Digital Commons Network^™

Decoupled, Linear, And Energy Stable Finite Element Method For The Cahn-Hilliard-Navier-Stokes-Darcy Phase Field Model, Yali Gao, Xiaoming He, Liquan Mei, Xiaofeng Yang

Mathematics and Statistics Faculty Research & Creative Works

In this paper, we consider the numerical approximation for a phase field model of the coupled two-phase free flow and two-phase porous media flow. This model consists of Cahn—Hilliard—Navier—Stokes equations in the free flow region and Cahn—Hilliard—Darcy equations in the porous media region that are coupled by seven interface conditions. The coupled system is decoupled based on the interface conditions and the solution values on the interface from the previous time step. A fully discretized scheme with finite elements for the spatial discretization is developed to solve the decoupled system. In order to deal with the difficulties arising from the …

Failure Of The Alexander Dam Embankment And Reconstruction Using Drainage Mitigation On Kauai, Hawaii, 1930-1932, Kerry D. Cato, J. David Rogers

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Alexander Dam is a hydraulic fill earth dam and the second-highest embankment dam in Hawaii, having been built in 1929-1932 on the south side of the Hawaiian island of Kauai to provide irrigation for McBryde Sugar Company Ltd. It was constructed across Wahiawa Stream mauka (Hawaiian for "stream that comes from the mountains," literally "toward the mountains"), upstream of Kalaheo, to store 800 million gallons (5 million m3) of water to irrigate sugarcane fields. The embankment dam was intended to have a maximum height of 125 ft (38 m), a crest length of 620 ft (189 m), and a maximum …

An Integrated Method For Forecasting Well Deliverability In Gas Condensate Reservoirs With Bottom Aquifer Drive, Abdulaziz Ellafi, Ralph E. Flori, Shari Dunn-Norman

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Gas condensate reservoirs constitute a significant portion of global hydrocarbon reserves. In these reservoirs, liquids develop in the pore space once bottomhole pressure falls below dew point. This results in the formation of a liquid bank near the wellbore region which decreases gas mobility, which then reduces gas inflow. In such complex reservoirs, it is important to correctly describe PVT impacts, adjustments to well test analysis and inflow performance, and then combine all effects in the reservoir analysis. The literature contains many references to individual adjustments of PVT analysis, well testing, or inflow performance for gas condensate reservoirs, but few …

Testing And Evaluation Of Shale Stability For Zubair Shale Formation, Ahmed K. Abbas, Ralph E. Flori, Ahmed Al-Anssari, Mortadha Alsaba

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Zubair Formation consists of approximately 55% shale, which causes almost 70% of wellbore problems due to incompatibilities of drilling fluids and shale formations. The most common and effective solution to shale instability is through the design and selection of drilling fluids. Understanding the interaction between drilling fluids and shale has been a challenge due to the complexity of both physical and chemical variations in shale formations. This paper presents some of the important laboratory and well-site testing techniques that are often used by mud engineers for characterizing and remediating drilling fluids and shale interaction. Well-preserved shale samples were analyzed to …

Advanced Ion Management To Improve Oil Recovery In Oil-Wet Carbonate-Sandstone Composite Reservoirs, Ali K. Alhuraishawy, Baojun Bai, Mingzhen Wei, Waleed H. Al-Bazzaz

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Waterflooding with different ionic composition called advanced ion management which play a role with ionic composition of injected water to enhance the oil production. In the last decade, many studies pointed out that the composition of injected water could changes rock wettability during waterflooding. The main purpose of this study is to evaluate the effects of SO4 and low salinity water on improving oil recovery in oil-wet carbonate reservoirs. Sulfate ion concentration, low salinity water, rock composition, porosity, and permeability were examined using a designed model. Typical seawater, increase SO₄, two and three times in the seawater, and …

Miscible Gases Based Eor In Unconventional Liquids Rich Reservoirs: What We Can Learn, Dheiaa Alfarge, Mortadha Alsaba, Mingzhen Wei, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Over the last decade, Unconventional Liquids Rich Reservoirs (ULR) have become the main target for oil and gas investors as conventional formations started to deplete and diminish in numbers. These unconventional plays have a huge oil reserve; however, the primary oil recovery factor is predicted to be less than 10%. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the oil industry since there is no commercial project reported for any IOR technique yet. Miscible gas based EOR technique might be the most potential strategy to improve oil recovery in such complex plays. In this study, a …

