AC Pump Research Articles

Hydroponic System with Integrator Modified on PI Controller for Nutrient and Water Regulation

— This study developed a hydroponic control system to regulate nutrient concentration (PPM) and water volume using a Proportional-Integral (PI) controller. The PI controller was chosen for its simplicity and effectiveness in systems that do not require fast response times. A trial-and-error method was used to tune the Kp and Ki values, which were implemented in an ATMega328 microcontroller. The system consists of one AC pump and two DC pumps: DC Pump-1 controls the PPM by supplying liquid fertilizer, while DC Pump-2 regulates the water volume. The results showed that modifying the PI controller with an integrator limitation improved performance. For PPM control, a limit of 13000 with Kp = 2 and Ki = 0.01 resulted in a 0.5% error, 56.8-second rise time, and a 4.8% overshot. For water level control, a limit of 12000 with Kp = 100 and Ki = 0.16 yielded a 3.25% error, 2% overshot, and a 65.4-second rise time. The test results demonstrated that the use of AB Mix can be reduced by up to 26% compared to a conventional PID, with an initial PPM value of around 350.

Coexistence of Bloch and Parametric Mechanisms of High-Frequency Gain in Doped Superlattices

The detailed theoretical study of high-frequency signal gain, when a probe microwave signal is comparable to the AC pump electric field in a semiconductor superlattice, is presented. We identified conditions under which a doped superlattice biased by both DC and AC fields can generate or amplify high-frequency radiation composed of harmonics, half-harmonics, and fractional harmonics. Physical mechanisms behind the effects are discussed. It is revealed that in a general case, the amplification mechanism in superlattices is determined by the coexistence of both the phase-independent Bloch and phase-dependent parametric gain mechanisms. The interplay and contribution of these gain mechanisms can be adjusted by the sweeping AC pump strength and leveraging a proper phase between the pump and strong probe electric fields. Notably, a transition from the Bloch gain to the parametric gain, often naturally occurring as the amplitude of the amplified signal field grows, can facilitate an effective method of fractional harmonic generation in DC–AC-driven superlattices. The study also uncovers that the pure parametric generation of the fractional harmonics can be initiated via their ignition by switching the DC pump electric field. The findings open a promising avenue for the advancement of new miniature GHz–THz frequency generators, amplifiers, and dividers operating at room temperature.

Reflected Atomic Magnetometer With Single Beam

A reflected atomic magnetometer with single beam is described in this study. A single beam propagates forward for polarizing the atoms and backward for detecting Larmor precession after reflection. The feasibility of the system was studied theoretically and experimentally and compared with the single beam with ellipticity. In reflected scheme, high pump efficiency ensures a reduced power and more flexible operating wavelength considering the AC Stark shift, pump efficiency, and probe signal. The nonuniform optical rotation distribution along the cell was also analyzed. The wavelength of the system was optimized to 795.3 nm. The magnetic field sensitivity of the system is achieved to be 600 fT/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> and the experimental bandwidth was 17 Hz. The compact design enables new possibility of the atomic magnetometer for magnetoencephalography systems.

Techno-economic feasibility of solar water pumping system in North-Gujarat region, India

North Gujarat region of India is predominantly known for agro based economy. As surface water sources are very much limited in these regions, irrigation mainly depends upon underground water strata available at different water table. (Viswanathan, 2014). Close to 80 per cent of the total irrigated area is dominated by deep and shallow tube wells while canal water covers hardly 20 per cent. Gujarat ranked fourth in terms of energization of pump sets over the past three decades, showing more than fivefold increase in the number of pump sets from 2.62 Lakhs during 1983 to 14.28 Lakhs during 2017 and around 3.5 lakh applications are still pending. The agriculture sector in Gujarat utilizes about 27 per cent of the total electricity supplied by Gujarat Urja Vikas Nigam Limited. Contrarily, out of the net revenue generated by GUVNL, only 3 per cent is contributed by the agriculture consumers owing to highly subsidized rate of 60 paisa/kWh. Solar photovoltaic (PV) pumps are powered by an array of solar panels. Solar PV pumps are designed to operate on DC power produced by solar panels, or on existing AC pump with inverter. Solar pumps are easy to install and are generally “good” for the sustainability of boreholes due to their low extraction volumes spread over eight to ten hours a day. To cope up the ever increasing demand, the Gujarat government has provided solar-powered water pumps to farmers to reduce the burden on existing power plants and encourage the farmers to opt for solar powered pumps for their regular irrigation needs. A study on techno economic feasibility of solar water pumping system at farmers fields was carried out during 2015 and 2016 in the North Gujarat region. The study recommended the farmers to adopt 5 hp solar photovoltaic water pumping system coupled with micro irrigation system to promote eco-friendly daytime irrigation. The North Gujarat region is endowed by abundant solar radiation for 300–315 days with insolation of 4.5–6.5 kWh/m2/day. The system is found quite appropriate in the total head range of 5–85 m. Life cycle cost (LCC) of PV system was found to be 58.5 per cent less compared with diesel pump set, average payback period was found to be about 04 years.

