Equivalent PI Research Articles

Model‐free linear active disturbance rejection output feedback control for electro‐hydraulic proportional system with unknown dead‐zone

Here, a model-free linear active disturbance rejection controller (LADRC) integrating dead-zone inverse compensation for an electro-hydraulic proportional (EHP) system with an unknown dead-zone is proposed. Unlike the existing LADRC design idea, the presented method uses a new hydraulic system block diagram to select the order of LADRC instead of the highest degree of the system. Furthermore, the rationality of order selection is illustrated by the frequency domain analysis theory. To solve the dead-zone of the proportional valve, a novel structural transformation is proposed by constructing a new dead-zone, which has a definite physical meaning and can be obtained by the experimental measurement. Then, the dead-zone disturbance is reduced, and the burden of the observer is relieved. At the same time, the controller parameters are decreased from three to two equivalent PI controller. Besides, the stability of the closed-loop system is analysed by the describing function method. The performance of the proposed control solution has been investigated through extensive comparative experiments under different working conditions. The experimental results successfully demonstrate the effectiveness and practicality of the presented method.

Can We Eliminate Opioids After ACL Reconstruction? A Prospective Randomized Controlled Trial

The opioid epidemic has increased concerns about the safety of opioids and the appropriate management of pain with opioid medications creating the need for controlling postoperative pain without narcotics. The purpose of this study was to determine if postsurgical pain following anterior cruciate ligament reconstruction could be managed effectively with a nonnarcotic multimodal analgesic protocol. We performed a prospective study evaluating a novel multimodal non-opioid pain protocol in all patients undergoing anterior cruciate ligament reconstruction from January 2019 to June 2019. Patients were randomized to either a traditional pain protocol consisting of hydrocodone 5 mg/acetaminophen 325 mg or a novel non-opioid pain protocol. The non-opioid pain protocol consisted of preoperative analgesics, intraoperative local infiltration analgesia, and a postoperative pain regimen. Patient VAS pain levels and PROMIS pain interference levels (PI) were reported using a text message service. A total of 26 patients were included. The average age of patients included was 26.9 ± 11.7 years, the average body mass index was 27.5 ± 3.8kg/m2, and 44.0% of the patients were male. Patients on the nonnarcotic protocol had statistically significant improvements (p<0.05) in VAS pain scores at all time points on post-operative days 1-10. There was no difference in PROMIS PI levels among patients administered narcotics (59.1 ± 7.2 vs. 65.6 ± 6.6, p=0.051) and the non-narcotic protocol (58.7 ± 5.8 vs. 57.4 ± 10.5, p= 0.348). The most common side effect of the narcotic pain protocol was constipation (33.0%) and drowsiness (23.5%) for the non-narcotic pain protocol. All patients (100%) were satisfied with their pain management postoperatively. Patients undergoing an anterior cruciate ligament reconstruction with non-narcotic protocol showed improved pain scores, equivalent PROMIS PI scores, and an alternative side-effect profile as compared to traditional narcotic analgesia.

Two-Phase Approach for the Analysis of Laterally Loaded Pile Groups in Sandy Soils

Abstract In this study, a new hybrid method is suggested for the analysis of laterally loaded pile groups in sandy soils. In the proposed method, a pile group is replaced by an equivalent single pi...

In-situ Blockage Monitoring of Sensing Line

Abstract A reactor vessel level monitoring system measures the water level in a reactor during normal operation and abnormal conditions. A drop in the water level can expose nuclear fuel, which may lead to fuel meltdown and radiation spread in accident conditions. A level monitoring system mainly consists of a sensing line and pressure transmitter. Over a period of time boron sediments or other impurities can clog the line which may degrade the accuracy of the monitoring system. The aim of this study is to determine blockage in a sensing line using the energy of the composite signal. An equivalent Pi circuit model is used to simulate blockages in the sensing line and the system's response is examined under different blockage levels. Composite signals obtained from the model and plant's unblocked and blocked channels are decomposed into six levels of details and approximations using a wavelet filter bank. The percentage of energy is calculated at each level for approximations. It is observed that the percentage of energy reduces as the blockage level in the sensing line increases. The results of the model and operational data are well correlated. Thus, in our opinion variation in the energy levels of approximations can be used as an index to determine the presence and degree of blockage in a sensing line.