New Insights Of Low Salinity Water Flooding In Low Permeability-Low Porosity Clay Rich Sandstone Reservoir, Ali K. Alhuraishawy, Baojun Bai, Mingzhen Wei, Waleed H. Al-Bazzaz

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

One of the EOR technologies is low-salinity water flooding (LSWF) is an EOR method that operates at a lower cost than other EOR methods, which makes it a preferred area of interest for oil industry economists, who continue to call for EOR costs to come down. The aim is to minimize the possible cost to recover as much oil as possible. The performance of low salinity waterflooding in decreasing residual oil saturation in low permeability-porosity clay-rich sandstone reservoir. Porosity test, core flooding test, XRD and scanning electron microscopy (SEM) tests were achieved in this study. Salinity effect on the porosity, …

Application Of Integrated Reservoir Geomechanics For Well Planning Of High-Angled Wells In A Mature Oil Field, Ahmed K. Abbas, Ralph E. Flori, Yousif M.B. Al-Asadi, Mortadha Alsaba, Nasser A. Al-Hamad

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Zubair oil reservoir has a significant potential to contribute to the petroleum supply in Iraq. Drilling highly deviated wells is a commonly used approach to enhance the production in mature fields. Drilling these wells in the Zubair Formation has been a challenge due to severe wellbore instability issues. This study presents how integrated reservoir geomechanics was used for efficient well planning and safe drilling of nearly horizontal wells (75° Inclination) through Zubair depleted sandstone oil reservoir. In this study, an integrated workflow was implemented mainly to build a geomechanical model using offset well data. The in-situ principal stresses and their …

Learning From Experience: An Automatic Ph Neutralization System Using Hybrid Fuzzy System And Neural Network, Ethar H.K. Alkamil, Seaar Al-Dabooni, Ahmed K. Abbas, Ralph Flori, Donald C. Wunsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

In oil and gas industry, the pH level is one of the most important indicators of mud contamination while drilling. Although the process has simple components, the pH neutralization process is complicated in the mud circulation system. This difficulty is due to the high nonlinearity of the process. In this paper, the fuzzy neural network (FNN) is integrated to the fuzzy logic controller (FLC) to create a system which identifies pH fluctuation into a drilling mud system, assesses and signals its severity. And then, it automatically actuates a chemical treating fluids valve (CTFV), such as Caustic Soda (CS), for neutralizing …

Using Managed Pressure Drilling To Reduce Stuck Pipe Problem, Ethar H.K. Alkamil, Husam R. Abbood, Ralph E. Flori, George Medley, Sagar Nauduri, Mortadha Alsaba

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Differences between mud pressure in a wellbore and pore pressure in high permeability rocks can lead to differential sticking, particularly when drilling deviated wells and encountering mud losses. Several solutions, all challenging, can be used to address this problem, where the conventional mitigation method of managing the mud weight (MW) is often used. However, managed pressure drilling (MPD) offers a promising solution with a positive risk-adjusted cost and other benefits. Wells in the E oilfield in southern Iraq are typically drilled overbalanced and therefore often experience a high percentage of non-productive time (NPT) due to differential sticking. This study evaluates …

Computational Modeling Of Heat Transport And Volatile Extraction From Asteroid Materials, Joel C. Sercel, Mark A. Crawford, Christopher Dreyer, Egboche Unobe, Robert Jedicke, Stanley Love, Leslie S. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This paper presents the results of a program of computational modeling focused on elucidating the physics and chemical processes associated with the extraction of volatile materials from asteroid feedstocks with an eye toward use of the extracted materials for propulsion, radiation shielding, and replenishment of mission consumables. We present a math model of conductive heat transport, chemical processes, and gas escape by Darcian diffusion. Chemical processes in the model include pyrolysis of organic chemical constituents and thermal dehydration and decarbonization of hydrates and carbonates. The model is implemented in a spherical finite difference computational engine that predicts time histories of …

A Novel Ultra-Low Interfacial Tension Nanofluid For Enhanced Oil Recovery In Super-Low Permeability Reservoirs, Derong Xu, Baojun Bai, Ziyu Meng, Qiong Zhou, Zhe Li, Yao Lu, Hairong Wu, Jirui Hou, Wanli Kang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The exploration and development of super-low permeability reservoirs have become a global focus in recent years. However, conventional flooding systems commonly face problems of high injection pressure and poor displacement efficiency in super-low permeability reservoirs. Thus, it is imperative to find new flooding agents that tackle such problems. In this study, a novel ultra-low interfacial tension (IFT) nanofluid was formulated, consisting of surfactants to achieve ultra-low IFT and silica nanoparticles to reduce injection pressure. The compatibility test between the surfactants and silica nanoparticles in 10,000 mg/L NaCl solution at 90 °C was conducted to ensure their adaption to harsh reservoir …

