General-purpose Software Research Articles

Statistical analyses of solution methods for the multiple-choice knapsack problem with setups: Implications for OR practitioners

An interesting extension of the classic Knapsack Problem (KP) is the Multiple-Choice Knapsack Problem with Setups (MCKS) which is focused on solving practical applications that involve both multiple periods and setups. Sophisticated solution methods for the MCKS that are presented in the operations research (OR) literature are not readily available for use by OR practitioners. Using MCKS test instances that appear in the literature, we demonstrate that the general-purpose integer programming software Gurobi sometimes used in an iterative manner can efficiently solve these MCKS instances using all default parameter values on a standard PC. It is shown both empirically and statistically that these Gurobi solutions are competitive with solution approaches from the literature. Hence, our approach using Gurobi is both easy for the OR practitioner to use and gives results competitive with the best specialized MCKS solution methods in the literature without the need to generate algorithm-specific code. Furthermore, this paper presents significant concerns regarding the solutions stated in the literature by the approximate solution method that reports the best results on 120 MCKS test instances. Specifically, 26% of this method’s solutions violate Gurobi upper bounds and an additional 33% of its solutions, on average, exceed the known guaranteed optimums by a value of 12,510.

Investigation of the Use of Computer-aided Translation (CAT) Tools in Freelancing Practice in Saudi Arabia

To cope with large information content in today’s multilingual Saudi Arabia, translation services are essential. Like any other industry, translation practice was heavily affected by technological advances. Professionals in the translation field use technology like Computer-Aided Translation (CAT) tools to complete their translation tasks. Freelance translators are not exempt from this. This study examines the utilization of CAT tools in the freelance industry in Saudi Arabia. Fulford and Granell-Zafra (2005) have proposed a model that incorporates both information and Communication Technology (ICTs)and CAT tools, facilitating a diverse array of activities such as document creation, information search and retrieval, communication, business management, marketing, procurement, and translation. While CAT tools support document creation, business management, and translation, ICT tools are responsible for the remaining activates . This research aims to thoroughly analyze the characteristics of Saudi freelance translators who use CAT tools, evaluate their usage of CAT tools, and acquire valuable insights into their overall attitudes towards CAT tool. The data was gathered using the survey method and distributed among 98 Saudi freelance translators. The data was analyzed using SPSS descriptive analysis and frequency tables showing percentages of each respondent. The results show that Saudi freelance translators employed general-purpose software like MS Word and MS PowerPoint, whereas less interest was given to special-purpose software which represent CAT tools . The vast majority of the participants agreed on the positive effect of CAT tools. Finally,it may be beneficial to conduct further research to gain a more comprehensive understanding of the topic.

A Foundational Study on Rational Optimization of Damping Ratio for Accurate Dynamic Simulation with Ultra Large Displacement

The integration of dynamic simulation analysis has become widespread in general-purpose software, providing enhanced capabilities. However, accurately tracking deformations based on complete equilibrium solutions remains a significant challenge in problems characterized by strong geometric nonlinearity. This study examines the accuracy of the combined Newmark β method and Tangent stiffness method in dynamic analysis with ultra large displacements and evaluates the utility of Rayleigh proportional damping in numerical simulations compared to experimental models. An experimental model of a slender steel plate undergoing free vibrations after being released from a deformed state was created. Video footage capturing the deformation histories was compared to computational simulations to verify accuracy. The study also examines the appropriate values of the damping ratio (ζ) and the Newmark β value in the simulations. The results indicate that adjusting various damping ratio and a β value of 1/2 yield more realistic simulations with longer conservation of mechanical energy. The findings suggest that incorporating numerical damping into actual damping settings can achieve a more realistic simulation of dynamic behaviour with ultra-large displacements. Furthermore, experiments and analyses were performed to correct natural frequency by changing Young’s modulus, which is a key factor influencing natural frequencies, with observed correlations to plate thickness, setting the stage for further research under varied conditions to develop a more rational methodology for structural analysis.

