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2024

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Articles 13921 - 13950 of 14118

Full-Text Articles in Physical Sciences and Mathematics

Incorporating Effects-Based Approaches Into Environmental Impact Assessment To Improve Post-Development Monitoring, Carolyn J M Brown Jan 2024

Incorporating Effects-Based Approaches Into Environmental Impact Assessment To Improve Post-Development Monitoring, Carolyn J M Brown

Theses and Dissertations (Comprehensive)

Over the last 50 years, improvements in design of industrial facilities have significantly reduced environmental impacts. But impacts still occur and monitoring programs are the main mechanism to inform when modification/implementation of mitigation is needed. Informed decisions require adequate baseline (pre-development) data to predict impacts based on the development’s design and to understand when the post-development environment has changed. An adaptive monitoring plan provides an effective way to evaluate monitoring results and allow for proactive responses to environmental change before impacts become difficult or challenging to reverse. Unfortunately, baseline data gathered during an environmental impact assessment (EIA) is often inadequate …

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The Atiyah-Hitchin-Singer Theorem And An 8-Dimensional Generalization, Timothy Ponepal Jan 2024

The Atiyah-Hitchin-Singer Theorem And An 8-Dimensional Generalization, Timothy Ponepal

Theses and Dissertations (Comprehensive)

The Atiyah-Hitchin-Singer theorem states that the twistor almost complex structure on a certain S2 bundle over an oriented Riemannian 4-manifold (M, g) is integrable if and only if the Weyl curvature tensor of g is self-dual. These ideas were developed by Roger Penrose connecting 4-dimensional Riemannian geometry with complex geometry. We present a new approach to the Atiyah-Hitchin-Singer theorem using horizontal lifts and their respective flows, cross products and the quaternions to show that the Nijenhuis tensor vanishes if and only if the Weyl curvature tensor of g is anti-self-dual. An eight dimensional generalization is presented when the …

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Impacts Of Wildfire On Subcanopy Energy Balance, Thermal Regime, And Permafrost Stability In Peat Plateaus At Scotty Creek, Canada, Maude Auclair Jan 2024

Impacts Of Wildfire On Subcanopy Energy Balance, Thermal Regime, And Permafrost Stability In Peat Plateaus At Scotty Creek, Canada, Maude Auclair

Theses and Dissertations (Comprehensive)

The stability of permafrost in peatland-dominated regions of northwestern Canada is compromised by ongoing climate warming and increased wildfire activity. This study examines an 8-year record of changes to the surface and subsurface properties of a peat plateau following a low-severity wildfire that occurred in 2014 in a region of thawing, discontinuous permafrost. This is accomplished by comparing the burned portion of a peat plateau to two unburned control sites, one of which is the unburned portion of the same plateau that was affected by the fire. Net radiation was not significantly different one year following the wildfire but became …

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Recoloring In Hereditary Graph Classes: Structure And Decomposition, Manoj Belavadi Jan 2024

Recoloring In Hereditary Graph Classes: Structure And Decomposition, Manoj Belavadi

Theses and Dissertations (Comprehensive)

In this thesis we study reconfiguration problems in graph theory. A reconfiguration problem is generally defined on the solution space of a problem for which a configuration can be defined as a feasible solution, for example, a coloring of a graph. In Chapters 1 through 4 we study the reconfiguration of vertex colorings. The reconfiguration graph of the k-colorings, denoted Rk(G), is the graph whose vertices are the k-colorings of G and two colorings are adjacent in Rk(G) if they differ on exactly one vertex. The basic question investigated here …

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Road Extraction On Remote Sensing Imagery: Historical Mapping Of The Brazilian Amazon, Jonas Paiva Botelho Jr Jan 2024

Road Extraction On Remote Sensing Imagery: Historical Mapping Of The Brazilian Amazon, Jonas Paiva Botelho Jr

