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  • Open Access

    ARTICLE

    Image Watermarking Algorithm Base on the Second Order Derivative and Discrete Wavelet Transform

    Maazen Alsabaan1, Zaid Bin Faheem2, Yuanyuan Zhu2, Jehad Ali3,*

    CMC-Computers, Materials & Continua, Vol.84, No.1, pp. 491-512, 2025, DOI:10.32604/cmc.2025.064971 - 09 June 2025

    Abstract Image watermarking is a powerful tool for media protection and can provide promising results when combined with other defense mechanisms. Image watermarking can be used to protect the copyright of digital media by embedding a unique identifier that identifies the owner of the content. Image watermarking can also be used to verify the authenticity of digital media, such as images or videos, by ascertaining the watermark information. In this paper, a mathematical chaos-based image watermarking technique is proposed using discrete wavelet transform (DWT), chaotic map, and Laplacian operator. The DWT can be used to decompose… More >

  • Open Access

    ARTICLE

    A Robust Image Watermarking Based on DWT and RDWT Combined with Möbius Transformations

    Atheer Alrammahi1,2, Hedieh Sajedi1,*

    CMC-Computers, Materials & Continua, Vol.84, No.1, pp. 887-918, 2025, DOI:10.32604/cmc.2025.063866 - 09 June 2025

    Abstract Ensuring digital media security through robust image watermarking is essential to prevent unauthorized distribution, tampering, and copyright infringement. This study introduces a novel hybrid watermarking framework that integrates Discrete Wavelet Transform (DWT), Redundant Discrete Wavelet Transform (RDWT), and Möbius Transformations (MT), with optimization of transformation parameters achieved via a Genetic Algorithm (GA). By combining frequency and spatial domain techniques, the proposed method significantly enhances both the imperceptibility and robustness of watermark embedding. The approach leverages DWT and RDWT for multi-resolution decomposition, enabling watermark insertion in frequency subbands that balance visibility and resistance to attacks. RDWT,… More >

  • Open Access

    REVIEW

    State-of-the-Art Review on Seepage Instability and Water Inrush Mechanisms in Karst Collapse Columns

    Zhengzheng Cao1, Shuaiyang Zhang1, Cunhan Huang2,*, Feng Du3,4, Zhenhua Li3,4, Shuren Wang1, Wenqiang Wang3,4, Minglei Zhai3,4

    FDMP-Fluid Dynamics & Materials Processing, Vol.21, No.5, pp. 1007-1028, 2025, DOI:10.32604/fdmp.2025.062738 - 30 May 2025

    Abstract Karst collapse columns typically appear unpredictably and without a uniform spatial arrangement, posing challenges for mining operations and water inrush risk assessment. As major structural pathways for mine water inrush, they are responsible for some of the most frequent and severe water-related disasters in coal mining. Understanding the mechanisms of water inrush in these collapse columns is therefore essential for effective disaster prevention and control, making it a key research priority. Additionally, investigating the developmental characteristics of collapse columns is crucial for analyzing seepage instability mechanisms. In such a context, this paper provides a comprehensive… More > Graphic Abstract

    State-of-the-Art Review on Seepage Instability and Water Inrush Mechanisms in Karst Collapse Columns

  • Open Access

    ARTICLE

    Modeling Oil Production and Heat Distribution during Hot Water-Flooding in an Oil Reservoir

    Chinedu Nwaigwe1,2,*, Abdon Atangana2

    FDMP-Fluid Dynamics & Materials Processing, Vol.21, No.5, pp. 1239-1259, 2025, DOI:10.32604/fdmp.2025.059925 - 30 May 2025

    Abstract In the early stages of oil exploration, oil is produced through processes such as well drilling. Later, hot water may be injected into the well to improve production. A key challenge is understanding how the temperature and velocity of the injected hot water affect the production rate. This is the focus of the current study. It proposes variable-viscosity mathematical models for heat and water saturation in a reservoir containing Bonny-light crude oil, with the aim of investigating the effects of water temperature and velocity on the recovery rate. First, two sets of experimental data are… More >

  • Open Access

    ARTICLE

    Detection, Analysis, and Mapping of Potential Groundwater Areas in the Oued Lakhdar Watershed (Morocco): Using GIS and AHP Techniques

    Elhoucein Layati*, Omaima Elkbichi, Bahija Choukri, Mohamed El Ghachi

    Revue Internationale de Géomatique, Vol.34, pp. 277-300, 2025, DOI:10.32604/rig.2025.063846 - 30 May 2025

    Abstract Awareness of the impact of climate change, urbanization, population growth, and anthropogenic pressure on surface waters has led to the need for specialized studies on groundwater potential. Groundwater is an important source of freshwater, particularly in regions where surface water is scarce. With climate change, the need to rely on these waters to cope with water shortages and rising demand is becoming increasingly apparent. Remote sensing, the Analytic Hierarchy Process (AHP), and the Geographic Information System (GIS) are advanced spatial tools used in this study to assess groundwater potential in the Oued Lakhdar watershed, which… More >

