Physical Sciences and Mathematics Commons^™

A Survey On Sentiment Analysis In Urdu: A Resource-Poor Language, Asad Khattak, Muhammad Zubair Asghar, Anam Saeed, Ibrahim A. Hameed, Syed Asif Hassan, Shakeel Ahmad

All Works

© 2020 Background/introduction: The dawn of the internet opened the doors to the easy and widespread sharing of information on subject matters such as products, services, events and political opinions. While the volume of studies conducted on sentiment analysis is rapidly expanding, these studies mostly address English language concerns. The primary goal of this study is to present state-of-art survey for identifying the progress and shortcomings saddling Urdu sentiment analysis and propose rectifications. Methods: We described the advancements made thus far in this area by categorising the studies along three dimensions, namely: text pre-processing lexical resources and sentiment classification. These …

Accurate Segmentation Of Cerebrovasculature From Tof-Mra Images Using Appearance Descriptors, Fatma Taher, Ahmed Soliman, Heba Kandil, Ali Mahmoud, Ahmed Shalaby, Georgy Gimel'farb, Ayman El-Baz

All Works

© 2013 IEEE. Analyzing cerebrovascular changes can significantly lead to not only detecting the presence of serious diseases e.g., hypertension and dementia, but also tracking their progress. Such analysis could be better performed using Time-of-Flight Magnetic Resonance Angiography (ToF-MRA) images, but this requires accurate segmentation of the cerebral vasculature from the surroundings. To achieve this goal, we propose a fully automated cerebral vasculature segmentation approach based on extracting both prior and current appearance features that have the ability to capture the appearance of macro and micro-vessels in ToF-MRA. The appearance prior is modeled with a novel translation and rotation invariant …

The Subconstituent Algebra Of A Hypercube, Jared B. Billet

UNF Graduate Theses and Dissertations

We study the hypercube and the associated subconstituent algebra. Let Q_D denote the hypercube with dimension D and let X denote the vertex set of Q_D. Fix a vertex x in X. We denote by A the adjacency matrix of Q_D and by A* = A*(x) the diagonal matrix with yy-entry equal to D − 2i, where i is the distance between x and y. The subconstitutent algebra T = T(x) of Q_D with respect to x is generated by A and A* . We show that A 2A* − 2AA*A + A*A 2 = 4A* A*2A − 2A*AA* + …

Harmonic Morphisms With One-Dimensional Fibres And Milnor Fibrations, Murphy Griffin

UNF Graduate Theses and Dissertations

We study a problem at the intersection of harmonic morphisms and real analytic Milnor fibrations. Baird and Ou establish that a harmonic morphism from G: \mathbb{R}^m \setminus V_G \rightarrow \mathbb{R}^n\setminus \{0\} defined by homogeneous polynomials of order p retracts to a harmonic morphism \psi|: S^{m-1} \setminus K_\epsilon \rightarrow S^{n-1} that induces a Milnor fibration over the sphere. In seeking to relax the homogeneity assumption on the map G, we determine that the only harmonic morphism $\varphi: \mathbb{R}^m \setminus V_G \rightarrow S^{m-1}\K_\epsilon$ that preserves \arg G is radial projection. Due to this limitation, we confirm Baird and Ou's result, yet establish …

Maximality And Applications Of Subword-Closed Languages, Rhys Davis Jones

UNF Graduate Theses and Dissertations

Characterizing languages D that are maximal with the property that D^* ⊆ S^⊗ is an important problem in formal language theory with applications to coding theory and DNA codewords. Given a finite set of words of a fixed length S, the constraint, we consider its subword closure, S^⊗, the set of words whose subwords of that fixed length are all in the constraint. We investigate these maximal languages and present characterizations for them. These characterizations use strongly connected components of deterministic finite automata and lead to polynomial time algorithms for generating such languages. We prove that …

