irradiated fiber with the cement composite was studied by a series of quasi-static pullout test for a specific embedded length. As a final task, flexural tests were carried out for different irradiated fibers to sum up the investigation. An average increase of 13% in the stiffness of the fiber was observed for 5 kGy of radiation. Flexural tests showed an average increase of 181% in the Req3 value and 102 % in the toughness of the sample was observed for 5 kGy of dose.
ContributorsTiwari, Sanchay Sushil (Author) / Mobasher, Barzin (Thesis advisor) / Neithalath, Narayanan (Thesis advisor) / Dharmarajan, Subramaniam (Committee member) / Holbert, Keith E. (Committee member) / Arizona State University (Publisher)
Created2018
Description
This research summarizes the validation testing completed for the material model MAT213, currently implemented in the LS-DYNA finite element program. Testing was carried out using a carbon fiber composite material, T800-F3900. Stacked-ply tension and compression tests were performed for open-hole and full coupons. Comparisons of experimental and simulation results showed a good agreement between the two for metrics including, stress-strain response and displacements. Strains and displacements in the direction of loading were better predicted by the simulations than for that of the transverse direction.
Double cantilever beam and end notched flexure tests were performed experimentally and through simulations to determine the delamination properties of the material at the interlaminar layers. Experimental results gave the mode I critical energy release rate as having a range of 2.18 – 3.26 psi-in and the mode II critical energy release rate as 10.50 psi-in, both for the pre-cracked condition. Simulations were performed to calibrate other cohesive zone parameters required for modeling.
Samples of tested T800/F3900 coupons were processed and examined with scanning electron microscopy to determine and understand the underlying structure of the material. Tested coupons revealed damage and failure occurring at the micro scale for the composite material.
Double cantilever beam and end notched flexure tests were performed experimentally and through simulations to determine the delamination properties of the material at the interlaminar layers. Experimental results gave the mode I critical energy release rate as having a range of 2.18 – 3.26 psi-in and the mode II critical energy release rate as 10.50 psi-in, both for the pre-cracked condition. Simulations were performed to calibrate other cohesive zone parameters required for modeling.
Samples of tested T800/F3900 coupons were processed and examined with scanning electron microscopy to determine and understand the underlying structure of the material. Tested coupons revealed damage and failure occurring at the micro scale for the composite material.
ContributorsHolt, Nathan T (Author) / Rajan, Subramaniam D. (Thesis advisor) / Mobasher, Barzin (Committee member) / Hoover, Christian (Committee member) / Arizona State University (Publisher)
Created2018
Description随着社会经济发展，人们生活水平提高，红木市场不断发展壮大。但红木市场中存在
原材料无法认证、加工工艺无法辨别、产品价格混乱的现象，成为我国红木市场三大痛
点。能否解决红木市场这三大痛点，成为未来红木行业能否健康顺利发展的关键因素。
针对红木行业存在的问题，本文应用市场交易效率理论、信息不对称理论、金融市场
微观结构理论对红木市场做理论梳理，通过实地调研获取红木企业发展现状、厘清传统红
木交易流程和各交易环节中存在的问题，尝试在信息不对称理论的框架下对行业和典型企
业进行分析，将红木市场的交易要素进行序列梳理，重构市场组织和流程再造，创造性地
利用现代的互联网技术，把涉及的非标准的市场要素进行标准化设计，使其成为可交易的
标准化标的产品，并在设计可操作性的红木交易平台上进行交易，从而解决现有红木市场
中信息不对称导致的市场交易效率低下问题。本文一共分为十一章，第一到第五章为绪论、理论研究和研究综述。主要根据市场交
易效率理论、信息不对称理论和金融市场微观结构理论，引出建立红木交易市场，从而为
后续红木交易市场的设计奠定理论基础。第五章，对红木产业及其市场的要素进行信息解
析，为后面的非标准的市场要素进行标准化设计提供依据。第六、第七章，主要对红木交
易市场的信息不对称现状、红木交易市场交易效率进行分析。第八、第九章，主要基于信
息对称条件下的交易要素标准化设计和交易架构设计。第十章，主要通过对实际数据抓
取，对红木交易平台的有效性进行实证对比验证。第十一章是本文的结论和建议。
由于红木交易平台的设计是弥补大宗交易的空白，特别是红木交易市场要素的非标
准化，给标准化交易架构的设计带来一定难度。红木交易平台未来运营与发展中可能会遇
到很多风险，特别是投资者资格认证、交易涉众等社会问题，本文限于篇幅没有进行研
究，留待今后实践中不断总结和修正。
原材料无法认证、加工工艺无法辨别、产品价格混乱的现象，成为我国红木市场三大痛
点。能否解决红木市场这三大痛点，成为未来红木行业能否健康顺利发展的关键因素。
针对红木行业存在的问题，本文应用市场交易效率理论、信息不对称理论、金融市场
微观结构理论对红木市场做理论梳理，通过实地调研获取红木企业发展现状、厘清传统红
木交易流程和各交易环节中存在的问题，尝试在信息不对称理论的框架下对行业和典型企
业进行分析，将红木市场的交易要素进行序列梳理，重构市场组织和流程再造，创造性地
利用现代的互联网技术，把涉及的非标准的市场要素进行标准化设计，使其成为可交易的
标准化标的产品，并在设计可操作性的红木交易平台上进行交易，从而解决现有红木市场
中信息不对称导致的市场交易效率低下问题。本文一共分为十一章，第一到第五章为绪论、理论研究和研究综述。主要根据市场交
易效率理论、信息不对称理论和金融市场微观结构理论，引出建立红木交易市场，从而为
后续红木交易市场的设计奠定理论基础。第五章，对红木产业及其市场的要素进行信息解
析，为后面的非标准的市场要素进行标准化设计提供依据。第六、第七章，主要对红木交
