The paper discusses the primary and secondary convergence conditions for the second monetary zone in West Africa. The focal point is however the primary conditions as these provide the basis for the attainment of the secondary conditions. Panel data for the research are obtained from the West African Monetary Agency website: www.wami.imao.org. The variables are those given in the primary conditions and these are first tested for unit root and stationarity for each country. A panel cointegration test is then applied to obtain a long-run equation which is used as an objective function in the Simplex method of linear programming with the primary conditions as constraints. The panel unit root test results show that all the variables are integrated with the degree of integration varying from zero to one for different countries. The stationarity test confirms the result, as the variables are non-stationarity in level for some countries but stationarity for others. Since the unit root and stationarity test show conflicting results, the pooled mean group estimator is used to obtain long-run cointegration equation. This equation can be applied irrespective of whether the variables are integrated or not. Linear programming is then used to obtain the optimal condition for attainment of a single currency project for West Africa. The result shows that the objective function is minima at 0.0462 with inflation contributing more to the variation in the government external reserves. The paper recommend that Central Banks in those countries preparing for second monetary zone should avoid implementing inflation targeting as a way to solving their economic problem.

Purpose: The purpose of this paper is to examine Macedonian managers’ behavior and the strategy they most often have facing a conflict situation at work.

Design/methodology/approach: Research instrument in a form of questionnaire was used to obtain data about strategies for managing conflict. For assessing which of the five modes: competing, collaborating, compromising, avoiding and accommodating Macedonian managers’ use we used Thomas-Kilmann conflict mode instrument.

Findings: The results from the study give new insights in the managerial mind, providing information about managers’ approaches they have facing problems and conflict situations.

Research limitations/implications: There is a literature gap in the area of organizational behavior studies in Macedonia. The results from the survey can be used for comparing the profile of Macedonian managers with managers from other countries.

Practical implications: This study will increase the understanding of how managers’ behavior is connected with conflict management styles. Also, the results from the study can be used in creating new teams and predicting behavior based on the styles used in learning and conflict resolution.

Originality/value: This research contributes to the field of organizational behavior by offering support and new findings. This study adds to the body of literature in what is considered relatively new and unexplored area of study in Macedonia. Also, this study will provide information about the behavior Macedonian managers have and clearer picture of their managerial style.

In past ten years the world of retailing has changed dramatically due to changes to consumer consumption, product saturation and most of all to technology improvements. Retailers have to operate in environment that fluctuates among different challenges that global economy puts on their way of doing business. Also global economy and internationalization of business reduced dependence on home markets and mood swing of domestic consumers. Needless to say attractiveness of foreign-new markets and its possibilities of growth. But unfamiliar and unpredictable territory has its treats and risk. In our paper we are focused on analysis of the strategies that retailers have as option when their wont to internationalize their business. Analysis of theoretical aspects of retail internationalization, and also of motives that shift retailers operations and attention from domestic toward unfamiliar markets are also given. The question for new analysis or research is put is there the best entry strategy for retailers or is it a mix of skill, experience and luck?

Prerequisites of agent’s limited rationality are defined, when their choice is influenced by preferences, last events, emotional characteristics. An impact of behavioral characteristics on making decision in case of limited rationality of the agent is considered. For example, overconfidence managers encourage an increase in debt in capital structure of the company and overinvestment. The conflicts of interests for the Russian companies with ownership concentration are analyzed. Moreover ownership concentration – is a necessary measure of shareholders protection, not always have a negative effect on financial economic results. Behavioral features and agency problems vary at life cycles of the company. The algorithm of transition from one life stage to another in accordance with determined risks, agency problems and drivers is developed. The challenge to stimulate managers for increase of productivity and their decisions is determined. This article presents investigation a motivation and an encouragement of management; defined behavioral characteristics in the way of incentives; behavioral stereotypes in stimulation methods are presented.

Ready-mix concrete business as the part of the procurement chain in the construction industry is strongly influenced by the economic and social situation in Slovenia. The financial crisis has revealed all the weaknesses and forced the industry into huge transition that left behind a mass of companies at the edge of survival. The purpose of this study is to investigate and examine the most appropriate strategic change framework with some proposals for the selected organization. After the analysis of current situation a desk research was made to explore different strategic change models. In the next stage the study adopted a quantitative methodology using self-completing questionnaire to collect relevant data about customer values and requirements and a qualitative methodology conducting a focus group interview among company's management team to evaluate most important strategic change issues. New mission, vision, and core values were developed as the core strategic elements of new approach. On the basis of selected strategic model new strategy was transformed into a set of managerial projects. Conclusions of the study confirm that ready-mix concrete production is a commodity business that competes mostly on price and quality on geographically small markets. However, further analysis demonstrates additional opportunities when customers are segmented into more specific groups in view of their core businesses and specialities. In addition to regular ready-mix concrete production for general use, there is a possibility to provide individually developed concrete based solutions. All presented findings and conclusions that constitute a new strategic approach contribute to long term company stabilization, competitive advantage and overall performance.

While some countries have achieved considerable development, many others still lack access to the goods and services considered standard in the modern society. As $\mathrm{CO}_2$ emissions and development are often correlated, this paper employs the theoretical background of the Environmental Kuznets Curve (EKC) and the learning curves toolkit to analyze how carbon intensities have changed as countries move towards higher development (and cumulative wealth) levels. The EKC concept is then tested with the methodology of learning curves for the period between 1971 and 2010 , so as to capture a dynamic picture of emissions trends and development. Results of both analyses reveal that empirical data fails to provide direct evidence of an EKC for emissions and development. The data does show, however, an interesting pattern in the dispersion of emissions levels for countries within the same HDI categories. While data does not show that countries grow more polluting during intermediary development stages, it does provide evidence that countries become more heterogeneous in their emission intensities as they develop, later re-converging to lower emission intensities at higher HDI levels. Learning rates also indicate heterogeneity among developing countries and relative convergence among developed countries. Given the heterogeneity of development paths among countries, the experiences of those which are managing to develop at low carbon intensities can prove valuable examples for ongoing efforts in climate change mitigation, especially in the developing world.

