Experimentally Tested Research Articles

Utilization of different plant species for dewatering of sewage sludge.

Bench-scale and pilot-scale experiments were conducted in an outdoor environment to study the ability of some plant species in dewatering of sewage sludge collected from biological activated sludge treatment. In the bench-scale experiments, four types of plants were tested, including water hyacinth (Eichhornia crassipes), common reed (Phragmites austuralis), Samar (Cyperus alopecuroides), and El Nesila (Panicum echinochloa). Sludge dewatering in the plant reactors was compared with that in the control reactors (no plants). The bench-scale experiments were conducted in reactors with capacities of 17 L. All plants showed a growth in the sewage sludge matrix. High dewatering efficiencies of sewage sludge were obtained with the use of each type of plant, as compared with those in the controls. Among other plants tested in the current study, water hyacinth proved to have the highest dewatering efficiency and was selected for further testing in a pilot-scale experiment. Two identical drying beds were constructed as a pilot-scale, each with its own multi-layered underdrainage system. The plants were added to one of the beds while the other bed served as a control. The pilot study showed that the use of water hyacinth in conventional sludge drying beds can triple the sludge dewatering capacity of these beds. In addition, the quality of the dewatered sludge was also improved compared with that found in conventional drying beds.

Zero Voltage Switching Condition in Class-E Inverter for Capacitive Wireless Power Transfer Applications

This paper presents a complete design methodology of a Class-E inverter for capacitive wireless power transfer (CWPT) applications, focusing on the capacitance coupling influence. The CWPT has been investigated in this paper, because most of the literature refers to inductive power transfer (IWPT). However, CWPT in perspective can result in lower cost and higher reliability than IWPT, because it does not need coils and related shields. The Class-E inverter has been selected, because it is a single switch inverter with a grounded MOSFET source terminal, and this leads to low costs and a simple control strategy. The presented design procedure ensures both zero voltage switching (ZVS) and zero derivative switching (ZDS) conditions at an optimum coupling coefficient, thus enabling a high transmission and conversion efficiency. The novelties of the proposed method are that the output power is boosted higher than in previous papers available in the literature, the inverter is operated at a high conversion efficiency, and the equivalent impedance of the capacitive wireless power transfer circuit to operate in resonance is exploited. The power and the efficiency have been increased by operating the inverter at 100 kHz so that turn-off losses, as well as losses in inductor and capacitors, are reduced. The closed-form expressions for all the Class-E inverter voltage and currents waveforms are derived, and this allows for the understanding of the effects of the coupling coefficient variations on ZVS and ZDS conditions. The analytical estimations are validated through several LTSpice simulations and experimental results. The converter circuit, used for the proposed analysis, has been designed and simulated, and a laboratory prototype has been experimentally tested. The experimental prototype can transfer 83.5 W at optimal capacitive coupling with operating at 100 kHz featuring 92.5% of the efficiency, confirming that theoretical and simulation results are in good agreement with the experimental tests.

Energetic and exergetic performance comparison of three solar cookers for developing countries

Three different domestic solar cookers are compared experimentally during water heating experiments using different loads. The solar cookers experimentally tested using energy and exergy thermal performance parameters are: a solar box cooker without a reflector, a solar box cooker with a reflector and a parabolic dish solar cooker. The rate of heat losses is more detrimental to the performance of the parabolic solar cooker since the cooking vessel is exposed more to the ambient weather conditions. Heat losses seem to have little effect on the performance of the solar box cookers. The solar box cooker with the reflector shows the highest average energy efficiencies, which increase with the water heating load. The parabolic solar cooker shows the lowest average energy efficiencies with the lower loads, which increase to be higher than those of the solar box cooker without the reflector at the higher loads. The solar box cooker with the reflector shows the highest average energy and exergy efficiency values, which are not dependent on the water load. The parabolic dish solar cooker shows average exergy efficiencies, which increase with the water heating load. The greatest cooking potential in terms of the speed of cooking is shown by parabolic dish solar cooker. The best overall thermal performance is shown with the solar box cooker with a reflector, but its cooking speed is rather slow when compared to the parabolic dish solar cooker. The solar box cooker without the reflector shows the worst thermal performance in most of the tested parameters except for the heat losses where it shows the lowest heat loss factors for all the experimental tests.