Analisis Penyebab Kerusakan Unit Pompa Pendingin AC dan Kompresor menggunakan Metode FMEA

PT. XYZ is a company engaged in the steel industry which produces steel slabs, steel billets, steel plates and steel wires. One of the equipment that often gets damaged is the air conditioning pump and compressor unit in the fluid center service. The results of the availability of the AC and compressor refrigeration pump units show that the availability value is still below the company standards set so that an analysis of the root causes of the problem is needed and finding the best solution to fix existing problems by applying the failure mode and effect analysis (FMEA) method. FMEA is a method that systematically and structurally can analyze and identify the consequences of system and process failures and reduce or analyze the chances of failure. The purpose of this study is to identify and analyze the level of damage and its causes by applying the FMEA method. Based on the Pareto diagram of the damage to the air conditioning pump and compressor engine unit, it was found that the highest frequency of damage was the power supply with a down time percentage of 32.4%. The results of FMEA analysis produce two components that have a very high RPN value which is categorized as potential severity, namely fuse as the first component with an RPN value of 378 and the second is a fuse holder with an RPN value of 252. These two components are the main priority for improvement in the pump engine unit air conditioners and compressors especially for the machine and human aspects.

Study on energy loss of 35 kW all vanadium redox flow battery energy storage system under closed-loop flow strategy

A large all vanadium redox flow battery energy storage system with rated power of 35 kW is built. The flow rate of the system is adjusted by changing the frequency of the AC pump, the energy efficiency, resistance, capacity loss and energy loss of the stack and under each flow rate is analyzed. The energy efficiency of the system is calculated by combining with the pump loss. The results show that with the increase of flow rate, the energy efficiency of the stack is improved and the stack resistance is reduced, but pump loss increases greatly. At 180 mA•cm−2 current density and 110 L/min flow rate, the energy efficiency of the stack reached 77.10% and the system reached 69.49%. In the battery system, the loss of resistance energy accounted for 80.27% of the total energy consumption, and the pipeline and transfer energy loss accounted for 18.73%. Therefore, reducing the energy consumption of the pump and reducing the energy loss of the resistance in the system are very important for improving the energy efficiency of the all vanadium redox flow battery energy storage system.

Operation optimization and costs analysis of the wet desulfurization system in an ultra‐supercritical coal‐fired power plants

AbstractWith the increasingly strict requirements on energy saving and environmental protection, the economical, efficient and environment friendly operation of large coal‐fired units are being more and more critical. In light of the technical problems of massive energy consumption and high cost in the operation of the wet desulfurization system in a 1,000 MW ultra‐supercritical boiler, the effects of slurry circulation pump combination, slurry pH and absorption tower liquid level on desulfurization efficiency under different unit loads were tested, and the total operating costs were calculated. The results showed that the power consumption under different conditions could be greatly reduced by changing the combination of slurry circulation pumps. The power cost increases from 1,059.42 to 1,146.99 yuan/hr as the combination of slurry circulation pump changes from AC pump combination to BD pump combination under 1,000 MW, increased by 7.63%. Considering all factors, the combination of BC circulating pump can effectively reduce the power consumption cost and achieve the optimal economical operation under the load of 1,000 and 750 MW. The desulfurization efficiency is in direct proportion to the increase of slurry pH. The optimal pH of slurry under 1,000 MW is in the range of 5.50–5.60, 4.80–4.90 under 750 MW, and 4.50–4.60 under 500 MW. Besides, the absorption tower liquid level has a significant impact on the energy consumption of desulfurization system. With the decrease of the absorption tower liquid level, the power consumption cost of desulfurization system shows a downward trend. To avoid the frequent adjustment of liquid level which may result in safety accidents, the optimal liquid level of absorption tower is maintained at 8.00–9.00 m under different unit loads. The research results can provide significant guidance for the operation optimization and fine management of the desulfurization system of the same type.

