scholarly journals Micro Satellite Orbital Boost by Electrodynamic Tethers

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 916
Author(s):  
Peter Yao ◽  
Timothy Sands
Keyword(s):  
Aerodynamic Drag ◽  
Equations Of Motion ◽  
Translational Motion ◽  
Electrical Power ◽  
Moment Equation ◽  
Low Earth Orbit ◽  
Electrodynamic Tether ◽  
Power Requirement ◽  
Power Draw ◽  
Low Earth Orbits

In this manuscript, a method for maneuvering a spacecraft using electrically charged tethers is explored. The spacecraft’s velocity vector can be modified by interacting with Earth’s magnetic field. Through this method, a spacecraft can maintain an orbit indefinitely by reboosting without the constraint of limited propellant. The spacecraft-tether system dynamics in low Earth orbit are simulated to evaluate the effects of Lorentz force and torques on translational motion. With 500-meter tethers charged with a 1-amp current, a 100-kg spacecraft can gain 250 m of altitude in one orbit. By evaluating the combined effects of Lorenz force and the coupled effects of Lorentz torque propagation through Euler’s moment equation and Newton’s translational motion equations, the simulated spacecraft-tether system can orbit indefinitely at altitudes as low as 275 km. Through a rare evaluation of the nonlinear coupling of the six differential equations of motion, the one finding is that an electrodynamic tether can be used to maintain a spacecraft’s orbit height indefinitely for very low Earth orbits. However, the reboost maneuver is inefficient for high inclination orbits and has high electrical power requirement. To overcome greater aerodynamic drag at lower altitudes, longer tethers with higher power draw are required.

Process design and equipment selection for optimized steam and power concepts – the “zero” process steam sugar factory

2020 ◽  
pp. 40-50
Author(s):  
Boris Morgenroth ◽  
Thomas Stark ◽  
Julian Pelster ◽  
Harjeet Singh Bola
Keyword(s):  
Process Design ◽  
Sugar Industry ◽  
Electrical Power ◽  
Power Requirement ◽  
Equipment Selection ◽  
Good Potential ◽  
Set Up ◽  
The Right ◽  
Key Aspects ◽  
Steam Drying

Optimization of process steam requirement in order to maximize sugar recovery and export power along with manpower optimization is a must for sugar factories to survive under difficult conditions and to earn additional revenues. The process steam demand of greenfield and revamped plants has been reduced to levels of 32–38% from originally more than 50% steam on cane in the case of the brownfield plants. In addition, significant improvement in the power requirement of the plants has been achieved. Bagasse drying offers a good potential to improve the power export. Different available concepts are compared with a focus on bagasse steam drying and low temperature bagasse drying. In order to set up an optimized highly efficient plant or to optimize an existing plant to achieve competitive benchmarks, good process design and the right equipment selection are very important. Experience has been gained with multiple stage or double effect crystallization in the beet sugar industry offering further steam optimization potential. Vapour recompression is also an option to substitute live steam by electrical power. This even provides options to reduce the steam demand from the power plant for the sugar process down to zero. Key aspects concerning the process design and equipment selection are described.

scholarly journals QUANTITATIVE THERMOGRAPHY FOR ELECTIC MOTOR EFFICIENTY DIAGNOSIS

2011 ◽  
Author(s):  
Matt Narrol ◽  
Warren Stiver
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Environmental Sustainability ◽  
Thermal Imaging ◽  
Mechanical Load ◽  
Global Climate ◽  
Electrical Power ◽  
Motor Efficiency ◽  
Power Draw ◽  
Quantitative Thermography

Global climate change is one of the most important challenges and threats to economic, social and environmental sustainability.. Reducing electrical power demand is an important and necessary step in lessening global climate change and preserving our energy resources for future generations. The objective of this work is the development and demonstration of a quantitative thermographic system to rapidly and noninvasively determine in-use electrical motor efficiency. The development has included testing of four motors in a controlled laboratory setting. This setting permits the complete and steady measurement of electrical power draw, mechanical load applied in addition to the thermal imaging. It provides a reliable means to validate the quantitative thermographic system. The thermographic technique proved to be reliable for all motors at 60% or more of full load.