Experimental Investigation of the Mechanical Behaviour of Wall\u2013Beam\u2013Strut Joints for Prefabricated Underground Construction

Prefabricated construction is becoming increasingly prevalent, however, it is rarely applied in underground constructions, except for tunnel linings, due to the difficulties that arise in jointing various prefabricated components in underground conditions. To solve the vertical location problem of embedded mechanical couplers during the construction of wall–beam–strut joints for a prefabricated metro station, a new connection using welded steel plates is proposed. In this paper, four full-scale specimens of wall–beam–strut joints connected using welded steel plates and mechanical couplers were experimentally tested under monotonic and low-reversed cyclic loading conditions. The testing results were analysed in terms of the ultimate bearing capacity, failure mode, hysteresis, skeleton curve, stiffness degradation, energy dissipation and strain of the reinforcement bars. Notably, the two kinds of joints had similar ultimate bearing capacities and failure modes, but the crack distributions on the tops of the waler beams were different. For the specimens with the welded steel plate connection, tensile horizontal cracks first appeared on the top surface of the beam, where the welded steel plate was located, and then coalesced gradually; however, this cracking pattern was not observed during the experimental test of the specimens connected with the mechanical couplers. Furthermore, it was determined that the energy dissipation and ductility of the welded steel plate connection were better than those of the mechanical coupler connected joint, because the steel plate could redistribute the internal force in the joint and increase the stiffness. It was concluded that the proposed welded steel plate connection could be more favourable than the mechanical coupler connection in the construction of a prefabricated metro station in Guangzhou. Moreover, the results obtained from these experiments could provide guidelines for the corresponding connections employed in underground-prefabricated structures.

Coplanar waveguide superconducting microwave power divider: Design, preparation and experimental tests

Power divider is a useful device that divides the power of signal into different subpowers at a certain ratio. The superconducting power divider plays an important role in various superconducting quantum computing circuits and superconducting microwave photon detectors. Therefore, in this paper we investigate how to design and prepare a typical coplanar waveguide superconducting microwave power divider. The parameters are designed by using the odd-even mode method to analyze the transport features of a three-port microwave network. Specifically, the microwave transport properties of the device with a center frequency of 5 GHz and 3 dB power division ratio are simulated. Then, the designed aluminum coplanar waveguide superconducting power divider on silicon is prepared by micro-processing technology and experimentally tested at low temperature. It is shown that the measurement results are consistent with the design parameters. It is noted that the center frequency of the actually prepared power divider is measured to be about 5.25 GHz, which is slightly different from the result of the design and simulation. This difference is probably due to the following main reasons. Firstly, the limited precision of the micromachining process is caused by the fact that the fabricated quarter-wave impedance matching line is etched incompletely, leading the length of the impedance matching line to be shortened. As a consequence, the frequency of the prepared power divider is slightly higher. Secondly, the simulation software is not designed specially for superconducting device simulations, thereby yielding the design parameters slightly different from those of the fabricated superconducting devices. Additionally, a series of attenuations has been used in the experimental test system of the superconducting microwave power dividers for reducing the various noises. This causes the input test signal to weaken, thus the reflected signal turns significantly small. Therefore, none of the <i>S</i><sub>11</sub> parameters of the device can be effectively measured. Finally, neither of <i>S</i><sub>21</sub> and <i>S</i><sub>31</sub> parameters measured in the experiment is the predicted –3 dB, which is mainly due to the imperfections in the welding between SMA connectors and high-frequency transmission lines, and the spot welding between high-frequency transmission lines and power divider samples, and also due to the discontinuities of the high-frequency transmission line and the power divider and so on. All these factors can yield the tested insertion loss of the device. Hopefully, the method in this work can be extended to designing and preparing other passive superconducting microwave devices.

