Required Settling Time Research Articles

Demulsification of water-in-oil emulsions applying Fe3O4 magnetic nanoparticles for demulsifier modification: Experimental optimization via response surface methodology

The Water-in-Oil (W/O) emulsions will cause serious problems in the operation, maintenance, and transportation of the petroleum industry. The presence of asphaltenes in crude oil intensifies the stability of this emulsion. In the current study, reusable Fe3O4 magnetic nanoparticles (MNPs) as a modifier for a commercial demulsifier were investigated to improve the demulsification of W/O emulsions with high asphaltenes content (13 wt%). Fe3O4 MNPs have been selected due to low consumption and cytotoxicity, most importantly, synthesis them by a facile and cost-effective electrochemical method. The research was carried out experimentally through bottle test methods and modeling via response surface methodology (RSM). The individual and reciprocal effects of five independent variables of temperature (T), concentration demulsifier (XD), pH, water content (WC), and nanoparticle dosage (ND) were analyzed on the percentage of demulsification efficiency (DE (%)) by a full quadratic polynomial model. The results showed that ND, pH, and WC, out of the ranges of the studied variables, had significant effects on DE (%), respectively. According to the results from statistical analyses, the highest DE (%) was 97.83% in optimal conditions: T of 40 °C, XD of 300 ppm, pH of 6.4, WC of 7.5 ml, and ND of 0.033 gr. Eventually, Fe3O4 MNPs can be reused at least three times successfully. Furthermore, by applying them in addition to the commercial demulsifier, DE (%) could be increased 10%, and the settling time decreased by 6 h. Consequently, the results indicated that the required settling time was significantly less than the conventional chemical demulsification. It reveals the high ability and performance of Fe3O4 MNPs in the W/O demulsification process.

Data-Driven Aggregation Control for Thermoelectric Loads in Demand Response

Within the concept of a smart grid, aggregators have the task of coordinating the behavior of large sets of Distributed Energy Resources, each of them offering small power/energy capacities, which help to balance the power grid and can serve as providers of services. Adequate coordination strategies are required to optimally exploit these resources in the ancillary services market. However, deriving model-based control policies for them is complex due to the heterogeneity and uncertainty related to the large set of associated agents. Then, a data-driven model is an adequate solution for this sort of situation. This paper presents the application of the Youla–Kucera Data-Driven Control strategy for the development of an aggregator to regulate the power consumption of a set of thermoelectric refrigerators, avoiding the modeling process and directly designing a controller from data. A detailed simulation framework was executed to verify the validity of the proposed methodology. It is shown that the derived aggregator is able to offer frequency containment reserves service, achieving the required settling time of 30 seconds and with a tracking error below 4.7%.

Modeling and Phase Synchronization Control of High-Power Wireless Power Transfer System Supplied By Modular Parallel Multi-Inverters

Modular parallel multi-inverters (MPMIs) with master-slave phase synchronization control is proposed for high-power wireless power transfer (WPT) where the MPMI output voltage phase is synchronized to suppress current circulation by compensating for the time delay of the slave inverters caused by signal propagation delay. Different power levels can be conveniently satisfied by flexibly adjusting the number of MPMIs. A modeling method based on the energy-amplitude and phase is developed and linearized to get the slowly changing phase variable and to analyze the system dynamic characteristics at its operating point. To achieve the required dynamic performance of the proposed model, the parameters of a PI controller are obtained by calculating the required settling time and overshoot of the closed-loop dominant poles. A 20.07 kW WPT prototype supplied by three MPMIs with an efficiency of 92.17% was designed and tested. Experimental results show that the proposed modeling method and controller design achieved both good performances of circulating current suppression and MPMIs output voltage phase synchronization.

