Experimental Investigation of the Spray Autoignition of n Heptane in a Jet in Cross Flow Configuration and Comparison to Single Droplet Ignition Simulations

Modern combustion machines, which inject liquid hydrocarbon fuels into compressed air at high temperatures, aim for a high compression ratio to achieve high process efficiency. This means, there is only a limited residence time of the fuel in the combustion chamber before autoignition. The residence time however is important in terms of vaporizing and turbulent mixing of the fuel with air. A well stirred mixture with a lean overall equivalence ratio (near the lean flammability limit) will reduce the combustion temperature and in turn reduce the production of nitric oxides (NO, N2O and NO2) through the Zeldovich mechanism. This thesis details the results obtained under the ESA MAP project CPS III (Combustion Properties of Partially Premixed Spray Systems), where (amongst other topics) n-heptane sprays are observed under machine conditions and these experimental results are compared to numerical results of a simulation for single droplet ignition. The experiments were conducted in the hot wind tunnel Bremen (HWK), a newly operational Ludwieg tube type wind tunnel, which provides high temperature and high pressure flows with moderate flow rates. The comparison of the experimental data and simulations shows, that for the simple case of an unobstructed jet in cross flow (JICF) configuration, the induction times and their scatter can be predicted fairly well by assuming for the simulation, many super-positioned monodisperse equidistant sprays of different droplet diameter and their respective volume fractions assuming a Rosin Rammler distribution

Travels in Bokhara

n/

The Role and Implications of Executive Functions on Learning and Performing Math in High School Algebra I Students

Current research is largely lacking in the areas of math, math learning deficits, and math-specific interventions. Even less available is research and interventions specific to high school learners. Some research addresses these areas with a specific focus on executive functions and how they may relate to student learning and performance. The present study sought to determine the relationship between three specific executive functions, Shift, Inhibit, and Working Memory, on learning and performance in math. Other executive functions, as measured by BRIEF rating scales and including Planning and Organization, Initiate, and Monitor, were also reviewed. Results of the present study found no relationship between Shift and Inhibit with learning and performance measures (e.g., homework completion, test/quiz grades) and a relationship between Working Memory and learning and performance measures (i.e., homework completion). A relationship was also found between Initiation, Planning and Organization, and Working Memory as having a relationship with student learning and performance. Based on these findings, future studies should look specifically at what learning behaviors and skills students demonstrate that lead to adequate math performance and how these skills relate to executive functions. Essentially, starting with relating basic math behaviors and skills (e.g., math fluency or algebra skills) to academic performance (e.g., test grades, homework completion, standardized test results) in math and then relating these results to measurable executive functions, which may be an indicator of how one learns math. This information would help demonstrate how actual skills translate to student performance and achievement and could then be related to the learning of math in a classroom, which tends to tax executive skills. This information would be helpful to support student iv learning and allow for the development of appropriate and effective interventions that meet the needs of students struggling to keep up with grade level academic materials

On the implications of knowledge bases for regional innovation policies in Germany

Regional innovation policies have been criticised for being too standardised, one-size-fits-all and place-neutral in character. Embedded in these debates, this paper has two aims: first, to analyse whether industries with different knowledge bases in regions in Germany have different needs for regional innovation policies, and secondly, to investigate whether knowledge bases can contribute to the fine-tuning of regional innovation policies in particular and to a modern, tailor-made, place-based regional innovation policy in general. It concludes that although needs differ due to differences in knowledge bases, those bases are useful only to a limited extent in fine-tuning regional innovation policies

Aufgaben und Struktur der Bezirkstage und Raete der Bezirke in der DDR 1952-1990/91 am Beispiel des Bezirkes Cottbus

Die Publikation beschreibt die verwaltungsgeschichtliche Entwicklung der Bezirkstage und Räte der Bezirke der DDR zwischen 1952 und 1990/91 am Beispiel des Bezirkes Cottbus. Sie geht detailliert auf die einzelnen Strukturteile und deren Aufgaben und Zuständigkeiten ein, gibt dadurch einen umfassenden Überblick über die von der wichtigsten Verwaltungsbehörde der DDR auf der regionalen Ebene bearbeiteten Sachgebiete und belegt die Ausführungen durch ausführliche Quellenangaben. Im Anhang werden die leitenden Mitarbeiter in Kurzbiographien vorgestellt. Begriffserklärungen DDR-typischer Termini und ein Sach- und Personenregister sowie ein Abkürzungsverzeichnis erleichtern dem Leser die Benutzung

Philanthropy Handbook - Giving Effectively from Singapore to Asia-Pacific

The purpose of this handbook is to: * Offer guidance to current and new philanthropists on how to start or expand your giving journey from Singapore.* Highlight joint areas for action that you can rally around with others to build the ecosystem and collectively address persistent needs.* Motivate inclusive wealth management by providing access to a network in Singapore that can support you in achieving both financial goals and social impact

ReFEx: Reusability Flight Experiment - A Demonstration Experiment for Technologies for Aerodynamically Controlled RLV Stages

The Reusability Flight Experiment (ReFEx) is a technology demonstration flight experiment to gain developmental and operational experience with a fully aerodynamically controlled reusable launch vehicle stage. It is slated to launch from Koonibba test range in South Australia in 2024 using a VSB- 30 sounding rocket to inject it into a trajectory typical of returning stages. Key factor is to demonstrate the capability to autonomously initiate return flight trajectory to the launch site using only aerodynamic means and reach designated waypoints. The project is currently in the final stages of AIV and organisational activities such as applying for a launch license. This paper gives an overview of the main systems and focuses on a system level FMECA approach used to identify failure response modes for the flight safety analysis

ReFEx: Reusability Flight Experiment – Trajectory Design

The DLR project ReFEx aims at flying a trajectory representative for aerodynamically controlled stages. Further objectives are demonstrating maneuverability capabilities and ensuring safety. The ReFEx trajectory is oriented towards flight paths of operational and conceptual winged reentry vehicles represented in a Mach-Altitude map. Reentry trajectories are designed based on iterative solution of three degrees of freedom equations of motion. To analyze the mission performance under perturbed conditions, they are integrated in a six degrees of freedom, closed loop simulation environment. After the experimental phase and prior to touchdown a reduction of impact energy through a flare maneuver is foreseen

ReFEx: Reusability Flight Experiment - Flight Safety Analysis

The German Aerospace Center project ReFEx aims to demonstrate autonomous GNC capabilities for aerodynamically controlled RLVs, its launch is scheduled for 2024 in Australia. This paper covers the flight safety analysis required by the Australian Space Agency (ASA). Monte Carlo campaigns results are used to assert that the flight termination system is capable of destabilizing the vehicle, to define impact probabilities for different ground areas, which are then use to calculate the risk of human injury for offnominal trajectories of the reentry segment. The results show that the requirements of the ASA are fulfilled with margin