Mathematical analysis of a wave energy converter model

In a context where sustainable development should be a priority, Orazov et al. have proposed in 2010, an excitation scheme for buoy-type ocean wave energy converters. The simplest model for this scheme is a non autonomous piecewise linear second order differential equation. The goal of the present paper is to give a mathematical framework for this model and to highlight some properties of its solutions. In particular, we will look at bounded and periodic solutions, and compare the energy-harvesting capabilities of this novel WEC with respect to that of a wave energy converter without mass modulation.     

A comparative approach to the economic modelling of a large-scale wave power scheme

Conversion of marine energy sources, including ocean waves and tidal currents, into electricity is a rapidly developing industry. Although many technologies have been proposed and some have generated electricity at full scale, it is difficult to predict which technology will be economic at large scales of installation. Several studies have been conducted which estimate the cost of electricity on the basis of schematic designs. However, each study represents a best estimate of the future cost based on current design details and direct comparison between the results of these studies is not straightforward. A methodology for directly comparing different wave energy concepts and potential locations would be beneficial to aid investment decisions. In this study we describe how the established data envelopment analysis technique could be employed for this purpose. The developed model is employed to rank the efficacy with which several types of conceptual and prototype wave energy conversion technologies generate electricity from the wave energy resource available at UK and US sites.     

A theorem on energy integrals for linear second-order ordinary differential equations with variable coefficients

We aim at demonstrating a novel theorem on the derivation of energy integrals for linear second-order ordinary differential equations with variable coefficients. Namely, in this context, we will present a possible and consistent method to overcome the traditional difficulty of deriving energy integrals for Lagrangian functions that explicitly exhibit the independent variable. Our theorem is such that it appropriately governs the arbitrariness of the variable coefficients in order to have energy integrals ensured. In view of the theoretical framework in which the theorem will be embedded, we will also demonstrate that it can be applied as a mathematical method to solve linear second-order ordinary differential equations with variable coefficients. These results are expected to have a generalized fundamental character.     

我国可持续发展指标体系属性区间识别综合评价模型及其应用

可持续发展越来越多地受到不确定性因素的影响 .试将属性评价模型应用于可持续发展指标体系的评价 ,对我国可持续发展总体能力进行定量研究 ,并进行多层次综合属性评价 ,为属性分析方法在可持续发展研究中的应用做了有益的尝试 ,评价结果为政府指导与调控我国可持续发展规划提供科学参考依据 .     

A multicriteria approach to sustainable energy supply for the rural poor

Despite significant progress in energy technology, about two billion people worldwide, particularly the poor in rural areas of developing countries, have no access to electricity. Decision-making concerning the most appropriate energy technology for supplying these areas has been difficult; existing energy decision-support tools have been useful but are mostly incomplete. Trade-offs, as well as impacts that can be positive or negative, may emerge as a result of implementing modern forms of energy. These can affect both community’s livelihoods as well as the confidence of decision-makers in relation to alternative technologies. The paper discusses a newly designed multicriteria approach and its novel robustness analysis for selecting energy generation systems for the improvement of livelihoods in rural areas. The proposed methodology builds upon a sustainable rural livelihoods framework to address multiple interactions and calculate trade-offs aimed at boosting decision-makers’ confidence in the selected technologies. The methodology is tested via a case study in Colombia.     

我国钢铁行业上市公司可持续增长状况的实证分析

高速增长,快速扩张是许多企业追求的目标,但理论和实践均证明企业增长或扩张速度并非越快越好,企业的增长速度只有与自身的经营效率、财务政策相匹配,才具有可持续性。本文选取沪深两市32家钢铁行业上市公司为样本,以罗伯特·希金斯和詹姆斯·范霍恩的可持续增长模型作为理论基础,通过描述性统计、Wilcoxon Signed Ranks检验等统计方法检验钢铁行业的增长现状及其增长的可持续性。研究结果表明:近年我国钢铁行业上市公司的实际增长率远远超过了可持续增长率,如此高速增长并不具有可持续性;在整个行业高速增长的背景下,其可持续增长率却逐年下滑;盈利能力下降是导致可持续增长率下滑的主要原因。只有采取增加产品技术含量和附加值,降低运营成本,提高技术装备水平等措施提高盈利能力,进而提高可持续增长率,并使企业实际增长率与可持续增长率相匹配,钢铁企业才可能实现快速可持续发展。     