A Simple Model For Elastic-Plastic Contact Of Granular Geomaterials, Jian Wang, Qimin Li, Changwei Yang, Yidan Huang, Caizhi Zhou

Materials Science and Engineering Faculty Research & Creative Works

We propose a simple elastic-plastic contact model by considering the interaction of two spheres in the normal direction, for use in discrete element method (DEM) simulations of geomaterials. This model has been developed by using the finite element method (FEM) and nonlinear fitting methods, in the form of power-law relation of the dimensionless normal force and displacement. Only four parameters are needed for each loading-unloading contact process between two spheres, which are relevant to material properties evaluated by FEM simulations. Within the given range of material properties, those four parameters can be quickly accessed by interpolating the data appended or …

Multitask Allocation To Heterogeneous Participants In Mobile Crowd Sensing, Weiping Zhu, Wenzhong Guo, Zhiyong Yu, Haoyi Xiong

Computer Science Faculty Research & Creative Works

Task allocation is a key problem in Mobile Crowd Sensing (MCS). Prior works have mainly assumed that participants can complete tasks once they arrive at the location of tasks. However, this assumption may lead to poor reliability in sensing data because the heterogeneity among participants is disregarded. In this study, we investigate a multitask allocation problem that considers the heterogeneity of participants (i.e., different participants carry various devices and accomplish different tasks). A greedy discrete particle swarm optimization with genetic algorithm operation is proposed in this study to address the abovementioned problem. This study is aimed at maximizing the number …

Nupt St-Data Miner: An Spatio-Temporal Data Analysis And Visualization System, Zhiqiang Zou, Junjie Xiong, Xuerong He, Haihong Dai

Computer Science Faculty Research & Creative Works

Given the increasing popularity and availability of location tracking devices, large quantities of Spatio-Temporal data (ST-data) are available from many different sources. For the ST-data, reflecting the mobile characteristic of the world, it is essential to build a functional system to perform quickly interactive analysis. In this paper, we present an analysis and visualization system, NUPT ST-data Miner, which facilitates users to visualize and analyze ST-data. It (1) provides a flexible and extensible framework based on cloud computing platform, (2) is able to quickly retrieve specified ST-data, (3) integrated multiple functions for the ST-data. To demonstrate its efficiency, we validate …

Sand Distribution Effect On Three Dimensional Printed Sand Properties, Kip Woods

Dissertations and Theses @ UNI

The purpose of this study was to assess the performance characteristics of commercially available round grain silica sand for the use in three-dimensional sand printers. Two different average diameters were selected to examine the effects of screen distribution on printing performance; these diameters were 57-grain fineness number (GFN) and 70 GFN. These sands were a high purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates.

The resin system utilized in this investigation was a commercially available Furan resin system. Two test specimens were used in this study the American Foundry Society (AFS) tensile …

Applying Convolutional Neural Networks For The Source Reconstruction, He Ming Yao, Wei E.I. Sha, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel source reconstruction method (SRM) based on the convolutional neural network algorithm. The conventional SRM method usually requires the scattered field data oversampled compared to that of target object grids. To achieve higher accuracy, the conventional SRM numerical system is highly singular. To overcome these difficulties, we model the equivalent source reconstruction process using the machine learning. The equivalent sources of the target are constructed by a convolutional neural networks (ConvNets). It allows us to employ less scattered field samples or radar cross section (RCS) data. And the ill-conditioned numerical system is effectively avoided. Numerical examples …

Disposable Printed Lateral Flow Electrochemical Immunosensors For Human Cardiac Troponin T, Eithne Dempsey, Dhanraj Rathod

Articles

Here we report an electrochemical ELISA approach for cardiac Troponin T (cTnT) determination based on a lateral flow membrane with underlying screen printed electrodes (<;100 Ω /cm 2 ). The thick film transducer was modified with the anti-cardiac Troponin T antibody via physisorption and the electrochemical performance of the immunosensor was evaluated using cyclic voltammetry. The capture antibody coated immunoelectrode employed for electrochemical determination of Troponin T antigen used a sandwich assay format with horseradish peroxidase conjugated signaling antibodies held in the track of a lateral flow sensor strip. A simple two step procedure realized signal acquisition within <;20 min (total assay time). The lateral flow electrochemical immunosensor response resulted in a calibration curve with linear response (0-700 ng/ml cTnT) with limit of detection of 0.15 ng/ml.

