bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ genetic association for serotiny, a fire‐related trait, in Mediterranean maritime pine (Pinus pinaster)
Authors: Budde Katharina B. , Heuertz Myriam , Hernández‐Serrano Ana , Pausas Juli G. , Vendramin Giovanni G. , Verdú Miguel , González‐Martínez Santiago C.
Published: September 2013

Wildfire is a major ecological driver of plant evolution. Understanding the genetic basis of plant adaptation to wildfire is crucial, because impending climate change will involve fire regime changes worldwide. We studied the molecular genetic basis of serotiny, a fire‐related trait, in Mediterranean maritime pine using association genetics.

A single nucleotide polymorphism (SNP) set was used to identify genotype : phenotype associations in situ in an unstructured natural population of maritime pine (eastern Iberian Peninsula) under a mixed‐effects model framework. RR‐BLUP was used to build predictive models for serotiny in this region. Model prediction power outside the focal region was tested using independent range‐wide serotiny data.

Seventeen SNPs were potentially associated with serotiny, explaining approximately 29% of the trait phenotypic variation in the eastern Iberian Peninsula. Similar prediction power was found for nearby geographical regions from the same maternal lineage, but not for other genetic lineages.

Association genetics for ecologically relevant traits evaluated in situ is an attractive approach for forest trees provided that traits are under strong genetic control and populations are unstructured, with large phenotypic variability. This will help to extend the research focus to ecological keystone non‐model species in their natural environments, where polymorphisms acquired their adaptive value.
Medical Innovations: Their Diffusion, Adoption, and Critical Interrogation
Authors: Blume Stuart S.
Published: September 2013

The 1950s and 1960s were a ‘golden age’ of medical progress: an era of high expectations, widespread faith, and life‐saving innovations. In the 1970s, as it gradually became clear that medicine's technological advance also contributed to the rising costs of health care, policy makers began to question the ways in which new technologies diffused. Sociologists soon found that professional and institutional interests, the search for competitive advantage, and processes of ‘institutional isomorphism’ played major roles. By the end of the millennium, as a result of growing patient (and ‘health care consumer’) activism, and of globalization, the context in which new technologies were developed, introduced, and used had become politicized, and technologies had become more heterogeneous. The patient perspective offered a new vantage point from which to study medical technology in use, and one which fitted many sociologists' normative and methodological commitments. Many recent sociological studies highlight failures, contradictions, and the (often concealed) interests involved in the promotion of new drugs and other medical technologies. However, resources for studies aligned with dominant interests, perspectives, and claims are more readily available.
Biological Pre‐emption: “Race”, Class, and Genomics
Authors: Williams Johnny E.
Published: September 2013

Genomics is a complex field of study involving researchers and practitioners immersed in the social milieu from which their genetic theories and comprehensions in part emerge. Genomic researchers' embeddedness in social formations with distinct ideologies predisposes them to construct hypotheses about genetics with value‐laden assumptions. Given genomics' inseparability from social influences this article explores how its use with marginalized groups has eugenic implications. Several important links between eugenics and genomics are identified suggesting eugenic implications in genomics.
Introduction to Special Issue: Bound to be peaceful? The changing approach of Western European small states to peace
Authors: Goetschel Laurent
Published: September 2013

Despite a changed international political context in the post‐Cold War period, Western European small states remain firmly engaged in peace policy. One would be tempted to describe them as “natural born” peacemakers. This article shows a different approach to small states' peace policies. Using a typology from the literature on the role of norms and ideas, it argues that the type of peace engagement followed by small states has changed considerably during recent decades. More precisely, a shift has occurred in their peace policies from normative to cognitive ideas. This may be explained through their closer cooperation with international organisations (such as theEU), loss of significance of traditional role concepts such as neutrality, and the changed content of peace policies. Two consequences result from it: firstly, cognitive ideas are less linked to historically deep‐rooted identities and therefore more prone to change; secondly, there fewer comparative advantages accrue to small states in promoting cognitive ideas. Thus, though small states remain very active peacebuilders, they have become less “natural” peacemakers than they used to be.
Multidrug‐resistant TB in Zambia: review of national data from 2000 to 2011
Authors: Kapata Nathan , Chanda‐Kapata Pascalina , Bates Matthew , Mwaba Peter , Cobelens Frank , Grobusch Martin P. , Zumla Alimuddin
Published: September 2013

Background

Multidrug‐resistant tuberculosis (MDR‐TB) is posing a great threat to global TB control. The burden in Zambia is not well defined because routine surveillance data are scarce. We reviewed national MDR‐TB data for the last decade to inform future public health policy with respect to MDR‐TB in Zambia.

Method

Retrospective review of national surveillance of MDR‐TB data, TB programme and laboratory reports between 2000 and 2011.