Water-Mediated Peptide Bond Formation In The Gas Phase: A Model Prebiotic Reaction, George C. Shields, Ariel Gale, Tuguldur T. Odbadrakh, Tyler Ball

Chemistry Publications

The emergence of life on the prebiotic Earth must have involved the formation of polypeptides, yet the polymerization of amino acids is thermodynamically unfavorable under biologically relevant aqueous conditions because amino acids are zwitterions in solution and because of the production of a water molecule through a condensation reaction. Many mechanisms for overcoming this thermodynamic unfavorability have been proposed, but the role of gas phase water clusters has not been investigated. We present the thermodynamics of the water-mediated gas phase dimerization reaction of glycine as a model for the atmospheric polymerization of amino acids prior to the emergence of biological …

A Proposed Mechanism To Induce Multi-Layer Polydiacetylene-Coated Filter Color Response To Bacteria , Timothy Hanks

Chemistry Publications

The purpose of this study was to develop a multi-layer diacetylene (PDA)-coated filter and to verify the proposed color response mechanism of PDA-coated filters to bacteria. Unlike other reports which immobilize PDA lipo- somes on solid support or create monolayer Langmuir films, multi-layer PDA-coated filters were generated by directly evaporating organic solvents. Different from incorporating functional headgroups or inserting phospho- lipids into PDA, we reported that bacterial growth can trigger the color change of PDA sensors without any mod- ification or phospholipid insertion. The mechanism that pH change from bacteria metabolites lead to color change of PDA filter was proposed …

Particle Formation And Surface Processes On Atmospheric Aerosols: A Review Of Applied Quantum Chemical Calculations, George C. Shields, Ariel Gale, Tyler Ball, Tuguldur T. Odbadrakh, Angelini Leonardi, Heather M. Ricker, Juan G. Navea

Chemistry Publications

Aerosols significantly influence atmospheric processes such as cloud nucleation, het- erogeneous chemistry, and heavy-metal transport in the troposphere. The chemical and physical complexity of atmospheric aerosols results in large uncertainties in their climate and health effects. In this article, we review recent advances in scientific understanding of aerosol processes achieved by the application of quantum chemical calculations. In particular, we emphasize recent work in two areas: new particle for- mation and heterogeneous processes. Details in quantum chemical methods are pro- vided, elaborating on computational models for prenucleation, secondary organic aerosol formation, and aerosol interface phenomena. Modeling of relative humidity effects, …

The Impacts Of Accessibility On Vulnerability Of Place In Comfort Castle, Jamaica, Heather Thole

Dissertations, Master's Theses and Master's Reports

Jamaica experiences meteorological, hydrological, and geological natural hazards that can produce island-wide impacts. The island’s exposure to multiple hazard types requires effective and sustainable mitigation and disaster risk management to lessen potential impacts, especially for vulnerable populations and communities. Comfort Castle, a small rural farming community, sits in the upper Rio Grande Valley of Portland parish and experiences earthquakes, landslides, hurricanes, heavy rainfall, and floods. Steep terrain and remoteness due to geographic location affect the community’s geophysical vulnerability. Their social vulnerability results from a lack of employment, health, educational, and livelihood resources within the community. Together, geophysical, and social factors …

Optical Dispersion Relations From Three-Dimensional Chiral Gold Nanocubes In Periodic Arrays, Manpreet Boora

Dissertations, Master's Theses and Master's Reports

Chiral metamaterials are artificially tailored materials that are composed of nanoparticles that lack in-plane mirror symmetry. Application of chirality to plasmonic nanostructures can lead to chiro-optical effects such as asymmetric transmission of circularly polarized light, circular dichroism and optical activity. When light is incident on metallic nanoparticles, conduction electrons undergo collective oscillations within the nanoparticles, resulting in localized surface plasmon (LSP) resonance. Surface lattice resonances (SLRs) are hybrid plasmonic-photonic modes arising from the radiative coupling between LSPs and electromagnetic waves diffracted in the plane of the periodic array. Because of the collective dipole interactions, SLRs have less radiative losses compared …

The Stained Glass Of Knowledge: On Understanding Novice Mental Models Of Computing, Briana Christina Bettin

Dissertations, Master's Theses and Master's Reports

Learning to program can be a novel experience. The rigidity of programming can be at odds with beginning programmer's existing perceptions, and the concepts can feel entirely unfamiliar. These observations motivated this research, which explores two major questions: What factors influence how novices learn programming? and How can analogy by more appropriately leveraged in programming education?

