Mechanistic cutting force model parameters evaluation in milling taking cutter radial runout into account

The simulation of the cutting process becomes a key aspect on production optimization. The search for optimal cutting parameters by simulation can be a very effective way of reducing the tuning time of the process and can demonstrate potential cost reduction. As the simulation of the microscopic behavior of the cut is still difficult to perform, most of the prediction techniques are based on mechanistic models of the cutting forces, whose parameters are deduced from experimental tests. The runout of the tool can be a parasite effect that lowers the precision of the identification of the cutting forces parameters. This paper shows the improvement of an identification algorithm given by the modeling of radial runout effect on the undeformed chip thickness. Two different models of cutter runout have been used and tested on experimental measurement performed on a static dynamometer. The adequacy between simulation and experiment is good and allows reliable prediction of cutting forces for different cutting conditions.     

Spectral and chemical evidence for the direct formation of carboxylic groups in aerobically oxidised water-soluble fullerenes

The synthesis of oxidised water-soluble fullerenes, prepared by chemically-induced aerobic oxidation, yields functionalised carbon cluster structures, which are oxidised by the covalent insertion of different oxygen units. Their strictly pH-dependent behaviour in aqueous solutions appears to be properly ascribed to the existence of directly attached carboxylic moieties. The presence of these groups, which are usually neglected and underestimated, has been thoroughly investigated. Several concurrent spectral (UV-VIS, XPS, solid-state ¹³C CPMAS NMR, FT-IR, Raman, EDAX, TGA-MS, ESI-MS) and chemical (acid-base behaviour, salt precipitation by metal-complexation, carboxylic functionalisation) methods have provided a definitive set of consistent evidence, indicating for the first time the direct linkage of carboxylic groups on water-soluble fullerenes prepared in this manner.     

Analogies between progressive collapse of structures and fracture of materials

The analogy between structural progressive collapse and Fracture Mechanics is consistent either for phenomenological, technological and theoretical aspects. In this paper a general energy criterion suitable for fracture in heterogeneous materials is applied to study the progressive collapse of simple structures with cohesive post peak behavior: elementary frames and fiber bundles. The analyses put into evidence some interesting scale effects induced by ductility and dynamics. In particular, a power law describing the decrease of the reduced dynamic critical load with the structural scale and a second order ductile-brittle transition, have been found. These results can be usefully applied in robustness oriented structural design. Moreover, the study of the influence of the extent of the starting damage in structures with different sizes suggests that, the elementary cells of complex framed structures can play a role similar to the microstructure of materials. In conclusion, a new approach to the problem of collapse into complex structures by means of the tools of Fracture Mechanics is proposed.     

The impact of indoor thermal conditions,system controls and building types on the building energy demand

It is possible to evaluate the energy demand as well as the parameters related to indoor thermal comfort through building energy simulation tools. Since energy demand for heating and cooling is directly affected by the required level of thermal comfort, the investigation of the mutual relationship between thermal comfort and energy demand (and therefore operating costs) is of the foremost importance both to define the benchmarks for energy service contracts and to calibrate the energy labelling according to European Directive 2002/92/CE. The connection between indoor thermal comfort conditions and energy demand for both heating and cooling has been analyzed in this work with reference to a set of validation tests (office buildings) derived from a European draft standard. Once a range of required acceptable indoor operative temperatures had been fixed in accordance with Fanger's theory (e.g. −0.5 < PMV < −0.5), the effective hourly comfort conditions and the energy consumptions were estimated through dynamic simulations. The same approach was then used to quantify the energy demand when the range of acceptable indoor operative temperatures was fixed in accordance with de Dear's adaptive comfort theory.     

An optical study of alumina films thermal evolution upon ammonia annealing

The physical and structural evolution of alumina films deposited by ALCVD annealed at high temperatures in N₂ has been studied.Low temperature post deposition treatments in NH₃ (PDN) have been performed to evaluate the impact of nitrogen incorporation in the alumina film on its thermal stability. Thermal evolution has been studied by deep UV spectroscopic ellipsometry and grazing X-ray reflectance techniques. AFM measurements were also performed to confirm and complete the ellipsometric and GXR analysis.The change of the crystalline structure was detected by ellipsometry by the different UV refractive index, while the GXR provided a unique thickness evaluation.It was therefore possible to determine the layer densification after the thermal treatment and the impact of the PDN on the transition temperature.     

