In memoriam Julius Bartels

Ohne Zusammenfassung

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In memoriam Julius Bartels

     

Power management and distribution system for a more-electricaircraft (MADMEL)

A five-phase Power Management and Distribution System for a More-Electric Aircraft (MADMEL) program was awarded by the Air Force to Northrop/Grumman Military Aircraft Division in September 1991. The objective of the program is to design, develop, and demonstrate an advanced electrical power generation and distribution system for a More-Electric Aircraft (MEA). The MEA emphasizes the use of electrical power in place of hydraulics, pneumatic, and mechanical power to optimize the performance and life cycle cost of the aircraft. This paper presents an overview of the MADMEL program and a top-level summary of the program results, development and test of major components to date. In Phase I and Phase II studies, the electrical load requirements were established and the electrical power system architecture was defined for both near-term (NT-year 1996) and far-term (FT-year 2003) MEA application. The detailed design and specification for the Electrical Power System (EPS), its interface with the Vehicle Management System, and the test set-up were developed under Phase III. Phase IV, fabrication and testing of the subsystem level hardware, has been completed. Overall system level integration and testing, Phase V, is scheduled to be completed by September 1999     

An analysis of temperature fields in rotating fluid

A possible variant presented for solving the equation of motion of a rotating flow is more general with respect to the variants known in the literature. On the basis of the simultaneous solution of the equations of motion and energy, the temperature fields are determined under changes of the rotation nature.     

Aeronautical telemetry using multiple-antenna transmitters

The placement of multiple antennas on an air vehicle is one possible practice for overcoming signal obstruction created by vehicle maneuvering during air-to-ground transmission. Unfortunately, for vehicle attitudes where more than one of these antennas has a clear path to the receiving station, this practice also leads to self-interference nulls, resulting in dramatic degradation in the average signal integrity. This paper discusses application of unitary space-time codes such as the Alamouti transmit diversity scheme and unitary differential space-time codes to overcome the self-interference effect observed in such systems. The mathematical foundations of these techniques within the context of this application as well as computational performance gains associated with their implementation are provided. Issues such as the cost of channel estimation for trained techniques as well as the throughput performance of nondifferential and differential schemes for realistic air-vehicle motion are analyzed     

Fiber-optic gyros and quartz accelerometers for motion control

In article the opportunity of use strapdown inertial navigation system (SINS) on the base of fiber-optic gyroscopes and quartz accelerometers corrected from star sensors and satellite navigation equipment (SNE) for perspective interplanetary spacecrafts motion control on phases of interplanetary trajectory insertion, trajectory correction, and braking during transition to Mars orbit is investigated. Results of onboard control complex accuracy characteristics estimation are presented at the given dynamic spacecraft scheme which is taking into account the liquid oscillations in tanks and structure elements elasticity. At modelling the errors of measuring devices installation, errors of SINS initial alignment and instrumental errors of SINS sensitive elements, variation of control engines parameters were taken into account. The structure of the developed complex of imitation modelling of interplanetary spacecraft controlled motion is resulted. Estimations of active flight legs realization accuracy were received by a method of statistical modelling of spacecraft controlled motion     

Effects of Local Detachment of a Melt from Ampoule Walls,Crystal Vibration,and Magnetic Field at Crystal Growth under Zero Gravity

A numerical investigation of the melt flow and heat and mass transfer is carried out at the crystal growth under zero gravity, when the melt detachment from ampoule walls, crystal vibration, and various magnetic fields are active. Specific features of the melt flow are demonstrated depending on the size of a detachment zone adjacent to the crystallization boundary. The velocity of the averaged flow generated by crystal vibration is determined as a function of the vibration intensity. It is shown that the crystal vibration cannot compensate a thermal capillary flow (caused by detachment of the melt from the ampoule wall) and reduce the macrosegregation of impurities. It is shown that the application of steady and rotating magnetic fields are inefficient for all ampoule methods of crystal growth under microgravity conditions.     

On electromagnetic phenomena in Mercury’s magnetosphere

Mercury has a small but intriguing magnetosphere. In this brief review, we discuss some similarities and differences between Mercury’s and Earth’s magnetospheres. In particular, we discuss how electric and magnetic field measurements can be used as a diagnostic tool to improve our understanding of the dynamics of Mercury’s magnetosphere. These points are of interest to the upcoming ESA-JAXA BepiColombo mission to Mercury.