Physical Sciences and Mathematics Commons^™

Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp

Dissertations, Master's Theses and Master's Reports

Boreal peatlands store approximately one third of the earth’s terrestrial carbon, locked away in currently waterlogged and frozen conditions. Peatlands of boreal and arctic ecosystems are affected increasingly by shifting hydrology caused by climate change. The consequences of these relatively rapid ecosystem changes on carbon cycling between the landscape and the atmosphere could provide an amplifying feedback to climate warming. Alternatively, the advancement of terrestrial vegetation into once waterlogged soils could uptake carbon as a sink. Previous work suggests that fens will become an increasingly dominant landscape feature in the boreal. However, studies investigating fens, their response to hydrologic and …

Investigation Of Light Transport And Scattering In Turbulent Clouds: Simulations And Laboratory Measurements, Corey D. Packard

Dissertations, Master's Theses and Master's Reports

A better understanding of light transport and scattering in turbulent clouds is needed for more accurate remote sensing, improved imaging and signal transmission through atmospheric aerosol and fog, and deeper understanding of cloud optical properties relevant to weather and climate. In this study, we investigate the impact of light scattering in clouds on two problems of atmospheric relevance.

In the first part, we examine deleterious effects of the atmosphere on remotely acquired images including signal attenuation and potential blurring due to forward-scattered light accepted by the imaging system. A prior proposed aerosol scattering model provides a method for calculating the …

Development Of Ecoregion Criteria Through Assessment Of Changing Floating Vegetation: A Case Study Of Intha Communities In Inlelake, Myanmar, Saint N/A

Chulalongkorn University Theses and Dissertations (Chula ETD)

The Inle Lake ecoregion, one of the fresh water ecoregions in the Global 200 list of ecoregions, is facing impacts of sedimentation from upland catchments. Sediment loads and soil sediment characteristics from degraded forest of Kalaw catchment shallowed and reduced plant nutrients in the Inle Lake ecosystems where used to be well recognized for the balancing between Intha livelihoods and natural production of littoral and pelagic zones. This study aimed to assess causes of ecological function change in terms of high sediment loads influencing Intha livelihoods; floating vegetation and to propose criteria for ecoregion development concerning sustainable floating vegetation yields …

Some Properties Of Uniform Fuzzy Modules And Semiuniform Fuzzy Modules, Burhan Chemat

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this thesis, we study some properties of uniform fuzzy modules and semiuniform fuzzy modules. Let R be a ring with the identity and M a right R-module. A submodule A of a right R-module M is called an essential submodule of M, if any non-zero submodule B of M, A∩B≠{θ} where θ is the zero element in M. A right R-module M is called a uniform module, if any non-zero submodule of M is an essential submodule of M. A submodule α of a fuzzy module μ in a right R-module M is called an essential submodule of μ, …

Distance Powers Of Partial Unitary Cayley Graphs, Muntiranee Mongkolsin

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

Reliability Analysis For Systems With Outsourced Components, Zhengwei Hu

Doctoral Dissertations

"The current business model for many industrial firms is to function as system integrators, depending on numerous outsourced components from outside component suppliers. This practice has resulted in tremendous cost savings; it makes system reliability analysis, however, more challenging due to the limited component information available to system designers. The component information is often proprietary to component suppliers. Motivated by the need of system reliability prediction with outsourced components, this work aims to explore feasible ways to accurately predict the system reliability during the system design stage. Four methods are proposed. The first method reconstructs component reliability functions using limited …

Provenance And Depositional Environments Of The Upper Permian-Lowermost Triassic Fluvial And Lacustrine Sandstones, Wutonggou Low-Order Cycle, Bogda Mountains, Nw China, Dongyu Zheng

