Search

Purpose: Being the final end of the logistic distribution, attended home delivery (AHD) plays an important role in the distribution network. AHD typically refers to the service provided by the distribution service provider to the recipient's doorstep. Researchers have always identified AHD as a bottleneck for last-mile delivery. This paper addresses a real-life stochastic multi-objective AHD problem in the context of the Indian public distribution system (PDS). Design/methodology/approach: Two multi-objective models are proposed. Initially, the problem is formulated in a deterministic environment, and later on, it is extended to a multi-objective AHD model with stochastic travel and response time. This stochastic AHD model is used to extensively analyze the impact of stochastic travel time and customer response time on the total expected cost and time-window violation. Due to the NP-hard nature of the problem, an ant colony optimization (ACO) algorithm, tuned via response surface methodology (RSM), is proposed to solve the problem. Findings: Experimental results show that a change in travel time and response time does not significantly alter the service level of an AHD problem. However, it is strongly correlated with the planning horizon and an increase in the planning horizon reduces the time-window violation drastically. It is also observed that a relatively longer planning horizon has a lower expected cost per delivery associated. Research limitations/implications: The paper does not consider the uncertainty of supply from the warehouse. Also, stochastic delivery failure probabilities and randomness in customer behavior have not been taken into consideration in this study. Practical implications: In this paper, the role of uncertainty in an AHD problem is extensively studied through a case of the Indian PDS. The paper analyzes the role of uncertain travel time and response time over different planning horizons in an AHD system. Further, the impact of the delivery planning horizon, travel time and response time on the overall cost and service level of an AHD system is also investigated. Social implications: This paper investigates a unique and practical AHD problem in the context of Indian PDS. In the present context of AHD, this study is highly relevant for real-world applications and can help build a more efficient delivery system. The findings of this study will be of particular interest to the policy-makers to build a more robust PDS in India. Originality/value: The most challenging part of an AHD problem is the requirement of the presence of customers during the time of delivery, due to which the probability of failed delivery drastically increases if the delivery deviates from the customer's preferred time slot. The paper modelled an AHD system to incorporate uncertainties to attain higher overall performance and explore the role of uncertainty in travel and response time with respect to the planning horizon in an AHD, which has not been considered by any other literature. [ABSTRACT FROM AUTHOR]

Mosquito breeding-sites are an essential resource for mosquito growth, yet an understanding of their existence and creation, in the case of temporary habitats, have not been mathematically studied. Hence, we use a system of two first order nonlinear ordinary differential equations to model and theoretically investigate the dynamics of temporary mosquito breeding-sites formation in a uniform environment. The model captures the dynamic interplay between community action, climatic factors and availability of temporary mosquito breeding-sites by interpreting the possible pathways and environmental processes leading to temporary breeding-sites formation. Model's analysis show it is possible to eliminate temporary breeding-sites from around a close vicinity to human habitats by increasing the level of human consciousness, with human consciousness measured via human response to community action. Different feedback response functions are used to excite breeding-site removal and community action. When the response functionals are both constants, an indicator function is identified, whose size can indicate whether in the long-run, community action can lead to the removal and elimination of temporary breeding-sites near human habitats. Using a predictor–corrector procedure that fits real climatic data to a continuous periodic function, we demonstrate how climatic variables can be included in the model and how the time variation of temperature and precipitation in a given area can be constructed just by appropriately choosing the parameters of a sinusoidal function and then correcting the output using nonlinear least squares analysis. Numerical simulation results are used to complement our analytical results showing the different dynamical behaviours that can be obtained. When breeding-site densities are high, human consciousness starts rising and its effect can lead to the reduction of breeding-site density, measured, and interpreted via community action. In some scenarios, the response can lead to complete removal of the breeding sites, while in others it may enter a limit cycle with different transient dynamics determined by the temperature parameters, waning rate of consciousness and breeding site impact on igniting consciousness. The novelty in this manuscript lies in the idea in which the focus is on modelling temporary mosquito breeding-sites, a process that is natural, yet neglected. Additionally, the incorporation of human consciousness highlights the need for a better understanding of human factors in neglected population dynamics studies and to attempt to correlate consciousness to adherence and its influence on disease control. Our mathematical model to address the problem of mosquito breeding-site formation, an important problem that has minimally been addressed, serves as a foundational model that can be extended to incorporate stochasticity in breeding site formation. • Breeding sites eliminated through community/individual actions due to increased human consciousness. • Interplay between community action, climate and breeding site availability captured. • Predictor–corrector procedure fitting local climatic data to continuous periodic function. • High breeding site density could drive increase in human consciousness. • Climatic factors do affect the density of breeding sites in an appreciable way. [ABSTRACT FROM AUTHOR]

A fundamental feature of collective cell migration is phenotypic heterogeneity which, for example, influences tumour progression and relapse. While current mathematical models often consider discrete phenotypic structuring of the cell population, in-line with the 'go-or-grow' hypothesis (Hatzikirou et al., 2012; Stepien et al., 2018), they regularly overlook the role that the environment may play in determining the cells' phenotype during migration. Comparing a previously studied volume-filling model for a homogeneous population of generalist cells that can proliferate, move and degrade extracellular matrix (ECM) (Crossley et al., 2023) to a novel model for a heterogeneous population comprising two distinct sub-populations of specialist cells that can either move and degrade ECM or proliferate, this study explores how different hypothetical phenotypic switching mechanisms affect the speed and structure of the invading cell populations. Through a continuum model derived from its individual-based counterpart, insights into the influence of the ECM and the impact of phenotypic switching on migrating cell populations emerge. Notably, specialist cell populations that cannot switch phenotype show reduced invasiveness compared to generalist cell populations, while implementing different forms of switching significantly alters the structure of migrating cell fronts. This key result suggests that the structure of an invading cell population could be used to infer the underlying mechanisms governing phenotypic switching. • A model for heterogeneous cells invading into ECM is proposed. • Two sub-populations of cells that either move and degrade ECM or proliferate. • We compare travelling waves of heterogeneous specialists to homogeneous generalists. • The speed and structure of invading cells depends on the phenotypic switching mechanism. [ABSTRACT FROM AUTHOR]

Polyclonal antibody–antigen reactions assuming constant free antibody clone concentrations and monovalent reactants are modelled by using a linear system of differential equations. The positive invariance of the simplex of immunologically meaningful points is shown, the unique equilibrium point is determined and its global asymptotic stability is proven. The trajectory starting at the origin is examined. Numerical simulations illustrate the results. [ABSTRACT FROM AUTHOR]

• 14 new IT2FPID controllers are proposed using multiple fuzzy sets and 1D input space. • The validity of the controllers is examined, and their properties are studied. • Effects of the FOUs on the structures of the proposed controllers are investigated. • Applicability of the controllers is demonstrated in simulation and real-time. • Effectiveness of the controllers is depicted through system performance comparison. Interval Type-2 Fuzzy PID (IT2FPID) controllers use Interval Type-2 Fuzzy Sets (IT2FSs). The difference between Type-1 Fuzzy PID (T1FPID) controllers and IT2FPID controllers is the Footprint of Uncertainty (FOU) which occurs due to the use of IT2FSs. FOU gives an extra degree of freedom to the controller structure, which is capable of handling uncertainty in the plant. However, the effect of FOU on the analytical structures of the IT2FPID controllers is not yet explored when uniformly/non-uniformly distributed multiple IT2FSs are used on the input side and uniformly/non-uniformly distributed multiple singleton fuzzy sets are considered on the output side of the controller. In this paper, controllers with three different types of FOUs and two different defuzzification methods are considered, and their analytical structures are derived. The suitability of the controllers is examined, and the properties of the suitable controllers are explored. Effects of FOU on the nonlinearity, gain, and computational aspects of the suitable controllers are studied. The applicability of proposed IT2FPID controllers is shown through simulation and real-time studies. The effectiveness of the proposed controllers is depicted by comparing their performances with that of the recently developed Integer Order Fuzzy PID (IOFPID) and Fractional Order Fuzzy PID (FOFPID) controllers. [ABSTRACT FROM AUTHOR]

