scholarly journals Numerical study of influential factors on partial discharges in HVDC XLPE cables

2018 ◽  
Vol 37 (3) ◽  
pp. 1110-1117 ◽  
Author(s):  
Miao He ◽  
Miao Hao ◽  
George Chen ◽  
Wenpeng Li ◽  
Chong Zhang ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Repetition Rate ◽  
Power Transmission ◽  
Numerical Study ◽  
Influence Factors ◽  
Influential Factors ◽  
External Factors ◽  
Element Analysis ◽  
Power Sources ◽  
Content Type

Purpose For the dramatically developed high voltage direct current (HVDC) power transmission, HVDC cables play a vital role in the power transmission across seas and connections with renewable power sources. However, the condition monitoring of HVDC cables is still a challenging research topic. This paper aims to understand the influence of external factors, namely, current, cavity location and material properties, on partial discharge (PD) characteristics in HVDC cable in a numerical way referring to the refined Niemeyer’s model. Design/methodology/approach The influences of the three external factors are studied by a proposed numerical model for DC PDs based on the modification of a conventional PD model for AC voltage via a finite element analysis method. Findings The external factors can influence the discharge magnitude and discharge repetition rate via affecting the electrical conductivity of the material: DC PD is more frequent and with higher discharge magnitude when the cavity is closer to the conductor or the current through the conductor is higher. Both DC PD repetition rate and average discharge magnitude in long-term aged material are lower than virgin material. The effect of discharge on insulation degradation becomes decreasingly significant. Research limitations/implications The current work is based on the numerical modelling of DC PDs. Further experimental validations and comparisons are essential for improving the model. Practical implications The studies of the influence factors for PDs under HVDC voltage can benefit the research and practical power transmission on DC PDs, contributing the design and test of DC PDs in HVDC cables, exploring the understandings of the DC PDs’ mechanism. Originality/value This paper, to the best of author’s knowledge, first studies the influence factors on DC PDs based on the numerical modelling work.

Analysis of BIM functionalities diffusion in the construction industry: the case of the MENA region

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Claudette El Hajj ◽  
Germán Martínez Montes ◽  
Dima Jawad
Keyword(s):  
Construction Industry ◽  
Mixed Model ◽  
Diffusion Theory ◽  
Explanatory Power ◽  
Influence Factors ◽  
External Factors ◽  
Adoption Process ◽  
Mena Region ◽  
Content Type ◽  
Aec Industry

PurposeThis paper researches the diffusion patterns of various BIM functionalities across the Middle East and North Africa (MENA) construction industry.Design/methodology/approachThe study grounds on the innovation diffusion theory proposition that both the internal and external factors drive the widespread adoption of innovative trends. The study empirically analyzes the diffusion patterns of BIM by employing and comparing three mathematical influence models: internal, external and mixed models.FindingsThe results of the questionnaires point out that the mixed model as having the highest explanatory power and shows that the internal influence factors outperform the external factors in affecting the diffusion of BIM functionalities in the MENA Architectural, Engineering, and Construction (AEC) industry.Research limitations/implicationsThis paper can be of significant value for academic researchers as well as BIM business developers who are interested in emerging markets via providing an enhanced understanding of the adoption process of different BIM functionalities as well as a theoretical basis for explaining the diffusion patterns of information technology innovations in the AEC industry.Originality/valueThis study is among the first applications of the influence models to examine the adoption of BIM functionalities in the AEC industry and the very first across the MENA region.

A unique mathematical optimization approach for examination of failure effects on electric power transmission grids by combined environmental and economic indicators

2017 ◽  
Vol 14 (3) ◽  
pp. 237-248
Author(s):  
Ali Azadeh ◽  
Maryam Sattarian ◽  
Azadeh Arjmand
Keyword(s):  
Power System ◽  
Electric Power ◽  
Power Flow ◽  
Power Transmission ◽  
Environmental Issues ◽  
Influential Factors ◽  
Optimization Approach ◽  
Content Type ◽  
Total Cost ◽  
The Cost

