WorldWideScience

Sample records for channel sounding modeling

  1. Contributions in Radio Channel Sounding, Modeling, and Estimation

    DEFF Research Database (Denmark)

    Pedersen, Troels

    2009-01-01

    This thesis spans over three strongly related topics in wireless communication: channel-sounding, -modeling, and -estimation. Three main problems are addressed: optimization of spatio-temporal apertures for channel sounding; estimation of per-path power spectral densities (psds); and modeling of...... reverberant channels. We develop a theory for optimization of spatio-temporal apertures used in multiple-input multiple-output (MIMO) channel sounding. Initially, we focus on joint estimation of bi-direction and Doppler frequency from time-division multiplexing (TDM) MIMO measurements.  We introduce and...... analyze a bi-spatio-temporal ambiguity function for spatio-temporal channel sounding. The analysis reveals that by proper design of the spatio-temporal aperture, the maximum estimable Doppler frequency of a TDM-MIMO sounder is as high as that of a traditional single-input single-output sounder.  We give...

  2. Satellite Data Assimilation of Upper-Level Sounding Channels in HWRF with Two Diff erent Model Tops

    Institute of Scientific and Technical Information of China (English)

    邹晓蕾; 翁富忠; 林琳; 张邦林; 吴陈锋; 秦正坤

    2015-01-01

    The Advanced Microwave Sounding Unit-A (AMSU-A) onboard the NOAA satellites NOAA-18 and NOAA-19 and the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) MetOp-A, the hyperspectral Atmospheric Infrared Sounder (AIRS) onboard Aqua, the High resolution In-fraRed Sounder (HIRS) onboard NOAA-19 and MetOp-A, and the Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership (NPP) satellite provide upper-level sounding channels in tropical cyclone environments. Assimilation of these upper-level sounding channels data in the Hurricane Weather Research and Forecasting (HWRF) system with two diff erent model tops is investigated for the tropical storms Debby and Beryl and hurricanes Sandy and Isaac that occurred in 2012. It is shown that the HWRF system with a higher model top allows more upper-level microwave and infrared sounding channels data to be assimilated into HWRF due to a more accurate upper-level background profi le. The track and intensity forecasts produced by the HWRF data assimilation and forecast system with a higher model top are more accurate than those with a lower model top.

  3. A New Weighting Function for Estimating Microwave Sounding Unit Channel 4 Temperature Trends Simulated by CMIP5 Climate Models

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuanze; ZHENG Xiaogu; YANG Chi; LUO San

    2013-01-01

    A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project,Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV vl0).For the same CMIP5 model simulations,it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV,but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa,California) static weighting functions.The new static weighting function not only reduces the computational cost,but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function.This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics.Although not completely removed,this difference can be reduced using the proposed weighting function to some extent,especially over the tropics.This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions.This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.

  4. Modelling Hyperboloid Sound Scattering

    DEFF Research Database (Denmark)

    Burry, Jane; Davis, Daniel; Peters, Brady;

    2011-01-01

    The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering....

  5. Optimization of Spatiotemporal Apertures in Channel Sounding

    DEFF Research Database (Denmark)

    Pedersen, Troels; Pedersen, Claus; Yin, Xuefeng;

    2008-01-01

    In this paper we investigate the impact of the spatio-temporal aperture of a channel sounding system equipped with antenna arrays at the transmitter and receiver on the accuracy of joint estimation of Doppler frequency and bi-direction. The contribution of this work is three-fold. Firstly, we sta...

  6. Geographic variation in Puget Sound tidal channel planform geometry

    Science.gov (United States)

    Hood, W. Gregory

    2015-02-01

    Tidal channels are central elements of salt marsh hydrodynamics, sediment dynamics, and habitat. To develop allometric models predicting the number and size of tidal channels that could develop following salt marsh restoration, channels were digitized from aerial photographs of Puget Sound river delta marshes. Salt marsh area was the independent variable for all dependent channel planform metrics. Tidal channel allometry showed similar scaling exponents for channel planform metrics throughout Puget Sound, simplifying comparisons between locations. Y-intercepts of allometric relationships showed geographic variation, which multiple-regression indicated was associated with tidal range and storm significant wave height. Channel size and complexity were positively related to tidal range and negatively related to wave height. Four case studies, each with paired regions of similar tidal range and contrasting wave environments, further indicated wave environment affected channel geometry. Wave-mediated sediment delivery may be the mechanism involved, with wave-sheltered areas experiencing relative sediment deficits, such that some salt marshes in Puget Sound are already suffering sea-level rise impacts that are reflected in their channel network geometry.

