Automatic Flow Control Research Articles

Исследование устойчивости автоматической системы регулирования расхода орошения в стабилизационной колонне в процессе каталитического риформинга

It is proposed to take into account the influence of uncontrolled disturbances on the regulation of irrigation flow into the stabilization column of the catalytic reforming unit catalyst stabilization unit by changing the coefficients of the polynomial of the denominator of the transfer function of the automatic irrigation flow control system based on a probabilistic approach to robust stability. To study the robust stability of the automatic irrigation flow control system in the stabilization column, a typical scheme of the regulation system is considered. To describe the problem, a general view of the denominator polynomial of the transfer function of an automatic irrigation flow control system in a stabilization column is obtained. For the robust stability of the automatic irrigation flow control system in the stabilization column under the influence of disturbances, the task of estimating the probability of stability of the family of polynomials of the denominator of the transfer function of the automatic control system is set. A family of polynomials of the denominator of the transfer function of an automatic irrigation flow control system in a stabilization column with uncertainty parameters varying in a cube is considered. The problem of estimating the probability of stability of a family of polynomials of the denominator of the transfer function of an automatic irrigation flow control system in a stabilization column is reduced to solving problems: sample generation and probability estimation by frequency. To assess the probability of stability of the family of polynomials of the denominator of the transfer function of the automatic irrigation flow control system in the stabilization column, four polynomials, including the nominal one, are given. Based on generating a sample of one hundred independent random variables, calculating the corresponding polynomials and checking their stability, the considered family of polynomials of the denominator of the transfer function of the automatic irrigation flow control system in the stabilization column has stability with a probability close to unity.

Nonlinear Transient and Steady State Stretching of Deflated Vesicles in Flow.

Membrane-bound vesicles and organelles exhibit a wide array of nonspherical shapes at equilibrium, including biconcave and tubular morphologies. Despite recent progress, the stretching dynamics of deflated vesicles is not fully understood, particularly far from equilibrium where complex nonspherical shapes undergo large deformations in flow. Here, we directly observe the transient and steady-state nonlinear stretching dynamics of deflated vesicles in extensional flow using a Stokes trap. Automated flow control is used to observe vesicle dynamics over a wide range of flow rates, shape anisotropy, and viscosity contrast. Our results show that deflated vesicle membranes stretch into highly deformed shapes in flow above a critical capillary number Cac1. We further identify a second critical capillary number Cac2, above which vesicle stretch diverges in flow. Vesicles are robust to multiple nonlinear stretch-relax cycles, evidenced by relaxation of dumbbell-shaped vesicles containing thin lipid tethers following flow cessation. An analytical model is developed for vesicle deformation in flow, which enables comparison of nonlinear steady-state stretching results with theories for different reduced volumes. Our results show that the model captures the steady-state stretching of moderately deflated vesicles; however, it underpredicts the steady-state nonlinear stretching of highly deflated vesicles. Overall, these results provide a new understanding of the nonlinear stretching dynamics and membrane mechanics of deflated vesicles in flow.

Automatic Flow Control Valves Solve Raw Water Management Challenges

For all the historical and natural charm of Greenville, S.C., efforts to serve the city's water customers were hampered by raw water management challenges at a nearby reservoir. A new automatic flow control valve provided Greenville Water, City of Greenville Commission of Public Works, with a customized solution.

Intelligent flow control algorithm for microservice system

In microservice systems, availability can be ensured through a variety of measures, such as fault tolerance and flow limiting, which are collectively called the flow control. In the current mainstream system design, the flow control rules are usually fixed and set manually, which cannot be dynamically adjusted according to the flow shape. The performance of the system is thus not fully explored. To mitigate this problem, an adaptive dynamic flow control algorithm is proposed. Based on the system's monitoring data and current flow, the algorithm calculates the flow-limiting threshold in real time, and then it implements fine-grained service adaptive flow control to improve the resource utilization. Experimental results show that the performance of the adaptive automatic flow control is better than that of the traditional static method on resource utilization.

Recent developments in flow modeling and fluid control for paper-based microfluidic biosensors

Over the last 10 years, researchers have shown that paper is a promising substrate for affordable biosensors. The field of paper-microfluidics has evolved rapidly in that time, with simple colorimetric assays giving way to more complex electrochemical devices that can handle multiple samples at a given time. As paper devices become more complex, the ability to precisely control different fluids simultaneously becomes a challenge. Specifically, automated flow control is a necessary attribute to make paper-based devices more useable in resource-limited settings. Flow control strategies on paper are typically developed experimentally through trial-and-error, with little focus on theory. This is because flow behavior in paper is not well understood and sometimes difficult to predict precisely. Additionally, popular theoretical models are too simplistic, making them unsuitable for complex device designs and application conditions. A better understanding of flow theory would allow devices conceived straight from theoretical models. This could save time and resources by reducing experimental work. In this review, we provide an overview of different theoretical models used to characterize imbibition in paper substrates and document the latest flow control strategies that have been applied to automated fluid control on paper. Additionally, we look at current efforts to commercialize paper-based devices along with challenges facing this industry.