Doctoral Dissertations

"This work integrates petrographic and fieldwork studies and documents the spatial and temporal distributions of compositions and textures of the upper Permian-lowermost Triassic fluvial-lacustrine sandstones, Wutonggou low-order cycle (WTG LC), Bogda Mountains, NW China. In the first part, three petrofacies are identified on the basis of the relative abundances of quartz, feldspar, and lithics and conglomerate compositions and paleocurrent directions are documented. These data indicate that rocks of the eastern North Tianshan Suture (ENTS) and rift shoulders were the provenance lithology. Moreover, the upsection changes of petrofacies and conglomerate compositions suggest that the lithology of ENTS changed. During approximately Wuchiapingian, …

Nanomorphology Dependent Optical And Mechanical Properties Of Aerogels, Chandana Mandal

Doctoral Dissertations

"Aerogels are very low density, light weight open pore materials. A hypothesis that is under intense current investigation by the scientific community states that the mechanical properties of nanostructured polymers depend on their nanomorphology. Aerogels are nanostructured ultra-lightweight nanoporous materials with skeletal frameworks that can display a wide range of nanomorphologies. Thereby aerogels comprise a suitable platform for testing not only that hypothesis but also a wide range of other properties such as light scattering for applications, for example, in thermally insulating windows.

To study the mechanical properties of nanostructured matter as a function of nanomorphology, various shape-memory polyurethane aerogels …

Origin Of Periclines In The Ozark Plateau, Missouri: A Field And Numerical Modeling, Chao Liu

Doctoral Dissertations

"A series upright sub-horizontal folds in sandstones of the early Ordovician Roubidoux Formation are exposed in road cuts along US Highway 63 in the northern part of the Salem Plateau of central Missouri for over a distance of approximately 10 km. These folds are in marked contrast to the more typical horizontal to sub-horizontal Ordovician strata of the Ozark Plateau. The origin of those folds remains enigmatic. The inspection of the characteristics of these folds using stereographic analysis revealed a non-cylindrical geometrical pattern than a near cylindrical fold. Structural data of 54 folds indicate an alternating basin and dome pattern. …

Decoding The History Of The Early Solar System Using Comet Volatile Compositions, Nathaniel Xavier Roth

Doctoral Dissertations

"Understanding the evolution of the solar system, as well as its current volatile content, requires knowledge of the initial conditions present in the solar nebula. As some of the first objects to accrete in the solar nebula, cometary nuclei are among the most primitive remnants of solar system formation, and their present-day volatile composition likely reflects the composition and conditions where (and when) they formed. As such, the volatile compositions of cometary nuclei may serve as 'fossils' of solar system formation. High-resolution near-infrared spectroscopy offers a valuable tool for sampling the primary volatile (i.e., ices subliming directly from the nucleus) …

Applications Of Machine Learning In Nuclear Imaging And Radiation Detection, Shaikat Mahmood Galib

Doctoral Dissertations

"The main focus of this work is to use machine learning and data mining techniques to address some challenging problems that arise from nuclear data. Specifically, two problem areas are discussed: nuclear imaging and radiation detection. The techniques to approach these problems are primarily based on a variant of Artificial Neural Network (ANN) called Convolutional Neural Network (CNN), which is one of the most popular forms of 'deep learning' technique.

The first problem is about interpreting and analyzing 3D medical radiation images automatically. A method is developed to identify and quantify deformable image registration (DIR) errors from lung CT scans …

Characterization Of A Green Electric Solid Propellant For Electric Propulsion, Matthew Scott Glascock

Doctoral Dissertations

"Electric solid propellants are advanced solid chemical rocket propellants that can be controlled (ignited, throttled and extinguished) through the application and removal of an electric current. These propellants are also being considered for use in ablative pulsed plasma thruster and multimode systems. In this work, the behavior and performance of a novel green electric solid propellant operating in an electrothermal ablation-fed pulsed plasma thruster was investigated. Using an inverted pendulum micro-Newton thrust stand, the impulse bit and specific impulse of the device using the electric solid propellant were measured for short-duration and long-duration runs to end-of-life, at energy levels of …

Accurate Monitoring Of X, Y, And Z Magnetization For Analysis Of Hardware And Pulse Sequence Performance In Nmr Spectroscopy, Emmalou Theresa Schmittzehe

