Numerical Operations Research Articles

Sustaining 500,000 Folding Cycles through Bioinspired Stress Dispersion Design in Sodium-Ion Batteries.

Developing super-foldable electronic materials and devices presents a significant challenge, as intrinsic conductive materials are unable to achieve numerous true-folding operations (super-foldable) due to limitations from short-range forces of chemical bonds. Consequently, super-foldable batteries remain unexplored. This work focused on sodium-ion batteries as a breakthrough point to advance super-foldable devices. By employing a "2+1" bioinspired strategy, we stepwise designed and assembled super-foldable components, from substrates to electrodes, and to ultimately device. This bioinspired approach completely disperses folding stress and thus prevents the breakage of chemical bonds, enabling the successful fabrication of the first super-foldable ion battery. This battery can withstand true-folding at any angle, in any direction, and for an unprecedented number of cycles-far outperforming current foldable phones with hinge structures. Remarkably, after 500,000 true-folding cycles, the battery's microstructure remains intact with no significant degradation of electrochemical performance. Real-time dynamic folding observations reveal an M-shaped folding structure within the bioinspired materials, which effectively disperses stress via bulged layers, dispersed arcs, and slidable microgrooves that work together across different directions and dimensions to achieve super-foldability. Mechanical simulations vividly verify this principle. This work represents a breakthrough in super-foldable devices, offering valuable insights and promoting practical application for future super-foldable devices.

A Modification of Fenestration Technique (MOFT) to Increase Vestibular Depth: A Case Series.

The most prevalent mucogingival issues include insufficient gingival width, decreased vestibular depth, abnormal frenal attachment, gingival recession, pockets that reach the mucogingival junction, excess gingival, inconsistent gingival margin, excessive gingival display and abnormal gingival colour. Numerous periodontal plastic operations have been used to treat these issues. However, each approach has its own drawbacks and is technique-dependent. Adequate depth of vestibule is necessary to maintain good oral health as shallow vestibule leads to accumulation of food and thus impedes oral hygiene maintenance. This case series describes a vestibular deepening procedure performed using modification of periosteal fenestration technique. This technique includes a series of eight cases of shallow vestibule where vestibular deepening was conducted by giving a full-thickness incision to expose the periosteum and create a window of fenestration followed by suturing the labial mucosa to the periosteum at the apical level. The results reported an excellent post-operative outcome showing increased depth of the vestibule.

Frequency domain solution method for electromagnetic influence analysis on torsional vibrations

In electric motor-driven machines, mechanical torsional dynamics are nonlinearly coupled with the electrical system through the electromagnetic torque and the counter-electromotive force. In this paper, an approach based on small-signal linearization is proposed for modeling the steady-state torsional dynamics of the coupled system. Using the linearized model, resonance interference diagrams, torsional response, and stability can be evaluated rapidly across numerous operating points, while accurately accounting for the electromagnetic effects. The model is validated with conventional time-stepping simulations of two induction machines. An example analysis of a 3 MW motor-driven compressor train displays the modification of torsional properties due to the electromagnetic coupling effect and explains the mechanism of torsional destabilization. Finally, previously published measurements of a 37 kW motor test bench are considered to validate the instability of the elastic torsional mode predicted by the model.

Spurious numerical mixing under strong tidal forcing: a case study in the south-east Asian seas using the Symphonie model (v3.1.2)

Abstract. The role of mixing between layers of different densities is key to how the ocean works and interacts with other components of the Earth's system. Correctly accounting for its effect in numerical simulations is therefore of utmost importance. However, numerical models are still plagued with spurious sources of mixing, originating mostly from the vertical advection schemes in the case of fixed-coordinate models. As the number of phenomena explicitly resolved by models increases, so does the amplitude of resolved vertical motions and the amount of spurious numerical mixing, and regional models are no exception to this. This paper provides a clear illustration of this phenomenon in the context of simulating the south-east Asian (SEA) seas along with a simple way to reduce its impact. This region is known for its particularly strong internal tides and the fundamental role they play in the dynamic of the region. Using the Symphonie ocean model, simulations including and excluding tides and using a pseudo-third-order upwind advection scheme on the vertical are compared to several reference datasets, and the impact on water masses is assessed. The high diffusivity of this advection scheme is demonstrated along with the importance of accounting for tidal mixing for a correct representation of water masses. Simultaneously, we present an improvement in this advection scheme to make it more suitable for use in the vertical. Simulations with the new formulation are added for comparison. We conclude that the use of a higher-order numerical diffusion operator greatly improves the overall performance of the model.

