Testing the Dynamics of Flight for the Products of Explosion for a Warhead with a Weight of 250 kg

This study presents the results of the testing of the explosion process of a warhead with a weight of 250 kg, filled with 87 kg of TNT with 20% of aluminium dust, in two configurations: with horizontal and vertical alignment of the warheads longitudinal axis, and with the centre of length of the warhead body located at a height of approx. 1 m above the ground. Four warheads were detonated in each configuration. The horizontal configuration allowed the collection of some amount of the fragments from the ground, with sizes and spatial distribution of the fragments corresponding to the location on the body from which they came, with the largest fragments from the central part of the shell measuring approximately 9 30 280 mm. For the vertical configuration, the warheads nose was pointed downwards, with an up-down excitation. In both configurations, the explosion process was recorded from a distance of 300 m using a PHANTOM fast camera with a time resolution (frame interval) of 55 s to 133 s: for the horizontal configuration along the bodys longitudinal axis, for the vertical configuration perpendicular to this axis. In the vertical configuration, the bodys expansion process was recorded using short-circuit sensors spaced every 5 mm along the flight radius. The sensors sent short-circuit signals to the time meter, whereas the first sensor was installed at a distance of approx. 1 mm from the body surface and was used to initiate the processes of time counting and recording the overpressure diagrams over time at the front of the explosion/shock (FU) wave. The recorded expansion velocity was approx. 1300 m/s, with the shell radius increasing by 20 mm. Overpressure at the front of the FU was measured by PCB pencil-tip piezoelectric sensors (CzP). Every sensor had two active surfaces arranged in tandem at a distance of 100 mm, which made it possible to determine the local FU velocity. Signals from CzP were recorded every 200 ns using a DEWETRON recorder with software allowing their initial and further processing. Three sensors were spaced 8 m from each other, whereas the first was located 8 m to 10 m from the warheads longitudinal axis. Under a row of the sensors a thick-wall steel pipe was placed to protect the sensors from destruction by the fragments. The determined local FU velocities varied from approx. (590 m/s to 740 m/s) at a distance of approx. 8 m from the epicentre up to approx. 370 m/s at a distance of approx. 26 m from the epicentre; the overpressure measured values varied from approx. (230 kPa to 550 kPa) at a distance of approx. 8 m to approx. 22 kPa at a distance of approx. 26 m from the epicentre; satisfying conformance of the velocity and pressure values under the flat FU model was found. The FU trajectory was also taken from the video recording the velocities measured varied from approx. 2,650 m/s at a distance of 0.3 m to approx. 670 m/s at a distance of 6 m from the epicentre, which corresponds to the CzP data. The fragments flying next to the CzP, generally with the highest mass to effective transverse surface ratio, left traces of their conical FU on the CzP overpressure records, which allowed the determination of average velocities for some of them across the access path to the CzP, whereas these velocities ranged from approx. 1700 m/s at a distance of approx. 8 m and (1500 m/s to 1600 m/s) at a distance of 16 m to approx. 1300 to 1400 m/s at a distance of 26 m from the epicentre. Average access velocities of the selected fragments to the field marks were determined on the basis of the video recording ranged from approx. 1800 m/s at a distance of 5 m to approx. 1500 m/s at a distance of 20 m from the explosion epicentre

Influence of environment on the corrosion of glass–metal connections

'Glass sensors' of the eighteenth century Backer glass and the sixteenth century enamel from Limoges have been chosen for a series of experiments. Combinations of these materials with different base materials such as copper and bronze has been investigated. To create surface changes on the 'glass sensor', a corrosion process was induced in a controlled environment. A variety of corrosive agents such as hydrochloric acid, sulfuric acid, water and formaldehyde were used. The sample immersed in the corrosive solution was exposed alternately to light and high temperature for a total of 38 weeks. During this period, macroscopic and microscopic observations were made and series of tests such as SEM/EDS and Raman spectroscopy were performed on the surface of the samples. ICP-MS methods were used to determine the change in the chemical composition of the solutions where the samples had corroded. The primary aim of this study was to identify the impact of a number of external corrosive variables such as temperature, humidity and local environment to identify the most damaging environments for glass–metal objects. The obtained results showed the chemical and physical phenomena acting on the surface of the glass, metal or in the place of their joints. Information obtained on this study was used to explain the influence of the environment on the surface of glass–metal materials. Results can be used in the design of conservation work as well as for sustainable conservation

Analysis of the impact of sex and age on the variation in the prevalence of antinuclear autoantibodies in Polish population: a nationwide observational, cross-sectional study

