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Understanding the effects of water absorption on the geometry of a paper sheet is important for inkjet printing applications, since internal moisture content differences may cause unacceptable out-of-plane deformations. The present work focuses on moisture-induced deformations due to a moisture content that is uniform over the thickness of the sheet. Large enough in-plane differences will cause the sheet to buckle, leading to a wavy pattern at the edges of the sheet. Two approaches are utilized to study this for levels of moisture content up to and including the threshold for buckling. An analytical approach, based on geometrically nonlinear plate theory (von Kármán theory), and a numerical one, using commercially available finite element software, are presented. As a first reference problem an isotropic circular plate, wetted uniformly at its center, is solved both analytically and numerically for the in-plane stress distribution, the buckling threshold, and the resulting buckling mode. Secondly, the same is done for an orthotropic rectangular plate, wetted at its edges. Here, in the analytical approach a Rayleigh–Ritz analysis is employed to approximate the buckling threshold. The latter is also calculated by numerical means. The results show that the methods provide results consistent with each other. [ABSTRACT FROM AUTHOR]

Much literature exists for rock-paper-scissors (RPS) game. It is well known in a single habitat that spatial models are more stable than well-mixed population. However, the mechanism of spatial stabilization has been unclear. In the present article, we study multilayer model of RPS game in a patchy environment; respective patches are set as lattices. The predation probability of one of three species is assumed to be reduced as a parameter. Simulations on two-layer system reveal the opposite result to those on a single-habitat system. Namely, the well-mixed population becomes stable. In contrast, extinction occurs by random migration in spatially-explicit model, when the reduced predation probability is below a certain critical value. The extinction in spatial model is found to be caused by the collapse of a kind of swarm intelligence (SI). In RPS system, large swarms of each species are automatically protected from its predator. Such a self-organized protection is one of the simplest examples of SI. We also discuss some serious problems for random migration. • Spatial pattern of rock, paper and scissors are studied in patchy environment. • A distinct point of the present paper is to set lattices as respective patches. • We illustrate that biodiversity is sustained by a kind of "swarm intelligence". • Large swarms of each species are automatically protected from its predator. [ABSTRACT FROM AUTHOR]

In this paper, a quick convergence adaptive structure is proposed for trajectory tracking of an articulated type robotic manipulator using the Hardware in the Loop (HIL) simulation technique. A novel Nonlinear Quick Convergence Adaptive Sliding Backstepping Control (QCASBC) algorithm is implemented on a C2000 real-time controller board. The performance of the proposed control algorithm is inspected concerning the sliding mode PID (SM-PID) control technique to estimate its correlation with the proposed algorithm. The experimental part of the HIL simulation tests has been carried out on a simulated model of a three-link serial robot manipulator. A dynamic model of the robotic manipulator has been developed using Matlab Simulink software and its performance is analyzed using the HIL technique via a C2000 real-time controller for tracking the desired trajectory. Results show that the speed of convergence while tracking the desired trajectory of the manipulator is better in the proposed algorithm. It is also estimated that the positional error of the QCASBC algorithm is superior to the SM-PID control algorithm. The observed average angle error is improved by 14% and the average response time error is improved by 11% by using the proposed QCASBC algorithm compared to the SM-PID approach. [ABSTRACT FROM AUTHOR]

Due to the complexity of open-channel networks in which a lengthy procedure is required to understand and analyze their behavior. This paper introduces a methodology for the skeletonization of complex tree-shaped open channel systems. The aim is to aggregate separate branches into one equivalent branch, which has a new skeletonization factor. Three different illustrative examples of river systems using two approaches are analyzed. The software package HEC-RAS is employed to simulate the proposed open channel networks as a one-dimensional steady, gradually varied flow state. Results show that there is a strong correlation between the skeletonization factor required for the equivalent branch and the flow rate of the equivalent branch. The skeletonization factor is also significantly affected by an increase in the ratio of the bed width of each branch canal to that of the main channel in Approach A. The water depth along the main channel has increased more significantly in approach B than in approach A, with average increases of 49.5 %, 29.2 %, and 14.1 % for a number of branches equal to 2, 4, and 6, respectively. Finally, the developed skeletonization concept can be used to represent complex open-channels network models. [ABSTRACT FROM AUTHOR]

With the widespread use of substation intelligent simulation systems, existing substation intelligent simulation systems have problems such as platform redundancy, system dispersion, and information sharing, which can lead to the insecurity of substation intelligent simulation systems. Therefore, this paper proposes a security operation analysis of substation intelligent simulation system based on improved genetic algorithms, aiming to improve the security of substation intelligent simulation system by using improved genetic algorithms. This paper experimentally tests that the number of vulnerabilities in a substation intelligent simulation system using improved genetic algorithms is between 0 and 20 within a month, while the number of vulnerabilities in a traditional substation intelligent simulation system is between 30 and 50, indicating that improved genetic algorithms do have the effect of improving the safety coefficient of the substation intelligent simulation system. [ABSTRACT FROM AUTHOR]

The launcher recovery method known as 'In-Air Capturing' is an innovative approach where a winged rocket stage is captured mid-air by an aircraft and subsequently towed back to the launch site. To achieve this, a capturing device attached to a tether is released from the towing aircraft. This device autonomously connects the reusable launch vehicle to the aircraft, while the two vehicles are in proximity. The tether's flexible dynamics have a strong influence on the maneuverability of the capturing device. Thus, it is critical to model the dynamics of the tether to get a realistic understanding and to evaluate feasibility of the concept. However, precise modelling and control of highly flexible systems with large deformations is both challenging and computationally intensive. For engineering applications which involve closed-loop simulations, finding a trade-off between accuracy and computational effort is crucial. In this paper, the tether is modelled as a discretized chain of rigid bodies connected by rotational springs at the joints. The tether along with the capture system is integrated in a simulation model and open loop tests are performed to analyse the system characteristics. The tether properties are studied to find a suited configuration for 'In-Air Capturing'. • Multibody modelling approach for long cable like bodies with large deformation. • Capture system dynamics for the unique 'In-Air Capturing' launcher recovery concept. • Dynamic modelling for the complete capturing system including towing aircraft, capturing device and tether. • Assessment of tether properties suited for 'In-Air Capturing' with sensitivity studies. [ABSTRACT FROM AUTHOR]