State control of discrete-time linear systems to be bound in state variables by equality constraints

The paper is concerned with the problem of designing the discrete-time equivalent PI controller to control the discrete-time linear systems in such a way that the closed-loop state variables satisfy the prescribed equality constraints. Since the problem is generally singular, using standard form of the Lyapunov function and a symmetric positive definite slack matrix, the design conditions are proposed in the form of the enhanced Lyapunov inequality. The results, offering the conditions of the control existence and the optimal performance with respect to the prescribed equality constraints for square discrete-time linear systems, are illustrated with the numerical example to note effectiveness and applicability of the considered approach.

Mesh analysis for extracting the S-parameters of lumped element RF and microwave circuits

This paper demonstrates the applicability of basic mesh current circuit analysis techniques, usually learned in the first year of engineering studies, to lumped element RF circuits, which are usually taught with more sophisticated analysis techniques. As an example, the S-parameters of the 90° lumped element hybrid coupler is derived using the traditional mesh current analysis, and compared to that of the distributed micro-strip response. The distributed transmission line coupler is transformed into equivalent lumped element PI sections, and then combined for the resulting lumped element coupler. Mesh current analysis is then utilized to demonstrate the equivalence between the lumped element coupler and the micro-strip coupler as well as the ability to easily simulate the effects of finite inductor Q on the circuit's performance.

Dynamic aggregated building electricity load modeling and simulation

In order to support the growing interest in demand response modeling and analysis, there is a need for physical-based building load models. This work presents a new approach for simulating electrical power flow in buildings. The new approach handles the power flow capacity shortage in existing building simulation programs, which have been used for the past few decades by building energy communities. The suggested approach represents the building as a group of electrical networks, organized in hierarchical levels. On the top level, the user defines key parameters such as rated power and power factor of existing loads. The power cables are modeled by their equivalent PI model. Accurate simulation models are developed for solving the building network equations where building loads are integrated into building network. Smart meters are implemented at different locations for power quality and energy auditing. Two case studies of residential and commercial buildings are investigated to prove the capability of the introduced approach. A comparison with EnergyPlus, as verified building energy software, is introduced to prove the ability of the proposed Matlab-based model to evaluate the annual energy consumption of the building. All results show the accuracy and ability of the proposed approach for simulating the electrical power flow of the building and can be integrated with renewable and storage energy.

On the Fundamental Differences Between Interval Type-2 and Type-1 Fuzzy Logic Controllers

Interval type-2 fuzzy logic controllers (IT2 FLCs) have recently been attracting a lot of research attention. Many reported results have shown that IT2 FLCs are better able to handle uncertainties than their type-1 (T1) counterparts. A challenging question is the following: What are the fundamental differences between IT2 and T1 FLCs? Once the fundamental differences are clear, we can better understand the advantages of IT2 FLCs and, hence, make better use of them. This paper explains two fundamental differences between IT2 and T1 FLCs: 1) Adaptiveness, meaning that the embedded T1 fuzzy sets used to compute the bounds of the type-reduced interval change as input changes; and 2) Novelty, meaning that the upper and lower membership functions of the same IT2 fuzzy set may be used simultaneously in computing each bound of the type-reduced interval. T1 FLCs do not have these properties; thus, a T1 FLC cannot implement the complex control surface of an IT2 FLC given the same rulebase. We also present several methods to visualize and analyze the effects of these two fundamental differences, including the control surface, the P-map, the equivalent generalized T1 fuzzy sets, and the equivalent PI gains. Finally, we examine five alternative type reducers for IT2 FLCs and explain why they do not capture the fundamentals of IT2 FLCs.

Robust fractional order controller for irrigation main canal pools with time-varying dynamical parameters

A new method is proposed with which to design a class of robust fractional order controllers – which we denote as FPI controllers since they can be regarded as a generalization of standard PI controllers – for the effective control of water distribution in irrigation main canal pools characterized by time-varying dynamical parameters. The closed loop behavior of the nominal plant is defined by using frequency specifications, which are combined with an optimization procedure that minimizes the IAE ( Integral of Absolute Error) – a cost related to the closed loop time response specifications – in the whole range of plant parameter variations. Interest in such robust fractional order controllers is justified by the fact that dynamical parameters of irrigation main canal pools may change drastically according to their operational regimes. Equivalent FPI, PI and PID controllers – in the sense of their exhibiting the same closed loop dynamics for the nominal plant specifications – were simulated for several working conditions, and their behaviors were compared. Additional issues, such as noise rejection or robustness to unmodelled high frequency dynamics have also been considered.

