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Abstract: By analyzing COSMIC data, found more than 50% reduction in electron density during a solar eclipse at the F2-layer and above, with the peak of ∼70% at 370km. So great eclipse effect on topside ionosphere was very abnormal and much different from previous studies. However, by comparing the cosmic data with IRI results, we find that the abnormal reduction comes mainly from the significant local time variation at sunrise, not from the eclipse effect. Furthermore, we simulated the eclipse effect by using a theoretical model to confirm our analysis. [Copyright &y& Elsevier]

This paper aims to investigate the stability of hydro-turbine governing system (HTGS) with sloping ceiling tailrace tunnel (SCTT) and upstream surge tank (UST) considering nonlinear hydro-turbine characteristics (NHTCs). Firstly, the mathematical model of HTGS is presented based on nonlinear seventh-order state equation, which is verified by example analysis so as to study the stability of HTGS. Subsequently, the effect of HTGS parameters on the stability of the system is investigated with numerical simulation. Finally, the coupling effect mechanism of SCTT and UST on stability under the effect of NHTCs is revealed by using contrastive analysis. The results are summarized as follows: (1) T a , K d and T wt perform larger effect on the stability of HTGS, while the influence of F and T wy is mild; (2) the NHTCs are beneficial under negative load disturbance and unfavorable under positive load disturbance for the stability and dynamic performance of HTGS; (3) the coupling effect of SCTT and UST outperforms the results of SCTT or UST alone under all load disturbances; (4) the incorporation of UST to the established model plays a certain role in stability compensation, while the introduction of SCTT not only improves the stability but also achieves smaller amplitude and lower frequency. [ABSTRACT FROM AUTHOR]

• The mathematical model on the grounding resistance of the vertical electrode is proposed. • Accuracy of the mathematical model is proved by computer simulation analysis and the field measurement examination in this paper. • The mathematical model can be used in the design of vertical grounding electrode effectively. In this paper, a mathematical model on the grounding resistance of vertical electrode is proposed. The proposed mathematical model is modeled with consideration of the effects of parameters such as the length and diameter of vertical electrode, the soil resistivity and the embedding depth. This mathematical model can be applied effectively to the design of grounding system using vertical electrode in harmonious soil with the resistivity values less than 900Ω∙m. The accuracy of proposed model is proved by the simulation analysis and measurement examination of the electric field in this paper. [ABSTRACT FROM AUTHOR]

In high-power laser systems, the large-aperture continuous phase plates (CPPs) are designed and fabricated with continuous varying structured topography to serve as the class of phase-modulating beam-conditioning optics. To achieve better optical performance, its fabrication highly depends on the reiterative figuring to eliminate the form error relative to the designed CPP surface. However, the characteristics of large aperture and complex structured topography make the quality inspection of CPPs still challenging. A typical inspection process includes measuring the CPPs with the sub-aperture stitching technique, followed by the characterization procedure with respect to the CPP design description. This paper proposes an innovative stitching-embedded characterization method for imprinting the large-aperture CPPs, which combines the sub-aperture stitching and characterization procedure together. First, the concept and mathematical model of the stitching-embedded characterization method is presented. Then, both numerical simulations and experiments were undertaken to verify the proposed method, and the results demonstrate its feasibility and reasonability to provide the more reliable form error evaluation while simplify the analysis procedure compared with the conventional inspection process. • The stitching-embedded characterization method is presented for imprinting the large-aperture CPPs. • The mathematical model is established to integrate the sub-aperture stitching into the characterization procedure. • Numerical simulations were undertaken to verify the proposed method, which can achieve sub-nanometer accuracy in simulation. • In application, the proposed method can achieve more reliable form error evaluation with lower time cost. [ABSTRACT FROM AUTHOR]

