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In an attempt to reduce acoustic pollution due to terminal flight phases (lift-offs and landings) in the surroundings of heliport, project MANOEUVRES developed a device capable of estimating the acoustic footprint of helicopters on the ground. This device requires knowledge of certain quantities that cannot be directly measured through physical sensors: the tip-path plane angle of attack and the main rotor thrust coefficient. Previous research has demonstrated that these quantities can be accurately estimated using observers that are properly fed with directly measurable flight mechanics and rotor state variables. However, these observers, which are based on linear mathematical models identified offline and employed through interpolation with respect to nominal airspeed, have shown poor robustness when the number of identification input cases is reduced, as required for a realistic design of observers in the field. This issue has particularly emerged when non-trimmed manoeuvres were considered during observation testing. To address this issue, this paper introduces a new baseline for the observation model, which includes dynamic pressure as an additional input. Moreover, a different model structure is considered depending on the observed variable. Specifically, for the tip-path plane angle of attack, a single model covers the entire airspeed range, while observation models for the rotor thrust coefficient are interpolated based on flight altitude. This new approach demonstrates results of comparable or superior quality to previous observation models. Furthermore, it exhibits increased robustness when the pool of identification cases used for observer synthesis is significantly reduced. Such improved performance and ease of synthesis pave the way for the setup and adoption of the proposed observers in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method to determine the strength criterion causing failure of spot joints used in the construction of thin-walled profiles under impact load has been developed and strength parameters guaranteeing joint continuity during dynamic crushing of crash–boxes were determined. • Extensive quasi-static and dynamic materials tests were conducted for the 5 most popular steel grades used in the automotive industry (DP600, DP800, DP1000, HSLA and DC01A). • The strength of spot joints in a complex load state was evaluated and numerical simulations were performed to predict the behavior (shearing force, cross–tension force) of the clinched and spot-welded joints. • Both quasi-static and dynamic crushing of thin-walled, energy-absorbing, top-hat structures were conducted and compared with presented constitutive strength models which allowed to calibrate the FEM models. • The constitutive models for the minimum shear strength (F s) and cross-tension strength (F n) of joints was determined as a function of sheet thickness and parameters R e and R m. The goal of this paper was to determine the strength criterion that causes the failure of point-to-point joints of thin-walled profiles under impact load, as well as to determine the strength parameters that guarantee joint continuity during dynamic folding of crash boxes. For this purpose, extensive quasi-static and dynamic materials tests were conducted for the five most popular steel grades used in the automotive industry: DP600, DP800, DP1000, HSLA and DC01. The strength of the spot joints was investigated in a complex load state using the original instrumentation. This allowed authors to build and validate mathematical models of the load-bearing capacity of point-to-point joints and to conduct simple and efficient numerical simulations of these elements without the need to account for their geometry. Following the validation of mathematical models and load-bearing models of the joints, extensive experiments of quasi-static and dynamic crushing of thin-walled energy-absorbing top-hat (TH) structures were conducted. The data collected made it possible to calibrate the FEM model correctly and conduct numerical simulations of the dynamic crushing of energy-absorbing structures. As a result, the minimum shear strength (F s) and cross-tension strength (F n) of the joints were determined as a function of the sheet thickness and the parameters of R e and R m. The creation of any spot joint enabling the simultaneous carrying of forces F s and F n ensures the preservation of joint continuity throughout the entire crushing process and makes it possible for manufacturers to select the type of spot joint based only on its strength. [ABSTRACT FROM AUTHOR]

Numerical back analysis based on incomplete in situ stress measurements is widely used to estimate the three-dimensional (3D) in situ stress fields of large deep underground caverns. However, the variable collinearity caused by complex geological environments has rarely been considered. This paper proposes a numerical back analysis method for 3D in situ stress fields based on stepwise regression (BSSR). In BSSR, the collinearity between independent variables is associated with the surface topography, and insignificant variables caused by variable collinearity are eliminated through stepwise regression. BSSR was applied to the underground powerhouse of a hydropower station for validation, and the results showed that it can reliably estimate the 3D in situ stress field despite the complex geological environments. Multidimensional mathematical models of in situ stress fields were established with the improved predictive ability and clear physical meaning, which can quantify the contributions of six geological actions and three stress sources. The findings of this study can help with understanding the formation mechanism of in situ stress fields for large, deep underground caverns in complex geological environments and provide a useful reference for optimizing excavation schemes and support designs. [ABSTRACT FROM AUTHOR]

Pre-Darcy flow is widely found in many naturally porous media, such as low-permeability clay. Nonflowing liquid boundary layers strongly influence fluid flow in low-permeability porous media. There is evidence in the literature that the porosity and permeability of low-permeability porous media change with variations in the effective stress, which is called stress sensitivity. In this paper, a new mathematical model for pre-Darcy flow in low-permeability porous media is developed and validated with experimental data from the literature. The nonflowing boundary layer thickness can be obtained from the proposed model instead of the empirical equation. First, an equation for calculating the pore radius with stress sensitivity is derived. Two parameters ε p and ε r are defined to calculate the nonflowing boundary layer thickness. Second, based on the capillary bundle model, the apparent flow velocity and apparent liquid permeability of the porous media are determined. Finally, the stress sensitivity and boundary-layer effects on the apparent flow velocity and apparent liquid permeability are analyzed. The research results show that the effect of stress sensitivity on apparent flow velocity increases with increasing pore compressibility. When the pore compressibility C p >0 MPa−1, the apparent liquid permeability increases continuously with increasing pressure gradient. When the pore compressibility C p =0 MPa−1, the apparent liquid permeability continues to increase with increasing pressure gradient. The apparent liquid permeability eventually tends to a constant value. The apparent flow velocity decreases with ε p , and ε r decreases at a given pressure gradient. The larger ε p and ε r are, the faster the rate of increase in the apparent liquid permeability with increasing pressure gradient. The proposed model can estimate the apparent flow velocity at different pressure gradients with a high accuracy. This work is important for understanding flow phenomena in low permeability porous media, such as landslides caused by seepage of water in clay. • A low-velocity pre-Darcy flow model in low permeability porous media is developed. • The nonflowing boundary layer thickness was obtained from a new model. • The relationship between the boundary layer and the pressure gradient is established. • The effect of stress sensitivity on velocity and permeability is analyzed. • The effect of nonflowing boundary layer on velocity and permeability is analyzed. [ABSTRACT FROM AUTHOR]

