Conceptual mechanization studies for a horizon definition spacecraft electrical power subsystem
Solar cell-battery electrical power subsystem for horizon definition spacecraft
SOLAR CELL↗
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Microwave power transmission system studies. Volume 3, section 8: Mechanical systems and flight operations
The efforts and recommendations associated with preliminary design and concept definition for mechanical systems and flight operations are presented. Technical discussion in the areas of mission analysis, antenna structural concept, configuration analysis, assembly and packaging with associated costs are presented. Technology issues for the control system, structural system, thermal system and assembly including cost and man's role in assembly and maintenance are identified. Background and desired outputs for future efforts are discussed.
Maynard, O. E.↗
Cost and sizing sensitivities for the solar power satellite
A summary is provided of the characteristics and error parameters of the reference microwave transmission system for the solar power satellite (SPS). The relative importance of electrical and mechanical tolerances upon scattered microwave power and electrical costs is investigated. It is found that small increases in efficiency and/or reduction of losses (less than one percent) can improve the revenue from a single satellite over its 30-year lifetime by several hundred million dollars. Attention is given to a system definition, cost sensitivities for the reference system, the klystron dc-RF conversion efficiency, the transmitting antenna, the rectenna collection efficiency, system sizing tradeoffs, a cost analysis, and multiple antennas.
Monford, L.↗
Obtaining an electrical output from a mechanical flowmeter
Circuit using optical sensor, low power counting electronics, oneclip digital-to-analog converter and operational amplifier converts mechanical readout of water, gas, fuel-oil or power meter to analog signal suitable for online processings.
Powers, W. T.↗
Development of an Unmanned Mobile Current Turbine Platform: Preprint
The design and development of a prototype unmanned mobile floating platform, equipped with a custom low-flow marine current turbine for autonomously seeking and harnessing tidal/coastal currents is described. The platform is an unmanned surface vehicle in the form of a catamaran with two electric outboard motors and capabilities for autonomous navigation. An undershot water wheel, aided by a custom flow concentrator, has been selected as the basic design for the marine current turbine, which is mounted on the stern of the unmanned surface vehicle platform. The concept of operation is that the platform would navigate to a designated marine current resource, autonomously anchor at the location, align itself in the current and deploy the current turbine using a custom cable-lift deployment mechanism. As the turbine harnesses the local current, an onboard power-take-off device converts the harnessed mechanical energy to electricity which is stored in onboard batteries. Considerations of deployment in tidal and coastal waters required obtaining the necessary environmental permits for conducting in-water testing; developing required mitigation measures in protecting local wildlife and their habitats; and identifying potential in-water test sites and surveying them for their suitability in terms of the current resource, bottom type, water depth, and local boat traffic. The design and development of the turbine and the results of initial in-water testing are discussed. The potential for scaling up the system for extended capacity is presented.
ENGINEERING,TIDAL AND WAVE POWER↗
Electrical Prototype Power Processor for the 30-cm Mercury electric propulsion engine
An Electrical Prototpye Power Processor has been designed to the latest electrical and performance requirements for a flight-type 30-cm ion engine and includes all the necessary power, command, telemetry and control interfaces for a typical electric propulsion subsystem. The power processor was configured into seven separate mechanical modules that would allow subassembly fabrication, test and integration into a complete power processor unit assembly. The conceptual mechanical packaging of the electrical prototype power processor unit demonstrated the relative location of power, high voltage and control electronic components to minimize electrical interactions and to provide adequate thermal control in a vacuum environment. Thermal control was accomplished with a heat pipe simulator attached to the base of the modules.
Biess, J. J.↗
Human Powered Centrifuge
A human powered centrifuge has independently established turntable angular velocity and human power input. A control system allows excess input power to be stored as electric energy in a battery or dissipated as heat through a resistors. In a mechanical embodiment, the excess power is dissipated in a friction brake.
Mulenburg, Gerald M.↗
20 kHz, 25 kVA node power transformer
The electrical and mechanical design information and the electrical and thermal testing performed on the 440-208-V rms, 20-kHz, 25-kVa prototype node transformer are summarized. The calculated efficiency of the node transformer is 99.3 percent based on core loss and copper loss test data, and its maximum calculated load regulation is 0.7 percent. The node transformer has a weight of 19.7 lb and has a power density of 0.8 lb/kW. The hot-spot temperature rise is estimated to be 33 C above the cold plate mounting base. This proof-of-concept transformer design is a viable candidate for the space station Freedom application.