An alternative modeling approach to incorporate bond-slip effects in fiber-based elements

Fiber-based elements can provide accurate estimates of the global and local inelastic response of RC members subjected to reversed cyclic loads. However, fiber-based elements per se do not account for the localized deformations that arise from strain penetration or bond-slip effects at the member ends. To account for bond-slip effects, some researchers have suggested the use of modified properties for the steel reinforcement fibers, or that a zero-length element be attached at the element ends. In this study, a modified modeling procedure is proposed to include anchorage-slip effects in reinforced concrete frame members modeled with fiber-based beam-column elements. The proposed modeling approach is based on local bond-slip laws that can be implemented in general-purpose fiber-element software, and it differs from existing approaches in that it does not require the use of a zero-length element (though it could be used), and that it can be used with any local bond-slip relationship representative of a variety of bar embedment conditions. As such, the model can be used to simulate the effects of bond-slip of short or long embedment lengths in confined or unconfined concrete. The proposed modeling procedure is validated by comparing the calculated response with experimental data from four independent investigations. The test data included three columns and two beam specimens with various confinement and reinforcement configurations and included members reinforced with conventional and high-strength steel reinforcement. The results from the analyses show that the proposed modeling procedure provides a very good estimate of both the global and the local responses (anchorage-slip rotation) of the specimens.

Efficient Cardiovascular Parameters Estimation for Fluid-Structure Simulations Using Gappy Proper Orthogonal Decomposition.

As full-scale detailed hemodynamic simulations of the entire vasculature are not feasible, numerical analysis should be focused on specific regions of the cardiovascular system, which requires the identification of lumped parameters to represent the patient behavior outside the simulated computational domain. We present a novel technique for estimating cardiovascular model parameters using gappy Proper Orthogonal Decomposition (g-POD). A POD basis is constructed with FSI simulations for different values of the lumped model parameters, and a linear operator is applied to retain information that can be compared to the available patient measurements. Then, the POD coefficients of the reconstructed solution are computed either by projecting patient measurements or by solving a minimization problem with constraints. The POD reconstruction is then used to estimate the model parameters. In the first test case, the parameter values of a 3-element Windkessel model are approximated using artificial patient measurements, obtaining a relative error of less than 4.2%. In the second case, 4 sets of 3-element Windkessel are approximated in a patient's aorta geometry, resulting in an error of less than 8% for the flow and less than 5% for the pressure. The method shows accurate results even with noisy patient data. It automatically calculates the delay between measurements and simulations and has flexibility in the types of patient measurements that can handle (at specific points, spatial or time averaged). The method is easy to implement and can be used in simulations performed in general-purpose FSI software.

Behavior of container berth structure under the influence of environmental and operational loads

Abstract Container docks, which are an essential component of the marine berth, are exposed to loads from various sources, such as self-weight, operation, and environment. In this study, four sets of combined loads to which the container berth is exposed were selected at the Um-Qaser Port in southern Iraq. The berth was constructed more than 40 years ago, which has to be verified according to latest specifications, and each set of combined loads was analyzed in three cases. In the first case, the piles were assumed to be fixed at the seabed, and in the second and third cases the piles were modeled as embedded in elastic and elasto-plastic sandy soil, respectively. The general-purpose finite-element software ABAQUS was used to model the various components to determine the maximum stresses, displacements, axial forces, shear forces, and bending moments due to dead, live, operate, berthing, mooring, waves, and seismic loads. It has been demonstrated that the impact loads of ships have a more significant impact on the structure compared to other loads. The calculated displacement when the piles are assumed to be fixed at the seabed level may be reduced by 50–94% of that calculated when the soil is modeled, meaning that assuming fixed piles yields inaccurate results, especially for deck displacements. However, this assumption was verified to yield reasonable results for shear forces at the pile head. It could also be noted that the elasto-plastic model of soil was more sensitive than the elastic model in displacement by 0.4–8% and bending moment by 0.3–34%, while it is less sensitive in axial force by 3–8%. The aim of this study is to obtain knowledge on the behavior and efficiency of container berth under the influence of different loads and the environmental conditions surrounding it.