Graduate Theses/Dissertations

This work proposes an artificial intelligence model based on U-Net architecture to map road networks in the Brazilian Amazon. Over the years, the Amazon region has been heavily exploited, leading to increased deforestation rates, contributing to CO2 emissions, amplifying global warming, and causing a disturbance in local fauna and flora. The expansion into the forest by illegal miners, loggers, and land grabbers can be tracked down by the construction of roads, which we can refer to as the arteries of deforestation. Previous works on the matter proposed algorithms that use high-resolution imagery to map roads precisely. However, this work approach …

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Hydrogeomorphic Response Of Fluvial Systems To Climate Change - An Example From James River, Missouri, Afrida Aranya Jan 2024

Hydrogeomorphic Response Of Fluvial Systems To Climate Change - An Example From James River, Missouri, Afrida Aranya

Graduate Theses/Dissertations

Climate change has led to unpredictable hydrological patterns, significantly altering the fluvial environment and their flow regime. Despite extensive research, our knowledge about the impacts of climate change on flow regimes in the US Midwest is limited, particularly in karst-dominated fluvial landscapes. This research addresses this gap by investigating the effects of climatic change on the hydrogeomorphology of the James River, located in the karst-dominated Ozark Highlands in southwest Missouri, USA. The study focuses on two ~1.5 km stream segments—one relatively active and one stable in the context of geomorphology—near Springfield, Missouri. The research aims to (i) understand the changing …

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Context Detection With Word Embedding And Emotionally Relevant Keyword Search For Smart Home Environment, Brent Anderson Jan 2024

Context Detection With Word Embedding And Emotionally Relevant Keyword Search For Smart Home Environment, Brent Anderson

Graduate Theses/Dissertations

Voice-enabled virtual assistants have gained widespread popularity and are increasingly common in smart homes. To enhance customization and personalization in user experiences with these assistants, implementing a context detection feature is beneficial. This feature enables the virtual assistant to gather more information from the audio data of short voice conversations with users, helping it maintain awareness of the conversation and respond more aptly. In this thesis, I propose a novel context detection approach for virtual assistants in smart homes, named WERKS, which leverages user emotions. WERKS stands for word embedding with emotionally relevant keyword search. The WERKS approach incorporates emotion …

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Origin Of Carbonate Mud Mounds In Southwestern Missouri, Jared Mcavoy Jan 2024

Origin Of Carbonate Mud Mounds In Southwestern Missouri, Jared Mcavoy

Graduate Theses/Dissertations

Small carbonate mud mounds are found in Lower Mississippian strata of southwestern Missouri. These compare favorably with larger mounds, known as Waulsortian mounds, located in the Meuse River valley of southern Belgium. The origin of Waulsortian and similar mounds is unknown, but they commonly are interpreted as accumulations of mud, where the presence of biological organisms responsible for supposed bio-construction remains uncertain. Alternative hypotheses are that these may have been non-cohesive slump or cohesive slide masses. Multiple techniques, including δ13C and δ18O isotopic analyses and unmanned aerial vehicle photography, were used to determine the most feasible working hypothesis. Determining the …

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Scene Understanding And Spatial Analysis Using Scene Graph Enhanced By Hall's Proxemics Zones In Smart Homes, Debaleen Das Spandan Jan 2024

Scene Understanding And Spatial Analysis Using Scene Graph Enhanced By Hall's Proxemics Zones In Smart Homes, Debaleen Das Spandan

Graduate Theses/Dissertations

Voice-controlled smart assistants have received widespread popularity. It plays a pivotal role in smart homes by providing a natural and convenient interface for interacting with smart devices. However, these assistants are unable to serve persons with physical disabilities and speech impairments. Therefore, non-verbal communication methods, such as eye tracking, gesture recognition, and context awareness can complement and overcome some of these limitations to enhance user experience in smart homes. To address this issue, I am investigating non-verbal communication methods to make smart home technology more accessible and intuitive. In this research, I focus on proxemics, i.e., the study of distance …

