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This paper provides a redesigned version of the Standard High Gain Observer (SHGO) to cope with the peaking phenomenon occurring during the transient periods as well as the sensitivity to high frequency measurement noise. The observer design is performed for a class of uniformly observable systems with noise free as well as noisy output measurements and the resulting observer is referred to as Non Peaking Filtered High Gain Observer (NPFHGO). The NPFHGO shares the same structure as its underlying SHGO and differs only by its corrective term which is still parameterized by a unique positive scalar up to an appropriate expression involving nested saturations. Of a fundamental interest, the power of the scalar parameter does not exceed one unlike in the case of the SHGO where this power grows from 1 to the system dimension. Moreover, it is shown that the equations of the NPFHGO become identical to those of the SHGO after a transient time horizon that can made arbitrarily small for sufficiently high values of the design parameter. A particular emphasis is put on the case of systems with noisy output measurements. It is shown how a multiple integrator of the corrupted outputs can be cascaded with the original system leading to an augmented system included in the class of systems for which the NPFHGO has been designed. The performance and main properties of the NPFHGO are highlighted and compared to those of its underlying SHGO through simulation results involving a single link robot arm system.

While control design objectives are formulated most commonly in terms of asymptotic behavior (as time goes to infinity) of signals in the closed-loop system, the recently developed notion of “prescribed-time” stabilization considers closed-loop signal behavior over a fixed (prescribed) time interval and addresses the problem of regulating the state to the origin in the prescribed time irrespective of the initial state. While prior results on prescribed-time stabilization considered a chain of integrators with uncertainties matched with the control input (i.e., normal form), we consider here a general class of nonlinear strict-feedback-like systems with state-dependent uncertainties allowed throughout the system dynamics including uncertain parameters (without requirement of any known bounds on the uncertain parameters). Furthermore, we address the output-feedback problem and show that a dynamic observer and controller can be designed based on our dual dynamic high gain scaling based design methodology along with a novel temporal transformation and form of the scaling dynamics with temporal forcing terms to achieve both state estimation and regulation in the prescribed time.

In this article, a single-layer frequency selective surface (FSS)-loaded compact coplanar waveguide (CPW)-fed antenna is proposed for very high-gain and ultra-wideband applications. At the initial stage, a geometrically simple ultra-wideband (UWB) antenna is designed which contains CPW feed lines and a multi-stub-loaded hexagonal patch. The various stubs are inserted to improve the bandwidth of the radiator. The antenna operates at 5–17 GHz and offers 6.5 dBi peak gain. Subsequently, the proposed FSS structure is designed and loaded beneath the proposed UWB antenna to improve bandwidth and enhance gain. The antenna loaded with FSS operates at an ultra-wideband of 3–18 GHz and offers a peak gain of 10.5 dBi. The FSS layer contains 5 × 5 unit cells with a total dimension of 50 mm × 50 mm. The gap between the FSS layer and UWB antenna is 9 mm, which is fixed to obtain maximum gain. The proposed UWB antenna and its results are compared with the fabricated prototype to verify the results. Moreover, the performance parameters such as bandwidth, gain, operational frequency, and the number of FSS layers used in the proposed antenna are compared with existing literature to show the significance of the proposed work. Overall, the proposed antenna is easy to fabricate and has a low profile and simple geometry with a compact size while offering a very wide bandwidth and high gain. Due to all of its performance properties, the proposed antenna system is a strong candidate for upcoming wideband and high-gain applications.

In this paper, a spherical near-field to far-field transformation method (SNFTM) based scattering matrix algorithm (SMA) is presented to predict accurately far-field radiation patterns of electrically large high-gain antennas. The associated simulated and measured results are provided to the accuracy and validity of the SNFTM. It implies that this method makes it possible to calculate complete far-field radiation patterns for electrically large high-gain antennas.

This article proposes a new high-gain transformerless dc/dc boost converter. Although they possess the ability to boost voltage at higher voltage levels, converter switching devices are under low voltage stress. The voltage stress on active switching devices is lower than the output voltage. Therefore, low-rated components are used to implement the converter. The proposed converter can be considered as a promising candidate for PV microconverter applications, where high voltage-gain is required. The principle of operation and the steady-state analysis of the converter in the continuous conduction mode are presented. A hardware prototype for the converter is implemented in the laboratory to prove the concept of operation.

DC-DC boost converters are necessary to extract power from solar panels. The output voltage from these panels is far lower than the utility voltage levels. One of the main functions of the boost converter is to provide a considerable step-up gain to interface the panel to the utility lines. There are several techniques used to boost the low panel voltage. Some of the issues faced by these topologies are a high duty ratio operation, complex design with multiple active switches and discontinuous input current that affects the power drawn from the panel. This paper presents a boost converter topology that combines the advantages of an interleaved structure, a voltage lift capacitor and a passive voltage multiplier network. A mathematical analysis of the proposed converter during its various modes of operation is presented. A 100 W prototype of the proposed converter is designed and tested. The prototype is controlled by a PIC16F18455 microcontroller. The converter is capable of achieving a gain of 10 without operating at extremely high duty ratios. The voltage stress of the switch is far lower than the maximum output voltage.