Food Safety Management System (FSMS): An Analysis of Restaurant Certificate Schemes in Malaysia

Customers of restaurants encounter some degree of uncertainty or risk due to their inability to evaluate the food or service qualities received before or after meal consumption. The Food Safety Management System (FSMS) certification schemes are intended to reduce the incidence of foodborne illnesses in Malaysia and to be used as a communication instrument to address the issue of information asymmetry. This investigation investigates the diverse FSMS certification programs that are accessible to food establishments, with a particular emphasis on restaurant operations in Malaysia. The study is dedicated to the identification of the concept of various FSMS certificate schemes that are designed and implemented in Malaysian restaurant operations. It also discusses the fundamental concept of the role differences of each FSMS certificate scheme that is obtained by numerous restaurant operations in Malaysia to communicate with potential customers. A content analysis was conducted on ten independent Malaysian-owned restaurants that had obtained and disclosed their FSMS certifications online (i.e., through their official website or social media account) to the public. All participating restaurant premises believe food safety certification through appropriate authorities is crucial, particularly in the context of the provision of information regarding sanitation, safety, and nutrition to guarantee high food quality standards and service delivery. FSMS eliminates the knowledge asymmetry between producers and consumers and demonstrates that a certified party adheres to a recognised standard. This investigation suggested that the Food Safety Management System (FSMS) should function as more than merely a mechanism for guaranteeing the safety and quality of food for consumers. It contributes to the establishment of client trust and confidence in the restaurant and improves the image of food businesses.

Modeling cost-optimal fuel choices for truck, ship, and airplane fleets: The impact of sustainability commitments

For the next 25 years, numerous transport operators have introduced sustainability commitments to mitigate carbon emissions. However, static goals to reduce fossil fuel usage and adopt renewable fuel technologies pose economic risk. This study analyzes the costs of strategic fleet replacement through a mixed integer linear program. Comparing three Norwegian transport operators, we determine cost-optimal investments in fossil and renewable fuel technologies for two approaches: One integrating and the other neglecting sustainability commitments. Our findings reveal that the truck operator’s sustainability commitments incur minimal additional costs, with battery-electric trucks proving cost-effectiveness early. In contrast, ship and airplane operators exhibit significant differences in fleet replacement decisions, resulting in additional costs ranging from +6% to +31% for ships and +4% to +11% for airplanes, across fuel cost and carbon price scenarios. Norwegian carbon price regulations fall short in incentivizing a cost-competitive technology transition for ships and airplanes. Additional policies are needed to encourage gradual fleet replacement.

Geospatial Demand for Approved Cleft Care in the United States.

Geographic information systems are powerful tools for characterizing the geospatial factors influencing access to care. As patients with cleft lip and/or palate (CL/P) require long-term care, with numerous operations and therapies, access to timely, quality care is extremely important. This study uses population level analysis and geographic information systems to identify United States counties with limited access to American Cleft Palate Association-approved cleft teams. Natality data were queried from the National Vital Statistics System. Population and geographic data were obtained from the US Census Bureau. The Social Vulnerability Index (SVI) was utilized to account for social inequality. Total births with CL/P, population estimates, SVI, distance to the nearest center, and total centers within 50 km were used to generate the cleft care demand index (CCDI). Ninety-two counties had CCDIs between 66.7 and 100. The highest scoring county, Hidalgo County, Texas, had 62 births with CL/P, population estimate of 888,367 persons, distance to the nearest cleft center of 368.4 km, and SVI of 0.99. This study demonstrates the power of geographic information systems for identifying areas with limited access to approved cleft teams. The CCDI measures cleft burden, socioeconomic disadvantage, and geographic barriers to quantify the demand for approved cleft care in each county. Utilizing these scores can help direct future interventions, outreach efforts, and cleft care center planning.

Towards python program repair with generative pre-trained transformer (GPT-3.5)

ChatGPT has a great potential using a simple prompt design, which means further studies can be done to investigate the effect of different prompt designs. Complex software often contains hidden bugs in its source code. Recent study suggests that OpenAIs ChatGPT can perform numerous operations including code-to-code operations like code completion, translation, repair, and summarization, along with language-to-code operations such as code explanation and search. ChatGPTs dialogue capability can assist in generating more accurate bug fixes. However, it sometimes offers solutions without seeking further information, which can mislead users. To address this issue and enhance user experience, we conducted three design iterations to develop D-bugger a system enabling programmers to fix bugs more effectively. We conducted a survey to gauge the need for refinement, designed a low-fidelity prototype with key features, and then created a high-fidelity prototype evaluated by Python users. Our work aims to enhance the debugging process and user engagement.