Enhancing Lithium Leaching By Mechanical Activation, Nader Setoudeh, Ataollah Nosrati, Nicholas J. Welham

Research outputs 2014 to 2021

The lithium (Li) bearing minerals lepidolite and spodumene were mixed with different mass ratios of Na2SO4 and mechanically activated by milling in a planetary ball mill for 5 h. The milled samples were studied using thermogravimetry under an air atmosphere up to 950 ºC. Isothermal heating of the milled samples was undertaken in a furnace at temperatures of 700 ºC and 800 ºC for 1 h. Hot water leaching of the calcines indicated that increasing the calcination temperature had a significant effect on the dissolution of lithium. The leaching of lithium from lepidolite was notably higher than that from spodumene.

Chinese Outbound Travel: Understanding The Socioeconomic Drivers, Songshan (Sam) Huang, Xiang Wei

Research outputs 2014 to 2021

This study used a national sample (N = 36,490) of Chinese urban residents to examine the relationship between outbound travel intention and some key demographic, economic, and geographic variables. Findings indicate that education, income, and paid vacation days significantly predicted outbound travel intention. Compared to residents in Tier-4 cities in China, those in Tier-1, -2, and -3 cities had higher probability of choosing outbound travel by 13.1%, 30.9%, and 15.3%, respectively. This study draws meaningful connections between Chinese outbound tourism and the social and economic realities in China and offers an alternative approach to understanding Chinese outbound tourism.

Manipulation Of Human Verticality Using High-Definition Transcranial Direct Current Stimulation, Taiza E.G. Santos, Diandra B. Favoretto, Iman Ghodratti Toostani, Diego C. Nascimento, Brunna P. Rimoli, Eduardo Bergonzoni, Tenysson Will Lemos, Dennis Q. Truong, Alexandre C.B. Delbem, Bahador Makkiabadi, Renato Moraes, Francisco Louzada, Marom Bikson, Joao P. Leite, Dylan J. Edwards

Research outputs 2014 to 2021

Background: Using conventional tDCS over the temporo-parietal junction (TPJ) we previously reported that it is possible to manipulate subjective visual vertical (SVV) and postural control. We also demonstrated that high-definition tDCS (HD-tDCS) can achieve substantially greater cortical stimulation focality than conventional tDCS. However, it is critical to establish dose-response effects using well-defined protocols with relevance to clinically meaningful applications.

Objective: To conduct three pilot studies investigating polarity and intensity-dependent effects of HD-tDCS over the right TPJ on behavioral and physiological outcome measures in healthy subjects. We additionally aimed to establish the feasibility, safety, and tolerability of this stimulation protocol.

Methods: …

Modelling And Forecasting Stock Price Movements With Serially Dependent Determinants, Rasika Yatigammana, Shelton Peiris, Richard Gerlach, David Edmund Allen

Research outputs 2014 to 2021

The direction of price movements are analysed under an ordered probit framework, recognising the importance of accounting for discreteness in price changes. By extending the work of Hausman et al. (1972) and Yang and Parwada (2012),This paper focuses on improving the forecast performance of the model while infusing a more practical perspective by enhancing flexibility. This is achieved by extending the existing framework to generate short term multi period ahead forecasts for better decision making, whilst considering the serial dependence structure. This approach enhances the flexibility and adaptability of the model to future price changes, particularly targeting risk minimisation. Empirical …

Minimally Actuated Walking: Identifying Core Challenges To Economical Legged Locomotion Reveals Novel Solutions, Ryan T. Schroeder, John Ea Bertram

Research outputs 2014 to 2021

Terrestrial organisms adept at locomotion employ strut-like legs for economical and robust movement across the substrate. Although it is relatively easy to observe and analyze details of the solutions these organic systems have arrived at, it is not as easy to identify the problems these movement strategies have solved. As such, it is useful to investigate fundamental challenges that effective legged locomotion overcomes in order to understand why the mechanisms employed by biological systems provide viable solutions to these challenges. Such insight can inform the design and development of legged robots that may eventually match or exceed animal performance. In …

The Utility And Limits Of Canons Of Construction In Public International Law, Sean D. Murphy