As one of the most import planning problems in container port operation, the allocation of berth template to all vessels scheduled to call at the port is concerned. This paper investigates the berth template management for container port of waterway-waterway transit, which is different from traditional import and export container ports. Aiming to reduce the container transit distance between the quay side and the yard side, two main evaluation indicators are proposed to maximize the connection between mother vessels and feeder vessels. On this basis, a two-stage mathematical model with four optimization objectives is developed. Numerical experiments are also conducted to validate the effectiveness and efficiency of the proposed method, and scenario analysis also shows the management insights for the container port of waterway-waterway transit. [ABSTRACT FROM AUTHOR]

• A theoretical method is developed for analytical calculation of spin Chern number. • The effect of surface elasticity on dispersion and topological properties of phononic plate at nanoscale is examined. • Surface effect can be approximately seen as a comprehensive result of surface density and the residual stress. • The topologically protected interface mode is observed in the phononic plate at nanoscale. A new model with analysis for the propagation of flexural waves in a phononic plate at nanoscale is developed. The Gurtin-Murdoch theory for surface elasticity is adopted to model the surface heterogeneity. The Mindlin (or first-order) plate theory is further generalized to establish the governing equations for flexural waves in a phononic plate with surface effect, for which the plane wave expansion method is applied to derive the dispersion relation. A numerical model is developed using the finite element method and very good consistency between theory and numerical solution is observed. It is found that the surface density and the surface residual stress play the main role that affects the band structures. The surface effect can be approximately regarded as the competition between frequency decrease due to surface density and frequency increase caused by surface residual stress, which effectively increases the low-frequency bands but decreases the high-frequency bands. The quantum spin Hall effect is observed in the phononic plate at nanoscale, and the surface effect is studied numerically. By applying the k.p perturbation method, a theoretical framework is established to calculate the spin Chern number, which is an important topological invariant that determines the quantum spin Hall effect. Based on the topological analysis, an efficient waveguide with a zig-zag path is designed, in which a topologically protected wave in the interface state can robustly propagate along the path against disorders. The theory and numerical study developed in this paper will help better understand the size-dependent quantum spin Hall effect in nanostructures and it may also provide guidance for the design of topological wave devices at nanoscale. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• A novel mathematical model of tumor immune interactions system consisting of tumor cells, M1 and M2 macrophages is proposed. • The model captures two major functions of macrophages with both pro- tumor and anti-tumor effects. • Bifurcation diagrams of steady states are drawn in different parameters planes. • The sensitivity analysis is performed to illustrate the role of parameters with respect to tumor size. • The decay of tumors is not only the result of activation of M1 and M2, but also the effect of transition between M1 and M2. More and more evidences show that macrophages can induce both pro-tumor and anti-tumor effects. The study on genetically engineered macrophages to kill tumor cells has become a new direction for anti-cancer therapy in recent years. In this paper, we propose a mathematical model of interactions between tumor cells, M1 and M2 macrophages, and study the stability and bifurcations around the interior equilibrium. It is shown that the model exhibits stable periodic oscillations bifurcating from Hopf bifurcation, which indicates the long-term coexistence of tumor cells, M1 and M2 macrophages as well as long-term tumor relapse. Furthermore, sensitivity analysis is performed to illustrate the effect of parameters on tumor size. Our results show that an increase in ξ (the ratio of activation rates by tumor cells of M2/M1 macrophages) leads to a decrease of tumor cells, which can be explained that ξ has significant effects on γ 1 (the transition rate from M1 to M2 macrophages) and γ 2 (the transition rate from M2 to M1 macrophages). Hence, the decay of tumor cells is not only the result of direct activation of M1 and M2 macrophages by tumor cells, but also the combined effect of the transition between M1 and M2 macrophages. [ABSTRACT FROM AUTHOR]

• Error using only force in the constitutive characterization of heterogeneous strain. • Use of heterogeneous deformation field for accurate constitutive characterization. • Use of the non-conflicting concept to assess the performance of constitutive models. The mechanical characterization of thermoplastics submitted to finite strain is a non-trivial procedure since they may present necking and cold-drawing. These phenomena are associated with heterogeneous strain fields that may mask the real stress–strain curve and lead to mistaken conclusions about the capability of constitutive models to represent the material mechanical response. Aiming to shed light on this issue, this paper presents a numerical study based on a Finite Element Method Updating (FEMU) technique to obtain the true stress–strain curve of a thermoplastic specimen. FEMU technique is employed to characterize three elastoplastic models with different mathematical frameworks. Inverse problems are constructed considering force response and displacement data of a heterogeneous strain field on the specimen due to the necking and neck propagation kinematics. Results shown that even a very simple multilinear elastoplastic model, available in commercial software, is capable of representing force response of a tensile test when only experimental force data is considered. However, when the necking kinematics is taken into account, the studied models present different results and poor mechanical behavior representation, indicating that only the force data obtained from a tensile test is not enough to establish conclusions about the performance of a constitutive model when heterogeneous strain field occurs. Since none of the models was capable of accurately reproduce the experimental force and kinematics data, to evaluate which model performs better, it is proposed a multi-objective analysis of Pareto front results. [ABSTRACT FROM AUTHOR]

In this paper we study from a mathematical point of view the drug release and the degradation process in the context of biodegradable intravitreal implants. In particular, two different clinical situations are considered: non-vitrectomized and vitrectomized eyes. In the former case we assume that the vitreous humor is replaced by a saline solution or a silicone oil. In intravitreal space, the intravitreal liquid enters the implant by non-Fickian diffusion causing the degradation of the poly(lactic-co-glycolic acid) based implant. Then, drug in the implant dissolves and diffuses out of the polymeric matrix. The transport of drug in the vitreous chamber and retina is modeled by Fickian diffusion and convection generated by the flow of the vitreous humor. In order to numerically solve the system of partial differential equations that define the model, we propose an Implicit–Explicit finite element method that allows for the decoupling of the solution reducing the computational cost of the simulations. Several numerical experiments showing the effectiveness of the proposed numerical schemes are also included. The proposed mathematical model may be useful to optimize patient specific treatments in clinical practice. • A model for degradation and drug delivery from a PLGA ocular implant is proposed. • The model studies the effects of the LA and GA into the break of the polymeric chains. • Humor diffuses into the implant creating a non-Fickian mass flux. • Drug release occurs by diffusion associated to humor absorption and dissolution. • Stability analysis of the fully couple model. [ABSTRACT FROM AUTHOR]

