Input Flow Rate Research Articles

Modeling of controlled biological treatment processes in the bioreactor of University of Cape Town

The paper is devoted to the study of processes in the bioreactor with the structural scheme of the University of Cape Town. The ASM1 mathematical model was used to study purification processes. Operating values of recycle flow rates are determined depending on input flow rate required for effective purification of ammonium nitrogen, and a method is proposed to expand the range of control of these values in combination with regulation of oxygen supply to the aerobic zone of the reactor. The specific role of the aerobic zone in the UCT reactor having a key role and affecting both nitrification and denitrification due to nitrate recycling is shown.

Studies on fluorine-based impurity production in Triple-GEM detectors operated with C[formula omitted]-based gas mixture

One of the primary elements influencing gaseous detector operation is the purity of the gas mixture. Its quality can be undermined by the presence of impurities, already present in the supply gas bottles or that could be created in the gas system or from the detector itself. Gaseous detectors operated with Freon-based gas mixtures are subject to the formation of the products of gas molecules break up, occurring when the gas is exposed to high-rate radiation, and enhanced by the presence of high electric field. The release of highly reactive products could be critical as they could either create polymerized deposits or cause material etching, that could compromise detector performance and accelerate aging processes. Moreover, the operation of gas systems with gas recirculation, nowadays common in many gas systems, could worsen the risk of damage due to possible impurities accumulation. This work focuses on the production of fluorine-based impurities in Triple-GEMs detectors operated with CF4-based gas mixture. Detectors are operated in a LHC-like gas system and exposed to high-rate gamma irradiation thanks to the intense 137Cs source provided by the CERN Gamma Irradiation Facility (GIF++). Impurity production is characterized for different detector operation conditions such as gas mixture, working voltage, input flow rate, and irradiation rates. Furthermore, purifier module operation is validated proving its efficiency in removing Fluoride impurities.

Examination of the dominant factor affecting the mixing in the microchannel

The effect of the input flowrate ratio and the Reynolds numbers in range from 10 to 300 on the mixing of liquids in a T-type micromixer was examined. Linear trends of mixing efficiency change on the ratio of input flowrates and Reynolds number are approximated. The most effective mixing (the mixing coefficient reaches 0.86) was obtained at Reynolds numbers 186 and 300 and the input flowrate ratio R = 1. It is determined that with equal input flowrate ratio, as the Reynolds number increases from 10 to 300, the mixing efficiency rises sharply: from 0.2 to 0.8 (for 0.5 < R < 1). Variation of the ratio of input flowrates at low Reynolds numbers in the range from 10 to 120 can lead to a significant increase in the mixing of liquids (Re = 47, the growth mixing from 0.22 to 0.67). With Reynolds numbers 186 and 300, as the input flowrate ratio increases from 0.1 to 1, the mixing ratio rises from 0.25–0.30 to 0.85–0.90.

Effective practical removal of acetaldehyde by a sandwich-type plasma-in-honeycomb reactor under surrounding ambient conditions

The effective removal of acetaldehyde by humidified air plasma was investigated with a high throughput of contaminated gas in a sandwiched honeycomb catalyst reactor at surrounding ambient temperature. Here, acetaldehyde at the level of a few ppm was successfully oxidized by the honeycomb plasma discharge despite the harsh condition of large water content in the feed gas. The conversion rate of acetaldehyde increased significantly with the presence of catalysts coating on the surface channels. The increased conversion rate was also obtained with a high specific energy input (SEI) and total flow rate. Interestingly, the conversion changed negligibly under the acetaldehyde concentration range from 5 to 20 ppm. However, the conversion rate decreased toward increased water amount in the feed gas. Notably, about 60% of acetaldehyde in the feed was oxidized under SEI of 40 J/L at water amounts ≤ 2.5%, approximately 0.5 g/kWh for acetaldehyde removal. Also, the plasma-catalyst reaction was superior to the thermal reactive catalyst for acetaldehyde removal in airborne pollutants. In comparison with other plasma-catalyst sources for acetaldehyde removal, the energy efficiency under the condition is comparable. Moreover, the honeycomb plasma discharge features high throughput, avoiding pressure drop, and straightforward reactor configuration, suggesting potential practical applications.

