bluuebunny/crossref_metadata_2025 huggingface dataset:
The change of addressing in the communication of Vietnamese family from the view of language social network
Authors:   Graduate student at University of Social Sciences and Humanities, Vietnam National University, Ho Chi Minh City. Ho Chi Minh, Thi Dieu Trang BUI
Published: October 2022

Addressing people is always the number one priority in the communication of Vietnamese people. The change of addressing in family shows a part of culture, characteristics and specific nature of one national language. Speakers take full control in choosing the addressing method based on their attitude, context, subject and communication purpose. This paper focuses on the change on how to choose addressing methods in Vietnamese family which is the basic to fully study and analyze another links in language social network.
Human resource training to develop community tourism in the Con Cuong District, Nghe An Province
Authors:   Institute of Social Pedagogy, Vinh University, Thi Thuy TRAN
Published: October 2022

The Con Cuong District is considered as a highlight of Nghe An tourism with the orientation of developing community tourism associated with preserving Thai culture. However, Thai community in Con Cuong District has just started to pratice this type of tourism so there are many surprises. Human resource training is one of the prerequisites for developing community tourism in Con Cuong District, Nghe An Province. The article has pointed out the content and the forms of training that can be applied to improve the quality of labor resources to develop community tourism in Con Cuong District.
The voice of spirit in poems of the “Innovation” generation writers
Authors:   Au Lac Secondary School, Ho Chi Minh City, Thi Trinh PHAM
Published: October 2022

Some writers in the “Innovation” generation used the voice of spirit as an artistic object, a creative medium to access the mystery of the human mind - a sacred, mysterious and ambiguous world opposed to the reality human beings’ experience. The writers, namely Nguyễn Quang Thiều, Nguyễn Bình Phương, Mai Văn Phấn, Nguyễn Lương Ngọc, Dương Kiều Minh, Inrasara, etc. are supposed to employ their exploration and narration of the voice of spirit to acquire deeper understandings of the modern man’s spititual life, ideology and internal life as a whole. When it comes to the voice of spirit as a poetic object, it is these same ‘Innovation’ generation writers’ inspiration that made critical contributions to poetry stylistics in terms of word combination, linguistic styles, images and tones, etc.
Some frequent structures in modern Vietnamese novels written based on fanciful realism
Authors:   Dong Nai University, Thi Kim Anh TRUONG
Published: October 2022

Writing structure is a unique creation in each work, the general aspect, meaning and artistic creation design expression of the writer. The fanciful realism trend has clearly dominated the formation of structures in modern Vietnamese novels, of which the followings are particularly remarked: maze structure, fragmentary structure, reality-illusion interweaving structure.
The renovation process in the 3/2 Farm, Quy Hop District, Nghe An Province from 1995 to 2010
Authors:   Vinh Medical University, Nghe An, Thi Yen HOANG
Published: October 2022

Since the 1970s and 1980s of the 20th century, several state-run farms faced challenges and difficulties, which required renewal to survive and develop. The article clarifies the renovation process of the 3/2 Farm in Quy Hop District, Nghe An Province from 1995 to 2010. In this article, the author outlined the situation of 3/2 Farm before 1995 and evaluated the renovation process at 3/2 Farm in the fields of contract method, production, and business from 1995 to 2010.
The reality and solutions to time management of students at Vinh University in the context of CDIO approach education
Authors:   Vinh University, Nghe An, Viet Nam, Thi Bich Ngoc NGUYEN , Cong Trong NGUYEN ,   Vinh University, Nghe An, Viet Nam, Huyen Trang PHAM ,   Vinh University, Nghe An, Viet Nam
Published: October 2022

Time management in the access to training model CDIO is crucial for students who study at Vinh University, but not all students understand and know how to manage their time. This fact significantly affects the studying performance of those students. Based on the surveys and statistics conducted, this essay analyses the reality of time management of students at Vinh University in the recent time, then suggest several solutions to improve the skill at time management in the context of CDIO approach education.
Application of the theory of constructivism in designing lessons history for grades 4 and 5
Authors:   Vinh University, Nghe An, Viet Nam, Thi Phuong Nhung NGUYEN , Thien Chung NGUYEN ,   Vinh University, Nghe An, Viet Nam
Published: October 2022

Nowadays, like other students in general education, elementary students are not interested in history. The reason for this is not the fact that primary students do not love history, but because primary teachers are probably lacking in teaching methods and ways to help students love history. Applying the theory of constructivism in the design of history will help solve two fundamental problems of teaching history: Learners do not want to learn (due to boring, teaching methods are not attractive); The instructor has a new tool, a new approach to teaching history, and enhances student activeness.
Application of linguistic gameplay in teaching English language
Authors:   Faculty of Foreign Languages, Hanoi University of Industry, Thi Bich Loan DAU , Thi Quynh Ngan HOANG ,   Faculty of Foreign Languages, Hanoi University of Industry
Published: October 2022

