The main objective of this study is to assess the social, financial and corporate governance (CG) implications of the proposed social enterprise (SE) legislation in Malta. In light of such implications, the study also assesses the applicability of the SE under such legislation. A mixed methodology was adopted. Fifteen interviews were held with experts. Such data was supplemented by 52 valid responses to a questionnaire sent both to co-operatives and voluntary organisations (VOs) in Malta. The study concludes that the proposed legislation has various positive social, financial and CG implications and that the SE, as being proposed, is applicable and filling a void within the Maltese environment. Although such legislation offers both a new legal form and a label, its reference to the Companies Act which ignores SEs’ unique social dimension is questionable. Alternatively, a holistic SE regulatory framework may be developed. Furthermore, statutory thresholds, such as for dividend distribution and trade income, are to be possibly rendered more flexible. This study aspires to raise awareness about the implications of a proposed regulatory framework in Malta, hence hopefully promoting the application of the concept.

Policies of the European Union cover a range of social, environmental and economic aspirations and the current environmental directives and laws have evolved from a suite of norms which have changed over time. These may be characterised loosely according to ‘Three Ps’: Practical, those taking an anthropocentric approach; Pure, those taking an ecocentric approach and Popular, those appealing to the general public. In this paper I use these three perspectives as a tool to analyse the complexity and identify contradictions in European aquatic environmental legislation. Some trade-offs between development and conservation are identified and used to characterise the potential qualities of more successful agency to achieve environmental goals in the governance of European aquatic environments.

Sustainability science encompasses a unique field that is defined through its purpose, the problem it addresses, and its solution-oriented agenda. However, this orientation creates significant methodological challenges. In this discussion paper, we conceptualize sustainability problems as wicked problems to tease out the key challenges that sustainability science is facing if scientists intend to deliver on its solution-oriented agenda. Building on the available literature, we discuss three aspects that demand increased attention for advancing sustainability science: 1) methods with higher diversity and complementarity are needed to increase the chance of deriving solutions to the unique aspects of wicked problems; for instance, mixed methods approaches are potentially better suited to allow for an approximation of solutions, since they cover wider arrays of knowledge; 2) methodologies capable of dealing with wicked problems demand strict procedural and ethical guidelines, in order to ensure their integration potential; for example, learning from solution implementation in different contexts requires increased comparability between research approaches while carefully addressing issues of legitimacy and credibility; and 3) approaches are needed that allow for longitudinal research, since wicked problems are continuous and solutions can only be diagnosed in retrospect; for example, complex dynamics of wicked problems play out across temporal patterns that are not necessarily aligned with the common timeframe of participatory sustainability research. Taken together, we call for plurality in methodologies, emphasizing procedural rigor and the necessity of continuous research to effectively addressing wicked problems as well as methodological challenges in sustainability science.

This study aims to investigate the effect of board diversities to the intellectual capital performance by also testing the board meetings effectiveness. Using the data from knowledge-intensive companies from 2012-2015, we found that board meetings effectiveness increase the positive effects of board diversities (i.e. gender, educational level, nationality and the extent of board independent) to the intellectual capital performance except nationality diversity. We however, cannot provide convincing evidence that nationality diversity affect the intellectual capital. The implications of our study indicate that corporate governance structure, particularly regarding the companies’ oversight function, have an important roles in enhancing the intellectual capital performance.

The existing economics literature neglects the important role of capacity in the production of renewable energy. To fill this gap, we construct a model in which renewable energy production is tied to renewable energy capacity, which then becomes a form of capital. This capacity capital can be increased through investment, which we interpret as arising from the allocation of energy, and which therefore comes at the cost of reduced general production. Requiring societal well-being to never decline—the notion of sustainability favored by economists—we describe how society could optimally elect to split energy in this fashion, the use of non-renewable energy resources, the use of renewable energy resources, and the implied time path of societal well-being. Our model delivers an empirically satisfactory explanation for simultaneous use of non-renewable and renewable energy. We also discuss the optimality of ceasing use of non-renewable energy before the non-renewable resource stock is fully exhausted.