  7. Virtual reproducing system for 5.1 channel surround sound

    Institute of Scientific and Technical Information of China (English)

    XIE Bosun; SHI Yong; XIE Zhiwen; GUAN Shanqun

    2005-01-01

    An improved virtual reproducing system for 5.1 channel surround sound and signal processing algorithm of the system are proposed. Firstly, by analyzing the sound field of virtual reproducing systems for 5.1 ch surround sound, it is proved that there are some defects in current systems, including narrow listening area, sound image direction distortion, timbre change in reproduction etc. Then from theoretical analysis, it is proposed that, by decreasing the separated angle between reproducing loudspeaker pair to ±15° and using signal processing algorithm with timbre equalization, the improved system can get rid of the defects of current systems. Additionally, the signal processing algorithm of improved system is also simple. The results of psychoacoustic experiment verify theoretical analysis, and show that improved system is able to recreate sound image in half of horizontal plane (about ±90°) in the front. Finally, the system and its arrangement of loudspeakers are suitable to be used in TV sets or multimedia computers.

  8. Models of ancient sound vases

    Science.gov (United States)

    Bruel, Per V.

    2002-11-01

    Models were made of vases described by Vitruvius in Rome in about the year 70 A.D. and of sound vases (lydpotter) placed in Danish churches from 1100-1300 A.D. Measurements of vase's resonant frequencies and damping (reradiation) verified that the model vases obeyed expected physical rules. It was concluded that the excellent acoustical quality of many ancient Greek and Roman theaters cannot be ascribed to the vases placed under their seats. This study also found that sound vases placed in Nordic churches could not have shortened the reverberation time because there are far too few of them. Moreover, they could not have covered a broad frequency range. It remains a mystery why vases were installed under the seats of ancient Greek theaters and why, 1000 years later, Danes placed vases in their churches.

  9. On the Sediment Dynamics in a Tidally Energetic Channel: The Inner Sound, Northern Scotland

    Directory of Open Access Journals (Sweden)

    Jason McIlvenny

    2016-04-01

    Full Text Available Sediment banks within a fast-flowing tidal channel, the Inner Sound in the Pentland Firth, were mapped using multi-frequency side-scan sonar. This novel technique provides a new tool for seabed sediment and benthic habitat mapping. The sonar data are supplemented by sediment grab and ROV videos. The combined data provide detailed maps of persistent sand and shell banks present in the Sound despite the high energy environment. Acoustic Doppler Current Profiler (ADCP data and numerical model predictions were used to understand the hydrodynamics of the system. By combining the hydrodynamics and sediment distribution data, we explain the sediment dynamics in the area. Sediment particle shape and density, coupled with persistent features of the hydrodynamics, are the key factors in the distribution of sediment within the channel. Implications for tidal energy development planned for the Sound are discussed.

  10. Broadband unidirectional transmission of sound in unblocked channel

    Science.gov (United States)

    Zhu, Yi-Fan; Zou, Xin-Ye; Liang, Bin; Cheng, Jian-Chun

    2015-04-01

    We have designed and experimentally fabricated a straight channel capable of realizing unidirectional acoustic transmission within a broad band while leaving a gap much wider than the wavelength that may serve as a passage for other entities such as fluids or objects. This extraordinary feature stems from a distinctly different mechanism that directs the sound path asymmetrically by employing acoustic metasurfaces. The numerical and experimental results agree quite well with the theoretical predictions. Our scheme may open up avenue for the design of acoustic one-way devices and have potentials in various applications such as architectural acoustics or medical ultrasound.

  11. Channel Sounding for the Masses: Low Complexity GNU 802.11b Channel Impulse Response Estimation

    CERN Document Server

    Firooz, Mohammad H; Zhang, Junxing; Patwari, Neal; Kasera, Sneha K

    2010-01-01

    New techniques in cross-layer wireless networks are building demand for ubiquitous channel sounding, that is, the capability to measure channel impulse response (CIR) with any standard wireless network and node. Towards that goal, we present a software-defined IEEE 802.11b receiver and CIR estimation system with little additional computational complexity compared to 802.11b reception alone. The system implementation, using the universal software radio peripheral (USRP) and GNU Radio, is described and compared to previous work. By overcoming computational limitations and performing direct-sequence spread-spectrum (DS-SS) matched filtering on the USRP, we enable high-quality yet inexpensive CIR estimation. We validate the channel sounder and present a drive test campaign which measures hundreds of channels between WiFi access points and an in-vehicle receiver in urban and suburban areas.

