The vibrations induced by surface irregularities in road pavements – a Matlab® approach

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Correction to: The vibrations induced by surface irregularities in road pavements – a Matlab® approach

After publication of this article [1], it is noticed the article contained an error with eq. 12, the c s should be squared. The correct eq. 12 is provided below

Biofunctional Silk Kirigami With Engineered Properties.

The fabrication of multifunctional materials that interface with living environments is a problem of great interest. A variety of structural design concepts have been integrated with functional materials to form biodevices and surfaces for health monitoring. In particular, approaches based on kirigami-inspired cuts can engineer flexibility in materials through the creation of patterned defects. Here, the fabrication of a biodegradable and biofunctional "silk kirigami" material is demonstrated. Mechanically flexible, free-standing, optically transparent, large-area biomaterial sheets with precisely defined and computationally designed microscale cuts can be formed using a single-step photolithographic process. Using modeling techniques, it is shown how cuts can generate remarkable "self-shielding" leading to engineered elastic behavior and deformation. As composites with conducting polymers, flexible, intrinsically electroactive sheets can be formed. Importantly, the silk kirigami sheets are biocompatible, can serve as substrates for cell culture, and be proteolytically resorbed. The unique properties of silk kirigami suggest a host of applications as transient, "green", functional biointerfaces, and flexible bioelectronics

Characterisation of road bumps using smartphones

Introduction: Speed bumps are used as the main means of controlling vehicle speeds all over the world. It is not too infrequent, especially in the emerging economies, to have unmarked bumps that can be perilous for the passengers. Fortuitously, the roadways and mobile phone networks have grown simultaneously in emerging economies. This paper demonstrates the capability of smartphones placed inside the vehicles in characterisation of road bumps. The smart mobile phones have accelerometers and position sensors that can be useful for autonomous monitoring roads. This can empower the user community in monitoring of roads. However, the capability of the smartphone in discerning different types of speed bumps while travelling in heterogeneous vehicle types needs to be examined. Methods: A range of road vehicles is mathematically modelled as mass, spring, and damper systems. The mathematical model of the vehicle is excited with parameters analogous to some common speed bumps and its acceleration response is calculated. The accelerometer of a smartphone is validated by comparing it with high precision accelerometers. The acceleration response of the phone while passing over the corresponding road bumps, which was used in the model earlier, is recorded using an Android based application. The experiment is repeated for different classes of vehicles. Filters have been used to reduce noise in the signals. A time averaging technique has been employed to compress the collected data.Results and conclusions: The acceleration signals have been digitally processed to capture road bumps. The importance of using a mathematical model to understand the acceleration response of a vehicle has been established. Also, the use of pass filters to extract the signal of concern from the noisy data has been exhibited. The ability of the technique to discern different types of speed bumps while travelling in a variety of vehicle types has been demonstrated. This investigation demonstrates the potential to automatically monitor the condition of roadways obviating costly manual inspections. As smartphones are ubiquitous, the methodology has the potential to empower the user community in the maintenance of infrastructure

Il calcolo e il disegno automatico delle linee di flesso e continuità

Il presente articolo si inserisce nell’ambito delle ricerche condotte presso la Cattedra di Costruzioni di Strade, Ferrovie e Aeroporti della Facoltà di Ingegneria dell’Università di Ancona finalizzate alla realizzazione di programmi completi per la progettazione e la realizzazione grafica di percorsi stradali mediante l’elaboratore elettronico e la configurazione hardware ad esso associata. L’Autore propone un interessante programma di calcolo per determinare gli elementi progettuali delle linee di raccordo di flesso e di continuità

La scelta ottimale del raccordo policentrico in sostituzione della clotoide

Nelle costruzioni stradali e ferroviarie hanno notevole importanza i raccordi planimetrici, la cui funzione risponde a necessità di ordine pratico, dinamico, cinematico, estetico. Lo studio condotto dall’Autore illustra la possibilità di sostituire, nelle ordinarie applicazioni, la clotoide con una curva policentrica che consenta scarti in valore assoluto tra le coordinate dei punti finali delle curve a confronto inferiori all’l % e che riproponga la continuità della clotoide con un modello discontinuo (serie di archi)

