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We present a mathematical model for the slow combustion (smoldering) of a two-dimensional sheet of paper. We describe the evolution of the char region, and we investigate the effects of an orthogonal air flow on the shape of the combustion front. The mathematical formulation consists in a set of two nonlinear PDEs for the temperature and the oxygen concentrations coupled with one ODE for the cellulose concentration. The (dimensionless) problem is solved numerically by means of a spectral collocation scheme based on Chebyshev polynomials. Our results show that the Péclet and the Lewis number strongly influence the shape of the ignition front and that the advancement of the combustion front does not occur if advection and diffusion are neglected (zero Péclet and Lewis numbers). In particular we observe that the burning region and the ignition front are strongly influenced by the velocity of the airflow and by the mass and heat transport phenomena due to diffusion and advection. We shall see that the increasing of the ratio between the convective and diffusive characteristic times (Péclet number) and the decreasing of the ratio between the mass and heat diffusive characteristic times (Lewis number) have a "flattening effect" on the combustion front. [ABSTRACT FROM AUTHOR]

In this article, we present a mathematical model and numerical simulation of the coffee-ring effect on porous papers. The numerical method is based on Monte Carlo simulation. The proposed model is simple but can capture the main mechanism of coffee stain formation on porous papers. Several numerical experiments are presented to demonstrate the performance of the proposed algorithm. We can obtain the coffee-ring effect on porous papers as the computer simulation results. [ABSTRACT FROM AUTHOR]

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]

Mathematical modelling is a powerful tool in science. Causal mathematical models based on a clear picture of how key variables interact enable a deeper understanding of a given situation and provide reliable predictions. This is a classic approach in science. Unfortunately, this approach is declining in pulp and paper-related research in favour of simply reporting experimental data. The lack of a framework provided by a model diminishes the value of much experimental work. Therefore, the increased use of mathematical models is encouraged, and this approach is illustrated via several practical examples from our work. [ABSTRACT FROM AUTHOR]

To enhance the quality and efficiency of computer-enabled generation of papers for Test for English Majors Band 8 (TEM-8), a paper generation model supported by sparrow search algorithm-genetic algorithm was studied. First, a simplified test paper generation mathematical model was set up after analyzing and studying types and characteristics of TEM-8 tasks. In the model, quantity, type, difficulty, discrimination degree, scores, exposure, and answering time of test questions were taken into consideration. To enhance the optimizing effect of the genetic algorithm for searching test questions, the traditional genetic algorithm was improved by introducing the sparrow search algorithm into the model to achieve a better crossover rate, variance rate, optimization precision, and speed of the genetic algorithm. A new sparrow search-genetic algorithm (SSA-GA) was designed, and the optimizing effect of SSA-GA was verified to be ideal through optimizing six standard test functions. Then, SSA-GA was applied to conduct experimentation with test paper generation, and comparison with traditional genetic algorithms was also made. The values of best and average fitness of SSA-GA were better than those of the traditional genetic algorithm (GA) in the paper generation. Exposure rate and success rate in TEM-8 paper generation of SSA-GA were higher than those of traditional GA in TEM-8 paper generation. Results showed that the studied SSA-GA could implement test paper generation with higher speed and better quality. [ABSTRACT FROM AUTHOR]

Howard Rachlin's widely influential behavioral economic approach to self‐control and related issues provides the model for this submission. The topic is overconsumption. Current human consumption levels are unsustainable. Explanations typically focus on societal factors, such as the seductive power of advertising and/or misguided tax policies. However, the effectiveness of these factors depends on the degree to which individuals are susceptible to the message: "consume more." Humans are not blank slates. This paper argues that how individuals frame their choices establishes the susceptibility to overconsume. According to economic theory, consumers frame their options as bundles, composed of different combinations of the available items and activities. This leads to maximizing. In experiments, participants tend to frame their options as "either‐or" choices. This leads to the matching law. Mathematical models of concurrent schedule choice procedures show that (1) the matching law implies overconsumption of the most preferred option and (2) that individuals will persist in preferring their favorite option even when doing so reduces overall reward rates. Given that the matching law better describes how individuals choose than does maximizing, the mathematical models of widely used choice procedures help explain why efforts to increase consumption have been more influential than efforts to control consumption. [ABSTRACT FROM AUTHOR]

