Multi-Channel-Based Microgrid for Reliable Operation and Load Sharing

This paper presents a novel approach to distribute available power among critical and non-critical loads in microgrids. The approach is based on supplying power over a number of channels with distinguishable frequencies where loads could be served by these channels according to their level of importance. The multi-channel scheme not only offers flexibility to supply loads but also to share power among adjacent microgrids. The control system, which can deal with multi-channel scheme, is presented and different applications that can be offered whereby are discussed. The number of channels that can be supplied by any inverter is determined based on the parameters of the used filter. Moreover, the power exchange efficiencies over the active channels at various power levels are determined and approximated formulas for quick evaluation are presented. To verify the proposed solution performance, simulation and experimental studies were performed. The obtained results demonstrate the effectiveness of using multi-channel scheme for power exchange in microgrid and also confirm the accuracy of the provided formula related to power exchange efficiencies.

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АКУСТИЧНА ПОМІТНІСТЬ БЕЗПІЛОТНИХ ЛІТАЛЬНИХ АПАРАТІВ З СИЛОВИМИ УСТАНОВКАМИ НА БАЗІ ПОРШНЕВИХ ДВИГУНІВ

Open Information and Computer Integrated Technologies ◽

10.32620/oikit.2020.88.05 ◽

2020 ◽

pp. 62-80

Author(s):

В. В. Руденко ◽

И. В. Калужинов ◽

Н. А. Андрущенко

Keyword(s):

Control System ◽

Internal Combustion Engine ◽

Power Plants ◽

Combustion Engine ◽

Spectral Characteristics ◽

Experimental Studies ◽

Internal Combustion ◽

Detection Range ◽

Acoustic Signature ◽

Static Conditions

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of noise reduction from UAVs urgent both from the point of view of acoustic imperceptibility and ecology.The aim of the work is to determine a set of methods that help to reduce the visibility of UAVs in the acoustic range. It is shown that the main source of noise from the UAV on the ground is the power plant, which includes the engine and the propeller. The parameters of the power plants influencing the processes that determine the acoustic signature of the UAV were investigated. A comprehensive analysis of the factors affecting visibility was carried out. The power plants include two-stroke and four-stroke engines, internal combustion and two-blade propellers. The use of silencers on the exhaust of the internal combustion engine was considered. The spectral characteristics of the acoustic fields of the propeller-driven power plants for the operating sample of the UAV "Eco" were obtained. The measurements were carried out in one-third octave and 1/48 octave frequency bands under static conditions. The venue is the KhAI airfield. Note that the propellers that were part of the power plants operated at Reynolds numbers (Re0,75<2*105), which can significantly affect its aerodynamic and acoustic characteristics. It is shown that when choosing a UAV control system, one should take into account the fact that two-stroke piston engines are the dominant source in the noise of propeller-driven control systems in the absence of a hood and mufflers in the intake and exhaust tracts. The use of a four-stroke internal combustion engine significantly reduces the noise of the control system. In the general case, the position of the boundaries of the zone of acoustic visibility of a UAV at the location of the observer is determined by the ratio between the intensity of acoustic radiation perceived by the observer from the UAV and the intensity of sound corresponding to the natural acoustic background and depends on the degree of manifestation of acoustic effects accompanying the propagation of sound in a turbulent atmosphere - the refraction of sound waves. Absorption and dissipation of acoustic energy. The calculation and comparison of the UAV detection range was carried out taking into account the existing natural maskers.The results of experimental studies are presented that allow assessing the degree of acoustic signature of the UAV. A set of measures aimed at reducing the intensity of the acoustic signature of the UAV in various regions of the radiation spectrum has been determined.

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Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove"

SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION ◽

10.28999/2541-9595-2020-10-3-226-233 ◽

2020 ◽

Vol 10 (3) ◽

pp. 226-233

Author(s):

Dmitry A. Neganov ◽

◽

Victor M. Varshitsky ◽

Andrey A. Belkin ◽

◽

...

Keyword(s):

Internal Pressure ◽

Experimental Studies ◽

Full Scale ◽

The Other ◽

Metal Loss ◽

Calculation Methods ◽

Reliable Operation ◽

Sufficient Stability ◽

Comparative Results ◽

The Moment

The article contains the comparative results of the experimental and calculated research of the strength of a pipeline with such defects as “metal loss” and “dent with groove”. Two coils with diameter of 820 mm and the thickness of 9 mm of 19G steel were used for full-scale pipe sample production. One of the coils was intentionally damaged by machining, which resulted in “metal loss” defect, the other one was dented (by press machine) and got groove mark (by chisel). The testing of pipe samples was performed by applying static internal pressure to the moment of collapse. The calculation of deterioration pressure was carried out with the use of national and foreign methodical approaches. The calculated values of collapsing pressure for the pipe with loss of metal mainly coincided with the calculation experiment results based on Russian method and ASME B31G. In case of pipe with dent and groove the calculated value of collapsing pressure demonstrated greater coincidence with Russian method and to a lesser extent with API 579/ASME FFS-1. In whole, all calculation methods demonstrate sufficient stability of results, which provides reliable operation of pipelines with defects.