  12. Accuracy Assessments of ATMS Upper-Level Temperature Sounding Channels Using COSMIC RO Data

    Science.gov (United States)

    Lin, L.; Weng, F.; Zou, X.

    2012-12-01

    The Advanced Technology Microwave Sounder (ATMS) on board Suomi National Polar-orbiting Partnership (NPP) is a 22-channel passive microwave radiometer that can provide high-spatial-resolution data for generating temperature and moisture soundings in cloudy conditions. Global Positioning System (GPS) radio occultation (RO) data have high vertical resolution, are not affected by clouds, and are most accurate from 8 to 30 km, making them ideally suited for estimating the precision of ATMS measurements for upper level temperature sounding channels. In this study, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO data are collocated with ATMS observation from December 10, 2011 to June 30, 2012. Compared with GPS simulations using the U.S. Joint Center of Satellite Data Assimilation (JCSDA) Community Radiative Transfer Model (CRTM), the global biases of brightness temperatures from ATMS measurements are within 0.5K for channels 6 to 13 for clear-sky data over ocean. This value is well within the pre-launch specification, indicating that the ATMS upper level temperature sounding channels have high accuracy. The monthly variation and angular dependence of ATMS bias are also examined.

  13. Sound

    CERN Document Server

    Robertson, William C

    2003-01-01

    Muddled about what makes music? Stuck on the study of harmonics? Dumbfounded by how sound gets around? Now you no longer have to struggle to teach concepts you really don t grasp yourself. Sound takes an intentionally light touch to help out all those adults science teachers, parents wanting to help with homework, home-schoolers seeking necessary scientific background to teach middle school physics with confidence. The book introduces sound waves and uses that model to explain sound-related occurrences. Starting with the basics of what causes sound and how it travels, you'll learn how musical instruments work, how sound waves add and subtract, how the human ear works, and even why you can sound like a Munchkin when you inhale helium. Sound is the fourth book in the award-winning Stop Faking It! Series, published by NSTA Press. Like the other popular volumes, it is written by irreverent educator Bill Robertson, who offers this Sound recommendation: One of the coolest activities is whacking a spinning metal rod...

  14. Sound propagation in two-axis underwater channel based on beam-displacement ray-mode theory

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in horizontally stratified shallow water. An improved method for computing the upper boundary reflection coefficient in the BDRM is proposed and applied to calculate the acoustic fields of a two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated in the new BDRM. The corresponding results are in good agreement with those from the Kraken code, and furthermore the computed speed of the new BDRM excels the other methods.

  15. Spatial distribution of sound channel and its parameters in north Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ashalatha, K.; Murty, T.V.R.; Prasad, K.V.S.R.

    Structure and SOFAR Channel Depth in the Indian Ocean.” Journal of Ship Technology (5): 53-72. [16] Hareeshkumar, P. V. 2013. “The Sound Channel Characteristics in the South Central Bay of Bengal.” International Journal of Innovative Technology...

  16. Extraction of auditory features and elicitation of attributes for the assessment of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Choisel, Sylvain; Wickelmaier, Florian

    2005-01-01

    The identification of relevant auditory attributes is pivotal in sound quality evaluation. Two fundamentally different psychometric methods were employed to uncover perceptually relevant auditory features of multi-channel reproduced sound. In the first method, called Repertory Grid Technique (RGT...

  17. Three-dimensional Sound Source Localization Using Inter-channel Time Difference Trajectory

    Directory of Open Access Journals (Sweden)

    Sangmoon Lee

    2015-12-01

    Full Text Available Sound source localization is one of the basic and essential techniques for intelligent robots in terms of human-robot interaction and has been utilized in various engineering fields. This paper suggests a new localization method using an inter-channel time difference trajectory, which is a new localization cue for efficient 3-D localization. As one of the ways to realize the proposed cue, a two-channel rotating array is employed. Two microphones are attached on the left and right sides of the spherical head. One microphone is in a circular motion on the right side, while the other is fixed on the left side. According to the rotating motion of the array, the (source direction-dependent characteristics of the trajectories are analysed using the Ray-Tracing formula extended for 3-D models. In simulation, the synthesized signals generated by the fixed and rotating microphone signal models were used as the output signals of the two microphones. The simulation showed that the localization performance is strongly dependent on the azimuthal position of a source, which is caused by the asymmetry of the trajectory amplitude. Additionally, the experimental results of the two experiments carried out in the room environment demonstrated that the proposed system can localize a Gaussian noise source and a voice source in 3-D space.

