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• Study on the Annular Fluid Level ­Identification­Algorithm­for­ Ultra-Deep Wells Based on Acoustic­Velocity­Correction

  K. Liu, C. Yang, M. Li, S. Tang, W. Hao, W. Wang, Y. Chen, Y. Li

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 21

  
  

  Abstract

  The geological conditions and pressure system of ultra-deep oil and gas wells are complex, and formation leakage conditions are prone to occur. Accurately obtaining the annular liquid level depth during leakage is crucial for treatment decisions. In the high-temperature and high-pressure wellbore environment of ultra-deep wells, the sound velocity shows a nonuniform variation trend, which seriously affects the accuracy of annular liquid level identification. Therefore, it is of significance to carry out a study on the annular fluid level identification algorithm based on acoustic velocity correction. Based on establishing a calculation model for the annular temperature and pressure field, a sound velocity calculation model in the annular air section was constructed. By combining the actual sound velocity of the clear signal segment identified through the echo signal, the basic parameters in the sound velocity calculation model can be calibrated to obtain the calibrated wellbore sound velocity distribution. Finally, tests were conducted on simulated well sites and noisy production wells to verify the accuracy of the annular liquid level identification algorithm constructed in this study. The results showed that the identification algorithm had an error of less than 2%. All in all, this study can effectively meet the demand for dynamic annular liquid level data during the leakage conditions, which is of great significance for the treatment and decisionmaking in deep and ultra-deep wells.OPEN ACCESS Received: 30/07/2025 Accepted: 25/09/2025 Published: 23/01/2026

  Abstract
  The geological conditions and pressure system of ultra-deep oil and gas wells are complex, and formation leakage conditions are prone to occur. Accurately obtaining the annular [...]

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• Functional H∞ Filtering for Descriptor Systems with Monotone Nonlinearities

  R. Sharma, M. Gupta, N. Tomar

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 18

  
  

  Abstract

  This paper proposes a new framework for the design of functional H∞ filters tailored for nonlinear descriptor systems affected by disturbances. Earliermethods have some significant drawbacks: they rely on the restrictive assumption of system regularity, employ implicit descriptor-form filters that complicate implementation, and emphasize full-order filtering, which is often unnecessary and computationally expensive. To overcome these drawbacks, the proposed filter is developed in an explicit state-space form that allows simple implementation with arbitrary initial conditions. Moreover, its order is minimized by matching it to the dimension of the functional vector, which reduces computational complexity compared to conventional filters. A new set of sufficient conditions is presented for the existence of a functionalH∞ filter, expressed through a rank condition and a linear matrix inequality (LMI) formulation. These conditions guarantee the stability of the estimation error dynamics while ensuring that the L2 gain from disturbances to errors remains below a specified bound. A numerical example based on a simple constrained mechanical system is presented to illustrate the effectiveness of the proposed method.

  Abstract
  This paper proposes a new framework for the design of functional H∞ filters tailored for nonlinear descriptor systems affected by disturbances. Earliermethods have some [...]

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• Bayesian and Non-Bayesian Inference for Discrete Model Based on Censored Samples with Optimal Test Plan

  R. Alotaibi, H. Rezk, E. Almetwally

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 20

  
  

  Abstract

  In reliability and lifetime studies, it is often impractical to observe the failure times of all units in a sample, particularly when the process is timeconsuming or expensive. Type II censoring addresses this by terminating the experiment after a predetermined number of failures from a total sample of size. The Discrete Alpha Power Extended Inverted Weibull distribution is particularly suitable for modeling such censored discrete lifetime data. Its flexible shape parameters allow it to capture a wide range of failure behaviors, including over-dispersion, which is common in censored datasets. In this context, the likelihood function and estimation procedures (maximum likelihood and Bayesian) explicitly account for the censoring, ensuring unbiased parameter estimates and reliable predictive inferences. Consequently, the Discrete Alpha Power Extended Inverted Weibull distribution provides a practical and statistically robust framework for analyzing discrete lifetimes under type II censoring.OPEN ACCESS Received: 28/07/2025 Accepted: 19/09/2025 Published: 23/01/2026

  Abstract
  In reliability and lifetime studies, it is often impractical to observe the failure times of all units in a sample, particularly when the process is timeconsuming or expensive. [...]

