66 research outputs found
Development and application of optical process monitoring and controlling for production of chalcopyrite thin film layers
No full textFür die industrielle Herstellung von chalkopyritbasierten Absorbern ist für die Einhaltung von Qualitätsstandards eine reproduzierbare Prozesskontrolle notwendig. Die benötigte Prozesskontrolle ist in der Lage die Bildung von Phasen während des Prozesses zu detektieren. In dieser Arbeit ist ein optisches Konzept dargelegt, welches während des Abscheidungsprozesses Aussagen über die strukturelle Zusammensetzung erlaubt. Dazu sind für zwei Prozessarten (die Herstellung von Cu(In,Ga)Se2 mittels des Drei-Stufen-Prozesses, sowie die Herstellung von Cu(In,Ga)S2 mittels des RTP Prozesses) die Anwendung von optischen Methoden gezeigt. Die beschriebenen Methoden basieren auf der Streuung und der Messung der direkten Reflektion. Zur Korrelation der strukturellen und optischen Informationen sind für die beiden Prozessarten zwei verschiedene Vorgehensweisen dargelegt. Bei der Entwicklung einer Prozesssteuerung für die Herstellung von Cu(In,Ga)Se2 durch den Drei-Stufen-Prozess ist eine Vielzahl von Abbruchexperimenten in Abhängigkeit der ersten beiden Stufen durchgeführt werden. Dabei wurden beide Stufen separiert voneinander untersucht. Für die erste Stufe wurde eine temperaturabhängige Analyse des Precursors durchgeführt, um die Phasenbildung der ersten Stufe zu verstehen. In der zweiten Stufe wurde eine Serie aus Abbruchexperimenten gewählt, um durch ex-situ bestimmte Phaseninformationen die Korrelation mit der in-situ gemessenen optischen Information auszuführen. Aus dieser Korrelation ist eine sinnvolle Beschreibung der optischen Signale für die ersten zwei Stufen gewonnen worden. Für die Entwicklung der Prozesskontrolle für Cu(In,Ga)S2 wurden die Erkenntnisse aus der Untersuchung des Drei-Stufen-Prozesses auf die RTP Herstellung des Cu(In,Ga)S2 transformiert. Dabei wurde ebenfalls die Korrelation zwischen optischen und strukturellen Messungen durchgeführt. Allerdings wurden die Phaseninformationen während des Prozesses in-situ bestimmt, wodurch eine genaue Korrelation möglich ist. Dabei wurde eine aufwendige Simulation der optischen Signale durchgeführt, die anhand der strukturellen Informationen den Bildungsprozess beschreibt.Industrial fabrication of chalkopyrite absorbers to comply with international quality standards recommends a reliable process control. The required process control has to detect phase changes during the process. This thesis presents an optical concept which allows investigations about the structural status of the depositing layers. Therefore two different process types (the three stage process for manufacturing of Cu(In,Ga)Se2 and the rapid thermal processing of Cu(In,Ga)S2) were monitored by optical methods. The described methods based upon the measurements of scattering and direct reflection. Therefore two different optical models were formed, which describes the optical measurements by structural formation of the layers during the process. The developing of a reliable process control for the deposition of Cu(In,Ga)Se2 by the three-stage process a huge number of break-off experiments were prepared to investigate the first two stages. Both stages were investigated separately. The first stage was investigated by a temperature variation of the precursor to understand the formation of these layers. For investigations of the second stage a series of break-off experiments with varied copper content was done to correlate the in-situ monitored optical signals by ex-situ measured structure information. By use of this correlation a senseful result was gained and presented in this thesis. The development of a process control for Cu(In,Ga)S2 was done by use of the acquired knowledge of the deposition of Cu(In,Ga)Se2 were transformed to the RTP deposition of Cu(In,Ga)S2. Also for these investigation the correlation between optical and structural was done. In difference the measuring of the structural properties was done by an in-situ method, therefore an exact correlation was possible. An experienced simulation of the structural formation and phase changes was applied to simulate the optical measurements during the process
Improved techniques of measuring laminar flame speeds for fire safety and thermal engine applications