  18. EXPERIMENTAL INVESTIGATION ON SOUND SPEED PROPAGATING THROUGH HIGH SPEED AERATED FLOW IN OPEN CHANNEL

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experiment concerning the sound propaga-tion in aerated open channel flow was designed and conductedin a variable slope chute. The acquisition of sound data wasdone by the hydro-phones installed into the bottom wall of thechute. The data were analyzed and processed by the tape re-corder and a 3562A analyzer. The primary experimetal resultsindicated that the sound speed in aerated flow is varied with the air concentration and highly lower than each of the soundspeed in pure water or air. As released by the derived theoryformula, the minimum sound of 24m/s in aerated flow hap-pened when the air concentration achieved to 50%. This resultshows that the compressibility of high speed aerated flowshould be considered when the air concentration is near to50%. A criterion of compressibility of high speed aerated flowwas also giv. En in this paper.

  19. Proton channel models

    OpenAIRE

    Pupo, Amaury; Baez-Nieto, David; Martínez, Agustín; Latorre, Ramón; González, Carlos

    2014-01-01

    Voltage-gated proton channels are integral membrane proteins with the capacity to permeate elementary particles in a voltage and pH dependent manner. These proteins have been found in several species and are involved in various physiological processes. Although their primary topology is known, lack of details regarding their structures in the open conformation has limited analyses toward a deeper understanding of the molecular determinants of their function and regulation. Consequently, the f...

  20. Sound

    CERN Document Server

    2013-01-01

    Sound has the power to soothe, excite, warn, protect, and inform. Indeed, the transmission and reception of audio signals pervade our daily lives. Readers will examine the mechanics and properties of sound and provides an overview of the "interdisciplinary science called acoustics." Also covered are functions and diseases of the human ear.

  1. Wireless Channel Propagation Models Evaluation

    OpenAIRE

    Raikel Bordón López; Reinier Alonso Quintana; Samuel Montejo Sánchez

    2012-01-01

    In the design of wireless communications systems, channel modelling is an efficient alternative to predict the path loss. In this paper we present a comparative study between Okumura, Hata, Walfisch-Bertoni and Walfisch-Ikegami propagation models. We present a developed software tool, which is useful to evaluate these models from a graphical user interface. The main objective is to analyze and compare path loss predictions, taking into account different environment conditions and a common val...

  2. Analysis of simulated engine sounds using a psychoacoustic model

    Science.gov (United States)

    Duvigneau, Fabian; Liefold, Steffen; Höchstetter, Marius; Verhey, Jesko L.; Gabbert, Ulrich

    2016-03-01

    The aim of the paper is the evaluation and the prediction of the perceived quality of engine sounds, which is predicted in the design process by numerical simulations. Periodic combustion sounds of the operating engine are synthesized with the help of an overall numerical simulation approach before a real prototype exists. The perceived quality of the sound is rated in hearing tests using the method of relative comparison and absolute judgment. Results are transferred into an interval scaled ranking of the stimuli. Based on the data, a psychoacoustic model for sound quality is developed using psychoacoustic parameters. Predictions of this model are used to evaluate the sound quality of several technical design modifications, for example, different engine encapsulations. The results are visualized to allow a simple qualitative analysis of the sound perception. This results in an impartial and objective decision regarding the final design of an acoustic encapsulation with a higher perceived sound quality.

  3. Mobile Radio Channels Modeling in MATLAB

    OpenAIRE

    N. Kostov

    2003-01-01

    In this paper, a MATLAB based approach for mobile radio channels modeling is presented. Specifically, the paper introduces the basic concepts for modeling flat fading channels in MATLAB by means of user-defined m-files. Typical small-scale fading channel models are derived such as uncorrelated Rician fading channel and Rayleigh fading channel with Doppler shift. Further, simple and useful MATLAB constructions for approximation of cumulative distribution functions (CDFs) and probability densit...

  4. Ultrawideband VNA Based Channel Sounding System for Centimetre and Millimetre Wave Bands

    DEFF Research Database (Denmark)

    Hejselbæk, Johannes; Fan, Wei; Pedersen, Gert F.

    2016-01-01

    Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations of an exi...... utilizing the proposed setup equipped with rotational directive horn antennas, with a focus on multi-band power-angle-delay profiles, was performed. The measured frequency bands are 18 - 20 GHz, 25 - 27 GHz, 28 - 30 GHz and 38 - 40 GHz.......Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations...... of an existing vector network analyzer (VNA) based channel sounding system in terms of frequency range and measurement range. After that, an improved system is proposed to address these limitations. The proposed system is capable of measuring from 2 to 50 GHz at 30 meters distances. A measurement campaign...