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Bank Erosion Dynamics In Response To Anthropogenic Disturbances In The Cuivre River Watershed Of Missouri, Usa, Nathan Douglas Sines Jan 2024

Bank Erosion Dynamics In Response To Anthropogenic Disturbances In The Cuivre River Watershed Of Missouri, Usa, Nathan Douglas Sines

Graduate Theses/Dissertations

Riverbank erosion is increasingly recognized as a pressing issue exacerbated by human activities. The Cuivre River, a tributary of the Mississippi River, located in northeast Missouri, has limited documentation on bank erosion, with the most recent study conducted in the early 1990s. This research aims to fill this gap by exploring the stream bank erosion dynamics from 1816 to 2015. The objectives are to: (i) understand the channel width dynamics for 1816 to 1994 ii) determine the sediment erosion and deposition volume along the riverbank in the period of 1994 to 2015. iii) identify the anthropogenic disturbances particularly land use …

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Million-Year Melt-Presence In Mogollon-Datil Volcanic Field Rhyolites: Constraining The Histories Of The Bursum Caldera Resurgent Domes, Ethan Wagner Jan 2024

Million-Year Melt-Presence In Mogollon-Datil Volcanic Field Rhyolites: Constraining The Histories Of The Bursum Caldera Resurgent Domes, Ethan Wagner

Graduate Theses/Dissertations

The Mogollon-Datil volcanic field which is located in southwestern New Mexico, is the result of punctuated volcanism and the transition between arc and rift magmatism. The resurgent domes within the 28 Ma Bursum caldera records the transition from rhyolitic to basaltic andesite volcanism that occurred between 27-26 Ma. Using a combination of new zircon U-Pb ages using chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) with zircon U-Pb geochronology and trace element contents by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and whole rock and mineral trace element contents and isotope geochemistry this study investigates the temporal and …

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Introducing Ordered Silicon Vacancies Into Wsi2, Grace M. Atkins Jan 2024

Introducing Ordered Silicon Vacancies Into Wsi2, Grace M. Atkins

Graduate Theses/Dissertations

Thermoelectric materials are very useful in industry due to their unique ability to convert waste heat into electricity. One such reported thermoelectric material is rhenium silicide (ReSi1.75▯0.25), resulting from ordered silicon vacancies in its crystal structure. The purpose of this project is to dope tungsten silicide (WSi2) with more electron rich elements to find a ternary silicide with a similar crystal structure to ReSi1.75▯0.25, in order to synthesize a less expensive thermoelectric material. Two synthesis methods are used in this project to dope WSi2. Powder x-ray diffraction (XRD) …

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Optimizing Sports Outcome Prediction Through Feature Engineering And Machine Learning, Vitor S. Freitas Jan 2024

Optimizing Sports Outcome Prediction Through Feature Engineering And Machine Learning, Vitor S. Freitas

Graduate Theses/Dissertations

The challenge of predicting the outcome of a team game lies in the high complexity and dynamics of the sports data. This thesis focuses on the aspect of using feature engineering and the genetic algorithm to predict the winner and the score of various sports events. Generally, it deals with how machine learning algorithms are combined with state-of-the-art feature engineering techniques in sports datasets derived from various sports disciplines. In this thesis, five different machine learning models have been applied, classification and regression trees (CART), random forest (RF), stochastic gradient boosting (SGB), eXtreme gradient boosting (XGBoost), and extreme learning machine …

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Influences Of Shape Of Plasmonic Gold Nanoparticles Decorated On Titanium Dioxide For Photo-Oxidation Of Benzyl Alcohol, Naritsara Kornkanlaya Jan 2024

Influences Of Shape Of Plasmonic Gold Nanoparticles Decorated On Titanium Dioxide For Photo-Oxidation Of Benzyl Alcohol, Naritsara Kornkanlaya

Chulalongkorn University Theses and Dissertations (Chula ETD)