Agent-based modeling has become increasingly prevalent in transportation systems simulation as the scenarios around new technologies and policies become increasingly complex. This increased complexity, in terms of traveler behavior, traffic flow, modal operations, system management, and so on, requires increasingly sensitive and detailed representation of the core components of the simulation, especially as it relates to traffic flow. Many future mobility solutions rely on connectivity, communication, advanced sensing, and detailed information flows, while the simulation also needs to remain computationally tractable. In this paper, we propose a new Lagrangian Coordinate within the POLARIS Agent-Based-Modeling Framework (LC-POLARIS) of traffic flow, which combines computational efficiency while adding microscopic features. This model allows multi-class traffic flow by setting different speed-spacing relationships. In this modeling, automated vehicles have lower reaction time, while light-duty trucks have lower free-flow speed and higher jam spacing. The model captures the reduction in capacity and higher queue spillback because of higher jam spacing of trucks. Also, the model yields higher capacity for both passenger and light duty automated vehicles on expressways. The LC-ABM traffic flow model is validated in Bloomington, IL, USA, in a scenario with different rates of four vehicle types. [ABSTRACT FROM AUTHOR]

Macroscopic traffic flow models are powerful tools for assessing the level of service on freeway segments. One popular model is the Cell Transmission Model (CTM) proposed by Daganzo. The US highway capacity manual (HCM) operationalizes this model in the form of the simulation tool FREEVAL for assessing sequences of freeway segments. The conceptual CTM also supports networks of freeway segments. In the literature this was implemented and applied to a mid-scale freeway network of 340 km. However, the literature lacks research in efficient implementations of CTM, which becomes relevant when applying it to large-scale networks at national scale like the German Autobahn with a length of 260 000 km. In this paper we propose a vectorized formulation of the CTM for networks. Boolean vectors are employed for vectorized case distinction. Furthermore, we exploit the properties of adjacency matrices to achieve shifting operation on complex network structures. To evaluate the vectorized CTM implementation, we simulate synthetic freeway network grids of varying size and complexity for different simulation periods. The results show that the network complexity has no influence on computation time, while it scales linear in simulated hours. A quadratic regression was applied to the measured computation times over varying network sizes. For large network sizes, the vectorized CTM implementation achieves a speedup factor of 9 compared to a sequential implementation. When simulating 2880 kilometers of freeway, the computation time of 2.3 hours is reduced to 16 minutes. [ABSTRACT FROM AUTHOR]

This paper introduces a flexible framework to enable high-fidelity simulations of the fuel slosh dynamics for verification of the Guidance, Navigation and Control (GNC) algorithms. The sloshing phenomenon must be tackled during the control system design phase and the GNC software run and validated within appropriate simulation frameworks. Equivalent mechanical models can well approximate sloshing under specific assumptions, allowing the derivation of the multibody vehicle's equations of motion; however, while suitable for analysis and control synthesis purposes, this approach presents several limitations for implementation as a simulation model. In this work, the multibody plant embedding slosh dynamics is modeled by means of the DLR's Vertical Landing Vehicles Library (VLVLib) written using the object-oriented Modelica modeling language. The advantages of using Modelica are explored throughout the paper. Given that control synthesis, analyses and simulation campaigns are usually performed in the Matlab/Simulink environment, a core point of the proposed solution is to achieve a good synergy within the latter and the Modelica plant model with the least readaptation burden for the developer. The strategies to achieve a full integration and verification tool chain are illustrated. The potential of this approach is demonstrated via two different test cases: a lunar landing scenario of the ALINA spacecraft developed by PTS, and CALLISTO reusable rocket demonstrator. • A flexible framework to enable high-fidelity simulations of the fuel slosh dynamics for verification of the GNC algorithms is introduced. • The spacecraft model embedding the slosh dynamics is implemented exploiting Modelica language. • A GNC testing framework is obtained with the integration of the causal Simulink environment with the compiled Modelica model. • Two test cases are presented: the ALINA spacecraft lunar landing scenario and CALLISTO reusable Vertical-Takeoff–Vertical-Landing demonstrative mission. [ABSTRACT FROM AUTHOR]

The work presented in this paper is part of a project that focuses on sorting simulation models used at Intel to calculate power consumption of electronic devices. Hundreds of thousands of analytical power models have already been accumulated in a directory of files and folders, for the simulation of the consumption of thousands of products. As a first step, this work focuses on comparing and grouping together models of smaller granularity - the formulas - which consist of power equations, the definition of the parameters involved in these equations, and a description. To manage this large data problem, we follow the principles of Model Management and Analytics, to decompose the problem into the analysis of constituent fields. We believe that the equations describing power consumption are the most highly information-rich field of our models. The aim of this work is to group together the formulas models, using Mathematical Language Processing (MLP), to take advantage of the business information contained in electrical equations. We calculate the embeddings of our formulas, to enable comparisons between them, to cluster together similar equations (and therefore models). [ABSTRACT FROM AUTHOR]

Space-based gravitational wave detection missions use multiple satellites to form a very large scale Michelson laser interferometer in space. This requires extremely high precision displacement measurements at the picometer level between test masses even millions of kilometers apart. Drag-free control is a key technology to ensure the ultra-static and ultra-stable space experiment platform for space-based gravitational wave detection. This paper proposes an innovative ground simulation scheme for drag-free control principle based on the Stewart platform. The kinematics and dynamics modeling of the Stewart platform used in the experiment is presented. A drag-free ground simulation experimental equipment is designed and built. A two-degree-of-freedom (2-DOF) drag-free controller is designed based on the H ∞ loop shaping algorithm which outperforms a PID controller in Simulink simulation. A semi-physical simulation experiment is conducted to verify the controller designed using rapid control prototyping technology. The experimental results show that the control performance reaches the limit accuracy of the hardware device, thus verifying the effectiveness of the drag-free control algorithm. • Introduce a novel ground simulation scheme for drag-free control using the Stewart platform. • Design a drag-free controller based on H ∞ loop shaping. • Validate our approach through a two-degree-of-freedom semi-physical simulation experiment. [ABSTRACT FROM AUTHOR]

Many cities around the world have experienced an increase in population and pose challenges in planning and managing the freight transportation within the city. Off-peak hour delivery (OPHD) is a strategy of delivering goods in the afternoon and evening to reduce congestion during peak periods, increase the efficiency of delivery companies, and reduce emissions. This research proposed a model of city logistics in the retail supply chain by implementing OPHD in the logistics system. The aim of this study is to explore the extent of potential implementation of OPHD in urban logistics. An agent-based modeling and simulation (ABMS) approach is applied to model the autonomous and dynamic interactions of stakeholders involved in city logistics systems. Preliminary results are presented in this paper to provide illustrations of the model. It shows that OPHD can significantly reduce the transportation cost and emissions cost, and ABMS is able to provide results that are relatively close to pilot test drive research which is carried out in real world. [ABSTRACT FROM AUTHOR]