  5. A computational model of cardiovascular physiology and heart sound generation.

    Science.gov (United States)

    Watrous, Raymond L

    2009-01-01

    A computational model of the cardiovascular system is described which provides a framework for implementing and testing quantitative physiological models of heart sound generation. The lumped-parameter cardiovascular model can be solved for the hemodynamic variables on which the heart sound generation process is built. Parameters of the cardiovascular model can be adjusted to represent various normal and pathological conditions, and the acoustic consequences of those adjustments can be explored. The combined model of the physiology of cardiovascular circulation and heart sound generation has promise for application in teaching, training and algorithm development in computer-aided auscultation of the heart.

  6. Optimal models of sound localization by barn owls

    OpenAIRE

    Fischer, Brian J

    2009-01-01

    Sound localization by barn owls is commonly modeled as a matching procedure where localization cues derived from auditory inputs are compared to stored templates. While the matching models can explain properties of neural responses, no model explains how the owl resolves spatial ambiguity in the localization cues to produce accurate localization for sources near the center of gaze. Here, I examine two models for the barn owl’s sound localization behavior. First, I consider a maximum likeli...

  7. Second-sound studies of coflow and counterflow of superfluid 4He in channels

    International Nuclear Information System (INIS)

    We report a comprehensive study of turbulent superfluid 4He flow through a channel of square cross section. We study for the first time two distinct flow configurations with the same apparatus: coflow (normal and superfluid components move in the same direction), and counterflow (normal and superfluid components move in opposite directions). We realise also a variation of counterflow with the same relative velocity, but where the superfluid component moves while there is no net flow of the normal component through the channel, i.e., pure superflow. We use the second-sound attenuation technique to measure the density of quantised vortex lines in the temperature range 1.2 K ≲ T ≲ Tλ ≈ 2.18 K and for flow velocities from about 1 mm/s up to almost 1 m/s in fully developed turbulence. We find that both the steady-state and temporal decay of the turbulence significantly differ in the three flow configurations, yielding an interesting insight into two-fluid hydrodynamics. In both pure superflow and counterflow, the same scaling of vortex line density with counterflow velocity is observed, L∝Vcf2, with a pronounced temperature dependence; in coflow instead, the vortex line density scales with velocity as L ∝ V3/2 and is temperature independent; we provide theoretical explanations for these observations. Further, we develop a new promising technique to use different second-sound resonant modes to probe the spatial distribution of quantised vortices in the direction perpendicular to the flow. Preliminary measurements indicate that coflow is less homogeneous than counterflow/superflow, with a denser concentration of vortices between the centre of the channel and its walls

  8. Degenerate RFID Channel Modeling for Positioning Applications

    Directory of Open Access Journals (Sweden)

    A. Povalac

    2012-12-01

    Full Text Available This paper introduces the theory of channel modeling for positioning applications in UHF RFID. It explains basic parameters for channel characterization from both the narrowband and wideband point of view. More details are given about ranging and direction finding. Finally, several positioning scenarios are analyzed with developed channel models. All the described models use a degenerate channel, i.e. combined signal propagation from the transmitter to the tag and from the tag to the receiver.

  9. Selecting participants for listening tests of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Wickelmaier, Florian; Choisel, Sylvain

    2005-01-01

    A selection procedure was devised in order to select listeners for experiments in which their main task will be to judge multi-channel reproduced sound. 91 participants filled in a web-based questionnaire. 78 of them took part in an assessment of their hearing thresholds, their spatial hearing, and...... their verbal production abilities. The listeners displayed large individual differences in their performance. 40 subjects were selected based on the test results. The self-assessed listening habits and experience in the web questionnaire could not predict the results of the selection procedure. Further......, the hearing thresholds did not correlate with the spatial-hearing test. This leads to the conclusion that task-specific performance tests might be the preferable means of selecting a listening panel....

  10. Box model for channels of human migration

    CERN Document Server

    Vitanov, Nikolay K

    2016-01-01

    We discuss a mathematical model of migration channel based on the truncated Waring distribution. The truncated Waring distribution is obtained for a more general model of motion of substance through a channel containing finite number of boxes. The model is applied then for case of migrants moving through a channel consisting of finite number of countries or cities. The number of migrants in the channel strongly depends on the number of migrants that enter the channel through the country of entrance. It is shown that if the final destination country is very popular then large percentage of migrants may concentrate there.

