Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
Displaying 1 - 10 of 106
Description
I show that firms' ability to adjust variable capital in response to productivity shocks has important implications for the interpretation of the widely documented investment-cash flow sensitivities. The variable capital adjustment is sufficient for firms to capture small variations in profitability, but when the revision in profitability is relatively large, limited substitutability between the factors of production may call for fixed capital investment. Hence, firms with lower substitutability are more likely to invest in both factors together and have larger sensitivities of fixed capital investment to cash flow. By building a frictionless capital markets model that allows firms to optimize over fixed capital and inventories as substitutable factors, I establish the significance of the substitutability channel in explaining cross-sectional differences in cash flow sensitivities. Moreover, incorporating variable capital into firms' investment decisions helps explain the sharp decrease in cash flow sensitivities over the past decades. Empirical evidence confirms the model's predictions.
ContributorsKim, Kirak (Author) / Bates, Thomas (Thesis advisor) / Babenko, Ilona (Thesis advisor) / Hertzel, Michael (Committee member) / Tserlukevich, Yuri (Committee member) / Arizona State University (Publisher)
Created2013
Description
For decades, microelectronics manufacturing has been concerned with failures related to electromigration phenomena in conductors experiencing high current densities. The influence of interconnect microstructure on device failures related to electromigration in BGA and flip chip solder interconnects has become a significant interest with reduced individual solder interconnect volumes. A survey indicates that x-ray computed micro-tomography (µXCT) is an emerging, novel means for characterizing the microstructures' role in governing electromigration failures. This work details the design and construction of a lab-scale µXCT system to characterize electromigration in the Sn-0.7Cu lead-free solder system by leveraging in situ imaging.
In order to enhance the attenuation contrast observed in multi-phase material systems, a modeling approach has been developed to predict settings for the controllable imaging parameters which yield relatively high detection rates over the range of x-ray energies for which maximum attenuation contrast is expected in the polychromatic x-ray imaging system. In order to develop this predictive tool, a model has been constructed for the Bremsstrahlung spectrum of an x-ray tube, and calculations for the detector's efficiency over the relevant range of x-ray energies have been made, and the product of emitted and detected spectra has been used to calculate the effective x-ray imaging spectrum. An approach has also been established for filtering `zinger' noise in x-ray radiographs, which has proven problematic at high x-ray energies used for solder imaging. The performance of this filter has been compared with a known existing method and the results indicate a significant increase in the accuracy of zinger filtered radiographs.
The obtained results indicate the conception of a powerful means for the study of failure causing processes in solder systems used as interconnects in microelectronic packaging devices. These results include the volumetric quantification of parameters which are indicative of both electromigration tolerance of solders and the dominant mechanisms for atomic migration in response to current stressing. This work is aimed to further the community's understanding of failure-causing electromigration processes in industrially relevant material systems for microelectronic interconnect applications and to advance the capability of available characterization techniques for their interrogation.
In order to enhance the attenuation contrast observed in multi-phase material systems, a modeling approach has been developed to predict settings for the controllable imaging parameters which yield relatively high detection rates over the range of x-ray energies for which maximum attenuation contrast is expected in the polychromatic x-ray imaging system. In order to develop this predictive tool, a model has been constructed for the Bremsstrahlung spectrum of an x-ray tube, and calculations for the detector's efficiency over the relevant range of x-ray energies have been made, and the product of emitted and detected spectra has been used to calculate the effective x-ray imaging spectrum. An approach has also been established for filtering `zinger' noise in x-ray radiographs, which has proven problematic at high x-ray energies used for solder imaging. The performance of this filter has been compared with a known existing method and the results indicate a significant increase in the accuracy of zinger filtered radiographs.
The obtained results indicate the conception of a powerful means for the study of failure causing processes in solder systems used as interconnects in microelectronic packaging devices. These results include the volumetric quantification of parameters which are indicative of both electromigration tolerance of solders and the dominant mechanisms for atomic migration in response to current stressing. This work is aimed to further the community's understanding of failure-causing electromigration processes in industrially relevant material systems for microelectronic interconnect applications and to advance the capability of available characterization techniques for their interrogation.
ContributorsMertens, James Charles Edwin (Author) / Chawla, Nikhilesh (Thesis advisor) / Alford, Terry (Committee member) / Jiao, Yang (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2015
Description
I examine the determinants and implications of the level of director monitoring. I use the distance between directors' domiciles and firm headquarters as a proxy for the level of monitoring and the introduction of a new airline route between director domicile and firm HQ as an exogenous shock to the level of monitoring. I find a strong relation between distance and both board meeting attendance and director membership on strategic versus monitoring committees. Increased monitoring, as measured by a reduction in effective distance, by way of addition of a direct flight, is associated with a 3% reduction in firm value. A reduction in effective distance is also associated with less risk-taking, lower stock return volatility, lower accounting return volatility, lower R&D; spending, fewer acquisitions, and fewer patents.