Along with the government's policy to convert from kerosene to LPG gas, LPG consumer demand is increasing. It requires the LPG distributors to be able to meet the needs of its customers. PT. Limas Raga Inti is an authorized distributor company PT. Pertamina LPG product devoted to distribute 12 kg. The company's main commitment is to provide the best service to the consumer. One of the efforts to improve the quality of service is to provide optimization of the distribution process. Optimization can be done by determining the distribution of the matrix saving method to obtain the optimal route. The purpose of the optimization of route determination is to provide effectiveness and efficiency of the distribution process. Effectiveness and efficiency can be seen with the speed of delivery time and can overcome the problems that exist in the company. In the process of determining the route to saving matrix, is done in the consumer sorting method which has produced the nearest neighbor and nearest the insert. Then do the repair method using 2-opt and or-opt in order to provide the best route to the selected proposal. Furthermore, the delivery time will be calculated based on the productivity of the proposal and indicating the optimal route. The results of this study are are 4 routes proposed by sorting nearest neighbor method with a total delivery time of 10 hours 30 minutes for 100 customers spread in the distribution area D14. The resulting productivity by 85.11%.

This paper analyses the start of the debt crisis in Europe and in Spain, which increased inflation, unemployment and public debt. Although Spanish banking system was considered one of the best, the growing debt brought Spain into one of the worst affected countries in financial crisis. Because of this, Spain was faced to the fiscal consolidation as the imperative for further development. The strength of the crisis in Spain can be seen from main economic indicators. Budget deficit in Spain was almost 12% just two years after it went into surplus for the first time in 30 year period. Public debt has started to rise from 2007 and in 2013 it overcomes 90% of GDP. The rate of unemployment also started to rise from 2007 and in 2013 it is higher than 25%. This paper analyses also Phillips curve in Spain using the actual data after the start of fiscal consolidation.

The aim of this paper is to examine the return and volatility spillovers and stock market co-movements among Western, Central and Southeast European stock markets. To examine the volatility spillover effects we employ a multivariate GARCH-BEKK (1, 1) model on a daily data from 2005 to 2014. There is a high and stable conditional correlation between Central and Western European markets during most of the analyzed period and the conditional correlation rises sharply during the periods of financial turmoil, suggesting some evidence on contagion. Conditional correlation between Croatian and Romanian markets and their Western counterparts is modest but it increases during the periods of financial crisis. Conditional correlation coefficients indicate that Macedonian and Serbian stock markets are relatively isolated from the advanced European markets. The return spillovers are investigated with the forecast-error variance decomposition based on the generalized VAR model. Following Diebold and Yilmaz (2012), we develop “spillover indices” based on the variance decomposition results on the generalized VAR model. The results indicate that total spillover index rose sharply during the periods of major financial disruptions. DAX and FTSE100 are the major net transmitters of spillovers to Central and Southeast European markets. There are bi-directional spillovers between DAX and FTSE100, between PX and WIG-20 and between MBI10 and BELEX15.

Sustainable development is a knowledge intensive process, but plagued by persistent concerns over our apparent inability to connect what we know with more sustainable practices and outcomes. While considerable attention has been given to ways we may better understand and enhance the knowledge-based processes that support the governance of social-ecological systems, relatively few have examined the governance of knowledge itself. The institutions-rules and norms-that govern knowledge may shed light on the persistence of 'gaps' between knowledge and action. In this review I seek to answer the question: can interdisciplinary knowledge governance literature contribute to understanding and analysing the institutional knowledge-based dimensions of sustainable development? I present and analyse the concept of knowledge governance as it is emerging in a range of disciplines and practice areas, including private sector management literature and public regulation theory and practice. I then integrate the findings from this review into a model of sustainable development proposed by Nilsson et al. [1]. I show that knowledge governance (as a scale above knowledge management) can inform Nilsson et al.'s three "nested" dimensions of sustainability: human wellbeing (through access to knowledge and freedom to exercise informed choice); resourcebase management (though enhancing regulation and innovation and transitions from exclusive to inclusive knowledge systems); and global public goods (by balancing public and private interests and fostering global innovation systems). This review concludes by presenting a framework that places sustainable development in the context of broader socio-political struggles towards more open, inclusive knowledge systems.

Disaster losses continue to escalate globally and in many regions human losses (death, injury, permanent displacement) often exceed the economic toll. Current disaster policies are reactive with a short-term focus―respond and rebuild as quickly as possible and in the same way after the event. Such policies ignore the longer-term approach of building disaster-resilient communities, in which investments made now show financial and social returns later by reducing the impact of disasters. This article provides a vision for resilient nations in 2030 based on three recent policy reports. It highlights the necessary steps towards achieving sustainability using the lens of disaster resilience as the pathway towards strengthening communities' ability to prepare and plan for, absorb, respond to, and recover from present and future disasters.

