Loose Coupling Model Research Articles

The development of multi-physics approach with Monte Carlo and computational fluid dynamics coupling for reactor cores

Highly accurate solutions for neutronic and thermal hydraulic phenomena in reactor cores certainly improve the safety conclusions about the reactors. The coupling methodology of governing physics of these two fields by using Monte Carlo and computational fluid dynamics (CFD) methods was described in this study with its application to Istanbul Technical University (ITU) TRIGA Mark II Research Reactor. As a different approach, instead of not modelling top and bottom grid plates of the reactor that is the common practice for geometrical simplification, the effect of grid plates on flow hydrodynamics was included into the conjugate heat transfer calculations as boundary conditions. The investigation on the effect of core element temperature, cross sections, and S(α,β) thermal scattering data showed the need of proper coupling of neutronic and thermal hydraulic fields since 30–45% relative error on excess reactivity value of the ITU research reactor was observed. With the developed loose coupling model, 483 individual cross section and 483 different S(α,β) thermal scattering data were generated by using NJOY nuclear data generation code and MAKSXF and OTF utilization tools of MCNP6.2 code. The reactivity loss against power increase in research reactor value of this study showed 6% relative error with loose coupling comparing to maximum 50% without coupling.

VO and GPS integrated navigation algorithm based on plane constraint

In view of the deficiencies of GPS in the urban environment, such as signal occlusion, multipath and Non-LOS, this paper proposes a solution that using a low-cost monocular camera instead of inertial navigation system to combine with GPS. Firstly, considering that the actual road conditions of the vehicle are mostly plane and in order to reduce the computational resources of visual odometer (VO), this paper establishes a VO solving model based on plane constraint; then the VO&GPS loose coupling model is proposed. The position error and yaw angle error of the two sensors are taken as input, and the errors are filtered by the adaptive Kalman filter. Experiments show that the positioning effect of VO&GPS loose coupling system is better than that of single GPS, and it can suppress the drift of VO, which can meet the positioning requirements when satellite signals are interfered in a short time.

Application of a loose coupling model for assessing the impact of land-cover changes on groundwater recharge in the Jinan spring area, China

The Jinan spring area is one of the fastest developing and most water-stressed regions of China. Because of rapid urban expansion, groundwater recharge has been greatly influenced by land-use/cover change (LUCC). To gain an improved understanding of how the groundwater recharge affected by LUCC from 1960 to 2015, normal years, including 1985, 2000, and 2015, were selected using the Pearson-III distribution. Land-cover types of the normal years were classified using Thematic Mapper images. A loose coupling of an urban expansion model and a hydrological model was used to quantify the impact of LUCC on groundwater recharge. The results showed that land converted to built-up land was mainly mixed forest and arable land. The proportion of land-use types that remained unchanged was generally less than 50%, except for built-up land. In 2030, the area of built-up land will continue to increase, while the area of arable land and mixed forest will decrease correspondingly. The mean annual groundwater recharge was 88.32, 87.95, 73.31, and 76.17 mm for 1985, 2000, 2015, and 2030, respectively, which accounts for 14.01, 12.90, 12.20, and 11.98%, respectively, of the annual precipitation. In the water balance of the study area, only a small fraction (11.98–14.01%) of precipitation recharges the groundwater, and the remainder is lost by evapotranspiration (81.41–82.05%) and to a lesser extent by surface runoff (4.15–6.83%). The amount of groundwater recharge is mainly controlled by precipitation and potential evapotranspiration. Recharge is negatively correlated with the drought index. The ratio of groundwater recharge to precipitation decreased at a rate of − 0.06% from 1985 to 2015. The recharge/precipitation ratio is expected to decrease by a further 0.22% by 2030. The decrease in the ratio is primarily the result of an increase in built-up land areas, and a decrease in mixed forest and arable land areas.

3D full coupling model for strong interaction between a pulsating bubble and a movable sphere

In this study, we establish a full coupling model (FCM) to simulate strong bubble-sphere interactions based on a three-dimensional boundary integral method. Different from the conventional loose coupling model (LCM), FCM adopts several auxiliary functions to deal with the mutual dependence between the hydrodynamic force and the sphere acceleration. In addition, the weighted moving least square method, a mesh density control scheme and an adaptive mesh refinement scheme are implemented to improve the quality of mesh on the deformable bubble surface. To validate the present model, convergence tests on different mesh sizes and time steps are conducted at first. The numerical results are also compared with the axisymmetric model, in which consistent results have been achieved. We further make comparisons between the numerical results and those from several experiments under different boundary conditions. For weak interaction cases, both LCM and FCM can give the results that have good agreement with the experiment data. As the interaction effects become stronger, the advantage of the FCM over the LCM becomes increasingly obvious. Particularly, when the pulsating bubble is in contact with the sphere surface, the essential physical features of the experiments can be well reproduced by the FCM while the predictions by the LCM are significantly different from the experiment. The present 3D model can be further extended to study more complex underwater contact explosions, cavitation inception on a structure and airgun bubble dynamics.

Electromagnetic-structural analysis and improved loose coupling method in electromagnetic forming process

Electromagnetic forming (EMF) is a high-velocity forming technology, which can effectively overcome the difficulties in the light-weight alloy processing. At present, the loose coupling model or the sequential coupling model is used to analyze the electromagnetic-structural coupling process in EMF, but the simulation results cannot clarify the relationship between the electromagnetic parameters and structural parameters. In this paper, the loose coupling model, the displacement model, the velocity model, and the complete coupling model are simultaneously established to analyze the effect of the displacement and motional electromotive force on the forming velocity in the EMF process. The results show that the forming velocity is slightly affected by the workpiece displacement but mainly dominated by the motional electromotive force when the forming speed is smaller than 100 m/s. When the forming velocity is larger than 200 m/s, both the workpiece displacement and the motional electromotive force affect the forming velocity. Based on this analysis, an improved loose coupling method is proposed in this paper. The experiments of electromagnetic forming have been done at the Wuhan National High Magnetic Field Center (WHMFC), China. The results show that the maximum deformation at the workpiece center of the experiments, the loose coupling model, and the improved loose coupling model is 25.5, 38.3, and 25.2 mm respectively. Our studies show that the workpiece deformation profile obtained by the improved loose coupling method matches well with the experiment because it takes both the workpiece displacement and the motional electromotive force into consideration.