Purpose: This work is devoted to increasing the effectiveness of a mathematical modelling lesson with the help of mobile devices. It verifies the authors' hypothesis which states that enabling students to solve mathematical models on mobile devices improves their academic results in the discipline. Design/methodology/approach: The paper describes an experiment conducted among 38 college students in an extracurricular mathematical club where they solved mathematical models with the help of their own smartphones. The authors describe the mathematical models assigned to students, analyse their academic performance and gather their opinions. Findings: The usage of mobile devices in the mathematical modelling class positively affects students' scores and interest in the subject. The percentage of positive grades among students working on mobile devices is higher than among students working on desktop computers. Originality/value: The authors discover that in the context of the college-level mathematical modelling course, mobile devices can be successfully used as an alternative replacement for traditional desktop computers. [ABSTRACT FROM AUTHOR]

Purpose: Carbon emission is a significant issue for the current business market and global warming. Nowadays, most countries have focused to reduce the environmental impact of business with durable financial benefits. The purpose of this study is to optimize the entire cost functions with carbon emission and to find the sustainable optimal ordering quantity for retailers. Design/methodology/approach: This paper illustrates a sustainable inventory model having a set of two non-instantaneous substitutable deteriorating items under joint replenishment with carbon emission. In this model demand and deterioration rate are considered as deterministic, constant and triangular fuzzy numbers. The objective is to find the optimal ordering quantity for retailers and to minimize the total cost function per unit time with carbon emission. The model is then solved with the help of Maple software. Findings: This paper presents a solution method and also develop an algorithm to determine the order quantities which optimize the total cost function. A numerical experiment illustrates the improvement in optimal total cost of the inventory model with substitution over without substitution. The graphical results show the convexity of the cost function. Finally, sensitivity analysis is given to get the impact of parameters and validity of the model. Originality/value: This study considers a set of two non-instantaneous substitutable deteriorating items under joint replenishment with carbon emission. From the literature review, in the authors' knowledge no researcher has undergone this kind of study. [ABSTRACT FROM AUTHOR]

Atmospheric corrosion of metals is the most common type of corrosion which has a significant impact on the environment and operational safety in various situations of everyday life. Some of the common examples can be observed in land, water and air transportation systems, electronic circuit boards, urban and offshore infrastructures. The dew drops formed on metal surface due to condensation of atmospheric moisture facilitates corrosion as an electrolyte. The corrosion mechanisms under these droplets are different from classically known bulk electrolyte corrosion. Due to thin and non-uniform geometric thickness of the droplet electrolyte, the atmospheric oxygen requires a shorter diffusion path to reach the metal surface. The corrosion under a droplet is driven by the depletion of oxygen in the center of the droplet compared to the edge, known as differential aeration. In case of a larger droplet, differential aeration leads to preferential cathodic activity at the edge and is controlled by the droplet geometry. Whereas, for a smaller droplet, the oxygen concentration remains uniform and hence cathodic activity is not controlled by droplet geometry. The geometry of condensed droplets varies dynamically with changing environmental parameters, influencing corrosion mechanisms as the droplets evolve in size. In this review, various modelling approaches used to simulate the corrosion under droplet electrolytes are presented. In the efforts of developing a comprehensive model to estimate corrosion rates, it has been noted from this review that the influence of geometric evolution of the droplet due to condensation/evaporation processes on corrosion mechanisms are yet to be modelled. Dynamically varying external factors like environmental temperature, relative humidity, presence of hygroscopic salts and pollutants influence the evolution of droplet electrolyte, making it a complex phenomenon to investigate. Therefore, an overview of available dropwise condensation and evaporation models which describes the formation and the evolution of droplet geometry are also presented from an atmospheric corrosion viewpoint. [ABSTRACT FROM AUTHOR]

Purpose: Based on generic reviews of research on school leadership, this study aims to conceptualize an emerging leadership competence model for further prioritizing school leadership training needs by decision-making trial and evaluation laboratory (DEMATEL)-based analytic network process (ANP). Targeting at a specific group of junior high school principals in Taiwan, the synthesized prioritization of core competences and competence indicators computed by DEMATEL-based ANP can be used as a blueprint for systematically developing school principal preparation programs elsewhere based on contextually specific needs and concerns. Design/methodology/approach: For the purpose of detecting the priority of competences extracted from a plethora of literature in relation to school leaders' skills, abilities and knowledge, a hybrid MCDM model, known as DEMATEL-based ANP, is used to snapshot critical leadership competences for tailoring the intended junior high school principal preparation program. Findings: Results of global weight computations by DEMATEL-based ANP show that the overall prioritization of the five dimensions in ranking order are "Redesigning the organization," "Related leadership practices," "Setting Directions," "Personal Characteristics" and "Developing People." Factor-level analysis indicated that "Legality," "Consensus Building," "Shared Vision," "Strategic Management," "Authoritarianism," "Modeling Behavior" and "High Performance Emphasis" were prioritized factors to be included in developing the intended school principal preparation program. Research limitations/implications: Contextually based findings yielded from DEMATEL-based ANP would only be applicable to the target context under investigation. Generalizing the findings to junior high school principals elsewhere might not be appropriate. Methods introduced in this study are extensible to further studies aiming at shaping leadership trainings in other school settings to achieve maximum impact based on contextually specific needs. Limitations associated with sophisticated mathematical computations involved in performing high-leverage MCDM models would shed light on the importance of interdisciplinary collaborations between scholars, practitioners and methodologists. Practical implications: To efficiently deliver training for junior high school principals, the prioritization of core competences and competence indicators solicited by DEMATEL-based ANP can be used as a scenario-based reference for planning the intended school principal preparation program planning, as well as a mechanism for selecting and evaluating potential and incumbent school principals with desired leadership competences. Originality/value: This study has used DELATEL-based ANP as a decision-making tool to disclose a plethora of competences extracted from different threads in the literature into a prioritized competence framework that differs from past one-size-fit-all approach to design and plan school principal preparation programs. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate a fuzzy hybrid approach for ranking the flare gas recovery methods and allocating to refineries. Design/methodology/approach: The proposed approach is containing four stages: in the first stage, experts' assessment is applied to identify relevant criteria and sub-criteria in the evaluation of flare gas recovery methods. In the second stage, the corresponding weights of criteria and sub-criteria are determined via fuzzy decision-making trial and evaluation (DEMATEL)-analytical network process (ANP) (DANP) method. In the third stage, the flare gas recovery methods are ranked using fuzzy weighted aggregated sum product assessment method (WASPAS) multi-criteria decision-making (MADM) technique. In the fourth stage, an optimization model is developed to allocate gas recovery methods to refineries while maximizing the total utility of allocations based on model constraints. Findings: According to the results of fuzzy DANP method, technical and operational criterion was the most important followed by economic, political, managerial and environmental criteria. With respect to sub-criteria, international sanctions and political stability were the most important. The results of fuzzy WASPAS method indicated that gas injection was the first ranked alternative. Finally, the mathematical modeling allocated the recovery methods to five refineries of South Pars gas field in Iran based on budget and time constraints. Originality/value: The proposed approach provides a systematic tool in the selection of flare recovery methods and allocation to refineries. This approach uses a new combination of fuzzy DEMATEL-ANP (DANP) method, fuzzy WASPAS method and mathematical programming. The approach is effectively implemented in a case study for ranking the flare gas recovery methods and allocating to refineries of South Pars gas field in Iran. [ABSTRACT FROM AUTHOR]