The paper presents results of analysis of existing mathematical models for orbital debris fragments breakup in high velocity collisions. The breakup models are modified and updated taking into account the latest breakup criteria, experimental data and basic conservation laws. The model examples are analyzed, the criterion is developed for distinguishing fragments, which will stay in orbit after collision event. • Analysis of mathematical models for orbital debris fragments breakup is presented. • The breakup models are modified and updated. • Criterion for distinguishing fragments, which will stay in orbit, is developed. [ABSTRACT FROM AUTHOR]

• A novel mathematical model is developed. • The model is tested on the test problems. • Interval search ant colony algorithm is developed. • The results are compared with random search, improved ACO and GA • The proposed algorithm outperforms other algorithms. The use of robots is significantly increasing day by day in manufacturing systems, and especially improving the efficiency of the lines. Robots can be used to complete disassembly tasks, and each of the robots can need different operation times to perform the tasks. In this paper, the balancing of the robotic disassembly line problem has been studied to develop efficient solution techniques. Firstly, a mixed-integer linear mathematical model is proposed to determine and solve the problem optimally. A case study from literature is addressed to assess and show the efficiency and effectiveness of the model to minimize cycle time. Secondly, a heuristic algorithm based on ant colony optimization is also proposed to discover a solution for especially the large-size test problems due to the complexity of the problem. The performance of the proposed heuristic algorithm is verified and compared with the different heuristic on data sets. The computational results indicate that the proposed mathematical model and the algorithms are promising for the small and large-size test problems, respectively. Finally, it should be stated that robots have great potential to use in the area of disassembly line and useful solutions provide according to test results. [ABSTRACT FROM AUTHOR]

In order to make full use of the advantages of superheated steam (SHS), SHS injection in multi-point injection wells (MPIW) is proposed in this paper. Firstly, a mathematical model comprised of SHS flow model in inner tubing (IT) or long tubing (LT) and annulus, transient heat transfer model in oil layer is established. Secondly, type curves of SHS flow in MPIW is obtained by finite difference method on space and the iteration technique. Then, the effect of injection temperature on distributions of thermophysical properties of SHS in MPIW is discussed in detail. Results show that: (a) When the heat exchange between IT and annulus is taken into consideration. SHS temperature in IT has a decrease while SHS temperature in annulus has an increase. (b) With the help of MPIW, heating effect at both heel and toe points of the horizontal wellbores can be enhanced. (c) While the increase of SHS temperature certainly benefits the formation heating effect through the increase of both SHS temperature and superheat degree, the following decrease of SHS pressure in annulus will lead to the decrease of SHS absorption rate. This paper unravels some intrinsic flow characteristics of SHS in MPIW, which has a significant impact on the optimization of SHS injection parameters and analysis of heat transfer law in MPIW. [ABSTRACT FROM AUTHOR]

The frictional receding contact problem for two graded layers pressed by a rigid punch is considered in this paper. The punch is subjected to both normal and tangential loads thereby resulting in frictional contact with the upper layer. It is also assumed that the contact between the layers is frictional and the lower layer is fixed. It is further assumed that the gradation in the layers follows an exponential variation through the thickness with different profiles while Poissons ratios are taken as constants. Using standard Fourier transform, the contact problem is converted to a system of two singular integral equations in which the contact pressures and the contact widths are the unknowns. The integral equations are then solved numerically using Gauss–Jacobi integration formula. The Finite Element Method was additionally employed and both exponential and power law material gradation is used to solve the investigated problem and the obtained numerical and analytical results are in good agreement. The primary intention of this paper is to investigate the effect of material gradation, friction coefficients, layers thicknesses and material property mismatch at the interface between the layers on the contact pressures and contact widths. [ABSTRACT FROM AUTHOR]

Phase equilibrium, phase diagram and phase transformation of a solid that undergoes elastic-plastic deformation under non-hydrostatic stress conditions have technical and scientific significance, and numerous experimental and theoretical studies have been performed on this issue; however, a comprehensive theoretical description remains an unresolved problem. The crucial obstacle lies in seeking the phase equilibrium conditions, especially the formula of the general chemical potential. Duvall and Graham (1977) specified that it is impossible to construct a general Gibbs function, i.e. a general chemical potential, to define the equilibrium conditions for phase transformation when shear stress is present, except for some particular cases. This work focuses on the phase equilibrium problem of a solid-solid two-phase system, which permits elastic-plastic deformation under non-hydrostatic stress loading. We found the expression of the general chemical potential, which was often used in previous is not rigorous in logic. On the basis of a widely used approximation that the constitutive relationships between deviatoric stress and deviatoric elastic strain are linear, and the elastic coefficients depend only on pressure and temperature, a formula of the general chemical potential was derived in this paper. The result was found to be similar to that in hydrostatic thermodynamics as long as we substitute temperature T with an effective quantity T eff , which has the unit of temperature, and pressure P with another effective quantity P eff , which has the unit of pressure. The expressions of T eff and P eff are correlated with deviatoric elastic strain, elastic coefficients and the pressure and temperature partial derivatives of elastic coefficients. It is through the correlation between T eff and P eff and deviatoric quantities that the influence of deviatoric stress on phase equilibrium and phase transformation is imposed. In classical solid mechanics, the mechanical properties of a solid body are usually divided into two classes: volumetric properties and deviatoric properties. In addition, the deviatoric properties are thought to be affected by volumetric properties, but the volumetric properties are not influenced by deviatoric properties. Thus, the deviatoric and volumetric properties are standing unequal in classical solid mechanics. In contrast, the irrational inequality between volumetric and deviatoric properties has been successfully removed in the formulism proposed in this paper. For an isotropic solid system, the general Clausius-Clapyron relation was further deduced, which can be used to quantitatively calculate the shift in transition pressure caused by deviatoric stress. As an example of application, as well as verification, the formulism proposed in this paper was employed to quantitatively interpret the scatter in transition pressure of the α - ω transformation of titanium observed in experiments, which was commonly thought to have a relationship with non-hydrostatic stresses, but comprehensive quantitative theoretical interpretations are still needed. [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 describes Large Eddy Simulations of a turbulent premixed flame (the VOLVO rig) comparing Analytically Reduced Chemistry (ARC) with globally reduced chemistry for propane-air combustion, a dynamic Thickened Flame (TFLES) model with the usual non-dynamic TFLES model and a high-order Taylor Galerkin numerical scheme with a low-order Lax–Wendroff scheme. Comparisons with experimental data are presented for a stable case in terms of velocity and temperature fields. They show that going from two-step to ARC chemistry changes the flame stabilization zone. Compared to the usual non-dynamic TFLES model, the dynamic formulation allows to perform a parameter-free simulation. Finally, the order of accuracy of the numerical method is also found to play an important role. As a result, the high-order numerical method combined with the ARC chemistry and the dynamic TFLES model provides the best comparison with the experimental data. Since the VOLVO data base is used in various benchmarking exercises, this paper suggests that these three elements (precise chemistry description, dynamic parameter-free turbulent combustion model and high-order numerical methods) play important roles and must be considered carefully in any LES approach . [ABSTRACT FROM AUTHOR]

