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Abstract: A wide range of mathematical models for multiple effect evaporators in process industry including paper industry are well reported in the literature but not so extensive work on the dynamic behavior of MEE system is available in the literature. In the present study dynamic behavior of multi-effect evaporator system of a paper industry is obtained by disturbing the feed flow rate, feed concentration, live steam temperature and feed temperature. For this purpose an unsteady-state model for the multi-effect evaporator system is developed. Each effect in the process is represented by a number of variables which are related by the energy and material balance equations for the feed, product and vapor flow. A generalized mathematical model which could be applied to any number of effects and all kinds of feeding arrangements like forward feed, backward feed, mixed feed and spilt feed in the MEE system with simple modifications was finally obtained. Finally model for mixed feed sextuple effect falling film evaporators system was solved using MATLAB. For the steady state and dynamic simulation the ‘fsolve’ and ‘ode45’ solvers in MATLAB source code is used respectively. [Copyright &y& Elsevier]

Abstract: A new two-dimensional network model is proposed as a micromechanics model to simulate paper’s failure process due to sequentially breakages of fibers and/or bonds. Paper is approximated as a network composed of fibers any two of which link to each other by their intersecting point, namely so-called bond. Fibers distribute along three particular directions, leading to network’s macro-level isotropy. In the framework of finite element method, nodes correspond to fiber-to-fiber bonds, while elements are fiber segments between every two neighboring nodes and described by Timoshenko beam theory. Element breaks when its equivalent internal tensile stress reaches the tensile strength of fiber. Strength of nodes, i.e. fiber-to-fiber bonds is assumed to be dependant on shearing interaction between fibers, considering the dominant interaction is shearing in a plane problem. Numerical examples show the model’s capacity of reflecting basic failure characteristic in paper. Influences of fiber length and the ratio of fiber strength to bond strength are analyzed in detail. [ABSTRACT FROM AUTHOR]

Paper is a stochastic network of fibres, water and additives, and in that sense it may be envisaged as a composite material. Since fibres are much longer than the thickness of the paper sheet, the network is planar and almost two-dimensional. The two-dimensional structure governs many paper properties but the three-dimensional porous structure is also important. Insight into the structural changes that take place when paper is compressed in the paper machine may be gained by modelling and simulation of its viscoelastoplastic behaviour. The present work describes a mathematical model based on the cellular solids theory, characterising the nonlinear rheologic behaviour of the material. This approach results in an unsteady state problem and the resulting set of ODEs is solved by means of the DLSODES subroutine, which uses an integrator based in the Gear method. Experiments were conducted on a laboratory-scale dynamic press in order to validate the mechanical model. [Copyright &y& Elsevier]

Abstract: This paper deals with a perfectly continuously monitored system which gradually and stochastically deteriorates. The system is renewed by a delayed maintenance operation, which is triggered when the measured deterioration level exceeds an alarm threshold. A mathematical model is developed to study the asymptotic behavior of the reliability function. A procedure is proposed which allows us to identify the asymptotic failure rate of the maintained system. Numerical experiments illustrate the efficiency of the proposed procedure and emphasize the relevance of the asymptotic failure rate as an interesting indicator for the evaluation of the control-limit preventive replacement policy. [Copyright &y& Elsevier]

Abstract: We prove a theorem for the existence of solutions to a variational problem, under assumptions that do not require the convexity of the integrand. [Copyright &y& Elsevier]

Abstract: In this paper we describe electrophoresis of charged particles in a thin layer of a nonpolar liquid between two insulating substrates because this configuration is common in recently developed in-plane electronic paper. In the in-plane electrophoresis experiments a model system of charged inverse micelles in dodecane has been used which is well understood from studies of out-of-plane electrophoresis. The transient current due to drift and diffusion of charged inverse micelles is measured in thin in-plane devices upon application of a voltage step. For the modelling of the transient dynamics of charged inverse micelles without chemical reactions or convection a 1-dimensional approximation of the Poisson–Nernst–Planck (PNP) equations is developed. This approximation is valid for a sufficiently thin in-plane device and allows much faster calculations. Firstly, it is verified in the case of a sufficiently thin in-plane device and high applied voltage that the 1-dimensional approximation is in good agreement with the solution of the full 2-dimensional PNP equations with finite elements implementation. Then, the 1-dimensional approximation is used to study the transient current and trajectories of trace amounts of charged colloidal particles in different regimes depending on the screening of the electric field. Also a comparison is made to the well-studied case of out-of-plane electrophoresis. Finally, it is verified that for voltages much larger than the thermal voltage the experimental results are in good agreement with the 1-dimensional approximation, indicating that the charge transport dynamics of charged inverse micelles in the bulk are described well by the model. [Copyright &y& Elsevier]

Abstract: Some of the limitations of the model recently used by Nicoleau in a recent article [Accelerated growth of calcium silicate hydrates: experiments and simulations, Cement Concr. Res. 21 (2011) 1339 -1348.] are discussed. [Copyright &y& Elsevier]