The purpose of this article is to demonstrate that, as part of its mission, sustainability science can change the way planners engage with urban problems on three points: First, that effective standard planning is an illusion, and the crucial task for urban planners should be considering—on a place-based rationale—the long-term consequences of decisions, policies and, technology change. Second,how it is necessary to develop collaborative planning and co-production of knowledge. Third, to build effective actions on the basis of collaborative planning, it is crucial to take first into account how the population and the institutions respond to and resist change. Conversely, this paper shows that urban planning is also a breeding ground for consolidating the theoretical framework of sustainability science, considering that cities can be seen as paragons of both socio-ecological systems and complex adaptive systems—a position that is discussed throughout the article. Bringing sustainability science and urban planning in closer dialogue with each other, to exploit their potential synergies, has not been done sufficiently: It is an important gap in the academic literature that this article aims at filling.

The effects of ceramic powder, a waste material, on the properties of lime-cement plasters were investigated in this article. The influence of the addition of the pozzolana as a supplementary cementitious material on mechanical and thermal properties of the studied materials was assessed in relation to its basic physical properties and pore structure characterization. Investigated parameters were bulk density, matrix density, open porosity, pore-size distribution, compressive strength, tensile strength, thermal conductivity and specific heat capacity. The results revealed the densifying effect of the pozzolana on the plaster microstructure as the open porosity decreased and bulk density rose to binder replacement level. Although the mean diameter of pores for plasters with higher amount of pozzolana was slightly higher, the volume of pores was lower. The presence of ceramic powder also showed a positive effect on the mechanical properties of plasters. Both compressive and tensile strength rose with increasing replacement ratio. Varying porosities were reflected in the increasing trend of thermal conductivity with rising binder replacement level. On the contrary, specific heat capacity showed the lower values the higher the amount of pozzolana.

The present paper describes experimental measurements of wood stiffness and analytical homogenization to provide estimates of the Micro-fibril angle (MFA). It is known that the orientation of fiber-like aggregates of crystalline cellulose in S2 layer of the wood cell with respect to the alignment of lumens considerably influences the overall stiffness of wood. Recently an inverse approach exploiting the results of nanoindentation at the level of wood cell and analytical homogenization has been proposed as a suitable tool for the MFA determination. A simpler methodology based on the results of indentation at the structural level using the Pilodyn 6J testing device has also been advocated as an alternative appealing particularly to engineering practice. Comparison of the two approaches suggesting their advantages as well as drawbacks is the principal objective of this contribution. As an example, an application to spruce as the most common type of wood used in building structures is considered.

Producing a light structure with affordable cost without sacrificing strength has always been a challenging task for designers. Using a hybrid material approach provides an expanded methodology to combine materials having different costs and properties (for example, combining fibers with high cost and high stiffness such as carbon with low cost, less stiffness fibers such as glass). Hence, a comparative approach is useful for the evaluation of design solutions in terms of weight and cost. In this study, a methodology for a combined weight and cost optimization for sandwich plates with hybrid composite facesheets and foam core is presented. The weight and cost of the hybrid sandwich plates considered are the objective functions subject to required equality constraints based on the bending and torsional stiffnesses. The hybrid sandwich plates considered consisted of thin hybrid composite facesheets, symmetric with respect to the mid-plane of the sandwich plates. The facesheets considered consisted of carbon/epoxy and E-glass/epoxy fiber-reinforced polymer. The layup of the fibers of the facesheets were restricted to some discrete sets of plies having orientation angles of 0, ±45 and 90. A multi-objective optimization technique was applied to minimize simultaneously the weight and the cost of the hybrid sandwich plate. The normalized normal constraint method with Pareto filter was used to generate the Pareto frontier trade-off curve. The Pareto trade-off curve was constructed by optimizing a sequence of combining weight and cost objective functions, while every function was minimized using the Active Set Algorithm.