  • Open Access

    ARTICLE

    The Influence of Water-Polymer Co-Flooding on the Development Effect of Oil Reservoirs

    Wensheng Zhou1,2, Chen Liu1,2, Deqiang Wang1,2, Bin Wang3, Yaguang Qu4,*

    Energy Engineering, Vol.122, No.6, pp. 2337-2354, 2025, DOI:10.32604/ee.2025.062530 - 29 May 2025

    Abstract The J oilfield in the Bohai has a long development history and has undergone comprehensive adjustment measures, including water injection and polymer injection. Following these adjustments, the injection and production well network now features coexistence of both polymer injection wells and water injection wells, which has negatively impacted production dynamics. Firstly, based on the adjusted reservoir well network in the J oilfield, a representative water-polymer co-injection well network was established. Subsequently, a numerical simulation model of this typical reservoir unit was developed using reservoir numerical simulation methods to confirm the interference issues associated with water-polymer More >

  • Open Access

    ARTICLE

    Performance Evaluation of Evacuated Tube Receiver at Various Flow Rates under Baghdad Climate with Nanofluid as Working Fluids

    Walaa M. Hashim, Israa S. Ahmed, Ayad K. Khlief*, Raed A. Jessam, Ameer Abed Jaddoa

    Energy Engineering, Vol.122, No.6, pp. 2485-2501, 2025, DOI:10.32604/ee.2025.061630 - 29 May 2025

    Abstract Achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge since the absorption peaks of common metal particles are usually located in the visible part of the radiation spectrum. This paper aims to present the results of experimental investigations on the thermal performance of heat pipe-type evacuated solar collectors. The experimented system consists of 15 tubes, providing the hot nanofluid to 100-L storage in a closed flow loop. The solar collector with a gross area of 2.1 m2 is part of the solar hot water test system located in Baghdad-Iraq. Al2O3 nanofluid at… More >

  • Open Access

    ARTICLE

    Performance Analysis of Solar Porous Media Collector Integrated with Thermal Energy Storage Charged by CuFe2O4/Water Nanofluids Coil Tubes

    Ahmad Mola1, Sahira H. Ibrahim1, Nagham Q. Shari2, Hasanain A. Abdul Wahhab3,*

    Energy Engineering, Vol.122, No.6, pp. 2239-2255, 2025, DOI:10.32604/ee.2025.061590 - 29 May 2025

    Abstract High-efficiency solar energy systems are characterized by their designs, which primarily rely on effective concentration and conversion methods of solar radiation. Evaluation of the performance enhancement of flat plate solar collectors by integration with thermal energy storage could be achieved through simulation of proposed designs. The work aims to analyze a new solar collector integrated with a porous medium and shell and coiled tube heat exchanger. The heat transfer enhancement was investigated by varying the geometrical parameters in shell and helically coiled tubes operating with CuFe2O4/water with different volume fractions of 0.02%, 0.05%, and 0.1 vol.%.… More >

  • Open Access

    ARTICLE

    A Hybrid Deep Learning Method for Forecasting Reservoir Water Level from Sentinel-2 Satellite Images

    Hoang Thi Minh Chau1,2,3, Tran Thi Ngan4,*, Nguyen Long Giang5, Tran Manh Tuan6, Tran Kim Chau7

    CMC-Computers, Materials & Continua, Vol.83, No.3, pp. 4915-4937, 2025, DOI:10.32604/cmc.2025.062784 - 19 May 2025

    Abstract Global climate change, along with the rapid increase of the population, has put significant pressure on water security. A water reservoir is an effective solution for adjusting and ensuring water supply. In particular, the reservoir water level is an essential physical indicator for the reservoirs. Forecasting the reservoir water level effectively assists the managers in making decisions and plans related to reservoir management policies. In recent years, deep learning models have been widely applied to solve forecasting problems. In this study, we propose a novel hybrid deep learning model namely the YOLOv9_ConvLSTM that integrates YOLOv9,… More >

  • Open Access

    ARTICLE

    Robust Reversible Watermarking Technique Based on Improved Polar Harmonic Transform

    Muath AlShaikh*

    Computer Systems Science and Engineering, Vol.49, pp. 435-453, 2025, DOI:10.32604/csse.2025.062432 - 13 May 2025

    Abstract Many existing watermarking approaches aim to provide a Robust Reversible Data Hiding (RRDH) method. However, most of these approaches degrade under geometric and non-geometric attacks. This paper presents a novel RRDH approach using Polar Harmonic Fourier Moments (PHFMs) and linear interpolation. The primary objective is to enhance the robustness of the embedded watermark and improve the imperceptibility of the watermarked image. The proposed method leverages the high-fidelity and anti-geometric transformation properties of PHFMs. The image is transformed into the frequency domain of RRDH, after which compensation data is embedded using a two-dimensional RDH scheme. Linear… More >

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