  11. Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 - 75 km altitude

    Science.gov (United States)

    Dickson, S.; Gausa, M. A.; Robertson, S. H.; Sternovsky, Z.

    2012-12-01

    We demonstrate that a channel electron multiplier (CEM) can be operated on a sounding rocket in the pulse-counting mode from 120 km to 75 km altitude without the cryogenic evacuation used in the past. Evacuation of the CEM is provided only by aerodynamic flow around the rocket. This demonstration is motivated by the need for additional flights of mass spectrometers to clarify the fate of metallic compounds and ions ablated from micrometeorites and their possible role in the nucleation of noctilucent clouds. The CEMs were flown as guest instruments on the two sounding rockets of the CHAMPS (CHarge And mass of Meteoritic smoke ParticleS) rocket campaign which were launched into the mesosphere in October 2011 from Andøya Rocket Range, Norway. Modeling of the aerodynamic flow around the payload with Direct Simulation Monte-Carlo (DSMC) code showed that the pressure is reduced below ambient in the void beneath an aft-facing surface. An enclosure containing the CEM was placed above an aft-facing deck and a valve was opened on the downleg to expose the CEM to the aerodynamically evacuated region below. The CEM operated successfully from apogee down to ~75 km. A Pirani gauge confirmed pressures reduced to as low as 20% of ambient with the extent of reduction dependent upon altitude and velocity. Additional DSMC simulations indicate that there are alternate payload designs with improved aerodynamic pumping for forward mounted instruments such as mass spectrometers.

  12. Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 to 80 km altitude

    Science.gov (United States)

    Dickson, Shannon; Gausa, Michael; Robertson, Scott; Sternovsky, Zoltan

    2013-04-01

    We demonstrate that a channel electron multiplier (CEM) can be operated on a sounding rocket in the pulse-counting mode from 120 km to 80 km altitude without the cryogenic evacuation used in the past. Evacuation of the CEM is provided only by aerodynamic flow around the rocket. This demonstration is motivated by the need for additional flights of mass spectrometers to clarify the fate of metallic compounds and ions ablated from micrometeorites and their possible role in the nucleation of noctilucent clouds. The CEMs were flown as guest instruments on two sounding rockets to the mesosphere. Modeling of the aerodynamic flow around the payload with Direct Simulation Monte-Carlo (DSMC) code showed that the pressure is reduced below ambient in the void behind (relative to the direction of motion) an aft-facing surface. An enclosure containing the CEM was placed forward of an aft-facing deck and a valve was opened during flight to expose the CEM to the aerodynamically evacuated region behind it. The CEM operated successfully from apogee down to ∼80 km. A Pirani gauge confirmed pressures reduced to as low as 20% of ambient with the extent of reduction dependent upon altitude and velocity. Additional DSMC simulations indicate that there are alternate payload designs with improved aerodynamic pumping for forward mounted instruments such as mass spectrometers.

  13. Modeling huge sound sources in a room acoustical calculation program

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge

    1999-01-01

    A room acoustical model capable of modeling point sources, line sources, and surface sources is presented. Line and surface sources are modeled using a special ray-tracing algorithm detecting the radiation pattern of the surfaces of the room. Point sources are modeled using a hybrid calculation...... method combining this ray-tracing method with image source modeling. With these three source types it is possible to model huge and complex sound sources in industrial environments. Compared to a calculation with only point sources, the use of extended sound sources is shown to improve the agreement with...

  14. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  15. A corticothalamic circuit model for sound identification in complex scenes.

    Directory of Open Access Journals (Sweden)

    Gonzalo H Otazu

    Full Text Available The identification of the sound sources present in the environment is essential for the survival of many animals. However, these sounds are not presented in isolation, as natural scenes consist of a superposition of sounds originating from multiple sources. The identification of a source under these circumstances is a complex computational problem that is readily solved by most animals. We present a model of the thalamocortical circuit that performs level-invariant recognition of auditory objects in complex auditory scenes. The circuit identifies the objects present from a large dictionary of possible elements and operates reliably for real sound signals with multiple concurrently active sources. The key model assumption is that the activities of some cortical neurons encode the difference between the observed signal and an internal estimate. Reanalysis of awake auditory cortex recordings revealed neurons with patterns of activity corresponding to such an error signal.