The composite of gold nanoparticles (AuNPs) and titanium dioxide (TiO2) has been extensively utilized to enhance photocatalytic activity due to the localized surface plasmon resonance (LSPR) effect of AuNPs, which improves TiO2 photocatalytic performance. This study investigates the shape effect of AuNPs on TiO2-MPTMS surface for the aerobic photo-oxidation of benzyl alcohol. AuNPs with spherical, rod, and star shapes were synthesized by controlling plasmonic absorption within the 500-600 nm region and subsequently decorated on the TiO2-MPTMS surface via a deposition-precipitation method to compare their photocatalytic activity. The aerobic oxidation of benzyl alcohol was performed under 300 W Xe lamp irradiation …

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Electromembrane Extraction With Flat Sheet Membrane For Determination Of Chromium(Vi), Preenapa Saengaroon Jan 2024

Electromembrane Extraction With Flat Sheet Membrane For Determination Of Chromium(Vi), Preenapa Saengaroon

Chulalongkorn University Theses and Dissertations (Chula ETD)

An electromembrane extraction with a flat sheet membrane platform was developed for colorimetric detection of chromium(VI). This study designed an electromembrane extraction device using a simple flat sheet membrane with an open area to reduce the effect of gas generation from the electrolysis reaction. In addition, a 1,5-diphenylcarbazide (DPC) colorimetric reagent for Cr(VI) was introduced into the acceptor phase to improve the mass transfer of Cr(VI) by simultaneously reacting with the transferred Cr(VI) facilitating the driving force due to concentration gradient in the acceptor phase. When a voltage was applied, the analytes were extracted, transferred from the sample solution (donor …

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Key Factor Analysis For Base Patterns In Minibridge By Reinforcement Learning, Thanathat Dechakulkamjorn Jan 2024

Key Factor Analysis For Base Patterns In Minibridge By Reinforcement Learning, Thanathat Dechakulkamjorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

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Specifying The Desired Attributes Of Solutions To Vehicle Routing Problems With Time Windows Using Machine Learning, Teerapong Chaochanglek Jan 2024

Specifying The Desired Attributes Of Solutions To Vehicle Routing Problems With Time Windows Using Machine Learning, Teerapong Chaochanglek

Chulalongkorn University Theses and Dissertations (Chula ETD)

A vehicle routing problem with time windows (VRPTW) has been studied widely in the literature. Most effective methods to find a solution are still heuristics, which are constructed from the inventor’s ideas of how a good solution should be obtained, and their efficiency is quantified only by empirical data. However, these ideas may or may not yield a near-optimal solution. It would be better if we can identify some characteristics of a solution to VRPTW to help guide the heuristic in the right direction. Arnold and Sörensen had proposed a statistical learning model to determine a characteristic of a near-optimal …

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การเพิ่มปริมาณของกรดโอเลอิกในน้ำมันปาล์มผ่านอินเทอร์เอสเทอริฟิเคชันเชิงเคมีเพื่อการประยุกต์เป็นน้ำมันหม้อแปลงไฟฟ้าชีวภาพ, ณฐพร อินคง Jan 2024

การเพิ่มปริมาณของกรดโอเลอิกในน้ำมันปาล์มผ่านอินเทอร์เอสเทอริฟิเคชันเชิงเคมีเพื่อการประยุกต์เป็นน้ำมันหม้อแปลงไฟฟ้าชีวภาพ, ณฐพร อินคง

Chulalongkorn University Theses and Dissertations (Chula ETD)

