English
Articoli, Atti convegni, PDF dal mondo dell'automazione industriale, strumentazione industriale e 4.0
Impact of jet fan ventilation systems on sprinkler activation
(in lingua inglese)
In order to quantify the potential delay to sprinkler activation caused by jet fans continuing to operate sixteen CFD analyses are undertaken to determine whether (i) it is significant and (ii) it detrimentally impacts upon the means of escape in the car park undertaken in a separate companion analysis (not presented here for brevity). The results of the analyses indicate delays of 630s to sprinkler activation where the sprinkler and jet fans layout was coordinated so the sprinklers are inplane with the jet fan nozzle. This does not significantly increase the hazard to occupants with the safety margin in the egress design being many times greater than this. Furthermore, the jet fans do not adversely affect the visibility in means of escape.
A modified critical velocity for road tunnel fire smoke management with dedicated smoke extraction configuration
(in lingua inglese)
Based on a typical example 2 lane road tunnel with a fixed smoke extraction rate of 282 m3 /s, Computational Fluid Dynamics (CFD) analysis has been performed on selected cases to investigate the modified critical velocity considering specific smoke extraction configurations and other parameters. These parameters examined included the extraction damper locations, total number of operating dampers, tunnel gradient, fire location and the traffic blockages in the tunnel region that is upstream of the fire.
Sensitivity study of the morphometric fitting on the pressure field inside ankle joints
(in lingua inglese)
In this paper the 2D metrological characterization in the sagittal plane of the articular surfaces in the lubricated contact of the human ankle joint has been carried out. From a proper medical image segmentation, tibial and talar bone surfaces are modelled on constant curvature (circles) under different criteria: least squares (LS) and minimum zone (MZ).
Cracking of underground welded steel pipes caused by HAZ sensitization
(in lingua inglese)
The failure of a galvanized welded 27 mm 3 mm steel pipe was investigated. The findings ofthe present evaluation have led to the following conclusions: cracking initiated prior to galvanizing and has led to brittle fracture adjacent to the weld area in the HAZ. No static tensile overload during service is considered as primary failure mechanism. Strong microstructural heterogeneity is evident in HAZ, while the failure is most probably attributed to sensitization and intergranular embrittlement. The sensitization could be probably attributed to the segregation of harmful impurities or hot shortness constituents (such as Cu, CuS) to the grain boundaries, while the contribution of hydrogen and Zn-liquid metal assisted cracking to the intergranular failure cannot be discounted.
EFFICIENZA ENERGETICA: LO STRUMENTO DELL’ENERGY PERFORMANCE CONTRACTING ED I RUOLI DELL’INGEGNERE
Obiettivo di tale articolo è quello di illustrare i principali strumenti di misura e verifica dell’Efficienza Energetica, che costituiscono la base per la predisposizione degli allegati tecnici agli EPC, al fine di fornire una valutazione oggettiva delle performance (baseline, algoritmo di calcolo, sistemi di monitoraggio strumentale, fattori di normalizzazione e correzione dei consumi energetici) ed una allocazione e normalizzazione dei rischi per l’intera vita utile del Progetto.
An investigation of cracking causes in an outlet RTJ flange in ISOMAX unit
(in lingua inglese)
In this case, another source of chloride is anti-seize grease that it is used for fastening of flanges. So a sample of that grease was evaluated according to ASTM D808 method to determine the amount of its chloride. The result showed that there was 0.1 wt.% chloride in the used grease. The entrapped chloride at the groove of RTJ flange because of its geometry get concentrated by evaporation at high operating temperature, and the subsequent cracking of the RTJ groove occurs at areas with applied or residual stress. Above evidences indicated that the flange failed by Cl SCC due to using unqualified anti-seize grease in maintenance procedure.
