Engineering Commons^™

Decoding Stock Market Movements: The Role Of Unemployment And Volatility, Bipllab Roy, Suparna Bhattacharjee

Northeast Journal of Complex Systems (NEJCS)

This study investigates how unemployment and market volatility interact with stock prices in the Indian context, framing the stock–labour–volatility nexus as a complex adaptive system (CAS) rather than a set of linear, time-invariant relationships. Using verified secondary data on unemployment, India VIX, and NSE stock indices for 2013–2023, we first apply simple and multiple regression as a descriptive baseline. Results show a strong negative association between unemployment and stock prices (R ≈ 0.824, R² ≈ 0.68, p < 0.05), consistent with Keynesian demand-side channels, while the linear VIX–stock relationship is weak and statistically insignificant (R² ≈ 0.07, p > 0.05), consistent with the expectation that volatility operates through non-linear, regime-dependent mechanisms not captured by OLS.

Importantly, we document and transparently disclose critical …

Enhancing Occupational Comfort And Energy Performance In Administrative Buildings Through Thermochromic Glazing And Upvc Curtain Wall Systems, Sherihan Adel, Esraa E. Abu-Elenain

HBRC Journal

This study investigates the influence of curtain wall façade systems—defined as non-structural glazed enclosures—on workplace comfort and energy performance in administrative buildings in Cairo, Egypt. The research addresses the limited understanding of how façade orientation and the integration of sustainable materials affect building performance in hot-arid climates. The focus is on the role of Unplasticized Polyvinyl Chloride (UPVC) frames and thermochromic glazing in enhancing thermal, visual, and acoustic comfort. A mixed-methods approach was applied, combining 600 occupant questionnaires from six office buildings with performance simulations using DesignBuilder (v6.1.0.006). The findings showed that west- and southwest-facing façades provided poor daylighting and …

``Urban Expansion And Its Relationship To The Development Of New Cities (Applied Study On The New Egyptian Cities)'', Tarek Abdel Latif Abou El Atta, Aliaa Mamdouh Mahmoud

HBRC Journal

The Egyptian government adopted a policy of establishing new cities to address urban challenges such as rapid population growth and unbalanced population distribution, with the aim of redistributing residents and achieving more balanced urban development. However, many of these cities have not achieved their planned population growth, despite the continued issuance of urban expansion decisions, raising questions about the alignment of these decisions with demographic and developmental realities. This study aims to evaluate urban expansion decisions in Egypt's new cities by analyzing their relationship with urban development factors and the city's capacity to attract residents, as well as examining their …

Leveraging Ict Adoption And Electricity Access For Sustainable Agricultural Productivity Among Nigerian Households, Menghan Huang, Qin Chen, Oluwayemisi Kadijat Adeleke, Mamdouh Abdulaziz Saleh Al-Faryan

The Philippine Agricultural Scientist

This study investigated ICT adoption (mobile phone and internet usage), access to electricity, and their impact on household agricultural productivity in Nigeria, Africa’s largest economy. Utilizing Wave 4 (2018 to 2019) Living Standards Measurement Study–Integrated Survey on Agriculture (LSMS–ISA) data covering 4,980 household heads, this study applied logit regression and Propensity Score Matching (PSM) for estimation, alongside a Cobb-Douglas production function to analyze input contributions to agricultural output. The findings revealed that the age, residential location, educational level, and access to electricity of household heads significantly determine technology adoption among farming households. Furthermore, ICT adoption exhibits a significant, positive relationship …

Building Services Engineering May/June 2026

Building Services Engineering

No abstract provided.