Simplified analysis of cantilever diaphragm walls in cohesive soils

In this paper, a method is presented for a simplified analysis of cantilever diaphragm walls in cohesive soils under undrained and drained conditions. A rectilinear distribution of the net contact stresses that are not completely predetermined by the limit state is assumed at the soil-wall interface, consistently with the mechanism usually experienced by these structures. Simple equations are derived to readily calculate the contact stress distribution on the wall and the associated internal forces in the ultimate and service conditions. Moreover, these equations require few parameters as input data. Comparisons are carried out with a limit equilibrium method commonly used in design to show the usefulness of the proposed method for practical purposes.     

Spectral properties and dynamics of gold nanorods revealed by EMCCD‐based spectral phasor method

Gold nanorods (NRs) with tunable plasmon‐resonant absorption in the near‐infrared region have considerable advantages over organic fluorophores as imaging agents due to their brightness and lack of photobleaching. However, the luminescence spectral properties of NRs have not been fully characterized at the single particle level due to lack of proper analytic tools. Here, we present a spectral phasor analysis method that allows investigations of NRs' spectra at single particle level showing the spectral variance and providing spatial information during imaging. The broad phasor distribution obtained by the spectral phasor analysis indicates that spectra of NRs are different from particle to particle. NRs with different spectra can be identified in images with high spectral resolution. The spectral behaviors of NRs under different imaging conditions, for example, different excitation powers and wavelengths, were revealed by our laser‐scanning multiphoton microscope using a high‐resolution spectrograph with imaging capability. Our results prove that the spectral phasor method is an easy and efficient tool in hyper‐spectral imaging analysis to unravel subtle changes of the emission spectrum. We applied this method to study the spectral dynamics of NRs during direct optical trapping and by optothermal trapping. Interestingly, different spectral shifts were observed in both trapping phenomena. Microsc. Res. Tech. 78:283–293, 2015. © 2015 Wiley Periodicals, Inc.     

A non-linear analysis to detect the origin of PM10 concentrations in Northern Italy

This work presents the formalization and the application of the factor separation technique in order to investigate the impact of precursor emission and their nonlinear interaction (in particulate matter accumulation processes). By processing the simulations of a 3D multiphase modeling system, the factor separation methodology can support the Environmental Authority in quantifying the impact of precursor emissions on PM10 production and consequently in assessing the feasible efficiency of different emission control strategies over a considered domain. The case study proposed by this paper focuses on the Po Valley region (Northern Italy), characterized by critical PM10 levels claiming for sound emission reduction policies. The results show the heavy nonlinearities and the strong seasonal dependence in the formation of PM10, over the study domain. Furthermore the results highlight that peak PM10 concentrations are mainly related to primary PM emissions in urban areas, and gas emissions (mainly NOx and NH3) in rural areas.     

A spectro-microscopic investigation of Fe-Co bimetallic catalysts supported on MgO for the production of thin carbon nanotubes

Fe-Co bimetallic catalysts supported on MgO were studied for the catalytic chemical vapor deposition growth of carbon nanotubes (CNTs). Different wt.% metal loadings were investigated at various deposition temperatures and times. Characterization of the products involved thermal analysis (DTA-TGA), X-ray diffraction, spectroscopy (Raman, UPS, EELS and STS) and microscopy (SEM, TEM and STM) techniques. It was found that the metal content is critical, not only to the yield and the structural quality of the synthesized carbon nanotubes, but it can be also used to tune the desired type of synthesized nanotubes. Lower (2 wt.%) loadings of Fe-Co catalysts favor the formation of single- and/or double-wall CNTs for deposition time and temperature 30 min and 800 °C, respectively. Thermal analysis and Raman measurements showed that these thin CNTs were synthesized at high amounts (CNT-per-catalyst wt.% of more than 100%), exhibiting high graphitization degree with only traces of by-products (mainly amorphous carbon) among them. Microscopy results revealed the formation of CNTs bundles, consisting of individual nanotubes with less than 2 nm outer diameter, while additional energy loss measurements pointed out that the deposited CNTs are mainly single wall. Higher (10 wt.%) Fe-Co loadings resulted to the formation of multi-wall CNTs.