The article aims to generalize the rationale for linguistic gameplay in teaching English, thereby to conduct a study of perception on game-based English teaching with the involevement of 389 economics-majored students of some public universities in Hanoi. The research results confirm the roles of language games in teaching English, including creating a cheerful learning atmosphere, motivating learning motivation, and creating a favorable environment for communication skill improvement, pronunciation practice, vocabulary development as well as grammar reinforcement for students.
The support of the overseas Chinese in the South of Vietnam for the Chinese revolutionary movement led by Sun Yat-sen
Authors:   Vinh University, Nghe An, Viet Nam, Thi Huong NGUYEN , Thi Hong Tham NGUYEN ,   Vinh University, Nghe An, Viet Nam
Published: October 2022

Due to the objective and subjective conditions brought, the land of South Vietnam is not only a place with a large number of the overseas Chinese living concentrated, but most of them, especially in Saigon, Cholon areas are also originally from Guangdong - the homeland of Sun Yat-sen. Therefore, when coming to Vietnam to revolutionize, Sun Yat-sen paid special attention and came to the South many times. The activities that Sun Yat-sen conducted in the South of Vietnam have sparked a revolution in this community. So in the struggle movement to overthrow the Manchu feudalism and build a republic in China then, the overseas Chinese residing here had made great contributions. Their response took place for a long time and expressed in many fields, which contributed to the revolutionary career of Sun Yat-sen being in trouble, gradually developing.
Structure of dialogues containing commentary action in novel written by Ma Van Khang
Authors:   Vinh University, Nghe An, Viet Nam, Thi Thu DANG
Published: October 2022

The paper analyzes the structure of dialogues that contain the commentary action in the Ma Van Khang novel. The structure of a commentary dialogue includes dependent action and main action. The main action is an act of comment, and the dependent action is act of the other language and accompanying commentary action. The results show that there are four types of structures: dialogue with only one comment; dialogue with two or more comments; dialogue with one comment as the main action and other accompanying dependent actions; dialogue with two comments as the main action and accompanying dependent actions. Through describing and analyzing the types of structures of dialogue that contain commentary, the paper contributes to highlighting Ma Van Khang's talents in applying language actions in a flexible and versatile manner in order to supplement and clarify the purpose of communication.
On existence of fixed points for weakly T-contactive and generalized weakly T-contactive mappings in b-metric-like spaces
Authors:   Institute of Natural Pedagogy, Vinh University, Nghe An, Huy Hoang DINH , The Hue NGUYEN ,   Ngo Quyen High School, Quang Binh, Tuan Ngoc NGUYEN ,   Ngo Quyen High School, Quang Binh
Published: October 2022

In this paper, we prove some results for the existence and uniqueness fixed points for weakly T -contactive and generalized weakly T -contactive mappings in b-metric-like spaces. Our results extend and generalize the results in [3] [10].
Chemical constituents of the leaves of Uvaria boniana Fin. & Gagnep in Vietnam
Authors:   Institute of Natural Pedagogy, Vinh University, Thanh Tam NGUYEN , Thi Ngan NGUYEN ,   Institute of Biotechnology & Food, Industrial University of Ho Chi Minh City. Ho Chi Minh, Van Trung HOANG ,   Institute of Biochemistry and Environmental Technology, Vinh University, Van Luu HOANG ,   Institute of Biochemistry and Environmental Technology, Vinh University
Published: October 2022

A phytochemical study of extracts of Uvaria boniana Fin. & Gagnep collected at Pu Mat National Park, Nghe An Province leaves led to the isolation of three secondary metabolites, including 6-methoxyzeylenol (1), aristolactam AII (2), and stigmasta-4,22-dien-3-on (3). Their structure elucidation was determined on the basis of one and two-dimensional NMR and other spectrometric methods. This is the first report on the chemical constituents of Vietnamese Uvaria boniana.
Explore the motivations behind studying English - a case study of first year pedagogical students at Vinh University
Authors:   Department of Foreign Languages, Vinh University, Thi Viet Huong VU , Thi Tuong NGUYEN ,   Department of Foreign Languages, Vinh University
Published: October 2022

Motivation is crucial factor in the success of language learning. A great deal of research has been done so far to explore proper methods to motivate students to study English effectively. Personally, it is our concern that there are a number of difficulties in motivating students to study, especially for teachers of foreign languages in general and for EFL instructors in particular. The purpose of this article is, therefore, to obtain an overview of Vietnamese students’ motivations for learning English and teachers’ tasks in relation to motivation, to report on the author’s experience in real teaching situations at Vinh University, and to present some pedagogical implications. The results are of significant importance since Vinh University is applying CDIO approach in teaching methods and designing curriculum.
The balanced curriculum a post-method approach to language learning and teaching
Authors:   Notre Dame Seishin University, Japan, Waring ROB
Published: October 2022