Del Miedo A La Ternura: Deconstrucción De Imaginarios Constitutivos De La Iag Para Imaginarla Como Una Tecnología Futura, Elizabeth Rodríguez Rendon

GDI. Revista de investigación de Género, Diseño e Innovación

El artículo propone una reflexión crítica a modo de ensayo sobre los imaginarios sociotécnicos que han configurado históricamente el desarrollo de la tecnología y, particularmente, de la Inteligencia Artificial Generativa (IAG). Se sostiene que la ciencia moderna occidental se estructuró a partir del miedo como afecto dominante, heredado de las tradiciones prometeica y fáustica, las cuales promovieron una relación con la técnica basada en el control, la dominación de la naturaleza y el rechazo de la finitud humana. Desde esta lógica, la tecnología ha sido imaginada como instrumento de poder, defensa y superioridad, reforzando narrativas de fascinación y temor frente …

A Review On Credit Card Electronic Fraud Detection Methodologies, Titilayo Mary Sayikanmi, Ibrahim Adepoju Adeyanju, Bolaji Abigail Omodunbi

Mansoura Engineering Journal

Credit card fraud remains a critical and escalating challenge within the global financial ecosystem, driving substantial annual losses and necessitating the continuous evolution of detection methodologies. This paper presents a systematic literature review, conducted via the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework, which comprehensively analyzes the state-of-the-art in electronic credit card fraud detection. Through a rigorous examination of 49 high-quality studies, this review maps the methodological evolution from traditional rulebased systems and statistical models to advanced artificial intelligence techniques, including machine learning, deep learning, and graph-based approaches. The analysis reveals that while individual methods possess distinct advantages …

Developing A Framework For Mooc Dropout: The Role Of Utilitarian And Hedonic Values In Student Retention, Bipllab Roy, Mave D'Souza, Madhura Laghane

Northeast Journal of Complex Systems (NEJCS)

Massive Open Online Courses (MOOCs) have expanded access to higher education but continue to face persistently high dropout rates, raising concerns about their long‑term effectiveness and sustainability. This study develops and empirically tests a structural framework that links utilitarian values (perceived usefulness, certificate value, time flexibility), hedonic values (enjoyment, variety and novelty, personal interest alignment), and individual characteristics (goal orientation, self‑efficacy, motivation type) to MOOC student retention. Data were collected through a structured questionnaire administered to 200 MOOC learners from Christ University, Lavasa Campus, and analyzed using Structural Equation Modelling (SEM) in AMOS. The results show that goal orientation, self‑efficacy …

Experimental Evaluation Of Walking Stability Of Bilateral Transtibial Prosthetic User: A Case Study, Mustafa Sharaf Jaian, Mahmud Rasheed Ismail

AUIQ Technical Engineering Science

Bilateral transtibial amputation presents a complex biomechanical condition in which the loss of biological ankle function and reduced sensory feedback can compromise walking stability. This case study aimed to experimentally evaluate gait stability in a bilateral transtibial prosthesis user under controlled sensory and mechanical walking conditions using a portable G-Walk inertial measurement system. The novelty of this study lies in the use of a structured three-factor experimental protocol that systematically combined visual input, arm posture, and surface type across twelve walking conditions to assess walk quality, propulsion, propulsion symmetry, and pelvic symmetry indices. The participant was a 31-year-old bilateral transtibial …

Are Single-Pilot Operations An Advantage Or A Disadvantage?, Ezgi Berte Erme

International Journal of Aviation, Aeronautics, and Aerospace

This study aims to investigate the potential benefits and drawbacks of Single-Pilot Operations (SPO) and to provide actionable insights for commercial airlines. A qualitative research design was employed, with data collected via online interviews and analyzed thematically and descriptively using MAXQDA 24. The findings indicate that pilots perceive several advantages of SPO, including the power of automation, learning artificial intelligence, minimizing human error, cockpit systems designed for artificial intelligence, more effective decision-making/speed-up in response time, reduced labor costs, reduced pilot fatigue, and reduced need for human factor/performance. Conversely, the perceived disadvantages include diminished lack of situational awareness, lack of communication …

