Search results for ""Verlag G. Mainz""

To avoid greenhouse gas (GHG) emissions and mitigate climate change, low-carbon technologies must be used to provide renewable energy and replace fossil fuels. However, this system transition is very material-intensive and leads to high demand for critical materials. Copper is such a material that is essential for electrical applications and many low-carbon technologies. The production of copper itself is an energyintensive process. Thus, two challenges arise that are addressed in this thesis: the flexible process operation in a fluctuating renewable energy system and the avoidance of process-based GHG emissions.The flexible operation of electricity-intensive processes can support the power grid and provide economic benefits. Demand response (DR) describes operational adjustments based on an economic incentive, such as fluctuating electricity prices. Our initial analysis shows a large DR potential of two electricity-intensive process steps in copper production. To consider th

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Organometallic chemistry has shown tremendous success in developing new metal catalysts for industrial applications, e.g. polymerization, organic synthesis or fine chemical synthesis. Nowadays, several active and selective catalysts are known and still, the issue of activity and selectivity remains a challenge. Nature has solved this issue by evolving selective enzymes. These enzymes have excellent catalytic properties with high substrate specificity and product selectivity due to their specialized active site. However, the advantage of high product selectivity comes at the cost of a limited substrate scope. The shape of the active site is crucial for selectivity since it is responsible for highly efficient substrate recognition and orientation together with stabilization of reactive intermediates. The number of enzymatic processes in industry increased due to an increased demand of enantiopure products. The concept of biohybrid catalysts, also named artificial metalloproteins/-enzy

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Transition metal catalysis plays a crucial role in the development of new chemical transformations, which can be broadly applied in organic synthesis, medicinal chemistry, synthesis of biologically relevant molecules, pharmaceuticals and other related fields. In recent years, the need for application of sustainable methods is significantly growing due to the necessity of waste-free transformations. Plenty of industrially run processes still apply classical procedures, which often lead to production of tons of waste as a consequence of multistep synthesis. Thus, development of novel catalytic systems which would afford complex molecular structures via straightforward processes is still desired. Hence, metal-catalyzed transformations play a crucial role in the development of new synthetic strategies, as they can easily lead to the reduction of synthetic steps and, ipso facto, reduction of waste leading to atom-economic transformations. Application of transition metals particularly in

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Transmitting analog audio, video, or sensor data with a digital system requires sampling and quantization. While a sampled bandlimited signal can be reconstructed perfectly if the Nyquist-Shannon sampling theorem is met, quantization unavoidably adds irreversible errors. Given a certain bitrate for quantization (or source coding in general), the achievable signal quality is therefore limited. Transmission of the signal over a noisy channel causes additional errors. If some part of the bitrate is used for protecting the signal with a channel code, these additional errors can be reduced or even eliminated. However, this reduces the achievable maximum quality if the gross bitrate is fixed. Since this compromise between quantization and channel coding is often designed for the worst-case channel, the signal quality saturates early with increasing channel quality, and transmission over a better channel is far below optimum.Instead of conventional digital systems, this thesis cover

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In the context of this work, three unilateral NMR sensors were designed, constructed and characterized. For the new sensors, the concept was chosen to vary the angle of the polarization of the magnets. This affects the size and the position of the sensitive slice. The MOUSEPAD, based on the modified design of the Profile NMR-MOUSE with 5 mm penetration depth, achieved a penetration depth of 17 mm. The Mini-MOUSEPAD is based on the Mini-MOUSE and has an increased penetration depth of 2.5 mm. The penetration depth is a crucial parameter for investigations with unilateral NMR, since the object of interest can be arbitrary shaped and the relevant areas at higher depths might be difficult to access. Therefore, these sensors might show a strategy for further miniaturization of state-of-the-art unilateral NMR sensors. The special magnet arrangement of both sensors results in a reduction of the magnetic field strenght (4.9MHz for the MOUSEPAD and 9.0 MHz for the Mini-MOUSEPAD) and much lowe

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In order to slow down global warming, greenhouse gas emissions must be reduced. Human-caused greenhouse gas emissions come primarily from consumption of fossil energy. In order to reduce the consumption of fossil energy, the demand is rising for energy-efficient technologies. One promising energy-efficient technology is the adsorption dishwasher that was commercialized recently. The use of adsorbents enabled the adsorption dishwasher to save 25% of energy compared to a conventional dishwasher. To increase the savings and to further enhance the entire process, the adsorption dishwasher should be improved. The improvement should foremost focus on the adsorbents, since adsorbents are the key of this energy-efficient technology.This thesis therefore assesses adsorbents for the application in an adsorption dishwasher. The assessment is carried out both experimentally and theoretically. Theoretical investigations are divided in 3 stages of complexity:Stage 1 is a static anal

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The increasing worldwide concerns about the danger of climate change have pushed goverments to strictly regulate CO2 emissions of automobiles. This development has led the auto industry to focus on design concepts that can reduce fuel consumption, and subsequently emissions. The power generation and tranmission systems, which lead the fuel consumption inefficiency in a car, are the leading factors for high emissions. The conventionally bulky structure of automobiles comes second. Thus improvements on autobody design can decrease the emissions significantly.