Results

The total number of DSTs performed during this 11‐year period was 2 038 and accounted for 2.6% (2 038/78 639) of all the retreatment cases notified. The total number of diagnosed MDR‐TB cases for this period was 446, of which 56.3% (251/446) were male and 41.7% (186/446) female. Only one child was found to have MDR‐TB. Poly‐drug resistance accounted for 18.9% (172/911) of the DR‐TB cases and 8.4% of the total DSTs. 8.8% (80/911) of the DR‐TB cases showed either rifampicin mono‐ or poly‐resistance other than MDR‐TB. No XDR‐TB was reported. There were no data available on DR‐TB and HIV co‐infection. Only 65 MDR‐TB patients were notified and put on second‐line treatment according to WHO guidelines.

Conclusions

Multidrug‐resistant tuberculosis may be an emerging challenge in Zambia. There is a need to invest in improving the capacity of the TB programme to detect and manage MDR‐TB.
A Quantum Question Order Model Supported by Empirical Tests of anA Prioriand Precise Prediction
Authors: Wang Zheng , Busemeyer Jerome R.
Published: September 2013

Question order effects are commonly observed in self‐report measures of judgment and attitude. This article develops a quantum question order model (theQQmodel) to account for four types of question order effects observed in literature. First, the postulates of theQQmodel are presented. Second, ana priori, parameter‐free, and precise prediction, called theQQequality, is derived from these mathematical principles, and six empirical data sets are used to test the prediction. Third, a new index is derived from the model to measure similarity between questions. Fourth, we show that in contrast to theQQmodel, Bayesian and Markov models do not generally satisfy theQQequality and thus cannot account for the reported empirical data that support this equality. Finally, we describe the conditions under which order effects are predicted to occur, and we review a broader range of findings that are encompassed by these very same quantum principles. We conclude that quantum probability theory, initially invented to explain order effects on measurements in physics, appears to be a powerful natural explanation for order effects of self‐report measures in social and behavioral sciences, too.
A Quantum Probability Perspective on Borderline Vagueness
Authors: Blutner Reinhard , Pothos Emmanuel M. , Bruza Peter
Published: September 2013

The term “vagueness” describes a property of natural concepts, which normally have fuzzy boundaries, admit borderline cases, and are susceptible to Zeno's sorites paradox. We will discuss the psychology of vagueness, especially experiments investigating the judgment of borderline cases and contradictions. In the theoretical part, we will propose a probabilistic model that describes the quantitative characteristics of the experimental finding and extends Alxatib's and Pelletier's () theoretical analysis. The model is based on a Hopfield network for predicting truth values. Powerful as this classical perspective is, we show that it falls short of providing an adequate coverage of the relevant empirical results. In the final part, we will argue that a substantial modification of the analysis put forward by Alxatib and Pelletier and its probabilistic pendant is needed. The proposed modification replaces the standard notion of probabilities by quantum probabilities. The crucial phenomenon of borderline contradictions can be explained then as a quantum interference phenomenon.
Poincaré–Lelong equation via the Hodge–Laplace heat equation
Authors: Ni Lei , Tam Luen-Fai
Published: September 2013

In this paper, we develop a method of solving the Poincaré–Lelong equation, mainly via the study of the large time asymptotics of a global solution to the Hodge–Laplace heat equation on$(1, 1)$-forms. The method is effective in proving an optimal result when$M$has nonnegative bisectional curvature. It also provides an alternate proof of a recent gap theorem of the first author.
Residues and duality for singularity categories of isolated Gorenstein singularities
Authors: Murfet Daniel
Published: September 2013

We study Serre duality in the singularity category of an isolated Gorenstein singularity and find an explicit formula for the duality pairing in terms of generalised fractions and residues. For hypersurfaces we recover the residue formula of the string theorists Kapustin and Li. These results are obtained from an explicit construction of complete injective resolutions of maximal Cohen–Macaulay modules.
DSMC Simulation of Low Knudsen Micro/Nanoflows Using Small Number of Particles per Cells
Authors: Amiri-Jaghargh Ali , Roohi Ehsan , Niazmand Hamid , Stefanov Stefan
Published: September 2013

Direct simulation Monte Carlo (DSMC) method in low Knudsen rarefied flows at micro/nanoscales remains a big challenge for researchers due to large computational requirements. In this article, the application of the simplified Bernoulli-trials (SBT)/dual grid collision scheme is extended for solving low Knudsen/low speed and low Knudsen/high gradient rarefied micro/nanoflows. The main advantage of the SBT algorithm is to provide accurate calculations using much smaller number of particles per cell, i.e., 〈N〉 ≈ 2, which is quite beneficial for near continuum DSMC simulations where the requirement of fine meshes faces the simulation with serious memory restrictions. Comparing the results of the SBT/dual grid scheme with the no time counter (NTC) scheme and majorant frequency scheme (MFS), it is shown that the SBT/dual grid scheme could successfully predict the thermal pattern and hydrodynamics field as well as surface parameters such as velocity slip, temperature jump and wall heat fluxes. Therefore, we present SBT/dual grid algorithm as a suitable alternative of the standard collision schemes in the DSMC method for typical micro/nanoflows solution. Nonlinear flux-corrected transport (FCT) algorithm is also employed as a filter to extract the smooth solution from the noisy DSMC calculation for low speed/low Knudsen number DSMC calculations.
Dynamic Model of Oscillation-Assisted Cylindrical Plunge Grinding With Chatter
Authors: Pawłowski Witold
Published: September 2013