This paper deals with the spatial spreading speed and traveling wave solutions of a general epidemic model with nonlocal dispersal in time and space periodic habitats. It should be mentioned that the existence of spreading speed and traveling wave solutions of nonlocal dispersal cooperative system in space–time periodic habitats have been established previously. In this paper, we further show that the epidemic system has a spreading speed c ∗ ( ξ ) and for any c > c ∗ ( ξ ) , there exist a unique, continuous space–time periodic traveling wave solution ( Φ 1 ( x − c t ξ , t , c t ξ ) , Φ 2 ( x − c t ξ , t , c t ξ ) ) of epidemic model in the direction of ξ with speed c , and there is no such solution for c < c ∗ ( ξ ) . [ABSTRACT FROM AUTHOR]

Time-Series data has been of great importance to the research field of prediction models. Over the past two decades, multitudinous fuzzy time series blueprints have been put forth for agricultural yield production. However, most of these predictions were based on 7th interval partitioning. A surprising insight was that nobody gave a sound reason to justify the choice of that particular interval. So, this paper focuses on predicting data values on a large spectrum of fuzzy logic computations based on second and third-degree relationships. This paper showcases work on 4 different types of the fuzzy interval, where each interval is tested with 4 degrees of regression equations. Each of these 16 cases is performed for the fuzzy logic relationship (FLR) 2 and 3 separately. Apart from this, the robustness of algorithm is a testament to an incredible solution for the time series model. In addition to this, A Regression analysis model has been enforced to accomplish the efficient defuzzification operation. To elucidate the process of forecasting, the historical data of wheat yield of University of Agriculture and Technology has been used. [ABSTRACT FROM AUTHOR]

The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith’s theory of cracks, is applied to the problem of arbitrary crack growth in 2D. The proposed formulation enables minimisation of the total energy of the mechanical system with respect to the crack extension directions and crack extension lengths to solve for the evolution of the mechanical system over time. The three parts focus, in turn, on (I) the theory of multiple crack growth including competing cracks, (II) the discrete solution by the extended finite element method using the minimum-energy formulation, and (III) the aspects of computer implementation within the Matlab programming language. The key contributions of Part-I of this three-part paper are given as follows. (1) Formulation of the total energy functional governing multiple crack behaviour. (2) Three solution methods to the problem of competing crack growth for different fracture front stabilities, e.g. stable, unstable, or partially stable crack tip configurations; we compare our approach to Budyn et al. (2004) and demonstrate via example cases that the latter approach of resolving competing crack growth is not energy minimal in some cases. Finally, (3), the minimum energy criterion for a set of crack tip extensions is posed as the condition of vanishing rotational dissipation rates with respect to the extension angles. The proposed formulation lends itself to a straightforward application within a discrete framework involving multiple finite-length crack tip extensions. The open-source Matlab code, documentation, benchmark/example cases are included as supplementary material. [ABSTRACT FROM AUTHOR]

This paper deals with a fully parabolic chemotaxis-growth system with singular sensitivity u t = Δ u − χ ∇ ⋅ u ∇ ln v + r u − μ u 2 , ( x , t ) ∈ Ω × ( 0 , ∞ ) , v t = Δ v − v + u , ( x , t ) ∈ Ω × ( 0 , ∞ ) , under homogeneous Neumann boundary conditions in a smooth bounded domain Ω ⊂ R 2 , where the parameters χ , μ > 0 and r ∈ R . Global existence and boundedness of solutions to the above system were established under some suitable conditions by Zhao and Zheng (2017). The main aim of this paper is further to show the large time behavior of global solutions which cannot be derived in the previous work. [ABSTRACT FROM AUTHOR]

Numerical simulations of film boiling heat transfer on a horizontal surface are conducted in this paper using a modified pseudo-potential liquid-vapor phase change lattice Boltzmann model. A conjugate heat transfer problem, including heat conduction in the heater and its thermal responses during the film boiling process, is investigated. Unlike previous numerical studies which needed to initialize the shape of the liquid-vapor interface wave at the beginning of the computation, the computation domain for fluid region is occupied initially by saturated liquid in this paper. Taylor instability at the liquid-vapor interface is triggered by small temperature perturbations imposed at the bottom of the heater during a short initial period. Consequently, this paper represents a more direct and complete numerical simulation for film boiling heat transfer on a horizontal heater. The simulated time- and space-averaged Nusselt number is found in good agreement with a previous correlation equation. Temporal and spatial variations of the vapor film thickness are also investigated numerically and compared with existing correlation equations. It is demonstrated that the temperature at the top surface of the heart changes with position and time during the film boiling process. Although the transient film boiling patterns may depend on temperature perturbations imposed on he bottom of the heater during an initial period, the time- and space-averaged film boiling heat flux is independent of initial temperature perturbations. [ABSTRACT FROM AUTHOR]

This paper presents the Korea Superconducting Tokamak Advanced Research (KSTAR) Real-Time Data Archiving System (RTDAS) for a real-time network. In most fusion experiments, a stable and low latency real-time network is essential for achieving real-time controllability. Inspecting and supervising the operation of a real-time network is essential for ensuring its stability. Archiving the network data makes it possible to analyze the performance and status of a network. In the KSTAR, RTDAS has been developed to monitor and archive real-time network data that is used to control the plasma and send diagnostic data to Plasma Control System (PCS) in real-time to ensure the stable operation of the real-time network. The KSTAR adopts reflective memory (RFM) as a real-time network and this paper presents the algorithm of the real-time data archiving system and the experimental results of this system. The real-time data archiving system operates in two phases. During the experiment, the archiving system stores data from these real-time networks in real-time. After the experiment is finished the system sends this archived data to the MDSplus data server; this system stores all data in accordance with the KSTAR timing system. Therefore, all data is synchronized with the KSTAR timing system. This system is configured with Experimental Physics and Industrial Control System (EPICS) and Asynchronous Driver Support (AsynDriver). This system operates in real-time, was implemented on Messaging Realtime Grid -Real time (MRG-R) kernel 3.10, and uses Multi-Core Utilities (MCoreUtil). The system was tested to validate the performance of this archiving system; the test results show this system’s real-time performance. [ABSTRACT FROM AUTHOR]