Regional Pole Placers of Power Systems under Random Failures/Repair Markov Jumps

This paper deals with a discrete-time stochastic control model design for random failure prone and maintenance in a single machine infinite bus (SMIB) system. This model includes the practical values of failure/repair rate of transmission lines and transformers. The probability matrix is, therefore, calculated accordingly. The model considers two extreme modes of operations: the most reliable mode and the least reliable contingency case. This allows the control design which stochastically stabilizes the system under jump Markov disturbances. For adequate transient response, the proposed state feedback power system stabilizer (PSS) achieves a desired settling time and damping ratio by placing the closed-loop poles in a desired region. The control target should also be satisfied for load variations in either mode of operation. A sufficient condition is developed to achieve the control objectives via solving a set of linear matrix inequalities (LMI). Using simulation, the performance of the designed controller is tested for the system that prone to random failure/maintenance under various loading conditions. Simulation results reveal that the closed-loop poles reside within the desired region satisfying the required settling time and damping ratio under the aforementioned disturbances. The contributions of the paper are summarized as follows: (1) modeling of transition probability matrix under Markov Jumps using practical data, (2) designing a controller by compelling the closed poles into the desired region to achieve adequate dynamic performance under different load varying conditions.

A Power-Efficient SAR ADC with Optimized Timing-Redistribution Asynchronous SAR Logic in 40-nm CMOS

This paper presents a power-efficient successive-approximation register (SAR) analog-to-digital converter (ADC) with fast response reference buffer (RV-buffer). Several techniques are applied in the system design to improve the performance of the SAR ADC. A novel timing-redistribution SAR logic is proposed to balance the difference between required settling time for the most significant bit and the least significant bits (LSBs) in the digital-to-analog capacitor array, which reduces the incomplete settling error and releases the requirements on the RV-buffer to achieve lower power dissipation. The SAR ADC is fabricated in 40-nm CMOS technology occupying 0.13 mm $$^{2}$$ area. At 1.1 V supply voltage and 80 MHz sampling frequency, the ADC achieves 50.7 dB SNDR, 69.5 dBc SFDR with a 1 MHz input at −8 dBFS. The total power consumption of the ADC is 2.99 mW, including the reference buffer power consumption of 2 mW. The Schreier FoM is 164.1 dB.

Sensitivity of a physically realizable heliogyro root pitch control system to inherent damping models

The heliogyro solar sail employs high aspect ratio blades that are rigidized by spinning about the central spacecraft, eliminating the need for structural booms typically used to tension traditional square sails. The easily scalable heliogyro gains its maneuverability by actuating the blades at their root with sinusoidal pitch profiles. The blade vibration caused by maneuvering must be attenuated using active control since there is little inherent damping in the blade material. Due to the small root pitch control torques required, on the order of 2 µNm, compared to the large friction torques associated with a root pitch actuator, it has only recently been shown that a single blade heliogyro impedance controller can add damping to the lowest frequency torsional modes of the blade in the presence of modeled actuator friction torques. However, the need to measure blade twist away from the actuator at the root creates a non-collocated control system. Some inherent damping at the blade’s higher frequency modes is therefore needed to stably add damping to the larger-magnitude low-frequency modes, hence control design is sensitive to the accuracy of the blade damping model. Recently, damping characterization tests performed on a small-scale heliogyro blade in a high-vacuum chamber invalidated the assumption of a linear viscous torsional blade damping model that was previously used in blade control designs. This paper describes the formulation of three modal damping models based on the new experimental data and their integration into the single blade heliogyro model. A comparison of the robustness and performance envelopes for the baseline proximal blade twist feedback controller using these damping models shows the ability to meet the required settling time of less than 720 s necessary for a heliogyro technology demonstration mission. This comparison of physically realizable root pitch control systems for a heliogyro blade is critical to increasing the sailcraft to Technology Readiness Level three.

Blood glucose concentration control for type 1 diabetic patients: a multiple‐model strategy

In this study, a multiple-model strategy is evaluated as an alternative closed-loop method for subcutaneous insulin delivery in type 1 diabetes. Non-linearities of the glucose-insulin regulatory system are considered by modelling the system around five different operating points. After conducting some identification experiments in the UVA/Padova metabolic simulator (accepted simulator by the US Food and Drug Administration (FDA)), five transfer functions are obtained for these operating points. Paying attention to some physiological facts, the control objectives such as the required settling time and permissible bounds of overshoots and undershoots are determined for any transfer functions. Then, five PID controllers are tuned to achieve these objectives and a bank of controllers is constructed. To cope with difficulties of the presence of delays in subcutaneous blood glucose (BG) measuring and in administration of insulin, a glucose-dependent setpoint is considered as the desired trajectory for the BG concentration. The performance of the obtained closed-loop glucose-insulin regulatory system is investigated on the in silico adult cohort of the UVA/Padova metabolic simulator. The obtained results show that the proposed multiple-model strategy leads to a closed-loop mechanism with limited hyperglycemia and no severe hypoglycemia.