น้ำมันปาล์มเป็นพืชเศรษฐกิจสำคัญของไทยและได้รับการส่งเสริมจากรัฐบาลให้มีการเพิ่มมูลค่าโดยการใช้น้ำมันปาล์มเป็นวัตถุดิบสำหรับผลิตน้ำมันหม้อแปลงไฟฟ้าชีวภาพซึ่งเป็นทางเลือกที่เป็นมิตรต่อสิ่งแวดล้อม โดยทั่วไปน้ำมันหม้อแปลงที่ใช้ในปัจจุบันทำจากน้ำมันแร่ซึ่งมีสมบัติทางไฟฟ้าและความร้อนที่ดี แต่มีจุดวาบไฟและจุดติดไฟต่ำ ไม่สามารถย่อยสลายได้ทางชีวภาพและเป็นพิษต่อสิ่งแวดล้อม ขณะที่น้ำมันปาล์มจุดเด่นเกี่ยวกับประเด็นด้านสิ่งแวดล้อม อีกทั้งมีจุดวาบไฟและจุดติดไฟสูงกว่าน้ำมันแร่ แต่มีค่าความหนืดและจุดไหลเทสูงไม่เหมาะกับการนำมาใช้งานเป็นน้ำมันหม้อแปลง ดังนั้นงานวิจัยนี้จึงมุ่งเน้นการปรับปรุงโครงสร้างไตรเอซิลกลีเซอรอลของน้ำมันปาล์มโดยเพิ่มปริมาณกรดไขมันไม่อิ่มตัวในโครงสร้างด้วยปฏิกิริยาอินเทอร์เอสเทอริฟิเคชันเชิงเคมี (chemical interesterification, CIE) และกระบวนการแยกส่วนแบบแห้ง พบว่าเมื่อใช้อัตราส่วนปาล์มโอเลอีนต่อเมทิลโอลีเอตเท่ากับ 50:50 โดยน้ำหนัก ตัวเร่งปฏิกิริยาโซเดียมเมทอกไซด์ 0.5% โดยน้ำหนักเทียบกับสารตั้งต้น เวลาในการทำปฏิกิริยา 1.5 ชม. และอุณหภูมิในการทำปฏิกิริยาที่ 110 องศาเซลเซียส ให้ผลิตภัณฑ์ไตรเอซิลกลีเซอรอล (triacylglycerol, TAG) ที่มีหมู่เอซิลแบบไม่อิ่มตัวเพิ่มขึ้น ได้แก่ กลุ่มที่มีคาร์บอน 52 (TAG-C52) และ 54 (TAG-C54) มีปริมาณเพิ่มขึ้นจาก 43.45% เป็น 44.93% และจาก 10.74% เป็น 27.74% ตามลำดับ นอกจากนี้กระบวนการแยกส่วนแบบแห้งช่วยเพิ่มสัดส่วนความไม่อิ่มตัวในผลิตภัณฑ์จาก CIE โดยการแยกส่วนแบบแห้ง ณ อุณหภูมิ 0 องศาเซลเซียส เวลา 72 ชั่วโมง ให้ผลิตภัณฑ์ส่วนของเหลวที่มีปริมาณ TAG-C52 และ TAG-C54 เพิ่มขึ้นเป็น 49.90% และ 31.76% ตามลำดับ ส่งผลให้ค่าความหนืดและจุดไหลเทของผลิตภัณฑ์ลดลงจากก่อนทำปฏิกิริยา ที่ 13.59 เป็น 10.55 เซนติสโตกส์ และจุดไหลเทมีค่าลดลงจาก -5 องศาเซลเซียส เป็น -5.5 องศาเซลเซียส

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Simulation Of Optimal Control Of Vaccination For Svihr Covid-19 Epidemic Model, Kantanop Yimfan Jan 2024

Simulation Of Optimal Control Of Vaccination For Svihr Covid-19 Epidemic Model, Kantanop Yimfan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Infectious disease modeling plays a crucial role in understanding and managing epidemic outbreaks. Mathematical models, combined with control strategies, can help guide effective interventions and policy making. In this study, we examined an epidemic model, so-called SV IHR, which is an extended SIR model with additional states to incorporate vaccination and treatment. Our goal is to determine parameters known as controls; specifically, the vaccination proportion, through the framework of the optimal control problems. We defined an objective function and explored the control strategies that optimize it. Numerical simulations were then performed to illustrate the dynamics of the epidemic both with …