Abstract: The flows of paper are analyzed throughout the papermaking processes, with the year 2007 and Korea defined as the system boundaries. In practice, the statistical data on the production, import and export of paper or pulp can be collected with relative ease from the government and industrial associations. However, the input data regarding the volumes of pulp and wastepaper used in different paper products, such as newsprint, printing papers, sanitary and household papers, specialty papers, and corrugating board base, are difficult to obtain because such information is generally kept confidential in the course of corporate operations. The production processes of paper products in Korea are modeled using information on raw materials, their compositions and production yields of products in order to identify and quantify the amounts of pulp and wastepaper used in each paper product. The material flows of paper are then analyzed based on the calculation model derived from the correlation of input and output flows between the individual processes throughout the entire paper lifecycle. Accuracy analysis using both mean absolute error (MAE) and mean absolute percent error (MAPE) is conducted to verify the amounts of pulp and wastepaper calculated from the proposed model against the volumes of domestically consumed pulp and wastepaper provided in the national statistics. Although the calculated values for the past (i.e., the 1980s and 1990s) differ to some degree from the statistical values, the data for the 2000s have a relatively higher level of accuracy, with the MAPE of the total pulp and recycling volume at 5.39% and 5.30%, respectively, thus validating the adequacy of the proposed modeling method. The proposed calculation model can be effectively used in the material flow analysis (MFA) of paper to reduce the burden of data collection and obtain relatively accurate results. [Copyright &y& Elsevier]

Due to rapid temperature rise and insulation moisture, bubbles can generate in the oil-paper insulation of oil-immersed power transformers, which can reduce the dielectric strength of oil-paper insulation and even bring about the risk of insulation breakdown. In order to accurately evaluate the conditions of bubble formation, the physical process of bubble formation in oil-paper insulation is studied in this article. Considering the effects of water vaporization, gas dissolution in oil, and moisture migration on bubble formation, a bubble formation prediction model is constructed. Based on Henry’s law, the dissolution equilibrium of gas in oil is taken into consideration and the upper boundary of the initial temperature of bubble effect (ITBE) envelope is obtained in this model. Based on the moisture equilibrium in oil-paper insulation, the bubble formation process caused by the emergence and rapid evaporation of free water is analyzed, and then, the lower boundary of the ITBE envelope is obtained in this model. The model results show that the moisture content of the pressboard and the presence of free water have a great impact on ITBE. Specifically, the higher the moisture content, the lower the ITBE value. In addition, with the further increase of moisture content, the upper and lower boundaries of the ITBE envelope gradually tend to be the same. However, once free water is present on the surface of cellulose, ITBE decreases rapidly to below 120 °C. The model built in this article is of great significance to study the temperature limit of the power transformer. Hence the ITBE envelope can provide an important theoretical reference for reducing the risk of bubble formation during power transformer operation. [ABSTRACT FROM AUTHOR]

• Combined effects of extruded brick compositions with paper sludge and expanded perlite were characterized. • The use of additives in bricks has significantly affected their thermo-physical and mechanical properties. • The effects of process parameters on brick properties were investigated with a new mathematical modeling approach. • Fired brick samples showed good thermal insulation performance. • Produced exruded bricks have good potential for energy saving. Lightweight bricks produced with addition of different additive materials such as expanded perlite (EP) and recycling paper sludge (RPS) waste have been accomplished by a pug mill. Porous fired bricks were produced by using organic and inorganic additives such as paper waste and expanded perlite as pore-makers. In the experimental study, the seventeen mixture sets were prepared with Box-Behnken experimental design procedure of two additive ratios and firing temperatures. The brick samples were produced with shaping by extrusion method and firing at 850, 950 and 1050 °C for two hours after drying. Physical characteristics such as bulk density, apparent porosity and water absorption, and also, compressive strength, thermal conductivity and microstructural properties of brick samples were studied. Influences of process parameters on brick properties were investigated with a detailed neuro-regression analysis. In conclusion, the best brick composition (10 % EP + 10 %RPS by weight) in terms of thermal conductivity corresponding to acceptable mechanical properties was optimized. Accordingly, the compressive strength values of all samples are around 10 to 27 MPa. Also, the samples with high additive content (especially 10 %RPS + 5 %EP sample) exhibited the lowest thermal conductivity value (0.432 W/mK) due to the low firing temperature. [ABSTRACT FROM AUTHOR]

This paper is aimed at developing a systematic methodology for the cost-effective reduction of water usage and discharge in pulp and paper plants. As the industry moves towards increased system closure, the build-up of Non-Process Elements (NPEs) leads to serious consequences on the process equipment. In response, this paper achieves the following: • a mathematical model to track water and primary NPEs throughout the pulping process • rigorous targeting for water usage and discharge • a systematic framework for water reduction using mass integration strategies including no/low cost techniques as well as capital-based techniques • an optimisation model for the optimisation of allocation, recycle and separation of aqueous streams. A case study for water management in a kraft pulping process has been solved to highlight the usefulness of the devsied approach. [ABSTRACT FROM AUTHOR]

