Code Coupling Research Articles

Luhmann's theory of psychic systems and communication in social work practice

Summary The aim of the article is to increase interest in the social systems theory of Niklas Luhmann among practicing social workers. The enigmatic statement from Luhmann that only ‘communication can communicate’ is explained with reference to his autopoietic systems theory which identifies three distinct types of systems: systems of communication, systems of life and systems of consciousness. The article proceeds to describe the meaning and nature of autopoietic systems before discussing the place of the individual in Luhmann’s theory and how it is relevant for practicing social workers. The concepts of psychic systems, structural coupling and communicative codes are described and discussed. Findings The conceptual framework derived from Luhmann’s systems theory is applied to a description of the social worker/client encounter. Communication in social work practice is polyphonic: it is structured by a hybrid of communicative codes which the practitioner must draw on depending on the auspices of the communicative context. The key conclusion of the article is that Luhmann retains a conception of the individual as an active agent in systems theory aiming ‘noise’ at the function systems with which the individual interacts. Applications The article suggests that the systems perspective presented provides social workers with a useful and nuanced framework for reflective practice because it makes the components of the practice system explicit and visible.

Sensitivity kernels for body tides on laterally heterogeneous planets based on adjoint methods

SUMMARY We apply the adjoint method to efficiently calculate the linearized sensitivity of body tide observations to perturbations in density, elastic/anelastic moduli and boundary topography. This theory is implemented practically within the context of normal mode coupling calculations, with an advantage of this approach being that much of the necessary technical machinery is present in existing coupling codes. A range of example sensitivity kernels are calculated relative to both spherically symmetric and laterally heterogeneous background models. These results reaffirm the conclusions of earlier studies that the M2 body tide is strongly sensitive to spherical harmonic degree-2 density variations at the base of the mantle. Moreover, it is found that the sensitivity kernels are only weakly dependent on the background model, and hence linearized methods are likely to be effective within inversions of body tide observations.

Development and application of Monte Carlo and COMSOL coupling code for neutronics/thermohydraulics coupled analysis

The tightly coupled solution of neutronics and thermal-hydraulics play an important role in precise simulation of fuel designs. Fully Ceramic Microencapsulated (FCM) fuel was one of the popular designs for accident tolerant fuel. To simulate advanced fuel types such as FCM fuel, a new method was proposed to couple the Monte Carlo code RMC with multi-physical software COMSOL. The MATLAB interface was adopted for coupling, and the superimposed structured mesh was applied to the mesh mapping and data interpolation between the structured meshes of RMC and unstructured meshes of COMSOL. Then the coupling code was verified by a typical PWR fuel rod and a FCM case. Results show that the calculated power and temperature distributions are reasonable, which can capture the self-shielding effect of thermal neutrons. Comparing with the traditional “cell-to-cell” mapping, the proposed method has advantages of good geometric flexibility and high accuracy, which can be applied to multi-physics simulations of different fuel designs.

A Coupling Framework for Multi-Domain Modelling and Multi-Physics Simulations.

This paper describes a coupling framework for parallel execution of different solvers for multi-physics and multi-domain simulations with an arbitrary number of adjacent zones connected by different physical or overlapping interfaces. The coupling architecture is based on the execution of several instances of the same coupling code and relies on the use of smart edges (i.e., separate processes) dedicated to managing the exchange of information between two adjacent regions. The collection of solvers and coupling sessions forms a flexible and modular system, where the data exchange is handled by independent servers that are dedicated to a single interface connecting two solvers’ sessions. Accuracy and performance of the strategy is considered for turbomachinery applications involving Conjugate Heat Transfer (CHT) analysis and Sliding Plane (SP) interfaces.

