bluuebunny/crossref_metadata_2025 huggingface dataset:
A Methodology for the Determination of the Light Distribution Profile of a Micro-Algal Photobioreactor
Authors: Straub Quinn , Ordonez Juan
Published: March 2012

The following work presents an in depth analysis of the distribution of the light absorbance profile. The proper identification of conditions that maximize the growth efficiency of photosynthetic algae is necessary to optimize the productivity as a whole of the photobioreactor. In an effort to understand light as it interacts with an absorbing species such as algae, various tests were completed to extrapolate extinction coefficient ε or a calibration curves based on Beer-Lamberts Law. To characterize the absorbance conditions in a photobioreactor, a light distribution model was developed. From the basis of an external radiated light system, a single-source system was developed. Mathematical expressions for the local light intensity and the average light intensity were derived for a cylindrical photobioreactor with external sources, single internal sources, and multiple internal sources. The proposed model was used to predict the light absorbance values inside an externally and internally radiated photobioreactor using Nannochloropsis Oculata. The effects of cell density and light path length were interpreted through experimental and model simulation studies. The predicted light intensity values were found to be within +/− 7% to those obtained experimentally. This level of accuracy could be better improved with more testing and more precise instrumentation. Due to the simplicity and flexibility of the proposed model, it was also possible to predict the light conditions in other complex multiple light source photobioreactors.
Comparing Utility Connected to Stand Alone Micro-Grids: From the Viewpoint of a Utility Engineer
Authors: Hoffman Mike , Russo Brian
Published: March 2012

This paper presents project examples of grid and grid-isolated micro-grids. It discusses micro-grid drivers; economic, environmental, and financial issues; and tools to plan and design micro-grids. Tools covered include modeling software resource options, generation types, fuel options, and services to provide smooth transitions (including required equipment and software controls), ranging from those of minimal expense to maximum functionality. The need for, and construction of, real-time operational interfaces is also addressed, with a focus on real world complications and guidance regarding implementation of planning design and of a micro-grid. This paper attempts to present a broad overview of micro-grids, including project examples, modeling tools, technology options, and practical and business insights to enable interested parties to quickly come up to speed on micro-grid basics. The included information should give interested parties the tools and resources to move forward on their own projects, assuming these parties have sufficient knowledge and experience with electrical distribution systems.
Analysis Tools for Sizing and Placement of Energy Storage in Grid Applications
Authors: Hoffman Mike , Kintner-Meyer Michael , DeSteese John , Sadovsky Artyom
Published: March 2012

In recent decades, research and development has significantly improved the cost and reliability of energy storage systems. However, a relatively small percentage of that work has focused on engineering tools for integrating energy storage into existing or future electric grids. This literature review revealed that only a small number of software tools exist, and that those tools only partially address the needs for placement, sizing, and overall control strategies of stationary energy storage within a smart grid infrastructure. None of the tools comprehensively captures the benefits of energy storage, which would reveal all of the potential values. None of the tools or models provides optimization features that identify optimal placement and sizing options within a transmission or distribution system context. This review identifies a need for tool development to fill the gap in the grid analytics and provides some recommendations of guiding principles for advancing the analytical capabilities needed for the engineering and grid planning communities.
Using a Windbreak to Improve the Thermal Performance of a Flat Plate Solar Collector: A Feasibility Study
Authors: Moaveni Saeed , Watts Michael C.
Published: March 2012

During the past few decades, a wide range of studies have been performed to improve the performance of flat plate solar collectors by either reducing the heat loss from a collector or by increasing the amount of solar radiation absorbed by the absorber plate. Examples of these studies include adding transparent honeycomb to fill the air gap between the glazing and absorber plate to reduce convective heat loss, replacing the air in the gap by other gases such as Argon, Krypton, Xenon and Carbon Dioxide, or adding a chemical coating such as Copper Oxide to increase absorbtance and reduce the emittance of the absorber plate. While these methods improve the collector’s efficiency, they focus primarily on limiting the natural convection that occurs in the collector cavity, or on improving the optical properties of the absorber or glazing. None of these studies have addressed the problem of heat loss due to forced convection to the surrounding ambient air in any detail. Yet, research has shown that forced convection will contribute significantly to the heat loss from a collector. Windbreaks have traditionally been used to direct wind to protect farmland, and to direct wind drifts and sand dunes. Windbreaks also have been shown to provide protection for homes from winter winds which result in reduced heating costs for buildings. While windbreaks have been traditionally used for large scale applications, there is reason to believe that similar benefits can be expected for scaled down applications such as adding a windbreak along side of a flat-plate solar collector. In this paper, we examine the feasibility of using a windbreak to provide a flat plate solar collector protection from the wind in order to improve its performance. A series of experiments were performed wherein the thermal performance of two flat-plate collectors — one without a windbreaker and one with a windbreaker — were measured. The results of these experiments are reported in this paper and the need for further studies to explore different windbreak configurations is discussed.
Case for the Inclusion of a Degree in Sustainable Energy Engineering in the University of the State of Mexico
Authors: Dura´n M. D. , Marti´nez I. , Rinco´n E.
Published: March 2012

