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We study a variant of the weighted consecutive ones property problem. Here, a 0/1-matrix is given with a cost associated to each of its entries and one has to find a minimum cost set of zero entries to be turned to ones in order to make the matrix have the consecutive ones property for rows. We investigate polyhedral and combinatorial properties of the problem and we exploit them in a branch-and-cut algorithm. In particular, we devise preprocessing rules and investigate variants of “local cuts”. We test the resulting algorithm on a number of instances, and we report on these computational experiments.

With the growth of the floating wind industry, new operation and maintenance (O&M) research has emerged evaluating tow-to-port strategies (Offshore Wind Innovation Hub, 2020), but limited work has been done on analysing other logistical strategies for offshore floating wind farms. In particular, what logistical solutions are the best for farms located far offshore that cannot be reached by crew transfer vessels (CTVs)? Previous studies have looked at the use of surface effect ships (SES) and CTVs during the operation and maintenance (O&M) of bottom-fixed wind farms, but only some of them included service operation vessels (SOVs). This study analyses two strategies that could be used for floating wind farms located far from shore using ORE Catapult's in-house O&M simulation tool. One strategy comprises of having a SOV performing most of the maintenance on the wind farm, and the other strategy uses an offshore maintenance base (OMB) instead, which would be located next to the offshore substation and would accommodate three CTVs. This paper provides an overview of the tool and the inputs used to run it, including failure rates of floating wind turbine subsea components and their replacement costs. In total six types of simulations were run with two strategies, two different weather limits for CTVs and two weather datasets ERA5 and ERA-20C. The results of this study show that the operational expenditure (OPEX) costs for the strategy with an OMB are 5 %–8 % (depending on the inputs) lower than with SOV, but if capital expenditure (CAPEX) costs are included in the analysis and the net present value (NPV) is taken into account then the fixed costs associated with building the offshore maintenance base have a significant impact on selecting a preferred strategy. It was found that for the case study presented in this paper the OMB would have to share the foundation with a substation in order to be cost competitive with the SOV strategy.

The study, carried out at the Local Healthcare Authority in Reggio Emilia, Italy, focused on required travel of its employees with reference to length of travel route, degree of coverage through local public transport, degree of overlapping travel (useful to assess the feasibility of car sharing initiatives) and plans for shift work. The goal was to identify main obstacles when attempting to improve the reliability and scalability of this type of analysis, so that it can be used for regular updates. It was found that, on the one hand, it is necessary to promptly identify changes in the staff structure due to turnover that particularly affects health practitioners, such as doctors and fixed-term employees, while, on the other it is mandatory to comply with the provisions of Italian Law according to which, mobility managers must draw up annual commuting plans with an analysis of the routes travelled. The results of this work are likely to have useful implications for the improvement of the logistics system and, in particular, for the resilience of healthcare organizations.

Floating offshore wind is rapidly gaining traction in deep water locations. As with all new technologies, to gain the confidence of developers and investors, the technical and economic feasibility of this technology must be proven and robust cost estimates are necessary. In this paper, the authors present a methodology to calculate the capital and operational indicators of a floating wind farm over its project lifetime. A set of computational models is used to reduce the uncertainties in the estimation of the technical and economical parameters. In particular, the effect of using detailed operation and maintenance models and strategies allows a better estimation of operational cost. The paper highlights the requirements and specific adjustments considered for floating offshore wind technology. The methodology is demonstrated for two case studies inspired by real floating wind installations in the United Kingdom, namely the Hywind and Kincardine projects. The related input data, gathered from publicly available sources, constitute a reference database for future studies in the floating offshore wind sector. Results are presented for the two case studies. These show that availability and energy production are in line with typical values for offshore wind projects, and highlight the substantial contribution of operational expenses to the cost of energy. Results are also compared against previous estimations for floating offshore wind projects, showing satisfactory agreement for the overall project costs but an underestimation of operation and maintenance costs in previous studies. This highlights the importance of using detailed operation and maintenance models to adequately capture operational expenses. &nbsp