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In modern medicine, magnetic resonance imaging (MRI) is an essential diagnostic tool, which enables physicians to detect a great variety of diseases and physical injuries. The scope of possibilities encompasses neuro-, cardiovascular-, musculoskeletal-, hepatobiliary- and gastrointestinal imaging as well a magnetic resonance angiography. Besides commercially available MRI scanners, low magnetic field devices gain more and more attention because they are more compact, mostly portable, easier to handle due to the lack of cryogenic coolants, and usually come with a large cost saving.In this thesis, high magnetic field devices and unilateral NMR sensors are deployed to explore different biomedical topics. Imaging techniques are used to study the flow inside aneurysmsenlargements of blood vessels in the human body, whose rupture can lead to severe health issues. In an experimental flow set-up, different fluids and flow velocities are tested inside silicon aneurysm models with and

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Optimal operation and control of batch and semi-batch processes has an increasing importance in the chemical process industry. However, the solution of dynamic uncertainties in the process model might lead to a high risk of constraint violations. In order to solve the dynamic optimization problem under parametric uncertainty, four different approaches are investigated in this work. Thereafter, two of them are used in a multi-scenario eNMPC in order to robustly control batch processes under parametric uncertainties.

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Adsorption energy systems can be driven by thermal energy from waste heat or the sun and thereby allow reducing fossil energy consumption and thus reduce global greenhouse gas emissions. Adsorption heat pumps and chillers can provide heating or cooling, adsorption thermal energy storage allows storing thermal energy. However, adsorption energy systems suffer from high investment costs due to low performance.Performance of adsorption energy systems strongly depends on the equilibrium properties of the working pair as well as heat and mass transfer mechanisms of the adsorption material in the adsorption energy system (adsorbent configuration).Evaluating new working pairs and adsorbent configurations is rather challenging: While the working pair''s equilibrium properties can be determined with standardized measurement equipment, heat and mass transfer mechanisms cannot easily be determined, since they strongly depend on the full-scale adsorption energy system. Constructio

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Thermal energy storage (TES) helps to reduce energy consumption and peak demands by balancing heat supply and demand on all time scales from short-term to seasonal. Thus, TES is an important technology to improve flexibility and efficiency of energy systems. In particular, adsorption TES systems, which exploit the enthalpy of adsorption, provide high energy storage density and high efficiency.The present thesis therefore analyzes an adsorption TES unit for residential and industrial applications. Industrial energy supply can be made more efficient by integrating waste heat into the process heat supply and by using energy-efficient technologies. Adsorption TES contributes to both approaches: waste heat can be integrated via the heat pump effect and TES allows for energy-efficient cogeneration heat supply for batch processes.We evaluate the energy efficiency of the heat supply for an industrial batch process by adsorption TES and cogeneration. To evaluate the performance

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With the technological progress, devices, such as mobile phones, tablet computers or hearing aids, can be used in a large variety of every-day situations for mobile communication. Acoustic background noise signals, which are picked up with the desired speech signal, can impair the signal quality and the intelligibility of a conversation. A special noise type is generated outdoors, if the microphone is exposed to a wind stream resulting in strong-rumbling noise, which is highly non-stationary. As a result, conventional approaches for noise reduction fail in the case of noise induced by wind turbulences.This thesis is focused on the development of signal processing concepts, which reduce the undesired effects of wind noise. The key contributions are: Signal analysis of wind noise Digital signal model for wind noise generation Signal processing algorithms for detection and reduction of wind noise signals.All these topics are considered with the focus

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Terrestrial broadcast is traditionally realized over High Tower High Power (HTHP) networks which have been preserved in the transition from the analog PAL to the first generation of the digital DVB-T technology. The drawback of this traditional network design is its spectral inefficiency. The demand for providing more TV programs with HD quality as well as the increasing spectrum consumption of mobile internet services, with video streaming being one of the driving factors, necessitate a re-optimization of the current broadcast network and a more efficient allocation of frequencies.In this thesis, three options for a future frequency-efficient evolution and coexistence of terrestrial TV and mobile internet are specified and investigated: Transition from the current terrestrial broadcast with DVB-T to its successor DVB-T2 while retaining the HTHP network infrastructure Switch-over from DVB-T to DVB-T2 with transition to a Low Tower Low Power (LTLP) network infras

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Synthetic organic chemistry aims toward the development of methods for the practical synthesis of important molecules such as bioactive ingredients, pesticides, dyes, and polymers. Although extraction of organic molecules from natural resources is possible, organic synthesis often provides a cheaper and more practical access to them from readily accessible starting materials, as well as the possibility to artificially modify the structure of naturally-occurring molecules to increase their activity or modulate their properties. In medicinal chemistry, a standard approach to find the most potent active ingredient is the so-called combinatorial sythesis strategy: after identification of a promising structure, often a small molecule found in nature, a library of compounds with different substitution patterns is prepared and tested to find the bist hit.

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Smoking chimneys are a symbol for environmental impacts of industrial processes. Indeed, industrial processes are major contributors to environmental problems such as global warming. Beyond emission-related problems, industrial processes deplete limited resources because they require raw materials. Raw materials are directly linked to costs, emission-related impacts cause indirect expenditures, e.g., through the European emissions trading scheme (EU-ETS) for greenhouse gas emissions. Therefore, industrial enterprises seek to reduce costs by reducing environmental impacts of their processes.Two well-known strategies for reducing environmental impacts of industrial processes are process integration and recycling. Process integration establishes interconnections between formerly separate processes by utilizing co-products. Process integration thereby relies on unit processes with multiple products, so-called multi-product processes. Similarly, recycling uses waste as raw materia

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