An ultra-high step-up, non-isolated DC–DC converter with a continuous input current was developed as a result of this research. This converter’s architecture consists of a voltage multiplier cell (VMC), a positive output super lift Luo converter (POSLLC), and a quadratic boost converter (QBS) (also referred to as a cascaded boost topology (CBT)). Thus, the bold points of the topologies mentioned earlier enhance the voltage gain of the proposed topology. It is important to note that when the duty cycle is at 50%, the converter attains a voltage gain of ten. Additionally, the constant input current of the topology reduces the current stress on the input filter capacitor. This converter’s topology was investigated and studied under various operating conditions: ideal and non-ideal modes, as well as continuous and discontinuous current modes (CCM/DCM). The converter’s efficiency and voltage gain were also compared to those of newly proposed converters. PLECS and MATLAB software tools were used in the investigation of the proposed topology. A 200 V/200 W prototype was constructed. The experimental results validated the theoretical study and the simulation results. The extracted efficiency was 91%.

In offshore crane systems, the floating platform motion has a significant impact on the dynamics of the cart motion. Nevertheless, previous studies have ignored the dynamic coupling interaction between the crane and the floating platform induced by changes in hydrostatic, hydrodynamic, and mooring loads affecting the offshore platform-crane system response. To address this problem, this study presents, firstly, a comprehensive model of the crane-platform dynamic coupling under realistic surge-roll-heave motions of the floating platform induced by ocean waves. While the payload motion can be known, the surge-roll-heave motions of the floating platform are considered unknown. Therefore, secondly, we propose an output feedback control approach that combines a state feedback controller and an extended high-gain observer to primarily achieve desired trajectories of the cart motion under unknown payload mass, dynamic friction, dynamic coupling, and external disturbances. The extended high-gain observer uses the measured displacement of the cart to estimate the dynamic states and external disturbances, providing the state feedback controller with the necessary information and increasing the robustness of the control system. The effectiveness of the proposed model-based control approach under unknown dynamic and wave motion disturbances is verified through simulation.

•A new fixed-time filtered extended high-gain observer is developed in the presence of channel noise.•The settling time of the synchronization is preselected in advance uniformly with respect to any initial states. The modulating function based coordinates transformation allows to annihilate the effect of initial conditions on the synchronization process.•Only a single channel with a single signal is used to achieve the synchronization.•Theoretical results are established for both the unfiltered and filtered observers. These results demonstrate the immediate convergence in a predefined-time of observers using the Lyapunov stability theory.•The efficiency of proposed synchronization methods is theoretically and numerically demonstrated in a master-slave based secure communication protocol. Memristor based chaotic oscillators are often chosen for secure communication owing to their interesting feature. In chaos-based secure communication applications, synchronization is a central issue. Most of synchronization methods proposed in the literature are asymptotic. In practice, it is desirable that synchronization be established in a user predefined time. This paper provides new developments in the design of filtered extended high-gain observer dedicated for prescribed-time synchronization of memristor chaotic systems used in a master-slave based secure communication process subject to channel noise. The proposed prescribed-time extended filtered-high gain observer is constructed on the basis of a time-dependent coordinates transformation based on modulating functions which annihilate the effect of initial conditions on the synchronization time. Simulations performed on a numerical example illustrate the efficiency of the proposed approach.

High-voltage and high-frequency stresses comprising of AC and DC components are encountered across the surge arresters at various nodes in HVDC stations. There is a need to generate these stresses to evaluate surge arresters employed at different locations in the HVDC networks. In the present work, an attempt is made to develop complex waveforms using a novel single-stage DC–AC converter. The presented switched-mode converter is based on a coupled inductor which gives an extra degree of freedom to obtain a higher gain with the modulation in the duty ratio. Fixing the turns ratio of the coupled inductor, the duty ratio is appropriately modulated to generate the complex waveform of high frequency and high amplitude. The proposed converter offers a single-stage solution for DC–AC inversion using pulse width modulation, with fewer components, higher power density, and the ability to generate a frequency of 600 Hz. The detailed converter and controller design analysis is discussed in the present investigation. The breakdown operation of the surge arrester demands a massive short-circuit current from the source side, which may be difficult to obtain if a high-gain amplifier is used without proper protection. The presented switched-mode converter-based approach rectifies the issue of the short-circuit current during the insulator breakdown. A simulation study is performed to validate the circuit for both positive and negative buck-boost regions. Further, a hardware setup is developed to verify the generation of high-frequency and high-voltage complex waveforms. The developed converter could be widely used for insulation evaluation and condition monitoring of various high-voltage equipment.