This paper proposes a production and differential pricing decision model in a two-echelon supply chain that involves a demand from two or more market segments. In this framework, the retailer is allowed to set different prices during the planning horizon. While integrated production-marketing management has been a key research issue in supply chain management for a long time, little attention has been given to set prices and marketing expenditures in integrated multi-site (parallel) manufacturing systems and multiple demand classes. Generally, the presence of multiple demand classes induced by different market segments may impose demand leakage and then change production plan and ordering policies throughout the supply chain system. To tackle this problem, this paper develops a novel approach in order to provide an optimal aggregate production and marketing plan by interconnecting the sales channels of the retailer and demand. A non-linear model is established to determine optimal price differentiation, marketing expenditures and production plans of manufacturing sites in a multi-period, multi-product and multi-sale channels production planning problem by maximizing total profit of the supply chain. To handle the model and obtain solutions, we propose an efficient analytical model based upon convex hulls. Finally, we apply the proposed procedure to a clothing company in order to show usefulness and significance of the model and solution method. [ABSTRACT FROM AUTHOR]

In this paper, a fundamental approach to analyzing the maneuverability of spacecraft with mounted control moment gyros is addressed by searching feasible angular momentum. The geometrical array of control moment gyros considered is a roof array also known as a 2-SPEED system . Due to the simplicity of the singularity envelope of the array considered, it is reasonably practical to conduct rotational performance analysis of the spacecraft. This maneuverability analysis technique uses a unique chart developed in this work, which allows a guaranteed maximum torque output and angular momentum at any time without concern about the singularity problem of the control moment gyros. Therefore, the purpose of this paper is to provide a conservative method for maneuverability analysis of a spacecraft with installed control moment gyros by searching allowable maximum angular momentum. This method is demonstrated using an illustrative example. [ABSTRACT FROM AUTHOR]

In the context of geothermal applications, the thermal response of the ground is a primary concern. Many models use the concept of g-function introduced by Eskilson in the eighties. These functions were associated with a special field arrangement and libraries of tabulated values were pre-calculated and made available for simulation. In order to increase the flexibility, several analytical models were recently proposed and the model of Cimmino and Bernier is the most precise of such models. In their approach, they split each borehole into segments where they assume an unknown constant heat flux. In this paper, we modify their approach where we replace the piecewise-constant heat flux profile assumption by a piecewise-linear distribution. Doing so, it is possible to achieve the same precision with fewer segments in the model. The model needs however a new mathematical treatment of the thermal response which is developed in the present paper. Comparison between both approaches and original Eskison g-function is done. [ABSTRACT FROM AUTHOR]

This paper introduces a novel approach for controlling the operational ventilation in complex road tunnels. Basically, the control structure is feed-forward with an adaptive logic. The feed-forward part includes the static optimization which uses the mathematical model of airflow dynamics. The adaptive logic is based on the recursive least squares with exponential forgetting, which compensates deviations between the mathematical model and real measured data, and thus provides a feedback. During the standard operation of road tunnels, requirements to maintain indoor air quality (IAQ) and protect the surrounding area of a tunnel from pollution, are necessary. Moreover, reducing electricity costs is desirable, as the ventilation in road tunnels forms a significant part of electricity costs. The control scheme has been validated through the long-term evaluation of operation in the Blanka tunnel complex in Prague, Czech Republic, which is the largest city tunnel in Central Europe. The experimental validation of the proposed control scheme is the main contribution of the paper. [ABSTRACT FROM AUTHOR]

Simulating multi-body dynamics with both rigid and flexible parts and with frictional contacts is a hard problem. We solve this by expressing the couplings between the bodies as position level constraints. The implicit treatment of the constraint directions gives us improved stability over velocity based methods. Then by employing regularization of nonlinear constraints and a convex minimization formulation, we bridge constraint-based methods to traditional force-based methods. In fact, the former are just a dual variables formulation of the latter. We solve this dual problem using position based dynamics (PBD). We show how PBD is a completely valid modeling technique and we extend it with an accurate contact and Coulomb friction model. We further show for the first time how the same solver can be used to simulate both rigid and deformable solids with two way coupling. For the soft bodies we introduce a novel form of linear finite elements expressed as constraints, that is more accurate than PBD mass-spring systems. More of our results include the energy conserving Newmark integrator and the accelerated Jacobi solver suitable for parallel architectures. Note that this paper is an extended and revised version of the conference paper published in [1]. [ABSTRACT FROM AUTHOR]

The mechanical performance of a spatial structure is strongly influenced by the structural configuration. A generalized shape optimization algorithm is proposed to enhance the structure’s stiffness in this paper. The nodal coordinates are treated as the design variables during the optimization process. At each iteration, based on the sensitivity analysis all the free nodes are moved along certain directions to reduce the compliance. A volume adjustment scheme is applied to satisfy the volume constraint. Jagged surfaces are automatically smoothed during the volume adjustment process and therefore no extra smoothing procedure is needed. A variety of 2D and 3D examples are presented to verify the effectiveness and the validity of the proposed method. It is shown that the new node-shifting method developed in this paper can be used for finding optimal shapes of general reticulated spatial structures including those with cantilevered parts where traditional inverse hanging method would fail. [ABSTRACT FROM AUTHOR]

This paper provides a companion study to a previous paper by the same author (Virgin, 2017). In that paper, 3D printing was used to provide a hands-on experience for students of (linear) structural analysis based on the lateral stiffness of plane frames. In this paper, a related set of structural plane frames is investigated in terms of their natural frequencies, perhaps the fundamental feature in structural dynamics. Again, a 3D printer is used to provide a variety of parameter variations, and the extent to which certain simplifying analytical assumptions are justified is assessed. [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]

In Jung and Roh (2017), we investigated some properties of approximate solutions of the second-order inhomogeneous linear differential equations. In this paper as an application of above paper we will study the stability of the time independent Schrödinger equation with a potential box of finite walls. [ABSTRACT FROM AUTHOR]

This paper deals with the study of a nonlinear eigenvalue problem driven by a new class of non-homogeneous differential operators with variable exponent and involving a nonlinear term with variable growth. The framework in the present paper corresponds to the case of small perturbations of the nonlinear term. Combining variational arguments with energy estimates, we establish the existence of eigenvalues in a neighborhood of the origin. Our abstract setting includes several models described by nonhomogeneous differential operators, including the case of the capillarity equation. [ABSTRACT FROM AUTHOR]