Future offshore wind technology solutions will be floating to facilitate deep water locations. The EUH2020 funded project FLOTANT (Innovative, low cost, low weight and safe floating wind technology optimized for deep water wind sites) aims to address the arising technical and economic challenges linked to this progress. In particular, innovative solutions in terms of mooring lines, power cable and floating platform, specifically designed for floating offshore wind devices, will be developed and tested, and the benefits provided by these components assessed. In this paper a purpose-built Failure Modes and Effect Analysis (FMEA) technique is presented, and applied to the novel floating offshore wind components. The aim is to determine the technology qualification, identify the key failure modes and assess the criticality of these components and their relative contributions to the reliability, availability and maintainability of the device. This will allow for the identification of suitable mitigation measures in the development lifecycle, as well as an assessment of potential cost savings and impacts of the specific innovations. The methodology takes into account inputs from the components developers and other project partners, as well as information extracted from existing literature and databases. Findings in terms of components innovations, their main criticalities and related mitigation measures, and impacts on preventive and corrective maintenance, will be presented in order to inform current and future developments for floating offshore wind devices.

Quantum annealing is getting increasing attention in combinatorial optimization. The quantum processing unit by D-Wave is constructed to approximately solve Ising models on so-called Chimera graphs. Ising models are equivalent to quadratic unconstrained binary optimization (QUBO) problems and maximum cut problems on the associated graphs. We have tailored branch-and-cut as well as semidefinite programming algorithms for solving Ising models for Chimera graphs to provable optimality and use the strength of these approaches for comparing our solution values to those obtained on the current quantum annealing machine, D-Wave 2000Q. This allows for the assessment of the quality of solutions produced by the D-Wave hardware. In addition, we also evaluate the performance of a heuristic by Selby. It has been a matter of discussion in the literature how well the D-Wave hardware performs at its native task, and our experiments shed some more light on this issue. In particular, we examine how reliably the D-Wave computer can deliver true optimum solutions and present some surprising results.

The advent of the COVID-19 pandemic (C19) has put a strain on the tightness of the epidemiological forecasting algorithms. These predictive models are traditionally based on SIR (Susceptible, Infected, Removed) and its updates. However, they did not provide reliable answers, especially in the first delicate phase, in which governments must take rapid decisions that are deemed to affect deeply the development and the outcome of the outbreak. This inadequacy derives not only from the model itself; it is also and undoubtedly generated by the lack of correct and timely data. Moreover, on the onset of a new pandemic, the disease is not known or it is only partially known. The first problem is the attitude of predicting it a priori, assuming the trend starting from a known mathematical curve. This approach is flawed, because it is impossible to provide a truthful forecast at the beginning of the epidemics (or of a new wave of infections), when, however, it is necessary to act promptly. Though as expected, as the epidemic progresses and the situation becomes homogeneous, mathematical models of pure interpolation and also SIR give more and more correct results. But during an epidemic, producing precise diffusion forecasts, including information on the structure of the wave front and its speed, is of paramount importance to organize an effective containment response.

Offshore renewable technologies hold the potential to satisfy a considerable amount of the global energy demand in the coming years. In this chapter, the main sources of renewable energy related to the oceans (waves, tides, and offshore winds) will be characterized and discussed, with reference to the challenges related to their use. Thus, the main devices capable of exploiting these resources will be presented. Their working principal, together with operational and technological requirements, will be described, highlighting strengths and weaknesses of each technology and providing examples of the past and current experiences. The elements of project management, as well as environmental impact and public perception, will be included. Finally, conclusions on the current viability of ocean energy devices will be drawn, together with guidelines for their future exploitation.

Synthetic mooring lines are becoming a popular alternative to conventional chain mooring systems. For marine renewable energy devices, they have been considered as an enabling technology for this nascent sector, given their reduced costs and ease of deployment. However, the extreme operating environment has led to an increased interest in the &lsquo, insitu&rsquo, condition monitoring of these mooring lines. This paper considers the use of polymer fibre optic technology and the optical time domain reflectometry (OTDR) technique for the condition monitoring of synthetic mooring lines. To establish the operating envelope of the fibres, Polymethylmethacrylate (PMMA) polymer optical fibres are mechanically tested. Additionally, an OTDR is used to monitor fibres whilst under elongation using a tensile test machine, and the sensitivity of the system in monitoring strain is established. At the lowest strain rate, the average proportional limit and yield points of the fibres are found at 1.16% strain and 5.41% strain, respectively. Fatigue exposure of fibres up to 1.25% strain identifies no measurable effect on fibres&rsquo, proportional limit or yield point. The occurrence of significant creep is identified for fibres strained beyond 1.5%. The OTDR system is able to identify strains at and above 4%. The study identifies important criteria that should be considered in the integration of polymer optical fibres for mooring applications. Limitations are discussed and suggestions for progressing this technology are provided.

