1,721,335 research outputs found
Variazioni sui rilievi tarquiniesi di età arcaica
No full textSi presentano alcuni nuovi esemplari della classe, discutendo criticamente gli studi che su questi monumeti sono stati pubblicati negli ultimi decenn
A study of the Civic Tower in Ravenna as an example of medieval towers' preservation problems
No full textStructuralstabilityis a major item when considering very high masonry buildings made of stones, bricks, etc., that can start sudden structural failures and collapses, often without any obvious signs of warning. A famous example is the collapse of the belfry of the Basilica of San Marco in Venice --the implementation of it began in the ninth century-- which took place in July 1902 a few days after the appearanceof a fissure. This paper discusses the scientific investigation performed on the Torre Civica (Civic Tower) in Ravenna (North-East Italy), in order to characterize its constituent materials, namely bricks and mortar. All this information and relevant data merge in a multimedia database which will help to design appropriate conservation and restoration works, mainly concerning the reconstruction of the apical part of the tower, that was foreshortened ten years ago for safety reasons, starting from the original materials catalogued and preserved up to the present day. © 2013, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg
Comparison of wheel–rail contact models in the context of multibody system simulation: Hertzian versus non-Hertzian
Full text linkThe calculation of the wheel–rail contact forces is one of the most difficult yet time-consuming processes in multibody system (MBS) simulations for a vehicle-track interaction system. The classical combination of the Hertzian model with the FASTSIM algorithm is the most widely used model in MBS code for railway application and the ‘exact’ solver CONTACT is seldom used due to its high computational cost. A trade-off solution between accuracy and computational efficiency is the simplified and approximate non-Hertzian approach. This paper attempts to compare the influence on MBS simulation for rail vehicle system dynamics of the varied combinations of the classical contact models (i.e. Hertz model and FASTSIM), well-known simplified non-Hertzian model (Kik–Piotrowski model) recently developed improved simplified non-Hertzian models i.e. Extended Kik–Piotrowski and Kalker Book of Tables for Non-Hertzian contact (KBTNH), and the CONTACT algorithm. The results show that all non-Hertzian approaches deviate from the classical Hertzian solutions in both local contact and global dynamics and the KBTNH model provides better agreement with CONTACT than the FASTSIM algorithm for non-elliptic contact conditions considered in this study. A detailed analysis of the causes and influences of the difference due to varied contact models is presented
An examination of alternative schemes for active and semi-active control of vertical car-body vibration to improve ride comfort
Full text linkThe recent tendency to reduce the weight of car bodies is posing a new challenge to vertical ride quality, since the vibrations related to car-body vertical bending modes affect heavily passengers’ comfort and cannot be fully mitigated by conventional vehicle suspensions. In this work, four mechatronic suspensions, considering active and semi-active technologies in secondary and primary suspensions, are compared to show their relative merits. LQG and H∞ model-based control strategies are established in a consistent way for each suspension scheme to perform a comparative assessment of the four concepts on objective grounds. A two-dimensional 9-DOF vehicle model is firstly built, using a simplified representation of car-body bending modes; this model is also used to design the model-based controllers. The comparison of the four mechatronic suspension schemes based on the 9-DOF model shows that full-active secondary suspension is the most effective solution whilst semi-active primary suspension is also effective in terms of mitigating car-body bending vibration. Then, a three-dimensional flexible multibody system (FMBS) vehicle model integrated with a finite-element car-body is considered to allow a more detailed consideration of the vehicle’s vibrating behaviour. The results of the FMBS model show a good agreement to the results of the 9-DOF model and the relative merits of the four mechatronic suspension schemes as found from the previous analysis are basically confirmed, although the FMBS model is more suited for a quantitative assessment of ride quality
New data from the Fornaci necropolis in Capua. Continuity and innovation in tombs of the Orientalizing period
No full textThe paper aims to shed further light on the Orientalising period in Capua through the analysis of two relevant unpublished funerary contexts (947 and 975 Tombs) stored in the Archaeological Museum of Santa Maria Capua Vetere. These contexts have been recorded and analysed as part of the review of the materials from the excavations of the Fornaci necropolis carried out by W. Johannowsky between the 1950s and 1970s. The contribution analyses the stratigraphic context and the grave goods of the two tombs, allowing us to reconstruct and update the interpretation of the Sector Q of the necropolis as a whole. It offers both an overview of the traditional and innovative aspects of the elements of Orientalising material culture documented in Capua and those of continuity and discontinuity in the Fornaci funerary complex. Furthermore, the article offers the preliminary archaeometric results of the Tomb 947 bucchero vessels
