| 1. |
- Young, William J., et al.
(författare)
-
Genetic analyses of the electrocardiographic QT interval and its components identify additional loci and pathways
- 2022
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The QT interval is a heritable electrocardiographic measure associated with arrhythmia risk when prolonged. Here, the authors used a series of genetic analyses to identify genetic loci, pathways, therapeutic targets, and relationships with cardiovascular disease. The QT interval is an electrocardiographic measure representing the sum of ventricular depolarization and repolarization, estimated by QRS duration and JT interval, respectively. QT interval abnormalities are associated with potentially fatal ventricular arrhythmia. Using genome-wide multi-ancestry analyses (>250,000 individuals) we identify 177, 156 and 121 independent loci for QT, JT and QRS, respectively, including a male-specific X-chromosome locus. Using gene-based rare-variant methods, we identify associations with Mendelian disease genes. Enrichments are observed in established pathways for QT and JT, and previously unreported genes indicated in insulin-receptor signalling and cardiac energy metabolism. In contrast for QRS, connective tissue components and processes for cell growth and extracellular matrix interactions are significantly enriched. We demonstrate polygenic risk score associations with atrial fibrillation, conduction disease and sudden cardiac death. Prioritization of druggable genes highlight potential therapeutic targets for arrhythmia. Together, these results substantially advance our understanding of the genetic architecture of ventricular depolarization and repolarization.
|
|
| 2. |
|
|
| 3. |
- Bravo, L, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 4. |
- Tabiri, S, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 5. |
- Barrera Rolla, Leandro, et al.
(författare)
-
Implementation of the forward-advancing wave expansion method (FWEM) for numerical solution of three dimensional large-scale sound propagation problems
- 2007
-
Ingår i: 36th International Congress and Exposition on Noise Control Engineering, INTER-NOISE. - 9781605603858 ; , s. 4796-4805
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper a “one-way” wave based field discretization method for solving the Helmholtz equation in large-scale problems is proposed and is referred to as the Forward Wave Expansion Method (FWEM). The FWEM is derived from a highly efficient discretization procedure based on the interpolation of wave functions known as the Wave Expansion Method (WEM) and computes the propagated sound field by means of an exclusively forward advancing solution. This technique does not require the inversion of large system matrices and thus enables the solution of large scale acoustic problems where backscatter is not of interest. A computationally light model is thus formulated which retains many advantages of WEM. Accurate results were obtained for a free field sound propagation benchmarking problem. The method was also implemented to successfully model some diffraction effects. The FWEM offers a simple, flexible and efficient discretization method to solve the Helmholtz equation for extensive domains with mesh densities as low as 3 nodes per wavelength. This makes the FWEM a promising method for long range sound propagation problems.
|
|
| 6. |
- Bharath, G., et al.
(författare)
-
Iterative solutions of the three-dimensional Helmholtz equation using the wave expansion method for high frequency acoustic scattering problems
- 2007
-
Ingår i: 36th International Congress and Exposition on Noise Control Engineering, INTER-NOISE. - 9781605603858 ; , s. 4788-4795
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Modelling sound propagation over large domains presents severe challenges with respect to computational requirements. In general, direct solutions of system equations resulting from the full field discretization of many three-dimensional problems of practical interest cannot be attempted. The present study investigates iterative solutions for solving a Three-Dimensional Helmholtz equation. The discretization of the Helmholtz equation is done by a Wave Based Finite Difference scheme known as the Wave Expansion Method (WEM). The WEM requires only 2-3 nodes per wavelength to obtain accurate solutions which offers a potential for major improvement in efficiency compares to conventional techniques such as the Finite Element/Finite Difference approaches which require around 8-10 nodes per wavelength. The solver employed here is the standard Bi-Conjugate Gradient Stabilized (Bi-CGSTAB) algorithm. Results are presented for high frequency acoustic scattering problems occurring in aircrafts. Investigations are also carried out to check the effectiveness of the standard preconditioning strategies such as the Incomplete LU decomposition with drop tolerance method. The influence of the scatterer is also studied in this paper.