The Balanced Curriculum (TBC) is an ideational approach to syllabus and curriculum design that provides a framework for teachers and students to easily see the kinds of focus which are needed in order to learn a language. The central concept of TBC is that language learning and teaching are made up of different elements which should all be balanced. TBC has two main elements, input and output which could broadly be referred to as the receptive and productive modes. These are then each subdivided by whether the activity is language-focused or fluency-focused
Active teaching methods applied in training system towards CDIO educational framework
Authors:   Vinh University, Nghe An, Viet Nam, Thi Uyen NGUYEN , Xuan Sang TRAN ,   Vinh University, Nghe An, Viet Nam
Published: October 2022

Innovation in teaching methods to raise learners’ positiveness, activeness and creativeness is one of the important issues in education. In traditional teaching methods, the authority model is teacher-centered and frequently entails one-way presentations. Students are passive learners in traditional teaching model. Shifting from passive teaching methods to active teaching approach, lecturers and students are required to think and solve problems actively. Students will find information through the lectures, while teachers will plan, organize and coordinate activities in the classroom. In this paper, we present and analyze some active teaching methods applied in training system towards CDIO educational framework.
Teacher education programs and teacher administration: a comparison between Vietnam and New Zealand in the current period - issues and solutions
Authors:   Department of Foreign Languages, Vinh University, Thi Ngoc Yen TRAN
Published: October 2022

Teacher education programs play a crucial role in the educational system of a country. This paper describes the teacher education programs offered by a university in New Zealand (NZ) and a university in Vietnam (VN) from the comparative perspective. The description focuses on such issues as learning outcomes, admission criteria, course selection, practicum periods, management, and teacher qualifications. A comparison between the teacher administration system of Vietnam and that of New Zealand is also presented.
Semi-Active Reinforcement Learning Suspension Control for the Off-Road Vehicles
Authors: Zhuang Ye , Sun Haojie , Qi Yingchun , Fan Weiguang Fan , Ye Hui
Published: October 2022

Vertical vibration of the terrain vehicle involves its comfort, maneuverability, and fatigue life of the key components. The type of road surface encountered by the vehicle is very complex and difficult to measure. Besides, the damper system has a strong non-linearity, which makes the design of the vehicle suspension controller difficult. Compared with the active suspension, the semiactive suspension has the advantages of low energy consumption and high safety, therefore this paper uses semi-active magneto-rheological damper and reinforcement learning technology, from the comfort point of view, to solve the suspension random optimal control problem. It is expected to improve the comfort of the terrain-vehicle with intelligent, low-power control method. This paper applies Gaussian Process (GP) technology to learn and model the nonlinear part of the terrain vehicle system, and then carries out the design of the reinforcement learning control strategy, establishes a linear control law with the suspension deflection, the sprung mass velocity, and the unsprung mass velocity as the feedback variables. The introduced reinforcement learning algorithm learns the appropriate feedback gain during the interaction process with the system, and then uses the learned feedback gain to carry out system simulation and experimental analysis. The paper compares the reinforcement learning algorithm with other classical semi-active control algorithms under the input of random, bump and sinusoidal pavement, and the analysis results show that the reinforcement learning algorithm introduced in the paper has excellent control effect in the full frequency band and can provide good comfort for terrain vehicles under the condition of low power consumption.
Los Factores sociodemográficos que influyen en la rotación de capital humano en la industria manufacturera de San Luis Potosí. Apuntes para la toma de decisiones
Authors: Segura Mojica Francisco Javier
Published: October 2022

En este trabajo se explora el fenómeno de la rotación de personal en la industria manufacturera de San Luis Potosí, México. Se realiza un análisis cualitativo y cuantitativo de información relacionada con el mercado de trabajo y el perfil de los trabajadores industriales, con el fin de determinar si la movilidad laboral se encuentra asociada a factores demográficos, y si es posible definir un perfil de trabajadores “estables” o “rotadores” que ayude a mejorar las decisiones de selección de personal y disminuya los costos asociados a la rotación.
Conectando lo discreto con lo continuo; propuesta metodológica para el cálculo de ancho de bin gráfico en el análisis estadístico de datos
Authors: Bárcenas Castro Mayra Angélica , Borselli Lorenzo , Díaz de León-Zapata Ramón , Flores-García Efrén , De la Rosa-Zapata Ariel Benjamín
Published: October 2022