STORMM: Structure and topology replica molecular mechanics for chemical simulations.

The Structure and TOpology Replica Molecular Mechanics (STORMM) code is a next-generation molecular simulation engine and associated libraries optimized for performance on fast, vectorized central processor units and graphics processing units (GPUs) with independent memory and tens of thousands of threads. STORMM is built to run thousands of independent molecular mechanical calculations on a single GPU with novel implementations that tune numerical precision, mathematical operations, and scarce on-chip memory resources to optimize throughput. The libraries are built around accessible classes with detailed documentation, supporting fine-grained parallelism and algorithm development as well as copying or swapping groups of systems on and off of the GPU. A primary intention of the STORMM libraries is to provide developers of atomic simulation methods with access to a high-performance molecular mechanics engine with extensive facilities to prototype and develop bespoke tools aimed toward drug discovery applications. In its present state, STORMM delivers molecular dynamics simulations of small molecules and small proteins in implicit solvent with tens to hundreds of times the throughput of conventional codes. The engineering paradigm transforms two of the most memory bandwidth-intensive aspects of condensed-phase dynamics, particle-mesh mapping, and valence interactions, into compute-bound problems for several times the scalability of existing programs. Numerical methods for compressing and streamlining the information present in stored coordinates and lookup tables are also presented, delivering improved accuracy over methods implemented in other molecular dynamics engines. The open-source code is released under the MIT license.

On design of preprocessing and postprocessing in cascaded-resonator-based harmonic analyzers and filter banks

The cascaded-resonator (CR)-based filter structure provides high attenuation in the stopbands thanks to the serially coupled resonators, which is an advantage in many applications of harmonic analyses and/or filtering. In addition to that, it has good properties provided by its parallel structure. On the other side, there are applications which besides the high stopband attenuation need wider (or even flat-top) passbands, lower group delays, etc. These performances can be modified/improved by preprocessing and postprocessing through reshaping of the primary CR-based filter bank frequency responses. The numerical complexity is also an important aspect where infinite impulse response (IIR) filters provide implementation with a smaller number of numerical operations, but involving nonlinearity of the phase responses and stability control issue. Although most of these issues have been discussed in the previous papers dealing with the design of the CR-based harmonic filtering and/or filter banks, the aim of this paper is to highlight them all together. In addition, some improvements of the previously described design techniques are suggested too.

Impact of working memory on arithmetic problem solving in primary school pupils with mathematical learning difficulties

Learning arithmetic operations is fundamental for social and professional emancipation, where counting and solving numerical operations is part of everyday behavior; this reflects the more or less serious difficulties that pupils with mathematics learning difficulties (MLD) may encounter. The interest of this work is to underline the importance of the cognitive deficit at the memory level in these subjects. In this sense we selected 30 pupils aged 7 to 8 years old, educated from 2nd to3rd year of the primary cycle with MLD on whom we applied tests of arithmetic problem solving and working memory (WM). Analysis of the results indicates a significant correlation between the difficulties recorded in arithmetic and WM. These results lead us to a systematic evaluation of WM in subjects with MLD, in any therapeutic diagnostic approach.

A 3D thermo-mechanical damage model for concrete including Short-Term Thermal Creep Strain (STTCS)

In the current study, a Short-Term Thermal Creep Strain (STTCS) model of concrete was innovatively developed. This model can predict the time-dependent deformation of concrete subjected to wide applied load level ranging from 20 % to 60 % and temperatures up to 900 °C. A creep compliance function was developed to study the nonlinear creep characteristics of concrete with creep parameters. The definition and sensitivity of the creep parameters were investigated. In order to comprehensively predict the performance of concrete subjected to multiaxial compressive loads in fire, an orthotropic triaxial compression thermo-mechanical damage model for concrete is developed. The influence of STTCS on the multiaxial stress-strain behaviors was taken into account in the multiaxial model. The coupling thermo-mechanical contributions containing the development of STTCS with thermal effect, stress confinement, plastic damage and hardening evolution were creatively considered in the potential function within thermodynamics framework. The sensitivity of yield surface was discussed. The numerical operations of this proposed model were conducted for validation. The nonlinear stress-strain responses of concrete were accurately captured at temperatures ranging from 20 °C to 800 °C through the comparative study with test results in literatures, which indicates the accuracy and applicability of the proposed model.

