Electric Propulsion Research Articles

Orbital Electrowetting-on-Dielectric for Droplet Manipulation on Superhydrophobic Surfaces.

Electrowetting-on-dielectric (EWOD), recognized as the most successful electrical droplet actuation method, is essential in diverse applications, ranging from thermal management to microfluidics and water harvesting. Despite significant advances, it remains challenging to achieve repeatability, high speed, and simple circuitry in EWOD-based droplet manipulation on superhydrophobic surfaces. Moreover, its efficient operation typically requires electrode arrays and sophisticated circuit control. Here, a newly observed droplet manipulation phenomenon on superhydrophobic surfaces with orbital EWOD (OEW) is reported. Due to the asymmetric electrowetting force generated on the orbit, flexible and versatile droplet manipulation is facilitated with OEW. It is demonstrated that OEW droplet manipulation on superhydrophobic surfaces exhibits higher speed (up to 5 times faster), enhanced functionality (antigravity), and manipulation of diverse liquids (acid, base, salt, organic, e.g., methyl blue, artificial blood) without contamination, and good durability after 1000 tests. It is envisioned that this robust droplet manipulation strategy using OEW will provide a valuable platform for various processes involving droplets, spanning from microfluidic devices to controllable chemical reactions. The previously unreported droplet manipulation phenomenon and control strategy shown here can potentially upgrade EWOD-based microfluidics, antifogging, anti-icing, dust removal, and beyond.

DESIGN OF IOT BASED TRICYCLE

The rapid advancement in Internet of Things (IoT) technology has opened up numerous opportunities for innovation across various industries. In the transportation sector, IoT has the potential to revolutionize conventional vehicles into smart, connected modes of transportation. This project focuses on the design of an IoT-based electric tricycle, aimed at providing a sustainable and efficient mode of personal transportation.The electric tricycle integrates IoT technology to enhance its functionality and user experience. Key features include real-time monitoring of vehicle parameters such as speed, battery status, and location, enabling remote tracking and management through a dedicated mobile application. Additionally, the tricycle incorporates smart safety features such as collision detection and automatic emergency braking, enhancing rider safety on the road.The design phase involves the selection of appropriate components and the integration of IoT modules, sensors, and actuators into the tricycle framework. The fabrication process encompasses building the chassis, integrating the electric propulsion system, and assembling the IoT components. Emphasis is placed on ensuring durability, reliability, and energy efficiency throughout the construction process.Overall, the project aims to contribute to the advancement of sustainable transportation solutions by leveraging IoT technology to create an innovative, eco-friendly electric tricycle. Through this endeavor, we envision promoting the adoption of electric vehicles and facilitating a more connected and efficient urban mobility ecosystemTop of Form Keywords: IoT-based electric tricycle, Sustainable transportation, Connected vehicles, Electric vehicle innovation, Real-time monitoring, Safety features, Fabrication process, Integration of IoT technology, User experience, Smart mobility solution

Designing Digital Twins of Robots Using Simscape Multibody

Digital twins of industrial and collaborative robots are widely used to evaluate and predict the behavior of manipulators under different control strategies. However, these digital twins often employ simplified mathematical models that do not fully describe their dynamics. In this paper, we present the design of a high-fidelity digital twin of a six degrees-of-freedom articulated robot using Simscape Multibody, a Matlab toolbox that allows the design of robotic manipulators in a rather intuitive and user-friendly manner. This robot digital twin includes joint friction, transmission gears, and electric actuators dynamics. After assessing the dynamic accuracy of the Simscape model, we used it to test a computed torque control scheme, proving that this model can be reliably used in simulations with different aims, such as validating control schemes, evaluating collaborative functions or minimizing power consumption.

Predicting propeller emergence severity in adverse sea conditions: An integrated approach using stacked machine learning models

In adverse sea conditions, variations in the propeller submergence depth can induce ventilation and out-of-water effects. These effects result in propeller-torque and thrust losses, impacting the shipboard power network's reliability and accelerate wear on propulsion shaft system. Ensuring the stability and safety of sailing ships necessitates predicting the occurrence and severity of ventilation and out-of-water effects. This, in turn, enables the implementation of a switching strategy with a fast response for propulsion control. Nonetheless, existing methods can only identify current propeller ventilation states, mainly categorised as ventilation and non-ventilation, or more elaborately, as full ventilation, partial ventilation and non-ventilation. These methods, however, face a critical limitation—they cannot predict the severity of ventilation or the out-of-water effect, leading to ineffective propulsion-control-strategy switching. This study proposes a method for predicting propeller emergence severity (that is, non-emergence, light emergence and severe emergence) under wave conditions. This method introduces a novel approach for establishing propeller emergence states and a sophisticated stacked model. The new method categorises different propeller emergence states for diverse classifications based on the maximum emergence severity that the propeller can develop. This to overcome the challenges in predicting the development of the ventilation severity and the out-of-water effect. The innovative stacked model helps improve the overall prediction performance of a single intelligent algorithm. Finally, using simulation experimental data, it is verified that the propeller emergence severity method has satisfactory effectiveness and accuracy. The proposed method provides crucial technical support for the efficient switching of propulsion control strategies in electric propulsion systems when ships are navigating under adverse sea conditions.