This paper describes an accurate model of the Electrical Power Subsystem (EPS) of the Thermal Analysis Support and Environment Characterization Laboratory (TASEC-Lab), a university experiment developed for using in high-altitude balloon missions to measure and analyze the convection heat transfer. A Li-ion battery and two high efficient DC–DC converters have been characterized through laboratory tests and fitting to the experimental results. The developed mathematical models described in this paper are used to carry out accurate EPS simulations and are validated by comparison with the experimental data. • Design and modeling of the electrical power subsystem of a stratospheric balloon experiment. • New Li-lion battery discharging model that describes the three main parts: initial decay, linear, and exponential decay. • Formulation of a new DC/DC converter efficiency model. • Simulation and model validation of the electrical power subsystem. [ABSTRACT FROM AUTHOR]

Abstract: This paper concerns the modelling of an accumulator used in industrial elastic web processing plant such as paper mills, fabric, rolling mills etc. Accumulators are used to allow rewind or unwind core changes while the process continues at a constant web velocity. A new nonlinear model of a pneumatic actuated industrial accumulator including pneumatic jack model, static friction representation and web weight is first detailed which enables to deduce a linear model. These models are derived from physical laws that describe web tension and velocity dynamics in each web span. In a second part, the effects of time-varying mechanical parameters, such as web Young modulus, web length and rollers inertia on accumulator dynamics are presented. The performances of the modeled accumulator are illustrated by simulations in Matlab/Simulink software environment. [Copyright &y& Elsevier]

In this paper, we address modelling and simulation of dynamics involved in docking of large marine vessels with aid of tugboats, with the aim of providing a tool for improved design of control algorithms for autonomous docking operations. Mathematical models of the docking vessel and tugboats in 3DOF are derived, with a special focus on realistic interactions through towline, contact and friction forces with stick–slip dynamics and time delays, which are typically not considered in previous publications on the topic. We also present the implementation of the developed models in the first step towards a Simulink simulator in which considers the special case of tugboat-assisted docking operations in the Narvik harbour. The developed simulator is available on GitHub (see Ørke et al. (2023)) and encompasses model dynamics, tugboat control and vessel control and guidance, although the scope of this paper is model dynamics. We present simulation results that show that we are indeed able to capture interaction dynamics in a realistic way. Finally, we include a discussion of our results and some ideas for further development, as well as some concluding remarks. [Display omitted] • Mathematical modelling of docking vessel and tugboats in 3DOF. • Modelling of interaction forces in pushing/pulling operations. • Model implementation in Simulink-developed simulator. • Simulation and discussion of interaction forces, and ideas for future work. [ABSTRACT FROM AUTHOR]

The use of Phase Change Materials (PCM) in different building applications is a hot topic in today's R&D activities. Numerical simulations of PCM-based components are often used both for research activities and as a design tool, although present-day codes for building performance simulation (BPS) present some shortcomings that limit their reliability. One of these limitations is the limited possibility of replicating the effects given by thermal hysteresis – a characteristic of several PCMs. In this paper, an original algorithm that allows hysteresis effects to be accounted for is described and the results from simulations are compared against experimental data. The algorithm is implemented in EnergyPlus™ and makes use of the Energy Management System (EMS) group, one of the high-level control methods available in EnergyPlus™. The algorithm enables the replication of PCM's different heating/cooling enthalpy curves in this BPS tool, which just recently was equipped with an integrated module for the replication of the effects of thermal hysteresis. A comparison between numerical results from the proposed model and from other methods implemented in BPS tools, and the experimental data provided, shows the impact of the algorithm in the simulation of heat transfer in a PCM layer intent for opaque walls. In general, it is shown that the proposed method presents a better agreement with experimental data than alternative modelling approaches, but it is also seen that all the tested numerical models are not fully able to replicating the behaviour of PCM layers if the PCM does not melt or resolidify completely (i.e. it remains in the phase change) during the charge/discharge cycle. A local sensitivity analysis complements this study and highlights the most relevant parameters that influence the results of a simulation carried out with the proposed model. Finally, the paper hypothesises that the general discrepancy between simulations and experimental data seen in the case of incomplete melting of the PCM layer can be due to unsuitable data for the thermophysical behaviour of the PCM, which are obtained through conventional characterisation procedures far from the physics of the PCM layer when in real building structures. [ABSTRACT FROM AUTHOR]

The numerical modelling of the internal heat generation in passenger vehicle tyres using finite element analysis is a well-known numerical approach. However, this application is rather uncommon for earthmover tyres. This paper describes the development of a finite element model of a 23.5R25 earthmover tyre for the numerical modelling of the temperature distribution in the tyre cross-section at steady-state heat transfer conditions using an uncoupled analysis procedure. Considering the non-linear behaviour of the rubber compounds used for the manufacturing of these tyres, as well as the complexity associated with the composite structural aspects of the tyre, the material properties used for the proposed numerical model were established experimentally. In the analyses completed, the tyre behaviour was studied by simulations at various inflation pressures, loads and rolling velocities. The numerical tyre defection was within an 8% deviation from the actual tyre behaviour. Thermal simulation results were used to derive an equation that can be used to predict the maximum temperature that would occur in the tyre’s cross-section as a function of its vertical deflection, its forward rolling velocity and the ambient temperature of the surroundings. The numerical models and simulations presented in this paper were completed using MSC.Marc/Mentat. [ABSTRACT FROM AUTHOR]