|
|
| 7. |
- Cameron, Christopher John, 1980-
(författare)
-
Design of Multifunctional Body Panels for Conflicting Structural and Acoustic Requirements in Automotive Applications
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the past century, the automobile has become an integral part of society, with vastincreases in safety, refinement, and complexity, but most unfortunately in mass. Thetrend of increasing mass cannot be maintained in the face of increasingly stringentregulations on fuel consumption and emissions.The body of work within this thesis exists to help the vehicle industry to take a stepforward in producing vehicles for the future in a sustainable manner in terms of botheconomic and ecological costs. In particular, the fundamentally conflicting requirementsof low weight and high stiffness in a structure which should have good acousticperformance is addressed.An iterative five step design method based on the concepts of multifunctionality andmultidisciplinary engineering is proposed to address the problem, and explained witha case study.In the first step of the process, the necessary functional requirements of the systemare evaluated. Focus is placed on the overall system behavior and diverted from subproblems.For the case study presented, the functional requirements included: structuralstiffness for various loading scenarios, mass efficiency, acoustic absorption, vibrationaldamping, protecting from the elements, durability of the external surfaces,and elements of styling.In the second step of the process, the performance requirements of the system wereestablished. This involved a thorough literature survey to establish the state of theart, a rigorous testing program, and an assessment of numerical models and tools toevaluate the performance metrics.In the third step of the process, a concept to fulfil requirements is proposed. Here, amulti-layered, multi-functional panel using composite materials, and polymer foamswith varying structural and acoustic properties was proposed.In the fourth step of the process, a method of refinement of the concept is proposed.Numerical tools and parameterized models were used to optimize the three dimensionaltopology of the panel,material properties, and dimensions of the layers in a stepwisemanner to simultaneously address the structural and acoustic performance.In the fifth and final step of the process, the final result and effectiveness of the methodused to achieve it is examined. Both the tools used and the final result in itself shouldbe examined. In the case study the process is repeated several times with increasingdegrees of complexity and success in achieving the overall design objectives.In addition to the design method, the concept of a multifunctional body panel is definedand developed and a considerable body of knowledge and understanding is presented.Variations in core topology, materials used, stacking sequence of layers, effects ofperforations, and air gaps within the structure are examined and their effects on performanceare explored and discussed. The concept shows promise in reducing vehicleweight while maintaining the structural and acoustic performance necessary in the contextof sustainable vehicle development.
|
|
| 8. |
- Dehghan, Abbas, et al.
(författare)
-
Genome-Wide Association Study for Incident Myocardial Infarction and Coronary Heart Disease in Prospective Cohort Studies : The CHARGE Consortium
- 2016
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- Background Data are limited on genome-wide association studies (GWAS) for incident coronary heart disease (CHD). Moreover, it is not known whether genetic variants identified to date also associate with risk of CHD in a prospective setting. Methods We performed a two-stage GWAS analysis of incident myocardial infarction (MI) and CHD in a total of 64,297 individuals (including 3898 MI cases, 5465 CHD cases). SNPs that passed an arbitrary threshold of 5x10(-6) in Stage I were taken to Stage II for further discovery. Furthermore, in an analysis of prognosis, we studied whether known SNPs from former GWAS were associated with total mortality in individuals who experienced MI during follow-up. Results In Stage I 15 loci passed the threshold of 5x10(-6); 8 loci for MI and 8 loci for CHD, for which one locus overlapped and none were reported in previous GWAS meta-analyses. We took 60 SNPs representing these 15 loci to Stage II of discovery. Four SNPs near QKI showed nominally significant association with MI (p-value<8.8x10(-3)) and three exceeded the genome-wide significance threshold when Stage I and Stage II results were combined (top SNP rs6941513: p = 6.2x10(-9)). Despite excellent power, the 9p21 locus SNP (rs1333049) was only modestly associated with MI (HR = 1.09, p-value = 0.02) and marginally with CHD (HR = 1.06, p-value = 0.08). Among an inception cohort of those who experienced MI during follow-up, the risk allele of rs1333049 was associated with a decreased risk of subsequent mortality (HR = 0.90, p-value = 3.2x10(-3)). Conclusions QKI represents a novel locus that may serve as a predictor of incident CHD in prospective studies. The association of the 9p21 locus both with increased risk of first myocardial infarction and longer survival after MI highlights the importance of study design in investigating genetic determinants of complex disorders.
|
|
| 9. |
- Eicher, John D., et al.
(författare)
-
Platelet-Related Variants Identified by Exomechip Meta-analysis in 157,293 Individuals
- 2016
-
Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 99:1, s. 40-55
-
Tidskriftsartikel (refereegranskat)abstract
- Platelet production, maintenance, and clearance are tightly controlled processes indicative of platelets' important roles in hemostasis and thrombosis. Platelets are common targets for primary and secondary prevention of several conditions. They are monitored clinically by complete blood counts, specifically with measurements of platelet count (PLT) and mean platelet volume (MPV). Identifying genetic effects on PLT and MPV can provide mechanistic insights into platelet biology and their role in disease. Therefore, we formed the Blood Cell Consortium (BCX) to perform a large-scale meta-analysis of Exomechip association results for PLT and MPV in 157,293 and 57,617 individuals, respectively. Using the low-frequency/rare coding variant-enriched Exomechip genotyping array, we sought to identify genetic variants associated with PLT and MPV. In addition to confirming 47 known PLT and 20 known MPV associations, we identified 32 PLT and 18 MPV associations not previously observed in the literature across the allele frequency spectrum, including rare large effect (FCER1A), low-frequency (IQGAP2, MAP1A, LY75), and common(ZMIZ2, SMG6, PEAR1, ARFGAP3/PACSIN2) variants. Several variants associated with PLT/MPV(PEAR1, MRVI1, PTGES3) were also associated with platelet reactivity. In concurrent BCX analyses, there was overlap of platelet-associated variants with red (MAP1A, TMPRSS6, ZMIZ2) and white (PEAR1, ZMIZ2, LY75) blood cell traits, suggesting common regulatory pathways with shared genetic architecture among these hematopoietic lineages. Our large-scale Exomechip analyses identified previously undocumented associations with platelet traits and further indicate that several complex quantitative hematological, lipid, and cardiovascular traits share genetic factors.
|
|
| 10. |
- Ellinor, Patrick T., et al.