Energy efficiency and risk management in public buildings: strategic model for robust planning

Due to deregulations of the energy sector and the setting of targets such as the 20/20/20 in the EU, operators of public buildings are now more exposed to instantaneous (short-term) market conditions. On the other hand, they have gained the opportunity to play a more active role in securing long-term supply, managing demand, and hedging against risk while improving existing buildings’ infrastructures. Therefore, there are incentives for the operators to develop and use a Decision Support System to manage their energy sub-systems in a more robust energy-efficient and cost-effective manner. In this paper, a two-stage stochastic model is proposed, where some decisions (so-called first-stage decisions) regarding investments in new energy technologies have to be taken before uncertainties are resolved, and some others (so-called second-stage decisions) on how to use the installed technologies will be taken once values for uncertain parameters become known, thereby providing a trade-off between long- and short-term decisions.     

Design of regional production networks for second generation synthetic bio-fuel - A case study in Northern Germany

In the medium-term, second generation synthetic bio-diesel will make an important contribution to sustainable mobility. However, attributed to political, technical, and market related uncertainties, it is still not clear which interest groups will invest in production capacities and which technologies will be used. Hence, a multi-period MIP-model is presented for integrated location, capacity and technology planning for the design of production networks for second generation synthetic bio-diesel. The approach is applied to the region of Niedersachsen, Germany. Principle network configurations are developed for this region considering different scenarios and different risk attitudes of interest groups. As results of the investigation, recommendations are drawn regarding advantageous plant concepts, as well as strategies for the capacity installation. Finally, recommendations for political decision makers as well as for potential investors are deduced.     

Statistics and probability theory in renewable energy: Teaching and research

In this paper, the key-role and utility of statistics and probability theory in the field of renewable energy are emphasized and illustrated via specific examples. It is demonstrated that renewable energy is a very suitable field to effectively teach and implement many statistical and probabilistic concepts and techniques. From a research point of view, statistical and probabilistic methods have been successfully employed in evaluating renewable energy systems. These methods will continue to be of core interest for the renewable energy sector in the future, as new and more complex renewable energy systems are developed and installed. In this context, some future research directions in relation to the evaluation of renewable energy systems are also presented.     

New advances in economic modelling and evaluation of environmental issues

This paper gives an overview of recent progress made in modelling economic environmental systems and in environmental policy analysis. In the modelling part attention will be given to new integrating frameworks offered inter alia by materials balance approaches, especially in the context of linkages between physical environmental phenomena and economic production and valuation. These can be relevant for studying materials-product chains, multisectoral materials flows, or even multiple use of complex ecosystems. Modern approaches will be dealt with, such as analysis for sustainable development, and ways of incorporating scenario experiments in environmental modelling approaches. In the context of sustainable development, modelling of multiple use of ecosystems and of spatial dimensions is also discussed. In the last part of the paper new advances in the area of environmental policy analysis will be dealt with. The main focus will be on methods for addressing uncertainty in evaluating environmental policy strategies, in particular fuzzy information and the use of meta-analysis.     

The Pohozaev-Schoen identity on asymptotically Euclidean manifolds: Conservation laws and their applications

The aim of this paper is to present a version of the generalized Pohozaev-Schoen identity in the context of asymptotically Euclidean manifolds. Since these kind of geometric identities have proven to be a very powerful tool when analysing different geometric problems for compact manifolds, we will present a variety of applications within this new context. Among these applications, we will show some rigidity results for asymptotically Euclidean Ricci-solitons and Codazzi-solitons. Also, we will present an almost-Schur type inequality valid in this non-compact setting which does not need restrictions on the Ricci curvature. Finally, we will show how some rigidity results related with static potentials also follow from these type of conservation principles.     

