Sökning: "digital topology"

Visar resultat 36 - 40 av 57 avhandlingar innehållade orden digital topology.

1. 36. Physisorption of CO and N2O on ceria surfaces

   Författare :Carsten Müller; Kersti Hermansson; Konstantin Neyman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ceria; carbon monoxide; nitrous oxide; embedded cluster; physisorption; method of increments; CCSD T ; vibrational frequencies; Quantum chemistry; Kvantkemi; Quantum Chemistry; kvantkemi;

   Sammanfattning : Physisorption of CO and N2O on surfaces of ceria (CeO2) was investigated by means of high-level quantum-mechanical embedded cluster calculations. Both systems have high relevance in the field of environmental chemistry and heterogeneous catalysis. LÄS MER

3. 37. Magnetic Reconnection in Space Plasmas : Cluster Spacecraft Observations

   Författare :Alessandro Retinò; Mats André; Andris Vaivads; Bengt U. Ö. Sonnerup; Uppsala universitet; []
   Nyckelord :Space and plasma physics; space physics; plasma astrophysics; plasma physics; transport processes; boundary layers; magnetic reconnection; turbulence; particle acceleration; solar system; magnetospheres; Rymd- och plasmafysik;

   Sammanfattning : Magnetic reconnection is a universal process occurring at boundaries between magnetized plasmas, where changes in the topology of the magnetic field lead to the transport of charged particles across the boundaries and to the conversion of electromagnetic energy into kinetic and thermal energy of the particles. Reconnection occurs in laboratory plasmas, in solar system plasmas and it is considered to play a key role in many other space environments such as magnetized stars and accretion disks around stars and planets under formation. LÄS MER

4. 38. Magnetic fields and chemical maps of Ap stars from four Stokes parameter observations

   Författare :Naum Rusomarov; Oleg Kochukhov; Nikolai Piskunov; Werner Weiss; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; chemically peculiar stars; magnetic fields; spectropolarimetry; Doppler imaging; stellar atmospheres; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik; Astronomy; Astronomi;

   Sammanfattning : Our knowledge of stellar magnetic fields relies almost entirely on circular polarization observations, which has historically limited our understanding of the stellar magnetic field topologies. Recently, it has become possible to obtain phase-resolved high-resolution spectropolarimetric observations in all four Stokes parameters for early-type magnetic stars. LÄS MER

5. 39. CMOS Data Converters for Closed-Loop mmWave Transmitters

   Författare :Victor Åberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; CMOS; SAR ADC; IQ-modulator; Data converter; mmWave; RF-DAC;

   Sammanfattning : With the increased amount of data consumed in mobile communication systems, new solutions for the infrastructure are needed. Massive multiple input multiple output (MIMO) is seen as a key enabler for providing this increased capacity. With the use of a large number of transmitters, the cost of each transmitter must be low. LÄS MER

7. 40. Wideband Sigma-Delta Modulators

   Författare :Xiaolong Yuan; Svante Signell; Jakob Wikner; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sigma-delta modulator; feedforward; reconfigurable; quadrature bandpass filtering; Electronics; Elektronik;

   Sammanfattning : Sigma-delta modulators (SDM) have come up as an attractive candidatefor analog-to-digital conversion in single chip front ends thanks to the continuousimproving performance. The major disadvantage is the limited bandwidthdue to the need of oversampling. LÄS MER