This paper presents a review of the design parameters, mathematical techniques and simulations used in the design of parabolic trough solar systems, along with a review on their applications. Recent studies that analyze the deployment of solar parabolic trough collectors (SPTC) in different countries and the operational SPTC plants are also presented and discussed. The paper also discusses the different kinds of software and test methods of solar collectors developed since 1981 which can be distinguished by their particular mathematical models or tracking techniques. In particular, since the mathematical models are especially required for the design, analysis, testing and validation of the systems results as they provide an approximation of the dynamic behavior of the physical properties of the system, they are discussed in depth. The mathematical models allow the calculation of different parameters of the solar parabolic trough system, the angle of inclination of the collecting surface and the forces acting on the system. The validity and experimental validation of the major mathematical models on practical solar parabolic trough concentrators, receivers and other components of different dimension are also reviewed. The paper showed the optical efficiency values are close to 63% and the theoretical peak optical efficiency reached 75%. [ABSTRACT FROM AUTHOR]

This paper addresses a multi-stage inventory model that allows different order quantities among the selected suppliers to obtain the optimal solutions. To achieve the objective of the study, the single-objective and multi-objective methods are adopted for suitable real-world applications. With respect to a single-objective method, this paper aims to minimize the total ordering costs, holding costs, and purchasing costs, subject to the price, quality, and capacity. With respect to a multi-objective method, it focuses on cost minimization, as well as quality and capacity maximization. The proposed model not only considers the allocation of different order quantities among the selected suppliers, but also incorporates the multi-stage inventory problem. Furthermore, a numerical example is provided to illustrate the usefulness of the proposed model and a comparative understanding of various methods. In addition, a simulation test is performed to effectively validate the proposed model which outperforms the previous works. Finally, a sensitivity analysis is carried out to investigate the impact of supply chain cost. [ABSTRACT FROM AUTHOR]

Pulsed water jets have been widely applied in the field of underground mining because of their unique advantages. Revealing the mechanical mechanism of rock breaking under a pulsed water jet is significant in advancing the application of pulsed water jets in the rock crushing process. Based on continuum mechanics and interpolation theory, this paper establishes a numerical model to simulate the propagation of stress waves in rock by adopting the method of smooth particle hydrodynamics (SPH). According to the simulation results, this paper presents a quantitative approach to schematize the propagation of stress waves in the time-space dimension. The waveforms of stress waves in the selected path and the effective stress history of test particles are obtained to quantitatively describe the propagation of stress waves. Relying on the approach, the effects of jet velocity and rock properties on the propagation of stress waves are investigated. The results show that in the rock model, the influence area, propagation speed and attenuation rate of the stress wave all increase with increasing jet velocity. Moreover, the mean effective stress of a test particle in the numerical model increases with increasing jet velocity. Of the rocks considered in this paper, granite shows the greatest mean effective stress acting on the test particle, propagation speed, and attenuation rate of the stress wave. [ABSTRACT FROM AUTHOR]

The understanding, modelling and analysis of the behaviour of a non-linear ship propulsion plant are of great importance for conceptual system design, component selection, selection of control strategy and for propulsion control system tuning. Conceptual propulsion system design activities, such as deciding the combinator curve, require a relatively simple steady state simulation model, while propulsion controller design and tuning requires a non-linear time domain simulation model which captures the intricacies of the propulsion plant. In this paper a linearised model of the uncontrolled ship propulsion system is derived which can be used for analysis of propulsion system behaviour in waves and for initial controller design and tuning. Furthermore a thorough analysis is made of the conditions under which local instability of the system can occur. In a follow up paper the linearised model is extended and verified by means of comparison with a non-linear model. There it is furthermore used to investigate the effect of engine governor settings on a propulsion plant when sailing in waves at different encounter frequencies. The authors believe that, due to its transparency and clear link to well known parameters and variables, the linearised core propulsion system model as derived in this paper should appeal to marine system engineers, control engineers and hydrodynamicists alike. The linearised model should however not be seen as the replacement for a non-linear model, but rather as an additional tool that can be used. [ABSTRACT FROM AUTHOR]

Design and optimization of propulsion control strategies is a crucial part of ship design. In fact, propulsion plant behaviour is greatly influenced by the control system dynamics. Acceleration, deceleration, crash stop, heavy turning are some examples of transient conditions that a propulsion plant has to sustain whilst maintaining optimal performance without reducing ship safety and reliability. In this paper, the methodology and the simulation models needed to design the propulsion control logics for an innovative CODLAG propulsion plant are discussed. The methodology is based on the RT-HIL already used by the authors in a previous naval ship project and consists in the development of the propulsion control logics in a virtual environment. In order to increase the reliability of the results new and more detailed ship simulation models have been developed and their validation discussed in the paper. Thanks to this methodology, it is possible to test the control system under different operational conditions off-line, ashore in the office, without any hazards for the real system. The overall design time is reduced and this allows reduction in the time and the related cost of the sea trials for the final commissioning. At the end of this paper, sea trials results are shown to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper we present a multiphysics simulation model of Halcyon, an autonomous unmanned surface vehicle (USV). The simulation model presented in this paper has been developed to rapidly progress the design, development and validation of Halcyon’s autonomy management system, particularly in challenging sea conditions. Using simulation for this purpose enables extensive testing across the full environmental operating envelope of the vessel, hence greatly reducing the need for real-world sea-trials. The simulator is comprised of a novel and comprehensive sea-surface wave environment model, a six degree of freedom nonlinear unified seakeeping and manoeuvring boat dynamics model, an actuation dynamics model, an autopilot and an interface with an autonomy management system. Results are presented that show good agreement between real-world and simulated sea-trials data. [ABSTRACT FROM AUTHOR]