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A Study on Vision-Based Backstepping Control for a Target Tracking System

Actuators ◽

10.3390/act10050105 ◽

2021 ◽

Vol 10 (5) ◽

pp. 105

Author(s):

Thinh Huynh ◽

Minh-Thien Tran ◽

Dong-Hun Lee ◽

Soumayya Chakir ◽

Young-Bok Kim

Keyword(s):

Control System ◽

Visual Servoing ◽

Tracking System ◽

Experimental Studies ◽

Imaging Geometry ◽

Control Scheme ◽

Decoupled Control ◽

Control Configuration ◽

A New Technique ◽

Pointing Control

This paper proposes a new method to control the pose of a camera mounted on a two-axis gimbal system for visual servoing applications. In these applications, the camera should be stable while its line-of-sight points at a target located within the camera’s field of view. One of the most challenging aspects of these systems is the coupling in the gimbal kinematics as well as the imaging geometry. Such factors must be considered in the control system design process to achieve better control performances. The novelty of this study is that the couplings in both mechanism’s kinematics and imaging geometry are decoupled simultaneously by a new technique, so popular control methods can be easily implemented, and good tracking performances are obtained. The proposed control configuration includes a calculation of the gimbal’s desired motion taking into account the coupling influence, and a control law derived by the backstepping procedure. Simulation and experimental studies were conducted, and their results validate the efficiency of the proposed control system. Moreover, comparison studies are conducted between the proposed control scheme, the image-based pointing control, and the decoupled control. This proves the superiority of the proposed approach that requires fewer measurements and results in smoother transient responses.

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Optical Inspection Systems for Axisymmetric Parts with Spatial 2D Resolution

Symmetry ◽

10.3390/sym13071218 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1218

Author(s):

Aleksandr Kulchitskiy

Keyword(s):

Control System ◽

Optical System ◽

Measurement Accuracy ◽

Experimental Studies ◽

Digital Camera ◽

Digital Cameras ◽

Bodies Of Revolution ◽

Optical Inspection ◽

Inspection Systems ◽

Projection Error

The article proposes a solution to the problem of increasing the accuracy of determining the main shaping dimensions of axisymmetric parts through a control system that implements the optical method of spatial resolution. The influence of the projection error of a passive optical system for controlling the geometric parameters of bodies of revolution from the image of its sections, obtained by a digital camera with non-telecentric optics, on the measurement accuracy is shown. Analytical dependencies are derived that describe the features of the transmission of measuring information of a system with non-telecentric optics in order to estimate the projection error. On the basis of the obtained dependences, a method for compensating the projection error of the systems for controlling the geometry of the main shaping surfaces of bodies of revolution has been developed, which makes it possible to increase the accuracy of determining dimensions when using digital cameras with a resolution of 5 megapixels or more, equipped with short-focus lenses. The possibility of implementing the proposed technique is confirmed by the results of experimental studies.

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Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

Molecules ◽

10.3390/molecules26133866 ◽

2021 ◽

Vol 26 (13) ◽

pp. 3866

Author(s):

Natasha Irrera ◽

Alessandra Bitto ◽

Emanuela Sant’Antonio ◽

Rita Lauro ◽

Caterina Musolino ◽

...

Keyword(s):

Cannabinoid Receptors ◽

Hematological Malignancies ◽

Antitumor Agents ◽

Control Cell ◽

Experimental Studies ◽

Endocannabinoid System ◽

Chemotherapeutic Agents ◽

Cancer Cell Growth ◽

Cell Functions ◽

Novel Approach

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

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Collective Losses of Low Power Cage Induction Motors—A New Approach

Energies ◽

10.3390/en14061749 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1749

Author(s):

Elzbieta Szychta ◽

Leszek Szychta

Keyword(s):

Control System ◽

Experimental Studies ◽

Complex Problem ◽

Accurate Estimation ◽

New Approach ◽

Water Pumping ◽

Efficiency Control ◽

Interacting Systems ◽

Cage Induction Motor ◽

Selection Of

Energy efficiency of systems of water pumping is a complex problem since efficiency of two distinct interacting systems needs to be combined: water and power supply. This paper introduces a non-intrusive method of calculating the so-called “collective losses” of a cage induction motor. The term “collective losses”, which the authors define, allows for accurate estimation of motor efficiency. Control system of a pump determines operating point of a pumping station, and thus its efficiency. General estimated performance characteristics of a motor, components of a control system, are assumed to serve selection of a range of pumping speed variations. Rotational speed has a direct effect on motor load torque, pump power and head, and thus on motor performance. Hellwig’s statistical method was used to specify characteristics of estimated collective losses on the basis of experimental studies of 21 motors rated at up to 2.2 kW. The results of simulations and experiments are used to verify validity and efficiency of the suggested method. The method is non-intrusive, simple to use, and requires minimum data.