Stability analysis of rotor whirl under nonlinear internal friction by a general averaging approach

2016 ◽  
Vol 23 (5) ◽  
pp. 808-826 ◽  
Author(s):  
Francesco Sorge
Keyword(s):  
Internal Friction ◽  
Equations Of Motion ◽  
Translational Motion ◽  
Stable Limit ◽  
Rotor Shaft ◽  
Shaft System ◽  
Flexible Supports ◽  
Asymmetric Rotor ◽  
Nonlinear Equations Of Motion ◽  
Shrink Fit

The two main sources of internal friction in a rotor-shaft system are the shaft structural hysteresis and the possible shrink-fit release of the assembly. The internal friction tends to destabilize the over-critical rotor running, but a remedy against this effect may be provided by a proper combination of some external damping in the supports and an anisotropic arrangement of the support stiffness, or at most by the support damping alone, depending on the system geometry. The present analysis reported here considers a general asymmetric rotor-shaft system, where the rotor is perfectly rigid and is constrained by viscous–flexible supports having different stiffnesses on two orthogonal planes. The internal friction is modelled by nonlinear Coulombian forces, which counteract the translational motion of the rotor relative to a frame rotating with the shaft ends. The nonlinear equations of motion are dealt with using an averaging approach based on the Krylov-Bogoliubov method with some adaptation to address the multi-degree-of-freedom nature of the problem. Stable limit cycles may be attained by the overcritical whirling motions, whose amplitudes are inversely proportional to the external dissipation applied by the supports. A noteworthy result is that the stiffness anisotropy of the supports is recognized as beneficial in reducing the natural whirl amplitudes, albeit mainly in the symmetric configuration of the rotor at the mid span and, to a rather lesser extent, in the asymmetric configuration, which then requires a stronger damping action in the supports.

Dynamic Modelling of a Three Degree-of-Freedom Planar Platform-Type Manipulator

1997 ◽  
Author(s):  
Hazem A. Attia ◽  
Maher G. Mohamed
Keyword(s):  
Differential Equations ◽  
Efficient Solution ◽  
Equations Of Motion ◽  
Translational Motion ◽  
Dynamic Modelling ◽  
Degree Of Freedom ◽  
Constraint Forces ◽  
Dynamic Formulation ◽  
System Of Particles ◽  
Three Degree Of Freedom

Abstract In this paper, the dynamic modelling of a planar three degree-of-freedom platform-type manipulator is presented. A kinematic analysis is carried out initially to evaluate the initial coordinates and velocities. The dynamic model of the manipulator is formulated using a two-step transformation. Initially, the dynamic formulation is written in terms of the Cartesian coordinates of a dynamically equivalent system of particles. Since there is no rotational motion associated with a particle, then the differential equations of motion are derived by applying Newton’s second law to study the translational motion of the particles. The constraint forces between the particles are expressed in terms of Lagrange multipliers. Then, the differential equations of motion are written in terms of the relative joint variables. This leads to an efficient solution and integration of the equations of motion. A numerical example is presented and a computer program is developed.

U.S. Freight Rail Fuel Efficiency: 1920-2015 Review and Discussion of Future Trends

2019 ◽  
Author(s):  
Michael E. Iden
Keyword(s):  
World War Ii ◽  
New Technologies ◽  
Aerodynamic Drag ◽  
Energy Content ◽  
Fuel Efficiency ◽  
Heavy Duty ◽  
Power Requirement ◽  
Steel Wheel ◽  
Heavy Duty Truck ◽  
Percent Improvement