This paper analyzes the evolution of the engineer’s role through history, from its origin in the Industrial Revolution to the present day. After that, an analysis of the current energetic transition and climate change context in the world, especially from the perspective of Mexico, is made. This analysis shows the need for a professional specialized in the development and improvement of efficient equipment for the sustainable use of energy. Throughout this article, professional degrees related with sustainable development in Mexico are reviewed, and the lack of this kind of professional degree was observed. Finally, we present the development of the Sustainable Energy Engineering Curriculum in the State of Mexico University. We have established the competencies and abilities that this professional must have in order to develop sustainable solutions to the energy dilemmas in Mexico.
Estimation of Performance of Absorption/Desorption System for Regenerating Waste Water From Industrial Process
Authors: Nakaso Koichi , Oktariani Erfina , Noda Atsushi , Nakashima Kazuya , Tahara Keisuke , Xue Bing , Wijayanta Agung Tri , Fukai Jun
Published: March 2012

More reduction in energy consumption is requested to the industrial processes. In particular, large quantity of waste water at low temperature is released from chemical and steel processes. In this study, adsorption/desorption process of zeolite and water pair were selected to generate steam from water at low temperature. Contacting water liquid and zeolite directly, adsorption heat released from zeolite makes excess water evaporate. Basic experiments for adsorption/desorption process were carried out. First of all, adsorbents with different type were tested to find the candidate of the proposed system, and then suitable adsorbent was selected. From the basic adsorption experiment, generation of steam from the water liquid was confirmed by the proposed system. In the desorption process, hot dry gas was introduced to the adsorbent. The effect of gas temperature and its flow rate was investigated. The performance of the system was theoretically investigated based on overall heat and mass balances. As a result, the ratio of enthalpy of recovered steam of 140°C to input waste water of 80°C was around 6 when adsorption process was only considered. On the other hand, the ratio was 0.57 when waste heat was utilized for the desorption process. However if waste heat such as exhaust gas can be utilized for the desorption process, the ratio, that is, the efficiency would increase.
Increased Efficiency of Photovoltaic Module via Groundwater Cooling: Energy and Economic Considerations
Authors: Budischak Cory , Goossen Keith W.
Published: March 2012

Solar energy will be an important source of energy for a sustainable energy system whether or not it is directly collected (solar thermal, photovoltaics) or indirectly collected (wind, wave, etc). This project focused on increasing the efficiency of the direct conversion of solar energy into electricity, which is also known as photovoltaics (PV). It has long been known that photovoltaic cells perform less efficiently at higher temperatures. In fact, solar modules under concentration are frequently cooled either actively or passively. The current study, however, focused on cooling modules under no concentration. The goal of the current project was to answer the question: Can the energy gained by cooling a photovoltaic module with groundwater be greater than the energy used by the cooling system and is there an economic benefit? A digital simulation of a simple photovoltaic module under groundwater cooling was performed in order to answer the research question. The simulation was performed for Phoenix, AZ and assuming certain control parameters it was found that the overall system produced over 9% more electricity than a system without groundwater cooling. While the groundwater cooled system increased overall electrical production, the economics of the system will also be presented. Recently, an Arizona utility APS introduced time of use pricing for electricity. Because groundwater cooling provides the most benefit during very hot days with high electrical demand, cooling is more economically attractive. A simple economic analysis will be presented including estimated costs of the cooling system and added value of the excess electrical energy produced under different APS rate plans.
The Comparative Study of Compact Development and Green Open Spaces in LEED-ND and Chinese Urban Planning Standards
Authors: Yin Hongxi , Wen Wen , Qu Ming , Ao Guowei
Published: March 2012

On the basis of a green neighborhood development project in Changsha, this paper, studies the disparities between compact development and green (vegetated) open space issues in LEED-ND and the following Chinese national and local urban planning standards: • Changsha City Technical Regulations on Urban Planning (CSCTRUP); • China Code of Urban Residential Areas Planning and Design (CURAPD); • Evaluation Standard for Green Building (ESGB). The author found LEED-ND scoring method in compact development and green open space suitable for Chinese urban redevelopment, however, the point’s scale in Neighborhood Pattern and Design (NPD) Credit 2: Compact Development and NPD Credit 9: Access to Civic and Public Space, cannot reflect Chinese urban reality. A set of alternative scoring approaches have been proposed to improve LEED-ND’s adaptability in China. Similarly, the green (vegetated) open space requirements are studied and technical suggestions are provided to adapt LEED-ND in China.
Enormous shrinkage of carbon nanotubes by supersonic stress and low-acceleration electron beam irradiation
Authors: Fujita Jun-ichi , Takahashi Teppei , Ueki Ryuichi , Hikata Takeshi , Okubo Soichiro , Utsunomiya Risa , Matsuba Teruaki
Published: March 2012