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Hypoxic mechanisms in primary headaches

Cephalalgia ◽

10.1177/0333102416647037 ◽

2016 ◽

Vol 37 (4) ◽

pp. 372-384 ◽

Cited By ~ 8

Author(s):

Josefine Britze ◽

Nanna Arngrim ◽

Henrik Winther Schytz ◽

Messoud Ashina

Keyword(s):

Cluster Headache ◽

High Altitude ◽

Acute Mountain Sickness ◽

Experimental Studies ◽

Epidemiological Studies ◽

Primary Headaches ◽

Secondary Headaches ◽

Novel Approach ◽

Calcitonin Gene ◽

Level Of Knowledge

Background Hypoxia causes secondary headaches such as high-altitude headache (HAH) and headache due to acute mountain sickness. These secondary headaches mimic primary headaches such as migraine, which suggests a common link. We review and discuss the possible role of hypoxia in migraine and cluster headache. Methods This narrative review investigates the current level of knowledge on the relation of hypoxia in migraine and cluster headache based on epidemiological and experimental studies. Findings Epidemiological studies suggest that living in high-altitude areas increases the risk of migraine and especially migraine with aura. Human provocation models show that hypoxia provokes migraine with and without aura, whereas cluster headache has not been reliably induced by hypoxia. Possible pathophysiological mechanisms include hypoxia-induced release of nitric oxide and calcitonin gene-related peptide, cortical spreading depression and leakage of the blood-brain barrier. Conclusion There is a possible link between hypoxia and migraine and maybe cluster headache, but the exact mechanism is currently unknown. Provocation models of hypoxia have yielded interesting results suggesting a novel approach to study in depth the mechanism underlying hypoxia and primary headaches.

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EXPERIMENTAL STUDIES ON THE DEVELOPMENT OF AN AUTOMATED SYSTEM FOR REGULATING THE SOIL DENSITY USED IN A SEEDING MACHINE

AGRICULTURAL ENGINEERING ◽

10.26897/2687-1149-2021-2-9-15 ◽

2021 ◽

pp. 9-15

Author(s):

ALEKSEI S. DOROKHOV ◽

Keyword(s):

Control System ◽

Automatic Control ◽

Automatic Control System ◽

Power Supply ◽

Experimental Studies ◽

Automated System ◽

Statistical Characteristics ◽

Vegetable Crops ◽

Soil Density ◽

Density Control

Research on the development of an automatic control system for the rolling-in working units is aimed at establishing the reliability and analytical relationships, determining the quality indicators of work in real conditions of the rolling-in working units of a seeding machine, and checking the patterns obtained in the fi eld and identifi ed theoretically. Research on the development of an automatic control system for the rolling implements was carried out when sowing dragee seeds of table beet of the Bordeaux variety with a seeding unit consisting of a Belarus-4235 tractor and a Monopil S15/12 precision seeding machine. The system for automatic control of soil density includes the main hardware and software: actuators for maintaining and deepening the rolling working units, microcontrollers, motor drivers, a non-contact ultrasonic sensor, a power supply unit and a sensor for measuring soil density. The paper presents the results of a study to determine the soil density when sowing seeds of table beet, depending on the moisture content of the soil in the sowing layer. The authors describe research methodology, provide graphical relationships between changes in soil density and the depth of seeding, and comment on the main obtained statistical characteristics of the experiment. As a result of the study, structural, echnological and functional diagrams of a rolling rink with an automatic control system using electronically controlled electric cylinders (linear actuators) have been developed. The optimal parameters of the linear drive of the press roller have been established: power - 50W, power supply - 12V, rod stroke - 200…600 mm, speed - 10…45 mm/s, load - 200…900 N. Experimental studies have shown the applicability of the presented system of the automatic control of soil density, which ensures the optimum density of the seedbed of 1.3…1.4 g/cm³. The described technique can be used to develop a soil density control system when sowing seeds of other vegetable crops.

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Decentralized Voltage Regulation in Islanded DC Microgrids Based on a Modified Droop Control using Superimposed AC Voltage

10.36227/techrxiv.16641184.v1 ◽

2021 ◽

Author(s):

Mohammadreza Nabatirad ◽

Reza Razzaghi ◽

Behrooz Bahrani

Keyword(s):

Control System ◽

Load Sharing ◽

Voltage Regulation ◽

Control Technique ◽

Droop Control ◽

Dc Microgrids ◽

Distributed Generator ◽

Voltage Compensation ◽

Terminal Voltage ◽

Unit Output

The conventional droop control is a widely-used technique in load sharing among Distributed Generator (DG) units in islanded DC Microgrids (MGs). This method provides Plug-and-Play (PnP) capability for DG units; however, poor load sharing accuracy and unregulated voltage are two shortcomings of that. This article proposes a novel control system in islanded DC MGs to provide simultaneous regulated voltage and accurate load sharing. The method utilizes a modified droop control technique in a decentralized manner. The proposed control system injects a superimposed AC voltage to the network that carries a frequency proportional to the master DG unit output current. The injected voltage adjusts an added a term to the conventional droop control named as the voltage compensation term in order to cancel voltage changes. This term adjusts terminal voltage of DG units proportional to the frequency of the superimposed AC voltage. The performance of the proposed control system is validated via a set of simulation studies using PLECS, and the experimental results confirm the viability and feasibility of the proposed control system.

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