Du Undergraduate Showcase Abstracts: Research, Scholarship, And Creative Works, Sophia Wismar, Henry Staats, Allison Metzler, Chloe Puckett, Rachel Levine, Christa Kilpatrick, Scott Wolf, Joe Walsh, Grace Doolittle, John Engebreston, Zoe Lopez, Christopher Aaby, Audrey Duff, Timothy Sisk, Katelyn Lamberton, Angela Narayan, Gilkah Argueta, Habiba Samir, Girena Tesfazghi, Genet Kenore, Sinit Tesfamariam, Effley Brooks, Abi Newell, Megan Doherty, Natalie Baer, Lexi Blood, Talya Riciputi, Jessica Jimenez, Devin Hernandez, Lynn Clark, Taj Kumar, Sunil Kumar, Allen Rutman, Mira Pronobis, Tess Carson, Anna Sher, Frankie Stroud, Tamra Pearson D'Estree, Alyssa Wilson, Emily Melnick, Jenalee Doom, Yihang Gao, Gwendolyn Geiger, Noah Gettle, Scott Nichols, Clare Ayoub, Cara Dienno, Sunny Walker, Zoe Hansen, Maya Wheeler, Addison Rice, Patrick Martin, Sanjana Acharya, Daniel Mcintosh, Amanda Mckellips, Calli Cain, Justin Blake, Peter Sokol-Hessner, Natalie Miller, Max Weisbuch, Sophia Dellota, John Macikas, Charlotte Snow, Mark Siemens, Zoe Lynch, Alex Huffman, Prachi Shah, Jason Roney, Halcyon Levi, Nicole Herzog, Andrea Koly, Daniel Linseman, Annie London, Xi Yang, Avery Zwisler, Jane Smith, Chaz Contag, Michael Kerwin, Lucy Rand, Grace Schroeder, Michelle Rozenman, Nissa Tapper, Guiming Zhang, Mateo Mazariego-Halpern, Keith Meyer, Julie Do, Dakota Park-Ozee, Travis Herink, Kara Neu, Jonathan Plomin, Eve-Odine Duchaufour, Debbie Gale Mitchell, Tennyson Anderson-Stricklin, Lily Treitz, Samantha Rosenberger, Sierra Griffith, Finley Joseph, Daniel Sampson, Emmy Davis, Skyler Kasnoff, Evon Lopez, Vivian Nguyen, Cassy Young, Franklin Sellner, Martin Tobon, Ila Graham, Zach Billings, Holden Hedit, Decatur Boland, Paul Kosempel, Cory Chandler, Jay Mahoney, Sam Dragan, Susan Dagget, Yarrow Ator, Heidi Vuletich, Owen Weber, Andrew Kloeppel, Petersen Gray, Mandi Schaeffer-Fry, Razleen Bassra, Bryanna Rodriguez, Christina Blue, Taubie Sanders, Rachel Epstein, Luke Milburn, Camryn Evans, Ezra Martinez, Mary Westwood, Gabri Notov, Robin Tinghitella, Lilou Cabrol, Eli Barbour, Juliet Mendik, Selma Myers, Zac Wise, Noah Fahlin, Michelle Knowles, Abigail Hopper, Michael Greenberger, Romi Laclair, Sarah Watamura, Sabrina Efroymson, Casey Barker, Sydney Seltzer, Bryn Yehle, Jennifer Hoffman, Sara Garcia, Ryuka Nagamine, Trevor Briggs, Remy Le Boeuf, Elena Krone, Eileen Farrell, Regan O'Rourke, Elena Roel, Greg Mortimer, Ali Ayoub, Stefani Langehennig, Caitlin Turk, Logan Scmid, Stefan Chavez-Norgaard, Karen Kim, Tatiana Peccedi, Courtney Cassidy, John Sebesta, Rhianna Lewis, Janice Bening-Lacek, Vivian Lawless, Mckenna Hanson, Jeffrey Amidon, Riya Joshi, Ram Ambre, Brady Worrell, Perrin Schneider, Ali Azadani, Brooke Agulnek, Lyndsie Salvagio, Elise Siemanowki, Yan Qin, Andre Allen, Melodie Nguyen, Megan Livengood, Abby Reams, Saffron Hartreeve, Bri Wylie, Sarah Brookman, Mariah Loiacono, Green Russo, Abhia Lodhi, Gabrielle Welsh, Nika Spehar, Shahked Levin, Evrim Baykal, Kimberly Chiew, Jocelyn Torres, Kailey Hicks, Mykaela Tanino-Springsteen, Audrey Bellows, Akam Chahal, Madeline Tepper, Shannon Murphy, Alexa Fonseca, Deborah Han, Cassandra Perez, Oluwatoyin Alaba, Julia Roncoroni, Vy Nguyen, Nana Burn, Sarah Sasse, Rubin Tuder, Anthony Gerber, Nancy Lorenzon, Christine Vohwinkel, Camryn Gunter, Tristan Weber, Sam Rommel, Brian Michel, Muskan Fatima, Alannah Oleson, Kira Frey, Edward Garrido, Beckett Morris, Kerstin Haring, Drew Middleton, Abigail Walpert, Liam Dee, Gabby Ishaw, Cole Carnes, Maddie Weiser, Claire Fox, Valeriia Vlasenko, Kateri Mcrae, Riley Smith, Abigail Templin, Kushani Rajapaksha