This paper proposes a new ranking algorithm based on comprehensive weighted clique degree (CWCDR) for ranking importance of nodes in complex network. Simulation results show that CWCDR algorithm can overcome the limitation of degree ranking algorithm and find important nodes in complex networks more precisely and effectively. To the shortage of small-world model and BA model, this paper proposes an evolutionary model of complex network based on CWCDR algorithms, named CWCDR model. Simulation results show that the CWCDR model accords with power-law distribution. Compared with BA model, this model has better average shortest path length and clustering coefficient. Therefore, the CWCDR model is more consistent with the real network. [ABSTRACT FROM AUTHOR]

This paper is the part of research aimed at creating robotic manipulator controlled by means of Brain-Computer Interface for improving household self-reliance of persons with disabilities and expanding the scope of their activity. The robotic manipulator gives possibility of self-fulfillment in basic household functions, s.a. drinking, eating, facial hygiene. The paper presents a mathematical model of the kinematics of the robotic manipulator. The solution of the forward and inverse kinematics problems based on the geometric method are given and obtained in MATLAB for the 5DOF manipulator. [ABSTRACT FROM AUTHOR]

In the present investigation, a non-linear mathematical model is developed for the analysis of Septuple effect flat falling film evaporator (SEFFFE) system used for concentrating black liquor in a nearby paper mill. This model is capable of simulating process of evaporation considering variations in boiling point rise (τ), overall heat transfer coefficient (U), heat loss (Q loss), flow sequences, liquor/steam splitting, feed, product and condensate flashing, vapor bleeding and physico-thermal properties of the liquor. Based on mass and energy balance around an effect a cubic polynomial is developed and solved repeatedly in a predetermined sequence using generalized cascade algorithm. For development of empirical correlations for τ, U and Q loss, plant data have been collected from SEFFFE system. These correlations compute τ, U and Q loss within average absolute errors of 2.4%, 10% and 33%, respectively, when their results are compared with the plant data. [Copyright &y& Elsevier]

This paper considers the design of an input signal for minimizing the time and energy required to detect and isolate faults in the outputs of a system. Faults are represented by discrete switches between affine models with bounded disturbances and bounded measurement errors. Within this framework, previous work has demonstrated that a minimally harmful input guaranteeing fault diagnosis can be obtained by solving a Mixed Integer Quadratic Program (MIQP). A closed-loop approach allows to reduce the length and/or norm of this input by solving an MIQP at each time instant with the newly available measurements. However, solving such programs online can be computationally demanding. In this paper, we employ multi-parametric (mp) programming to move most of the computation offline, thus allowing the application of the closed-loop approach to fast processes. Still, the mp-MIQP complexity becomes quickly prohibitive as the number of faulty models increases. In order to overcome this problem, we propose a strategy based on mp-optimization and graph theory that takes into account only two models at a time. While this approach is suboptimal compared to the case in which all the models are considered simultaneously, simulations show that, in practice, the performance is comparable. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to propose an avian eye-inspired visual attention approach for unmanned air vehicles (UAV), with the objective of improving the capability of UAV target detection. A visual attention model inspired by the functional architecture of the avian visual system is proposed in this paper. The neuro memetic model employs multiple contrast features as primary channels inspired by the contrast sensitivity of avian retina. The global context strategy is also adopted for focus attention based on the visual mechanisms of tectofugal pathway of avian cortex. Our approach is evaluated through quantitative simulations in various environments. Experimental results demonstrated the feasibility and effectiveness of the proposed method: The proposed method is capable to guarantee efficiency of target localization in the complex environment. [ABSTRACT FROM AUTHOR]

In many transformer applications, it is necessary to have a core magnetization model that takes into account both magnetic and electrical effects. This becomes particularly important in three-phase transformers, where the zero-sequence impedance is generally high, and therefore affects the magnetization very strongly. In this paper, we demonstrate a time-step topological simulation method that uses a lumped-element approach to accurately model both the electrical and magnetic circuits. The simulation method is independent of the used hysteresis model. In this paper, a hysteresis model based on the first-order reversal-curve has been used. [ABSTRACT FROM AUTHOR]

