Aspekte des Gewässerschutzes und der Gewässernutzung beim Anbau von Energiepflanzen: Ergebnisse eines Forschungsvorhabens im Auftrag des Umweltbundesamtes

Der vorliegende Arbeitsbericht entstand im Rahmen eines Forschungsvorhabens im Auftrag des Umweltbundesamtes und beleuchtet mit dem Thema 'Gewässerschutz und Energiepflanzen' einen Aspekt, der bisher nicht im Fokus der Diskussionen um den Energiepflanzenanbau stand. In dieser Studie wurden relevante Verwertungsketten für die energetische Nutzung von landwirtschaftlicher Biomasse in Deutschland anhand potenzieller Auswirkungen auf die Gewässer bewertet. Mögliche negative Wirkungen auf die Gewässer sind häufig auch aus Klimaschutzgründen relevant. Vorgestellt werden zudem Möglichkeiten des gewässerschonenden Anbaus. Die Analyse stützt sich auf die Auswertung von Literatur sowie schriftlicher und telefonischer Befragungen verschiedener Experten. Demnach bestehen Herausforderungen insbesondere bezüglich der Lagerung und Ausbringung von Gärresten sowie der Überwachung von Nährstoffströmen im Zu-sammenhang mit Biogasanlagen. Grünlandschutz und die Implementierung gewässerscho-nender Anbaupraktiken sind auch unabhängig vom Energiepflanzenanbau zu verfolgen. Im Hinblick auf die derzeitige, allgemeine Intensivierungstendenz der landwirtschaftlichen Flächennutzung sollte zudem eine Überprüfung bestehender Standards für die Landnut-zung vorgenommen werden. Eigenständige Standards nur für den Energiepflanzenanbau sind nicht zu empfehlen. In diesem Zusammenhang werden bestehende Förder- und Steuerinstrumente der Agrar-, Umwelt- und Energiepolitik diskutiert und ausgewählte politische Handlungsoptionen vorgestellt. -- This report results from a research project, commissioned by the German Federal Environment Agency (Umweltbundesamt), and with the subject of 'water protection and energy crops' examines an aspect that has not been in the focus of the discussions around the cultivation of energy crops so far. In this study the relevant chains for the energetic use of agricultural biomass in Germany are assessed with regard to their potential imapacts on water. Possible negative impacts are often as well relevant for climate protection. As well options for water-friendly cultivation are presented. The analysis is based on a review of literature as well as a questionnaire and interviews of different experts. According to this, challenges exist especially concerning the storage and application of fermentation residues as well as the monitoring of nutrients in relation to biogas plants. The protection of grassland and the implementation of water-friendly cultivation practices are to be pursued as well independently of the cultivation of energy crops. Moreover, in view of the current general tendency for intensification of agricultural land use, the existing standards for land use should be reassessed. Separate standards only for energy crops are not recommendable. In this context, existing incentive and steering instruments within agricultural, environmental and energy policy are discussed and selected options for adaptation presented.Energiepflanzen,Gewässerschutz,Biogasanlagen,Landnutzung,Steuerungsinstrumente,Energy crops,water protection,biogas plants,regulation instruments,land use

Micromechanical fracture modeling of asphalt concrete using a single-edge notched beam test

Cracks in asphalt pavements create irreversible structural and functional deficiencies that increase maintenance costs and decrease lifespan. Therefore, it is important to understand the fracture behavior of asphalt mixtures, which consist of irregularly shaped and randomly oriented aggregate particles and mastic. A two-dimensional clustered discrete element modeling (DEM) approach is implemented to simulate the complex crack behavior observed during asphalt concrete fracture tests. A cohesive softening model (CSM) is adapted as an intrinsic constitutive law governing material separation in asphalt concrete. A homogenous model is employed to investigate the mode I fracture behavior of asphalt concrete using a single-edge notched beam (SE(B)) test. Heterogeneous morphological features are added to numerical SE(B) specimens to investigate complex fracture mechanisms in the process zone. Energy decomposition analyses are performed to gain insight towards the forms of energy dissipation present in fracture testing of asphalt concrete. Finally, a heterogeneous model is used to simulate mixed-mode crack propagatio

Characterization of oxidative aging in asphalt concrete using a noncollinear ultrasonic wave mixing approach