In this paper, the mathematical model of the oscillation-assisted cylindrical plunge grinding process has been presented. In this model, the dynamical properties of the grinder, self-excited vibration (regenerative chatter), and nonlinear behavior of the grinding force have been taken into consideration. This mathematical model has been applied to analyze both formation and development of chatter on the workpiece and the grinding wheel surface during oscillation-assisted cylindrical plunge grinding. The frequency response function (FRF), describing dynamical properties of the grinder, has been determined by means of modal experiment. The model has been implemented in matlab-simulink environment in order to perform simulations. The results of the simulations confirmed the antiregenerative properties of the oscillations of the workpiece rotational movement during cylindrical plunge grinding.
Avoiding Chatter in Traverse Cylindrical Grinding by Continuous Workpiece Speed Variation
Authors: Alvarez J. , Zatarain M. , Marquinez J. I. , Ortega N. , Gallego I.
Published: September 2013

Regenerative chatter is one of the main limiting factors in traverse cylindrical grinding since it involves loss of productivity, geometric inaccuracies, superficial marks, and increase of roughness. Continuous workpiece speed variation is demonstrated to be an efficient method among chatter suppression techniques but variation parameters (amplitude and frequency) are normally selected based on trial-and-errors. Therefore, a dynamic stability approach is proposed in which optimal combination of these parameters is defined based on semidiscretization technique, which consists of obtaining the eigenvalues of the transition matrix between consecutive workpiece rotations. Validation is carried out experimentally and good correlation between simulated and experimental results is achieved. Best combinations of variation parameters are achieved with amplitudes higher than 10% of the nominal workpiece speed and frequencies lower than 1 Hz. Then, the optimal parameters of continuous workpiece speed variation for chatter suppression can be predicted theoretically via semidiscretization. The application of this suppression technique has been successfully assessed for traverse cylindrical grinding.
Autogenerating/Drawing Valid Arrays and Contracted Graphs With Pentagonal Links for Type Synthesis of Mechanism by Computer Aided Design
Authors: Lu Yi , Huang Hui , Lu Yang , Ye Nijia
Published: September 2013

A method for autogeneration/draw of valid arrays and contracted graphs by cad is studied in this paper. First, the concepts and relative new criteria of arrays and contracted graphs (CGs) are explained for the representation/generation of the CGs and the identification of the isomorphic/invalid CGs using the arrays. Second, a software is created in Visual Basic for automatically generating the arrays of the CGs with pentagonal links, identifying the isomorphic/invalid arrays, generating the valid arrays, and automatically drawing their CGs. Third, the interface of the software and the main functions of the compiled programs are explained. Finally, some examples are given to illustrate this software and method.
The Dimensional Synthesis of Spatial Cable-Driven Parallel Mechanisms
Authors: Azizian K. , Cardou P.
Published: September 2013

This paper presents a method for the dimensional synthesis of fully constrained spatial cable-driven parallel mechanisms (CDPMs), namely, the problem of finding a geometry whose wrench-closure workspace (WCW) contains a prescribed workspace. The proposed method is an extension to spatial CDPMs of a synthesis method previously published by the authors for planar CDPMs. The WCW of CDPMs is the set of poses for which any wrench can be produced at the end-effector by non-negative cable tensions. A sufficient condition is introduced in order to verify whether a given six-dimensional box, i.e., a box covering point-positions and orientations, is fully inside the WCW of a given spatial CDPM. Then, a nonlinear program is formulated, whose optima represent CDPMs that can reach any point in a set of boxes prescribed by the designer. The objective value of this nonlinear program indicates how well the WCW of the resulting CDPM covers the prescribed box, a null value indicating that none of the WCW is covered and a value greater or equal to one indicating that the full prescribed workspace is covered.
Three-Dimensional Numerical Analysis of Turbulent Flow in Porous Media Formed by Periodic Arrays of Cubic, Spherical, or Ellipsoidal Particles
Authors: Yang J. , Zhou M. , Li S. Y. , Bu S. S. , Wang Q. W.
Published: September 2013

