Avoidance and Coalescence of Delamination Patterns

Delamination of coatings and thin films from substrates generates a fascinating variety of patterns, from circular blisters to wrinkles and labyrinth domains, in a way that is not completely understood. We report on large-scale numerical simulations of the universal problem of avoidance and coalescence of delamination wrinkles, focusing on a case study of graphene sheets on patterned substrates. By nucleating and growing wrinkles in a controlled way, we are able to characterize how their interactions, mediated by long-range stress fields, determine their formation and morphology. We also study how the interplay between geometry and stresses drives a universal transition from conformation to delamination when sheets are deposited on particle-decorated substrates. Our results are directly applicable to strain engineering of graphene and also uncover universal phenomena observed at all scales, as for example in geomembrane deposition

Fracture strength: Stress concentration, extreme value statistics and the fate of the Weibull distribution

The fracture strength distribution of materials is often described in terms of the Weibull law which can be derived by using extreme value statistics if elastic interactions are ignored. Here, we consider explicitly the interplay between elasticity and disorder and test the asymptotic validity of the Weibull distribution through numerical simulations of the two-dimensional random fuse model. Even when the local fracture strength follows the Weibull distribution, the global failure distribution is dictated by stress enhancement at the tip of the cracks and sometimes deviates from the Weibull law. Only in the case of a pre-existing power law distribution of crack widths do we find that the failure strength is Weibull distributed. Contrary to conventional assumptions, even in this case, the Weibull exponent can not be simply inferred from the exponent of the initial crack width distribution. Our results thus raise some concerns on the applicability of the Weibull distribution in most practical cases

Conformational mechanism for the stability of microtubule-kinetochore attachments

Regulating the stability of microtubule(MT)-kinetochore attachments is fundamental to avoiding mitotic errors and ensure proper chromosome segregation during cell division. While biochemical factors involved in this process have been identified, its mechanics still needs to be better understood. Here we introduce and simulate a mechanical model of MT-kinetochore interactions in which the stability of the attachment is ruled by the geometrical conformations of curling MT-protofilaments entangled in kinetochore fibrils. The model allows us to reproduce with good accuracy in vitro experimental measurements of the detachment times of yeast kinetochores from MTs under external pulling forces. Numerical simulations suggest that geometrical features of MT-protofilaments may play an important role in the switch between stable and unstable attachments

Knowledge Management Strategies to Support Operational Security Requirements of Transmission System Operators of Electricity: the case of MAVIR

The Operational Security Network Code will provide the basis on European Union level for the power system to function with a satisfactory level of security and quality of supply, as well as efficient utilization of infrastructure and resources. It requires each TSO to launch knowledge sharing and knowledge management initiatives with emphasis on Transmission System elements, the operation of the Transmission System, use of the on-the-job systems and processes, as well as inter-TSO operations and market arrangements   In order to analyse the organizational context for successful knowledge management strategies, we completed both quantitative and qualitative research at MAVIR Hungarian Independent Transmission Operator Company. We undertook a knowledge management survey among 580 employees, and performed 15 semi-structure interviews with senior management.   Based on our research findings, knowledge management strategies to support operational security requirements of TSOs should focus on: Knowledge-sharing technology development, that is able to integrate within one single platform all knowledge management needs, supported by an intelligent search engine.Knowledge content development, focused on informal/tacit knowledge, as well as knowledge gaps. Companywide involvement of senior experts and knowledge worker is essential within the content development projects.Transparent knowledge management processes and well-defined roles and responsibilities within the knowledge creation, sharing and application.Cultural change / change management project to support the whole organization in realizing its knowledge management strategy. Individual incentives should also be included to encourage active involvement within knowledge sharing. Keywords Knowledge management, knowledge sharing, strategy, TSO, operational security, network code, MAVI

Organizational Changes and Management Challenges Induced by New Operational Security Requirements and Trends for Integration of European TSOs

A rapid rate of change characterizes European electricity markets. New government regulations, new products and services, growing renewables, increased competition, technological developments, and an evolving workforce compel Transmission System Operators to undertake changes on a regular basis.  Current operational security requirements and trends for integration of some functions of European TSOs might imply significant organizational changes.   In our current paper, we address the key management challenges induced by organizational changes of European TSOs. We join the debate of scholars and industry professionals of change management with a clear need of revisiting some fundamental questions in relation of TSOs and their operational security.   Based on our research, we can conclude that European TSOs should engage in continuous organizational changes to achieve higher performance and coordination among themselves. A key question of decision-makers is how to identify champions who will become local change agents in their organizations. Change agents must be efficient in handling resistance to change.   In a rapidly changing environment, the knowledge that is most useful to TSOs helps them change and perform effectively. To achieve relevance and generate knowledge that is useful for TSOs there is a need for cooperation between academics and industry professionals to fully understand complex problems and contribute to solutions.   Keywords: Organizational changes, change management, knowledge management, TSO, operational security, European electricity marke

