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2S
Published in Bernard Lovell, Echoes of War, 1991
By that time the major panic about the dangers of using H2S was subsiding. As related by Saward the claim made by Dalton-Morris during his visit to TRE on 21 July, that a captured German pilot claimed to have shot down a bomber ‘by using Naxos’, turned out to be a myth. Squadron Leader W.H. Thompson of my staff was a fluent German linguist, and I arranged for him to interrogate the German pilot who had recently been shot down and made a prisoner of war and who was alleged to have made statements about the use of Naxos. Oddly, the Naxos equipment had not been installed in his aircraft, which was reasonably intact in its crashed condition. This interrogation took place at Trent Park, near Cockfosters in Hertfordshire, on 14 October. The prisoner of war explained to Thompson what he knew of the system and how it was used, describing in some detail the method of presentation of the information it received. He also stated, most emphatically, that the device was designed to be used only to locate the bomber stream, the instrument being crude to the extreme, providing no measurement of range or accurate bearing of detected H2S transmissions. This German went on to say that for attack the fighter relied on instructions from his Ground Night Fighter Control and the use of his radar interception equipment known as SN2, which was comparable to Britain’s ai.8
Radar Electronic Warfare
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
ESM is thus employed to accomplish three primary functions: interception of radar emissions, analysis of radar signals, and direction finding to the origin of radar signals. The primary use of ESM in tactical situations is in the simplest radar warning receiver (RWR), which intercepts radar signals, warns that a radar is emitting radar signals, and attempts to ascertain the functions of the radar. It advises the presence of threats such as missile radar supplying the relative bearing on cockpit-based display. It is unsophisticated low-frequency equipment that is present to cover the bandwidth of expected threats, and it exploits the range information to indicate the threat before it comes into firing range. Receivers then increase the complexity through tactical ESM to the full ELINT capability. In some radar design, radar's process gain exceeds the process gain of the interceptor to the same illumination signal so that the echo detection takes place at a longer range than interception. Radars of this type that emit waveforms coded in such a way as to be difficult to detect without knowing the code, are known as low probability of intercept (LPI)6 radars. Diversity of signals, such as pulsed, CW, and interpulse-modulated, must all be accommodated with a high probability of intercept (POI) and a low false-alarm rate (FAR). The probability of intercept in RWRs deteriorates, particularly when many emitters are present in the dense environment. It needs filtering or sorting of emissions to classify each signal to know the important parameters like the amplitude, pulse width, frequency, angle of arrival, coherency, polarization, and pulse train characteristics of the radar.
Gas Filtration Theory
Published in Michael J. Matteson, Clyde Orr, Filtration, 2017
The same result can be obtained using the general Eq. (269) and the flow field [Eq. (292)]. On the basis of Eq. (205), these authors [516] carried out an analysis of the filtration characteristics. The case of direct interception for isolated sphere in the range of small Kn was treated by Pich [517].
Filtration of airborne particles by a trickle granular bed: a modelling approach
Published in Environmental Technology, 2020
Nassim Khirouni, Augustin Charvet, Dominique Thomas
The validity of the modelling approach was tested using experimental data obtained in a previous work [6] on the removal of Al2O3 micronic particles (with a mean aerodynamic diameter of 1.8 µm) by a trickle granular bed with different collector diameters (2, 5 and 10 mm) and a bed thickness of 50 cm. These measurements were conducted on the same experimental pilot presented by Figure 1. The model predictions are in good agreement with the experimental results (Figures 8–10), taking into consideration the measurements uncertainties (10% error). Results show that the collection efficiency increases with increasing the particle diameter, due to the predominance of inertial and interception mechanisms in this size range. Using smaller collectors allows improving the collection efficiency which is in agreement with theoretical predictions and experimental observations [4]. Increasing the water flow rate results in an increase of the collection efficiency. This is mainly due to the decrease of the bed porosity, that will also cause an increase of the interstitial velocity, enhancing the particle collection by the inertial mechanism. In Figure 10, the experimental collection efficiency of the dry bed is lower than that predicted by the model. This might be due to the increase of the collector diameter causing a decrease of the ratio between the column diameter and the collector diameter. Low ratios result in a wall effect that creates preferential passages. In the presence of liquid this effect will disappear because of the liquid hold up.
Determination of the aerosol particle size distribution by means of the diffusion battery: Analytical inversion
Published in Aerosol Science and Technology, 2018
A. A. Onischuk, S. V. Valiulin, A. M. Baklanov, P. P. Moiseenko, V. G. Mitrochenko
Equation (4) is the basis of the classical filtration theory. To calculate the overall collection efficiency, the efficiencies due to individual mechanisms are included additively and the correction term is incorporated to compensate the combined effect (Kirsch et al. 1969). However, Equation (4) cannot be justified in a rigorous theoretical way. To predict the aerosol filtration by fibrous filters more exactly, Yeh and Liu (1974) calculated the single-fiber collection efficiency numerically for the continuum and the slip-flow regimes, considering diffusion, interception, and inertial impaction simultaneously. The calculated overall collection efficiency was in good agreement with the formula Equation (4) for the range of interception parameter R < 0.05. Hunt et al. (2014) calculated the single-fiber efficiency from the collision rate for particles with fibers. They applied the Langevin equation for particle motion, which enabled consideration of all filtration mechanisms simultaneously. The calculated filtration efficiencies were in good agreement with those determined from Equation (4) for R < 0.03.
Fast detection and parameter estimation for polyphase-code radar signal
Published in International Journal of Electronics, 2018
Xiaofeng Wang, Runlan Tian, Rui Zhou, Chunyu Wang
Electronic warfare includes the interception and analysis for the received signal (Pace, 2003), which refers to the detection for radar signal and the estimation for its modulation parameters (Li, Ji, & Jiang, 2011). In the face of the increasingly powerful electronic warfare equipment, more and more radar systems have adopted the pulse compression signals which have a low probability of intercept (LPI) (Govoni, Li, & Kosinski, 2013; Monakov & Nesterov, 2017; Shi, Wang, Sellathurai, & Zhou, 2017; Shi, Zhou, & Wang, 2017; Yang & Chen, 2017).