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We present an intriguing topic in a mathematical modelling course where Lanchester models are taught to our students. Lanchester models are some of the earliest and most important models used for combat modelling. We describe modelling activities and the use of technology that can be implemented in teaching this topic in this paper. [ABSTRACT FROM AUTHOR]

The model, as a synthetic abstraction of reality, is applied in engineering practice to study the characteristics and behavior of dynamic systems. The paper gives an example of a simple physical model of an aircraft. A mathematical model is defined for testing primary flight characteristics. The paper uses a predictive model that is used to analyze the consequences of different system management strategies. The predictive model connects dependent and independent variables that describe system states. The paper presents simulations on three models. Mathematical and statistical methods are used in the paper. Parametric statistical methods are based on the normal distribution when predicting certain phenomena with a certain probability. The simulations in this paper represent the execution of operations on the system model in order to obtain the desired knowledge about the system’s behavior. This is a simple and safe way to experiment with a model. A real dynamic system whose movement is described with twelve differential equations is considered. The complexity of the problem of solving differential equations requires the use of the Runge-Kutta method of the fourth order. These simulations enable the understanding of the movement of complex dynamic systems, the design of new ones and the improvement of the performance of existing systems. A special contribution of the paper is in the large savings of all resources. The contribution of the paper itself is in confirming that the role of simulation in scientific research is indispensable due to: better understanding of the system (it reveals oversights in design), improving efficiency (it reveals problems in systems), testing alternatives (it avoids costly and sometimes dangerous trial and error experimentation on the real system), saving time, human resources and money (the cost of simulation is small compared to the gain it gives), and creating virtual environments. [ABSTRACT FROM AUTHOR]

This paper presents a computational heat transfer model of a rotary kiln used for the production of rutile titanium dioxide by the calcination of paste-like hydrous titanium dioxide. The work details the modelling of several chemical reactions occurring in the solid bed region along with turbulent convection of gas, radiation heat exchange among hot gas, refractory wall and the solid surface, and conduction in the refractory wall. Finite-difference techniques are used and the steady state thermal conditions are assumed. The kiln is divided into axial segments of equal length. The solution is of marching type and proceeds from the solid inlet to the solid outlet. The direction of gas flow is opposite to that of the solids. Mass balance of each species in the solid charge, and mass and energy balances of the solid and gas in an axial segment are used to obtain solids and gas temperatures, and species concentration at the exit of that segment. The kiln length predicted by the present model is 45.75 m as compared to 45 m of an actual kiln reported by Ginsberg and Modigell (2011). The steady-state axial gas and solid temperature profiles have been also satisfactorily validated with the numerical results of the aforementioned paper. The output data consist of refractory wall temperature distribution, the axial solids and gas temperature profiles, axial solids composition profile, the length required for drying of the solid charge and the total kiln length required to achieve 98% conversion of anatase TiO 2 to rutile TiO 2 . A detailed parametric study with respect to the controlling parameters such as percent water content (with respect to dry solids), solids flow rate, gas flow rate, kiln inclination angle and kiln rotational speed lent a good physical insight into the rutile-TiO 2 production process in a rotary kiln. [ABSTRACT FROM AUTHOR]

In trustworthy service discovery for Mobile Social Networking in Proximity (MSNP), conventional trust computation faces a big challenging issue—relatively high latency. To cope with it, trustworthiness determination strategies were proposed in our previous study, aiming at avoiding trust computation under certain conditions, so as to reduce the latency. These strategies are conceived based on the assumption that data of a user's past experience and current profile could be used, and they are incorporated with a set of thresholds from the analysis result of these data. The settings of these thresholds directly affect service quality and user satisfaction on the MSNP service, which in turn becomes an optimization problem. In this paper, we focus on formulating this optimization problem and demonstrating the effectiveness of our proposed solution by designing a simulation experiment. In detail, we establish mathematical models and adjust parameters. We conduct simulations on MATLAB and analyze the results obtained under several different settings. We further compare our work with related works. The results show that our proposed solution is practically feasible and effective in reducing latency under certain conditions. [ABSTRACT FROM AUTHOR]

Cocoa mirid, Sahlbergella singularis, is one of the major pests of cocoa in West Africa. It is responsible of several damages in plots. In this paper, we study the dynamics of this pest. Based on biological and ecological partial knowledge, we develop 2 cooperative mathematical models that aim to describe the time dynamics of the cocoa mirids. We first develop a cooperative stage‐structured model, derived some qualitative results, and a sensitivity analysis study in order to determine the most important parameters. Assuming that all parameters are or not periodic, we obtain conditions that allow the persistence or not of the population. We highlight the influence of cocoa pods variation along the year on the time evolution of the population. Then, we derive a 2‐stage cooperative time‐delay model, with 2 delays, that takes into account the eggs' development time and the females' maturation time. We illustrate our theoretical results with some simulations and show that the delayed system provides the best results compared with real observations. Finally, we focus on chemical control that is commonly used in Cameroon and compare it to a new biological control, mixing mating disrupting and trapping. We discuss the results and provide future perspectives based on this work. [ABSTRACT FROM AUTHOR]