Stress Loss of Pre-Tensed CFRP Strips Strengthening Square RС Column

Pre-tensing the CFRP strip strengthening RC column can improve the strain lag of the confined concrete and avoid unloading of column in advance. The pre-stress of strip has an important influence of strengthen. Stress loss of the strip pre-tensed by using the device proposed were investigated by using an experimental test. Firstly, the reasons for the stress loss of strip were analyzed according to the working principle of the device and the strengthening procedure. Then the primary causes of the stress loss, such as friction, relaxation and removing device, were experimentally tested. The influence of the pretension, detail and sectional geometric dimension on the stress loss of the strip were studied. The results show that all three types of pre-stress losses increase significantly with the initial stress. Increasing the cross-sectional size would reduce the relaxation and unwinding losses, but it has little effect on friction losses. The influence of fillet radius on the pre-stress loss was negligible, but in order to avoid premature tearing of local CFRP caused by stress concentration, the chamfer should be made as large as possible within the thickness of concrete protective cover. The test also found that friction was the main cause of stress loss, and friction loss accounts for more than 90% of the total loss.

Model Predictive Control With Environment Adaptation for Legged Locomotion

Re-planning in legged locomotion is crucial to track the desired user velocity while adapting to the terrain and rejecting external disturbances. In this work, we propose and test in experiments a real-time Nonlinear Model Predictive Control (NMPC) tailored to a legged robot for achieving dynamic locomotion on a variety of terrains. We introduce a mobility-based criterion to define an NMPC cost that enhances the locomotion of quadruped robots while maximizing leg mobility and improves adaptation to the terrain features. Our NMPC is based on the real-time iteration scheme that allows us to re-plan online at $25\,\mathrm{Hz}$ with a prediction horizon of $2$ seconds. We use the single rigid body dynamic model defined in the center of mass frame in order to increase the computational efficiency. In simulations, the NMPC is tested to traverse a set of pallets of different sizes, to walk into a V-shaped chimney,and to locomote over rough terrain. In real experiments, we demonstrate the effectiveness of our NMPC with the mobility feature that allowed IIT's $87\, \mathrm{kg}$ quadruped robot HyQ to achieve an omni-directional walk on flat terrain, to traverse a static pallet, and to adapt to a repositioned pallet during a walk.

Experimental testing of exterior wall mounted mechanical ventilation exhaust air outlet devices

The purpose of the study was to experimentally test the performance of four types of wall-mounted mechanical ventilation exhaust air outlet devices. A full-scale mock-up of a segment of an external wall with an exhaust air outlet was constructed. The tested exhaust air devices include a gravity louver, fixed-blade louver, louver plate, and exhaust nozzle. The performance assessment included two types of experiments over the exhaust airflow rate range of 25–94 l/s at isothermal conditions with no influencing wind: (i) the particle tracer method with smoke to visualize the exhaust air jets from the outlets, and (ii) the tracer gas method to measure the dilution of CO2 concentration in the exhaust air jet. Furthermore, the aerodynamic performance was comparatively evaluated in terms of pressure drop and exhaust air face velocity at the outlet. The qualitative comparison of airflow patterns by smoke visualization showed notable differences between the tested device types. Concentration decrease evaluation indicated that the exhaust air pollutants are more efficiently transported away from the building wall by exhaust outlets that discharge at 0–45 degrees downwards from the horizontal plane. Discharge angles 60–90 degrees downwards produced a wall-attached jet and the pollutant tracer concentration remained relatively high in the vicinity of the wall.