Evaluation of challenges and limitations of mechanical thrombectomy using 3D printed neurovascular phantoms.

The mechanical thrombectomy (MT) efficacy, for large vessel occlusion (LVO) treatment in patients with stroke, could be improved if better teaching and practicing surgical tools were available. We propose a novel approach that uses 3D printing (3DP) to generate patient anatomical vascular variants for simulation of diverse clinical scenarios of LVO treated with MT. 3DP phantoms were connected to a flow loop with physiologically relevant flow conditions, including input flow rate and fluid temperature. A simulated blood clot was introduced into the model and placed in the Middle Cerebral Artery region. Clot location, composition (hard or soft clot), length, and arterial angulation were varied and MTs were simulated using stent retrievers. Device placement relative to the clot and the outcome of the thrombectomy were recorded for each situation. Angiograms were captured before and after LVO simulation and after the MT. Recanalization outcome was evaluated using the Thrombolysis in Cerebral Infarction (TICI) scale. Forty-two 3DP neurovascular phantom benchtop experiments were performed. Clot mechanical properties, hard versus soft, had the highest impact on the MT outcome, with 18/42 proving to be successful with full or partial clot retrieval. Other factors such as device manufacturer and the tortuosity of the 3DP model correlated weakly with the MT outcome. We demonstrated that 3DP can become a comprehensive tool for teaching and practicing various surgical procedures for MT in LVO patients. This platform can help vascular surgeons understand the endovascular devices limitations and patient vascular geometry challenges, to allow surgical approach optimization.

A study on 6063aa elliptical and semi-circular cross-section tpct with fe3o4 nano fluid

Thermosyphon is the most preferred device to transfer heat for it costs low, requires comparatively low maintenance, besides being adaptable to any size. The ship transfer characteristics in this cooling system get enhanced by the use of the working fluid this paper deals with the elliptical and semicircular Two-Phase Closed Thermosyphon (TPCT) range of efficiency when it is added with Fe3O4 nanofluid. A number of tests are conducted with elliptical and semicircular TPCT with Fe3O4 with the inevitable input parameters such as heat input, inclination and pure water flow rate to obtain the output result of efficiency. The results of the experiments with thermosyphons proved the fact that the thermal performance has improved with the incorporation of elliptical TPCT combined with Fe3O4 Nano.

Lyapunov Stability of Periodic Control on a Continuous Stirred Tank Reactor

Abstract Periodic control uses zero mean parametric excitation as a tool to influence the transient behavior of a dynamical system. Unlike conventional methods, based on feedback or feedforward principles, the method of periodic control may not require any measurement of the deviations or disturbances to stabilize an unstable system. The choice of amplitude and frequency in periodic control provides two additional degrees of freedom to stabilize an open-loop system. Stability analysis of periodically forced systems is often limited to linearization methods. This is often not sufficient to assess the global properties of a non-linear system like finding the region of convergence. In this paper, forced oscillations are introduced in the input flow rates of a continuous stirred-tank reactor (CSTR) to operate the process around an unstable point. We use Lyapunov analysis to demonstrate the exponential stability of a CSTR system under the operation of periodic control. For exponentially convergent systems, we derive a theorem to estimate the region of convergence and show that the rate of convergence for a system under weak oscillations is almost the same as that of its averaged system. Numerical simulations of a propylene glycol process are carried out to illustrate the exponential stability of periodic control and verify the results of our analysis.

