• Energy Research
• Article close
• DE close

Results obtained during the International Polar Year (IPY) on the thermal state of permafrost and the active layer in the Antarctic are presented, forming part of ANTPAS (‘Antarctic Permafrost and ...

We present a unified description of interface kinetic effects in phase field models for isothermal transformations in binary alloys and steps dynamics in molecular-beam-epitaxy. The phase field equations of motion incorporate a kinetic cross-coupling between the phase field and the concentration field. This cross coupling generalizes the phenomenology of kinetic effects and was omitted until recently in classical phase field models. We derive general expressions (independent of the details of the phase field model) for the kinetic coefficients within the corresponding macroscopic approach using a physically motivated reduction procedure. The latter is equivalent to the so-called thin interface limit but is technically simpler. It involves the calculation of the effective dissipation that can be ascribed to the interface in the phase field model. We discuss in details the possibility of a non positive definite matrix of kinetic coefficients, i.e. a negative effective interface dissipation, although being in the range of stability of the underlying phase field model. Numerically, we study the step-bunching instability in molecular-beam-epitaxy due to the Ehrlich-Schwoebel effect, present in our model due to the cross-coupling. Using the reduction procedure we compare the results of the phase field simulations with the analytical predictions of the macroscopic approach.

Large industrial sites commonly contain multiple production and utility systems. In practice, integrated optimization is often not possible because the necessary complete information cannot be exchanged between the systems. Often, industrial sites optimize the operation of production and utility systems sequentially without any feedback, which leads to suboptimal operation. In this paper, we propose a method to coordinate between production and utility systems in a multileader multi-follower Stackelberg game. The proposed method does not require complete information exchange. The only information exchanged in one feedback loop is the energy demand and demanddependent energy cost. In two case studies, the method reduces the total production cost by 7.6% and 3.4% compared to the common sequential optimization. These cost savings correspond to 84% and 88% of the potential cost savings by an integrated optimization. In summary, the proposed method reduces cost significantly, while only incomplete information is exchanged between production and utility systems. Computers & Chemical Engineering, 150 ISSN:0098-1354 ISSN:1873-4375

The deuterium excess of polar ice cores documents past changes in evaporation conditions and moisture origin. New data obtained from the European Project for Ice Coring in Antarctica Dome C East Antarctic ice core provide new insights on the sequence of events involved in Termination II, the transition between the penultimate glacial and interglacial periods. This termination is marked by a north–south seesaw behavior, with first a slow methane concentration rise associated with a strong Antarctic temperature warming and a slow deuterium excess rise. This first step is followed by an abrupt north Atlantic warming, an abrupt resumption of the East Asian summer monsoon, a sharp methane rise, and a CO 2 overshoot, which coincide within dating uncertainties with the end of Antarctic optimum. Here, we show that this second phase is marked by a very sharp Dome C centennial deuterium excess rise, revealing abrupt reorganization of atmospheric circulation in the southern Indian Ocean sector.

Quenching problems were investigated on inorganic luminescent materials for fluorescent lamps. It could be shown that the decrease of luminescence intensity under the influence of short-wave UV radiation is not only a function of the irradiation time but also depends strongly on the activator concentration and a mechanical treatment. The photochemical luminescence quenching represented by the intensity loss as a function of the irradiation time can be expressed as a sum of three exponential terms, constants and exponents of which contain the concentration of virgin and UV induced lattice defects in both the bulk and the surface. To explain the complex quenching process the theory of radiationless energy transport was used.

Der “Unterbau”, die Infrastruktursysteme – sie haben für die Entwicklung einer Gesellschaft selbst sowie für deren wirtschaftliche Entwicklung eine oft unterschätzte Bedeutung. Sie sind sehr langlebig und stellen eine enorme Investition dar. Einmal getroffene Entscheidungen (etwa über “eingesetzte” Technologien, Kapaziäiten) binden die Gesellschaft langfristig. Die Nachwirkungen beeinflussen auch die Handlungsoptionen nachfolgender Generationen. Neben den finanziellen Aspekten sind vor allem Aspekte der Ressourceneffizienz einmal gewählter Infrastruktur-Technologien in Betracht zu ziehen. Die starke Abhängigkeit vom eingeschlagenen Pfad führt zur Inflexibilität derartiger Systeme und kann somit zu einem Hemmnis für den technischen Fortschritt und die Wettbewerbsfähigkeit einer Gesellschaft werden. Dies gilt vor allem für leitungsgebundene Infrastruktursysteme (Wasser, Abwasser, Strom, Gas et cetera), ganz besonders dann, wenn sie unterirdisch verlegt und darum schlecht zugänglich sind. Im folgenden soll exemplarisch auf Abwasserentsorgungseinrichtungen eingegangen werden, die zu den ältesten Infrastruktursystemen gehören. Gerade im Bereich der Abwasserentsorgung sind die bestehenden Einrichtungen in einem zum Teil desolaten Zustand; in Deutschland stehen zur Sanierung der Systeme derzeit Re-Investitionen an, die auf die Größenordnung von mindestens 100–150 Milliarden DEM geschätzt werden. Die Handlungsfähigkeit der Akteure wird damit für Jahrzehnte eingeschränkt werden. Die Tatsache, daß hier mittelfristig ein beträchtlicher Investitionsbedarf besteht, sollte dazu genutzt werden, vorhandene Abwasserentsorgungs-Konzepte nicht unreflektiert fortzuschreiben, sondern sie vor dem Hintergrund der aktuellen umweltpolitischen Paradigmen (Ressourceneffizienz, Nachhaltigkeit) kritisch zu prüfen und gegebenenfalls einen technologischen Systemwechsel anzustoßen. Abstarct & Keywords → p. 238