Hussey, S.↗
Lifetime renormalization of driven weakly anharmonic superconducting qubits. II. The readout problem
Recent experiments in superconducting qubit systems have shown an unexpectedly strong dependence of the qubit relaxation rate on the readout drive power. This phenomenon limits the maximum measurement strength and thus the achievable readout speed and fidelity. We address this problem here and provide a plausible mechanism for drive-power dependence of relaxation rates. To this end we introduce a two-parameter perturbative expansion in qubit anharmonicity and the drive amplitude through a unitary transformation technique introduced in Part I. This approach naturally reveals number-nonconserving terms in the Josephson potential as a fundamental mechanism through which applied microwave drives can activate additional relaxation mechanisms. Here, we present our results in terms of an effective master equation with renormalized state- and drive-dependent transition frequency and relaxation rates. Comparison of numerical results from this effective master equation to those obtained from a Lindblad master equation which only includes number-conserving terms (i.e., Kerr interactions) shows that number-nonconserving terms can lead to significant drive-power dependence of the relaxation rates. The systematic expansion technique introduced here is of general applicability to obtaining effective master equations for driven-dissipative quantum systems that contain weakly nonlinear degrees of freedom.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Flexible polyacrylamide substrata for the analysis of mechanical interactions at cell-substratum adhesions
We have described a powerful tool for the study of mechanical interactions between cells and their physical environment. Although the approach has already been used in a variety of ways to measure traction forces and to characterize active and passive responses of cultured cells to mechanical stimulation, it can be extended easily and combined with other microscopic approaches, including fluorescent analog imaging (Beningo et al., 2001), photobleaching, calcium imaging, micromanipulation, and electrophysiology. This method will be particularly useful for studying the functions of various components at focal adhesions, and the effects of mechanical forces on focal adhesion-mediated signal transduction. In addition, the method can be extended to a 3D setting, e.g., by sandwiching cultured cells between two layers of polyacrylamide to create an environment mimicking that in the tissue of a multicellular organism. Whereas chemical interactions between cells and the environment have been investigated extensively, many important questions remain as to the role of physical forces in cellular functions and the interplay between chemical and physical mechanisms of communication. The present approach, as well as other approaches capable of probing physical interactions, should fill in this important gap in the near future.
NASA Discipline Cell Biology↗
Design and Analysis of an Integral MPPT Control Law for Wave Energy Conversion Systems
In this paper, we propose an integral-based maximum power point tracking (MPPT) algorithm for point absorber wave energy conversion (WEC) systems. A permanent magnet synchronous generator (PMSG) is coupled to the point absorber and its drive implements the proposed MPPT control. While the rotating frame of reference of the PMSG implements power control, the slower mechanical frequency of the incident waves are processed with an additional transformation that yields another set of dc dynamics. The computed dc power in the new reference frame, which is focused on slow wave dynamics, is input to the MPPT control law that tunes the emulated resistance of the machine drive to extract peak power from the wave absorber device. We derive a stability condition for the proposed controller and validate our control design on a simulated 10kW system.
wave energy, maximum power point tracking (MPPT), ↗
Concepts and cost trade-offs for land vehicle antennas in satellite mobile communications
Several antenna design concepts, operating at UHF (821 to 825 MHz transmit and 866 to 870 MHz receive bands), with gain ranging between 6 and 12 dBic, that are suitable for land mobile vehicles are presented. The antennas may be used within CONUS and ALASKA to communicate to and from a geosynchronous satellite. Depending on the type of steering mechanism, the antennas are broken down into three categories; (1) electronically scanned arrays with phase shifters, (2) electronically switched arrays with switchable power dividers/combiners, and (3) mechanically steered arrays. The operating characteristics of two of these design concepts, one a conformal antenna with electronic beam steering and the other a nonconformal design with mechanical steering, were evaluated with regard to two and three satellite system. Cost estimates of various antenna concepts were made and plotted against their overall gain performance.
Haddad, H. A.↗
Dual shear plate power processor packaging design
The use of solar electric propulsion (SEP) for spacecraft primary propulsion imposes an extreme range of operational and environmental design requirements associated with the diversity of missions for which solar electric primary propulsion is advantageous. One SEP element which is particularly sensitive to these environmental extremes is the power processor unit (PPU) which powers and controls the electric ion thruster. An improved power processor thermal-mechanical packaging approach, referred to as dual shear plate packaging, has been designed to accommodate these different requirements with minimum change to the power processor design. Details of this packaging design are presented together with test results obtained from thermal-vacuum and structural-vibration tests conducted with prototype hardware.