DU Undergraduate Research Journal Archive

Abstracts from the DU Undergraduate Research Showcase.

Modulating Electronic Structure With Linearly Fused Pyrazine Units For High-Voltage And Stable Zinc-Organic Batteries Cathode, Min-Jian Zhao, Li-Bin Zhang, Jin-Tao Wang, Kun Ding, Hai-Mei Liu, Yong-Gang Wang

Journal of Electrochemistry

High-voltage n-type organic cathode materials are critical for constructing zinc-organic batteries (ZOBs) with high energy density and long cycle life. However, the intrinsically unfavorable electronic structures and relatively high LUMO energy levels of most n-type materials often lead to sluggish kinetics, high solubility, and suboptimal discharge voltages (< 0.8 V). Here, we design a small molecule, quinoxalino[2’,3’:5,6]pyrazino[2,3-f][1,10]phenanthroline (DPQP), as a ZOB cathode by introducing locally electron-deficient motifs into the conjugated backbone of aromatic compounds. The linearly fused pyrazine units extending the pyrazine–benzene framework effectively optimize the electronic structure, thereby significantly enhancing the discharge voltage. Meanwhile, the expanded π-conjugated plane suppresses dissolution and accelerates charge-transfer kinetics. Benefiting from these features, the DPQP electrode exhibits an exceptional increase in average operating voltage from 0.61 V to 1.07 V (vs. Zn²⁺/Zn) at 0.1 A·g^–1, with an overpotential of only 140 mV. Notably, no discernible voltage decay occurs as the current density increases, indicating rapid and highly reversible redox kinetics. Furthermore, the DPQP cathode delivers outstanding cycling stability, maintaining over 2000 h of continuous operation at 0.1 A·g^{–1 …}

(Co,Ni,Mn,Cu,Zn)O High-Entropy Oxide Nanotubes As Efficient Bifunctional Electrocatalyst For Oxygen Evolution And Hydrazine Oxidation Reactions, Pan-Yan Chen, Wan-Wan Wu, Heng Bian, Wei-Wei Li, Xin-Sheng Zhao, Lu Wei

Journal of Electrochemistry

High-entropy oxides (HEOs) present significant scientific challenges in both design and synthesis due to their multielement and high-entropy nature, which involves complex combinations of multiple metal cations and oxygen anions, typically arranged in equimolar ratios to achieve structural stability. Herein, one-dimensional (Co,Ni,Mn,Cu,Zn)O high-entropy oxide nanotubes (HEO-NTs) are fabricated by means of a gradient electrospinning strategy with a tailored polyvinyl alcohol (PVA) molecular weight distribution and controlled pyrolysis. Benefiting from the HEO features and the synergistic effect of multicomponent sites, the as-synthesized (Co,Ni,Mn,Cu,Zn)O HEO-NTs exhibit exceptional bifunctional electrocatalytic activity for the oxygen evolution and hydrazine oxidation reactions (OER/HzOR). This study offers …

Measuring Stock Market Inefficiency Using A Multilayer Composite Efficiency Index: A Case Of The Egyptian Exchange, Patrick K. Owido, Hiroki Sayama

Northeast Journal of Complex Systems (NEJCS)

Financial markets play a critical role in resource allocation. Their performance depends on the decisions of millions of independent investors constantly reacting to one another. Their informational efficiency remains a subject of debate across economic systems. When informational efficiency is present at the weak form, historical price information should not consistently predict future returns. Several empirical tests of this hypothesis often focus on the behavior of aggregate market indices, and use individual efficiency proxies such as autocorrelation, GARCH-type volatility, or entropy-based measures to measure efficiency. This has often yielded mixed results, particularly in emerging markets. Here we show that testing …