Failure analysis of a bridge crane shaf
(in lingua inglese)
This study analyzed the failure of a bridge crane shaft, the analysis allowed concluding as follows. Stereography examination revealed the presence of beach and ratchet marks on the fracture surface and the fractography examination shows striations; all of this evidence indicates the shaft was fractured by fatigue. The shaft material did not satisfy the chemical composition standard; on the other hand, the microstructure was not adequate for this application because it has low mechanical properties and large amount of defects near to the fracture zone. Specifically, the study found the length of MnS inclusions above the value of critical inclusion size parameter, which produced a drastic decrease in fatigue life.
Igiene sostenibile in cantina con l’impiego dell’ozono: zero residui
Le nuove soluzioni a ozono, oltre ad abbattere i residui chimici, migliorano i processi produttivi e la sicurezza per gli operatori di cantina, dimostrandosi altamente sostenibili e apprezzate dal mercato.
In particolare, l’ozono è sempre più utilizzato nella sanificazione delle barrique e delle botti perchè è più efficace ed arriva più in profondità delle altre metodiche utilizzate normalmente in cantina, senza rischio di alterazione nelle barriques e riducendo i consumi di risorse pregiate quali acqua ed energia elettrica, generalmente usate per la diffusione e rimozione del disinfettante. Inoltre l’utilizzo di acqua ozononizzata nei CIP e nelle imbottigliatrici è indicato per evitare di ricontaminare con l’acqua (che è potabile, ma non sterile) i serbatoi durante la fase di risciacquo o di portare la contaminazione da un serbatoio all’altro e per eliminare il biofilm nelle condotte.
Failure analysis of a burner ring made of 20Cr32Ni1Nb alloy in gas turbine combustion chamber
(in lingua inglese)
A work duration of 5000 h at the maximum service temperature resulted in the enlargement and elimination of a large quantity of intra-dendritic carbides in the Ex-service parts. Moreover, a significant increase of Nb was detected in the intermetallic MC carbides. The microstructural changes during 5000 h indicated that the service temperature was more than the standard working temperature of this material. Decarburization and precipitate enlargement resulted in the reduction of mechanical properties that led to the deformation of ring at high temperature due to thermal stresses. Furthermore, enlarged Nb rich precipitates were proper sites to generate voids in front of the crack path that joining of the voids resulted in crack propagation.
Failure analysis of cracked brass turrets used in electronic circuits
(in lingua inglese)
Free cutting brass as specified by the ASTM B16 has different microstructures for the different composition of the major alloying elements. This affects the material properties, particularly, hardness. The material has homogenous alpha phase at zinc content less than 35 wt.% and the heterogeneous alpha + beta above 35 wt.%. The presence of b-beta phase makes the material more brittle and causes the material to crack during the plastic deformation/cold working. The cracks formed will propagate through the harder b phase in the microstructure.
Fracture of a veneered-ZrO2 dental prosthesis from an inner thermal crack
(in lingua inglese)
Our fractographic analysis showed that fracture of dental prostheses may initiate from internal thermal flaws, and not exclusively from contact cracks, radial cracks or marginal defects. The fracture origin in the presented case was a thermal flaw that resulted from the layering technique. Fracture was prompted by sliding contact loading and expedited by an internal flaw embedded in a veneering material under considerable thermal residual stresses.
Reduction in diversion due to coil break in CRNO grades of coils
(in lingua inglese)
No significant variation in microstructure was observed between fully processed CRNO samples with and without coil breaks. Higher nitrogen level in excess of 60 ppm led to an increase in susceptibility to coil breaks. To minimize the effect of nitrogen, Ti microalloyed CRNO heats were made and processed. The Ti-microalloyed coils exhibited similar diversion on account of coil breaks as the plain CRNO steels indicating the genesis of the problem lies elsewhere.
Failure analysis of re-bars during bending operations
(in lingua inglese)
From the visual observation of the failed samples chervon markrs were observed through out the locations of the centrally splitted re-bar samples. The factography analysis of the fracture surface shows predominantly cleavage facets at the surface of the failed samples. From visual and fractography analysis results the indication of brittle nature of fracture was obtained. From the microstructure analysis through harden martensitic matrix was observed from core to edge of the rebar sample with few amounts of retain austenitic structure (average 328 HV).