Modeling sustainability transitions on complex networks

There has been renewed interest in sociotechnical systems in the context of transitioning to a more sustainable society. While gains have been made in the qualitative understanding of sustainable transitions and sociotechnical systems, these approaches have not been well‐operationalized. Given the importance of meeting future energy and environmental policy targets, there is need to develop predictive techniques and more robust methods to quantify and analyze sociotechnical systems undergoing rapid change and uncertainty due to sustainability pressures. Sustainability transitions depend on large‐scale diffusion of technological and behavioral innovations on physical and virtual networked systems. Transitions can therefore be viewed as a subclass of diffusion phenomenon and subject to a range of mathematical and computational methods. We review, categorize, and critically assess methodological and theoretical approaches that integrate different aspects of sustainability, innovation, and complexity. We argue that these approaches should be adapted to improve our understanding of the behavior and dynamics of a broad range of sociotechnical systems to meet sustainability objectives. We therefore also make the conceptual link between complexity and sustainability as complimentary fields of research to inform policy and decision making to achieve more sustainable outcomes. © 2014 Wiley Periodicals, Inc. Complexity 19: 8–22, 2014     

Control and game-theoretic assessment of climate change: Options for Joint Implementation

The Framework Convention on Climate Change (FCCC) demands reductions in greenhouse gas emissions by the industrialized countries, while developing countries are still permitted to expand their energy consumption and greenhouse gas emissions. To identify, assess and compare options for avoiding and minimizing anthropogenic climate change, the framework of dynamic-game models (the SCX conflict model and the problem-specific TEM model) is applied to analyze the interaction between energy technologies, emission reductions and economic output with regard to energy use and the relationship between conflict and cooperation in climate policy. Basic variables are energy production, emissions into the enviroment, the energy price and the economic output. Major control parameters are the allocation of funding with regard to various energy options and the degree of international cooperation through technology transfer and capital flow. In particular, the impact of cooperation between industrialized and developing countries is evaluated to understand the role of governments in the transition to sustainable market economies. Simulations and numerical results are presented which can be used in a constructive way to implement a Joint-Implementation Program as an advanced market institution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of photovoltaic cells in a multi-criteria decision making process

The requirements to satisfy the energy needs of today without compromising those of future generations have forced humans to adopt rules that permit a better use of the available resources, of which the sun is an inexhaustible energy source. Amongst the energy sources that offer the possibility of exploiting the resources offered by the Earth, solar energy has acquired great strength. Photovoltaic energy has presented a major evolution and it is forecasted as being an important contributor to power generation and an alternative to other non-renewable energy sources. The high cost of solar electricity is today the main reason why electricity from photovoltaic systems has not been introduced in a more widespread way. In this context, the aim of this paper is the study and analysis of the decision criteria to be used when searching for the best photovoltaic cell, studying both the criteria that exert most influence or their manufacture (defined by quantitative and qualitative values) and the alternatives which will be the decision problem to be solved; each alternative will correspond to one type of photovoltaic cell. Thus, relevant information has been provided by three experts and the TOPSIS method has been used to aggregate all the information combined with the use of fuzzy sets which will model the use of linguistic labels in the process.     

基于三方演化博弈的后补贴时代新能源汽车政产学协同创新机制研究

政产学协同创新是促进新能源汽车发展的重要举措。我国将进入新能源汽车后补贴时代,这项举措无疑会对新能源汽车产业带来巨大的影响。本文在拟取消新能源汽车补贴的大背景下,运用三方演化博弈方法,建立了新能源汽车企业、高校、政府三方的协同创新博弈支付矩阵,通过Matlab的数值仿真,研究了相关参数对三方协同创新策略的影响。结果表明:三方参与协同创新意愿增长速度不同,且政府参与意愿会随着新能源汽车企业和高校参与意愿的增长而下降;新能源汽车企业参与协同创新的意愿趋近于稳定的速度始终快于高校;政府对新能源汽车企业和高校协同创新的激励成本的大小影响着政府的参与意愿;政府参与和不参与协同创新的可获得收益不能单独影响政府的参与意愿,参与和不参与可获得收益之间差额的大小决定政府的参与意愿。     

