Study of impact on helicopter blade

This article presents a study of damage in structures that are similar to helicopter blade sections, subjected to an impact. These complex composite structures were impacted by a steel ball of 125 g at impact speed ranging from 30 to 130 m/s. This led to properly highlight the kinematics of the impact and to define the sequence of the damage’s mechanisms. An explicit FE model is also presented. The damage modelling of the roving is performed through a scale change. It allows a good representation of observed experimental behaviour. As the mesh density is low, it can be used for the modelling of a real structure

Spiral tessellation on the sphere

In this paper we describe a tessellation of the unit sphere in the 3-dimensional space realized using a spiral joining the north and the south poles. This tiling yields to a one dimensional labeling of the tiles covering the whole sphere and to a 1-dimensional natural ordering on the set of tiles of the tessellation. The correspondence between a point on the sphere and the tile containing it is derived as an analytical function, allowing the direct computation of the tile. This tessellation exhibits some intrinsic features useful for general applications: absence of singular points and efficient tiles computation. Moreover, this tessellation can be parametrized to obtain additional features especially useful for spherical coordinate indexing: tiles with equal area and good shape uniformity of tiles. An application to spherical indexing of a database is presented, it shows an assessment of our spiral tiling for practical uses

Neutronic benchmark of the FRENETIC code for the multiphysics analysis of lead fast reactors

The FRENETIC code is being developed at Politecnico di Torino in the frame of the international effort for the deployment of lead fast reactors technology. FRENETIC is a multiphysics computational tool solving the neutronics and thermal-hydraulics equation at the full-core level, aiming at performing steady-state and time-dependent simulations in different conditions. In the present work, the validation activity of FRENETIC is carried forward by performing a benchmark against a reference computational model for the ALFRED design implemented in Serpent. Different core configurations in FRENETIC and different temperature distributions are considered, performing consistent comparisons between the two codes. All the results obtained show an extremely good agreement between the two models, implying that the ALFRED core can be well characterized by the FRENETIC code. The present study sets the basis for the future application of the code to simulate safety-relevant transients with FRENETIC

Intergovernmental cooperation for hydrometry – what, why and how?

Two thirds of hydrological observation networks in developing countries are reported to be in poor or declining condition. At the same time innovation in sensor technologies and data processing are presenting opportunities for enhancing observation networks that are not being realized. The World Meteorological Organization’s Global Hydrometry Support Facility, or WMO HydroHub, was launched in 2016 to transform assistance to operational water monitoring agencies around the world. If successful, the initiative will increase the amount of hydrometric data available to researchers, catchment managers and water policy makers. To those unfamiliar with UN organizations, however, the nature of such initiatives, the reasoning behind the decisions taken to establish them and the mechanisms by which they try to deliver benefits for society, can be opaque. This paper adopts a novel dialogue-style format to explore the set-up of the WMO HydroHub and build awareness amongst those who ultimately may benefit from its approaches

Segmental ureterectomy vs. radical nephroureterectomy for ureteral carcinoma in patients with a preoperative glomerular filtration rate less than 90 ml/min/1.73 m2: A multicenter study

Objectives: To compare segmental ureterectomy (SU) and radical nephroureterectomy (RNU) in terms of overall survival (OS) and impact on postoperative renal function in patients treated for upper tract urothelial carcinoma (UTUC) of the ureter with preoperatively reduced estimated glomerular filtration rate (eGFR). Materials and methods: We retrospectively collected the data of consecutive patients treated for UTUC, in 6 Italian tertiary referral centers, from 2003 to 2013, and analyzed those treated with RNU or SU for ureteral cancer and with a preoperative eGFR <90 ml/min/1.73m2. The primary outcome was to compare the postoperative eGFR variation and the OS according to the surgical technique chosen. Results: Out of 521 patients with UTUC, 228 patients had preoperative reduced eGFR. Out of these patients, 93 had ureteral cancer and were included in the primary analyses \u2013 67 (72.0%) treated with RNU and 26 (28.0%) with SU. Preoperative characteristics were similar in the 2 groups. The overall median follow-up period was 26.5 months. A nonsignificant postoperative eGFR decrease of 3.0 ml/min/1.73m2 was found overall (P = 0.094), with nonsignificant difference between the 2 groups (P = 0.735). A comparable 5-year OS was calculated for RNU and SU patients (P = 0.99). Conclusions: The type of surgery (SU vs. RNU) has a low impact on postoperative renal function and OS in patients with ureteral cancer and preoperative eGFR <90 ml/min/1.73m2. The indications for kidney sparing surgery for UTUC should be based on the surgical and oncological risks in these patients

Damage in single lap joints of woven fabric reinforced polymeric composites subjected to transverse impact loading

Single lap joints of woven glass fabric reinforced phenolic composites, having four different overlap widths, were impacted transversely using a hemispherical impactor with different velocities in the low velocity impact range. The resulting damage was observed at various length scales (from micro to macro) using transmission photography, ultrasonic c-scan and x-ray micro tomography (XMT), in support of each other. These experimental observations were used for classification of damage in terms of damage scale, location (i.e. ply, interfaces between plies or bond failure between the two adherends) and mechanisms, with changing overlap width and impact velocity. In addition, finite element analysis was used to simulate delamination and disbond failure. These simulations were used to further explain the observed dependence of damage on overlap width and impact velocity. The results from these experiments and simulations lead to the proposal of a concept of lower and upper characteristic overlap width. These bounds relate the dominant damage pattern (i.e. scale, location and mechanism) with overlap width of the joint for a given impact velocity range.National University of Sciences and Technology, NUST, Pakistan: The University of Manchester, EPS fellowshi