易市场的信息不对称现状、红木交易市场交易效率进行分析。第八、第九章，主要基于信
息对称条件下的交易要素标准化设计和交易架构设计。第十章，主要通过对实际数据抓
取，对红木交易平台的有效性进行实证对比验证。第十一章是本文的结论和建议。
由于红木交易平台的设计是弥补大宗交易的空白，特别是红木交易市场要素的非标
准化，给标准化交易架构的设计带来一定难度。红木交易平台未来运营与发展中可能会遇
到很多风险，特别是投资者资格认证、交易涉众等社会问题，本文限于篇幅没有进行研
究，留待今后实践中不断总结和修正。
ContributorsChiu, Yung (Author) / Pei, Ker-Wei (Thesis advisor) / Qian, Jun (Thesis advisor) / Wu, Fei (Committee member) / Arizona State University (Publisher)
Created2018
Description
Being a remarkably versatile and inexpensive building material, concrete has found tremendous use in development of modern infrastructure and is the most widely used material in the world. Extensive research in the field of concrete has led to the development of a wide array of concretes with applications ranging from building of skyscrapers to paving of highways. These varied applications require special cementitious composites which can satisfy the demand for enhanced functionalities such as high strength, high durability and improved thermal characteristics among others.
The current study focuses on the fundamental understanding of such functional composites, from their microstructural design to macro-scale application. More specifically, this study investigates three different categories of functional cementitious composites. First, it discusses the differences between cementitious systems containing interground and blended limestone with and without alumina. The interground systems are found to outperform the blended systems due to differential grinding of limestone. A novel approach to deduce the particle size distribution of limestone and cement in the interground systems is proposed. Secondly, the study delves into the realm of ultra-high performance concrete, a novel material which possesses extremely high compressive-, tensile- and flexural-strength and service life as compared to regular concrete. The study presents a novel first principles-based paradigm to design economical ultra-high performance concretes using locally available materials. In the final part, the study addresses the thermal benefits of a novel type of concrete containing phase change materials. A software package was designed to perform numerical simulations to analyze temperature profiles and thermal stresses in concrete structures containing PCMs.
The design of these materials is accompanied by material characterization of cementitious binders. This has been accomplished using techniques that involve measurement of heat evolution (isothermal calorimetry), determination and quantification of reaction products (thermo-gravimetric analysis, x-ray diffraction, micro-indentation, scanning electron microscopy, energy-dispersive x-ray spectroscopy) and evaluation of pore-size distribution (mercury intrusion porosimetry). In addition, macro-scale testing has been carried out to determine compression, flexure and durability response. Numerical simulations have been carried out to understand hydration of cementitious composites, determine optimum particle packing and determine the thermal performance of these composites.
The current study focuses on the fundamental understanding of such functional composites, from their microstructural design to macro-scale application. More specifically, this study investigates three different categories of functional cementitious composites. First, it discusses the differences between cementitious systems containing interground and blended limestone with and without alumina. The interground systems are found to outperform the blended systems due to differential grinding of limestone. A novel approach to deduce the particle size distribution of limestone and cement in the interground systems is proposed. Secondly, the study delves into the realm of ultra-high performance concrete, a novel material which possesses extremely high compressive-, tensile- and flexural-strength and service life as compared to regular concrete. The study presents a novel first principles-based paradigm to design economical ultra-high performance concretes using locally available materials. In the final part, the study addresses the thermal benefits of a novel type of concrete containing phase change materials. A software package was designed to perform numerical simulations to analyze temperature profiles and thermal stresses in concrete structures containing PCMs.
