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Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle. This resulted in the generation of cross flow surrounding the core jet flow from the conical nozzle. Due to the entrainment of the gas stream from the conical nozzle the pressure in its exit plane was found to be lower than that of the ambient. A Cold gas instead of hot combustion gases was used as the working fluid. A mathematical simulation of the concept was validated by experiment. Measurements confirmed the simulation results that due to the introduction of a second nozzle the pressure in the separated region of the conical nozzle was significantly reduced. It was also established that the boundary layer separation inside the conical nozzle was delayed thus allowing an increased degree of overexpansion. The condition established by the pressure measurements was also demonstrated qualitatively using transparent nozzle configurations.
In the Laser Powder Bed Fusion (LPBF) process, parts are built out of metal powder material by exposure of a laser beam. During handling operations of the powder material, several influencing factors can affect the properties of the powder material and therefore directly influence the processability during manufacturing. Contamination by moisture due to handling operations is one of the most critical aspects of powder quality. In order to investigate the influences of powder humidity on LPBF processing, four materials (AlSi10Mg, Ti6Al4V, 316L and IN718) are chosen for this study. The powder material is artificially humidified, subsequently characterized, manufactured into cubic samples in a miniaturized process chamber and analyzed for their relative density. The results indicate that the processability and reproducibility of parts made of AlSi10Mg and Ti6Al4V are susceptible to humidity, while IN718 and 316L are barely influenced.
A capacitive electrolyte-insulator-semiconductor (EISCAP) biosensor modified with Tobacco mosaic virus (TMV) particles for the detection of acetoin is presented. The enzyme acetoin reductase (AR) was immobilized on the surface of the EISCAP using TMV particles as nanoscaffolds. The study focused on the optimization of the TMV-assisted AR immobilization on the Ta 2 O 5 -gate EISCAP surface. The TMV-assisted acetoin EISCAPs were electrochemically characterized by means of leakage-current, capacitance-voltage, and constant-capacitance measurements. The TMV-modified transducer surface was studied via scanning electron microscopy.
Kompakter Aufbau eines lichtadressierbaren potentiometrischen Sensors mit verfahrbarem Diodenlaser
(2011)
Concept, scientific research and managerial applications of Provocative Coaching, according to the „Provocative Therapy“ of Prof. Dr. Frank Farrelly (University of Wisconsin, U.S.A) in terms of an application of the Provocative Communication Style in specific situations of practical leadership, especially in the role of a coach for their subordinates.
O Perfil Reiss apresenta no resultado uma visão da estrutura dos motivos e impulsos de uma pessoa. O ponto de saída para a análise do resultado é o conhecimento de que os motivos vitais (= valores e metas de sobrevivência) formam a moldura, na qual as competências e capacidades que uma pessoa possui possam se desabrochar de forma ideal. A partir desse princípio, não existe no Perfil Reiss nenhum resultado que se possa classificar como correto ou falso, nem como bom ou mau. Uma comparação entre o resultado do Perfil Reiss e o conteúdo de uma atividade apresentada ou ambicionada dá informação sobre até que ponto a capacidade de rendimento de uma pessoa nessa posição pode vir ou virá a se desenvolver por um longo tempo.
In this article we describe an Internet-of-Things sensing device with a wireless interface which is powered by the oftenoverlooked harvesting method of the Wiegand effect. The sensor can determine position, temperature or other resistively measurable quantities and can transmit the data via an ultra-low power ultra-wideband (UWB) data transmitter. With this approach we can energy-self-sufficiently acquire, process, and wirelessly transmit data in a pulsed operation. A proof-of-concept system was built up to prove the feasibility of the approach. The energy consumption of the system is analyzed and traced back in detail to the individual components, compared to the generated energy and processed to identify further optimization options. Based on the proof-of-concept, an application demonstrator was developed. Finally, we point out possible use cases.
Entwicklung einer Qualitätssicherung für das Laserstrahlschweißen im Vakuum mittels Bildverarbeitung
(2019)
Infused Thermal Solutions (ITS) introduces a method for passive thermal control to stabilize structural components thermally without active heating and cooling systems, but with phase change material (PCM) for thermal energy storage (TES), in combination with lattice - both embedded in additive manufactured functional structures. In this ITS follow-on paper a thermal model approach and associated predictions are presented, related on the ITS functional breadboards developed at FH Aachen. Predictive TES by PCM is provided by a specially developed ITS PCM subroutine, which is applicable in ESATAN. The subroutine is based on the latent heat storage (LHS) method to numerically embed thermo-physical PCM behavior. Furthermore, a modeling approach is introduced to numerically consider the virtual PCM/lattice nodes within the macro-encapsulated PCM voids of the double wall ITS design. Related on these virtual nodes, in-plane and out-of-plane conductive links are defined. The recent additive manufactured ITS breadboard series are thermally cycled in the thermal vacuum chamber, both with and without embedded PCM. Related on breadboard hardware tests, measurement results are compared with predictions and are subsequently correlated. The results of specific simulations and measurements are presented. Recent predictive results of star tracker analyses are also presented in ICES-2021-106, based on this ITS PCM subroutine.