Writing for publication group: professional development situated in the interstices of academia and performativity

This article features nine ‘narratives of experience’ illustrative of academics engaged in an alternative Professional Development (PD) activity, referred to as Writing for Publication, in a regional Australian university. Each narrative adopts a critical stance to academic practice situated in what Ball defines as a ‘culture of performativity’ perpetuated by a ‘global neoliberal environment’. Contrary to professional development built primarily around sporadic content-provision and credential-based activities, Writing for Publication represents an alternative approach to professional development, a loose-coupling model, that gives validation to academics engaged in navigating dominant neoliberal discourses driving higher education filtered through the interstices or sites for identity-creation, agency formation and emerging communities of practice.

Aeroelastic analysis of helicopter rotors using computational fluid dynamics/comprehensive analysis loose coupling model

A new rotor computational fluid dynamics(CFD)/comprehensive analysis (CA) loose coupling model is presented in this paper. In the coupled analysis, moderate deflection beam theory is employed to obtain the blade motions, while a high fidelity, overset grid based N-S solver is adopted to compute airloads. In order to improve the computation efficiency, the delta method is used to integrate the airloads computed by CFD analysis into the CA module. Based on the aforementioned method, the airloads at two challenging level-flight conditions of the UH-60A Blackhawk helicopter are investigated, and the simulated results show that the CFD/CA coupling model developed in this paper is efficient and accurate in capturing the rotor unsteady airloads.

Programmable virtual network as a service: towards a future Internet testbed based on IaaS cloud

During recently years, several OpenFlow-enabled testbeds have been deployed in world-wide research community. Typically, these OpenFlow-enabled testbeds need to stitch to other testbeds to link to virtual servers and immit experimentation traffic. From the view point of researchers, these OpenFlow-enabled testbeds only provide OpenFlow networking resource, and they have to resort to other experiment infrastructure to provide computing and storage resource. Due to the OpenFlow networking and other resource belongs to different infrastructure provider and is managed by their own control software, it is difficult to coordinate these partners to provide a full programmable experiment environment. Meanwhile, the control software of these testbeds are tight coupling with their substrate resources, which means that these substrate resources, together with virtualization technologies, are permanently dedicated to the control software and difficult to be used by other services. In this paper, a new future Internet testbed architecture based on the open Infrastructure-as-a-service cloud and software defined network (SDN) paradigm is proposed. It extends the current virtual network service by adding programmable virtual switch and controller resources that can be controlled by the researcher. Its loose coupling model allows the testbed operator decouple the experiment service from the infrastructure provider, which is a more flexible way to build the testbed. The initial prototype implementation in this paper shows that this new testbed architecture built on IaaS cloud and SDN is feasible and flexible to provide programmable virtual network service.

Loose Coupling Based Reference Scheme for Shop Floor-Control System/Production-Equipment Integration

Coupling shop floor software system (SFS) with the set of production equipment (SPE) becomes a complex task. Itinvolves open and proprietary standards, information and communication technologies among other tools andtechniques. Due to market turbulence, either custom solutions or standards based solutions eventually require aconsiderable effort of adaptation. Loose coupling concept has been identified in the organizational design communityas a compensator for organization survival. Its presence reduces organization reaction to environment changes. Inthis paper the results obtained by the organizational design community are identified, translated and organized tosupport the SFS-SPE integration problem solution. A classical loose coupling model developed by organizationalstudies community is abstracted and translated to the area of interest. Key aspects are identified to be used aspromoters of SFS-SPE loose coupling and presented in a form of a reference scheme. Furthermore, this referencescheme is proposed here as a basis for the design and implementation of a generic coupling solution or couplingframework, that is included as a loose coupling stage between SFS and SPE. A validation example with various setsof manufacturing equipment, using different physical communication media, controller commands, programminglanguages and wire protocols is presented, showing an acceptable level of autonomy gained by the SFS.

Using Department Protocols as Indicators of Emergent Organizational Reality in a Ground‐Level Administrative Subunit

This study examines administrative protocols established by a ground‐level subunit in a complex organization during a 13‐year period. The protocols are identifiable, verifiable, and (for the questions examined in this study) objectively interpretable. The authors report tangible evidence that the subunit developed some of its own emergent organizational characteristics, consistent with predictions using a loose coupling model. Copresent, however, clear manifestations are also found of the subunit at certain times merely acting out unitary executive–style policy decisions that have been made at higher administrative levels in the organization.

Preliminary Design System for Concrete Box Girder Bridges

A neural network-based design system is presented in this paper for preliminary design of concrete box girder bridges. The system is based on a loose coupling model that integrates the artificial neural network and the fuzzy network to perform the task of noisy data filtering, knowledge extraction, and candidate synthesis. After a comparative study, the radial basis function neural network is chosen in the design knowledge generation instead of the commonly used back-propagation neural network. The fuzzy network is employed to determine the integer types of design parameters. The developed system provides a few feasible design configurations, and enables the user to overwrite some of the design parameters, so that that user can have a wide choice in his preliminary design. The accuracy of the neural network testing and the influence of the size of the design cases on the neural network prediction are discussed. A design example is included to illustrate the design procedure.