Towards inverse modeling of turbidity currents: The inverse lock-exchange problem

A new approach is introduced for turbidite modeling, leveraging the potential of computational fluid dynamics methods to simulate the flow processes that led to turbidite formation. The practical use of numerical flow simulation for the purpose of turbidite modeling so far is hindered by the need to specify parameters and initial flow conditions that are a priori unknown. The present study proposes a method to determine optimal simulation parameters via an automated optimization process. An iterative procedure matches deposit predictions from successive flow simulations against available localized reference data, as in practice may be obtained from well logs, and aims at convergence towards the best-fit scenario. The final result is a prediction of the entire deposit thickness and local grain size distribution. The optimization strategy is based on a derivative-free, surrogate-based technique. Direct numerical simulations are performed to compute the flow dynamics. A proof of concept is successfully conducted for the simple test case of a two-dimensional lock-exchange turbidity current. The optimization approach is demonstrated to accurately retrieve the initial conditions used in a reference calculation.     

Implications of Weak Link Effects on Thermal Characteristics of Transition-Edge Sensors

Weak link behavior in transition-edge sensor (TES) microcalorimeters creates the need for a more careful characterization of a device’s thermal characteristics through its transition. This is particularly true for small TESs where a small change in the bias current results in large changes in effective transition temperature. To correctly interpret measurements, especially complex impedance, it is crucial to know the temperature-dependent thermal conductance, G(T), and heat capacity, C(T), at each point through the transition. We present data illustrating these effects and discuss how we overcome the challenges that are present in accurately determining G and T from I–V curves. We also show how these weak link effects vary with TES size. Additionally, we use this improved understanding of G(T) to determine that, for these TES microcalorimeters, Kaptiza boundary resistance dominates the G of devices with absorbers while the electron-phonon coupling also needs to be considered when determining G for devices without absorbers     

Elimination of Perfluorinated Surfactants – Adsorbent Evaluation Applying Surface Tension Measurements

The adsorption of perfluorooctane sulfonate (PFOS) onto activated carbons, nonfunctionalized polymeric adsorbents, and anion exchange resins was evaluated in batch as well as column experiments. It was found that the total PFOS capacity, adsorption kinetics, breakthrough times, and minimum effluent concentrations were highly dependent on the material properties, such as the inner surface area, pore size, functionalization, and hydrophobic character of the material, and on process parameters like temperature and ionic strength of the solution. The experiments furthermore revealed that surface tension measurements are a suitable method for online determination of PFOS concentrations above a defined value.     

Austenitic stainless steel for separating safeguards: development of an FEA-model for the simulation of impact tests in reference to material specific parameters

Austenitic stainless steels have a high potential for the use in separating safeguards of machine tools based on the TRIP (Transformation Induced Plasticity) effect. The problem with these materials is the high variance of the alloy composition. Therefore, the specific penetration resistance W _D,spec varies significantly. The presented research analyses the impact of material specific parameters on the specific penetration resistance W _D,spec and the FEA simulation of impact tests. The result of the project is the knowledge of the penetration resistance and hence the security (factor of safety) against penetration.     

增强现实技术于洪水风险沟通中的应用

气候变迁,特别是洪水问题给地处三角洲的城市带来了与日俱增的风险。作为应对手段,提出一种整合性的洪水风险管理方法,该方法确保了洪水风险沟通在洪水风险管理战略中的重要地位。洪水的可视化作为洪水风险沟通的一种工具,在改变人们对洪水风险的观念方面有着强大的作用。它可以通过互动的方式,使当地的利益相关者了解洪水的剩余风险和未来风险。其中增强现实技术作为一种可视化手段,它的快速发展与应用为风景园林设计、规划与教育等领域提供了崭新的交互方式。首先,探讨增强现实技术(AR)在洪水风险沟通中的应用现状,并重点关注增强现实技术的2个关键应用领域:对现场决策的支持和针对高层次设计的可视化与对景观干预的评估。随后,展示一种基于增强现实技术所开发的应用,该款创新性的应用为洪水风险沟通提供了一种轻量化的可视化手段。     

Mehr leichte Produkte aus Rohölen – Eine Herausforderung für die Ölindustrie

More light products from crude oil – A challenge to the oil industry . A new long-term pattern of demand for oil is evolving mainly due to the politically limited availability of crude oil and increasing prices. For the Federal Republic of Germany an essentially constant level of demand for naphtha and gasoline is expected with a shrinking demand for distillate and fuel oil. The expected pattern cannot be met by the currently predominating hydroskimming process. Technological possibilities and development of conversion processes are emphasized in this article: Thermal catalytic and hydrocracking as well as hydroconverting for steam cracker feed generation. Increasing importance is predicted for residue cracking. Oil will continue to make a major contribution and the oil industry will be able to keep step with product demand.     

Description of the Sounding Rocket Experiment—SOURCE

A SOUnding Rocket Compere Experiment (SOURCE) is prepared for launch in spring 2008 and shall deliver approximately 360 s of microgravity time. The experiment is intended to partially fulfill the scientific objectives of the European Space Agency Microgravity Applications Program project AO-2004-111 (Convective boiling and condensation). One of the tasks of this experiment is the investigation of capillary dominated flow at a heated wall. The SOURCE experiment will also serve the needs of the COMPERE research group whose mandate is to investigate the behavior of propellant in spacecraft tanks. SOURCE is a benchmark type of experiment on fluid behavior in tanks to test hypotheses and numerical predictions (quantitative results on a tank scale). Several work packages have been distributed to the Center of Applied Space Technology and Microgravity (ZARM) to manage a part of the preparation of this experiment. Since ZARM acts also as a principal investigator, the subject of surface tension driven flows is one of the main topics. It includes the design of the experimental setup to study free surface behavior as well as the numerical predictions to quantify the heat transfer at a non-isothermal boundary condition in the absence of gravity.