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Mathematical modeling is a high-leverage topic; it is critical to students' participation in STEM education and supports civic engagement. Until recently, research on modeling at the elementary level has been underemphasized, particularly research on supports and challenges for teachers who engage in designing authentic modeling tasks. In this study, we employed qualitative case study methods to investigate how elementary teachers designed and implemented authentic mathematical modeling tasks, with an explicit focus on how their tasks evidenced different dimensions of authenticity. We analyzed three cases of teams of elementary teachers as they developed modeling tasks connected to school and community contexts. The three cases were: 1) a student-driven modeling task related to paper and plastic waste in a school cafeteria, 2) a modeling task based on authentic situations at a community-run resource center, and 3) a modeling task focused on designing and monitoring a school community-building art project. Our cases illustrate that elementary teachers can successfully design and implement modeling activities that utilize different entry points and evidence multiple dimensions of authenticity. Furthermore, we found that the specific dimensions of authenticity may vary depending on the design supports and curriculum challenges within each context. [ABSTRACT FROM AUTHOR]

This study aimed to address these limitations by employing a systematic approach. Initially, body measurements of 115 children were meticulously recorded and subjected to statistical analysis. Subsequently, a children's jeans paper pattern was chosen, and a predictive model for pattern sizing was developed using BP neural networks. Additionally, a parametric mathematical model was constructed by integrating the design principles of the paper pattern. Using the Visual-LISP programming language on the Auto-CAD 2020 edition platform, an editing process was performed to create a children's jeans automatic drawing program. The predicted pattern size data for children's jeans were then imported into the DCL dialog box of Auto-CAD, enabling the automatic generation of paper patterns. To evaluate the effectiveness of the approach, the generated garment paper patterns were imported into the CLO-3D virtual fitting software. [ABSTRACT FROM AUTHOR]

A large variety of acid-free Asian and Western papers offer objects conservators numerous applications in their work. Not only have objects conservators borrowed this extraordinary material - paper - from the field of paper conservation but they have also adopted many of the well-developed methods and techniques of handling and manipulating it in their 3-D treatments. Paper meets all material criteria in modern conservation practice, including reversibility, strength, inertness, long-term stability, minimal change in color over time, and compatibility with the original artwork. Additional attractive characteristics are that it is light weight, non-toxic, hydrophilic, it conforms well to surfaces, and is not affected by the solvents typically used. Also, the cost of paper varies but is not excessively high. Finally, having the option of using paper in sheet, fiber or powder form - either in a dry or wet state - allows for even wider applications. This article is a survey of the wide range of applications of paper in objects conservation. Its use can have two very different functions. It can serve as a restoration material, thereby remaining with the artwork after the treatment is complete, and as a tool during treatment, thereby not remaining with the artwork after the treatment is complete. [ABSTRACT FROM AUTHOR]

This study examines a two-stage two-dimensional cutting stock problem encountered by a paper mill company. The problem includes various machine-related and operational constraints based on real-world situations. Paper products are manufactured using two major cutting processes. Each cutting machine has a specific minimum and maximum width for input and output rolls and is limited by the maximum number of rolls it can cut at the same time. A mathematical model is presented to formally address the problem and an efficient multiple-choice knapsack-based heuristic algorithm is proposed to solve the problem. To demonstrate the efficiency of the proposed heuristic algorithm, computational experiments are conducted on test data-set generated from real-world data provided by a large paper mill company in the Republic of Korea. [ABSTRACT FROM PUBLISHER]

The pulp and paper sector is the fourth largest industrial sector in terms of energy use in the world. Of the numerous processes involved in paper-making by a paper machine, the dryer section is the process that consumes the largest amount of energy. A model-based method for estimating energy-saving potentials of the dryer section was put forward in the present study. It was done by four steps: establishing a mathematical model about energy consumption, determining the model parameters, benchmarking the drying performance to obtain the corresponding energy-saving measures, and estimating the energy-saving potentials by using the mathematical model. In a case study, a multi-cylinder dryer section was selected to illustrate the method. After a fundamental field test and observation, several operating problems that restricted the energy performance of paper drying were found. And then several reasonable energy-saving measures were suggested to the operators. Finally, applying the mathematic model, it was found that 0.32 ton of steam will be saved when producing 1 ton of paper in recommended operating conditions. With the designed capacity of 200,000 tons/year, the annual steam-savings will be 64,000 tons. Generally, the price of steam is 130–150 Chinese Yuan (about US$21–24) in China, and the annual economic benefits will be 8.32–9.60 million Chinese Yuan (about US$1.344–1.536 million). [ABSTRACT FROM AUTHOR]

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In this article, a mathematical model of the vacuum paper drying process was developed utilizing Fluent, a commercial Computational Fluid Dynamic software. Paper is treated as a porous medium, which is in thermodynamic equilibrium with humid air. Water distribution within paper is resolved by solving a so-called lumped diffusion equation. A developed model requires numerous experimental data and unknown/uncertain parameters. The latter ones are subjects of inverse thermal analysis. This analysis is based on the Levenberg-Marquardt method. [ABSTRACT FROM AUTHOR]