(författare)
-
Meta-analysis identifies six new susceptibility loci for atrial fibrillation
- 2012
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:6, s. 88-670
-
Tidskriftsartikel (refereegranskat)abstract
- Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death(1). We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 x 10(-8)). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
|
|
| 11. |
- Erzurumluoglu, A. Mesut, et al.
(författare)
-
Meta-analysis of up to 622,409 individuals identifies 40 novel smoking behaviour associated genetic loci
- 2020
-
Ingår i: Molecular Psychiatry. - : Nature Publishing Group. - 1359-4184 .- 1476-5578. ; 25:10, s. 2392-2409
-
Tidskriftsartikel (refereegranskat)abstract
- Smoking is a major heritable and modifiable risk factor for many diseases, including cancer, common respiratory disorders and cardiovascular diseases. Fourteen genetic loci have previously been associated with smoking behaviour-related traits. We tested up to 235,116 single nucleotide variants (SNVs) on the exome-array for association with smoking initiation, cigarettes per day, pack-years, and smoking cessation in a fixed effects meta-analysis of up to 61 studies (up to 346,813 participants). In a subset of 112,811 participants, a further one million SNVs were also genotyped and tested for association with the four smoking behaviour traits. SNV-trait associations with P < 5 × 10-8 in either analysis were taken forward for replication in up to 275,596 independent participants from UK Biobank. Lastly, a meta-analysis of the discovery and replication studies was performed. Sixteen SNVs were associated with at least one of the smoking behaviour traits (P < 5 × 10-8) in the discovery samples. Ten novel SNVs, including rs12616219 near TMEM182, were followed-up and five of them (rs462779 in REV3L, rs12780116 in CNNM2, rs1190736 in GPR101, rs11539157 in PJA1, and rs12616219 near TMEM182) replicated at a Bonferroni significance threshold (P < 4.5 × 10-3) with consistent direction of effect. A further 35 SNVs were associated with smoking behaviour traits in the discovery plus replication meta-analysis (up to 622,409 participants) including a rare SNV, rs150493199, in CCDC141 and two low-frequency SNVs in CEP350 and HDGFRP2. Functional follow-up implied that decreased expression of REV3L may lower the probability of smoking initiation. The novel loci will facilitate understanding the genetic aetiology of smoking behaviour and may lead to the identification of potential drug targets for smoking prevention and/or cessation.
|
|
| 12. |
- Guastavino, Rémi, 1974-
(författare)
-
Elastic and acoustic characterisation of porous layered system
- 2006
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For an accurate prediction of the low and medium frequency surface vibration and sound radiation behaviour of porous layered systems, there is a need to improve the means of estimating their elastic and acoustic properties. The underlying reasons for this are many and of varying origin, one prominent being a poor knowledge of the geometric anisotropy of the cell microstructure in the manufactured porous materials. Another one being, the characteristic feature of such materials i.e. that their density, elasticity and dissipative properties are highly dependent upon the manufacturing process techniques and settings used. In the case of free form moulding, the geometry of the cells and the dimensions of the struts are influenced by the rise and injection flow directions and also by the effect of gravity, elongating the cells. In addition the influence of the boundaries of the mould also introduces variations in the properties of the foam block produced. Despite these complications, the need to predict and, in the end, optimise the acoustic performance of these materials, either as isolated components or as part of a multi-layer arrangement, is growing. It is driven by the increasing demands for an acoustic performance in balance with the costs, a focus which serves to increase the need for modelling their behaviour in general and the above mentioned, inherent, anisotropy in particular. The current work is focussing on the experimental part of the characterisation of the material properties which is needed in order to correctly represent the anisotropy in numerical simulation models. A hybrid approach based on a combination of experimental deformation and strain field mapping, and physically based porous material acoustic Finite Element (FE) simulation modelling, is under development which ultimately will provide the anisotropic elastic coefficients and acoustic properties of the porous layered system. The first step, involving new testing methods, is discussed here and demonstrated for a soft foam. In addition investigations using laser vibrometers combined with finite element modelling of the Panphonics G1 multi-layered panel elements are also discussed. Variations in the mounting conditions, including globally acting restraints, are evaluated through dynamic measurements and acoustic interaction with the surrounding acoustic field. Results from investigations into different changes of the panel design parameters in order to improve the effectiveness in the low frequency range are presented.
|
|
| 13. |
- Larsson, Johan, et al.