Editorial: Best Practices on Advanced Condition Monitoring of Rail Infrastructure Systems
Full text linkCOVID-19 has just proven that transportation systems are not immunized and are vulnerable. The coronavirus causes severe consequences including step changes in travel behaviors, risk perception and avoidance, transportation operations, network policies, and real capabilities to track, monitor, and contain the virus through social distancing, quarantine, and isolation within the transport networks. These too affect the standard and practice for managing infrastructure systems. We can no longer consider or treat resilience simply for better responses to environmental hazards as a business as usual. Societal, economic, and engineering resilience has become more underlyingly critical than ever. In fact, the virus underpins the necessity to manage temporal and spatial risks through advanced condition monitoring across transportation networks, modalities, and systems. Such needs have been the key theme in this special Research Topic that is emphasized on rail infrastructure systems designed to cope with multi hazards and extreme events
Villa di Bocca delle Menate, Comacchio
No full textL'indagine consiste in:1- Inquadramento dell’area di indagine (Comune di Comacchio, catasto F. 52, partt. 122, 184); 2- Messa a sistema del materiale proveniente dalle indagini già eseguite presso il sito di Bocca delle Menate. 3- Realizzazione di una base cartografica del sito, tramite il reperimento degli strumenti tecnici di base, propedeutica alla realizzazione delle attività che si intendono svolgere, procedendo di pari passo all’acquisizione dei dati bibliografici e di archivio disponibili. 4- Indagini archeologiche con attività didattiche e laboratori 5- Redazione di nuova documentazione 6- Ricostruzione del contesto territoriale: contestualizzare materiali e documentazione nel palinsesto del Padus
Influence of individual wheel profiles on the assessment of running dynamics of a rail vehicle by numerical simulation: a case study
Full text linkIt is well known that wheel wear degrades the dynamic performance of the rail vehicles, especially in regard to the issue customarily known as ‘running stability’ and resulting in the evaluation of the vehicle’s critical speed. Past research addressed this problem mainly from the viewpoint of the influence on the vehicle performance of the wear pattern. The aim of this work is to investigate the influence of individual wheel profiles measured on a rail vehicle on the vehicle’s dynamics in the context of multibody (MB) simulations. The EN14363-based method, bifurcation map and the decreasing speed approach were implemented, and two new criteria were proposed based on the bifurcation map and decreasing speed schemes. Six methods were compared for assessing the vehicle’s critical speed for a case study. The results show that different assumptions made in the MB simulations for the wheel profiles may have a significant effect on the assessment of system dynamics and that some of the methods used for the calculation of the vehicle’s critical speed are more sensitive to the combination of profiles used. Therefore, the consideration of the peculiarity of each wheel profile is desirable for a detailed dynamics assessment of a vehicle in service
Imparare ad insegnare che fatica!
No full textIl gruppo Strumenti e strategie per imparare a insegnare ha sviluppato un metodo sperimentale per la formazione dei bibliotecari educatori durante la Conferenza Stelline 2025. In Italia, infatti, i bibliotecari che assumono ruoli educativi spesso lo fanno senza avere una formazione pedagogica. Devono quindi “imparare a nuotare”. Attraverso attività ludiche e interattive, il gruppo ha promosso un approccio didattico partecipativo. I risultati sono stati condivisi in una sessione di laboratorio pratico e in un Wikibook collaborativo
Fault-tolerant design and evaluation for a railway bogie active steering system
Full text linkActive suspension system can drastically improve dynamic behaviours of the railway vehicle but will also introduce safety-critical issues. The fault-tolerant analysis, therefore, is essential for the design and implementation of active suspension. However, this issue did not receive enough attention so far and only few papers can be found related to the fault tolerance of active steering for the railway vehicle. In this work, an approach based on Risk Priority Number is established to present quantitative assessment for fault tolerance of actuation system. Then this method is adopted to compare nine different active steering schemes resulting in a novel, comprehensive approach that enables a quantitative evaluation of different designs of the actuation system and of different principles to improve the fault tolerance. The impacts of typical failure modes are investigated through multi-body simulation and quantified by severity factor. Finally, the fault tolerance of different actuation schemes is evaluated by RPN values
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