This dissertation investigates the factors influencing novice programming through multiple methods. The CS1 classroom is observed as a "whole system", with consideration to the factors present in it that can influence the learning process. Learning's cognitive processes are elaborated to ground exploration into specifically …

The Effect Of Spacing Of Vetiver Grass (Chrysopogon Zizanioides) Hedgerows On Hillslope Erosion In Eastern Region, Ghana, Evan R. Lanese

Dissertations, Master's Theses and Master's Reports

Soil erosion in Ghana negatively effects many small holder farmers due to heavy rainfall, continuous land use, and a changing climate. Inexpensive, local, and sustainable practices that can be used to reduce soil movement thus building productive soils would benefit farmers in Ghana. Vetiver grass (Chrysopogon zizanioides) has been used to this effect worldwide. Its local availability and positive reputation leaves desire to learn about its applicability in Ghana. A field study was conducted on plots of sloping farmland (10ft by 60ft) with three treatments: (1) control with no vetiver grass, (2) two vetiver grass hedgerows, (3) four …

Physical Modeling Of The Krauklis Waves: Insights From Two Experimental Apparatuses, Haitao Cao

Dissertations, Master's Theses and Master's Reports

Fractures play an important role in the geological related processes such as hydraulic fracturing, water-water disposal, and volcanic earthquake. Seismic waves can provide useful information from fractures at a relatively low cost. In particular, the acoustic property of fractures containing magmatic or hydrothermal fluids can provide useful information about the fracture size and the fluid composition within the fracture. For instance, in volcanology, the resonant frequency of long-period events that are linked to crack interface waves is used to obtain fluid properties of cracks in magmatic systems. However, in order to rely on seismic data, they should be precisely characterized …

Understanding The Mechanisms Controlling The Concentration-Discharge Relationships Of Streams In Northeastern And North Midwestern United States, Veronica Porter

Dissertations, Master's Theses and Master's Reports

Analysis of concentration-discharge (C-Q) power-law relationships (C=aQ^b) is a powerful diagnostic tool to unravel solute export processes. However, application to watersheds with less intensive data can be difficult due to unexplained variation in C-Q behavior. To tackle this problem, I started my study at a small but data-intensive watershed in Vermont and then applied the insights to 138 watersheds throughout the Great Lakes Basin (GLB). I found that an increase in solute concentrations from shallow to deep flowpaths results in chemodynamic dilution (negative b-coefficient), a decrease produces chemodynamic flushing (positive b-coefficient). When applied …

Rain Generated Lahars Prior To The 2018 Catastrophic Eruption Of Fuego Volcano, Guatemala, Claudia Buondonno

Dissertations, Master's Theses and Master's Reports

Fuego volcano is one of the most active and hazardous volcanoes in the world. It is located in the northern part of the Central American Volcanic Arc in Guatemala and its activity can be characterized by long term, low-level background activity, and sporadic larger explosive eruptions. Its historical observations of eruptions date back to 1531, but it has been erupting vigorously since 2002 with major activity throughout 2018, producing three main eruptions in February, June and November. Its almost persistent activity generates major ashfalls, pyroclastic flows, lava flows; when heavy rains mobilize its deposits, they can form damaging lahars. Phenomena, …

Exploring Substrate Specificity Of Fructose Transporters En Route To Glut Specific Probes For Biochemical And Biomedical Applications, Vagarshak Vigenovich Begoyan

