Peter J. Schubert

A polyimide-based capacitive humidity sensor

The design of a relative humidity sensor is studied in which the principle of operation is based on the change of dielectric constant of a thin film of polyimide. The design of the sensor is established in such a way that it would be suitable for an integrated-circuit type of fabrication. The studies have shown that the experimental data are described well by the use of the Looyenga equation for dielectric constant behavior coupled with the Dubinin equation to describe the absorption as a function of relative humidity.

Electronics and Algorithms for Rollover Sensing

Rollover sensing and discrimination generally requires an algorithm that monitors vehicle motion and anticipates conditions that will lead to a rollover. In general, a deploy command is required in a time frame such that safety measures can be activated early enough to protect the occupants. A rollover discrimination system will typically include internal motion sensors, vehicle signals from other on-board sensors, and a microprocessor to execute the deployment algorithm. A supplemental signal path is used to arm the system, making it less susceptible to single point component failures. In this chapter we explore basic concepts of rollover sensors and system mechanization, rollover discrimination algorithms, and arming methodology. A simulation environment that models the performance of the system across part tolerance, temperature extremes and component age is used to estimate the scope of expected discrimination performance in the field. A representative selection of real-world events is presented, which can be used to calibrate algorithm parameters to ensure immunity margins and deployment timing for the entire system.

Model-based Development for Event-driven Applications using MATLAB: Audio Playback Case Study

Audio playbacks are mechanisms which read data from a storage medium and produce commands and signals which an audio system turns into music. Playbacks are constantly changed to meet market demands, requiring that the control software be updated quickly and efficiently. This paper reviews a 12 month project using the MATLAB/Simulink/Stateflow environment for modelbased development, system simulation, autocode generation, and hardware-in-the-loop (HIL) verification for playbacks which read music CDs or MP3 disks. Our team began with a “clean slate” approach to playback architecture, and demonstrated working units running production-ready code. This modular, layered architecture enables rapid development and verification of new playback mechanisms, thereby reducing the time needed to evaluate playback mechanisms and integrate into a complete infotainment system. A system simulation environment which included a real-time operating system supports generic mechanism and behavior models, to account for functional differences in playback mechanism from different suppliers. The execution of HIL system simulation required the design and implementation of a communication protocol device which transceives command messages passed between the system environment and the playback mechanism. With this harness, either a generic mechanism model or a hardware unit can be tested, allowing development of mechanism control software before production system hardware platforms are available. Specification-derived test vectors are used as functional tests during development and results have been used during the verification of auto-generated production software against the model. A comprehensive application of executable specs to audio playbacks is successfully demonstrated, including important considerations such as configuration management, model library management, and requirements traceability. Limitations and benefits of this approach are described, along with lessons learned in the implementation of model-based design in the field of automotive electronics. CHALLENGES Audio playback mechanisms (“playbacks”) are typically the most complex building block in a radio. Aggressive price-cutting by playback vendors, and a steady flow of new functions and requirements all drive rapid change. Despite communication standards, playbacks vary in their implementation of IIC, or other protocols. On-board microprocessors within a playback may provide verbose error messages, just a modicum of information, or no feedback at all. Automotive consumers demand interoperability of their music media. Despite the industry standard for Compact Disc Digital Audio (the “Red Book”, IEC 908 – see CDDA trademark at right), many widelyavailable CD burning programs do not comply. Thus, while CD playback software developers strive for universality, there are many radio warranty complaints whose root cause is a non-compliant CD format. Technology advances in consumer electronics are expected in automobiles more rapidly each year. From on-board vinyl record players pioneered by Delco Electronics (the forerunner of Delphi Electronics & Safety) in the 1950’s, today’s mobile audiophiles bring music stored on tape, on CDs (CDDA or MP3), on flash memory sticks, and on portable hard drives (e.g. iPod). In addition, vehicle manufacturers continue to bundle more features into car radios, such as navigation, safety warnings (seat belt reminder), Bluetooth® wireless communications, and satellite radio (e.g. XMTM). These complex devices are no longer just a “radio”, but are more accurately called “infotainment systems”. To handle the rapid change of such complex products, radio suppliers must accelerate software development, testing, and implementation for playbacks. Modular design within a universal architecture is a design goal, using customizable building blocks from a reuse library. The project described herein addresses these needs and successfully demonstrates the ability to rapidly create the control software to operate a new playback.