An adaptive leak localisation system based on a multi-level analytics framework in piping network

Leak localisation is a growing concern in water distribution system (WDS). The conventional time-correlation analysis incorporates with acoustic sensing is a feasible leak localisation technique in single pipeline system. However, this technique is impractical and time-consuming in a piping network due to multi-directional transmission waves from the leak source. In this paper, we propose an adaptive leak localisation system incorporating a remote-acoustic sensor network and a multi-level analytics framework (MLAF) for piping networks. The MLAF overcomes the multi-directional waves issue in piping networks. The system is adopted with an automated flow control algorithm to ensure time-effective localisation without needs of human supervision. The performance of MLAF has been evaluated based on several emulated piping networks with various network topologies. The characterisation results demonstrated high adaptiveness and location accuracies. The excellent results of field prediction in a local district metered area (DMA) further validated the feasibility of the MLAF.

Automated flow control of a multi-lane swimming chamber for small fishes indicates species-specific sensitivity to experimental protocols.

In fishes, swimming performance is considered an important metric to measure fitness, dispersal and migratory abilities. The swimming performance of individual larval fishes is often integrated into models to make inferences on how environmental parameters affect population-level dynamics (e.g. connectivity). However, little information exists regarding how experimental protocols affect the swimming performance of marine fish larvae. In addition, the technical setups used to measure larval fish swimming performance often lack automation and accurate control of water quality parameters and flow velocity. In this study, we automated the control of multi-lane swimming chambers for small fishes by developing an open-source algorithm. This automation allowed us to execute repeatable flow scenarios and reduce operator interference and inaccuracies in flow velocity typically associated with manual control. Furthermore, we made structural modifications to a prior design to reduce the areas of lower flow velocity. We then validated the flow dynamics of the new chambers using computational fluid dynamics and particle-tracking software. The algorithm provided an accurate alignment between the set and measured flow velocities and we used it to test whether faster critical swimming speed (U crit) protocols (i.e. shorter time intervals and higher velocity increments) would increase U crit of early life stages of two tropical fish species [4-10-mm standard length (SL)]. The U crit of barramundi (Lates calcarifer) and cinnamon anemonefish (Amphiprion melanopus) increased linearly with fish length, but in cinnamon anemonefish, U crit started to decrease upon metamorphosis. Swimming protocols using longer time intervals (more than 2.5 times increase) negatively affected U crit in cinnamon anemonefish but not in barramundi. These species-specific differences in swimming performance highlight the importance of testing suitable U crit protocols prior to experimentation. The automated control of flow velocity will create more accurate and repeatable data on swimming performance of larval fishes. Integrating refined measurements into individual-based models will support future research on the effects of environmental change.

Automated Flow Control System in a Baseline Test Rig for Studying Pulsed Fluid Flows

Automated Flow Control System in a Baseline Test Rig for Studying Pulsed Fluid Flows

The Use of a Microscale Physical Model to Simulate Bankfull Discharge in the Lower Reaches of the Yellow River

Microscale physical models (MSPMs) were once widely used in flood planning in large basins. They fell out of favor but are now being used again. This paper explores the benefits of using such a model for understanding a flood problem on the Lower Yellow River (LYR). We constructed an indoor MSPM of a nearly 800-km reach of the LYR. The model had different scales in the longitudinal, transverse, and vertical directions, and we adjusted the slope of the model. Meanwhile, a real-time water level monitoring system and an automatic flow control system were built on the MSPM to automatically control hydrodynamic testing. Through several discharge experiments, bankfull discharge for multiple MSPM sections was obtained and compared with measured data from the corresponding hydrological section of the prototype during the early flood season of 2016. The comparison demonstrated good linear correlation. The analysis of model similarity showed that although there was some deviation in gravity similarity between the MSPM and the prototype, the model discharge scale derived from resistance similarity adequately described the relationship between the model and the prototype bankfull discharge. Further analysis of the relationship between the model and the prototype bankfull discharge revealed that a split-line line may be better than a single regression line. A MSPM could reproduce the bankfull discharge of the LYR with the nearly 800-km reach in the laboratory which is impossible for a small distortion rate physical model, and obtain a result close to that of the assimilated numerical model.