Mix optimisation for cement mixtures made of R.A.P. and C&D

The increasing traffic flows on road infrastructures significantly quicken the degradation time of the pavements efficiency characteristics. As a consequence, the managing bodies are obliged to consider more frequent maintenance interventions, so as to guarantee high levels of both safety and comfort for users. Therefore, considering the wide extension of the Italian road infrastructures, one could easily imagine the large amount of milled materials (R.A.P.) coming from maintenance. Along with R.A.P., there is another waste material which is to be considered also: it is the so-called C&D, which basically belongs from the demolition of civil engineering structures. Both materials involve serious environmental considerations, the need of new landfills being compulsory. The re-use of these substances is the solution to this concern, and this reflects the current trend of finding alternative technologies for the use of waste materials. Actually, waste materials recycling, including R.A.P. and C&D is one of the most interesting technical innovations, both the economical and environmental aspects being considered at the same time. For this reason, this paper proposes the outcomes of an optimisation study on R.A.P. and R.A.P.+ C&D mixes for the manufacture of cement admixtures for road infrastructures, based on mechanical and economical evaluations

Applicazione del metodo dei successivi residuali nella determinazione del modulo complesso di miscele di conglomerato bituminoso e confronto con i metodi empirici di letteratura

La determinazione del modulo complesso del conglomerato bituminoso è di fondamentale importanza ai fini del calcolo razionale delle pavimentazioni flessibili e semirigide, soprattutto in fase di rafforzamento e manutenzione delle sovrastrutture stradali esistenti. La difficoltà oggettiva di condurre determinazioni di modulo complesso giustifica ancora oggi l’adozione di metodi di valutazione empirici, che si rifanno alle proprietà volumetriche delle miscele e alle caratteristiche del legante bituminoso, pur nella consapevolezza che tali procedure possono produrre margini di errore assai ampi. Gli Autori, attraverso una campagna di prove effettuata su tre tipi di conglomerati bituminosi per strato di usura a differente composizione di inerte, pervengono alla determinazione del modulo complesso dei materiali analizzati con prove di creep statico ed applicazione del metodo dei successivi residuali, operando nel contempo specifiche valutazioni basate sui metodi empirici di letteratura. Dal confronto dei risultati ottenuti emerge con chiarezza la scarsa attendibilità dei metodi empirici a fronte dell’accertata validità del metodo dei successivi residuali

Thermal analysis and fatigue verification of the LWR for an effective maintenance of the railway transport network

The increase in trains velocity and the improvement of comfort on railways belong to both the improvement of vehicles performances and to the use of the long welded rail (LWR). The analysis of the thermal set-up of the track is fundamental for the sake of the railway transport network performances: it basically deals with the changes in spans and strains occurring daily after temperature ranges. This phenomenon is described by the free dilatation law for tracks without bonds and by the stopped dilatation law for completely constrained tracks. The thermal analysis of the LWR shows a cyclic soliciting phenomenon belonging to both the daily temperature ranges and to the effects of moving vehicles: from this point of view a repetition of strains which involves an appropriate fatigue verification of the railways can be identified. For this reason the authors propose a procedure based on the synergic application of the Woehler construction theory for the fatigue curves and of the Miner law of linear accumulation. Once the Woehler curves are found as function of the different stress state due to the thermal variations and to the moving vehicles passing, the comprehensive damage for both kinds of strains can be quantified by means of the Miner theory. For this purpose the authors propose the implementation of a calculation software which can automate the thermal lay-out analysis phase, performing the Woehler curve, the internal stresses computation and the damage analysis following Miner’s law. In conclusion, this research is an useful tool for an effective maintenance of the LWR, as it allows the monitoring of the stress state of tracks, especially during the last part of their life cycle, when the temperature range and the moving vehicles passage consequences are more severe