Void diagnostics in liquid-filled pressure sensing lines

Air or gas entrapped in liquid-filled sensing lines can result in false pressure readings, sluggish response, and extraneous noise due to acoustic resonances. This work models the impact on the pressure system transfer function of voids inside sensing lines based on an equivalent pi circuit along with a lumped parameter void representation. Field test data from a fossil power plant are used to validate the simulation results. Two void indicators derived from resonant peak frequencies are also introduced to perform sensing line diagnostics.

Equivalent PI Circuit for Zero-sequence Networks of Parallel Transmission Lines

The equivalent PI circuit for single-circuit lines is well established in the literature based on the distributed parameter line model. However, the equivalent circuit for the mutually coupled zero-sequence networks of a double-circuit line has not yet been adequately addressed. This article endeavors to derive the equivalent PI circuit for the zero-sequence networks of a double-circuit line based on the distributed parameter model. The parameters of the equivalent circuits have a closed analytical form in terms of the line parameters in per-unit length. A numerical example is provided to demonstrate the application of the proposed method.

Blockage diagnostics for nuclear power plant pressure transmitter sensing lines

Blockages occur in pressure sensing lines in nuclear power plants due to solidification of boron, sludge, and accumulation of other contaminants. This paper investigates the impact of sensing line blockages on the pressure system transfer function based on an equivalent pi model. For both whole-length and localized blockage scenarios, the first resonant peak tends to shift toward a lower frequency while reducing the peak magnitude. Higher frequency resonant peaks may move to either higher or lower frequencies depending on the blockage type. The lower frequency peaks start to vanish when the impulse line cross-sectional area shrinks. Operational steam pressure noise data from a nuclear power plant are analyzed and are found to compare well to simulation results from the sensing line model. Utilization of the resonant peak frequency and peak interval deviations in the operational data power spectral density is introduced in this paper. This work can be employed to achieve predictive maintenance of sensing lines so that plant operation is not disturbed.

Applying the equivalent pi circuit to the modeling of hydraulic pressurized lines

Pressurized lines, such as water pipelines and hydraulic brake lines, are used for many applications across different industries. Various models focusing on the dynamic pressure behavior of such lines have been developed; however, some representations are either inadequate or difficult to implement. In this paper, existing pressurized line models are first reviewed and a comparison of the relative accuracy among different representations is provided. Moreover, the equivalent pi circuit model developed in electric power engineering is applied to provide an exact representation of a distributed parameter pressurized line. This exact model is compared to multi-lump representations, and its use is demonstrated using examples.

Estimation of transmission line parameters from measurements

This paper describes the method of estimating the transmission line parameters from voltage, current, and power measurements at the two ends of the line. This becomes necessary if a new parallel transmission line is constructed between two substations due to load growth or if an underground cable replaces an overhead line and the overall parameters of the paralleled lines or the cable are desired to be determined. The parameters of the equivalent pi network of the line are obtained from the measurements at the line ends by using the Newton–Raphson method to solve the non-linear equations. The proposed method then gives the resistance/m, inductance/m, and capacitance/m, considering the distributed nature of the transmission line. The technique to determine the conductance parameter is also presented.

Robust Fractional Order PI Controller for a Main Irrigation Canal Pool

A new method is proposed to design a class of robust fractional order PI controller (FPI) based on frequency specifications for water distribution in a main irrigation canal pool. The robustness features of the obtained FPI controller are compared with the ones of an equivalent standard PI controller with the same design frequency specifications. A justification of its enhanced properties it is also provided. The interest of such fractional order controllers is justified by the fact that dynamical parameters of main irrigation canal pools may change drastically in function of its operation regimes. The designed FPI controller was implemented in a PLC of the Siemens company (Simatic 300) and was installed in a real main irrigation canal pool. The real time experimental results carried out comparing both FPI and standard PI controllers for different discharge regimes showed the superiority of the obtained FPI controller over the standard PI controller in terms of time domain performance and robustness. These results proved that the proposed design method leads to an efficient realistic FPI controller for main irrigation canal pools.