MW-Scale High-Voltage Direct-Current Power Conversion for Large-Spacecraft Electric Propulsion

This paper proposes a megawatt (MW)-scale high-voltage (HV) electrical power-conversion element for large-spacecraft electric propulsion (EP) systems. The proposed scheme is intended for long-term and crewed missions, and it is driven by a nuclear electric propulsion (NEP) that acts as a heat source. The scheme includes (i) A two-rotor generator (TRG), (ii) A rectification stage, and (iii) An isolated dual output DC-DC (iDC2) converter. The TRG is a high-reliability electric machine with two rotors, a permanent magnet rotor (PMR), and a wound field rotor (WFR). The PMR has a fixed flux and hence back-EMF, while the back-EMF due to the WFR is controlled by injecting a direct current (DC) into the WFR winding. The total TRG output voltage, which is the sum of voltages due to the PMR and WFR, is controlled over a prescribed region of spacecraft operation. The output of the TRG is rectified and connected to the input of the iDC2 converter. The iDC2 converter uses a three-winding transformer, where the primary winding is fed from the rectified output of TRG, the secondary winding processes the propulsion power to an electric thruster via a high-voltage DC (HVDC) link and a tertiary winding that is connected to the spacecraft’s low-voltage DC (LVDC) power system. Three controllers are proposed for the system: an HVDC voltage controller, an HVDC current controller that controls the voltage and current processed to the thruster, and an LVDC controller that adjusts the current to the LVDC system. Detailed analytical models for the TRG, iDC2 converter, and controllers are developed and verified via simulations under different conditions. The analytical studies are further validated via results from a laboratory prototype.

Formation of magnetic double emulsions under steady and variable magnetic fields from a 3D-printed coaxial capillary device

BackgroundDouble emulsions (DEs) have attracted researchers’ attention to be utilized as a promising platform in biomedical and chemical applications. Several actuation mechanisms have been proposed for the generation of DEs. The conventional DE formation approaches (e.g. two-stage emulsification) suffer from low monodispersity. The electric actuation (i.e. coaxial electrospray technology) has been demonstrated as a controllable method for the DE formation, while the capability of magnetic actuation has not been studied yet. ResultIn the present study, the generation of ferrofluid double emulsions (FDEs), made from water-based ferrofluid as a core and oil as a shell, under the magnetic actuation of a permanent magnet with a steady magnetic field and an electromagnet with DC and pulse width modulation (PWM) magnetic fields was investigated with a simple controllable setup fabricated using 3D printing. The effect of various parameters affecting the FDE formation, such as the fluid flow rates, the magnetic field type, the magnetic flux density, and the PWM frequency and duty cycle, on the FDE formation characteristics, including the inner and outer equivalent diameters, and the formation frequency was studied. Under the steady magnetic field, two regimes of the FDE formation were identified: inertia-dominated and magnet-dominated. SignificanceWireless power-free magnetic actuation provides better control over the FDE formation, enhancing this process by increasing the FDE formation frequency with high monodispersity. The PWM magnetic field offers excellent controllability over the FDE formation with low-volume or no, in some cases, satellite droplets by tuning the PWM frequency and the duty cycle.

An efficient energy management strategy based on heuristic dynamic programming specialized for hybrid electric unmanned delivery aerial vehicles