High-order discretization–based self-adaptive turbulence eddy simulation for supersonic base flow with PHengLEI software

PurposeThe purpose of the present study is to develop a new numerical framework that can predict the supersonic base flow more accurately, including the development of axisymmetrically separated shear layer and recompression shock. To this end, two aspects are improved and combined, i.e. a newly self-adaptive turbulence eddy simulation (SATES) turbulence modeling method and a high-order discretization numerical scheme. Furthermore, the performance of the new numerical framework within a general-purpose PHengLEI software is assessed in detail.Design/methodology/approachSatisfactory prediction of the supersonic separated shear layer with unsteady wake flow is quite challenging. By using a unified turbulence model called SATES combining high-order accurate discretization numerical schemes, the present study first assesses the performance of newly developed SATES for supersonic axisymmetric separation flows. A high-order finite differencing-based compressible computational fluid dynamics (CFD) code called PHengLEI is developed and several different numerical schemes are used to investigate the effects on shock-turbulence interactions, which include the monotonic upstream-centered scheme for conservation laws (MUSCL), weighted compact nonlinear scheme (WCNS) and hybrid cell-edge and cell-node dissipative compact scheme (HDCS).FindingsCompared with the available experimental data and the numerical predictions, the results of SATES by using high-order accurate WCNS or HDCS schemes agree better with the experiments than the results by using the MUSCL scheme. The WCNS and HDCS can also significantly improve the prediction of flow physics in terms of the instability of the annular shear layer and the evolution of the turbulent wake.Research limitations/implicationsThe small deviations in the recirculation region can be found between the present numerical results and experimental data, which could be caused by the inaccurate incoming boundary layer condition and compressible effects. Therefore, a proper incoming boundary layer condition with turbulent fluctuations and compressibility effects need to be considered to further improve the accuracy of simulations.Practical implicationsThe present study evaluates a high-order discretization-based SATES turbulence model for supersonic separation flows, which is quite valuable for improving the calculation accuracy of aeronautics applications, especially in supersonic conditions.Originality/valueFor the first time, the newly developed SATES turbulence modeling method combining the high-order accurate WCNS or HDCS numerical schemes is implemented on the PHengLEI software and successfully applied for the simulations of supersonic separation flows, and satisfactory results are obtained. The unsteady evolutions of the supersonic annular shear layer are analyzed, and the hairpin vortex structures are found in the simulation.

On Binscatter

Binscatter is a popular method for visualizing bivariate relationships and conducting informal specification testing. We study the properties of this method formally and develop enhanced visualization and econometric binscatter tools. These include estimating conditional means with optimal binning and quantifying uncertainty. We also highlight a methodological problem related to covariate adjustment that can yield incorrect conclusions. We revisit two applications using our methodology and find substantially different results relative to those obtained using prior informal binscatter methods. General purpose software in Python, R, and Stata is provided. Our technical work is of independent interest for the nonparametric partition-based estimation literature. (JEL C13, C14, C18, C51, O31, R32)

BYOG : Multi-Channel, Real-time LoRaWAN Gateway Testbed using General-purpose Software Defined Radio

BYOG : Multi-Channel, Real-time LoRaWAN Gateway Testbed using General-purpose Software Defined Radio

REPrune: Channel Pruning via Kernel Representative Selection

Channel pruning is widely accepted to accelerate modern convolutional neural networks (CNNs). The resulting pruned model benefits from its immediate deployment on general-purpose software and hardware resources. However, its large pruning granularity, specifically at the unit of a convolution filter, often leads to undesirable accuracy drops due to the inflexibility of deciding how and where to introduce sparsity to the CNNs. In this paper, we propose REPrune, a novel channel pruning technique that emulates kernel pruning, fully exploiting the finer but structured granularity. REPrune identifies similar kernels within each channel using agglomerative clustering. Then, it selects filters that maximize the incorporation of kernel representatives while optimizing the maximum cluster coverage problem. By integrating with a simultaneous training-pruning paradigm, REPrune promotes efficient, progressive pruning throughout training CNNs, avoiding the conventional train-prune-finetune sequence. Experimental results highlight that REPrune performs better in computer vision tasks than existing methods, effectively achieving a balance between acceleration ratio and performance retention.

3D-printed custom tray for maxillofacial implant assisted partial denture.

