Design methodology for an air-lubricated seal

A methodology to design an air-lubricated piston seal for pneumatic actuators is described. Such a seal permits a small air leakage through a very narrow gap between the seal lip and the counterpart; this air film both avoids contact and ensures lubrication at the seal-counterpart interface thus permitting reduced friction and wear. Subsequently the use of grease could be limited or avoided. A seal geometry equipped with a self-pressurized balancing chamber was designed to make leakage as insensitive as possible to the supply pressure and to the barrel machining tolerances. A prototype was manufactured and tests were carried ou

A new conceptual approach for systematic error correction in CNC machine tools minimizing worst case prediction error

A new artifact-based method to identify the systematic errors in multi-axis CNC machine tools minimizing the worst case prediction error is presented. The closed loop volumetric error is identified by simultaneously moving the axes of the machine tool. The physical artifact is manufactured on the machine tool and later measured on a coordinate measuring machine. The artifact consists of a set of holes in the machine tool workspace at locations that minimize the worst case prediction error for a given bounded measurement error. The number of holes to be drilled depends on the degree of the polynomials used to model the systematic error and the number of axes of the machine tool. The prediction error is also function of the number and location of the holes. The feasibility of the method is first investigated for a two-axis machine to find the best experimental setting. Finally based on the two-axis case study, we extend the results to machine tools with any number of axes. The obtained results are very promising and require only a short time to produce the artifac

High-performance device for air interlacing of a yarn and corresponding method

Abstract A device for air interlacing of a yarn , comprising an interlacing chamber , a first entrance channel for receiving the yarn at the device entrance and feeding it to the interlacing chamber , and a second exit channel for receiving the yarn from the interlacing chamber and releasing it at the device exit, in which the interlacing chamber is delimited by a first emitting wall bearing a nozzle for the emission of a continuous jet of compressed air , and a second deflecting wall , opposite the first wall , suitable for receiving and deflecting the jet of compressed air emitted by the nozzle and intersecting the yarn to be interlaced, and in which the second deflecting wall is concave in shape both on a transversal plane and on a longitudinal plane with respect to the feeding path of the yarn through the device

A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at sqrt(s) = 13 TeV

A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at s=13TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb-1 . The 95% confidence level upper limit set on the branching fraction of the 125 GeV Higgs boson to invisible particles, B(H → inv) , is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous B(H → inv) searches carried out at s=7 , 8, and 13 TeV in complementary production modes. The combined upper limit at 95% confidence level on B(H → inv) is 0.15 (0.08 expected)

Preliminary structural analysis of an active exoskeleton for robotic neuro-rehabilitation

In this paper the exoskeleton P.I.G.R.O. (Pneumatic Interactive Gait Rehabilitation Orthosis), developed in the Department of Mechanical and Aerospace Engineering (DIMEAS) Politecnico di Torino with the important co-operation with doctors, is presented. It was preliminary designed for a completely unloaded walking gait cycle in order to treat the first steps of the neurorehabilitation trainings. An initial FEM evaluation of P.I.G.R.O. structure is here presented. It underlines a lot of important aspects and techniques to analyse the structural characteristics of P.I.G.R.O. legs rigid parts using a commercial software but analysing both the actions of the pneumatic actuators and of the patients muscles and/or movements. The results obtained are good and allow to verify the P.I.G.R.O. legs structure and to establish a procedure to study its characteristics also with the presence of the patien

Measurements of the azimuthal anisotropy of prompt and nonprompt charmonia in PbPb collisions at sqrt(s_NN)= 5.02 TeV

The second-order (v2) and third-order (v3) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of √sNN = 5.02TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb−1 recorded with the CMS detector. The J/ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. The v2 and v3 coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured v2 values for prompt J/ψ mesons are found to be larger than those for nonprompt J/ψ mesons. The prompt J/ψ v2 values at high pT are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/ψ meson v3 and prompt ψ(2S) v2 and v3 values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions

Measurements of inclusive and differential cross sections for the Higgs boson production and decay to four-leptons in proton-proton collisions at sqrt(s) = 13 TeV

Measurements of the inclusive and differential fiducial cross sections for the Higgs boson production in the H → ZZ → 4l (l = e, μ) decay channel are presented. The results are obtained from the analysis of proton-proton collision data recorded by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. The measured inclusive fiducial cross section is 2.73 ± 0.26 fb, in agreement with the standard model expectation of 2.86 ± 0.1 fb. Differential cross sections are measured as a function of several kinematic observables sensitive to the Higgs boson production and decay to four leptons. A set of double-differential measurements is also performed, yielding a comprehensive characterization of the four leptons final state. Constraints on the Higgs boson trilinear coupling and on the bottom and charm quark coupling modifiers are derived from its transverse momentum distribution. All results are consistent with theoretical predictions from the standard model

First measurement of the top quark pair production cross section in proton-proton collisions at sqrt(s) = 13.6 TeV

The first measurement of the top quark pair (tt ̄) production cross section in proton-proton collisions at s√ = 13.6 TeV is presented. Data recorded with the CMS detector at the CERN LHC in Summer 2022, corresponding to an integrated luminosity of 1.21 fb−1, are analyzed. Events are selected with one or two charged leptons (electrons or muons) and additional jets. A maximum likelihood fit is performed in event categories defined by the number and flavors of the leptons, the number of jets, and the number of jets identified as originating from b quarks. An inclusive tt ̄ production cross section of 881 ± 23 (stat + syst) ± 20 (lumi) pb is measured, in agreement with the standard model prediction of 924+32−40 pb