Pumping Conditions Research Articles

Complete characteristic curve processing method based on improved backpropagation neural network and Logarithmic curve projection

The calculation of transient process is the basis of the design and construction of pumped storage power plant, which directly affects operation stability of pumped storage units. However, for satisfying the design of uniform and smooth flow in both directions, the complete characteristic curves of pumped turbine show a significant S feature, which brings difficulties to the interpolation calculation in the transient process as there are crossover and overlap phenomenon in pump and turbine working conditions. In this paper, a transformation method for complete characteristic curves based on logarithmic curve projection and improved backpropagation neural network is presented to solve the above problem. Furthermore, the feasibility and accuracy of the method are verified through the comparison of load rejection condition with on-site measurement, the results show that the proposed method overcomes the multi-value problem that exists in the original curve, in especial makes the small opening region well expressed. The simulation based on the transformed curve reaches a high similarity of transient process with the field test, both in the trend and extreme values, which provides great convenience for the calculation of transient process.

Robust controller design for small pressurized water reactors using non-smooth optimization

The flexible operating conditions of small pressurized water reactors (SPWRs) under parameter uncertainties require highly robust control systems. This paper presents a robust controller design for an SPWR using non-smooth optimization. First, nonlinear mathematical models of the SPWR nuclear steam supply system were adopted and linearized to obtain the corresponding transfer function models. Then, sensitivity analysis of the SPWR physical and thermodynamic parameters was conducted to determine the critical uncertainty parameters for the robust controller design. Subsequently, the reactor power and steam generator feedwater robust control systems were designed under large uncertainties in the identified critical parameters. Finally, simulation studies of typical transients for the SPWR under high- and low-speed operating conditions of the main pump were performed. The results indicate that the designed robust control systems for the SPWR exhibit good performance and excellent robustness under large parameter uncertainties during various load change transients.

PERANCANGAN SISTEM MONITORING DAN KONTROLING POMPA AIR BERBASIS ANDROID

Water is a necessity that is so important for every creature in the world, and the estimate of water must always be available or it is in homes, offices, public places or industry. This causes the water storage tank to play an important role in ensuring the availability of air is always there and under control. In this research, it is based on an Android-based Water Pump Monitoring and Control system with the support of IoT (Internet of Things) technology so that it makes it easier for users to monitor the amount of water in the storage tank and control the water pump to fill water into the tank, the system built is supported by the NodeMCU module. esp8266, Relay and Ultrasonic Sensor and connected to the Blynk application which functions as an application interface in monitoring and controlling the water pump. If the air has determined the specified distance, a notification will appear to immediately turn off the water pump, thus it is hoped that this system can help users see the condition of the water pump and water tank even though they are not at home

Design and Development of an Automatic Prototype Smart Irrigation Model

In the current condition, it is difficult to increase plant development and reduce expenses in agricultural sectors; nevertheless, an advanced thought leads to the use of an automated model that introduces automation in the irrigation system, which can aid in improved water and human resources management. An automated model has been developed using sensors and microcontroller technology, to make the most efficient use of water supply for irrigation. A soil moisture content detector is inserted into the soil of the crops, and an ultrasonic sensor is placed above the soil of the crops to measure the water level after irrigation has begun. A C++ program with threshold values for the moisture sensor was used to start the system in the crop field depending on the soil moisture level, and an ultrasonic sensor was used to control the water in the crop field. The Arduino UNO board is a microcontroller inbuilt of Atmel in the mega AVR family (ATMega328) and the sensors were used to lead the model in turning ON/OFF. A microcontroller was included in this model to run the program by receiving sensor input signals and converting them to soil water content and water level values in the crop field. The microcontroller began by receiving input values, which resulted in an output instructing the relay to turn on the groundwater pump. An LCD screen has also been interfaced with the microcontroller to show the percentage of moisture in the soil, field water level, and pump condition. When the soil moisture level reaches 99 percent and the water level reaches 6 cm after 2.5 and 4 minutes, respectively, the pump is turned off. This model, according to the study, might save water, time, and reduce human effort.

Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine

Hydraulic pumped storage is a special power generation and electricity shortage technology, which is usually operated with thermal power and nuclear power units, and plays a key role in ultra-high voltage and smart grid. Pressure fluctuations are the main reasons for the instability of the S-shaped region of pump–turbines, which seriously affects their lifespan and operation stability. To reveal the mechanism and propagation law of pressure fluctuations in the S-shaped region as well as numerical simulations at the turbine, the braking and the reverse pump operating conditions of a pump–turbine were carried out. Numerical results were validated using the performance experiments, and the generation mechanism and propagation law of pressure fluctuation were analyzed in detail. The analyses show that high-amplitude pressure fluctuations mainly occur in the braking and reverse pump operating conditions. Under the braking condition, a 0.49-fn low-frequency pressure fluctuation was captured, which is caused by the rotation of the backflow in the vanes. Under the reverse pump condition, a 0.19-fn low-frequency pressure fluctuation was confirmed, which is caused by the periodic rotation of the vortex between the vaneless space. This study has important guiding significance for practical engineering application.

Critical dynamics of an asymmetrically bidirectionally pumped optical microresonator

An optical ring resonator with third-order, or Kerr, nonlinearity will exhibit symmetry breaking between the two counterpropagating circulating powers when pumped with sufficient power in both the clockwise and counterclockwise directions. This is due to the effects of self- and cross-phase modulation on the resonance frequencies in the two directions. The critical point of this symmetry breaking exhibits universal behaviors including divergent responsivity to external perturbations, critical slowing down, and scaling invariance. Here we derive a model for the critical dynamics of this system, first for a symmetrically pumped resonator and then for the general case of asymmetric pumping conditions and self- and cross-phase modulation coefficients. This theory not only provides a detailed understanding of the dynamical response of critical-point-enhanced optical gyroscopes and near-field sensors, but is also applicable to nonlinear critical points in a wide range of systems.

Optimization of valve plate applied in secondary unit and noise reduction

Secondary unit, in term of application, is the combination of pump and motor, the valve plate specifically designed for pump or motor may not be suitable for a secondary unit. This paper mainly discusses design of valve plate of secondary unit applied in mobile crane, several critical points needed to be noticed during design have been discussed, furthermore, by adopting the proposed method to optimize a valve plate, which originates from closed-loop pump and now is used in opened-loop system, noise reduction was realized. Firstly, 1D simulation models, including pump condition and motor condition, were established in AMESim to obtain cylinder pressure, flow ripple and other critical parameters; secondly, by using Pumplinx, 3D numerical simulation was conducted to evaluate the cavitation risk; finally, a test bed was set up to validate the simulation result. Simulation result agreed well with the tested one. Both of them verified practicability of the proposed method. This research may provide a guidance for engineers and scholars who are interested in pump and motor.

Chirality-selective easily adjustable spin current from uniaxial antiferromagnets

Spin current generation and injection in antiferromagnetic heterostructures opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Here, we theoretically investigate terahertz spin current in an antiferromagnet (AFM)/normal metal (NM) heterostructure generated by spin pumping. Under the framework of linear response theory, we compute the alternating spin current (ac spin current) inside the NM of the heterostructure arising from the spin pumping of a resonant terahertz magnetic field inside the AFM. An external direct current (dc) magnetic field is also applied to tune the resonance frequency of the AFM, allowing the resonance between terahertz field and AFM to be achieved more easily. In both uniaxial antiferromagnets MnF2 and Cr2O3, we find that once the driving THz field is resonant and circular polarized according to the resonance mode of the AFM, the amplitude of ac spin current is independent of the external magnetic field. On the other hand, in the biaxial antiferromagnet NiO under the same pumping conditions, such a phenomenon is not observed, which can be ascribed to the complicated nondegenerate elliptical chiral mode in biaxial AFMs. More interestingly, for both types of AFMs, we find that the ac component of the spin current increases linearly with the applied terahertz magnetic field distinct from the dc component that increases quadratically. The aforementioned features in uniaxial AFMs provide an easily tunable guideline to optimize the generation of high-frequency spin current by a given terahertz pumping source.

Analysis of causes of failure of the electric centrifugal pump elements by the methods of automated diagnostics

The article discusses the issues of assessing the technical condition of electric centrifugal pumps (ECP) by the methods of automated diagnostics. The factors influencing the ECP and causes of failures of the electric centrifugal pump (ECP) and the submersible electric motor (SEM) are analyzed. The results of ECP failure identifiaton using the measuring systems are presented. Recommendations on the operation of electric centrifugal pumps are provided.