Purpose To achieve the optimum performance of electric transmission power system performance, the possibility of generators’ failure and the consequences are amongst the most important and real assumptions which should be taken into consideration. This paper aims to recognize the most influential factors on generators’ failures that can have a deep effect on the total cost and environmental issues. The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow. Design/methodology/approach The data used in this study are gathered from a real case in USA in first step, the influential generator points that their failure has a significant effect on the objective function, have been recognized. Then, different failure scenarios are defined, and the optimum values in each of these scenarios through the GAMS modeling software are found. Consequently, by using a two-level factorial design approach, the critical generators across the power grid are determined. Findings The results show that by using such information, it is possible to detect the significant nodes in the power system grid and have a better maintenance plan. In addition, by means of this analysis and changing the capacity of main generators, it is possible to significantly reduce the operation costs. By comparing the indexes in case of the generator’s location, it seems that some of them are critical because of their capacity and position in the network (as their failure causes infeasibility in the model). Also, some of these deficiencies caused considerable index changes and critical consequences. Practical implications The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow. Social implications This paper endeavors to recognize the most influential factors on generators’ failures that can have a deep effect on the total cost and environmental issues. Originality/value The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow.

Numerical study on sealing characteristic of rubber X-ring exposed to high-pressure hydrogen by considering swelling effect

2019 ◽  
Vol 71 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Chilou Zhou ◽  
Mohan He ◽  
Guohua Chen ◽  
Saihua Jiang
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Mechanical Damage ◽  
Element Analysis ◽  
Content Type ◽  
User Subroutine ◽  
Sealing Performance ◽  
Ring Seal ◽  
Insight Into ◽  
Pressure Hydrogen

Purpose This paper aims to investigate the sealing characteristic of the rubber X-ring combined seal used in high-pressure hydrogen service and clarify the effect of swelling due to dissolved hydrogen on the sealing behavior. Design/methodology/approach A finite element analysis method with a user subroutine is proposed to investigate the sealing characteristic of rubber X-ring seals in conjunction with the swelling effect. Findings The swelling has a noticeable impact on the sealing behavior. The higher peak contact stress suggests that the X-ring seal may be superior to the O-ring seal, while the calculated increase in Mises stress suggests the X-ring exhibits a higher propensity to mechanical damage under low pressure conditions. Originality/value This paper describes a method with a user subroutine developed within ABAQUS to simulate the sealing performance coupled hydrogen swelling. The suitability of X-ring seals is evaluated. This work provides insight into the swelling effect on sealing behavior of an X-ring, which is of great value for the design and application of rubber seals used in hydrogen service.

Numerical study on racking behavior of light steel frames with K-shaped bracing

2019 ◽  
Vol 16 (2) ◽  
pp. 238-247
Author(s):  
Mohammad Javad Kazemi ◽  
Shahabeddin Hatami ◽  
Abdolreza Zare ◽  
Ali Parvaneh
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Failure Modes ◽  
Numerical Study ◽  
Shear Walls ◽  
Element Analysis ◽  
Content Type ◽  
Lateral Strength ◽  
Cold Formed Steel ◽  
Lateral Behavior

Purpose This paper aims to study the lateral behavior of cold-formed steel walls with K-shaped bracing by finite element modeling. Design/methodology/approach The braces which have the same section as those for studs and tracks are connected to the frame by screw connections. By pushover analysis, lateral performance of two frame categories, with different dimensions and bracing arrangements, is examined, and the force-displacement diagram and the ultimate strength of walls are extracted. Probable failure modes during lateral loading including distortional buckling of studs, buckling in braces and failure of connections are simulated in the numerical model, and some strengthening suggestions would be offered to prevent brittle failures and, therefore, to increase the lateral strength of the walls. Findings The strengthened walls are examined, and their seismic behavior is compared with the original walls. Finally, a parametric study is carried out to evaluate the effect of factors such as thickness of frame members, frame height and yield tension of members on lateral behavior of the shear walls. Originality/value In the present research, lateral strength and failure modes of nine types of cold-formed steel shear walls with different arrangements of K-shaped bracing are examined by non-linear finite element analysis, and a parametric study is carried out to extract the effect of the wall frame characteristics on the lateral behavior. Shear walls are classified into two series.