Prediction of Withdrawal Resistance of Single Screw on Korean Wood Products

In this article, withdrawal resistances of axially loaded self-tapping screws on wood products made by Korean Larch were predicted with existing estimation equation, and compared with experimental test data. The research was required because no design methodology for the withdrawal resistance of self-tapping screw is present in Korean building code (KBC). First, the withdrawal resistance of wood screw was predicted to use the withdrawal design value estimation equation in National Design Specification for Wood Construction (NDS). Second, three types of wood products, solid wood, cross-laminated timber (CLT) and plywood, were utilized for withdrawal test. For decades, various engineered wood products have been developed, especially cross-laminated timber (CLT) and hybrid timber composites such as timber composites of solid wood and plywood. Therefore, CLT and plywood were also investigated in this study as well as solid wood. Finally, the predicted values were compared with experimentally tested values. As the results, the tested values of solid wood and CLT were higher than the predicted values. In contrast, it is inaccurate to predict withdrawal resistance of plywood since prediction was higher than tested values.

Korelacije prinosa zrna soje i komponenti prinosa između potomstava majki i ukrštanja u punom srodstvu

The F2 population was developed by crossing the adaptive yield variety of soybean with a variety without the Kunitz trypsin inhibitor in the mature grain. From the segregating F2 population 48 plants were taken. Their seeds were used to set up field experiment; part of the seed was saved for full-sib (FS) crosses. After yield testing, three lines marked as L6, L30 and L38 were chosen. Two FS cross combination, using saved seeds, were made (L30 x L38 and L6 x L30). Progenies of soybean full-sibs (FSF1:2) and each mother plant (F3:4) were grown, to make enough seed for testing in the field experiment. Data obtained in this experiment were processed to determine correlations of grain yield and other studied traits between mother's and proper full-sib progenies, using simple correlations and Spearman's rank correlations. A significant correlation into examinated traits between two types of progenies does not found, except for stem height and 1000 grain weight in the FS combination L30 x L38. The lack of correlation of plant characteristics between progenies of full-sibs and their mothers indicated the influence of lines used as fathers component. In both combinations of FS crosses, FSF1:2 progenies with better yield than the adapted parent (one without Kunitz trypsin inhibitor) were identified, which are considered promising for the further process of creating new varieties.

Treatment Preferences for Cardiac Procedures of Patients With Chronic Kidney Disease in Acute Coronary Syndrome: Design and Pilot Testing of a Discrete Choice Experiment.

Background:Chronic kidney disease is associated with a high incidence of acute coronary syndrome and related morbidity and mortality. Treatment choices for patients with chronic kidney disease involve trade-offs in the potential benefits and harms of invasive management options.Objective:The objective was to quantify preferences of patients with chronic kidney disease toward invasive heart procedures.Design:Design and pilot a discrete choice experiment.Setting:We piloted the discrete choice experiment in 2 multidisciplinary chronic kidney disease clinics in Calgary, Alberta, using an 8-question survey.Patients:Eligible patients included those aged 18 years and older, an estimated glomerular filtration rate < 45 mL/min/1.73 m2, not currently receiving dialysis, and able to communicate in English.Measurements:Quantification of the average importances of key attributes of invasive heart procedures.Methods:We identified attributes most important to patients and physicians concerning invasive versus conservative management for acute coronary syndrome, using semi-structured qualitative interviews. Levels for each attribute were derived from analysis of early invasive versus conservative acute coronary syndrome management clinical trials and cohort studies, where subgroups of patients with chronic kidney disease were reported. We designed the pilot study with patient partners with relevant lived experience and considered statistical efficiency to estimate main effects and interactions, as well as response efficiency. Hierarchical Bayesian estimation was used to quantify average importances of attributes.Results:We recruited 43 patients with chronic kidney disease, mean (SD) age 67 (14) years, 67% male, and 35% with a history of cardiovascular disease, of whom 39 completed the survey within 2 weeks of enrollment. The results of the pilot revealed acute kidney injury requiring dialysis and permanent kidney replacement therapy, as well as death within 1 year were the most important attributes. Measures of internal validity for the pilot discrete choice experiment were comparable to those for other published discrete choice experiments.Limitations:Discrete choice experiments are complex instruments and often cognitively demanding for patients. This survey included multiple risk attributes which may have been challenging for some patients to understand.Conclusions:This pilot study demonstrates the feasibility of a discrete choice experiment to quantify preferences of patients with chronic kidney disease toward the benefits and trade-offs related to invasive versus conservative management for acute coronary syndrome. These preliminary findings suggest that patients with chronic kidney disease may be on average similarly risk averse toward kidney replacement therapy and death. This pilot information will be used to inform a larger discrete choice experiment that will refine these estimates of patient preferences and characterize subgroups with distinct treatment preferences, which should provide new knowledge that can facilitate shared decision-making between patients with chronic kidney disease and their care providers in the setting of acute coronary syndrome.