(författare)
-
Concurrent sizing and topology optimization of lightweight sandwich structures with load bearing and wide-band frequency response constraints
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The design of lightweight sandwich structures with constraints the response to static and dynamic loads is investigated. A concurrent optimization of the face sheet thickness and core topology is used to minimize the structural mass of a sandwich beam with constraints on both the static load bearing properties and the average response to a time-harmonic load over a frequency band. The results show that the mass of the resulting structure is very dependent on how tight the dynamic constrain is if the frequency band covers the fundamental resonance frequency of the structure. If the frequency band of excitation covers the second resonance frequency or is between two resonance frequencies, lowering the dynamic response is much cheaper in terms of mass.
|
|
| 14. |
- Lindberg, Eskil, 1979-
(författare)
-
A Vibro-Acoustic Study of Vehicle Suspension Systems : Experimental and Mathematical Component Approaches
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of the present work is to study the vehicle suspension as a vibro-acoustic system of high complexity, consisting of many sub-systems with fundamentally different acoustical properties. In a parallel numerical and experimental modelling effort, important contributions to the understanding of its behaviour have been achieved. These findings are based on a balance between component investigations and global modelling of the complete system; they have been formulated for the transmission of both tyre-road excitation and friction-induced vibrations in the brake system.Initially an experimental study was conducted on a full vehicle test rig studying the broadband interior brake noise problem of, here named, roughness noise. The purpose of the study was twofold: first, to determine if the transmission from the source to the interior of the vehicle was structure-borne; second, to study the complexity of the suspension as a vibro-acoustic system. Parameters a_ecting the vibro-acoustic source were varied to gain understanding of the source mechanisms. This experimental study laid the foundation of the first part of this thesis (paper A) and provided the directions for the second part, the development of a mathematical modelling approach (paper B and C). In these two papers, methods for analysing the complex vibro-acoustic transfer of structure-borne sound in a vehicle suspension system were developed. The last part was then focussed on the wheel rim influence on the vibro-acoustic behaviour (paper D) of the suspension system. As a whole, the work clearly demonstrates that it is possible to conduct component studies of subsystems in the vehicle suspension system; and from these component studies it is possible draw conclusions that very well may avoid severe degradations in the interior noise of future vehicle generations.
|
|
| 15. |
- Lu, Yingchang, et al.
(författare)
-
New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
- 2016
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk.
|
|
| 16. |
- Lumbers, R. T., et al.
(författare)
-
The genomics of heart failure: design and rationale of the HERMES consortium
- 2021
-
Ingår i: Esc Heart Failure. - : Wiley. - 2055-5822. ; 8:6, s. 5531-5541
-
Tidskriftsartikel (refereegranskat)abstract
- Aims The HERMES (HEart failure Molecular Epidemiology for Therapeutic targets) consortium aims to identify the genomic and molecular basis of heart failure. Methods and results The consortium currently includes 51 studies from 11 countries, including 68 157 heart failure cases and 949 888 controls, with data on heart failure events and prognosis. All studies collected biological samples and performed genome-wide genotyping of common genetic variants. The enrolment of subjects into participating studies ranged from 1948 to the present day, and the median follow-up following heart failure diagnosis ranged from 2 to 116 months. Forty-nine of 51 individual studies enrolled participants of both sexes; in these studies, participants with heart failure were predominantly male (34-90%). The mean age at diagnosis or ascertainment across all studies ranged from 54 to 84 years. Based on the aggregate sample, we estimated 80% power to genetic variant associations with risk of heart failure with an odds ratio of >1.10 for common variants (allele frequency > 0.05) and >1.20 for low-frequency variants (allele frequency 0.01-0.05) at P < 5 x 10(-8) under an additive genetic model. Conclusions HERMES is a global collaboration aiming to (i) identify the genetic determinants of heart failure; (ii) generate insights into the causal pathways leading to heart failure and enable genetic approaches to target prioritization; and (iii) develop genomic tools for disease stratification and risk prediction.
|
|
| 17. |
- Mao, Huina, et al.
(författare)
-
Twist, tilt and stretch: From isometric Kelvin cells to anisotropic cellular materials
- 2020
-
Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 193
-
Tidskriftsartikel (refereegranskat)abstract
- Simple geometric distortions applied to the isometric Kelvin cell structures, (the tetrakaidecahedron), are shown to result in equivalent materials with anisotropic Hooke's tensors. The equivalent material models are estimated using a recently published inversion method where the 21 independent elastic constants of the Hooke's tensor are identified. In these cell geometries, some of the faces of the Kelvin cell have been twisted and/or tilted. Numerical experiments suggest that the equivalent material models of the distorted cells exhibit variations in compression, shearing, shear-compression and shear-shear coupling moduli, which are shown to be continuous functions of the degree of twist and tilt applied. When twist and tilt are combined, it is demonstrated that full anisotropy in the elastic properties may be generated. A rotational symmetry without symmetry planes, but having either a tetragonal or a monoclinic elastic symmetry is discussed. Four cell geometries, one isometric and three distorted, were manufactured using masked stereolithography 3D printing technology and measured in a laboratory compression set-up. Results from numerical simulations are compared to the experimental in terms of the compressive modulus.
|
|
| 18. |
- Ntalla, Ioanna, et al.
