<p>As the economy recovered with the winding down of the pandemic, businesses with complex supply chains could not bring their inventories back to optimal levels as their production was susceptible to disruption due to supply outages. Deriving optimal ordering policies as a way to mitigate the impact of production disruption represents a challenge in multi-stage decision problems given the complexity of the network and the uncertainty in the demand.</p> <p><br></p> <p>In the first part of the thesis, we formulate a stochastic inventory control problem for a general supply network model. Using the Bellman’s recursion and properties of the cost function at each stage, we characterize the optimal request decision as a threshold policy where the threshold computation is based on the marginal cost. Lastly, we validate that the policy developed minimizes the inventory cost and meets an exogenous random demand. However, the policy does not guarantee that the inventory level for each firm satisfies the constraints when a supply disruption occurs in the network.</p> <p><br></p> <p>In the second part of the thesis, we consider a serial network in which firms engage in production subject to disruption risk and they look to maximize their profit. We propose an algorithm to characterize a stationary optimal policy based on the closed-form solutions obtained from a discounted finite horizon problem for profit maximization. Finally, by computing the policy proposed as a function of the tier’s location and its disruption probability, we provide simulation results of the disruption effect in the supply network.</p>

Block copolymer (BCP) nanocomposites are an important class of hybrid materials in which the BCP guides the spatial location and the periodic assembly of the additives. High loadings of well-dispersed nanofillers are generally important for many applications including mechanical reinforcing of polymers. In particular the composites shown in this work might find use as etch masks in nanolithography, or for enabling various phase selective reactions for new materials development. This work explores the use of hydrogen bonding interactions between various additives (such as homopolymers and non-polymeric additives) and small, disordered BCPs to cause the formation of well-ordered morphologies with small domains. A detailed study of the organization of homopolymer chains and the evolution of structure during the process of ordering is performed. The results demonstrate that by tuning the selective interaction of the additive with the incorporating phase of the BCP, composites with significantly high loadings of additives can be formed while maintaining order in the BCP morphology. The possibility of high and selective loading of additives in one of the phases of the ordered BCP composite opens new avenues due to high degree of functionalization and the proximity of the additives within the incorporating phase. This aspect is utilized in one case for the formation of a network structure between adjoining additive cores to derive mesoporous inorganic materials with their structures templated by the BCP. The concept of additive-driven assembly is extended to formulate BCP-additive blends with an ability to undergo photo-induced ordering. Underlying this strategy is the ability to transition a weakly interacting additive to its strongly interacting form. This strategy provides an on-demand, non-intrusive route for formation of well-ordered nanostructures in arbitrarily defined regions of an otherwise disordered material. The second area explored in this dissertation deals with the incorporation of additives into photoresists for next generation extreme ultra violet (EUV) photolithography applications. The concept of hydrogen bonding between the additives and the polymeric photoresist was utilized to cause formation of a physical network that is expected to slow down the diffusion of photoacid leading to better photolithographic performance (25-30 nm resolution obtained).

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24962号 / 理博第4987号 / 新制||理||1712(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中家 剛, 教授 永江 知文, 教授 田島 治 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

As consumers continue to adopt and adapt to newer technologies, firms face a common question adapted from the 1989 motion picture Field of Dreams: “If we build it, will they come?” Until recently, it has been assumed that the answer will always be “yes.” However, to properly expand upon this question, we look in this paper to the research proposed around the same time the aforementioned feature film was released to understand the application of Davis’s Technology Acceptance Model (1986) as it relates to newer emerging technologies such as Facial authentication as an alternative to the point-of-entry at public event spaces. The introduction of biometrics as a method of entry creates an opportunity to examine the tension between this technology and user acceptance of privacy. The option of mobile ordering juxtaposed with traditional point-of-sale and physically waiting in line provides insight into a second sub-setting to address technology adoption’s impact on revenue.The first study leverages secondary data collected from a pilot program conducted at three Major League Baseball stadiums in 2021 to examine the use and efficacy of Facial authentication as a point-of-entry solution and alternative to mobile ticketing. This study analyzed the data collected in pre- and post-participant surveys and transactional data from 21 events in 30 days (n=343). The study uses secondary data to test two hypothetical scenarios through variables such as the method of entry and patron traits to determine if a relationship exists between one or more of the variables. The second study focuses on understanding the use of a newly introduced technology within the sub-setting of concessions in the sports & entertainment setting. The data was collected from 45 consecutive events over 25832 individual transactions and examined the influence of mobile ordering on revenue and patron behavior (n=557). The setting provides an opportunity for examination of variables impacting the firm as juxtaposed with legacy technology. The study establishes setting and sub-settings related to sports & entertainment. The primary setting is the venue, which contains sub-settings permeated with emerging technologies. The two sub-settings examined are the first two settings patrons typically interact with on a given event level. Point-of-entry provided for examinations of patron use of a newly introduced facial authentication platform, which affirms TAM and UTAUT models. In the second study the count of items within a mobile ordering transaction were significant and led to creation of a new variable which measures average revenue per item per transaction. This new variable shed light into a key finding. Interestingly enough, the second sub-setting provided insight into consumer spending habits through the newly introduced technology that led to findings related to revenue and conclusions for the firm regarding future deployment and positioning of the technology. / Business Administration/Management Information Systems