Development Research on Integrating CNC Machine Tool with Plasma for Online Surface Heat Treatment

In this study, the plasma was integrated with a lathe, and the online heat treatment was performed to achieve mechanical strength and hardness, to reduce the machining process and handling. However, for online heat treatment of cast iron FC25, it is important to study the parameters of the lathe and plasma, and the research method is used eventually to optimize the process and reduce the machining cost and machining error. The variable factors in the surface online real‐time heat treatment are spindle speed, feed rate, and current, and the objective function is the hardness of mechanical properties. In the screening experiment, the interaction of factors was discussed using a full factorial experiment. The Central Composite Design was combined with the Lack‐of‐Fit test for the optimization experiment, and the R2 coefficient was used to determine whether the regression model is appropriate. The optimum parameters were derived from the contour diagram and response surface diagram. The experimental results show that the significant factors include spindle speed, feed rate, and current and the optimum parameters include spindle speed of 168 rpm, feed rate of 0.068 mm/rev, and current of 86 A. The experimental results of optimum parameters show that the surface hardness is increased from 306 HLD to 806 HLD and the surface hardening effect is enhanced by 163%, so the online real‐time heat treatment equipment has the best hardening effect.

Mobile Measurement System for the Rapid and Cost-Effective Surveillance of Methane and Volatile Organic Compound Emissions from Oil and Gas Production Sites.

In this study, a ground-based mobile measurement system was developed to provide rapid and cost-effective emission surveillance of both methane (CH4) and volatile organic compounds (VOCs) from oil and gas (O&G) production sites. After testing in several controlled release experiments, the system was deployed in a field campaign in the Eagle Ford basin, TX. We found fat-tail distributions for both methane and total VOC (C4-C12) emissions (e.g., the top 20% sites ranked according to methane and total VOC (C4-C12) emissions were responsible for ∼60 and ∼80% of total emissions, respectively) and a good correlation between them (Spearman's R = 0.74). This result suggests that emission controls targeting relatively large emitters may help significantly reduce both methane and VOCs in oil and wet gas basins, such as the Eagle Ford. A strong correlation (Spearman's R = 0.84) was found between total VOC (C4-C12) emissions estimated using SUMMA canisters and data reported from a local ambient air monitoring station. This finding suggests that this system has the potential for rapid emission surveillance targeting relatively large emitters, which can help achieve emission reductions for both greenhouse gas (GHG) and air toxics from O&G production well pads in a cost-effective way.

The influence of operational sex ratio on reproductive success in male sheepshead minnow (Cyprinodon variegatus)

Abstract Operational sex ratio (OSR) is predicted to influence the direction and intensity of sexual selection. Thus, as the relative numbers of reproductively active males vs females change, the behavioural competition among males and their differences in reproductive success are also predicted to change. While these outcomes seem intuitively obvious, there have been few experimental tests that examine these predictions. Here, we experimentally tested the relationship between OSR and reproductive behaviour in sheepshead minnows (Cyprinodon variegatus) competing in laboratory-based pools. Males and females were assigned to one of three OSRs (female-biased, equal, or male-biased). We monitored aggression, territory size, and number of eggs acquired by the most aggressive male, termed the “focal male,” in the pool. We used microsatellite analyses to determine the parentage of the eggs within the focal males’ territories. Focal males, by definition, were the most aggressive individual in their pools, but the degree of their aggressiveness and number of spawning sites they controlled were not influenced by OSR. Compared to focal males in the equal and male-biased OSRs, focal males in the female-biased OSR did receive more eggs but the OSR did not appear to influence the percentage of eggs they fathered on their own spawning sites. We speculate that a focal male’s competitive ability is more important to reproductive success than the number of other males and females present.

