70 research outputs found
Інтерактивний контроль при формоутворенні багатогабаритних деталей
Physical phenomenon of warping (springing) can be observed as a technological heritage after large-dimensional articles forming or curing and consequent cooling of composite articles. This phenomenon can be seen as gaps between ready article contour and forming jig contour. Deviation degree of ready article surface from theoretical contour and article dimensions has to be controlled during manufacturing. Application of auxiliary controlling jig leads to expenses and labor-manufacturability increasing. Possibility of application forming jig with inserted jet gages is considered for articles shape controlling. Such gages and realization of acoustic methods allow to control not only final article shape but also geometry on intermediate stages of manufacturing.Після формоутворення багатогабаритних листових деталей з листових механічних заготовок або полімеризації і охолодження деталей з композитних матеріалів проявляється технологічна спадковість у вигляді викривлення (пружнення). Це спостерігається у вигляді неприлягання готової деталі до формозадаючої поверхні технологічного оснащення. При контролі якості формозміни необхідно вимірювати
ступінь порушення форми і розмірів. Застосування контрольної оснастки дорого і складно. Розглянуто можливість використання для контролю формозадаючої оснастки з встановленими в ній повітряними струминними датчиками. Такі датчики і застосування акустичних методів дозволяють контролювати не тільки кінцеву форму заготовки, а й форму заготовки на попередваріантних етапах формозміни
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Oxygen-deficient oxide growth by subliming the oxide source material: The cause of silicide formation in rare earth oxides on silicon
The fundamental issue of oxygen stoichiometry in oxide thin film growth by subliming the source oxide is investigated by varying the additionally supplied oxygen during molecular beam epitaxy of RE2O3 (RE = Gd, La, Lu) thin films on Si(111). Supplying additional oxygen throughout the entire growth was found to prevent the formation of rare earth silicides observed in films grown without an oxygen source. Postgrowth vacuum annealing of oxygen stoichiometric films did not lead to silicide formation thereby confirming that the silicides do not form as a result of an interface instability at growth temperature in vacuum but rather due to an oxygen deficiency in the source vapor. The average oxygen deficiency of the rare-earth containing species in the source vapor was quantified by the 18O tracer technique and correlated with that of the source material, which gradually decomposed during sublimation. Therefore, any oxide growth by sublimation of the oxide source material requires additional oxygen to realize oxygen stoichiometric films
Coulomb driven energy boost of heavy ions for laser plasma acceleration
An unprecedented increase of kinetic energy of laser accelerated heavy ions
is demonstrated. Ultra thin gold foils have been irradiated by an ultra short
laser pulse at an intensity of W/cm. Highly charged
gold ions with kinetic energies up to MeV and a bandwidth limited
energy distribution have been reached by using Joule laser energy on
target. D and D Particle in Cell simulations show how a spatial
dependence on the ions ionization leads to an enhancement of the accelerating
electrical field. Our theoretical model considers a varying charge density
along the target normal and is capable of explaining the energy boost of highly
charged ions, leading to a higher efficiency in laser acceleration of heavy
ions
Impact of dislocations and dangling bond defects on the electrical performance of crystalline silicon thin films
A wide variety of liquid and solid phase crystallized silicon films are
investigated in order to determine the performance limiting defect types in
crystalline silicon thin-film solar cells. Complementary characterization
methods, such as electron spin resonance, photoluminescence, and electron
microscopy, yield the densities of dangling bond defects and dislocations
which are correlated with the electronic material quality in terms of solar
cell open circuit voltage. The results indicate that the strongly differing
performance of small-grained solid and large-grain liquid phase crystallized
silicon can be explained by intra-grain defects like dislocations rather than
grain boundary dangling bonds. A numerical model is developed containing both
defect types, dislocations and dangling bonds, describing the experimental
results
Modelling of Droplet Capture in an Open-Cell Metal Foam at the Pore and Macroscopic Scales
Open-cell metal foams are often used in applications where particulate and/or droplet capture is important. Here a Computational Fluid Dynamics (CFD) modelling approach is described which models the metal foam at both the pore-scale and the macroscopic scale. At the pore-scale, the detailed internal geometry of the foam is included and the flow field and droplet tracking and capture is modelled explicitly. At this scale, a coefficient is found for each metal foam that relates the distance a droplet can freely travel through the foam to both the droplet diameter and the Darcian velocity in the porous medium. Then, at the macroscopic scale, the coefficient from the pore-scale droplet capture simulations is used in a novel stochastic particle extinction model. Here, the droplets travel through a porous zone and are removed from the model, the probability of which is determined by the coefficient from the pore-scale modelling. A test case is described in which the macroscopic model is verified against the pore-scale model with acceptable levels of accuracy
Securing the Downside Up: Client and Care Factors Associated with Outcomes of Secure Residential Youth Care
Although secure residential care has the potential of reducing young people's behavioral problems, it is often difficult to achieve positive outcomes. Research suggests that there are several common success factors of treatment, of which the client's motivation for treatment and the quality of the therapeutic relationship between clients and therapists might be especially relevant and important in the context of secure residential care. The objective of the present study was to explore the association of these potential success factors with secure residential care outcomes. A repeated measures research design was applied in the study, including a group of adolescents in a secure residential care center that was followed up on three measurements in time. Interviews and questionnaires concerning care outcomes in terms of adolescents' behavior change during care were administered to 22 adolescents and 27 group care workers. Outcomes in terms of adolescents' treatment satisfaction were assessed by the use of questionnaires, which were completed by 51 adolescents. Adolescents reported some positive changes in their treatment motivation, but those who were more likely to be motivated at admission were also more likely to deteriorate in treatment motivation from admission to departure. Treatment satisfaction was associated with better treatment motivation at admission and with a positive adolescent-group care worker relationship. The results suggest that outcomes can be improved by a more explicit treatment focus on improving the adolescent's treatment motivation and the quality of the adolescent-care worker relationship during secure residential care
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