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Technical Paper

“Model Based Predictive Control of MELISSA Photobioreactors. Steady State Determination”

Mathematical modeling and control of artificial ecosystems, such as MELISSA, require first the study of physical and biological characteristics in optimal and limiting conditions. Following the previous determination of the stoichiometric equations (Spirulina compartment) and regarding the two phototrophic compartments of MELISSA (Rhodospirillaceae and Spirulina), we have first to focus our control study on the growth kinetics for the light source. In this paper, we recall the theoretical equations of microbial growth kinetics and emphasise the problem of the light transfer in a photobioreactor. We present their adaptations to our pilot plant taking into account technological and biological specifics (lamp spectrum, working illuminated volume, growth rate,…). We then develop the principles and structure of the control system and describe tests of both the hardware and software for several steady state configurations.
Technical Paper

eROSITA Camera Low Temperature Thermal Control

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is a powerful X-ray telescope under development by the Max-Planck-Institut für extraterrestrische Physik (MPE) in Garching, Germany. eROSITA is the core instrument on the Russian SRG1 mission which is planned for launch in 2011. It comprises seven nested Wolter-I grazing incidence telescopes, each equipped with its own CCD camera. The mirror modules have to be maintained at 20°C while the cameras are operated at -80°C. Both, mirrors and CCDs have to be kept within tight limits. The CCD cooling system consists of passive thermal control components only: two radiators, variable conductance heat pipes (VCHP) and two special thermal storage units. The orbit scenario imposes severe challenges on the thermal control system and also on the attitude control system.
Technical Paper

X-29A Subsystems Integration - An Example for Future Aircraft

The X-29A is the first X-series experimental aircraft developed in the United States since the mid-sixties. The X-29A is a technology demonstrator aircraft that integrates several different-technologies into one airframe. Among the technologies demonstrated are the aeroservoelastically tailored composite forward swept wings, close coupled canards, discrete variable camber wing, triplex digital flight control system with analog backup, thin supercritical wing, three surface pitch control, large negative static margin and the integration of these technologies into the X-29 airframe. This paper deals with the issue of technology integration of five of the X-29A subsystems and the early design decision to use existing aircraft, components whenever and wherever possible. The subsystems described are the X-29 aircraft Hydraulics System, the Electrical Power System, the Emergency Power System, the Aircraft Mounted Accessory Drive and the Environmental Control System.
Technical Paper

Working Fluid De-freezing in Radiator on Base of LHP

Selection of working fluid is one of the main criterions for designing of heat pipes thermal control systems (TCS) for space application. In this paper we will describe how we solved the task of development of the TCS with working fluid of high thermal physical properties. In 2004-2006 we developed the Engineering model of Deployable Radiator based on Loop Heat Pipe by CAST purchase order. It was developed for qualification tests. Ammonia application as LHP working fluid is stipulated by its high thermal physical properties. However Ammonia freezing temperature is of minus 77ºC. Such fact impedes Ammonia application when operation temperatures of LHP Radiator are lower than this value, for example, It takes several tens of hours to orbit a spacecraft and prepare it for work (at that moment the spacecraft is out of power supply) and the working fluid can be frozen in a condenser-radiator when the spacecraft being in the shadow over a long period of time.

Wire Fed Plasma Arc Directed Energy Deposition Additive Manufacturing Process

This specification establishes process controls for the repeatable production of preforms by Wire Fed Plasma Arc Directed Energy Deposition (PA-DED). It is intended to be used for aerospace parts manufactured using Additive Manufacturing (AM) metal alloys, but usage is not limited to such applications.
Technical Paper

Wind Tunnel and Flight Development of Spoilers for General Aviation Aircraft

Wind tunnel tests have been carried out to develop a spoiler lateral control system for use with the GA(W)-1 airfoil with a 30% Fowler flap. Tests show that unfavorable aerodynamic interactions can occur between spoiler and flap for large flap deflections. Providing venting of lower surface air through the spoiler opening substantially improves performance. Results of tests with a number of spoiler and cavity shapes are presented and discussed. Applications of two-dimensional wind tunnel results to the design of satisfactory manual lateral control systems are discussed.
Technical Paper

Why Companies Use Air Freight — A Basic Consideration in Air Freight Systems Planning and Traffic Forecasting

Use of air freight depends not on the commodity or industry, as such, but on the combinations of characteristics that enable company to benefit from air shipment in any particular situation. Air freight handling and control systems should augment, not decrease, these benefits. Future air freight traffic must be forecast in terms of the different benefits sought in shipping by air. Research is required to determine the relative importance of different benefits in future traffic generation. Research areas are defined and cooperative research efforts urged.
Technical Paper

Who Needs Avionics Performance Minimums - The Government or You?