Unbiased density computation for stochastic resetting *

We establish a practical means for unbiased computation of the marginal probability density function of the dynamics under stochastic resetting. In contrast to conventional dynamics devoid of resetting, the marginal probability density function under resetting may exhibit cusps and, in multi-dimensions, explosions at reset positions, arising from the compelled displacement of mass. Standard numerical techniques, such as kernel density estimation, fall short in accurately reproducing those characteristics due to their inherent smoothing effects. The proposed unbiased estimation formulas are derived using advanced stochastic calculus in their general formulations, yet their implementation in specific problem settings involves only elementary numerical operations, requiring minimal mathematical expertise and marking the very first instance of a numerical method free from bias in this context. We present numerical results throughout to validate the derived estimation formulas and, more broadly, to demonstrate the effectiveness of our approach in accurately capturing the irregularities of the marginal probability density function.

Empowering Data Owners: An Efficient and Verifiable Scheme for Secure Data Deletion

Cloud services have attracted numerous enterprises, organizations, and individual users due to their exceptional computing power and almost limitless storage capacity. A vast amount of business data and private data are continuously uploaded to the cloud platform, driven by a series of attractive services offered by the cloud. Unfortunately, once data is uploaded to the cloud, its owner has no way of ensuring that it is actually deleted as intended. This obviously increases the concerns of data owners about the security of their data, because it is related to the privacy of users. Therefore, there must be a reliable solution to prove that data is deleted as requested by users, to prevent data leakage or abuse. In existing data deletion schemes, most are designed based on cryptographic knowledge rather than erasure or overwrite techniques, in order not to cause incalculable damage to the storage medium. However, most cryptographic-based data deletion schemes, particularly attribute-based encryption, involve numerous complex bilinear mapping operations, which are expensive for most devices. To address this issue, the paper proposes an Efficient and Verifiable Scheme for Secure Data Deletion (EVSD). Firstly, Elliptic Curve Cryptography (ECC) is introduced to achieve efficient encryption of data. Then, leveraging Linear Secret Sharing Scheme (LSSS), fine-grained data deletion policies supporting logical operations are implemented. Finally, the deletion of the data is efficiently verified using the root of the Merkle Hash Tree (MHT) generated by the defined illegal and legal attributes, while the deletion proof is also generated. Satisfactorily, security analysis shows that the EVSD scheme is much more advantageous compared to existing schemes, and a trait likewise is also observed in the performance evaluation.

Determination of flexural stiffness of composite timber beams using DIC and wavelet transform of deflection lines

The article presents an experiment of four-point bending of timber I-beams, the deflections of which were measured using digital image correlation (DIC). The deflection functions were subjected to a wavelet transform operation, which used the second derivative of the Gaussian distribution to determine the curvature of the beams’ axis. On this basis, the distribution of flexural stiffness of the elements was estimated, showing the potential usefulness of the DIC technique in production control and laboratory testing of prefabricated timber elements. The limitations of the proposed research method related to the need to perform numerical integration operations on discrete experimental data subject to measurement errors are also presented

Practical Aspects of Using Modern Laser Scanning Techniques for Measuring Mine Excavations

Abstract For more than a dozen or so years now, there has been growing interest in the use of modern laser scanning measurement methods in numerous mining operations engaged in underground excavation. However, the simple possession of a scanner does not guarantee satisfactory measurement results. This study sets out the results of scanning mine excavations in an active mine and describes the current guidelines on various aspects of the measurement process. These guidelines were developed on the basis of several hundred measurements carried out over the last dozen or so years. This study also outlines the typical measurements errors observed over the course of many years. These errors, resulting partly from hardware limitations and partly from human error when planning or actually performing measurements, were an important factor behind the introduction of standards regulating underground measurements. This study discusses in detail not only scanning that utilises traditional stationary laser scanners but also scanning based on mobile scanners. It also presents possible areas of future technological development in line with global trends.

