Divergence, at what cost?

The EU-UK Trade and Cooperation Agreement is a free trade agreement like no other: the first between parties negotiating from a position of regulatory convergence; the first trade deal in which the EU has accepted the principle of no tariffs and no quotas, but also the first trade deal which not only incorporates provisions that can broaden and deepen the Agreement’s scope, but also narrow it. However, at what cost are the parties willing to increase divergence, asks Totis Kotsonis (Pinsent Masons LLP)

Wavelet-like analysis in the frequency-damping domain for modal parameters identification

Modal analysis and parametric model identification play a fundamental role in many fields, especially for the optimization and vibration control of civil structures and complex mechanical systems. In the last decades these techniques have been frequently applied for the development of innovative cutting tools and CNC machine tools. Although several methodologies are available in literature for parametric model identification, there is still a lack of an effective and robust algorithm. In this paper a new algorithm for automatic identification of a parametric model of a linear dynamic Single Input Single Output system with Multiple Degrees of Freedom is presented. Some recent approaches perform the Wavelet decomposition of the Impulse Response in the time-frequency domain. Here a Wavelet-like decomposition of the Frequency Response in the frequency-damping domain is introduced for vibration modes recognition. Afterwards, advanced statistical approaches are applied for vibration modes selection and model generation. The method was successfully tested on a complicated frequency response characterized by several vibration modes, which was obtained from experimental modal analysis performed on a circular saw blade

Influence of the Experimental Setup on the Damping Properties of SLM Lattice Structures

Background: Metal lattice structures obtained through Selective Laser Melting may increase the strength-to-weight ratio of advanced 3D printed parts, as well as their damping properties. Recent experimental results showed that AlSi10Mg and AISI 316L lattices are characterized by higher Rayleigh damping coefficients with respect to the fully dense material. However, some unclear or contradictory results were found, depending on the experimental setup adopted for modal analysis. Objective: In this work the influence of the experimental setup when performing modal analysis on different SLM AISI 316L lattice structures was deeply investigated. The study provides a critical comparison of various experimental modal analysis approaches, allowing to evaluate the influence of external damping sources and material internal damping phenomena. Methods: The dynamic behaviour of SLM AISI 316L specimens incorporating lattice structures was estimated by means of pulse testing and sinusoidal excitation through an electromagnetic shaker. The validity of the viscous damping model was assessed by means of sinusoidal excitation with different levels of vibration velocity. Moreover, the influence of experimental setup on modal analysis results was critically evaluated, by considering different actuators, contact and non-contact sensors and boundary/clamping conditions. Results: The classical viscous damping model describes with good approximation the damping properties of SLM lattice structures. When exciting single specimens in free-free conditions, those embedding lattice structure and unmelted metal powder filler were characterized by superior internal damping properties with respect to the specimens incorporating the lattice structure without any filler, which was however more effective than the full density equivalent material. Most of the other experimental setups introduced additional external damping sources, that could alter this important outcome. Conclusions: SLM lattice structures embedded into 3D printed components provide superior damping properties against mechanical and acoustic vibrations and the metal powder filler does significantly enhance such damping capacity. A correct estimation of material internal damping was achieved by applying non-contact sensors and free-free boundary conditions, whereas other experimental setups were partly inadequate

Upgraded Kalman filtering of cutting forces in milling

Advanced piezoelectric dynamometers with a wide frequency bandwidth are required for cutting force measurement in high-speed milling and micromilling applications. In many applications, the signal bandwidth is limited by the dynamic response of the mechanical system, thus compensation techniques are necessary. The most effective compensation techniques for a full 3D force correction require an accurate and complex identification phase. Extended Kalman filtering is a better alternative for input force estimation in the presence of unknown dynamic disturbances. The maximum bandwidth that can be currently achievable by Kalman filtering is approximately 2 kHz, due to crosstalk disturbances and complex dynamometer\u2019s dynamics. In this work, a novel upgraded Kalman filter based on a more general model of dynamometer dynamics is conceived, by also taking into account the influence of the force application point. By so doing, it was possible to extend the frequency bandwidth of the device up to more than 5 kHz along the main directions and up to more than 3 kHz along the transverse directions, outperforming state-of-the-art methods based on Kalman filtering

Utjecaj skladištenja plodova masline u vrećama na kakvoću ulja i sastav hlapljivih sastojaka

The composition of olive oil volatile components depends on genetic factors, ripening grade of the fruit, fruit storage and processing conditions. Storage of olives in reticular or plastic bags is still a frequently used practice that has negative effects on oil quality, particularly on sensory characteristics. The changes of volatile compounds during this procedure were determined using headspace solid phase microextraction (HS-SPME). The method was optimised as regards sample conditioning and extraction time, and verified by testing the repeatability and linearity of the response. The main changes during fruit storage in bags are increase of methanol and ethanol concentration and decrease of 1-penten-3-one, trans-2-hexenal and cis-3-hexenyl acetate concentration. The changes in plastic bags are more evident and significant differences between the two types of storage are established.Sastav hlapljivih sastojaka maslinovog ulja ovisi o genetičkim faktorima, stupnju zrelosti plodova i njihovu skladištenju te uvjetima preradbe. Još uvijek se često primjenjuje skladištenje maslina u mrežastim ili plastičnim vrećama, što negativno utječe na kakvoću ulja, osobito na senzorska svojstva. Promjene hlapljivih sastojaka tijekom ovoga postupka utvrđene su primjenom mikroekstrakcije na čvrstoj fazi u natprostoru (HS-SPME). Metoda je optimirana s obzirom na kondicioniranje uzorka i vrijeme ekstrakcije, te provjerena utvrđivanjem ponovljivosti i linearnosti odgovora. Glavne su promjene tijekom skladištenja plodova u vrećama povećanje koncentracije metanola i etanola, te smanjenje koncentracije 1-penten-3-ona, trans-2-heksenala te cis-3-heksenil acetata. Promjene u plastičnim vrećama više su izražene, a uočene su i bitne razlike između dvaju načina skladištenja