Swarm Production is a novel paradigm promoting a high degree of flexibility in material flow and reconfigurability in shop floor layout, enabling high-mix production in manufacturing through the induction of autonomous robots. The conceptual description promises a leap within smart manufacturing and the Industry 4.0 domain. Implementing this theoretical concept becomes crucial to the self-organising production domain and gradually learning the relevant technological stack, optimisation methods, objective functions, and shop floor constraints needed for Swarm Production. This research paper addresses the challenges of the simulation of autonomous mobile robots in the production environment and concludes with an exemplified case simulation. A simulation testbed visually demonstrates the concept with planning, scheduling and control systems, providing their feasibility and reliability. [ABSTRACT FROM AUTHOR]

This paper presents the high-fidelity physical modeling of a Thrust Vector Control (TVC) system operated by Electro-Mechanical Actuators (EMAs) for Reusable Launch Vehicles (RLVs). In contrast to simplified, often linear, models, high-fidelity physical models enable a better assessment of the actual system performance and a deeper verification of the on-board software robustness against disturbances, unmodeled dynamics or degradation. This aspect is essential to enable the reusability concept as driven by long-term reliability requirements. Moreover, critical systems like Fault Detection, Isolation and Recovery (FDIR) logic, whose robustness and efficacy are often difficult to prove, can be thoroughly tested without requiring hardware experiments with eventual invasive modifications for fault injections. This work captures the whole dynamics of the EMA and TVC components, including the power drive electronics, the electrical motor, and the mechanical transmission for the EMA, as well as the mechanical properties of the engine nozzle acting as a load. The resulting differential algebraic equation system is modeled in the Modelica acausal object-oriented modeling language. An ad-hoc framework is implemented to guarantee flexibility and modularity, which allows models with different fidelity levels to be easily exchanged to achieve the simulation objectives and needed accuracy level. The impact of the different models on the closed-loop TVC dynamics is analyzed in both the frequency and time domain, and then benchmarked with a realistic RLV mission. The results show that the high-fidelity physical models provide a better understanding of the more complex effects governing the TVC dynamics and can, in turn, effectively improve its requirement definition process. • The physical modeling and simulation of an EMA-based TVC system is presented. • High-fidelity physical models help assessing TVC system control software performance. • EMA component models with incremental fidelity levels are proposed. • EMA and TVC system models are integrated in a Modelica-based framework. • Different closed-loop responses are analyzed in the frequency and time domains. [ABSTRACT FROM AUTHOR]

Promoting the development of green innovation is crucial for achieving the green transformation of society. This paper considers the decision bias of different agents in policy implementation and presents a theoretical model that captures the structure of the green innovation system. The model includes six subsystems: government, technology, public, energy, environment, and population. The study examines the transmission effect of green innovation and the influence mechanism of multiple decision biases on policy combination effects using a combination of various policy tools. The results show that: Various policy tools and their implementation differences have distinct effects on the green innovation and environmental performance. In most cases, the synergistic policy mix effect, surpassing the impact of individual policies, is driven by the resource effect. However, the synergistic effect of policy combination may not be fully realized, leading to potential conflicts. Due to various decision biases, particularly the gap in the public's green behavior, the policy mix faces challenges in achieving immediate synergistic effects. Combining tax policies with other policy instruments increases the risk of incoherence and inconsistency. However, in the long term, the combination of policy tools can exert strong late-developing advantages. This study provides insights for green innovation policy improvement. • This paper develops a green innovation system with the government subsystem serving as the operational hub. • This paper establishes a policy framework for green innovation systems based on multi-subject decision bias. • This paper simulates the impact of policy implementation on green innovation and main pollutant emissions. • The study finds that tax policy has a more significant dampening effect when combined with other policies. • This study finds that policy mix can exert resource effects, but decision biases cause a delayed manifestation. [ABSTRACT FROM AUTHOR]

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

Energy-efficient resource-optimization for multiple application scenarios requires appropriate clustering-based network-fractioning that skillfully removes unbalanced network connectivity, which is a stimulating bottleneck in WSN-performance. This paper proposes a new Uniform Connectivity-based clustering Protocol, called Lines-of-Uniformity based Enhanced-Threshold (LUET) to provide energy-efficient coverage in three-tier heterogeneous WSN. This protocol considers the node's remnant-energy and its proximity from either of the lines of uniformity for lowering down average isolated node count in WSN. This paper also proposes a rotation epoch-based LUET variant, (LUET|R) that incorporates static epoch for initial clustering rounds until First-Node-Death to overcome the rapid fall after the death of the first node. The simulation model demonstrates the superiority of LUET and its variants over other established clustering protocols in terms of network-lifetime, power-efficiency, net death-rate, average isolated-nodes, throughput. [ABSTRACT FROM AUTHOR]

We study numerically orientation of rigid fibres in a turbulent flow. Instead of a Lagrangian approach, i.e. following fibres along trajectories and analyzing orientations after simulations, we are using a fibre orientation probability distribution (FOPD) model. The mathematical model predicting the two spherical orientation angles (in a three-dimensional computational domain) is presented and solved in a coupled manner, which is the novelty of our approach. Furthermore, numerical predictions are validated with experiments. The origin of the problem is in the papermaking industry, that is, distributing and orienting fibres optimally into a paper sheet produced. [ABSTRACT FROM AUTHOR]

In this paper, two new climate change mathematical models are extended using the stochastic-deterministic piecewise hybrid fractional derivatives, where the hybrid fractional order operator is applied to extend the deterministic model and the fractional Brownian motion operator is applied to extend the stochastic model. The steady states analysis of the propsed models are discussed. Two numerical methods are constructed to study the behavior of the proposed models. These methods are Caputo proportional constant Adams-Bashfourth fifth step method for solving the hyprid fractional deterministic model and the modified nonstandard Euler Maruyama technique to study numerically the fractional Brownian motion stochastic model. Several numerical test examples are given to demonstrate the efficiency of the methods and to support the theoretical results. [ABSTRACT FROM AUTHOR]

With the development of 3D technology, the construction of 3D motion model has become an important research issue in many fields, such as virtual reality, animation and robot vision. In this paper, a 3D motion model construction method based on simulation algorithm is proposed. Firstly, the gravity simulation algorithm is used to simulate the trajectory of the object, and the position data of multiple moments with numerical accuracy of 10cm are obtained. Then, the interpolation algorithm is used to interpolate these position data into continuous curves, and the object trajectory with 1cm accuracy is obtained. Finally, we integrate the obtained trajectory data with 3D modeling software to generate a 3D motion model with real motion effect. The experimental results show that this method has high accuracy and reliability in constructing 3D motion model, and is suitable for many fields. [ABSTRACT FROM AUTHOR]

