Numerical and experimental characterization of a railroad switch machine

This contribution deals with the numerical and experimental characterization of the structural behavior of a railroad switch machine. Railroad switch machines must meet a number of safety-related conditions such as, for instance, exhibiting the appropriate resistance against any undesired movements of the points due to the extreme forces exerted by a passing train. This occurrence can produce very high stress on the components, which has to be predicted by designers. In order to assist them in the development of new machines and in defining what the critical components are, FEA models have been built and stresses have been calculated on the internal components of the switch machine. The results have been validated by means of an ad-hoc designed experimental apparatus, now installed at the facilities of the Department of Industrial Engineering of the University of Bologna. This apparatus is particularly novel and original, as no Standards are available that provide recommendations for its design, and no previous studies have dealt with the development of similar rigs. Moreover, it has wide potential applications for lab tests aimed at assessing the safety of railroad switch machines and the fulfilment of the specifications by many railway companies

Fluoroscopic freehand and electromagnetic-guided targeting system for distal locking screws of humeral intramedullary nail

Purpose The current techniques used to lock distal screws for the nailing of long bone fractures expose the surgeons, radiologists and patients to a hearty dose of ionizing radiation. The Sureshot™ Distal Targeting System is a new technique that, with the same results, allows for shorter surgery times and, consequently, less exposure to radiation. Materials and methods The study was performed on 59 patients (34 males and 25 females) with a simple humerus fracture diagnosis, type 1.2.A according to the AO classification, who were divided into two groups. Group 1 was treated with ante-grade intramedullary nailing with distal locking screws inserted with a freehand technique. Group 2 was treated with the intramedullary nail using the Sureshot™ Distal Targeting System. Two intra-operative time parameters were evaluated in both groups: the time needed for the positioning of the distal locking screws and the time of exposure to ionizing radiations during this procedure. Results Group 2 showed a lower average distal locking time compared to group 1 (645.48″ vs. 1023.57″) and also a lower average time of exposure to ionizing radiation than in group 1 (4.35″ vs. 28.96″). Conclusion The Sureshot™ Distal Targeting System has proven to be equally effective when compared to the traditional techniques, with the added benefits of a significant reduction in both surgical time and risk factors related to the exposure to ionizing radiation for all the operating room staff and the patient

Two-Color Surface Photometry of Brightest Cluster Members

The Gunn g, r and i CCD images of a representative sample of 17 Brightest Cluster Galaxies (BCM) have been analyzed in order to derive surface brightness and color profiles, together with geometrical parameters like eccentricity and position angle. The sample includes both X-ray and optically selected clusters, ranging in redshift from z=0.049 to z=0.191. We find that BCMs are substantially well described by de Vaucouleurs' law out to radii of $\sim 60-80$ kpc, and that color gradients are generally absent. Only in two cases we find a surface brightness excess with respect to the $r^{1/4}$ law, which for A150 is coupled with a change in the $g-r$ color. The rest frame colors of BCMs do not show any intrinsic dispersion. By parametrizing the environment with the local galaxy number density, we find that it is correlated with the BCM extension, i.e. BCMs with larger effective radii are found in denser environments.Comment: accepted for publication in Aj, May 1997, 25 pages LaTeX format (aas style files), including tables, plus 6 figures (postscript

Gas-Sensing Properties of Thermally-Oxidized Metal Oxide Nanowires

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An unusual case of gardening ocular injury during Covid-19 lockdown

NTRODUCTION: Facial trauma are an important cause of serious ocular morbidity. In particular domestic trauma are a small part of total. COVID-19 pandemic has been influencing our life in a way never seen before, people need to remain at home due to lockdown restrictions. In this scenario we are seeing an increase in the percentage of domestic facial trauma. In other hand pandemic has influenced the possibility of hospitalization, so daily based procedures increased their importance in global treatment planning. CASE PRESENTATION: A 58 yo man presented to our ward with a foreign body in left eyebrow. Trauma happened during gardening. CLINICAL DISCUSSION: The importance of imaging to perform the right procedure has become more important during pandemic to reduce time of hospitalization. CONCLUSION: CT scan and ophtalmology consult have been the guideline to avoid a more invasive treat- ment which was performed in an outpatient regimen with local anesthesia

On Hirth Ring Couplings: Design Principles Including the Effect of Friction

Rings with Hirth couplings are primarily used for the accurate positioning of axial-symmetric components in the machine tool industry and, generally, in mechanical components. It is also possible to use Hirth rings as connection tools. Specific industries with special milling and grinding machines are able to manufacture both tailor made and standard Hirth rings available on stock. Unfortunately, no international standard (for instance ISO, DIN or AGMA) is available for the production and the design of such components. In the best-case scenario, it is possible to find simplified design formulae in the catalogue of the suppliers. The aim of this work is to provide some accurate formulae and computational methods for design to provide better awareness on the limitations and the potential of this type of connection. The work consists of five parts: (i) a review of the base calculation derived mainly from the catalogues of manufacturers; (ii) an improved calculation based on a new analytical method including the friction phenomenon; (iii) an experimentation run for validating the method; (iv) a case study applied to a machine tool; and, (v) a closed form formulation to determine an upper threshold for friction, thus ensuring the Hirth coupling regular performance

Open Circulation Facies in the Cenomanian of the Northeastern Margin of the Friuli Platform: the Iudrio Valley Case (NE Italy)

The Early Middle Cenomanian margin sequence of Val ludrio, connected with the northeastem margin of the Friuli Platform shows intercalated layers with pelagic organisms: Calcisphaerulidae and planktonic forams, among which is Favwsella. These are interpreted as transgressive episodes recorded in a calbonate ramp sequence related to a tectonically subsiding margin. ln the Dinaric and Friuli Platforms two distinct Calcisphaerulidae and planktonic forams facies are distinguished for the Cenomanian. The first one, of early-middle Cenomanian age, which is also present in the ludrio sequence, developed in platform margin zones subjected to drawning. The second one, of late Cenomanian age, developed in more internal areas of the Dinaric and Friuli Platforms, and can be related to the transgression associated with the OAE 2 event

Efficient probabilistic reconciliation of forecasts for real-valued and count time series

Hierarchical time series are common in several applied fields. Forecasts are required to be coherent, that is, to satisfy the constraints given by the hierarchy. The most popular technique to enforce coherence is called reconciliation, which adjusts the base forecasts computed for each time series. However, recent works on probabilistic reconciliation present several limitations. In this paper, we propose a new approach based on conditioning to reconcile any type of forecast distribution. We then introduce a new algorithm, called Bottom-Up Importance Sampling, to efficiently sample from the reconciled distribution. It can be used for any base forecast distribution: discrete, continuous, or in the form of samples, providing a major speedup compared to the current methods. Experiments on several temporal hierarchies show a significant improvement over base probabilistic forecasts.Comment: 25 pages, 4 figure

On the dimension of the singular set in optimization problems with measure constraint

In this paper, we prove estimates on the dimension of the singular part of the free boundary for solutions to shape optimization problems with measure constraints. The focus is on the heat conduction problem studied by Aguilera, Caffarelli, and Spruck and the one-phase Bernoulli problem with measure constraint introduced by Aguilera, Alt and Caffarelli. To estimate the Hausdorff dimension of the singular set, we introduce a new formulation of the notion of stability for the one-phase problem along volume-preserving variations, which is preserved under blow-up limits. Finally, the result follows by applying the program developed in [Buttazzo et al. 2022] to this class of domain variation.Comment: 17 pages. arXiv admin note: text overlap with arXiv:2212.0911