Dissertations, Master's Theses and Master's Reports

Carbohydrate Transporters (GLUTs) are responsible for the transportation of sugars into the cell and have been of great interest in research for decades. Alterations or mutations that result in overexpression of GLUTs have been linked to a great number of diseases including, obesity, diabetes, and cancer. Differentiation between transporters has been shown to be incredibly difficult due to the highly conserved nature of the transporter structure, and thus specific targeting of transporters has proven a difficult challenge. Additionally, the GLUTs have been shown to high flexibility in their conformations, so it is difficult to determine what can or cannot pass …

Critiquing Antipatterns In Novice Code, Leo C. Ureel Ii

Dissertations, Master's Theses and Master's Reports

Students in introductory computer science courses, are learning to program. Indeed, most students perceive that learning to code is the central topic explored in the courses. Students spend an enormous amount of time struggling to learn the syntax and understand semantics of a particular language. Instructors spend a similar amount of time reading student code and explaining the meaning of the cryptic error messages displayed by compilers. Messages provided by compilers are intended to give feedback on the adherence of one’s code to the language specification and conventions. Unfortunately, these message are geared towards experts who have a clear understanding …

Surface-Enhanced Raman Scattering For Enantiomeric Discrimination, Thanyada Sukmanee

Chulalongkorn University Theses and Dissertations (Chula ETD)

Surface-enhanced Raman scattering (SERS) substrates with intended surface modification were developed for enantiomeric analysis by taking the consideration of asymmetric electric field and molecular interaction between a probe molecule and enantiomeric analyte. In the first study, discrimination between enantiomers is achieved by performing tip-enhanced Raman scattering using a silver tip which is chemically modified by an achiral para-mercaptopyridine (pMPY) probe molecule. The different relative intensities of the pMPY spectra were obtained when three pairs of enantiomers containing hydroxy and/or amino groups were used as analytes. Enantiomeric discrimination can be attained by the asymmetric electric field of the tip apex co-existed …

Electrospun Polyacrylonitrile/Graphene Oxide Nanofibers As Sorbent For Solid Phase Extraction Of Epichlorohydrin In Water, Chotitas Sribun

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this study, electrospun nanofibers of polyacrylonitrile functionalized with graphene oxide (PAN/GO) were fabricated and applied as a sorbent in solid phase extraction in a disk format (SPE disk). Graphene oxide were synthesized by chemical oxidation of graphite powder via Hummers and Tour methods and were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). For electrospun PAN/GO nanofibers, the average diameters of fibers ranged from 117-147 nm and the surface area of PAN and PAN/GO nanofibers were ranged from 7.77-13.40 m2/g. Then, the PAN/GO nanofibers were assembled in a SPE disk format and …

Improvement Of Error Bounds Of Local Limit Theorems For Sums Of Independent Integer-Valued Random Variables, Tatpon Siripraparat

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

Poisson Approximation For Locally Dependent Collateralized Debt Obligation, Nat Yonghint

Chulalongkorn University Theses and Dissertations (Chula ETD)

A collateralized debt obligation (CDO) is a type of structured asset-backed security. The assets are pooled together and divided into tranches to be sold to investors. Each tranche has a substantially different credit quality and risk level. Jaio and Kaouri (2009), Neammanee and Yonghint (2020) used Poisson approximation to approximate a percentage loss for each tranche in CDO where all reference assets are independent. However, in the real world, each asset may not have the independent structure. In this thesis, we consider reference assets without assuming independence. If a default of reference asset may affect to some asset then we …

Smooth Approximations Of Continuous Functions Definable In D-Minimal Structures, Phaphontee Yamchote

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

Development Of Polymeric Niosomes Containing Oxyresveratrol For Skin Care Products, Jirawut Jaimun

Chulalongkorn University Theses and Dissertations (Chula ETD)