Multidisciplinary approaches can significantly advance our understanding of complex systems. For instance, gene co-expression networks align prior knowledge of biological systems with studies in graph theory, emphasising pairwise gene to gene interactions. In this paper, we extend these ideas, promoting hypergraphs as an investigative tool for studying multi-way interactions in gene expression data. Additional freedoms are achieved by representing individual genes with hyperedges, and simultaneously testing each gene against many features/vertices. Further gene/hyperedge interactions can be captured and explored using the line graph representations, a technique that reduces the complexity of dense hypergraphs. Such an approach provides access to graph centrality measures, which identifies salient features within a data set. For instance dominant or hub-like hyperedges, leading to key knowledge on gene expression. The validity of this approach is established through the study of gene expression data for the plant species Senecio lautus and results will be interpreted within this biological setting. • Identification of unique behaving genes through hypergraphs. • Application of centrality measures to reveal salient features of data. • Useful visual tools and representations of hypergraphs and graphs. • Discussion of the significance of genes with respect to mathematics and biology. [ABSTRACT FROM AUTHOR]

• In bioengineered oncolytic adenoviruses, higher viral infection rates are preferable. • Extreme (low or high) viral oncolysis rates lead to less effective treatment outcomes. • Under hypoxic conditions, oncolysis rates dominating over infectivity is favourable. • Local OV* injection has more pronounced systemic effect under oxygen rich conditions. We develop and analyze a mathematical model of oncolytic virotherapy in the treatment of melanoma. We begin with a special, local case of the model, in which we consider the dynamics of the tumour cells in the presence of an oncolytic virus at the primary tumour site. We then consider the more general regional model, in which we incorporate a linear network of lymph nodes through which the tumour cells and the oncolytic virus may spread. The modelling also considers the impact of hypoxia on the disease dynamics. The modelling takes into account both the effects of hypoxia on tumour growth and spreading, as well as the impact of hypoxia on oncolytic virotherapy as a treatment modality. We find that oxygen-rich environments are favourable for the use of adenoviruses as oncolytic agents, potentially suggesting the use of complementary external oxygenation as a key aspect of treatment. Furthermore, the delicate balance between a virus' infection capabilities and its oncolytic capabilities should be considered when engineering an oncolytic virus. If the virus is too potent at killing tumour cells while not being sufficiently effective at infecting them, the infected tumour cells are destroyed faster than they are able to infect additional tumour cells, leading less favourable clinical results. Numerical simulations are performed in order to support the analytic results and to further investigate the impact of various parameters on the outcomes of treatment. Our modelling provides further evidence indicating the importance of three key factors in treatment outcomes: tumour microenvironment oxygen concentration, viral infection rates, and viral oncolysis rates. The numerical results also provide some estimates on these key model parameters which may be useful in the engineering of oncolytic adenoviruses. [ABSTRACT FROM AUTHOR]

Highlights • A fundamental nonlinear mathematical model for cancer chemotherapy is presented. • A chemotherapeutic treatment consists of cytotoxic drugs delivered in periodic cycles. • The rate of destruction is proportional to the rate of growth of a similar unperturbed tumor. • Tumor cells regrow between cycles, reducing the benefits of the treatment. • The relative benefits of increasing the dose versus increasing the frequency are studied. Abstract A fundamental model of tumor growth in the presence of cytotoxic chemotherapeutic agents is formulated. The model allows to study the role of the Norton-Simon hypothesis in the context of dose-dense chemotherapy. Dose-dense protocols aim at reducing the period between courses of chemotherapy from three weeks to two weeks, in order to avoid tumor regrowth between cycles. We address the conditions under which these protocols might be more or less beneficial in comparison to less dense settings, depending on the sensitivity of the tumor cells to the cytotoxic drugs. The effects of varying other parameters of the protocol, as for example the duration of each continuous drug infusion, are also inspected. We believe that the present model might serve as a foundation for the development of more sophisticated models for cancer chemotherapy. [ABSTRACT FROM AUTHOR]

Highlights • New strategies are typically disadvantageous in stable populations. • Stochasticity can delay the extinction of a new strategy in a large, stable population. • Individuals that adopt the new strategy can change the environment of the population. • Changes in the environment can affect the stability of the population. • In this case, the new strategy might become advantageous. Abstract When a new type of individual appears in a stable population, the newcomer is typically not advantageous. Due to stochasticity, the new type can grow in numbers, but the newcomers can only become advantageous if they manage to change the environment in such a way that they increase their fitness. This dynamics is observed in several situations in which a relatively stable population is invaded by an alternative strategy, for instance the evolution of cooperation among bacteria, the invasion of cancer in a multicellular organism and the evolution of ideas that contradict social norms. These examples also show that, by generating different versions of itself, the new type increases the probability of winning the struggle for fitness. Our model captures the imposed cooperation whereby the first generation of newcomers dies while changing the environment such that the next generations become more advantageous. [ABSTRACT FROM AUTHOR]

Purpose The lack of reliable and scalable superconducting random access memory (RAM) cells is the main obstacle for full implementation of superconducting rapid single flux quantum(RSFQ) computers. This work points the methodology and the structures that shall be used in future implementation of RSFQ RAM.Design/methodology/approach A new design for RAM using two ferromagnetic strips in proximity to the superconductor in a RSFQ computer is presented (1). The concept of using a RAM RSFQ cell as a tuneable superconducting qubit is also explored.Findings Two basic architectures for superconducting RAM cells were developed with integration schemes in two dimensions.Research limitations/implications The proposed RAM cells as depicted in Figures 7 and 16 offer smaller size and greater 3 scalability in comparison to other suggested schemes (4), (3), (2), (5).Practical implications Currently, the main obstacle in implementation of RSQF computer is lack of reliable RAM cell. RSQF computer shall have potential to take a large fraction of classical supercomputers, as it consumes much less power.Social implications Computation power shall be cheaper when one uses RSQF computers for big data and computational centres. It is a matter of some time.Originality/value The publication presents the new design of superconducting RAM cell for use in RSQF computer. The numerical relaxation method is used to solve biharmonic Ginzburg–Landau equation. The analytic approach as a solution of a specified problem is given. [ABSTRACT FROM AUTHOR]

Highlights • This paper uses the boundary integral method to model the motion of a cell through a viscous fluid. • The model can be used to simulate chemotaxis. • The results of the calculations are compared to some experimental data. Abstract In experiments clusters of cells are often observed to move in response to a chemical signal which is present in the fluid surrounding the cells. This process is known as chemotaxis. This paper presents a method for modelling the motion of clusters of cells moving through a viscous fluid in response to a known chemical signal using a boundary integral formulation of the governing equations rather than the more usual differential equation formulation. The numerical results presented in this paper show that the boundary integral method can be used to simulate the motion of cell clusters through the fluid. The results of the simulations are compared to some experimental observations of cell and cluster motion. [ABSTRACT FROM AUTHOR]

The immune system turns out to have both stimulatory and inhibitory factors influencing on tumor growth. In recent years, the pro-tumor role of immunity factors such as regulatory T cells and TGF-β cytokines has specially been considered in mathematical modeling of tumor-immune interactions. This paper presents a novel structural methodology for reviewing these models and classifies them into five subgroups on the basis of immune factors included. By using our experimental data due to immunotherapy experimentation in mice, these five modeling groups are evaluated and scored. The results show that a model with a small number of variables and coefficients performs efficiently in predicting the tumor-immune system interactions. Though immunology theorems suggest to employ a larger number of variables and coefficients, more complicated models are here shown to be inefficient due to redundant parallel pathways. So, these models are trapped in local minima and restricted in prediction capability. This paper investigates the mathematical models that were previously developed and proposes variables and pathways that are essential for modeling tumor-immune. Using these variables and pathways, a minimal structure for modeling tumor-immune interactions is proposed for future studies. [ABSTRACT FROM AUTHOR]