Dynamic robot routing optimization: State–space decomposition for operations research-informed reinforcement learning

There is a growing interest in implementing artificial intelligence for operations research in the industrial environment. While numerous classic operations research solvers ensure optimal solutions, they often struggle with real-time dynamic objectives and environments, such as dynamic routing problems, which require periodic algorithmic recalibration. To deal with dynamic environments, deep reinforcement learning has shown great potential with its capability as a self-learning and optimizing mechanism. However, the real-world applications of reinforcement learning are relatively limited due to lengthy training time and inefficiency in high-dimensional state spaces. In this study, we introduce two methods to enhance reinforcement learning for dynamic routing optimization. The first method involves transferring knowledge from classic operations research solvers to reinforcement learning during training, which accelerates exploration and reduces lengthy training time. The second method uses a state–space decomposer to transform the high-dimensional state space into a low-dimensional latent space, which allows the reinforcement learning agent to learn efficiently in the latent space. Lastly, we demonstrate the applicability of our approach in an industrial application of an automated welding process, where our approach identifies the shortest welding pathway of an industrial robotic arm to weld a set of dynamically changing target nodes, poses and sizes. The suggested method cuts computation time by 25% to 50% compared to classic routing algorithms.

Integration of Control Strategies for Cleaning Based on Granular Computing

Cleaning control based on changes in cleaning loss rate and impurity rate has emerged as a hot topic in the research on intelligent control for rice and wheat combined harvesters. However, numerous operation parameters can lead to deviations beyond the normal range of cleaning loss rate and impurity rate. The impact of cleaning control parameters in rice and wheat combined harvesters on cleaning loss rate and impurity rate often tends to be contradictory. How to combine different contradictory cleaning control strategies to get a more widely used and better cleaning control strategy is a hot issue in the current cleaning control research. In this paper, the granularity of quotient space is introduced into the cleaning control based on operation parameters, and a cleaning control model based on granularity synthesis theory is proposed. This method first constructs a knowledge base for intelligent control of cleaning tailored to the cleaning loss rate and impurity rate using production rule representation, and considers that these control strategies constitute different quotient spaces, and then organizes these quotient spaces according to granularity synthesis theory to get the cleaning control strategy. The experimental results verify that the validity of the cleaning control based on granular computing is better than fuzzy control.

Numerical investigation of mixing and heat transfer in a 7.9 m JP-8 pool fire

The response of objects engulfed in, and adjacent to, large-scale pool fires is of interest in accident and safety assessments. In this study, Fuego, a low-Mach turbulent reacting flow code was used to study conjugate heat transfer in a 7.9 m diameter JP-8 pool fire. Simulations were designed to replicate past experimental measurements (Blanchat et al., 2006) of incident heat flux to three cylindrical calorimeters in and around the pool fire. Two turbulent combustion models were compared directly - the eddy dissipation concept and a more recently developed unsteady flamelet model. First and second order spatial and temporal discretization schemes were also compared to assess the performance of low-dissipation numerical operators. Heat flux predictions to the transportation size calorimeter outside the fire were within experimental uncertainties. Inside the fire, experimental measurements were higher than predicted values and may have been a consequence of soot deposition and augmented participating media radiation from soot and fuel vapor. Simulation predictions improved in cases where turbulent kinetic energy and mixing were more resolved. This work, and others referenced herein, suggest that spatial resolution on the order of 0.5–1.0 cm may be required to fully resolve fluid instabilities, vortex production between fire plumes and crosswind, soot production, and fuel-air mixing. This presents a substantial computational challenge for safety assessments of engulfed objects in fully turbulent pool fires.

Regenerative adventure tourism. Going beyond sustainability – a horizon 2050 paper

Purpose This study aims to provide an overview of the regenerative concept and how this can be implemented in adventure travel. It looks into the history of sustainable adventure tourism and showcases best practice examples. This study is encouraging operators within the adventure tourism industry to adopt a regenerative approach. Design/methodology/approach A comprehensive literature review on the paradigm of regenerative tourism has been conducted and applied to the adventure tourism industry. Three case studies of selected adventure tourism operators have been selected to enforce this concept. Findings With nature being an essential element of adventure travel, the industry has a long history in terms of sustainability. While tour operators, destination management organisations and other stakeholders are working towards sustainable products, consumers are still convenient and not willing to restrict themselves. The attitude behaviour gap is also noticeable in this segment and a rethinking is necessary. Through the pandemic and the climate crisis, among other aspects, a shift within the tourism industry is inevitable. Adventure tourism can be a role model in this process and good examples from the industry give hope for change. A concept that focuses on the solutions to address the polycrises is regenerative development, which is based on an ecological worldview and a living systems thinking and aims to restore locally visited communities and environments. Numerous operators have already taken measures to help local communities, such as starting projects for nature conservation or encouraging social justice. Research limitations/implications This is a conceptual review without an empirical foundation. The best-case examples are based on an Anglo-Western perspective. Originality/value To the best of the authors’ knowledge, this study is the first to provide an overview of the current state of research into sustainable adventure tourism and categorise it within the concept of regenerative tourism.