This technique presents a new fabrication workflow for a three-dimensional (3D) printed custom tray, which duplicates the morphology of the treatment denture for maxillofacial prostheses using an intraoral scanner, computer-aideddesign (CAD) software, and a 3D printer. A 70-year-old man underwent reconstruction of segmental mandibulectomy for mandibular osteoblastoma, followed by implant placement and secondary surgery. During the surgical treatment, a treatment denture was fabricated to restore oral function and determine the morphology of the definitive denture. To create the definitive denture with the same morphology as the treatment denture a custom tray was fabricated with the denture morphology after chairside adjustments. The oral cavity was scanned using an intraoral scanner, and the data acquired were imported into general-purpose CAD software, adjusted, and imported into a 3D printer to produce the custom tray. This was fitted into the patient's mouth without any issues, and closed tray impressions were made with impression caps for the locator attachments on the implant body. The morphology of the treatment denture was replicated in the definitive denture by making a silicon impression of the cameo surface at the fabrication of the cast after impression making. In this technique, the morphology of the treatment denture was transferred accurately to the definitive implant partial denture by leveraging existing digital technology. This method represents a practical approach for partial denture fabrication, including maxillofacial defects with complex denture configurations.

A type system for formal verification of cyber-physical systems C/C++ software

The subject: This study focuses on improving the quality of Cyber-Physical System (CPS) software by eliminating incorrect usage of units of measurement and orientation in C/C++ programs. Incorrect usage often leads to critical errors that conventional systems cannot effectively prevent. Manual examination of code using dimensional and orientation analysis can detect these errors in physical equations, but these methods become impractical when dealing with complex physical computations. Objectives: As suggested by Siano, the proposed approach uses physical quantities and prefixes defined by the International System of Units and orientation operations on physical objects. The elaborated system incorporates dimensional and orientation analysis and metaprogramming techniques. The methods used are dimensional & orientational analysis and metaprogramming. The following results were obtained: ensuring consistency of the units, incorporating orientation operations into the programming model for accurately handling physical object rotations and alignments, and using Siano’s work to precisely manipulate object orientation, thereby reducing the likelihood of orientation-related errors. Checking physical dimensions and orientations during the compilation stage identifies potential software defects before code execution, thereby reducing debugging time and lowering the cost of addressing issues later in development. The elaborated system represents a crucial step towards safer and more dependable Cyber-Physical System applications. This approach allows us to identify approximately 90% of incorrect usage of program variables; additionally, it detects over 50% of erroneous operations during compilation and execution of large-scale programs in real-world conditions. Conclusions. Scientific novelty: it proposed and developed a specialized C++-type library for formal compile-time software verification of Cyber-Physical Systems software. The proposed C++-type library leverages dimensional and orientational analysis to enhance software quality, reliability, and real-time formal verification. Although the proposed method for formal verification is not tailor-made for cyber-physical objects and systems, given its primary focus on software-level concerns, it does exhibit adaptability for verifying general-purpose software that incorporates various physical parameters. This versatility extends to diverse domains such as educational, gaming, and simulation software.

Analytical and numerical investigation of second-order infinitesimal mechanism in rigid origami

This study investigates second-order infinitesimal mechanisms and bifurcation paths of rigid origamis with multiple-degree-of-freedom mechanisms. A truss model, consisting of pin-connected rigid bars, is employed for the infinitesimal mechanism analysis. The conditions for the existence of a second-order infinitesimal mechanism are analytically solved to investigate the combinations of the infinitesimal mechanism modes that are the potential finite mechanisms. Analytical solutions for simple crease patterns show the bifurcation of the deformation paths at the flat state, some disappeared combinations of the mechanism modes in a single path, and the relationship between the nodal displacement and axial force distribution. This comprehensive analysis, using analytical solutions, lays the foundation for understanding bifurcation and finite mechanism of rigid origami, which have not yet been fully explored. These properties are also verified in the finite deformation paths generated by large deformation analysis of a frame model consisting of frame members and hinges, which is suitable for the analysis using general-purpose finite element analysis software. The second-order infinitesimal mechanisms found in this study are confirmed to be able to be extended to the finite mechanisms.