No full textAccurate measurements of laminar flame speeds are imperative in comprehending complex combustion phenomena, particularly under premixed conditions. This necessity drives the quest for high-fidelity data by minimizing potential uncertainty sources using robust measurement techniques. However, measuring the laminar flame speed of slowly propagating flames, often encountered for mildly flammable substances, presents a formidable challenge. Systematic errors stemming from radiation heat loss and gravity-induced buoyancy necessitate specialized measurement techniques and rigorous data post-processing to yield dependable flame speeds. In addition, flame speeds are essential for modeling and optimizing efficiency and pollutant emissions in technical combustion processes. This thesis introduces refined measurement methodologies tailored for assessing fire safety risks and determining flame speeds of conventional fuels in technical combustion processes. The research begins by assessing uncertainties, emphasizing the importance of optimizing fuel/oxidizer mixture preparation processes to mitigate uncertainties. The demand for experiments under elevated pressures and temperatures is addressed by employing the pressure-rise method in conjunction with optical flame measurements, allowing for cross-validation and increased data output for chemical kinetic model validation. The study extends its focus to refrigerants with a low global warming potential and their fire hazards. A specialized setup in microgravity environments mitigates buoyancy effects, and radiation heat losses can be considered separately, drastically reducing uncertainties. This thesis carefully examines the limitations of optical and pressure methods, leading to the recommendation of using pressure measurement for industrial assessment of refrigerant fire hazards. The method is simple, more robust, and provides ample data for validating kinetic models. The thesis involves creating accurate approximation formulas for laminar flame speeds in technical combustion processes for biofuel blends and gasoline through measurements, compiling and validating a kinetic model, and simulation under spark-ignition engine conditions. Incorporating these formulas into engine simulations significantly reduces calibration efforts, as demonstrated by comparing the early burn duration of simulations and engine experiments. This thesis contributes to the advancement of research and development processes in various industries by offering highly reliable measurement methodologies and data
Entwicklung und Applikation von optischen Prozesssteuerungen und Prozesskontrollen zur Herstellung von Chalkopyritschichten
No full textA Security Verification Template to Assess Cache Architecture Vulnerabilities
No full textIn the recent years, cache based side-channel attacks have become a serious threat for computers. To face this issue, researches have been looking at verifying the security policies. However, these approaches are limited to manual security verification and they typically work for a small subset of the attacks. Hence, an effective verification environment to automatically verify the cache security for all side-channel attacks is still missing. To address this shortcoming, we propose a security verification methodology that formally verifies cache designs against cache side-channel vulnerabilities. Results show that this verification template is a straightforward, automated method in verifying cache invulnerability.Accepted author manuscriptComputer EngineeringQuantum & Computer Engineerin
Laminar Burning Velocity of Market Type Gasoline Surrogates as a Performance Indicator in Internal Combustion Engines
No full textSurvey on Architectural Attacks: A Unified Classification and Attack Model
No full textAccording to the World Economic Forum, cyberattacks are considered as one of the most important sources of risk to companies and institutions worldwide. Attacks can target the network, software, and/or hardware. Over the years, much knowledge has been developed to understand and mitigate cyberattacks. However, new threats have appeared in recent years regarding software attacks that exploit hardware vulnerabilities. This article defines these attacks as architectural attacks. Today, both industry and academia have only limited comprehension of architectural attacks, which represents a critical issue for the design of future systems. To this end, this work proposes a new taxonomy, a new attack model, and a complete survey of existing architectural attacks. As a result, it provides the tools to understand architectural attacks in more depth and to start building improved designs and protection mechanisms.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Quantum & Computer Engineerin
An Updated Chemical Kinetic Model for the Simulation of Laminar Burning Velocities of Premixed Hydrogen-, Methane-, and n-Heptane/Air Flames
No full textAn Updated Chemical Kinetic Model for the Simulation of Laminar Burning Velocities of Premixed Hydrogen-, Methane-, and n-Heptane/Air Flames
No full textIntegral blow moulding for cycle time reduction of CFR-TP aluminium contour joint processing
No full text
- …