(författare)
-
Multi-ancestry GWAS of the electrocardiographic PR interval identifies 202 loci underlying cardiac conduction
- 2020
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N=293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease. On the electrocardiogram, the PR interval reflects conduction from the atria to ventricles and also serves as risk indicator of cardiovascular morbidity and mortality. Here, the authors perform genome-wide meta-analyses for PR interval in multiple ancestries and identify 141 previously unreported genetic loci.
|
|
| 19. |
- O'Reilly, Ciarán J., et al.
(författare)
-
A Lighthill based jet noise model for acoustic shielding prediction
- 2010
-
Ingår i: 17th International Congress on Sound and Vibration, ICSV17. - 9781617822551 ; , s. 558-565
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The majority of research on jet noise has considered isolated shear-flows and, as such, jet noise models based on Lighthill's acoustic analogy traditionally assume a free-space Green's function for propagation. In order to evaluate the reduction in jet noise attainable from proposed airframe shielding configurations, a jet noise model based on Lighthill's analogy is derived in this paper, which retains an explicit Green's function in the expression for the far-field spectral density. This Green's function may be evaluated to include the diffraction of the sound field about an acoustic shield. A preliminary comparison is made with the limited data available for shielded jets. In addition to facilitating the study of shielding configurations, isolated predictions made using this model compare favourably with isolated jet noise data.
|
|
| 20. |
- O'Reilly, Ciarán J., et al.
(författare)
-
An Assessment of Jet Noise Shielding Prediction Parameters
- 2010
-
Ingår i: 16th AIAA/CEAS Aeroacoustics Conference (31st AIAA Aeroacoustics Conference). - Reston, Virigina : American Institute of Aeronautics and Astronautics.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- On-going research and development by the European aeronautical community towards the reduction of civil aircraft noise has been investigating the shielding of engine noise sources by airframe components (wing/fuselage/empennage). In order to assess the noise reduction benefits attainable from such novel configurations, it is necessary to develop appropriate acoustic evaluation tools. In this paper, the Tam-Auriault jet noise model, with a RANS solution input, in conjunction with a Fresnel-Kirchhoff diffraction method is used to make isolated and shielded far-field jet noise predictions. This methodology is employed as a sensitivity analysis tool in order to establish the relative importance of the source location, spatial extent and directivity in jet noise shielding predictions.Although, the predicted isolated jet directivity agrees well with far-field empirical values, the predicted levels of shielding are much larger than those observed in the available data. A preliminary investigation into the possible causes of this discrepancy indicates that the introduction of the shield adjacent to the jet may result in the generation of new ‘installation sources’, which limit the shielding achievable in practical applications.
|
|
| 21. |
- O'Reilly, Ciarán J., et al.
(författare)
-
An investigation into the effects of engine body reflections and flow refraction on jet noise shielding predictions
- 2007
-
Ingår i: 36th International Congress and Exhibition on Noise Control Engineering, INTER-NOISE. - 9781605603858 ; , s. 733-742
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Airframe acoustic shielding predictions, using simple point sources located over an isolated wing, tend to over-predict shielding effects, when compared with full-model test data. The study presented in this paper investigates the effects of the inclusion of the engine body and the jet flow on shielding predictions. A wave expansion method (WEM), is used to efficiently model the sound propagation, in a small domain which includes the wing and engine body. In this model the jet is still represented as point sources. A 2d model is examined, in which the mean jet flow has been included. The point source locations and strengths are determined using a RANS solution of a hot coaxial jet and Goldstein's interpretation of the acoustic analogy. The near-field WEM results are then propagated to the far-field using the Helmholtz-Kirchhoff integral equation, which assumes a uniform flow external to the Kirchhoff surface. Results presented here are very encouraging as they clearly indicate that with the inclusion of engine body reflections, and the refractive effects of the jet flow, predicted shielding values are much more consistent with observed levels both in terms of magnitude and variation over observation angle.
|
|
| 22. |
- O'Reilly, Ciarán J., et al.
