Research on a Measurement Method for Middle-Infrared Radiation Characteristics of Aircraft

Aiming at the problem wherein temperature inversion accuracy is unstable due to the major differences in atmospheric transmittance under various observation paths, a method for measuring radiation characteristics of an aircraft engine’s hot parts and skin using a cooled middle-wave infrared camera is proposed. Based on the analysis of the aircraft’s infrared radiation characteristics, the atmospheric transmission model of any observation path was revised, the absolute radiation correction model was established, and the temperature inversion equation was calculated. Then, we used the quasi-Newton method to calculate the skin temperature and discussed uncertainty sources. After the theoretical study, an outfield test was carried out. A middle-wave infrared camera with a wavelength of 3.7–4.8 μm was applied to the actual experimental observation of the turbofan civil aviation aircraft. The ground observation distance was 15 km, and the flying height was 3 km. When implementing temperature inversion with the method presented in this paper, the surface temperature of the aircraft engine hot parts was 381 K, the correction uncertainty was ±10 K, the surface temperature of the skin was 296 K, and the correction uncertainty was ±6 K. As the experiment showed, the method in this paper can effectively implement infrared target temperature inversion and provide a reference for the quantification of infrared data.

Mathematical Modeling Methods in Designing Onboard Laser-Ranging Systems of Spacecraft

To perform rendezvous and docking of spacecraft (SC), it is necessary to detect and measure the coordinates of a passive space vehicle (SV) using the onboard aids of an active SV. For this purpose, in addition to radio engineering systems, laser-ranging systems (LRS) are used. A designing process of the onboard LRS for promising spacecraft is currently becoming more complicated and requires taking into account a lot of factors.The authors have developed the PC software to assess capabilities of onboard pulse LRS of spacecraft when working on the nearby or distant space objects that have a diffusely scattering surface, as well as are equipped with the corner reflectors. The software also allows us to calculate the LRS parameters, which, according to GOST R 50723-94, ensure eye-safety in the spectral range of 0.81 ... 1.5 microns in case of accidental irradiation.The energy of the intensifier pulse and the divergence of a sensing beam determine the LRS range and the distance of eye-safe observation, which are the most important indicators to characterize the onboard LRS capabilities. To ensure the best LRS range and safety characteristics simultaneously, it is necessary to solve the problem of multi-criteria optimization.The paper solves the problem of multi-criteria optimization for the maximum LRS range and the eye-safe observation distance by Pareto sets the use of which allows us to avoid uncertainty in choosing a significance of criteria.The results obtained show that the proposed methods can be successfully applied in designing onboard LRS of spacecraft.

Distribution of carbon stocks in drainage areas on peatlands of Sungai Tohor Village, Meranti Islands District, Indonesia

Silviana SH, Saharjo BH, Sutikno S. 2021. Distribution of carbon stocks in drainage areas on peatlands of Sungai Tohor Village, Meranti Islands District, Indonesia. Biodiversitas 22: 5106-5114. Peatland ecosystems provide a variety of environmental services and biodiversity with their ability to store and absorb carbon. The increase of land clearing followed by the construction of drainage or canal has resulted in the degradation of peatlands and is prone to fire incidences. Canal construction, whether we realize it or not, has a negative ecological impact on the in situ (local) environment, namely land degradation and subsidence, as well as a wider (global) impact in the form of loss of carbon stocks, increased GHG emissions that can trigger global warming. This study aims to identify the distribution of carbon in the area where drainage is made where the distribution of carbon stock in starting at a distance of 10 m, 50 m, 100 m, 250 m, and 350 m from the canal. The study was conducted on the community plantations including unburned areas (rubber plantations and secondary forests) and burned areas. The influence of land use and drainage development on carbon stock distribution is rarely known. The results showed a decrease in C-Stock with a decrease in drainage distance. The quantity of carbon stock in secondary forests ranged from 13.275 ton ha-1 - 24.839 ton ha-1, Burnt Area-1 ranged from 6.995 ton ha-1 - 11.59 ton ha-1, and Burnt Area 2 ranged from 4.677 ton ha-1 - 12.580 ton ha-1. In contrast, rubber plantations had higher C-stock in the initial observation distance, around 9.064 ton ha-1 - 11.805 ton ha-1, which may be due to intensive land use near the canal.

Insulator filth monitoring and situation awareness based on ultraviolet pulse and least square method

To monitor the filth state of insulators in time, a method based on ultraviolet pulse method is proposed to monitor the filth status of insulators, which can detect the early corona discharge of insulators by detecting UV signals and determine the degree of insulator filth. On this basis, the response characteristics of spot area to electrical pulse signal are studied and theoretical analysis is carried out, the relationship between spot area and electrical pulse signal amplitude is studied, and the correlation curve is obtained. By observing the change law of image size with the observation distance in ultraviolet image. the experiment found that the image size of UV channel and the image size of visible light channel increased or decreased in approximate proportion with the observation distance and proposed a new method to estimate the “discharge imaging area ” of discharge on the surface of the insulator by using the image information of the visible light channel. According to the discharge “relative spot area mean”, one minute time “number of large spot area image frames” two ultraviolet imaging parameters used to characterize the filth discharge characteristics, combined with the ambient humidity to establish a fuzzy logic reasoning model of the filth state, to achieve the assessment of the filth state of the insulator. By using the proposed UV image processing method, the accuracy of insulator filth detection is improved.

