Sizing Directional Pneumatic Valves Based on the Characteristic Dynamic Behavior of Linear Actuators

In this paper, a novel approach to size directional pneumatic valves based on the analysis of the characteristic behavior of pneumatic actuators applied for pick and place tasks is presented. The study evidences the existence of three characteristic times in the displacement of a standard pneumatic actuation system, which are the emptying time, the transient-state time, and the steady-state time. The results also indicate that there is a close correlation between the velocity profile and the relative size of the piston area, where the steady-state time might be negligible when the piston is correctly sized. The emptying time, characterized by the depressurization of the counterpressure chamber, occurs predominantly with choked mass flow rate and constant volume. In this way, an analytical equation to estimate the emptying time has been determined. Moreover, during the transient-state time, the velocity profile is similar to the characteristic behavior of a first order system, therefore, the transient-state time is estimated by the time constant of the system, which was obtained by a linear first order model developed using the fundamental equations that govern the system behavior. The total displacement time, which is a design requirement to size directional valves, can be expressed as the sum of the emptying and transient-state time. Consequently, a set of equations are proposed to size the directional valve using design parameters such as displacement time, piston volume, load force, and supply pressure. The proposed equations were evaluated along with simulation and experimental results, demonstrating their validity and accuracy.

Predicting Stabilized Oil Well Inflow Performance Relationship on Unconventional Reservoir

Unconventional reservoirs are described as any reservoir that requires special recovery operations asides the conventional operating practices. However, low permeability affects the time it requires to attain stability. Presently, most of deliverability test is only carried out in a maximum 24-hour time. Limited test time makes it almost impossible to attain the reservoir stabilization time while carrying out the deliverability test. Meanwhile, to construct Inflow Performance Relationship (IPR) curve, the properties from stabilized time are required. This study aims to discuss how to predict the IPR curve by determining the stabilized flow coefficient value (C) on unconventional reservoir. Furthermore, the stabilized C was used to determine the Inflow Performance Relationship (IPR) for low porosity and permeability reservoir model, also known as Tight Oil Reservoir. The stabilized time and deliverability exponent value need to be determined before the stabilized C value. The stabilized time also know as pseudo-steady state time was evaluated from John Lee and Chaudry equation with validation from the reservoir model. The method proposed by Hashem and Kazemi, which employed the use of transient data in determining the flow coefficient value was also used. In addition, deliverability exponent (n) was determined using an equation proposed by Johnston and Lee. Furthermore, the backpressure equation from Rawlins and Schellhardt was used to construct the IPR curve.

Analisa Peralihan Tanggapan Tegangan Sistem Automatic Voltage Regulator (AVR) Tipe Arus Searah Dengan Pengendali 2 Derjat Kebebasan

This journal discusses the design and analysis of the transfer response of the direct cuurent type of Automatic Voltage Regulator (AVR) system with 2 degrees of freedom controller. Direct current type of the AVR system is represented in the form of transfer function. For 2 degrees of freedom controllers are designed using a parallel architecture with the help of Matlab software using predefined design criteria. The types of controllers used consist of Proportional Differential (PD), Proportional Integral (PI), Proportional Integral Differential (PID), Proportional Differential with First Order Filters in the Differential Section (PDF) and Proportional Intregral Differential with First Order Filters in the Differential Section (PIDF). For the transition analysis, the observed parameters consist of rise time, peak time, steady state time, maximum pass value and peak value. The results of the analysis show that the controller that meets the design criteria is a Proportional Differential (PD) controller with an uptime parameter value of 0.2808 seconds, a peak time of 1.3354 seconds, a steady state time of 0.7017 seconds, a maximum pass of 0% and a peak value of 0.9512. For the Proportional Differential controller with First Order Filter in the Differential Section (PDF) with an increase time parameter value of 0.4177 seconds, a peak time of 1.4684 seconds, a steady state time of 0.8453 seconds, a maximum pass of 0% and a peak value of 0.9502.

Temperature-Dependent Excitonic Photoluminescence and Nonlinear Absorption of CdTe Nanocrystal/Polyvinyl Alcohol Films

The temperature dependence of the excitonic photoluminescence (PL) and nonlinear absorption characteristics of CdTe nanocrystals (NCs)/polyvinyl alcohol (PVA) film are investigated using steady-state/time-resolved PL spectroscopy and Z-scan methods. The excitonic PL peaks of CdTe NCs can be observed at the wavelengths from 560 to 670 nm, with size changes from 2.1 to 3.9 nm. From the temperature-dependent PL spectra, the smaller photon energy of the PL emission peak, the rapidly decreasing PL intensity, and the wider linewidth are observed with increasing temperature from 80 to 300 K. It is revealed that the exciton PL is composed of both trapped state and band-edge excitonic state, which presents biexponential fitting dynamics. The short-lived species is due to the surface-trapped state recombination in NCs, which has a photogenerated trapped channel and a time-resolved peak shift. The species with a long-lived lifetime is ascribed to the intrinsic excitonic recombination. Through the femtosecond Z-scan method, the nonlinear absorption coefficient becomes smaller with the increase in the size of the NCs. The optical properties of the CdTe NC/PVA film show the potential of II-VI traditional NCs as display and luminescent materials that can utilize the combination of exciton PL and nonlinear absorption for expanded functionality.

Fractional order PID controller adaptation for PMSM drive using hybrid grey wolf optimization

In this paper, the closed loop speed controller parameters are optimized for the permanent magnet synchronous motor (PMSM) drive on the basis of the indirect field-oriented control (IFOC) technique. In this derive system under study, the speed and current controllers are implemented using the fractional order proportional, integral, and derivative (FOPID) controlling technique. FOPID is considered as efficient techniques for ripple minimization. The hybrid grey wolf optimizer (HGWO) is applied to obtain the optimal controllers in case of implementing conventional PID as well as FOPID controllers in the derive system. The optimal controller parameters tend to enhance the drive response as ripple content in speed and current, either during steady state time or transient time. The drive system is modeled and tested under various operating condition of load torque and speed. Finally, the performance for PID and FOPID are evaluated and compared within MATLAB/Simulink environment. The results attain the efficacy of the operating performance with the FOPID controller. The result shows a fast response and reduction of ripples in the torque and the current.

Time response of FOPID controlled PV based cascaded landsman converter-inverter fed induction motor and electric drives applications

Time Response enhancement utilizing photovoltaic based cascaded Landsman Converter (LC) structure is one of the soft strategies in the recent scenario. The prime function of a DC-DC Landsman converter is to optimize the output power of the photovoltaic array and reduce the output voltage ripples. This paper reveals the demonstration and simulation of the Cascaded Landsman Converter Inverter System (CLCIS) with a PV source. MATLAB Simulink-model for CLCIS has been created utilizing the components of Simulink and closed-loop examinations are performed with PI and Fractional-Order-PID (FOPID) Controllers. The present work deal with the comparison of transient and steady-state time responses of CLCIS with PI and FOPID controllers. The outcomes demonstrate that dynamic reaction is enhanced by utilizing FOPID controller.

The thermal stability of FAPbBr3 nanocrystals from temperature-dependent photoluminescence and first-principles calculations

The thermal properties of FAPbBr3 perovskite nanocrystals (PNCs) is investigated by use of temperature-dependent steady-state/time-resolved photoluminescence and first-principle calculations.