(författare)
-
Investigation of a jet-noise-shielding methodology
- 2015
-
Ingår i: AIAA Journal. - : American Institute of Aeronautics and Astronautics. - 0001-1452 .- 1533-385X. ; 53:11, s. 3286-3296
-
Tidskriftsartikel (refereegranskat)abstract
- Ongoing research toward the reduction of environmental noise from aircraft is investigating the possible shielding of engine-noise sources by novel airframe configurations. To assess the noise-reduction benefits attainable from such configurations, it is necessary to develop appropriate acoustic evaluation tools. In this paper, a jet-noise-shielding- prediction methodology is described. The Tam–Auriault (“Jet Mixing Noise from Fine-Scale Turbulence,” AIAA Journal, Vol. 37, No. 2, 1999, pp. 145–153) jet-noise model with a Reynolds-averaged Navier–Stokes solution input, together with a Fresnel–Kirchhoff diffraction method (Fundamentals of Physical Acoustics, Wiley-Interscience, New York, 2000, pp. 472–494), is used to make isolated and shielded far-field jet-noise predictions. This methodology is employed as a sensitivity-analysis tool to establish the relative importance of the source location, spatial extent, and directivity in jet-noise-shielding predictions. Predictions have been made for a shielded single-stream Mach 0.9 jet, and compared with experimental data. Good qualitative agreement is observed, and the disagreement in the shielding levels is most likely due to underestimation of the source axial extent by the jet-noise model.
|
|
| 23. |
- O'Reilly, Ciarán J., et al.
(författare)
-
Jet noise modelling for shielding calculations using RANS solution source localisation and WEM propagation
- 2006
-
Ingår i: 22nd International Conference on Noise and Vibration Engineering, ISMA. - : Leuven University Press. - 9789073802834 ; , s. 667-676
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, a method to determine the jet noise source input for shielding calculations is described. The method involves three steps - localisation, propagation and simplification. Firstly, for the frequency of interest, a small localised source region is determined, using Goldstein-Rosenbaum's acoustic model, with a numerical RANS solution providing local flow properties. A number of distinct incoherent noise sources may be located in this region, using the turbulence length scales. In the second step, each source is propagated out through the jet flow using the wave expansion method (WEM) to solve the Helmholtz equation, with local Mach values acquired from the RANS solution. The third step is to define a Kirchhoff surface outside the jet flow, from which the sound may be propagated further by simply using the Helmholtz-Kirchhoff integral, which can account for any mean flow present. Although the method is quite crude, it is relatively robust as it is a shielding factor or ratio, rather than an absolute value, which is of interest in design evaluation. Preliminary results, presented in this paper, provide encouragement that this new three-step jet noise source modelling method can be used to provide a source input for use in airframe shielding calculations, that is equivalent - in terms of source frequency, distribution and directivity - to the noise produced by a jet flow.
|
|
| 24. |
- O'Reilly, Ciarán J., et al.
(författare)
-
Jet noise modelling for shielding calculations using RANS source localisation and WEM propagation
- 2006
-
Ingår i: 8th International Symposium Transport Noise and Vibration.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, a method to determine the jet noise source input for shielding calculations is described. The method involves three steps – localisation, propagation and simplification. Firstly, for the frequency of interest, a small, localised source region is determined, using Goldstein-Rosenbaums’ acoustic model, with a numerical RANS solution providing local flow properties. A number of distinct incoherent noise sources may be located in this region, using the turbulence length scales. In the second step, each source is propagated out through the jet flow using the wave expansion method (WEM) to solve the Helmholtz equation, with local Mach values acquired from the RANS solution. The third step is to define a Kirchhoff surface outside the jet flow, from which, the sound may be propagated further by simply using the Helmholtz-Kirchhoff integral equation, which, can account for any mean flow present. This method is relatively robust, as it is a shielding factor or ratio, rather than an absolute value, which is of interest in acoustic design evaluation. Preliminary results, presented in this paper, provide encouragement that this new three-step jet noise source modelling method can be used to provide a source input for use in airframe shielding calculations, that is equivalent – in terms of source frequency, distribution and directivity – to the noise produced by a jet flow.
|
|
| 25. |
- O'Reilly, Ciarán J., et al.
(författare)
-
Jet noise shielding : Mean flow convection and refraction effects on jet noise source propagation
- 2008
-
Ingår i: 23rd International Conference on Noise and Vibration Engineering, ISMA. - : Leuven University Press. - 9789073802865 ; , s. 525-533
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Positioning aircraft engines on the rear of the fuselage above a U-shaped empennage, is an aircraft configuration, which could possibly reduce the engine noise emitted towards the ground during take-off and approach. In order to acoustically assess the shielding effect attained from such a configuration, the complicated physical noise sources must, firstly, be represented in a manner appropriate for input into propagation / shielding prediction methods. In this paper, the development of an innovative methodology for providing such a source for jet noise is described. Convecting point sources are located using Lighthill's analogy with a Reynolds-Averaged Navier Stokes (RANS) solution to provide mean flow properties. The refractive effect of the mean jet flow on sound propagation is determined using a Wave Expansion Method (WEM) to efficiently numerically propagate monopole noise sources in a small domain, which includes the sheared jet flow. This near-field WEM result is then propagated to the far-field using the Helmholtz-Kirchhoff integral equation, assuming a uniform flow external to the Kirchhoff surface. The refractive flow effect on omnidirectional sources is superimposed on the convecting sources. These directional point sources may be used as a sound source input for shielding prediction methods. In this present study, jet noise sources have been created for a range of frequencies. The isolated sound pressure level and the shielding effect, resultant from separating these sources from an arc of receivers, with a flat plate, have been evaluated and results compared with test data. Results presented here are very encouraging, as they clearly indicate that with the inclusion of both the convective and the refractive effects of the jet flow on the propagation of point sources, simple jet noise sources may be defined for use in shielding prediction methods, however, using the present approximations, the predicted sound pressure levels are greater than the measured values at downstream receiver angles.