In this paper, the use of reinforcement learning (RL) in control systems is investigated using a rotatory inverted pendulum as an example. The control behavior of an RL controller is compared to that of traditional LQR and MPC controllers. This is done by evaluating their behavior under optimal conditions, their disturbance behavior, their robustness and their development process. All the investigated controllers are developed using MATLAB and the Simulink simulation environment and later deployed to a real pendulum model powered by a Raspberry Pi. The RL algorithm used is Proximal Policy Optimization (PPO). The LQR controller exhibits an easy development process, an average to good control behavior and average to good robustness. A linear MPC controller could show excellent results under optimal operating conditions. However, when subjected to disturbances or deviations from the equilibrium point, it showed poor performance and sometimes instable behavior. Employing a nonlinear MPC Controller in real time was not possible due to the high computational effort involved. The RL controller exhibits by far the most versatile and robust control behavior. When operated in the simulation environment, it achieved a high control accuracy. When employed in the real system, however, it only shows average accuracy and a significantly greater performance loss compared to the simulation than the traditional controllers. With MATLAB, it is not yet possible to directly post-train the RL controller on the Raspberry Pi, which is an obstacle to the practical application of RL in a prototyping or teaching setting. Nevertheless, RL in general proves to be a flexible and powerful control method, which is well suited for complex or nonlinear systems where traditional controllers struggle.
Es existieren verschiedenste Arten von Spielen, die versuchen, die Motivation einer Spielsituation in einen ernsten Kontext zu überführen. In diesem Artikel wird der Überbegriff „Competence Developing Games“ definiert und anhand von Beispielen erläutert. Dafür werden Erkennungskriterien vorgestellt, entsprechende Spieltypen erläutert und eine Zuordnung durch-geführt.
Dr.-Ing. Martin Wolf ; Dipl.-Kaufm. Daniel Ulbrich , Dr. Pecher und Partner Ingenieurgesellschaft mbH, München. 31 S. (S. 139-168). Beitrag zum 1. Aachener Softwaretag in der Wasserwirtschaft < 1, 2007, Aachen>. Zusammenfasung [der Autoren] Die öffentlichen Kanalnetze Deutschlands stellen mit einem Wert von rd. 330 Mrd. € ein enormes Anlagevermögen dar. Auf Grund des oft schlechten Zustandes und geringer Ausgaben zur Instandhaltung und Erneuerung ist zu erwarten, dass durch die gegenwärtige Sanierungspraxis eher ein Substanzwertverzehr des Kanalnetzes als ein Substanzwerterhalt im Sinne des Generationenvertrages erzielt wird. Für einen nachhaltigen Betrieb und Erhalt der Kanalnetze sind deshalb Sanierungsstrategien erforderlich, die neben den technischen und gesetzlichen Anforderungen auch den mittel- und langfristigen Substanzwertverlauf berücksichtigen. Dieser wird beeinflusst vom erforderlichen oder durchgeführten Sanierungsumfang, Art und Zusammensetzung der ausgewählten Maßnahmen sowie der zeitlichen Abfolge der Sanierungsmaßnahmen. Erheblichen Einfluss auf den Substanzwertverlauf hat zudem die Berücksichtigung der hydraulischen Verhältnisse sowie der optisch nicht sichtbaren Undichtheiten. Entsprechend ist es erforderlich, die tatsächlich vorhandenen Defizite zu ermitteln und die Sanierungsmaßnahmen sowie eine Strategie zur Umsetzung zu erarbeiten. Da sich gezeigt hat, dass alleine die Einhaltung der technischen und gesetzlichen Anforderung für einen Substanzwerterhalt nicht ausreicht, muss die geplante Strategie im Dr.-Ing. Martin Wolf 139 von 170 Decision-Support-System kokas zur Sanierungsplanung und Strategieentwicklung 1. Aachener Softwaretag in der Wasserwirtschaft Hinblick auf die nachhaltige Wertentwicklung überprüft und ggf. Anpassungen vorgenommen werden. Kurzfristig erzielte Einsparungen durch reduzierten Schadensumfang oder einseitige Maßnahmenwahl ermöglichen zwar im günstigsten Fall, die Anforderungen einzuhalten, gehen jedoch zwangsläufig zu Lasten des Substanzwertes und führen mittel- und langfristig zu einer Verschärfung der Kosten- und Gebührensituation. Der monetäre, am konkreten Sanierungsaufwand orientierte Substanzwertansatz ermöglicht dabei, technische und kaufmännische Gesichtspunkte praxisnah zu verknüpfen und den bestmöglichen Ausgleich zwischen den gegenläufigen Zielen Substanzwerterhalt und Gebührenkonstanz zu finden.
Objekt-orientierte Modellierung hybrider Systeme mit heuristischen und analytischen Merkmalen
(1994)
Harte Echtzeit für Windows
(1999)
10 Regeln für das Desaster
(2001)