Interoperability between structural and geotechnical analysis for the study of safety in existing bridges

In recent years, the engineering community has shown a significant increase in interest in the field of soil-structure interaction. This problem is undoubtedly one of the most complex. Despite the exponential increase in computer performance in the last two decades, followed by the continuous development of numerical methods, the interaction between structural analysis programs and geotechnical issues remains limited. Specialized calculation codes for structural engineering and geotechnical engineering often operate independently. The reason for this separation lies in the highly specialized capabilities that a solver designed for geotechnical issues must possess. However, it remains crucial to incorporate the structural element within its geotechnical context, especially in the case of structures that are fully or partially embedded in the ground, such as tunnels, retaining walls, bridge abutments, and so on. There exists a mutual and reciprocal influence of the stress-strain state: the stiffness (and strength) of the foundation determines the response of the structure, which in turn affects the response of the foundation through its own stiffness. In many projects, there is an increasing demand to develop analyses that harness the full potential of both the structural and geotechnical aspects. Hence, there is a clear need to establish a connection between these two computational environments. The proposed solution involves the interaction of two programs: Midas Civil, an essential tool for structural engineers, and Flac 3D, a general-purpose software for geotechnical engineering. As explained further, this interaction is made possible thanks to the flexibility and openness of both software codes. Referring to a real case study of a road bridge with a superstructure consisting of reinforced concrete beams, this paper will illustrate the main challenges, significant steps, and undeniable advantages obtained through this approach.

Численное моделирование процессов естественного проветривания карьера при вариации его глубины в условиях инверсионного состояния атмосферы

The research objective is to assess the influence of the background stratification parameter and the depth of an open pit mine on the time of natural ventilation of the mine and the level of atmospheric pollution at the upper side of the pit downwind of blasting operations in conditions of the North. An aerothermodynamic model of the atmosphere was used, in which the equations of dynamics in the approximation of incompressible fluid were supplemented with the heat transfer equation, and the buoyancy and background stratification mechanisms were taken into account. The model was created in a general-purpose COMSOL software package and makes it possible to study aerothermogasodynamics of the atmosphere in its various states. A two-dimensional CFD-model of the open pit atmosphere was tested using the recirculation ventilation process. The background stratification parameter (from 0.0 to +0.025 °С/m with the increment of 0.005 °С/m) and the quarry depth from 300 to 700 m were variated. The wind velocity of 1 m/s at the upper side of the pit, the initial location of the dust and gas cloud (in the center of the pit near its floor) and the slope angle of the pit wall of 45° were recorded. A significant increase in the time of natural ventilation of the open pit is demonstrated at intensifying inversion of the atmosphere. Two formation types of the maximum pollution area with the increasing pit depth are predicted: (1) displacement from the center to the lee side of the pit at neutral stratification; and (2) position in the center of the pit near its floor at positive background stratification. It is shown that increasing of both the pit depth and the background stratification parameter leads to a noticeable increase in the time to reach the maximum concentration at the upper side of the pit and a decrease in the value of this maximum. For the recirculation ventilation scheme, intensification of inversion in the atmosphere increases the time of natural ventilation, but reduces the level of atmospheric contamination at the upper side of the pit downstream.

Comparison of Solubilization Treatment Technologies for Phosphorus Release from Anaerobic Digestate of Livestock Manure

This study addresses the imminent threat of phosphorus (P) depletion, investigating anaerobically digested livestock manure as a high-concentration P alternative. To achieve this objective, Visual MINTEQ software, a general-purpose software used for chemical equilibrium modeling, was employed to simulate the alteration in P species fractions at different pH levels. The investigation further examined the variation in P release rates and electrical energy consumption across various pretreatment processes as influenced by pH levels. The results indicate a significant pH influence on P release, with enhanced efficacy under both acidic and alkaline conditions. At pH 2, total P concentration peaked at 684 mg·L−1, with 83.0% reactive P, in contrast with pH 10 conditions, which exhibited 504 mg·L−1 and 48.4%, respectively. P release increased with reaction time across all pretreatment processes. Sonication notably increased P release by 126.9%, with the highest reactive P release efficiency at 2.09 mg·L−1·Wh−1, emerging as an optimal process. Simulation results using Visual MINTEQ software indicate that the inclination for P release in alkaline conditions can be ascribed to the heightened presence of hydroxyapatite, brushite, and Ca-Fe (III)-phosphate bonds with rising pH levels. These simulation results, which are consistent with the experimental results, affirm the crucial influence of cations in determining P release on pH values.