Enhanced Population Mean Estimation Using An Exponential Estimator With Known Medians Of Dual Auxiliary Variables Within A Neutrosophic Approach: Applications In Agricultural Yield Prediction, Anchal Yadav, Mukesh Kumar

Neutrosophic Systems with Applications

In classical statistical theory, estimation of population parameters is generally carried out under the assumption that all observed data are precise, complete, and free from ambiguity. However, in many practical and real-world situations, data often deviate from these ideal conditions and instead appear in vague, uncertain, or interval-valued forms. Such imperfections reduce the effectiveness of traditional estimation techniques and motivate the development of more flexible and robust methodologies. To address these challenges, several improved estimators, particularly neutrosophic ratio-type estimators and their advanced extensions, have been proposed in recent literature. In this study, a new estimator known as the two auxiliary …

On Some Properties Of Generalised Regular Anti-Topological Space, Bhimraj Basumatary, Gugu Narzary, Jeevan Krishna Khaklary

Neutrosophic Systems with Applications

This article studies Regular Anti-open sets and Generalised Regular Anti-open sets within a topological framework, addressing the limited development of anti-open structures in generalised topology. We introduce Regular Anti-open sets and establish their fundamental properties. The study is extended by defining Generalised Regular Anti-open sets, providing a broader and more flexible class of sets. Furthermore, the notions of GR-interior and GR-closure are introduced and analyzed, and their essential properties are obtained. The results contribute to a clearer understanding of generalized anti-open structures and provide a basis for further research in topology.

Optimization Of A Multi-Item Supply Chain Model With Shortages Under Parametric Type-2 Interval Environments, Sourav Kumar Kumar Giri, Totan Garai, Sahidul Islam, Haridas Mondal, Shariful Alam

Neutrosophic Systems with Applications

Modern supply chain systems frequently operate in environments where demand, costs and inventory-related parameters are uncertain and difficult to estimate accurately. These uncertainties become more critical in multi-objective decision-making situations, where decision makers must simultaneously balance several conflicting goals. Conventional optimization techniques often fail to represent the ambiguity and vagueness present in practical decision environments. To overcome these limitations, this study develops a multi-item supply chain model for a single supplier and a single buyer by incorporating Type-2 interval representations into the modelling framework. The proposed approach introduces a structured set of arithmetic operations for Type-2 intervals to manage uncertain …

Classes Of Analytic Functions Defined By Salagean Derivative Operator Associated With Neutrosophic Generalized Poisson Distribution, Soliu O. Opeyemi Okunola, Olushola Adeyemo, Sayo A. Abidemi Gbangbala, Folorunso I. Isola Akinwale

Neutrosophic Systems with Applications

This study introduces and analyses new subclasses of analytic functions by applying the Salagean derivative operator to the Neutrosophic Generalized Poisson Distribution (NGPD) series. We develop a model where the mean parameter is treated as an interval or set to account for indeterminacy in complex systems. By employing Stirling numbers of the second kind and decreasing factorials, we derive necessary and sufficient coefficient inequalities and inclusion relations for these new subclasses. Numerical results and graphical illustrations demonstrate the sensitivity of these functions to orientation and the neutrosophic parameter, providing a framework for applications in fields like medical imaging and network …

A Goal Programming Approach For Finding The Best Compromise Solution Of Multiobjective Linear Programming Under Neutrosophic Environment, Sultan S. Alodhaibi, Hamiden Abd El- Wahed Khalifa

Neutrosophic Systems with Applications

Decision problems often involve multiple objectives that conflict, making simultaneous optimization impossible. These problems require trade-offs to achieve a solution that balances the competing goals. In this paper, the detailed discussion that is related to linear programming (SVTrNFMOLP) with single valued trapezoidal neutrosophic numbers is made. Furthermore, this study deals with all the related parameters and discussion. As rank function and due to its definition, the SVTrNFMOLP is transformed in the crisp MOLP. It is noticed that goal programming is best to get the best compromise solution. The advantages of the proposed approach are: The use of Tr allows the …

Mining And Sustainable Development In Sierra Leone: The Role Of Institutional Quality, Ibrahim Massaquoi