In the present paper, three-dimensional (3D) turbulent flow in the porous media formed by periodic arrays of particles is numerically investigated. 3D Navier–Stokes equations and a standard k-ε turbulence model with enhanced wall function are adopted to model the turbulent flow inside the pores. Both local and macroscopic turbulence characteristics for different particle types (cubic, spherical, and ellipsoidal particles) and array forms [simple cubic (SC) and body center cubic arrays (BCC)] with different pore Reynolds numbers and porosities are carefully examined. It is revealed that, in the structural arrays of particles, the effects of particle shape and array form would be remarkable. With the same Reynolds number and porosity, the magnitudes of turbulence kinetic energy and its dissipation rate for the simple cubic array of spheres (SC-S) would be higher than those for the other arrays. Furthermore, with a nonlinear fitting method, the macroscopic correlations for extra turbulence quantities k∞ and ɛ∞ in the structural arrays for different particle types and array forms are extracted. The forms of present correlations can fit well with those of Nakayama and Kuwahara's correlations [Nakayama and Kuwahara, 1999, “A Macroscopic Turbulence Model for Flow in Porous Media,” ASME J. Fluids Eng., 121(2), pp. 427–433], but some model constants would be lower.
Effects of Brownian Diffusion and Thermophoresis on the Laminar Forced Convection of a Nanofluid in a Channel
Authors: Rossi di Schio Eugenia , Celli Michele , Barletta Antonio
Published: September 2013

A steady laminar forced convection in a parallel–plane channel using nanofluids is studied. The flow is assumed to be fully developed, and described through the Hagen–Poiseuille profile. A boundary temperature varying with the longitudinal coordinate in the thermal entrance region is prescribed. Two sample cases are investigated in detail: a linearly changing wall temperature, and a sinusoidally changing wall temperature. A study of the thermal behavior of the nanofluid is performed by solving numerically the fully–elliptic coupled equations. The numerical solution is obtained by a Galerkin finite element method implemented through the software package Comsol Multiphysics (© Comsol, Inc.). With reference to both the wall temperature distributions prescribed along the thermal entrance region, the governing equations have been solved separately both for the fully developed region and for the thermal entrance region. The analysis shows that if a linearly varying boundary temperature is assumed, for physically interesting values of the Péclet number the concentration field depends very weakly on the temperature distribution. On the other hand, in case of a longitudinally periodic boundary temperature, nonhomogeneities in the nanoparticle concentration distribution arise, which are wrongly neglected whenever the homogeneous model is employed.
Development of an Inertia-Driven Model of Sideways Fall for Detailed Study of Femur Fracture Mechanics
Authors: Gilchrist Seth , Guy Pierre , Cripton Peter A
Published: September 2013

A new method for laboratory testing of human proximal femora in conditions simulating a sideways fall was developed. Additionally, in order to analyze the strain state in future cadaveric tests, digital image correlation (DIC) was validated as a tool for strain field measurement on the bone of the femoral neck. A fall simulator which included models for the body mass, combined lateral femur and pelvis mass, pelvis stiffness, and trochanteric soft tissue was designed. The characteristics of each element were derived and developed based on human data from the literature. The simulator was verified by loading a state-of-the-art surrogate femur and comparing the resulting force-time trace to published, human volunteer experiments. To validate the DIC, 20 human proximal femora were prepared with a strain rosette and speckle paint pattern, and loaded to 50% of their predicted failure load at a low compression rate. Strain rosettes were taken as the gold standard, and minimum principal strains from the DIC and the rosettes were compared using descriptive statistics. The initial slope of the force-time curve obtained in the fall simulator matched published human volunteer data, with local peaks superimposed in the model due to internal vibrations of the spring used to model the pelvis stiffness. Global force magnitude and temporal characteristics were within 2% of published volunteer experiments. The DIC minimum principal strains were found to be accurate to 127±239μɛ. These tools will allow more biofidelic laboratory simulation of falls to the side, and more detailed analysis of proximal femur failure mechanisms using human cadaver specimens.
Effect of Laser-Induced Crystallinity Modification on Biodegradation Profile of Poly(L-Lactic Acid)
Authors: Hsu Shan-Ting , Tan Huade , Lawrence Yao Y.
Published: September 2013

Poly(L-lactic acid) (PLLA) is of interest in drug delivery applications for its biodegradable and biocompatible properties. Polymer-controlled drug delivery relies on the release of embedded drug molecules from the polymer matrix during its degradation. PLLA degradation exhibits an induction period, during which an insignificant amount of degraded products and embedded drug can be released. Due to this induction period, drug release is initially nonlinear, a complication in drug delivery applications. PLLA degradation is a function of crystallinity, such that control over its crystallinity tailors drug release over time. In this study, the effect of laser-induced PLLA crystallinity reduction on degradation is investigated. Samples having lower surface crystallinity are shown to have higher rates of molecular weight reduction and earlier mass loss than nonlaser-treated samples, as observed from gel permeation chromatography and mass change. Wide-angle X-ray diffraction measurements show that crystallinity increases with degradation. A numerical model is implemented from hydrolysis and diffusion mechanisms to investigate the effect of laser irradiation on biodegradation. Controlled laser treatment of PLLA offers a method for constant drug release through the reduction of surface crystallinity.
Manufacturing of Nanostructured Blades for a Francis Turbine by Isothermal Forging of AA6063
Authors: Salcedo D. , Luis C. J. , León J. , Puertas I. , Fuertes J. P. , Luri R.
Published: September 2013