Se presenta una propuesta metodológica para el análisis de resultados de gráficos estadísticos, en donde el ancho de bin es el principal factor de cambio para su representación. Se implementa un pseudocódigo que permite visualizar los pasos a seguir para obtenerlo. Se realizó un ejercicio para mostrar la pérdida o ganancia de información al implementar la Densidad de Kernel y también la ausencia de esta. La propuesta se hizo directamente con la metodología de Bowman y Azzalini (1997) en Matlab y el generado en este trabajo. Se utilizó el test de Kolmogorov-Smirnov para validar las ventajas del método propuesto. Se encontró que el método propuesto permite una mejor tendencia de los datos ya sea positiva, negativa o simétrica y poca o escasa pérdida de información con respecto evaluación estadística aplicando densidad de kernel; de este modo es una opción para obtener un mejor análisis estadístico cuantitativa y cualitativamente y además puede ser reproducido en temas similares.
Automatización de obturadores de sistema de crecimiento por haces moleculares usando arduino mega en una interfaz de Labview
Authors: Lara-Velázquez Ismael , Díaz de León-Zapata Ramón , Flores-García Efrén , Méndez García Victor Hugo , Espinosa Vega Leticia Ithsmel , Perea Parrales Felipe Eduardo
Published: October 2022

En este trabajo reportamos el desarrollo de un control de obturadores para un sistema de crecimiento por Haces Moleculares (EHM) o del Ingles Molecular Beam Expitaxy (MBE) utilizando una interfaz gráfica de LabView y la plataforma de Arduino Mega para la adquisición de datos. La técnica de epitaxia por haces moleculares permite controlar espesores a escala nanométrica de muy alta calidad cristalina, para la fabricación de dispositivos electrónicos y optoelectrónicos.
Experimental Study and CFD Modeling of Flow Characteristics in an Annulus with a Tubing Collar
Authors: Zhou Yisu , Huang Zhongwei , Zhang Zhuangzhuang , Jiang Tianwen , Zhang Minghe
Published: October 2022

An experimental investigation based on Particle Image Velocimetry (PIV) technology is used to measure the annular flow with a tubing collar in a casing pipe. The main purpose of this paper is to study variable cross-section annular flow characteristics with different Reynolds numbers through the visualization experiment. Streamlines distribution, velocity distribution, the vortex identification by the Q-criterion and TKE are displayed. The Reynolds number influence on the flow characteristics is discussed. A CFD modeling is established to verify the accuracy of the experiment. The results show the BFS flow is easier to generate the recirculation zones than the FFS flow at a certain freestream condition, especially at a higher Reynolds number in the VCSA flow. The presence of the VCS structure has an acceleration effect on the mean velocity at y/h>1.0 and an inhibition effect at y/h<1.0 near the step. The mean velocity variation of the VCSA flow is asymmetric, therefore pressure losses caused by BFS and FFS are different. Rotation structures identified by Q-criterion mainly exist at the entrance of NA flow and BFS flow in this study.

1. INTRODUCTION

Improper prediction and control of annular pressure losses pose significant challenges (Dokhani et al., 2020; Qin et al., 2021) in drilling, completion, fracturing, acidizing, workover and production in the petroleum industry (Jeong and Shah., 2004; Birchenko et al., 2010) with the development of deep wells and ultra-deep wells. It becomes more vital and sophisticated with the increase of well depth, not only by the effects of fluid properties, rotation and eccentricity but also by the increasing number of tubing collars and tool joints. The presence of a tubing collar or a tool joint changes the annulus geometry which leads to tapered (gradual) and squared (sudden) contraction and expansion clearance resulting in strong turbulence and fluid acceleration that generates additional pressure losses (Enfis et al., 2011). The tubing collars or tool joints effect in annular flow can be regarded as the flow past wall-mounted finite cylinders. Many engineering configurations, such as heat-exchangers, several building structures and electronic cooling systems of environment (Sachidananda and Arun, 2021; Woyciekoski et al., 2020; Ma et al., 2020; Yuan et al., 2020) can be also modeled as finite-length cylinders. Therefore, this particular flow configuration has received a lot of attention in recent years due to its importance in engineering applications and fundamental research.
Enhanced Geothermal System Design Using GeoDT and Fracture Caging — EGS Collab Stimulation Prediction Study
Authors: Frash L. P. , Li W. , Meng M. , Carey J. W. , Sweeney M.
Published: October 2022

Enhanced Geothermal System (EGS) design optimization requires simultaneous evaluation of well placement, well stimulation, flow rates, pumping pressures, seismic stability, and power production. Furthermore, it is crucial to consider subsurface uncertainty to evaluate the probability of success of various design options to inform good decision making. In this study, we present our analysis of various injection flow rates and volumes for fracture hydraulic stimulation and fluid circulation through the EGS Collab Project’s Experiment 2 & 3 test bed at Sanford Underground Research Facility (SURF) in South Dakota. Here, our goal is to identify the minimum, optimum, and maximum injection parameters that should ensure successful well stimulation and observation of produced fluid cooling (i.e., thermal breakthrough) within a targeted timeframe of 24 hours to 6 months. This work uses our Geothermal Design Tool (GeoDT). Based on this analysis, we predict that fracture caging (i.e., containment of a fluid pressure propped fracture) will be both possible and necessary for successful well stimulation and observing thermal breakthrough.