We adapt a population-based model of Opisthorchis viverrini transmission dynamics to determine the effectiveness of three different interventions. The model includes the definitive hosts, humans; the reservoir hosts, dogs and cats; and the intermediate hosts, snails and fish. We consider the interventions: education campaigns to reduce the consumption of raw or undercooked fish, improved sanitation and treatment through mass drug administration. We fit model parameters to a data set from two islands in southern Lao PDR. We calculate the control reproduction number, simulate different scenarios and optimise the interventions with optimal control. We look at the potential of the interventions to eliminate transmission within 20 years. The model shows that education and improved sanitation need a very high coverage to fulfil the goal of elimination, whereas annual drug distribution at medium coverage is sufficient. The best solution is a combination of drug distribution at a medium level of coverage and as high as possible coverage of education and improved sanitation. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study is to design a DSS for construction sectors, which can determine the status of the related supplier alternatives, accompanying G-T, SC measures and their interrelated metrics. In today’s era, a supplier is observed as significant among entire agents of green supply chain (SC) management. Presently, it is determined that appraising worth of the supplier under green-traditional (G-T), SCs concerns still require the support of novel algorithmic/decision support systems (DSSs), which could embrace potential decision-making.Design/methodology/approach The authors have proposed a DSS (consisting of the implementation of multi-level multi-criterion decision-making [ML-MCDM], reference point approach [RPA] and multi-objective optimization on the basis of simple ratio analysis [MOOSRA] methods on constructed MCDM supplier evaluation appraisement module) for measuring the performance score of clay-brick suppliers coming under G-T SCs corresponding to fuzzy and non-fuzzy information. A comparative analysis is conducted among the performance scores against alternatives, obtained by the three methods, i.e. ML-MCDM, RPA and MOOSRA, for robustly making a potential decision.Findings The presented research offers a DSS toward managers of construction sectors for benchmarking the performance scores against supplier alternatives under G-T SC measures and their interrelated metrics, modeled by fuzzy cum non-fuzzy information.Originality/value Presented research work exhibited a DSS that can be used by construction sectors for benchmarking the supplier alternatives in accordance with their performance scores under G-T SCs. The MCDM G-T supplier evaluation appraisement module is constructed pertaining to small-scale clay-brick production units, located in the northern part of India to check the effectiveness of the proposed DSS. [ABSTRACT FROM AUTHOR]

The complexity of the anaerobic digestion process has motivated the development of complex models, such as the widely used Anaerobic Digestion Model No. 1. However, this complexity makes it intractable to identify the stability profile coupled to the asymptotic behaviour of existing steady-states as a function of conventional chemostat operating parameters (substrate inflow concentration and dilution rate). In a previous study this model was simplified and reduced to its very backbone to describe a three-tiered chlorophenol mineralising food-web, with its stability analysed numerically using consensus values for the various biological parameters of the Monod growth functions. Steady-states where all organisms exist were always stable and non-oscillatory. Here we investigate a generalised form of this three-tiered food-web, whose kinetics do not rely on the specific kinetics of Monod form. The results are valid for a large class of growth kinetics as long as they keep the signs of their derivatives. We examine the existence and stability of the identified steady-states and find that, without a maintenance term, the stability of the system may be characterised analytically. These findings permit a better understanding of the operating region of the bifurcation diagram where all organisms exist, and its dependence on the biological parameters of the model. For the previously studied Monod kinetics, we identify four interesting cases that show this dependence of the operating diagram with respect to the biological parameters. When maintenance is included, it is necessary to perform numerical analysis. In both cases we verify the discovery of two important phenomena; i) the washout steady-state is always stable, and ii) a switch in dominance between two organisms competing for hydrogen results in the system becoming unstable and a loss in viability. We show that our approach results in the discovery of an unstable operating region in its positive steady-state, where all three organisms exist, a fact that has not been reported in a previous numerical study. This type of analysis can be used to determine critical behaviour in microbial communities in response to changing operating conditions. [ABSTRACT FROM AUTHOR]

Radiofrequency ablation is a valuable tool in the treatment of many diseases, especially cancer. However, controlled heating up to apoptosis of the desired target tissue in complex situations, e.g. in the spine, is challenging and requires experienced interventionalists. For such challenging situations a mathematical model of radiofrequency ablation allows to understand, improve and optimise the outcome of the medical therapy. The main contribution of this work is the derivation of a tailored, yet expandable mathematical model, for the simulation, analysis, planning and control of radiofrequency ablation in complex situations. The dynamic model consists of partial differential equations that describe the potential and temperature distribution during intervention. To account for multipolar operation, time-dependent boundary conditions are introduced. Spatially distributed parameters, like tissue conductivity and blood perfusion, allow to describe the complex 3D environment representing diverse involved tissue types in the spine. To identify the key parameters affecting the prediction quality of the model, the influence of the parameters on the temperature distribution is investigated via a sensitivity analysis. Simulations underpin the quality of the derived model and the analysis approach. The proposed modelling and analysis schemes set the basis for intervention planning, state- and parameter estimation, and control. [ABSTRACT FROM AUTHOR]

Purpose The present investigation aims to deal with the study of unsteady, heat-generating/-absorbing and chemically reacting Casson fluid flow over a vertical cone and flat plate saturated with non-Darcy porous medium in the presence of cross-diffusion effects.Design/methodology/approach A numerical computation for the governing equations has been performed using implicit finite difference method of Crank–Nicolson type.Findings The influence of various physical parameters on velocity, temperature and concentration distributions is illustrated graphically, and the physical aspects are discussed in detail. Numerical results for average skin-friction, Nusselt number and Sherwood number are tabulated for the pertaining physical parameters. Results indicate that Soret and Dufour effects have notable influence on heat and mass transfer characteristics of the fluid when the temperature and concentration gradients are high. It is also observed that the consideration of heat generation/absorption plays a vital role in predicting the heat transfer characteristics of moving fluids.Research limitations/implications Consider a two-dimensional, unsteady, free convective flow of an incompressible Casson fluid over a vertical cone and a flat plate saturated with non-Darcy porous medium. The fluid properties are assumed to be constant except for density variations in the buoyancy force term. The fluid flow is moderate and the permeability of the medium is assumed to be low, so that the Forchheimer flow model is applicable.Practical implications The flow of Casson fluids (such as drilling muds, clay coatings and other suspensions, certain oils and greases, polymer melts and many emulsions), in the presence of heat transfer, is an important research area because of its relevance in the optimized processing of chocolate, toffee and other foodstuffs.Social implications In the heat and mass transfer investigations, the Casson fluid model is found to be accurately applicable in many practical situations in the wings of polymer processing industries and biomechanics, etc.; some prominent examples are silicon suspensions, suspensions of bentonite in water and lithographic varnishes used for printing inks.Originality/value The motivation of the present study is to bring out the effects of heat source/sink, Soret and Dufour effects on chemically reacting Casson fluid flow over a vertical cone and flat plate saturated with non-Darcy porous medium. The flow of Casson fluids (such as certain oils and greases, polymer melts and many emulsions) in the presence of heat transfer is an important research area because of its relevance in the optimized processing of chocolate, toffee and other foodstuffs. A numerical computation for the governing equations has been performed using implicit finite difference method of the Crank–Nicolson type. [ABSTRACT FROM AUTHOR]