This paper considers an optimal control problem of large-scale gas supply systems. Solving this problem, we must take into account line packing in systems modeling. For unsteady-state gas flow modeling, a lumped-parameter model is proposed. On the base of this model the paper elaborates a system of ordinary differential equations to imitate unsteady-state gas flow in pipeline system of selectable configuration and provides the integration algorithm using the global gradient method. Adduced an example of calculating a circuitous gas supply system demonstrates the adequacy of the proposed model. The paper includes the mathematical formulation of a technical diagnostics problem of large pipeline system equipment in case of unsteady-state gas flow. The estimation of technical state is reduced to the constrained optimization problem. On the base of the lumped parameters model, we propose an algorithm of the solution of this problem and use it for identification of the gas supply system of selectable configuration. The numerical experiments demonstrate that the algorithm converges with good speed. The paper contains a description of an optimal control concept of large-scale pipeline system. Stated ideas can be applied in case of the system collapse. • For unsteady-state gas flow modeling a lumped-parameter model is proposed. • A method for integrating this system is recommended. • A method for estimating parameters of gas transportation system model is proposed. • A concept of large pipeline system control is described. [ABSTRACT FROM AUTHOR]

This paper presents a quasistatic problem of an elastic body in frictional contact with a moving foundation. The model takes into account wear of the contact surface of the body caused by the friction. We recall existence and uniqueness results obtained in Sofonea et al. (2017). The main aim of this paper is to present a fully discrete scheme for numerical approximation together with an error estimation of a solution to this problem. Finally, computational simulations are performed to illustrate the mathematical model. [ABSTRACT FROM AUTHOR]

In wet-lab experiments, the slime mold Physarum polycephalum has demonstrated its ability to tackle a variety of computing tasks, among them the computation of shortest paths and the design of efficient networks. For the shortest path problem, a mathematical model for the evolution of the slime is available and it has been shown in computer experiments and through mathematical analysis that the dynamics solves the shortest path problem. In this paper, we generalize the dynamics to the network design problem. We formulate network design as the problem of constructing a network that efficiently supports a multi-commodity flow problem. We investigate the dynamics in computer simulations and analytically. The simulations show that the dynamics is able to construct efficient and elegant networks. In the theoretical part we show that the dynamics minimizes an objective combining the cost of the network and the cost of routing the demands through the network. We also give alternative characterizations of the optimum solution. [ABSTRACT FROM AUTHOR]

A nonlinear energy-based controller and a Lyapunov-based model predictive control (MPC) technology are constructed in sequence for shipboard boom cranes, while taking full state constraints into account. The mathematical model is firstly transformed to ease the explicit influences of ship rollings on the desired positions and payload swings. Barrier Lyapunov functions (BLFs) are then involved in the energy-based controller to deal with different types of state constraints, in which constraints with positive bounds are also effectively tackled with a modified BLF. By adding a contractive constraint with the energy-based controller in traditional MPC framework, Lyapunov-based MPC is then established, in which the recursive feasibility and stability is ensured effectively and easily. Asymptotical stability of two controllers is analyzed and guaranteed in theory, respectively. Compared with the energy-based controller, control performance is improved and enhanced by the Lyapunov-based MPC through solving the optimal control problem. Simulations are finally implemented, and comparisons are also carried out to demonstrate the effectiveness and features of the established controllers in this paper. • An energy-based controller is independently developed for shipboard boom cranes. The asymmetrical constraints on all states are strictly respected and asymptotic stability is guaranteed by embedding BLFs in the Lyapunov function and controller. • To the best of our knowledge, Lyapunov-based MPC is firstly applied to shipboard boom cranes while tackling full state constraints. The recursive feasibility and asymptotic stability are ensured by taking energy-based controller as initial guesses and contractive constraints. • Two groups of numerical simulations are implemented to demonstrate the effectiveness. [ABSTRACT FROM AUTHOR]

Multisource assessment (MSA) is a common employee performance evaluation model in which subjective views of different groups of assessors about individuals are collected and aggregated. Since in the MSA model, uncertain and subjective assessments are usually aggregated using the Averaging method, the quality of its outputs has been questioned in many studies. Regarding the importance of the data aggregation problem and lack of a proper solution in this context, in this paper, a new model based on the Evidence Theory has been proposed to improve data aggregation process in MSA model. To determine the best implementation mode, the performance of the proposed model has been investigated in various defined conditions through a simulation study. The findings of the paper reveal that, in comparison with the traditional aggregation method, the proposed model significantly increases the accuracy of the outputs in the MSA model. [ABSTRACT FROM AUTHOR]