This research work deals with the manufacturing of blades for a Francis turbine with a submicrometric structure through the isothermal forging of a heat-treatable aluminum alloy that has been previously processed by angular channel extrusion. In addition, mechanical properties and microstructure of these same blades are analyzed. A comparative study is also carried out between the properties obtained in the forged blades from the alloy previously deformed through angular channel extrusion and those obtained by employing two other isothermal forging processes of this alloy which mean utilizing different process stages. Moreover, a modeling by finite element about the isothermal forging process of the blades is performed using flow rules obtained from compression tests on these alloys at different temperatures. In this way, a much higher degree of accuracy is achieved in the results compared with that obtained through traditional approaches. With this present study, it is intended to make some progress in the development of nanostructured mechanical components with the aim of demonstrating the feasibility of their manufacturing and achieving an improvement in their mechanical properties.
New Proportionate Affine Projection Algorithm
Authors: Albu Felix
Published: September 2013

A new proportionate-type affine projection algorithm with intermittent update of the weight coefficients is proposed. It takes into account the “history” of the proportionate factors and uses a fast recursive filtering procedure. Also, the effect of using dichotomous coordinate descent iterations is investigated. Simulation results indicate that the proposed algorithm has improved performance and much lower computational complexity than other proportionate affine projection algorithms. Therefore it represents a practical solution for acoustic echo cancellation systems.
The Significance of Balcony Acoustic Treatments in Mitigating Urban Road Traffic Noise
Authors: Tan Andy C. C. , Naish Daniel A. , Demirbilek F. Nur
Published: September 2013

Urban road traffic noise in cities is an ongoing and increasing problem across much of the world. Consequently a large amount of effort is expended in attempts to address this problem, especially in the area of acoustic design of buildings. Acoustic design policies developed by government authorities will typically focus on required transport noise reductions through a building façade to meet a specified internal noise levels. The significance of balcony acoustic treatments has been highlighted in recent decades yet this area has potentially been considered less important than the need for acoustic isolation of building facades. This paper outlines recent research that has been conducted in determining the significance of balcony acoustic treatments in mitigating urban road traffic noise. It summarizes recent literature, some of which focuses on technological advances in the knowledge of balcony acoustic design and some literature discusses the overall aims and benefits of balcony acoustic design. The aim of this paper is to promote the use of balcony acoustic design as a significant element in the overall solution towards mitigating road traffic noise in modern cities.
Six Noise Type Military Sound Classifier
Authors: Shelton Christopher Michael , Vipperman Jeffrey S. , Nykaza Edward T. , Valente Dan
Published: September 2013

Blast noise from military installations often has a negative impact on the quality of life of residents living in nearby communities. This, in turn, negatively impacts the military’s testing & training capabilities due to restrictions, curfews, or range closures enacted to address noise complaints. In order to more directly manage noise around military installations, accurate noise monitoring around bases has become a necessity. Although most noise monitors are simple sound level meters, more recent ones are capable of discerning blasts from ambient noise with some success. Investigators at the University of Pittsburgh (Pitt) developed a more advanced noise classifier that can discern between wind, aircraft, and blast noise, while simultaneously lowering the measurement threshold. Here, more recent work between Pitt and the US Army Engineer Research and Development Center will be presented from the development of a more advanced classifier that identifies additional classes of noise such as machine gun fire, vehicles, and electronic noise. Additional signal metrics were explored given the increased complexity of the classifier. By broadening the types of noise the system can accurately classify and increasing the number of metrics, a new system was developed with increased blast noise accuracy, decreased number of missed events, and significantly fewer false positives.
Recent Developments in High-Performance Computational Vibro-Acoustics in the Medium Frequency Regime
Authors: Farhat Charbel , Tezaur Radek , Hetmaniuk Ulrich
Published: September 2013

Structural acoustics applications in the medium frequency regime are computationally challenging. One avenue of research pursues higher-order discretization methods that can deliver both accuracy and computational efficiency at smaller mesh resolutions. The Discontinuous Enrichment Method (DEM) is one example which distinguishes itself from competing approaches in the additional information it incorporates in the approximation method. It has shown a significant promise for acoustic and structural acoustic applications and therefore is reviewed here, together with new applications to shell problems. Frequency sweeps, which are almost inevitable in many vibro-acoustic engineering problems, present an additional challenge as they significantly increase the already high computational cost. Therefore, interpolatory model reduction techniques that successfully address this challenge and enable real-time frequency sweep analyses are also discussed in this paper.
Procedure to Estimate the In-Duct Sound Power in the High Frequency Range With Non-Plane Waves
Authors: Hynninen Antti , Åbom Mats
Published: September 2013