Doctoral Dissertations

"A new nuclear magnetic resonance (NMR) imaging protocol has been developed to independently record the x, y, and z components of the nuclear net magnetization at any point in a pulse sequence while eliminating the observation of the other components. This protocol provides an experimental method of tracking magnetization which then can be used in conjunction with theoretical models to scrutinize the predicted outcome of each step in an NMR pulse sequence and potentially find further improvements to their effectiveness and efficiency. The protocol utilizes a rapid rotating-frame imaging pulse-train technique to obtain RF-field (B₁) and resonance-offset (ΔB …

Fault Imaging Enhancement In Taranaki Basin, New Zealand And Rock Physics And Inversion Based Reservoir Characterization In The Central Gulf Coast Region Of Texas, Tianze Zhang

Doctoral Dissertations

"Fault imaging technique and reservoir characterization based on rock physics analysis and pre-stack inversion has been widely used hydrocarbon exploration. For the fault imaging technique, the ant tracking has been widely used in fault interpretation. However, the reliability of the results is highly dependent on appropriately choosing a signal processing method and volume attributes. In our study area, which lies in the southern Taranaki Basin, we applied Graphic Equalizer as the processing tool and the Chaos attribute before running the ant tracking algorithm. Results show that the procedure provides a better result and can map both the major and minor …

Designing Novel Multinary Transition Metal Selenides As High-Efficiency Oxygen Evolution Reaction Electrocatalysts And Investigating Surface Properties, Xi Cao

Doctoral Dissertations

”Water splitting has been widely considered to be an efficient way to generate sustainable and renewable energy resources in fuel cells, metal-air batteries and other energy conversion devices. Exploring efficient electrocatalysts to expedite the anodic oxygen evolution reaction (OER) is a crucial task that needs to be addressed to boost the practical application of water splitting. This research focuses on the identification of OER electrocatalysts by systematically designing non-stochiometric mixed transition metal-based selenide OER electrocatalysts through combinatorial electrodeposition and investigation of selenide-based naturally occurring minerals as effective OER electrocatalyst. Paper I describes the study of Ni-Fe-Co selenides as OER catalysts …

Volumetric Error Compensation For Industrial Robots And Machine Tools, Le Ma

Doctoral Dissertations

“A more efficient and increasingly popular volumetric error compensation method for machine tools is to compute compensation tables in axis space with tool tip volumetric measurements. However, machine tools have high-order geometric errors and some workspace is not reachable by measurement devices, the compensation method suffers a curve-fitting challenge, overfitting measurements in measured space and losing accuracy around and out of the measured space. Paper I presents a novel method that aims to uniformly interpolate and extrapolate the compensation tables throughout the entire workspace. By using a uniform constraint to bound the tool tip error slopes, an optimal model with …

Spatial And Temporal Variation Of Heavy Metals In Pm10 And Pm2.5 Surrounding E-Waste Dismantling Community In Buriram Province, Siriwipha Chanthahong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Spatial and temporal variation of heavy metals in PM10 and PM2.5 surrounding e-waste dismantling community at Buriram Province were investigated during April and September. The aims of this study were to monitor and compare between those found at non- (NS) and e-waste dismantling house (ES) and open dump area (OD), and identify potential sources of heavy metals including As, Cr, Cu, Cd, Ni, Mn, Pb, Zn and Fe. The heavy metals in PM were analyzed by ICP-MS. The results showed that average PM2.5 and PM10 were highest at NS (33.8 ±18.8 µg/m3) and OD (57.6 ±17.5 µg/m3), respectively. PM2.5 was …

Evaluation Of Landslide Occurrence Using Hydrological Model In Huai Nam Phung Subbasin, Thailand, Rugkiet Chansorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

Huai Nam Phung subbasin, which is located at the boundary between Loei and Phetchabun provinces, is the area where landslides occur frequently. Therefore, this study aims to evaluate the occurrence of landslides in this area by using the Digital Elevation Model (DEM), Meteorological data hydrological data and physical properties of soils processed with the Geographic Information System (GIS) to analyze the physical data of the study area and use the TOPography based hydrological MODEL (TOPMODEL) combined with the theory of factor of safety in slope stability to simulate the slope stability between 2016 and 2017. According to the satellite imageries …