Effects of different cross-sections of Body Centered Cubic cells on pressure drop and heat transfer of additively manufactured heat sinks

In many industrial applications, heat loads management requires the design and production of compact heat exchangers which are expected to handle high thermal loads with acceptable pressure losses, while assuring good mechanical performances. These challenging targets can be achieved by filling the cavities where the cool/hot fluid circulates with lattice structures promoting the heat exchange between the fluid and the cavity boundaries. Such lattice structures can be only produced through Additive Manufacturing due to their high geometric complexity. Recent experimental investigations proved the effectiveness of some kinds of lattice structures having a circular cross section. Here the aerothermal behaviour of Body-Centred Cubic (BCC) lattice stagger arrays in a rectangular channel was experimentally investigated by considerably extending the previous studies to higher Reynolds numbers (up to 30′000) and to new types of lattice structures. Specifically, three new BCC structures having a cam-like, drop-like and elliptical cross section were explored in this work and compared against those having circular cross section. All the samples were manufactured by means of Laser Powder Bed Fusion and made from AlSi10Mg. At first, the heat exchangers were comprehensively characterized by means of optical non-destructive methods. Successively they were tested in a dedicated rig by imposing constant heat flux boundary conditions. The characteristics of the transitional or fully turbulent approaching flow to the test section are also reported thanks to dedicated flow field measurements performed by Particle Image Velocimetry. According to the obtained results, the BCC structure with the circular cross section of larger diameter is the most effective in terms of heat transfer, although it is largely penalized by the pressure losses. Similar heat transfer performances were achieved by the tapered cross section of elliptical shape with the advantage of a considerably lower friction factor. Pressure losses resulted almost identical for all the tapered cross sections but lower than those of the circular one having an equal frontal dimension. When considering the thermal performance factor the circular shape becomes unfavourable for Re>20′000, while the elliptical cross section is the best choice to efficiently promote heat transfer up to Re=30′000

State aid and Brexit: the temptation for political intervention

State aid is currently regulated by the EU and, after Brexit, the government intends to transpose the rules into UK legislation, with the Competitions and Markets Authority overseeing the issue. Totis Kotsonis (Eversheds Sutherland) explains why future governments could be tempted to allow political intervention that EU membership precludes

Digital upgrade of a bandsaw machine through an innovative guidance system based on the digital shadow concept

Nowadays, there is an increasing trend towards advanced CNC machine tools having a high level of automation. Nevertheless, manually operated equipment is still playing an important role in many industrial workshops. Operators’ experience is still essential in the perspective of increasing productivity, enhancing product quality, reducing manufacturing costs related to tool wear, waste and maintenance. Thus, even manual operations that are apparently less important in terms of product added value may deserve attention and need to be improved according to the principles of the digital transformation era. This paper introduces a structured approach for design, development and implementation of an operator guidance system for a manual bandsaw machine, based on the digital shadow concept and additional feedback sensors. This provides an actual example of how the digital transformation of a small-scale equipment may improve the manufacturing performance and ergonomics as well

Passive chatter suppression of thin-walled parts by means of high-damping lattice structures obtained from selective laser melting

Chatter vibrations arising during machining operations are detrimental for cutting process performance, since they may cause poor surface quality of the machined part and severe damages to machine tool elements. Passive approaches for chatter suppression are based on the integration of special mechanical components with high-damping properties within the machining system. They represent a good solution to this problem thanks to their intrinsic simplicity. Recently, the application of metallic lattice structures inside 3D printed parts obtained from the Selective Laser Melting technology have proven superior damping properties with respect to the same full density material. Here, this idea is further explored by considering the novel configuration where the unmelted powder grains are retained inside the lattice structure by an external shell, acting as a multiplicity of microscopic mechanical dampers. This concept is applied for passive chatter suppression of thin-walled parts that are of particular relevance for industry. Preliminary experimental investigation was first carried out on simple beam-like specimens, and then on thin-walled benchmarks that were identified through modal analysis and tested under real cutting conditions. The main conclusion is that the novel proposed configuration (lattice plus unmelted powder) has higher damping properties with respect to the full density and lattice alternatives. Accordingly, it may be successfully applied for passive chatter suppression in real machining operations

Classifying Italian newspaper text: news or editorial?

We present a text classifier that can distinguish Italian news stories from editorials. Inspired by earlier work on English, we built a suitable train/test corpus and implemented a range of features, which can predict the distinction with an accuracy of 89,12%. As demonstrated by the earlier work, such a feature-based approach outperforms simple bag-of-words models when being transferred to new domains. We argue that the technique can also be used to distinguish opinionated from non-opinionated text outside of the realm of newspapers.Presentiamo una tecnica per la classificazione di articoli di giornale in italiano come articoli di cronaca oppure editoriali. Ispirandoci a precedenti pubblicazioni riguardanti la lingua inglese, abbiamo costruito un corpus adatto allo scopo e selezionato un insieme di caratteristiche testuali in grado di distinguere il genere con un accuratezza dell’ 89,12%. Come dimostrato dai lavori precedenti, questo approccio basato sulle proprietà del testo mostra risultati migliori rispetto ad altri quando trasferito a nuovi argomenti. Riteniamo inoltre che questa tecnica possa essere usata con successo anche in contesti diversi dagli articoli di giornale per distinguere testi contenenti opinioni dell’autore e non