Despite the tremendous effort of researchers and manufacturing engineers in improving the predictability of the air bending process, there is still a strong need for comprehensive and dependable prediction models. Currently, available modeling approaches all present some relevant limitations in practical applications. In this paper, we propose a new method, which represents an improvement over all existing modeling and prediction techniques. The proposed method can be used for accurate prediction of the main response variables of the air bending process: the angle a after springback and the bend deduction BD. The metamodeling method is based on the hierarchical fusion of different kinds of data: the deterministic low-fidelity response of numerical finite element method (FEM) simulations and the stochastic high fidelity response of experimental tests. The metamodel has been built over a very large database, unprecedented in the scientific literature on air bending, made of more than 500 numerical simulations and nearly 300 experimental tests. The fusion is achieved first by interpolating the FEM simulations with a kriging predictor; then, the hierarchical metamodel is built as a linear regression model of the experimental data, using the kriging predictor among the regressors. The accuracy of the method has been proved using a variant of the leave-one-out cross validation technique. The quality of the prediction yielded by the proposed method significantly over-performs the current prediction of the press brake on-line numerical control. [ABSTRACT FROM AUTHOR]

Abstract: Coaxial Heat Exchangers (CHXs) are now used extensively in heat pump (HP) and refrigeration systems. The design of such systems requires estimation of CHX's thermal and hydraulic performance. This paper presents a generalized finite volume CHX model that is capable of simulating single-phase and two-phase flow with a smooth or fluted inner tube. The concepts of segment insertion and subdivision (moving boundary within the segment) are adopted in this model to track the phase change point along the flow channel. This allows for reliable model accuracy even with a lower number of discretized finite volumes, thereby reducing computation time. For the segment insertion and subdivision functions, four different approaches are provided in order to achieve the best accuracy and least computational effort under various flow configurations and fluid conditions. The simulation model can be applied to straight and helical tubes with choices of smooth, grooved and fluted tube surface. Empirical single-phase and two-phase correlations from the literature are adopted in the proposed model for the applicable surfaces. At present, there are no correlations for two-phase flow in fluted tube annuli, in the open literature. This paper proposes modifications to existing two-phase fluted surface heat transfer and pressure drop correlation formulations by applying empirical two-phase flow multipliers onto existing fluted tube single phase correlations. The solving methodology of this model requires the heat exchanger geometry, flow configuration, inlet states, as well as mass flow rates of the fluids to solve for the outlet conditions, heat load, pressure drop and charge of the CHX. Coupled with non-linear equation solver, the model can also provide the required mass flow rate for a specific superheat/subcooling on either side of the CHX. The model and modified correlations are validated against experimental data of brine-to-refrigerant fluted tube condenser and evaporator used in a heat pump application. [Copyright &y& Elsevier]

Mechanical ventilation is a key therapy for patients who cannot breathe adequately by themselves, and dynamics of mechanical ventilation system is of great significance for life support of patients. Recently, models of mechanical ventilated respiratory system with 1 lung are used to simulate the respiratory system of patients. However, humans have 2 lungs. When the respiratory characteristics of 2 lungs are different, a single-lung model cannot reflect real respiratory system. In this paper, to illustrate dynamic characteristics of mechanical ventilated respiratory system with 2 different lungs, we propose a mathematical model of mechanical ventilated respiratory system with 2 different lungs and conduct experiments to verify the model. Furthermore, we study the dynamics of mechanical ventilated respiratory system with 2 different lungs. This research study can be used for improving the efficiency and safety of volume-controlled mechanical ventilation system. [ABSTRACT FROM AUTHOR]

This paper presents numerical studies of large-size and high-quality fused silica glass synthesis by SiCl 4 flame hydrolysis deposition method, specifically the correlation of uniformities of SiO 2 deposition and OH concentration with the optimal location of the substrate placement. A comprehensive computational model is developed to describe the complex turbulent reacting flow with the detailed SiCl 4 -H 2 -O 2 reaction mechanism. Numerical simulation is first conducted to obtain the characteristics of SiCl 4 hydrolysis flame without considering the substrate and the SiO 2 particle formation. The distribution of SiO 2 accumulation is then calculated. The potential region and location for placing substrate are initially determined based on the criterion of a uniform SiO 2 accumulation. Further, the effects of H 2 -O 2 equivalence ratio and the SiCl 4 flow rate on the distributions of the temperature, SiO 2 concentration and OH concentration are investigated. It is found that the H 2 -O 2 equivalence ratio is sensitive to the temperature and the OH concentration, and the flow rate of SiCl 4 mainly affects the temperature and SiO 2 concentration. This finding indicates that the H 2 -O 2 equivalence ratio and the flow rate of SiCl 4 have equally important roles in determining the optimal location for the deposition substrate placement. The presence of the substrate also changes the distributions of the temperature and compositions concentrations in the furnace. Adjusting the substrate location is an effective strategy to achieve optimal location with more uniform distributions of the SiO 2 accumulation and the OH concentration on the deposition surface. [ABSTRACT FROM AUTHOR]

