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Numerical methods that are able to predict the failure of technical structures due to fracture are important in many engineering applications. One of these approaches, the so-called phase field method, represents cracks by means of an additional continuous field variable. This strategy avoids some of the main drawbacks of a sharp interface description of cracks. For example, it is not necessary to track or model crack faces explicitly, which allows a simple algorithmic treatment. The phase field model for brittle fracture presented in Kuhn and Müller (Eng Fract Mech 77(18):3625–3634, 2010 ) assumes quasi-static loading conditions. However dynamic effects have a great impact on the crack growth in many practical applications. Therefore this investigation presents an extension of the quasi-static phase field model for fracture from Kuhn and Müller (Eng Fract Mech 77(18):3625–3634, 2010 ) to the dynamic case. First of all Hamilton’s principle is applied to derive a coupled set of Euler-Lagrange equations that govern the mechanical behaviour of the body as well as the crack growth. Subsequently the model is implemented in a finite element scheme which allows to solve several test problems numerically. The numerical examples illustrate the capabilities of the developed approach to dynamic fracture in brittle materials.

Purpose – The purpose of this paper is to qualitatively validate the constructs of a theoretically derived research model while gaining insights to steer the direction of a greater study on methodologies, their elements, and their impact on project success. In doing so, to investigate whether different project environments, notably project governance, impacts the relationship between methodologies and project success. Design/methodology/approach – A deductive approach was applied to validate a theoretically derived research model. In total, 19 interviews across 11 industrial sectors and four countries were used to collect data. Pattern-matching techniques were utilized in the analysis to deductively validate the research model. Findings – There is a positive relationship between project methodology elements and the characteristics of project success; however, environmental factors, notably project governance, influence the use and effectiveness of a project methodology and its elements with a resulting impact on the characteristics of project success. Research limitations/implications – Project governance plays a major role in the moderating effect of a project methodology’s effectiveness. Contingency theory is applicable to a project’s methodology’s selection and its customization according to the project environment. Practical implications – Understand the impact of project methodologies and their elements on the characteristics of project success while being moderated by the project environment, for example, the risk of suboptimal project performance due to the effectiveness of methodology elements being negatively impacted by the project environment. Originality/value – The impact of a project methodology (collection of heterogeneous-related elements) on the characteristics of project success is identified while being moderated by the project environment, notably project governance.

PurposeThe purpose of this paper is to investigate and discuss stakeholder issues faced by renewable energy megaprojects and in particular solar and wind power projects and their relevance to socioeconomic evaluation of megaprojects.Design/methodology/approachThe paper uses secondary data collected from the recent literature published on stakeholder issues face by mega solar and wind power energy generation projects around the world. The issues are then analysed across specific challenges in five continents where these projects are being developed. The paper then focuses on the literature on energy justice to elaborate the type of issues being faced by renewable energy megaprojects contributing to the achievement of UN Sustainable Goal 7 and their impact on vulnerable communities where these projects are situated.FindingsRenewable energy megaprojects are rarely discussed in the project management literature on megaprojects despite their size and importance in delivering sustainable development goals. While these projects provide social benefits they also create issues of justice due to their impact of vulnerable populations living is locations where these projects are situated. The justice issues faced include procedural justice, distributive justice, recognition inequalities. The type of justice issues was found to vary intensity in the developed, emerging and developing economies. It was found that nonprofit organisations are embarking on strategies to alleviate energy justice issues in innovative ways. It was also found that, in some instances, smaller local projects developed with community participation could actually contribute more equitable to the UN sustainable development goals avoiding the justice issues posed by mega renewable energy projects.Research limitations/implicationsThe research uses secondary data due to which it is difficult to present a more comprehensive picture of stakeholder issues involving renewable energy megaprojects. The justice issues revealed through thesis paper with renewable energy megaprojects are also present in conventional megaprojects which have not been discussed in the project management literature. Post-COVID-19 these justice issues are likely to become mor prevalent due to the pandemic's impact on vulnerable population exacerbating the issues and increasing their severity on these populations. Therefore it is becoming even more critical to take these into account while developing renewable energy megaprojects.Practical implicationsProper identification and response to energy justice issues can help in alleviating stakeholder issues in renewable energy megaprojects.Social implicationsContributes to the equitable achievement of the United Nations Sustainable Development Goal 7.Originality/valueThis paper addresses a gap in the project management literature on the exploration of stakeholder issues on renewable energy megaprojects. It also brings out the importance of justice issues which can assist in expanding stakeholders issues faced by megaprojects as these issues have not received sufficient attention in the past in the project management literature.