The aim of this article is to develop an experiment and a procedure to investigate the restoration of water-damaged paper and archival materials using freeze drying in order to allow a reproducible test and comparison of the influence of different operating conditions on drying time and restored paper quality. Firstly, a reproducible method for the preparation of soaked samples simulating water-damaged paper has been developed. Then, the samples have been freeze-dried in a laboratory-scale apparatus that allowed monitoring the temperature as well as the weight of the samples. The technique of evaporative freezing, which reduces the drying time required, has been used in this case. An innovative procedure for the visualization of the progress of the drying process has been validated, thus allowing the validation of a simple phenomenological model of the time evolution of the ice core volume; in addition, data on the residual moisture of the dried paper sheets in different zones have been given. Finally, optimization of this particular drying process by using simple or more sophisticated approaches has been discussed. [ABSTRACT FROM AUTHOR]

A mathematical model for through drying of paper at constant pressure drop was developed. The model is based on physical properties; hence, basis weight, pressure drop, drying air temperature, pore size distribution, initial gas fraction, and tortuosity are important input parameters to the model. The model was solved for different combinations of the variables basis weight, drying air temperature, and pressure drop corresponding to industrial conditions and the results were compared with data from bench-scale experiments. The simulations show that the drying rate curve is very sensitive to the air flow rate and that correctly modeling the correlation between pressure drop and air flow rate is the most important factor for a successful model for through drying. The model was tuned by adjusting the parameters initial gas fraction and tortuosity in order to give the best possible fit to experimental data. For a given basis weight and pressure drop, different drying air temperatures resulted in relatively constant values of the fitted parameters. This means that the model can well predict the effects of changes in drying air temperature based on a tuning of the model performed at the same basis weight and pressure drop. However, for a given basis weight, an increase in pressure drop yielded fitted parameters that were somewhat different; i.e., a lower initial gas fraction and a higher tortuosity, a change that increases the resistance to air flow. This implies that the correlation between pressure drop and air flow rate in the model does not quite capture the nonlinear relationship shown by the experiments. [ABSTRACT FROM AUTHOR]

The article discusses the result of an experimental study which shows that people do not follow the optimal strategy in practice and suggests two strategies for defeating human opponents in rock-paper-scissors (RPS). The study found that the probability of repeating a game on the next trial is well above one-third, while the strategy of always playing the symbol is assessed to be an effective strategy in defeating the symbol that the other player has previously played. The study also observed that the wins of each competition have increased by 26.4%, while the losses are decreased by 9.51%.

The research leading to the modeling framework presented in this paper was motivated by the need to provide Canadian pulp and paper producers with a means of maximizing the value created from available fibre supplies. The proposed approach involves finding optimal strategies for partitioning fibre supplies into grades, allocating fibre grades to process streams, selecting appropriate production technologies and capacities, and establishing end-product range compositions and production volumes. These strategies are elaborated with a mixed-integer programming model which can be solved using commercial optimization software. Three test case scenarios are used to validate the model and illustrate how it can be applied to strategic and tactical decision making. A variant of this model has also been applied to an industrial planning problem. [ABSTRACT FROM AUTHOR]

Part of the dewatering in a paper machine takes place via vacuum suction boxes situated below the moving web. In addition to the removal of liquid water, considerable amounts of air are sucked through the paper. The air flow that accompanies dewatering is a crucial parameter for the electricity consumption of a vacuum system. The present study models this air flow, combining differential conservation equations with fiber characterization. Measured air flow rates for different vacuum levels, basis weights, and pulp types are compared to model predictions. More than 70% of the data agree within the range of experimental error. [ABSTRACT FROM PUBLISHER]

I question whether Wachtel’s assertion that there are gaps in the relational literature and residues of a one-person psychology is little more than a reflection of the relational tradition, which encompasses a multiplicity of perspectives. This notwithstanding, his paper helpfully addresses a neglected dimension of clinical practice and provides the opportunity to explore the evolution of Stephen Mitchell’s thinking about the baby as a psychoanalytic metaphor. In doing so, I briefly, if somewhat tangentially, discuss the structure of the inner world, the role of memory in psychoanalysis, the nature of transference, and the extent to which early experiences with caregivers influence adult intimate relationships. To further illuminate Wachtel’s theoretical and therapeutic model, I summarize Mitchell’s (2000) case study of Connie, focusing on his detailed inquiry into her everyday relationship with her husband. [ABSTRACT FROM PUBLISHER]