Journal of Sustainable Mining

While mining can drive economic growth, create jobs, and promote infrastructural development, it also poses risks to the environment, human health, and social well-being. Therefore, to achieve sustainable development, responsible mining is crucial. This study empirically examines the role of institutional quality in the mining-sustainable development nexus in Sierra Leone. With the use of the planetary pressures-adjusted human development index (PHDI) as a comprehensive measure of sustainable development, the study is able to integrate economic, social, and environmental dimensions. The autoregressive distributed lag (ARDL) model confirms the existence of both short-run and long-run dynamics. The results of the study show …

Integrated Passive Design Strategies For Enhancing Energy Performance Of Hotel Buildings In Hot-Arid Climates: A Simulation-Based Study, Esraa Ebrahiem Abu-Elenain

HBRC Journal

Sustainable architectural design strategies offer effective solutions for enhancing energy efficiency and reducing operational costs in energy-intensive buildings, such as hotels in hot-arid climates. However, limited research has addressed the integrated application of multiple passive design strategies within hotel buildings using a unified simulation-based framework. This study investigates the combined application of wind catchers (Malqaf), adaptive mashrabiya shading systems, and high-performance glazing on a proposed hotel floor in Ras Sedr, Egypt. The design was modeled in Autodesk Revit and analyzed through dynamic simulation using EnergyPlus. A comparative approach was adopted, including a baseline scenario and an improved design scenario. The …

Enhancing Social Activity Through Climate-Adaptive Design In Hot-Humid Campus Open-Spaces: A Case Study Of The University Of Basrah In Iraq, Noor A. Almansor, Farah Ahmed Thiab, Riyam Rajab Fenjan

HBRC Journal

Outdoor open spaces between university buildings support students' community interactions and academic achievements. However, in hot-humid climate zones, some of these spaces lack activity and experience social withdrawal due to thermal discomfort. This is seen on the University of Basrah campus. To address this, the study aimed to identify the most suitable climate-adaptive design pattern to improve thermal comfort and, in turn, enhance students' social presence in the University of Basrah's neglected, peripheral outdoor campus spaces. A convergent mixed-method case study was applied. First, measurable environmental and social factors were identified from related studies. Next, two open spaces in the …

The Impact Of Climate Change On Glass Facades: A Bibliometric Analysis, Pelin Akın, Güneş Mutlu Avinç

HBRC Journal

Climate change has direct impacts on the design and performance of building envelopes, necessitating new approaches in the discipline of architecture. In this study, a bibliometric analysis was conducted to understand the effects of climate change on glass façade systems. The 612 academic publications obtained from the Web of Science database were analyzed through R Studio Biblioshiny. Within the scope of the study, publication trends, key themes, prominent authors, institutions and geographical distributions were evaluated in detail. According to the findings of the research, it was indicated that research has gained momentum especially after 2016, focusing on themes such as …

A Hybrid Deep Learning Framework For Multi-Class Retinal Disease Classification, Ali M. Duhaim, Abbas M. Al-Bakry

AUIQ Technical Engineering Science

Ocular diseases such as diabetic retinopathy, glaucoma, and cataract remain major causes of vision loss worldwide, creating an increasing demand for accurate and reliable automated diagnostic systems. Although deep learning techniques have demonstrated strong performance in retinal image analysis, their clinical adoption is still limited by challenges related to predictive reliability, robustness, and interpretability. This study presents HEFR-Net (Hybrid EfficientNet-B3 and ResNet-50 Feature-Fusion Network), a hybrid deep learning framework designed for multi-class classification of retinal fundus images. The proposed architecture integrates EfficientNet-B3 and ResNet-50 through feature-level fusion, enabling the model to capture both fine-grained texture patterns and high-level structural characteristics …

From Follower To Leader: Seismic Coal Exploration Techniques In China Over The Past 70 Years−In Celebration Of The 70th Anniversary Of Ccteg Xi’An Research Institute (Group) Co., Ltd., Cheng Jianyuan, Wang Yunhong, Wang Baoli, Li Gang, Li Yuteng, Qin Si