It has been shown that prolonged systemic presence of a drug can cause a build-up of that drug in the skin. This drug ‘reservoir’, if properly understood, could provide useful information about recent drug-taking history of the patient. We create a pair of coupled mathematical models which combine to explore the potential for a drug reservoir to establish based on the kinetic properties of the drug. The first compartmental model is used to characterise time-dependent drug concentrations in plasma and tissue following a customisable drug regimen. Outputs from this model provide boundary conditions for the second, spatio-temporal model of drug build-up in the skin. We focus on drugs that are highly bound as this will restrict their potential to move freely into the skin but which are lipophilic so that, in the unbound form, they would demonstrate an affinity to the outer layers of the skin. Buprenorphine, a drug used to treat opiate addiction, is one example of a drug satisfying these properties. In the discussion we highlight how our study might be used to inform future experimental design and data collection to provide relevant parameter estimates for reservoir formation and its potential to contribute to enhanced drug monitoring techniques. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to evaluate the forecasting performance of grey prediction models on educational attainment vis-à-vis that of exponential smoothing combined with multiple linear regression employed by the National Center for Education Statistics (NCES).Design/methodology/approach An out-of-sample forecasting experiment was carried out to compare the forecasting performances on educational attainments among GM(1,1), GM(1,1) rolling, FGM(1,1) derived from the grey system theory and exponential smoothing prediction combined with multivariate regression. The predictive power of each model was measured based on MAD, MAPE, RMSE and simple F-test of equal variance.Findings The forecasting efficiency evaluated by MAD, MAPE, RMSE and simple F-test of equal variance revealed that the GM(1,1) rolling model displays promise for use in forecasting educational attainment.Research limitations/implications Since the possible inadequacy of MAD, MAPE, RMSE and F-type test of equal variance was documented in the literature, further large-scale forecasting comparison studies may be done to test the prediction powers of grey prediction and its competing out-of-sample forecasts by other alternative measures of accuracy.Practical implications The findings of this study would be useful for NCES and professional forecasters who are expected to provide government authorities and education policy makers with accurate information for planning future policy directions and optimizing decision-making.Originality/value As a continuing effort to evaluate the forecasting efficiency of grey prediction models, the present study provided accumulated evidence for the predictive power of grey prediction on short-term forecasts of educational statistics. [ABSTRACT FROM AUTHOR]

We characterised the hydrodynamics of the two staggered swimming fish using vortex dynamic method. Based on the theoretical model, we showed that the horizontal spacing between the two fish plays a crucial role in affecting the fluid dynamics around two fish, while the vertical spacing between the two fish merely affects the value of propulsive force individually generated by the two fish. Furthermore, we revealed that there are two horizontal spacing thresholds for the holding and breaking of the spatial configurations of the two fish, indicating that two fish would swim at the stable status: the synchronous acceleration or deceleration. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to analyze the performance of LCLC resonant converter (RC) with proportional integral controller and fuzzy gain scheduled proportional integral controller.Design/methodology/approach The drawbacks of series RC and parallel resonant converter (PRC) are explained using relevant references in Section 1 of this paper. The necessity of RCs and the merits of zero voltage and zero current switching are given in the Section 2. In Section 3, the modeling of LCLC RC using state space technique is done. In Section 4, the open loop analysis and performance evaluation of proportional integral controller, fuzzy gain scheduled proportional controller using MATLAB Simulink is obtained. The hardware specification is given and experimental results are taken for LCLC RC. In Section 5, conclusion of study is given.Findings The LCLC RC overcomes the drawbacks of series and PRC. The fuzzy gain scheduled proportional integral controller is suitable for load variations in RC.Originality/value The output of the converter is not affected with the load variations since the controller suggested in the paper works for load changes and can be a solution for load parameter deviation applications. Also performance of the RC is improved by the fast response of the proposed controller. [ABSTRACT FROM AUTHOR]

Purpose Different from manufacturing resources allocation problems, the prices and amounts of limited public service resources could not be changed with the consumers’ requirements and social fairness is the most important objective for improving allocation efficiency. To measure social fairness reasonably, the purpose of this paper is fourfold: first, divide social fairness into longitudinal comparative fairness and crosswise comparative fairness, therefore providing their calculation formula and describing the comprehensive fair degree by using the interval numbers. Second, the comparison regulations of interval numbers are given and the corresponding features are also described. Third, an extension of VIKOR method is put forward for evaluating social fairness of different allocation alternatives with interval numbers. Finally, a numerical example illustrates the proposed method and clarifies the main results developed in the paper.Design/methodology/approach In this paper, the author depicts the social fair degree as an interval number, and thus proposes the comparison method between any two interval numbers. Based on the basis procedure of the VIKOR method, the paper proposes an extension of the fuzzy VIKOR method with the interval numbers to rank and select the compromise allocation alternatives. Finally, a numerical example illustrates the practicability of the proposed method.Findings The comparison of interval numbers is very important when the author evaluates the decision alternatives. Through analyzing the present comparison methods, the paper proposes the simple method of comparing the interval numbers, which can obtain the same results with the above two methods. The fuzzy VIKOR method, a popular multi-criteria decision-making method, focusses on ranking and selecting from a set of alternatives in a fuzzy environment. For the fuzzy value, the paper also proposes the extension of the VIKOR method to perform an evaluation and get the compromise alternatives.Originality/value According to the huge customers’ requirement, how to improve their social fair degree has become the focus in public service resources allocation, where the social fair degree may be a comprehensive concept which includes the fair degree compared with all the other allocation alternatives and the fair degree compared with the other small group under the same allocation alternative. In the paper, the author defines the above two types of fair degree and then depicts the comprehensive fair degree as their integration, which will be interval numbers. [ABSTRACT FROM AUTHOR]

Aurora B kinase is a protein that controls several processes in mitosis when it is found associated with INCENP, Survivin and Borealin in a complex known as the Chromosomal Passenger Complex. Aurora B in complex with INCENP is phosphorylated on three sites, resulting in the full activation of Aurora B. In prophase and metaphase, Aurora B is activated at centromeres, the region of chromatin linking sister chromatids, due to an autophosphorylation mechanism, and it has been hypothesised that Aurora B is activated throughout the cytoplasm due to its concentration at centromeres. In this article, we first develop a time-dependent model of Aurora B activation that does not incorporate spatial variation. This model is used to demonstrate the various qualitative behaviours that the activation of Aurora B is capable of displaying for different model parameters. Next, we develop a spatio-temporal model of Aurora B activation that includes diffusion of soluble Aurora B and binding of Aurora B to immobile centromeric binding sites. This model describes the activation of Aurora B throughout the cytoplasm due to its concentration-dependent activation at centromeres. The models demonstrate the effects that a soluble phosphatase concentration, multisite phosphorylation and diffusion have on the activation of Aurora B. [ABSTRACT FROM AUTHOR]

A mathematical model that describes the transmission dynamics of bovine tuberculosis (BTB) in both buffalo and cattle populations is proposed. The model incorporates cross-infection and contaminated environment transmission routes. A full analysis of the model is undertaken. The reproduction number of the entire model is comprised of cross-infection and contaminated parameters. This underscores the importance of including both cross-infection and contaminated environment transmission routes. Crucially our simulations suggest that the disease has a more devastating effect on cattle populations than on buffalo populations when all transmission routes are involved. This has important implications for agriculture and tourism. [ABSTRACT FROM AUTHOR]

Purpose – Since the construction of China-ASEAN Free Trade Area (CAFTA) launched in 2002, the bilateral trade increased rapidly. The purpose of this paper is to test the competition and cooperation in trade relationships between China and the main trading partners (Singapore, Malaysia and Thailand (SMT)) from ASEAN in international trade under CAFTA. Design/methodology/approach – Grey Lotka-Volterra competition models are established for testing the trade relationships between China and SMT, respectively, based on the data of import and export from 2003 to 2014. To improve modeling accuracy, the interpolated coefficients for dynamic background value are introduced into the grey Lotka-Volterra model. The optimal parameters are solved through minimizing the mean absolute percentage error and the constraint of parameter relationships. Besides, eigenvalues of the Jacobian matrix are adopted to carry out the stability of equilibrium points of the trade relationships. Findings – As the beneficiary party, China has mutual benefit and win-win trade relationship with Singapore, while it has predator-prey trade relationships with Malaysia and Thailand. The future exports from SMT to China will stabilize at 462.31, 598.13 and 447.03 billion dollars, respectively. The future exports from China to SMT will stabilize at 637.16, 943.71 and 827.52 billion dollars, respectively. Practical implications – This study can be regarded as an important reference for China and its trading partners from ASEAN. The modeling results can help the decision makers to formulate appropriate international trade strategies to gain and maintain competitive advantages. Originality/value – A new approach to testing the trade relationships is proposed based on grey Lotka-Volterra competition model. The study also proposed a dynamic optimization method for the background value of grey Lotka-Volterra model. [ABSTRACT FROM AUTHOR]