The compression strength of a corrugated board box is a direct measure of its stacking strength. The edgewise compression strength of corrugated board is the major contributor to the box stacking strength. This relation can be further extended to the critical strength properties of paper substrates. It was, therefore, the aim of this study to establish predictive mathematical correlations between corrugated board and paper compression properties after exposure to certain climate conditions. This would allow packaging technologists in the field to select adequate paper substrates, with certain strength characteristics, to manufacture corrugated board with the necessary compression strength for achieving a desired carton performance for certain climate conditions. The results of this study were used to determine the linear regression constants in the Maltenfort model by correlating the measured board edgewise compression strength (ECT) with the predicted strength, using the paper components' compression strengths, measured with the short-span compression test (SCT) and the ring crush test (RCT) methods. The obtained predictive mathematical models were as follows: ECT = 0.6982 (SCTL1 + SCTL2 + SCTL3 + α1SCTF1 + α2SCTF2) and ECT = 1.028 (RCTL1 + RCTL2 + RCTL3 + α1RCTF1 + α2RCTF2). The obtained models showed very high coefficients of determination (R²SCT = 0.9758, R²RCT = 0.9625), which confirmed that they can be used successfully to predict the compression strength of corrugated board, using the measured paper compression strength (SCT or RCT) after exposure to constant climatic conditions. The results also indicated that the obtained plant-specific predictive mathematical models compared well to the overall linear models and that no major difference existed between the plants' capabilities to convert the paper compression strength into corrugated board edgewise crush strength. This suggested that a single set of predictive mathematical models can be utilised with a good degree of confidence in the South African corrugating industry. [ABSTRACT FROM AUTHOR]

This paper highlights the relationship between reflective practice and staff mindfulness, situation and movement awareness, and person-centredness during mobility care in nursing homes. An overview of relevant decision-making theory is followed by discussion of the place of reflective practice in optimizing mobility care. Two contrasting case scenarios, derived from observations of mobility care during a previous qualitative study, are used to illustrate and contrast how mindfulness, situation awareness and reflection-in-action may enable person-centredness. Implications for training designed to improve person-centredness during mobility care are considered. Training in situation and movement awareness, combined with observations and collaborative reflective practice, may provide a format for coaches and peer leaders to develop mindfulness and person-centredness of care staff during mobility care. [ABSTRACT FROM AUTHOR]

Introduction: Widening participation in education by including students from underrepresented groups has been recognized as important for the last decade. During the recent pandemic, the interest in how to make students from different backgrounds feel part of the university, and connected to their studies and peers, has become an even more widespread concern and therefore important to explore further. The aim of our study was to develop a conceptual model for educational design to support student engagement and participation, by exploring pedagogical aspects recognized as being valuable during widening participation initiatives. Methods: We used meta-ethnography following the recommended seven steps: getting started, developing a search strategy, reading and assessing the quality of the papers, analyzing how the different studies related to each other based on the interpretation of quotations of the informants (first order) and the researchers of the articles (second order), translating the meaning of the studies, developing a line of argument, and finally developing a conceptual model to express the synthesis. Three databases we used: PubMed, ERIC, and Scopus; the PRISMA workflow was used. Results: Six articles with a qualitative approach were included. A conceptual model was developed with the theme 'Scaffolding Strategies' and four sub-themes: Academic Support, Social Interaction, Processing Expectations and Clarifying Learning Progress. Conclusion: We developed a conceptual model from previous studies that entailed aspects of particular importance to support widening participation. By using scaffolding strategies in course design, teachers and students may collectively improve the learning environment to promote widening participation, through clear instructions and frequent interaction, communication and calibration of expectations, clarification of learning processes and progress, and support for academic-skills development. Furthermore, the importance of using academic support and social interaction between students and teachers early on, to encourage students to explore how to become an independent learner, is highlighted. [ABSTRACT FROM AUTHOR]

Harmful Sexual Behaviour (HSB) has been regularly documented as a demanding area of practice within the United Kingdom (UK). The aim of this paper is to share a practice model developed in an under-resourced inner London borough. The HSB forum is formed of a multi-agency group of professionals and runs monthly providing a platform for practitioners to seek consultation for young people they are working with who are displaying HSB's. Initial feedback for the forum from practitioners has been consistently positive and they have valued specifically the opportunity to formulate, have clear directions, and the multi-disciplinary perspective. In addition, most reported feeling empowered to implement the recommendations suggested. Given the shared vulnerability factors between those displaying HSB's and other at-risk young people such as those who are being sexually exploited, this model provides an innovative way that practitioners can be supported by multiple agencies where there is a lack of specialist services. [ABSTRACT FROM AUTHOR]

In taking up the matter of intersubjectivity in Kleinian-Bionian theories Brown creatively reimagines the clinical situation, transcending demarcations of analytic schools to arrive (though never fully arrive) at new understandings of interaction. I discuss Brown's engaging paper from my own emerging concept of enactivity, drawing distinctions between this approach and Bion's approach and extending the enactive to a consideration of enactive fields that, like Brown's paper, draws on the seminal reinterpretation of Kleinian theory by the Barangers. In writing of the field as an emergent process of becoming I rely on Merleau-Ponty's notion of 'singing the world' to illustrate my developing understanding of the possibilities for interaction in the Kleinian-Bionian tradition. My comments on Brown's clinical case material focus on what appears to me to be the intersubjective aspects of his approach. [ABSTRACT FROM AUTHOR]

Final dewatering in the production of dry creped tissue is performed by Yankee drying, which includes hot pressing followed by simultaneous contact and impingement drying. The present study models Yankee drying and compares simulation results to the data obtained from trials on a pilot tissue machine. It advances models published previously by the representations developed for the transport of heat in the pressing stage and for the heat transfer involved in the dehydration of the cylinder coating spray. The model predicts an average specific drying rate within 4% in the range of the experimental data used. [ABSTRACT FROM PUBLISHER]

