367 research outputs found
Development of Biofidelic Human Head and Neck Surrogates for the Experimental Evaluation of Advanced Injury Criteria
No full textImproving people's safety is a challenge which requires skills and expertise coming from different fields from medicine to engineering. About this, the role of an engineer is to provide devices to protect people and tools to objectively evaluate their performance according to clinical evidences. Head injuries alone lead to a big percentage of hospitalization and fatalities among people subjected to traumatic events in traffic, sports, and work activities. Therefore the research field linked to the understanding of injury mechanisms and their mitigation is of great importance. There are several types of head injury each with its own cause and outcome, and specific protection developed aiming to mitigate it. Helmets have represented a form of protection since many years. At first, protection was meant to avoid skull fractures and specific injury criteria were developed and applied to the testing of helmet as a functional requirement, thankfully improving their performances. Then, protection was improved also for severe closed head injuries by using energy absorbing materials which mitigated accelerations to the head coming from the impact. Nowadays, modern helmets could significantly reduce the incidence of many severe or fatal head injuries. The research of injury mechanisms improved also thanks to FE model of the human head, which helped to identify other mechanisms of brain injury. Moreover, they aided the design of more advanced protective devices which aim to reduce injury risk to the brain during impacts with a strong rotational component. However, while FE models are capable of providing really detailed modeling of the human head structures and give the full field of kinematics, strain and stresses for each element of the head, experimental tests are still limited to rigid headforms which have poor biofidelity and simple sensor output (usually a triaxial accelerometer and gyrometer applied to the skull). To address this, some headforms with higher bio fidelity and more advanced sensors were developed. Starting from this fact, the purpose of this thesis is to improve bio fidelic head model to investigate closed head injuries. This surrogate head aims to replicate of some anatomical structures such as skull, scalp, brain and meninges with materials having similar mechanical properties of the human tissues. Furthermore, the surrogate will be equipped with several sensors to provide kinematics, pressure waves, and internal stress of brain and skull. Together with the head, also a neck surrogate with biofidelic response and integrated sensors will be studied to work as a stand alone tool or to be paired with the head. The first part of the thesis aimed to develop a sensor to measure the internal stress state inside the brain surrogate, providing both normal and shear stress. Together with the sensor development, some materials were investigated as possible surrogates for the brain tissue. Then, the work moved to the improvement of the plastic skull, which was completely redesigned to provide a robust and reversible connection between its two parts needed to insert the inner structures. The work on the skull was followed by a modeling of the meninges, in particular focusing on the subarachnoid space and the two membranes separating brain lobes and brain from cerebellum: falx cerebri and tentorium cerebelli. After its full realization, the head was used together with a custom drop tower built according to standards for motorcycle helmets (UNECE 22.06) to perform conventional drop tests. In the second part of the thesis a new neck surrogate was developed from a first prototype available at the university. The prototype was completely renewed by redesigning the plastic discs replicating the vertebrae, allowing compatibility with Hybrid III dummy head and trunk. NOT COMPLETE (too long for the form, please read in the thesis)
The use of iodine staining for the quantitative analysis of lipids separated by thin layer chromatography
No full textThe use of iodine staining for the quantitative analysis of lipids separated by thin layer chromatography.
No full textTorsion loads on a ski-touring boot sole during uphill climbing and downhill skiing
No full textIntroduction: Ski-touring is a well settled winter activity in mountain regions. Differently to alpine skiing, the high ground is reached by climbing the mountain using sealskins under the skis and special boots and bindings. This difference introduces higher concerns on the weight of the equipment rather than other skiing disciplines. Nevertheless, to allow a safe and enjoyable skiing the structural properties of the boot must be guaranteed. Past studies aimed to determine loads and stiffness of alpine and cross-country skiboots using in field or laboratory approaches [1,2,3]. The present study aims to provide an estimation of the torsion loads acting on the ski-touring boot sole during walking and skiing phases. Such measure is helpful towards the design of more performant ski-touring boots.
Methods: A ski-touring boot (left side, size: 26.5 MP) was prepared with strain gauge bridges and calibrated using a servohydraulic machine (Fig 1a). First, the outer rubber sole was cut to reach the plastics of the boot shell. Then, two full Wheatstone bridge were placed on the sole in middle length of the boot to measure torsion and flexion loads.