A lengthy effort to develop the minimum operational requirements of avionics systems needed for participation in the air traffic control system has not yet yielded standards or a means of administration acceptable to all segments of aviation. A new, more palatable approach by which users of the airspace can provide certain minimum operational characteristics in their airborne electronic systems shows promise. In order to make it work, FAA must clearly describe its electronic systems, how they work, and what their limitations are, so that willing participants may find out what they need to do in order to be right. Based on these system standards, minimum operational characteristics of airborne avionics can be developed and implemented. These may then meet with the approval of most of those affected, since the requirements will merely represent their own self-interest.
Technical Paper

What's Next in Commercial Aircraft Environmental Control Systems?

Before considering the future of aircraft environmental control systems (ECS's), a review of the relatively short history of this field would be valuable in understanding the present situation. Therefore, this paper notes many of the significant developments in commercial aircraft air-cycle refrigeration and in cabin environmental control. The evolution leading to the great variety of air-cycle systems now in production, or under development, is discussed along with a generic comparison of the merits of the various system types and some reasons for their selection. Constraints on air conditioning system development imposed by the airline operators, aircraft manufacturers, and regulatory agencies are touched upon as significant to charting the future direction of air conditioning system design. Finally, several directions that could be taken in future design are briefly commented upon.

Ways of Dealing with Power Regeneration onto an Aircraft Electrical Power System Bus

This SAE Aerospace Information Report (AIR) considers the issue of power regeneration into the EPS of an aircraft. A series of options for dealing with this regenerative power are considered and arranged in categories. Advantages and disadvantages of each solution, including the existing solution, are included. Validated simulation results from representative Electrical Power systems are presented in order to demonstrate how some of the solutions may operate in practice and how power quality can be maintained during regeneration. The impact on changes to the electrical generation system are also highlighted in this AIR, as these changes may have an impact on the solution deployed and the wider impact on the design of engines and auxiliaries. This AIR reviews concepts and excludes detailed discussions on power system design. These concepts relate to the More Electric Aircraft, cover both AC and DC systems and can be applied to both normal operating conditions or as fault mitigation.
Technical Paper

Wavelet-based Fouling Diagnosis of the Heat Exchanger in the Aircraft Environmental Control System

The Environmental Control System (ECS) of an aircraft provides thermal and pressure control of the engine bleed air for comfort of the crew members and passengers onboard. For safe and reliable operation of the ECS under complex operating environments, it is critical to detect and diagnose performance degradations in the system during early phases of fault evolution. One of the critical components of the ECS is the heat exchanger, which ensures proper cooling of the engine bleed air. This paper presents a wavelet-based fouling diagnosis approach for the heat exchanger.
Technical Paper

Virtualization Technology and Using Virtual CPU in the Context of ISO26262: The E-Gas Case Study

A new development environment is required where conflict between control systems is minimized, where processing can be executed while maintaining independence between systems, and where quality can be assured easily. This environment must enable flexibility in software layouts to accommodate software changes during the development process and the parallel development of multiple derivative systems. We have developed virtualization technology (virtual CPU), which allows the execution of system control with a single CPU without conflict between systems. An outstanding virtual CPU architecture that we have developed allows us to execute multiple real-time control tasks with the hardware scheduler, and we have developed hardware that extends the management of address space and interrupt handling, making it possible for a single CPU to be configured as multiple CPUs. Also, we have implemented a bus system that reduces interference between threads.
Technical Paper