The main market studies depict a future in which all one-aisle aeroplanes will mount engines composed of elements with complex surfaces. Among the new generation of tools, the barrel-shaped tools were released to the market for the machining of such types of surfaces. However, there are no evidences reported in the literature about how do these tools work. This work presents for the first time a mathematical model based on the numerical discretization of barrel cutters to predict the cutting forces. The effects of helix angle, runout and lead and tilt angles were included and the model was validated for a range of conditions in a 5-axis machine. In this line, this paper enables future mathematical developments including more details and aiming at other complex problems. [ABSTRACT FROM AUTHOR]

This paper presents the mathematical model and numerical analysis of the convective drying process of thick slices of colloidal capillary-porous materials slowly moving through conveyor-belt dryer. A flow of hot moist air was used as drying agent. The drying process has been analyzed in the form of a 2-D mathematical model, in two directions: along the conveyor and perpendicular on it. The mathematical model consists of two non-linear differential equations and one equation with a transcendent character and it is based on the mathematical model developed for drying process in a form of a 1-D thin layer. The appropriate boundary conditions were introduced. The presented model is suitable for the automated control of conveyor-belt dryers. The obtained results with analysis could be useful in predicting the drying kinetics of potato slices and similar natural products. [ABSTRACT FROM AUTHOR]

A conventional robot sequence of a single-armed cluster tool pursues a backward strategy for efficiency; the strategy is optimal when identical work cycles are repeated. However, we cannot guarantee the strategy is optimal under some abnormal situations, such as breakdowns or during auto-cleaning (periodic cleaning for preventive maintenance). In this paper, we focus on undesirable but predictable auto-cleaning, which cleans the chambers of a cluster tool each time a predefined number of wafers has been processed to prevent deterioration of wafer quality caused by residual chemicals. For auto-cleaning, we suggest alternative cleaning frequencies of a single-armed cluster tool that periodically clean the inside of process modules based on the Theory of Constraints. Additionally, we derive its heuristic robot scheduling from Petri-net models, because finding the optimal robot sequence in real time is impossible. Finally, we examine the effectiveness of our suggestions by simulation. [ABSTRACT FROM AUTHOR]

Modern passenger terminals are characterized by dynamic processes variability, diverse options consideration, taking into account the criteria of safety, reliability analysis and the continuous research of passenger processing. For any modern marine passenger terminal it is necessary to use the tool to simulate passenger flows. In this way it is possible to obtain the analytical information and use it for decision-making when solving the problem of the amount of personnel required for passenger services.in line with the original ship arrival schedule, to solve problems of forecasting groups at the terminal. Of particular relevance is the choice of the mathematical transport model and the practical conditions for the implementation of the model in the real terminal operation. In this article the analysis technique of simulation-based terminal services, provides a mathematical model of passenger movement inside the terminal. Also, the conditions of implementation of the transportation model during the operation of marine passenger terminal are examined. The object of the research is the marine Passenger Port of St. Petersburg “Marine Facade”. The paper discusses advantages of using such systems and their introduction in the early stages of operation of the terminal. In addition, the conclusion about the effectiveness of such systems for the analysis of the correctness of internal space of the marine terminal. The study represents an example of analytical information used for the forecast of the terminal operations, the analysis of the workload and efficiency of the organization of the marine terminal. [ABSTRACT FROM AUTHOR]

This paper is about partitioning in parallel and distributed simulation. That means decomposing the simulation model into a number of components and to properly allocate them on the execution units. An adaptive solution based on self-clustering, that considers both communication reduction and computational load-balancing, is proposed. The implementation of the proposed mechanism is tested using a simulation model that is challenging both in terms of structure and dynamicity. Various configurations of the simulation model and the execution environment have been considered. The obtained performance results are analyzed using a reference cost model. The results demonstrate that the proposed approach is promising and that it can reduce the simulation execution time in both parallel and distributed architectures. [ABSTRACT FROM AUTHOR]