Purpose – Air traffic resources mainly include two parts, namely, air traffic controller (ATC) and physical system resources, such as airspace. Reasonable assessment and effective management of ATC and airspace resources are the premise and foundation of ensuring the safety and efficiency of air traffic management systems. The previous studies focussed on subjective workload control and the statistics of control communication time; they revealed the lack of kinetic universality analyses of controlling actions. Although frequency distribution patterns were generated by controlling the timing sequence, the correlation between the controlling actions and terminal airspace (TMA) sector capacity was not revealed. The paper aims to discuss these issues. Design/methodology/approach – Thus, given the immeasurable complexity of controlling actions and statistical features of the controlling communications, a dynamical model of ATC was built in this study to identify the frequency distribution patterns generated by controlling the timing sequence. With the Directorate of Operational and Analysis Task method, TMA sector capacity was estimated through multiple linear regression analysis. Findings – With data from the Kunming sector, the power exponent was calculated as 2.55, and the mathematical expectation was determined to be 47.21 s. The correlation between controlling actions (workload) and sector capacity was obtained. Finally, the data were integrated in the verification of the model and its feasibility. Originality/value – Airspace capacity is an index to measure the ability of the airspace system to deliver services to meet the air traffic demand. A scientific and accurate forecast of airspace capacity is a foundation of the effective management and rational allocation of the airspace resources. The study is of great significance for the efficient use of airspace resources, controller resources. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to investigate a competitive location problem to determine how to allocate a budget to expand company’s chain by either adding new facilities, expanding existing facilities, or a combination of both actions. Solving large problems may exceed the computational resources currently available. The authors treat a special case when the market can be divided into mutually exclusive sub-markets. These can be markets in cities around the globe or markets far enough from each other so that it can be assumed that customers in one market do not patronize retail facilities in another market, or that cross-patronizing is negligible. The company has a given budget to invest in these markets. Three objectives are considered: maximizing profit, maximizing return on investment (ROI), and maximizing profit subject to a minimum ROI. An illustrative example problem of 20 sub-markets with a total of 400 facilities, 4,800 potential locations for new facilities, and 5,000 demand points is optimally solved in less than two hours of computing time. Design/methodology/approach – Since the market can be partitioned into disjoint sub-markets, the profit at each market by investing any budget in this sub-market can be calculated. The best allocation of the budget among the sub-markets can be done by either solving an integer linear program or by dynamic programming. This way, intractabole large competitive location problems can be optimally solved. Findings – An illustrative example problem of 20 sub-markets with a total of 400 facilities, 4,800 potential locations for new facilities, and 5,000 demand points is optimally solved in less than two hours of computing time. Such a problem cannot be optimally solved by existing methods. Originality/value – This model is new and was not done in previous papers. [ABSTRACT FROM AUTHOR]

Purpose – Critical links in traffic networks are those who should be better protected because their removal has a significant impact on the whole network. So, the purpose of this paper is to identify the critical links of traffic networks. Design/methodology/approach – This paper proposes the definition of the critical link for an urban traffic network and establishes mathematical model for determining critical link considering the travellers’ heterogeneous risk-taking behavior. Moreover, in order to improve the computational efficiency, the impact area of a link is quantified, a partial network scan algorithm for identifying the critical link based on the impact area is put forward and the efficient paths-based assignment algorithm is adopted. Findings – The proposed algorithm can significantly reduce the search space for determining the most critical links in traffic network. Numerical results also demonstrate that the structure of efficient paths has significant impact on identifying the critical links. Originality/value – This paper identifies the critical links by using a bi-level programming approach and proposes a partial network scan algorithm for identifying critical links accounting for travellers’ heterogeneous risk-taking behavior. [ABSTRACT FROM AUTHOR]

Purpose – As far as the author knows the modeling of induction surface hardening is still a challenge. The purpose of this paper is to present both mathematical models of continuous and simultaneous hardening processes and exemplary results of computations and measurements. The upper critical temperature Ac3 is determined from the Time Temperature Austenization diagram for investigated steel. Design/methodology/approach – Computation of coupled electromagnetic, thermal and hardness fields is based on the finite element methods, while the hardness distribution is determined by means of experimental dependence derived from the continuous cooling temperature diagram for investigated steel. Findings – The presented results may be used as a theoretical background for design of inductor-sprayer systems in continual and simultaneous arrangements and a proper selection of their electromagnetic and thermal parameters. Research limitations/implications – The both models reached a quite good accuracy validated by the experiments. Next work in the field should be aimed at further improvement of numerical models in order to shorten the computation time. Practical implications – The results may be used for designing induction hardening systems and proper selection of field current and cooling parameters. Originality/value – Complete mathematical and numerical models for continuous and simultaneous surface induction hardening including dual frequency induction heating of gear wheels. Experimental validation of achieved results. Taking into account dependence of the upper critical temperature Ac3 on speed of heating. [ABSTRACT FROM AUTHOR]

Purpose – Overweight, obesity, and physical inactivity have in recent years become an important public health problem worldwide. Investigations that study obesity using a systemic approach in low- and middle-income countries (LMICs) are limited. Therefore, the purpose of this paper is to study the nutritional stages dynamics within the Colombian urban population. Design/methodology/approach – The authors used a population-level systems dynamics (SD) model that captures the transitions of population by body mass index (BMI) categories. The authors proposed a heuristic to estimate the transference rates (TRs) between BMI categories using data from the Colombian Demographic and Health Survey 2005 and 2010. Findings – The Colombian urban population is moving to overweight and obese categories. The TRs from not overweight to overweight and from overweight to obese (0.0076 and 0.0054, respectively) are higher than the TRs from obese to overweight and from overweight to not-overweight (1.025×10e−7 and 3.47×10e−7, respectively). The simulation results show that the prevalences of overweight and obesity will increase by 6.2 and 7.5 percent by 2015, and by 13.4 and 18.9 percent by 2030, respectively. Originality/value – Investigations that study obesity using a systemic approach in LMICs are limited. A SD model was proposed to examine changes in the population’s nutritional stages using population accumulation structures by BMI categories. The authors propose a heuristic to estimate the TRs of individuals between BMI categories. The proposed model can be used to study the effects of policy interventions to prevent overweight and obesity. The authors analyze a few policy intervention strategies. [ABSTRACT FROM AUTHOR]

The present study aims to provide a comprehensive mathematical model for drug release from microparticles to the adjacent tissues. In the elucidation of drug release mechanisms, the role of mathematical modelling has been depicted thereby facilitating the development of new therapeutic drug by a systematic approach, rather than expensive experimental trial-and-error methods. In order to study the whole process, a two-phase mathematical model describing the dynamics of drug transport in two coupled media is presented. Drug release is described taking into consideration both solubilisation dynamics of drug crystallites and diffusion of the solubilised drug through the microparticle. In the coupled media, reversible dissociation/recystallisation processes are taking place. The model has led to a system of partial differential equations that are solved analytically. The model points out the important roles played by the diffusion, mass-transfer and reaction parameters, which are the main architects behind drug kinetics across two layers. The dependence of drug masses on the main parameters is also analysed. [ABSTRACT FROM AUTHOR]