The acoustic characterization of fluid machines, e.g., internal combustion engines, compressors, or fans is of great importance when designing the connected duct systems and its silencers. For machines connected to large ducts where also the non-plane wave range is important, for instance large diesels and gas turbines, a suitable way to characterize the source is to determine the sound power under reflection free conditions. For the low frequency plane wave range in-duct sound power can be measured with the widely used two microphone method. The goal of this study is to investigate how, starting from the two-microphone approach, a suitable wall mounted microphone configuration can be defined and used to estimate the propagating in-duct sound power also beyond the plane wave range. For this purpose an acoustic source test-rig was built and numerical simulations were also conducted. The in-duct sound power from monopole, dipole, and quadrupole source types was determined using twelve wall mounted microphones and cross-spectra averaging methods. The in-duct results were compared against sound power measured using the reverberation room method (ISO 3741). Based on the simulations and the experimental results the best microphone positions and weighting factors were determined.
What Kind of Friction Model Is Needed to Predict Brake Squeal?
Authors: Butlin Tore , Woodhouse Jim
Published: September 2013

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters.
Characterization of the Pressure Wave Emitted From Implosion of Submerged Cylindrical Shell Structures
Authors: Shields Michael D. , Woelke Pawel , Abboud Najib N.
Published: September 2013

Buckling of submerged cylindrical shells is a sudden and rapid implosion which emits a high pressure pulse that may be damaging to nearby structures. The characteristics of this pressure pulse are dictated by various parameters defining the shell structure such as the length to diameter ratio, shell thickness, material, and the existence and configuration of internal stiffeners. This study examines, through the use of high fidelity coupled fluid-structure finite element computations, the impact of various structural parameters on the resulting pressure wave emanating from the implosion. The results demonstrate that certain structural configurations produce pressure waves with higher peak pressure and impulse thereby enhancing the potential for damage to nearby structures.
An Approach for Structural-Acoustic Optimization of Ribbed Panels Using Component Mode Synthesis
Authors: Shepherd Micah R. , Hambric Stephen A.
Published: September 2013

Component mode synthesis (CMS) is an approach used to couple dynamics of complex structures using modes of individual components. A CMS approach is developed to determine the response of a ribbed panel based on the individual rib and plate modes. The CMS method allows for rapid evaluation of noise-control designs as component modes need to be solved only once. Since efficient evaluation is required for global design optimization procedures, the CMS approach can be well suited in optimization problems. A simple structural-acoustic optimization problem was created to demonstrate the utility of the formulation by finding the optimal rib location and material to reduce sound radiation for a point-driven plate. Several parameters of the optimization algorithm are varied to test convergence speed and accuracy.
Sonic Boom Propagation in Urban Canyons
Authors: Riegel Kimberly A. , Sparrow Victor W.
Published: September 2013

In order to make civilian supersonic flight over land possible, the resulting sonic boom must be acceptable to the people exposed. In order to determine the impact on people, determining the behavior of a sonic boom in a large city is critical. A combined ray tracing radiosity method was developed to propagate sonic booms into urban canyons. A variety of environmental parameters were changed to determine their effect on the resulting sound field. The arrival angles of the boom, the height of the canyons, the width of the canyons, and the amount of diffusion were all varied. It was shown that the resulting sound levels from most of these parameters was highly dependent on the combination of the parameters rather than a single parameter. Diffusion was the only parameter that showed a consistent trend in the amplitude of the sound field. [Work funded by NASA and the FAA’s PARTNER Center of Excellence.]
Optimal Sensor and Actuator Placement for Active Vibration Control Systems
Authors: Späh Britta , Schittenhelm Rudolf Sebastian , Rinderknecht Stephan
Published: September 2013

Locations of sensors and actuators have major impact on the characteristics of control systems. In this paper a procedure for sensor and actuator placement for vibration control systems is presented. Two different performance criteria are used in order to find optimal positions for the system under consideration. One is considering observability and controllability only, the other one includes knowledge about a disturbance and the control objective. Both criteria are applied to a clamped plate resulting in different optimal sensor and actuator positions. The resulting configurations are investigated by comparison of optimal feed forward and H∞ feedback control of the system with identical disturbances and control objectives but different sensor and actuator positions. The required control effort and achieved amplitude reduction are employed to rate the different performance criteria that were used to determine the sensor and actuator positions. It is shown that, by placing sensors and actuators on the basis of an adequate performance criterion, increased control performance in terms of amplitude reduction per control effort is achieved.
Transfer Path Analysis of Body Panel Participation Using a Structural-Acoustic Finite Element Model
Authors: Sung Shung H. , Nefske Donald J.
Published: September 2013