Systematic design of a new gearbox for concrete mixers

2020 ◽  
Vol 18 (6) ◽  
pp. 2017-2042 ◽  
Author(s):  
Lorenzo Fiorineschi ◽  
Susanna Papini ◽  
Luca Pugi ◽  
Andrea Rindi ◽  
Federico Rotini
Keyword(s):  
Power Transmission ◽  
Mechanical Design ◽  
Direct Consequence ◽  
Design Approach ◽  
Systematic Design ◽  
Original Design ◽  
Element Analysis ◽  
Content Type ◽  
Planetary Gearbox ◽  
Embodiment Design

Purpose The purpose of this study is to identify an innovative solution for the power transmission gearbox of concrete mixers, according to the specifications provided by the company. Design/methodology/approach A tailored systematic design approach (inspired to the German systematic framework) has been adopted to comprehensively gather the company specifications and perform in-depth design space explorations. Subsequently, an iterative embodiment design approach has been followed to identify the size of the components for the preferred concept, by using acknowledged mechanical design procedures and finite element analysis tools. Findings An innovative cycloidal gearbox has been developed, by merging the kinematics underpinning the classical cycloidal drives and the Wolfrom planetary gearbox. The resulting concept provides high reduction rates with a very high overload capacity. Research limitations/implications The main limitation of the studies is the absence of in-depth evaluations usually performed in the detail design phase. However, this limitation is a direct consequence of the company specifications, which only asked to find a preferred concept and to perform preliminary evaluations. Accordingly, the subsequent design optimization are intended to be performed by the company’s staff. Originality/value The present paper shows an original design approach, opportunely tailored to the design of innovative gearboxes. It can be conveniently adapted and reused by designers involved in similar tasks. Moreover, the designed cycloidal gearbox paves the way for important innovations in the field of concrete mixers, allowing to design more robust and compact devices.

A minimisation algorithm with application to optimal design of reinforcements in textiles and garments

2007 ◽  
Vol 19 (3/4) ◽  
pp. 159-166
Author(s):  
Željko Šomodi ◽  
Anica Hursa ◽  
Dubravko Rogale
Keyword(s):  
Finite Element ◽  
Optimal Design ◽  
Objective Function ◽  
Influence Factors ◽  
Element Model ◽  
Geometrical Parameters ◽  
Elastic Model ◽  
Element Analysis ◽  
Elliptic Paraboloid ◽  
Content Type

PurposeThis paper aims to develop an efficient two‐variable minimisation algorithm and to apply it in engineering optimisation of buttonhole reinforcements.Design/methodology/approachAn iterative extreme search is based on quadratic approximation of objective function, locating approximate solution at the minimum of corresponding elliptic paraboloid. Stress analysis is performed using plane stress finite element model. Optimal selection of geometrical parameters of buttonhole‐type reinforcement is done in terms of balance between maximum stress and material consumption.FindingsAdopted minimisation algorithm is assessed in a selected test example and proven to perform well in comparison with methods available in literature. In the selected case two local minima have been found within the predefined optimisation domain, with slight difference in objective function values.Research limitations/implicationsResearch is limited to homogeneous isotropic elastic model and a single representative load case. Objective function is restricted to two influence factors and predefined optimisation domain.Practical implicationsThe method can be useful for engineers/practitioners in the branch of clothing technology as a tool for computational estimate of optimal design of structural reinforcements.Originality/valueThe main quality of the paper is in software fusion of finite element analysis and advanced optimisation algorithm. The proposed theoretical‐numerical model is discussed in terms of applicability in parameter setting on buttonholer in garment production.

scholarly journals Examining the accounts of oil spills crises in Nigeria through sensegiving and defensive behaviours

2020 ◽  
Vol 33 (8) ◽  
pp. 2053-2076 ◽  
Author(s):  
Osamuyimen Egbon ◽  
Chijoke Oscar Mgbame
Keyword(s):  
Policy Implication ◽  
Design Methodology ◽  
Oil Spills ◽  
Burden Of Proof ◽  
Multinational Companies ◽  
External Factors ◽  
Content Type ◽  
Political Dynamics ◽  
Defensive Behaviours ◽  
Practical Implications

