Analog Implementation of Fractional-Order Elements and Their Applications

With advancements in the theory of fractional calculus and also with widespread engineering application of fractional-order systems, analog implementation of fractional-order integrators and differentiators have received considerable attention. This is due to the fact that this powerful mathematical tool allows us to describe and model a real-world phenomenon more accurately than via classical “integer” methods. Moreover, their additional degree of freedom allows researchers to design accurate and more robust systems that would be impractical or impossible to implement with conventional capacitors. Throughout this thesis, a wide range of problems associated with analog circuit design of fractional-order systems are covered: passive component optimization of resistive-capacitive and resistive-inductive type fractional-order elements, realization of active fractional-order capacitors (FOCs), analog implementation of fractional-order integrators, robust fractional-order proportional-integral control design, investigation of different materials for FOC fabrication having ultra-wide frequency band, low phase error, possible low- and high-frequency realization of fractional-order oscillators in analog domain, mathematical and experimental study of solid-state FOCs in series-, parallel- and interconnected circuit networks. Consequently, the proposed approaches in this thesis are important considerations in beyond the future studies of fractional dynamic systems

Realization of Fractance Device using Continued Fraction Expansion Method

The realization of fractional-order circuits is an emerging area of research for people working in the areas of control systems, signal processing and other related fields. In this paper, an attempt is made to realize fractance devices. The continued fraction expansion formula is used to calculate the fractance device's rational approximation. For the simulation in the experimentation, the third-order approximation for fractional order, α = -1/2, -1/3, -1/4 is used. For the aim of mathematical simulation, the MATLAB platform was used. The proposed rational approximation is used to create a circuit. The TINA programme is used to simulate circuits. It has been discovered that the simulation and theoretical conclusions are in agreement

HYBRID APPROXIMATION METHOD FOR TIME RESPONSE IMPROVEMENT OF CFE BASED APPROXIMATE FRACTIONAL ORDER DERIVATIVE MODELS BY USING GRADIENT DESCENT ALGORITHM

Due to its high computational complexity, fractional order (FO) derivative operators have been widely implemented by using rational transfer function approximation methods. Since these methods commonly utilize frequency domain approximation techniques, their time responses may not be prominent for time-domain solutions. Therefore, time response improvements for the approximate FO derivative models can contribute to real-world performance of FO applications. Recent works address the hybrid use of popular frequency-domain approximation methods and time-domain approximation methods to deal with time response performance problems. In this context, this study presents a hybrid approach that implements Continued Fraction Expansion (CFE) method as frequency domain approximation and applies the gradient descent optimization (GDO) for step response improvement of the CFE-based approximate model of FO derivative operators. It was observed that GDO can fine-tune coefficients of CFE-based rational transfer function models, and this hybrid use can significantly improve step and impulse responses of CFE-based approximate models of derivative operators. Besides, we demonstrate analog circuit realization of this optimized transfer function model of the FO derivative element according to the sum of low pass active filters in Multisim and Matlab simulation environments. Performance improvements of hybrid CFE-GDO approximation method were demonstrated in comparison with the stand-alone CFE method

Electronically Tunable Fully-Differential Fractional-Order Low-Pass Filter

The paper presents proposal of a fully- differential (1 + )-order low-pass filter. The order of the filter and its cut-off frequency can be controlled electronically. The filter is proposed using operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs) and fully-differential current follower (FD-CF). The circuit structure is based on well-known Inverse Follow-the-Leader Feedback (IFLF) topology. Design correctness of the proposed filter is supported by PSpice simulations with transistor-level simulation models. The ability of the electronic control of the order has been tested for five individual values of parameter . Furthermore, the ability of the electronic control of the cut-off frequency of the filter has been also tested for five different values. Additionally, the simulation results of the proposed fully-differential (F-D) filter are compared with the results of the single-ended (S-E) equivalent of the presented filter

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters

Dynamical Systems

Complex systems are pervasive in many areas of science integrated in our daily lives. Examples include financial markets, highway transportation networks, telecommunication networks, world and country economies, social networks, immunological systems, living organisms, computational systems and electrical and mechanical structures. Complex systems are often composed of a large number of interconnected and interacting entities, exhibiting much richer global scale dynamics than the properties and behavior of individual entities. Complex systems are studied in many areas of natural sciences, social sciences, engineering and mathematical sciences. This special issue therefore intends to contribute towards the dissemination of the multifaceted concepts in accepted use by the scientific community. We hope readers enjoy this pertinent selection of papers which represents relevant examples of the state of the art in present day research. [...

Modeling the Demand for Electric Vehicles in Canadian Corporate and Government Fleets

This dissertation investigates factors affecting the acquisition of Electric Vehicles (EVs) in the Canadian fleet market. Data from a random sample of over 1,000 fleet operating entities (FOEs) that owned and operated light fleets (i.e., cars, pickup trucks and utility vehicles) in Canadian cities were collected via an online survey titled Canadian Fleet Acquisition Survey (CFAS) in December 2016. The CFAS gathered information about the general characteristics of the surveyed FOEs, their existing fleet characteristics, future acquisition plans and EV fleet prospects. A stated preference (SP) section was introduced in the CFAS to identify the circumstances that will lead to higher adoption rates of EVs for fleet usage. The SP responses were based on six choice scenarios, each featuring four powertrains (Internal-Combustion Engine Vehicles, Hybrid Electric Vehicles, Plug-in Hybrid Electric Vehicles and Battery Electric Vehicles). The CFAS also included attitudinal statements to understand the issues that support or deter EV acquisition in fleets. Chapters 4, 5 and 6 of the dissertation are dedicated to employing various modeling approaches including Exploratory Factor Analysis (EFA), Analytical Hierarchy Process (AHP), and advanced discrete choice models such as Latent Class (LC) and Ordered Logit (OL) models to investigate the feasibility of EVs in fleets from various perspectives. This includes investigating EV adoption with respect to entity type (i.e., corporate vs. government), fleet type (car fleets vs. pickup truck fleets vs. utility vehicles fleets), industry type (transportation and warehousing vs. retail trade) as well as the temporal dimension for fleet electrification (i.e., short run vs. long run). The estimated EFA models identify latent constructs of behavior on various aspects and attitudes relating to EV adoption and provides evidence of attitudinal heterogeneity in the corporate and government FOEs. The AHP approach validates the logical consistency of the attitudinal responses obtained from the sampled FOEs. The four latent classes of FOEs identified in the estimated LC choice model provide novel results regarding the factors that affect acquisition of EVs in fleets. The willingness-to-pay estimates from the LC model reflect the taste variation among the four latent classes for improvements in certain attributes of EVs. The results from the OL modelling exercise successfully explain the behavior governing the acquisition timeframe for battery electric vehicles in the sampled FOEs and highlight the heterogeneity in the factors affecting the acquisition timeframe. Finally, evidence-based policy guidelines are proposed to help stakeholders make informed decisions regarding the acquisition of EVs in fleets. Key guidelines include investment in public charging infrastructure, incentivizing on-site charging infrastructure, engaging FOEs with climate action plan, and harvesting positive attitudes towards fleet electrification through various campaigns. The research work described in this dissertation is the first of its kind to collect and analyze revealed and state preference data on the acquisition of EVs in Canadian fleets including the timeframes under which these vehicles will likely be acquired. The work is seminal as it fills an important gap in the current knowledge about the motivations and preferences towards fleet electrification in Canada