The Exascale Framework for High Fidelity coupled Simulations (EFFIS): Enabling whole device modeling in fusion science

We present the Exascale Framework for High Fidelity coupled Simulations (EFFIS), a workflow and code coupling framework developed as part of the Whole Device Modeling Application (WDMApp) in the Exascale Computing Project. EFFIS consists of a library, command line utilities, and a collection of run-time daemons. Together, these software products enable users to easily compose and execute workflows that include: strong or weak coupling, in situ (or offline) analysis/visualization/monitoring, command-and-control actions, remote dashboard integration, and more. We describe WDMApp physics coupling cases and computer science requirements that motivate the design of the EFFIS framework. Furthermore, we explain the essential enabling technology that EFFIS leverages: ADIOS for performant data movement, PerfStubs/TAU for performance monitoring, and an advanced COUPLER for transforming coupling data from its native format to the representation needed by another application. Finally, we demonstrate EFFIS using coupled multi-simulation WDMApp workflows and exemplify how the framework supports the project’s needs. We show that EFFIS and its associated services for data movement, visualization, and performance collection does not introduce appreciable overhead to the WDMApp workflow and that the resource-dominant application’s idle time while waiting for data is minimal.

A trans-dimensional multi-physics coupled analysis method for direct-steam-generation parabolic-trough loop

Quantification of the thermal stress-induced deformation issue of the heat collection element (HCE), which is hardly avoidable during the practical operation of parabolic-trough (PT) concentrated solar power (CSP) plants is of primary importance, especially with direct steam generation (DSG) technology. However, currently-available analysis methods are either inefficient or inaccurate. In the present work, a trans-dimensional multi-physics coupled analysis method is proposed. The method consists of a one-dimensional loop-level thermo-hydrodynamic model, which efficiently predicts the global performance of loop, and three-dimensional optical-hydrodynamical-thermal-mechanical coupled model, which accurately quantifies the local deformation of HCE. The information exchange between the two models is accomplished through a self-developed coupling code. After model validation by experimental data, the proposed method is applied in different cases for the preheating, boiling (annular/stratified flow pattern), and superheating sections of a DSG-PTC loop. The worst scenario is found to exist in the superheating section, giving the maximum circumferential temperature difference of 29 K and the maximum z-deviation of −1.67 cm. When it is stratified flow (x = 0.56) in the boiling section, the corresponding values are 21 K and 0.69 cm. It should be noted that, considering the practical installation errors and the interaction between HCE and concentrator, the deformation not only changes the distribution of heat flux but also potentially causes optical loss. Meanwhile, the results verify the capability of the proposed analysis method in performing thermal stress deformation analysis on entire loop, which can be further extended to various forms of line-focused CSP technologies.

Reliability and reproducibility in computational science: implementing validation, verification and uncertainty quantification in silico.

Reliability and reproducibility in computational science: implementing validation, verification and uncertainty quantification in silico.

Motivations, benefits, and issues for adopting Micro-Frontends: A Multivocal Literature Review

Micro-Frontends are increasing in popularity, being adopted by several large companies, such as DAZN, Ikea, Starbucks and may others. Micro-Frontends enable splitting of monolithic frontends into independent and smaller micro applications. However, many companies are still hesitant to adopt Micro-Frontends, due to the lack of knowledge concerning their benefits. Additionally, provided online documentation is often times perplexed and contradictory. The goal of this work is to map the existing knowledge on Micro-Frontends, by understanding the motivations of companies when adopting such applications as well as possible benefits and issues. For this purpose, we surveyed the academic and grey literature by means of the Multivocal Literature Review process, analysing 173 sources, of which 43 reported motivations, benefits and issues. The results show that existing architectural options to build web applications are cumbersome if the application and development team grows, and if multiple teams need to develop the same frontend application. In such cases, companies adopted Micro-Frontends to increase team independence and to reduce the overall complexity of the frontend. The application of the Micro-Frontend, confirmed the expected benefits, and Micro-Frontends resulted to provide the same benefits as microservices on the back end side, combining the development team into a fully cross-functional development team that can scale processes when needed. However, Micro-Frontends also showed some issues, such as the increased payload size of the application, increased code duplication and coupling between teams, and monitoring complexity. Micro-Frontends allow companies to scale development according to business needs in the same way microservices do with the back end side. In addition, Micro-Frontends have a lot of overhead and require careful planning if an advantage is achieved by using Micro-Frontends. Further research is needed to carefully investigate this new hype, by helping practitioners to understand how to use Micro-Frontends as well as understand in which contexts they are the most beneficial.