The aim of this paper is the development of a mathematical model to compute the optimal inventory mix to face stochastic demand at minimum cost in a two-level supply chain. The paper addresses a multi-product dynamic lot-sizing problem under stochastic demand subject to capacity and service level constraints. This model is executed to compare a Make To Order (MTO) strategy to a Vendor Managed Inventory (VMI) partnership between the supplier and their customers. Both strategies provide the demand order to be produced. A schedule of production orders is determined over the planning horizon in order to minimize the inventory holding costs of the supply chain, taking into consideration that the supplier is also responsible of initiating the replenishment orders and deliveries of their customers according to the VMI partnership. The simulation model is illustrated empirically using a real case study: a paper manufacturing company that pursues to improve customer service level and supply chain inventory costs through a proper production planning of their paper machines and a suitable VMI order replenishment schedule. [ABSTRACT FROM AUTHOR]

The article presents a conceptual framework using simulation to predict effluent biochemical oxygen demand (BOD) characteristics as a function of improved wastewater treatment. These simulations use equations that describe BOD kinetics. They also able to reproduce trends in f-ratio observed at various pulp and paper facilities and predict BOD reactivity as a function of treatment.

Within our research work we determined the Young's modulus distribution in the paper plane on the basis of results of tensile tests in selected directions. Using mathematical relationships valid for orthotropic materials, the moduli were calculated theoretically. The tensile stiffness orientation angle (TSA), and the TSO and TSI indices were also determined in order to define the deviations of the main axes of orthotrophy in the paper plane as determined by the machine and the cross directions. The calculation results were compared with measured values. They justified the conclusion that paper may be treated as an orthotropic material. [ABSTRACT FROM AUTHOR]

The generation and distribution of furfural are significantly affected by moisture content in the insulating paper. However, the diffusion mechanism of furfural under moisture effect is not clear, hence, this study investigates the effect of moisture on the diffusion characteristics of furfural by combining macro experiment and micro molecular dynamics simulation. The simulation results demonstrate that the increased moisture content in paper accelerates the diffusion of furfural from paper to oil, which is also proved by the experimental data. Then, the results of interaction energy analysis indicate that the increase of moisture enhances the van der Waals force between oil and furfural. The present findings are expected to improve the theoretical level of furfural analysis, which will facilitate the aging evaluation of the transformer insulating paper based on furfural. [ABSTRACT FROM AUTHOR]

The space charge effect of transformer insulating paper will distort its internal electric field, and its space charge effect will be more prominent under extremely complex working conditions. At present, the micromechanism of charge transport and electric field distortion characteristics of paperboard are not clear under complex working conditions. So in this article, based on the bipolar carrier transport (BCT) model and the dynamic carrier balance model, the effects of high temperature, aging degree, moisture content, and bent degree on charges accumulation in paperboard are studied under dc high voltage by numerical simulation and the measured data needed for simulation. The results show that the higher temperature strengthens the carrier migration, deepens the injection depth of the charge, and aggravates the distortion of electric field intensity in paperboard. The more extended the aging time of paperboard, the greater the internal trap density and the deeper the trap depth, which lead to charges migration difficultly. Increasing water content in the paperboard will accelerate space charges to reach a steady state, while further increasing it will slow down this process, which is related to the shallow trap getting deeper. When the critical part of paperboard is extruded, many traps are introduced, resulting in charges accumulation seriously. The research results can reference the design of paperboard and the maintenance of transformer insulation system. [ABSTRACT FROM AUTHOR]

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]

This article is aimed at quantifying the health condition of the power transformer insulation system through its frequency-domain dielectric characteristic by using the concept of the resistor and fractional calculus. In this regard, the dielectric model of the fractional Poynting–Thomson (PT) is proposed, and a mathematical model for parameter identification of the proposed model is presented. The shuffled frog leaping algorithm (SFLA) is used to realize the parameter identification and the fractional PT model parameters of the oil-paper samples under different insulation health conditions. The influence of moisture and aging on the fractional PT dielectric model parameters is experimentally studied. Results show that, with the increase in the water content within the insulation system, the parameters of the fractional PT model gradually decrease, and there is a strong correlation between the relaxation time and the water content. This facilitates the employment of the fractional PT model parameters to quantify the aging and moisture content of the power transformer insulation system. [ABSTRACT FROM AUTHOR]