Large-sized unmanned delivery aerial vehicles (UDAVs) stand out as prominent vertical take-off and landing aircraft, benefiting from integrating a hybrid electric propulsion system (HEPS) to enhance the power-to-weight ratio. Despite this advancement, UDAVs encounter challenges regarding range limitations and the need for swift computational solutions. Addressing these issues necessitates a computationally efficient energy management strategy (EMS) that optimizes power distribution to properly plan engine working points, ultimately aimed at enhancing fuel economy to increase flight range. This study proposes a heuristic dynamic programming (HDP)-based EMS tailored for the HEPS of a large-sized UDAV. In this strategy, the HDP framework is adopted to improve computational efficiency by iteratively updating control variables. To account for the specific flight characteristics, a flight state identifier incorporating selected flight command flags applicable to UDAVs is designed. This identifier aids in predicting velocity changes for different flight states by amalgamating corresponding prediction networks into an integrated velocity prediction network (IVPN). Substituting the model network with IVPN in the HDP framework significantly enhances prediction accuracy and guides power distribution towards optimal results, signifying an efficient EMS specialized for UDAVs. The proposed strategy is evaluated against baseline strategies in designed flight scenarios, highlighting a remarkable 51.37% improvement in prediction accuracy, a noteworthy 6.04% reduction in equivalent fuel consumption, and an impressive 95.81% reduction in global computation time. Finally, the actual applicability of the proposed strategy is validated in a hardware-in-loop test. Consequently, the proposed strategy can provide theoretical support for the efficient energy management of diverse large-sized UDAVs.

The Angular Momentum Unloading of the Asymmetric GEO Satellite by Using Electric Propulsion with a Mechanical Arm

A high-precision attitude control satellite uses an angular momentum exchange device such as a flywheel or a control moment gyro as the actuator for attitude stability control. Once the accumulation of angular momentum exceeds the upper limit of the angular momentum exchange device, the satellite will lose its attitude control ability. Therefore, it is necessary to unload the angular momentum exchange device to ensure the attitude control ability of the satellite platform. The angular momentum accumulation of GEO(Geosynchronous Orbit, GEO) satellites with asymmetric structure can reach 40 Nms per day, and the accumulation speed is more than 20 times that of GEO satellites with symmetrical structure. Therefore, it is necessary to carry out angular momentum unloading for GEO satellites with asymmetric structure every day. The previous method of angular momentum unloading using electric propulsion has weak unloading capacity, which is not suitable for angular momentum unloading of asymmetric satellites. This paper presents a method of angular momentum unloading using a four-joint mechanical arm plus an electric thruster. Large angular momentum unloading with near-zero burn-up can be achieved through the thrust generated by station keeping. In addition, the problem of attitude and orbit coupling control can be solved by controlling the thrust direction of the electric thruster with a mechanical arm.

Electric Vehicles for Smart Village

Today transport accounts for about 60 % of total world oil consumption. This global problem of Energy for propulsion motivates the automotive industry to turn to the electric drive. All major automobile manufacturers attentions are shifted to electrically propelled battery-operated electric vehicles (BEV). Improve the existing power system efficiency, alternate fuels, new materials or alternate power systems like electric vehicles. EV is a road vehicle based on modern electric propulsion consisting of electric machines, power electronic converters, electric energy sources and storage devices, and electronic controllers; EV is a broad concept, including BEV, HEV, FCEV, etc

Review On Evolution and Development of Electric Road Roller

The evolution and development of electric road rollers mark a significant advancement in the construction machinery industry, driven by the imperative of sustainable infrastructure development. This paper provides a comprehensive overview of the historical progression, technological innovations, and current trends shaping electric road rollers. Beginning with the early developments of steam-powered and diesel-driven road rollers, the transition towards electric propulsion systems is traced, highlighting the environmental benefits and operational efficiencies offered by electric models. An electric-applied road roller vehicle represents a sustainable and innovative solution for the construction industry. This eco-friendly equipment utilizes electric power to propel the roller, reducing carbon emissions and noise pollution compared to traditional fossil fuel-powered counterparts. The vehicle's design incorporates advanced technology, such as gear chain mechanism to maximize energy efficiency and extend battery life. With its quiet operation and reduced environmental impact, the electric road roller vehicle demonstrates a promising step towards greener construction practices, contributing to a cleaner and more sustainable future. Top of Form Keywords— Electric Road Roller, Battery, High torque dc motor, propulsion system, gear assembly, etc.

Simulation analysis of local temperature field of electric propulsion slip ring

The temperature at which the carbon brushes and the structure of the rings in the electric propulsion slip ring operate has a crucial influence on the safe and reliable operation of the ship. In order to control the temperature of the local structure of the electric propulsion slip ring, this study established a carbon brush and ring piece model through finite element simulation analysis and designed a five-factor, four-level orthogonal test to derive the sensitivity of the final temperature influence factor: initial temperature > current > wind speed > pressure > speed; the optimal combination of parameters is obtained: initial temperature 35 °C, pressure 25 N, speed 5 rpm, wind speed 0.20 m/s, and current 40 A, and the optimal parameters are substituted for the temperature field simulation. The results show that the relatively large area of temperature is distributed on the carbon brushes with a maximum value of 58.3 °C, which is relatively reasonable in size and distribution; the relatively large area of potential is distributed on the carbon brushes, the maximum value of which is 0.3V The entire potential distribution is symmetrical, indicating a reasonable current path; the relatively large area of current density distribution is on the carbon brushes with a value of 64.7 A/cm2, the entire current density distribution is symmetrical and corresponds to the potential distribution, which, together with the frictional rotation, corresponds to the temperature distribution, indicating that the simulation results have a certain degree of reliability.