Purpose – The attractiveness of functionally graded composites lies in the possibility of a gradual spatial change of their properties such as hardness, strength and wear resistance. The purpose of this paper is to discuss the use of electromagnetic buoyancy to separate the reinforcement particles during the casting process of such a composite. Design/methodology/approach – The basic problem encountered in the process of casting composites is to obtain electromagnetic buoyancy and simultaneously to avoid a flow of the liquid metal which destroys the desired composite structure. In this paper the authors present the methodology of numerical optimization of inductor geometry in order to homogenize the electromagnetic force field distribution. Findings – The optimization method based on searching the solution subspace created by applying knowledge of the modelled process physics proved better than the universal local optimization methods. These results were probably caused by the complex shape of the criterion function hypersurface characterized by the presence of local minima. Practical implications – Due to their characteristics, functionally graded composites are of great interest to the automotive, aerospace and defense industries. In the case of metal matrix composites casting techniques (as the presented one) are the most effective methods of producing functionally graded materials. Originality/value – The paper presents the optimization of a new process of casting functionally graded composites in a low-frequency alternating electromagnetic field. The process involves problems that did not occur previously in the area of electromagnetic processing of materials. The paper proposes the use of special design of inductors to homogenize the electromagnetic force field. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the performance of generalized frequency division multiplexing (GFDM) in some frequency selective fading channels. The exact symbol error rate (SER) expressions in Hoyt (Nakagami-q) and Weibull-v fading channels are derived. A GFDM transceiver simulation test bed is provided to validate the obtained analytical expressions. Design/methodology/approach – Modern cellular system demands higher data rates, very low-latency transmissions and sensors with ultra low-power consumption. Current cellular systems of the fourth generation (4G) are not able to meet these emerging demands of future mobile communication systems. To address this requirement, GFDM, a novel multi-carrier modulation technique is proposed to satisfy the future needs of fifth generation technology. GFDM is a block-based transmission method where pulse shaping is applied circularly to individual subcarriers. Unlike traditional orthogonal frequency division multiplexing, GFDM transmits multiple symbols per subcarrier. The authors have used the probability density function approach in solving the final analytical expressions. Findings – Detailed analysis of GFDM performance under Hoyt-q, Weibull-v and Log-Normal Shadowing fading channels. Exact analytical formulae were derived which support the simulations carried out by authors and other authors. The exact dependence of SER on fading parameters and roll-off factor α in the raised cosine pulse shape filter was determined. Practical implications – Development and fabrication of high-performance GFDM systems under fading channel conditions. Originality/value – Theoretical support to simulated system performance. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to introduce signature analysis to humour research. Signature analysis is not widely used in the fields of humanities, the introduction of a new technique will invite comparison with the long standing factor analysis method. Design/methodology/approach – A signature presumes the existence of a model with ideal attributes for the purpose of identification. The model derived from types of humour which describe four types of age dependence. Age dependence contrast sharply with factor analysis which usually ignores age differences in humour. The signatures of four types of humour were calculated from the average scores of all line scores of each type. The Cramer-Rao Bounds were also calculated from the same groups, this defines the centre points and the limits of best type estimators. The age profiles of individual lines were plotted against their type signatures. The error distributions were plotted, with and without offset compensation. Findings – The error plot with offset compensation showed a spike close to the zero error, indicating the existence of significant matching between profiles and signature. Research limitations/implications – This is an exploratory analysis of responses from 277 participants in an online long survey. More participation is required/hoped for to confirm these findings. Practical implications – The graphical identification of context in sentences, humorous and non-humorous. Originality/value – Signature analysis is well known in the physical sciences, the author knows of no application in psychology or humour research. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to carry out an analytical approximation model (heat transfer model (HTM)) for the calculation of the heat transfer coefficient at the end winding bars of large hydro generators. These coefficients are needed for lumped parameter thermal models in the design process. Design/methodology/approach – The computational fluid dynamics simulation in combination with conjugate heat transfer (CHT) validates the accuracy of the HTM. The theoretical approach describes the formulation of the heat transfer coefficient and the Gauss-Newton method has been applied to find the coefficients of the approximation model. Findings – The paper describes the new analytical approximation model for the heat transfer coefficient at the end winding bars of hydro generators and shows also the validation to simulation results. Originality/value – The analytical approximation model for the heat transfer coefficient at the end winding bars has been described and a comparison with CHT results has shown a good agreement. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to present a new concept of a multi-module electromagnetic launcher with pneumatic assist. The authors focus on the problem of modelling a two-module electromagnetic launcher consisting of a coil-gun (module C) and a rail-gun (module R), as well as on the key problem of determining their position-dependent parameters, i.e. the resistances and inductances of discharging electrical circuits connected with the both modules. Special attention is paid to the possibility of influencing the missile’s flight via basic controller variation of the initial voltage values across the terminals of the capacitor batteries supplying current to both modules C and R. Design/methodology/approach – Analysis of the electromagnetic launcher has been based on the circuit-field approach. Differential equations describing movement of the missile have been drawn from circuit theory. The Finite Element Method and the Comsol Multiphysic program were used to determine position-dependent parameters in module C. It is worth emphasising that the effect of saturation (resulting from B-H curve for ferromagnetic part of the considered magnetic circuit) was taken into account. The influence of the initial missile speed adjusted in a pneumatic assist unit on the missile’s velocity was also considered and illustrated by appropriate simulations (the Matlab program). Findings – In analysing the flight of a missile along coil-gun and rail-gun modules, it is necessary to distinguish between three specific stages of the moveable element: the “fall in” stage, the “drive through” stage and the “fall out” stage. One of the most important findings is that during modelling, it is necessary to take into account of all the three above-mentioned stages of missile movement and, in particular, the “fall in” stage. It was shown both by computer simulations and laboratory investigations that this stage plays an important role in determining the time curves of decaying currents in discharging electrical circuits of both module C and module R. Research limitations/implications – The main difficulties are related to determining the influence of air drag force upon missile movement (especially in module C), as well as identifying an accurate value for contact resistances and friction force between the rails and the missile in module R. Practical implications – Hybrid construction employing propelling units of different characters should be treated as a promising and challenging trend in developing launcher structure. One of the most significant advantages of such a solution is the possibility of influencing missile velocity during its flight. Social implications – Since the first device was successfully completed in 1920 the continuous rise in the interest on electromagnetic launchers has been observed. As far as their social and technical impact is concerned, one of the most promising fields of interest seem to be launchers of satellites, high-pressure compressors, simulators modelling collisions between meteoroids and the surface of the earth and electromagnetic guns on board war ships. Originality/value – The novel concept in developing the construction of launchers presented in this paper has been to integrate propelling modules of different characteristics and to create a new multi-module constructional-compact whole. The designed and constructed prototype consists of three modules: a pneumatic drive unit and two electromagnetic drive units that have different principles of operation. The original methodology leading to the creation of its effective mathematical model (focusing on determination of position-depended parameters) was presented and verified in an experimental way. [ABSTRACT FROM AUTHOR]

Purpose -- The purpose of this paper is to provide a model for quantitatively analyzing the security profile of an organization's IT environment. The model considers the security risks associated with stored data, as well as services and devices that can act as channels for data leakages. The authors propose a sensitive information (SI) leakage vulnerability model. Design/methodology/approach -- Factors identified as having an impact on the security profile are identified, and scores are assigned based on detailed criteria. These scores are utilized by mathematical models that produce a vulnerability index, which indicates the overall security vulnerability of the organization. In this chapter, the authors verify the model result extracted from SI leakage vulnerability weak index by applying the proposed model to an actual incident that occurred in South Korea in January 2014. Findings -- The paper provides vulnerability result and vulnerability index. They are depends on SI state in information systems. Originality/value -- The authors identify and define four core variables related to SI leakage: SI, security policy, and leakage channel and value of SI. The authors simplify the SI leakage problem. The authors propose a SI leakage vulnerability model. [ABSTRACT FROM AUTHOR]

By treating HCV-infected injecting drug users (IDUs), we may prevent infections to other IDUs. Curing preferentially individuals who most often share injecting equipment has the advantage of preventing more infections. However, such high risk behavior IDUs are also more likely to become re-infected. We have created a model that can inform us about most efficient HCV treatment policy; the expected benefits per treatment of one HCV-infected IDU are calculated, defined as a decrease in the number of chronic HCV infections. This includes the probability that the cured IDU remains uninfected, and the number of new infections prevented both directly and indirectly in further infection generations. We explore analytically how these benefits depend on the syringe sharing frequency of the cured IDU. We find that whom to best cure is determined by the prevalence of HCV contamination among exchanged syringes within the IDU population. Treating lowest risk IDUs is most beneficial above a certain prevalence of contamination, since the term for re-infection dominates the equation in this domain. At lower prevalence treating highest risk IDUs is most beneficial, since here the term for prevention dominates. In a much simplified model the threshold between domains is found at exactly 50% HCV prevalence. The threshold value is lowered when taking HCV induced mortality or increased infectiousness during an acute stage of infection into account. It is increased when taking into account treatment duration, or when HCV-treatment is combined with intervention that reduces the syringe sharing rate of the cured IDU. [ABSTRACT FROM AUTHOR]