The detection of antinuclear autoantibody (ANA) is dependent on many factors and varies between the populations. The aim of the study was first to assess the prevalence of ANA in the Polish adult population depending on age, sex and the cutoff threshold used for the results obtained. Second, we estimated the occurrence of individual types of ANA-staining patterns. We tested 1731 patient samples using commercially available IIFA using two cutoff thresholds of 1:100 and 1:160. We found ANA in 260 participants (15.0%), but the percentage of positive results strongly depended on the cutoff level. For a cutoff threshold 1:100, the positive population was 19.5% and for the 1:160 cutoff threshold, it was 11.7%. The most prevalent ANA-staining pattern was AC-2 Dense Fine speckled (50%), followed by AC-21 Reticular/AMA (14.38%) ANA more common in women (72%); 64% of ANA-positive patients were over 50 years of age. ANA prevalence in the Polish population is at a level observed in other highly developed countries and is more prevalent in women and elderly individuals. To reduce the number of positive results released, we suggest that Polish laboratories should set 1:160 as the cutoff threshold

Skuteczność wybranych metod estymacji mocnej a poziom niezawodności sieci

The work presents the results of studies on dependence of effectiveness of chosen robust estimation methods from the internal reliability level of a geodetic network. The studies use computer-simulated observation systems, so it was possible to analyse many variants differing from each other in a planned way. Four methods of robust estimation have been chosen for the studies, differing substantially in the approach to weight modifications. For comparative reasons, the effectiveness studies have also been conducted for the very popular method in surveying practice, of gross error detection basing on LS estimation results, the so called iterative data snooping. The studies show that there is a relation between the level of network internal reliability and the effectiveness of robust estimation methods. In most cases, in which the observation contaminated by a gross error was characterized by a low index of internal reliability, the robust estimation led to results being essentially far from expectations.W pracy przedstawiono wyniki badan nad zależnością skuteczności wybranych metod estymacji odpornej od poziomu niezawodności wewnętrznej sieci geodezyjnej. W badaniach wykorzystano symulowane komputerowo układy obserwacyjne, dzięki czemu możliwe było przeanalizowanie wielu wariantów różniących się w zaplanowany sposób. Do badan wybrano cztery metody estymacji odpornej różniące się istotnie podejściem do modyfikacji wag. Dla porównania, badaniom skuteczności poddano również popularna w praktyce geodezyjnej metodę wykrywania błędów grubych bazująca na wynikach estymacji MNK, tzw. metodę Baardy. Z przeprowadzonych badan wynika, ze istnieje związek pomiędzy poziomem niezawodności wewnętrznej sieci a skutecznością metod estymacji odpornej. W większości przypadków, w których obserwacja obarczona błędem grubym charakteryzowała się niskim wskaźnikiem niezawodności wewnętrznej, estymacja odporna prowadziła do uzyskania wyników istotnie odbiegających od oczekiwanych

Comparative analysis of different manners of execution of huber's robust estimation

Observations made in geodetic network must be processed in order to find the parameters that we search for, such as coordinates of points or their displacement. In practice, the most popular method used for this purpose is the least squares adjustment. However, according to research, it is susceptible to gross errors in observations. In recent years, the so-called robust estimation methods have gained great popularity. In these methods, the impact of gross errors is eliminated by iterative modification of observation weights. One of these methods is Huber’s robust estimation, in which the objective function is a spline. For observations with residuals within the assumed range, the component of the objective function is identical to objective function in the method of least squares. However, for the remaining observations the component of the objective function is similar to that in the least absolute deviations method. In literature, various ways of implementation of Huber’s method have been described. The study presents results of numerical analyses of effectiveness of Huber’s method. Various approaches to weight modification, described in literature, have been applied. Conclusions on research conducted have been presented

Algorithm of determining the coexistence levels of unknowns and thier binding functions in linear equation systems

The study presents a unified algorithm of determining the coexistence levels in any system of linear equations. The coesistence levels can be determined both for the system unknowns (or groups of) as well as for functions binding those unknowns (equations or their groups). Because we deal with systems of linear equations also in geodetic networks, the presented algorithm allows the determination of coexistence levels of network points or observations made within that network. Due to the possibility of grouping of unknowns and equations in the algorithm, there are no limitations of space for the geodetic network. The functioning of the presented algorithm has been iIlustrated by the example of a linear, horizontal geodetic network. Exemplary tasks have also been shown, in which the coexistence levels can be helpful

Analysis of the results of monitoring of bucket wheel excavator’s superstructure effort

W artykule przestawiono przykładowe wyniki analizy statystycznej rozkładów naprężeń w wybranych punktach ustroju nośnego koparki kołowej. Wyniki uzyskane zostały podczas wielomiesięcznych pomiarów, a więc bez wiadomości o uzyskiwanej wydajności orz rodzaju urabianych skał. Są te wyniki źródłem ogólnej wiedzy o wytężeniu ustroju nośnego podczas eksploatacji maszyny, są zatem miarodajne dla oszacowania stopnia jej degradacji.The paper presents examples of the results of the statistical analysis of stress distribution at selected points of the superstructure of bucket wheel excavator. The results were obtained during several months of measurement, without knowledge of the obtained work load and the type of mined rocks. These results are a source of general knowledge about effort of the superstructure during the operation of the machine. They are therefore meaningful to estimate the degree of machine’s degradadion