An estimated 2.6 billion people rely on traditional biomass for home cooking and heating, so improving the efficiency of household cookstoves could provide significant environmental, social and economic benefits. Some researchers have estimated that potential greenhouse gas emission reductions could exceed 1 billion tons of carbon dioxide equivalent $\left(\mathrm{CO}_2 \mathrm{e}\right)$ per year. Carbon finance offers a policy mechanism for realizing some of this potential and could also bring improved monitoring to cookstove projects. However, there are formidable methodological challenges in estimating emission reductions. This paper evaluates the quantification approaches to three key variables in calculating emission impacts: biomass fuel consumption, fraction of non-renewable biomass, and emission factors for fuel consumption. It draws on a literature review as well as on interviews with technical experts and market actors, and identifies lessons learned and knowledge gaps. Key research needs identified include incorporating accounting for uncertainty; development of additional default factors for biomass consumption for baseline stoves; refinement of monitoring approaches for cookstove use; broadened scope of emission factors used for cookstoves; accounting for non- $\mathrm{CO}_2$ gases and black carbon; and refinement of estimates and approaches to considering emissions from bioenergy use across methodologies.

The dominant paradigm of sustainable development (SD) where the environment is just the third pillar of SD has proven inadequate to keep humanity within the safe operational space determined by biophysical planetary boundaries. This implies the need for a revised definition compatible with a nested model of sustainable development, where humanity forms part of the overall social-ecological system, and that would allow more effective sustainable development goals and indicators. In this paper an alternative definition is proposed based on the thermodynamics of open systems applied to ecosystems and human systems. Both sub-systems of the global social-ecological system show in common an increased capability of buffering against disturbances as a consequence of an internal increase of order. Sustainable development is considered an optimization exercise at different scales in time and space based on monitoring the change in the exergy content and exergy dissipation of these two sub-systems of the social-ecological system. In common language it is the increase of human prosperity and well-being without loss of the structure and functioning of the ecosystem. This definition is functional as it allows the straightforward selection of quantitative indicators, discerning sustainable development from unsustainable development, unsustainable stagnation and sustainable retreat. The paper shows that the new definition is compatible with state of the art thinking on ecosystem services, the existence of regime shifts and societal transitions, and resilience. One of the largest challenges in applying the definition is our insufficient understanding of the change in ecosystem structure and function as an endpoint indicator of human action, and its effect on human prosperity and well-being. This implies the continued need to use midpoint indicators of human impact and related thresholds defining the safe operating space of the present generation with respect to future generations. The proposed definition can be considered a valuable complement to the recently emerged nested system discourse of sustainable development, by offering a more quantitative tool to monitor and guide the transition of human society towards a harmonious relationship with the rest of the biosphere.

A lot can be learned from the numerous pitfalls of sustainable development implementation: they outline how collective representation, short term interests and balance of power can undermine sustainability. For instance, the usefulness of global institutions in dealing with sustainable development is questionable as most are skewed toward the interests and perceptions of developed countries. The notion of sustainable development itself induces a profound cleavage between academic authors and the actors of its implementation, some of whom confuse it with sustainable growth (which favors spatial equity), whilst the others with environment management (which favors intergenerational equity). This polarization is a real problem, since originally, "Our Common Future" report promotes an inclusive approach, able to cope with both equities simultaneously. Finally, if there are obligations toward future generations, there are also obligations toward the current generation. The key issue for effective sustainability policies should be making them acceptable to everyone by including the expectations of local societies and communities. As a matter of consequence, universal solutions do not exist. They would not meet the specificities of local circumstances. The traditional prescriptive sustainable development model should give way to flexible plural sustainabilities. Singular, top-down, global-to-local approaches to sustainable development should be substituted for multiple sustainabilities.

I am honored to contribute an editorial for the inaugural issue of Challenges in Sustainability (CiS). It has provided the opportunity for me to take a step back and reflect on both the developmental progress in the field of sustainability science since its formal launch, now over twelve years ago [1], [2], and where the field might head in coming years. While it may always feel that the field is changing too slowly to keep up with the challenges it addresses, the developments have been noteworthy, especially in academia. I will discuss three areas: education, research and institutional development.

The growing offering of sustainability (science) educational programs at all levels has been an important part of the field’s evolution. Individual areas of concentration can include business and management, leadership, engineering, or policy management, to name a few. Flagship programs are now found throughout the world, including Arizona State University, Leuphana University of Lüneburg, and the University of Tokyo. In addition, programs at smaller academic institutions such as Furman and Kean Universities in the U.S. have arisen to meet the increasing demand for sustainability education. In Sweden, where I am based, there are international master’s programs in sustainability at Uppsala, Stockholm, Malmö, and Lund Universities, as well as Blekinge Institute of Technology. These programs and their different foci, seek not only to increase student knowledge to understand the complexities of sustainability challenges, but also aim to strengthen key competency development [3] in areas such as facilitation and strategic leadership.

In addition to sustainability education, the nature of research projects and programs in the field has also changed. The changes have been driven by both top-down funding priorities to finance research that is more relevant to society, and bottom-up desire from scholars to carry out more integrated work. This has led to the slow evolution from a focus on descriptive analytical research, with emphases on understanding the effects of environmental change, to transitional (or transformational) research agendas that embrace working in closer collaboration with societal stake-holders. Such research may concentrate on, for example, envisioning and scenario exercises, or problem-solving strategies beyond change strict policy change [4], [5]. Transitional sustainability science research is being carried out by individuals in innovative Ph.D. projects focused on single case studies using particular theories and approaches, and by networks of researchers in longer-term programs, such as the Earth System Governance project (www.earthsystem governance.org), united by common sustainable development themes.

