Design and Application of an Adaptive Tracking Filter Control System

The design of an adaptive tracking filter control system and its application to large flexible booster vehicles is described. The problem of elastic vehicle stability is considered along with its solution by conventional and adaptive techniques. The improvement in vehicle stability, which may be achieved with the adaptive tracking filter technique as compared to conventional techniques, is shown. The control system evolved uses two adaptive tracking filters to phase stabilize the first and second bending modes, in addition to conventional compensation techniques. The application of this adaptive technique to a vehicle in which the modal frequencies are in close proximity (<2.5 percent separation) is discussed. The mechanization of the adaptive control system involves the selection of design techniques and components that are electrically and physically compatible with the intended airborne application. The development of a suitable frequency tracking technique and tracking filter is described, in addition to the electronic and mechanical design of the adaptive control system prototype.     

Astrometric positioning and orbit determination of geostationary satellites

In the project titled “Astrometric Positioning of Geostationary Satellite” (PASAGE), carried out by the Real Instituto y Observatorio de la Armada (ROA), optical observation techniques were developed to allow satellites to be located in the geostationary ring with angular accuracies of up to a few tenths of an arcsec. These techniques do not necessarily require the use of large telescopes or especially dark areas, and furthermore, because optical observation is a passive method, they could be directly applicable to the detection and monitoring of passive objects such as space debris in the geostationary ring.     

Market mature 1998 hybrid electric vehicles

Beginning in 1990, the major automotive passenger vehicle manufacturers once again re-evaluated the potential of the battery powered electric vehicle (EV). This intensive effort to reduce the battery EV to commercial practice focused attention on the key issue of limited vehicle range, resulting from the low energy density and high mass characteristics of batteries, in comparison to the high energy density of liquid hydrocarbon (HC) fuels. Consequently, by 1995, vehicle manufacturers turned their attention to hybrid electric vehicles (HEV). This redirection of EV effort was highlighted finally in 1997, at the 57th Frankfurt Motor Show, the Audi Duo parallel type hybrid was released for the domestic market as a 1998 model vehicle. Also at the 1997 32nd Tokyo Motor Show, Toyota Hybrid System (THS) Prius was released for the domestic market as a production 1998 model vehicle. This paper presents a comparative analysis of the key features of these two 1998 model year production hybrid systems. Among the conclusions, two issues are evident: one, the major manufacturers have turned to the hybrid concept in their search for solutions to the key EV issues of limited range; and, heating/air conditioning; and two, the focus is now on introducing hybrid EV for test marketing domestically     

Source and loss processes in the inner magnetosphere

Space Science Reviews -     

Cometary Materials: Progress Toward Understanding the Composition in the Outer Solar Nebula

A major objective of the workshop was to learn about the chemical composition, physical structure, and thermodynamic conditions of the outer parts of the solar nebula where comets formed. Here we sum up what we have learned from years of research about the molecular constituents of comet comae primarily from in situ measurements of Comet 1P/Halley and remote sensing of Comets 1P/Halley, Hale-Bopp (C/1995 O1), and Hyakutake (C/1996 B2). These three bright comets are presumably captured Oort cloud comets. We summarize the analyses of these data to predict the composition of comet nuclei and project them further to the composition, structure, and thermodynamic conditions in the nebula. Near-future comet missions are directed toward less active short-period Jupiter-family comets. Thus, future analyses will afford a better understanding of the diversity of these two major groups of comets and their respective regions of origin in the solar or presolar nebula. We conclude with recommendations for determining critical data needed to aid in further analyses. Results of the workshop provide new guidelines and constraints for modeling the solar nebula. This revised version was published online in June 2006 with corrections to the Cover Date.     

Acceleration of the High Speed Solar Wind in Coronal Holes

We outline a theory for the origin and acceleration of the fast solar wind as a consequence of network microflares releasing a spectrum of high frequency Alfvén waves which heat (by cyclotron absorption) the corona close to the Sun. The significant features of our model of the fast wind are that the acceleration is rapid with the sonic point at around two solar radii, the proton temperatures are high (~ 5 million degrees) and the minor ions are correspondingly hotter, roughly in proportion to their mass. Moreover we argue that since the energy flux needed to power the quiet corona in closed field regions is about the same as that needed to drive the fast solar wind, and also because at deeper levels (< 2 × 10⁵ K) there is no great difference in the properties of supergranules and network in closed and open field regions, the heating process (i.e., dissipation of high frequency waves) must be the same in both cases. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaporation and ignition of droplets in combustion chambers modeling and simulation

Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present paper processes of non-equilibrium evaporation of small droplets will be discussed. As it was shown before, accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplet diameters less than 100 μm, while the surface tension effects essentially manifest only for droplets below 0.1 μm. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their lifetime. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Droplet atomization interferes the heating, evaporation and combustion scenario. The scenario of fuel spray injection and self-ignition in a heated air inside combustion chamber has three characteristic stages. At first stage of jet injection droplets evaporate very rapidly thus cooling the gas at injection point, the liquid jet is very short and changes for a vapor jet. At second stage liquid jet is becoming longer, because evaporation rate decreases due to decrease of temperature. But combustion of fuel vapor begins which brings to increase of heat flux to droplets and accelerates evaporation. The length of the liquid jet decreases again and remains constant slightly oscillating.     

Dosimetry during the first IBIS facility flight.

The dosimetry of cosmic rays was performed during the first experimental flight of the IBIS facility. Different thermoluminescent detectors (TLD) have been used to measure the contribution of the low linear energy transfer component (LET < 10 keV/micrometer) and plastic nuclear track detectors (PNTD) for the high linear energy tranfer (LET) component. Several parameters of tracks have been measured to determine the LET spectra of primary and secondary charged particles. The total absorbed dose rate (TLD+PNTD) during the flight was 0.23 mGy/day and the dose equivalent rate using the ICRP 60 was 0.52 mSv/day. The corresponding mean quality factor was 2.4. These results are in agreement with those obtained aboard the MIR station with a tissue equivalent proportional counter.     

Future concepts for electromagnetic detection: fromspace-time-frequency resources management to wideband radars

An overview of the key operational and technical factors governing future radar evolution is given, in order to identify main lines along which research and development effort should be oriented