Torsional nano-scanners have a variety of applications in nano/micro-electro-mechanical systems. In this paper, two- and three-dimensional numerical solutions based on the lattice Boltzmann are proposed for simulating the dynamic behavior of an electromechanical torsional nano-scanner. The complete governing equations are modified based on the couple stress theory and developed by considering the effect of the Casimir force. Furthermore, the physics of the system is extended by considering the effects of dissolved electric agents on the dynamic performance of the nano-scanner. The passive/active electrolyte flow behavior with the moving solid boundary is described and simulated using Nernst-Plank-Poisson compensation of the electrolyte flow. The proposed numerical results are validated by comparing them with those available in the literature. Finally, the influence of scale dependency and Casimir force on the nano-scanner's dynamic performance and pull-in instability are investigated. Also, as torsional nano-scanners might be immersed in ionic media, the impact of ionic concentration on the pull-in voltage of a nano-scanner is investigated. The obtained results demonstrate that increasing the ionic concentration reduces the instability voltage of the nano-scanner considerably. [ABSTRACT FROM AUTHOR]

In this paper, a fractional nonlinear control strategy based on the nested saturations technique and the Caputo-Fabrizio derivative for a quadrotor aircraft, to maintain desired position and orientation in stationary flight and trajectory tracking tasks, is proposed and developed. In addition, the dynamic model is obtained by using the Euler–Lagrange formulation, and then it is generalized to an arbitrary order through the Caputo-Fabrizio derivative. The traditional nonlinear control based on the nested saturation technique is also developed and implemented on the quadrotor for comparison purposes between both control schemes. Numerical simulations demonstrated the superiority of the proposed control strategy for stabilizing the quadrotor at hover and reaching the desired position and orientation, over its integer-order counterpart. In addition, three additional desired trajectories are considered, keeping the same gains and orders, to demonstrate the robustness of the proposed control scheme under different operating conditions. In this sense, our controller presents significant performance improvements, which were validated through system simulations. Our proposed control system and its traditional counterpart were tuned experimentally using the response of the system to a desired trajectory. [ABSTRACT FROM AUTHOR]

The National Aeronautics and Space Administration (NASA) is currently developing the next generation of spacesuits for use in future exploration missions. This effort, referred to as the Exploration Extravehicular Mobility Unit (xEMU), has been underway since 2015 with the goal of demonstrating the new technologies during a mission to the International Space Station (ISS). Due to the complexity of the xEMU system, and particularly its portable life support system (PLSS), computer simulations are heavily relied on in the development process, from dynamic loads analysis to software verification. The models of the physical systems that are currently being used for system-level simulations are mostly empirical, where the underlying formulas are mathematical fits to test or simulation data. An advantage of this approach is the fact that these models are very performant and can be used in real-time applications such as user interface testing and operator training. The research presented in this paper describes a different approach to modeling and simulation. A simulation tool focused on life support systems for human spaceflight in general and PLSSs in particular has been under development at the Technical University of Munich (TUM) since 2006. The spacesuit specific variant of this tool is called The Virtual Spacesuit (V-SUIT) and is now being utilized in the current spacesuit development process at the NASA Johnson Space Center (JSC). In contrast to the previously mentioned empirical models, V-SUIT uses a first-principles-based, bottom up modeling approach, where basic physical, chemical or biological effects are modeled at the lowest level and the component and system models are created using these fundamental building blocks. This enables the simulation to account for effects, and especially off-nominal situations, that may not be within the range of validity of the empirical models. This paper presents the structure of and the rationale behind V-SUIT itself as well as a status report on the ongoing effort to integrate it with the existing simulation systems in use at JSC, which is based on Trick/GUNNS. As a proof of concept, a single component model from V-SUIT, that of the spacesuit water membrane evaporator (SWME), has been integrated with NASA's simulation tool. Results include comparisons of the performance of the two simulation systems and a description of challenges that were encountered during implementation. The paper closes with an outlook towards the future developments that are planned for V-SUIT within the xEMU development program. • A novel approach to dynamic system-level simulations is applied to a spacesuit. • Multi-disciplinary, bottom-up modeling instead of domain-specific, top-down models. • Performance shown to be fast enough to provide value during system development. [ABSTRACT FROM AUTHOR]

• A new reliability method combining relevance vector machine and subset simulation importance sampling is proposed. • The ability of surrogate model-based subset simulation importance sampling to handle multiple failure mode problems is achieved. • An efficient update strategy is employed to improve the prediction accuracy of relevance vector machine and avoid unnecessary iterations. • The proposed method improves computational efficiency while ensuring the accuracy of the result. Evaluating the failure probability of engineering structures involving implicit performance functions generally requires time-consuming finite element simulations. The computational effort is usually unbearable, especially for small failure probability. This paper proposes a new reliability analysis method combining relevance vector machine and subset simulation importance sampling, which guarantees the accuracy of results and improves the computational efficiency. In this method, relevance vector machine is first applied to approximate relatively coarse limit states. Then, subset simulation importance sampling is executed based on the constructed relevance vector machine. To improve the prediction accuracy, samples from first and last level are used to refine relevance vector machine. Since only the samples of last level are involved in the calculation of the failure probability, and the updated relevance vector machine has a very high prediction accuracy for the samples of last level, the obtained failure probability is extremely accurate. In addition, the samples are predicted by the well-constructed relevance vector machine rather than evaluated with real performance functions, which drastically decreases the calculation time. To reduce redundant iterations in the update process, a novel learning function based on the current design of experiment position and a stopping condition based on error estimation of reliability prediction are employed. Furthermore, the K-means clustering algorithm is utilized to implement the ability of surrogate model-based subset simulation importance sampling to handle multiple failure mode problems. The efficiency and accuracy of the proposed method are verified by four examples involving different types of features. [ABSTRACT FROM AUTHOR]

A Physical Internet of hubs ('PI-hubs') is a network of logistics terminals that allow shipments to flow through, similar to the flow of Internet data packets. PI-hub networks are a recent proposal and their properties have not been studied in detail. In this paper we model PI-hub networks using the theory of queuing networks, particularly, Jackson queuing networks. Under certain assumptions, PI-hub networks behave like Jackson queuing networks, and thus analytical methods can be used to calculate important properties such as throughputs, processing times, traffic size etc. In this paper we analyse the performance characteristics (throughput, queue size) for each PI-hub and for the whole PI-hub network. [ABSTRACT FROM AUTHOR]