Pulp-and-paper mills produce various types of contaminants and a significant amount of wastewater depending on the type of processes used in the plant. Since the generated wastewaters can be potentially polluting and very dangerous, they should be treated in wastewater treatment plants before being released to the environment. This paper reviews different wastewater treatment processes used in the pulp-and-paper industry and compares them with respect to their contaminant removal efficiencies and the extent of greenhouse gas (GHG) emission. It also evaluates the impact of operating parameters on the performance of different treatment processes. Two mathematical models were used to estimate GHG emission in common biological treatment processes used in the pulp-and-paper industry. Nutrient removal processes and sludge treatment are discussed and their associated GHG emissions are calculated. Although both aerobic and anaerobic biological processes are appropriate for wastewater treatment, their combination known as hybrid processes showed a better contaminant removal capacity at higher efficiencies under optimized operating conditions with reduced GHG emission and energy costs. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that students who are engaged in learning tasks and make errors before receiving instruction on how to complete them, achieve better learning outcomes than students who first receive instruction and then complete the learning activities with the aim of avoiding errors. Although simulation literature often refers to errors as learning opportunities, to date, there is limited understanding of how pedagogical approaches that promote learning from errors can guide the design of simulation-based learning in healthcare education. To (a) present the Learning from Errors conceptual model; and (b) provide an example of how educators can use this model. The Learning from Errors model is drawn from critical elements of two pedagogical approaches, productive failure and error management training and pedagogical features of high-quality healthcare simulations. We describe the Learning from Errors model, which emphasises the need for adopting pedagogical methods that explicitly use errors as learning opportunities and ultimately inform simulation design. We then illustrate the application of this model to a simulation example. The model includes the following elements: i) normalisation of errors, ii) challenging simulation scenarios, iii) self-directed learning, iv) collaborative teamwork and v) comparison with best practice. This discussion paper presents the Learning from Errors conceptual model, an evidence-based approach that can assist educators in the design of simulations that embrace errors as a catalyst for learning. [ABSTRACT FROM AUTHOR]

Methanol concentration as an aging indicator can assess cellulose aging and estimate cellulose degree of polymerization (DP). Despite the advantages of methanol (MeOH), its major disadvantage is that its concentration in the oil decreases after some time. This point is called the MeOH peak in this article. Therefore, using this indicator when MeOH concentration is reduced leads to incorrect results. When using methanol, the main problem is that whenever the methanol concentration in a transformer is measured, it cannot be identified that the measured concentration belongs to the left or right side of the MeOH peak. If the measured concentration belongs to the right side of the MeOH peak, the estimated DP is incorrect. In this article, an empirical equation is established to estimate the DP value as a function of methanol concentration when methanol concentration belongs to the left side of the MeOH peak. Then, a new index called methanol peak detector index (MPDI) composed of a 2-furfural/MeOH ratio and normalized DP is presented to ensure the validity of the calculated DP value. If it is found that the measured concentration belongs to the left side of the MeOH peak, then the estimated DP by the presented equation is valid. Finally, the application of this method is verified by applying it to measurement data samples indicating the validity of the method. [ABSTRACT FROM AUTHOR]

The traditional method for transformer moisture diagnosis is to establish empirical equations between feature parameters extracted from frequency domain spectroscopy (FDS) and the transformer’s moisture content. However, the established empirical equation may not be applicable to a novel testing environment, resulting in an unreliable evaluation result. In this regard, it is acknowledged that FDS combined with machine learning is more suitable for estimating moisture content in a variety of test environments. Nonetheless, the accuracy of the estimation results obtained using the existing method is limited by the algorithm’s inability to generalize. To address this issue, we propose an AdaBoost algorithm-enhanced back-propagation neural network (BP_AdaBoost). This study creates a database by extracting feature parameters from the FDS that characterize the insulation states of the prepared samples. Then, using the BP_AdaBoost algorithm and the newly constructed database, the moisture estimation models are trained. Finally, the results of the estimation are discussed in terms of laboratory and field transformers. By comparing the proposed BP_AdaBoost algorithm to other intelligence algorithms, it is demonstrated that it not only performs better in generalization, but also maintains a high level of accuracy. [ABSTRACT FROM AUTHOR]

Paper-cutting is a traditional Chinese art, and Fuyang paper-cutting is a miracle of Chinese paper-cutting art. As Fuyang paper-cutting art is gradually promoted by artists during the historical inheritance, its traditional form has changed, a batch of new-style paper-cutting artworks have been created, Wang Xiaying is a leading figure in its inheritance. From the perspective of manifestation means and modeling language, this paper found that Wang Xiaying on the basis of inheriting traditional paper-cutting learned from other arts, applied innovative techniques to break through limitations in modeling, and realized the innovation of paper-cutting art It was concluded that traditional paper-cutting arts could only achieve sustainable development by integrating with new elements. [ABSTRACT FROM AUTHOR]