In transportation vehicles under operating conditions, interior noise frequently results from forces transmitted through the vehicle structure that excite body panel vibrations that couple with the body modes to radiate noise to the interior. The body panel participations to the interior noise that result from the force transfer paths can be identified using acoustic and structural-acoustic finite element models of the vehicle. This paper describes the transfer path analysis method to identify the body panel and modal participations for prescribed forcing excitations to the vehicle and to evaluate the effect of structural modifications. The theoretical development of the structural-acoustic finite element method and its example applications to two automotive vehicles are presented.
An Analytical–Numerical Aerodynamic Formulation for Efficient Aeroacoustics Analysis of Rotorcraft
Authors: Gennaretti Massimo , Testa Claudio , Bernardini Giovanni , Anobile Alessandro
Published: September 2013

This paper presents an analytical-numerical aerodynamic/aeroacoustic formulation for the analysis of the tonal noise emitted by helicopter rotors and propellers. It is particularly suited for those configurations dominated by local high-frequency changes (both in time and space) of blades inflow velocity. The solution of the Ffowcs Williams-Hawkings equation for noise radiation prediction is combined with the frequency-domain Küssner-Schwarz formulation that yields the sectional, unsteady aerodynamic loads, starting from the knowledge of the downwash on the airfoil due to blade motion and inflow induced on it by any external source of perturbation. Here, the blade inflow is assumed to be evaluated through a 3D, unsteady, panel method formulation suited for the analysis of rotors operating in a complex aerodynamic environment. This aerodynamic/aeroacoustic model gives a computationally efficient solution procedure that may be conveniently applied in preliminary design/multidisciplinary optimization applications. The proposed approach is validated through comparison with the (accurate, but computationally expensive) acoustic field obtained through the blade pressure loads directly evaluated by the time-marching panel-method solver. The results are provided in terms of blade loads, noise signatures and sound pressure level contours.
Influence of Wall Surface and Air Modelling in Finite-Element Analysis of Sound Transmission Between Rooms in Lightweight Buildings
Authors: Andersen Lars Vabbersgaard , Kirkegaard Poul Henning , Dickow Kristoffer Ahrens , Kiel Nikolaj , Persson Kent
Published: September 2013

Noise is a nuisance in the built environment, and to avoid undesirable transmission of sound and vibration within a building, its vibro-acoustic performance must be addressed in the design phase. For heavy structures, a reliable assessment of the sound pressure levels can be made by statistical energy analysis—especially at high frequencies. However, for lightweight buildings a numerical approach, e.g. the finite-element method, must be applied. A problem in this regard is the computational complexity. Even at low frequencies, many degrees of freedom are required in a model accounting for all possible paths for transmission of sound in a building—in particular when finite elements are employed for the air. This paper examines whether a rigorous model of the acoustic field in each room is necessary in order to obtain accurate estimates of the sound pressure, or if a simpler approach may be adopted. Five different cases are compared: A model that only includes the structure, a model with semi-infinite elements to account for radiation from the structure into the air, a model introducing finite elements for the acoustic field, a model with dissipation of sound inside the room, and finally a model with sound absorption on the surfaces of walls, floors and ceilings.
On the Effect of Mechanical Excitation Position on Panel Loss Factor Estimation With the Power Input Method
Authors: Dande Himanshu A. , Ewing Mark S.
Published: September 2013

For experimental determination of structural loss factor with mechanical excitation, the excitation location — i.e. “where to excite?” — and sensor placement — i.e. “where to measure?” — are quintessential considerations. For a highly-damped panel a significant portion is not experiencing reverberant field conditions, especially in higher frequency bands. That is, localized disturbances “die-out” before they can reflect off boundaries. As energy flows away from the excitation point, the energy the level in the direct field is higher than elsewhere, thereby resulting in higher response levels. Since the level of response is inversely proportional to damping, the loss factor predicted inside the direct field is underestimated. The size of direct field is proportional to frequency and loss factor. Therefore, for a highly damped and/or small plate, loss factor estimation based on randomly positioned accelerometers—which have a higher probability of being inside the direct field—will tend to underestimate damping.
Exploiting the Complex Plane: The Moebius Transformation and Vibro-Acoustic Optimization
Authors: Herrin D. W. , Zhang Y. , Liu J.
Published: September 2013

If a mechanical or acoustical impedance modification is introduced between two positions, the effect of that modification can be plotted in the complex plane at a given frequency. It has been shown that the mechanical or acoustical response will trace a circle in the complex plane for straight-line modifications to impedance in the complex plane. In that case, the equations relating the response to an impedance modification are in a form consistent with the Moebius transformation, which maps straight lines or circles in one complex domain into straight lines or circles in another complex plane. It is demonstrated that the equations for muffler transmission loss and mount insertion loss are in a form consistent with the Moebius transformation for certain design changes. Accordingly, the usefulness of this linear system property will be illustrated for both muffler and mount design.
A Laboratory Framework for Synchronous Near/Far-Field Acoustics and MHz PIV in High-Temperature, Shock-Containing, Jets
Authors: Murray N. , Lyons G. , Tinney C. E. , Donald B. , Baars W. , Thurow B. , Haynes H. , Panickar P.
Published: September 2013