Virtual Laboratory (VLAB) Concept Applied in a Life Science Laboratory

As pieces of the International Space Station (ISS) enter their test phase, access to information and data from the test laboratories must be made immediately available to analysts, managers, and customers. The Virtual Laboratory (VLAB) concept provides remote access to laboratory test data and other information, indirectly as archived data or directly as real-time data off the test bed. We applied VLAB to a life support system hardware test (the Trace Contaminant Control System, TCCS) in the Life Support Technology Center (LSTC). In this paper we describe the VLAB concept in the context of the TCCS hardware test.
Technical Paper

Viral Populations within the International Space Station's Internal Active Thermal Control System Ground Support and Potential Flight Hardware

The Internal Active Thermal Control System (IATCS) aboard the International Space Station (ISS) contains an aqueous, alkaline fluid (pH 9.5±0.5) that aids in maintaining a habitable environment for the crew. Because microbes have significant potential to cause disease, adverse effects on astronaut health, and microbe-induced corrosion, the presence of both bacteria and viruses within IATCS fluids is of concern. This study sought to detect and identify viral populations in IATCS samples obtained from the Kennedy Space Center as a first step towards characterizing and understanding potential risks associated with them. Samples were concentrated and viral nucleic acids (NA) extracted providing solutions containing 8.87-22.67 μg NA per mL of heat transfer fluid. After further amplification viral DNA and cDNA were then pooled, fluorescently labeled, and hybridized onto a Combimatrix panvira 12K microarray containing probes for ∼1,000 known human viruses.
Journal Article

Verification of Thermal System Performance for Control Applications Using TMG Finite Element Simulation and MATLAB

Many real world engineering systems are sensitive to temperature, and temperature control is vital to the success and operation of a broad spectrum of engineering applications. This paper investigates the use of numerically generated frequency response data to simulate the control system behavior of a simple but realistic finite element based nonlinear thermal model. Using an IDEAS TMG finite element model, a thermal control system Bode plot was computed. The Bode plot was then used to determine the transfer function of the thermal system and design an appropriate control compensator to implement thermal control. The performance of the compensated thermal system was then predicted first by MATLAB, and second by TMG. The response predicted by MATLAB using transfer functions was corroborated by its close agreement with a TMG finite element transient response simulation.
Technical Paper

Verification and Validation of the F/A-22 Raptor Environmental Control System/Thermal Management System Software

The F/A-22 Raptor Environmental Control System/Thermal Management System (ECS/TMS) software is a real-time digital control system application. The system is comprised of 4 separate computer software configuration items (CSCI). Verification & Validation (V& V) activities of such a system is complex and performed in stages. The process begins with structured design and analysis techniqes and culminates with actual flight test. This paper provides an overview of the V& V effort to perform the formal software qualification testing to flight certify this software. First, an overview of the system and software architecture is provided. Then each level of testing is described. Development and problem report metrics are shown. Finally, lessons learned are presented.
Technical Paper

Velocity Command/Position Hold: A New Flight Control Concept for Hovering VTOL Aircraft

A new flight control concept for a hovering VTOL aircraft has been developed. The main feature of this system is that deflection of a pilot's controller produces a linear velocity command with position hold when the controller is centered. Another novel feature is that horizontal commands both tilt the aircraft and deflect the thrust vector, while the position feedbacks only deflect the thrust vector. This system has been evaluated in two piloted simulations of landing a VTOL aircraft on a small ship. The pilots consistently rated this system better than three other, more conventional, control systems.
Technical Paper

Variable Conductance Thermal Control by Passive or Active Control of Fluid Manipulation

A concise survey is given of international research done in the last decades for developing spacecraft-oriented (variable conductance) two-phase thermal control systems, based on passive or active control of fluid manipulation. The various methods of variable conductance heat pipe control are discussed, focusing on control using non-condensable gas. The historical development is given, including the arguments why these relatively simple two-phase thermal control systems often have been and will be the preferred solution to meet the large variety of different restrictions, induced by the typical requirement specifications of many, relatively low power (up to 5 kW) applications in space. The paper briefly mentions alternative control approaches considered in the past, while focusing on those that are regaining attention, i.e. systems, based on electro-hydrodynamics and electro-osmosis. It touches also a novel switching/pumping control alternative based on electric wetting.