Multiple Criteria Decision-Making (MCDM) methods are widely used in research and industrial applications. These methods rely heavily on expert perceptions and are often sensitive to the assumptions made. The reliability and robustness of MCDM analysis can be further tested and verified by a computer simulation and sensitivity analysis. In order to address this, five different MCDM approaches, including Weighted Sum Model (WSM), Weighted Product Model (WPM), revised Analytic Hierarchy Process (rAHP), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and COmplex PRoportional ASsessment (COPRAS) are explored in the paper. Real data of the case study for assessing housing affordability are used for testing the robustness of alternative ranking and finding the most sensitive criteria to the change of criterion weight. We identify the most critical criteria for any and best ranking alternatives. The paper highlights the significance of sensitivity analysis in assessing the robustness and reliability of MCDM outcomes. Furthermore, randomly generated and model-based data sets are used to establish relationship between the dispersion of relative importance values of alternatives and ranking uncertainty. Our findings demonstrate that the dispersion of relative importance values of alternatives correlate with the Euclidian distances of aggregated values. We conclude that the dispersion of relative importance values contributes directly to the ranking uncertainty and can be used as a measure for identifying critical criteria. [ABSTRACT FROM AUTHOR]

Abstract The mathematical model of heating substation, which is an important part of district heating system, is presented in this paper. The main components of district heating substation system, from the automatic control perspective, that are observed in this paper are heat exchanger and three-way valve. Presented mathematical model is developed so it could operate in real-time, since the crucial aspect of development, deployment and testing of new control techniques and optimization algorithms is their accurate validation on the real system. However, the accessibility to a real system is often not possible. Corresponding to this, an alternative is the existence of the correct mathematical model of a process, with the ability to operate in real-time. First, the presented mathematical model of district heating substation is decomposed to the simpler models of its main elements, in order to provide the analysis of the various parameters on the model performance through numerical simulation. Second, a real-time model is developed in LabVIEW software package and deployed on the embedded controller with a real-time processor as a three-layer application which enables data acquisition and communication with a programmable controller. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of gain-scheduled controller design for parameter-varying discrete-time systems. In practice, the scheduling parameters are only available with limited accuracy due to the measurement errors. In the present paper, these uncertainties are systematically taken into account for the gain-scheduled controller synthesis to achieve improved performance in practical situations. It is assumed that all the matrices of the state-space model of the plant have a homogeneous polynomial dependency of arbitrary degree on the scheduling parameters. The merit of the proposed method is its capability in dealing with the measurement error less conservatively than available approaches while it can also encompass the traditional methods employing the exact scheduling parameters in a less conservative manner. A comprehensive numerical example demonstrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In order to solve the problem of estimating the model parameters of hemodynamic model under low frequency interference, a new model parameter estimation algorithm (CSCKS) is proposed in this paper for the hemodynamic model with low frequency interference. The algorithm is based on SCKS algorithm to improve, its estimation effect is obviously better than the existing SCKS algorithm and DEM algorithm. We simulate the proposed algorithm and some other traditional algorithms to evaluate the estimation performance of CSCKS proposed in this paper under different Signal to Interference Ratio (SIR) and different integration steps, and through the simulation results, the estimated results of the algorithm were analyzed and compared. [ABSTRACT FROM AUTHOR]

Transportation modeling and simulation play an important role in the planning and management of emergency evacuation. It is often indispensable for the preparedness and timely response to extreme events occurring in highly populated areas. Reliable and robust agent-based evacuation models are of great importance to support evacuation decision making. Nevertheless, these models rely on numerous hypothetical causal relationships between the evacuation behavior and a variety of factors including socio-economic characteristics and storm intensity. Understanding the impacts of these factors on evacuation behaviors (e.g., destination and route choices) is crucial in preparing optimal evacuation plans. This paper aims to contribute to the literature by integrating well-calibrated behavior models with an agent-based evacuation simulation model in the context of hurricane evacuation. Specifically, discrete choice models were developed to estimate the evacuation behaviors based on large-scale survey data in Northern New Jersey. Monte-Carlo Markov Chain (MCMC) sampling method was used to estimate evacuation propensity and destination choices for the whole population. Finally, evacuation of over a million residents in the study area was simulated using agent-based simulation built in MATSim. The agent-based modeling framework proposed in this paper provides an integrated methodology for evacuation simulation with specific consideration of agents’ behaviors. The simulation results need to be further validated and verified using real-world evacuation data. [ABSTRACT FROM AUTHOR]