The paper reports on some preliminary results obtained by using polynomial time algorithms to solve max-cut on some special graphs within a heuristic scheme known as subgraph sampling. Computational results are reported on toroidal graphs of about 100 000 nodes with edge weights generated from both a Gaussian and a bivariate uniform distribution.

One of the key objectives for renewable energy technologies is to reduce the environmental impact of energy generation. Floating offshore wind technologies have been developed in recent years to exploit the wind energy resource available at deep waters where bottom-fixed technologies are not economical. However, few studies exist that analyse the environmental impact of such technologies. Particularly, offshore activities such as those required for Operation and Maintenance (O&M) are not represented in detail in previous studies. The present study addresses these gaps by performing a Life Cycle Assessment using an advanced O&M model to quantify the environmental impact of a floating offshore wind farm. Different O&M philosophies – assuming towing to shore for major operations vs. performing all operations on site – and their impact are evaluated and discussed for two case studies inspired by real pilot park deployments. The results show mean Global Warming Potential (GWP) values between 25.3 and 45.2 gCO2 eq/kWh depending on the assumed O&M strategy and vessels, with the contribution of O&M to GWP ranging from 26 to 49%. Assuming O&M strategies to be the same for fixed and floating offshore wind could result in a 20.0% underestimate of GWP, whereas the vessel choice resulted in up to 29.6% variation in the estimated GWP. An environmental impact perspective provides key insights on the choice of different designs, operation strategies and asset management, and thus should be used in the decision-making process.

Quantitative reliability, availability, and maintainability (RAM) assessments are of fundamental importance at the early design stages, as well as planning and operation of marine renewable energy systems. This paper presents an RAM framework adaptable to different offshore renewable technologies, conceived to provide support in the choice of the device components and subsequent planning of the O&M strategies. A case study, characterizing a pilot farm of oscillating water column (OWC) wave energy converters (WECs), is illustrated together with the method used to obtain reliable estimate of its key performance indicators (KPIs). Based on a fixed feed-in-tariff for the project, economic figures are estimated, showing a direct relationship with the availability of the farm and the cost of maintenance interventions. Consequently, the probability distributions of the most relevant output variables are presented, and the mutual correlations between them investigated using principal components analysis (PCA) with the aim of discovering the relationships influencing the performance of the offshore farm. In this way, the contributions of the individual factors on the profitability of the project are quantified, and generic guidelines to support the decision-making process are derived. It is shown how this type of analysis provides important insights not only to ocean energy farm operators after the deployment of the devices, but also to device developers at the early design stage of wave energy concepts.

In order to accelerate the access into the energy market for ocean renewables, the operation and maintenance (O&M) costs for these technologies must be reduced. In this paper a reliability-based simulation tool for the optimization of the management of an offshore renewable energy (ORE) farm is presented. The proposed tool takes into account the reliability data of the simulated devices and estimations on the energy produced to create a series of results in terms of availability and maintainability of the farm. The information produced supports operational and strategic decision making regarding the O&M for offshore farms. A case study simulating a conceptual tidal energy project, consisting of an array of two tidal turbines located off the north coast of Scotland, is presented to show some of the results achievable with this model. The proposed methodology, although adopted for a tidal farm here, is generally applicable to other kinds of ORE farms.