Does the materiality of a three-dimensional model have an effect on how this model operates in an exploratory way, how it prompts discovery of new mathematical results? Material mathematical models were produced and used during the second half of the nineteenth century, visualizing mathematical objects, such as curves and surfaces—and these were produced from a variety of materials: paper, cardboard, plaster, strings, wood. However, the question, whether their materiality influenced the status of these models—considered as exploratory, technical, or representational—was hardly touched upon. This article aims to approach this question by investigating two case studies: Beltrami's paper models vs. Dyck's plaster ones of the hyperbolic plane; and Chisini's string models of braids vs. Artin's and Moishezon's algebraization of these braids. These two case studies indicate that materiality might have a decisive role in how the model was taken into account mathematically: either as an exploratory or rather as a technical or pedagogical object. [ABSTRACT FROM AUTHOR]

The imbalance between the prevalence of patients with acute respiratory failure (ARF) and acute-on-chronic respiratory failure and the number of intensive care unit (ICU) beds requires new solutions. The increasing use of non-invasive respiratory tools to support patients at earlier stages of ARF and the increased expertise of non-ICU clinicians in other types of supportive care have led to the development of adult pulmonary intensive care units (PICUs) and pulmonary intermediate care units (PIMCUs). As in other European countries, Italian PICUs and PIMCUs provide an intermediate level of care as the setting designed for managing ARF patients without severe non-pulmonary dysfunction. The PICUs and PIMCUs may also act as step-down units for weaning patients from prolonged mechanical ventilation and for discharging patients still requiring ventilatory support at home. These units may play an important role in the on-going coronavirus disease 2019 pandemic. This position paper promoted by the Italian Thoracic Society (ITS-AIPO) describes the models, facilities, staff, equipment, and operating methods of PICUs and PIMCUs. [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]

Video halftoning is a key technology for use in electronic paper (e-paper) or smart paper, which is an emerging display device that has received considerable attention recently. In this paper, a temporal frequency of flickering-distortion optimized video halftoning method is proposed. We first uncover three visual defects that conventional neighboring frame referencing-based video halftoning methods, due to their sequential changes of reference frames, will encounter. To deal with the problem, we then propose a reference frame update per GOP-based error diffusion video halftoning method based on a flickering sensitivity-based human visual model. To efficiently compromise between average temporal frequency of flickering (ATFoF) and visual quality, temporal frequency of flickering-distortion (TFoFD) is presented as a metric for video halftoning performance evaluation. Based on the proposed probability model of video halftoning, the TFoFD curve can be accurately estimated to optimize the tradeoff between quality and ATFoF before the video is halftoned. Our temporal frequency of flickering-distortion optimization strategy can also be applied to other video halftoning schemes for performance improvement. Experimental results and comparisons with known methods demonstrate the effectiveness of our video halftoning method. [ABSTRACT FROM AUTHOR]

We give a direct proof of the main result of the paper 'Homomorphisms with respect to a function' by K. Boulabiar and F. Gdara [1] without using the Axiom of Choice. [ABSTRACT FROM AUTHOR]

The spatiotemporal arrangement of interacting populations often influences the maintenance of species diversity and is a subject of intense research. Here, we study the spatiotemporal patterns arising from the cyclic competition between three species in two dimensions. Inspired by recent experiments, we consider a generic metapopulation model comprising "rock-paper-scissors" interactions via dominance removal and replacement, reproduction, mutations, pair exchange, and hopping of individuals. By combining analytical and numerical methods, we obtain the model's phase diagram near its Hopf bifurcation and quantitatively characterize the properties of the spiraling patterns arising in each phase. The phases characterizing the cyclic competition away from the Hopf bifurcation (at low mutation rate) are also investigated. Our analytical approach relies on the careful analysis of the properties of the complex Ginzburg-Landau equation derived through a controlled (perturbative) multiscale expansion around the model's Hopf bifurcation. Our results allow us to clarify when spatial "rock-paper-scissors" competition leads to stable spiral waves and under which circumstances they are influenced by nonlinear mobility. [ABSTRACT FROM AUTHOR]

Abstract: The non-citation rate refers to the proportion of papers that do not attract any citation over a period of time following their publication. After reviewing all the related papers in Web of Science, Google Scholar and Scopus database, we find the current literature on citation distribution gives more focus on the distribution of the percentages and citations of papers receiving at least one citation, while there are fewer studies on the time-dependent patterns of the percentage of never-cited papers, on what distribution model can fit their time-dependent patterns, as well as on the factors influencing the non-citation rate. Here, we perform an empirical pilot analysis to the time-dependent distribution of the percentages of never-cited papers in a series of different, consecutive citation time windows following their publication in our selected six sample journals, and study the influence of paper length on the chance of papers’ getting cited. Through the above analysis, the following general conclusions are drawn: (1) a three-parameter negative exponential model can well fit time-dependent distribution curve of the percentages of never-cited papers; (2) in the initial citation time window, the percentage of never-cited papers in each journal is very high. However, as the citation time window becomes wider and wider, the percentage of never-cited papers begins to drop rapidly at first, and then drop more slowly, and the total degree of decline for most of journals is very large; (3) when applying the wider citation time windows, the percentage of never-cited papers for each journal begins to approach a stable value, and after that value, there will be very few changes in these stable percentages, unless we meet a large amount of “Sleeping Beauties” type papers; (4) the length of an paper has a great influence on whether it will be cited or not. [Copyright &y& Elsevier]