  16. Indoor MIMO Channel Measurement and Modeling

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Andersen, Jørgen Bach

    2005-01-01

    Forming accurate models of the multiple input multiple output (MIMO) channel is essential both for simulation as well as understanding of the basic properties of the channel. This paper investigates different known models using measurements obtained with a 16x32 MIMO channel sounder for the 5.8GHz...... accurate model for Gaussian channels. For each of the environments different sizes of both the transmitter and receiver antenna arrays are investigated, 2x2 up to 16x32. Generally it was found that in terms of capacity cumulative distribution functions (CDFs) all models fit well for small array sizes, but...

  17. Modeling Large sound sources in a room acoustical calculation program

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge

    1999-01-01

    A room acoustical model capable of modelling point, line and surface sources is presented. Line and surface sources are modelled using a special ray-tracing algorithm detecting the radiation pattern of the surfaces in the room. Point sources are modelled using a hybrid calculation method combining...... this ray-tracing method with Image source modelling. With these three source types, it is possible to model large and complex sound sources in workrooms....

  18. A High Resolution Hydrodynamic Model of Puget Sound to Support Nearshore Restoration Feasibility Analysis and Design

    International Nuclear Information System (INIS)

    Estuarine and coastal hydrodynamic processes are sometimes neglected in the design and planning of nearshore restoration actions. Despite best intentions, efforts to restore nearshore habitats can result in poor outcomes if circulation and transport which also affect freshwater-saltwater interactions are not properly addressed. Limitations due to current land use can lead to selection of sub-optimal restoration alternatives that may result in undesirable consequences, such as flooding, deterioration of water quality, and erosion, requiring immediate remedies and costly repairs. Uncertainty with achieving restoration goals, such as recovery of tidal exchange, supply of sediment and nutrients, and establishment of fish migration pathways, may be minimized by using numerical models designed for application to the nearshore environment. A high resolution circulation and transport model of the Puget Sound, in the state of Washington, was developed to assist with nearshore habitat restoration design and analysis, and to answer the question 'can we achieve beneficial restoration outcomes at small local scale, as well as at a large estuary-wide scale?' The Puget Sound model is based on an unstructured grid framework to define the complex Puget Sound shoreline using a finite volume coastal ocean model (FVCOM). The capability of the model for simulating the important nearshore processes, such as circulation in complex multiple tidal channels, wetting and drying of tide flats, and water quality and sediment transport as part of restoration feasibility, are illustrated through examples of restoration projects in Puget Sound.

  19. Numerical Models for Sound Propagation in Long Spaces

    Science.gov (United States)

    Lai, Chenly Yuen Cheung

    Both reverberation time and steady-state sound field are the key elements for assessing the acoustic condition in an enclosed space. They affect the noise propagation, speech intelligibility, clarity index, and definition. Since the sound field in a long space is non diffuse, classical room acoustics theory does not apply in this situation. The ray tracing technique and the image source methods are two common models to fathom both reverberation time and steady-state sound field in long enclosures nowadays. Although both models can give an accurate estimate of reverberation times and steady-state sound field directly or indirectly, they often involve time-consuming calculations. In order to simplify the acoustic consideration, a theoretical formulation has been developed for predicting both steady-state sound fields and reverberation times in street canyons. The prediction model is further developed to predict the steady-state sound field in a long enclosure. Apart from the straight long enclosure, there are other variations such as a cross junction, a long enclosure with a T-intersection, an U-turn long enclosure. In the present study, an theoretical and experimental investigations were conducted to develop formulae for predicting reverberation times and steady-state sound fields in a junction of a street canyon and in a long enclosure with T-intersection. The theoretical models are validated by comparing the numerical predictions with published experimental results. The theoretical results are also compared with precise indoor measurements and large-scale outdoor experimental results. In all of previous acoustical studies related to long enclosure, most of the studies are focused on the monopole sound source. Besides non-directional noise source, many noise sources in long enclosure are dipole like, such as train noise and fan noise. In order to study the characteristics of directional noise sources, a review of available dipole source was conducted. A dipole was

  20. Modelling Large sound sources in a room acoustical calculation program

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge

    1999-01-01

    A room acoustical model capable of modelling point, line and surface sources is presented. Line and surfacesources are modelled using a special ray-tracing algorithm detecting the radiation pattern of the surfaces in the room.Point sources are modelled using a hybrid calculation method combining...... this ray-tracing method with Image sourcemodelling. With these three source types, it is possible to model large and complex sound sources in workrooms....

  1. A model to predict the sound reflection from forests

    NARCIS (Netherlands)

    Wunderli, J.M.; Salomons, E.M.