The Urban Intelligence (UI) paradigm proposes an ecosystem of technologies to improve urban environment, wellbeing, quality of life and smart city systems. It fosters the definition of a digital twin of the city, namely a cyber-physical counterpart of all the city systems and sub-systems. Here we propose a novel approach to UI that extends available frameworks combining advanced multidisciplinary modelling of the city, simulation and learning tools with numerical optimization techniques, each of them specialized for the digital representation of city systems and subsystems, including not only city infrastructures, but also city users and their interactions. UI provides sets of candidate policies in complex scenarios and supports policy makers and stakeholders in designing sustainable and personalized solutions. The main characteristics of the proposed UI architecture are (a) fully multidisciplinary integration of city layers, (b) connection and evolution with the city, (c) integration of participative strategies to include 'human-oriented' information, and (d) modularity of application.

The International Register of the Ideas and Innovations (IRI) is a “visionary” and at present an experimental project that wants to protect all over the world the intellectual work leveraging on the blockchain paradigm (BC). IRI protects all the intellectual work not only the traditional ones (patents, trademarks, copyright, industrial design, geographical indication) but also those not protected by traditional offices such as ideas, projects, models, services, artefacts. The starting point is how to generate trust between many and different subjects engaged in the innovation value chain in order to create, build and collaborate in the developing of innovation. For this reason BC is also used to certify the actions, activities and relationships between researchers, inventors, students, innovators, funders, industries, user communities during the creation, construction and marketing of innovation. Detaching from the main BC platforms that need the consensus of the transaction based on a mechanism of proofing (especially regarding the financial area like bitcoin or Ethereum) the core of the project is the Proof-of-Originality algorithm (PoOr) that detects and compares the originality of the proposal. The challenge is to verify how the publication on IRI of an idea, project, …, assumes a “de-facto” protection. If an innovator can protect the idea and if the actions and the relationships that allowed the realization of the innovation are certified, he can share it and this allows the co-construction, the development and at the same time this generates trust for the selling or the search for funding.

Mooring systems constitute a fundamental component of all floating systems. For port authorities and device developers, improvements in moorings and foundations allow for savings in capital costs and increased revenues. In this work, a cost effective and secure mooring system for the station keeping of commercial vessels is presented and developed. A modular arrangement constituted by a series of connecting lines and clump weights is proposed, in order to allow for its deployment by small or craft vessels, and reduce the capital, installation and maintenance costs with respect to those of traditional mooring systems. The mooring system is calibrated according to the environmental conditions of Falmouth Harbour, UK. A numerical model of the mooring system is implemented using the offshore dynamics analysis software OrcaFlex. Experimental demonstration is provided through testing of a scaled prototype. Both numerical and experimental investigations aim at a preliminary evaluation of the design proposed. The outcomes indicate the feasibility of the arrangement as a suitable alternative to conventional and more expensive mooring systems. Further areas of improvement are identified and outlined.

All’indomani dell’approvazione presso l’Assemblea legislativa della proposta di legge "Disciplina regionale sulla tutela e l’uso del territorio" n. 4223, un gruppo di urbanisti, tecnici, intellettuali, esprime preoccupazione per i contenuti di un atto legislativo che rischia di imprimere una svolta deregolativa capace di ledere l’autonomia comunale in materia di urbanistica e pianificazione del territorio.

Lowering Operation and Maintenance (O&M) expenses is pivotal in order to increase the penetration of offshore renewables in the generation of electricity. The combined use of Monte Carlo simulation and optimization algorithms has been explored to support the assets management and propose improved solutions in an efficient and automated way. However, due to the lack of operational experience and historical data, validation of these models, intended in the commonly known sense of comparison against observed data is often not possible. This generates concern about their ability to fully grasp and interpret the complex dynamics of an offshore renewable energy system. This paper presents a method to effectively calibrate, verify and benchmark computational tools for O&M strategies and asset management of an offshore wind farm, as an alternative to validation in absence of real data. A case study is used to test the quality of the results and compare them against those provided by similar tools built for the same purpose. The evaluation functions for an optimization of the O&M strategies are then benchmarked against these outputs in order to ensure that the solutions are consistent within the overall characterization and optimization framework. The requirements for acceptability of the models performance, as well as guidelines for analogous verifications using similar models, are derived. Hence, this work provides a basis to benchmark future models and increase confidence and credibility in computational tools for the O&M planning of offshore renewables.