Information regarding the metabolism of xenobiotic chemicals plays a central role in regulatory risk assessments. In regulatory programmes where metabolism studies are required, the studies of metabolic pathways are often incomplete and the identification of activated metabolites and important degradation products are limited by analytical methods. Because so many more new chemicals are being produced than can be assessed for potential hazards, setting assessment priorities among the thousands of untested chemicals requires methods for predictive hazard identification which can be derived directly from chemical structure and their likely metabolites. In a series of papers we are sharing our experience in the computerized management of metabolic data and the development of simulators of metabolism for predicting the environmental fate and (eco)toxicity of chemicals. The first paper of the series presents a knowledge-based formalism for the computer simulation of non-intermediary metabolism for untested chemicals, with an emphasis on qualitative and quantitative aspects of modelling metabolism. [ABSTRACT FROM AUTHOR]

Abstract: The present paper, as the first part of two, suggests a method to approach the challenge of capacity control in Ground Source Heat Pumps (GSHP). The paper describes the development of a model of the system which includes several sub-models such as the heat pump unit, building, ground source, thermal storage tank, auxiliary heater, and climate. The developed computer model can be used for comparative analysis of different control methods and strategies aiming at the improvement of the system seasonal performance. With this model, on/off controlled and variable capacity GSHPs, with a single speed or variable speed pumps in the systems, can be evaluated in a wide range of operating conditions and more energy efficient methods of the system control can be found. The computer model is developed in the two environments EES and TRNSYS utilizing so-called co-solving technique. [Copyright &y& Elsevier]

This paper presents modeling guidelines and a benchmark system for power system simulation studies of grid-connected, three-phase, single-stage Photovoltaic (PV) systems that employ a voltage-sourced converter (VSC) as the power processor. The objective of this work is to introduce the main components, operation/protection modes, and control layers/schemes of medium- and high-power PV systems, to assist power engineers in developing circuit-based simulation models for impact assessment studies, analysis, and identification of potential issues with respect to the grid integration of PV systems. Parameter selection, control tuning, and design guidelines are also briefly discussed. The usefulness of the benchmark system is demonstrated through a fairly comprehensive set of test cases, conducted in the PSCAD/EMTDC software environment. However, the models and techniques presented in this paper are independent of any specific circuit simulation software package. Also, they may not fully conform to the methods exercised by all manufacturers, due to the proprietary nature of the industry. [ABSTRACT FROM AUTHOR]

The modern approach of the exploration of dynamic characteristic of elements or system of some device has been enabled by system dynamics. System dynamics is an excellent software system for studying the dynamic of the behaviour of natural, technical and societal realities i.e. system of various natures and features in which there exist relatively high analogy rate. The methodology of its work, including even the use of digital computers has shown to be an efficient mean for solving the problems: management, behaviour, sensitivity, flexibility and studying of dynamics of the behaviour of the systems of high complexity by computer simulation, in laboratory what means without danger for the realities observed. For the usage of system dynamics in the solution of complex problems, various complex knowledge from various scientific disciplines are required, but good knowledge of the nature of the problem itself, which is being analyzed. The paper has analyzed dynamic characteristic of cooling system in marine diesel engines by means of system dynamics. The cooling system of propulsion of MDE is a complex system onto which various disorders act and due to their changeable act result into the changes of working temperature of MDE. System dynamic approach in the analysis of MDE enable us to obtain the answer to the question "What if…" in other words we arrive at the solution what the reaction would be at the changes of any variable in the cooling system. The paper has shown: dynamic and static regime of work, mathematic model of the cooling system of MDE, simulation model in POWERSIM programme language and diagrams of the flows of water. [ABSTRACT FROM AUTHOR]

In this paper the MADA mathematical model is presented for the optimal management of aquifer exploitation. The model is built by embedding the AQÜIMPE model for simulation of ground water aquifers into a linear programming algorithm. MADA is used to evaluate exploitation in «Cuenca Sur de la Habana» aquifer, following a given water use plan (PUA). It is shown in the paper that PUA distribution of well abstractions is not considering possible saline intrusion in the aquifer and to that end a solution is presented. [ABSTRACT FROM AUTHOR]