In this paper, the influence of steel fiber-reinforcement when designing precast-prestressed concrete (PPC) road bridges with a double U-shape cross-section is studied through heuristic optimization. A hybrid evolutionary algorithm (EA) combining a genetic algorithm (GA) with variable-depth neighborhood search (VDNS) is formulated to minimize the economic cost and CO2 emissions, while imposing constraints on all the relevant limit states. The case study proposed is a 30-m span-length with a deck width of 12 m. The problem involved 41 discrete design variables. The algorithm requires the initial calibration. Moreover, the heuristic is run nine times so as to obtain statistical information about the minimum, average and deviation of the results. The evolution of the objective function during the opti- mization procedure is highlighted. Findings show that heuristic optimization is a forthcoming option for the design of real-life prestressed structures. This paper provides useful knowledge that could offer a better understanding of the steel fiber-reinforcement in U-beam road bridges.

This research reports a vehicle occupant restraint system design by using evolutionary multi-objective optimization with response surface model. The vehicle occupant restraint systems are composed of restraint equipment, such as an airbag, a seat belt and a knee bolster. The optimization aims to improve the safety of the system by evaluating some indexes based on some safety regulations. Estimation mod- els of the safety indexes are introduced for accelerating the optimization. The estimation models, which are called the response surface models, are constructed by using Gaussian Process, which is a kind of machine learning method. The Gaussian Process constructs the estimation model from sampling results, which are calculated by using multi-body dynamics simulation. Some helpful information for designing the restraint systems, such as trade-off information of safety performance and contribution of design variables for the safety performance, is obtained by analysing the Pareto optimal solutions.

Composite structures with the shell-like geometry must provide the sufficient mechanical stiffness in order to eliminate the unwanted deformations caused by the action of airflow. Because the pressure field on the design surface caused by airflow is generally uniform, the ensuring of the necessary stiffness can be achieved by creating a nonuniform thickness along the shell surface. In the present study the CFD finite element analysis of the virtual wind-tunnel test for the studied composite shell is performed assuming its absolute stiffness. The problem is further parameterized by the introduction of the auxiliary sphere, which causes a smooth distribution function of the shell thickness. The optimum seeking is performed by means of the four parameter variation of this function, providing a minimum total energy of the shell deformation under the given restrictions on its weight.

In bridge design, many variables like material grades, cross-sectional dimensions, passive and prestressing steel need to be modeled to evaluate structural performance. Efficiency gains are intended while satisfying the serviceability and ultimate limit states imposed by the structural code. In this paper, a computer-support tool is presented to analyze continuous post-tensioned concrete (PSC) box-girder road bridges, to minimize the cost as well as to provide optimum design variables. The program encompasses six modules to perform the optimization process, the finite-element analysis, and the limit states verification. The methodology is defined and applied to a case study. A harmony search (HS) algorithm optimizes 33 variables that define a three-span PSC box-girder bridge located in a coastal region. However, the same procedure could be implemented to optimize any structure. This tool enables one to define the fixed parameters and the variables that are optimized by the heuristic algorithm. Moreover, the output provides useful rules to guide engineers in designing PSC box-girder road bridges.

Crack formations in concrete may cause major damages in concrete structures. These damages require extensive maintenance work and thus have high costs. This paper addresses issues such as what causes cracks in concrete structures and how does the appearance of cracks look like with respect to an applied load? Can the appearance, distance, and size of the crack tell us something about crack initiation and propagation, or is it just by pure coincidence that cracks occur in structures as they do?

This research work investigated the effect of external factors such as load variables, time, the dimensions of the beam and the relative humidity on crack formation. Internal factors that have been investigated are the various constituents of the concrete, and how various levels of these constituents have an impact on cracking. In addition, the influence of concrete quality, tensile reinforcement, shear reinforcement, and anchoring reinforcement was investigated.