To operationalize the education and research agendas in sustainability science, new organizational constellations have developed. Changes have ranged from the creation of new faculty structures at a number of universities, to the establishment of interdisciplinary research schools and programs. The Lund University Centre of Excellence for Integration of Social and Natural Dimensions of Sustainability (www.lucid.lu.se) is just one example of a longer-term program that unites senior and junior staff and Ph.D. candidates from disciplinary backgroundsincluding Economics and Economic History, Philosophy, Physical Geography, Human Geography, Political Science, and Human Ecology. The frequent interactions via discussions, debates, and joint publications have the goal of, amongst others, fostering new professionals who are capable of and accept working with the theoretical and empirical multiplicities [6] often inherent in sustainability education and research.

Despite the advancements over the past decade, there is still much to be done. Continued creativity in restructuring academic disciplines, departments, and funding and tenure incentives are necessary to pro- mote the interaction needed to achieve the interdisciplinary goals of sustainability science. Sustainability issues must also be strengthened in other areas such as the arts and humanities utilizing alternative forms of knowledge dissemination. In the area of education, additional sustainability programs are still needed,but more importantly, there must also be increased efforts in mainstreaming sustainability into all educational programs at different levels. Finally, the field must also continue to place strong emphases on reaching outside of academia in addressing pressing societal challenges.

The launch of Challenges in Sustainability represents an important step in further strengthening the field. The journal’s broad aims that focus on systemic analyses of sustainability challenges, solutions and transition processes, and associated trade-offs within socio-ecological systems, will create an important publishing outlet for scholars involved in integrative research. Furthermore, because Challenges in Sustainability is open access, it will mean that the knowledge produced in it can reach a wider range of stake-holders, adding one more attribute in a sustainability science we want to create.

Measuring sustainable development based on analytical models of growth and development and modern methods of growth accounting is an economic approach—often called the capital approach – to establishing sustainable development indicators (SDIs). Ecological approaches may be combined with the capital approach, but there are also other approaches to establishing sustainable development indicators—for example the so-called integrated approach. A recent survey of the various approaches is provided in UNECE, OECD and Eurostat [1]. This review note is not intended to be another survey of the various approaches. Rather the objective of this paper is twofold: to present an update on an economic approach to measuring sustainable development—the capital approach—and how this approach may be combined with the ecological approach; to show how this approach is actually used as a basis for longer-term policies to enhance sustainable development in Norway—a country that relies heavily on non-renewable natural resources. We give a brief review of recent literature and set out a model of development based on produced, human, natural and social capital, and the level of technology. Natural capital is divided into two parts—natural capital produced and sold in markets (oil and gas)—and non-market natural capital such as clean air and biodiversity. Weak sustainable development is defined as non-declining welfare per capita if the total stock of a nation's capital is maintained. Strong sustainable development is if none of the capital stocks, notably non-market natural capital, is reduced below critical or irreversible levels. Within such a framework, and based on Norwegian experience and statistical work, monetary indexes of national wealth and its individual components including real capital, human capital and market natural capital are presented. Limits to this framework and to these calculations are then discussed, and we argue that such monetary indexes should be sustainable development indicators (SDIs) of non-market natural capital, and physical SDIs, health capital and social capital. Thus we agree with the Stiglitz-Sen-Fitoussi Commission [2] that monetary indexes of capital should be combined with physical SDIs of capital that have no market prices. We then illustrate the policy relevance of this framework, and how it is actually being used in long term policy making in Norway—a country that relies heavily on non-renewable resources like oil and gas. A key sustainability rule for Norwegian policies is to maintain the total future capital stocks per capita in real terms as the country draws down its stocks of non-renewable natural capital —applying a fiscal guideline akin to the Hartwick rule.

Sustainability science is a young discipline that started emerging in the late 20th century, although Hans Carl von Carlowitz had already introduced ideas about sustainable management of forests in the early 18 th century. In recent times, the Club of Rome report in 1972 and the Brundtland report in 1987 developed these concepts further, and subsequently the sustainability idea became prominent in political debates as well. In both reports it was recognized that growth would have certain limits and a different style of resource utilization was therefore necessary. However, despite numerous approaches dealing with sustainability, it is still an important issue.

Nowadays humanity increasingly interferes with natural systems on a planetary scale. This holds for many subsystems of the Earth including the climate, soil and water bodies, and marine systems. During the 20th century, rapid technological development and demographic pressure advanced to a degree that we caused radical and unintended changes in the Earth's integrity. This is observable in certain subsystems, for example in the atmosphere (global warming), in marine systems (overexploitation of fish stocks), or in soils (degradation). One crucial element of sustainability is the capacity of natural resources to sustain human demands. It is foreseeable that parts of the system are overburdened beyond their capacity. This holds likewise for waste disposal, as for the atmosphere (greenhouse gases) and the utilization of resources like ores and renewables like trees and fish. To sum up, one can state that the overexploitation of natural resources and economic growth causes environmental impacts which may lead several systems to the brink of collapse. In other words, humanity causes a multitude of problems and most of them are not grounded in one sector, region, either can they be described by one scientific discipline.

Thus, sustainability science is a discipline that can be placed as the one at the meeting point of different scientific disciplines. However, during the last four decades, science made remarkable progress in regard to an assessment on how climate and global change will affect livelihood conditions, and how humanity is accelerating the above mentioned changes. The question is how we can avoid certain human activities that destroy the functionality of certain subsystems of the Earth and how we can develop potential solutions. It is a major challenge to understand the dynamics of man-made environment systems as a basis for the development of sustainable transition pathways in the sense of planetary engineering and management. In other words, sustainability science addresses the man-made environment interface.