PurposeThe paper examines how oil multinational companies (MNCs) in Nigeria framed accounts to dissociate themselves from causing oil spills.Design/methodology/approachThe authors utilised data from relevant corporate reports, external accounts and interviews, and used sensegiving with defensive behaviours theoretical framing to explore corporate narratives aimed at altering stakeholders' perceptions.FindingsThe corporations gave sense to their audience by invoking scapegoating blame avoidance narrative in attributing the cause of most oil spills in Nigeria to outsiders (sabotage), despite potentially misclassifying the sabotage-corrosion dichotomy. Corporate stance was reinforced through justifying narrative, which suggested that multi-stakeholders jointly determined the causes of oil spills, thus portraying corporate accounts as transparent, credible and objective.Research limitations/implicationsThe socio-political dynamics in an empirical setting affect corporate accounts and how those accounts appear persuasive, implying that such contextual factors merit consideration when evaluating corporate accounts. For example, despite contradictions in corporate accounts, corporate attribution of oil spills to external factors appeared persuasive due to the inherently complicated socio-political dynamics.Practical implicationsWith compensation to oil spills' victims only legally permitted for non-sabotage-induced spills alongside the burden of proof on the victims, the MNCs are incentivised to attribute most oil spills to sabotage. On policy implication, accountability would be best served when the MNCs are tasked both with the burden of proof and a responsibility to demonstrate their transparency in preventing oil spills, including those caused by sabotage.Originality/valueCrisis situations generate multiple and competing perspectives, but sensegiving and defensive behaviours lenses enrich our understanding of how crisis-ridden companies frame narratives to alter stakeholders' perceptions. Accounts-giving therefore partly satisfies accountability demands, and acts as sensegiving signals aimed at reframing/redefining existing perceptions.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

scholarly journals On Hydromechanical Interaction during Propagation of Localized Damage in Rocks

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 162
Author(s):  
A.A. Jameei ◽  
S. Pietruszczak
Keyword(s):  
Numerical Study ◽  
Fluid Pressure ◽  
Implicit Time ◽  
Integration Scheme ◽  
Internal Length ◽  
Element Analysis ◽  
Equivalent Permeability ◽  
Mechanical Coupling ◽  
Splitting Test ◽  
Localized Damage

This paper provides a mathematical description of hydromechanical coupling associated with propagation of localized damage. The framework incorporates an embedded discontinuity approach and addresses the assessment of both hydraulic and mechanical properties in the region intercepted by a fracture. Within this approach, an internal length scale parameter is explicitly employed in the definition of equivalent permeability as well as the tangential stiffness operators. The effect of the progressive evolution of damage on the hydro-mechanical coupling is examined and an evolution law is derived governing the variation of equivalent permeability with the continuing deformation. The framework is verified by a numerical study involving 3D simulation of an axial splitting test carried out on a saturated sample under displacement and fluid pressure-controlled conditions. The finite element analysis incorporates the Polynomial-Pressure-Projection (PPP) stabilization technique and a fully implicit time integration scheme.

scholarly journals A 3DEC Numerical Analysis of the Interaction Between an Uneven Rock Surface and Shotcrete Lining

2021 ◽  
Author(s):  
Ping Zhang ◽  
Ering Nordlund
Keyword(s):  
Numerical Study ◽  
Support Effect ◽  
Influential Factors ◽  
Numerical Analyses ◽  
Numerical Code ◽  
Rock Surface ◽  
Stress Concentrations ◽  
Circular Tunnel ◽  
Rock Tunnels ◽  
Shotcrete Lining

AbstractRock tunnels excavated using drilling and blasting technique in jointed rock masses often have a very uneven and rough excavation surface. Experience from previous studies shows that the unevenness of a rock surface has a large impact on the support effect of shotcrete lining. However, clear conclusions regarding the effect of 2D and 3D uneven surfaces were not obtained due to limited studies in the literature. The numerical analyses reported in this paper were made to investigate the influence of the surface unevenness of a circular tunnel opening on the support effect of shotcrete using a 3D numerical code (3DEC). The models were first calibrated with the help of observations and measured data obtained from physical model tests. The influential factors were investigated further in this numerical study after calibration had been achieved. The numerical analyses show that, in general, the unevenness of a tunnel surface produces negative support effects due to stress concentrations in recesses (compressive) and at apexes (tensile) after excavation. However, shotcrete sprayed on a doubly waved uneven surface has better support effect compared to shotcrete sprayed on a simply waved tunnel surface. The development of shear strength (specifically frictional strength) on the uneven interface between the shotcrete and the rock contributes to this effect, in the condition where bonding of the shotcrete does not work effectively. The interface is a crucial element when the interaction between the rock and shotcrete is to be simulated. When an entire tunnel surface is covered by shotcrete with high modulus, more failures will occur in the shotcrete especially when rock surface is uneven. Based on the numerical model cases examined, some recommendations on how to incorporate tunnel surface conditions (2D or 3D unevenness) in the design of a shotcrete lining are given.

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