Mechanical properties of CFRP-strengthened prestressed concrete cylinder pipe based on multi-field coupling

Broken prestressing wires in prestressed concrete cylinder pipe (PCCP) can cause incident of pipe burst. A method was proposed to repair damaged PCCP with broken wires by externally bonding carbon fiber reinforced polymer (CFRP). A finite element model was established and calibrated against the data from a prototype-scale laboratory test. Upon calibration, a three-dimensional numerical model was built to simulate the response of PCCP pipeline with five segments. Multi-field coupling was accomplished by Mesh-based parallel Code Coupling Interface (MpCCI) to incorporate the soil–pipe interaction and the effect of hydrodynamic pressure for PCCP. The effect of externally bonded CFRP to repair PCCP with broken wires was systematically analyzed. Results show that at a certain number of broken wires, the use of CFRP for pipe repair can significantly reduce the strains for each pipe component and increase the resilience of PCCP. The improved PCCP performance was assessed on the basis of crack visibility in the concrete core, and the deformation of the steel cylinder. The CFRP strain was much less than its ultimate strain, when cracks in the concrete core became visible and the steel cylinder yielded, suggesting that failure of PCCP could be ahead of CFRP.

Spatially Coupled LDPC Codes via Partial Superposition and Their Application to HARQ

This paper proposes a new class of spatially coupled codes, which are constructed by sending codewords of a low-density parity-check block code (LDPC-BC) in a block Markov superposition transmission (BMST) manner, resulting in the BMST-LDPC codes. Different from the conventional spatially coupled LDPC (SC-LDPC) codes, the proposed BMST-LDPC codes can have encoder/decoder implemented using the structure of the corresponding LDPC-BCs. The proposed construction is universal , which is applicable to any existing LDPC-BCs including the 5 G New Radio (5G-NR) LDPC-BCs to obtain extra coding gains. The proposed BMST-LDPC codes are also a special class of BMST codes, which have lower error floors even with an encoding memory of one, inheriting a low decoding latency. Moreover, partial superposition , where a fraction of the coded bits are superimposed onto the following codewords, is introduced to alleviate the decoding error propagation. The construction can be optimized, for random long codes, by a protograph-based extrinsic information transfer (EXIT) chart analysis, or by a one-dimensional search for structured block codes. Furthermore, the BMST-LDPC scheme is integrated with the hybrid automatic retransmission request (HARQ) over the block fading channel, improving the throughput performance. Numerical results are presented to validate our analysis and demonstrate the performance advantage of the BMST-LDPC codes over the LDPC-BCs. They also show that the proposed HARQ scheme can yield a throughput improvement of up to 10% over the conventional HARQ scheme.

Development of a multi-physics coupling system based on ICoCo interface and its validation on NEA-OECD core transient benchmark

This paper describes the development of a multi-physics coupling system of Thermal-Hydraulics (T-H) code CORTH and reactor dynamics diffusion code CORCA-K for nuclear core analysis. The coupling system is based on a typical server-client coupling system ICoCo (Interface for Code Coupling), where each code is first wrapped by the ICoCo interface and then compiled into a shared library. And a 3rd-party library named MEDCoupling is adopted to handle the mesh interpolation and field mapping between CORTH and CORCA-K.The prediction capabilities of CORCA-K/CORTH are proved by the analysis of the NEA-OECD rod ejection transient benchmark, which proves that the developed coupling system CORCA-K/CORTH has good accuracy in nuclear reactor core transient calculation.

Nested Array-Based Spatially Coupled LDPC Codes

Linear nested codes, where two or more sub-codes are nested in a global code, have been proposed as candidates for reliable multi-terminal communication. In this article, we consider nested array-based spatially coupled low-density parity-check (SC-LDPC) codes and propose a line-counting based optimization scheme for minimizing the number of dominant absorbing sets in order to improve its performance in the high signal-to-noise ratio regime. Since the parity-check matrices of different nested sub-codes partially overlap, the optimization of one nested sub-code imposes constraints on the optimization of the other sub-codes. To tackle these constraints, a multi-step optimization process is applied first to one of the nested codes, then sequential optimization of the remaining nested codes is carried out based on the constraints imposed by the previously optimized sub-codes. Results show that the order of optimization has a significant impact on the number of dominant absorbing sets in the Tanner graph of the code, resulting in a trade-off between the performance of a nested code structure and its optimization sequence: the code which is optimized without constraints has fewer harmful structures than the code which is optimized with constraints. We also show that for certain code parameters, dominant absorbing sets in the Tanner graphs of all nested codes are completely removed using our proposed optimization strategy.