ContributorsBennett, Benjamin (Author) / Coles, Jeffrey (Thesis advisor) / Hertzel, Michael (Committee member) / Babenka, Ilona (Committee member) / Custodio, Claudia (Committee member) / Arizona State University (Publisher)
Created2014
Description
This dissertation analyzes the reliability of reported employee stock option (ESO) expense, the determination of expected life of ESOs, motivations to manipulate ESO expense, and the impact of noise in ESO expense on subsequent stock price returns. Based on unique data, this is the first paper to measure average historical ESO life for all employees of a broad set of firms. I find average life has a mean of 4.12 years. Average life is reduced by 0.38 years per 10 percentage point increase in volatility, and industry effects explain an additional 7% of the variation. Reported expected life increases 0.37 years per year of historical life and an additional 0.16 years per year of age of the outstanding options. Deviations of reported volatility and life from benchmarks have positive correlations with deviations from own reporting history. Using stated assumptions rather than benchmark assumptions drops (increases) ESO expense by 8.3% (17.6%) for the 25th (75th) percentile firm. The change in earnings per share decreases (increases) by $0.019 ($0.007) for the 25th (75th) percentile firm. Tests for motivations to manipulate stock option expense downward have mixed results. Absolute values of deviations from benchmarks have a positive relationship with subsequent stock price volatility suggesting noise in reported stock option expense results in stock price noise. Deviations from benchmarks and subsequent cumulative abnormal returns have statistically significant results but are difficult to interpret.
ContributorsYoung, Brian (Author) / Coles, Jeffrey (Thesis advisor) / Hertzel, Michael (Committee member) / Babenko, Ilona (Committee member) / Arizona State University (Publisher)
Created2011
Description
In this dissertation, I examine the source of some of the anomalous capital market outcomes that have been documented for firms with high accruals. Chapter 2 develops and implements a methodology that decomposes a firm's discretionary accruals into a firm-specific and an industry-specific component. I use this decomposition to investigate which component drives the subsequent negative returns associated with firms with high discretionary accruals. My results suggest that these abnormal returns are driven by the firm-specific component of discretionary accruals. Moreover, although industry-specific discretionary accruals do not directly contribute towards this anomaly, I find that it is precisely when industry-specific discretionary accruals are high that firms with high firm-specific discretionary accruals subsequently earn these negative returns. While consistent with irrational mispricing or a rational risk premium associated with high discretionary accruals, these findings also support a transactions-cost based explanation for the accruals anomaly whereby search costs associated with distinguishing between value-relevant and manipulative discretionary accruals can induce investors to overlook potential earnings manipulation. Chapter 3 extends the decomposition to examine the role of firm-specific and industry-specific discretionary accruals in explaining the subsequent market underperformance and negative analysts' forecast errors documented for firms issuing equity. I examine the post-issue market returns and analysts' forecast errors for a sample of seasoned equity issues between 1975 and 2004 and find that offering-year firm-specific discretionary accruals can partially explain these anomalous capital market outcomes. Nonetheless, I find this predictive power of firm-specific accruals to be more pronounced for issues that occur during 1975 - 1989 compared to issues taking place between 1990 and 2004. Additionally, I find no evidence that investors and analysts are more overoptimistic about the prospects of issuers that have both high firm-specific and industry-specific discretionary accruals (compared to firms with high discretionary accruals in general). The results indicate no role for industry-specific discretionary accruals in explaining overoptimistic expectations from seasoned equity issues and suggest the importance of firm-specific factors in inducing earnings manipulation surrounding equity issues.
ContributorsIkram, Atif (Author) / Coles, Jeffrey (Thesis advisor) / Hertzel, Michael (Committee member) / Tserlukevich, Yuri (Committee member) / Arizona State University (Publisher)
Created2011
Description
Mutual monitoring in a well-structured authority system can mitigate the agency problem. I empirically examine whether the number 2 executive in a firm, if given authority, incentive, and channels for communication and influence, is able to monitor and constrain the potentially self-interested CEO. I find strong evidence that: (1) measures of the presence and extent of mutual monitoring from the No. 2 executive are positively related to future firm value (Tobin's Q); (2) the beneficial effect is more pronounced for firms with weaker corporate governance or CEO incentive alignment, with stronger incentives for the No. 2 executives to monitor, and with higher information asymmetry between the boards and the CEOs; (3) such mutual monitoring reduces the CEO's ability to pursue the "quiet life" but has no effect on "empire building;" and (4) mutual monitoring is a substitute for other governance mechanisms. The results suggest that mutual monitoring by a No. 2 executive provides checks and balances on CEO power.