Bounding hulls such as convex hull, α -shape, χ -hull, concave hull, crust, etc. offer a wide variety of useful applications. In this paper, we explore another bounding hull, namely α -concave hull, as a generalization of convex hull. The parameter α determines the smoothness level of the constructed hull on a set of points. We show that it is NP-hard to compute α -concave hull on a set of points for any 0 < α < π . This leads us to a generalization of Fekete work (when α = π ). We also introduce α − M A C P as an NP-hard problem similar to the problem of computing α -concave hull and present an approximation algorithm for α − M A C P . The paper ends by implementing the proposed algorithm and comparing the experimental results against those of convex hull and α -shape models. [ABSTRACT FROM AUTHOR]

A numerical investigation on cold-formed high strength steel (HSS) tubular beams is presented in this paper. The nominal 0.2% proof stresses of the HSS sections ranged from 700 MPa to 1100 MPa. In the complementary study [1], experimental investigation on the beam specimens have been performed. In the present study, numerical modelling methodology for beams was first validated and parametric study on the cold-formed HSS tubular beams was conducted. A total of 423 numerical data was obtained to investigate the structural performance of HSS tubular beams. The experimental and numerical results were then compared with the codified design guidelines from ANSI/AISC 360-10 [2], EN 1993-1-1 [3], AS 4100 [4] and AISI S100 [5] in addition to the predictions from Direct Strength Method (DSM) for square hollow sections (SHS), rectangular hollow sections (RHS) and circular hollow sections (CHS). The codified slenderness limits for sections subjected to bending were examined. Improvements on the design guidelines are proposed in this paper. [ABSTRACT FROM AUTHOR]

Material non-linearity of pier members is an important factor that needs to be considered for dynamic analysis of the bridge pier subjected to barge impact. However, many existing studies pertaining to barge impact on the bridge pier are based on the assumption that the pier is rigid or elastic. High-resolution finite-element simulation serves as the main strategy for dynamic analysis of the bridge pier subjected to barge impact considering material non-linearity of pier members. However, high-resolution finite-element simulations are expensive regarding both calculation time and computing resources, thus efficient models are often required. This paper develops the numerical model of the square RC pier column with fixed base. By coupling the simplified mass-spring model developed by the authors previously with the RC pier column at the impact position using fibre beam elements, the efficient model is developed to predict the impact force time-history and dynamic responses of the RC pier column subjected to barge impact. The studies in this paper show that the prediction quality of the proposed efficient model is adequate for different impact scenarios. [ABSTRACT FROM AUTHOR]

A lot of research has been carried out to explain the manner in which longitudinal moments of a bridge respond to traffic. The total longitudinal bending moment is made of ‘static’ and ‘dynamic’ components, which vary with time as a result of the inertial forces of the bridge and changes in value and point of application of the forces of the vehicle. However, there is limited evidence about how bending moments at planes other than longitudinal, or twisting moments, act in response to a moving vehicle. For the first time in the literature, this paper analyses the total resultant moments (‘static’ + ‘dynamic’) for any plane orientation (from 0 to 360°) at any location of a solid slab deck due to the crossing of a vehicle. The bridge is modelled as a simply supported straight orthotropic plate and the vehicle is modelled as a three-dimensional 5-axle articulated system composed of interconnected sprung and unsprung masses. Simulations are performed for three vehicle transverse paths and three speeds. Using Wood and Armer equations, the resultant moment at any plane orientation can be obtained from equilibrium of bending and twisting moments acting on longitudinal and transverse planes. Maximum twisting moments develop in planes at 45° with longitudinal and transverse planes. Bending moments reach maximum and minimum values at longitudinal and transverse planes. Nevertheless, the moments acting on other plane orientations cannot be ignored in order to accurately assess whether the moment capacity of the bridge provides adequate safety. Therefore, the amount of slab reinforcement will be sufficient provided that the moment capacity exceeds the applied moment for any location and plane. Critical locations with highest values of sagging, hogging and twisting are identified in the bridge, and the dynamic amplification associated to the applied moments is evaluated. Bridge codes such as the Eurocode employ a unique built-in dynamic amplification factor for moment that depends only on the bridge length and the number of lanes. This paper shows how to perform an improved assessment allowing for changes in dynamic behaviour with location and plane orientation, which may prevent needless expense in bridge rehabilitation. [ABSTRACT FROM AUTHOR]

A fraction-order total variation blind image restoration algorithm based on L1-norm was proposed for restoring the images blurred by unknown point spread function (PSF) during imaging. According to the form of total variation, this paper introduced an arithmetic operator of fraction-order total variation and generated a mathematical model of cost. Semi-quadratic regularization was used to solve the model iteratively so that the solution of this algorithm became easier. This paper also analyzed the convergence of this algorithm and then testified its feasibility in theory. The experimental results showed the proposed algorithm can increase the PSNR of the restored image by 1 dB in relation to the first order total variation blind restoration method and Bayesian blind restoration method. The details in real blurred image were also pretty well restored. The effectiveness of the proposed algorithm revealed that it was practical in the blind image restoration. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic organic Rankine cycle waste heat recovery (ORC-WHR) Simulink® model and an engine model for heavy-duty diesel applications. The dynamic, physics-based ORC-WHR system model includes parallel evaporators, flow control valves, a turbine expander, a reservoir, and pumps. The evaporator model contains an enhanced pressure drop model, which calculates pressure drop for each working fluid phase via a linear relation to the axial location inside each phase. The ORC-WHR component models parameters are identified over large range of steady state and transient experimental data, which are collected from an ORC-WHR system on a 13 L heavy-duty diesel engine. The component models are integrated into an entire system model and the boundary conditions, inputs and outputs for the individual models are described. A GT-POWER® engine model and its transient validation is presented. The speed and torque profiles of a long-haul, constant speed variable-load heavy-duty cycle are processed through the engine model to produce the exhaust and recirculated exhaust gas transient conditions relevant for the ORC model. The ORC-WHR system then simulated over these highly transient engine conditions. Overall, this paper provides detailed guidelines for ORC-WHR system modeling, model calibration, and component models integration. [ABSTRACT FROM AUTHOR]