The design of these materials is accompanied by material characterization of cementitious binders. This has been accomplished using techniques that involve measurement of heat evolution (isothermal calorimetry), determination and quantification of reaction products (thermo-gravimetric analysis, x-ray diffraction, micro-indentation, scanning electron microscopy, energy-dispersive x-ray spectroscopy) and evaluation of pore-size distribution (mercury intrusion porosimetry). In addition, macro-scale testing has been carried out to determine compression, flexure and durability response. Numerical simulations have been carried out to understand hydration of cementitious composites, determine optimum particle packing and determine the thermal performance of these composites.
ContributorsArora, Aashay (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Chawla, Nikhilesh (Committee member) / Hoover, Christian G (Committee member) / Arizona State University (Publisher)
Created2018
Description
Phase change materials (PCMs) are combined sensible-and-latent thermal energy storage materials that can be used to store and dissipate energy in the form of heat. PCMs incorporated into wall-element systems have been well-studied with respect to energy efficiency of building envelopes. New applications of PCMs in infrastructural concrete, e.g., for mitigating early-age cracking and freeze-and-thaw induced damage, have also been proposed. Hence, the focus of this dissertation is to develop a detailed understanding of the physic-chemical and thermo-mechanical characteristics of cementitious systems and novel coating systems for wall-elements containing PCM. The initial phase of this work assesses the influence of interface properties and inter-inclusion interactions between microencapsulated PCM, macroencapsulated PCM, and the cementitious matrix. The fact that these inclusions within the composites are by themselves heterogeneous, and contain multiple components necessitate careful application of models to predict the thermal properties. The next phase observes the influence of PCM inclusions on the fracture and fatigue behavior of PCM-cementitious composites. The compliant nature of the inclusion creates less variability in the fatigue life for these composites subjected to cyclic loading. The incorporation of small amounts of PCM is found to slightly improve the fracture properties compared to PCM free cementitious composites. Inelastic deformations at the crack-tip in the direction of crack opening are influenced by the microscale PCM inclusions. After initial laboratory characterization of the microstructure and evaluation of the thermo-mechanical performance of these systems, field scale applicability and performance were evaluated. Wireless temperature and strain sensors for smart monitoring were embedded within a conventional portland cement concrete pavement (PCCP) and a thermal control smart concrete pavement (TCSCP) containing PCM. The TCSCP exhibited enhanced thermal performance over multiple heating and cooling cycles. PCCP showed significant shrinkage behavior as a result of compressive strains in the reinforcement that were twice that of the TCSCP. For building applications, novel PCM-composites coatings were developed to improve and extend the thermal efficiency. These coatings demonstrated a delay in temperature by up to four hours and were found to be more cost-effective than traditional building insulating materials.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
ContributorsAguayo, Matthew Joseph (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Underwood, Benjamin (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2018
Description本文选取当前在学界和业界关注度较高的“新三板”企业作为研究对象，从融资效率和融资偏好角度实证了新三板企业当前的运行状况，补充了资本结构和融资效率的研究文献。利用二元选择回归以及分位数回归方法，探究了内部融资、债务融资以及权益融资偏好的影响因素。本文发现：1）对于内部融资，企业资产负债率越低、经营能力越强、盈利能力越好、抵押品越少以及公司成长性高的企业更倾向于使用内部融资，资产负债率对内部融资的负面影响边际增大；2）对于债务融资，资产负债率越低、盈利能力越好、经营能力越强、抵押品越多、公司成长性高的企业更倾向于使用债务融资；3）对于权益融资，盈利能力较差、经营能力较弱的企业更倾向于使用权益融资，而资本结构以及公司成长性对权益融资没有影响。分位数回归也发现，盈利能力、现金状况、总资产周转率、资产流动性、非债务税盾、民营企业以及公司成长性等变量对权益融资的影响较为稳定，提示公司的特征变量对权益融资并没有明显的主导作用。在融资效率上，本文也发现：1）于2012年挂牌新三板的企业整体融资效率不高，DEA融资效率为有效的企业占比仅为10%左右；但融资效率在逐年持续改善，表现出一个较好的发展势头。并且，对于做市转让的企业来说，2014年由协议转让改为做市转让以后，融资相对有效的企业数量增长明显快于协议转让企业，表明采用做市转让的企业融资效率优于采用协议转让的企业。2）市场整体融资规模并未达到挂牌企业的需求，导致一半以上企业尚未达到最优的生产经营状态，仍需要资金来增加生产资料的投入，以扩大生产规模获取规模收益。对于做市转让的企业来说，在2014年由协议转让改为做市转让以后，规模报酬递增的企业数量占比下降更快，表明做市转让制度要比协议转让制度从融资效率角度更能满足新三板企业的融资需求。
ContributorsWu, Jintao (Author) / Pei, Ker-Wei (Thesis advisor) / Li, Feng (Thesis advisor) / Wang, Tan (Committee member) / Arizona State University (Publisher)
Created2019