The authors demonstrated a new method for inducing enormous shrinkage in single-walled carbon nanotube bundles by applying low energy electron beam irradiation along with supersonic vibration, and a maximum shrinkage rate of −100% cm2/C was obtained under electron acceleration of 1 keV. The characteristic feature of the shrunken single-walled carbon nanotubes was a wavy deformation that affected the entire bundle. The authors believe that a uniaxial stress induced by the supersonic vibration broke the equilibrium of the internal stress and allowed the uniform accumulation of defects under low energy electron beam excitation. The wavy deformation of the single-walled carbon nanotubes resulted in the enormous shrinkage of the bundle.
The silent base flow and the sound sources in a laminar jet
Authors: Sinayoko Samuel , Agarwal Anurag
Published: March 2012

An algorithm to compute the silent base flow sources of sound in a jet is introduced. The algorithm is based on spatiotemporal filtering of the flow field and is applicable to multifrequency sources. It is applied to an axisymmetric laminar jet and the resulting sources are validated successfully. The sources are compared to those obtained from two classical acoustic analogies, based on quiescent and time-averaged base flows. The comparison demonstrates how the silent base flow sources shed light on the sound generation process. It is shown that the dominant source mechanism in the axisymmetric laminar jet is “shear-noise,” which is a linear mechanism. The algorithm presented here could be applied to fully turbulent flows to understand the aerodynamic noise-generation mechanism.
Coherent acoustic wave propagation in media with pair-correlated spheres
Authors: Caleap Mihai , Drinkwater Bruce W. , Wilcox Paul D.
Published: March 2012

Propagation of plane compressional waves in a non-viscous fluid with a dense distribution of identical spherical scatterers is investigated. The analysis is based on the multiple scattering approach proposed by Fikioris and Waterman, and is generalized to include arbitrary choice of the pair-correlation functions used to represent the distribution of the scatterers. A closed form solution for the effective wavenumber as a function of the concentration of pair-correlated finite-size spheres is derived up to the second order. In the limit of uncorrelated point-scatterers, this solution is identical to that obtained by Lloyd and Berry. Different pair-correlation functions are exemplified and compared, and the resulting differences discussed.
Acoustic impulse response method as a source of undergraduate research projects and advanced laboratory experiments
Authors: Robertson W. M. , Parker J. M.
Published: March 2012

A straightforward and inexpensive implementation of acoustic impulse response measurement is described utilizing the signal processing technique of coherent averaging. The technique is capable of high signal-to-noise measurements with personal computer data acquisition equipment, an amplifier/speaker, and a high quality microphone. When coupled with simple waveguide test systems fabricated from commercial PVC plumbing pipe, impulse response measurement has proven to be ideal for undergraduate research projects—often of publishable quality—or for advanced laboratory experiments. The technique provides important learning objectives for science or engineering students in areas such as interfacing and computer control of experiments; analog-to-digital conversion and sampling; time and frequency analysis using Fourier transforms; signal processing; and insight into a variety of current research areas such as acoustic bandgap materials, acoustic metamaterials, and fast and slow wave manipulation.
Student design projects in applied acoustics
Authors: Bös Joachim , Moritz Karsten , Skowronek Adam , Thyes Christian , Tschesche Johannes , Hanselka Holger
Published: March 2012

This paper describes a series of student projects which are intended to complement theoretical education in acoustics and engineering noise control with practical experience. The projects are also intended to enhance the students’ ability to work in a team, to manage a project, and to present their results. The projects are carried out in close cooperation with industrial partners so that the students can get a taste of the professional life of noise control engineers. The organization of such a project, its execution, and some of the results from the most recent student project are presented as a demonstrative example. This latest project involved the creation of noise maps of a production hall, the acoustic analysis of a packaging machine, and the acoustic analysis of a spiral vibratory conveyor. Upon completion of the analysis, students then designed, applied, and verified some simple preliminary noise reduction measures to demonstrate the potential of these techniques.
Acoustic testing and modeling: An advanced undergraduate laboratory
Authors: Russell Daniel A. , Ludwigsen Daniel O.
Published: March 2012

This paper describes an advanced laboratory course in acoustics, specifically targeted for students with an interest in engineering applications at a school with a strongly integrated industrial co-op program. The laboratory course is developed around a three-pronged approach to problem solving that combines and integrates theoretical models, computational models, and experimental data. The course is structured around modules that begin with fundamental concepts and build laboratory skills and expand the knowledge base toward a final project. Students keep a detailed laboratory notebook, write research papers in teams, and must pass laboratory certification exams. This paper describes the course layout and philosophy and shares personal experience from both faculty and student perspectives.
Classroom demonstrations of acoustic beamforming
Authors: Carman Jessie C.
Published: March 2012

A tabletop apparatus permitting demonstrations and hands-on student exercises in the acoustic beamforming of linear arrays is described. The apparatus can be used to demonstrate how interference effects from two or more linearly arranged sources produce patterns of maxima and minima as described by theory. A transmitting array is attached to the top of a rotating table and a receiving transducer provides voltages to a signal processor. Students measure the angular speed of the rotating table and the voltages produced by the receiving transducer as a function of time. These data can be analyzed in a spreadsheet program and compared to theory. The angles at which signal maxima occur correspond well to theory and useful teaching discussions result from comparisons of signal maxima magnitudes. The spreadsheet analysis can also provide the students a graphical demonstration of l’Hôpital’s rule.
Education in acoustics and speech science using vocal-tract models
Authors: Arai Takayuki
Published: March 2012

