Search results for "DCA"
showing 10 items of 188 documents
Soft proton exchanged channel waveguides in congruent lithium tantalate for frequency doubling
2010
We report on stable optical waveguides fabricated by soft-proton exchange in periodically-poled congruent lithium tantalate in the a-phase. The channel waveguides are characterized in the telecom wavelength range in terms of both linear properties and frequency doubling. The measurements yield a nonlinear coefficient of about 9.5pm/V, demonstrating that the nonlinear optical properties of lithium tantalate are left nearly unaltered by the process. (C) 2010 Optical Society of America
A Novel Multi-hop Broadcasting Method for VANETs Based on Autonomic Computing Paradigm
2014
One of the three best papers, Selected for the Annals of Telecommunications journal; International audience; Broadcasting is widely used in Vehicular Ad hoc Networks (VANETs) but it is hard to achieve efficiently since it depends on the network density, i.e. may cause network congestion if the protocols are not well designed. This paper introduces a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an online adaptation to the network characteristics. The aim is to make effective use of radio resources when there are many messages to send imu…
Choosing to Work? Mothers Return-to-Work Decisions, Social Class, and the Local Labor Market
2015
The aim of this study is to examine the ways in which social class shapes the return-to-work decisions of Finnish working-class and middle-class mothers, and how these decisions are structured by the constraints and opportunities mothers face in the local labor market. The focus of the study is in the local labor market of the city of Jyväskylä. The data consist of two semi-structured focus group interviews of 14 employed mothers of below school-age children. Using the framework of “gendered moral rationalities,” the study shows that there are similarities in mothers’ experiences, while the structural constraints mothers faced when deciding about the timing of returning back to work differ.…
Meat substitutes: formulations and comparative analysis
2021
The nutritional quality of animal products is often overlooked in our consumers' imaginations. Sustainability for example, must takeinto account sustainability for humans, starting with meeting their nutritional needs as naturally as possible. For starters, the protein intake, inquantity per 100 g of edible food (usually cooked), greatly exceeds those of vegan equivalents, whether they are meat analogues made fromvegetable proteins or vegetarian dishes reputed to be sources of protein (chickpeas, hummus, lentils, tofu etc.). In addition, it is clear that animalproducts are protein sources of high nutritional quality (DIAAS 80) unlike vegetarian equivalents (DIAAS 80). Animal proteins ar…
A comparison of physical activity levels in childcare contexts among Finnish and Dutch three-year-olds
2016
The aim of the current study was to determine Finnish and Dutch three-year-old preschool children's physical activity (PA) levels and how levels vary across gender, location, time of day and social contexts in both countries. A modified version of the Observational System for Recording Physical Activity in Children-Preschool (OSRAC-P) was used to measure children's PA levels and contextual variables (e.g. group composition, prompts) of children attending childcare centres in Finland and the Netherlands. In total, 90 Finnish children (46 boys and 44 girls) and 97 Dutch children (46 boys and 51 girls) were observed. Three-level linear regression analyses with cross level interactions were use…
Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers
2016
To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accura…
Coll Positioning systems: a two-dimensional approach
2006
The basic elements of Coll positioning systems (n clocks broadcasting electromagnetic signals in a n-dimensional space-time) are presented in the two-dimensional case. This simplified approach allows us to explain and to analyze the properties and interest of these relativistic positioning systems. The positioning system defined in flat metric by two geodesic clocks is analyzed. The interest of the Coll systems in gravimetry is pointed out.
Digitale Fenster für γ-γ-Koinzidenzmessungen mit Halbleiterdetektoren
1968
Zusammenfassung Digital windows have been designed and built to avoid the disadvantages of normal single channel analysers setting the gate in γ-γ-coincidence experiments with two Ge(Li)-detectors.
Hidden Oscillations in Electromechanical Systems
2016
In this paper an electromechanical system with two different types of motor is considered. It is shown that during the spin-up, the system with DC motor may experience unwanted vibration—the Sommerfeld effect. This is a well-known effect when the motor of electromechanical system gets stuck near the resonance zone instead of reaching its nominal power. The absence of this effect is demonstrated in the system with synchronous motor. Nowadays, there are many works devoted to the study of this effect in various systems. Here we discuss the Sommerfeld effect from the point of view of localization of the so-called hidden oscillations.
An evaluation of exposure metrics in an epidemiologic study on radio and television broadcast transmitters and the risk of childhood leukemia.
2009
Electric field strength values calculated by wave propagation modeling were applied as an exposure metric in a case–control study conducted in Germany to investigate a possible association between radio frequency electromagnetic fields (RF-EMF) emitted from television and radio broadcast transmitters and the risk of childhood leukemia. To validate this approach it was examined at 850 measurement sites whether calculated RF-EMF are an improvement to an exposure proxy based on distance from the place of residence to a transmitter. Further, the agreement between measured and calculated RF-EMF was explored. For dichotomization at the 90% quantiles of the exposure distributions it was found that…