Excavation on jobsites is a collaborative effort, with a spotter serving as an extra set of eyes for the operator to ensure safety. However, current training methods using simulators are limited in immersion and primarily designed for individual operators to practice basic skills. This paper presents a multi-user teleoperation system featured with hybrid-immersive interface and between-user communication. The effectiveness of the system is evaluated through human subject experiments. The study's findings indicate that operators experienced greater immersion, a stronger sense of presence, and improved user interaction when using an immersive interface. This paper has important implications for the future of excavation training, with potential benefits including reduced utility strike damage and the opportunity to investigate human-robot collaboration in jobsites with multiple workers performing various roles within a highly immersive operational environment. • A multi-user excavator simulation system composed of robotic control, motion capture, and hybrid-immersive interfaces. • Human subject experiments with 57 subjects to evaluate the proposed system. • The effectiveness of the system is validated by achieving higher performance metrics than the monitor-based system. • Task completion time, accuracy, and safety are significantly improved under collaborative operation with a spotter. • Enhanced human factors study of the multi-user interaction with multi-roles in the human-robot collaboration in jobsites. [ABSTRACT FROM AUTHOR]

Distribution networks aim to get the right products to consumers at the right time and in the right place. When consumers return these products, another type of logistics network is involved. This function of returning end-of-life products is referred to as reverse logistics. A critical characteristic of these reverse logistics networks is the dependence of material flow on the voluntary action of the consumer. Therefore, the success of an end-of-life collection strategy depends on the ability to anticipate the collection rate of end-of-life products at specific locations by understanding the factors that influence consumer behavior. However, there is no established tool or methodology for assessing the impact of consumer decisions on reverse logistics material flows. Therefore, this paper proposes an agent-based simulation tool to predict the performance of a reverse logistics network, taking into account the location of collection points, socio-demographic information, attitudes towards sustainable development, as well as the consumption profile. More specifically, this paper presents the configuration, calibration and validation of a simulation tool modelling the return of empty glass bottles in a small group of municipalities in Québec, Canada. Experiments also demonstrate the tool's ability to provide useful information to support the design of collection strategies that maximize return rates while minimizing installation and operating costs by optimizing the number of drop-off depots in the reverse logistics network. • Drop-off points for post-consumer voluntary glass collection. • Agent-based simulation model of consumer waste management (at consumer level). • Configuration, calibration and validation of a simulation model with empirical data. • Experiments performed with the model evaluates different logistics configurations. • Results suggest that population-specific characteristics can influence return rates. [ABSTRACT FROM AUTHOR]

In this paper we present a scalable approach based on the latency-based linear multistep compound method to use graphic processing unit (GPU) to accelerate the power system simulations with electromagnetic transients. To balance between the computational load and accuracy, we modeled the power system using shifted frequency analysis. Then, to efficiently exploit the hardware, our computational approach is designed to utilize both data-parallel and task-parallel execution. In addition, a graph-based thread safety design is introduced to achieve high scalability in the paralleled component computations. Furthermore, our implementation introduces a translation layer for different heterogeneous computing frameworks during compile time, so that a wide range of GPU devices can be supported without losing performance. Finally, benchmark results show that our approach achieves faster-than-real-time capability for systems with hundreds to thousands of nodes. [Display omitted] • Exploits data- and task-parallelism together in an automated way. • A graph-based approach to ensure thread safety to increase scalability. • A compile-time translation layer to allow execution on various platforms. • Faster-than-real-time for system with more than 10,000 dynamic components. • 82 × faster compared to an optimized sequential simulation. [ABSTRACT FROM AUTHOR]

The Full of Economic-Environment Linkages and Integration dX/dt (FeliX) model is a System Dynamics-based Integrated Assessment Model (IAM), explicitly incorporating human behaviors and their dynamic interactions among global systems. This paper presents FeliX 2.0, describing the detailed framework and key interactions among nine integrated modules. FeliX 2.0 refined its original version in population dynamics, food and land use systems, and socioeconomic settings for poverty analysis. Robust calibration is applied to key variables against their historical data since 1950. Future projections of multiple variables up to 2100 demonstrate coherences between FeliX 2.0 and the IAMs used in IPCC assessments. Both outputs (the robust calibration results and future projections) underscore the efficacy of FeliX 2.0 in capturing complex interdependencies within global systems. FeliX 2.0 stands as an informative tool and offers insights into interactions within the human-Earth system and the analysis of complex economic-environmental-social challenges in short- and long-term future. • A SD-based IAM model—FeliX 2.0—integrating human behavior for the human-Earth system simulation. • FeliX 2.0 refines FeliX 1.0 in population dynamics, food and land use, and poverty modeling. • Coherent projections up to 2100 for key variables in human-Earth systems by FeliX 2.0 • FeliX 2.0 stands as a pioneering tool for analyzing economic, environmental and social challenges. [ABSTRACT FROM AUTHOR]

The supporting structure's dynamic stiffness has an important influence on the rotor system. However, current research is mainly limited to the stiffness of a single supporting structure. A single supporting structure may not meet the requirements of the rotor system in some cases. Therefore, the method of solving dynamic stiffness of combined supporting structure is presented and compared with the traditional method based on the parallel stiffness formula. The correctness of the proposed method is verified experimentally. Then, the model of rotor system is established that takes into account the combined supporting structure's dynamic stiffness. Finally, the variation of rotor system's critical speeds and vibration response under the influence of dynamic stiffness is analyzed. An experiment is carried out to verify the influence of dynamic stiffness on the critical speeds. Furthermore, the critical speeds of rotor system will decrease under the influence of dynamic stiffness. • This paper presents a dynamic stiffness model of the combined supporting structure. • The accuracy of the proposed model is validated by experiment. • The rotor system model considering dynamic stiffness is established. • The effect of dynamic stiffness on the rotor system is verified by numerical and experimental studies. [ABSTRACT FROM AUTHOR]

The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver. [Display omitted] • Patterns are interesting from a visual and a mechanical perspective. • Their computational design is complex and an intriguing task. • We provide an efficient simulation model with our generated flat patterns. • Pipeline for direct design of tiled patterns' assemblies. • Design exploration with an interactive tool that manages geometry and loads. [ABSTRACT FROM AUTHOR]

Constructing simulation models can be a complex and time-consuming task, in particular if the models are constructed from scratch or if a general-purpose simulation modeling tool is used. In this paper, we propose a model construction framework, which aims to simplify the process of constructing discrete event simulation models for emergency medical service (EMS) policy analysis. The main building blocks used in the framework are a set of general activities that can be used to represent different EMS care chains modeled as flowcharts. The framework allows to build models only by specifying input data, including demographic and statistical data, and providing a care chain of activities and decisions. In a case study, we evaluated the framework by using it to construct a model for the simulation of the EMS activities related to acute stroke. Our evaluation shows that the predefined activities included in the framework are sufficient to build a simulation model for the rather complex case of acute stroke. [ABSTRACT FROM AUTHOR]