1. INTRODUCTION

The EGS Collab Project is a decameter-scale hydraulic well stimulation study being conducted at the Sanford Underground Research Facility (SURF) under the Black Hills of South Dakota, USA (Kneafsey et al., 2022). The project is currently in its second phase (Experiments 2 and 3) where the focus is on well stimulation and subsequent fluid circulation between two or more wells at 1250 m (4100 ft) depth. The rock at this site is Yates amphibolite with numerous rhyolite intrusions. The drilled well layout (Fig. 1) has one northeast oriented well surrounded by four bounding sub-parallel wells, all five being open-hole (no casing or cement). In a crossing southeast direction, an encompassing box of four instrumented and cemented wells were installed for geophysical monitoring. The monitoring wells include instruments for microseismicity, electrical resistivity, temperature, and strain. Fluid flow will target injection into the central northeast oriented well with production planned from one or more of the four bounding sub-parallel open holes, each of which is instrumented to measure flow rates and pressures.
Creep Tests on Salt Samples Performed at Very Small Stresses
Authors: Bérest P. , Gharbi H. , Jehanno D. , Peach C. J. , Brouard B. , Blanco-Martin L.
Published: October 2022

From 1996 to 2021, uniaxial creep tests were performed on salt samples in dead-end drifts of the Varangéville (France) and Altaussee (Austria) mines to take advantage of constant temperature and hygrometry. The applied loads were from 0.05 MPa (relative) to 4.5 MPa, i.e., much smaller than the loads currently applied during standard creep tests performed at the laboratory. Main conclusions are: (1) Steady state is reached after a long period (longer than 8 months). (2) Cumulated transient creep is relatively large (3) Strain rates are faster (than extrapolated from high stresses) by 4-5 orders of magnitude (4) Steady state strain rate is a linear function of the applied stress (approximately) in the σ < 3 MPa domain (5) Strain rate is a decreasing function of grain size (6) The transition between the linear (n = 1) and the non-linear (n = 3 to 5) behavior seems to range between 3 MPa and 4.5 MPa (7) No creep is observed in a very dry environment (8) No threshold for salt creep (or smaller than 0.05 MPa) is observed (9) In the small stress domain, reverse creep is observed.

1. INTRODUCTION

It has been suspected for long (Spiers et al., 1990; Urai and Spiers, 2007) that, in the small deviatoric stress domain (σ < 3 MPa), the governing mechanism for salt creep was pressure solution — rather than dislocation creep. A consequence should be that creep rate in this domain is much faster - by several orders of magnitude - than extrapolated from tests performed in the high stress domain. In addition, creep rate should be a decreasing function of grain size; it should be a linear function of the applied stress, and the presence of a small amount of brine at the grains interface should be a necessary condition for active creep. These statements were based on theoretical arguments, geological evidence and the results of tests performed on artificial salt.
Westerly Granite Anisotropy Study
Authors: Lokajícek T. , Petružálek M. , Svitek T. , Vasin R. , Wenk H. R.
Published: October 2022

Westerly granite (WG) is well known rock, believed to be isotropic. We studied four samples of WG heated between 100°C and 600°C, by ultrasonic sounding on spherical samples under hydrostatic pressure up to 400 MPa, neutron diffraction on identical samples and scanning electron microscopy (SEM). Thermal treatment studies are important for localities like nuclear waste storages, geothermal projects, rock and earthquake mechanics. All measurements were done at room temperature. The 3D distribution of P-wave velocities at high pressures reflects intrinsic structure and even though the anisotropy is low, the orientation of the minimum velocity corresponds to the highly preferred orientation of plagioclase (010) and biotite (001). Image analyses showed that there is also preferred orientation of microcracks regardless of their size and thermal treatment level. Neutron diffraction measurements of the samples heated to 100°C and 600°C confirm weak intrinsic elastic anisotropy, which remain unchanged due to the thermal treatment. We can assume that in Westerly granite there are two types of anisotropy: crystal preferred orientation which was formed during igneous crystallization and second one is due to the oriented microcracks which have been formed during tectonic exhumation or during sample excavation in the quarry. Both seems to be unrelated.

1. INTRODUCTION

Westerly granite has been studied for decades and its properties are very well known. There were studied mechanical properties, elastic properties, development of cracks introduced by uniaxial or triaxial loading, thermal heating, study of permeability, study of fracturing process by acoustic emission, modelling of crack systems and plenty of others. Westerly granite is considered as fine grained, homogeneous material, isotropic and therefore it is often discussed or even used as a standard for comparison with other granitic rocks. Quantification of elastic properties of granites is important to determine crustal seismic velocities and stress orientation. Generally, it is assumed that granitic rocks are elastically isotropic. In this paper, we study influence of thermal cracks and crack induced anisotropy on P-wave propagation in spherical samples of Westerly granite at different confining pressures. Experimental elastic wave velocity distributions in Westerly granite are compared to the model based on neutron diffraction data on mineral composition and mineral preferred orientations. Due to high penetration depth of thermal neutrons, information on a large representative volume of geomaterial is obtained; and the method of neutron diffraction allows to investigate same bulk samples that were used for elastic wave propagation study. Thus, ultrasonic sounding (US) and neutron diffraction form a pair of complementary methods suitable for in-depth analysis of elastic anisotropy of rocks.
Assessing the Effect of In-Situ Stress Conditions in Back-Analysis of Rock Mass Parameters of Tunnels Using Machine Learning Techniques
Authors: Khetwal A. , Gutierrez M.
Published: October 2022