This review paper provides the operations management (OM) community with an exhaustive analysis of the mathematical models developed for the problem of low-carbon supply chain management (LCSCM). Our paper belongs to the green supply chain management (GSCM) reviews but is distinguished by its specific interest in analysing research works on supply chain (SC) management regarding the reduction of carbon emissions and its related constraints. To facilitate our benchmarking of the 83 selected papers, we adopt a literature classification based on the logistic decisions studied within the developed models. We distinguish three categories of logistic decisions: operational management, technology investment and SC design coordination. Companies are currently facing great external pressures from governments and their conscientious customers to reduce their overall emissions. We analyse how these environmental constraints, which we believe are key drivers for low-carbon emissions management, have been incorporated into mathematical models. Analysing these external pressures in terms of concern about carbon emissions constitutes our main contribution through this literature review. In addition, companies are facing a challenge to reduce their carbon emissions, which are mainly generated from production, transport and storage activities. Consequently, the modelling of carbon emissions remains a crucial task when addressing the LCSCM problem. We suggest analysing the techniques used thus far to approximate those carbon emissions. Furthermore, to illustrate our literature classification and the features of the LCSCM problem, we provide the framework on which we based our analysis of the selected literature. We discuss the modelling aspects of this problem to highlight the limits of the existing literature and consequently suggest recommendations for future research. We believe that this issue will continue to be one of the top concerns of the OM community within the GSCM field as it continues to gain importance among business leaders, and political and social actors. [ABSTRACT FROM AUTHOR]

To achieve socio-economic and environmental sustainability, utilization of existing capacities and assets has become a key challenge for the transportation sector. This challenge has been recognised by many scholars, policy makers and practitioners leading to a substantial body of new concepts and models. The rather parallel evolution of the Physical Internet (PI) and synchromodal transport presents an opportunity to improve the current unsustainable freight transportation, by inducing a positive modal shift from roads to rails and inland waterways, and improving service levels by better connecting production research with freight movement. This paper thus examines the synchromodal and PI state-of-the-art models together with their designs, methodologies and findings proposed in the scientific literature. The main objective is to assess and explore the correlations between these two concepts in order to understand how they can reinforce each other. Despite the integrated vision of the Alliance for Logistics Innovation through Collaboration in Europe, the findings of this paper yield no well-established interconnections in the scientific literature between PI and synchromodality as they both merely coexist in parallel and address different dimensions, scales and levels of abstraction. This paper thus identifies potential synergies, future research directions and critical questions to be considered by modellers, developers and policy makers. [ABSTRACT FROM AUTHOR]

On the other hand, optimization techniques generally do not employ methods of inverse design, although they could potentially reduce the number of time-consuming analysis required by the typical evolutionary optimization algorithms. B ECCOMAS 2022: 8th European Congress on Computational Methods in Applied Sciences and Engineering b B June 5-9, 2022, Oslo, Norway b http://www.eccomas2022.org/frontal/default.asp B Track Number 4000 - Minisymposium 18 b B INVERSE PROBLEMS, DESIGN & OPTIMIZATION IN HEAT TRANSFER b B Organizers: Helcio R. B. Orlande, George S. Dulikravich, Marcelo J. Colaço and Zbigniew Bulinski b ABSTRACT Inverse problems, design theories and multi-objective constrained optimization strategies are three areas of advanced research of great interest for practicing engineers and designers. Similarly, design theory is commonly not used by the optimization community, where formulation of the appropriate multiple objectives and system-of-systems design formulations are often performed using intuition and personal experience. [Extracted from the article]

In this paper, we demonstrate that the relation between two jobs defined by min{ai, bj} ≤ min{bi, aj}, used in Johnson’s theorem, is not transitive. However, both the theorem and Johnson’s algorithm are correct. [ABSTRACT FROM AUTHOR]

A mathematical model modified from the well established Activated Sludge Model no. 1 was used for modelling a full-scale wastewater treatment plant (WWTP) in a bleached kraft pulp mill. Effluents from the pulp and paper industry are typically nutrient deficient, which was considered in the model. The wastewater characterization and model calibration were based on respirometric batch experiments with sludge and wastewater sampled from the WWTP. The model performance was validated in a long-term simulation using routinely measured process data from the WWTP as the model inputs. The simulation results proved useful in evaluating nutrient dosage strategies at the WWTP and in troubleshooting poor treatment plant performance. However, in order to achieve a completely accurate description of nitrogen removal, more complex phenomena would have to be included in the model. Even though the simulated period was long compared to the brief measurement campaign used in the model calibration, the model was able to describe the treatment plant's behaviour. The calibrated model can be expected to stay valid for a long time, which allows the use of deterministic modelling in practical applications at pulp and paper WWTPs. [ABSTRACT FROM AUTHOR]

The article discusses the major differences in articles which investigated the application of wavelet networks in traffic volume forecasting. First is the focus of research on the use of wavelet networks for the prediction of short-term traffic flow data. Second, the wavelet networks are different. Third, the performance of wavelet networks is compared with the performance of popular neural network models.

