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Novel fuzzy logic controllers with self-tuning capability
No full textTwo controllers which extend the PD+I fuzzy logic controller to deal with the plant having time varying nonlinear dynamics are proposed. The adaptation ability of the first self tuning PD+I fuzzy logic controller (STPD+I_31) is achieved by adjusting the output scaling factor automatically thereby contributing to significant improvement in performance. Second controller (STPD+I_9) is the simplified version of STPD+I_31 which is designed under the imposed constraint that allows only minimum number of rules in the rule bases. The proposed controllers are compared with two classical nonlinear controllers: the pole placement self tuning PID controller and sliding mode controller. All the controllers are applied to the two-links revolute robot for the tracking control. The tracking performance of STPD+I_31 and STPD+I_9 are much better than the pole placement self tuning PID controller during high speed motions while the performance are comparable at low and medium speed. In addition, STPD+I_31 and STPD+I_9 outperform sliding mode controller using same method of comparison study
Methods of frequency tuning vibration based micro-generator
No full textA vibration based micro-generator is an energy harvesting device that couples a certain transduction mechanism to the ambient vibration and converts mechanical energy to electrical energy. In order to maximize available power, micro-generators are typically inertial devices that operate at a single resonant frequency. The maximum output power is generated when the resonant frequency of the generator matches the ambient vibration frequency. The output power drops significantly if these two frequencies do not match due to the high Q-factor of the generator. This thesis addresses possible methods to overcome this limit of vibration based micro-generators, in particular, method of tuning the resonant frequency of the generator to match the ambient vibration frequency. This thesis highlights mechanical and electrical methods of resonant frequency tuning of a vibration based micro-generator. The mechanical frequency tuning is realized by applying an axial tensile force to strain the cantilever structure of the generator. A tunable micro-generator with a tuning range from 67.6 Hz to 98Hz and a maximum output power of 156.6µW at a constant low vibration acceleration level of 0.59m·s-2 was designed and tested. The tuning mechanism was found not to affect the damping of the generator. A closed loop frequency tuning system as well as the frequency searching algorithms has been developed to realize automatic frequency tuning using the proposed mechanical tuning method. The model of duty cycle of the system was established and it was proved theoretically that a reasonable duty cycle can be achieved if the generator and tuning system is designed properly.The electrical tuning method is realized by changing the load capacitance of the generator. Models of piezoelectric and electromagnetic generators using electrical tuning methods were derived. The model of the electromagnetic generator has also been experimentally verified. The electrically tunable generator tested has a maximum 3dB bandwidth of 4.2Hz. In conclusion, resonant frequency tuning using mechanical methods presented in the thesis have larger tuning range than that using electrical methods. However, frequency tuning using electrical tuning methods consumes less power than that using mechanical methods for the same amount of tuning range
God, Fine-Tuning, and the Problem of Old Evidence
No full textThe fundamental constants that are involved in the laws of physics which describe our universe are finely-tuned for life, in the sense that if some of the constants had slightly different values life could not exist. Some people hold that this provides evidence for the existence of God. I will present a probabilistic version of this fine-tuning argument which is stronger than all other versions in the literature. Nevertheless, I will show that one can have reasonable opinions such that the fine-tuning argument doesn’t lead to an increase in one’s probability for the existence of God
Closed loop frequency tuning of a vibration-based micro-generator
No full textThis paper presents a tunable electromagnetic vibration-based micro-generator with closed loop frequency tuning. Frequency tuning is realized by applying an axial tensile force to the micro-generator. A closed-loop frequency tuning system has been developed to control the tuning process so that the generator always operates at the ambient vibration frequency to make the entire process automatic. Experimentally the resonant frequency has been successfully tuned from 67.6 to 98 Hz when various axial tensile forces were applied to the structure. The generator produced a power of 61.6 to 156.6 μW over the tuning range when excited at vibrations of 0.588 m/s2
The time-domain response of coupled-resonator filters with applications to tuning
No full textThis thesis develops a new theory of tuning filters based on the time-domain response of the filter. These methods are shown to work very well for all-pole coupledresonator
filters in particular, and may be applied to automated tuning of filters.
Numerous filter-tuning methods are reviewed, and the attributes and limitations of each are discussed. Key results about transfer functions, filter theory and Laplace
transform theory are reviewed as applied to all-pole filters. The Fourier Transform theory is reviewed and a new, detailed analysis of the Vector Network Analyzer (VNA)
time-domain transform, including gating and windowing is presented, including new work in area of the compensation for the masking effects of time-domain gating.
A complete description of the time-domain tuning method is presented, which includes experimental and empirical results from simulations and measurements on filters.
The theoretical underpinning supporting the novel method of time-domain tuning is developed, along with a rigorous mathematical relationship between VNA timedomain
response of a simple filter, and the analytic impulse response. The timedomain results observed in experiments are shown to be directly correlated to the filter
transfer functions and the specific effects that differentiate the VNA time-domain transform from the analytically derived impulse response.
This thesis includes previously unpublished work that is the basis for two U.S. patents, as well as the development of a commercial filter tuning software program. An
improved method for filter tuning, which uses time-domain gating on the S 11 response of the filter is introduced, and shown to be a key improvement for developing automated
tuning techniques.
The details of a software application for filter tuning are presented, along with methods for determining and compensating the interactions from other resonators. A case
study of applying the FTS method to a complex duplex filter is described.
Areas for extension into other filter types are discussed. General guidelines for the successful application of the new tuning method to various filter types are presented,
along with other conclusions of this thesis
First measurement of the fragmentation fraction ratio fs/fd with tree level hadronic decays at 7 TeV pp collisions
No full textMerk, M.H.M. [Promotor]Tuning, N. [Copromotor
Optimal sigmoidal tuning curves for intensity encoding sensory neurons with quasi-Poisson variability
No full textRate-coding neurons are often characterized by their tuning
curve, that is, the average firing rate, T(x), as a function
of stimulus intensity, x. However the substantial natural
variability in firing rate that often occurs for a fixed stimulus
provides a limitation on the fidelity of firing rate
encoding of stimuli. Consequently, stimulus-dependent
variance in firing rate, V(x), is crucial in studies of tuning
curve optimality. Information theory can be used to quantify
such limits and to address the question of finding the
tuning curve that maximizes information rate
Power System Stabilizer Tuning Based on Multiobjective Design Using Hierarchical and Parallel Micro Genetic Algorithm
No full textIn order to achieve the optimal design based on some specific criteria by applying conventional techniques, sequence of design, selected locations of PSSs are critical involved factors. This paper presents a method to simultaneously tune PSSs in multimachine power system using hierarchical genetic algorithm (HGA) and parallel micro genetic algorithm (parallel micro-GA) based on multiobjective function comprising the damping ratio, damping factor and number of PSSs. First, the problem of selecting proper PSS parameters is converted to a simple multiobjective optimization problem. Then, the problem is solved by a parallel micro GA based on HGA. The stabilizers are tuned to simultaneously shift the lightly damped and undamped oscillation modes to a specific stable zone in the s-plane and to self identify the appropriate choice of PSS locations by using eigenvalue-based multiobjective function. Many scenarios with different operating conditions have been included in the process of simultaneous tuning so as to guarantee the robustness and their performance. A 68-bus and 16-generator power system has been employed to validate the effectiveness of the proposed tuning method
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