Roman Hydraulic Engineering: The Pont du Gard Aqueduct and Nemausus (Nîmes) Castellum

The water distribution castellum at the terminal end of the Pont du Gard aqueduct serving the Roman city of Nemausus in southern France is analyzed for its water engineering design and operation. By the use of modern hydraulic engineering analysis methods applied to analyze the castellum, new aspects of Roman water engineering technology are discovered not previously reported in the archaeological literature. Analysis of the castellum’s 10 basin wall flow distribution pipelines reveals that when a Roman version of modern critical flow theory is utilized in their design, the 10 pipelines optimally transfer water to city precincts at the maximum flow rate possible with a total flow rate closely approximating the input flow rate from the aqueduct. The castellum’s three drainage floor ports serve as additional fine-tuning to precisely match the input aqueduct flow rate to the optimized 10 pipeline output flow rate. The castellum’s many hydraulic engineering features provide a combination of advanced water engineering technology to optimize the performance of the water distribution system while at the same time enhancing the castellum’s aesthetic water display features typical of Roman values. While extensive descriptive archaeological literature exists on Roman achievements related to their water systems both in Rome and its provinces, what is missing is the preliminary engineering knowledge base that underlies many of their water system’s designs. The present paper is designed to provide this missing link by utilizing modern hydraulic engineering methodologies to uncover the basis of Roman civil engineering practice—albeit in Roman formats yet to be discovered.

A disposable smart microfluidic platform integrated with on-chip flow sensors

Microfluidic devices are powerful tools for biological, biomedical, chemical, and pharmaceutical applications, but their commercialization is still hindered by the lack of methods to automatically control fluid flow in a low-cost, simple, accurate, and safe manner. This study introduces a disposable smart microfluidic platform (DIS-μChip), which can be fully automated and utilized for a wide range of applications. On-chip microfluidic flow sensors are integrated with the platform and placed at all inlet and outlet channels, thereby allowing the DIS-μChip to be fully automated with a pressure control system. Furthermore, these confer a self-diagnosis function through monitoring of all the input and output flow rates. The DIS-μChip consists of a disposable polymeric microchannel superstrate and a permanent multifunctional substrate, which could be assembled and disassembled using only vacuum pressure. The superstrate was fabricated by combining a polydimethylsiloxane microchannel structure with a polyethylene terephthalate (PET) thin film. The substrate contains sense electrodes for the on-chip-integrated flow sensors and functional components for creating an energy field, which can penetrate the PET thin film and manipulate the fluid in the microchannels of the superstrate. Owing to the film-chip technique, the superstrate was disposable and could prevent biological cross-contamination, which cannot be realized with conventional flow sensors. The usefulness of the DIS-μChip was demonstrated by using it to isolate circulating tumor cells from the blood of patients with pancreatic cancer and to obtain cancer-specific genetic information from them with droplet digital PCR.

Feedforward boundary control of 2[formula omitted]2 nonlinear hyperbolic systems with application to Saint-Venant equations

Because they represent physical systems with propagation delays, hyperbolic systems are well suited for feedforward control. This is especially true when the delay between a disturbance and the output is larger than the control delay. In this paper, we address the design of feedforward controllers for a general class of 2×2 hyperbolic systems with a single disturbance input located at one boundary and a single control actuation at the other boundary. The goal is to design a feedforward control that makes the system output insensitive to the measured disturbance input. We show that, for this class of systems, there exists an efficient ideal feedforward controller which is causal and stable. The problem is first stated and studied in the frequency domain for a simple linear system. Then, our main contribution is to show how the theory can be extended, in the time domain, to general nonlinear hyperbolic systems. The method is illustrated with an application to the control of an open channel represented by Saint-Venant equations where the objective is to make the output water level insensitive to the variations of the input flow rate. Finally, we address a more complex application to a cascade of pools where a blind application of perfect feedforward control can lead to detrimental oscillations. A pragmatic way of modifying the control law to solve this problem is proposed and validated with a simulation experiment.

Parametric optimization for better thermal performance on Heat Pipe using Taguchi method

Heat pipes are hollow cylindrical form devices filled with a small amount of operational fluid and are used to transfer heat, which alters its phase. In contrast to standard heat exchange systems, the heat transfer rate in heat pipes is higher. Different heat pipes are being built depending on the heat transfer applications. The aim of the current work is to optimize the process parameters of heat pipe using Taguchi technique. The control factors like heat input (Q), inclination angle (θ), fill ratio (ϕ) and mass flow rate (M) were considered to evaluate the thermal performance in terms of thermal resistance and thermal conductivity. Using a L9 orthogonal array, a total of nine experimental runs were performed and the optimal combination of control parameter levels for the responses was calculated. The Taguchi technique is utilized by using MiniTab-17 software to find the level of importance and optimal independent parameter for the cylindrical mesh wick heat pipe using DI-water as the working fluid.