Performance-based wind engineering assessment of a telecommunication mast utilizing Bayesian extreme wind velocity model

A promising design concept, the performance-based wind engineering methodology is adopted, implementing a finite element model (FEM) to analyse the structural behaviour of a telecommunication steel lattice mast. The integration of site-specific wind loading models into the standardized FEM-based design can be a powerful tool for design engineers. The tower being investigated, located in Central Hungary, is equipped with sensors to measure wind velocity and strains in chord members. The stochastic modelling of the extreme wind velocity, i.e., the basic wind velocity is assessed using the peak-over-threshold approach with an automated threshold selection method. To enhance the accuracy of the analysis, Bayesian inference is employed, combining the information from a relatively short duration of measurements collected at the tower site with a more extensive dataset from measurement locations across the country. Numerical model of the telecommunication mast subjected to wind loading is developed in a general-purpose finite element software. The probabilistic design system module is applied for performing probabilistic calculations of both serviceability criterion and load-bearing capacity of the structure using Monte Carlo simulation with Latin hypercube method. Numerical results are compared and validated with measurement data. The accuracy of wind load assessment is examined in this study, considering both the standardized design method according to EN 1993-3-1 and wind tunnel testing. The main objective is to demonstrate the potential of integrating the Performance-based Wind Design framework with a monitoring system and a finite element model, highlighting their combined benefits.

LibMBD: A general-purpose package for scalable quantum many-body dispersion calculations.

Many-body dispersion (MBD) is a powerful framework to treat van der Waals (vdW) dispersion interactions in density-functional theory and related atomistic modeling methods. Several independent implementations of MBD with varying degree of functionality exist across a number of electronic structure codes, which both limits the current users of those codes and complicates dissemination of new variants of MBD. Here, we develop and document libMBD, a library implementation of MBD that is functionally complete, efficient, easy to integrate with any electronic structure code, and already integrated in FHI-aims, DFTB+, VASP, Q-Chem, CASTEP, and Quantum ESPRESSO. libMBD is written in modern Fortran with bindings to C and Python, uses MPI/ScaLAPACK for parallelization, and implements MBD for both finite and periodic systems, with analytical gradients with respect to all input parameters. The computational cost has asymptotic cubic scaling with system size, and evaluation of gradients only changes the prefactor of the scaling law, with libMBD exhibiting strong scaling up to 256 processor cores. Other MBD properties beyond energy and gradients can be calculated with libMBD, such as the charge-density polarization, first-order Coulomb correction, the dielectric function, or the order-by-order expansion of the energy in the dipole interaction. Calculations on supramolecular complexes with MBD-corrected electronic structure methods and a meta-review of previous applications of MBD demonstrate the broad applicability of the libMBD package to treat vdW interactions.

A new open-source library based on novel high-resolution structure-preserving convection schemes

This work develops a new finite volume convection scheme and open-source library for convection-dominated problems on unstructured grids. The formulated reconstruction operators can realize high-resolution and structure-preserving properties by adjusting numerical dissipation and anti-dissipation errors in a unified normalized-variable diagram. Then, this work develops a new open-source library based on the devised schemes within one of the most widely used general-purpose open-source software whose solution quality is intrinsically limited by the low accuracy of the conventional total variation diminishing schemes. The performance of the new library is first verified by some fundamental problems including pure advection and inviscid Euler equations. The numerical results of the accuracy tests show that the developed interpolation library can significantly reduce numerical errors with a minor increased computational cost compared with the conventional second-order schemes. The complex profile advection test demonstrates that the new library can offer an improved structure-preserving property that gives essentially oscillation-free solutions and preserves the structures of the passive transported scalar. Furthermore, the robustness of the new library is validated by compressible high-speed flow simulations with irregular geometries. Thus, this work presents a new library of high-resolution structure-preserving schemes for the accurate and efficient discretization of the convection term which plays an essential role in a wide range of computational fluid dynamics. The source code of the new scheme and library are released via DOI:10.5281/zenodo.8399000.

Finite Element 3D Simulation Experiment on Shield Excavation

Shield technology is widely used in subway excavation projects, and the excavation of soil causes surface settlement, which affects the normal use and safety of the tunnel itself and surface buildings. Using Abaqus, a large general-purpose finite element software, a three-dimensional excavation finite element model of the shield tunnel is established, and the dynamic excavation process of the shield tunnel is finely simulated to derive the soil displacement settlement law during the shield excavation, and to discuss the influence of the change of the simulated values of the post-shield grouting pressure and support pressure on the maximum settlement (uplift) of the ground surface. The conclusions of the study have important theoretical and practical engineering significance.