A method for constructing an airfoil using a specified chord velocity diagram

A problem of determining a shape of the airfoil being streamlined by a potential incompressible inviscid flow is solved by the successive approximation method using a specified chord velocity diagram. It is shown that a closed airfoil that possesses a specified chord velocity diagram can be constructed with a sufficient accuracy; if the chord diagram is unsuccessfully specified, the closed airfoil may prove to be not univalent, that is, physically unrealizable.     

Airborne radar: its beginnings in World War II

Although not realized at the time, the defeat of the German Air Force in the summer of 1940 was one of the crucial battles of World War II. The narrow margin of victory can be ascribed to Britain's air-warning radar, Chain Home (CH), consisting of the 15-meter CH and the 1.5-meter CHL. The skillful use of this equipment by the Royal Air Force made daylight bombing unsustainable; the Luftwaffe then turned to night attacks, generally called "The Blitz." These were not effective in destroying military and industrial targets and depended on the hope of reducing the population's will to fight. Chain Home was of little use except to observe the attackers arrival, as it had almost no ability to follow the attackers as they proceeded inland. This eventuality was reckoned with before the outbreak of hostilities and had called for radars mounted in night fighters capable of guiding the pilot close enough to the target for him to open fire visually. The electronic techniques used at 1.5-meters were adapted to planes capable of carrying the radar and its operator. But there were three important design constraints: 1) the antennas had to be restricted to sizes that were practical for installation on aircraft, which for meter waves gave them low gain and large side lobes; 2) the set's maximum range was limited by the fighter's altitude as a result of the huge ground returns from the side lobes. British antiaircraft artillery, the stepchild of their arms, was too ineffective to drive the bombers to extreme altitudes; and 3) a minimum range had to be held until the flier could see his target, which strained the pulse techniques of the time.     

Automotive-grade MEMS sensors used for general aviation

The attitude heading reference system (AHRS) provides data for primary flight instruments, head-up displays, autopilots, and moving map navigation systems. Advances in solid-state MEMS rate sensors, coupled with Kalman filter algorithms designed to mitigate high drift rates, provide the basis for low-cost, high-performance AHRS for general aviation. This paper describes the performance of a low cost, miniaturized AHRS using automotive-grade MEMS sensors. The performance of the system is detailed. The implications for certification of this class of system and fault tolerance are discussed.     

Microdosimetric measurements of heavy ion tracks.

The biological effectiveness of radiations depends on the spatial pattern of ionizations and excitations produced by the charged particle tracks involved. Ionizations produced by both the primary ion and by energetic delta rays may contribute to the production of biologically relevant damage and to the concentration of damage which may effect the probability of repair. Although average energy concentration (dose) can be calculated using homogeneous track models, the energy is actually concentrated in small volumes containing segments of the ion and delta ray tracks. These local concentrations are studied experimentally using low pressure proportional counters, and theoretically, using Monte Carlo methods. Small volumes near an ion track may be traversed by a delta ray. If they are, the energy deposited will be similar to that produced by a single electron track in a low-energy x-ray irradiation. The probability of a delta ray interaction occurring decreases with the square of the radial distance from the track. The average energy deposited is the product of this probability and the energy deposited in an interaction. Average energy deposited calculated from measured interaction probability is in good agreement with the results of homogeneous track models.     

Optimal number of phased array faces and signal processors for horizon surveillance

The problem of the optimal number of phased array faces for performing 360/spl deg/ horizon surveillance is considered. Assuming the detection performance is the same in all beam positions and the total number of T/R modules is constant, it is shown that the optimal number of array faces is three. This is true whether the arrays are operating simultaneously or sequentially. A parametric analysis is performed between the number of array faces operating simultaneously and the associated cost of simultaneous operation in terms of the size of the array.     

Reduced-order multiple model adaptive controller for flexiblespacestructure

The robustness of a moving-bank multiple model adaptive estimator/controller to order reduction in the controller design model is examined. It is shown that the adaptive mechanism and bank-moving logic are not confounded by the effects of unmodeled higher order modes of a large flexible spacestructure. Control characteristics are achieved that are essentially equivalent to those of an artificially informed benchmark controller     

SETI education programs in Australia

This paper discusses and evaluates two innovative SETI education programs conducted at the University of Western Sydney, viz: the SETI Pathways Program and the Life in the Universe Curriculum Project.     

An experimental investigation of three eigen DF techniques

The comparative direction-finding (DF) performance of multiple signal classification (MUSIC), ROOT-MUSIC, and estimation of signal parameters via rotational invariance techniques (ESPRIT) is considered. Data were collected from two target transmitters operating simultaneously. The objective of the experiment was to evaluate multipath resolution capability using measurement precision equivalent to that found in modern radio direction-finding systems     

Application of Gram-Schmidt algorithm to fully adaptive arrays

The Gram-Schmidt orthogonalization (GSO) algorithm has excellent numerical performance and is readily applicable to systolic implementations such as in a field of adaptive cancellation systems. A modified GSO algorithm for a fully adaptive array is proposed and computer simulations show that the proposed algorithm gives superior performance. A systolic implementation of the proposed GSO algorithm for fully adaptive array is presented. A feedback mode GSO algorithm for use with analog weights is also presented and has been shown to have excellent performance in the presence of weight errors