Introduction of ramp-type technology in HTS quasiparticle injection devices

Injection of quasiparticles with an energy larger than the superconducting gap into a superconducting strip results in breaking of Cooper-pairs and hence the suppression of the superconducting properties. Experiments using planar injection devices made of HTS materials with various barrier materials showed current gains varying from 2 up to 15 at 77 K. By changing the junction size and therefore the superconducting volume the current gain could be increased. A further reduction of the junction volume is very difficult using the planar device geometry. However, by applying the ramp-type technology it is possible to reduce the junction volume by at least one order of magnitude and a further increase in current gain is expected. Another advantage of this technology is the formation of in-situ barriers and electrodes and hence a better control of the junction characteristics should be possible, also the compatibility with the processes involved making RSFQ devices can be interesting for later applications. We have fabricated ramp-type injection devices, using various types of barriers. Characterization of these devices has been performed and the results of these experiments will be presented and discussed

HTS quasiparticle injection devices with large current gain at 77 K

Recent progress on the development of planar QP-injection devices using YBCO and STO as an epitaxial injection barrier will be discussed. The main problem for HTS injection devices is to grow reliably a well defined, ultra-thin tunneling barrier suitable for QP tunneling. For this purpose, we used inverted cylindrical magnetron sputtering to first optimize the smoothness of our YBCO films by controlling tightly an relevant sputtering conditions. We are able to prepare smooth (001) YBCO films on (001) STO substrates on a routine basis with an average roughness varying between 1 and 2 nm. With these flat YBCO films both planar as well as grain boundary junctions were fabricated using epitaxial STO barriers between 2 and 8 nm thick and a 50 nm of Au counter electrode. Planar junctions with 6 nm STO barriers were in most cases fully insulating, in some cases, a current gain of up to 7.4 at 77 K was obtained. For 3 nm STO barriers, the highest current gain was 15 at 81 K. The injection results also show a scaling behavior with junction size. Based on the present materials development and device understanding, we consider a current gain of up to 20 at 77 K possibl

Exploiting programmable architectures for WiFi/ZigBee inter-technology cooperation

The increasing complexity of wireless standards has shown that protocols cannot be designed once for all possible deployments, especially when unpredictable and mutating interference situations are present due to the coexistence of heterogeneous technologies. As such, flexibility and (re)programmability of wireless devices is crucial in the emerging scenarios of technology proliferation and unpredictable interference conditions. In this paper, we focus on the possibility to improve coexistence performance of WiFi and ZigBee networks by exploiting novel programmable architectures of wireless devices able to support run-time modifications of medium access operations. Differently from software-defined radio (SDR) platforms, in which every function is programmed from scratch, our programmable architectures are based on a clear decoupling between elementary commands (hard-coded into the devices) and programmable protocol logic (injected into the devices) according to which the commands execution is scheduled. Our contribution is two-fold: first, we designed and implemented a cross-technology time division multiple access (TDMA) scheme devised to provide a global synchronization signal and allocate alternating channel intervals to WiFi and ZigBee programmable nodes; second, we used the OMF control framework to define an interference detection and adaptation strategy that in principle could work in independent and autonomous networks. Experimental results prove the benefits of the envisioned solution

The Informational Role of the Media in Private Lending

ABSTRACT We investigate whether a borrower's media coverage influences the syndicated loan origination and participation decisions of informationally disadvantaged lenders, loan syndicate structures, and interest spreads. In syndicated loan deals, information asymmetries can exist between lenders that have a relationship with a borrower and less informed, nonrelationship lenders competing to serve as lead arranger on a syndicated loan, and also between lead arrangers and less informed syndicate participants. Theory suggests that the aggressiveness with which less informed lenders compete for a loan deal increases in the sentiment of public information signals about a borrower. We extend this theory to syndicated loans and hypothesize that the likelihood of less informed lenders serving as the lead arranger or joining a loan syndicate is increasing in the sentiment of media‐initiated, borrower‐specific articles published prior to loan origination. We find that as media sentiment increases (1) outside, nonrelationship lenders have a higher probability of originating loans; (2) syndicate participants are less likely to have a previous relationship with the borrower or lead bank; (3) lead banks retain a lower percentage of loans; and (4) loan spreads decrease

The Informational Role of the Media in Private Lending

We investigate whether a borrower’s media coverage influences the syndicated loan origination and participation decisions of informationally disadvantaged lenders, loan syndicate structures, and interest spreads. In syndicated loan deals, information asymmetries can exist between lenders that have a relationship with a borrower and less informed, nonrelationship lenders competing to serve as lead arranger on a syndicated loan, and also between lead arrangers and less informed syndicate participants. Theory suggests that the aggressiveness with which less informed lenders compete for a loan deal increases in the sentiment of public information signals about a borrower. We extend this theory to syndicated loans and hypothesize that the likelihood of less informed lenders serving as the lead arranger or joining a loan syndicate is increasing in the sentiment of mediaâ initiated, borrowerâ specific articles published prior to loan origination. We find that as media sentiment increases (1) outside, nonrelationship lenders have a higher probability of originating loans; (2) syndicate participants are less likely to have a previous relationship with the borrower or lead bank; (3) lead banks retain a lower percentage of loans; and (4) loan spreads decrease.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136338/1/joar12131_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136338/2/joar12131.pd

Mandate-driven networking eco-system : a paradigm shift in end-to-end communications

The wireless industry is driven by key stakeholders that follow a holistic approach of "one-system-fits-all" that leads to moving network functionality of meeting stringent End-to-End (E2E) communication requirements towards the core and cloud infrastructures. This trend is limiting smaller and new players for bringing in new and novel solutions. For meeting these E2E requirements, tenants and end-users need to be active players for bringing their needs and innovations. Driving E2E communication not only in terms of quality of service (QoS) but also overall carbon footprint and spectrum efficiency from one specific community may lead to undesirable simplifications and a higher level of abstraction of other network segments may lead to sub-optimal operations. Based on this, the paper presents a paradigm shift that will enlarge the role of wireless innovation at academia, Small and Medium-sized Enterprises (SME)'s, industries and start-ups while taking into account decentralized mandate-driven intelligence in E2E communications

A unified radio control architecture for prototyping adaptive wireless protocols

Experimental optimization of wireless protocols and validation of novel solutions is often problematic, due to limited configuration space present in commercial wireless interfaces as well as complexity of monolithic driver implementation on SDR-based experimentation platforms. To overcome these limitations a novel software architecture is proposed, called WiSHFUL, devised to allow: i) maximal exploitation of radio functionalities available in current radio chips, and ii) clean separation between the logic for optimizing the radio protocols (i.e. radio control) and the definition of these protocols