Failure analysis of work rolls of a thin hot strip mill
(in lingua inglese)
The above two cases in this present article imposed that, roll is a critical component for the rolling mill and failure of roll occurred due to improper roll quality. In the first case, improper microstructure (inhomogeneous in nature) led to failure of roll during service. While, the second case the defect of the roll originated from the manufacturing process. It has been cleared from the article that the roll manufacturing plays a significant role in performance of roll.
Statistical tools applied for the reduction of the defect rate of coffee degassing valves
(in lingua inglese)
A problem of high defect rate in the production of coffee valves was tackled, using first the basic tools of quality design and performing a dimensional analysis of the involved parts. Subsequently, a statistical analysis of the data, led to the determination of their distributions. Afterwards, an easy approach was proposed, to indicate the most suitable strategy to improve production quality, predicting the achievable defect rate. A specific requirement addressed to the suppliers led to more conformal dimensions of the covers, with the final result of a significant decrease of the defect rate to acceptable values.
Failure analysis of edge discoloration of galvanized fuel tank
(in lingua inglese)
Due to lower bath aluminium content(0.13% as compared to 0.185 regular during galvanizing process), lower speed and thicker section combination resulted in formation of partial Galvannealed surface in the coil owing to the internal heat content of the coil. It is recommended that coils for automotive galvanizing grade are not to be scheduled during unstable zinc condition (like run down).
Robotica in medicina
• Migliorano la qualità della vita delle persone diversamente abili .
•Utilizzati nelle sale operatorie o per la diagnosi e per la riabilitazione e problemi di neuromotoria;
Fracture analysis of a low pressure steam turbine blade
(in lingua inglese)
FEA predicts the local mean stress sm higher than 500 MPa at the edge of the turbine blade root in un-notched condition caused by the rotor speed. In notched condition, FEA showed that the pitting hole increased the local stress above yield. The spatial stress increase due to the pitting hole was larger than microstructure features, such as the prior austenite grain size. The superposition of Dsb causes the fatigue crack to grow from micro-structurally small to large.
Characterizing material properties of cement-stabilized rammed earth to construct sustainable insulated walls
(in lingua inglese)
This article presents the findings of a study initiated in Canada to determine the mechanical properties of rammed earth including compressive strength, bond strength, and flexural strength. The compressive strength test results indicate that strengths in excess of 15 MPa can be easily achieved at 28 days. Cored specimens indicated a much lower standard variability. Cast specimens on the other hand can be used to measure the compressive strength, but the high variability in test results needs to be accounted for. This study also presents some interesting findings on the pull out strength of rebar embedded vertically or horizontally in RE.
Monitoring in situ performance of pervious concrete in British Columbia - A pilot study
(in lingua inglese)
A case study is presented that describes a 1000 ft2 pilot placement of pervious concrete in a parking lot that is serving as a non-conventional paving material in an urban environment. A network of embedded perforated pipes is being used to monitor the capacity of the pavement to absorb and detain the rain runoff and its effect on improving quality of permeated runoff. The innovative construction procedure is comparable to conventional construction and a desired finish/texture for a parking lot can be achieved. The lack of an existing technique to manufacture molded specimens for compression testing may have partly contributed to the low measured compressive strength
Con AppFire la stufa a pellet diventa "smart"
AppFire e WiFire sono una novità di HottoH, la business unit di Astrel Group specializzata nella progettazione e commercializzazione di centraline elettroniche per stufe e caldaie alimentate a biomassa. AppFire e WiFire sono compatibili con tutte le centraline elettroniche per stufe a pellet e caldaie a biomassa di nuova generazione della linea HottoH. HottoH investe con continuità nell’innovazione di prodotto, con un’attenzione particolare verso la semplicità d’uso, la connettività ed il risparmio energetico. In sinergia con le altre business unit Astrel Group, HottoH pone particolare attenzione nello sviluppo di soluzioni adatte ai nuovi trend del mercato, con un focus particolare sui mercati e le applicazioni per Internet of Things e Smart Home.