The universe can be utilized as a sink for heat pumping by means of passive radiative cooling (PRC). This approach is an age-old cooling practice that has had a renaissance with increasing numbers of research papers over the past two decades. This paper reviews the trends of this technique, as well as advancements in recent years, with an attempt being made to analyze the cooling magnitude and developmental prospects for both diurnal and nocturnal periods. The models and calculations for computing the performances of passive radiative cooling systems are discussed along with the designs and fabrication factors that influence a system's performance. Optimizing strategies that maximize the net cooling power are also presented. The various system configurations that are available to date are summarized to demonstrate the building integration forms of PRC systems. The cooling potentials of different systems are assessed by simulations, and it is shown that the daytime cooling energy density is rather modest, even under the most favorable conditions. The barriers that likely exist to widespread application as well as the scopes for further improvements of PRC are also provided. It is noted that the commercialization of PRC systems is primarily limited by coating material constraints and technique reliability. The advent of a new type of material will be a critical solution to the prevalence of PRC. [ABSTRACT FROM AUTHOR]

• The rock failure volume model under particle jet impact is put forward and established. • Damage evolution and failure volume under particle jet impact are dynamically simulated and analyzed. • The correctness and applicability of mathematical model were verified by comparative analysis with experiment and simulation. There are some difficult problems in deep and ultra-deep oil and natural gas drilling process due to the complex stress environment and hard formation, such as slow drilling speed, well deviation and high cost. As one of the important parameters to measure rock-breaking efficiency, mathematical model of failure volume is proposed in this paper, which is suitable for deep-well rock-breaking technology. First, the particle jet impact rock-breaking laboratory experiment was conducted based on the self-developed experimental platform, and the strength of rock specimen was tested. Then, the failure volume model of particle jet impact rock-breaking which varied with particle size, and water-jet velocity was established based on contact mechanics. Meanwhile, the simulation model and method of particle jet impact rock was carried out and introduced, and damage evolution was dynamical simulated. Comparative analysis of experiment results, model calculation and dynamic simulation was used to analyze the failure volume, and it showed, failure volume would increase linearly with increase of water-jet velocity, while particle size has little effect on failure volume under the condition of constant nozzle diameter. The comparison results of theoretical modeling and rock-breaking experiment are basically consistent, which proves the correctness and applicability of failure volume model. [ABSTRACT FROM AUTHOR]

In this paper, linear parameter-varying (LPV) control is considered for a solution copolymerization reactor, which takes into account the time-varying nature of the parameters of the process. The nonlinear model of the process is first converted to an exact LPV model representation in the state-space form that has a large number of scheduling variables and hence is not appropriate for control design purposes due to the complexity of the LPV control synthesis problem. To reduce such complexity, two approaches are proposed in this paper. First, an approximate LPV representation with only one scheduling variable is obtained by means of a parameter set mapping (PSM). The second approach is based on reformulating the nonlinear model so that it provides an LPV model with a fewer number of scheduling parameters but preserves the same input–output behavior. Moreover, in the implementation of the LPV controllers synthesized with the derived models, the unmeasurable scheduling variables are estimated by an extended Kalman filter. Simulation results using the nonlinear model of the copolymerization reactor are provided in order to illustrate the performance of the proposed controllers in reducing the convergence time and the control effort. [ABSTRACT FROM AUTHOR]

The exploration problem has been extensively studied in unsafe networks containing malicious hosts of a highly harmful nature, called black holes , which completely destroy mobile agents that visit them. In a recent work, Královič and Miklík (SIROCCO 2010, LNCS 6058, pp. 157–167) [20] considered various types of malicious host behavior in the context of the Periodic Data Retrieval problem in asynchronous ring networks with exactly one malicious host. In this problem, a team of initially co-located agents must report data from all safe nodes of the network to the homebase, infinitely often. The malicious host can choose whether to kill visiting agents or allow them to pass through (gray hole). In another variation of the model, the malicious host can, in addition, alter its whiteboard contents in order to deceive visiting agents. The goal is to design a protocol for Periodic Data Retrieval using as few agents as possible. In this paper, we present the first nontrivial lower bounds on the number of agents for Periodic Data Retrieval in asynchronous ring networks. Specifically, we show that at least 4 agents are needed when the malicious host is a gray hole, and at least 5 agents are needed when the malicious host whiteboard is unreliable. This improves the previous lower bound of 3 in both cases and answers an open question posed in the aforementioned paper. On the positive side, we propose an optimal protocol for Periodic Data Retrieval in asynchronous rings with a gray hole, which solves the problem with only 4 agents. This improves the previous upper bound of 9 agents and settles the question of the optimal number of agents in the gray-hole case. Finally, we propose a protocol with 7 agents when the whiteboard of the malicious host is unreliable, significantly improving the previously known upper bound of 27 agents. Along the way, we set forth a detailed framework for studying networks with malicious hosts of varying capabilities. [ABSTRACT FROM AUTHOR]

In order to relieve the influence of wind power uncertainty on power system operation, demand response and robust stochastic theory are introduced to build a stochastic scheduling optimization model. Firstly, this paper presents a simulation method for wind power considering external environment based on Brownian motion theory. Secondly, price-based demand response and incentive-based demand response are introduced to build demand response model. Thirdly, the paper constructs the demand response revenue functions for electric vehicle customers, business customers, industry customers and residential customers. Furthermore, robust stochastic optimization theory is introduced to build a wind power consumption stochastic optimization model. Finally, simulation analysis is taken in the IEEE 36 nodes 10 units system connected with 650 MW wind farms. The results show the robust stochastic optimization theory is better to overcome wind power uncertainty. Demand response can improve system wind power consumption capability. Besides, price-based demand response could transform customers’ load demand distribution, but its load curtailment capacity is not as obvious as incentive-based demand response. Since price-based demand response cannot transfer customer’s load demand as the same as incentive-based demand response, the comprehensive optimization effect will reach best when incentive-based demand response and price-based demand response are both introduced. [ABSTRACT FROM AUTHOR]