A Ground-Motion Model for GNSS Peak Ground Displacement

ABSTRACT We present an updated ground-motion model (GMM) for Mw 6–9 earthquakes using Global Navigation Satellite Systems (GNSS) observations of the peak ground displacement (PGD). Earthquake GMMs inform a range of Earth science and engineering applications, including source characterization, seismic hazard evaluations, loss estimates, and seismic design standards. A typical GMM is characterized by simplified metrics describing the earthquake source (magnitude), observation distance, and site terms. Most often, GMMs are derived from broadband seismometer and accelerometer observations, yet during strong shaking, these traditional seismic instruments are affected by baseline offsets, leading to inaccurate recordings of low-frequency ground motions such as displacement. The incorporation of geodetic data sources, particularly for characterizing the unsaturated ground displacement of large-magnitude events, has proven valuable as a complement to traditional seismic approaches and led to the development of an initial point-source GMM based on PGD estimated from high-rate GNSS data. Here, we improve the existing GMM to more effectively account for fault finiteness, slip heterogeneity, and observation distance. We evaluate the limitations of the currently available GNSS earthquake data set to calibrate the GMM. In particular, the observed earthquake data set is lacking in observations within 100 km of large-magnitude events (Mw>8), inhibiting evaluation of fault dimensions for earthquakes too large to be represented as point sources in the near field. To that end, we separately consider previously validated synthetic GNSS waveforms within 10–1000 km of Mw 7.8–9.3 Cascadia subduction zone scenario ruptures. The synthetic data highlight the importance of fault distance rather than point-source metrics and improve our preparedness for large-magnitude earthquakes with spatiotemporal qualities unlike those in our existing data set.

Prospects for using gated lidars in autonomous mobile robots

The analysis of the implementation problems of technical vision systems based on the use of time-of-flight laser lidars is carried out. It is concluded that the implementation of vision systems with acceptable parameters dictates an excessively high cost of the lidar. An alternative version of the lidar implementation is considered – a gated lidar based on a laser vision system. Replacing the broadband detector and high-speed scanning system with a gated CCD-matrix can significantly reduce the cost of the lidar while ensuring the high resolution of the lidar. The analysis of the dependence of the signal-to-noise ratio for gated lidar with and without an electron-optical converter has shown that in bad weather conditions the decrease in the gain of the useful signal when the image intensifier is excluded is compensated by the exclusion of the EOC's noise factor, so that the loss in the observation distance is less than 15%.

The research of the energy and the fluence of the primary and the secondary γ-ray in the n/γ hybrid radiation field

According to the "little boy" data from the United States, this paper simulates the primary γ-ray of the nuclear explosion and the secondary γ-ray produced by neutron, γ-ray and material interaction. At the same time, the linear attenuation coefficient spectra of 0.001mev to 100mev was calculated. The information was obtained from the point of the source projection of 500 meters to 1km. The results showed in the observation distance: The attenuation of the primary γ-ray energy was in line with the spectral γ-ray passing through the law of shielding the decay of the material. and it showed the phenomenon of the "hardening" of the energy spectrum. The fluence decreases an order of magnitude. The energy of the secondary γ-ray does not showed obvious attenuation laws, and the fluence decreases by about two orders of magnitude. It was worth noting that the average energy of the two kinds of γ-ray was around 2.100 MeV, and the fluence was in the same order of magnitude at 1km from the distance simulation.

A Rational Approach to the Problem of Accurate UAV Landing Using Intelligent Image Processing Methods

This paper is devoted to the description of preliminary results of solving two problems related to the problem of accurate unmanned aerial vehicle (UAV) landing. The first task is to develop a methodology for rational choice of the landing platform image, which ensures the best recognition by an UAV from any angle and a reasonable observation distance. The second task is to develop a procedure for a sequential analysis of the current situation, forthcoming of the UAV to the platform and accurate landing. To solve these problems, it is proposed to use the previously developed intelligent processing methods based on the using of the structural properties of an image. In particular, the technique is applied using the Weibull distribution model for the gradient magnitude of an image and its components. Numerical results are presented that show the prospects of the proposed procedures and the directions for improving the developed techniques.

A Seismological Study of the Sos Enattos Area—the Sardinia Candidate Site for the Einstein Telescope

The recent discovery of gravitational waves (GWs) and their potential for cosmic observations prompted the design of the future third-generation GW interferometers, able to extend the observation distance for sources up to the frontier of the Universe. In particular, the European detector Einstein Telescope (ET) has been proposed to reach peak strain sensitivities of about 3×10−25 Hz−1/2 in the 100 Hz frequency region and to extend the detection band down to 1 Hz. In the bandwidth [1,10] Hz, the seismic ambient noise is expected to represent the major perturbation to interferometric measurements, and the site that will host the future detectors must fulfill stringent requirements on seismic disturbances. In this article, we conduct a seismological study at the Italian ET candidate site, the dismissed mine of Sos Enattos in Sardinia. In the range between few mHz to hundreds of mHz, out of the detection bandwidth for ET, the seismic noise is compatible with the new low-noise model (Peterson, 1993); in the [0.1,1] Hz bandwidth, we found that seismic noise is correlated with sea wave height in the northwestern Mediterranean Sea. In the [1,10] Hz frequency band, noise is mainly due to anthropic activities; within the mine tunnels (≃100 m underground), its spectrum is compliant with the requirements of the ET design. Noise amplitude decay with depth is consistent with a dominance of Rayleigh waves, as suggested by synthetic seismograms calculated for a realistic velocity structure obtained from the inversion of phase- and group-velocity dispersion data from array recording of a mine blasting. Further investigations are planned for a quantitative assessment of the principal noise sources and their spatiotemporal variations.