Although all these points have bleen well-known for decades, we need to ask why it is so difficult to achieve pathbreaking scientific results, which may help us to develop clear visions of real sustainable development. It is well-known that resource consumption is an accompanying factor of economic prosperity and global resource consumption is still steeply growing. In some countries we observe-mainly the advanced ones-that resource consumption stabilizes or even decreases, while their high material intensity is still managed by exporting it to developing countries. Thus, the challenge to decouple resource consumption from economic development remains, and it is not only a question of a green economy, technological progress, or how natural resources are being utilized. It is indeed also a societal challenge. Human lifestyle changes might be a further catalyst for making headway towards sustainability. Nevertheless, current progress into this direction is slow, moreover, in large parts in the developing countries, we can see a tendency just to copy westernized lifestyles. A real innovation for the world would be a strategic approach for a sustainable economy that results in social equity and fairness, risk resilient livelihood conditions, sustainable resource use, and the avoidance of ecological scarcities-all these under consideration of planetary boundaries.

Nevertheless, sustainability is still an elusive concept. It is hard to define what sustainability really implies in terms of environmental constraints or societal development, in particular on a regional scale. Consequently, at the beginning of the 21st century, scientific bodies called for a more systematic sustainability science, e.g. International Council for Science defined sustainability as a major goal in its research strategies. Despite these efforts, concepts still lack real meaning. Thus, the aim should be to underpin activities dealing with the general aspects of sustainability with stronger and sounder scientific concepts. Questions, like: what exactly is sustainability? How can we achieve sustainability targets? And, what does 'being sustainable' mean? need to be in the foreground. Thus, sustainability science is environmental systems science.

Although all these points have been intensely discussed in recent decades, a thrilling and demanding journey still lies ahead for sustainability science. In regard to methodological terms, we need to encompass the different magnitudes of scales in terms of time, space and functions. Thus, sustainability science still invokes a lot of questions, i.e. we have to tackle, in particular, the following three challenges: 1) The provision of a methodological arsenal that allows the description and analysis of questions of sustainability in a comparable and transferable manner, i.e. we permanently have to ask ourselves what we can learn from singular cases in terms of the overarching sustainability challenge; 2) Options for solutions at different levels, e.g. regional and global, need to be assessed systematically in order to develop pathways which allow us to achieve predefined environmental targets, like the 2℃ target agreed in the Copenhagen Accord 2009; 3) As a lot of strategies are included under the term 'sustainability', there is a need to develop a concept which allows assessment and measurement of success of implemented sustainability measures.

However, sustainability itself is a challenge, because it needs ethical decisions from humankind itself whether we want to live in a safe environment or not. But how we achieve these safe limits is an issue of sustainability science, i.e. in terms of how to achieve these limits and what potential trade-offs there might be. The new journal Challenges in Sustainability provides a perfect platform for these goals.

Nowadays, a variety of numerical methods and numerical formulations exits to solve complex or coupled field problems in three dimensions. Most of them are generally applicable to nearly arbitrary kind of field problems. On the other hand, some highly optimized methods are available, which are predestined for the solution of a specific kind of problem. Especially in the case of weakly coupled multiphysics problems, a mixture of several numerical methods is very advantages to benefit from different properties of numerical methods for diverse physical sub-problems. A very promising approach for a flexible coordination of the related solution process is the application of software agents. Then, the results of one sub-problem are converted into boundary values or volume source distributions for another sub-problem and software agents choose solution methods independently for each sub-problem. Furthermore, two main aspects have to be considered in applications of numerical methods. First, the solution of a boundary value problem should be computed efficiently and second, the solution is evaluated for visualization and interpretation of obtained results. In practice, it is difficult to choose a single appropriate method, which is well suited both for the solution of a problem and its evaluation, since the demands differ in both cases. Here, a concept is presented to apply various numerical methods successfully to the solution and evaluation of complex field problems. Attention is mainly turned on the integration of boundary element methods into the concept of mixed numerical formulations.

Climate change impacts particularly affect vulnerable populations such as children. Therefore, addressing the adaptation of educational buildings is crucial in avoiding these negative effects on school performance. In this paper, three educational buildings, located in Badajoz (Spain), Evora (Portugal) and Porto (Portugal), serve as pilot samples to study the suitability of nature-based solutions (NBS), chosen for each one of three climatic zones. The NBS selected include green roofs, vertical structures with vegetation to shade holes, outdoor trees and free-cooling ventilation. The scenarios of the different NBS implemented in the three models were simulated with the software EnergyPlus, which allows optimising the appropriate decision before renovation operations begin. The results obtained from the simulations suggest energy performance improvements after applying the most adequate NBS selection to each one of the three buildings tested. Particularly, a reduction in radiation on both roofs and facades is required in the case of Evora and Badajoz, where both climate zones have similar features, that is, warm and dry. While in Porto, milder and more humid than the former ones, it is very effective to operate mainly on the roof, complemented by small ventilation operations.

In drive systems and component technology a high reliability is very important for machines. Machine element dimensions are calculated for reliability. The properties for these elements are based on conventional manufacturing techniques. Very high stresses are applied on bearings in their operating time. To improve the endurance life, residual stresses can be induced into the subsurface zone. In contrast to a conventional grinding process, the mechanical surface modification process deep rolling is able to induce very high compressive residual stresses. A computational approach was developed to establish an appropriate residual stress depth profile matching the applied loads. Thus, the costs of manufacturing can be chosen in accordance to the required properties. The method to determine the residual stresses is based on an iterative reverse calculation of an existing bearing fatigue life model of Ioannides et al. The model originates from the approach of Lundberg and Palmgren (1947) including a stress fatigue limit tu. For the term ti, the fatigue criterion of Dang-Van is applied. The equation accounts for the maximum orthogonal shear stress and the local hydrostatic pressure phyd, corrected for residual and hoop stress. The inputs into the computational model are the stresses on the surface, which are simulated based on the load and geometry of the contact between roller and bearing surface. As an output the required residual stress profile underneath the bearings raceway is given to achieve a bearing fatigue life as required for the given application. In order to verify the model, the bearing fatigue life was experimentally determined for a given residual stress profile by experiments.