This paper reviews key issues in the physical and numerical modelling of marine renewable energy systems, including wave energy devices, current turbines, and offshore wind turbines. The paper starts with an overview of the types of devices considered, and introduces some key studies in marine renewable energy modelling research. The development of new International Towing Tank Conference (ITTC) guidelines for model testing these devices is placed in the context of guidelines developed or under development by other international bodies as well as via research projects. Some particular challenges are introduced in the experimental and numerical modelling and testing of these devices, including the simulation of Power-Take-Off systems (PTOs) for physical models of all devices, approaches for numerical modelling of devices, and the correct modelling of wind load on offshore wind turbines. Finally, issues related to the uncertainty in performance prediction from model test results are discussed.The paper is based on the report of the International Towing Tank Conference specialist committee on Hydrodynamic Modelling of Marine Renewable Energy Devices to the 27th ITTC held in Copenhagen, Denmark in 2014 (ITTC Specialist Committee on Hydrodynamic Modelling of Marine Renewable Energy Devices, 2014a. Final Report and Recommendations to the 27th ITTC Proc. 27th International Towing Tank Conference, Copehagen, Denmark, vol. 2, pp. 680–725). [ABSTRACT FROM AUTHOR]

The paper focuses on sensitivity analysis achieved on a mathematical model for system reliability assessment: the aim of this study is to assess propagation and quantification of uncertainty from input (e.g. nominal values of failure rates taken from a generic database) to output (e.g. system reliability). Many sources of uncertainty affect input data so a limit in the confidence on the response of the model is considered. After the definition of the variability range of possible input and its associated distribution, Monte Carlo simulation is used to have a wide sample of survey. In this paper sensitivity analysis is achieved on reliability outcomes of a generic SIS ( Safety Instrumented System ) constituted by sensors, logic solver and final elements; SIS is used to implement one or more safety functions to control critical processes on plants in order to avoid unacceptable or dangerous conditions. The results obtained with MC simulation and the following sensitivity analysis prove the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

Application of deaerators in ship has been restricted due to space limitation. Thus far, the function of deaerator has been integrated into the hot well of the condenser. The condensate water would be heated to saturation by extracting steam from turbine, which would make the solubility of Oxygen in condensate water fall to zero according to Henry’s law and Dalton’s law. The purpose of this paper was to build a mathematical model of bubbling hot well deaerator in the condensers of ships. In this paper, the heat exchange rate was calculated by empirical formulas which took the specific structure and process of heat exchange into account. When the operating conditions were in the application ranges of the empirical formulas, the simulation model would be performed by utilizing them; otherwise, calculations would be done by the conservation of energy, which assured the simulation model could be used at any operating condition. Different from previous works, the solubility of Oxygen in heated condensate water could be calculated by an empirical formula. The simulation results showed that the structure and heat exchange process considered could be highly accurate at the steady-state operations, and the main parameters trend curves during dynamic-state operations were consistent with theoretical analysis. The solubility of Oxygen could be calculated and the simulation results at the steady-state operations were verified against the practical situation, the trend curves during dynamic-state operations were consistent with theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper details the fatigue life prediction model for welding components based on hybrid intelligent technology. We make use of the capabilities and advantages of rough set theory, particle swarm optimization (PSO) algorithm and BP neural network for establishing of the fatigue life prediction model. Firstly, rough set theory was used to deal with the original fatigue sample data; the minimum fatigue feature subset was obtained. Secondly, improved PSO algorithm was used to optimize the initial weighs and thresholds of the BP neural network, which resolves such problems as local extremum and slow convergence that exist in the traditional BP neural network. At last, minimum reduced subset was inputted into the optimized BP neural network to construct the novel fatigue life prediction model for welding components by the continuous training and adjusting. Sample data of the titanium alloy welded joints was used to verify the correctness and validity of the novel fatigue life prediction model, simulation results show that the fatigue life prediction model proposed in this paper has better fault tolerance, higher precision, and can fitting fatigue life value more accurately than traditional BP model. Consequently, the model based on hybrid intelligent technology can provide an effective new approach to predict the fatigue life of welded joints. [ABSTRACT FROM AUTHOR]

This paper develops an analytical method to measure the performance of a multi-product unreliable production line with finite buffers between workstations. The performance measure used in this paper is Total Cycle Time. The proposed method is an approximation that generalizes the processing times to ease the variation of product types in a multi-product system. A decomposition method is then employed to approximate the production rate of a multi-product production line. The decomposition method considers generally distributed processing times as well as random failure and repair. A GI/G/1/N queuing model is also applied to obtain parameters such as blocking and starvation probabilities that are needed for the approximation procedure. Several numerical experiments under different scenarios are performed and results are validated by simulation models in order to assess the accuracy and strength of the proposed method. Consequent analysis and discussion of the results are also presented. [ABSTRACT FROM AUTHOR]