Due to today's competitive environment and information boom, companies are concerned about production planning in uncertain conditions. This paper integrates decision-making method with production scheduling model by considering limited resources. In this paper, a new mathematical model is extended for production project scheduling with multiple execution modes. The main aim of the formulation is to plan and schedule real production projects in uncertain environments. A new mixed-integer linear formulation is presented by considering trade-off of cost, time, as well as quality. Cost–time-quality trade-off is extended with the interval information. In the presented model, activity quality could be enhanced by reworking. The interval forms of some parameters, including duration, quality of activities, cost, and total available resources, are obtained by determining weights of experts and aggregating them. The presented group decision-making method is based on a bi-directional projection measure to deal with interval information. Since the mathematical model is multi-objective and some data are interval, a new modified solution method is developed for solving the model. The presented method for both decision-making and mathematical models is investigated by a real-world production project and two datasets to ascertain the accuracy of the model. Finally, an appropriate sensitivity analysis is proposed. [ABSTRACT FROM AUTHOR]

A grey-box modelling incorporating mechanism and data is presented in this paper to predict the ship manoeuvering motion. The traditional mathematical model in three degrees of freedom is adopted to reveal the known movement mechanism, in which an additional hydrodynamic correction term is developed by Neural Network (NN) based on the data to adaptively estimate the errors induced by the idealised approximation. The KRISO Container Ship (KCS) is taken as the study object and the free-running model tests are carried out to obtain the data for establishing the NN model of hydrodynamic correction terms. The typical manoeuvers (tactical circles, zigzags, Williamson turns) are simulated by the grey-box model and the mathematical model, respectively. The results indicate that the grey-box modelling method proposed in this paper can not only improve the prediction accuracy but also demonstrate a good generalisation performance. [ABSTRACT FROM AUTHOR]

Kraft pulp, the raw material in paper manufacturing, is obtained by exposing pieces of wood to a cooking process. The parameters of this process (temperatures, times, chemicals, etc.) depend strongly on the density of the different woods in the cooker and have an influence on the quality of the pulp that is obtained. In order to optimize both the production process and the pulp quality, one wishes to cook together woods having similar densities. However, given that the harvest areas contain limited quantities of trees and that wood densities vary significantly from one area to another, deciding how harvested wood from different areas should be mixed for processing is a significant operational decision in pulp production planning. This situation is modelled as a scheduling problem where one has to decide which harvested area goes to each available processing units in order to minimize the variance of wood densities within each cooker for each period of the planning horizon. We also present an approximated solution approach based on the formulation proposed. Some results are reported and the efficiency of the method is discussed. [ABSTRACT FROM AUTHOR]

This study presents an integrated approach to assess energy performance during hood retrofitting from a semi-closed hood to a closed hood. According to the principle of heat and mass transfer, a simulation program was established by a mathematical model and some necessary model parameters. It could be used to simulate the paper-drying process and calculate steam and power consumption during paper drying. The method was applied to a corrugated paper machine. After a fundamental field test and observation, the simulation program determined appropriate model parameters. Finally, we found a 13.2% steam consumption reduction and a 13.5% total energy consumption reduction. [ABSTRACT FROM PUBLISHER]

To increase the efficiency of photovoltaic (PV) systems, maximum power point (MPP) tracking of the solar arrays is needed. Under partially shaded conditions (PSCs), the solar arrays power–current (P–I) characteristic has multiple MPP. This paper presents various methods and approaches of tracking the MPP from a PV generator operating under PSC. Some comparisons, advantages, drawbacks and critical analysis of each method are discussed. It was found that, indirect methods use empirical data or mathematical expressions of numerical approximations to estimate the MPP from the PV generator’s voltage, current and irradiance. Direct methods offer the advantage of obtaining the actual maximum power from the PV generator’s voltage and current. Artificial intelligence methods do not need exact mathematical models. They can perform under parameter variation, load and supply voltage disturbances. Finally, novel methods require less number of iterations to converge, independent to the initial conditions. All these algorithms can be included in some of the DC/DC converters and MPP trackers for stand-alone or grid-connected systems. [ABSTRACT FROM AUTHOR]

People born with disabilities (PWDs) face many problems because of their inability to accomplish simple daily tasks. However, the evolution of technological solutions has helped the PWDs to accomplish their tasks independently. Although a significant amount of the research work can be found on these technologies still, the authors believe that there is a lack of a rational method to quantitatively assess the solutions for their applicability to the respective impairment. In this paper, a quantitative and a qualitative assessment approach for the evaluation of the various technologies is proposed. It measures the applicability of the technological solutions for the different impairment groups. Based on the scoring model known as the multi-weighted scoring model (MWSM), the proposed evaluation approach carries out comparative judgment of clinical experts and input from PWD's using a well-defined criteria. The technique is applied to 16 research papers which are dealing with the application of technologies that assist PWDs suffering from various impairment conditions. The assessment technique has successfully identified the relevant criteria that can be used to assess technological research papers. It has also identified the research gaps which require further attention. The proposed quantitative approach can be a very useful tool to assess the applicability and the quality of the previous relevant works. [ABSTRACT FROM AUTHOR]