Determining The Effective Authentication Factors Using Touchscreen Phones' Random Numeric Keypad, Nareerat Benjapatanamongkol

Chulalongkorn University Theses and Dissertations (Chula ETD)

For the past decade, the increased usage of touchscreen phone devices has driven the mobile application market that prompted the financial institutes to release their own mobile banking applications to better serve their customers. To date, there are two ways a Thai bank customer can access his/her account(s) via the mobile banking application i) using a 6-digit Personal Identification Number (PIN) or ii) using fingerprint. To help to strengthen the current PIN-only authentication which may be exposed to smudge and shoulder-surfing attacks, the research studied and determined the effective authentication factors using a random numeric keypad. The results from the …

Adaptive Matrix Multiplication For Various Degree Of Sparsity Using Tensorflow, Siraphob Theeracheep

Chulalongkorn University Theses and Dissertations (Chula ETD)

Matrix multiplication is a fundamental operation used in many problems, and many matrix multiplication algorithms are proposed for many computing environments. TensorFlow is a machine learning platform with many mathematic library functions including matrix multiplication. TensorFlow provides two methods, tf.matmul and tf.sparse_matmul, for matrix multiplication. It is suggested that tf.matmul should be used for dense matrices, and tf.sparse_matmul should be used for sparse matrices. In this work, an approach is proposed to improve the efficiency of matrix multiplication in TensorFlow. The proposed approach divides each matrix into four submatrices, and chooses either tf.matmul or tf.sparse_matmul for the multiplication of each …

Machine Reading Comprehension For Multiclass Questions On Thai Corpus, Theerit Lapchaicharoenkit

Chulalongkorn University Theses and Dissertations (Chula ETD)

Previous Thai question answering and machine reading comprehension researches focus on small scale dataset and do not utilize the deep learning approach to build the models. In this research, we develop a Thai machine reading comprehension (MRC) model on Thai MRC dataset provided by NECTEC. This dataset consists of 17,000 question-answer pairs and has two classes of questions, which are factoid and yes-no questions. We use BIDAF as the based MRC architecture. We have performed experiments with 3 different multiclass model designs, which includes special tokens, joint, and cascade model. We also utilize contextual embeddings for Thai language to enhance …

A Generative Adversarial Network For Generating Realistic Users Using Embedding From Recommendation Systems, Parichat Chonwiharnphan

Chulalongkorn University Theses and Dissertations (Chula ETD)

User data has been used by many companies to understand user behaviors and find new business strategies. However, common techniques could not be used when it comes to new products that have not yet been released due to the fact that there are no prior data available. In this work, we propose a framework for generating realistic user data on new products which can then be analyzed for insights. Our model uses Conditional Generative Adversarial Network (CGAN) with the Straight-Through Gumbel estimator which can also handle discrete-valued outputs. The CGAN is conditioned on product features learned using a recommendation system …

Thai Stock Return Prediction Using Deep Learning Models With Stock Indicators And Textual Features, Tanawat Chiewhawan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Stock prediction task is notoriously challenging due to the uncertainty and dynamic external factor which influence the stock behavior. Recently, Deep learning research is gaining popularity on this task but often focuses on only a particular type of data; numeric indicators or textual information. Moreover, most researches focus on only a single stock or a market index. In this paper, we aim to predict multiple stock returns using both types of data. The model consists of dual-stage attention recurrent neural network, our proposed stock relation inference framework, and textual features integration. The proposed stock relation inference help tackles multiple time-series …

Oxidation States Of Trace Elements In Synthetic Corundum, Ontima Yamchuti

Chulalongkorn University Theses and Dissertations (Chula ETD)