This paper describes simulation model of real network with various neutral earthing methods when a single pole earth fault occurs. Model was made using Matlab. The aim of the paper is to analyse values of the currents and of the temporary overvoltages with power frequency in case of a single pole earth fault. The currents of single phase to ground faults depend (along with the neutral earthing method) mostly on the earth capacitances of the overhead lines or cables connected to the network. A comparison of the network with a large number of long cables and network with mostly overhead lines was made with the purpose to determine their influence. With the intention to control results given by simulation models the mathematical model was created as well. The comparison of the simulation model results and calculated values show match. Simulation models are powerfull analysis tools used to validate different solutions of neutral point earthing. [ABSTRACT FROM AUTHOR]

Abstract: Multiagent-based simulations enable us to validate different use-case scenarios in a lot of application domains. The idea is to develop a realistic virtual environment to test particular domain-specific procedures. This paper presents a multilevel model of a physic environment for the simulation of crowd in a virtual 3D building. The major contributions of this paper is the agentification of the model to support multilevel simulation of the environment. Finally, the application of the model inside an airport terminal is presented. [Copyright &y& Elsevier]

In one-way quantum computation (1WQC) model, universal quantum computations are performed using measurements to designated qubits in a highly entangled state. The choices of bases for these measurements as well as the structure of the entanglements specify a quantum algorithm. As scalable and reliable quantum computers have not been implemented yet, quantum computation simulators are the only widely available tools to design and test quantum algorithms. However, simulating the quantum computations on a standard classical computer in most cases requires exponential memory and time. In this paper, a general direct simulator for 1WQC, called OWQS, is presented. Some techniques such as qubit elimination, pattern reordering and implicit simulation of actions are used to considerably reduce the time and memory needed for the simulations. Moreover, our simulator is adjusted to simulate the measurement patterns with a generalized flow without calculating the measurement probabilities which is called extended one-way quantum computation simulator (EOWQS). Experimental results validate the feasibility of the proposed simulators and that OWQS and EOWQS are faster as compared with the well-known quantum circuit simulators, i.e., QuIDDPro and libquantum for simulating 1WQC model. (This paper is an extended version of the paper presented at Euromicro DSD conference (Nikahd et al., 2012) [1].) [ABSTRACT FROM AUTHOR]

Usually, the geometry of the manufactured product inherently varies from the nominal geometry. This may negatively affect the product functions and properties (such as quality and reliability), as well as the assemblability of the single components. In order to avoid this, the geometric variation of these component surfaces and associated geometry elements (like hole axes) are restricted by tolerances. Since tighter tolerances lead to significant higher manufacturing costs, tolerances should be specified carefully. Therefore, the impact of deviating component surfaces on functions, properties and assemblability of the product has to be analyzed. As physical experiments are expensive, methods of statistical tolerance analysis tools are widely used in engineering design. Current tolerance simulation tools lack of an appropriate indicator for the impact of deviating component surfaces. In the adoption of Sensitivity Analysis methods, there are several challenges, which arise from the specific framework in tolerancing. This paper presents an approach to adopt Sensitivity Analysis methods on current tolerance simulations with an interface module, which bases on level sets of constraint functions for parameters of the simulation model. The paper is an extension and generalization of Ziegler and Wartzack [1] . Mathematical properties of the constraint functions (convexity, homogeneity), which are important for the computational costs of the Sensitivity Analysis, are shown. The practical use of the method is illustrated in a case study of a plain bearing. [ABSTRACT FROM AUTHOR]

This paper is focused on increasing the knowledge on methods for calibrating BES models and to get more insights of different approaches for the optimization of the calibration process. The paper will be centred in the evaluation of a multistage guided search approach. It defines an iterative optimization procedure which starts with the assignment of probabilistic density functions to the unknown parameters, followed by a random sampling and running batch of simulations. It then finishes with an iterative uncertainty and sensitivity analysis combined with a re-assignment of the ranges of variation of the strong parameters. The procedure converges when no new influencing parameters are found. This method is applied to a real case study consisting of an unoccupied office building located in Lleida (Spain). The measured indoor temperature has been used to determine the uncertainty and precision of the method. The effect of the size of the sampling, the number of iterations and the parameters of the global sensitivity method are analyzed in detail. The results of this paper exemplify the degree of accuracy of multistage guided search approaches, and illustrate the reasons how these analyses can contribute to the improvement of more refined calibration methods. [ABSTRACT FROM AUTHOR]

Abstract: In designing complex engineered systems, various experiments and simulations are needed for the verification of design hypotheses. Because the conducted verification is multidisciplinary, synthesis of these verification results should be based on a neutral model regarding the domains and disciplines. This paper introduces a metamodel, to which the roles and designers’ intentions (i.e., design situation) of various verification models are referred, and uses it for analyzing the synthesis process. The design of a paper-handling device is used for an analysis example, which clarifies advantages and drawbacks in modeling the synthesis process with such a metamodel. [Copyright &y& Elsevier]