In the article 'How long is my toilet roll-a simple exercise in mathematical modelling' several models of increasing complexity are introduced and solved to calculate indirectly the length of paper on a toilet-roll. All these results are presented without errors. The authors of this comment believe the error analysis of measurements made in a laboratory is an important part of the experiment. The calculation of the absolute errors in indirect measurements provides us with information about the confidence that we must have in our experimental results. For that reason, the error calculation for all approximations has been made. [ABSTRACT FROM AUTHOR]

It is well-known that the Lotka–Volterra predator-prey model has a family of periodic orbits, but does not possess limit cycles and therefore the model is said to be structurally unstable. The Lotka–Volterra model is a special case of a much larger group namely the quadratic population models and it can be shown that none of them can produce limit cycles. The surprising finding is that by combining two quadratic models a quadratic population model with two limit cycles is uncovered. Although the model looks simple at first glance it provides a rich source of dynamics and deserves attention. In this paper, we revisit a model that has its origin in the work of Dubois and Closset. A set of two quadratic population models interact as piecewise defined differential equations. The model has been discussed by Ren Yongtai and Han Li, cryptically written and showing some linguistic and typographical errors, but providing an excellent vehicle for developing skills in mathematical modelling, differential equations and technology for the young researcher. We explore the model in clearer detail and supplement the theory with rich graphical illustration. The paper has the purpose of providing an example of how a young researcher, such as a postgraduate student in biomathematics, can expand on an existing model by making use of current technology. [ABSTRACT FROM AUTHOR]

Presents an overview of the panel papers on cybernetics and systems research presented at a session on Cultural Systems in Europe. Mathematical approaches applied to central problems addressed by cultural anthropologists; Awards and achievements of the panel papers; Discussion on mathematical methodology in the published work.

Harmful sexual behaviour that occurs between siblings (HSB-S) is thought to be one of the most common forms of intrafamilial abuse. Despite an increase in academic papers, and acknowledgement of the prevalence of the problem, there is still a lack of specific assessment and intervention models. The aim of this paper is to provide an overview on the Assessment, Intervention and Moving On (AIM) HSB-S Practice Guidance. The framework draws on the literature and evidence-based models, as well as clinical practice illustrated by the four-case series summarised. Of the four-case series illustrated in the paper positive outcomes were observed. In addition, the intervention includes the practitioner guiding the family to write a structured narrative which supports them to restore family relationships and find a way of moving forward. This guidance will strengthen practitioner's skills and confidence in working with families impacted by HSB-S and provide hope for them that they can heal from this crisis. This paper provides a preview for the AIM HSB-S Practice Guidance illustrated by a case series. The framework will provide practitioners with a clear approach to assessment and intervention when working with families impacted by HSB-S. [ABSTRACT FROM AUTHOR]

Motivated by a practical problem, this paper investigates the integrated planning of maintenance operations and workload allocation on a set of machines in a workshop. Given quantities of products to be produced per period on a planning horizon must be processed on unrelated flexible machines. Moreover, each machine has to undergo one or more maintenance operations that must be planned within a given time window and impact products differently. The main goal is to find a feasible plan that satisfies the machine capacity by allocating the production quantities to machines and assigning maintenance operations as late as possible in their time windows. Various original mathematical models are presented. In particular, we propose models that allow maintenance operations and some production quantities to overlap two consecutive periods. Computational experiments based on industrial data show that allowing this overlapping helps the earliness of maintenance operations to be significantly reduced in the most difficult instances, going for example from a total of 14 periods to only 1 period, and by more than 35% on average. [ABSTRACT FROM AUTHOR]

The paper presents a historical overview of the development of hydrological models in the former USSR and Russia since the 1930s. An overwhelming number of hydrological papers were published in Russian, and they are not sufficiently well known to the world hydrological community. The purpose of the review is to fill the gap and present the main achievements, some of which were pioneering for their time. The period under consideration is divided into three sub-periods. Pre-computer, the 1930–1950s were associated, first of all, with the development of models of unsteady water flow in river channels and linear flood-routing models; in the 1960–1980s, many theoretical and practical foundations for modelling the processes of the hydrological cycle and the formation of river runoff were developed; and in the Russian era, following 1991, several notable advancements in the considered field were also made. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to contribute to the development of a theoretical model that is useful for enhancing well-being/positive mental health with pedagogical resources that enable the acquisition of skills and knowledge, particularly during Emerging Adulthood. Methods: This paper enquires into the role of well-being promotion in higher education following the dual-factor model of mental health difficulties and wellbeing. The study narratively reviews the main well-being models and presents a compared theoretical synthesis examining the dimensions that promote or facilitate the presence of well-being using a promotion approach. Results: The study identifies 14 dimensions involved in wellbeing—emotional, psychological and social factors—that can be potentially improved through learning processes. Drawing on empirical and theoretical studies on emerging adult population, a factorial model is proposed. Preliminary factor interactions are examined paying close attention to the cognitive processes that explain or affect their relationship with well-being, the possible correlations between them and particularities of emerging adults. Conclusion: Wellbeing factors can be particularly targeted by educational promotion, as they can be developed through learning processes. An integrative model that provides a broad perspective can assist in pedagogical design and defining educational goals for these learning processes involved in wellbeing promotion. [ABSTRACT FROM AUTHOR]

