29 research outputs found
PROTON RADIOGRAPHY WITH THE PIXEL DETECTOR TIMEPIX
This article presents the processing of radiographic data acquired using the position-sensitive hybrid semiconductor pixel detector Timepix. Measurements were made on thin samples at the medical ion-synchrotron HIT [1] in Heidelberg (Germany) with a 221 MeV proton beam. The charge is energy by the particles crossing the sample is registered for generation of image contrast. Experimental data from the detector were processed for derivation of the energy loss of each proton using calibration matrices. The interaction point of the protons on the detector were determined with subpixel resolution by model fitting of the individual signals in the pixelated matrix. Three methods were used for calculation of these coordinates: Hough transformation, 2D Gaussian fitting and estimate the 2D mean. Parameters of calculation accuracy and calculation time are compared for each method. The final image was created by method with best parameters
Analysis and Parameter Identification of Automatic Cannon Carriages
Experimental procedures for the research of vibrations in automatic weapons mounted on combat vehicles is introduced. Experiment preparation procedures, experience and examples of evaluation of measured results in direct fire from a tracked combat vehicle are explained on BMP-2 IFV example. The result is the movements of the turret and the hull of a combat vehicle in single shot firing, and short and long burst firing. In addition to time domain analysis, methods of correlation and spectral analysis are used. Live firing experiments are complemented by laboratory experiments and are used to determine model parameters for calculations such as stiffness and damping in the suspensions of the hull, elevation parts, clearance in the elevating gear, and the natural vibration frequency of the hull and elevation parts
REFLECT – Research flight of EURADOS and CRREAT: Intercomparison of various radiation dosimeters onboard aircraft
Aircraft crew are one of the groups of radiation workers which receive the highest annual exposure to ionizing
radiation. Validation of computer codes used routinely for calculation of the exposure due to cosmic radiation
and the observation of nonpredictable changes in the level of the exposure due to solar energetic particles, requires continuous measurements onboard aircraft. Appropriate calibration of suitable instruments is crucial,
however, for the very complex atmospheric radiation field there is no single reference field covering all particles
and energies involved. Further intercomparisons of measurements of different instruments under real flight
conditions are therefore indispensable.
In November 2017, the REFLECT (REsearch FLight of EURADOS and CRREAT) was carried out. With a
payload comprising more than 20 different instruments, REFLECT represents the largest campaign of this type
ever performed. The instruments flown included those already proven for routine dosimetry onboard aircraft
such as the Liulin Si-diode spectrometer and tissue equivalent proportional counters, as well as newly developed
detectors and instruments with the potential to be used for onboard aircraft measurements in the future. This
flight enabled acquisition of dosimetric data under well-defined conditions onboard aircraft and comparison of
new instruments with those routinely used.
As expected, dosimeters routinely used for onboard aircraft dosimetry and for verification of calculated doses
such as a tissue equivalent proportional counter or a silicon detector device like Liulin agreed reasonable with each other as well as with model calculations. Conventional neutron rem counters underestimated neutron
ambient dose equivalent, while extended-range neutron rem counters provided results comparable to routinely
used instruments. Although the responses of some instruments, not primarily intended for the use in a very
complex mixed radiation field such as onboard aircraft, were as somehow expected to be different, the verification of their suitability was one of the objectives of the REFLECT. This campaign comprised a single short
flight. For further testing of instruments, additional flights as well as comparison at appropriate reference fields
are envisaged. The REFLECT provided valuable experience and feedback for validation of calculated aviation
doses
Control Problems of Classical Type of Microtron and Application of Fuzzy Logic Controller
This work deals with control problems of the classical microtron with Kapitza type of the accelerating cavity. Fuzzy controller is used. The main problem, which led to use this type of controller, is a problematical measurement of the radio-frequency electric field inside accelerating cavity. Careful setting of this electric field is necessary for accelerating condition fulfillment
Computing of MT 25 Microtron Dynamic Behavior and Fast Simulation
This paper presents the design of a mathematical model and its fast simulation developed for the setup of the control system of the MT 25 microtron, which is a cyclic electron accelerator. This type of accelerator has been controlled manually until now. The mathematical model is based on calculations of the electron motion in the accelerating cavity and vacuum chamber. The simulation diagram was created in Matlab – Simulink
Data from: Context-dependence of maternal effects: testing assumptions of optimal egg size, differential- and sex-allocation models
If offspring develop in adverse conditions, the maternal component of their phenotypic variation might increase due to the stronger dependence of offspring traits on parental investment. This should result in increased parental investment to individual offspring, as assumed by the model of optimal egg size. The opposite pattern, i.e., stronger dependence of offspring fitness on parental investment and consequently larger parental investment under good conditions is assumed by both the theory of differential allocation if attractive males provide material benefits, and reproductive compensation if they invest less into paternal care. Another influential idea is the Trivers-Willard model, which assumes sex-specific dependence of offspring fitness on parental investment. Here we tested these ideas by examining the effects of egg size on offspring fitness across many postnatal contexts in the Collared Flycatcher Ficedula albicollis. We employed a cross-fostering design that generated variation in egg size within nests and used brood means of fledgling mass as a functional measure of the quality of rearing conditions. Effects of egg size on three offspring traits, including lifetime reproductive success of recruits, were more pronounced in low-quality broods. These results support the assumption of the model of optimal egg size. Based on female preference for males providing material benefits, this pattern could support differential allocation, if attractive males invest less in paternal care, or reproductive compensation, if they invest more. By comparison, we did not find any evidence for sex specificity of fitness returns that might explain sex monomorphism of egg size in this species. The challenge for future studies will be the integration of components of parental investment and offspring fitness into their global measures and testing how the former affects the latter across gradients of postnatal conditions
Data from: Female collared flycatchers choose neighbouring and older extra-pair partners from the pool of males around their nests
Extra-pair copulation is common among passerine birds. Females might engage in this behavior to obtain direct or indirect benefits. They may choose extra-pair males with larger ornaments, especially if they are costly to produce. Here we studied extra-pair paternity in the collared flycatcher. Genetic analysis allowed us to identify the presence or absence of extra-pair young in the focal nests, and to identify extra-pair fathers. We also identified potential males available as extra-pair sires around the nests of females who had extra-pair young. First, we tested the relationship between paternity in own nest and ornament size (wing patch and/or forehead patch), morphological traits and age of social males and females. Second, we compared the same suite of traits among social mates, extra-pair males and all potential extra-pair mates. Finally, we investigated the effect of the size of ornaments on the distance between the social nest and that of nest the extra-pair father. Contrary to our prediction, males with larger ornaments and longer wings lost more paternity in their nests. We also found that early breeders lost less paternity in their nests. Extra-pair males were older and had longer wings than social and potential extra-pair males. Females mainly obtained extra-pair mates near their nests but the distance did not vary according to ornamentation. These results could potentially be explained by differences in mate guarding strategy as older males may be more experienced in guarding their mate and attract other females more easily. More data about mate guarding and prospecting are needed to increase our understanding of mechanisms underlying the extra-pair paternity in birds