ContributorsLi, Zhichuan (Author) / Coles, Jeffrey (Thesis advisor) / Hertzel, Michael (Committee member) / Bharath, Sreedhar (Committee member) / Babenko, Ilona (Committee member) / Arizona State University (Publisher)
Created2012
Description
This paper investigates the role of top management and board interlocks between acquirers and targets. I hypothesize that an interlock may exacerbate agency problems due to conflicting interests and lead to value-decreasing acquisition. An interlock may also serve as a conduit of information and personal experience, and reduce the cost of information gathering for both firms. I find supporting evidence for these two non-mutually exclusive hypotheses. Consistent with the agency hypothesis, interlocked acquirers underperform non-interlocked acquirers by 2% during the announcement period. However, well-governed acquirers receive higher announcement returns and have better post-acquisition performance in interlocked deals. The proportional surplus accrued to an acquirer is positively correlated with the interlocking agent's ownership in the acquirer relative to her ownership in the target. Consistent with the information hypothesis, when the target's firm value is opaque, interlocks improve acquirer announcement returns and long-term performance. Interlocked acquirers are also more likely to use equity as payment, especially when the acquirer's stock value is opaque. Target announcement returns are not influenced by the existence of interlock. Finally, I find acquisitions are more likely to occur between two interlocked firms and such deals have a higher completion rate.
ContributorsWu, Qingqing (Author) / Bates, Thomas W. (Thesis advisor) / Hertzel, Michael (Committee member) / Lindsey, Laura (Committee member) / Arizona State University (Publisher)
Created2012
Description
The study of deflagration to detonation transition (DDT) in explosives is of prime importance with regards to insensitive munitions (IM). Critical damage owing to thermal or shock stimuli could translate to significant loss of life and material. The present study models detonation and deflagration of a commonly used granular explosive: cyclotetramethylene-tetranitramine, HMX. A robust literature review is followed by computational modeling of gas gun and DDT tube test data using the Sandia National Lab three-dimensional multi-material Eulerian hydrocode CTH. This dissertation proposes new computational practices and models that aid in predicting shock stimulus IM response. CTH was first used to model experimental data sets of DDT tubes from both Naval Surface Weapons Center and Los Alamos National Laboratory which were initiated by pyrogenic material and a piston, respectively. Analytical verification was performed, where possible, for detonation via empirical based equations at the Chapman Jouguet state with errors below 2.1%, and deflagration via pressure dependent burn rate equations. CTH simulations include inert, history variable reactive burn and Arrhenius models. The results are in excellent agreement with published HMX detonation velocities. Novel additions include accurate simulation of the pyrogenic material BKNO3 and the inclusion of porosity in energetic materials. The treatment of compaction is especially important in modeling precursory hotspots, caused by hydrodynamic collapse of void regions or grain interactions, prior to DDT of granular explosives. The CTH compaction model of HMX was verified within 11% error via a five pronged validation approach using gas gun data and employed use of a newly generated set of P-α parameters for granular HMX in a Mie-Gruneisen Equation of State. Next, the additions of compaction were extended to a volumetric surface burning model of HMX and compare well to a set of empirical burn rates. Lastly, the compendium of detonation and deflagration models was applied to the aforementioned DDT tubes and demonstrate working functionalities of all models, albeit at the expense of significant computational resources. A robust hydrocode methodology is proposed to make use of the deflagration, compaction and detonation models as a means to predict IM response to shock stimulus of granular explosive materials.
ContributorsMahon, Kelly Susan (Author) / Lee, Taewoo (Thesis advisor) / Herrmann, Marcus (Committee member) / Chen, Kangping (Committee member) / Jiao, Yang (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2015
Description
Materials with unprecedented properties are necessary to make dramatic changes in current and future aerospace platforms. Hybrid materials and composites are increasingly being used in aircraft and spacecraft frames; however, future platforms will require an optimal design of novel materials that enable operation in a variety of environments and produce known/predicted damage mechanisms. Nanocomposites and nanoengineered composites with CNTs have the potential to make significant improvements in strength, stiffness, fracture toughness, flame retardancy and resistance to corrosion. Therefore, these materials have generated tremendous scientific and technical interest over the past decade and various architectures are being explored for applications to light-weight airframe structures. However, the success of such materials with significantly improved performance metrics requires careful control of the parameters during synthesis and processing. Their implementation is also limited due to the lack of complete understanding of the effects the nanoparticles impart to the bulk properties of composites. It is common for computational methods to be applied to explain phenomena measured or observed experimentally. Frequently, a given phenomenon or material property is only considered to be fully understood when the associated physics has been identified through accompanying calculations or simulations.
