Statistical estimation of trailing edge noise from finite wall-mounted airfoils

The 2016 Joint Conference of The Australian Acoustical Society and The Acoustical Society of New Zealand. Acoustics2016 - The Second Australasian Acoustical Societies ConferenceIt is important to be able to accurately model the flow and noise generated by finite wall-mounted airfoil flows because of the many engineering applications in which these flows occur. One method for predicting turbulent trailing edge noise is the Reynolds-averaged Navier-Stokes based statistical noise model (RSNM) of Doolan et al. (Proceedings of 20th International Congress on Acoustics, ICA 2010). The RSNM method has previously been used successfully on a range of two-dimensional geometry-flow cases. In this paper a new turbulent velocity cross-spectrum model and improved implementation are proposed to allow the RSNM method to be used to effectively and efficiently predict turbulent trailing edge noise from more complex three-dimensional cases. Reynolds-averaged Navier-Stokes (RANS) simulations of a series of wing-in-junction cases are used in combination with the developed acoustic model to predict the far-field noise and compared against experimental noise measurements.Jesse Coombs, Con Doolan, Anthony Zander, Danielle Moreau and Laura Brook

Acoustic absorption behaviour of a tall carbon nanotube forest

Previous investigations have shown that a 3-mm-high carbon nanotube (CNT) forest has an acoustic absorption coefficient of about 5-10% within the frequency range 125 Hz-4 kHz, which is above that of conventional acoustic materials on a per-mass basis. It was hypothesised that a CNT array of greater height, lower density, and with a non-uniform arrangement of the nanotubes could enhance the amount of acoustic absorption. In order to investigate this hypothesis, an impedance tube test was conducted to measure the acoustic absorption coefficient of a relatively tall 6-mm CNT forest. The results indicate that a greater length and lower density of CNTs may improve the absorption performance of CNT-based acoustic absorbers. Analyses of the results showed anomalies in the measured acoustic absorption coefficient compared with previous investigations. Theoretical analyses were performed based on classical models of acoustic absorption to explain the anomalies. This study describes the factors that may affect the acoustic absorption behaviour of nanomaterials.M. Ayub, A. C. Zander, C. Q. Howard, B. S. Cazzolato, D. M. Huang, N. T. Alvarez, and V. N. Shano

Multi-Qubit Systems: Highly Entangled States and Entanglement Distribution

A comparison is made of various searching procedures, based upon different entanglement measures or entanglement indicators, for highly entangled multi-qubits states. In particular, our present results are compared with those recently reported by Brown et al. [J. Phys. A: Math. Gen. 38 (2005) 1119]. The statistical distribution of entanglement values for the aforementioned multi-qubit systems is also explored.Comment: 24 pages, 3 figure

Relativistic Klein-Gordon charge effects by information-theoretic measures

The charge spreading of ground and excited states of Klein-Gordon particles moving in a Coulomb potential is quantitatively analyzed by means of the ordinary moments and the Heisenberg measure as well as by use of the most relevant information-theoretic measures of global (Shannon entropic power) and local (Fisher's information) types. The dependence of these complementary quantities on the nuclear charge Z and the quantum numbers characterizing the physical states is carefully discussed. The comparison of the relativistic Klein-Gordon and non-relativistic Schrodinger values is made. The non-relativistic limits at large principal quantum number n and for small values of Z are also reached.Comment: Accepted in New Journal of Physic

Decoding human mental states by whole-head EEG+fNIRS during category fluency task performance

Objective: Concurrent scalp electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS), which we refer to as EEG+fNIRS, promises greater accuracy than the individual modalities while remaining nearly as convenient as EEG. We sought to quantify the hybrid system's ability to decode mental states and compare it with unimodal systems. Approach: We recorded from healthy volunteers taking the category fluency test and applied machine learning techniques to the data. Main results: EEG+fNIRS's decoding accuracy was greater than that of its subsystems, partly due to the new type of neurovascular features made available by hybrid data. Significance: Availability of an accurate and practical decoding method has potential implications for medical diagnosis, brain-computer interface design, and neuroergonomics

Feature Lines for Illustrating Medical Surface Models: Mathematical Background and Survey