• A novel application of SFO algorithm to extract PV model parameters is presented. • Three-diode PV model is used in this paper. • Parameters of SFO-TDPV model are compared with other optimization based models. • The SFO-TDPV model is verified by comparing its results with measured data. • The error among these results records a value less than 0.5%. This article proposes an accurate and straightforward method for modeling and simulation of photovoltaic (PV) modules. The main target is to find the nine-parameter of a three-diode (TD) model based on the datasheet parameters, which are given by all commercial PV modules. The objective function is formulated based on short circuit, open circuit, power derivative, and maximum power equations. Two parameters (parallel resistance and photo-generated current) are calculated analytically and rest parameters are optimally designed using the sunflower optimization (SFO) algorithm. The presented method is applied to model three types of commercial PV modules (multicrystal KC200GT, poly-crystalline MSX-60, and mono-crystalline CS6K-280M). The optimal nine-parameters obtained in this paper are paralleled with that attained by other approaches. In order to assess the efficiency of the offered approach, I-V and P-V characteristics are validated with measured data under various temperatures and solar irradiations. The error among these results records a value less than 0.5%. Therefore, the simulation results indicate an excellent agreement with the measured data. This proposed approach can be utilized to model any marketable PV module based on given datasheet parameters only. [ABSTRACT FROM AUTHOR]

The authors have attempted to summarize the evolution of research in Construction Productivity (CP) through a Systematic Literature Review (SLR) from the papers published from 2006 to 2017. The methodology adopted for the study is to use the systematic literature review for selecting the papers published in a few selected major journals of construction, built environment, and construction management fields. A total of eight journals selected for the SLR and 101 papers have been selected using the keyword "Construction Productivity in the title or the Keywords". The findings of the study conclude that the studies in CP are focused in seven main areas are industry-level studies, the study of factors/attributes, measurement techniques, simulation and models, equipment and technology, issues and problems associated with CP, and improvement techniques and proposed frameworks. [ABSTRACT FROM AUTHOR]

Vehicular communication is characterized by a dynamic environment and high mobility. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in underground gallery. As first results, we present in this paper the delay spread statistics for each investigated environment. We also study the large-scale, small-scale fading and extract some time channel parameters such as root-mean-square (RMS) delay for a realistic underground propagation environment at 5.9 GHz. Since there are so far few published results for these confined environments, the results obtained can be useful for the deployment of vehicular-to-vehicular (V2V) and vehicular-to-infrastructure (V2I) communication systems inside underground mines galleries. [ABSTRACT FROM AUTHOR]

In order to solve the failure of traditional methods in the response prediction for the complex spacecraft under the wide frequency shock load, this paper provides the FE-SEA (Finite Element-Statistical Energy Analysis) hybrid modeling technique to improve the virtual mode synthesis and simulation (VMSS). Taking the L-shape typical structure as an example, the research is developed through the numerical analysis and experiment verification. In the FE-SEA hybrid model of the typical structure, the two honeycomb boards which have a higher modal density are built as the SEA model, while the connection beam that has a larger stiffness is established as FE model. And then the hybrid model is computed with the VMSS code, giving the transient response results. A shock experiment for the typical structure is carried out to verify the correctness of the methodology above. The results indicate that the numerical results have the similar trend and magnitudes with the ones of the experiment in time domain, and the shock response spectrum (SRS) of the numerical results can realize the ±6 dB tolerance limit compared with the experiment results. This paper finds that the FE-SEA hybrid modeling techniques for the typical structure can effectively overcome the problem of the dynamic differences between the substructures under the excitation of shock load, and the combination of FE-SEA and VMSS has the ability to predict the shock responses of the typical structure accurately. The research methods and conclusions achieved in this paper are expected to further extend to the shock response calculation of the complex spacecraft structures. [ABSTRACT FROM AUTHOR]

Abstract Terrestrial laser scanning is extensively adopted in the area of high-precision monitoring and three-dimensional measurement. Architectural structures today are increasingly complex and health monitoring plays an important role in guaranteeing their safety. Therefore, how reliability deformation monitoring can be improved is one of the key problems in the field of engineering. This paper combines the three-dimensional laser scanning technology and finite element method (FEM) to investigate the deformation mechanism of arched structures. Within this paper, we simulated arched structures using the FEM, which is consistent with the result of terrestrial laser scanner (TLS) measurement. We aimed at constructing an intelligent and efficient FEM model which can be extensively applied in the monitoring of many constructs, such as bridges and ancient architecture. The focus in this research lies mainly on deformation analysis, which is based on FEM model simulation with the calibration of TLS measurement. [ABSTRACT FROM AUTHOR]

A Physical Internet of hubs ('PI-hubs') is a network of logistics terminals that allow shipments to flow through, similar to the flow of Internet data packets. PI-hub networks are a recent proposal and their properties have not been studied in detail. In this paper we model PI-hub networks using the theory of queuing networks, particularly, Jackson queuing networks. Under certain assumptions, PI-hub networks behave like Jackson queuing networks, and thus analytical methods can be used to calculate important properties such as throughputs, processing times, traffic size etc. In this paper we analyse the performance characteristics (throughput, queue size) for each PI-hub and for the whole PI-hub network. [ABSTRACT FROM AUTHOR]

Abstract The lifted sample-time approach has been extensively applied to analyze the behavior of a Networked Control System (NCS) under instances of packet-drop and/or variable communication latency (jitter) of varying durations. This paper combines the simplicity of the lifted sample-time approach in modeling an NCS under arbitrary but bounded instances of packet-drop and/or jitter with the proven L 2 induced norm based approach of controller design to realize an NCS which is capable of preserving the designed value of the norm under assumed conditions of packet-drop and/or jitter and hence a satisfactory time response under these conditions. The design methodology presented in this paper assumes a state feedback controller and uses a simple criterion based on a Linear Matrix Inequality (LMI). The methodology is validated using credible offline and real-time simulations. Highlights • Lifted sample-time approach for NCS is used. • Stability and time response is analyzed using MSFC to control the plant over network under jitter and packet-drop. • LMI based methodology to analyze the stability and controller design for NCS has been proposed. • The LMI formulations use a disturbance attenuation level as a specification for the lifting system. • The methodology has been demonstrated with credible offline and real-time simulations. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a speed sensorless control scheme named as finite control set-model predictive current control (FCS-MPCC) using a modified fictitious ohmic quantity (R) based model reference adaptive system (MRAS) for grid-connected doubly-fed induction machine (DFIM) drive. The variables of the reference model of this speed sensorless scheme (R-MRAS) are represented in stationary reference frame while those for the adaptive model are denoted in synchronously rotating reference frame. The sensorless formulation thus obtained is completely independent of any stator/rotor resistance terms. The scheme is also devoid of any stator/rotor flux estimation. Moreover, the intuitiveness of FCS-MPCC brings in additional flexibility in comparison to the conventional control techniques like field oriented control (FOC) and direct torque control (DTC). The overall scheme demonstrates faster execution time than FOC/DTC based control of DFIM drive. The proposed control algorithm is simulated and tested for limited speed range application in MATLAB/Simulink. The validation of simulation results are further done by experimentation on a dSPACE-1103 based DFIM laboratory setup. Highlights • In this paper, MRAS based sensorless speed estimation of DFIM drive by FCS-MPCC is reported. • The estimation scheme insensitive to the changes in machine parameters. • The overall scheme demonstrates faster execution time than FOC/DTC based control of DFIM drive. [ABSTRACT FROM AUTHOR]