The paper discusses research that concerns itself with the design explorations of high performance structural and climatic systems. It also examines their efficient and low-cost application techniques in refugee facilities. Initially, the paper presents a survey of the current conditions of refugee schools in Lebanon. The survey highlights the need for alternative design strategies in the provision of environmentally friendly educational facilities with low-cost yet adequate learning conditions. Considering the current conditions, the premise is set that required design strategies call for an integrated strategic approach. This is to promote sustainable development models as post-disaster responses. The “Nasma” project is then taken as a case study that exemplifies a sustainable pilot project as a post-disaster response. It is an educational unit developed and implemented in Lebanon by the author in collaboration with a team from Transsolar climate engineers led by Christian Frenzel. It therefore represents a paradigm of integrated architectural and environmental design strategies taking into considering the complex socio-political context of refugee settlements in Lebanon’s Bekaa Valley. The project aims to provide visual, air, thermal and acoustic comfort. It also integrates innovative structural systems and construction methods that allow the school to be rapidly deployed and relocated. Strategies that aim towards social impact include using local materials and engaging the community in the building process. Finally the paper concludes by assessing the actual performance of the structure as a replicable post-disaster response.

Long span bridges and high rise buildings are two types of structures that have always arisen the atten­tion of engineers and architects. The former are appropriate for creating crossings over wide rivers or estuaries in a sort of recreation of the geography of our planet. The latter are many times used to be a symbol of the wealthy of the cities where they are erected.

Construction of both typologies has experienced a dramatic activity since the last decades of the past century in many countries located in different continents such as Europe, Asia or America, and such tendency has even increased in recent years, and several challenging proposals have also been proposed for the years to come.

This article starts with a brief description of the capabilities and advantages of long span bridges and tall buildings. Afterwards, a description of the main realizations of suspension and cable-stayed bridges already existing all around the world is presented mentioning their main characteristics and fea­tures. Additionally, information on bridge projects that could take place in a near future are mentioned. Then, a similar treatment is carried out for the vast collection of signature buildings erected in the last decades. It will be observed that in addition to the new tall structures in already very cosmopolitan cit­ies, many of them have been built in other places and have transformed radically the skyline of cities in China, Singapore, Korea or the Arabic Gulf countries, to name a few.

Environmental problems have been increasing at a disproportionate rate, contributing to global warming, one of humanity’s greatest challenges. As stated in the latest report of the Intergovernmental Panel on Climate Change ‘climate change is widespread, rapid and intensifying’ and there is certainty that this is a result of human activity. In this context, environmental social responsibility is fundamental to prevent, mitigate or repair the environmental damage generated by productive activity. This obliges us to take concrete actions and thus move from a linear economy approach to a circular economy approach that allows for sustainable development, where waste and pollution are eliminated from the design stage and materials are used for as long as possible. Chile must implement actions that allow it to meet the commitments obtained in its Nationally Determined Contribution of 2020, and move towards sustainable development. The Chilean case is interesting to study because it is a highly exposed and fragile country in the face of climate change. The purpose of this publication is to highlight the current problem of climate change and the threat it poses to our planet, to understand that the circular economy approach as a business model allows for a long-term solution to this problem, to understand the consequences of climate change in Chile and to know the current situation in terms of strategic planning at the country level in relation to the circular economy.

The article explores the problem of train rescheduling based on the actual situation. The proposed stochastic model uses specific distributions of operating times which are dependent on the current traffic conditions. The arrival time distribution is considered as a result of adjusting the train trajectory by speed control. The results of modelled arrival distributions correspond well with the experimental data received at the russian railways. The proposed model is used for prevention of sequence-of-trains conflicts and violations of connections. The basis of deviation prediction is two-train model of mesa-level which uses actual features of scattering of the operation times both at sites and at stations. The article also proposed a new measure of arrival delay which considers the share of satisfied passengers.

The paper deals with the optimization of a single-storey timber building structure designed from timber portal frames connected with steel purlins, rails and façade columns. While the portal frames are made of the glued laminated timber with rectangular cross-sections, purlins, rails and façade columns are made of commercially available steel I-profiles. The portal frames are supported by square concrete pad foundations. The building structure is optimized by a mixed-integer non-linear programming (MINLP). The optimization model is developed. The objective function defines the material costs of the structure. The objective function is subjected to structural analysis and design constraints defined according to Eurocode standards. The Modified Outer-Approximation/Equality-Relaxation algorithm (OA/ER) and the linked multi-level strategy are applied. The optimization determines the minimum material costs of the structure, the optimal number of glulam frames and steel members and all standard/discrete cross- sections. A numerical example at the end of the paper shows the efficiency of the proposed optimization approach.

As large consumers of energy, cities offer the opportunity for significant energy savings in relation to the implementation of energy-efficiency measures. In this context, the cities of Barcelona, Cologne and Stockholm, together with a diverse group of stakeholders from public and private sectors, joined to create the GrowSmarter project. GrowSmarter seeks to demonstrate and stimulate the uptake of Smart Solutions in energy, infrastructure and transport, to provide other cities with insights and create a ready market to support the transition to a sustainable Europe. With the objective of promoting and developing low-energy districts, a set of solutions were tested aiming to reduce their environmental impact. These are classified in three blocks: building energy retrofitting, energy consumption visualization platforms and local energy generation with smart management. All these actions have been technically and economically evaluated in GrowSmarter, and the results are presented in this article. The project has analysed different impacts of active and passive retrofitting measures in building energy performances and the feasibility of the proposed business models behind them. Energy visualization platforms have proven to be a promising tool to engage end users, but there is still work to do to define successful business models. The assessment of the deployment of local energy generation units shows that the corresponding regulation differs to a significant extent among countries. A clear and harmonized regulation according to the current state of technology is required in order to fully deploy distributed energy resources at commercial level. Finally, besides guaranteeing the correct implementation and operation of energy-efficiency measures, communication and information campaigns are key to build trust and ensure user acceptance. Working on building users’ awareness and acceptance has proven to be a must in order to succeed in making low-energy districts the preferred path in urban development.