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New Fluorescent Sensors Based On Thiazolinyl Quinoline Derivatives For Metal Ion Detection, Kavisara Srithadindang Jan 2024

New Fluorescent Sensors Based On Thiazolinyl Quinoline Derivatives For Metal Ion Detection, Kavisara Srithadindang

Chulalongkorn University Theses and Dissertations (Chula ETD)

Heavy metals can severely impact human health by causing neurotoxicity and other serious disorders at high concentrations. This dissertation focuses on developing chemosensors designed for the selective detection and measurement of Cu2+ and Zn2+, two of the most abundant heavy metals on earth. The initial section outlines the design, synthesis, and characterization of four novel fluorescent sensors (8-TQ1, 2-TQ2, 3-TQ2, and 8-TQ2). Conceptually, these probes are designed to possess an aminoquinoline scaffold linked with a thiazoline unit as a receptor to enable selective metal ion detection. 8-TQ1 probe, which features a secondary amine group within its structure and is connected …

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Gemstone Identification By Raman Spectroscopy Combined With Chemometric Methods, Nontawat Sricharoen Jan 2024

Gemstone Identification By Raman Spectroscopy Combined With Chemometric Methods, Nontawat Sricharoen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Accurate and reliable gemstone classification is critical in gemology for authentication and identification purposes. A one-class classifier using self-organizing maps (SOMs), combined with Monte Carlo permutation testing, was successfully developed for gemstone classification based on Raman spectroscopy data. The developed SOM model was optimized by adjusting the map size and training iteration counts, and Monte Carlo permutation tests were conducted to evaluate prediction score through empirical p-values by generating random permutations of the data, allowing for a statistically robust assessment of classification reliability. Using the Raman spectra of RRUFF database and certain garnet gemstones, the model demonstrated high classification accuracy …

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Enhance Gnn-Based Social Recommendation Using User Dynamic Characteristics, Janekhwan Kitsupapaisan Jan 2024

Enhance Gnn-Based Social Recommendation Using User Dynamic Characteristics, Janekhwan Kitsupapaisan

Chulalongkorn University Theses and Dissertations (Chula ETD)

In recent developments, social recommendation frameworks have increasingly employed Graph Neural Networks (GNNs) to model social connections among users, encompassing both immediate and more distant relationships within the network. Nonetheless, current advanced models encounter challenges related to the limited number of propagation steps they can perform on the graph. Messages originating from distant nodes often diminish the distinct features of the target user, resulting in more homogeneous representations that are difficult to differentiate. This issue is known as over-smoothing. Several approaches have been proposed to address this, aiming to preserve individual user traits by incorporating auxiliary information into GNN-based models. …

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Relationship Between Hotspot And Geography – Meteorology Factors In Thailand And Neighboring Countries, Thanchanok Ngernted Jan 2024

Relationship Between Hotspot And Geography – Meteorology Factors In Thailand And Neighboring Countries, Thanchanok Ngernted

Chulalongkorn University Theses and Dissertations (Chula ETD)

Air pollution is a critical issue in many countries and has become a significant problem in Southeast Asia. Wildfires, agricultural burning, and biomass burning are major sources of pollution emissions. This study aims to analyze hotspot activity and study the relationship between hotspots and geographic-meteorological factors in Thailand and neighboring countries. MODIS hotspot data were analyzed using the frequency-magnitude distribution (FMD) and geography-meteorology factors. The results indicate that areas with high hotspot activity were mainly found in northwestern to eastern Cambodia and northern Laos. Additionally, northern Laos and some pockets in Myanmar showed high hotspot intensity, capable of generating a …

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Environmental Reconstruction In Nong Thale Pron, Nakhon Si Thammarat Province, Kanokpon Surijamorn Jan 2024