Tecnica e design: il nuovo sistema di regolazione per il miglioramento del comfort
Per l’installazione del sistema R-Tronic non sono necessarie né opere murarie, né interventi di un elettricista e il radiotermostato, che si fissa molto semplicemente alla parete, può dialogare con uno, due o tre servomotori a batteria facilmente abbinabili alle valvole dei corpi scaldanti. L’abbinamento alle valvole di tipo preregolabile della serie “AV9”, oltre a garantire il corretto apporto di fluido vettore, offre interessanti vantaggi come la possibilità di disporre di 17 valori di preregolazione, di bilanciare la rete a servizio dei corpi scaldanti, di prevenire transitori anomali, di rispettare le portate di progetto e di ottenere sia una migliore efficienza, sia un maggiore risparmio energetico.
Corrosion assessment of reinforced concrete elements of Torre Velasca in Milan
A significant effect of local exposure conditions, i.e. height and orientation, on carbonation depth did not emerge. The presence of coating with high thickness, cementitious nature and low porosity both prevented concrete carbonation and delayed the ingress of water into concrete. Hence, most rebars embedded in concrete were either still passive or free from actively-propagating corrosion. A repair strategy based only on the repair of the few local cracked areas is proposed, whilst the sound concrete, even if carbonated, should not be removed.
Dimensionamento di micro turboespansori assiali per recupero energetico
Nel presente lavoro è stata presentata una metodologia per il progetto di micro turboespansori assiali da utilizzare in sostituzione di valvole di laminazione per recuperare parte dell’energia che altrimenti verrebbe persa. Questa metodologia consiste essenzialmente in tre passi: utilizzo di una semplice formulazione unidimensionale per la definizione dei principali parametri geometrici e operativi della macchina; calcolo bidimensionale ottimizzato per la definizione della forma delle palette statoriche e rotoriche; simulazione CFD tridimensionale dell’intera macchina per valutare i coefficienti di perdita necessari nel calcolo unidimensionale.
State estimation with quantized innovations in wireless sensor networks
(in lingua inglese)
This paper explores an innovative Gaussian mixture state estimation algorithm. By studying the assumptions of prior and posterior pdfs which are based on the quantized innovations, a Gaussian mixture estimator has been derived in the paper. Besides, a recursive posterior CRLB for state estimation using quantized innovations in WSNs is developed. The theoretical lower bound is estimated approximately by adopting a Monte-Carlo method. Performance analysis and simulation experiments show that the Gaussian mixture estimator is better than those quantization KF algorithms.
A novel particle filter approach for indoor positioning by fusing WiFi and inertial sensors
(in lingua inglese)
In this paper, a novel fusion algorithm for indoor positioning is proposed. The filter method is exploited to integrate inertial sensor, WiFi sensor and the map information. Also, local RBPF and global RBPF are introduced into the fusion algorithm. By dividing the indoor environments into several local areas, without computing the global areas, the computation could reduce greatly. Preliminary trial results show that the proposed RBPF algorithm could achieve the positioning accuracy of 1.2 m and it meets the need of indoor positioning. Also, the calculation burden is nearly half of the conventional PF methods.
DOA and polarization estimation via signal reconstruction with linear polarization-sensitive arrays
(in lingua inglese)
The signal components embedded in differently polarized array measurements are reconstructed and combined in this paper, so as to estimate the 1-D and 2-D directions of signals with different degrees of polarization and the polarization parameters of completely polarized signals. The proposed method is free of multi-dimensional searching and variable-pairing. It adapts to polarization sensitive linear arrays with different polarization directions if only the array sensors have identical structures. The proposed method also performs well in separating coherent signals and signals with different degrees of polarization.