Natural and synthetic corundums have various colors due to trace elements in their structures. Despite the abundance of research on impurities in natural corundum, little is known about trace elements in synthetic corundum. This project is aimed to quantify trace elements and identify their oxidation states related to coloration in red, blue, and yellow synthetic corundums. A total of 15 corundums, synthesized by melt growth process, were investigated by advanced analytical techniques. X-ray diffraction results indicate that all synthetic corundums contain crystalline Al2O3. Measurements from Electron Probe Micro-Analyzer, UV-Vis-NIR, and X-ray Absorption Near Edge Structure spectrometry suggest that Cr3+ is …

Co-Creating Built Environment For Sustainable Development: A Case Study Of Ban Moh, Mahasarakham Province, Chainun Prompen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Co-creation has been used widely in many fields, including innovation design, service design, and district development. In Thailand, many development projects apply co-creation as an approach to development. However, the academic knowledge about co-creating built environment in Thailand is limited and remains unclear. Therefore, this study aims to understand the processes and practices of co-creating built environment in the context of Thailand through the description and analysis of cases. The four case studies described here include the Chantaboon riverfront community in Chantaburi Province, Ban Pred Nai community in Trat Province, Ban Mun Kong project in Samut Prakan Province, and Pru …

Policy For Sustainable Informal Transport - A Case Study Of Feeder Services In Bangkok, Thailand, Chutaporn Amrapala

Chulalongkorn University Theses and Dissertations (Chula ETD)

One informal public transport service in Bangkok is Silor (SR), given the meaning in Thai as four-wheeler. SR facilitates urban mobility both in terms of major travel mode and feeder bus and mass transit lines in the city. This research aims to investigate service characteristics and challenges of SR service, identify factors affecting the use and non-use of SR, explore travel behavior and attitudes to determine service delivery gaps in order to propose policy recommendations for the better functioning of SR service. Interviews are conducted through questionnaire survey to collect data from supply side, including drivers and regulators, and demand …

Evaluation Of Carbon Dioxide And Nitrate Utilization From Recirculating Aquaculture System For Microalgal Production, Kittikoon Sucunthowong

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study evaluated carbon dioxide and nitrate utilization from tilapia cultivating system by means of microalgal cultivation. The first part of this study evaluated the feasibility of using nitrate-rich effluent from aquaculture to cultivate Scenedesmus armatus in comparison with the cultivation using BG-11 media. Comparable biomass productivity and pigment content of S. armatus from the cultivation indicated that nitrate-rich effluent from aquaculture could be used as substitute for a more expensive BG-11 growth media. The second part of this study evaluated the feasibility of utilizing carbon dioxide concentrated air from roughly 3 kg/m3 tilapia cultured tank to grow S. armatus. …

Geological And Mineralogical Characteristics Of Pilok And Takua Pit Thong Tin-Tungsten Deposits, Western Thailand, Karn Phountong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Pilok and Takua Pit Thong mine were one of tin-tungsten mines associated with the Western Granitoid Belt. Despite the very poor condition of the outcrop, petrographic and geochemical studies reveal two granitoid units: porphyritic granite and equigranular granite, which show similar petrography characteristics except for tourmaline that appears only in equigranular granite, and their textures. Based on whole-rock geochemistry, porphyritic granite is ferroan to magnesian, alkalic, peraluminous granite whereas equigranular granite is ferroan to magnesian, alkali to alkali-calcic, peraluminous granite. Both granites show S-type affinity. The REE patterns show enrichment in LILE (e.g. K, Rb) and HFSE (e.g. Nb, Ta). …

Petrography And Geochemistry Of Volcanic Rocks In Khao Sam Sip Area, Sa Kaeo Province, Maythira Sriwichai

Chulalongkorn University Theses and Dissertations (Chula ETD)

The volcanic rocks at Khao Sam Sip, Sa Kaeo province is part of the Loei-Phetchabun-Sa Kaeo Volcanic Belt. Based on field observation, petrographic and geochemical studies, the rocks in the study area can be divided into four rock units namely, 1) Basalt-andesite unit, 2) Polymictic andesitic unit, 3) Epiclastic unit, and 4) Clastic unit. Unit 1 is the lowest unit in sequence consisting of olivine-pyroxene-plagioclase basalt, pyroxene basalt, hornblende-plagioclase andesite, and plagioclase andesite. Unit 2 consists of polymictic andesitic breccia and polymictic andesitic sandstone. Unit 3 is epiclastic unit comprising of crystal-lithic sandstone and polymictic conglomerate. Units 4 includes fine-grained …