Two-species modeling of electrohydrodynamic pump based on surface dielectric barrier discharge

The electrical and mechanical characteristics of a cylindrical electrohydrodynamic pump are discussed in this paper. The air flow in this pump is produced by the surface dielectric barrier discharge generated between two strip electrodes attached to a hollow dielectric cylinder. The pump characteristics are predicted by simulating the ionized electric field (non-thermal plasma) and the air flow. A quasi-stationary plasma model is approximate and involves two ionic species. However, their full spatial and temporal distributions are calculated by solving the Poisson and charge transport equations using the Finite Element Method. The pump electrical (electric power) and mechanical (body force, velocity distribution, volume flow rate, output mechanical power, efficiency) parameters are presented for different magnitudes of ac voltage, its frequency, pump geometry and operating conditions. Simulations were based on combination of the COMSOL and ANSYS/FLUENT commercial software.

Photovoltaic Pumping System Fed by DC-DC Push Pull Converter

This paper is to design a photovoltaic DC motor pumping system powered by DC-DC push pull converter whose output can be used for irrigation purpose. The charge controller of the system will regulate the output voltage of photovoltaic module and charge the battery. The push-pull type DC-DC converter will increase the battery output voltage and supply the terminal voltage for the DC pump as per the requirement according to the design values. The photovoltaic module is used as a source which converts the light energy received from sun radiation into electrical energy. The produced electrical energy from the photovoltaic is in Direct Current form. So here, the DC pump is used as a load instead of AC pump where the inverter is to be placed which converts the DC into AC. In between the source and load, the charge controller, battery and push-pull type DC-DC converter are connected. The photovoltaic dc pump can be used for low power applications. The motor pump operating under DC power has many advantages than AC pump.

Tuning high-Q nonlinear dynamics in a disordered quantum magnet

Quantum states cohere and interfere. Atoms arranged imperfectly in a solid rarely display these properties. Here we demonstrate an exception in a disordered quantum magnet that divides itself into nearly isolated subsystems. We probe these coherent spin clusters by driving the system nonlinearly and measuring the resulting hole in the linear spectral response. The Fano shape of the hole encodes the incoherent lifetime as well as coherent mixing of the localized excitations. For the Ising magnet LiHo0.045Y0.955F4, the quality factor Q for spectral holes can be as high as 100,000. We tune the dynamics by sweeping the Fano mixing parameter q through zero via the ac pump amplitude as well as a dc transverse field. The zero crossing of q is associated with a dissipationless response at the drive frequency. Identifying localized two-level systems in a dense and disordered magnet advances the search for qubit platforms emerging from strongly interacting, many-body systems.

Anisotropy of the Resonance Transformation of the Microhardness of Crystals after Their Exposure in the EPR Scheme in the Earth’s Magnetic Field

It is shown that the preliminary exposure of ZnO, triglycine sulfate, and potassium hydrogen phthalate crystals in ultralow crossed magnetic fields—Earth’s magnetic field and ac pump field—leads to a resonance change in their microhardness. The resonance frequency of microhardness peaks is determined by the classical condition of electron paramagnetic resonance only at certain orientations of the crystals with respect to the Earth’s magnetic field BEarth. Rotations of all samples with respect to the direction BEarth by angle θ reduce the resonance frequency in proportion to cosθ. The observed anisotropy has been attributed to the presence of their own local magnetic fields Bloc ≫ BEarth in the crystals.

FOPID Controller Based AC Pump Supplied from PV Standalone Source Tuned using Fuzzy Logic Type 2

This paper presents 500 KW three phase standalone photovoltaic systems supplying pumping station consist of four pumps 80 KW rating. The system utilizes a two stage energy conversion power conditioning unit topology composed of a DC-DC boost converter and three level-three phase voltage source inverter (VSI). The Boost converter in this paper is designed to operate in continuous mode and controlled for maximum power point tracking (MPPT). In this paper, the performance of the pumps is improved by adapting the controller of MPPT using different techniques. The system is modeled and studied using MATLAB/Simulink.