Drug-eluting stents have revolutionised the treatment of coronary artery disease. These small medical devices have attracted much interest over the past decade from biologists, clinicians, engineers and mathematicians alike. This article provides a comprehensive review of the modelling of drug release from arterial stents and the subsequent drug transport through arterial tissue, and acts as a useful reference equally for those who are already involved in drug-eluting stents research and for those who are starting out in the field. Assembled in this review are the main models of drug release and arterial drug transport that have been published in the literature to date. Many of the models presented in this paper have evolved from drug transport models in other applications. Furthermore, the ideas presented in this review may also be extended to other drug-delivery applications, such as drug coated balloons, transdermal patches and therapeutic contact lenses. [ABSTRACT FROM AUTHOR]

Purpose – The recent scientific observation that human information processing involves four independent data types, has pinpointed a source of fallacious arguments within many domains of human thought. The species-unique ability to assign observable characteristics to purely conceptual entities has created beautiful poetry and literature. However, this ability to generate “Semantic Intertwine” has also created the most incomprehensible paradoxes and conundrums. The paper aims to discuss these issues. Design/methodology/approach – Semantic Intertwine can be created between, or within, Semantic Categories; and in either case it then lies at the heart of fallacious, yet often very persuasive, reasoning. Findings – This paper describes how to detect mathematically related Semantic Intertwine in erroneous arguments involving: operands (VIII), mathematical induction (VIIA), orthogonal axiom sets (VIIB), continuous functions (VIIA), exclusive disjunction (VIIA), propositional calculus (VI) and the hitherto thorny problems arising from ambiguous intra-category use of “infinity” (VIIB). Originality/value – The applications of Semantic Category Analysis (SCA) are manifold. Determine the Semantic Categories involved in an argument and their modes of combination, and any Semantic Intertwine revealed pinpoints erroneous reasoning. SCA can be applied to any domain of human thought. [ABSTRACT FROM AUTHOR]

• We investigate a novel non-integer model of the circumscribed self-excited spherical strange attractor. • We consider the Caputo-Fabrizio derivative. • We provide the existence of the solution by the fixed-point theories. • We apply very effective numerical technique. • We demonstrate the numerical simulations. The purpose of this study is to present and examine a novel non-integer model of the circumscribed self-excited spherical strange attractor, which has not been worked yet. To design the fractional-order model, we use the Caputo-Fabrizio derivative. In order to ensure the existence of the solution Picard-Lindel and fixed-point theories are provided. Moreover, the stability of the considered fractional-order model is shown using the Picard iteration and fixed point theory approach. To get the approximate solutions of the proposed fractional model an efficient numerical scheme called the fractional Euler method(FEM) is used. To see the performance of the used method, the behavior of the numerical solutions of the model is examined under various initial conditions(ICs) and fractional orders. Considerable chaotic behaviors of the solutions are obtained which prove the accuracy and reliability of FEM. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study a novel grey possibility degree approach, which is combined with multi-attribute decision making (MADM) and applied MADM model for solving supplier selection problem under uncertainty information. Design/methodology/approach – The supplier selection problem is a typical MADM problem, in which information of a series of indexes should be aggregated. However, it is relatively easy for decision makers to define information in uncertainty, sometimes as a grey number, rather than a precise number. By transforming linguistic scale of rating supplier selection attributes into interval grey numbers, a novel grey MADM method is developed. Steps of proposed model were provided, and a novel grey possibility degree approach was proposed. Finally, a numerical example of supplier selection is utilized to demonstrate the proposed approach. Findings – The results show that the proposed approach could solve the uncertainty decision-making problem. A numerical example of supplier selection is utilized to demonstrate the proposed approach. The results show that the proposed method is useful to aggregate decision makers’ information so as to select the potential supplier. Practical implications – The approach constructed in the paper can be used to solving uncertainty decision-making problems that the certain value of the decision information could not collect while the interval value set could be defined. Obviously it can be utilized for other MADM problem. Originality/value – The paper succeeded in redefining interval grey number, constructing a novel interval grey number based MADM approach and providing the solution of the proposed approach. It is very useful to solving system forecasting problem and it contributed undoubtedly to improve grey decision-making models. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to consider the following problem; if the manager of the parallel network systems wants to add new sub-decision making units (sub-DMUs) to each parallel network system, he/she wants to know how much new fuzzy inputs allocate to new sub-DMUs and how much outputs these new sub-DMUs produce such that the efficiency of each parallel network system improve or preserve. Design/methodology/approach – Resource allocation and target setting is a famous topic in management science, therefore many managers attention to this field. Data envelopment analysis is one approach to apply the resource. Resource allocation and target setting is a famous topic in management science, therefore many managers attention to this field. Data envelopment analysis is one approach to apply the resource allocation and target setting. In real application the structure of many DMUs are network and the data of them are imprecise. In this work first the authors calculate the fuzzy efficiency of parallel systems by common set of weights method, after that the authors propose an approach to find how much fuzzy inputs allocate to new sub-DMUs, and how much new fuzzy outputs produce, where the efficiency of each parallel network system improve or preserve. Findings – It is found the value of inputs and outputs of new sub-DMUs, where the efficiency of each system not worse than before. Practical implications – The method can be used in many organizations such as banks, chain stores, car factory, etc. Originality/value – For the first time the authors allocate new sub-DMUs to each system, and the data of paper are fuzzy numbers. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to establish a novel conflict analysis model so that it can well describe and deal with the real conflict problems. Design/methodology/approach – In order to overcome the shortcomings that the agents have only three attitudes with respect to the conflict issues in Pawlak conflict information system, so that it is too stiff to describe and portray the real conflict problems, the thought and methodology of the intuitionistic fuzzy set is employed to soften the agents’ attitudes of the conflict issues, and then a novel conflict analysis model is constructed. This method, to begin with, the intuitionistic fuzzy number is used to express the opposition and support degree with respect to the conflict issues from agents, and then the similarity measure method is utilized to define conflict coefficient; what is more, the conflict degrees between any two agents can be obtained, and then the alliances are determined by setting different threshold values. Finally, an example illustrates the validity and rationality of the proposed method. Findings – The novel conflict analysis model proposed in the paper can well describe and resolve a real-life conflict problems such as the conflict of national territory, employee and employer. Research limitations/implications – The proposed model can only do with the conflict problems in which there do not exit the correlations among conflict issues, while it does not cope with the conflict problems with the mutually interrelated conflict issues. Originality/value – The paper succeeds in softening the Pawlak conflict analysis information system, and describing and dealing with the actual conflict problems. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to demonstrate that sufficiently general concept of information encompassing multi-disciplinary scientific conceptualizations of this term can be useful for a discussion of the long standing philosophical problems. Design/methodology/approach – The author is using his concepts of information and its integration along with their mathematical formalization introduced in earlier publications to describe what constitutes an object, its identity and state. The concept of information used here is defined in terms of the categorical opposition of the one-and-many which plays a central role in philosophical tradition. Its formalization is closely related to formalisms of many theories involved in scientific disciplines. These features produce a common stage for philosophical discourse and scientific analysis. Findings – The formalism based on author's concept of information opens philosophical concepts such as object, identity and state to analysis consistent with scientific methodology. The analysis, consistent with modern physical theories, such as quantum mechanics, permits resolution paradoxal aspects of object's identity for long time puzzling philosophers. Originality/value – The approach to information applied here was introduced in earlier publications, but the analysis of the problems of identity in this context is novel and unprecedented. The author hopes, that even those who prefer different conceptualizations of information can benefit from the present exposition of author's analysis by considering it an example of bridging philosophical and scientific discourse. [ABSTRACT FROM AUTHOR]