Business Intelligence per le PMI: stato dell'arte e comparazione software
Lo scopo di questo lavoro è quello di ripercorrere il processo che un'azienda deve fare per progettare e implementare un sistema informativo che possa permetterle di utilizzare l'enorme quantità di dati che si trova a gestire per poterli trasformare in informazioni utili al processo decisionale. L'importanza di un sistema informativo ben sviluppato, già discusso nel primo capitolo, deve essere ben nota alle aziende, in quanto permette lorodi aumentare le conoscenze e le esperienze che possono fare la differenza all'interno di un mercato molto affollato e agguerrito. La prima fase di questo processo consiste nella definizione delle esigenze interne e dei vincoli aziendali che dipendono dalla singola realtà e, di conseguenza, di difficile definizione per le PMI in generale.
Analisi comparativa dei sistemi di sicurezza e controllo gru idrauliche su autocarro
La tecnologia legata al software di gestione, HPLS sul modello EH D e SHPLS sul modello SH D, garantisce la durata dei componenti sollecitati maggiormente utilizzando una ovvia riduzione nella velocità che va a compensare il maggiore stress di carico con un utilizzo addolcito nelle accelerazioni e decelerazioni grazie anche al radiocomando che permette non solo confort ma sensibilità maggiore nei movimenti della gru. Nella versione PK 16002 HP D il controllo della velocità operativa della gru è esclusiva del distributore di base, e sensibilità dell’operatore, pertanto non viene utilizzato un vero e proprio software di gestione e controllo, lavora a pressioni meno elevate rispetto alle altre e con un momento di sollevamento inferiore. Controlli sulle accelerazioni a tutta spinta o decelerazioni improvvise non vengono compensate da alcun sistema di controllo.
Motore ad aria compressa : alternativa al motore elettrico nei sistemi ibridi?
La piattaforma di test, come si vede in Fig 5, consiste in un regolatore, un serbatoio, un sensore della pressione nel cilindro (4075A, KISTLER), un sensore della pressione in ingresso, un sistema di accoppiamento, un dinamometro di corrente passante, il CAE modificato e un sistema di acquisizione dati. L’aria compressa che esce dal serbatoio, scorre attraverso una conduttura dentro il CAE. Il banco di prova è stato disegnato per misurare i parametri e le performance delle operazioni del CAE, comprese la pressione di ingresso, la velocità angolare e la coppia del CAE stesso. Il traduttore della pressione, inserito nelle tubazioni, restituisce il valore di pressione all’interno dei condotti. Il sensore di pressione del cilindro è stato istallato sulla testa del cilindro per misurare la pressone interna del cilindro CAE.
Real-time drogue recognition and 3D locating for UAV autonomous aerial refueling based on monocular machine vision
(in lingua inglese)
The proposed method is able to accomplish drogue recognition and 3D locating simultaneously, which makes the scheme more efficient. Simulations and real world experiment results show that the proposed method is accurate, fast and able to identify the drogue regardless of the changes in environmental conditions. The camera lens distortion has been considered in the monocular vision measurement algorithm for drogue 3D locating, which ensures the accuracy and real-time performance of the system.
Active fault-tolerant control strategy of large civil aircraft under elevator failures
(in lingua inglese)
An AFTC strategy based on model following technique has been proposed in this study for civil aircraft longitudinal control after some elevators fail. By introducing the performance improvement coefficient, AFTC can provide the appropriate controller under elevator faults to achieve the good performance. Implementing the control strategy on B747, the control law is able to track step command preciously without the steady-error. When less two elevators fail, there is no obvious difference whether to utilize the THS in FTCS or not with the increment of amplitude of step command.