Several vocal-tract models were reviewed, with special focus given to the sliding vocal-tract model [T. Arai, Acoust. Sci. Technol. 27(6), 384–388 (2006)]. All of the models have been shown to be excellent tools for teaching acoustics and speech science to elementary through university level students. The sliding three-tube model is based on Fant’s three-tube model [G. Fant, Acoustic Theory of Speech Production (Mouton, The Hague, The Netherlands, 2006)] and consists of a long tube with a slider simulating tongue constriction. In this article, the design of the sliding vocal-tract model was reviewed. Then a science workshop was discussed where children were asked to make their own sliding vocal-tract models using simple materials. It was also discussed how the sliding vocal-tract model compares to our other vocal-tract models, emphasizing how the model can be used to instruct students at higher levels, such as undergraduate and graduate education in acoustics and speech science. Through this discussion the vocal-tract models were shown to be a powerful tool for education in acoustics and speech science for all ages of students.
Vibrational behavior of a soundbox in an atmosphere with a variable speed of sound
Authors: Chen Mo , Kotlicki Andrzej , Waltham Chris , Wolfe Nathan , Fei Yu Jing , Zhu Chenchong
Published: March 2012

This paper describes a semi-quantitative method, suitable for a student laboratory exercise that shows that the acoustic properties of the soundbox of a musical instrument depend on the sound speed of the atmosphere surrounding and filling the instrument. A gas tent was constructed and used to enclose instruments in helium, carbon dioxide and mixtures thereof, allowing the sound speed to be varied from 250 to 1000 m/s. Soundboard admittance data were taken using a guitar and a violin as examples. The data, expressed as contour plots, show clearly the qualitative relationship between air and wood modes, and the guitar data are compared with a simple mechanical model. Experimental details of the construction and operation of gas tent are given, with attention paid to safety issues.
Measuring elastic constants of arbitrarily shaped samples using resonant ultrasound spectroscopy
Authors: Liu Guoxing , Maynard J. D.
Published: March 2012

One of the most important undertakings for materials is the measurement of the elastic behavior. As derivatives of the free energy with respect to atomic displacements, the elastic properties are closely connected to the thermodynamic properties of the material. Elastic behavior is a sensitive probe of the lattice environment in which all solid state phenomena occur, particularly in the vicinity of a phase transition. A useful method for measuring elastic properties is resonant ultrasound spectroscopy (RUS). Some novel materials to which RUS might be applied are often fragile or chemically reactive so that they cannot be polished into the shapes required by conventional RUS; for such cases a finite element method may be used. In this paper a discussion and test of a finite element method for RUS with arbitrarily shaped samples is provided.
Acoustical characteristics of water sounds for soundscape enhancement in urban open spaces
Authors: Jeon Jin Yong , Lee Pyoung Jik , You Jin , Kang Jian
Published: March 2012

The goal of the present study is to characterize water sounds that can be used in urban open spaces to mask road traffic noise. Sounds and visual images of a number of water features located in urban open places were obtained and subsequently analyzed in terms of psychoacoustical metrics and acoustical measures. Laboratory experiments were then conducted to investigate which water sound is appropriate for masking urban noise. The experiments consisted of two sessions: (1) Audio-only condition and (2) combined audio-visual condition. Subjective responses to stimuli were rated through the use of preference scores and 15 adjectives. The results of the experiments revealed that preference scores for the urban soundscape were affected by the acoustical characteristics of water sounds and visual images of water features; Sharpness that was used to explain the spectral envelopes of water sounds was proved to be a dominant factor for urban soundscape perception; and preferences regarding the urban soundscape were significantly related to adjectives describing “freshness” and “calmness.”
Threshold received sound pressure levels of single 1–2 kHz and 6–7 kHz up-sweeps and down-sweeps causing startle responses in a harbor porpoise (Phocoena phocoena)
Authors: Kastelein Ronald A. , Steen Nele , Gransier Robin , Wensveen Paul J. , de Jong Christ A. F.
Published: March 2012

Mid-frequency and low-frequency sonar systems produce frequency-modulated sweeps which may affect harbor porpoises. To study the effect of sweeps on behavioral responses (specifically “startle” responses, which we define as sudden changes in swimming speed and/or direction), a harbor porpoise in a large pool was exposed to three pairs of sweeps: a 1–2 kHz up-sweep was compared with a 2–1 kHz down-sweep, both with and without harmonics, and a 6–7 kHz up-sweep was compared with a 7–6 kHz down-sweep without harmonics. Sweeps were presented at five spatially averaged received levels (mRLs; 6 dB steps; identical for the up-sweep and down-sweep of each pair). During sweep presentation, startle responses were recorded. There was no difference in the mRLs causing startle responses for up-sweeps and down-sweeps within frequency pairs. For 1–2 kHz sweeps without harmonics, a 50% startle response rate occurred at mRLs of 133 dB re 1 μPa; for 1–2 kHz sweeps with strong harmonics at 99 dB re 1 μPa; for 6–7 kHz sweeps without harmonics at 101 dB re 1 μPa. Low-frequency (1–2 kHz) active naval sonar systems without harmonics can therefore operate at higher source levels than mid-frequency (6–7 kHz) active sonar systems without harmonics, with similar startle effects on porpoises.
Reflection of compressional and Rayleigh waves on the edges of an elastic plate with quadratic nonlinearity
Authors: Autrusson Thibaut B. , Sabra Karim G. , Leamy Michael J.
Published: March 2012

