In the application of large-scale ancient site protection, it is necessary to continuously monitor the ambient light, temperature, humidity and so on. However, it is impractical to frequently replace the nodes’ batte...In the application of large-scale ancient site protection, it is necessary to continuously monitor the ambient light, temperature, humidity and so on. However, it is impractical to frequently replace the nodes’ battery in the protected areas. So, the key methods to prolong the network lifetime are to aggregate the collected data and reduce the number of transferring messages. In this paper a Lightweight Data Aggregation Protocol (LDAP) based on the characteristics of the environmental changes in ancient sites is proposed. It has been implemented in the Lab with a dozen of MICAz motes and deployed in the real ancient sites. The result shows that LDAP is effective in reducing the number of transferring packets and satisfies the real application requirements.展开更多
The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition...The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction （XRD） investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy （SEM） analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface, Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency （SRF） cavities.展开更多
This work deals with the deposition of lead （Pb） thin films by the UV pulsed laser ablation technique, for their further use as photocathode devices in superconducting radio frequency guns. Scanning electron microsc...This work deals with the deposition of lead （Pb） thin films by the UV pulsed laser ablation technique, for their further use as photocathode devices in superconducting radio frequency guns. Scanning electron microscopy and atomic force microscopy analyses were performed to study the morphological features of Pb thin films deposited on Si （100） and Nb substrates. The films showed a granular structure with a nearly fully covered surface only for that one deposited on Nb substrate. X-ray diffraction measurements indicate the growth of polycrystalline Pb thin films with a preferential orientation along （111） planes. Results of the photoemission performance of Pb thin film deposited on Nb substrate showed a very encouraging average value of quantum efficiency of 6 x 10-5 through a single-photon absorption process, promoting further studies in the realisation of Pb photocathodes by this technique.展开更多
文摘In the application of large-scale ancient site protection, it is necessary to continuously monitor the ambient light, temperature, humidity and so on. However, it is impractical to frequently replace the nodes’ battery in the protected areas. So, the key methods to prolong the network lifetime are to aggregate the collected data and reduce the number of transferring messages. In this paper a Lightweight Data Aggregation Protocol (LDAP) based on the characteristics of the environmental changes in ancient sites is proposed. It has been implemented in the Lab with a dozen of MICAz motes and deployed in the real ancient sites. The result shows that LDAP is effective in reducing the number of transferring packets and satisfies the real application requirements.
基金supported partially by the Italian Ministry of Research in the framework of FIRB-Fondo per gli Investimenti della Ricerca di Base(Project no.RBFR12NK5K)the Italian National Institute of Nuclear Physics(INFN)
文摘The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction （XRD） investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy （SEM） analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface, Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency （SRF） cavities.
基金supported by the Italian National Institute of Nuclear Physics(INFN)
文摘This work deals with the deposition of lead （Pb） thin films by the UV pulsed laser ablation technique, for their further use as photocathode devices in superconducting radio frequency guns. Scanning electron microscopy and atomic force microscopy analyses were performed to study the morphological features of Pb thin films deposited on Si （100） and Nb substrates. The films showed a granular structure with a nearly fully covered surface only for that one deposited on Nb substrate. X-ray diffraction measurements indicate the growth of polycrystalline Pb thin films with a preferential orientation along （111） planes. Results of the photoemission performance of Pb thin film deposited on Nb substrate showed a very encouraging average value of quantum efficiency of 6 x 10-5 through a single-photon absorption process, promoting further studies in the realisation of Pb photocathodes by this technique.