CFD calculations on the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode
(in lingua inglese)
VBM/RBM solvers are developed in this work to predict the flowfield around a tilt-rotor in a conversion mode. The developed solvers are validated through comparing the calculated results with the available experimental data. The solvers are also used to investigate the effects of different flight modes on the tilt-rotor flowfield. A combination of the moving-embedded grid methodology and the AIM methodology can account for the rigid blade motions in a conversion mode, and is shown to be effective and robust in searching for the corresponding donor elements and getting the interpolated data for the information communication among different calculation zones. The proposed multi-layer movingembedded grid technique is capable of capturing effectively the unsteady characteristics of the flowfield of the tilt-rotor in a conversion mode.
An investigation of tip vortices unsteady interaction for Fokker 29 propeller with swirl recovery vane
(in lingua inglese)
The steady solutions and transient results for the combination of the propeller/swirl recovery vane are compared and good agreement is obtained. Larger fluctuations of thrust coefficient are observed on the stator so that the variations of the total efficiency depend mainly on the stator working performance. The transient surface pressures of the rotor/stator are decomposed into the blade passing frequency and the first three harmonics are presented. The unsteady load of the stator is about ten times that of the rotor. Large changes appear at the vane leading edge due to the potential disturbance as well as the wake effects of the upstream propeller. Much larger fluctuations occur at the vane tip region as a result of the interaction between the rotor/stator tip vortices.
Boundary-layer transition prediction using a simplified correlation-based model
(in lingua inglese)
The new transition model is implemented into an inhouse CFD solver and tested for some typical cases, ranging from low speed flows to hypersonic flows. Results from simulations in this work show that the accuracies of the flows are significantly improved by the proposed transition model, compared with the fully laminar and fully turbulent calculations.
Heat transfer analysis for fluid flow over an exponentially stretching porous sheet
(in lingua inglese)
The aim of the present paper is to study the boundary layer flow and heat transfer towards an exponentially stretching porous sheet embedded in a porous medium with variable surface heat flux. Similarity transformations are used to convert the partial differential equations corresponding to the momentum and heat equations into highly non-linear ordinary differential equations. Numerical solutions of these equations are obtained. It is found that the skin-friction coefficient increases with increasing the permeability parameter as well as with the suction parameter.
Design of alluvial Egyptian irrigation canals using artificial neural networks method
(in lingua inglese)
In this paper, ANNs have been used for estimating stable alluvial channel dimensions. The ANN model relates hydraulic radius, wetted perimeter, and water surface slope to the channel discharge and mean bed grain size. In developing the ANN model, 311 sets of field data collected from 61 manmade irrigation canals and drains ranging from distributary canals to carriers canals were used. The ANN estimates were compared with the outputs of three existing methods, frequently used to predict Egyptian canals dimensions, based on three different statistical methods.
Frenet frames and invariants of timelike ruled surfaces
(in lingua inglese)
Ruled surfaces have an important role in some areas such as design problems in spatial mechanisms and physics, kinematics and computer aided design (CAD). Especially, the frames and invariants of these surfaces have important applications in these sciences. Moreover, the study of ruled surfaces in the Minkowski 3-space is more interesting than the the Euclidean case. According to the classifications of ruled surfaces, they have different values for derivative of the vectors. So, the kinematics and geometric interpretations can be more different.
Scheduling and sequencing in four machines robotic cell: application of genetic algorithm and enumeration techniques
(in lingua inglese)
A genetic algorithm was developed and used to solve the problem of scheduling robot moves and jobs sequencing in fourmachines blocking robotic cells producing identical or different jobs to minimize the cycle time. The developed GA was tested against the full enumeration procedure and showed high performance in solving the problem.
GIS and geotechnical mapping of expansive soil in Toshka region
(in lingua inglese)
The tailored GIS system provides the processes of retrieving, visualizing, and updating large amounts of information associated with each soil sample and combines them with its spatial location in a clear organized form. This can be executed in an efficient and time saving way. The tailored GIS system, used in this study, provides decision makers with a quick, relevant and integrated tool for judging accurately and rapidly the soil properties and its activity for a particular site.