Abstract The article shows Generalized Interpolation Material Point Method numerical simulation of the Sainte Monique landslide. The simulation uses a strain-rate dependent Tresca constitutive model, extended with strain softening behaviour for structured clays. First, the paper replicates fall cone tests to validate the constitutive model and to select the material parameters. Afterwards, the paper shows the Sainte Monique landslide simulation which additionally considers shear band thickness to reduce the mesh-dependence. The results suggest that the strain-rate affects the prediction of the run-out distances and leads to the landslide acceleration-deceleration cycles (reported in, e.g. Corominas et al., 2005; Wang et al., 2010). [ABSTRACT FROM AUTHOR]

Abstract Mode I crack propagation in prestressed concrete sleepers B70 is simulated by a fracture mechanics approach. The plastic damage model, which takes the non-linear behavior of concrete into account, is utilized to calculate crack length and crack mouth opening displacement (CMOD). Numerical data from prestressed concrete sleepers B70 under three-point bending load are compared with those of the proposed fracture mechanics model. In this study, fracture mechanics parameters of prestressed concrete sleepers are investigated. Sleepers with the length of initiation crack of 5 to 45 mm (with 10 mm steps) and the width of initiation crack of 2 to 8 mm (with 2 mm steps) are analyzed. Sleeper cracks are created in the notch and both of its sides. These analyses confirm that the structural behavior of prestressed concrete sleepers can be predicted by a simple fracture mechanics model provided that the related material properties like KIC, crack length and CMOD, are known. Highlights • Fracture mechanics of pre-stressed concrete sleeper B70 is studied with numerical analysis. • We model B70 sleeper which have 5 crack initiation lengths and 4 crack initiation width in center of sleepers. • Force-Crack length and Force-CMOD diagrams are measured for notched sleeper models in center and sides of sleepers and compared together. • This paper follows sleeper B70 paper "F. Rezaei, S.M. Farnam, Fracture mechanics analysis of pre-stressed concrete sleepers via investigating crack initiation length, Eng. Fail. Anal, 58 (2015) 267–280". [ABSTRACT FROM AUTHOR]

Abstract In recent years, more and more existing building has an ever increasing requirement of retrofit, which has been developed from individual measure to combination package of multiple measures. It has become the challenging task for screening building multiple energy retrofit measures package (BMERMP). In this paper, a stepwise screening methodology for BMERMP is proposed considering economic and risk aspects, which integrates Life-Cycle Cost (LCC) and Monte Carlo (MC) analysis. First of all, this paper puts forward a calculation reference table for energy saving retrofit potential. In addition, this paper also uses unit energy saving incremental cost (UESIC) to screen technology and suggests economic internal rate of return（EIRR）as cost-benefit analysis index of BMERMP. Furthermore, the authors propose the concept of Value-at-Risk (VaR) as an effective measure to control the risk. The VaR for EIRR is determined by risk variation and can be obtained through MC simulation. Meanwhile, the study takes a commercial building for example, this building comprises 19 measures in initial BMERMP by energy diagnosis and the VaR of initial BMERMP is 97.6%, which has a high risk. According to the ranking of UESIC value, when 4 high cost technologies are reduced, the VaR can be reduced to 0.07%, then the economy of BMERMP is feasible and the risk is controllable. This paper provides a new perspective for the decision maker to select BMERMP. Highlights • A stepwise screening methodology to select building multiple energy retrofit measures package (BMERMTP) is proposed. • The screening methodology integrate Life-Cycle Costing(LCC) and Monte Carlo(MC) analysis. • Cost-benefit analysis for BMERMTP adopt the economic benefits of energy retrofits in the economic period. • Present the concept of Value-at-Risk (VaR) as an effective measure to control the risk for BMERMTP. • It suggests calculation table for building energy-saving retrofit potential. [ABSTRACT FROM AUTHOR]

Abstract In recent years, the application of imaging satellites has entered a completely new stage, with the new demands such as rapid response to emergency events, observation of large-scale regional targets and multivariate data fusion, the multi-autonomous satellite constellation has been proposed. This paper first designs the structure of multi-autonomous satellite constellation, and a centralized-distributed structure is proposed. This structure could improve the dynamic response capacity of the whole constellation. Then, this paper adds adapted filtering mechanism to single autonomous satellite online scheduling algorithm to enhance its performance. This article also pays more attention on task allocation strategies of the master satellite in constellation, and ten different task allocation strategies based on five dimensions are analyzed by simulation experiments. At last, this paper extracts several characteristic features of the regular observation targets and designs a selector based on support vector machine (SVM). This selector could select an appropriate strategy according to the features of each experiment scenario. [ABSTRACT FROM AUTHOR]

Abstract PID controllers are still widely practiced in the industrial systems. In the literature, many publications can be found considering PID controller design for unstable processes. However, owing to the structural limitations of PID controllers, generally, good closed loop performance cannot be achieved with a PID for controlling unstable processes and usually a step response with a high overshoot and oscillation is obtained. On the other hand, PI–PD controllers are proved to give very satisfactory closed loop performances for unstable processes. The paper presents a simple design method to tune parameters of a PI–PD controller for the control of the unstable processes with time delay. The proposed method is based on plotting the stability boundary locus, which is a locus dependent on the parameters of the controller and frequency, in the parameter plane. The method uses a new concept named centroid of the convex stability region. Simulation examples and an experimental application are given to illustrate the superiority of the proposed method over some existing ones. Highlights • The paper represents a novel method for PI–PD control of the unstable systems. • The proposed method uses a new concept named centroid of convex stability region. • Ability of being extended to uncertain plants of the proposed method by means of Kharitonov theorem is an important advantage. [ABSTRACT FROM AUTHOR]