Random-Defect Laser: Manipulating Lossy Two-Level Systems to Produce a Circuit with Coherent Gain.

We demonstrate a laser using material defects known for deleterious microwave absorption in quantum computing. These defects are two-level atomic tunneling systems (TSs), which are manipulated using a uniform swept dc electric field and two ac pump fields. The swept field changes the TS energies. TSs first pass through degeneracy with pump photons, which invert (excite) them with a high probability using rapid adiabatic passage. Population inversion is accomplished in spite of a broad distribution of TS parameters. Afterwards the TSs are brought to degeneracy with the resonator where they emit photons. The emission is found to be dependent on individual cavity-TS interactions, and the narrowing linewidth at increasing photon occupancy indicates stimulated emission. Characterization with a microwave probe shows a transition from ordinary defect loss to negligible microwave absorption, and ultimately to coherent amplification. Thus, instead of absorbing microwave energy, the TSs can be tuned to reduce loss and even amplify signals.

Change in the microhardness of nonmagnetic crystals after their exposure to the Earth’s magnetic field and AC pump field in the EPR scheme

Changes in the microhardness of ZnO, triglycine sulfate (TGS), and potassium acid phthalate (KAP) crystals after their exposure to crossed ultralow magnetic fields, i.e., the Earth’s field B Earth ≈ 50 μT and the alternating-current field \(\tilde B \approx 3 \mu {\rm T}\) orthogonal to it, have been revealed. In ZnO crystals, the microhardness increases, whereas in TGS and KAP, it decreases. A maximum change (10–15%) is reached within 1–3 h after magnetic treatment; then, the microhardness gradually recovers to its initial value for the first day. After a sufficient pause, the effect is completely reproduced under the same conditions. The resonant frequency of the pump field \(\tilde B\) corresponds to the EPR condition with a g-factor close to two. The magnetic memory exhibits a strong anisotropy: for each of the crystals, a direction is found, which, being coincident with the Earth’s magnetic field vector B Earth, causes complete or partial suppression of the effect. In ZnO and TGS crystals, these are symmetry axes 6 and 2, respectively. In the KAP crystal, it is the direction in the cleavage plane orthogonal the 2 axis. Possible physical mechanisms of the observed phenomena have been discussed.

Resonant dislocation motions in NaCl crystals under EPR conditions in the Earth’s magnetic field with a radio-frequency pump field

Three resonant peaks l(ν) of dislocation paths, appearing in NaCl crystals under simultaneous exposure to the Earth’s magnetic field B Earth and an ac pump field \(\tilde B\) have been observed in the radio-frequency range (ν ∼ 1 MHz). Each peak corresponds to a specific experimental geometry. Resonance frequencies correspond to ordinary EPR conditions in which, however, instead of the total Earth’s field, its projections onto particular crystallographic directions play part. These directions are probably related to orientations of magnetic moments at impurity centers in dislocation cores. A physical model describing well the positions all three EPR peaks l(ν) is proposed. The peak height l m is proportional to the squared amplitude of the pump field and the time t of sample exposure to crossed fields: \(l_m \propto \tilde B_m^2 t\). The threshold amplitude \(\tilde B_m^{th} \sim 1 \mu {\rm T}\) of the pump field is detected, below which the effect rapidly disappears. The time of spin-lattice relaxation of radical pairs on dislocations is estimated by the threshold field \(\tilde B_m^{th}\) level.

Realization of blood flow signals using MR images of femoral and coronary artery in vitro system