One approach to improve the reliability of predicting the response of tunnels is the "design as you go" method, where tunnel response is monitored during tunneling using field instrumentation. In the present study, various machine learning (ML) techniques are evaluated, and the best approach is proposed for the back-analysis of tunnel response. Incorporating in-situ stress conditions in back analysis is also essential as these are responsible for short- and long-term deformations. The study aims at predicting the cohesion and friction angle for a tunnel by setting the monitoring data and in-situ stress conditions. The ML techniques are combined with the results obtained from the commercially available finite difference code FLAC, widely used in geotechnical modeling. The ML algorithm with maximum accuracy is then used to determine the input parameters using the synthetic monitoring data. The present study evaluates a single tunnel with an overburden of 1000 m and an in-situ stress ratio ranging from 0.25 to 3 to prepare a training and validation set. The results show that with an acceptable 0.1% error, the Levenberg-Marquardt Back-Propagation Method (LMBP) of Artificial Neural Network (ANN) is found to be the most suitable ML algorithm.

1. INTRODUCTION

The key to the meticulous design of the underground structure is the careful assessment of ground parameters. Evaluation of rock mass behavior is crucial in determining the necessary support measure design that ultimately defines the safety of underground structures. This assessment is based on the results obtained from the numerical models with rock mass parameters as input data prior to construction. Bertuzzi (2017) pointed out that the elastic modulus of rock mass is often calculated using the correlations obtained from the rock mass classification system. Many researchers have expressed difficulty in interpreting the rock mass parameters using the in-situ testing as high variability in the results can be obtained, and the average behavior can be assessed by performing a large number of tests (Vibert and Ianos, 2015). Back-analysis of the rock mass parameters using the monitoring data is another approach that has proven to be helpful in optimizing underground structures’ overall design and is the aim of the present study. The back-analysis aims to validate the model parameters and improve the forward modeling of subsequent excavations. Re-calibration of the back-calculated parameters optimizes the design and overall project. Callisto and Ricci (2019) studied the tunnel damage response under seismic loading. It was found that back analysis contributed to assessing the primary causes of damage: geometry and dynamic response of lining. The crucial point for performing the back analysis is identifying the parameters that affect its accuracy.
A Simplified Hydro-Mechanical Model for Sanding from Hollow Cylinder Tests
Authors: Gravanis E. , Sarris E. , Patruno S.
Published: October 2022

Particles produced by the hydro-mechanical processes during sanding in hydrocarbon wells is a highly complex physical process. Sanding onset is influenced by a number of factors which include mechanical failure and hydrodynamic erosion. Over the years a number of mathematical and numerical models have been developed to describe the sand production process, involving sanding criteria or constitutive laws of mechanical or hydro-dynamical nature. In this work we propose a new simplified model working along the lines of the hydro-dynamical constitutive law of previous research works. The model amounts to a set of two ordinary differential equations coupling the mechanical process of plastic yielding with hydro-dynamic erosion, including degradation of the material. The model is constructed for hollow cylinder tests which allows cylindrical symmetry which is particularly useful for determining the sand production coefficient λ from such tests. The sand production coefficient as a function of the externally applied stress is estimated from previously published experimental data via a single parameter best fit. It is shown that the sand production coefficient is nearly constant for the range of values of the external stress considered. Additionally, the mathematical sand production curves capture fairly well the experimental data.

1. INTRODUCTION

The production of sand particles from oil and gas wells is a phenomenon by which detached rock solids, due to erosion, migrate from the exposed surface of the well along with reservoir fluids during production. Predicting sand production is highly important in hydrocarbons recovery because they can cause a number of operational problems like: local formation failure, blocking of perforation channels, inability of sand control measures, which may lead eventually to local well collapse or in extreme cases cause catastrophic failures (Wilson et al., 2002; Rahmati et al., 2013; Volonté et al., 2013; Wang and Sharma, 2016; Li et al., 2018; Eshiet et al., 2019). The majority of rocks that are prone to sand production are sandstones, mainly poorly consolidated or even consolidated, but also hydrocarbons provinces. For these reasons, petroleum companies are seeking collaborations with academia in search for solutions via advance modelling to help in the understanding of the physics and the mechanics of this phenomenon because it costs to the entire industry 2 billion per annum (Gravanis et al., 2015; Gravanis et al., 2016; Sarris et al., 2021).
A Comprehensive Constitutive Model Solver
Authors: Chieslar J. D.
Published: October 2022