Environmental Reconstruction In Nong Thale Pron, Nakhon Si Thammarat Province, Kanokpon Surijamorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

Climate change is one of the major factors influencing environmental changes. The study of proxies from geological records can extend climate data into the past, enabling the reconstruction of past environmental changes. This study collected sediment cores from three points at the deepest part of Nong Thale Pron, Nakhon Si Thammarat Province. The sediment core NTP-CP6 was selected for analysis using X-ray fluorescence (XRF), radiocarbon dating, grain size analysis, total organic carbon, total nitrogen, stable carbon isotopes, and n-alkanes. During the Last Glacial Maximum (21–19 ka BP), dry conditions were caused by a strong northeast monsoon and the exposure of …

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Computational Fluid Dynamics And Artificial Neural Network Based Modeling Of Microplastics Seperation Using Hydrocyclone, Dulyapat Thiemsakul Jan 2024

Computational Fluid Dynamics And Artificial Neural Network Based Modeling Of Microplastics Seperation Using Hydrocyclone, Dulyapat Thiemsakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Microplastics represent a considerable environmental hazard, particularly to aquatic ecosystems. These particles can adversely impact marine organisms and infiltrate the food chain, potentially posing risks to human health. Due to their small size and ubiquitous distribution, the removal of microplastics from water presents a significant technical challenge. This study focuses on the separation of microplastics using hydrocyclones. A three-dimensional Eulerian–Eulerian computational fluid dynamics (CFD) model was used to investigate this process. The model showed strong agreement with experimental data in terms of pressure drop, water split, and axial velocity, confirming the reliability of the simulation results. In this work, design …

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Boundaries Of Overlapping Isosceles Triangles, Kirati Sriamorn Jan 2024

Boundaries Of Overlapping Isosceles Triangles, Kirati Sriamorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

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Debris Flow And Flood Susceptibility Assessment In Phang-Nga Province, Southern Thailand, Aksara Kulsilarak Jan 2024

Debris Flow And Flood Susceptibility Assessment In Phang-Nga Province, Southern Thailand, Aksara Kulsilarak

Chulalongkorn University Theses and Dissertations (Chula ETD)

Phang-nga, a province in Southern Thailand, is highly susceptible to geohazards such as debris flows and flooding, both of which pose significant risks to human life and property. Two major topographic factors contribute to the potential for debris flow: i) steep mountain slopes and ii) the presence of multiple mountain-front outlets. This study presents the creation of susceptibility maps for debris flow and flood hazards in Phang-nga, using the Frequency Ratio (FR) method. The analysis classified the region into five susceptibility levels: very low, low, moderate, high, and very high, based on natural break classification. For debris flow, moderate susceptibility …

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การสังเคราะห์คาร์บอนดอตจากยางธรรมชาติโดยใช้ไพโรไลซิสด้วยไมโครเวฟและการประยุกต์ในทางด้านการตรวจจับสีย้อม, ธนาธิป สิทธิโชติ Jan 2024

การสังเคราะห์คาร์บอนดอตจากยางธรรมชาติโดยใช้ไพโรไลซิสด้วยไมโครเวฟและการประยุกต์ในทางด้านการตรวจจับสีย้อม, ธนาธิป สิทธิโชติ