|
|
| 26. |
- Rasam, Amin, et al.
(författare)
-
Aerodynamic noise prediction for a wind turbine using numerical flow simulations and semi-empirical modelling approaches
- 2016
-
Ingår i: 22nd AIAA/CEAS Aeroacoustics Conference. - Reston, Virginia : American Institute of Aeronautics and Astronautics.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, aerodynamic and aero-acoustic simulations are performed for a small horizontal axis wind turbine, suitable for the integration of wind energy in urban and peri-urban areas. Detached-eddy simulation (DES) of compressible flow is performed to compute the flow field over the wind turbine. The far-field noise is computed using the Ffowcs - Williams and Hawkings acoustic analogy. Furthermore, the blade element momentum theory is used with a semi-empirical acoustic modeling approach to predict the wind turbine noise. The acoustic modeling approach is based on a semi-empirical formulation for airfoil self noise and an analytic formulation for inflow noise.
|
|
| 27. |
- Rumpler, Romain, 1983-
(författare)
-
Efficient Finite Element Approach for Structural-Acoustic Applications including 3D modelling of Sound Absorbing Porous Materials
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the context of interior noise reduction, the present work aims at proposing Finite Element (FE) solution strategies for interior structural-acoustic applications including 3D modelling of homogeneous and isotropic poroelastic materials, under timeharmonic excitations, and in the low frequency range. A model based on the Biot-Allard theory is used for the poroelastic materials, which is known to be very costly in terms of computational resources. Reduced models offer the possibility to enhance the resolution of such complex problems. However, their applicability to porous materials remained to be demonstrated.First, this thesis presents FE resolutions of poro-elasto-acoustic coupled problems using modal-based approaches both for the acoustic and porous domains. The original modal approach proposed for porous media, together with a dedicated mode selection and truncation procedure, are validated on 1D to 3D applications.In a second part, modal-reduced models are combined with a Padé approximants reconstruction scheme in order to further improve the efficiency.A concluding chapter presents a comparison and a combination of the proposed methods on a 3D academic application, showing promising performances. Conclusions are then drawn to provide indications for future research and tests to be conducted in order to further enhance the methodologies proposed in this thesis.
|
|
| 28. |
|
|
| 29. |
- Shah, S, et al.
(författare)
-
Genome-wide association and Mendelian randomisation analysis provide insights into the pathogenesis of heart failure
- 2020
-
Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1, s. 163-
-
Tidskriftsartikel (refereegranskat)abstract
- Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies.
|
|
| 30. |
- Soranzo, Nicole, et al.
(författare)
-
A genome-wide meta-analysis identifies 22 loci associated with eight hematological parameters in the HaemGen consortium
- 2009
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:11, s. 38-1182
-
Tidskriftsartikel (refereegranskat)abstract
- The number and volume of cells in the blood affect a wide range of disorders including cancer and cardiovascular, metabolic, infectious and immune conditions. We consider here the genetic variation in eight clinically relevant hematological parameters, including hemoglobin levels, red and white blood cell counts and platelet counts and volume. We describe common variants within 22 genetic loci reproducibly associated with these hematological parameters in 13,943 samples from six European population-based studies, including 6 associated with red blood cell parameters, 15 associated with platelet parameters and 1 associated with total white blood cell count. We further identified a long-range haplotype at 12q24 associated with coronary artery disease and myocardial infarction in 9,479 cases and 10,527 controls. We show that this haplotype demonstrates extensive disease pleiotropy, as it contains known risk loci for type 1 diabetes, hypertension and celiac disease and has been spread by a selective sweep specific to European and geographically nearby populations.
|
|
| 31. |
- Truche, Paul, et al.
(författare)
-
Association between government policy and delays in emergent and elective surgical care during the COVID-19 pandemic in Brazil : a modeling study
- 2021
-
Ingår i: The Lancet Regional Health - Americas. - : Elsevier. - 2667-193X.