Previous ultrasonic studies have demonstrated that measurements of material nonlinearities can provide a means for detecting early signs of fatigue damage using both compressional (P) and Rayleigh (R) surface waves. However, these experimental studies have typically been limited to the direct wave arrival between the source and receiver in simple geometries where no reflection occurs. In particular, the degree of material nonlinearity is often quantified by the ratio of the cumulative amplitude of the first harmonic to that of the fundamental for the direct arrival only. Hence a practical question arises over the interpretation of ultrasonic measurements of material nonlinearities in the presence of reflected nonlinear waves. Thus, this article investigates the reflection problem of P or R waves at the edge of a homogeneous plate with quadratic nonlinearity using both a theoretical formulation, based on perturbation analysis, and direct numerical simulations using a Cellular Automata formulation. The numerical approach is first validated against an existing theoretical formulation for reflecting nonlinear P waves. It is then used to simulate the nonlinear reflection of R waves at a plate’s edge for which no closed-form formulation is presently available.
Wave field synthesis of a sound field described by spherical harmonics expansion coefficients
Authors: Ahrens Jens , Spors Sascha
Published: March 2012

Near-field compensated higher order Ambisonics (NFC-HOA) and wave field synthesis (WFS) constitute the two best-known analytic sound field synthesis methods. While WFS is typically used for the synthesis of virtual sound scenes, NFC-HOA is typically employed in order to synthesize sound fields that have been captured with appropriate microphone arrays. Such recorded sound fields are essentially represented by the coefficients of the underlying surface spherical harmonics expansion. A sound field described by such coefficients cannot be straightforwardly synthesized in WFS. This is a consequence of the fact that, unlike in NFC-HOA, it is critical in WFS to carefully select those loudspeakers that contribute to the synthesis of a given sound source in a sound field under consideration. In order to enable such a secondary source selection, it is proposed to employ the well-known concept of decomposing the sound field under consideration into a continuum of plane waves, for which the secondary source selection is straightforward. The plane wave representation is projected onto the horizontal plane and a closed form expression of the secondary source driving signals for horizontal WFS systems of arbitrary convex shape is derived.
Recognizing articulatory gestures from speech for robust speech recognition
Authors: Mitra Vikramjit , Nam Hosung , Espy-Wilson Carol , Saltzman Elliot , Goldstein Louis
Published: March 2012

Studies have shown that supplementary articulatory information can help to improve the recognition rate of automatic speech recognition systems. Unfortunately, articulatory information is not directly observable, necessitating its estimation from the speech signal. This study describes a system that recognizes articulatory gestures from speech, and uses the recognized gestures in a speech recognition system. Recognizing gestures for a given utterance involves recovering the set of underlying gestural activations and their associated dynamic parameters. This paper proposes a neural network architecture for recognizing articulatory gestures from speech and presents ways to incorporate articulatory gestures for a digit recognition task. The lack of natural speech database containing gestural information prompted us to use three stages of evaluation. First, the proposed gestural annotation architecture was tested on a synthetic speech dataset, which showed that the use of estimated tract-variable-time-functions improved gesture recognition performance. In the second stage, gesture-recognition models were applied to natural speech waveforms and word recognition experiments revealed that the recognized gestures can improve the noise-robustness of a word recognition system. In the final stage, a gesture-based Dynamic Bayesian Network was trained and the results indicate that incorporating gestural information can improve word recognition performance compared to acoustic-only systems.
Acoustic propagation from a spiral wave front source in an ocean environment
Authors: Hefner Brian T. , Dzikowicz Benjamin R.
Published: March 2012

A spiral wave front source generates a pressure field that has a phase that depends linearly on the azimuthal angle at which it is measured. This differs from a point source that has a phase that is constant with direction. The spiral wave front source has been developed for use in navigation; however, very little work has been done to model this source in an ocean environment. To this end, the spiral wave front analogue of the acoustic point source is developed and is shown to be related to the point source through a simple transformation. This makes it possible to transform the point source solution in a particular ocean environment into the solution for a spiral source in the same environment. Applications of this transformation are presented for a spiral source near the ocean surface and seafloor as well as for the more general case of propagation in a horizontally stratified waveguide.
Eigenpairs of a coupled rectangular cavity and its fundamental properties
Authors: Tanaka Nobuo , Takara Yusuke , Iwamoto Hiroyuki
Published: March 2012

