Ve dnech 28. 6.-2. 7. 2009 proběhl v Praze 11. ročník významné mezinárodní konference věnované vývoji detektorů pro zobrazování s pomocí ionizujícího záření - 11th iWoRiD 2009 (International Workshops on Radiation Imaging Detectors). Hostitelskou organizací bylo ČVUT v Praze a hlavním organizátorem celé akce Ústav technické a experimentální fyziky ČVUT (ÚTEF).
. and Stanislav Pospíšil.
Behavior of slender aero-elastic systems in a sub-critical domain including position of the lowest critical state is commonly investigated using double degree of freedom (DDOF) linear model. The most frequently used are neutral models treating aero-elastic forces as certain constants corresponding to system parameters and stream velocity. Although this approach is working well, it shows a number of shortcomings. For this reason modeling by flutter derivatives or indicial functions has been launched. However, these two groups of models have been developed separately one from each other. It seems they are rather isolated until now. Moreover they mostly suffer from various gaps in mathematical formulations and further treatment. The paper tries to put all three groups together on one common basis and to demonstrate linkage of them. This approach allows formulate more sophisticated models combining main aspects of all groups in question keeping the DDOF basis. These models correspond by far better to results of wind channel and full scale measurements. and Obsahuje seznam literatury
Double degree of freedom (DDOF) linear systems are frequently used to model the aero-elastic response of slender prismatic systems until the first critical state is reached. Relevant mathematical models appearing in literature differ in principle by way of composition of aero-elastic forces. This criterion enables to sort them roughly in three groups: (i) neutral models - aero-elastic forces are introduced as suitable constants independent from excitation frequency and time; (ii) flutter derivatives - they respect the frequency dependence of aero-elastic forces; (iii) indicial functions - they are defined as kernels of convolution integrals formulating aero-elastic forces as functions of time. The paper tries to put all three groups together on one common basis to demonstrate their linkage and to eliminate gaps in mathematical formulations between them. This approach allows formulate more sophisticated models combining main aspects of all groups in question keeping the DDOF basis. These models correspond by far better to results of wind tunnel and full scale measurements. and Obsahuje seznam literatury
V příspěvku je uveden souhrn vědeckých programů a aktivit Ústavu technické a experimentální fyziky jako vědecko-pedagogického pracoviště ČVUT v Praze zaměřeného na experimentální fyziku mikrosvěta a její aplikace., Stanislav Pospíšil., and Obsahuje seznam literatury
Polovodičový pixelový detektor Timepix je novým členem rodiny Medipix. Konstrukčně se Timepix neodlišuje od svého předchůdce, kterým je detektor Medipix2. Každý pixel detektoru je i zde vybaven předzesilovačem, diskriminátorem a čítačem. Čítač je však možno v každém pixelu nastavit do jednoho ze tří režimů. Prvním režimem (čítač) je prosté počítání částic. Druhý režim (časovač) umožňuje stanovit dobu detekce částice. V tomto textu se zaměříme na využití posledního režimu (Wilkinsonův AD převodník), který dovoluje přímé měření energie detekovaných částic. Tato vlastnost otevírá mnoho možností využití. V článku se budeme věnovat zejména aplikacím v oboru energeticky citlivé radiografie., Jan Jakůbek, Andrea Cejnarová, Stanislav Pospíšil, Josef Uher., and Obsahuje bibliografii
Many theoretical models of slender prismatic beams in a cross-wind have been developed during last decades. They mostly follow various types of the linear approach. Therefore their applicability is very limited especially for prediction of the system post-critical behavior. The subject considered in this paper represents a part of a complex theoretical background of the general nonlinear model which would enable fo predict any system reaction in the pre- and post-critical domain. In particular, the aeroelastic self-induced oscillaton of a mechanical system with generalized single degree of freedom (SDOF) is discussed. The motion is described by an ordinary differential equation of Duffing type with special generalized aero-elastic damping of Van der Pol type. A new semi-analytical approach is introduced to identify the limit cycles both stable and unstable. The latter are not possible to be identified by means of experiments nor by the numerical integration. and Obsahuje seznam literatury