Application of liquid low-temperature cooling in a multi-disk ytterbium laser head under conditions of multi-joule pumping at a high pulse repetition rate

We have investigated the possibility of low-temperature liquid cooling of a multi-disk laser head, as well as the main advantages of this approach. The active zone of the laser head was modelled: the temperature, coolant velocity, inversion, gain, stored energy in the active medium, and thermally induced phase distortions were calculated. It was shown that such cooling can be accomplished with ethyl alcohol; there also are more preferred liquids, which are more difficult in use. The optimal parameters of the active zone were found for using pump pulses with an energy of several J. A significant increase in the gain and stored energy were shown upon cooling from 300 to 200 K, as was a decrease in thermally induced phase distortions.

Effect of Adjusting Balance Hole to Cavitation Area on Cavitation Performance of a Centrifugal Pump

In this study, the cavitation flow field of a centrifugal pump with four different positions of balance holes was studied by experiment and simulation. The results show that: the critical cavitation number decreases first and then increases with the position, the critical cavitation numbers of positions 2, 3 and 4 are smaller than the original model, and the effect of improving cavitation performance is obvious. The input of the high-pressure liquid from the balance cavity increases the absolute pressure of the cavitation area, and changes the pressure gradient in the cavitation area, then the cavitation suppressed. The position of the balance hole has obvious influence on the axial force, positions 2 and 3 reduce the axial force and improve the stress condition of the centrifugal pump, while positions 1 and 4 increase the axial force. It can be concluded that the positions o 2, 3 and 4 can improve the cavitation performance, so the cavitation performance of the centrifugal pump can be significantly improved by setting balance holes along the 2, 3 and 4 lines, also the balance hole should be avoided at position 1.

ANALISA PENYEBAB RUSAKNYA CARGO OIL PUMP GUNA MENUNJANG DISCHARGE CARGO PERTAMAX DI ATASKAPAL MT. PATRA TANKER 2

When discharging the Pertamax cargo at the port at 10:25 a.m. local time, the on-duty engineer received information from the cargo control room that a problem had occurred, the engineer immediately went to the cargo pump room to check the condition of the cargo oil pump. The engineer is see a leak in the pump room which causes the pump room to be full of spills of Pertamax oil transported by the ship. This research is based on a case study on the ship MT. Patra Tanker 2. The data collection method was carried out by direct observation on the ship for one year and then conducted discussions and interviews with the ship's crew responsible for the cargo pump, as well as data from literature such as instruction manuals and standard operational procedures (SOP). The analysis approach was carried out in a descriptive qualitative manner based on data and various literatures used as a reference or comparison. From the results of the analysis it is stated that the cause of the damage to the cargo oil pump is due to the influence of the quality of the mechanical seal that does not meet the standard, the ball bearing is damaged or worn on the cargo oil pump, the ceramic sleeve shaft (bushing) is thinning or worn, and damage to the cargo oil pump shaft. The cause of damage to the cargo oil pump can be avoided by carrying out routine maintenance and controlling it regularly when the cargo oil pump is running.

Evolution of welfare indicators of pigs housed in deep bedding systems during growing and finishing phases: assessment of good health principles and housing conditions

The aim of the study was to monitor the evolution of welfare indicators of pigs throughout growing and finishing phases housed in a deep bedding system by principles of good health and housing. In all, 16,500 animals, distributed in 15 facilities, were evaluated over a 4-month period. Three assessments were carried out in each facility by a single evaluator, according to the following time distribution: phase one (75 to 85days old), phase two (86 to 161days old), and phase three (162 to 180days old). Only the parameters related to good health and good housing were considered. Data were analyzed by logistic regression for longitudinal data. Poisson distribution was used on the coughing and sneezing data, with subsequent chi-square analysis. There were no cases of poor body condition, shivering, panting, huddling, tail biting, pumping, twisted snout, rectal prolapse, lameness, and skin conditions. The final evaluations were associated with greater chances of hernia and bursitis, with greater prevalence in males than in females. The prevalence of wound and manure on the body parameters was influenced by the interaction of the evaluation and animal category. The incidence of coughing and the number of animals presenting this symptom gradually increased, becoming considerably higher in the final stage of evaluation. Health-related problems change throughout the production cycle. The evaluation of a broad and reliable view on animal welfare allows for the most appropriate management of production systems using deep bedding.