Models of occupant flow in buildings represent powerful tools for improving safety and efficiency of occupant movements in large public buildings. The ability to predict the movement of people is valuable from the view point of safety considerations as well as several nonemergency aspects such as the level of service, efficiency and comfort, as well as space cognition and interaction. Capturing the manner of occupant movement can be used for the design of pathways and corridors in large public buildings such as train stations, airports, academic buildings, and shopping centers. Surprisingly, to date there has been very limited research on correlating the design of the building corridors to the occupant flow. Short of code requirements for emergency egress, there are very few guidelines on sizing and designing corridors. This paper presents the findings of a study aimed at developing a method to evaluate the flow of occupants in corridors, so that designers can understand how well a particular corridor accommodates the occupants’ movements and activities. In this paper, a queuing model is developed for determining the occupant flow density in corridors. The queuing model can be used to determine the occupant flow density in a wide array of corridor layouts and designs and correlate it to the level of service. In addition, actual data were collected and analyzed to validate the results from the queuing model. It is shown that the model is robust and accurate enough to model a wide array of design variables. The analysis can be very useful in designing efficient corridors in buildings of various scales ranging from small shopping centers to large airports, resulting in potential construction cost savings. A computerized model is developed and presented along with an example. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes an application of a fuzzy logic position control to an electrohydraulic servosystem. Mathematical model of the electrohydraulic servosystem is obtained considering the internal leakage within the servosystem. Electrohydraulic servosystems are one of the most commonly used actuators. However, electrohydraulic servosystems are difficult to control due to nonlinearity and complexity of their mathematical models. In this paper, as a first step, the mathematical models of the main components of the servosystem are obtained. The effect of compressibility, friction, internal leakage in servovalve, leakage in actuator and inertia are included in the model. Since the system has a complex structure and the system characteristics are time dependent. Fuzzy Logic Control (FLC) is applied to the electrohydraulic servosystem. The error and change in error are employed in the FLC. The effect of internal leakage on the mathematical model and performance of the position control system is investigated. Numerical simulation results for position control under a square wave reference input are obtained. Results are presented in graphical form. Physical trends of numerical simulation results are discussed. Although leakage is often ignored in dynamic analysis of servosystems, results shown in the paper indicate that the leakage has a significant effect on the mathematical model and performance of the position control system at small spool displacements. [Copyright &y& Elsevier]

The BaBar experiment requires simulated events beyond the ability of a single computing site to provide. This paper describes the evolution of simulation and job management methods to meet the physics community requirements and how production became distributed to use resources beyond any one computing center. The evolution of BaBar simulation along with the development of the distribution of the computing effort is described. As the computing effort is distributed to more sites there is a need to simplify production so the effort does not multiply with number of production centers. Tools are created to be flexible in handling errors and failures that happen in the system and respond accordingly, this reduces failure rates and production effort. This paper will focus on one cycle of simulation production within BaBar as a description of a large scale computing effort which was fully performed, and provided new simulation data to the users on time. [ABSTRACT FROM AUTHOR]

Discrete event simulation (DES) has been widely applied to modelling and simulation of computer and engineering systems and is an active field of research that has now evolved from 2D to 3D discrete event simulation. This paper attempts to address several key issues in a successful implementation of DES models based on our own and the previous experiences of others. It describes the common basis, which forms the core for the application of modelling and simulation methodologies that are available to support manufacturing systems analysis, design and performance evaluation. Through a comprehensive literature survey, this paper summarises and compares the most widely used optimisation techniques for simulation of manufacturing systems; an overview of the recent and popular simulation languages and packages available for the modelling and simulation community and the classification of their utility for modelling and simulation of manufacturing systems is also given. Finally, this paper summarises and reports the latest development in the most exciting world wide web (www)-based simulation techniques that represent a future that may completely change the nature and future exploitation of modelling and simulation technology in industry. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT) are currently used as a promising family of nanovectors able to deliver different types of therapeutic molecules. Several applications dealing with CNT used as drug nanocarriers have been developed since their ability to penetrate into the cells has been proved. CNT can thus load several active molecules to various cells. In this paper, we will use molecular dynamic simulation to describe theoretically the potential of CNT to transport and deliver DNA through the formation of protamine-DNA-CNT complex. [ABSTRACT FROM AUTHOR]

A key parameter of the linear programming (LP) models widely used for production planning in industry and academia are the lead times, the estimated delay between material becoming available to a resource and its completion at that resource. Lead times are commonly treated as exogenous, workload-independent parameters and assumed to be integer multiples of the planning period. Although formulations with non-integer lead times have been implemented in industry, we are unaware of any studies systematically evaluating their performance. In this paper, we compare the performance of LP models with and without non-integer lead times by simulating the execution of the resulting release plans. We also compare their performance to that of a formulation incorporating workload-dependent lead times using nonlinear clearing functions. We find that the performance of the models with non-integer lead times is substantially better than those with integer lead times, and often superior to that of the much more complex clearing function models. These results suggest that whenever reasonable estimates of the lead times are available, non-integer lead times should be used due to their simplicity of implementation and excellent performance. [ABSTRACT FROM AUTHOR]