The paper presents technical calculations, where both the bending moment and shear forces are included in the analysis to determine how crack formations will propagate in the beam as a function of the applied loads. The first part of the paper deals with the theoretical factors that influence cracking in concrete. The second part deals with the calculations of crack formation in concrete. The results show how the cracks propagate in the x and y directions as a function of the load being applied.

Research into structural reliability for tensile structures is needed. The semi-probabilistic format for verification of so-called form-passive structures is well-established in the Eurocodes. Partial factors are the main features of this semi-probabilistic or design value method. Whereas for conventional structures these partial factors are calibrated to previous experience [1], appropriate partial factors have to be proposed and evaluated for tensile structures. A cable net structure built in 1958 was used as a case study to gain insight into the effect of partial factors according to Eurocode 3 (steel structures). Prestress contributes to the stiffness in the non-linear structural behaviour of membrane structures and thus increasing the prestress with factor 1.35 according to the Eurocodes might be non-conservative. The article investigates the effect of the partial factor for prestress (1.0 or 1.35) on a membrane structure. A similar geometry as the steel cable net structure is designed and analysed for comparison with the cable net structure. For the primary steel structure the partial factor for prestress 1.35 has to be applied. An in-depth study of the effect of the partial factor for prestress on the stress distribution in the membrane in warp and weft direction is performed. The stress distribution clearly depends on the boundary conditions. A sound conclusion though requires a thorough in-depth study for different shapes and membrane types. In a first step towards a reliability approach, the structural reliability of a three segments cable net structure is currently being analysed, taking into account the uncertainties associated with the pre-tensioned system.

We propose a new framework for topology optimization based on the boundary element discretization and kernel-independent fast multipole method (KIFMM). The boundary value problem for the considered partial differential equation is reformulated as a surface integral equation and is solved on the domain boundary. Volume solution at selected points is found via surface integrals. At every iteration of the optimization process, the new boundary is extracted as a level set of a topological derivative. Both surface and volume solutions are accelerated using KIFMM. The obtained technique is highly universal, fully parallelized, it allows achieving asymptotically the best performance with the optimization iteration complexity proportional to a number of surface discretization elements. More-over, our approach is free of the artifacts that are inherent for finite element optimization techniques, such as “checkerboard” instability. The performance of the approach is showcased on few illustrative examples.

The present issue contains a selection of edited papers presented at the Conference on High Performance and Optimum Design of Structures and Methods held at the University of Siena and co-organised by the Wessex Institute, UK, the Free University of Brussels and the University of A Coruña in Spain.

The issue contains papers on advanced types of structures, based on new design concepts. Modern structural design requires the development of new methods that can lead to systems able to resist a range of external stimuli. Particular emphasis is being placed on intelligent structures and materials.

Modern materials used in engineering components of structures are required to withstand a wide range of external stimuli. These range from high temperatures to special materials for restoration of heritage structures. Textile structures are usually highly stressed but they must result in minimal creep or relaxation for instance. Current research is also focused on their durability, which allows them to operate properly during their required lifetime.

Structural engineers must find adequate answers to the challenges of contemporary civil architecture, very often being a combination of lightweight structures with large spans. This requires sophisticated calculation techniques, including non-linear and vibration behaviour.

These new challenges require analysis, not only in terms of ultimate strength, serviceability and limit states but also in terms of their reliability and integrity. The engineer is also faced with the need to design ecological friendly structures to reduce their environmental impacts and incorporate reasonable resources.

The development and application of modern computational methods and powerful computers for structural modelling, control and management has increased the probabilities of using graphic interfaces and the incorporation of optimisation in the design process.

Some of the contributions in this issue are devoted to theoretical advances and practical applications of optimum design methodologies to several engineering disciplines. They demonstrate the current maturity of this design technique that has evolved with time from academic research to become a tool, useful to practising engineers. In fact, papers included in this issue originate not only from universities and research institutions but also from engineering companies. The papers are related to optimization of concrete and steel bridges, special structures and mechanical engineering. The problems formulated are very diverse and include size, shape and topology optimization, composite materials and a variety of nonlinear analysis.