Cross Interference Minimization and Simultaneous Wireless Power Transfer to Multiple Frequency Loads Using Frequency Bifurcation Approach

Simultaneous power distribution to multiple loads using a single source in the wireless power transfer (WPT) system is a challenging issue due to cross-coupling between the load coils, which reduces the power transfer efficiency. In a resonant WPT system, when two or more coils operated under over coupled condition, the original operating resonant frequency gets bifurcated, and thereby reduction in the power transfer efficiency. Different techniques are investigated in the literature to mitigate the frequency bifurcation phenomena in the resonant WPT system. However, the utilization of frequency bifurcation approach for the simultaneous power transfer to multiple loads is not addressed. This paper proposes a simultaneous power transfer approach using frequency bifurcation for the multiple load system designed with different operating frequency. Mathematical, simulation, and experimental studies performed for dual, triple, and four coil WPT systems with multiple loads. In addition, an automatic power flow control method is implemented to estimate the load current from the source, which helps to select a new set of load coils to be charged. The experimental results confirm the proposed power transfer, helps to attain higher power transfer efficiency of 39.34%, 49.31%, 68.22% and cross interference of −31.2 dBV, −36.2 dBV, −41.2 dBV for dual, triple, and four coil WPT system, respectively.

A paper-based microfluidic platform with shape-memory-polymer-actuated fluid valves for automated multi-step immunoassays

Smart fluid manipulation with automatically controlled paper valves will enable automated and multi-step immunoassays on paper-based microfluidic devices. In this work, we present an integrated paper-based microfluidic platform with shape-memory polymer (SMP)-actuated fluid valves capable of automated colorimetric enzyme-linked immunosorbent assays (ELISAs). A single-layer microfluidic paper-based analytical device (μPAD) was designed to store all the reagents on the chip, and sequentially transfer reagents to a paper test zone following a specific ELISA protocol through automatic fluidic flow control by the multiple SMP-actuated valves. The actuation of a paper valve was based on the thermally responsive, duel-state shape transformation of a SMP sheet attached to the root of a paper cantilever beam for driving a hydrophilic paper bridge to connect and disconnect two paper channels. A portable colorimetric reader was developed to control the on-chip valve operations, quantify the colorimetric signal output, display the assay result, and wirelessly transmit the data to a smart phone for the application of telemedicine. Reliable operations of the paper valve and the entire μPAD were demonstrated with success rates of 97% and 93%, respectively. A detection mechanism for valve malfunction was designed and confirmed effective to identify any mal-operation of individual valves, thus rendering our platform reliable in real assays. For device calibration, we conducted direct ELISAs of rabbit IgG in phosphate-buffered saline (PBS), and achieved a low limit of detection (LOD) of 27 pM (comparable to that of standard and paper-based ELISAs). In order to demonstrate the clinical application of our multi-step immunoassay platform, we also conducted sandwich ELISAs to quantify the protein level of an inflammatory cytokine, namely tumor necrosis factor (TNF)-α, in surgically injured laryngeal tissues of rats. The protein levels of TNF-α were shown similar between the conventional and μPAD ELISAs.

Flow-controlled ventilation during ear, nose and throat surgery: A prospective observational study.

Flow-controlled ventilation (FCV) is a new mechanical ventilation mode that maintains constant flow during inspiration and expiration with standard tidal volumes via cuffed narrow-bore endotracheal tubes. Originating in manually operated 'expiratory ventilation assistance', FCV extends this technique by automatic control of airway flow, monitoring of intratracheal pressure and control of peak inspiratory pressure and end-expiratory pressure. FCV has not yet been described in a clinical study. The aim of this study was to provide an initial assessment of FCV in mechanically ventilated patients undergoing ear, nose and throat surgery and evaluate its potential for future use. An observational study. Two German academic medical centres from 24 November 2017 to 09 January 2018. Consecutive patients (≥ 18 years) scheduled for elective ear, nose and throat surgery. Exclusion criteria were planned laser surgery, intended fibreoptic awake intubation, emergency procedures, increased risk of aspiration, American Society of Anesthesiologists (ASA) physical status more than III and chronic obstructive pulmonary disease classified as GOLD stage more than II. Peri-operative use of FCV provided by a new type of ventilator (Evone) via a narrow-bore endotracheal tube (Tritube). Minute volume, respiratory rate, intratidal tracheal pressure amplitude (Δp) and end-tidal CO2 (PetCO2) were recorded every 5 min. All adverse events were noted. Data are presented as median [IQR]. Sixteen patients provided 15 evaluable data sets. A minute volume of 5.0 [4.4 to 6.4] l min and a respiratory rate of 9 [8 to 11] min generated a PetCO2 of 4.9 [4.8 to 5.0] kPa. Δp was 10 [9 to 12] cmH2O. Five adverse events were recorded: a tube obstruction due to airway secretions and four tube dislocations (two attributed to coughing, two not study-related). FCV achieves adequate PetCO2 levels with minute volume and Δp in the normal range. Tritube's high flow resistance may increase the likelihood of tube dislocations if the patient coughs. Although further evaluation is necessary, FCV provides a new option for short-term mechanical ventilation. The successful operation of FCV with narrow-bore tubes contributes to the armamentarium for airway management. DRKS00013312.