In today's world, research on cardiovascular diseases has increased due to the social losses. Diagnosis and treatment of cardiovascular disorders are necessary to understand the biological and mechanical causes of the diseases. In vitro and in vivo experiments are performed to understand the mechanism of the disease. In in vitro experiments physiological blood flow signals are used to simulate the blood flow inside human body. In this study novel closed-loop flow control system has been developed with control technique and flow control devices to simulate the physiological waveform, unlike studies conducted to date. In vitro experimental system consists of centrifugal pump, pump driver card, solenoid valve, valve driver card, data acquisition card (DAQ), flow meters, in vitro model and sample fluid piping system. The control algorithm is written and run using Matlab/Simulink AC pump and solenoid valves were used to simulate the pulsatile flow in femoral and coronary arteries that they have the high and low flow rates of 25 and 3 ml/s, respectively. In the human body blood flow velocity and geometry of the measurement location can be recorded and visualized by MR imaging techniques. Images of blood flow signal can be transferred to experimental system by providing equivalence of dynamic simulation. For realization of blood flow, Fourier coefficients were obtained from MR blood flow image using image processing techniques and they were used to create flow velocity profile. Using Fourier coefficients femoral and coronary artery blood flow have been realized on the experimental system. Error performance (EP) criterion was developed during the studies to compare human blood flow signal to in vitro experimental blood flow signal. This study is a pioneer in terms of using close-loop control, two flow control devices and EP criteria in in vitro experimental systems. The algorithm developed in this research will be applied to different regions of cardiovascular system for future studies to better understand the cardiovascular diseases and related treatment.

Mathematical modeling of AC electroosmosis in microfluidic and nanofluidic chips using equilibrium and non-equilibrium approaches

AC electroosmotic micropumps are suggested to be powerful tools for electrolyte dosing in various micro- and nanofluidic systems. In this paper, we compare two modeling approaches for studying the AC electroosmosis in the following micro and nanochannel systems: (i) a traveling-wave AC pump with a spatially continuous wave of electric potential applied on a planar boundary, (ii) a traveling-wave AC pump with a wave of electric potential applied on a set of discrete planar electrodes, and (iii) an AC pump with a set of non-planar electrodes. The equilibrium approach is based on the use of capacitor–resistor boundary conditions for electric potential and the slip boundary conditions for velocity at electrode surfaces. The non-equilibrium approach uses the mathematical model based on the Poisson equation and the non-slip boundary conditions. We have observed discrepancies between the predictions given by the both models and then we have identified their possible reasons. The comparison of the equilibrium and non-equilibrium results further showed three important actualities: (a) how the equilibrium model overestimates or underestimates the net velocity, (b) how the velocity maxima in the frequency characteristics can be shifted, if the equilibrium model assumptions are not satisfied, (c) the parametric region where the equilibrium model is applicable. Because the data are obtained in a dimensionless form, they can be exploited for AC electroosmotic studies. We discuss the limitations of the equilibrium and non-equilibrium models and compare selected predictions with available experimental data.

Possible THz Bloch gain in dc–ac-driven superlattices

We study theoretically the feasibility of amplification and generation of THz radiation in dc–ac-driven semiconductor superlattices in the absence of electric domains. We find that if in addition to dc bias strong ac pump fields are applied, Bloch gain profile for a small THz signal can be achieved under conditions of positive static differential conductivity. We briefly review the case of THz pump and present preliminary results on the use of pump fields belonging to the microwave frequency band.

Influence of transient phonon relaxation on the Brillouin loss spectrum of nanosecond pulses

For pump-probe stimulated Brillouin scattering with a probe pulse of a few nanoseconds duration and with a finite DC level, the acoustic wave relaxation time varies with the pump power and the DC level. For a pump power of 1-6 mW, the acoustic wave relaxation changes from approximately 9 to 90 ns for polarization-maintaining fiber at a temperature of -40 degrees C for a 2 ns pulse width. When the pulse DC ratio of the probe varies from 10 to 20 dB, the acoustic relaxation time changes from 24 to 45 ns for single-mode fiber at 25 degrees C. This induces a power-increment spectral feature in the detected AC pump signal in the Brillouin loss spectrum of two temperature or strain sections, where both spectral components appeared at positions far from those related to the natural phonon relaxation time (approximately 10 ns) equivalent length. The theoretical calculations confirm the prolonged phonon relaxation.

Phase-locking in a nonuniform array of tunnel junctions

A nonuniform, one-dimensional tunnel junction array that is designed to promote phase-locking to an ac pump signal is proposed and theoretically investigated for possible information processing applications. The tunnel resistances of the junctions in one part of the array are tailored to provide phase restoration for electrons tunneling in the array, while the tunnel resistances in the other part of the array are designed to provide a time delay with minimal jitter. It is shown that phase-locking of the tunneling is possible at the fundamental and at the one-half subharmonic of the pump frequency. While the required parameter ranges and the necessary degree of control of this design are not practical for tunneling phase logic based on conventional tunnel junction technologies, the proposed design could potentially be realized in a molecular system.