Many-body spin glasses in the microcanonical ensemble

We investigate the p-spin model with Gaussian-distributed random interactions in the microcanonical ensemble using the replica theory. For p=2, there are only second-order phase transitions and we recover the results of Sherrington and Kirkpatrick obtained in the canonical ensemble. For p > 2, the transition between the ferromagnetic and paramagnetic phases is of first order, and the microcanonical and canonical ensembles give different results. We also discuss the ensemble inequivalence of the random energy model, corresponding to the limit p => infinity. This is the first systematic treatment of spin glasses with long-range interactions in the microcanonical ensemble, which shows how the two ensembles give different results.Comment: 15 pages, 5 figure

Innovation and Knowledge Management in the Energy Sector

We experience significant changes in the energy sector globally. The main trends are related to the sustainability, the growing share of renewables, the demand for decentralized solutions, the use of smart devices and the importance of energy efficiency and energy security. Because of the changing market environment, large energy companies need new organizational solutions and business activities, which can be achieved through innovation according to market trends. However, the rigorous regulation and the rigid institutional context limit opportunities, moreover, the large size of the energy companies, the highly concentrated markets and the dominance of traditional technologies result organizational inertia and path dependency suppressing innovation and organizational change. Our article analyzes the external factors forcing changes, external and internal factors suppressing changes, and finally identifies those management tools that can facilitate the innovation processes and organizational changes. Keywords: energy sector, environmental changes, organizational changes, change management, innovation management, knowledge management

Innovations in Operational Risk Management and Business Continuity Planning Methodologies of Transmission System Operators: Implications of the Operational Security Network Code

The ongoing liberalisation of national electricity markets and legislations to further reform electricity markets raises important issues regarding the operations of the interconnected transmission systems. To ensure compliance with new regulations, operational risk management (ORM) and business continuity planning (BCP) methodologies need to be reviewed in European Transmission System Operators (TSOs).In our current paper, we address key trends in ORM and BCP within the energy sector. We analyse the implications of the operational security network code within the context of the relationship between innovation and organizational performance.By raising ORM and BCP to strategic level within European TSOs and focusing on innovation, which complies with the European regulatory environment, system operators could achieve a significantly higher level of operational security. They would also be more flexible to regulatory changes while improving organizational performance.To improve operational security, innovations need to make the transmission system more robust and more resilient. The improved robustness expresses the better ability to predict and prevent incidents, while the more resilient system returns from the incidents more efficiently. The optimal security performance can be based on the balance of both areas. Therefore, future research has to improve parallelly the robustness and resiliency. Innovations in this context include specific technological and organizational solutions, as well. Keywords: operational risk management, business continuity planning, innovation, performance, TSO, operational security, European electricity marke

Ensemble Inequivalence in the Ferromagnetic p-spin Model in Random Fields

We study the effect that randomness has on long-range interacting systems by using the ferromagnetic Ising model with $p$-body interactions in random fields. The case with p=2 yields a phase diagram similar to that of previously studied models and shows known features that inequivalence of the canonical and microcanonical ensembles brings with it, for example negative specific heat in a narrow region of the phase diagram. When p>2, however, the canonical phase diagram is completely different from the microcanonical one. The temperature does not necessarily determine the microcanonical phases uniquely, and thus the ferromagnetic and paramagnetic phases are not separated in such a region of a conventional phase diagram drawn with the temperature and field strength as the axes. Below a certain value of the external field strength, part of the ferromagnetic phase has negative specific heat. For large values of the external field strength the ergodicity is broken before the phase transition occurs for p>2. Moreover, for p>2, the Maxwell construction cannot be derived in a consistent manner and therefore, in contrast to previous cases with negative specific heat, the Maxwell construction does not bridge the gap between the ensembles

Ensemble Inequivalence and the Spin-Glass Transition

We report on the ensemble inequivalence in a many-body spin-glass model with integer spin. The spin-glass phase transition is of first order for certain values of the crystal field strength and is dependent whether it was derived in the microcanonical or the canonical ensemble. In the limit of infinitely many-body interactions, the model is the integer-spin equivalent of the random-energy model, and is solved exactly. We also derive the integer-spin equivalent of the de Almeida-Thouless line.Comment: 19 pages, 7 figure