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในงานวิจัยนี้วัสดุเรืองแสงประเภทคาร์บอนดอต (CDs) ถูกสังเคราะห์จากยางธรรมชาติและแอมโมเนียมเปอร์ซัลเฟต ด้วยใช้การไพโรไลซิสด้วยไมโครเวฟ (microwave-assisted pyrolysis) CDs ที่สังเคราะห์ได้มีการเรืองแสงฟลูออเรสเซนต์สีฟ้าแกมเขียวภายใต้แสงยูวี การพิสูจน์เอกลักษณ์ของ CDs ถูกวิเคราะห์โดยกล้องจุลทรรศน์อิเล็กตรอนแบบส่องผ่าน เครื่องวิเคราะห์หาขนาดของอนุภาค เครื่องวิเคราะห์การเลี้ยวเบนของรังสีเอกซ์ อินฟราเรดแบบฟูเรียร์ทรานส์ฟอร์มสเปกโตรมิเตอร์ ยูวี-วิสิเบิลสเปกโตรมิเตอร์ และฟลูออเรสเซนต์สเปกโตรมิเตอร์ โดยขนาดอนุภาคของ CDs ที่สังเคราะห์ได้มีขนาดเล็กกว่า 5 นาโนเมตร และแสดงสมบัติเชิงแสงที่ดี นอกจากนี้ศึกษาผลของตัวทำละลาย (ฟอร์มาไมด์และไดเมทิลฟอร์มาไมด์) และตัวเติมไนโตรเจน (ยูเรีย พอลีเอทิลีนอิมีน และ แอล-ทริปโตเฟน) ที่มีผลต่อการสังเคราะห์ CDs พบว่าการกระจายตัวของ CDs ในไดเมทิลฟอร์มาไมด์ดีกว่าฟอร์มาไมด์ จากผลการเติมไนโตรเจน 3 ประเภท ค่าการเรืองแสง และควอนตัมยิลด์สูงสุดของ CDs ได้มาจากการเติมยูเรีย จากนั้นนำ CDs ที่ได้มาประยุกต์ใช้ในการตรวจจับสีย้อมซูดาน I พบว่าการเรืองแสงฟลูออเรสเซนต์ของ CDs สามารถถูกยับยั้งได้ด้วยการเติมซูดาน I โดยมีขีดจำกัดการตรวจจับที่ 0.15 ไมโครโมลาร์ ดังนั้น CDs ที่เตรียมได้ในงานวิจัยนี้สามารถใช้เป็นเซนเซอร์สำหรับการตรวจจับซูดาน I ในพริกป่นได้

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Nanofluid Flow Behavior And Heat Exchange In Polymer Based Microchannel Heat Exchanger Using Computational Fluid Dynamics And Fluid-Structure Interaction, Chaiyanan Kamsuwan Jan 2024

Nanofluid Flow Behavior And Heat Exchange In Polymer Based Microchannel Heat Exchanger Using Computational Fluid Dynamics And Fluid-Structure Interaction, Chaiyanan Kamsuwan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Energy is the main factor that driving human society for century, but rapid growth of population tends to raise world energy demand. Many researchers suggest many ideas such as using new energy resources and alternative energies. However, an interested alternative is to utilize waste heat from flue gas. To utilize energy embedded in the flue gas, two challenges remaining include their low heat potential in 100 – 200 oC and corrosion risk in the equipment due to corrosive gas such as CO2 and H2S. To encounter the challenges polymer-based microchannel heat exchanger (PMHE) was developed for reutilizing waste heat in …

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Biological Fluorescence Sensor Derived From Naphthalimide-Functionalized Pillar[5]Arene, Yanisa Sanguansap Jan 2024

Biological Fluorescence Sensor Derived From Naphthalimide-Functionalized Pillar[5]Arene, Yanisa Sanguansap

Chulalongkorn University Theses and Dissertations (Chula ETD)

Lung cancer has unavoidably encountered the most substantial fatality rate in recent years worldwide. The development of efficient and accessible diagnostic methods is required to assess disease severity. Prior studies have discovered the highest levels of long-chain aldehyde compounds particularly octanal (C8), nonanal (C9), and L-glutathione (L-GSH) as potential biomarkers for lung cancer. Herein, the novel artificial fluorescence sensor HNP5A containing bis-hydrazine naphthalimide decorated pillar[5]arene and 1,2-bis(6-bromohexyl)disulfane (BS) containing a disulfide part linked to a terminal bromoalkane were designed for two conceptual approaches. The first concept, sensor HNP5A has been accomplished for sensitive and selective detection of long-chain aldehydes. This …

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