Impact of climate change on groundwater levels in Sirhind Canal Tract of Punjab, India

Changing global climate predicts a warmer future which may alter the hydrological cycle, surface water as well as groundwater resource. Groundwater plays an ineradicable role in supplying its water needs to the arid and semi-arid parts of Punjab, region susceptible to the issue of diminishing groundwater resources and the effects of climate change. Thus, a study was performed to simulate the outcomes of the climate change on groundwater levels in Sirhind Canal Tract of Punjab using MODFLOWfor two future time spans, i.e. mid-century (MC) (2020–2050) and end century (EC) (2065–2095) based on CSRIO-Mk 6-CM model, under RCP 4.5 and RCP 6.0 climate scenarios. Two pumping conditions were considered-Condition A assumes that the number of tube wells till EC, would remain same as that of 2018 and Condition B considers that the number of tube wells are expected to increase till 2050, in accordance to the augmenting trend of years 2013–14 to 2017–18. The mean temperature of the tract is predicted to increaseby1.9 °C in MC and 3.6 °C in EC in RCP 4.5, and by 1.6 °C in MC and 3.5 °C in EC in RCP 6.0. The rainfall is also predicted to increase by 17.7 % and 18.2 % under RCP 4.5 and RCP 6.0. The projected change in climate is expected to have positive influence of groundwater recharge with an average increase by 30 % in Condition A and 174 % in Condition B by EC. A fall in water table fall by 5.7 m and 4.3 m by EC under RCP 4.5 and RCP 6.0, respectively for pumping Condition A is predicted, whereas higher fall of 45 m and 57.5 m by EC under RCP 4.5 and RCP 6.0, was predicted for Condition B.

Use of the K-Nearest Neighbour Classifier in Wear Condition Classification of a Positive Displacement Pump.

This paper presents a learning system with a K-nearest neighbour classifier to classify the wear condition of a multi-piston positive displacement pump. The first part reviews current built diagnostic methods and describes typical failures of multi-piston positive displacement pumps and their causes. Next is a description of a diagnostic experiment conducted to acquire a matrix of vibration signals from selected locations in the pump body. The measured signals were subjected to time-frequency analysis. The signal features calculated in the time and frequency domain were grouped in a table according to the wear condition of the pump. The next step was to create classification models of a pump wear condition and assess their accuracy. The selected model, which best met the set criteria for accuracy assessment, was verified with new measurement data. The article ends with a summary.

Operation of quantum dot based terahertz photoconductive antennas under extreme pumping conditions

Photoconductive antennas deposited onto GaAs substrates that incorporate InAs quantum dots have been recently shown to efficiently generate both pulsed and CW terahertz radiation. In this Letter, we determine the operational limits of these antennas and demonstrate their extreme thermal breakdown tolerance. Implanted quantum dots serve as free carrier capture sites, thus acting as lifetime shorteners, similar to defects in low-temperature grown substrates. However, unlike the latter, defect-free quantum-dot structures possess perfect lattice quality, thus not compromising high carrier mobility and pump intensity stealth. Single gap design quantum dot based photoconductive antennas are shown to operate under up to 1 W of average pump power (∼1.6 mJ cm−2 energy density), which is more than 20 times higher than the pumping limit of low-temperature grown GaAs based substrates. Conversion efficiency of the quantum dot based photoconductive antennas does not saturate up to 0.75 W of pump power (∼1.1 mJ cm−2 energy density). Such a thermal tolerance suggests a glowy prospect for the proposed antennas as a perspective candidate for intracavity optical-to-terahertz converters.

Kinematics and geometrical admissibility conditions of balanced vane pumps with twin lip vanes

The present work is devoted to analyze the kinematics of twin lip vanes adopted in balanced vane pumps. The work provides the analytical description of the vane motion according to its geometrical parameters and the cam ring profile. Attention is given to the duality of the solution, an intrinsic property of twin lip vanes that may be considered as followers with two symmetrical half-circular tips. Based on the linkage kinematics, the analytical dissertation is further deepened to define the geometrical admissibility of the vane design and its mathematical domain. In order to evaluate the proposed approach, an extended parametric study is performed on the basis of the Buckingham theorem, detailing how the twin lip configuration affects the machine kinematics. Additional calculations are proposed to determine the vane design configurations that satisfy the fundamental law of cam design and to highlight how this requirement dramatically reduces the subset of available choices in presence of cam ring with a precompression profile. Finally, design guidelines are proposed in order to overcome these drawbacks and expand the admissibility domain.