This paper presents a general modeling framework for Intermodal Freight Transport Terminals (IFTTs). The model allows simulating and evaluating the performance of such key elements of the intermodal transportation chain. Hence, it may be used by the decision maker to identify the IFTT bottlenecks, as well as to test different solutions to improve the IFTT dynamics. The proposed modeling framework is modular and based on timed Petri Nets (PNs), where places represent resources and capacities or conditions, transitions model inputs, flows, and activities into the terminal and tokens are intermodal transport units or the means on which they are transported. The model is able to represent the different types of existing IFTTs. Its effectiveness is tested first on an example from the literature and then on a real case study, the railroad inland terminal of a leading Italian intermodal logistics company, showing its ease of application. In the real case study, using the proposed formalism we test the as-is IFTT performance and evaluate alternative possible to-be improvements in order to identify and eliminate emerging criticalities in the terminal dynamics. [ABSTRACT FROM AUTHOR]

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the model results-here the simulation result are verified in terms of convergence of the model in dependence on the degrees of freedom (DOF) and by measurements. The experimental method is based on measurement of electric field inside the enclosure using an electric field probe with small dimensions is described in the paper. Solution of an illustrative example of SE by FEM is shown and simulation results are verified by experiments. [ABSTRACT FROM AUTHOR]

In this paper, a very easy, numerically stable and computationally efficient method is presented, which allows the modeling and simulation of a flexible robot with high precision. The proposed method is developed under the hypotheses of flexible links having varying cross sections, of targe link deformations and of time-varying geometrical and/or physical parameters of both the robot and the end-effector. This methodology uses the same approach of the modeling of rigid robots, after suitably and fictitiously subdividing each link of the robot into sublinks, rigid to the aim of the calculus of the inertia matrix and flexible to the aim of the calculus of the elastic matrix. The static and dynamic precision of the method is proved with interesting theorems, examples and some experimental tests. Finally, the method is used to model, control, and simulate a crane, composed of three flexible links and a cable with varying length, carrying a body with a variable mass. [ABSTRACT FROM AUTHOR]

Nowadays the gear presents of the most widespread part of the machines and equipment. There is needed to solve the machining process for a complicated involute profile of tooth face, because precision of the profile influences on the working of the parts. The paper deals with a mathematical model design for the Maag cutting of a gear profile, which is one of control mechanisms of the machining process. The mathematical model can be used for simulation of Maag cutting and analysis by the position of the gear rack profile towards involute gear profile. There is possible to determine final inaccuracy of gear rack machining which is caused by kinematical movement between work-piece and production tool. The results of the simulation in the reverse realization determine accurate profile of gear rack. [ABSTRACT FROM AUTHOR]

In this paper is presented the procedure of using Matlab-Simulink's SFunction blocks for simulating the Luenberger observer, which has the role of estimating the rotor flux of an induction machine with squirrel-cage rotor. In order to analyze the dynamic performance of the Luenberger estimator, both the effects of electric parameters variations and the effects of noise measurements are highlighted. [ABSTRACT FROM AUTHOR]

In this paper is presented the procedure of using Matlab-Simulink's S-Function blocks for simulating the mathematical mode of the induction motors with the squirrel-cage rotor, in which the iron losses are not negligible. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model of hydro power units, especially the governor system model for different operating conditions, based on the basic version of the software TOPSYS. The mathematical model consists of eight turbine equations, one generator equation, and one governor equation, which are solved for ten unknown variables. The generator and governor equations, which are different under various operating conditions, are presented and discussed in detail. All the essential non-linear factors in the governor system (dead-zone, saturation, rate limiting, and backlash) are also considered. Case studies are conducted based on one Swedish hydro power plant (HPP) and three Chinese plants. The simulation and on-site measurements are compared for start-up, no-load operation, normal operation, and load rejection in different control modes (frequency, opening, and power feedback). The main error in each simulation is also discussed in detail. As a result, the model application is proved trustworthy for simulating different physical quantities of the unit (e.g., guide vane opening, active power, rotation speed, and pressures at volute and draft tube). The model has already been applied effectively in consultant analyses and scientific studies. [ABSTRACT FROM AUTHOR]

This paper describes the research on adaptronic systems made by the author and offers to use biosensors that can be later inserted into the adaptronic systems. Adaptronic systems are based, on the one hand, on the adaptronic approach when the system is designed not to always meet the worst condition, but to change the structure of the system according to the external conditions. On the other hand, it is an extension of common automatic control ad adaptive systems. So, in the introduction firstly the adaptronic approach and biosensor as a term is explained. Adaptive systems, upon which adaptronic ones are based, are also mentioned. Then the construction of biosensor is described, as well as some information is given about the classification of biosensors and their main groups. Also it is suggested to use lichen indicators in industry to control concentration of chemical substances in the air. After that mathematical models and computer experiments for adaptronic system and biosensor analysis are given. [ABSTRACT FROM AUTHOR]