Blind competition on the numerical simulation of steel‐fiber‐reinforced concrete beams failing in shear

AbstractExperimental research has shown the extraordinary potential of the addition of short fibers to cement‐based materials by improving significantly the behavior of concrete structures for serviceability and ultimate limit states. Software based on the finite element method has been used for the simulation of the material nonlinear behavior of fiber‐reinforced concrete (FRC) structures. The applicability of the existing approaches has often been assessed by simulating experimental tests with structural elements, in general of a small scale, where the parameter values of the material constitutive laws are adjusted for the aimed predicting level, which constitutes an inverse technique of arguable utility for structural design practice. For assessing the predictive performance of these approaches, a blind simulation competition was organized. Two twin T‐cross section steel FRC beams, flexurally reinforced with steel bars and without conventional shear reinforcement in the critical shear span, were experimentally tested up to failure. Despite the experimental data provided for the definition of the relevant model parameters, inaccuracies on the load capacity, deflection, and strain at peak load attained 40, 113, and 600%, respectively. Inadequate failure modes and highly different results were estimated with the same commercial software, indicating the need for deeper analysis and understanding of the models and influence of their parameters on their predictive performance.

Applying evolutionary methods in economics: progress or pitfall?

The Darwinian theory of evolution has arguably become an important building block for experimental and theoretical economists. According to Burnham (J Econ Behav Org 90:S113–S127, 2013), it is possible to formulate novel hypotheses and predictions about human preferences, on the basis of what patterns of behavior would have been adaptive in the ancestral environment. After clarifying two theoretical concepts, the Adaptively Relevant Environment and fitness maximization, I argue that multiple scientifically plausible hypotheses about human preferences are compatible with evolutionary models that target behavior. Moreover, I propose a refinement of Burnham’s method based on theoretical resources provided by the indirect evolutionary approach. Economists apply or build evolutionary models of their own that target particular features of human psychology and cognition. Such models may reduce the number of plausible hypotheses to allow for rigorous scientific testing in laboratory or field experiments.

Estimating Each Other’s Memory Biases in Dialogue

ABSTRACT Conversational memory is subject to a number of biases. For instances, references which were reused during dialogue are remembered better than non-reused references. Two experiments examined whether speakers are aware that they are subject to such biases and whether they use information about reference origin (i.e., information about who said what) to determine which references are remembered better by their partner. Pairs of participants performed a map task followed by a questionnaire that assessed each participant’s content memory as well as each participant’s estimation of his or her partner’s memory. In Experiment 1, the participants were unaware that they would perform a memory test after the map task, whereas the participants were mutually aware of the upcoming memory test in Experiment 2. The results revealed that participants did know that their partner was subject to memory biases and that their estimation of these biases was mainly accurate. The results prevented us from drawing any conclusions about the role of origin memory in this process. These results have important implications for subsequent dialogic partner-adaptation.

Application of information technologies and microprocessor equipment for reducing the number of road accidents

