Higher Institute on Territorial Systems for Innovation
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New Techniques to Reduce the Execution Time of Functional Test Programs
No full textThe compaction of test programs for processor-based systems is of utmost practical importance: Software-Based Self-Test (SBST) is nowadays increasingly adopted, especially for in-field test of safety-critical applications, and both the size and the execution time of the test are critical parameters. However, while compacting the size of binary test sequences has been thoroughly studied over the years, the reduction of the execution time of test programs is still a rather unexplored area of research. This paper describes a family of algorithms able to automatically enhance an existing test program, reducing the time required to run it and, as a side effect, its size. The proposed solutions are based on instruction removal and restoration, which is shown to be computationally more efficient than instruction removal alone. Experimental results demonstrate the compaction capabilities, and allow analyzing computational costs and effectiveness of the different algorithms
A Key Distribution Scheme for Mobile Wireless Sensor Networks: Q-s-Composite
No full textThe majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the establishment of symmetric keys. A promising key distribution technique is the random predistribution of secret keys. Despite its effectiveness, this approach presents considerable memory overheads, in contrast with the limited resources of wireless sensor networks. In this paper, an in-depth analytical study is conducted on the state-of-the-art key distribution schemes based on random predistribution. A new protocol, called q-s-composite, is proposed in order to exploit the best features of random predistribution and to improve it with lower requirements. The main novelties of q-s-composite are represented by the organization of the secret material that allows a storing reduction, by the proposed technique for pairwise key generation, and by the limited number of predistributed keys used in the generation of a pairwise key. A comparative analysis demonstrates that the proposed approach provides a higher level of security than the state-of-the-art schemes
Design of procedures for rare, new or complex processes: Part 2 - Comparative risk assessment and CEA of the case study
No full textThe paper provides the comparative risk assessment for the case in related paper Design of Procedures for Rare, New or Complex Processes: Part 1 - An Iterative Risk-Based Approach and case study (this issue), where the optimization of the pressure testing procedure for an LPG storage sphere is discussed. Both the ‘Original' and the ‘Optimized' procedure alternatives were the subject of a double comparative risk assessment using two different methods, namely, Bayesian Belief Networks using the HUGIN programme and Integrated Dynamic Decision Analysis (IDDA) using the SPACCO programme. Results suggest that the outputs from both methods/programmes were essentially the same, while the differences are mainly related to the results visualization and their subsequent use. In addition, the adoption of the methods has shown a reduction of the overall failure probabilities considering the ‘Original' and ‘Optimized' procedural alternatives respectively. The results of the comparative cost effectiveness analysis between both alternatives suggest that the initial investment on developing and optimizing the procedure is easily compensated by direct savings in implementation costs, as well as by the further savings in delay risks, occupational safety risks and process safety risks. Pertaining uncertainties in the analysis are also discussed. The results were found valuable for the site management on the "how and why" of developing a rare and potentially hazardous test procedure
How harsh work environments affect the occupational accident phenomenology? Risk assessment and decision making optimisation
No full textThis paper describes a procedure to evaluate the risk of occupational accidents combining SKM (SOM & K-Means) and FAP (Fuzzy Logic approach) to explicitly take into account the impact that harsh productive environments can have on the occupational accident dynamics. The procedure proposed consists of an advanced approach based on two evaluation steps: (1) the investigation of occupational accidents dynamics in a productive sector through the SKM approach, based on neural networks; (2) the occupational accidents risk assessment for a specific plant through the Fuzzy Logic approach, exploiting the knowledge inherent in the accident analysis of an industrial sector to the benefit of the risk assessment in a specific work environment. The application of SKM and FAP approach respectively to the metallurgical sector and to an Italian industrial plant allowed the validation of the proposed procedures.Taking into account the accidents occurred in the Piedmont metallurgical sector from 2006 to 2013, the risk assessment for an Italian steel-manufacturing company was carried on, highlighting how a critical work environment can affect the accident dynamics, and how to correctly take into account their impact during the risk assessment could bring to an effective operational safety improvement