To calibrate the boot sole close to in-field testing conditions, a silicone dummy foot was fitted inside the boot. Then, the skiboot was mounted on ski-touring bindings surrogates attached to a servohydraulic torsion machine. The torsion channel was calibrated by applying a quasi-static ramp between -5/+5°, reading the applied torque and bridge output synchronously to obtain the bridge sensitivity.
The in-field test took place in Val di Zoldo (BL, Italy), outside temperature was 10 °C, on a slope covered by spring snow. The instrumented boot was connected to a SoMat eDAQ lite data acquisition system (HBM) powered with a 12 V battery, instrumentation was fitted in a small backpack (total weight: 3 kg). Data were acquired at a 500 Hz sampling rate.
Tests were performed by an amateur skier (height: 175 cm, weight: 70 kg, age: 25 yr) who climbed and skied an off-piste route graded BS in Blachère scale. The participant performed a 400 m gain uphill climbing which was divided into straight climb, and left/right side traverses. During the descent the participant was asked to perform narrow and wide slaloms at its own typical speed. Overall length of the test was 45 minutes.
Peak and valleys of data were computed and averaged for each phase to obtain the range of the load. The mean of the signal during each phase was also computed. Internal rotating torques applied to the boot front are positive.
Results and discussion: Calibration trials gave a bridge sensitivity of -12.59 Nm/(mV/V) with an applied torque ranging from -50 to +50 Nm. In field test data (Fig 1b, Table 1) evidenced highest torque ranges during skiing phase; torque mean values showed opposite sign in the two sides of uphill climbing. In both phases the range was well below the torque reached during the calibration trials.
This suggests that ski-touring boot torsion loads should be based on maximal values collected during skiing trials. The analysis and implementation of further measurement channels such as the sole flexion and the ski/walk links will be performed to improve the understanding of climbing and skiing loads. More tests are being conducted to account for subject variability and snow/terrain conditions.
1. Petrone N., Marcolin G., Centofante E., Atzori B. (2010), Analysis of the structural behavior of an innovative reinforced ski boot. Procedia Engineering. 2. 2599-2604. 10.1016/j.proeng.2010.04.038.
2. Petrone N., Marcolin G., Panizzolo F., (2013), The effect of boot stiffness on field and laboratory flexural behavior of alpine ski boots. Sports Engineering. 16. 10.1007/s12283-013-0133-z.
3. Hladnik J. Resman F. Jerman B. (2012), Torsion stiffness of a racing cross-country ski boot. Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology
Center of Pressure Behavior in Response to Unexpected Base of Support Shifting: A New Objective Tool for Dynamic Balance Assessment
No full textThe translation of the base of support represents a promising approach for the objective assessment of dynamic balance control. Therefore, this study aimed to present a servo-controlled, electrically driven movable plate and a new set of parameters based on the center-of-pressure (CoP) trajectory. Twenty subjects were assessed on a force platform screwed over a movable plate that could combine the following settings: direction (forward (FW) and backward (BW)), displacement (25 mm, 50 mm, and 100 mm), and ramp rate (100 mm/s and 200 mm/s). The subjects underwent two sets of 12 trials randomly combining the plate settings. From the CoP trajectory of the 2.5 s time window after the perturbation, the 95% confidence-interval ellipse (Area95) and the CoP mean velocity (Unit Path) were calculated. Within the same time window, the first peak (FP), the maximal oscillations (ΔCoPMax), and the standard deviation (PPV) of the CoP anterior–posterior trajectory were calculated. The plate direction (p < 0.01), ramp rate (p < 0.001), and displacement (p < 0.01) affected the Area95, FP, and ΔCoPMax, while the Unit Path and PPV were influenced only by the ramp rate (p < 0.001) and displacement (p < 0.001). The servo-controlled, electrically driven movable plate and the CoP-related parameters presented in this study represent a new promising objective tool for dynamic balance assessment
New maximum scattered linear sets of the projective line
No full textIn [A. Blokhuis, M. Lavrauw: Scattered spaces with respect to a spread in PG(n,q), Geom. Dedicata 81 (2000), 231--243.] and [G. Lunardon, O. Polverino: Blocking Sets and Derivable Partial Spreads, J. Algebraic Combin. 14 (2001), 49-56.] are presented the first two families of maximum scattered GF(q)-linear sets of the projective line PG(1,q^n). More recently in [J. Sheekey: A new family of linear maximum rank distance codes, Adv. Math. Commun. 10(3) (2016), 475-488.] and in [B. Csajbók, G. Marino, O. Polverino, C. Zanella: A new family of MRD-codes, Linear Algebra Appl. 548 (2018), 203-220.], new examples of maximum scattered GF(q)-subspaces of V(2,q^n) have been constructed, but the equivalence problem of the corresponding linear sets is left open.