Technical Feasibility of a Novel Method for Station Keeping

Long-term operation of large orbital structures, such as a solar power satellites (SPS), requires an efficient and replenishable station-keeping system. A novel station-keeping concept, recently awarded a US Patent, introduces an ablative propulsion method based on the slag produced by the processing of regolith. A refractory slag, composed primarily of calcia and magnesia, is the effluent of an isotope separation process. Solar cells, fabricated from silicon, aluminum, and phosphorus elements in lunar regolith, can be delivered to a geostationary orbit (GSO) inside ferrous payload canisters. Emplacement of square solar cells inside a spherical canister leaves space for six spherical sections of refractory slag. In this paper, the technical and economic feasibility are studied for the use of such slag targets to provide reaction mass for a laser ablation station-keeping system. Six degree of freedom torque and translation can be effected when slag targets are placed at extrema of an orbital structure, and pulsed by laser beams. A first order, first principles analysis is used to determine the mass production rate of refractories, the method of forming them into spherical sections for delivery from the moon to GSO, and their installation on a generic SPS. This simple model also includes analysis of the ablation process, characterization of the ejecta (direction, speed, and mass flow rate), and assesses the magnitude of the stationkeeping system vis-a-vis the orbital mechanics requirements for the SPS. This study provides key data needed to construct an overall systems-of-systems analysis of SPS based on lunar materials – an energy technology with significant potential to address baseload terrestrial energy needs.

Energy and Mass Balance for a Cislunar Architecture supporting SSP

For large scale power generation in space, a key economic challenge is launch costs of fabricated components . An attractive alternative is to manufacture solar panels in space, specifically on the moon, where a factory can produce many times its mass in finished goods . This paper presents an architecture for a complete space solar power (SSP) system based on severa l recently developed technologies. Lunar manufactories produce oxygen, silicon, iron, and aluminum, plus a refractory slag. These elements can be formed into single crystal solar panels, thin dielectric films, conductors, and structural members for a lunar infrastructure capable of delivering solar panels to geostationary earth orbit (GEO). There, humans build the power management infrastructure while robots assemble solar panels into an array capable of 10 GW of electric power. An orbiting transmitting ant enna delivers the power to a terrestrial receiving antenna. Mass and energy for each stage of this architecture are presented, with the results that an installation of this size requires at least 2.8 years to build, and requires landing 753 MT delivered to the moon and 202 MT delivered to GEO. Lunar produced mass totals 629 MT, and terrestrial mass required is 2 million MT. Ignoring non recurring engineering costs and component costs, the launch costs of this system are competitive with terrestrial nuclear power on a cost per GW basis. This architecture and supporting technology describe an attractive approach to large -scale development of SSP for the benefit of all mankind.

Fabrication results of a silicon epitaxial lateral overgrowth bipolar transistor without a buried collector

State of the art ,bipolar junction transistor (BJT) switching speed and unit gain frequency (f are limited by the transit times of carriers through the device and 8y the arasitic capacitances and resistances associated with the fabrication technology. The Epitaxial Lateral Overgrowth BJT (ELO/BJT) structure reduces parasitic capacitances by dielectrlcally isolating the low-reslstance collector region from the substrate and the base region. This obvlates the need for a traditional buried la er, with its attendant parasitic collector-substrate capacitance, yet the device is fuyly isolated Parasitic resistances are reduced by keeping current paths short, and placing the highly-doped extrinsic collector and extrinsic base regions in close proximity to the active device regions. As seen in Flgure 1 , the oxide layer covering the lateral portions of the overgrowth rovldes the dielectric isolation, and the field oxide provides inter device isolation. 7 he stacked nature of the two overgrowths allow collector, base, and emitter contacts to be spaced as closely as lithography allows, facilitating a small geometry device.

Lunar-sourced GEO Powersats: An Integrated ISRU System

Solar power satellites (powersats) can be built almost entirely from lunar resources. When C-class asteroids are also included as ore bodies a complete powersat can be built through in situ resource utilization (ISRU) given appropriate processing and transportation technology. This article provides an in-depth overview of the technical feasibility and economic viability of lunar construction and operations for powersat component construction and delivery to geostationary earth orbit (GEO). Techno-economic analysis suggests a return on investment in seven years assuming a three percent discount rate. Electrical power collected in GEO and beamed to terrestrial receivers by the powersats can be sold as baseload power in the wholesale electricity market to generate revenue. This work presents a complete concept of operations from initial rocket launches to regolith harvesting through transport to GEO. Lunar infrastructure can be constructed of modules to optimize size and weight for launch costs. Future growth can be derived from using ISRU to build additional processing bases. A scaleup in this manner can provide 22% of the world’s energy needs by the end of a 20-year period. This work builds upon previous studies and completes the architectural description of predominantly lunar-sourced GEO powersats.