The affective experience generated when users play computer games can influence their attitude and preference towards the game. Existing evaluation means mainly depend on subjective scales and physiological signals. However, some limitations should not be ignored (e.g. subjective scales are not objective, and physiological signals are complicated). In this paper, we 1) propose a novel method to assess user affective experience when playing single-player games based on pleasure-arousal-dominance (PAD) emotions, facial expressions, and gaze directions, and 2) build an artificial intelligence model to identify user preference. Fifty-four subjects participated in a basketball experiment with three difficulty levels. Their expressions, gaze directions, and subjective PAD emotions were collected and analysed. Experimental results showed that the expression intensities of angry, sad, and neutral, yaw angle degrees of gaze direction, and PAD emotions varied significantly under different difficulties. Besides, the proposed model achieved better performance than other machine-learning algorithms on the collected dataset. PRACTITIONER SUMMARY: This paper considers the limitations of existing methods for assessing user affective experience when playing computer games. It demonstrates a novel approach using subjective emotion and objective facial cues to identify user affective experience and user preference for the game. [ABSTRACT FROM AUTHOR]

People participate in many different types of physical activity, both daily and across their life span, but research on human movement is often siloed by type (sport, exercise, active transportation, etc.). Models developed for understanding participation in specific types of physical activity remain useful in those contexts, but are insufficient for describing, explaining, or enhancing movement at the individual or societal level. Physical literacy has the potential to serve this purpose, but its current application does not fulfill its potential for holistic and inclusive promotion of movement. This paper therefore introduces a new framework for physical literacy, Four Domains for Development for All (4D4D4All). This framework highlights the interrelations among the physical, psychological, social, and creative aspects of movement, and emphasizes how development across all four domains can be supported through the interrelations of individuals and their contexts. In this paper, we introduce the 4D4D4All framework and present ideas for its application in research and practice. Specifically, this individualized, holistic, and inclusive approach to physical literacy is an alternative to models that emphasize the production of podium-driven athletes or focus on meeting physical activity guidelines, and is therefore better suited to facilitate the development of flourishing active people. Lay summary: Current models of sport and physical activity participation do not adequately describe the developmental experiences of individuals moving in a variety of contexts. Our new physical literacy framework, Four Domains for Development for All (4D4D4All), enables all movement contexts to better support well-being through a focus on holistic individual development. IMPLICATIONS FOR PRACTICE: Practitioners in sport and physical activity settings should view their participants as whole people who engage in many types of active pursuits, both concurrently and across their life spans. Experiences in movement contexts, including sport, should be intentionally designed to support development of physical literacy in ways that promote development across the physical, psychological, social, and creative domains. Sport policy and physical activity promotion efforts should be based on holistic frameworks, like 4D4D4All, that recognize multiple pathways of participation and promote flourishing for all people, rather than focusing on international competitive success or standardized health metrics. [ABSTRACT FROM AUTHOR]

This paper proposes a new bi-objective aircraft and crew recovery model. Unlike previous researches, the proposed model considers all individual flight legs in the recovery process. The objective functions minimize the recovery cost regarding crew swapping, flight cancellation, flight delay, and crew deadhead costs. Besides, the crew sit time is reduced considering the maximum legal working hours and the minimum essential rest time. Moreover, maintenance operations can be done during the ground time, not necessarily at the end of duty day. The model is never infeasible because flight cancelation is an alternative solution for recovering a schedule. A modified Tabu Search (TS) approach has been developed to solve the model. The performance of the model and solution approach is examined by several test problems in small, medium, and large scales. The results indicate that TS reaches optimal and close-optimal in a short computational time, especially in large scale problems. [ABSTRACT FROM AUTHOR]

Based on the stress coping theory, the present paper aims to investigate the influence of users' networking ability and profile control ability in mitigating the negativity of social media overload. This paper argues that in the social media context, instead of discontinuance, users tend to develop comprehensive strategies and practices to manage their social media usage. Via an exploratory factor analysis (EFA) study, five practices were identified, including continuous usage, reduced usage, setting adjustment, support seeking, and information avoidance. The results show that social media overload leads to both the perception of emotional exhaustion and disturbance handling while networking and profile control ability make users focus on disturbance handling. Besides, networking ability is found to weaken the relationship between social media overload and emotional exhaustion while profile control ability exaggerates that relationship. Finally, emotional exhaustion and disturbance handling both predict users' different social media management practices. [ABSTRACT FROM AUTHOR]

This paper is written as a guide for any instructor seeking to develop the mathematical modeling process or open-ended problem solving in their courses. We describe a pedagogical approach to create mini modeling problems to develop the modeling process. These are problems that fall between traditional homework problems and open-ended modeling problems, and focus on specific aspects of the modeling process. Implementing such mini modeling problems is a means of scaffolding the modeling process to engage the students in smaller stages of modeling and prepare them for the full modeling process. This is intended as a means to empower the students so they can engage confidently in the modeling process. [ABSTRACT FROM AUTHOR]