Temporally resolved measurement of a force induced by a pulsed water-fuelled magnetron sputtering source

A high-speed solenoid-type pulsed valve is applied to a water-fuelled magnetron sputtering thruster, which can lead a compact and neutralizer-free electric propulsion device by generating a thrust due to the ejection of the sputtered target material, in order to minimize the size of the gas feeding system. The pulsed valve is opened for approximately 5 msec and the gaseous water is introduced into the source via a gas line connected to the source. A dc high voltage is firstly applied between the cathode and the anode; then the discharge is sustained for the period in which a gas pressure enough for the discharge is maintained and a change in the discharge mode is observed during the discharge pulse. To investigate the impact of the mode change on the thrust generation, a temporally resolved measurement of the force is equivalently performed by installing a pulsed voltage power supply and by changing the pulse width of the discharge voltage. The results show the temporal reduction of the thrust-to-power ratio during a pulsed discharge due to the nonlinear correlation between ion energy and sputtering yield. It is suggested that the use of a pulsed valve would be useful for downsizing of the electric propulsion system, while an optimization to properly control the gas flow rate is needed for further development.

The renaissance and evolving design of radical polymerization

Abstract During the 49th World Polymer Congress held 17–21 July 2022 in Winnipeg, Canada, Graeme Moad presented the Stepto Lecture Award [1], describing the mechanism and terminological evolution of reversible deactivation radical polymerization (RDRP) [2, 3, 4], including more recent intricate designs through the use of light and electrical propulsion.

Verification of Interface Compatibility Between Pcdu And High-power Hall Electric Propulsion

For the application of high power Hall electric propulsion system on satellites, a newly developed Power Control and Distribution Unit (PCDU) is applied which owns high voltage and high power. It is used to adjust the power of the solar array and battery to form a fully regulated 100V bus. Then the bus power is delivered to the Power Processing Unit (PPU). To verify the interface compatibility between the PCDU and the PPU load, as well as the rationality of the power supply architecture design, an integrated test of PCDU and PPU has been conducted. The test results shows that the compatibility meets the requirement.

Simulation of liquid cone formation on the tip apex of indium field emission electric propulsion thrusters

Field emission electric propulsion (FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities, making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics (CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic (EHD) equations and the volume of fluid (VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared. The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration. Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases. Moreover, some unstable behavior is observed during the cone formation process.

Investigation of the directional Faraday cup and improvement of the comparison between direct and indirect thrust measurements of a magnetic nozzle ECR thruster

The thrust of an electric propulsion device estimated from electrostatic probe measurements may be different from direct thrust measurements. In order to reduce this discrepancy for electron cyclotron resonance thrusters (ECRT), a new diagnostic is presented: the directional Faraday cup (FCDi). Thanks to a peculiar design, it assesses the angular distribution of ion current density in the plume of plasma thrusters. First, a theoretical model of the angular selectivity of the FCDi is introduced. It is validated with both simulations and experiments. Guidelines are given to use the FCDi in the plume of ECRT. Second, the observed discrepancies between direct thrust measurements made on a thrust stand and indirect ones are reduced when using the FCDi instead of a planar Faraday probe with a guard ring (FPGR). Relative errors come down to 10% with the FCDi, which are compared to 20%–30% observed with the FPGR. An analysis demonstrates that it is not due to the effect of local ion trajectories but comes from the magnitude of the ion current measured. A large sheath in front of the negatively biased FPGR seems to be the cause of this phenomenon. The grounded opening of the FCDi reduces this phenomenon and improves the ion flux measurement accuracy. This new probe, with angular selectivity characteristics, allows for the comparison of the ion flux ejection direction with the magnetic field line and contributes to a better description of ion population dynamic in the magnetic nozzle of the thruster.