The interest in stratospheric airships has increased and great progress has been achieved since the late 1990s due to the advancement of modern techniques and the wide range of application demands in military, commercial, and scientific fields. Thermal issues are challenging for stratospheric airships, while there is no systematic review on this aspect found yet. This paper presents a comprehensive literature review on thermal issues of stratospheric airships. The main challenges of thermal issues on stratospheric airships are analyzed. The research activities and results on the main thermal issues are surveyed, including solar radiation models, environmental longwave radiation models, external convective heat transfer, and internal convective heat transfer. Based on the systematic review, guides for thermal model selections are provided, and topics worthy of attention for future research are suggested. [ABSTRACT FROM AUTHOR]

Based on computer modeling and simulation, the problem of evacuation strategies that utilize a combination of stairs and elevators for high rise buildings is investigated in this paper. First, by using the Pathfinder software, a 28-storey building model with stairs and elevators is established. Then, based on the obtained model, several evacuation scenarios are designed for researching this issue. The simulation results show that the optimal percentages of the occupants evacuated by the elevators, when achieving the shortest evacuation time, is almost not related to the number of evacuated persons and floors. Furthermore, the evacuation time decrease achieved by increasing the elevator maximum speed is not as much as that obtained by increasing the number of elevators. Moreover, when evacuating different age groups, it is found that selecting the aged (slow-moving) people, who may create congestion in the stairs, to be evacuated by elevators can speed up the evacuation efficiently, and selecting the children to be evacuated by elevators can improve the utilization rate of the elevators. Finally, the evacuation with a priority order from lower floors to upper floors is considered. Results show that the evacuation with a priority order from lower floors to upper floors can effectively decrease the congestion on the stairs caused by the aged people, and achieve a faster evacuation rate during most of the evacuation process, although the total evacuation time increases a little. [ABSTRACT FROM AUTHOR]

This paper presents a detailed flexible mathematical model for planar solid oxide fuel cells (SOFCs), which allows the simulation of transient performance characteristics. This mathematical model includes the incorporation of a thermal modelling into an electrochemical model with physico-chemical governing equations and a detailed multi-component gas diffusion mechanism, Dusty Gas Model (DGM). Spatial discretization can be applied up to quasi 3-D geometries and is resolved with the FDM (Finite Difference Method). The model is built and implemented in the commercially available modelling and simulations platform gPROMS™. The model was compared against existing models, the differences in results are identified and attributed to assumptions. Several transient operation case studies are examined such as load change and start-up: the results illustrate how important such a tool is for analyzing SOFC operation. [ABSTRACT FROM AUTHOR]

The improvements in semiconductor technologies are gradually enabling extreme-scale systems such as teradevices (i.e., chips composed by 1000 billion of transistors), most likely by 2020. Three major challenges have been identified: programmability, manageable architecture design, and reliability. TERAFLUX is a Future and Emerging Technology (FET) large-scale project funded by the European Union, which addresses such challenges at once by leveraging the dataflow principles. This paper presents an overview of the research carried out by the TERAFLUX partners and some preliminary results. Our platform comprises 1000+ general purpose cores per chip in order to properly explore the above challenges. An architectural template has been proposed and applications have been ported to the platform. Programming models, compilation tools, and reliability techniques have been developed. The evaluation is carried out by leveraging on modifications of the HP-Labs COTSon simulator. [ABSTRACT FROM AUTHOR]

Laminar and turbulent forced convection heat transfer and flow characteristics of nanofluids in small smooth tubes are numerically simulated using two kinds of multiphase-flow models. The simulated results are compared with the experimental results from the published papers and the traditional predicting correlations to investigate the applicability of these models for nanofluids. The multiphase-flow models including mixture model and Eulerian model, and both of them belong to the well-known Euler–Euler model. The effects of various parameters such as Reynolds number and nanoparticles concentration on the heat transfer and flow characteristics are investigated and discussed in each model. The study results show that little deviation exists between the simulated results and the traditional predicting correlations for low concentration nanofluid, which indicates that low concentration nanofluid has no meaningful nano-effect on forced convection heat transfer. While, non-traditional fluid characteristics occur and increase with increasing the nanoparticles concentration, and the simulated results using special models of multiphase flow are closer to the experimental data than that of the traditional correlations, which means the multiphase flow models are more accurate than traditional correlations for high concentration nanofluid. Moreover, the numerical results also indicate that the drag coefficients of simulated results have only little difference less than 0.4% with that of experimental results for nanofluids in the laminar flow region. However, the drag coefficients of simulated results have a increase by about 60–22% compared with the experimental results in the turbulent flow region. As conclusion, the present study indicates that the two-phase models, including mixture model and Eulerian model, can predict the forced convection heat transfer and flow characteristics of nanofluid well, and have important implications for the application of nanofluid. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical sensitivity of a vibration sensor is investigated by developing a mathematical model with the function of a relative movement modulus and measurement error. This model enables mechanical sensitivity to be improved by enhancing the performance of the vibration sensor. The purpose of the present work is to reduce measurement error by choosing the right damping rate that enables vibration sensor sensitivity to be optimized. The presented model is validated by computer simulation and experimental tests. The obtained results have shown that correct choice of damping rate and frequency range keeps the mechanical sensitivity constant. [ABSTRACT FROM PUBLISHER]

