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The accelerated urbanization has led to increasing tension on urban land use. In this context, more and more slender high-rise buildings are being built worldwide in pursuit of better economic benefits. However, these structures are susceptible to wind excitation due to their lower first natural frequency. Different passive, semi-active, and active damping systems have been developed to reduce wind-induced structural vibration. Among them, the tuned mass dampers are widely used and proved as a very effective method in practice. However, this system requires a large additional damping mass. This also causes additional reinforcement, which increases the cost and carbon footprint. A huge space near the top story of the building is needed for the installation. In this research, a novel system named distributed-Multiple Tuned Facade Damping (d-MTFD) system is proposed by using specially designed parallel moveable Double-Skin Facade (DSF) outer skin as damping mass. These moveable facade elements can be installed on the upper stories of the high-rise building. Smooth-running guide rail systems are used to achieve the parallel moveability. Multi-objective optimization based on the Genetic Algorithm (GA) is applied to reduce the maximum top floor acceleration (Objective I) and to reduce the maximum facade relative displacement (Objective II) simultaneously. The optimization results for the passive and semi-active systems are presented in the form of the Pareto front. The trade-off between these selected two competing optimization objectives is observed. This approach was first validated in a simulation using a 306 m tall reference building for a wind speed of 13.5 m/s at 10 m above ground level with a return period of 10 years. Acceptable peak accelerations at the top story for hotel use and a maximum facade relative displacement of less than ±0.5 m could be achieved for the benchmark building with the d-MTFD system. For semi-active control, the variable damping coefficient can be achieved by using stepper motors in generator mode. The electrical damping coefficient can be continuously adjusted by the developed power electronics. In addition, electrical energy can be generated and stored in a battery. A full-scale prototype with one parallel moveable facade element was built. Based on the prototype, the functionality of the semi-active control using a stepper motor and its energy harvesting performance was tested by applying Hardware-in-the-Loop (HiL) simulations. Greybox system identification was used to estimate some parameters (spring stiffness, friction, etc.) in the connection. The accurate system identification results ensure further validation using HiL simulations. The HiL simulations successfully demonstrated the feasibility of a self-powered semi-active d-MTFD system.
Recent challenges and novel approaches of wireless communication networks are characterized by high performance requirements on the radio channel and by concepts of self-organization, in-network processing, or resource optimization which ultimately lead to distributed network applications, communication architectures, and radio transceivers.
Associated evaluation is driven by a multitude of ever-increasing requirements that call for multidisciplinary expertise. Depending on the discipline, simulation is one of the most widely used technologies, whereby often abstract assumptions and models do not allow for sufficiently accurate, comparable results.
In contrast, real-world measurements and field-tests can only be performed on actual systems, commonly under non-reproducible conditions.
This thesis establishes with the Split-Protocol-Stack a new type of evaluation method that intends to help closing the gap between purely simulative analyzes and real-world tests.
With the inclusion of real radio hardware and radio channels in the event-based simulation, this central hybrid approach in connection with the Radio-in-the-Loop methodology creates synergies in interdisciplinary fields.
The approach contains analytical discussions, methodological strategies, and practical contributions that are summarized as key elements in the subsequent central considerations and challenges.
With Real-Time-Shift, a pseudo-real-time synchronization approach for parallel simulation and radio channel emulation of communication flows is introduced.
Based on the underlying time compensation scheme, the discrete event simulation is decoupled from real-time constraints when exchanging event messages with real-world wireless hardware.
A physical layer emulation methodology and radio channel interface concept, called Radio-in-the-Loop, is introduced along with two practical realization approaches.
Furthermore, strategic details on radio network planning with an approach to automatic hardware resource allocation are presented for radio channel emulation-capable network testbeds.
The contributions of this work are evaluated using real-world reference measurements, practical application scenarios, and experiments that provide proof of concepts.
By means of an exemplary selected cross-layer optimization scenario, the benefits are practically demonstrated and discussed.
Finally, based on IEEE 802.15.4 as the reference protocol standard for low-power wireless networks, this thesis provides feasibility studies and analysis results using the representative prototype SEmulate for the Split-Protocol-Stack approach.
The requirement for wireless communication with a speed beyond 100 Gbps is growing. There are mainly two possible approaches to achieve 100 Gbps system. One approach is to target lower transmission bandwidth and very high spectral efficiency. This method requires advanced digital signal processing operations, which are power-hungry. Another possible path is to go for a high-transmission bandwidth and a moderate spectral efficiency. We decided for this direction to implement a 100 Gbps system. We have chosen parallel sequence spread spectrum (PSSS) as an analog-friendly mixed-signal modulation where most of the baseband processing is in the analog domain, and only a small part is in the digital domain. For the channel equalization, we consider an “effective channel” that takes into account the wireless channel and the effects of the transmitter and receiver hardware impairments. The influence of the nonlinear channel response was analyzed for a PSSS modulated signal by employing the RAPP model for the power amplifier. For the first time, we performed a Hardware-In-The-loop experiment using PSSS modulation in the terahertz band. A PSSS modulated signal at a chip rate of 20 Gcps with spectral efficiency of 4 bit/s/Hz is transmitted using a 230 GHz RF-frontend operating in the linear range to achieve a data rate of 80 Gbps. One more important property is that the channel estimation and equalization are performed in the analog domain. A high-speed channel equalization algorithm was developed and implemented on FPGA/ASIC, which operates at(1/10)th of PSSS symbol rate. A parallel PSSS encoder transmitter architecture was designed to work at a high chip rate, and it was implemented on FPGA /ASIC and had an energy efficiency of 0.21 pJ bit−1 on 28nm ASIC.
In this Thesis, we put forward a case for the analog-friendly modulation scheme called PSSS. This scheme does not only modulates the signal but rather builds up an eco-system (such as channel estimation, equalization, and synchronization), which is responsible for the baseband operation.