CMB Observations: improvements of the performance of correlation radiometers by signal modulation and synchronous detection

Observation of the fine structures (anisotropies, polarization, spectral distortions) of the Cosmic Microwave Background (CMB) is hampered by instabilities, 1/f noise and asymmetries of the radiometers used to carry on the measurements. Addition of modulation and synchronous detection allows to increase the overall stability and the noise rejection of the radiometers used for CMB studies. In this paper we discuss the advantages this technique has when we try to detect CMB polarization. The behaviour of a two channel correlation receiver to which phase modulation and synchronous detection have been added is examined. Practical formulae for evaluating the improvements are presented.Comment: 18 pages, 3 figures, New Astronomy accepte

Multistage Switching Architectures for Software Routers

Software routers based on personal computer (PC) architectures are becoming an important alternative to proprietary and expensive network devices. However, software routers suffer from many limitations of the PC architecture, including, among others, limited bus and central processing unit (CPU) bandwidth, high memory access latency, limited scalability in terms of number of network interface cards, and lack of resilience mechanisms. Multistage PC-based architectures can be an interesting alternative since they permit us to i) increase the performance of single software routers, ii) scale router size, iii) distribute packet manipulation and control functionality, iv) recover from single-component failures, and v) incrementally upgrade router performance. We propose a specific multistage architecture, exploiting PC-based routers as switching elements, to build a high-speed, largesize,scalable, and reliable software router. A small-scale prototype of the multistage router is currently up and running in our labs, and performance evaluation is under wa

Irescenari. Secondo rapporto triennale sugli scenari evolutivi del Piemonte 2004/7. Lo sviluppo della società dell'informazione in Piemonte tra tradizione industriale e nuove opportunità

Irescenari ; 2004/7- Indice #5- Presentazione #7- Il contesto internazionale: dagli eccessi della New Economy alle ICT come elemento di trasformazione delle imprese e della società dell'informazione #9- Problemi di metodo nella misurazione #13- Le diffusione della società dell'informazione in Piemonte #17- Il settore ICT in Piemonte: struttura, caratteristiche e prospettive di sviluppo #28- Gli scenari di sviluppo per il settore ICT e per la società dell'informazione in Piemonte #41- Riferimenti bibliografici #4