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The purpose of this experimental study is to examine the effects of recasts on narrowing overgeneralized grammar in the second language (L2). The study involved testing three major hypotheses of the mechanisms underlying recasts: the direct contrast hypothesis (Saxton, 1997, 2000), the additional input hypothesis (Gass, 1997; Gass & Mackey, 2007; Long, 1996, 2007), and the enhanced salience hypothesis (Leeman, 2003). Two structures (adjective ordering and indirect passives) were selected for this study, mainly because it was assumed that Japanese learners of English might produce overgeneralized rules that allow incorrect structures because of their first language (L1) influence. The participants were 97 Japanese university students learning English as a foreign language in Japan. They were randomly assigned to four treatment groups: recast (the REC Group), non-contingent positive evidence (the POS Group), recast plus additional input (the REC+ Group), and input with enhanced salience (the SAL Group). A pretest, posttest, and delayed-posttest design were employed. The measurement instruments were an oral production task, elicited imitation task, and untimed grammaticality judgment task, each of which was designed to elicit participants’ implicit and explicit knowledge about adjective ordering and indirect passives. Thus, the independent variable was the treatment conditions, and the dependent variable were the test scores regarding ungrammaticality of the overgeneralized rules of the target structures. After data screening, the data from 75 of the 97 participants were analyzed for adjective ordering, and the data from 90 participants were analyzed for indirect passives. The results showed that the POS Group did not improve on all the measures for adjective ordering and indirect passives; thus, it was suggested that positive evidence was not sufficient for the participants to narrow overgeneralized rules for the target structures. The findings indicated that for adjective ordering, medium effect sizes for the comparison of the POS and REC Groups were obtained on the grammaticality judgment tests for the pretest-posttest and pretest-delayed posttest comparisons. Thus, based on these effect sizes, the direct contrast hypothesis was partially supported (i.e., for one of the two structures and one measure of the three tests). Furthermore, on the basis of the results that the REC and REC+ Groups did not differ significantly on any measure and that on the adjective-ordering grammaticality judgment tests, the comparison between the REC+ Group and the POS Group obtained a medium effect size for the pretest-delayed posttest comparison, the provision of recasts in the REC and REC+ Groups was effective at least for the adjective-ordering grammaticality judgment tests; however, additional input alone did not have an impact on L2 learners’ retreat from the overgeneralized rules. Finally, the results showed that the POS and SAL Groups did not differ significantly and that there existed a difference in the performance on the adjective-ordering grammaticality judgment tests between the REC Group and the SAL Groups. Salience might not be effective in helping L2 learners retreat from overgeneralized rules, and the enhanced salience hypothesis can be interpreted as being limited to learning some linguistic structures. In conclusion, the present study provides empirical evidence that L2 learners can persist in using incorrect overgeneralized rules due to L1 rules and that ten tokens of the target structures are not effective for L2 learners to retreat from the overgeneralized rules. Furthermore, the findings lend support to the direct contrast hypothesis as a mechanism underlying recasts for one of the two target structures. / Teaching & Learning

The reliability and quality of suppliers' components are inevitably two factors that impact the performance of the supply chain. Stochastic reliability affects the final production quantity and hence makes it more difficult to predict the manufacturer's best ordering quantity as opposed to the simpler traditional news vendor model. In addition, the quality of suppliers' products directly influence the potential demand in the market. Hence every firm in the supply chain system faces the needs to invest time, money and effort to improve the product quality even though it may bring a higher production and investment cost. Thus our dissertation is divided into two parts. In the first part, we build a model for a two echelon supply chain system in which a single manufacturer sells his product to a market with stochastic demand. A group of suppliers provide essential components for the manufacturer. They may be: 1) homogeneous component suppliers, 2) complementary component suppliers or 3) divided into subgroups, suppliers in the same subgroup provide the same component while the components from different subgroups are assembled in the final product. The fraction of effective component ordered from each supplier is a random variable. We first analyze the manufacturer's optimal ordering quantity decision. We identify several important properties of the optimal decision. Then based on those properties, we devise optimal solution procedures and heuristic methods for the above three systems. Finally, in the case of Bernoulli reliability, we investigate the suppliers' price competition by non-cooperative game theory. In the second part, we model a two echelon assembly system which faces deterministic demand affected by the market price and quality of the product. Therefore, the decisions of the firms are divided into two stages: in the first stage, they decide on how much effort to invest in the quality of the components or the final product to stimulate the market. They may make decisions simultaneously or sequentially. Then after the efforts are invested, in the second stage, the component suppliers first decide on their components' wholesale price and then the manufacture decides on the market price given the wholesale price. We identify the existence of Nash equilibrium in each stage through potential functions. Moreover, in the first stage decision, we find that the competition with a leader can always benefit the whole system compared with simultaneous competition. / Ph. D.