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• Drill Bit Optimization Method Using Grey Clustering and Grey Correlation Analysis

  G. Chen, Y. Ye, D. Wu, Y. Li, Z. Zhu, S. Li

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 19

  
  

  Abstract

  The conventional approach to drill bit selection primarily relies on the performance records of bits used in adjacent wells, where the bestperforming bit in each formation is selected for the corresponding zone to be drilled. However, this method does not take into account the lithology and rock mechanical properties of all relevant wells, nor can it evaluate the adaptability of a particular bit type to different intervals. As a result, it fails to fully ensure an optimal match between the bit and the formation, thus exhibiting significant limitations. To address these issues, this paper proposes a bit optimization method based on grey clustering and grey correlation analysis. This method comprehensively considers the influence of rock mechanics parameters on formation drillability and quantitatively evaluates the similarity in drilling resistance between the target formation and previously drilled intervals using grey clustering. This approach breaks away from the traditional constraint of limited bit options for a specific formation grade. Instead, it screens all previously used bit types to construct a candidate bit library for the target zone. Subsequently, the grey correlation method is applied to assess the candidate bits using multiple indicators that reflect bit performance. This enables the optimization of bit types for various target zones. Field applications demonstrate that the new bit selection method effectively improves upon the conventional practices by enhancing the flexibility and scientific basis of bit selection, and has yielded favorable results in actual drilling operations.OPEN ACCESS Received: 28/07/2025 Accepted: 16/10/2025 Published: 23/01/2026

  Abstract
  The conventional approach to drill bit selection primarily relies on the performance records of bits used in adjacent wells, where the bestperforming bit in each formation [...]

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• Design and Implementation of a Vulkan-Based Rasterization System in the PC Environment

  M. Kim, N. Baek

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 17

  
  

  Abstract

  Graphics application programming interfaces (APIs) for threedimensional (3D) rendering have been employed in computer graphics. Traditional 3D graphics APIs, such as Open Graphics Library (OpenGL), have structured the entire pipeline for the programmer’s convenience and are relatively easy to use. With the advancement of graphics hardware technology, new graphics APIs, including Vulkan, have been introduced to control specific function units of the graphics card and reveal the graphics processing power. Vulkan has many advantages, such as graphics processing power and parallel processing support. However, it also has the disadvantage of increasing the implementation costs because it requires detailed controls. This paper aims to implement a rasterization pipeline that applies a local illumination model with Vulkan. The implemented system can be used for standardized 3D graphics tasks as is and can also be used as a starting point for varying the pipeline configurations. This work designs and implements a Vulkan-based local rasterization pipeline. With this implemented platform, practical 3D rendering scenes are executed to be compared and analyzed with the rendering results from traditional OpenGL. The experimental results demonstrate the correctness and efficiency of the implementation. The implementation will be used as a testbed for various rendering experiments in the future.OPEN ACCESS Received: 27/07/2025 Accepted: 11/10/2025 Published: 23/01/2026

  Abstract
  Graphics application programming interfaces (APIs) for threedimensional (3D) rendering have been employed in computer graphics. Traditional 3D graphics APIs, such as Open [...]