As is known to all, the cable corridor is one of the most important projects in China. In this paper, the fire temperature field distribution of L-type corridor under the condition of different fire source location height is studied through numerical simulation. When the heat release rate of the ignition source is 250 kW and longitudinal wind speed is fixed 0.5 meters per second, the temperature changing rule of the inflection point of L-type corridor is discussed. Furthermore, the temperature prediction formula is established based on the height of the ignition source at different stages according to the fire situation. Combined with the results of these studies, the paper shows that there is obvious "smoke accumulation effect" in L-type cable corridor. [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]

This paper is concerned with discrete-time negative imaginary (DT-NI) functions. First, a new definition of DT-NI functions is introduced. Then, by means of the relations between discrete-time positive real and DT-NI functions, two different versions of DT-NI lemmas are established to characterize the DT-NI properties based on state-space realizations. Also, a necessary and sufficient condition is presented to guarantee the internal stability of positive feedback interconnected DT-NI systems. Meanwhile, some other properties of DT-NI functions are studied. Several numerical examples are presented to illustrate the main results of this paper. Compared to the previous results, our results remove the symmetric assumption in rational case. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) data obtained by using an m-sequence source is typically segmented with an m-sequence cycle, and the random noise is suppressed by stacking the earth impulse responses recovered from each data segment. However, the stack cannot suppress the powerline noise, which is normally several orders of magnitude greater than the random noise. In this paper, the powerline noise reduction with different data lengths were compared by numerical simulation; the results show that there is always an optimal data length, not a single cycle but several cycles that can achieve maximum powerline noise suppression. The concept of an identification system was proposed and the identified earth impulse response is obtained by measuring the system output with the input of the voltage response. The optimal data length was summarized in two cases by analyzing the identification system with different data lengths. Coding frequency optimization was proposed to shorten the optimal data length to increase the stacking times. Finally, the validity of the theory described in this paper was verified by field data processing. Different from the traditional subtraction method and notch filter, the powerline suppression method presented here does not need a noise record or filter design; the powerline noise is suppressed accompanied by the identification processing without any additional workload; the simple and practical method provides a new insight into the powerline noise reduction. With this method, the utilization of field data is improved and the anti-noise performance of the m-sequence is also fully exploited. [ABSTRACT FROM AUTHOR]

This paper proposes a new method to achieve the resonant behavior of a point absorber floating buoy type of Wave Energy Converter using direct drive power take-off system. The system has four main components: a frame; a buoy with a guiding shaft; a supplementary mass coupled with a linear generator and a variable stiffness structure. Firstly, the motion in the vertical direction of the buoy in the sea is converted to an oscillating motion of the supplementary mass. Next, the mass is coupled with a copper coil. The coil motion inside a magnetic wall induces an electrical current in the coil as a linear generator. Besides, a pair of pre-tension springs creates a negative stiffness phenomenon that acts on the motion of the mass and increases the performance of the system. Finally, a variable stiffness structure is installed to control the trajectory of the mass, it can increase the velocity of the mass motion thus the performance of the system is improved. Configuration and working principles of WEC were introduced, studied and analyzed. The mathematical model was presented to explain system behavior. The numerical simulation had been carried out to evaluate the operation of the system. The experimental test rig had been set up and implemented to verify the effectiveness of the proposed structure. • This paper proposes a new method of Wave Energy Converter using a direct drive power take-off system. • The novel variable stiffness mechanism (VSM) has been proposed and investigated. • The mathematical model and experimental test rig are built to validate the system performance. • The mass travels a distance that is longer than that of the excitation motion up to 6 times. • The ball screw and motor are controlled to increase the tension force of the springs and boost the motion of the sup-mass. [ABSTRACT FROM AUTHOR]

Activated corrosion products (ACPs) are the dominant radiation hazard in water-cooled fusion reactor under normal operation conditions, and directly determine the occupational radiation exposure during operation and maintenance. In this paper, a two-phase three-node model is set up, and code CATE V2.0 is developed. Compared to the two-phase homogeneous model used in CATE V1.0, it is capable to analyze the spatial distribution of the ACPs along the cooling loops, and has the ability to deal with pulse of neutron flux, and almost all the radionuclides produced in the loop can be simulated. In the paper, the LIM-OBB loop of ITER is simulated by CATE V2.0. Different pulse handling methods applied to the simulation are compared. The spatial distribution of the composition and activity of ACPs along the loop is presented. And then the dose rate of the LIM-OBB loop is calculated by point kernel code ARShield. [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]