This paper deals with the eigenvalue problem of a coupled rectangular cavity comprising five rigid walls and one flexible panel frequently employed in much literature. It is the purpose of this paper to derive explicitly the eigenpairs of the coupled cavity, which are yet to be found. First, the coupling orthogonality conditions the eigenpairs need to satisfy are derived, thereby enabling the verification of the eigenpairs newly sought or already existent. Using the coupling orthogonality conditions, the modal equation of the coupled cavity system is then obtained, permitting one to deal with a forced response of the coupled cavity. It is shown that the eigenfunctions governing the dynamics of the sound field are expressed as the infinite sum of degenerate eigenfunctions. The characteristic matrix equation is then derived, specifying the eigenpairs of the coupled cavity. In order to investigate the fundamental properties of the eigenpairs derived, a numerical analysis is conducted, revealing the presence of evanescent modes in addition to the conventional standing wave modes. Finally, an experiment is carried out, verifying the validity of the eigenpairs derived in the article.
Velocity and attenuation of scalar and elastic waves in random media: A spectral function approach
Authors: Calvet Marie , Margerin Ludovic
Published: March 2012

This paper investigates the scattering of scalar and elastic waves in two-phase materials and single-mineral-cubic, hexagonal, orthorhombic-polycrystalline aggregates with randomly oriented grains. Based on the Dyson equation for the mean field, explicit expressions for the imaginary part of Green’s function in the frequency-wavenumber domain (ω, p), also known as the spectral function, are derived. This approach allows the identification of propagating modes with their relative contribution, and the computation of both attenuation and phase velocity for each mode. The results should be valid from the Rayleigh (low-frequency) to the geometrical optics (high-frequency) regime. Comparisons with other approaches are presented for both scalar and elastic waves.
Traffic noise reduction at balconies on a high-rise building façade
Authors: Ishizuka Takashi , Fujiwara Kyoji
Published: March 2012

The performance of balconies with ceiling-mounted reflectors on a high-rise building façade is examined using numerical analyses and scale-model experiments. The reflectors are designed to reflect direct and diffracted waves incident on the ceiling outside the balcony. The sound pressure reduction, provided by the reflectors, on a window surface adjacent to the balcony is evaluated at intermediate floors levels. In terms of A-weighted sound pressure levels, a balcony equipped with reflectors reduces road traffic noise by 7–10 dB(A), compared to an ordinary balcony, at incident angles of noise close to the angle for which the reflectors are designed. The efficiency is roughly the same as, or greater than, that of a balcony with an absorbent ceiling. However, it is also shown that when the vertical incident angle of the noise is smaller than the design angle of the reflectors, or the horizontal incident angle is large, efficiency is reduced.
Modeling of micro-perforated panels in a complex vibro-acoustic environment using patch transfer function approach
Authors: Maxit L. , Yang C. , Cheng L. , Guyader J.-L.
Published: March 2012

A micro-perforated panel (MPP) with a backing cavity is a well known device for efficient noise absorption. This configuration has been thoroughly studied in the experimental conditions of an acoustic tube (Kundt tube), in which the MPP is excited by a normal incident plane wave in one dimension. In a more practical situation, the efficiency of MPP may be influenced by the vibro-acoustic behavior of the surrounding systems as well as excitation. To deal with this problem, a vibro-acoustic formulation based on the patch transfer functions (PTF) approach is proposed to model the behavior of a micro-perforated structure in a complex vibro-acoustic environment. PTF is a substructuring approach, which allows assembling different vibro-acoustic subsystems through coupled surfaces. Upon casting micro-perforations and the flexibility of the MPP under transfer function framework, the proposed PTF formulation provides explicit representation of the coupling between subsystems and facilitates physical interpretation. As an illustration example, application to a MPP with a backing cavity located in an infinite baffle is demonstrated. The proposed PTF formulation is finally validated through comparison with experimental measurements available in the literature.
ACOUSTICAL STANDARDS NEWS
Authors: Blaeser Susan B. , Schomer Paul D.
Published: March 2012

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards catalogs, please contact Susan B. Blaeser.

Comments are welcomed on all material in Acoustical Standards News.

This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org.
Extracting the Green’s function from measurements of the energy flux
Authors: Snieder Roel , Douma Huub , Vasconcelos Ivan
Published: March 2012

Existing methods for Green’s function extraction give the Green’s function from the correlation of field fluctuations recorded at those points. In this work it is shown that the Green’s function for acoustic waves can be retrieved from measurements of the integrated energy flux through a closed surface taken from three experiments where two time-harmonic sources first operate separately, and then simultaneously. This makes it possible to infer the Green’s function in acoustics from measurements of the energy flux through an arbitrary closed surface surrounding both sources. The theory is also applicable to quantum mechanics where the Green’s function can be retrieved from measurement of the flux of scattered particles through a closed surface.
Comment on “Widespread RNA and DNA Sequence Differences in the Human Transcriptome”
Authors: Kleinman Claudia L. , Majewski Jacek
Published: March 2012