U.S. freight railroads produce about 40 percent of freight gross ton-miles while consuming only about 1/20th of the total U.S. diesel fuel1. Compared to heavy-duty trucks, freight railroads have significant energy (and emissions) advantages including the low coefficient of friction of steel wheel-on-rail (compared to rubber tires-on-pavement) and multiple-vehicle trains. However, improved heavy-duty truck technologies are being federally-funded and developed which may create some challenges to freight rail’s long-standing environmental (and economic) advantage in certain transportation markets and corridors. This paper reviews U.S. freight rail fuel efficiency (measured in gallons of fuel per thousand gross ton-miles) from 1920 to 2015, using published records from the former Interstate Commerce Commission (ICC) archived and made available by the Association of American Railroads (AAR). All freight locomotive energy consumption (all types of coal, crude oil, electricity kilowatt-hours and diesel fuel) are converted into approximations of diesel gallons equivalent based on the nominal energy content of each locomotive energy type, in order to show the effect of transitioning from steam propulsion to diesel-electric prior to 1960 and the application of other new technologies after World War II. Gross ton-miles (rail transportation work performed) will similarly be tracked from historic ICC and AAR records. Annual U.S. freight rail fuel efficiency is calculated and plotted by dividing total calculated diesel gallons equivalent (DGe) consumed by gross (and by lading-only net) ton-miles produced. New technologies introduced since 1950 which have likely contributed to improvements in freight rail fuel efficiency (such as introduction of unit coal trains, distributed power, alternating current locomotives, etc) will also be discussed and assessed as to relative contribution to fuel efficiency improvements. The paper includes a discussion about U.S. freight rail fuel efficiency compared to heavy-duty truck fuel efficiency, with comments on projected improvements in heavy-duty truck technologies and fuel efficiency. A conclusion is that U.S. freight railroads and equipment suppliers need to be more aware of projected heavy-duty truck fuel efficiency improvements and their potential for erosion of some aspects of traditional railroad competitiveness. Numerous suggested action plans are discussed, with particular focus on reducing the aerodynamic drag (a delta velocity-squared factor in train resistance and power requirement) of double-stack container trains. Last, this paper discusses possible courses of action for U.S. freight railroads to achieve fuel efficiency improvements greater than the historic ∼1 percent improvement achieved over the past 50 years. If freight rail is to remain economically competitive vis a vis heavy duty trucking, railroads will have to identify, evaluate and implement new technologies and/or new operating practices which can help them achieve fuel efficiency improvements matching (or exceeding) those projected for heavy trucks over the next 7-to-12 years. A specific example for improving fuel efficiency of double-stack container trains is discussed. Failure to address the future of freight rail fuel efficiency is likely not an option for U.S. railroads.

Robotic Gripper for Payload Capture in Low Earth Orbit

2016 ◽  
Author(s):  
Giancarlo Genta ◽  
Marco Dolci
Keyword(s):  
Computer Aided Design ◽  
Robotic Manipulator ◽  
Low Earth Orbit ◽  
Distal Phalanx ◽  
Study Phase ◽  
System Control ◽  
Robotic Hand ◽  
End Effector ◽  
Manipulator Design ◽  
Low Earth Orbits