Voltage Control for a Polymer Electrolyte Fuel Cell System By Model Predictive Control Controller

Due to its high power density, fast start up ability, low operating temperature, noiseless and environmental friendliness, polymer electrolyte fuel cells (PEFCs) have been regarded as the most promising alternative power sources for a variety of applications, such as transportation system, domestic system, stationary system and so on. Stable and effective control strategy is essential for the efficient and safe operation of PEFC systems. Voltage control is always a research hotspot in PEFCs’ control study. When using a PEFC system to supply power in a real application, it is of great significance to maintain a stable output voltage to avoid an adverse voltage drop under sudden load change, which can reduce the maintenance costs of the PEFC generation system. The output voltage of the PEFC system can be easily affected by the inlet flow rate of the reactant gas, i.e., the reactions inside the fuel cell system will be more sufficient with higher input flow rate of the reactant gas to produce higher electrical voltage, otherwise, less electrical voltage is generated. Therefore, the focus of this study is to control the output voltage of a PEFC system by regulating its hydrogen and air flow rates, which stands for a multi input and single output control problem.Model predictive control (MPC) is an advanced method of process control with stronger robustness and faster response compared with conventional controllers. Its main advantage is that it allows the current timeslot to be optimized while keeping future timeslots in account. Moreover, the MPC is rather suitable for solving systems with constraints, which makes a good choice for the voltage control of the PEFC system since the fuel cell system is a complicated nonlinear and strongly coupled system, with many constraints that need to be considered to ensure the coordination and balance between every subsystem.The first part of this study is to develop a PEFC system dynamic model, which is based on the NedStack PS6 of 6kW rated power. Its polarization behavior based on different reactant flowrates are evaluated. Then based on the developed model, a novel MPC controller is designed to control the PEFC system’s output voltage at 48V, assuming that the PEFC system can be an alternative power source for an electric bicycle with 48 V by regulating the input hydrogen and air flow rates. The following figure gives an overview of the voltage control of the PEFC system. It can be seen the input of the MPC controller contains the reference stack voltage, the state vector, the actual stack voltage and the current. It should be noted that the current is the our test signal. Figure 1

OPTIMIZATION OF PROCESS PARAMETERS IN LASER WELDING OF HASTELLOY C-276 USING ARTIFICIAL NEURAL NETWORK AND GENETIC ALGORITHM

In this paper, an effort is made to determine the optimized parameters in laser welding of Hastelloy C-276 using Artificial Neural Network (ANN) and Genetic Algorithm (GA). CO2 Laser welding was performed on a sheet of thickness 1.6[Formula: see text]mm based on Taguchi L27 orthogonal array. Laser power, welding speed and shielding gas flow rate were chosen as input parameters and Bead width, depth of Penetration and Microhardness were measured for assessing the weld quality. ANN was applied for modeling the welding process parameters i.e. heat input, welding speed and gas flow rate. Various learning algorithms such as Batch Back Propagation (BBP), Incremental Back Propagation (IBP), Quick Propagation (QP) and Levenberg–Marquardt (LM) were comprehensively tested for estimating the output parameters and a comparison was also made among them, with respect to prediction accuracy. BBP method was found to be the best learning algorithm. Experimental validation test was performed based on the ANN and GA predicted optimized responses and this welding input parameters provided satisfactory weld metal characteristics in terms of penetration depth, bead width and microhardness.

Experimental Analysis and Characterization of High-Purity Aluminum Nanoparticles (Al-NPs) by Electromagnetic Levitation Gas Condensation (ELGC).

