Compton scattering beyond the impulse approximation

We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the standard IA based formula for the cross section which involves the ground state electron momentum density (EMD) of the initial state. Our formalism will permit the analysis and interpretation of electronic transitions in correlated electron systems via inelastic x-ray scattering (IXS) spectroscopy beyond the constraints of the IA and the IPM.Comment: 7 pages, 1 figur

Miscibility studies of 2”-3”-difluoro-4”-pentylterphenyl-4-yl carbonate with ferroelectric compounds

Trzy trójpierścieniowe związki chiralne tworzące fazę ferroelektryczną były domieszkowane niechiralnym difluoropodstawionym węglanem o rdzeniu terfenylowym. Zbadano wpływ struktury i ilości węglanu na stabilność iskok helisy fazy ferroelektrycznej w mieszaninach dwuskładnikowych. Stwierdzono, że stabilność termiczna fazy SmC* związków chiralnych ulega zwiększeniu. Dodawanie węglanu z rdzeniem terfenylowym w dwóch przypadkach nieznacznie zwiększa skok helisy, a w jednym nieznacznie go zmniejsza.Three chiral compounds, containing three aromatic rings in a rigid core, forming ferroelectric phase were doped with non chiral difluorosubstituted terphenyl carbonate compound. The influence of the structure and the amount of terphenyl carbonate compound on the stability and helical pitch of the ferroelectric phase in binary mixtures was examined. It was found that thermal stability of the SmC* phase of chiral compounds has increased. Addition of terphenyl carbonate compound slightly increases the helical pitch (except for one of the binary mixture)

Laser-Assisted Thermomechanical Bending of Tube Profiles

The subject of the work is the analysis of thermomechanical bending process of a thin-walled tube made of X5CrNi18-10 stainless steel. The deformation is produced at elevated temperature generated with a laser beam in a specially designed experimental setup. The tube bending process consists of local heating of the tube by a moving laser beam and simultaneous kinematic enforcement of deformation with an actuator and a rotating bending arm. During experimental investigations, the resultant force of the actuator and temperature at the laser spot are recorded. In addition to experimental tests, the bending process of the tube was modelled using the finite element method in the ABAQUS program. For this purpose, the tube deformation process was divided into two sequentially coupled numerical simulations. The first one was the heat transfer analysis for a laser beam moving longitudinally over the tube surface. The second simulation described the process of mechanical bending with the time-varying temperature field obtained in the first simulation. The force and temperature recorded during experiments were used to verify the proposed numerical model. The final stress state and the deformation of the tube after the bending process were analyzed using the numerical solution. The results indicate that the proposed bending method can be successfully used in forming of the thin-walled profiles, in particular, when large bending angles and a small spring-back effect are of interest

Laser-assisted forming of thin-walled profiles

W ostatnich latach badane są procesy kształtowania plastycznego z wykorzystaniem lokalnego nagrzewania laserowego. Nagrzewanie ma na celu umożliwienie lub ułatwienie obróbki plastycznej materiałów, które wykazują niekorzystne właściwości, jak: kruchość, silne efekty umocnienia czy powrotnego odkształcenia sprężystego. Zaprezentowane badania dotyczą hybrydowego termo-mechanicznego kształtowania plastycznego elementów cienkościennych z użyciem lokalnego nagrzewania materiału wiązką laserową. Docelowo prace są nakierowane na formowanie elementów ze stopów wykorzystywanych w przemyśle lotniczym takich, jak nadstopy niklu Inconel 625, Inconel 718, a także wysokostopowe stale martenzytyczne AISI 410 i AISI 325. Wstępne badania przeprowadzono z użyciem stali nierdzewnej X5CrNi18-10. Prace eksperymentalne i symulacje numeryczne objęły zachowanie się płaskowników o grubości 1 mm, poddanych działaniu obciążenia mechanicznego w układzie wysięgnikowym i nagrzewanych wiązką lasera CO2, przemieszczaną od swobodnego końca próbki do miejsca jej zamocowania. Doświadczalnie wykazano możliwość stosunkowo łatwego uzyskiwania dużych deformacji giętnych dzięki zastosowaniu nagrzewania laserowego. Zweryfikowane eksperymentalnie symulacje numeryczne, które wykonano metodą elementów skończonych, ujawniły intensywne płynięcie plastyczne warstwy ogrzewanej wiązką laserową. Towarzyszyło temu przemieszczanie się osi obojętnej przekroju. W kolejnym etapie badane było gięcie rur cienkościennych na specjalnie skonstruowanym stanowisku. Umożliwia ono kontrolowane wprowadzanie obciążenia mechanicznego, ogrzewanie materiału ruchomą wiązką laserową i wymuszanie zadanej deformacji zgodnie ze schematem kinematycznym urządzenia.Forming processes assisted by localised laser heating are studied in recent years. Heating is used to make it possible or facilitate forming of materials, which exhibit such adverse properties as: brittleness, effects of high work-hardening or a high elastic spring-back. The hereby presented investigations concern the hybrid thermo-mechanical forming of thin-walled parts using local heating of the material by the laser beam. The research is aimed at forming of parts from materials used in the aviation industry, such as the nickel-base super-alloys Inconel 625, Inconel 718, and also martensitic super-alloys AISI 410 and AISI 325. Preliminary investigations are conducted using X5CrNil8-10 (1.4301) stainless steel. Experimental study and numerical simulations cover the behaviour of thin beams 1 mm thick, subjected to mechanical load in the cantilever arrangement and heated by the CO2 laser beam moving from the free end of the sample towards its fixture. The possibility of obtaining large bending deformations relatively easily due to the application of laser beam is demonstrated experimentally. Experimentally verified finite element numerical simulations show the intense plastic flow of the material layer heated by the laser beam. It is accompanied by a shift of the cross-section neutral axis of the beam. Bending of thin-walled tubes in a specially designed device is studied in the next step. It allows introducing mechanical loading in a controlled manner, heating the material by a moving laser beam and forcing the required deformation according to the kinematic scheme of the device

Fish: Friend or foe? Food policy and subpopulation warnings for consumers

Fish is a healthy food that provides valuable nutrients for heart health and cognitive development. However, for some subpopulations, consuming fish containing higher levels of methylmercury may pose a health risk. This research seeks to identify the impact of including a seafood warning disclosure in the advertisement of a can of tuna fish on consumers' purchasing behaviors. An experimental survey is employed to examine the resulting impact for two segments of the population - those considered at risk for methylmercury overexposure and all others. Findings indicate the use of warning disclosures increases respondents' negative product perceptions without significantly altering positive product perceptions. Attention to the warning is short-lived and does not significantly impact perceived healthful levels of consumption. Modeling purchase behavior using a random utility choice framework indicates that the inclusion of a warning in an advertisement of a can of tuna fish has no adverse affect on purchase behaviors for the population not at-risk and may, in certain cases, serve to decrease tuna purchase likelihood for "at-risk" respondents. Communicating advisory statements on healthy products, such as fish, creates a public health challenge; message pre-testing is imperative.Fish consumption Methylmercury in fish Consumer beliefs Warning disclosure