Re-use and recyclability of materials and structural components is becoming increasingly important, i.e. supporting the “cradle to cradle” approach. Re-use is also found nowadays in two levels, not only from the re-use of structural components and materials but also the transformation of complete buildings, such as offices into schools or residential accommodation.

The papers included in this issue reflect these advances and provide a state of the art view of some of the most recent advances in high performance structures and materials. They are published by WIT Press and available Open Access in the eLibrary of the Institute (witpress. com/elibrary) where they can be downloaded for free by the international community.

The Editors are grateful to the authors for their papers and to the reviewers for their help in ensuring the quality of the contents of this issue.

The Editors

Siena, 2016

Nowadays, in different industrial fields as transport or aerospace, a research effort is conducted to reduce the structural weight. One of the most promising solutions is the use of composite structures due to their high stiffness, their low mass density and their low damping factor. At the same time, there is an intensification of the operational dynamic environment and an increase of durability requirements. These different expectations seem to be contradictory. One solution to manage these points is to design and manufacture smart composite structures with a fully distributed set of integrated piezoelectric transducers. These structures are able to modify their mechanical properties with respect to their environment (e.g. active vibration control), to interact with other structures (e.g. mechatronic) or with human beings (e.g. Human–Machine Interaction).

To meet the technical specifications of smart composite structures, in particular for complex geometries, it is necessary to master the manufacturing process and consequently the material parameters of the manufactured composite. Indeed, during the design phase, these parameters have to be absolutely known. A design approach based on engineering system theory and uncertainty calculation is applied to our manufacturing process of smart composite structures. In this paper, two different material identification methods (the Resonalyser technique and the Time-of-Flight technique) were selected and are applied to several test plates and, finally, on a large smart spherical cap. The Resonalyser technique is a good method to extract overall material parameters. Its major drawback in terms of cost and difficulty of implementation is the use of contactless devices for the measurements. The Time-of-Flight technique is based on the duration measurements of pulse propagation with a simple and low cost experimental setup. Integrated piezoelectric transducers are used for this purpose in the present analysis. The results obtained are quite local (mean values along the propagation path) and need a strong physical interpretation. The different material parameters obtained are compared and discussed.

World leaders at the 2015 United Nations Sustainable Development Summit in New York have reconfirmed the relevance of sustainability as the guiding paradigm in countering the development and climate crisis of the Anthropocene. Recent decades however, have been characterized by confusion, contestations, and arbitrariness in defining the nature and pathways of sustainable development. Humanity must urgently find ways to unlock the potential of the sustainability paradigm and organize a sustainability transformation. An emerging sustainability science community has already established considerable consensus on essential features of transformative science and research. Sustainability scholars are providing growing evidence that an emancipatory and democratic construction of sustainable development and more equitable, deliberative, and democratized knowledge generation are pivotal in tackling sustainability challenges. These findings are further underpinned by experiences gained in the Eastern and Southern Africa Partnership Programme (1999–2015)—a rare case of a long-term, transnational, and transdisciplinary research endeavour already completed. The programme fulfilled the dual role which is compulsory in transformative research: It generated contextualized knowledge and innovation at the science–society interface while simultaneously securing meaningful participation and Southern agency in a co-evolutionary process. This paper offers insight into the programme’s adaptive structure and implementation processes, which fostered deliberation, capacity development, and joint programme navigation benchmarked against local needs and broader sustainability demands. The ESAPP experience confirms that, if taken as the overarching frame of reference for all actors involved, the sustainability paradigm unfolds its integrative and transformative power. It enables sustainability-oriented actors from all scientific and practical fields to seek consilience between differing development and innovation paradigms and synchronize their development agendas and research frameworks on behalf of societal co-production of knowledge and innovation. Accordingly, the sustainability paradigm has the power to guide development and innovation policy, and practice out of the current confusion and ineffectiveness.