Designing delivery systems to improve active ingredient (AI) efficiencies have increased incredible interests in recent years. In this study, a vesicular system has been developed using thin film hydration method with modifications. Niosomes formed from sorbitan monoesters (SpanTM) with cholesterol molar ratios of 0, 0.5, 1 and 1.5 were prepared with varying AI amount 10-50 mg and was hydrated by hyaluronan solution. Oxyresveratrol was separated from the heartwoods of Artocarpus lacucha. This AI has been broadly utilized to restrain enzyme tyrosinase; however, it possesses low stability against heat and light. Encapsulation utilizing niosome or polymeric niosome as a delivery system …

Simulation Of Plasma Dynamic In Theta Pinch Device By Finite Element Method With Shock Wave Effect, Nipitpon Chueachot

Chulalongkorn University Theses and Dissertations (Chula ETD)

Theta pinch is a device that generates plasma by induction from an external current. This study aims to investigate the dynamic of plasma with shock wave effect in microscopic species as the electron, ion, and neutral gas using Finite Element Method (FEM) simulation. Theta pinch device was simulated with argon gas at operating pressure of 2,5,8, and 10 Pa using an electromagnetic equation, a transport equation, and Navier-Stokes’s equation in the model. Plasma properties such as electron current, electron temperature, plasma radial position, and plasma radial velocity are compared with the Lee model at 10 Pa and experiment for verification. …

การออกแบบและการประเมินกระบวนการของระบบเซลล์เชื้อเพลิงชนิดคาร์บอเนตหลอมเหลวร่วมกับระบบการแยกอากาศด้วยเคมิคอลลูปปิง, กวินทรา กอบกู้วิทยา

Chulalongkorn University Theses and Dissertations (Chula ETD)

เซลล์เชื้อเพลิงชนิดคาร์บอเนตหลอมเหลวเป็นอุปกรณ์ผลิตไฟฟ้าผ่านกระบวนการทางไฟฟ้าเคมีที่มีประสิทธิภาพสูงและปล่อยมลพิษต่ำ อย่างไรก็ตามการใช้ไฮโดรคาร์บอนเป็นเชื้อเพลิงยังคงมีการปลดปล่อยคาร์บอนไดออกไซด์สู่บรรยากาศ งานวิจัยนี้จึงมีแนวคิดที่จะพัฒนาระบบเซลล์เชื้อเพลิงชนิดคาร์บอเนตหลอมเหลวร่วมกับการดักจับคาร์บอนไดออกไซด์โดยใช้กระบวนการแยกอากาศด้วยเคมิคอลลูปปิง โดยการสร้างแบบจำลองของระบบเซลล์เชื้อเพลิงร่วมกับระบบการแยกอากาศด้วยกระบวนเคมิคอลลูปปิงด้วยโปรแกรม Aspen plus ในแบบจำลองใช้ดีเซลเป็นเชื้อเพลิงและแมงกานีสออกไซด์เป็นตัวพาออกซิเจน แบ่งการออกเป็น 2 กรณี คือ กรณีที่ใช้คาร์บอนไดออกไซด์และกรณีที่ใช้ไอน้ำเป็นตัวพาออกซิเจน จากผลการศึกษา พบว่า ระบบที่มีการดักจับคาร์บอนไดออกไซด์ให้ประสิทธิภาพการผลิตไฟฟ้าโดยรวมต่ำกว่าระบบที่ไม่มีการดักจับคาร์บอนไดออกไซด์ แต่สามารถดักจับคาร์บอนไดออกไซด์ได้สูงถึงร้อยละ 81.13 เมื่อเปรียบเทียบกรณีที่ใช้แก๊สตัวพาออกซิเจนต่างกัน พบว่า กรณีที่ใช้คาร์บอนไดออกไซด์ให้ประสิทธิภาพการผลิตไฟฟ้าสูงกว่ากรณีที่ใช้ไอน้ำโดยให้ค่าประสิทธิภาพ การผลิตไฟฟ้าโดยรวมเท่ากับร้อยละ 50.78 และ 50.03 ตามลำดับ นอกจากนี้ พบว่า กรณีที่ใช้คาร์บอนไดออกไซด์มีปริมาณการปล่อยคาร์บอนไดออกไซด์และดัชนีการใช้พลังงานต่อการดักจับคาร์บอนไดออกไซด์ต่ำกว่ากรณีที่ใช้ไอน้ำ ซึ่งมีค่า 2.72 และ 2.76 โมลต่อกิโลวัตต์ชั่วโมง และ 109.27 และ 120.84 กิโลจูลต่อโมลคาร์บอนไดออกไซด์ ตามลำดับ นอกจากนี้จากการศึกษาผลของตัวแปรดำเนินการต่างๆ ที่ส่งผลต่อประสิทธิภาพการผลิตไฟฟ้าและความสามารถในการดักจับคาร์บอนไดออกไซด์ พบว่า ภาวะดำเนินการที่ดีที่สุด ได้แก่ อัตราส่วนต่อไอน้ำเท่ากับ 3 อุณหภูมิรีฟอร์มิงเท่ากับ 800 องศาเซลเซียส อุณหภูมิดำเนินการของเซลล์เชื้อเพลิงเท่ากับ 750 องศาเซลเซียส สัดส่วนการใช้เชื้อเพลิงเท่ากับร้อยละ 79 และสัดส่วนการใช้คาร์บอนไดออกไซด์เท่ากับร้อยละ 65 โดยให้ประสิทธิภาพการผลิตไฟฟ้าโดยรวมและดัชนีการใช้พลังงานต่อการดักจับคาร์บอนไดออกไซด์เท่ากับร้อยละ 53.04 และ 122.12 กิโลจูลต่อโมลคาร์บอนไดออกไซด์