Construction of Time Invariant Spatially Coupled LDPC Codes Free of Small Trapping Sets

In this paper, we propose a design technique for the construction of variable-regular time-invariant spatially-coupled low-density parity-check (SC-LDPC) codes with small constraint length and low error floor. The proposed technique reduces the error floor by imposing simple constraints on the short cycles in the code's Tanner graph, which in turn, result in the elimination of the most dominant trapping sets of the code. In some cases, we also derive lower bounds on the syndrome former memory for satisfying such constraints. The designed codes are superior to the state-of-the-art in terms of error floor performance and/or decoding complexity and latency.

Threshold Computation for Spatially Coupled Turbo-Like Codes on the AWGN Channel.

In this paper, we perform a belief propagation (BP) decoding threshold analysis of spatially coupled (SC) turbo-like codes (TCs) (SC-TCs) on the additive white Gaussian noise (AWGN) channel. We review Monte-Carlo density evolution (MC-DE) and efficient prediction methods, which determine the BP thresholds of SC-TCs over the AWGN channel. We demonstrate that instead of performing time-consuming MC-DE computations, the BP threshold of SC-TCs over the AWGN channel can be predicted very efficiently from their binary erasure channel (BEC) thresholds. From threshold results, we conjecture that the similarity of MC-DE and predicted thresholds is related to the threshold saturation capability as well as capacity-approaching maximum a posteriori (MAP) performance of an SC-TC ensemble.

Impacts of urbanization on carbon emissions: An empirical analysis from OECD countries

The impacts of urbanization on carbon emissions have attracted widespread attention for a long time. Quantitative research on the impacts is of great significance for formulating carbon reduction policy. Based on the dynamic panel autoregressive distribution lag (ARDL) model, we systematically study the general and heterogeneous long-run equilibrium relationships, short-run dynamic relationships, impact mechanism and lag effect between urbanization and three carbon emission dimensions in OECD high-income countries during long period. The main empirical results indicate that developed countries tend to have the same negative impacts of urbanization on carbon emissions, although there are differences in the endowments of different countries. The impact is relatively weak, for each percentage point increase in urbanization rate, CO 2 emissions per capita decrease by 0.015%, total CO 2 emissions decrease by 0.012%, and CO 2 emission intensity decrease by 0.009%. All member countries have achieved the decoupling of urbanization and carbon emissions. Urbanization affects carbon emissions by affecting economic growth, energy efficiency, and final energy consumption structure. This paper further reveals the multi-level impacts of urbanization on carbon emissions and provides policy implications of achieving carbon reduction through urbanization's agglomeration effect for government decision makers. • Estimate the impact of urbanization on carbon emissions based on panel ARDL model. • Analyze general & heterogeneous long-, short-run relationship and impact mechanism. • Urbanization decreases carbon emissions but the impact is weak in OECD countries. • Developed economies have achieved the decoupling of urbanization and CO 2 emissions. • Promote urbanization process and exert its scale effect to reduce carbon emissions.

Development and verification of the coupled thermal–hydraulic code – TRACE/SCF based on the ICoCo interface and the SALOME platform

The system thermal–hydraulic code TRAC/RELAP Advanced Computational Engine (TRACE) and the sub-channel code SubChanFlow (SCF) have been coupled together based on the Interface for Code Coupling (ICoCo) and the SALOME platform. It is a server-client system where TRACE and SCF are computational engines, ICoCo transfers the coupling data, and SALOME supervises the two clients’ synchronization. TRACE and SCF run serially. The coupled code adopts the domain-overlapping (assisted by a Dynamic Implicit Additional Source (DIAS) method) and the Operator Split (OS) explicit coupling approaches. The MEDCoupling library manages the field mapping between different meshes of TRACE and SCF. The YACS module in SALOME provides developers with useful tools that can implement numerical codes in SALOME. It provides users with Graphic User Interfaces (GUI) that can construct and execute the coupling simulations as well. Users can conveniently build/optimize/execute the coupling schemes in SALOME. The coupled code has been verified with an AP1000 feedwater-temperature-drop transient.