The production of high-purity aluminum nanoparticles (Al-NPs) is challenging due to the highly reactive nature of Al metals. Electromagnetic levitation gas condensation (ELGC) is a promising method to produce high-purity metallic particles as it avoids the interaction between molten metal and refractory-lined, which guarantees the removal of impurities such as oxygen (O). In this research, high-purity Al-NPs were successfully fabricated via ELGC process and fully characterized. The effects of power input and gas flow rate on particle size and distribution were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and dynamic light scattering (DLS). The results showed that the Al-NPs have spherical morphologies with an average diameter of 17 nm and size distribution of NPs is narrow under helium (He) flow rate of 15 L/min at a constant temperature of 1683 ± 10 K. The purity of the NPs was confirmed by utilizing X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and X-ray fluorescence (XRF). Finally, metal purity of 99.976% and 99.97% was measured by AAS and XRF analyses, respectively. Moreover, it was found that increasing gas flow rate and sample temperature results in a decrease in the particle size. The particle sizes for the Al-NPs obtained under He atmosphere were smaller than those obtained under Ar atmosphere.

Proportional–integral‐like fuzzy controller of a small‐scale linear fresnel reflector solar plant

This study reports on the development and implementation of the fuzzy incremental controller on a small-scale linear fresnel reflector solar plant. The control problem is concerned with forcing the output temperature to follow the reference, despite the existence of disturbances. Owing to the non-linear effects of solar plants, the capability of fixed parameters of the proportional–integral controller to cope with the control problem is limited and leads to unsatisfactory control performance. The proposed controller is a modification to a conventional proportional–integral algorithm with better tuning flexibility. Firstly, the ant colony optimisation algorithm is used to define the optimal parameter of proportional–integral plus series feed-forward controller while guaranteeing a satisfactory performance of the plant. Secondly, the resulting controller is replaced with an equivalent fuzzy knowledge-based controller with the error and change of error of the plant as the input variables and flow rate as an output variable. The proposed controller is tested on a quasi-dynamic model of linear fresnel reflector plant using conventional and renewable energy optimisation toolbox in the environment of MATLAB/Simulink. The controller's performance is compared to the proportional–integral controller, where its effectiveness is evaluated under nominal conditions, measurement delay, noise, and presence of disturbance.

EXPERIMENTAL INVESTIGATION OF AN ALUMINIUM THERMOSYPHON AT NORMAL OPERATING CONDITIONS

The paper presents experimental investigation of an aluminium thermosyphon charged with acetone as working fluid. The effect of filling ratio on steady state performance of thermosyphon is experimentally investigated. Experimentation is performed at three different ratios namely 30 %, 60 % and 100 %. The effect of heat input and mass flow rate of water is also investigated. The heat input is varied between 50 to 300 W and mass flow rate is maintained in the range 30 lph to 60 lph. A condenser section of thermosyphon is surrounded by two pass aluminium cooling block for effective condensation. The cooling block is design in such a way that water will absorbs maximum heat from working fluid in condenser section. The temperature at outer surface of thermosyphon is recorded with the help of temperature sensors. The temperature distribution at outer surface of evaporator and condenser observed to be almost uniform for all mass flow rates and filling ratios. The heat transfer limitations are not encountered for any of thermosyphon. The filling ratio has significant effect on outer surface temperature of evaporator. The surface temperature of evaporator increases by 20 % with increasing the filling ratio at 150 W heat input and 30 lph mass flow rate. The results also indicate that mass flow of cooling water has significant effect on total thermal resistance of thermosyphon at lower input. For 50 W heat input, minimum thermal resistance is recorded as 0.269 °C/W at 60 % filling ratio and 50 lph mass flow rate. While for a same heat input, maximum thermal resistance is recorded as 1.077 °C/W at 100 % filling ratio and 60 lph mass flow rate.

Increasing the dilution rate can globally stabilize two-step biological systems

We revisit two-step mass-balance models of biological processes as met to describe numerous biological systems including the anaerobic digestion or the nitrification process in view of its global stabilization. We show that when a bi-stability occurs, it can be possible to globally stabilize the dynamics toward an unique positive equilibrium by increasing the dilution rate. We give sufficient conditions on the growth functions of the model for this situation to appear. This illustrates that for biological multi-step reactional systems, increasing the residence time (e.g. decreasing the input flow rate) may not be the only way to stabilize the dynamics.