This paper presents development of numerical heat conduction model for prediction of transient three dimensional temperature field in the billet. The model is applied to billet heating process in the reheat furnace. The discretization of governing equation is done by control volume approach and implicit scheme of finite difference method. The model captures various time dependent boundary conditions corresponding to the billet reheat in the reheat furnace, in addition to this it also accounts for the growth of oxide scale layer on the billet surfaces during reheat simulations. The set of discretized equations is solved using own developed MATLAB ® code. The proposed model is capable of predicting the temperature field in the billet and scale growth on the billet surfaces. The model is validated with analytical results and published experimental results. The results obtained through the model simulations are in concurrence with the anticipated trend. The proposed methodology of numerical modeling will be helpful for the temperature and scale growth predictions, which are vital for a variety of reasons like energy efficiency, process optimization, roll force calculations, carbon segregation control and product microstructure control, etc. [ABSTRACT FROM AUTHOR]

The paper presents a part of the work conducted in the first stage of a Research Grant called "Hybrid micro-cogeneration group of high efficiency equipped with an electronically assisted ORC" acronym GRUCOHYB. The hybrid micro-cogeneration group is equipped with a four stroke Diesel engine having a maximum power of 40 kW. A mathematical model of the internal combustion engine is presented. The mathematical model is developed based on the Laws of Thermodynamics and takes into account the real, irreversible processes. Based on the mathematical model a computation program was developed. The results obtained were compared with those provided by the Diesel engine manufacturer. Results show a very high correlation between the manufacturer's data and the simulation results for an engine running at 100% load. Future developments could involve using an exergetic analysis to show the ability of the ORC to generate electricity from recovered heat. [ABSTRACT FROM AUTHOR]

The paper presents computer simulation approach to developing optimal bus scheduling under stochastic and deterministic network environments with static and dynamic demand. The primary objective is to minimize the total passenger waiting time. The mean transit demand at each stop and the travel time between neighboring bus stops are assumed as known information. An example route showing an application of the proposed model is presented. Comparisons between waiting times under different network scenarios have been made using the example route. The results obtained from the analyses are promising and thus the method can be implemented as a substitute to real time control strategies when implementation cost is an issue as the latter is relatively expensive. It may also be used in coordination with the real time control strategies to reduce holding time. In addition, it can assist transit users in planning their trips in advance so that misleading travel information is reduced. [ABSTRACT FROM AUTHOR]

Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC) is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO2 and H2O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated. [ABSTRACT FROM AUTHOR]

Computer simulations of complex food-webs are important tools for deepening our understanding of these systems. Yet most computer models assume, rather than generate, key system-level patterns, or use mathematical modeling approaches that make it difficult to fully account for nonlinear dynamics. In this paper, we present a computer simulation model that addresses these concerns by focusing on assumptions of agent attributes rather than agent outcomes. Our model utilizes the techniques of complex adaptive systems and agent-based modeling so that system level patterns of a marine ecosystem emerge from the interactions of thousands of individual computer agents. This methodology is validated by using this general simulation model to replicate fundamental properties of a marine ecosystem, including: (i) the predator-prey oscillations found in Lotka-Volterra; (ii) the stepped pattern of biomass accrual from resource enrichment; (iii) the Paradox of Enrichment; and (iv) Gause's Law. [ABSTRACT FROM AUTHOR]

The water time constant and mechanical time constant greatly influences the power and speed oscillations of hydro-turbine-generator unit. This paper discusses the turbine power transients in response to different nature and changes in the gate position. The work presented here analyses the characteristics of hydraulic system with an emphasis on changes in the above time constants. The simulation study is based on mathematical first-, second-, third- and fourth-order transfer function models. The study is further extended to identify discrete time-domain models and their characteristic representation without noise and with noise content of 10 & 20 dB signal-to-noise ratio (SNR). The use of self-tuned control approach in minimising the speed deviation under plant parameter changes and disturbances is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, prey–predator models appearing in various fields of mathematical biology have been proposed and studied extensively due to their universal existence and importance. In this paper, we introduce a fractional-order prey–predator model and deals with the mathematical behaviors of the model. The dynamical behavior of the system is investigated from the point of view of local stability. We also carry out a detailed analysis on the stability of equilibrium. Numerical simulations are presented to illustrate the results. [Copyright &y& Elsevier]