Search results for "Fracture"

Investigating the effects of intersection flow localization in equivalent-continuum-based upscaling of flow in discrete fracture networks

2021

Abstract. Predicting effective permeabilities of fractured rock masses is a crucial component of reservoir modeling. Its often realized with the discrete fracture network (DFN) method, whereby single-phase incompressible fluid flow is modeled in discrete representations of individual fractures in a network. Depending on the overall number of fractures, this can result in high computational costs. Equivalent continuum models (ECMs) provide an alternative approach by subdividing the fracture network into a grid of continuous medium cells, over which hydraulic properties are averaged for fluid flow simulations. While continuum methods have the advantage of lower computational costs and the pos…

Radiation curing of carbon fibre composites

2014

Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides…

[Percutaneous vertebroplasty]

2003

Impacts of tailored, rehabilitation nursing care on functional ability and quality of life in hospitalized elderly patients after rib fractures

2021

Objectives: We aimed to analyze the effects of a tailored rehabilitation nursing care program on functional ability and quality of life in patients with conservative treatment for rib fractures. Design: Randomized controlled trial. Setting: Inpatient rehabilitation hospital. Subjects: Rib fracture patients treated conservatively were randomized into two groups (experimental and control group). Interventions: Patients in control group received Treatment as Usual (TAU) and patients included in experimental group received TAU and an added tailored rehabilitation nursing care program (RNT). Main measures: At baseline, and end of hospitalization treatment, the functional ability was assessed wit…

Fracture Toughness of PIR Foams Produced from Renewable Resources

2012

Rigid low-density closed-cell polyisocyanurate (PIR) foams are used primarily as a thermal insulation material. Traditionally, they are manufactured from constituents produced by petrochemical industry. Introducing renewable materials in PIR formulation brings definite economical and environmental benefits. Fracture toughness of PIR foams obtained from renewable resources (with the polyol system comprising up to 80% of rapeseed oil esters) and petrochemical PIR foams has been characterized experimentally, by compact tension tests, for mode I crack propagation along the rise direction of the foams.

Long-term results after operative treatment of femoral neck fractures with ceramic head prostheses.

2001

ABSTRACT From 1 985-1 990, a total of 277 elderly patients underwent hemiarthroplasty using a ceramic head prosthesis. Average patient age was 81.7 years. Of these, 77 patients were available for follow-up examination in 1993. A standardized score was calculated assessing activity, gait, and hip pain; the average score was 58 out of 78 possible points. Three patients had hip pain, and in 4 patients, radiographic examination revealed protrusio acetabuli. Two of 4 patients underwent revision surgery for replacement of the cup, leaving the stem in situ. Because of the small number of prosthetic-related complications, hemiarthroplasty using a ceramic head prosthesis is the recommended surgical …

Ganzkörper-Spiral-CT zur Primärdiagnostik polytraumatisierter Patienten unter Notfallbedingungen

1997

PURPOSE The aim of this study was to evaluate the role of a fast whole body helical CT scanner for primary diagnosis in trauma patients. METHODS 27 severely injured patients (9 women, 18 men; mean age 43 years) were first examined with a helical CT scanner allowing for digital radiograms up to a length of 1024 mm and continuous helical scans of up to 70 seconds (slice thickness 3 to 10 mm, pitch factor up to 2). The primary CT diagnosis was verified either by x-ray after the CT examination or during the subsequent days, by abdominal ultrasound, by additional CT scans in the following days, and by clinical follow-up. RESULTS CT showed all clinically relevant injuries of the head, spine, ches…

The Evaluation of Four Electronic Apex Locators in Teeth with Simulated Horizontal Oblique Root Fractures

2008

The accuracy of four electronic apex locators (EALs) to locate the apical limit in teeth with simulated horizontal oblique root fractures was investigated. A horizontal oblique incomplete root fracture was simulated on 20 freshly extracted maxillary anterior teeth by means of a notch made on the vestibular root plane 8 mm from the anatomic apex. The EALs investigated were the ProPex (Dentsply Maillefer, Ballaigues, Switzerland), the NovApex (Forum Technologies, Rishon Le-Zion, Israel), the Root ZX (J. Morita Corp, Kyoto, Japan), and the Elements Apex Locator (SybronEndo, Orange CA). The electronic measurements were compared with the real "working length." The accuracy obtained was of 80% (n…

Volar and dorsal mid-shaft forearm plating using DCP and LC-DCP: interference with the interosseous membrane and forearm-kinematics.

2010

Purpose To clarify if dorsal plate osteosynthesis of the forearm shaft is associated with impingement of the interosseous membrane (IOM) and if rotational kinematics of the forearm are influenced. Background Forearm fractures are treated by separate incisions. Osteosynthesis via one approach in proximal forearm fractures was associated with higher rates of synostosis. It has been claimed that this is due to IOM impingement. Materials and methods 16 forearms of fresh frozen cadavers were dissected until only radius, ulna and the IOM remained. To preserve physiological forearm rotation, the elbow joint, the distal radio-ulnar joint and the carpus remained intact. In group 1, LC-DC and DC plat…

Internal spring distribution for quasi brittle fracture via Symmetric Boundary Element Method

2009

Abstract In this paper the symmetric boundary element formulation is applied to the fracture mechanics problems for quasi brittle materials . The basic aim of the present work is the development and implementation of two discrete cohesive zone models using Symmetric Galerkin multi-zone Boundary Elements Method . The non-linearity at the process zone of the crack will be simulated through a discrete distribution of nodal springs whose generalized (or weighted) stiffnesses are obtainable by the cohesive forces and relative displacements modelling. This goal is reached coherently with the constitutive relation σ − Δ u that describes the interaction between mechanical and kinematical quantities…