PurposeAim of this systematic review was to analyze long-term results after meniscus refixation.MethodsA systematic literature search was carried out in various databases on studies on long-term results after meniscus refixation with a minimum follow-up of 7 years. Primary outcome criterion was the failure rate. Secondary outcome criteria were radiological signs of osteoarthritis (OA) and clinical scores.ResultsA total of 12 retrospective case series (level 4 evidence) were identified that reported about failure rates of more than 7 years follow-up. There was no statistical difference in the failure rates between open repair, arthroscopic inside-out with posterior incisions and arthroscopic all-inside repair with flexible non-resorbable implants. In long-term studies that examined meniscal repair in children and adolescents, failure rates were significantly higher than in studies that examined adults. Six studies have shown minor radiological degenerative changes that differ little from the opposite side. The reported clinical scores at follow-up were good to very good.ConclusionThis systematic review demonstrates that good long-term outcomes can be obtained in patients after isolated meniscal repair and in combination with ACL reconstruction. With regard to the chondroprotective effect of meniscus repair, the long-term failure rate is acceptable.Level of evidenceIV.

Many plant species are able to regenerate adventitious roots either directly from aerial organs such as leaves or stems, in particularly after detachment (cutting), or indirectly, from over-proliferating tissue termed callus. In agriculture, this capacity of de novo root formation from cuttings can be used to clonally propagate several important crop plants including cassava, potato, sugar cane, banana and various fruit or timber trees. Direct and indirect de novo root regeneration (DNRR) originates from pluripotent cells of the pericycle tissue, from other root-competent cells or from non-root-competent cells that first dedifferentiate. Independently of their origin, the cells convert into root founder cells, which go through proliferation and differentiation subsequently forming functional root meristems, root primordia and the complete root. Recent studies in the model plants Arabidopsis thaliana and rice have identified several key regulators building in response to the phytohormone auxin transcriptional networks that are involved in both callus formation and DNRR. In both cases, epigenetic regulation seems essential for the dynamic reprogramming of cell fate, which is correlated with local and global changes of the chromatin states that might ensure the correct spatiotemporal expression pattern of the key regulators. Future approaches might investigate in greater detail whether and how the transcriptional key regulators and the writers, erasers, and readers of epigenetic modifications interact to control DNRR.

Purpose – The purpose of this paper is to identify the impact of relational norms on project success in different project governance contexts. Design/methodology/approach – A worldwide web-based questionnaire yielded 200 responses. Results from regression analyses supported the hypothesis that relational norms impact project success. Hierarchical regression analyses showed the moderating effect of governance and control on the relationship between relational norms and project success. Findings – Relational norms in the buyer-supplier relationship are positively associated with project success. This relationship is moderated by the strictness of project governance, especially the level of flexibility left to the project manager. Lower levels of managerial flexibility are detrimental to project success in cases of weak relational norms and supportive of project success in cases of high relational norms. Research limitations/implications – Academic implications stem from the indication that control has a low influence on the relationship between relational norms and project success, but that the level of managerial flexibility ultimately influences the choice of relational norms needed for a project to be successful. Practical implications – Clear organizational structures and methodologies are supportive of project success in cases of good relational norms. Therefore, project management training should focus on the relationship building capabilities of project managers, to leverage investments in existing methods and organizational structures. Originality/value – The paper extends the insights of the importance of soft aspects in managing projects across organizational borders and different governance structures.

In the present contribution the concept of isogeometric analysis is extended towards the numerical solution of the problem of gradient elasticity in two dimensions. In gradient elasticity the strain energy becomes a function of the strain and its derivative. This assumption results in a governing differential equation which contains fourth order derivatives of the displacements. The numerical solution of this equation with a displacement-based finite element method requires the use of C 1 -continuous elements, which are mostly limited to two dimensions and simple geometries. This motivates the implementation of the concept of isogeometric analysis for gradient elasticity. This NURBS based interpolation scheme naturally includes C 1 and higher order continuity of the approximation of the displacements and the geometry. The numerical approach is implemented for two-dimensional problems of linear gradient elasticity and its convergence behavior is studied.

Calving mechanisms are still poorly understood and stress states in the vicinity of ice-shelf fronts are insufficiently known for the development of physically motivated calving laws that match observations. A calving model requires the knowledge of maximum tensile stresses. These stresses depend on different simulation approaches and material models. Therefore, this study compares results of a two-dimensional (2-D) continuum approach using finite elements with results of a one-dimensional (1-D) beam model elaborated in Reeh (1968). A purely viscous model, as well as a viscoelastic Maxwell model, is applied for the 2-D case. The maximum tensile stress usually appears at the top surface of an ice shelf. Its location and magnitude are predominantly influenced by the thickness of the ice shelf and the height of the freeboard, the traction-free part at the ice front. More precisely, doubling the thickness leads to twice the stress maximum, while doubling the freeboard, based on changes of the ice density, results in an increase of the stress maximum by 61%. Poisson's ratio controls the evolution of the maximum stress with time. The viscosity and Young's modulus define the characteristic time of the Maxwell model and thus the time to reach the maximum principal stress.

While corporate culture plays a significant role in the success of any corporation, governance and “governmentality” not only determine how business should be conducted, but also define the policies and procedures organizations follow to achieve business functions and goals. In their book, Organizational Enablers for Project Governance, Ralf Müller, Jingting Shao, and Sofia Pemsel examine the interaction of governance and governmentality in various types of companies and demonstrate how these factors drive business success and influence project work, efficiency, and profitability.