Particle size reduction of dry granular material by mechanical means, also known as milling or comminution, is undoubtedly a very important unit operation in pharmaceutical, agricultural, food, mineral and paper industries. As comminution is a stochastic and a nonlinear process, an attempt was made to understand this complicated process by conducting parametric studies experimentally and computationally using discrete element method (DEM). Greater size reduction was observed at higher rotational speed of the hammer owing to the greater centrifugal force experienced by the particles. Increase in impeller wall tolerance resulted in rolling mode regime of powder bed, which was found to be significant at low impeller speeds. A numerical model based on DEM was used to simulate a hammer mill and study the breakage and kinematics of the particle motion within the hammer mill. In the simulations, increase in hammer tip speed causes higher frequency of impact of particles per unit time and higher specific energy of impact resulting in generation of much finer end product. A limit can be conceived during the breakage event. This is because as size reduction occurs, the breakage rates can fall for very fine particles as crack propagation ceases. This is because as size decreases the probability of finding a flaw also decreases. Simulations also showed a higher milling rate for big hammers as larger hammers decrease the tolerance between the milling chamber and rotating impeller. To study the effect of material properties, the energy of fragmentation was estimated and it was found to increase as the material became more cohesive.

This paper is focused on assessing the effects of floods on selected components of the environment. The components include the impact of floods on the population, water conditions, soil, fauna, flora and their habitats, the structure and use of the landscape, protected areas and their protection zones, for the territorial system of ecological stability, for the urban complex and land use, for cultural and historical monuments, cultural values of an intangible nature and for archaeological and paleontological sites and important geological localities. The basic principle of the methodology is the calculation of the risk index – an estimate of the level of risk that the proposed activity represents for the environment. The risk analysis is based on the principle that stressors are associated with the proposed activity, which poses a certain risk to the components of the environment. This can be quantified by calculating the individual risk for each identified environmental impact of the stressor. In summary, the total risk can be calculated, which represents what risk the proposed activity poses to the environment and human health. The calculated value of total risk represents very low level of risk in the addressed river basin. As a proposal for measures in the event of floods, a Draft Protocol providing health and social care in case of floods is created. The Draft Protocol may be used as a supplement to the Flood Management Plan from the point of view of providing health and social care.

All large railway networks use a mixture of outdated, modern and emerging signalling and train operation principles. There is a need to develop novel modelling and verification mechanisms to support mixed traffic scenarios, including, for example, mixing different types of signalling and driving. In our previous work we introduced the Unified Train Driving Policy (UTDP) formal modelling language for uniformly capturing diverse signalling principles and mixing, in a demonstratively safe manner, at the node and/or network-level novel and legacy signalling principles. This paper describes our work on making UTDP practical and useful for the engineers.

A numerical investigation is carried out to evaluate the influence of the gap between the bluff body and the bed on the wake characteristics generated in shallow flows. A sharp-edge bluff body with a fixed gap from the bed is employed in the study, and the results are compared with the no gap case. A sharp-edged bluff body was chosen to minimize the effect of reynolds number and ensure fixed flow separation points. The transient three-dimensional Navier–Stokes equations are numerically solved using a finite volume approach with the detached eddy simulation turbulence model. The flow field in this study involves two different fluids, i.e. water and the air above it. The volume of fluid method is used for tracking the free surface separating the water and air. The fluid structures that are generated in the wake are identified using the λ2-criterion. The results reveal that the gap flow will develop a new structure near the bed, which enhances the upwash flow immediately after the submerged jet is about to turn upwards due to the weak hydraulic jump. This structure plays an important role in recovering the free surface to its original shape at a shorter downstream distance from the bluff body than when there is no gap.

The use of low-cost devices for air quality monitoring is rapidly growing, and the reason behind the growth might (at least partially) be the real-time monitoring at a lower fixed and operating cost, ease of use and portability. nevertheless, the poor data reliability of low-cost sensors (LCS) remains a considerable challenge, especially when deployed in real-world conditions. This study aimed to evaluate and improve the performance of two commercially available indoor air quality monitoring LCS devices: AirVisual Pro and uRAD Monitor A3 (uRAD), which were used to monitor CO2 via non-dispersive infrared technology. The analysis took place from June to July 2019 in several classrooms of an urban school in Porto city. Machine learning techniques such as multivariate linear, support vector, gradient boosting and XGBoost regression models were used to perform an on-field calibration for improving the data accuracy of the devices. The results showed that although both the devices showed a strong linear correlation (r > 0.9) with the reference device, they might indicate deviated CO2 concentrations if used in their advertised plug and play format. Specifically, uRAD showed a steady offset compared to the reference values, while AirVisual Pro showed lower deviations than uRAD. The on-field calibration models improved the reliability and showed low root mean square error values (around 30 mg/m3) and a high coefficient of determination (0.99).