The object-oriented software concept is applied to material mechanics calculations. The result is a comprehensive predictor-corrector which has been employed to solve virtually all of the constitutive exercises in a mature, general-purpose, finite element program. In addition to updating internal variables consistent with global inputs (corrector), the software also produces consistent material tangents (predictor), without resort to formulae. Coupled mechanical-thermal-porous flow problems are addressed as well as compound mechanical responses: creep-plasticity, creep-damage, etc. Material and spatial coordinate transformations are incorporated as well as transformation to and from local material axes. Internal calculations may be undertaken in either spatial or material coordinates, depending upon the native definition. Even viscoelasticity and hyper-viscoelasticity, via Prony series, are efficiently handled by the sparse solver. A tool to exercise any material model, simulating global inputs, is incorporated. Historical plots may be produced and inputs may be cyclical or otherwise simulate complex histories. This is accomplished by using PostScript operators.

1 INTRODUCTION

It is perhaps most common in commercial modeling software that each constitutive model is self-contained, that is, each solves the responses and forms the material tangents (algorithm-oriented software design). There is much advantage to be gained by employing a uniform solution/tangent formation strategy for all material models. Indeed, this is the subject of this communication. At first examination, this may seem incongruous considering the different solution strategies employed for different models. For example visco-elasticity, via a prony series, is most often solved by a recursive solution scheme, whereas plasticity would be solved via a Newton-Raphson scheme. Of course, for simplified versions of these models, a forward difference integration scheme is employed, Flac3d, for example. If the constitutive model is algorithmically nonlinear, it is tacitly assumed that any path dependence is captured by taking small time/load steps. The highly nonlinear nature of strain-hardening models, however, generally requires iteration at the constitutive level. This is generally not supported in forward difference programs so the material models in these codes tend to be relatively simple.
Understanding Salt Mine Ground Behavior Through Geotechnical Monitoring and Data Analysis
Authors: Gregory S. A.
Published: October 2022

The Waste Isolation Pilot Plant (WIPP) was constructed for the permanent disposal of defense-generated transuranic waste from DOE sites around the United States. WIPP functions as a category 4 mine and category 2 nuclear facility. The waste is to be deposited 660 m (2150 ft) beneath the Earth’s surface inside of the Delaware Basin salt bed for permanent disposal. The first waste shipment arrived at WIPP in 1999 and is currently anticipated to operate beyond 2050. Due to the creeping nature of salt and the hazards involved in handling nuclear waste, it is paramount to monitor the changing conditions of the mine. Throughout the WIPP’s project life, geotechnical and mining engineers have developed and improved upon the data collection methods, instrumentation, and analysis that is required to monitor the ground movement in this unique salt mine. Using forecasting methods, WIPP’s geotechnical engineering team has predicted several ground falls and provides support to the site’s mining endeavors. A review of the historical ground movement data collection methods and analysis is given, as well as examples of ground falls and geotechnical abnormalities. In addition, ongoing application of operations research and engineering statistics will be discussed.

1. DISCLMAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Analysis of Pillar Strength and Design in a Karst-Affected Underground Stone Mine
Authors: Soni A. , Monsalve J. , Ripepi N.
Published: October 2022

Underground stone mines are often prone to karst formations created by the gradual erosion of carbonate rocks due to groundwater flow. The prevalent fracture network in these stone deposits offers favorable conditions for acidic dissolution, which leads to the formation of large karst cavities. The interaction of these cavities with the extensive presence of discontinuities is the major cause of ground control problems encountered during stone mining operations. This paper presents a case study for analyzing the effect of the karst cavity on the strength of a pillar in an underground room-and-pillar stone mine. Numerical analyses show that the presence of these voids in a pillar contributes to a considerable decrease in load-bearing capacity. Any development through excavation or blasting into the affected areas may pose a safety hazard to the miners. Apart from that, this may also disrupt production and burden the pre-planned mine operations. The study for estimating pillar strength using numerical modeling could provide a pragmatic approach to designing future pillars affected by karsts. The shape and volume of the karst cavities inside the concerned pillar were approximated using ground-penetrating radar (GPR) surveys. LiDAR scans were performed to map the discontinuity network around the pillars, and Discrete Fracture Network (DFN) technique was implemented to simulate the joint network in the pillar’s rock mass. The behavior of the pillar with the increase in axial compressive stress was observed with the help of Distinct-element modeling (DEM) using 3DEC software. The pillar’s rock mass is simulated using Elastic and Mohr-Coulomb constitutive models. Two scenarios are presented to assess the pillar strength with and without the presence of karst. Pillar strength is compared to the estimated current stress levels to understand the potential for improvement in the pillar design. The research emphasizes the importance of pillar design while maximizing safety and production in underground stone mines with karst cavities to prevent pillar instability or local roof failures.
Vermiculite as an Anti-Sag Additive for Water-Based Drilling Fluids
Authors: Basfar Salem , Ahmed Ashraf , Elkatatny Salaheldin , Bageri Badr
Published: October 2022