A Multifidelity Aero-Thermal Design Approach for Secondary Air Systems

Abstract The paper presents a multidisciplinary approach for aero-thermal and heat transfer analysis for internal flows. The versatility and potential benefit offered by the approach are described through the application to a realistic low pressure turbine assembly. The computational method is based on a run time code-coupling architecture that allows mixed models and simulations to be integrated together for the prediction of the subsystem aero-thermal performance. In this specific application, the model is consisting of two rotor blades, the embedded vanes, the interstage cavity, and the solid parts. The geometry represents a real engine situation. The key element of the approach is the use of a fully modular coupling strategy that aims to combine (1) flexibility for design needs, (2) variable level of modeling for better accuracy, and (3) in memory code coupling for preserving computational efficiency in large system and subsystem simulations. For this particular example, Reynolds averaged Navier–Stokes (RANS) equations are solved for the fluid regions and thermal coupling is enforced with the metal (conjugate heat transfer, CHT). Fluid–fluid interfaces use mixing planes between the rotating parts while overlapping regions are exploited to link the cavity flow to the main annulus flow as well as in the cavity itself for mapping of the metal parts and leakages. Metal temperatures predicted by the simulation are compared to those retrieved from a thermal model of the engine, and the results are discussed with reference to the underlying flow physics.

Spatially Coupled LDPC Codes With Sub-Block Locality

A new type of spatially coupled low-density parity-check (SC-LDPC) codes motivated by practical storage applications is presented. SC-LDPCL codes (suffix `L' stands for locality) can be decoded locally at the level of sub-blocks that are much smaller than the full code block, thus offering flexible access to the coded information alongside the strong reliability of the global full-block decoding. Toward that, we propose constructions of SC-LDPCL codes that allow controlling the trade-off between local and global correction performance. In addition to local and global decoding, the paper develops a density-evolution analysis for a decoding mode we call semi-global decoding, in which the decoder has access to the requested sub-block plus a prescribed number of sub-blocks around it. SC-LDPCL codes are also studied under a channel model with variability across sub-blocks, for which decoding-performance lower bounds are derived.

Hydro-elastic response of composite hydrofoil with FSI

The present study investigates experimentally and numerically the impact of composite materials on hydro-elastic performances of a hydrofoil experiencing Fluid–Structure Interactions, and focus on the bend–twist coupling phenomenon. Four flexible hydrofoils piercing the free surface, with identical geometry of extruded plan-form, a constant NACA0015 section, are tested in a cantilevered configuration in a hydrodynamic flume. The hydrofoils are built from the same mold with different materials (carbon or glass fiber) and different layups. The layups are designed to allow or not bend–twist coupling by the use of ± 45°plies in the structure. Two different coupled FSI numerical approaches are developed to model the hydrofoils behavior: a low fidelity code based on the coupling of a Vortex Lattice Method and a beam theory and a high fidelity code made of the coupling of the structural model code–ASTER and an OpenFOAM VoF hydrodynamic model with free surface. Mechanical characterization of the hydrofoils highlights the differences on the structures which are exacerbated in the hydrodynamic tests. The bend–twist coupling induces a modification of the angle of attack at the tip, leading to a significant difference of the generated lift and thus the deformation. The bend–twist coupling and the hydrodynamic performances are simulated by the numerical approaches.

Generalized Partially Information Coupled Polar Codes With Arbitrary Coupling Depth and Their Decoding Algorithms

We propose generalized partially information coupled (PIC) polar codes and their construction method. In the proposed codes, each code block (CB) shares systematic information bits partially with $J$ adjacent CBs on each side, where $J$ is referred to as the coupling depth. The conventional PIC polar code is a special case of the generalized PIC polar codes for $J=1$ . We modify the polar CB decoding and propose various inter-CB decoding schemes which apply to the code of arbitrary coupling depth $J$ . We also propose a low complexity evaluation method for the error rate of the generalized PIC polar codes, without channel generation and decoding operation. Numerical results show that this approximate evaluation is very accurate. It is verified by simulation that more coding gain can be attained for $J\ge 2$ . Finally, we compare the decoding complexities of the conventional inter-CB decoding algorithms and the proposed algorithms with which a lower decoding complexity is achieved without performance degradation.