Typed models of connector/component composition specify interfaces describing ports of components and connectors. Typing ensures that these ports are plugged together appropriately, so that data can flow out of each output port and into an input port. These interfaces typically consider the direction of data flow and the type of values flowing. Components, connectors, and systems are often parameterised in such a way that the parameters affect the interfaces. Typing such connector families is challenging. This paper takes a first step towards addressing this problem by presenting a calculus of connector families with integer and boolean parameters. The calculus is based on monoidal categories, with a dependent type system that describes the parameterised interfaces of these connectors. We use families of Reo connectors as running examples, and show how this calculus can be applied to Petri Nets and to BIP systems. The paper focuses on the structure of connectors— well-connectedness —and less on their behaviour, making it easily applicable to a wide range of coordination and component-based models. A type-checking algorithm based on constraints is used to analyse connector families, supported by a proof-of-concept implementation. [ABSTRACT FROM AUTHOR]

The distribution system is demanded to be more efficient, more flexible and more intelligent due to the continued growth of the electricity loads, the high efficiency of energy utilization and the environmental protection. The traditional distribution systems are facing the challenge of evolving from passive networks to the active distribution networks (ADN) with the integration of multiple controllable resources. This paper presents an optimal operation and schedule model of the ADN, considering a variety of controllable resources such as distributed generations, battery storages and interruptible loads. To solve the optimization problem, a modified fuzzy adaptive PSO assisted by Kriging model (KMA-MFAPSO) is developed in this paper. In KMA-MFPSO, a novel constraint handling technique (CHT) based on the PSO is proposed to handle the constraints effectively. In addition, under the premise of ensuring the accuracy of the calculation, the Kriging model is used in KMA-MFAPSO to calculate the power flow the ADN approximately, which greatly speeds up the solving process. Finally, the effectiveness of the proposed algorithm is tested on a modified IEEE-123 system. The optimal results obtained by the proposed method are compared with the results obtained by using other solving algorithms. The simulation results indicate that KMA-MFAPSO is very robust and fast to solve the optimization problem so that it can be used in practical systems. [ABSTRACT FROM AUTHOR]

Modern organizations execute processes to deliver product and services, whose enactment needs to adhere to laws, regulations and standards. Conformance checking is the problem of pinpointing where deviations are observed. This paper shows how instances of the conformance checking problem can be represented as planning problems in PDDL (Planning Domain Definition Language) for which planners can find a correct solution in a finite amount of time. If conformance checking problems are converted into planning problems, one can seamlessly update to the recent versions of the best performing automated planners, with evident advantages in term of versatility and customization. The paper also reports on results of experiments conducted on two real-life case studies and on eight larger synthetic ones, mainly using the Fast-downward planner framework to solve the planning problems due to its performances. Some experiments were also repeated though other planners to concretely showcase the versatility of our approach. The results show that, when process models and event logs are of considerable size, our approach outperforms existing ones even by several orders of magnitude. Even more remarkably, when process models are extremely large and event log traces very long, the existing approaches are unable to terminate because they run out of memory, while our approach is able to properly complete the alignment task. [ABSTRACT FROM AUTHOR]

This paper is devoted to the existence of the traveling waves of the equations describing a diffusive SEIR model with non-local reaction between the infected and the susceptible. The existence of traveling waves depends on the basic reproduction rate S − ∞ β / γ and the minimal speed. We use the Schauder fixed point theorem and the Laplace transform to get the existence and non-existence of traveling waves in our paper. We also give some numerical results of the minimal wave speed. [ABSTRACT FROM AUTHOR]

Attitude estimation plays a major role in the autonomy of unmanned aerial vehicles and requires fusion of different sensor measurements. This paper describes an adaptive estimation scheme in which the weight parameter for the complementary filter (CF) is varied over time. The adaptive mechanism proposed here is inspired from the multiple model adaptive estimation (MMAE) scheme used for varying noise parameters in the Kalman filter structure. In this paper, the linear complementary filters are used as elementary blocks in the MMAE structure and their weights are modified probabilistically to obtain an accurate orientation estimate. It avoids the problem of manual selection of weight factor for complementary filter and provides a robust orientation estimate against varying system dynamics. The proposed MMAE based adaptive CF scheme is modular in nature and is dependent on the residual error between estimated and the measured orientation angle. It is applied on the real world datasets logged from inertial sensors and the performance of MMAE based CF structure is found to work promisingly as compared to the non-linear complementary filter versions and the extended Kalman filter framework. [ABSTRACT FROM AUTHOR]

The thermal performance of a novel solar air collector with metal corrugated packing in the buildings of cold regions is studied in this paper. Mathematical models are developed to investigate the thermal performance of the collector and the results are verified by experiments. The hydraulic analysis is conducted experimentally to study the pressure drops of the air flows in the corrugated packing. Effects of the structural and operating parameters, such as the collector width, height, specific surface area and solar radiation intensity, ambient air temperature, air inlet temperature and velocity are studied to optimize the thermal performance of the collector. Comparisons are conducted among the metal corrugated packing solar air collector, the unglazed transpired solar collector, the glazed transpired solar collector and the packed bed solar collector with iron chips. The results indicate that the metal corrugated packing solar air collector is more appropriate to be used in the rural buildings of cold regions for its advantages of large heat transfer area, high heat transfer coefficient and good economic performance. [ABSTRACT FROM AUTHOR]