The computationally and experimentally integrated research presented in this dissertation provides improved understanding of the mechanical behavior and response including damage and failure in CNT nanocomposites, enhancing confidence in their applications. The computations at the atomistic level helps to understand the underlying mechanochemistry and allow a systematic investigation of the complex CNT architectures and the material performance across a wide range of parameters. Simulation of the bond breakage phenomena and development of the interface to continuum scale damage captures the effects of applied loading and damage precursor and provides insight into the safety of nanoengineered composites under service loads. The validated modeling methodology is expected to be a step in the direction of computationally-assisted design and certification of novel materials, thus liberating the pace of their implementation in future applications.
The computationally and experimentally integrated research presented in this dissertation provides improved understanding of the mechanical behavior and response including damage and failure in CNT nanocomposites, enhancing confidence in their applications. The computations at the atomistic level helps to understand the underlying mechanochemistry and allow a systematic investigation of the complex CNT architectures and the material performance across a wide range of parameters. Simulation of the bond breakage phenomena and development of the interface to continuum scale damage captures the effects of applied loading and damage precursor and provides insight into the safety of nanoengineered composites under service loads. The validated modeling methodology is expected to be a step in the direction of computationally-assisted design and certification of novel materials, thus liberating the pace of their implementation in future applications.
ContributorsSubramanian, Nithya (Author) / Chattopadhyay, Aditi (Thesis advisor) / Dai, Lenore (Committee member) / Jiao, Yang (Committee member) / Liu, Yongming (Committee member) / Rajadas, John (Committee member) / Arizona State University (Publisher)
Created2018
Description
Aluminum alloys are ubiquitously used in almost all structural applications due to their high strength-to-weight ratio. Their superior mechanical performance can be attributed to complex dispersions of nanoscale intermetallic particles that precipitate out from the alloy’s solid solution and offer resistance to deformation. Although they have been extensively investigated in the last century, the traditional approaches employed in the past haven’t rendered an authoritative microstructural understanding in such materials. The effect of the precipitates’ inherent complex morphology and their three-dimensional (3D) spatial distribution on evolution and deformation behavior have often been precluded. In this study, for the first time, synchrotron-based hard X-ray nano-tomography has been implemented in Al-Cu alloys to measure growth kinetics of different nanoscale phases in 3D and reveal mechanistic insights behind some of the observed novel phase transformation reactions occurring at high temperatures. The experimental results were reconciled with coarsening models from the LSW theory to an unprecedented extent, thereby establishing a new paradigm for thermodynamic analysis of precipitate assemblies. By using a unique correlative approach, a non-destructive means of estimating precipitation-strengthening in such alloys has been introduced. Limitations of using existing mechanical strengthening models in such alloys have been discussed and a means to quantify individual contributions from different strengthening mechanisms has been established.
The current rapid pace of technological progress necessitates the demand for more resilient and high-performance alloys. To achieve this, a thorough understanding of the relationships between material properties and its structure is indispensable. To establish this correlation and achieve desired properties from structural alloys, microstructural response to mechanical stimuli needs to be understood in three-dimensions (3D). To that effect, in situ tests were conducted at the synchrotron (Advanced Photon Source) using Transmission X-Ray Microscopy as well as in a scanning electron microscope (SEM) to study real-time damage evolution in such alloys. Findings of precipitate size-dependent transition in deformation behavior from these tests have inspired a novel resilient aluminum alloy design.
The current rapid pace of technological progress necessitates the demand for more resilient and high-performance alloys. To achieve this, a thorough understanding of the relationships between material properties and its structure is indispensable. To establish this correlation and achieve desired properties from structural alloys, microstructural response to mechanical stimuli needs to be understood in three-dimensions (3D). To that effect, in situ tests were conducted at the synchrotron (Advanced Photon Source) using Transmission X-Ray Microscopy as well as in a scanning electron microscope (SEM) to study real-time damage evolution in such alloys. Findings of precipitate size-dependent transition in deformation behavior from these tests have inspired a novel resilient aluminum alloy design.
ContributorsKaira, Chandrashekara Shashank (Author) / Chawla, Nikhilesh (Thesis advisor) / Solanki, Kiran (Committee member) / Jiao, Yang (Committee member) / De Andrade, Vincent (Committee member) / Arizona State University (Publisher)
Created2017