Frequency response of a continuously tuning narrow-band optical filter based on stimulated Brillouin scattering.

Tunable narrow-band optical filter (TNOF) based on stimulated Brillouin scattering (SBS) has been applied in various applications such as microwave photonics and a high-resolution optical spectrum analyzer (OSA). While the frequency response of a SBS-based filter has always been an important characteristic in the reported studies, few have addressed the issue of the filter response under a continuously tuning condition. When the tuning speed is too fast, the filter response will change and cause spectral distortion. In this paper, the frequency response of SBS-TNOF under a wavelength-swept pump (i.e., continuously tuning) condition is investigated and modeled. Experimental results are in good agreement with the theoretical analysis and verify that the broadening of the SBS-TNOF response is induced by the pump wavelength difference along different positions of the fiber, which can be explained as convolution with broadband pump as well. Based on the widely used Richardson-Lucy deconvolution algorithm and proposed SBS-TNOF response model, the distorted responses are successfully reconstructed and the sweep speed dependency is almost eliminated. Commonly used on-off keying signal is tested using the proposed reconstruction method to assess its performance in the SBS-OSA. Both the overall profile and the detail of the signal spectra are significantly recovered, and the quantitatively evaluation illustrates that the feasible sweep speed can be improved from ∼45 nm/s to over 95 nm/s.

Temperatures Near the Lunar Poles and Their Correlation With Hydrogen Predicted by LEND

AbstractThe lunar polar regions offer permanently shadowed regions (PSRs) representing the only regions which are cold enough for water ice to accumulate on the surface. The Lunar Exploration Neutron Detector (LEND) aboard the Lunar Reconnaissance Orbiter (LRO) has mapped the polar regions for their hydrogen abundance which possibly resides there in the form of water ice. Neutron suppression regions (NSRs) are regions of excessive hydrogen concentrations and were previously identified using LEND data. At each pole, we applied thermal modeling to three NSRs and one unclassified region to evaluate the correlation between hydrogen concentrations and temperatures. Our thermal model delivers temperature estimates for the surface and for 29 layers in the sub‐surface down to 2 m depth. We compared our temperature maps at each layer to LEND neutron suppression maps to reveal the range of depths at which both maps correlate best. As anticipated, we find the three south polar NSRs which are coincident with PSRs in agreement with respective (near)‐surface temperatures that support the accumulation of water ice. Water ice is suspected to be present in the upper ≈19 cm layer of regolith. The three north polar NSRs however lie in non‐PSR areas and are counter‐intuitive as such that most surfaces reach temperatures that are too high for water ice to exist. However, we find that temperatures are cold enough in the shallow sub‐surface and suggest water ice to be present at depths down to ≈35–65 cm. Additionally we find ideal conditions for ice pumping into the sub‐surface at the north polar NSRs. The reported depths are observable by LEND and can, at least in part, explain the existence and shape of the observed hydrogen signal. Although we can substantiate the anticipated correlation between hydrogen abundance and temperature the converse argument cannot be made.

Numerical analysis of gas production laws considering heterogeneous proppant distribution

Hydraulic fracturing is an effective treatment to enhance hydrocarbon recovery, such as shale gas. Proppant distribution is considered to be an important factor affecting fracture conductivity and cumulative gas production. In this paper, proppant flow simulation and gas production simulation were combined to numerically simulate the performance of partially propped fractures. The Eulerian Granular model was applied to simulate proppant migration and deposition in a 100-m-length fracture. The obtained proppant distribution data were extracted, converted, and inputted for gas production simulation in the in-house macroscopic reservoir simulator. The effects of various injection parameters on proppant distribution and cumulative gas production were investigated. Three types of proppant distribution patterns are concluded from dozens of cases with different pumping conditions. It was found that proppant distribution influences cumulative gas production a lot and the production is proportional to the locations of the proppant dune peak. The pressure distributions of the partially propped fracture observed from different views were compared and the influence of heterogeneous proppant distribution on pressure distribution was presented. Thus, combing the proppant flow simulation and gas production simulation can provide a more accurate prediction of pressure distribution and cumulative gas production for the fractured reservoir. Ignoring and simplifying the effects of proppant distribution or dune shapes in the fracture was not recommend. This work will expand the understanding of the difference in cumulative gas production from fractures with different proppant distributions. It helps optimize injection parameters and improve the well performance in the unconventional gas reservoir.