Ultrasound focuser: A multi-cylindrical source configuration and entrapped particles dynamics

We aim to introduce the proof of concept of a 3D ultrasound Focuser with possible advanced applications in living-matter/cell entrapment, particle focusing, transportation through virtual channel and drug, agent or material delivery systems. The proposed mechanism is assumed to be fully submerged in a fluidic environment and composed of three parallel acoustic line sources which are located in such a way that form a triangular right prism. By approximating the wave field of each cylindrical source as a progressive plane wave field whose amplitude decreases with respect to the travelling distance from the source, the acoustic radiation force exerted on a single particle is analytically derived. It is shown that when each source has a π/3 phase different from other sources, an attracting zone around the axis of the triangular prism is formed for wavelengths in the order of the size scale, λ/l∼O(1), where l denotes the distance between each two sources. The optimal operating situation (the largest attracting zone) is found for the case where λ≈l. The theoretical study is supported by stability analysis of dynamics of the entrapped particle which located on the axis of the prism; and validated by computing the trajectories of migration of the test particle. The stability analysis is performed by considering the unsteady solution of Stokes equations and the possible flow of environmental fluid medium. In addition, the required settling time and required length scales to focus the particle to the center line of the prism for different size scale ratios are estimated and discussed. Compared to other 3D focusing techniques, this method is non-invasive, robust, easy to implement, applicable to nearly all types of micro-particles and does not need any specific pre-designed channel for focusing process.

Wastewater treatment with acoustic separator

Acoustic separation is a filter-free wastewater treatment method based on the forces generated in ultrasonic standing waves. In this report, a batch-system separator based on acoustic separation was demonstrated using a small-scale prototype acoustic separator to remove suspended solids from oil sand process-affected water (OSPW). By applying an acoustic separator to the batch use OSPW treatment, the required settling time, which was the time that the chemical oxygen demand (COD) decreased to the environmental criterion (<200 mg/L), could be shortened from 10 to 1 min. Moreover, for a 10 min settling time, the acoustic separator could reduce the FeCl3 dose as coagulant in OSPW treatment from 500 to 160 mg/L.

Miller Compensation: Optimal Design for Operational Amplifiers with a Required Settling Time

Optimizing the settling response of an operational amplifier can be a serious design issue in today's low-power CMOS technologies. Several design challenges emerge when improving the linear and nonlinear responses of an amplifier. In this paper, we developed a settling model for use in design and optimization of two-stage Miller-compensated amplifiers. Using this model, the closed-form relations between settling time/settling error, gain-bandwidth product, noise, power and stability have been obtained. These relations are employed to form a settling-based design routine for Miller-compensated amplifiers. Simulation results in 0.18- $$\upmu $$ μ m CMOS validate the effectiveness of the proposed routine. In a design prototype, it predicts the settling time with an error less than 3 %. In another design example, the relationship between settling time and gain-bandwidth has been evaluated with an accuracy higher than 95 %. The proposed design routine is used to implement a 40 MS/s sample-and-hold amplifier. It achieves a settling time and signal-to-noise-plus-distortion ratio equal to 12.5 ns and 82 dB, respectively.

Robot control: Tracking with the required settling time

A recently developed concept of the finite-time tracking is studied within the framework of robot control. All the robot non-linearities are incorporated. Finite-time tracking and tracking with the required settling time are defined. The general sufficient conditions for all these tracking features are proved. They provide algorithms for control assuring the special tracking property. Their application to a rotational robot is shown via digital simulation. The simulation results illustrate the theory developed in the paper and show the excellent tracking behaviour of the robot.