Designing PI Controller Based on Iterative Learning Control using Adaptive Technique

This paper presents a technique that can be used in designing an equivalent PI controller to different classes of the known Iterative Learning Control (ILC) namely P-type and high order ILCs. The equivalent PI controller can be explicitly represented in the z domain in contrast to the time domain based ILC, which gives another potential for stability analysis. Moreover, the derived PI controller combines the ease of tuning with the learning feature from past processes, which is the base of Iterative Learning Control (ILC). The results show that the ability of proposed approach to provide an equivalent PI controller that provides similar performances to the ILC when applied to various systems with no restrictions on the system order or type.

PI CONTROLLER DESIGN BASED ON ITERATIVE LEARNING CONTROL

This paper presents a technique that can be used in designing an equivalent PI controller to different classes of the known Iterative Learning Control (ILC) namely P-type and high order ILCs. The equivalent PI controller can be explicitly represented in the z domain in contrast to the time domain based ILC, which gives better potential for stability analysis. Moreover, the derived PI controller combines the ease of tuning with the learning feature from past processes, which is the base of Iterative Learning Control (ILC). The results show that the ability of proposed approach to provide an equivalent PI controller that provides similar performances to the ILC when applied to various systems with no restrictions on the system order or type.

One-Dimensional Photonic Crystal-Based Multichannel Filters Using Binary Phase-Only Sampling Approach

For one-dimensional (1-D) photonic crystals, the amplitude reversal in refractive index profile is defined as an equivalent pi phase shift. With these defined pi phase shifts, the binary phase-only sampling approach can be implemented to design 1-D photonic crystal-based multichannel filters. Such filters exhibit high-count channels and excellent channel uniformity, which is identical with the phenomena obtained in sampled fiber Bragg gratings (SFBGs). Simulations of a nine-channel filter are given out and the distribution of reflection peaks is consistent with that of SFBGs. Then, the impact of structural parameters on filtering characteristics (especially the peak-trough contrast ratio) is discussed, such as optical length of unit cell, optical thickness ratio of alternate dielectric layers, and apodization technique.

The Effect of Training on Preparatory Attention in Older Adults: Evidence for the Role of Uncertainty in Age-Related Preparatory Deficits

Thirty-two older adults and 20 younger adults completed a simple visual detection task in which the preparatory interval (PI; 1, 3, and 5 s) that separates the warning signal from the target varied randomly on each trial. Participants were divided into two groups. In a control condition, participants completed four blocks of trials with the three PIs occurring equally often within a block. In the experimental condition, participants completed an equal probability block (Block 1) followed by two blocks (Blocks 2 and 3) in which the shortest PI (1 s) occurred on 2/3 of the trials, followed again by an equal probability block (Block 4). In Block 1, the results indicated a larger PI effect in older than younger participants, independent of general slowing. Increasing the likelihood of the shortest PI (Blocks 2 and 3 in the experimental condition) improved RT in older and younger adults and led to an equivalent PI effect in both age groups. This was not observed in the control condition, in which the age-related difference persisted during the four blocks of trials. Importantly, the improvement observed in the experimental group was maintained in the fourth block, where the PIs were reverted to an equal probability distribution. This supports the hypothesis that elderly participants prepare for events that have the greatest probability of occurrence and that this is a flexible process that can be modulated with brief training.

An Examination of an Interaction Model between AC and DC Transmission Lines.

In the populated area, parallel running or crossing of AC and DC line may happen. Then there are needs of analyzing the interaction between AC and DC line for the better control and protection. For the demand, the interaction model has to provide capabilities to represent highly accurate DC initialization, dynamics in low frequency as well as higher frequency and excitations at specified frequency including resonance phenomena. This paper concerns the phase domain modeling and presents a modification of frequency characteristics in low frequency band for the accurate DC initialization, newly devised fitting techniques for the modified characteristics which use only real data, and an approximation method which makes the approximation error to be zero at the specific frequency. The examination of the phase domain interaction model constituted by these methods showed the high reliability in DC initialization and dynamic responses. Also the steady state outputs of the model following AC excitation agree well with those of the equivalent pi circuit.