Initiating a state of the art system for real-time supply chain coordination

Intelligent Wireless Web (IWW) employs the capabilities of high speed wireless networks and exploits the parallel advancements in Internet-based technologies such as the Semantic Web, Web Services, Agent-based Technologies, and context awareness. Considering its great potentials to be applied in business systems, we have devised an innovative model, based on the IWW services, for a typical mobile real-time supply chain coordination system which has been developed and tested in a real operational environment. Our article investigates the proposed system in this way: at the start, the building blocks of the IWW are discussed in detail. Then, we fully explain the basic concepts of mobile real-time supply chain coordination and concentrate on the motivations to implement such a modern system. The vision of intelligent wireless web services, as discussed in this paper, centers on the need to provide mobile supply chain members highly specific data and services in real-time on an as-needed basis, with the flexibility of use for the user. In this regard, we investigate nine enabling technologies of the IWW for our system and discuss how, by exploiting the convergence and synergy between different technologies, it has become possible to deliver intelligent wireless web support to mobile real-time supply chain coordination. Afterwards, a practical framework is clearly established in four phases. This initiative system has been implemented in the laboratory and has passed the evaluation processes successfully. Further details will be announced in near future in another research article.     

Optimizing the positioning and technological choices of RFID elements for aircraft part identification

This paper concerns the integration of RFID (Radio Frequency IDentification) technologies in helicopters. A global RFID system, including RFID tags (passive, battery assisted and active), reading modules and data concentrator, will be embedded in helicopters. Such an integration requires a positioning model, which must consider technological choices of the on-board components. The proposed approach combines an optimization model and a physical model to determine an optimal covering of each tag by at least one reading module. This covering is based on radio wave propagation. The optimization model is derived from a location model with specific constraints. Experimental results validate the approach in an industrial context.     

Sustainable energy futures: Methodological challenges in combining scenarios and participatory multi-criteria analysis

This paper analyses the combined use of scenario building and participatory multi-criteria analysis (PMCA) in the context of renewable energy from a methodological point of view. Scenarios have been applied increasingly in decision-making about long-term consequences by projecting different possible pathways into the future. Scenario analysis accounts for a higher degree of complexity inherent in systems than the study of individual projects or technologies. MCA is a widely used appraisal method, which assesses options on the basis of a multi-dimensional criteria framework and calculates rankings of options. In our study, five renewable energy scenarios for Austria for 2020 were appraised against 17 sustainability criteria. A similar process was undertaken on the local level, where four renewable energy scenarios were developed and evaluated against 15 criteria. On both levels, the scenario development consisted of two stages: first an exploratory stage with stakeholder engagement and second a modelling stage with forecasting-type scenarios. Thus, the scenarios consist of a narrative part (storyline) and a modeled quantitative part. The preferences of national and local energy stakeholders were included in the form of criteria weights derived from interviews and participatory group processes, respectively. Especially in the case of renewable energy promotion in Austria, the paper systematically analyses the potentials and limitations of the methodology (1) for capturing the complexity of decision-making about the long-term consequences of changes in socio-economic and biophysical systems and (2) for appraising energy futures. The paper concludes that assessing scenarios with PMCA is resource intense, but this methodology captures successfully the context of technology deployment and allows decision-making based on a robust and democratic process, which addresses uncertainties, acknowledges multiple legitimate perspectives and encourages social learning.     

Stochastic Dynamic Programming Formulation for a Wastewater Treatment Decision-Making Framework

In this paper, a decision-making framework (DMF) based on stochastic dynamic programming (SDP) is presented for a wastewater treatment system, consisting of a liquid treatment line with eleven levels and a solid treatment line with six levels (Chen and Beck, 1997). A continuous-state SDP solution approach based on the OA/MARS method (Chen, Ruppert, and Shoemaker, 1999) is employed, which provides an efficient method for representing a wide range of possible influent conditions. The DMF is used to evaluate current and emerging technologies for the multi-level liquid and solid lines of the wastewater treatment system. At each level, one technology unit is selected out of a set of options which includes the empty unit. The DMF provides a comparison on possible technologies for screening which types of technologies may best be further developed in order for an urban wastewater infrastructure to be judged progressively more sustainable. The results indicate that one or a pair of technologies are dominant in each level. The cheap, lower-technology unit processes receive a mixed review. Some of them are selected as the most promising technology units while the others are not considered as good candidates.