The upstream offshore multi-phase well-pipeline-riser installations are facing huge challenges related to slugging flow: An unstable flow regime where the flow rates, pressures and temperatures oscillate in the multi-phase pipelines. One typical severe slug is induced by vertical wells or risers causing the pressure to build up and hence originates the oscillating pressure and flow. There exist many negative consequences related to the severe slugging flow and thus lots of investments and effort have been put into reducing or completely eliminating the severe slug. This paper reviews in details the state-of-the-art related to analysis, detection, dynamical modeling and elimination of the slug within the offshore oil & gas Exploration and Production (E&P) processes. Modeling of slugging flow has been used to investigate the slug characteristics and for design of anti-slug control as well, however most models require specific facility and operating data which, unfortunately, often is not available from most offshore installations. Anti-slug control have been investigated for several decades in oil & gas industry, but many of these existing methods suffer the consequent risk of simultaneously reducing the oil & gas production. This paper concludes that slug is a well defined phenomenon, but even though it has been investigated for several decades the current anti-slug control methods still have problems related to robustness. It is predicted that slug-induced challenges will be even more severe as a consequence of the longer vertical risers caused by deep-water E&P in the future. [ABSTRACT FROM AUTHOR]

As simulation systems get more and more complex, the study of multi-resolution modeling (MRM) remains an exciting and fertile area of research. Contrasting its abundant successful use cases, a rigorous mathematical foundation is still lacking in MRM. In this paper, we propose a quotient space based multi-resolution modeling (QMRM) theory based on granular computing in artificial intelligence and on discrete-event system specification (DEVS) in modeling and simulation. Based on quotient sets, resolution, multi-resolution modeling and other related concepts are defined and a general concept framework is constructed. Based on the concepts of quotient set and natural projection, several MRM principles are derived. The internal consistency principle guarantees consistency among different perspectives of an atomic model, whereas the external consistency principle guarantees that different components in a coupled model are consistent. The false-preserving principle indicates that if a construction relation or state transformation relation of a component does not exist in a low resolution model, then the corresponding relations should not exist in its high resolution model. The true-preserving principle tells us that a high resolution model can be simplified by choosing the proper low resolution model. QMRM is not only a formal specification, but also a fundamental framework to understand MRM concepts, a guiding ideology to design specific MRM methods, and a modeling methodology to develop MRM systems. QMRM is created from a general simulation perspective, not limited by any specific application or problem domain aspects. The results of this paper can serve as a starting point for further study of multi-resolution problems in different domains. [ABSTRACT FROM AUTHOR]

This paper presents an efficient method for increasing the accuracy of one key step regarding the process of determining a mobility map. That is, the interpolation of the original Digital Elevation Model (DEM) to a finer resolution before running multi-body-dynamics simulations. Specifically, this paper explores the use of fractal dimension and elevation range metrics for increasing the accuracy and reducing the computation time associated with the spatial interpolation ordinary kriging method. The first goal is to ensure the stationary variogram requirement. The second goal is to reduce kriging error or variance in the new predicted values. A novel segmentation-based approach has been proposed to divide the regions of interest into segments where stationarity is ensured. Empirical investigation based on real DEMs indicates the generality of the segmentation approach when natural and man-made terrains are considered. The proposed method leads to a more efficient computation burden and to more accurate results than the traditional approach. [ABSTRACT FROM AUTHOR]

Recently, the paper [2] introduced a method for model order estimation based on penalizing adaptively the likelihood (PAL). In this paper, we use the PAL based order estimation method for a nonlinear sinusoidal model and study its asymptotic statistical properties. We prove that the estimator of the model order using the PAL rule is consistent. Simulation examples are presented to illustrate the performance of the PAL method for small sample sizes and to compare it with that of three information criterion-based methods. [ABSTRACT FROM AUTHOR]

State of charge (SOC) estimators with online identified battery model have proven to have high accuracy and better robustness due to the timely adaption of time varying model parameters. In this paper, we show that the common methods for model identification are intrinsically biased if both the current and voltage sensors are corrupted with noises. The uncertainties in battery model further degrade the accuracy and robustness of SOC estimate. To address this problem, this paper proposes a novel technique which integrates the Frisch scheme based bias compensating recursive least squares (FBCRLS) with a SOC observer for enhanced model identification and SOC estimate. The proposed method online estimates the noise statistics and compensates the noise effect so that the model parameters can be extracted without bias. The SOC is further estimated in real time with the online updated and unbiased battery model. Simulation and experimental studies show that the proposed FBCRLS based observer effectively attenuates the bias on model identification caused by noise contamination and as a consequence provides more reliable estimate on SOC. The proposed method is also compared with other existing methods to highlight its superiority in terms of accuracy and convergence speed. [ABSTRACT FROM AUTHOR]