ผลของอายุคอมพาวนด์ต่อยางไม่ผ่านมาตรฐานจากเครื่องอัดรีดแบบสี่หัวและสมบัติของหน้ายาง, ปิยธิดา จันทรางสุวรรณ์

Chulalongkorn University Theses and Dissertations (Chula ETD)

การเติบโตของอุตสาหกรรมยานยนต์ส่งผลต่อการผลิตยางล้อ ยางคอมพาวนด์ จำนวนมาก ถูกทำลายจากการผลิตที่มากเกินไป เนื่องจากยางคอมพาวนด์ที่ถูกจัดเก็บ เป็นเวลานานอาจส่งผลต่อคุณภาพของยางรถยนต์ งานวิจัยชิ้นนี้ศึกษาผลกระทบของ ระยะเวลาการจัดเก็บยางคอมพาวนด์ที่อุณหภูมิ 25 °C เป็นเวลา 30 วัน และ 50 °C เป็นเวลา 6 วัน ยางคอมพาวนด์ถูกแบ่งประเภทโดยสารตัวเติมได้แก่ เขม่าดำ ซิลิกา – เขม่าดำที่อัตราส่วนโดยน้ำหนักเท่ากับ 1.3 และ 5.8 ทุกๆ 3 วันยางคอมพาวนด์ ถูกวิเคราะห์ผ่านเครื่องวัดความหนืดมูนนี่ และเครื่อง MDR รวมไปถึงการทดสอบ ค่าความแข็ง ความกระเด้งกระดอน สมบัติแรงดึง ความหนาแน่นของการเชื่อมขวาง และสัดส่วนเจลในยางวัลคาไนซ์ จากผลการศึกษา การเชื่อมขวางในตัวยางคอมพาวนด์ จะมีปริมาณมากขึ้นตามเวลา ส่งผลให้ค่าความหนืดมูนนี่มีปริมาณเพิ่มขึ้น โดยยางคอมพาวนด์ที่ใช้ซิลิกามีหมู่ไซลานอล (Si-OH) ที่พื้นผิวจะเกิดปฏิกิริยา ระหว่างสารตัวเติมมากกว่าเขม่าดำ การเพิ่มอุณหภูมิในการจัดเก็บยางคอมพาวนด์ส่งผลให้ เร่งการเกิดการเชื่อมขวาง สำหรับพฤติกรรมการคงรูป การเชื่อมขวางที่เพิ่มขึ้น ส่งผลให้ระยะเวลาการสุกลดลง ค่าแรงบิดต่ำสุดมีค่าเพิ่มขึ้น และค่าแรงบิดสูงสุดลดลง สำหรับยางวัลคาไนซ์ การเชื่อมขวางเพิ่มขึ้นส่งผลต่อการเพิ่มขึ้นของค่าความแข็ง ความกระเด้งกระดอน ยางจะมีความแข็งแรงและเหนียวที่มากขึ้น โดยยางคอมพาวนด์ ที่ถูกจัดเก็บที่ 50 °C จะมีระยะเวลาการจัดเก็บไม่เกิน 3 วัน