To preserve the harmony within a vernacular habitat, a delicate balance between living space, nature, and community must be maintained. This paper analyzes local communities from Maramureș, Romania, and their sustainable ways of living, and it also discusses the use of locally sourced materials in building settlements: a cautious combination of progressively integrating contemporary living solutions with preserving the powerful local heritage. Such initiatives become more challenging given that new, modern developments and rapid industrial changes tempt people away from ancient custom. In order to sustain the traditional habitat, as fundamental for the heritage preservation initiative, it is necessary to guide villagers in finding value and beauty locally and discourage them from migrating towards bigger cities or other countries. Based on two case studies of local craftsmen, Maria Zapca, a weaver from Săpânța, and Daniel Leș, a potter from Baia Sprie, the journey starts in Săpânța, home of the UNESCO heritage site The Merry Cemetery where the physical fabric of the place lends itself to sustaining local crafts and craftsmen. However, this is not an isolated case: Maramureș is famous throughout the world for its material culture such as wooden churches with tall spires – seven of them listed as UNESCO World Heritage Sites – alongside a multitude of home decorating fabrics and traditional attire still made and used by locals. Regional resources such as clay, wood, stone, wool, or hemp stand as fundamentals in shaping the vernacular habitat. Furthermore, the region is well-known for preserving customs and practices, which emphasize local group members’ lineage to the wider community. People are proud of their heritage and are connected to the cultural values that help shape their identity.

Climate change effect on water quality performance of lakes, rivers and streams is a significant concern for watershed planning and management. Climate change characteristics may potentially increase the likelihood that waterbodies will fail to meet established water quality standards, often obligating watershed managers to undertake expensive monitoring and load allocation studies for possible remedies against such impairment. One such load allocation study involves the implementation of water quality trading (WQt), which often is proposed as a mechanism for improving surface water quality goals under a socially and economically feasible manner. However, while future growth and land use change is incorporated through a margin of safety, WQt markets do not typically incorporate the characteristics of climate change that have been suggested to exhibit strong linkages against achieving the desired levels of water quality benefit. Consequently, this modelling study evaluates the characteristics of climate change upon the levels of water quality benefit along a river system subject to distinct load removal exercises: a) removal upon point sources only and b) removal based on a point–nonpoint source trad- ing mechanism under a theoretical WQt program. this study applies such assessments upon the load allocation exercises through carbonaceous biochemical oxygen demand reduction for addressing a recognized dissolved oxygen problem along the Jordan river in Utah, conducting such analyses through selected climate change projections described by the representative concentration pathways. For achieving such tasks, separate simulations are conducted through the Water Quality Assessment simulation program, evaluating the performance of such trading mechanisms under observed meteorological data against modelled climate data through selected representative concentration pathway projections under a historical period from Water year 2007 to 2009. This exercise assesses the performance of such load allocation studies subject to climatic characteristics toward suggesting linkages among climate change, water quality benefit and the effectiveness of a theoretical WQt mechanism.

In dependence upon a given geometric configuration, an actual or forecasted number of vehicles arriving at an intersection can turn left or right, otherwise proceed straight through it. This article can be placed in between a research working paper, and a kind of informational brief report. Indeed, it deals with forecasting techniques for estimation of intersection turning movements. Such issue is crucial, both in network planning and in traffic engineering, while its applications span from traffic safety and environmental impacts, to signal timing, roundabout design and setting of traffic control strategies. The number of vehicles making each movement on an existing intersection can be manually collected, especially when operational analyses are undertaken. Nevertheless, when the intersection is at the planning or design stage, an estimation process is required. In its first part, this paper provides a brief literature review of some of theoretical and practical methods focused to forecast the intersection turning movements. Such a review is limited on methods used to distribute the incoming and exiting traffic volumes within the different intersection branches, then generating an estimation of the so-called intersection O/D matrix of turning flows. The second part of the paper is experimental. Two different, but similar, heuristic procedures have described. Then, they have successively applied to some selected intersection real traffic data sets, and the respective computational performances were compared. Namely, the first one is known as proportion methods, while the second one is called as the difference, or deviation, method. Each method of these two starts from an initial matrix, and through iterative steps it reaches the best estimate of the matrix of turning flows, with respect to a given distribution model. Test intersections with their related set of real traffic data have been used as input, and each of the two procedures, as described in advance, was applied to the same numeric instances. The obtained values were compared in respect to few selected performance indicators. Finally, the computational results were displayed and discussed. On this basis, some insights are drawn and useful remarks for application and future research have been addressed.

Climate change has led to triple digit temperatures globally, notably along the western coast of the United states. These changes have produced intense weather-related events such as fires and landslides. Green roofs are one strategy to mitigate these high temperatures. For this report, several studies were compiled, using data found from physical green roof models as well as on-site data from the Javits Center Green Roof. At the Javits Green Roof, an infrared camera was used to collect thermal images at various parts of the roof, to determine its effectiveness for thermal buffering. Off site, a rain simulator was used on model green roof and a control roof, to determine change in retention and peak runoff rate. The green roof was able to retain 2%–22% of rainfall and reduce peak runoff by 19%–28%. From the graph comparing roof temperatures, there were higher temperatures on the black top roof in comparison to the green roof, and the slopes of the lines indicated the mitigating effect of the green roof on heat waves. These models were also analysed with an infrared camera, which showed that green roofs can be, as much as 25°f cooler than their standard roof counterparts, providing valuable evidence for the usefulness of green roofs to combat heat waves. Runoff quality was experimentally measured using a green roof model, where nitrogen concentration is measured before and after to determine change in runoff quality. This concept is based on studies which claim that the addition of wood mulch to soil can reduce nitrogen content. This experiment revealed a 23% reduction in runoff nitrates for the wood-mulch treated soil, in comparison to a 6.5% reduction for the control roof. Furthermore, a mathematical model was used to determine the ceiling temperature of the Javits Center within 3%.