Recent studies suggest the possibility of CO 2 sequestration in depleted shale gas reservoirs, motivated by large storage capacity estimates in these formations. Although various approaches have been proposed to evaluate and estimate CO 2 storage capacity and even almost all of researches mainly focus on the calculation of storage capacity at the present time, questions remain regarding the quantitative determination of abandonment pressure for a depleted shale gas reservoir, which is a key joint between shale gas recovery and CO 2 storage operation. Also the determination of abandonment pressure is the inversion problems of estimation of CO 2 capacity. Therefore, in this paper, to quantitatively determine the abandonment pressure and mathematically analyze related impacts of dynamic parameters on it, two semi-analytical models of pressure and rate transient analysis are simultaneously proposed for the closed outer boundary condition, without the assumption of sequential flow between the three contiguous media. Adsorption, desorption, diffusion flow, stress sensitivity and non-Darcy flow effects are simultaneously considered. Besides, a new modified Langmuir isotherm equation of CO 2 is initially established to consider the impacts of residual adsorption shale gas. Laplace transformation, source function, perturbation transformation method, superposition principle and numerical discretion method are employed to effectively solve these new models. Laplace solutions are inverted into real time space with stehfest numerical inversion algorithm. Numerical simulation and existing models are also simultaneously conducted to validate this proposed mathematical models. Based on this new solution, some crucial dynamic engineering parameters, including abandonment pressure and non-Darcy flow, are creatively analyzed combining pressure transient analysis (PTA) and rate transient analysis (RTA) For two kinds of CO 2 injection control: constant injection pressure and constant injection rate, it is the essence of this paper that typical chart referring quantitative determination of abandonment pressure is originally established via pressure transient analysis (PTA) and rate transient analysis (RTA). Via regression method using synthetic and real data, results mathematically show that for PTA method, the abandonment pressure has exponent relationship with the injection pressure, however, for RTA method, the abandonment pressure has logarithm relationship with CO 2 injection volume. Finally, well testing of gas production data, micro seismic date and core analysis allow for formation parameter estimation, two real shale gas wells from Sichuan Basin in China are selected to show the promising application prosperity of the new performance analysis and quantitatively determination of abandonment pressure for CO 2 storage in depleted shale gas reservoirs. [ABSTRACT FROM AUTHOR]

This paper studies the maintenance modelling of a multi-component system with two independent failure modes with imperfect prediction signal in the context of a system of systems. Each individual system consists of multiple series components and the failure modes of all the components are divided into two classes due to their consequences: hard failure and soft failure, where the former causes system failure while the later results in inferior performance (production reduction) of system. Besides, the system is monitored and can be alerted by imperfect prediction signal before hard failure. Based on an illustration example of offshore wind farm, in this paper three maintenance strategies are considered: periodic routine, reactive and opportunistic maintenance. The periodic routine maintenance is scheduled at fixed period for each individual system in the perspective of system of systems. Between two successive routine maintenances, the reactive maintenance is instructed by the imperfect prediction signal according to two criterion proposed in this study for the system components. Due to the high setup cost and practical restraints of implementing maintenance activities, both routine and reactive maintenance can create the opportunities of maintenance for the other components of an individual system. The life cycle of the system and the cost of the proposed maintenance policies are analytically derived. Restrained by the complexity from both the system failure modelling and maintenance strategies, the performances and application scope of the proposed maintenance model are evaluated by numerical simulations. [ABSTRACT FROM AUTHOR]

This paper searches for a deployment method with minimum sensor nodes to achieve agricultural intelligent monitoring. Because of the various features, topographies and complicated weather conditions, the selection of the location for deploying sensor nodes is difficult, especially in hilly areas. This paper puts forward a sensor node deployment algorithm for agricultural intelligent monitoring based on an optimized theory. It first develops a mathematical model for the node location selection. During the solution process, the features of the locations are of primary concern, as a location with more features is easier to choose than other locations. Next, a theoretical analysis and experimental simulation are carried out. Finally, OASNDFA is used in 3000 mu orange orchards in China. The result demonstrates that OASNDFA could perform relevant monitoring tasks with fewer monitoring nodes. [ABSTRACT FROM AUTHOR]