Organic Geochemical Characteristics Of Coal Deposits In Lampang Province, Patthapong Chaiseanwang

Chulalongkorn University Theses and Dissertations (Chula ETD)

ถ่านหินและหินตะกอนจำนวน 31 ตัวอย่างจากแหล่งถ่านหินแม่ตีบและแหล่งถ่านหินแม่ทานที่ตั้งอยู่ในจังหวัดลำปางทางตอนเหนือของประเทศไทยถูกนำมาศึกษาลักษณะเฉพาะทางธรณีเคมีอินทรีย์ (Organic geochemistry) ผลจากการวิเคราะห์ปริมาณสารอินทรีย์ทั้งหมด (Total organic carbon) พบว่าตัวอย่างถ่านหินจากแหล่งแม่ตีบมีค่าระหว่าง 30.12 - 73.71 wt. % และสูงกว่าตัวอย่างถ่านหินของแหล่งแม่ทานซึ่งมีค่าระหว่าง 23.48 - 52.50 wt. % หินดินดานจากทั้งสองแหล่งมีค่าใกล้เคียงกันระหว่าง 4.82 - 19.49 wt. % ในแหล่งแม่ตีบ และ 14.00 - 24.87 wt. % ในแหล่งแม่ทาน ค่าที่น้อยที่สุดของปริมาณสารอินทรีย์ทั้งหมดปรากฏในตัวอย่างหินโคลนซึ่งมีค่าระหว่าง 0.88 – 4.92 wt. % ในแหล่งแม่ตีบ และค่าระหว่าง 0.59 – 5.98 wt. % การวิเคราะห์ปริมาณสารอินทรีย์ที่สกัดได้ (Extractable organic matter) ในตัวอย่างหินของแหล่งแม่ตีบมีค่าระหว่าง 1,277 - 9,764 ppm ในขณะที่ตัวอย่างหินของแหล่งแม่ทานมีค่ามากกว่าโดยอยู่ระหว่าง 1,256-16,421 ppm จากข้อมูลข้างต้นทั้งสองแหล่งมีศักยภาพการเป็นชั้นหินต้นกำเนิดของแหล่งปิโตรเลียมอยู่ในเกณฑ์ดีถึงดีเยี่ยมยกเว้นหินโคลนบางตัวอย่าง ข้อมูลลักษณะเฉพาะทางธรณีเคมีอินทรีย์ศึกษาจากแก๊สโครมาโตแกรม (Gas chromatogram) ได้มาจากการวิเคราะห์โดยใช้เครื่องมือแก๊สโครมาโตกราฟี-แมสสเปกโตมิเตอร์ (Gas chromatography-mass spectrometer) ซึ่งให้ข้อมูลของตัวชี้วัดทางชีวภาพ (Biomarker and non-biomarker) ที่มีประโยชน์ในการตีความทั้งระดับความพร้อมสมบูรณ์ (Maturity) ชนิดของอินทรีย์วัตถุ (Organic matter input) และสภาพแวดล้อมการสะสมตัวในอดีต (Depositional environment) ในการศึกษานี้ถ่านหินมีระดับความพร้อมสมบูรณ์เทียบเคียงกับระดับถ่านหิน (coal rank) อยู่ในระดับลิกไนต์ถึงบิทูมินัสสารระเหยสูงระดับซี (Lignite – high volatile bituminous C) อ้างอิงจากตัวชี้วัดความพร้อมสมบูรณ์ทางชีวภาพ (Biomarker maturity) ซึ่งบ่งชี้ว่าตัวอย่างหินมีระดับความพร้อมสมบูรณ์อยู่ในระดับตอนต้น (immature-early mature stage) แก๊สโครมาโตแกรมของแอลเคนสายตรง (n-alkanes) …