Administrative Policy for Stochastic Democracy

Prior studies of stochastic democracy have compared it to other forms of governance, demonstrated how to scale up or scale down as population changes, and developed an algorithm for start-up on Day 1. Left unanswered is the administrative policy for regulating the statutes developed by the legislative bodies. As the aim of stochastic democracy is design of a corruption-resistance form of managing human affairs the implementation of the activities of the government must also be robust against undue influence, bribery, and abuse of power. Decision-makers in a stochastic democracy by design cannot be “career” politicians, however, the bureaucrats of the government agencies or departments or ministries are advantageously retained across the changes in the legislative bodies. This quality invites corruption, the answer to which cannot be simply to apply oversight or policing. In this paper is developed an integrated structure which supplants the Byzantine-derived corporate-style hierarchy. Seven principles are applied to the bureaucracy and their integration and practice described herein as administrative policy, the principles being: transparency of regulatory process; not-less-than time limits; disclosure of change proposers; inclusion of economic externalities; open debate and notices of intent; chairmanship and participant selection; and periodic but stochastic changes in the number of agencies at each level of governance. This latter enforces either consolidation or expansion, within high and low limits, the reorganization of which will shuffle the reporting structure of the regulatory bureaucracy and disrupt entrenched habits and possible corrupting schemes. When complementing the legislative functions this work rounds-out the formation of a corruption-resistant, scalable form of truly representative governance for space habitats and societies of arbitrary size.

Complete Hydrogen Storage System by ISRU

New technologies make it possible to build in space a complete hydrogen storage system using ISRU methods and techniques. Hydrogen can be stored in a solid-state form on the surface atoms of high surface area matrices such as those of porous silicon. Silicon is abundant in regolith and can be purified using a purely mechanical means which results in particulates in the scale range of tens of nanometers. Reagents used to porosify these nano-particles can be regenerated thermally to essentially eliminate the need for resupply from earth. Catalysts are needed to divide dihydrogen gas into atomic hydrogen for solid-state adsorption and to mediate the temperatures and pressures of charge and discharge into ranges easily achievable with simple equipment. Recent research has identified the utility of non-platinum group catalyst materials which are widespread on the moon. Rapid discharge, needed for propulsion, is possible with infra-red illumination at wavelengths which pass through pure silicon but are absorbed by the silicon-hydrogen bond. Such IR emitters can be fabricated by embossing of silica and additive manufacturing of metals. Control and power electronics can be fabricated using a patented process designed for space operations, and built on either silicon or silicon carbide substrates derived from regolith. Bringing these five technologies together for the first time allows a system which can be fed with moderate pressure gaseous hydrogen at moderate temperatures, stored for long durations with minimum loss, then released upon demand across a wide range of controllable rates. Such a system can displace the need for cryogenic hydrogen storage. Being suitable to bottom-up fabrication using only in-space materials makes this a “green” ISRU technology to store hydrogen for fuel cells, rocket engines, and chemical processes.

Distributed Bio-Hydrogen Refueling Stations

Hydrogen fuel cell cars are now available for lease and for sale. Renewable hydrogen fuel can be produced from water via electrolysis, or from biomass via gasification. Electrolysis is power-hungry with high demand from solar or wind power. Gasification, however, can be energy self-sufficient using a recently-patented thermochemical conversion technology known as I-HPG (indirectly-heated pyrolytic gasification). I-HPG produces a tar-free syngas from non-food woody biomass. This means the balance of plant can be small, so the overall system is economical at modest sizes. This makes it possible to produce renewable hydrogen from local agricultural residues; sufficient to create distributed refueling stations wherever there is feedstock. This work describes the specifics of a novel bio-hydrogen refueling station whereby the syngas produced has much of the hydrogen extracted with the remainder powering a generator to provide the electric power to the I-HPG system. Thus the system runs continuously. When paired with another new technology, moderate-pressure storage of hydrogen in porous silicon, there is the potential to also power the refueling operation. Such systems can be operated independently. It is even possible to design an energy self-sufficient farm where all electric power, heat, and hydrogen fuel is produced from the non-food residues of agricultural operations. No water is required, and the carbon footprint is negative, or at least neutral.