Here we show that the GF(q)-linear sets presented in [J. Sheekey: A new family of linear maximum rank distance codes, Adv. Math. Commun. 10(3) (2016), 475-488.] and in [B. Csajbók, G. Marino, O. Polverino, C. Zanella: A new family of MRD-codes, Linear Algebra Appl. 548 (2018), 203-220.], for n=6,8, are new.
Also, for q odd, q congruent to 1, -1, or 0 (mod 5), we present new examples of maximum scattered GF(q)-linear sets in PG(1,q^6), arising from trinomial polynomials, which define new GF(q)-linear MRD-codes of GF(q)^6×6 with dimension 12, minimum distance 5 and left idealiser isomorphic to GF(q^6)
MRD-codes arising from the trinomial x<sup>q</sup>+x<sup>q<sup>3</sup> </sup>+cx<sup>q<sup>5</sup> </sup>∈F<sub>q<sup>6</sup> </sub>[x]
No full textIn [10], the existence of Fq-linear MRD-codes of Fq 6×6, with dimension 12, minimum distance 5 and left idealiser isomorphic to Fq6 , defined by a trinomial of Fq6 [x], when q is odd and q≡0,±1(mod5), has been proved. In this paper we show that this family produces Fq-linear MRD-codes of Fq 6×6, with the same properties, also in the remaining q odd cases, but not in the q even case. These MRD-codes are not equivalent to the previously known MRD-codes. We also prove that the corresponding maximum scattered Fq-linear sets of PG(1,q6) are not PΓL(2,q6)-equivalent to any previously known linear set.</p
Responsabilità e automazione: una metodologia per la valutazione del rischio giuridico basata sull'argomentazione
No full textL’obiettivo di questo lavoro è di presentare una ricerca mirata a rappresentare le regole giuridiche per mezzo di argument maps (mappe di argomenti), e l’utilizzo di tali mappe all’intero del Legal Case, uno strumento metodologico che ha l’obiettivo di supportare l’integrazione di tecnologie ad alta automazione nei sistemi complessi, in particolare nella gestione del traffico aereo. Il contributo presenta brevemente la metodologia, e descrive lo sviluppo e l’utilizzo delle mappe di argomenti per la rappresentazione dell’informazione giuridica. Sono infine presentati i risultati della validazione dell’approccio basato sulle mappe, e le prospettive future della ricerca
Multi-orbit cyclic subspace codes and linear sets
No full textCyclic subspace codes gained a lot of attention especially because they may
be used in random network coding for correction of errors and erasures. Roth,
Raviv and Tamo in 2018 established a connection between cyclic subspace codes
(with certain parameters) and Sidon spaces. These latter objects were
introduced by Bachoc, Serra and Z\'emor in 2017 in relation with the linear
analogue of Vosper's Theorem. This connection allowed Roth, Raviv and Tamo to
construct large classes of cyclic subspace codes with one or more orbits. In
this paper we will investigate cyclic subspace codes associated to a set of
Sidon spaces, that is cyclic subspace codes with more than one orbit. Moreover,
we will also use the geometry of linear sets to provide some bounds on the
parameters of a cyclic subspace code. Conversely, cyclic subspace codes are
used to construct families of linear sets which extend a class of linear sets
recently introduced by Napolitano, Santonastaso, Polverino and the author. This
yields large classes of linear sets with a special pattern of intersection with
the hyperplanes, defining rank metric and Hamming metric codes with only three
distinct weights.Comment: Title and the organization of the paper have been changed. Accepted
for publication for Finite Fields and Their Application
A characterization of linearized polynomials with maximum kernel
No full textWe provide sufficient and necessary conditions for the coefficients of a q-polynomial f over which ensure that the number of distinct roots of f in equals the degree of f.
We say that these polynomials have maximum kernel. As an application we study in detail q-polynomials of degree over which have maximum kernel and for n ≤ 6 we list
all q-polynomials with maximum kernel. We also obtain information on the splitting field of an arbitrary q-polynomial. Analogous results are proved for q^s-polynomials as well, where
gcd(s, n) = 1
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