-
Tidskriftsartikel (refereegranskat)abstract
- Background:The impact of public health policy to reduce the spread of COVID-19 on access to surgical care is poorly defined. We aim to quantify the surgical backlog during the COVID-19 pandemic in the Brazilian public health system and determine the relationship between state-level policy response and the degree of state-level delays in public surgical care.Methods:Monthly estimates of surgical procedures performed per state from January 2016 to December 2020 were obtained from Brazil's Unified Health System Informatics Department. Forecasting models using historical surgical volume data before March 2020 (first reported COVID-19 case) were constructed to predict expected monthly operations from March through December 2020. Total, emergency, and elective surgical monthly backlogs were calculated by comparing reported volume to forecasted volume. Linear mixed effects models were used to model the relationship between public surgical delivery and two measures of health policy response: the COVID-19 Stringency Index (SI) and the Containment & Health Index (CHI) by state.Findings:Between March and December 2020, the total surgical backlog included 1,119,433 (95% Confidence Interval 762,663–1,523,995) total operations, 161,321 (95%CI 37,468–395,478) emergent operations, and 928,758 (95%CI 675,202–1,208,769) elective operations. Increased SI and CHI scores were associated with reductions in emergent surgical delays but increases in elective surgical backlogs. The maximum government stringency (score = 100) reduced emergency delays to nearly zero but tripled the elective surgical backlog.Interpretation:Strong health policy efforts to contain COVID-19 ensure minimal reductions in delivery of emergent surgery, but dramatically increase elective backlogs. Additional coordinated government efforts will be necessary to specifically address the increased elective backlogs that accompany stringent responses.
|
|
| 32. |
- Vasan, Ramachandran S, et al.
(författare)
-
Genetic variants associated with cardiac structure and function : a meta-analysis and replication of genome-wide association data
- 2009
-
Ingår i: Journal of the American Medical Association (JAMA). - : American Medical Association (AMA). - 0098-7484 .- 1538-3598. ; 302:2, s. 168-178
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Echocardiographic measures of left ventricular (LV) structure and function are heritable phenotypes of cardiovascular disease. OBJECTIVE: To identify common genetic variants associated with cardiac structure and function by conducting a meta-analysis of genome-wide association data in 5 population-based cohort studies (stage 1) with replication (stage 2) in 2 other community-based samples. DESIGN, SETTING, AND PARTICIPANTS: Within each of 5 community-based cohorts comprising the EchoGen consortium (stage 1; n = 12 612 individuals of European ancestry; 55% women, aged 26-95 years; examinations between 1978-2008), we estimated the association between approximately 2.5 million single-nucleotide polymorphisms (SNPs; imputed to the HapMap CEU panel) and echocardiographic traits. In stage 2, SNPs significantly associated with traits in stage 1 were tested for association in 2 other cohorts (n = 4094 people of European ancestry). Using a prespecified P value threshold of 5 x 10(-7) to indicate genome-wide significance, we performed an inverse variance-weighted fixed-effects meta-analysis of genome-wide association data from each cohort. MAIN OUTCOME MEASURES: Echocardiographic traits: LV mass, internal dimensions, wall thickness, systolic dysfunction, aortic root, and left atrial size. RESULTS: In stage 1, 16 genetic loci were associated with 5 echocardiographic traits: 1 each with LV internal dimensions and systolic dysfunction, 3 each with LV mass and wall thickness, and 8 with aortic root size. In stage 2, 5 loci replicated (6q22 locus associated with LV diastolic dimensions, explaining <1% of trait variance; 5q23, 12p12, 12q14, and 17p13 associated with aortic root size, explaining 1%-3% of trait variance). CONCLUSIONS: We identified 5 genetic loci harboring common variants that were associated with variation in LV diastolic dimensions and aortic root size, but such findings explained a very small proportion of variance. Further studies are required to replicate these findings, identify the causal variants at or near these loci, characterize their functional significance, and determine whether they are related to overt cardiovascular disease.
|
|
| 33. |
- Zieliński, Tomasz G., et al.
(författare)
-
Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies : Round robin study
- 2020
-
Ingår i: Additive Manufacturing. - : Elsevier B.V.. - 2214-8604 .- 2214-7810. ; 36
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work is to check if additive manufacturing technologies are suitable for reproducing porous samples designed for sound absorption. The work is an inter-laboratory test, in which the production of samples and their acoustic measurements are carried out independently by different laboratories, sharing only the same geometry codes describing agreed periodic cellular designs. Different additive manufacturing technologies and equipment are used to make samples. Although most of the results obtained from measurements performed on samples with the same cellular design are very close, it is shown that some discrepancies are due to shape and surface imperfections, or microporosity, induced by the manufacturing process. The proposed periodic cellular designs can be easily reproduced and are suitable for further benchmarking of additive manufacturing techniques for rapid prototyping of acoustic materials and metamaterials.
|
|
| 34. |
- Glasbey, JC, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 35. |
- Niemi, MEK, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 36. |
|
|