A method was developed to estimate the composition of deinked pulp or recovered paper in terms of hardwood kraft pulp, softwood kraft pulp, and mechanical pulp through analysis of the sugar units in hemicelluloses and pectins. Different pulps (i.e., bleached chemical pulp from hardwoods and softwoods and mechanical pulp) were obtained from different mills. The pulps were mixed in different proportions and dried. The content of arabinose, xylose, mannose, galactose, rhamnose, galacturonic acid, and 4-O-methyl-glucuronic acid, sugar units in hemicelluloses and pectins in the different pulps and in the mixtures were determined by acid methanolysis and gas chromatography. The contents of the sugar units were significantly different in the three pulp types but quite similar in the same pulp type, irrespectively of bleaching sequence. The modeling was performed using standard partial least squares regression (PLSR) and cross-validation using venetian blinds subsets. The data were autoscaled before regressions. The best model had two latent variables. The cumulative variation of X captured by the model was 0.988 (R²X), the cumulative variation of Y captured by the model was also 0.988 (R²Y), and the cumulative cross-validated variation of Y captured by the model was 0.974 (Q²). Accordingly, the PLS model is more than capable of predicting the validation set. It was concluded that the proportion of chemical pulp from hardwoods, chemical pulp from softwoods, and mechanical pulp can be estimated in recovered paper or deinked pulp using a mathematical model based on the content of selected sugar units in hemicelluloses and pectins. [ABSTRACT FROM AUTHOR]

The article discusses the study which develops a dynamic modular paper machine simulator package. It has been noted that computer simulation can be a valuable tool for the optimization of paper production processes, designing wastewater closure strategies and the visualization of a complicated process. It shows that by structuring the simulator as a set of modular blocks, a variety of configurations can be modeled by assembling the blocks in different ways. In addition, researchers have recommended that the simulator package can help in developing simple models for the simulation of complex dynamic systems.

We consider a one-dimensional cutting stock problem (CSP) in which the stock widths are not used to fulfill the order but kept for use in the future for the industrial-use paper production. We present a new model based on the flexible stock allocation and trim loss control to determine the production quantity. We evaluate our approach using a real data and show that we are able to solve industrial-size problems, while also addressing common cutting considerations such as aggregation of orders, multiple stock widths, and cutting different patterns on the same machine. In addition, we compare our model with others, including trim loss minimization problem (TLMP) and cutting stock problem (CSP). The results show that the proposedmodel outperforms the other two models regarding total flexibility and trim loss ratio. [ABSTRACT FROM AUTHOR]

Abstract: The use of paper-mill residuals in concrete formulations provides an alternative to landfill disposal. A response surface statistical methodology was carried out to model the influence on the slump and compressive strength of concrete containing paper-mill residuals with and without Class F fly ash replacement. The variables considered in this study included the water/cement ratio (w/c), paper-mill residual content and fly ash content to total cementitious material (FA/CM). The performance of the derived models to achieve good balance between the workability and compressive strength were further discussed by using the contour diagrams. The results showed that the compressive strength of concrete containing paper-mill residuals could be predicted from the referred slump value. [Copyright &y& Elsevier]

Abstract: The migration of components from paper into Tenax® was studied to determine the influence of molecular size and chemical character of the migrant and the influence of paper characteristics in the migration process. The Weibull model was applied because Fick’s 2nd law of diffusion gave poor fits in some cases. The migration pattern depended on the migrants molecular size and was independent of temperature in the studied range. The migration rate decreased with the migrant molecular size. The influence of the migrants character (polarity and vapour pressure) on the migration behaviour was also studied: nonpolar migrants with high vapour pressure presented low relative migration values and polar migrants presented high values of relative migration. Results indicated that the apparent partition coefficient between paper and the simulant Tenax® increased with the migrant vapour pressure and with both the paper grammage and the recycled pulp content. [ABSTRACT FROM AUTHOR]