This paper provides a tutorial and survey for a specific kind of illustrative visualization technique: feature lines. We examine different feature line methods. For this, we provide the differential geometry behind these concepts and adapt this mathematical field to the discrete differential geometry. All discrete differential geometry terms are explained for triangulated surface meshes. These utilities serve as basis for the feature line methods. We provide the reader with all knowledge to re-implement every feature line method. Furthermore, we summarize the methods and suggest a guideline for which kind of surface which feature line algorithm is best suited. Our work is motivated by, but not restricted to, medical and biological surface models.Comment: 33 page

Molecular dynamics simulations of sound wave propagation in a gas and thermo-acoustic effects on a carbon nanotube

Published: 19 January 2016Molecular dynamics (MD) simulations have been performed to study sound wave propagation in a simple monatomic gas (argon) and the thermo-acoustic effects on a single walled carbon nanotube (CNT). The objective of this study was to understand the acoustic behavior of CNTs in the presence of acoustic waves propagating in gaseous media. A plane sound wave was generated within a rectangular domain by oscillating a solid wall comprising Lennard-Jones (LJ) atoms with the same intermolecular potential as the gas molecules. A CNT was aligned parallel to the direction of the flow at the wall at the opposite end of the domain. Interatomic interactions in the CNT were modeled using the REBO potential. The behavior of the sound wave propagation in argon gas without the CNT was validated by comparison with a previous study. The simulation results show that the thermo-acoustic behavior of CNTs can be simulated accurately using MD and that large-scale MD can be performed in the ultrasonic frequency range. This investigation will contribute to an improved understanding of the acoustic absorption mechanism of these nanoscopic fibers.Md Ayub, Anthony C. Zander, Carl Q. Howard, David M. Huang, Benjamin S. Cazzolat

Agricultural land use changes – a scenario-based sustainability impact assessment for Brandenburg, Germany

AbstractDecisions for agricultural management are taken at farm scale. However, such decisions may well impact upon regional sustainability. Two of the likely agricultural management responses to future challenges are extended use of irrigation and increased production of energy crops. The drivers for these are high commodity prices and subsidy policies for renewable energy. However, the impacts of these responses upon regional sustainability are unknown. Thus, we conducted integrated impact assessments for agricultural intensification scenarios in the federal state of Brandenburg, Germany, for 2025. One Irrigation scenario and one Energy scenario were contrasted with the Business As Usual (BAU) scenario. We applied nine indicators to analyze the economic, social and environmental effects at the regional, in this case district scale, which is the smallest administrative unit in Brandenburg. Assessment results were discussed in a stakeholder workshop involving 16 experts from the state government.The simulated area shares of silage maize for fodder and energy were 29%, 37% and 49% for the BAU, Irrigation, and Energy scenarios, respectively. The Energy scenario increased bio-electricity production to 41% of the demand of Brandenburg, and it resulted in CO2 savings of up to 3.5milliontons. However, it resulted in loss of biodiversity, loss of landscape scenery, increased soil erosion risk, and increased area demand for water protection requirements. The Irrigation scenario led to yield increases of 7% (rapeseed), 18% (wheat, sugar beet), and 40% (maize) compared to the BAU scenario. It also reduced the year-to-year yield variability. Water demand for irrigation was found to be in conflict with other water uses for two of the 14 districts. Spatial differentiation of scenario impacts showed that districts with medium to low yield potentials were more affected by negative impacts than districts with high yield potentials.In this first comprehensive sustainability impact assessment of agricultural intensification scenarios at regional level, we showed that a considerable potential for agricultural intensification exists. The intensification is accompanied by adverse environmental and socio-economic impacts. The novelty lies in the multiscale integration of comprehensive, agricultural management simulations with regional level impact assessment, which was achieved with the adequate use of indicators. It provided relevant evidence for policy decision making. Stakeholders appreciated the integrative approach of the assessment, which substantiated ongoing discussions among the government bodies. The assessment approach and the Brandenburg case study may stay exemplary for other regions in the world where similar economic and policy driving forces are likely to lead to agricultural intensification

Current status and updated recommendations for diagnosis and treatment of plasma cell myeloma in Switzerland

The availability of drugs such as thalidomide, bortezomib and lenalidomide changed the landscape in myeloma treatment and has extended the median survival up to 10 years with a substantial improvement in quality of life. This development prompted a Swiss expert panel to re-evaluate the current status and formulate updated clinical recommendations for the diagnosis and treatment of plasma cell myeloma. These recommendations should help clinicians in their decision making to achieve the best outcome based on currently available data