Although possessing remarkable toughness in its original state, asphalt concrete (AC) becomes brittle and prone to damage with time in the form of costly pavement cracking. The time required to reach an unacceptable level of embrittlement depends upon a number of factors and varies widely from pavement to pavement, even within a given region and mixture type. Given the annual costs associated with pavement repair of damage caused by mechanical and thermal loads, considerable interest exists in testing methods to estimate damage in AC pavements. Current methods to evaluate the existing conditions of AC pavement surfaces for sustainability-based pavement asset management are based upon the binder’s rheological properties, are time consuming, costly, and by themselves, may cause additional damage. Oxidative aging is a key contributor in the deterioration of AC pavements. Exposure to environmental conditions causes gradual oxidative aging of the AC, where the highest aged material is located at the surface, whereas the material at the bottom of the pavement is significantly less aged. Over time, increasing aging at the surface leads to a pavement with graded material properties through its thickness where the material near the surface has warmer embrittlement temperatures and higher stiffness when compared with the bottom of the layer. Increasing aging also results in significant loss of adhesion between the binder, aggregates, and fines, which contributes to an increase in the microflaw population in the mastic and at the interfaces between the mastic and the aggregates. As the pavement is subjected to thermal and mechanical loads, microcracks develop and coalesce to form larger cracks. Repeated loading and exposure to environmental conditions eventually leads to significant deterioration of AC pavements. Although surveys are conducted to monitor the condition of pavements and to determine when preventative or corrective maintenance is necessary, accurate assessment of the amount of pavement deterioration has remained a challenge. A study to assess oxidative aging of AC using noncollinear wave mixing of two dilatational waves will be presented. Criteria are used to assure that the detected scattered wave originated via wave interaction in the AC and not from nonlinearities in the testing equipment. These criteria include frequency and propagating direction of the resultant scattered wave, and the time-of-flight separation between the two primary waves and the resulting scattered wave. It was observed that AC exhibits nonlinear behavior. It was also observed that the nonlinear response decreases with increased aging until ~24 hours of aging after which the nonlinear response exponentially increases. This observation is consistent with earlier studies including acoustic emission response to thermal loading, and with changes in dynamic modulus and fracture energy with increasing aging

Transkription. Analytische Aufbereitung gesprochener Sprache für die empirische Sozialforschung

Buttlar A-C. Transkription. Analytische Aufbereitung gesprochener Sprache für die empirische Sozialforschung. In: Boelmann JM, ed. Empirische Forschung in der Deutschdidaktik. Band 1: Grundlagen. 1st ed. Baltmannsweiler: Schneider Verlag Hohengehren; 2018: 313-327

Can crumb rubber modifier effectively replace the use of polymer- modified bitumen in asphalt mixture?

Laboratory scale mechanical performances on six plant produced mixtures; three semi-dense surface courses and three dense binder courses modified with engineered crumb rubber (ECR) using the dry process are presented. The two types of mixtures produced and investigated fulfilled for the most part, the requirements of the Swiss and/or US standards regarding volumetric properties, water sensitivity and rutting. In advanced testing where no requirements exist, the dense ECR mixtures performed similar to the reference polymer modified mixtures and slightly worse for semi-dense mixtures in high temperature tests, where the binder becomes viscous in the rubber-binder composite and its ability to transfer loads is reduced. The ECR mixtures performed similarly or better than the reference in low temperature tests.  Across the advanced testing data set, all obtained results were well within acceptable values for both ECR and reference polymer mixtures indicating that crumb rubber can effectively replace polymer in asphalt mixtures

Forschungs- und Entwicklungsprojekte: Virtuelle Maschinen: zSeries- und S/390-Partitionierung

Der gleichzeitige Betrieb mehrerer Gast-Betriebssysteme auf einem einzigen physischen Rechner unter einem Host-Betriebssystem ist eine leistungsfähige moderne Entwicklung. Bekannte Beispiele sind VMware für die IA32-Architektur sowie das Betriebssystem z/VM und die PR/SM-LPAR Einrichtungen der zSeries-Architektur. Die Nutzung eines Betriebssystems als Gast bedingt einen Leistungsverlust. Die als Partitionierung bezeichnete Zuordnung von Systemressourcen zu den einzelnen Gast-Betriebssysteme ist schwierig, wenn eine dynamische Anpassung an sich ändernde Lastprofile erforderlich ist. Diese Probleme lassen sich mittels Erweiterungen der Hardwarearchitektur adressieren, sowie durch Softwarestrukturen, welche diese Erweiterungen nutzen. Die Erweiterungen der Hardwarearchitektur gehen über das hinaus, was auf heutigen Rechnerarchitekturen wie IA32 oder Mips verfügbar ist. Der vorliegende Beitrag erläutert den optimalen Betrieb von Gast-Betriebssystemen und die begleitenden Partitionierungsmöglichkeiten auf der zSeries-Plattform und beschreibt die zusätzlichen Hardware und Software-Einrichtungen, welche dies ermöglichen.The capability to run multiple guest operating systems simultaneously on a single hardware platform is a powerful feature in a modern computer system.Well-known examples are VMware for the IA32-architecture and the z/VM operating system and the PR/SM-LPAR facilities of the zSeries architecture. Running an operating system as a guest results in a performance degradation. Partitioning of system resources and assigning them to individual guests may be difficult, if a dynamic adaptation to an ever changing load profile is required. Extensions of the hardware architecture and their exploitation by software permit to address these problems. Such extensions have not been available on existing architectures like IA32 or Mips. The following paper discusses the operation of guest operating systems and associated partitioning capabilities available in zSeries systems and describes supporting hardware and software facilities