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 accuracy of insulation defect diagnosis based on the dielectric spectrum response is severely influenced by temperature for oil-impregnated paper bushing. The dielectric loss (tan δ) mathematical model with a temperature–frequency factor to restrict the application of the frequency domain dielectric spectrum (FDS) for insulation diagnosis is not clear. In this paper, five temperatures are selected to study the frequency temperature characteristic of the FDS and polarization current for oil-impregnated paper bushing. The experimental results show that the temperature has different effects on the lower frequency (0.001 Hz–1 Hz) and higher frequency (1000 Hz–10 kHz) of FDS. With the increasing temperature, the lower frequency tan δ of 1 mHz–1 Hz shows a better pattern of exponential growth, while the higher frequency tan δ at 1 kHz–10 kHz shows the declining law with the rising temperature. With the increasing temperature, the polarization current shows a better pattern of exponential growth, while resistance obviously shows the declining law of the exponential pattern. The FDS curve of oil-impregnated paper bushings can be amended by the mathematical model of tan δ for the dielectric response on site for accuracy diagnosis. [ABSTRACT FROM AUTHOR]

This work is concerned with the determination of the adhesion strength between a paper web and an adhesive surface. Edvards- son et al. [Edvardsson, S., Gradin, P., and Isaksson, P., "On Dissipative Effects of Paper Web Adhesion Strength," Int. J. Solids Struct., Vol. 48(1), 2011, pp. 24-30] suggested recently a model that takes into account the energy dissipation caused by elastic-plastic deformation in the bent structure of a paper specimen. This model is fial'ther developed and investigated in the present work. A linear relation in plastic dissipation is discovered facilitating a novel analysis of the peeling tension and a more convenient determination of the proper adhesion strength. Industrial relevant examples are made with wet newsprint and kraft stock. A straightforward experimental procedure for determining the consistent adhesion strength is suggested. It is found that the agreement between the model and the experimental observations is good. [ABSTRACT FROM AUTHOR]

Waste paper is suitable for recycling back into paper or for incineration for energy recovery. If waste paper is used for recycling, secondary pulp replaces virgin pulp. Fiber recycling is limited, however, because of physical constraints—particularly the breakage of fiber in the recycling process—and a permanent input of virgin fiber to the system is required. Therefore one can expect that the relationship between recycling rates and resource requirements is represented by a curved line rather than a straight one. In this article, we present a mathematical model which confirms that the relationship between recycling rates and primary pulp requirements can be described as nonlinear. Furthermore, we show that this nonlinear relationship leads to an optimal recycling rate with regard to energy consumption: 93% for paper produced from chemical pulp, and 81% for paper produced from mechanical pulp. Sensitivity testing additionally reveals that at low recycling rates increasing waste paper recycling is energy efficient, but it becomes less efficient at higher recycling rates. Close to the optimum recycling rates (within 10%), increasing or decreasing the rate affects the total energy requirement less than 0.3%. [ABSTRACT FROM AUTHOR]

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Abstract: The conversion of ethanol from paper sludge using the separate hydrolysis and fermentation (SHF) process with cellulase and Saccharomyces cerevisiae GIM-2 were investigated in this paper. Optimization strategy based on statistical experimental designs was employed to enhance degree of saccharification by enzymatic hydrolysis of paper sludge. Based on the Plackett–Burman design, hydrolysis time, substrate concentration and cellulase dosage were selected as the most significant variable on the degree of saccharification. Subsequently, the optimum combination of the selected factors was investigated by a Box-Behnken approach. A mathematical model was developed to show the effects of each factor and their combinatorial interactions on the degree of saccharification. The optimal conditions were hydrolysis time 82.7 h, substrate concentration 40.8 g L−1 and cellulase dosage 18.1 FPU g−1 substrate, and a degree of saccharification of 82.1% can be achieved. When hydrolysate was further fermented with S. cerevisiae GIM-2, the conversion rate of sugar to ethanol was 34.2% and the ethanol yield was 190 g kg−1 of dry paper sludge, corresponding to an overall conversion yield of 56.3% of the available carbohydrates on the initial substrate. The results derived from this study indicate that the response surface methodology is a useful tool for optimizing the hydrolysis conditions to converse paper sludge to ethanol. [Copyright &y& Elsevier]