Franzon, A. O.↗
An Engineered Multifunctional Composite for Passive Sensing, Power Harvesting, and In Situ Damage Identification with Enhanced Mechanical Performance
A multifunctional fiber-reinforced composite with passive self-sensing, energy-harvesting, and damage detection capabilities is presented. In this work, barium titanate piezoelectric microparticles are deposited on basalt fibers by a scalable, low-cost, environmentally friendly continuous feed-through process. The resulting composite derives a superior interlaminar shear strength from the microparticle-modified fiber–matrix interfaces. The composite also demonstrates passive self-sensing capabilities that produce electrical signals proportional to various dynamic loading events. Vibration and strain-controlled experiments are performed on composite beams to quantify the sensitivity and power output as a function of input acceleration and strain. Furthermore, these composite-generated electrical signals are used to identify in situ damage initiation for structural health monitoring to inform composite damage prior to structural failure. In brief, this truly multifunctional composite simultaneously displays a sensitivity of 0.5–2.6 mV g -1 at a resolution of 0.045–0.20g (g = gravitational acceleration), energy harvesting in the range of nW cc -1 , and prediction of early damage by exhibiting 0.017–1.17 mV peaks in voltage–time history profiles while assuring ≈20% improved interlaminar shear strength.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Ordered Particle Packing in Dense TRISO/SiC Fuel Elements and Preliminary Assessment of Neutronic and Thermomechanical Characteristics
Detailed analysis of the particle distribution in Transformational Challenge Reactor fuel elements indicates that particle packing is not random; instead, it follows a relatively ordered structure near fuel element surfaces. Discrete particle neutronic simulations indicate that the core reactivity is not impacted when assuming homogenization of particles with the silicon carbide matrix. However, the neutronic power distribution resulting from the ordered packing structure indicates that the highest-power particles reside at the top and bottom of the fuel elements and nearest the YH 1.85 moderator rods. The power distribution results were applied to thermo-mechanical simulations using mesh-based power distributions. Previous results indicated high stress at the bottom of the fuel element, where packing is most ordered. Additionally, to reduce this stress concentration, additively manufactured protrusions were added to the bottom of a test fuel element to disrupt dense particle packing. These protrusions reduced the overall power peaking, but the thermomechanical simulations did not indicate a significant change in the fuel element’s maximum stress or failure probability.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Space shuttle flight readiness firing dress rehearsal for STS-1
The static firing of the Space Shuttle Main Engine in preparation for the launch of the Enterprise Orbiter is discussed. The following were also tested: structures and mechanics; thermal design integration; propulsion and power; avionics and software; guidance, navigation, and control; mechanical systems; communications and tracking; and integrated ground systems.
Riles, W. L.↗
Weight and power savings shaft encoder interfacing techniques for aerospace applications
Many aerospace applications for shaft angle digitizers such as optical shaft encoders require special features that are not usually required on commercial products. Among the most important user considerations are the lowest possible weight and power consumption. A variety of mechanical and electrical interface techniques that have large potential weight and power savings are described. The principles to be presented apply to a wide variety of encoders, ranging from 16 to 22 bit resolution and with diameters from 152 to 380 mm (6 to 15 in.).
Breslow, Donald H.↗
Advanced eLectrical Bus (ALBus) CubeSat: From Build to Flight
The Advanced eLectrical Bus (ALBus) CubeSat project is a technology demonstration mission of a 3-U CubeSat with an advanced, digitally controlled electrical power system capability and novel use of Shape Memory Alloy (SMA) technology for reliable deployable solar array mechanisms. The objective of the project was to advance the state of power management and distribution (PMAD) capabilities to enable future missions requiring flexible and reliable power systems with higher output power capabilities. The goals of the mission were to demonstrate 100W distribution to a target electrical load, respond to continuous and fast transient power requirements, and show reliable deployment of solar arrays and antennas utilizing re-settable SMA mechanisms. The power distribution function of the ALBus PMAD system is unique in the total power to target load capability. Power is distributed from batteries to provide 100W of power directly to a resistive load. The deployable solar arrays utilize NASA Glenn Research Center’s Nickel-Titanium-Palladium-Platinum high-temperature SMAs for the retention and release mechanism, and a super-elastic binary NiTi alloy for the hinge component. The deployable solar array hinge design features the utilization of SMA material properties for a dual purpose. First, the hinge uses the super-elastic SMA properties to provide the spring force to deploy the arrays. Second, the electrical conductivity properties of the SMA enables the design to provide clean conduits for power transfer from the deployable arrays to the power management system. This eliminates the need for electrical harnesses between the arrays and the PMAD system in the ALBus system design. The uniqueness of the SMA retention and release mechanism design is the ability to reset the mechanism and reuse the same hardware. This allow functional tests of the mechanisms before flight with no degradation of performance and flying the hardware that is tested. The project launched as part of the CubeSat Launch Initiative Educational Launch of Nanosatellites (ELaNa) XIX mission on Rocket Lab’s Electron in December 2018. This paper summarizes the final launched design of ALBus and lessons learned from the technology and overall project from development through flight.
Deboshri Sadhukhan↗