Problems. Overcoming the consequences of road accidents places a heavy burden on the country's health care and social services. The International Transport Forum has prepared a report "Striving for Zero: High Challenges and a Systemic Approach to Road Safety". The forum experts consider driving while intoxicated one of the key problems in the growing number of road accidents, and the use of information technology is one of the ways to reduce the number of accidents. Goal. On the basis of the conducted analysis the purpose of research which consists in creation of a way and the device for impossibility of driving of vehicles by drunk drivers is formulated. Tasks: 1. To formulate the concept of improving road safety in Ukraine in terms of preventing drunk drivers from driving; 2. To develop the functional scheme of the device for anti-alcohol blocking of vehicles; 3. To develop a schematic diagram of such a device; 4. To collect and test a full-scale sample of the device in the laboratory for experimental confirmation of the efficiency of the proposed method. Methodology. The analytical method was used – the study of existing systems that do not allow drivers to drive while intoxicated and the method of synthesis - the creation of a block diagram of a new system based on the advantages and disadvantages of the analyzed systems. Results. When creating a method of a device to prevent driving a vehicle, an analysis of existing methods and devices for forcible restriction of driving under the influence of drinks was made, which showed the lack of solutions to this problem in Ukraine at the moment. We have developed a method of improving safety in transport, based on the unconditional impossibility of driving under the influence of drunk drivers and developed its block diagram. A functional diagram of an anti-alcohol blocking device for the implementation of the proposed method on modern cars, which requires changes in their software, has also been developed. An electrical circuit of the locking device for vehicles based on the Arduino microprocessor platform has been developed. Using Arduino allows the developer to assemble the device with the desired properties and independently program the microprocessor to perform the desired actions in a given sequence. As a result, an anti-alcohol blocking device was assembled, programmed and experimentally tested. Experimental testing in conditions as close as possible to real (car starter and battery) showed that the developed device disconnects the starter from the power supply in the presence of a given amount of alcohol in the air. Practical value. The practical significance of the developed method of improving transport safety, which makes it impossible for drunk drivers to drive vehicles, is the possible savings for the state of Ukraine of about twenty billion hryvnias, which are spent each year on the consequences of road accidents. But the most important thing is the lives saved, which cannot be estimated in hryvnias or dollars.Key words: Arduino platform, information technologies, reduction of accidents on highways, microprocessor systems, microprocessor programming.

Control scheme selection and optimal tuning in industrial process control using factorial experiment design

In this study, a novel experimental approach for the optimal selection of an actuator-based control strategy is presented. The proposed approach is a two-stage method: first, a two-level factorial experiment design with n factors (2n) was applied to compare different control schemes. Schemes comparison was carried out in terms of energy consumption and closed-loop performance. For the best relative scheme, a Central Composite Face-centered (CCF) design was completed obtaining the controller parameters that optimize the performance in terms of the Integral Absolute Error (IAE) while operating in a region of low energy consumption. The proposed approach was experimentally tested using real data obtained from a laboratory prototype plant. Some experimental tests illustrating the suitability of our method are shown at the end of this article.

Extended Model Predictive Controller to Develop Energy Management Systems in Renewable Source-Based Smart Microgrids with Hydrogen as Backup. Theoretical Foundation and Case Study

This article presents a methodological foundation to design and experimentally test a Model Predictive Controller (MPC) to be applied in renewable source-based microgrids with hydrogen as backup. The Model Predictive Controller has been developed with the aim to guarantee the best energy distribution while the microgrid operation is optimized considering both technical and economic parameters. As a differentiating element, this proposal provides a solution to the problem of energy management in real systems, addressing technological challenges such as charge management in topologies with direct battery connection, or loss of performance associated with equipment degradation or the required dynamics in the operation of hydrogen systems. That is, the proposed Model Predictive Controller achieves the optimization of microgrid operation both in the short and in the long-term basis. For this purpose, a generalized multi-objective function has been defined that considers the energy demand, operating costs, system performance as well as the suffered and accumulated degradation by microgrid elements throughout their lifespan. The generality in the definition of the model and cost function, allows multi-objective optimization problems to be raised depending on the application, topology or design criteria to be considered. For this purpose, a heuristic methodology based on artificial intelligence techniques is presented for the tuning of the controller parameters. The Model Predictive Controller has been validated by simulation and experimental tests in a case study, where the performance of the microgrid under energy excess and deficit situations has been tested, considering the constrains defined by the degradation of the systems that make up the microgrid. The designed controller always made it possible to guarantee both the power balance and the optimal energy distribution between systems according to the predefined priority and accumulated degradation, while guaranteeing the maximum operating voltage of the system with a margin of error less than 1%. The simulation and experimental results for the case study showed the validity of the controller and the design methodology used.