Indigenous knowledge (IK) is now recognized as being critical to the development of effective, equitable and meaningful strategies to address socio-ecological crises. However efforts to integrate IK and Western science frequently encounter difficulties due to different systems of knowledge production and underlying worldviews. New approaches are needed so that sustainability can progress on the terms that matter the most for the people involved. In this paper we discuss a case study from Aotearoa New Zealand where an indigenous community is in the process of renegotiating and enacting new indigenous-led approaches to address coupled socio-ecological crises. We reflect on novel methodological approaches that highlight the ways in which projects/knowledge are co-produced by a multiplicity of human and non-human actors. To this end we draw on conceptualizations of environmental ethics offered by indigenous scholars and propose alternative bodies of thought, methods, and practices that can support the wider sustainability agenda.

Sustainability Science is an emerging, transdisciplinary academic field that aims to help build a sustainable global society by drawing on and integrating research from the humanities and the social, natural, medical and engineering sciences. Academic knowledge is combined with that from relevant actors from outside academia, such as policy-makers, businesses, social organizations and citizens. The field is focused on examining the interactions between human, environmental, and engineered systems to understand and contribute to solutions for complex challenges that threaten the future of humanity and the integrity of the life support systems of the planet, such as climate change, biodiversity loss, pollution, and land and water degradation. Since its inception in around the year 2000, and as expressed by a range of proponents in the field, sustainability science has become an established international platform for interdisciplinary research on complex social problems [1]. This has been done by exploring ways to promote ‘greater integration and cooperation in fulfilling the sustainability science mandate’ [2]. Sustainability science has thereby become an extremely diverse academic field, yet one with an explicit normative mission. After nearly two decades of sustainability research, it is important to reflect on a major question: what critical knowledge can we gain from sustainability science research on persistent socio-ecological problems and new sustainability challenges? As a step in that direction, we solicited submissions to a special issue on Sustainability Science in the open access journal Challenges in Sustainability (CiS). Whilst the question above will not be sufficiently answered in this special issue, what is provided are some examples of what sustainability science can offer and how parallels can be drawn with other study areas dealing with issues of sustainability.

As direction for the issue and as inspiration for authors, we asked them to reflect on the field’s mission, achievements and conflicts. To complement more systematic assessments such as literature reviews, we hope that this type of exercise can be a recurrent one, as a way to continually spur active reflection among scholars in the field.

Achieving high grain yields and crude protein (CP) standards in organic winter wheat (Triticum aestivum L.) is challenging because ensuring that adequate nitrogen (N) is available at key periods of wheat growth is difficult in organic systems. Split application regimes and in-season N management tests may improve organic production. In field trials conducted over four site-years in Maine and Vermont, USA, N application regimes were analyzed for their effects on organic winter wheat, N uptake, grain yield, and CP. Tiller density and tissue N tests were evaluated as in-season decision tools. Eight treatments arranged in a non-factorial design differed in terms of N application timing (pre-plant (PP), topdress at tillering (T1), and topdress at pre-stem extension (T2)) and N rate. Treatments were: (1) an untreated check, (2) pre-plant N at a low rate of 78 kg N ha^-1 (PP_L), (3) pre-plant N at a high rate of 117 or 157 kg N ha^-1 (PP_H), (4) T1₇₈, (5) PP_L + T1₃₉, (6) PP_L + T2₃₉, (7) PP_H + T2₃₉, and (8) PP_L + T1₃₉ +T2₃₉. Responses to N treatments were variable among site-years, however some common results were identified. The PP-only treatments increased grain yields more than they increased CP. The T1₇₈ and PP_H + T2₃₉ treatments were the most effective at increasing yield and CP, compared with the PP-only treatments. Tiller density and tissue N tests were good predictors of grain yield (r = 0.52, p < 0.001) and CP (r = 0.75, p < 0.001) respectively. Future work should test in-season decision tools using a wider range of tiller densities, and topdress N rates against tissue N measurements.