This paper proposes new algorithms for the assembly line balancing problem with hierarchical worker assignment (ALBHW). The ALBHW appears in real industrial contexts, where companies deal with a multi-skilled workforce. It considers task execution times that vary depending on the worker type to whom the task is assigned. Qualification levels among workers are ranked hierarchically, where a lower qualified worker costs less but requires larger execution times then a higher qualified one. The aim is to assign workers and tasks to the stations of an assembly line, in such a way that cycle time and precedence constraints are satisfied, and the total cost is minimised. In this paper, we first present a mathematical model and improve it with preprocessing techniques. Then, we propose a constructive heuristic and a variable neighbourhood descent that are useful to solve large instances. Extensive computational experiments on benchmark instances prove the effectiveness of the algorithms. [ABSTRACT FROM AUTHOR]

The selective maintenance problem (SMP) arises in many mission-oriented multi-component systems that are operated for consecutive missions interspersed with finite breaks, during which only limited component repairs can be performed due to constrained resources. This NP-hard problem decides which components to maintain and to what levels of repair to guarantee a pre-specified performance level during the subsequent mission. Over the last two decades, a sizeable body of literature has been published on this topic. However, the contributions have stagnated in quality, and most articles deal with small to moderate problems. This paper provides a critical review of the SMP literature. A total of 136 research articles related to SMP are reviewed and a selection of key representative models is discussed in detail. This review is framed according to two feature categories: formulation characteristics, composed of three sub-groups of characteristics related to the system, maintenance and mathematical model characteristics; and solution approaches, grouped by exact methods and approximate algorithms. This critical review is aimed at identifying drawbacks, shortcomings, and blind spots of the SMP literature, and providing a roadmap for the challenges to be addressed and innovative future research topics to further advance the academic and industrial contributions of SMP. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has caused critical challenges for e-commerce warehouses that strive to fulfill surging customer demand while facing a high virus infection risk. Current literature on picking optimization overlooks warehouse safety under pandemic conditions. Meanwhile, scattered storage and zone-wave-batch picking have been used in parallel by many large e-commerce warehouses, these two operational policies have not been considered together in picking optimization studies. This paper fills these gaps by solving an order batching problem considering scattered storage, zone-wave-batch picking, and pickers' proximity simultaneously. We formulate and solve the mathematical model of the discussed problem and propose the Aisle-Based Constructive Batching Algorithm (ABCBA) to help warehouses pick more efficiently and safely. Experiments with extensive datasets from a major third-party logistics (3PL) company show that, compared to the current picking strategy, ABCBA can reduce the total picking time and the virus infection risk due to pickers' proximity by 46% and 72%, respectively. Compared to other heuristics like tabu + nLSA3 (Yang, Zhao, and Guo 2020), ABCBA gets better results using less computation time. [ABSTRACT FROM AUTHOR]

Laser welding has been widely employed for aluminum alloy body-in-white. However, owing to the low utilisation efficiency of energy and material, the carbon emission of laser welding is serious. In this paper, the mathematical modelling of carbon emissions and process parameters optimisation for laser welding cells are studied. The carbon emission characteristics of the laser welding system are analysed, and the carbon emission model of the laser welding cell considering both welding features and welding transfers is established. Besides, the process parameters optimisation model of laser welding cell is developed. To obtain optimal welding sequence, a combinatorial algorithm based on Culture Algorithm and Ant Colony Algorithm is proposed. Based on the optimal welding sequence, the optimal transfer speed is obtained through mathematical theory. Furthermore, a case study is performed to verify the feasibility and reliability of the process parameters optimisation model. Additionally, compared with the Ant Colony Algorithm, the proposed solution algorithm has better comprehensive performance in terms of convergence speed and optimisation accuracy. This study lays a theoretical foundation for carbon emission modelling of the laser welding cell, and can support the automobile enterprise to make processing parameters selection of the laser welding line in the design stage. [ABSTRACT FROM AUTHOR]

Despite various supervised methods and algorithms, prediction methods do not necessarily provide the optimal values of the outputs. In this paper, an approach is proposed based on the integration of the clustering algorithm and a new mathematical programming model for predicting the efficient and optimal level of hospital outputs. In the first stage, units are evaluated using data envelopment analysis (DEA) and then, high-efficiency units are selected. In the second stage, the selected units are clustered based on the inputs of the units using the fuzzy C-means algorithm. For each unit to be estimated, the corresponding cluster is found and the closest unit to the target unit is determined. Finally, using the proposed new mathematical programming model, the optimal values are estimated based on the more efficient unit. A case study on Iranian hospitals illustrates the implementation of algorithms and methods and shows the abilities of the proposed approach. [ABSTRACT FROM AUTHOR]

Groupwork is a core method of social work intervention, yet in our experience, social work students and early graduates rarely embrace the idea of facilitating groups, nor foresee that as a role they would like to fill. Through our years of experience in practising and teaching groupwork, we have learned that one of the reasons for this reluctance is the fear of conflict. This paper focuses on our journey of understanding the role of conflict in groups viewed through the lens of Tuckman's 5 stages of groupwork. Through a series of examples from practice, we provide readers with strategies we have used for managing conflict in a groupwork practice setting. The aim of this paper is to provide social work educators, students and graduates with an understanding of why conflict occurs in groups and to provide a toolbox of strategies to respond to conflict. [ABSTRACT FROM AUTHOR]