František Racek

Forensic and clinical issues in the use of frangible projectile.

Frangible projectiles for firearms, which break apart on impact, are mainly used by law enforcement agencies for training purposes, but can also be used for police interventions. Apart from the usual absence of lead in the projectiles, the main advantage of using frangible projectiles is the reduced risk of ricochet after impact with a hard target. This article describes the design and function of frangible projectiles, and describes gunshot wounds caused by ultra-frangible projectiles which fragment after penetration of soft tissues. Shooting experiments performed by the authors confirmed that differences in the geometry and technology of frangible projectiles can significantly modify their wounding effects. Some frangible projectiles have minimal wounding effects because they remain compact after penetration of soft tissues, comparable to standard fully jacketed projectiles. However, a number of ultra-frangible projectiles disintegrate into very small fragments after impact with a soft tissue substitute. In shooting experiments, we found that the terminal behavior of selected ultra-frangible projectiles was similar in a block of ballistic gel and the soft tissues of the hind leg of a pig, except that the degree of disintegration was less in the gel.

Simulation of Laser Attacks against Aircrafts

Threats of laser attacks against transport planes are increasing around the world in the last time. Common laserpointers are used for suchattacks, which emit a continuous greenlaserbeam with the wavelength of λ = 532 nm, and the power emitted is hundreds of milliwatts. This situation is dealing with laws in many countries. The goal of the paper is to contribute to a solution to these dangerous situations for air traffic. The spatial analysis is possible to create in which the configuration of the landscape surrounding the airport, the position of the landing airplane, and parameters of irradiation are considered. The results identify locations from where suchattacks are possible. Such results can aid police by increasing their efficiency in intervening against laser attackers.

NATO hyperspectral measurement of natural background

This article focuses on results of international measurement that took place in a military training area near Baad Shaarow in the summer of 2017. The main goal of this measurement was collecting information about current attitudes to camouflage targets detection. Participants measured spectral signatures of present targets by using hyperspectral sensors. Image spectroscopy has been in great demand for the last decade. This field was initially used in remote sensing application. The progress in electrotechnology allowed for spreading out into diverse branches. This system has not been used in military technology for too long. The military application involves specific tools. This event was attended by several research groups from several countries. Every group operated a different hyperspectral device and they documented an identical target. Using different devices there was a wide spectrum of apparatus which work in different spectrum from VIS to SWIR. The main part of this work is focused on hyperspectral data comparison.

Evaluation of validity of observer test for testing of camouflage patterns

Physical characteristics of camouflage patterns such as color or remission spectra can be tested and measured by objective methods. In the vast majority of use of camouflage pattern, the human (obscure person) will recognize the camouflaged object. Therefore, the quality of the camouflage pattern ultimately determines how a person in a given environment perceives the camouflage pattern. Human perception is very subjective, and its assessment cannot be measured by simple physical methods. Therefore, we process the observer’s visual performance when searching for camouflaged objects. It must always be based on the statistical processing of information on perceived quality of camouflage by individual observers. One of the methods for assessing the quality of camouflage surfaces is so called observer test. The observer test is a simple visual test in which a number of viewers observe a series of images of different scenes containing camouflaged object. The time taken to find the camouflaged object is measured. Depending on the time, it takes to find the camouflaged object, the quality of the camouflage pattern is judged. The time required to find a camouflaged object depends, among other, on the arrangement of the scene, the conditions of the observer test, how the observer interacts with the test interface, the observers properties and last but not least the camouflage pattern quality. The time taken to find a camouflaged object by a particular observer in a particular frame must be assumed as a random variable because it depends on a large number of independent factors. The rated quality of the camouflage pattern is only one of these factors. Among the others, it was aim of the experiment we performed to evaluate the statistical behavior of the random variable to be able to describe the behavior of it by a suitable type of distribution.

Spectrally based method of target detection in acquisition system of general fire control system

The Fire Control Systems fulfil the main role in the development of modern weapon systems. Nowadays it can be seen the intensive progress of exclusive parts, altered features and operating principles connecting with modern FCS. The paper deals with the marginal problem associated with the unique method of target acquisition system. Moreover, the characterization of the FCS from the perspective of its complexity is also presented in the paper.

Selected issues connected with determination of requirements of spectral properties of camouflage patterns

Traditionally spectral reflectance of the material is measured and compared with permitted spectral reflectance boundaries. The boundaries are limited by upper and lower curve of spectral reflectance. The boundaries for unique color has to fulfil the operational requirements as a versatility of utilization through the all year seasons, day and weather condition on one hand and chromatic and spectral matching with background as well as the manufacturability on the other hand. The interval between the boundaries suffers with ambivalent feature. Camouflage pattern producer would be happy to see it much wider, but blending effect into its particular background could be better with narrower tolerance limits. From the point of view of long time user of camouflage pattern battledress, there seems to be another ambivalent feature. Width of the tolerance zone reflecting natural dispersion of spectral reflectance values allows the significant distortions of shape of the spectral curve inside the given boundaries.

Hyperspectral discrimination of camouflaged target

The article deals with detection of camouflaged objects during winter season. Winter camouflage is a marginal affair in most countries due to short time period of the snow cover. In the geographical condition of Central Europe the winter period with snow occurs less than 1/12 of year. The LWIR or SWIR spectral areas are used for detection of camouflaged objects. For those spectral regions the difference in chemical composition and temperature express in spectral features. Exploitation of the LWIR and SWIR devices is demanding due to their large dimension and expensiveness. Therefore, the article deals with estimation of utilization of VIS region for detecting of camouflaged object on snow background. The multispectral image output for the various spectral filters is simulated. Hyperspectral indices are determined to detect the camouflaged objects in the winter. The multispectral image simulation is based on the hyperspectral datacube obtained in real conditions.

Tracking, aiming, and hitting the UAV with ordinary assault rifle

The usage small-unmanned aerial vehicles (UAVs) is significantly increasing nowadays. They are being used as a carrier of military spy and reconnaissance devices (taking photos, live video streaming and so on), or as a carrier of potentially dangerous cargo (intended for destruction and killing). Both ways of utilizing the UAV cause the necessity to disable it. From the military point of view, to disable the UAV means to bring it down by a weapon of an ordinary soldier that is the assault rifle. This task can be challenging for the soldier because he needs visually detect and identify the target, track the target visually and aim on the target. The final success of the soldier’s mission depends not only on the said visual tasks, but also on the properties of the weapon and ammunition. The paper deals with possible methods of prediction of probability of hitting the UAV targets.

Pixelated camouflage patterns from the perspective of hyperspectral imaging

Pixelated camouflage patterns fulfill the role of both principles the matching and the disrupting that are exploited for blending the target into the background. It means that pixelated pattern should respect natural background in spectral and spatial characteristics embodied in micro and macro patterns. The HS imaging plays the similar, however the reverse role in the field of reconnaissance systems. The HS camera fundamentally records and extracts both the spectral and spatial information belonging to the recorded scenery. Therefore, the article deals with problems of hyperspectral (HS) imaging and subsequent processing of HS images of pixelated camouflage patterns which are among others characterized by their specific spatial frequency heterogeneity.

Ability of utilization of PCA in hyperspectral anomaly detection

Hyperspectral (HS) imaging is a complex way of taking the image of the scenery, where the rich spectral information is collected for any pixel of HS image. The rich spectral information can consequently be used for finding objects or identifying specific material in military utilization of HS imaging. Finding the objects as a spectral anomaly is one of specific tasks of HS image processing.