Mould growth on building materials is a complex phenomenon involving various causes environmental conditions including temperature and relative humidity, nutrients, exposure time. Environmental conditions and nutrient are closely related to physical properties of building materials. Thus, the appropriate selection of building materials is very important for prevention of adverse health effects due to mould growth. The aim of this study is to determine the influence of the hygric properties of interior finishing materials on the mould growth. This paper presents the results of mould growth risk evaluation with variation of hygric properties of interior finishing materials using hygrothermal and bio-hygrothermal simulation approaches. An experimental study was conducted to characterize the hygric properties of wallpapers which are used mainly as interior finishing material in residential buildings. Six types of wallpapers and two type of hygric properties (water vapour transmission property and moisture storage function) were selected for the study. WUFI Plus was selected for a whole building hygrothermal simulation. The results from the hygrothermal simulation were used for the assessment of mould growth risk using a biohygrothermal calculation model, WUFI-Bio. The simulation results show the clear correlation between the mould growth rates and the hygric properties of wallpapers. [ABSTRACT FROM AUTHOR]

Highlights • To our knowledge this is the first journal paper to include in-depth thematic analysis of expert interviews regarding the use of building performance simulation in Australia, with a particular focus on lower quality office buildings. • In this paper, the typical simulation and upgrade process operating in practice in Australia is compared with a previously outlined optimal strategy, and a 'Revised Systematic Approach' to sustainable building retrofits is proposed. • The thematic analysis of interview responses identified many of the drivers and barriers influencing the user of building simulation tools. • Several practices employed by practitioners that are likely to greatly increase the uncertainty associated with simulation results were identified. • The lack of reliable and accurate data was highlighted as a key issue facing this sector, and the implications of the uncertainty introduced by the necessary use of assumptions, particularly concerning innovative financing initiatives, is discussed. Abstract Building Performance Simulation (BPS) has become an important tool in the upgrading of the existing commercial building stock. It allows a user to predict energy savings from upgrades, and thereby optimise the energy, financial or other benefits of an energy efficiency upgrade. The current paper presents the findings from a qualitative investigation into the use of BPS in the Australian commercial building retrofitting industry. The interviews had a particular focus on challenges for lower quality (known as secondary grade or mid-tier) office buildings. Twelve semi-structured interviews were undertaken with stakeholders in the building energy retrofitting industry, including consultants, government administrators and building managers. Thematic analysis of the interview data revealed numerous challenges for BPS users, primarily related to the lack of reliable, accessible data regarding building operations and energy use in Australia. The poor data availability encouraged the use of simulation to inform decisions but required the modeller to use assumptions and heuristics to develop the model. This, in turn, necessitated a reliance on the expert knowledge of the simulation user, and made the interrogation of a building model by a third party problematic. [ABSTRACT FROM AUTHOR]

Highlights • Constitutive equations for a vertical rod bundle are reviewed. • Dependence of distribution parameter on flow conditions is discussed. • 1D momentum equation by considering void fraction distribution is discussed. • Effect of channel size on interfacial area concentration is discussed. Abstract In view of the quality assurance of two-phase flow simulations, CSAU (Code Scalability, Applicability, and Uncertainty) methodology and code V & V (Verification and Validation) have been proposed. The estimation of simulation uncertainty is indispensable in using best-estimate computational codes. A key of successful two-phase flow simulations is to use the state-of-the-art constitutive equations to close the mathematical system used in two-phase flow analyses. The advanced constitutive equations should be developed based on “physics” behind phenomena and should consider scaling parameters which enable their application beyond test conditions used for a code validation. Two-phase flow simulations in a rod bundle is important in various industrial apparatuses such as heat exchangers and nuclear reactors. Constitutive equations for two-phase flows in a vertical rod bundles have been advanced in recent five years. In view of this, this paper provides a comprehensive review of most advanced constitutive equations for two-phase flow analyses in a vertical rod bundle. The constitutive equations of two-phase flow parameters reviewed in this paper are flow regime map, void fraction, void fraction covariance and relative velocity covariance, interfacial area concentration and wall friction. In addition, an exact formulation of one-dimensional momentum equation in two-fluid model considering void fraction distribution is discussed. [ABSTRACT FROM AUTHOR]

Abstract Immersive Virtual Reality-based collaborative BIM 4D simulation can offer a unique, supportive environment for conducting constructability analysis meetings in the construction industry. While many research works have addressed various aspects of VR-based 4D simulation, there is still no comprehensive and neutral framework to help both practitioners and experts to identify the main challenges to address. This paper proposes four main complementary steps with which to define the VR environment, to develop the 4D model, to prepare and transfer the model in the VR system and to conduct constructability analysis meeting. In the current state of the framework, the 4D-based constructability analysis is more about the collaborative use of 4D rather than the collaborative generation and interaction with the 4D model. Each step of the framework is supported by appropriate methods and tools. A collaborative personas-based case study helps to evaluate the framework and to show how it can be used. Compared to recent related works, the proposed framework is more structured and comprehensive, providing a structured approach using concepts from multiple scientific areas. Highlights • The article proposes to support constructability analysis meetings with immersive VR-based collaborative 4D simulation. • The framework presents a detailed process for passing a 4D simulation from Navisworks into an immersive VR environment. • It uses collaboration personas theories to describe the definition of the practitioners' needs and the VR environment. • The paper presents innovative metamodels to support the use of the proposed framework. [ABSTRACT FROM AUTHOR]

Abstract The control-oriented modeling and real-time simulation method for a dual-mode scramjet combustor has been conducted in this paper. The 1-D unsteady model coupled with isolator shock train model and oblique shock wave modification can treat variable area, fuel addition, combustion heat release, variable specific heat, inflow air vitiation component, wall friction and mixing efficiency. Combustion is simplified into mass and heat addition process. So this paper discusses heat release distribution obtaining method which can be applied in scramjet combustor 1-D flowfield simulation in detail. It is fit for certain scramjet combustor configuration and acceptable over a wide range of inflow conditions. By mixed programming of C and Matlab, the code of model solving is capsuled into S-Function which can be used in SIMULINK. The control-oriented model is built on SIMULINK platform. When the model runs in a single-core 3.6 GHz Intel Core i7-4790 processor, computation time-consuming is found to require 5–10 ms within a control period. The computing speed indicates very promising, because model is compact enough to run in real time, and it can be used as an embedded model in control system research. This model can also be used to analyze unsteady and steady flowfield characteristic. The safety boundary codetermined by unstart and over-temperature is conducted using this model. Highlights • Control-oriented 1-D unsteady model was presented for dual-mode scramjet combustor. • By mixed programming, real-time model was built on SIMULINK platform. • The heat release distribution obtaining method was discussed and explained. • The unsteady, steady flowfield process and safety boundary were analyzed. [ABSTRACT FROM AUTHOR]