Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
3 results
Search Results
Item POLICY IMPACTS FOR DEVELOPMENT: EXAMPLES FROM A MARRIAGE LAW AND A LAND REFORM(2024) Chen, Ying; Battistin, Erich; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This abstract outlines the chapters that form my doctoral dissertation. The first two chapters analyze the impacts of the 1974 Age-of-Marriage law in Indonesia, which aimed to curb child marriage.In the first chapter, I study the effectiveness of age-of-marriage laws. I discuss how age-of-marriage restrictions delay marriages and also affect the marriage market equilibrium, including not only when people marry but also who they marry. I build a theoretical model and illustrate graphically what happens when a law abruptly shifts the supply of marriageable brides and grooms. My model predicts that the age-of-marriage laws are expected to postpone first marriages universally. However, the extent of their impact on the marriage market varies depending on the strength of age-related preferences. In cases where individuals strongly favor a specific age gap between spouses, no marriage market effects are anticipated. Conversely, under weaker age-related preferences, the law alters matching in the marriage market and can affect bride prices, age gaps, or marriage rates. I then test some of those predictions with regression discontinuity estimates using birth cohort as the running variable. Using a large nationally-representative dataset, I estimate impacts of the Indonesian Law on age of marriage and probability of underage marriage for both women and men. In addition, I examine marriage-market effects by estimating impacts on the age gap between spouses as well as spouse education. My estimations based on large survey datasets support the notion that the marriage law delayed marriages and prevented under-age marriages, and also altered matching patterns, at least in the short run. Because the estimation in an RD design is complicated by the misreporting of birth dates, I deploy a range of robustness checks to bolster my findings. Though some of the robustness checks raise important caveats, my overall findings still suggest the law effectively delays marriage and alters matching in the marriage market. The second chapter further explores the effects of delaying marriage on life outcomes. I continue to rely on Indonesia’s Age-of-Marriage law and the same nationally representative dataset. I leverage a fuzzy regression discontinuity design to explore whether the law further brought about other commonly expected desirable outcomes of delayed marriage, such as higher education attainment, employment participation, health, wealth, and more. My results show that the law had a strong impact on girls education. It led to significant increases in all completion rates for girls, from primary school to bachelor degrees. This is consistent with some existing studies finding that delayed marriage can prevent girls from dropping out of school. I do not find similar impacts for men, for whom the marriageable age is 19. My results further do not suggest strong impacts on employment, but I significant positive effects on access to banking and communications, as well as health insurance. Echoing results from Chapter 1, I find strong impacts on spouse outcomes, suggesting that women who delayed their wedding married more educated and more successful men. The third chapter examines the land rental market effects of increased tenure security in the context of China’s land titling reform. Between 2009 and 2018, the Chinese government introduced a nationwide reform to register land titles for rural individual households in over 600,000 villages. To estimate the causal effect of the land reform, I leverage differences across villages induced by a pilot project of the reform conducted between 2009 and 2013. Estimates suggest that registering land titles for individual households led to a substantial increase in their participation in farmland rental markets, and allowed a shift towards non-kin tenants with a higher willingness to pay.Item TACTILE SENSING WITH COMPLIANT STRUCTURES FOR HUMAN-ROBOT INTERACTION(2018) Chen, Ying; Yu, Miao; Smela, Elisabeth; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation presents the research on tactile sensing with compliant structures towards human-robot interaction. It would be beneficial for robots working collaboratively with humans to be soft or padded and have compliant tactile sensing skins over the padding. To allow the robots to interact with humans via touch effectively and safely and to detect tactile stimuli in an unstructured environment, new tactile sensing concepts are needed that can detect a wide range of potential interactions and sense over an area. However, most highly sensitive tactile sensors are unable to cover the forces involved in human contacts, which ranges from 1 newton to thousand newtons; to implement area sensing capabilities, there have been challenges in creating traditional sensing arrays, where the associated supporting electronics become more complex with an increasing number of sensing elements. This dissertation develops a novel multi-layer cutaneous tactile sensing architecture for enhanced sensitivity and range, and employs an imaging technique based on boundary measurements called electrical impedance tomography (EIT) to achieve area tactile sensing capabilities. The multi-layer cutaneous tactile sensing architecture, which consists of stretchable piezoresistive strain-sensing layers over foam padding layers of different stiffness, allows for both sufficient sensitivity and an extended force range for human contacts. The role that the padding layer plays when placed under a stretchable sensing layer was investigated, and it was discovered that the padding layer magnifies the sensor signal under indentation compared to that obtained without padding layers. The roles of the multi-layer foams were investigated by changing stiffness and thickness, which allows tailoring the response of multi-layer architectures for different applications. To achieve both extended force range and distributed sensing, EIT technique was employed with the multi-layer sensing architecture. Machine and human touch were conducted on the developed multi-layer sensing system, revealing that the second sensing skin is required to detect the large variability in human touch. Although widely applied in the medical field for functional imaging, EIT applied in tactile sensing faces different challenges, such as unknown number and region of tactile stimuli. Current EIT tactile sensors have focused on qualitative demonstration. This dissertation aims at achieving quantitative information from piezoresistive EIT tactile sensors, by investigating spatial performance and the effect of sensor’s conductivity. A spatial correction method was developed for obtaining consistent spatial information, which was validated by both simulation and experiments from our stretchable piezoresistive EIT sensor with an underlying padding layer.Item SOURCES AND FATE OF ATMOSPHERIC NUTRIENTS OVER THE REMOTE OCEANS AND THEIR ROLE ON CONTROLLING MARINE DIAZOTROPHIC MICROORGANISMS(2004-11-02) Chen, Ying; Siefert, Ronald L; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Atmospheric deposition can be a major source of nutrients to the remote ocean where these nutrient species can play a critical role in major biogeochemical cycles (e.g. carbon). Atmospheric input of Fe controls phytoplankton growth in high nitrate low chlorophyll regions. Fe can also be a rate-limiting nutrient to diazotrophic microorganisms and control the nitrogen fixation in the oligotrophic ocean. Due to low solubility of aerosol Fe in the seawater only a small fraction of atmospheric input of Fe may be bioavailable. This dissertation developed an aqueous sequential extraction procedure to measure the labile Fe species in aerosols. The measured labile Fe species were compared to the photo-reducible Fe under the ambient sunlight and to the bioavailable forms of aerosol Fe to a diazotrophic microorganism. The diazotroph showed a large capacity of luxury uptake of aerosol Fe, and the uptake amount was less than the total labile Fe measured in aerosols. Labile and total aerosol Fe was found to be highly variable in time and space over the North Atlantic and North Pacific oceans. The labile aerosol Fe was mostly associated with mineral dust transported from North Africa or Asia, although it can also be associated with anthropogenic sources and atmospheric processing. Major nutrients (soluble phosphate, nitrate and ammonium) in aerosols were also found to be temporally variable over these two oceanic regions. Mineral dust transported from North Africa or Asia was a major source for soluble phosphate only during a certain season. Soluble phosphate in aerosols was sometimes strongly associated with anthropogenic tracers. Anthropogenic activities were major sources for both aerosol nitrate and ammonium. It was also found that marine biogenic source of NH3 could be significant during the spring and summer over the remote oceans. Ratios between the atmospheric inputs of labile Fe, N and P also varied seasonally, which may result in a various nutrient limitation to the water column. The residence time of dissolved Fe in the upper Pacific was estimated longer than those in the Atlantic and the Indian oceans.