Automated Chemical Sensing Unit Integration for Parallel Optical Interrogation.

We report the integration of an automated chemical optical sensing unit for the parallel interrogation of 12 BICELLs in a sensing chip. The work was accomplished under the European Project Enviguard (FP7-OCEAN-2013-614057) with the aim of demonstrating an optical nano-biosensing unit for the in-situ detection of various chemical pollutants simultaneously in oceanic waters. In this context, we designed an optical sensing chip based on resonant nanopillars (R-NPs) transducers organized in a layout of twelve biophotonic sensing cells (BICELLs). The sensing chip is interrogated in reflection with a 12-channels optical spectrometer equipped with an embedded computer-on-chip performing image processing for the simultaneous acquisition and analysis (resonant mode fitting) of the 12 spectra. A microfluidic chip and an automated flow control system composed of four pumps and a multi-path micro-valve makes it possible to drive different complex protocols. A rack was designed ad-hoc for the integration of all the modules. As a proof of concept, fluids of different refractive index (RI) were flowed in the system in order to measure the time response (sensogram) of the R-NPs under optical reflectance, and assess the sensors’ bulk sensitivity (285.9 ± 16.4 nm/RIU) and Limit of Detection (LoD) (2.95 × 10−6 RIUS). The real-time response under continuous flow of a sensor chip based on R-NP is showed for the first time, obtaining 12 sensograms simultaneously, featuring the unit as a potential excellent multiplexed detection system. These results indicate the high potential of the developed chemical sensing unit to be used for in-situ, multiplex and automatic optical biosensing.

Controlled Solar Powered Irrigation System Based on GSM and Solar Panel

These days, irrigation system are generally utilized in agricultural field to lessen the dependency on rain, the vast majority of irrigation system are either having time based automation or directed manually. In these sorts of system water is applied to field based on fixed timeslots which required high labour for observing and furthermore it decreases the field efficiency. This fixed time slot working prompts over irrigation than the real plant requirement and under irrigation when plants required more water in their peak periods. Fall in crop growth rate, late blooming and decrease of the yield are the main faults caused because of water lack. Besides, over irrigation in the root zones prompts sickness of the root zones and vegetation, extra expense for agriculturist, wasting of water and time wastage. Additionally saltiness of the soil can be increased by ceaseless supply of excess water. For working of irrigation system, power is required. So utilization of sun energy for power generation is necessary to handle current energy crises. The main shortcomings of the fixed panel solar system is that because of rotation of the sun, it can't extract most extreme energy from the sun. Solar power based smart irrigation system are solutions to the Indian farmer. This system comprises of sunlight based water pumps along with an automatic water flow control utilizing a moisture sensor and GSM technology. It is the proposed answer for the present emergency condition for the Indian farmers. This system saves power by decreasing the utilization of grid power and monitors water by lessening water misuses. In GSM mode the farmer at his very own place can send instruction to ON and OFF the water supply through pump without really going to the field.

Non-Energized Above Knee Prosthesis Enabling Stairs Ascending and Descending with Hydraulic Flow Controller

This paper deals with an above-knee prosthesis (AKP) that allows stair ascending/descending with no external energy source. It controls the passive resistance and interlocking strength of the knee and ankle joints with a flow control valve (FCV) equipped with a hydraulic system. The FCV is also mechanically controlled by an automatic flow controller (AFC). Our previous study certified that the experimental AKP allows step-over-step gait in stair ascending and a slight knee flexion at the initial stage of the stance phase in level ground walking, as observed from non-amputees’ walking. However, the experiments showed that the AKP does not allow smooth flexing of the knee in the stance phase during stairs descending because of the improper timing of the AFC opening. This paper shows the total walking performance of the AKP equipped with a refined AFC.