Abstract: This paper presents a model of semantic ontologies integration into workflow co mposition design process via Virtual Simu lation Objects (VSO) concept and technology. Doma in knowledge distributed over open linked data sources may be usefully applied for new VSO-images design and used for organization co mputational-intensive simulation e xpe riments. In this paper we describe the VSO- architecture e xtended with novel functionality regarding integration with lin ked open data sources. We also provide a computational-scientific e xa mp le of do ma in-specific use-case offering a solution for some public-transportation domain problem. [Copyright &y& Elsevier]

We construct and analyze robust strong stability preserving IMplicit-EXplicit Runge-Kutta (IMEX RK) methods for models of flow with diffusion as they appear in astrophysics, and in many other fields where equations with similar structure arise. It turns out that besides the optimization of the region of absolute monotonicity, some other properties of the methods are crucial for the success of such simulations. In particular, the models in our focus dictate to also take into account the step size limits associated with dissipativity, positivity of the stiff parabolic terms which represent transport by diffusion, the uniform convergence with respect to different stiffness properties of those same terms, etc. Furthermore, in the literature, some other properties, like the inclusion of a part of the imaginary axis in the stability region, have been argued to be relevant. In this paper, we construct several new IMEX RK methods which differ from each other by taking various or even all of these constraints simultaneously into account. It is demonstrated for some simple examples as well as for the problem of double-diffusive convection, that the newly constructed schemes provide a significant computational advantage over other methods from the literature. Due to their accumulation of different stability properties, the optimized IMEX RK methods obtained in this paper are robust schemes that may also be useful for general models which involve the solution of advection-diffusion equations, or other transport equations with similar stability requirements. [ABSTRACT FROM AUTHOR]

This paper illustrates a simple procedure for calculating the covariances underlying any Generalized Extreme Value (GEV) model, based on an appropriate generalization of a result already established in the literature for the Cross-Nested Logit model (i.e. a particular GEV model). Specifically, the paper proves that the covariances in any GEV model are always expressed by a one-dimensional integral, whose integrand function is available in closed form as a function of the generating function of the GEV model. This integral may be simulated very easily with a parsimonious computational burden. Two practical examples are also presented. The first is an application to the CNL model, so as to check the consistency of the proposed method with the results already established in the literature. The second deals with the calculation of the covariances of the Network GEV (NGEV) model: notably, the NGEV is the most general type of GEV model available so far, and its covariances have not yet been calculated. On this basis, insights on the domain of the covariances reproduced by the NGEV model are also presented. [ABSTRACT FROM AUTHOR]

Leveling is a process used to minimize the bending defects in the steel industry. It plays an important role in delivering the desired material properties and product standards. This paper presents an analytical model for predicting the leveling process for H-beams with strong and weak axis bending defects. In this paper, an analytical model is first developed with the computational procedure of describing the continuous bending and reversed bending process, as well as the unloading process. Then, the developed analytical model and computational procedure are evaluated by a comparative study of results obtained from experimental data. Finally, the leveling process including curvature, trajectory, bending and residual stress distributions are evaluated for typical H-beam made of construction steel using the developed method. It is found that defective H-beam with different initial curvature tends to be flatted after the leveling process and the developed analytical model is much superior than finite element based modeling approach in terms of computational efficiency with the same level of accuracy. [ABSTRACT FROM AUTHOR]

Abstract: Numerical cross-shore profile evolution models have been good at predicting beach erosion during storm conditions, but have difficulty in predicting the accretion of the beach during calm periods. This paper describes the progress made in modifying and applying the public domain XBeach code to the prediction and explanation of the observed behaviour of coarse-grained beaches in the laboratory and the field under accretive conditions. The paper outlines in details the changes made to the original code (version 12), including the introduction of a new morphological module based upon Soulsby's sediment transport equation for waves and currents, and the incorporation of Packwood's infiltration approach in the unsaturated area of the swash region. The competence of this modified model during calm conditions for describing the steepening of the profile, and the growth of the beach berm is demonstrated. Preliminary results on the behaviour of the beach subject to both waves and tides are presented. Good agreement is found between the model simulations and large-scale laboratory measurements, as well as field observations from a composite beach in the UK. The reasons for the model's capabilities are discussed. [Copyright &y& Elsevier]

In process industry, failure or rupture of pressurized vessel is very dangerous especially when there is an escape of flammable gaseous mixture that can cause potential fire or explosion. One of the scenarios that causes such accidents is the blowdown process. Therefore, it becomes crucial to control blowdown process to prevent such accidents. It is important to design optimally to make sure that blowdown valve is according to the requirements. For the safe use of a pressure relief system, some of the parameters are critical, for example, selection of construction material, sizing of relief valves, temperature, and pressure, etc. There is no literature currently available that discusses all the mathematical models or simulation tools for optimum design of the blowdown process. This subject matters because the available models or tools cover different aspects of blowdown process. A meticulous review is required to present the applications of these models and tools based on the accidental scenarios. Therefore, this paper critically reviews the models and tools that are developed purposely to calculate optimum blowdown parameters based on fluid and vessel conditions. Recommendations are given for the development of new simulation tool to simulate phase change conditions especially when solid formation is involved. [ABSTRACT FROM AUTHOR]