Influence Assessment of Intelligent Unmanned Ground Vehicles on the Transport Network State

This article is devoted to econometric analysis of the results of experiments conducted with two agent-based models, which describe the movement of ground vehicles. There are two types of road users in these models: manned ground vehicles (MGV) and unmanned ground vehicles (UGV). In the first model, the main difference between UGV and MGV is an ability to exchange massages between UGV for transmitting information about extreme situations, which allows them to adjust speed and direction of movement. In the second model, in addition to the above differences, UGV have an additional advantage, namely, the ability to intelligently assess density of traffic flow for efficient maneuvering. In these models, at a given roundabout, traffic characteristics such as output stream traffic and the number of traffic accidents are analyzed. The main task of the econometric analysis is to study dependence of these traffic characteristics on the model parameters such as average vehicle speed, input flow rate, message exchange rate between UGV, and the impact of the effect obtained from the implementation into UGV ability of intelligent estimation of traffic flow density.

The role of heterogeneous catalysts in the plasma-catalytic ammonia synthesis

Ammonia, being the second largest produced industrial chemical, is used as a raw material for many chemicals. Besides, there is a growing interest in the applications of ammonia as electrical energy storage chemical, as fuel, and in selective catalytic reduction of NOx. These applications demand on-site distributed ammonia production under mild process conditions. In this paper, we investigated 16 different transition metal and oxide catalysts supported on γ-Al2O3 for plasma-catalytic ammonia production in a dielectric barrier discharge (DBD) reactor. This paper discusses the influence of the feed ratio (N2/H2), specific energy input, reaction temperature, metal loading, and gas flow rates on the yield and energy efficiency of ammonia production. The optimum N2/H2 feed flow ratio was either 1 or 2 depending on the catalyst – substantially above ammonia stoichiometry of 0.33. The concentration of ammonia formed was proportional to the specific energy input. Increasing the reaction temperature or decreasing gas flow rates resulted in a lower specific production due to ammonia decomposition. The most efficient catalysts were found to be 2 wt% Rh/Al2O3 among platinum-group metals and 5 wt% Ni/Al2O3 among transitional metals. With the 2 wt% Rh catalyst, 1.43 vol% ammonia was produced with an energy efficiency of 0.94 g kWh−1. The observed behaviour was explained by a combination of gas-phase and catalytic ammonia formation reactions with plasma-activated nitrogen species. Plasma catalysts provide a synergetic effect by activation of hydrogen on the surface requiring lower-energy nitrogen species.

The effect of sulfur in rotary kiln fuels on nickel laterite calcination

Rotary Kiln - Electric Furnace (RKEF) process is the most commonly used pyrometallurgical technique for processing nickel laterite ores and is mainly suited for saprolite deposits. Sulfur is one of the harmful elements in crude ferronickel obtained via the RKEF process. Typically, laterite ores contain insubstantial sulfur content; hence, it is hypothesized that most of the sulfur in crude ferronickel originates from the coal added as the fuel and the reductant during calcination in the rotary kiln. This study investigates the role of sulfur content of rotary kiln fuels on the composition of the calcine. The calcination-partial reduction experiments were conducted at 900 °C for a 2-h residence time. Various reducing gas mixtures representing combustion products of rotary kiln fuels (e.g., coal) were contacted with the ore. At constant PCO, the sulfur content of the calcine increases linearly with an increase in PSO2 in the input gas mixture. Similarly, at fixed PSO2, the percentage of sulfur in the calcine and the percentage of sulfur deportation increase with PCO. However, an exceptional case is observed at PSO2 = 0 atm in the input gas mixture; the sulfur content and sulfur deportation slightly decrease by increasing PCO in the input gas. The sulfur content and the percentage of sulfur deportation drop at a lower input flow rate of the reducing gas mixtures.