Framework for Enhanced Stormwater Management by Optimization of Sewer Pumping Stations
No full text: Control and reduction of pollution from stormwater overflow is a major concern to be addressed by municipalities in order to improve the quality of the receiving water bodies and the environment in general. In the European context, these actions are driven by the Water Directive 2000/60/CE. In this regard, assessment studies of the potential load from sewer networks recognize the need for adaptation and upgrade of existing networks with waterworks and management measures. In many cases this is done by building first-flush detention tanks that, however, present consistent practical and economical burdens. In this work, simple rules to manage existing pumping stations in combined sewer systems are proposed as a way to apply management rules that mitigate pollution load. Such rules can be easily implemented in real cases with minimal cost of activation and no need of additional infrastructures. The procedure is based on the previous knowledge of the precipitation forcing and of a quantity/quality model of the sewer network. The steps adopted are (1) use of a (long-term, high-resolution) sequence of rainfall events to compute a wide spectrum of flow conditions (hydrographs and pollutographs) to the pumping stations; (2) definitions of a pumping rule to apply to the whole sequence of events to filter the incoming flow toward the wastewater treatment plant, so to compute outflows; and (3) efficiency assessment of the pumping rule by cumulative frequency analysis of water volume, pollutant mass, and pollutant mean concentration. Rule optimization can be performed by iterating points (2) and (3). An example is proposed to show how two simple parameters (a discharge threshold on the inflow and a maximum pumping time) can control the management of water and pollutant fluxes. Numerical results show that a proper optimization allows one to reduce the pumped volumes (thus reducing energy requirements and increasing the treatment plant efficiency) without significant changes to the overall pollutant mass outflow. The new pumping rules can be implemented on real stations with minimal and economically sustainable intervention
The Record and Replay Approach for GNSS Receiver Performance Assessment in Road Environment
No full textNowadays the concept of smart transport, that exploits Intelligent Transport Systems (ITS) technology, plays a fundamental role in our society. The Global Navigation Satellite Systems (GNSS) have significant potential in the development of ITS where the estimation of the vehicle's position represents a key role. However, in strongly constrained environments, such as city centers, the definition of positioning performances is a challenge due to the variability of the different urban scenarios, the modeling of the dynamics as well as the architecture of the positioning platform, which might embed other sensors and aiding means to the GNSS unit. Moreover, the performance metrics of interest are not just position and speed but metrics related to the integrity/reliability concept, properly defined for the road environment. These performance metrics are becoming of paramount interest, as safety-critical application emerging, and have to be assessed. This framework asks for a deep understanding by the ITS sector of the achievable performance by GNSS systems in the different scenarios for automotive. In fact, positioning is taken as a fully reliable and accurate information, based on which more and more automated driving operations are performed. For this reason, the need of standardized performance metrics for GNSS-Based Positioning Terminal (GBPT) and the associated performance assessment procedures and scenarios assume considerable importance. The main focus of the paper is to introduce a performance evaluation procedure based on a record and replay approach able to represent meaningful and realistic scenarios. This approach requires proper data collections that allow the replay phase and data postprocessing to test the GBPT performance. The paper presents also some results obtained on a set of field tests related to different scenarios, selected as representative of reference scenarios for the Key Performance Indicators (KPIs) assessment
Applying the concept of difficulty of tunnelling to Brazilian cases
No full textThis study applies the concept of the difficulty of tunnelling by drilling an blasting (D&B) to selected cases from the Brazilian tunnelling industry. The difficulty of tunnelling has been defined in previous work as the difference of specific drilling (SD) from industrial average trend: easier when SD is lower than average, more difficult when SD is higher than average. Results show how tunnels in Brazil tend to be unrealistically more difficult to excavate when compared to similar excavations in similar geologies elsewhere in the world. It is thoroughly discussed the reason for such anomaly (up to +90% SD compared to industrial average). One reason could be the lack of options amongst explosive products on the brazilian market. Only ANFO and explosive emulsions are available in Brazil. Lacking high VOD (Velocity of Detonation) products might result in reducing the maximum allowable burden amongst