Determination of atmospheric concentration of beryllium-7 at ground level

Atmospheric concentration of beryllium-7 (7Be) at ground level was measured from September 2012 to October 2013 in San Carlos de Bariloche, Argentina, using a HPV-5300AFC brushless, automatic flow control outdoor high volume air sampler for continuous use, and 8”×10” 0.8 microns fiberglass filters. The activity of 7Be was determined on a high-purity germanium (HPGe) detector (relative efficiency 12.3%) by standard gamma spectrometry. The average value found was 4.1 ± 0.1 mBq/m3. Seasonal changes in the atmospheric concentration of 7Be were compared with other environmental variables (temperature, humidity, precipitations, and air kerma rate), and correlation, both positive and negative, was observed as expected. Measurements were carried out following the Radiological Environmental Monitoring Programme at Bariloche Atomic Centre. The aim of the study was to determine atmospheric concentration of 7Be at ground level and to correlate its seasonal changes with environmental variables. Air samplers and environmental dosemeter locations were far away from buildings and any other thing that could influence or alter the measurements. Pearson's correlation coefficient was calculated to evaluate the relation between atmospheric 7Be concentration and environmental variables of interest. These changes in 7Be concentration can be attributed to the variations and dynamic of air exchange between the stratosphere and the troposphere and to the variations of the tropopause height. To fully understand and correctly interpret the meaning of these seasonal variations in the concentrations of atmospheric 7Be, active atmospheric processes must be taken into account. According to the measurements carried out, contribution of 7Be concentration to the natural background radiation dose is negligible.

Development of automatic flow control system for the practice of Ziegler-Nichols and Cohen-Coon control theory

Development of automatic flow control system for the practice of Ziegler-Nichols and Cohen-Coon control theory

Optimal energy flow control strategy for a residential energy local network combined with demand-side management and real-time pricing

Due to the increasing importance of demand-side resources in the energy internet, this paper proposes an optimal energy flow control strategy for a residential energy local network (RELN), which consists of a small number of households, based on the idea of demand-side management. In particular, a type of optimal and dynamic RELN energy consumption scheduling framework is formulated to minimize the daily total operation cost, while fully considering the output forecast error of renewable energy sources (RESs), the consumption preference of users and the status of the energy storage system. In this framework, we provide a unified appliance model to group various types of appliances, which are connected to the network, into a physical model with the same attributes, and a comprehensive real-time pricing mechanism between the RELN and power distribution company (PDC) is developed based on the generalized total load to guide the electricity consumption behavior of the end-users and to also balance the total residential load. On this basis, a mixed integer programming (MIP) model for dynamic energy management optimization of the RELN is optimized at each decision period and integrated into a model predictive control method to reduce the negative impacts of forecast errors of RESs, thereby realizing an optimal and automatic energy flow control for the RELN. Finally, the effectiveness of the proposed RELN energy flow management framework is verified using several case studies.

Intensification of Heat Transport from the Furnace to Heat Accumulator through a Phase Change

In the article the authors analyse the process of heat transport from the furnace to a heat accumulator through a phase change of a heat carrier (working substance), design a construction and describe measurements done on experimental equipment. This type of heat transport is substantially more intense that the one in natural or forced convection and takes place without generating the working substance flow with a drive aggregate. Another advantage is heat accumulation control according to a pre-set temperature of an accumulator through an automatic flow control of the working substance in a condensation phase. The equipment consists of an autonomous evaporation section, a heat accumulator integrated with a condensation heat exchanger and of a thermostatically operated valve with thermal drive.

English

The milking unit sanitization is necessary after use. The processes are usually divided in steps and each one needs water at different temperatures for proper cleaning. However, to get the right temperature for each step cannot be easily achieved manually in rural properties. A hot water and cold water flow are needed. The farmer will need to properly mix the two water flows in order to reach a desired temperature for the cleaning step, and due to temperature fluctuations and flow, a constant intervention is necessary to maintain the same optimal temperature of the mixture. In this work, a mixer with automatic control of cold water flow, coupled to an electric heating system, was developed with the aim of reaching an ideal final temperature required for the sanitation of milking units, regardless of temperature variations and flow at the entrance. Two control boards were compared, the Arduino and the IOIO during the first seconds of operation of the system, the opening angle of the cold water registered is calculated from the hot and cold temperatures. After this gradual adjust in the angle was performed. The temperature was considered to be attained when it reached a maximum deviation of 1°C relative to the desired temperature. The system proved to be slightly more satisfactory with the IOIO, since the desired temperature was stabilized at lower average time, 24 s after system initialization.   Key words: Automation, sanitation, milking unit.