We reconstructed the palaeoenvironmental conditions of the last ca. 8,000 years in the Tres Lagunas region of the Quimsacocha volcanic basin (ca. 3,800 m a.s.l.) in the southwestern Ecuadorian Andes. By means of a pollen and charcoal record, we analysed vegetation, fire, and climate history of this area, which is sensitive to climatic changes of both the Pacific as well as of the eastern Andes and Amazon region. Sediment deposits, pronounced increases of pollen and charcoal concentrations, and pollen taxa reflect warmer and drier conditions in the early to mid-Holocene (~8000 to 3900 cal. b.p.). During the late Holocene (2250 to −57 cal. b.p.), five warm and cold phases occurred at Quimsacocha. The most prominent cold phase possibly corresponds to the globally recognized Little Ice Age (LIA; ~600 to 100 cal. b.p.). The cold phase signal at Quimsacocha was characterized by a higher abundance of Poaceae, Isoëtes and Gentianella, which are favoured by cold and moist conditions. Frequent charcoal particles can be recorded since the early to mid-Holocene (~7600 b.p.). The high Andean tree species Polylepis underwent several phases of degradation and re-establishment in the basin, which could indicate the use of fire by pre-Columbian settlers to enhance the growth of preferred herb species. The Tres Lagunas record suggests that human populations have been influencing the environment around Quimsacocha since the last ca. 8,000 years. peerReviewed

Abstract The goal of the project “Smart Region Pellworm” is the establishment and operation of a smart grid with a hybrid energy storage system on the German island of Pellworm.One part of the project is the integration of power-to-heat appliances into the smart grid for demand side management purposes.Thispaper deals with the prerequisites and lessons learned from the integration of electric night storage heaters into Pellworm's energy management system. Special focus lies on the development of a heat demand prediction model.

Lightweight frame components made of aluminum and load optimized connecting elements allow the reduction of weight and energy consumption as well as the increase of payload. Complex frame structures which nowadays can be designed and optimized with the help of modern simulation technologies require the use of adapted manufacturing technologies. Especially the flexible machining of single or limited products on the basis of common machining strategies is still inefficient and economically unacceptable. This article describes the development of adequate strategies for a high quality machining using simultaneous five-axis milling. Consequently, the machining of composite extruded aluminum profiles with continuously embedded steel-wire elements and the preparation of joining areas on nodes and commonly extruded profiles for innovative joining by forming processes have been analyzed.

This paper addresses how urban sustainability is modeled and the ways criteria-based systems deal with its measurability for an effective and reliable assessment. Twelve sustainability models are reviewed and a subset is briefly presented. More importantly, this research work investigates five national rating systems of sustainable urban development compared with the newly developed CAMSUD system. The comparison focuses on the systems' structure, categorization, technical content and measurability. The main findings about the selected national rating systems thoroughly discussed in the paper are: (i) They all have a tree-like structure, (ii) their conceptualization and categorization follow three or four sustainability pillars models, sustainability topics or spatial scale; (iii) they use either planning-oriented or performance-oriented weighting approaches; (iv) the criteria are defined as sustainability goals, action measures or assignments to be fulfilled; (v) the sustainability items can hardly be juxtaposed since they are differently handled, (vi) overlapping criteria might occur, (vii) similar criteria can be categorized under different categories and this affects the emphasis put on these categories, (viii) all criteria are independently rated with no consideration of mutual interrelationships. In an attempt to solve some of these weaknesses, the newly developed CAMSUD system is introduced as alternative and relies on the following: (i) the system structure is considered as a network, (ii) the conceptualization and categorization is based on spatial scaling as well as on sustainability topics and pillars, (iii) many criteria are directly planning-relevant (23 of 40), (iv) the criteria are defined as sustainability goals rather than action measures and (v) the quantification of criteria is planned as to account for mutual interactions.