The consensus to a study phase for an IXV (Intermediate eXperimental Vehicle) successor, a preoperational vehicle called PRIDE (Programme for Reusable In-orbit Demonstrator in Europe), has been recently enlarged, as approved during last EU Ministerial Council. One of the main project task consists in developing PRIDE to conduct on orbit servicing activity with no docking. PRIDE would be provided with a robotic manipulator system (arm and gripper) able to transfer payloads, such as scientific payloads, from low Earth orbiting platforms to PRIDE payload bay. The platform is a part of a space tug designed to move small satellites and other payloads from Low Earth Orbits (LEO) to Geostationary orbit (GEO) and viceversa. A study on this robotic technology is here presented. This research is carried out by Politecnico di Torino and Thales Alenia Space Italy (Grasping Manipulator Design), and by Thales Alenia Space Italy and Amet (PRIDE Robotics System Design). The system configuration of the robotic manipulator is first described in terms of volumes and masses. The assumed housing payload bay requirements in terms of volume (<100 l) and mass (<50 kg) combined with the required overall arm dimensions (4 m length), as defined following the stated mission scenario, and mass of the payload (5–30 kg) force to developing an innovative robotic manipulator with the task-oriented end effector. It results in a 7 degree-of-freedom arm to ensure a high degree of dexterity and a dedicate end-effector designed to grasp the payload interface. The gripper concept here developed consists in a multi-finger hand able to lock both translational and rotational payload degrees of freedom through an innovative under actuation strategy to limit its mass and volume. While in the literature in usual actuation architectures, underactuated systems have been realized where the first (nearest) phalanx closure led afterwards to the closure of the second (distal) one using the loading of a torsional springs and mechanical linkages, this system presents a new underactuation strategy. In this case the distal phalanx closes before the nearest one, allowing to grasp the handle side and limiting the handle length and volume. This concept will allow the distal phalanx to move independently from the nearest one. A configuration study on the payload handle interface has also been performed. Moreover, trade-off studies, computer aided design models, multibody and structural analysis of the whole system are shown to prove its feasibility. Finally, the concept of system control architecture, organized in three main blocks is defined: the Control Overall System Block, the Control Arm Block and the Control Robotic Hand Block.

Space Environment Effect on Fluorinated Polymers

2003 ◽  
Vol 792 ◽  
Author(s):  
M. Chipara ◽  
D. L. Edwards ◽  
J. Zaleski ◽  
B. Hoang ◽  
B. Przewoski ◽  
...  
Keyword(s):  
Atomic Oxygen ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Fluorinated Polymers ◽  
Space Applications ◽  
Environment Effect ◽  
Low Altitude ◽  
Low Earth Orbits ◽  
Degradation Of Materials ◽  
Earth Orbits

ABSTRACTThe effects of the space environment on polytetrafluorethylene and some fluorinated polymers, copolymers, and blends are critically reviewed. It is shown that in low altitude orbits such as Low Earth Orbit and Geostationary Orbit the presence of both ionizing radiation and atomic oxygen triggers a synergetic degradation of materials based on fluorinated polymers. The behavior is due to the lability of the in-chain alkyl radical to oxygen attack. It is concluded that fluorinated polymers should not be used as materials for space applications, as long as the mission implies low Earth orbits.

Nonlinear Dynamics of Piezoelectric Cantilever Energy Converters Through Perturbation Theory and Experimental Analysis

2014 ◽  
Author(s):  
Paulo S. Varoto ◽  
Andreza T. Mineto
Keyword(s):  
Energy Harvester ◽  
Resonance Condition ◽  
Equations Of Motion ◽  
Electrical Power ◽  
Ambient Vibration ◽  
Vibration Energy Harvester ◽  
Piezoelectric Energy ◽  
Structural Nonlinearities ◽  
Beam Type ◽  
Tip Mass

It is known that the best performance of a given piezoelectric energy harvester is usually limited to excitation at its fundamental resonance frequency. If the ambient vibration frequency deviates slightly from this resonance condition then the electrical power delivered is drastically reduced. One possible way to increase the frequency range of operation of the harvester is to design vibration harvesters that operate in the nonlinear regime. The main goal of this article is to discuss the potential advantages of introducing nonlinearities in the dynamics of a beam type piezoelectric vibration energy harvester. The device is a cantilever beam partially covered by piezoelectric material with a magnet tip mass at the beam’s free end. Governing equations of motion are derived for the harvester considering the excitation applied at its fixed boundary. Also, we consider the nonlinear constitutive piezoelectric equations in the formulation of the harvester’s electromechanical model. This model is then used in numerical simulations and the results are compared to experimental data from tests on a prototype. Numerical as well as experimental results obtained support the general trend that structural nonlinearities can improve the harvester’s performance.

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