Search results

In the context of range-independent solid media, we propose a well-conditioned dynamic stiffness matrix for an elastic layer sitting over an elastic half-space. This formulation overcomes the well-known problem of numerical ill-conditioning when solving the system of equations for deep-layered strata. The methodology involves the exact solutions of transformed ordinary differential equations in th

In the literature, expressions can be found for the mode shape functions of uniform Euler-Bernoulli beams. However, these expressions permit the evaluation of only the first 12 modes or so due to numerical issues associated with the evaluation of near field waves that increase exponentially with frequency. To overcome this problem, approximate expressions have been developed that avoid the evaluat

This paper describes an original numerical prediction technique developed for the analysis of coupled vibro-acoustic problems in fluid waveguides. Specifically it is a wave-based method that adopts a spectral element approach. Unlike the conventional element-based methods, this technique uses wave functions that satisfy the governing equations to describe the dynamic variables exactly. One advanta

Balancing a rotating machine is a vital step towards ensuring it will operate reliably and safely. To achieve this condition monitoring is an important aspect for early faulty detection and it can also result in the improvement of the operational continuity and equipment safety. Imbalance itself, is a common problem in rotating machinery and it can lead to poor or even dangerous vibration levels.

This article presents an innovative application of the frequency domain decomposition method based on an acoustic and vibration response. Frequency domain decomposition method has been frequently used for operational modal analysis testing in the last decade to identify modal parameters for in-situ case studies. For these studies, the outputs of the vibration response through accelerometers have b

Over many years, scientists and engineers have developed a broad variety of mathematical formulations to investigate the propagation and interactions with flow of flow-induced noise in early-stage of product design and development. Beside established theories such as the linearized Euler equations (LEE), the linearized Navier–Stokes equations (LNSE) and the acoustic perturbation equations (APE) wh

There are well-known expressions for natural frequencies and mode shapes of a Euler-Bernoulli beam which has classical boundary conditions, such as free, fixed, and pinned. There are also expressions for particular boundary conditions, such as attached springs and masses. Surprisingly, however, there is not a method to calculate the natural frequencies and mode shapes for a Euler–Bernoulli beam wh

The use of a single vertical screen to obstruct the propagation of noise from source to receiver over hard and soft flat ground is well known. However, In addition to considerations of acoustical efficiency, the design of road traffic noise barriers depends on many other factors. Site conditions, planning restraints and visual considerations will affect the final selected design, as will engineeri

Who benefits from the ignorance of others? We address this question from the point of view of a policy maker who can induce some ignorance into a system of agents competing for resources. Evolutionary game theory shows that when unconditional cooperators or ignorant agents compete with defectors in two-strategy settings, unconditional cooperators get exploited and are rendered extinct. In contrast

Computational social sciences (CSS) refer to computer-enabled investigations of human behaviour and social interaction. They include three main components - (i) computational modelling and social simulation, (ii) the analysis of digital traces of online interactions, (iii) virtual labs and online experiments - and allow researchers to perform studies that were even hard to imagine a few decades ag

Collaborations based on academic–practitioner interactions are not always as straightforward as presented in commonplace transdisciplinary theory. This chapter provides the most important insights from past and ongoing work from a sustainability project that uses the ‘Research Forum’ (RF) as a new a means of co-producing transdisciplinary knowledge. The findings center on four of the most common m

In the present paper, computational auralizations of a single pass-by of a passenger car and passenger train are investigated. Auralization of future traffic noise scenarios would be a valuable tool for city planners, noise consultants and decision makers, since it would make it possible to evaluate various noise mitigation solutions already at the planning stage. The main goal of the Swedish mult

Non-invasive imaging biomarkers (IBs) are warranted to enable improved diagnostics and follow-up monitoring of interstitial lung disease (ILD) including drug-induced ILD (DIILD). Of special interest are IB, which can characterize and differentiate acute inflammation from fibrosis. The aim of the present study was to evaluate a PET-tracer specific for Collagen-I, combined with multi-echo MRI, in a

Introduction: Fast-track referral pathways for patients with nonspecific, serious symptoms have been implemented in several countries. Our objective was to analyze time intervals in the diagnostic routes of patients diagnosed with cancer at Sweden’s first Diagnostic Center (DC) for nonspecific symptoms and compare with time intervals of matched control patients. Methods: Adult patients with nonspe

Aim: Students with hearing loss (HL) often fall behind hearing peers in complex language tasks such as narrative writing. This study explored the effects of school grade, gender, cognitive and linguistic predisposition and audiological factors on narrative text quality in this target group.Method: Eleven students with HL in Grades 5–6 and 7–8 (age 12–15) who took part in a writing intervention wro

Aortic Z-score (Z-score) is utilized in clinical trials to monitor the effect of medications on aortic dilation rate in Marfan (MFS) patients. Z-scores are reported in relation to body surface area and therefore are a function of height and weight. However, an information void exists regarding natural, non-pharmacological changes in Z-scores as children age. We had concerns that Z-score decrease a