Background: As a new application technology of the Internet of Things (IoT), intelligent medical treatment has attracted the attention of both nations and industries through its promotion of medical informatisation, modernisation, and intelligentisation. Faced with a wide variety of intelligent medical terminals, consumers may be affected by various factors when making purchase decisions.Purpose: To examine and evaluate the key influential factors (and their interrelationships) of consumer adoption behavior for improving and promoting intelligent medical terminals toward achieving set aspiration level in each dimension and criterion.Method: A hybrid modified Multiple Attribute Decision-Making (MADM) model was used for this study, based on three components: (1) the Decision-Making Trial and Evaluation Laboratory (DEMATEL) technique, to build an influential network relationship map (INRM) at both 'dimensions' and 'criteria' levels; (2) the DEMATEL-based analytic network process (DANP) method, to determine the interrelationships and influential weights among the criteria and identify the source-influential factors; and (3) the modified Vlse Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, to evaluate and improve for reducing the performance gaps to meet the consumers' needs for continuous improvement and sustainable products-development. First, a consensus on the influential factors affecting consumers' adoption of intelligent medical terminals was collected from experts' opinion in practical experience. Next, the interrelationships and influential weights of DANP among dimensions/criteria based on the DEMATEL technique were determined. Finally, two intelligent medicine bottles (AdhereTech, A1 alternative; and Audio/Visual Alerting Pillbox, A2 alternative) were reviewed as the terminal devices to verify the accuracy of the MADM model and evaluate its performance on each criterion for improving the total certification gaps by systematics according to the modified VIKOR method based on an INRM.Results: In this paper, the criteria and dimensions used to improve the evaluation framework are validated. The systematic evaluation in index system is constructed on the basis of five dimensions and corresponding ten criteria. Influential weights of all criteria ranges from 0.037 to 0.152, which shows the rank of criteria importance. The evaluative framework were validated synthetically and scientifically. INRM (influential network relation map) was obtained from experts' opinion through DEMATEL technique shows complex interrelationship among factors. At the dimension level, the environmental dimension influences other dimensions the most, whereas the security dimension is most influenced by others. So the improvement order of environmental dimension is prior to security dimension. The newly constructed approach was still further validated by the results of the empirical case, where performance gap improvement strategies were analyzed for decision-makers. The modified VIKOR method was especially validated for solving real-world problems in intelligent medical terminal improvement processes. For this paper, A1 performs better than A2, however, promotion mix, brand factor, and market environment are shortcomings faced by both A1 and A2. In addition, A2 should be improved in the wireless network technology, and the objective contact with a high degree of gaps.Conclusions: Based on the evaluation index system and the integrated model proposed here, decision-makers in enterprises can identify gaps when promoting intelligent medical terminals, from which they can get valuable advice to improve consumer adoption. Additionally, an INRM and the influential weights of DANP can be combined using the modified VIKOR method as integrated weightings to determine how to reduce gaps and provide the best improvement strategies for reaching set aspiration levels. [ABSTRACT FROM AUTHOR]

Pile foundations are usually used when the conditions of the upper soil layers are weak and unable to support the super-structural loads. Piles carry these super-structural loads deep into the ground. Therefore, the safety and stability of pile-supported structures depends largely on the behavior of the piles. In addition, accurate prediction of pile behavior is necessary to ensure appropriate structural and serviceability performance. In this paper, an ANN model is developed for predicting pile behavior based on the results of cone penetration test (CPT) data. Approximately 500 data sets, obtained from the published literature, are used to develop the ANN model. The paper compares the predictions obtained by the ANN with those given by a number of traditional methods and it is observed that the ANN model significantly outperforms the traditional methods. An important advantage of the ANN model is that the complete load-settlement relationship is captured. Finally, the paper proposes a series of charts for predicting pile behavior that will be useful for pile design. [ABSTRACT FROM AUTHOR]

Space robots can perform some tasks in harsh environment as assistants of astronauts or substitutions of astronauts. Taking the limited working time and the arduous task of the astronauts in the space station into account, an astronaut assistant robot (AAR-2) applied in the space station is proposed and designed in this paper. The AAR-2 is achieved with some improvements on the basis of AAR-1 which was designed before. It can exploit its position and attitude sensors and control system to free flight or hover in the space cabin. And it also has a definite environmental awareness and artificial intelligence to complete some specified tasks under the control of astronauts or autonomously. In this paper, it mainly analyzes and controls the 6-DOF motion of the AAR-2. Firstly, the system configuration of AAR-2 is specifically described, and the movement principles are analyzed. Secondly, according to the physical model of the AAR-2, the Newton - Euler equation is applied in the preparation of space dynamics model of 6-DOF motion. Then, according to the mathematical model's characteristics which are nonlinear and strong coupling, a dual closed loop position and attitude controller based on fuzzy sliding mode control is proposed and designed. Finally, simulation experiments are appropriate to provide for AAR-2 control system by using Matlab/Simulink . From the simulation results it can be observed that the designed fuzzy sliding mode controller can control the 6-DOF motion of AAR-2 quickly and precisely. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) is the terminology applied where the actions of microorganisms influence the corrosion process. In literature, terms such as microbial corrosion, biocorrosion, microbially influenced/induced corrosion, and biodegradation are often applied. MIC research in the oil and gas industry has seen a revolution over the past decade, with the introduction of molecular microbiological methods: (MMM) as well as new industry standards and procedures of sampling biofilm and corrosion products from the process system. This review aims to capture the most important trends the oil and gas industry has seen regarding MIC research over the past decade. The paper starts out with an overview of where in the process stream MIC occurs − from the oil reservoir to the consumer. Both biotic and abiotic corrosion mechanisms are explained in the context of managing MIC using a structured corrosion management (CM) approach. The corrosion management approach employs the elements of a management system to ensure that essential corrosion control activities are carried out in an effective, sustainable, well-planned and properly executed manner. The 3-phase corrosion management approach covering of both biotic and abiotic internal corrosion mechanisms consists of 1) corrosion assessment, 2) corrosion mitigation and 3) corrosion monitoring. Each of the three phases are described in detail with links to recent field cases, methods, industry standards and sampling protocols. In order to manage the corrosion threat, operators commonly use models to support decision making. The models use qualitative, semi-quantitative or quantitative measures to help assess the rate of degradation caused by MIC. The paper reviews four existing models for MIC Threat Assessment and describe a new model that links the threat of MIC in the oil processing system located on an offshore platform with a Risk Based Inspection (RBI) approach. A recent field case highlights and explains the conflicting historic results obtained through serial dilution of culture media using the most probable number (MPN) method as compared to data obtained from corrosion monitoring and the quantitative polymerase chain reaction (qPCR) method. Results from qPCR application in the field case have changed the way MIC is monitored on the oil production facility in the North Sea. A number of high quality resources have been published as technical conference papers, books, educational videos and peer-reviewed scientific papers, and thus we end the review with an updated list of state-of-the-art resources for anyone desiring to become more familiar with the topic of MIC in the upstream oil and gas sector. [ABSTRACT FROM AUTHOR]

Pumped hydro energy storage (PHES) has made significant contribution to the electric industry. Towards the improvement of this energy storage technology, a novel concept, known as gravity energy storage, is under development. This paper addresses the dynamic modeling of this storage system. A mathematical model is needed for descripting the hydraulic components of gravity storage as they include various time variant parameters. The objective of this paper is to build a robust model that simulates the dynamics of gravity storage system. This work concentrates on the hydraulic dynamics of the system rather than investigating the dynamics of the mechanical equipment such as turbine, and synchronous machine. The proposed model has been implemented in Matlab/Simulink, and demonstrated by a case study. The dynamic simulation is carried out to gain insight into the performance of the system. The model can predict the volume and the pressure of both chambers, as well as the piston motion throughout the charging and the discharging of the storage system. [ABSTRACT FROM AUTHOR]