This paper describes the experimental study of the noise generating characteristics of high-temperature, shock-containing jets emanating from conic-section, converging-diverging (C-D) nozzles. Conic C-D nozzles consist of two conic sections, one contracting and the other expanding, joined to form a supersonic nozzle with a very sharp radius of curvature at the nozzle throat. An experiment is conducted in which temporally resolved flow-field measurements are acquired simultaneously with near-field and far-field acoustics to allow investigation of the turbulence associated with noise generation. The MHz rate PIV system and its synchronization with acoustic measurements is described along with methods for data analysis. General acoustic results are presented to characterize the spectral content present, and preliminary results on the measured turbulence structures are discussed.
Identification of Sound Quality Parameters With Respect to Subjective Feel of HVAC Noise of Diesel SUV’s
Authors: Bodla Murali , Mohammed Riyazuddin , Bhangale Rajesh , Mansinh Khumbhar
Published: September 2013

Recent trends in developing quieter diesel power plants in automobiles leading to unmasking the secondary sound sources. One of the major secondary sound sources of in-cabin noise is HVAC system. HVAC noise is one such sound likely to be present as long as the automobile is in use. In extreme climatic conditions, like in India, HVAC is majorly operated at higher speeds and adding to that SUV volume requires more air circulation which generates lot of flow induced noise. Under these conditions, the contribution of HVAC noise is more significant for passengers and many a times it influences subjective cognition that causes the driver’s emotional response to be unpleasant, it is more important to identify the most significant sound quality parameters that contribute to the perception of HVAC noise. Measurements were done on five different diesel SUVs with different HVAC operating conditions each having variable fan speeds with engine on and off respectively. Using the semantic differential technique subjective rating of the measured signals has been done. The psycho acoustic parameters calculated objectively for the measured interior sounds later those were compared with subjective rating by using HVAC noise function (HNF) to obtain the suitable parameters to represent HVAC noise.
3D tomodosimetry using long scintillating fibers: A feasibility study
Authors: Goulet Mathieu , Archambault Louis , Beaulieu Luc , Gingras Luc
Published: September 2013

Purpose

: 3D dosimetry is recognized as an ideal for patient‐specific quality assurance (QA) of highly conformal radiotherapy treatments. However, existing 3D dosimeters are not straightforward to implement in the clinic, as their read‐out procedure is often tedious and their accuracy, precision, and/or sample size exhibit limitations. The purpose of this work is to develop a 3D dosimeter based on the concept of tomodosimetry inside concentric cylindrical planes using long scintillating fibers for the QA of modern radiotherapy techniques such as intensity‐modulated radiation therapy (IMRT) or intensity‐modulated arc therapy (IMAT).

Methods

: Using a model‐based simulation, scintillating fibers were modeled on three concentric cylindrical planes of radii 2.5, 5.0, and 7.5 cm, inside a 10 cm radius water‐equivalent cylinder phantom. The phantom was set to rotate around its central axis, made parallel to the linac gantry axis of rotation. Light acquisitions were simulated using the calculated dose from the treatment planning software and reconstructed in each cylindrical plane at a resolution of 1 mm2 using a total‐variation minimization iterative reconstruction algorithm. The 3D dose was then interpolated from the reconstructed cylindrical plane doses at a resolution of 1 mm3. Different scintillating fiber patterns were compared by varying the angle of each fiber in its cylindrical plane and introducing a light‐tight cut in each fiber. The precision of the reconstructed cylindrical dose distribution was evaluated using a Poisson modeling of the acquired light signals and the accuracy of the interpolated 3D dose was evaluated using an IMRT clinical plan for a prostate case.

Results

: Straight scintillating fiber patterns with light‐tight cuts were the most accurate in cylindrical dose reconstruction, showing less than 0.5 mm distance‐to‐agreement in dose gradients and a mean local dose difference of less than 0.2% in the high dose region for a 10 × 10 cm2 field. The precision attained with this fiber configuration was less than 0.9% in the high dose, low gradient region of an IMRT segment for light acquisitions of 0.1 MU over a 360 degree rotation of the cylinder phantom. 3D dose interpolation for the IMRT clinical plan yielded an overall dose difference with the reference input of less than 1%, except in high dose gradients.

Conclusions

: Using long scintillating fibers inside rotating, concentric cylindrical planes, the authors demonstrate that their tomodosimetry method has the potential for high resolution, precise, and accurate 3D dosimetry. Moreover, because of its water‐equivalence and rotational symmetry, this design should find interesting application for both treatment QA and machine commissioning.