scholarly journals Robust Implementation in Direct Mechanisms

2012 ◽  
pp. 153-194
Author(s):  
Dirk Bergemann ◽  
Stephen Morris
Keyword(s):  
Robust Implementation

scholarly journals A Unified Abaqus Implementation of the Phase Field Fracture Method Using Only a User Material Subroutine

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1913
Author(s):  
Yousef Navidtehrani ◽  
Covadonga Betegón ◽  
Emilio Martínez-Pañeda
Keyword(s):  
Phase Field ◽  
Crack Nucleation ◽  
Crack Density ◽  
Contact Problems ◽  
Element Mesh ◽  
Robust Implementation ◽  
Current Implementation ◽  
User Material Subroutine ◽  
Complex Crack ◽  
Monolithic Solution

We present a simple and robust implementation of the phase field fracture method in Abaqus. Unlike previous works, only a user material (UMAT) subroutine is used. This is achieved by exploiting the analogy between the phase field balance equation and heat transfer, which avoids the need for a user element mesh and enables taking advantage of Abaqus’ in-built features. A unified theoretical framework and its implementation are presented, suitable for any arbitrary choice of crack density function and fracture driving force. Specifically, the framework is exemplified with the so-called AT1, AT2 and phase field-cohesive zone models (PF-CZM). Both staggered and monolithic solution schemes are handled. We demonstrate the potential and robustness of this new implementation by addressing several paradigmatic 2D and 3D boundary value problems. The numerical examples show how the current implementation can be used to reproduce numerical and experimental results from the literature, and efficiently capture advanced features such as complex crack trajectories, crack nucleation from arbitrary sites and contact problems. The code developed is made freely available.

scholarly journals Estidama and the Pearl Rating System: A Comprehensive Review and Alignment with LCA

2021 ◽  
Vol 13 (9) ◽  
pp. 5041
Author(s):  
Ayyagari Ramani ◽  
Borja García de Soto
Keyword(s):  
Construction Projects ◽  
Rating System ◽  
Practical Relevance ◽  
Rating Systems ◽  
Sustainable Buildings ◽  
System A ◽  
Robust Implementation ◽  
New Construction ◽  
Main Components ◽  
Sustainability Standards

Multiple sustainability standards and rating systems have been developed to draw attention to constructing sustainable buildings. The Pearl Rating System (PRS) is a mandate for all new construction projects in Abu Dhabi. Hence, it is important to understand the main components, advantages, and limitations of the PRS. The feasibility and the practical relevance of the PRS are still being studied. This paper addresses this gap and critically evaluates the PRS against some of the well-established rating systems like LEED and BREEAM. The analysis suggests that the PRS considers the cultural aspect of sustainability, in addition to the environmental, societal, and economic aspects. It was also found that most rating systems, including the PRS, have a very superficial inclusion of life cycle assessment (LCA). The paper finally concludes with other observations and outlook for a more robust implementation of the PRS.

A Robust Implementation of a Reynolds Stress Model for Turbomachinery Applications in a Coupled Solver Environment

2020 ◽  
Author(s):  
David Roos Launchbury ◽  
Luca Mangani ◽  
Ernesto Casartelli ◽  
Francesco Del Citto
Keyword(s):  
Reynolds Stress ◽  
Turbulence Modeling ◽  
Computational Cost ◽  
Reynolds Stress Model ◽  
Tip Vortex ◽  
Stability And Convergence ◽  
Stress Model ◽  
Robust Implementation ◽  
Flow Phenomena ◽  
The Stability

Abstract In the industrial simulation of flow phenomena, turbulence modeling is of prime importance. Due to their low computational cost, Reynolds-averaged methods (RANS) are predominantly used for this purpose. However, eddy viscosity RANS models are often unable to adequately capture important flow physics, specifically when strongly anisotropic turbulence and vortex structures are present. In such cases the more costly 7-equation Reynolds stress models often lead to significantly better results. Unfortunately, these models are not widely used in the industry. The reason for this is not mainly the increased computational cost, but the stability and convergence issues such models usually exhibit. In this paper we present a robust implementation of a Reynolds stress model that is solved in a coupled manner, increasing stability and convergence speed significantly compared to segregated implementations. In addition, the decoupling of the velocity and Reynolds stress fields is addressed for the coupled equation formulation. A special wall function is presented that conserves the anisotropic properties of the model near the walls on coarser meshes. The presented Reynolds stress model is validated on a series of semi-academic test cases and then applied to two industrially relevant situations, namely the tip vortex of a NACA0012 profile and the Aachen Radiver radial compressor case.

scholarly journals The representation and tenure of female principals in public enterprises in emerging markets: A protracted dearth?

2021 ◽  
Vol 10 (1) ◽  
pp. 58-73
Author(s):  
Ralph Marenga
Keyword(s):  
Emerging Market ◽  
Gender Diversity ◽  
Public Enterprise ◽  
Public Enterprises ◽  
Contributing Factors ◽  
Reduced Representation ◽  
Female Principals ◽  
The Public ◽  
Robust Implementation ◽  
Implementation Gaps

The reduced representation and tenure of women as public enterprise (PE) principals in Namibia as an emerging market and developing country are concerning (Mboti, 2014; Menges, 2020). The contributing factors are an element literature fails to address explicitly in the Namibian case. This paper, therefore, aims to consolidate evidence on whether the underrepresentation and limited tenures of female principals in Namibian PEs signal a protracted dearth of women in such positions. Methodically, a desk review is used to analyse the literature. Key findings of this paper identify the absence of top-down hands-on leadership; legal and policy implementation gaps; failure to declare gender diversity as imperative in the public sector; failure to focus on helping women gain broad line experience early on, among others, as contributing factors that have disadvantaged female principals in Namibian PEs. The challenges women face in being appointed or completing their tenure as PE principals over the years signal a protracted dearth of women in positions of PE principals in Namibia. Understanding these dynamics is relevant for enhancing Namibia’s policy efforts to curb the further proliferation of patriarchy as nuanced in the glass ceiling. This paper recommends the robust implementation of existing anti-patriarchy legislation.

scholarly journals A tunable multicellular timer in bacterial consortia

2020 ◽  
Author(s):  
Carlos Toscano-Ochoa ◽  
Jordi Garcia-Ojalvo
Keyword(s):  
Collective Behavior ◽  
Bacterial Population ◽  
Single Cells ◽  
Bacterial Strains ◽  
Intracellular Space ◽  
Bacterial Consortia ◽  
Robust Implementation ◽  
Time Encoding ◽  
Stationary Conditions ◽  
Molecular Components

Processing time-dependent information requires cells to quantify the durations of past regulatory events and program the time span of future signals. Such timer mechanisms are difficult to implement at the level of single cells, however, due to saturation in molecular components and stochasticity in the limited intracellular space. Multicellular implementations, on the other hand, outsource some of the components of information-processing circuits to the extracellular space, and thereby might escape those constraints. Here we develop a theoretical framework, based on a trilinear coordinate representation, to study the collective behavior of a three-strain bacterial population under stationary conditions. This framework reveals that distributing different processes (in our case the production, detection and degradation of a time-encoding signal) across distinct bacterial strains enables the robust implementation of a multicellular timer. Our analysis also shows the circuit to be easily tunable by varying the relative frequencies of the bacterial strains composing the consortium.

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