Barite is widely used as a weighing material since it has several advantages such as high specific gravity, readily accessible, and environmentally benign. Even though, several difficulties with barite particle settling particularly at high-pressure high-temperature drilling operations and removal efficiency necessitate further investigation. The utilization of magnesium-aluminum-iron silicate (vermiculite) with its ecofriendly effect was studied in this work as an additive for improving the drilling fluid characteristics. Variable concentration of vermiculite was added to the water-based mud (WBM) to address the static and dynamic sag tendencies at 250 and 120 °F, respectively. Furthermore, the influence of vermiculite on rheological characteristics and filtration performance was studied under HPHT circumstances. The sagging experiments showed that adding 4 lb/bbl vermiculite improved the WBM stability properties by increasing the suspension capacity of barite particles. Also, this amount of vermiculite significantly enhanced the rheological characteristics as the plastic viscosity to yield point ratio (YP/PV) was increased from 1.6 to 2.5. The HPHT filtration showed that 4 lb/bbl decreased the filter cake thickness by 37.5% and reduced the filtrated volume by 39%.

1. INTRODUCTION

The solids sagging, thermal breakdown of polymeric compounds, and flocculation are commonly encountered when drilling deep wells with elevated temperature and high-pressure formations (DeAngelis et al., 2011; Kruszewski and Wittig, 2018; Reinsch et al., 2015; Saasen et al., 1995). Therefore, an optimization of the common water-based mud (WBM) with qualified additives becomes necessary to fulfill the challenges in such harsh conditions (Ahmed et al., 2021; Fink, 2015). At WBM, the sagging phenomenon of solids, such as barite, usually exhibits when the temperature reaches 250 °F (Ahmed et al., 2020; Tehrani et al., 2014), resulting in density variation and inconsistent drilling fluid properties which exhibits severe technical, operational, and well control issues; since the mud weight at the upper sections will not maintain the sufficient pressure control, while at the bottom, the precipitation of the solid elevates the equivalent circulation density and raises the potential pipe sticking and loss of circulation (Amighi and Shahbazi, 2010; Bern et al., 1996; Murray et al., 2013; Scott et al., 2004; Wilson, 2014).
Testing and Analysis of Potential Damage Factors in Carbonate Reservoir
Authors: Xia X. , Mou J. Y. , Zhang Y. C. , Li X. M. , Li Y. L.
Published: October 2022

The pollution damage of injected water, fracturing fluid and drilling fluid in carbonate reservoir are mainly studied, however, the potential product precipitation damage have been seldom studied. Majiagou Formation in Daniudi gas field mainly has two kinds of rock samples, one with dolomite as the main component and the other with gypsum as the main component. On the one hand, through mineral composition analysis, the main composition of dolomite sample is CaCl2 and MgCl2. Then the ion concentration of acid rock reaction product solution was tested, the results show that the highest Ca2+ content and the highest Mg2+ content in the four groups are lower than the lowest solubility of Ca2+ and Mg2+, so the products will not reach supersaturated state and precipitate in the solution. On the other hand, for the rock sample dominated by gypsum, the mass of rock plate changes little after water immersion and acid solution corrosion. Then the gypsum samples were subjected to acid displacement, and the surface morphology changes of the samples were observed and the mass changes were measured. The test results showed that the dissolution amount of the samples was small. Therefore, it shows that water and acid will not react with gypsum and will not produce potential precipitation.

1. INTRODUCTION

Carbonate reservoir is a part of unconventional oil and gas resources. The key technology of developing carbonate reservoir is acid fracturing. (Arthur B et al., 2010). However, the acid fracturing construction process will also bring negative effects, mainly manifested in the damage to the reservoir.

At present, carbonate reservoir damage mainly studies the pollution damage of injected water, fracturing fluid and drilling fluid (Tiner R. L et al., 1974, Moore W. R et al., 1996, and Shi F et al, 2018). Under the action of high differential pressure, some fracturing fluid will leak out and enter the reservoir matrix (Reinicke A et al, 2010, and Fang W et al., 2016). Usually, this part of fracturing fluid is difficult to completely break the gel, which is easy to cause mechanical blockage of matrix pore throat and reduce reservoir permeability. In the process of fracturing fluid invasion, flowback and production, due to the carrying effect of fluid on reservoir particles, when the particles migrate to the hole roar with small radius, they will be blocked, resulting in a certain degree of damage to reservoir permeability (Gray D. H et al, 1996, Wilson M. J ,2014, Q. Zhang et al, 2014, and AlMubarak T. A, 2015).