production holes, therefore increasing SD. Another reason could be found in the tunnel designers' tendency of choosing D&B as excavation method for weak rock masses that would benefit from mechanical excavation. The reason to this tendency can be partly found in the lack of availability of mechanical excavation machines in the brazilian market. Blasting in weak rock masses requires more careful smooth blasting, hence a closer spacing amongst contour holes to avoid costly overbreak: this increases SD. A third reason could be found in the lack of skill amongst the local workforce. When dealing with unskilled workers the blast designers naturally tend to avoid highly optimized blasts that require very skilled workforce to be realized on field. The designer in this case tends to leave the blast design simpler but more robust, at the cost of higher specific drilling and specific charge. The conclusions suggest that this unrealistic difficulty when compared to world average could be a simptom of the so-called "Brazilian cost" within the tunnelling industry
Innovazioni nello scavo meccanizzato in roccia
No full textNel corso degli anni l'evoluzione ed il perfezionamento dello scavo meccanizzato, sia per scopi estrattivi sia civili, sono stati oggetto di crescente attenzione. In ambienti di tipo hard rock, la tradizionale tecnica di scavo mediante Drill & Blast, ancora ampiamente impiegata per gallerie di breve o media lunghezza, è stata progressivamente sostituita, per gallerie di lunghezza notevole (mediamente superiore a 1 km), dallo scavo meccanico a piena sezione mediante Tunnel Boring Machine (TBM), a fronte di notevoli vantaggi soprattutto in termini di tempi e sicurezza in fase di realizzazione. Il successo di tale tecnica è fortemente influenzato dalle caratteristiche dell'opera da realizzare e dalle proprietà del materiale oggetto dello scavo. Nei decenni passati sono stati raggiunti numerosi progressi circa l'ottimizzazione dello scavo con TBM in condizioni ideali, storicamente associate ad ammassi rocciosi con caratteristiche omogenee e ricorrenti lungo il tracciato della galleria. La sfida attuale riguarda la messa a punto di macchine sempre più "flessibili", in grado di essere impiegate efficacemente anche in ammassi rocciosi eterogenei. Il presente studio ha lo scopo di illustrare le recenti innovazioni nel campo delle hard rock TBM. Sono analizzate le diverse tipologie di macchine impiegabili in differenti configurazioni e condizioni di scavo, evidenziando gli aspetti critici per la progettazione e realizzazione di macchine innovative, con particolare riferimento agli scavi in aree montane, in genere caratterizzati da notevoli lunghezze del tracciato e da elevate coperture. Sono infine riportati esempi di recente impiego di TBM per la realizzazione di gallerie in condizioni geotecniche difficili
Preparation and Characterization of Magnetic and Porous Metal-Ceramic Nanocomposites from a Zeolite Precursor and Their Application for DNA Separation
No full textIn this work, metal-ceramic nanocomposites were obtained through short (up to 2 h) thermal treatments at relatively moderate temperatures (750-800 C) under a reducing atmosphere, using Fe-exchanged zeolite A as the precursor. The as-obtained materials were characterized by X-ray powder diffraction analysis, N2 adsorption at −196 C, and highresolution transmission electron microscopy. The results of these analyses showed that the nanocomposites consisted of a dispersion of metallic Fe nanoparticles within a porous ceramic matrix, mainly based on amorphous silica and alumina. These nanocomposites were magnetically characterized, and their magnetic response was studied. Finally, the obtained metal-ceramic nanocomposite materials were used in the separation of Escherichia coli DNA from a crude cell lysate. The results of the DNA separation experiments showed that the obtained materials could perform this type of separation
Effect of pulsed laser irradiation on the SiC surface
No full textThe effect of a pulsed laser irradiation (Nd:YVO4, 1064 nm) in air on the Surface morphology and chemical composition of silicon carbide and on the adhesion with an epoxy adhesive was investigated. Scanning and transmission electron microscopies, atomic force microscopy, and X-ray photoelectron spectroscopy revealed that the laser treatment reduced the contamination level of the Surface and induced the formation of a silica-based nanostructured colum nar layer on the SiC surface. The mechanism for the formation of five different microstructural regions is described in this paper. In addition, the formation of a 5-10-nm-thick graphite layer between the oxide layer and SiC was observed. The joining test with Hysol EA9321 showed that the nanostructured columnar silica layer was completely infiltrated by the adhesive, thus leading to a significant increase in the joined specific area and a mecha nical interlocking at the adhesive/substrate interface. Nevertheless, the apparent shear strength of the joined SiC samples slightly decreased after the laser processing of the surfaces from about 42 MPa for lapped SiC to about 35 MPa for laser-nanostructured SiC. The formation of the graphite layer was found to be responsible of the poor adhesion properties of the SiC surfaces modified by the laser radiation