Coal Geology & Exploration

Background After 70 years of innovation and development, China has successfully transformed from a follower into a leader in both high-resolution surface seismic coal exploration techniques and underground in-seam seismic exploration techniques for coal mines. Furthermore, it has achieved disruptive innovations in intelligent seismic-while-mining (SWM) and seismic-while-tunneling (SWT) techniques. These achievements have established China’s worldwide leading position in the overall development of seismic coal exploration techniques.Advances In terms of high-resolution surface seismic coal exploration techniques, China has undergone four development stages: arduously catching up, striving to follow, keeping pace with continuously, and overtaking international counterparts with advanced techniques during …

Key Techniques For Volume Fracturing Of Deep Coalbed Methane Reservoirs And Their Applications: A Case Study Of The Daning-Jixian Block, Li Shuguang, Xiong Xianyue, Zhen Huaibin, Bai Kunsen, Ji Yuan, Yuan Pu, Li Zhongbai, Zhu Weiping

Coal Geology & Exploration

Background Deep coalbed methane (CBM) reservoirs generally exhibit ultra-low porosity and permeability, high stress, predominance of nanopores, and complex fracture propagation. These characteristics complicate reservoir stimulation, thereby restricting the enhancement in single-well productivity and commercial exploitation. Since 2019, technologies for deep CBM recovery have evolved from volumetric acid fracturing, which highlights the enhancement of matrix permeability, into large-scale volume fracturing focusing on the elevation of both the fracture network scale and proppant efficiency. In 2023, ultra-large-scale volume fracturing aimed at maximizing estimated ultimate recovery (EUR) was further developed. However, the implementation of this novel technique poses challenges such as a …

Sealing Performance Evaluation Criteria And Profile Optimization Of The Volumetric Cavities Of Positive Displacement Motors For Directional Drilling, Kuang Yuchun, Hu Xin, Zhou Jingpei, Luo Jinwu, Liu Yihui, Han Yiwei

Coal Geology & Exploration

Objective Constrained by complex stratigraphic conditions in underground coal mines, directional drilling faces challenges such as low efficiency when encountering medium-hard and hard formations. Positive displacement motors (PDMs) with a diameter of 89 mm are commonly used for directional drilling. Their efficiency is primarily influenced by the sealing performance of their volumetric cavities, which further significantly affects the drilling efficiency. Methods Based on the structural characteristics of the three-dimensional (3D) volumetric cavities of PDMs and the simulation method of two-way fluid-structure interactions, this study proposed the criteria for quantitatively evaluating the efficiency and volumetric cavity performance of PDMs, followed by …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

Instruments For Simulation Experiments On Coal-Rock Dynamic Disasters In China: Current Status And Key Challenges, Yuan Liang, Tang Haopeng, Ma Yankun, Wu Hua, Zhang Yachao, Jiao Biao, Wang Hao

Coal Geology & Exploration

Background Coal-rock dynamic disasters represent engineering disasters caused by the instability of the multi-phase and multi-field coupling of coal strata under mining disturbances, severely restricting the safe exploitation of deep coal resources. Elucidating the disaster-inducing mechanisms lays the foundation for exploring effective monitoring and early warning, along with prevention and control technologies, while instruments for simulation experiments provide crucial tools for investigating the mechanisms. Gradually increasing scientific and technological level has contributed to the continuous improvement in China's independently developed instruments for simulation experiments on coal-rock dynamic disasters. However, as engineering activities progressively extend toward deep parts, the multi-phase and …

Biogeochemical Mechanisms Behind Water Quality Evolution And Valuable Element Reutilization Of Abandoned Mine Drainage: A Review, Wu Pan, Huang Jiangxun, Li Qingguang, Zhang Ruixue, Li Bo

Coal Geology & Exploration

Background Abandoned mine drainage, also known as acidic mine drainage (AMD), represents a major pollution source in mining areas while also serving as an important carrier of strategic critical metals and underground space utilization. In China, water pollution stemming from coal mining is more severe in the south than in the north. This spatial pattern is jointly shaped by climatic conditions, geological settings, and mining history. Advances From the perspective of the environmental geochemical frontier, this study presents a systematic review of AMD formation and evolution mechanisms, as well as technologies for water pollution prevention and control, resource recovery, and …