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• Advanced Reliability Analysis with Applications of Hjorth Constant-Stress Normal-Operating Setting Using Newly Progressive Censored Data

  R. Alotaibi, M. Nassar, A. Elshahhat

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 16

  
  

  Abstract

  Modern high-reliability products fail rarely, so researchers rely on accelerated life testing to obtain failure information within practical time limits. This study presents a useful framework integrating constant-stress accelerated life tests with an improved adaptive progressive Type-II censoring plan to estimate the reliability function under normal operating conditions of the Hjorth model. The Hjorth model is chosen because its hazard rate can be constant, increasing, decreasing, or bathtub-shaped, which reduces errors due to incorrect hazard assumptions. Stress affects lifetime through a log-linear relationship applied to the scale and the shape parameter. We derive the full likelihood for the proposed censoring plan across several stress levels, obtain maximum likelihood estimates with confidence intervals based on the observed information matrix, and develop a Bayesian analysis with informative prior distributions and sampling by Markov chain Monte Carlo technique. We then estimate reliability at normal operating conditions together with its interval estimates by both approaches. Extensive Monte Carlo simulations demonstrate the superior accuracy of the Bayesian estimators, especially when the number of observed failures is small or censoring is heavy, while maintaining interval coverage close to the nominal level. The practical utility of the proposed methodology is demonstrated through its application to real-world accelerated lifetime data sets. Applications to real-world data sets show that the proposed model fits the data well and yields reliable estimates of reliability at normal operating conditions.OPEN ACCESS Received: 26/07/2025 Accepted: 28/10/2025 Published: 23/01/2026

  Abstract
  Modern high-reliability products fail rarely, so researchers rely on accelerated life testing to obtain failure information within practical time limits. This study presents [...]

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• Research on Correction Method for Pipe-Soil p-y Curves in Submarine Silty Clay-Sand Gas Hydrate Formations

  H. Diao, Y. Xia, B. Wu, F. Ban, L. Fu, H. Yang, K. Wang, A. He, X. Wang, P. Fu, H. Wang, C. Li, S. Deng

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 15

  
  

  Abstract

  The development of marine natural gas hydrates faces complex geomechanical challenges. Argillaceous silty hydrate reservoirs, due to their weak cementation and low permeability, have significantly different mechanical properties from those of general reservoirs. Based on the self-developed triaxial seepage experimental platform for hydrates, this paper systematically carried out triaxial compression experiments of argillaceous silt hydrate sediments, focusing on simulating the insitu temperature and pressure conditions of the formation, analyzing the influences of saturation, temperature and confining pressure on mechanical properties, and comparing them with the experimental results of sandy hydrate sediments. The experimental results show that due to the weak cementation effect of kaolin and methane hydrate, the failure mode of argillaceous silt hydrate is manifested as compression and dispersion, while sandy hydrate presents the traditional core compression failure characteristics. The peak strength of the stress-strain curve of argillaceous silt hydrate is lower than that of sandy hydrate, and the strain softening characteristic is more significant. The experimental results were calculated through MATLAB programming, and it was obtained that the cohesion and internal friction Angle of the argillaceous silt hydrate increased with saturation higher than those of the sandy hydrate. The pipe-soil coupling numerical simulation based on ABAQUS reveals that the initial stiffness and plastic deformation response of the p-y curve in the argillaceous silty hydrate formation are essentially different from those in the traditional API sandy soil model. By comparing the numerical simulation results of sandy properties and argillaceous silty hydrate, a two-parameter correction model for argillaceous silty strata was proposed. The cementation factor related to mass abundance and the displacement correction term were introduced. The error analysis indicated that the correction method was significantly superior to the API specification. Studies show that the mechanical properties of hydrates need to be evaluated independently, and the correction method provides a theoretical basis for the safety design of deep water well engineering.

  Abstract
  The development of marine natural gas hydrates faces complex geomechanical challenges. Argillaceous silty hydrate reservoirs, due to their weak cementation and low permeability, [...]