AVIOANE ELECTRICE: PROVOCĂRI, OPORTUNITĂȚI, REALIZĂRI, TENDINȚE ACTUALE, PERSPECTIVE DE VIITOR

Electric vehicles are widely used in various transportation applications: automobiles, buses, ships, trains, unmanned aircraft vehicles (UAV), and airplanes. Rising greenhouse gas emissions and the risk of fossil fuel depletion have driven the transition to electric transport, which the European Union aims to reduce substantially by 2035 through renewable energies. In air transport, this transition is more difficult, especially due to the weight of the equipment on board. Without exception, they all use the energy stored in batteries to drive electric motors. In recent years, various hybrid drive systems have developed in aviation, systems based on fuel cells and environmentally friendly energy sources par excellence. Their main advantages are high efficiency, lightweight, modularity, and lack of moving parts. When fueled with hydrogen, they do not produce greenhouse gases, the only reaction products being water and heat. Axial magnetic flux motors have replaced the classic radial magnetic flux electric motors with low weight and volume, efficiency, power, and high torque previously developed for electric vehicles with in-wheel motors and are used without modification. This paper presents an overview of the main problems raised by electric propulsion of aircraft. Also, important achievements and development trends in the field are presented. Finally, a light, electrically powered aircraft configuration is proposed with a hybrid energy source composed of the hydrogen fuel cell, LiIon Polymer battery, and axial magnetic flux motor.

Full lifetime demonstration of a Micro-Cathode-Arc thruster evolution characteristics

Ground lifetime test is the most crucial experiment to assess the performance, reliability, and flight qualification of electric propulsion, and it can bring new insights for understanding the operation characteristics. This work demonstrates a full lifetime test of 140000 cycles on a Micro-Cathode-Arc Thruster (μCAT) with 160 μs charging time and 86 mJ charging energy. A four-probe resistivity measurement method is utilized to investigate variations in the conductive film thickness and resistivity throughout the thruster lifespan. Direct film parameters show that the lifetime of the μCAT can be divided into three stages. In the initial stage, the film thickness decreases by 1.2 μm and the resistivity increases significantly due to the high discharge intensity and intense film ablation; In the steady stage, the change of the film thickness is within 5%, and the resistivity of the film increases slowly from 0.050 Ω·mm to 0.223 Ω·mm. In the end stage, the resistivity exponentially increases from 0.223 Ω·mm to 1.176 Ω·mm, with the increase accounting for 81%, ultimately resulting in the failure of the thruster open circuit. Additionally, the evolution of discharge parameters, and the variation of plume parameters are measured throughout the lifetime. The discharge characteristics also show significant differences in the duration of voltage and current in these three stages. The results of plume shape and plasma parameters are also well consistent with the discharge parameters and film state. These results suggest that, for evaluating the steady stage lifetime of thrusters, the film thickness is the best indicator compared to the variations in resistivity and voltage-current characteristics. For the end stage, the plasma plume morphology, discharge duration, and plume parameters can conveniently and clearly characterize the thruster failures and irregularity.

Design of E-Cycle Drivetrain Configuration Using MATLAB

This research explores the comprehensive dynamics of electric bicycles, focusing on the intricate interplay of rolling resistance, gradient resistance, aerodynamic resistance, and acceleration resistance. Through detailed analysis and mathematical formulations, the study aims to provide insights crucial for optimizing the design and efficiency of electric bicycle propulsion systems. By understanding the various resistive forces affecting performance, engineers and researchers can contribute to the ongoing evolution of sustainable urban mobility solutions Within this research, an in-depth examination unfolds, delving into the nuanced dynamics of electric bicycles. The spotlight is on the complex interaction between rolling resistance, gradient resistance, aerodynamic resistance, and acceleration resistance.

Electric propulsion for lifeboat

This paper presents the integration of the electric propulsion technology in the lifeboat maneuvering system to enhance efficiency, reliability and sustainability. The present lifeboat propulsion system often relies on the internal combustion engine which requires fuel to propel and also has various challenges to face such as emissions, maintenance, and overall environmental impact. This paper delves into the design, economics, ergonomics, engineering challenges and performance assessments associated with the successful implementation of electric propulsion for lifeboats. Special emphasis is given to the research and development of lightweight, high-capacity energy storage systems (ESS) and efficient electric motors which are suitable for the maritime emergency evacuation applications. The features of electric propulsion (EP), such as reduced harmful emissions, lowering maintenance requirements and improving maneuverability draws more attention for this research field. The paper also explores the integration of green energy sources such as solar and wind that can be used to supplement the electric propulsion system which enhance the autonomy and sustainability of the lifeboat during emergencies. This work focuses on the overall advancement of maritime emergency safety equipment and will also help in contributing to make maritime services more eco-friendly by offering a comprehensive analysis of electric propulsion integration in lifeboats, providing insights for further future developments.