Li
et al
. (Research Articles, 1 July 2011, p. 53; published online 19 May 2011) reported large numbers of differences between DNA and messenger RNA in human cells, indicating unprecedented levels of RNA editing, and including sequence changes not produced by any of the known RNA editing mechanisms. However, common sources of systematic errors in high-throughput sequencing technology, which were not properly accounted for in this study, explain most of the claimed differences.
Response to Comments on “Widespread RNA and DNA Sequence Differences in the Human Transcriptome”
Authors: Li Mingyao , Wang Isabel X. , Cheung Vivian G.
Published: March 2012

Kleinman and Majewski, Pickrell
et al
., and Lin
et al
. suggest that mapping and sequencing errors and genetic variants led to false discovery of RNA-DNA sequence differences in our paper. We repeated our analysis using two different sequence alignment methods and carried out additional experiments including whole genome DNA sequencing. The results are consistent with our finding of widespread RNA-DNA sequence differences.
Comment on “Widespread RNA and DNA Sequence Differences in the Human Transcriptome”
Authors: Pickrell Joseph K. , Gilad Yoav , Pritchard Jonathan K.
Published: March 2012

Li
et al
.
(
Research Articles, 1 July 2011, p. 53; published online 19 May 2011
)
reported more than 10,000 mismatches between messenger RNA and DNA sequences from the same individuals, which they attributed to previously unrecognized mechanisms of gene regulation. We found that at least 88% of these sequence mismatches can likely be explained by technical artifacts such as errors in mapping sequencing reads to a reference genome, sequencing errors, and genetic variation.
The Multielectron Ionization Dynamics Underlying Attosecond Strong-Field Spectroscopies
Authors: Boguslavskiy Andrey E. , Mikosch Jochen , Gijsbertsen Arjan , Spanner Michael , Patchkovskii Serguei , Gador Niklas , Vrakking Marc J. J. , Stolow Albert
Published: March 2012

Which Electron Went Where?

When strong laser fields pull electrons out of atoms or molecules and then send them careening back, the light released on recollision can offer direct insight into local attosecond-scale behavior, or it can be processed into attosecond pulses for probing other samples. When polyatomic molecules are involved, however, it is not always clear which of their electrons are being manipulated by the laser field.

Boguslavskiy
et al.

(p.
1336
; see the Perspective by

Gühr

) present a technique for exploring this question. Simultaneous tracking of electrons and fragment molecular ions during strong-field ionization of hydrocarbons revealed the different pathways involved.
Ultrastrong Coupling of the Cyclotron Transition of a 2D Electron Gas to a THz Metamaterial
Authors: Scalari G. , Maissen C. , Turčinková D. , Hagenmüller D. , De Liberato S. , Ciuti C. , Reichl C. , Schuh D. , Wegscheider W. , Beck M. , Faist J.
Published: March 2012

Quantum Hall Meets Metamaterial

Controlling and tuning light-matter interaction is crucial for fundamental studies of cavity quantum electrodynamics and for applications in classical and quantum devices.

Scalari
et al.

(p.
1323
) describe a system comprising an array of metamaterial split-ring resonators and a series of two-dimensional electronic gases (2DEG) formed in GaAs quantum wells. In a magnetic field, the electrons in the 2DEG performed cyclotron orbits and formed Landau levels. Strong coupling was observed between photon and magnetic cyclotron modes, producing a tunable semiconductor system for studying the light-matter interaction of two-level systems.
Scaling Hetero-Epitaxy from Layers to Three-Dimensional Crystals
Authors: Falub Claudiu V. , von Känel Hans , Isa Fabio , Bergamaschini Roberto , Marzegalli Anna , Chrastina Daniel , Isella Giovanni , Müller Elisabeth , Niedermann Philippe , Miglio Leo
Published: March 2012

Laying It on Thick

The growth of one layered material onto a second lies at the heart of many electronic devices. However, if there is a lattice mismatch between the two materials, strains develop in the overgrowth material leading to bowing and cracking.

Falub
et al.

(p.
1330
; see the cover) patterned Si substrates into a series of pillars onto which they grew a germanium layer. The germanium initially coated the top of each silicon pillar but then widened as the layer thickened, leading to thick, crack-free germanium films.
The Path from β-Carotene to Carlactone, a Strigolactone-Like Plant Hormone
Authors: Alder Adrian , Jamil Muhammad , Marzorati Mattia , Bruno Mark , Vermathen Martina , Bigler Peter , Ghisla Sandro , Bouwmeester Harro , Beyer Peter , Al-Babili Salim
Published: March 2012

Making Carlactone

Germination of parasitic witchweeds depends on strigolactones, which also regulate plant branching and signal in the context of mycorrhizal symbioses. The biosynthetic pathways that lead to strigolactones are founded in carotenoid biosynthesis, but further steps have been obscure.

Alder
et al.