GW Law Faculty Publications & Other Works

This draft chapter, for a volume that considers canons of construction and other interpretive principles in public international law, considers the utility and limits of such canons, drawing in part upon lessons learned from schools of American jurisprudence (formalism, realism, pragmatism) with respect to statutory interpretation. In international law, there are certain obligatory canons of construction that have been expressly incorporated in Articles 31 and 32 of the Vienna Convention on the Law of Treaties. These canons are essential elements of the interpretive process; while in any given context, one or the other of these elements might be favored, they …

Bifurcating Settlements, Michael B. Abramowicz, Sarah Abramowicz

GW Law Faculty Publications & Other Works

In settling a lawsuit, parties agree on their obligations to one another, but they need not separately address each issue, claim, or remedy that a trial court would have confronted. The legal system, however, can bifurcate the settle-ment process, requiring separate resolution of components of a settlement. Bi-furcation can protect third parties, for example, by preventing divorcing parents from trading child custody for money. In addition to identifying a wide range of contexts in which preventing trade-offs may be desirable, this Article shows that bifurcation will generally have only modest (and sometimes beneficial) effects on settlement rates.

Readership Count And Its Association With Citation: A Case Study Of Mendeley Reference Manager Software, S Ravikumar, Dohtdong Basbunlang Ms

Library Philosophy and Practice (e-journal)

The present study was carried out to find out the association between Mendeley readership count and citation pattern for scholarly articles. This study was carried out with the most prolific authors of 2014 from the four subject domain “Clinical medicine, Microbiology, Molecular Biology and Neuroscience” and around 4886 papers was identified and studied their Mendeley readership count and citation count. It was found that the articles of the most prolific authors in the above subject have a strong positive correlation between Mendeley readership count and citation; ρ value is .715**. The linear relationship for individual subjects was between .626** to …

Measuring The Research Output Of Indian Institute Of Technology (Iits) With Special Reference To Web Of Science (Wos) Database: A Bibliometric Approach, Amit Kumar, Monika Singh, Chaman Ranjan

Library Philosophy and Practice (e-journal)

Abstract:

Purpose: The study is an attempt to measure the research output of Indian Institute Technology (IITs) in quantitative manner as appeared in Web of Science (WoS) database from 1989 – 2018 (14.09.2018). In addition to measure the research output, the study aims to investigate the contribution made by the IITs, the most productive authors and their collaborative attitude with highly cited articles etc.

Design/Methodology/Approach: To accomplish the objectives of the study, the relevant data for the study was obtained from Web of Science (WoS) database. The bibliographical data were recorded in MS-Excel 2007 sheet for the analysis and …

Pythagorean Generalization Of Testing The Equality Of Two Symmetric Positive Definite Matrices, Jin Seo Cho, Peter C. B. Phillips

Research Collection School Of Economics

We provide a new test for equality of two symmetric positive-definite matrices that leads to a convenient mechanism for testing specification using the information matrix equality or the sandwich asymptotic covariance matrix of the GMM estimator. The test relies on a new characterization of equality between two k dimensional symmetric positive-definite matrices A and B: the traces of AB−1 and BA−1 are equal to k if and only if A=B. Using this simple criterion, we introduce a class of omnibus test statistics for equality and examine their null and local alternative approximations under some mild regularity conditions. A preferred test …

Comparative Pairs Judgements For High-Stakes Practical Assessments, Hendrati Nastiti

Theses: Doctorates and Masters

Assessment of practical tasks, as opposed to that of theoretical tasks, has been considered to be problematic, mainly because it is usually resource intensive and the scoring is subjective. Most practical tasks need to be assessed on site or involve products that need to be collected, stored, or transported. Moreover, because practical tasks are generally open-ended, and therefore subjective, there is concern over the reliability of the scores. In high-stakes assessment, these problems are even more challenging. There is a need for an assessment method that could overcome these problems. In this study, such a method that will be referred …

An Investigation Into Trust And Security In The Mandatory And Imposed Use Of Financial Icts Upon Older People, David Michael Cook

Theses: Doctorates and Masters

Care needs to be taken to reduce the number of people who are fearful and mistrustful of using ICT where that usage is forced upon them without choice or alternative. The growing incidence of mandatory and imposed online systems can result in confusion, misuse, fear, and rejection by people with only rudimentary ICT skills. A cohort where a high percentage of such people occur is older people, defined in this study as people over the age of 60 Examples of compulsory ICT interactions include some banks limiting bank statement access through online rather than paper-based options. Other examples include the …