Geophysical Assessment Of The Lake Chesterfield Site, Missouri, Diya Ali Ahmad Alfuqara

Doctoral Dissertations

"Since construction of the Lake Chesterfield, Missouri in 1986, significant leaks have occurred causing the lake to lose substantive volumes of water. Mitigation efforts, have not solved the problem. Indeed, in June of 2017, the water level in Lake Chesterfield dropped at an alarmingly rapid rate. Prior to authorizing additional mitigation work, the Lake Chesterfield. Home Owners Association (LCHOA) decided to acquire geophysical data across the drained and dry lake bed. These information would help a geotechnical engineering firm determine the most appropriate mitigation plan.

In the summer of 2018, electrical resistivity tomography, multichannel analysis of surface wave, and spontaneous-potential …

Towards Efficacy And Efficiency In Sparse Delay Tolerant Networks, Douglas John Mcgeehan

Doctoral Dissertations

"The ubiquitous adoption of portable smart devices has enabled a new way of communication via Delay Tolerant Networks (DTNs), whereby messages are routed by the personal devices carried by ever-moving people. Although a DTN is a type of Mobile Ad Hoc Network (MANET), traditional MANET solutions are ill-equipped to accommodate message delivery in DTNs due to the dynamic and unpredictable nature of people's movements and their spatio-temporal sparsity. More so, such DTNs are susceptible to catastrophic congestion and are inherently chaotic and arduous. This manuscript proposes approaches to handle message delivery in notably sparse DTNs. First, the ChitChat system [69] …

An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas

Doctoral Dissertations

”The Zubair Formation is the most prolific reservoir in Iraq, which is comprised of sandstones interbedded with shale sequences. Due to the weak nature of the shale sequence, the instability of a wellbore is one of the most critical challenges that continuously appears during drilling across this formation. Historically, over 90% of wellbore problems in the Zubair Formation were due to wellbore instability. Problems associated with wellbore instability, such as tight hole, shale caving, stuck logging tools along with subsequent fishing, stuck pipe, and sidetracking result in increasing the non-productive time. This non-productive time has cost an enormous amount of …

Magnetic Control Of Transport Of Particles And Droplets In Low Reynolds Number Shear Flows, Jie Zhang

Doctoral Dissertations

“Magnetic particles and droplets have been used in a wide range applications including biomedicine, biological analysis and chemical reaction. The manipulation of magnetic microparticles or microdroplets in microscale fluid environments is one of the most critical processes in the systems and platforms based on microfluidic technology. The conventional methods are based on magnetic forces to manipulate magnetic particles or droplets in a viscous fluid.

In contrast to conventional magnetic separation method, several recent experimental and theoretical studies have demonstrated a different way to manipulate magnetic non-spherical particles by using a uniform magnetic field in the microchannel. However, the fundamental mechanism …