(p.
1348
) have now identified a biochemical pathway that generates a strigolactone-like compound, carlactone, which shows biological actions similar to those of strigolactone.
Valuing Reversible Energy Storage
Authors: Miller John R.
Published: March 2012

A process based on laser-converted graphene is used to fabricate high-value energy storage material.
Open Access—Pass the Buck
Authors: Leptin Maria
Published: March 2012

Peer-reviewed scientific publishing serves the research community by verifying the validity of research results, disseminating the findings, and archiving them in a stable and accessible form. Over the past decade, “open access” has gained momentum as a model for scientific publishing, intended to makes results freely accessible to the scientific community and to the public on the Internet. Controversy over public access to research continues to escalate. For example, the dueling proposals recently introduced in the U.S. Congress could have reverberations worldwide: The Federal Research Public Access Act would require articles resulting from research funded by any federal agency to be made publicly available 6 months after publication, whereas the Research Works Act would prohibit such mandates.
Something Fishy? NOAA Economics Study Makes Waves
Authors: Malakoff David
Published: March 2012

An economist with the U.S. National Oceanic and Atmospheric Administration is mailing checks for up to $500 to anglers in Massachusetts as part of an unusual study to assess the value of saltwater fisheries.
Induction of Protective Immune Responses by a Multiantigenic DNA Vaccine Encoding GRA7 and ROP1 of Toxoplasma gondii
Authors: Quan Juan-Hua , Chu Jia-Qi , Ismail Hassan Ahmed Hassan Ahmed , Zhou Wei , Jo Eun-Kyeong , Cha Guang-Ho , Lee Young-Ha
Published: March 2012

Toxoplasma gondiiis distributed worldwide and infects most species of warm-blooded animals, including humans. The heavy incidence and severe or lethal damage caused byT. gondiiinfection clearly indicates the need for the development of a vaccine. To evaluate the protective efficacy of a multiantigenic DNA vaccine expressing GRA7 and ROP1 ofT. gondiiwith or without a plasmid encoding murine interleukin-12 (pIL12), we constructed DNA vaccines using the eukaryotic plasmids pGRA7, pROP1, and pGRA7-ROP1. Mice immunized with pGRA7, pROP1, or pGRA7-ROP1 showed significantly increased serum IgG2a titers; production of gamma interferon (IFN-γ), IL-10, and tumor necrosis factor alpha (TNF-α);in vitroT cell proliferation; and survival, as well as decreased cyst burdens in the brain, compared to mice immunized with either the empty plasmid, pIL12, or vector with pIL12 (vector+pIL12). Moreover, mice immunized with the multiantigenic DNA vaccine pGRA7-ROP1 had higher IgG2a titers, production of IFN-γ and TNF-α, survival time, and cyst reduction rate compared to those of mice vaccinated with either pGRA7 or pROP1 alone. Furthermore, mice immunized with either a pGRA7-ROP1+pIL12 or a single-gene vaccine combined with pIL12 showed greater Th1 immune response and protective efficacy than the single-gene-vaccinated groups. Our data suggest that the multiantigenic DNA antigen pGRA7-ROP1 was more effective in stimulating host protective immune responses than separately injected single antigens, and that IL-12 serves as a good DNA adjuvant.
Development and Evaluation of a Genus-Specific, Probe-Based, Internal-Process-Controlled Real-Time PCR Assay for Sensitive and Specific Detection of Blastocystis spp
Authors: Stensvold Christen Rune , Ahmed Umran Nisar , Andersen Lee O'Brien , Nielsen Henrik Vedel
Published: March 2012

Blastocystis
is a common intestinal parasite of unsettled clinical significance, which is not easily detected by standard parasitological methods. The genus comprises at least 13 subtypes (STs) (which likely represent separate species), 9 of which have been found in humans. Recent data indicate that at least one of the subtypes is associated with intestinal disease. A quantitative TaqMan 5′ nuclease real-time PCR (TaqMan PCR) including an internal process control (IPC) was developed for the detection of
Blastocystis
and shown to be applicable to genomic DNAs extracted directly from feces. The assay enabled successful amplification of DNAs from all relevant subtypes within the genus (ST1 to ST9). For assay evaluation, 153 samples previously tested by xenic
in vitro
culture (XIVC) were screened by the TaqMan assay. A total of 49/51 samples positive by XIVC and 13/102 samples negative by XIVC were positive by the TaqMan assay; samples positive by the TaqMan assay and negative by XIVC were subsequently tested by conventional PCR, and amplicons could be identified to the subtype level by sequencing in 69% of the cases. Compared to the TaqMan assay, XIVC had a sensitivity of 79%. This is the first time that a genus-specific, probe-based, internal-process-controlled real-time PCR assay for the detection
Blastocystis
has been introduced.
A New Loop-Mediated Isothermal Amplification Method for Rapid, Simple, and Sensitive Detection of Leptospira spp. in Urine
Authors: Koizumi Nobuo , Nakajima Chie , Harunari Tsunehito , Tanikawa Tsutomu , Tokiwa Toshihiro , Uchimura Eriko , Furuya Tokujiro , Mingala Claro Niegos , Villanueva Marvin Ardeza , Ohnishi Makoto , Suzuki Yasuhiko
Published: March 2012

We developed a new loop-mediated isothermal amplification (LAMP) method to detectrrs, a 16S rRNA gene of pathogenicLeptospiraspp. in urine. The method enables detection of two leptospiral cells per reaction mixture following boiling of urine specimens. The sensitivity of this method is higher than that of culture or offlaBnested PCR.