Abstract: Gas diffusion media (GDM) and flow fields perform the task of distributing the reactant gases uniformly over the active electrochemical area in proton exchange membrane (PEM) fuel cells. Carbon paper and carbon cloth are two commonly employed gas diffusion media in PEM fuel cells, and they differ widely in their structure and properties. Since the path of the reactant gases to the catalyst in the fuel cell electrodes involves passing through the flow fields as well as the GDM, a good design for a fuel cell requires an understanding of the interaction between these components. The focus of the present work is to study the impact of the difference in structure and properties of the diffusion media used, on the design of the PEM fuel cell flow field. Carbon paper and carbon cloth were characterized for the pressure drop they cause when used as GDMs, for channel intrusion, compressibility and electrical resistivity. Carbon cloth exhibits about 43–125% more intrusion into the channel in comparison with carbon paper for the conditions tested. This intrusion results in increased pressure drop in the flow channel especially at higher channel widths and at higher compression. Compression studies reveal that carbon cloth lacks compression rigidity and suffers considerable strain at lower stress values whereas carbon paper is relatively rigid in nature. The results indicate that the intrusion of carbon cloth into the channel, constraints the channel width in a flow field design if it were to be used with a carbon cloth GDM as opposed to a carbon paper GDM. Electrical resistivity measurements were carried out and a simple mathematical model has been developed for the potential drop in the GDM. The model indicates that even from the perspective of electrical properties, use of carbon cloth GDM constraints the channel width that is permissible in flow field design. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the determinability of time related colour changes in prints made using ink that dries on matte coated paper with the offset printing technique and infrared method, has been investigated with artifical neural networks after analysis of the experimental and numerical methods. In the experimental part a ECI 2002 CMYK test scale is printed on a 135g/m2 matte coated. The prints obtained were measured with a spectrophotometer at certain intervals and by converting the reflection data obtained into the CIELAB colour description spectrum, time related changes in printed colours have been determined. In the empirical study however, colour changes in prints made on matte coated paper using inks that dry with the infrared method are modelled numerically. The average deviation has been found to be 0.4%. As a result, artificial neural networks can be used with the aim to digitally calculate time related colour changes in the offset printing system. [Copyright &y& Elsevier]

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]

In this paper, a finite element procedure is used to study the dynamic behaviour of a paper web in a free span between two rollers, including effects of transport velocity and surrounding air. The paper web is modelled as a three-dimensional orthotropic structure. The influence of air is accounted for by utilizing fluid–solid interaction analyses based on acoustic theory. The contribution of transport velocity is included through gyroscopic matrices and forces. The structural response on harmonic excitations has been studied using linear and non-linear models. Results show that air significantly reduces eigenfrequencies of the web. So called “edge-flutter” is nothing but the result of skew tension profile. Excessive web vibration can be eliminated by adjusting the web tension. [Copyright &y& Elsevier]

Abstract: A lot of work has been done in the field of multi-valued model checking home and abroad. But some research works are not perfect. Some problems in the semantic definitions of temporal operators and corresponding model checking algorithms are found in the paper “Model Checking Using Partial Kripke Structure with 3-Valued Temporal Logic”. Some counterexamples are given to show these errors. On the basis of the discussion, some sound semantic definitions of temporal operators and correct algorithms of model checking for some temporal operators are given. [Copyright &y& Elsevier]

We prove that the pleated hyperbolic paraboloid, a familiar origami model known since 1927, in fact cannot be folded with the standard crease pattern in the standard mathematical model of zero-thickness paper. In contrast, we show that the model can be folded with additional creases, suggesting that real paper 'folds' into this model via small such creases. We conjecture that the circular version of this model, consisting simply of concentric circular creases, also folds without extra creases. At the heart of our results is a new structural theorem characterizing uncreased intrinsically flat surfaces-the portions of paper between the creases. Differential geometry has much to say about the local behavior of such surfaces when they are sufficiently smooth, e.g., that they are torsal ruled. But this classic result is simply false in the context of the whole surface. Our structural characterization tells the whole story, and even applies to surfaces with discontinuities in the second derivative. We use our theorem to prove fundamental properties about how paper folds, for example, that straight creases on the piece of paper must remain piecewise-straight (polygonal) by folding. [ABSTRACT FROM AUTHOR]

We fabricated multiwalled carbon-nanotube/cellulose composite papers and measured their temperature dependences of electrical conductivity. The dependences were described with the Sheng’s fluctuation-induced tunneling (FIT) model. A possible mechanism of the electrical conduction in the composite paper was discussed in the context of the FIT model. [ABSTRACT FROM AUTHOR]

The article presents information about the main characteristics of a fully developed kinetic model for describing the process of cellulose paper degradation. The parameters that must be monitored during the accelerated ageing tests in closed vessels are highlighted. According to the study, the rate of degradation of paper depends on the initial number of cellulose bonds available for degradation.

We investigate the population dynamics in generalized rock-paper-scissors models with an arbitrary number of species Ν. We show that spiral patterns with Ν arms may develop both for odd and even N, in particular in models where a bidirectional prédation interaction of equal strength between all species is modified to include one -cyclic predator-prey rule. While the former case gives rise to an interface network with Y-type junctions obeying the scaling law L ∝ t1/2, where L is the characteristic length of the network and t is the time, the latter can lead to a population network with N-armed spiral patterns, having a roughly constant characteristic length scale. We explicitly demonstrate the connection between interface junctions and spiral patterns in these models and compute the corresponding scaling laws. This work significantly extends the results of previous studies of population dynamics and could have profound implications for the understanding of biological complexity in systems with a large number of species. [ABSTRACT FROM AUTHOR]