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• Bifurcation Analysis and Dynamical Investigation of Nonlinear DiffusionReaction Equations with Nonlinear Convective Flux Term: Stability and Applications

  M. Zahid, A. Bashir, K. Hosseini, M. Farman, A. Sambas

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 14

  
  

  Abstract

  The aim of this work is to examine the rich dynamics of quadratic and quartic nonlinear diffusion-reaction (DR) equations with a nonlinear convective flux term. These equations are crucial for simulating a variety of biological and physical processes, such as the dynamics of species populations. The main goal is to use the modified extended simple equation method (mESEM), a generalization of the standard simple equation method that hasn’t been used in this situation before, to extend the analytical treatment of such equations. We obtain a variety of new exact solutions using this method, such as breathers, kink and anti-kink waves, multi-peak solitons, bright-dark solitons, periodic waves, and waveforms represented by hyperbolic, trigonometric, and rational functions. Analyzing the stability and physical relevance of these solutions is another major goal of this work. Modulational instability analysis verifies the robustness of the obtained waveforms, while bifurcation analysis reveals qualitative changes in system behavior under parameter variations. The various wave structures and their dynamical characteristics are further highlighted with graphic illustrations. In general, the study highlights the potential of mESEM to reveal rich wave phenomena with applications spanning fluid dynamics, plasma physics, chemical reaction processes, population biology, neuroscience, and optical fiber communication, in addition to showcasing its effectiveness and versatility in solving nonlinear DR equations.OPEN ACCESS Received: 15/07/2025 Accepted: 18/09/2025 Published: 23/01/2026

  Abstract
  The aim of this work is to examine the rich dynamics of quadratic and quartic nonlinear diffusion-reaction (DR) equations with a nonlinear convective flux term. These equations [...]

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• Thermomechanical Uncertainty Analysis of Steel PartitionWalls Using Direct FE2 and Polynomial Chaos Expansion

  S. Yang, Y. Xu, L. Huang, L. Liu

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 12

  
  

  Abstract

  Steel partition walls are essential components in modern civil engineering, providing both structural support and spatial separation. These walls are frequently exposed to combined thermal and mechanical loads, particularly in specialized environments such as high-temperature workshops or fire scenarios, where their thermo-mechanical coupling behavior is critical to building safety and functionality. This study integrates the direct finite element squared (Direct FE2) method with generalized polynomial chaos expansion (PCE) to quantify the uncertainties in key material propertiesnamely, the elastic modulus and the coefficient of thermal expansionand to evaluate their effects on the thermo-mechanical performance of steel partition walls. The proposed approach enables efficient simulation of material uncertainties and their influence on structural behavior under coupled thermal-mechanical conditions. Case studies demonstrate both the accuracy and computational efficiency of the method, while sensitivity analysis highlights the most influential uncertainty factors. The integration of Direct FE2and PCE thus offers a robust framework for assessing the reliability of steel partition walls under uncertain conditions, providing valuable insights for design optimization and enhancing the safety and efficiency of building structures in practical applications.OPEN ACCESS Received: 05/07/2025 Accepted: 17/09/2025 Published: 23/01/2026

  Abstract
  Steel partition walls are essential components in modern civil engineering, providing both structural support and spatial separation. These walls are frequently exposed to [...]

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• Modeling Engineering Reliability Data Using the Modified Generalized Exponential Distribution

  H. Aljohani

  Rev. int. métodos numér. cálc. diseño ing. (2026). Vol. 42, (1), 11

  
  

  Abstract

  This study introduces the modified generalized exponential (MGEx) distribution, a flexible probabilistic model designed to capture complex failure behaviors commonly encountered in engineering systems. The MGEx distribution accommodates various hazard rate shapes, including unimodal, increasing, and decreasing forms, making it suitable for modeling reliability and lifetime data. We derive the mathematical properties of the model and focus on computational techniques for parameter estimation using multiple frequentist approaches. To evaluate the numerical performance of these methods, we conduct extensive Monte Carlo simulations, comparing their accuracy and robustness through partial and overall ranking metrics. The practical utility of the MGEx model is demonstrated by applying it to two real-world engineering datasets. The results highlight the model’s potential in enhancing simulation accuracy and supporting data-driven decision-making in reliability analysis, system design, and failure prediction tasks.OPEN ACCESS Received: 05/07/2025 Accepted: 27/10/2025 Published: 23/01/2026

  Abstract
  This study introduces the modified generalized exponential (MGEx) distribution, a flexible probabilistic model designed to capture complex failure behaviors commonly encountered [...]

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