The purpose of the paper is to investigate the challenges in modelling the energy losses of heating networks and to analyse the factors that influence them. The verification of the simulation was conducted on a test stand in-situ and based on the measurements of the testing station, a database for the final version of the numerical model was developed and a series of simulations were performed. Examples of the calculated results are shown in the graphs. The paper presents an innovative method of identify the energy losses of underground heating network pipelines and quantify the temperature distribution around them, in transient working conditions. The presented method makes use of numerical models and measured data of actual objects. The dimensions of the pipelines used were 6 m wide, 8 m high and 1 m in depth, while they were simulated under conditions of zero heat flow in the ground, in the perpendicular to the sides direction of the calculated area and considering the effects of ground's thermal conductivity. The mesh was developed using advanced functions, which resulted its high quality with the average orthogonal quality of 0.99 (close to 1.00) and Skewness of 0.05 (between 0.00 and 0.25). To achieve better accuracy of the simulation model, the initial conditions were determined based on the numerical results of a three-dimensional analysis of heat losses, in steady state conditions in a single moment. The validation process confirmed the high quality of the model, as the differences between the ground temperatures were approximately 0.1 °C. [ABSTRACT FROM AUTHOR]

The accurate model of the jet-type valve, as the pilot control stage of a jet-pipe/deflector-jet servovalve, is of great significance to analyze and design a servovalve. However, the flow field in the jet-type valve is too complex to build an accurate mathematical model. In this paper, the collision between the liquid and the jet is supposed as the impact of jet on a moving piston, which makes a complex the fluid mechanical problem become simple. Based on this assumption, a model of the jet-type valve is developed in this paper. Unlike the previous models, the structural parameters, the distance between the jet-nozzle exit and receiving surface, the included angle between two receiver holes as well as the distance between two receiver holes, all can be considered in this model. To test and verify the theoretical model, the pressure and flow characteristic curves of a jet-type valve are given by the methods of flow filed numerical simulation and experiment.As shown by the verification results, the theoretical pressure characteristic curve is very approximate with the experimental data and numerical simulation, while the flow characteristic curves need to be modified and the modified model is valid. [ABSTRACT FROM AUTHOR]

Designs of petroleum wells involve many activities and technical areas. These areas cover various engineering aspects and can be solved with contributions from applied mathematics. This paper presents a new casing point optimization methodology. A novel mathematical formulation and procedure for optimization of casing string placement including geological uncertainty is developed. Determination of optimal casing point locations is a challenging task because many engineering and geologic variables affecting each other and are often uncertain and nonlinear. In this paper, the casing string placement problem was formulated as the optimization function under uncertainty. The geological uncertainty is modeled with considering different scenarios of geology. The Lingo software was used as the optimization tool. In order to find the optimum decisions for different risk attitudes, a utility framework that enables the assessment of the uncertainty of the casing string placement decisions is used. A large case study was undertaken to demonstrate the value of considering uncertainty in drilling decision-making. Numerical simulation was carried out with this selected case study to find optimum points under different risk attitudes in each section of drilling for different wells. Finally we show the application of that methodology has better performance to cost savings at least of 2.4–15.2% in the important drilling management. [ABSTRACT FROM AUTHOR]

In this paper, the friction compensation method of SCARA robot is proposed. During the operation, the friction force in the system causes the heat to the robot and system. Since heat which occurred in the system is accumulated for a long time, the robot and system have been damaged. Moreover, performance and stability of the system have been reduced. Therefore, compensation of friction force is an important method for increase performance and stability of the system. In this paper, the disturbance observer is used with mathematic modelling of friction compensation for compensate the friction force in the system. From the simulation results, the system which has a friction force compensation can show the increasing of performance and stability. [ABSTRACT FROM AUTHOR]

This paper presents a 3x3 antenna array of ractangular topology is designed to operate at Ku Band. The antenna has been designed as arrays of patches, where number of elements, spacing's and feeding currents has been optimized to fulfil the requirements of low side lobe level and good cross polarization. The operating frequency of array is from 12 to 18 GHz. The antenna array has been designed and simulated on FR4 Substrate with dielectric constant of 4.4. This paper presents that, the detail steps of designing and simulating the rectangular patch antenna and rectangular patch antenna Array in Ku-band. The design is analysed by FEM based HFSS 14.0 by which return loss, 3D polar plot, Directivity, VSWR and Gain of the antenna are computed. The software simulated results are shows that the proposed antenna array provides good performance in terms of return loss, VSWR and Gain. [ABSTRACT FROM AUTHOR]

Understanding and analysing security risks is an essential task when designing and maintaining a systems’ security. The first risk analysis should be performed during the system design. Identified risks have to be updated during the lifecycle when security controls are implemented or new threats appear. Visualization facilitates the risk analysis process, but visualizing the huge amount of risks with diverse causalities is challenging. This paper concentrates on risk visualization and related challenges. The paper presents a semantic model for risk visualization and structuring implemented into the Metric Visualization System (MVS). The proposed model and tool support make risk visualization consistent and ensures that it includes mutual connections of risks. The contribution helps designers to analyse risks and to select security controls in a justified manner. [ABSTRACT FROM AUTHOR]

In modern ages, universities have shaped the civilized society and contributed to its knowledge base by educating the workforce, and providing consultation to government and businesses. In the wake of globalization, it is necessary to establish mutual beneficial relationships between universities and their urban areas; hence, the university - city complex model. In the context of Vietnam, most universities are located in urban areas; none of which, however, has fully engaged in the local community in meaningful ways. With the core idea of “Building an intelligent and ecologically friendly city”, this paper proposes the design of a university - city complex in Hung Yen province, Vietnam. This design will stimulate sustainable development of the local community through green architecture, spatial planning of university complex, and careful design of education programs and services. This paper will also present the conceptual knowledge of the subject, potential factors driving the development, and successful case studies of university - city complexes. [ABSTRACT FROM AUTHOR]

This paper proposes a mathematical model and a computational approach applied to the study of the interaction between a moving platform and pedestrians walking on it. A ship deck motion used as a basic scenario for simulation is realized in three modes reproducing heaving, pitching or rolling rotations of the vessel. Behavior of virtual passengers is emulated by the Social Force pedestrian model modified with additional forces. In this paper the mathematical definitions of both models and their software implementations are discussed. The results of the experiments reproducing various combinations of characteristics of the ship motion are presented and compared with a case where it remained stationary. The paper is concluded with an analysis of the simulation results and perspectives for further research. [ABSTRACT FROM AUTHOR]

This paper presents a simple membrane fouling model intended for use in conjunction with an activated sludge model to form an integrated model of a membrane bioreactor (MBR). It is based on an earlier development of Liang et al.[1] who divided fouling into short-term reversible fouling tantamount with cake deposition and long-term irreversible fouling representing th effects of irreversible particle deposition inside membrane pores. The original model was extended to account for cake detachment, back- flushing, and dependency of soluble microbial products (SMP) deposition on permeate flux. The model was identified on two sets of data from two experiments: a short-term flux stepping experiment under fluxes higher from the ‘threshold flux’ and a long-term filtration experiment under fluxes not exceeding the ‘threshold flux’. Additionally, the paper proposes a simple ‘pen and ruler’ identification method for unique estimation of model parameters based on the information obtained from flux stepping experiments. [ABSTRACT FROM AUTHOR]

• The article proposes a new mathematical model of the inductive displacement sensor. • The model uses composite functions and a multi-objective optimization algorithm to design the coil structure parameters of the sensor. • The model aims to improve the sensor's linearity and sensitivity. • The new design method is verified by numerical simulation and physical experiments. This paper proposes a novel mathematical model that has high accuracy based on a multi-objective optimization algorithm for the inductive displacement sensors, which is popular in industrial production due to their simple design and reliable performance. The proposed model uses composite functions to establish the structural parameters of the coil winding. The non-dominated sorting genetic algorithm II (NSGA-II) is used to solve a series of non-dominated problems related to the coil structure parameters with the goal of achieving superior sensor performance. Density clustering sorting is used to select the desired non-dominated solutions. The designed sensor has a nonlinearity of 0.16%, and numerical simulations and physical experiments confirm the effectiveness of the new design method. [ABSTRACT FROM AUTHOR]