    2009-01-01

    A model is presented to predict the reflection of sound at forest edges. A single tree is modelled as a vertical cylinder. For the reflection at a cylinder an analytical solution is given based on the theory of scattering of spherical waves. The entire forest is represented by a line of cylinders pl

  2. Mobile Radio Channels Modeling in MATLAB

    Directory of Open Access Journals (Sweden)

    N. Kostov

    2003-12-01

    Full Text Available In this paper, a MATLAB based approach for mobile radio channelsmodeling is presented. Specifically, the paper introduces the basicconcepts for modeling flat fading channels in MATLAB by means ofuser-defined m-files. Typical small-scale fading channel models arederived such as uncorrelated Rician fading channel and Rayleigh fadingchannel with Doppler shift. Further, simple and useful MATLABconstructions for approximation of cumulative distribution functions(CDFs and probability density functions (PDFs are also given.Finally, a MATLAB based Monte Carlo simulation example is presented,which comprises performance estimation of phase shift keying (PSKsignaling over a Rician fading channel.

  3. Sound Hole Sound

    CERN Document Server

    Politzer, David

    2015-01-01

    The volume of air that goes in and out of a musical instrument's sound hole is related to the sound hole's contribution to the volume of the sound. Helmholtz's result for the simplest case of steady flow through an elliptical hole is reviewed. Measurements on multiple holes in sound box geometries and scales relevant to real musical instruments demonstrate the importance of a variety of effects. Electric capacitance of single flat plates is a mathematically identical problem, offering an alternate way to understand the most important of those effects. The measurements also confirm and illuminate aspects of Helmholtz's "bottle" resonator model as applied to musical instrument sound boxes and sound holes.

  4. THEORETICAL MODEL OF VIBRATING OBJECT TRANSMITTING NOISE TOWARDS EXTERNAL SOUND

    Institute of Scientific and Technical Information of China (English)

    姚志远

    2002-01-01

    On the basic theory of modal method, the coupling relation between the vibration of objects and external sound was analyzed, the theoretical model solving the vibration and noise was provided, the corresponding calculation formula was given. The calculating results show out that this calculation formula is correct.

  5. On the development of approximate models for outdoor sound propagation

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo

    1998-01-01

    The suitable prediction model for outdoor sound propagation depends on the situation and the application. Computationally intensive method such as Parabolic Equation methods, FFP methods and Boundary Element Methods all have advantages in certain situations. None of these approaches are at present...

  6. On the applicability of models for outdoor sound

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo

    1999-01-01

    The suitable prediction model for outdoor sound fields depends on the situation and the application. Computationally intensive methods such as Parabolic Equation methods, FFP methods and Boundary Element Methods all have advantages in certain situations. These approaches are accurate and predict...

  7. On the applicability of models for outdoor sound (A)

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo

    1999-01-01

    The suitable prediction model for outdoor sound fields depends on the situation and the application. Computationally intensive methods such as parabolic equation methods, FFP methods, and boundary element methods all have advantages in certain situations. These approaches are accurate and predict...

  8. Statistical modeling of bowing control applied to violin sound synthesis

    OpenAIRE

    Maestre E.; Blaauw M.; Bonada J.; Guaus E.; Perez A.

    2010-01-01

    Excitation-continuous music instrument control patterns are often not explicitly represented in current sound synthesis techniques when applied to automatic performance. Both physical model-based and sample-based synthesis paradigms would benefit from a flexible and accurate instrument control model, enabling the improvement of naturalness and realism. We present a framework for modeling bowing control parameters in violin performance. Nearly non-intrusive sensing techniques allow fo...

  9. Quantum Biological Channel Modeling and Capacity Calculation

    Directory of Open Access Journals (Sweden)

    Ivan B. Djordjevic

    2012-12-01

    Full Text Available Quantum mechanics has an important role in photosynthesis, magnetoreception, and evolution. There were many attempts in an effort to explain the structure of genetic code and transfer of information from DNA to protein by using the concepts of quantum mechanics. The existing biological quantum channel models are not sufficiently general to incorporate all relevant contributions responsible for imperfect protein synthesis. Moreover, the problem of determination of quantum biological channel capacity is still an open problem. To solve these problems, we construct the operator-sum representation of biological channel based on codon basekets (basis vectors, and determine the quantum channel model suitable for study of the quantum biological channel capacity and beyond. The transcription process, DNA point mutations, insertions, deletions, and translation are interpreted as the quantum noise processes. The various types of quantum errors are classified into several broad categories: (i storage errors that occur in DNA itself as it represents an imperfect storage of genetic information, (ii replication errors introduced during DNA replication process, (iii transcription errors introduced during DNA to mRNA transcription, and (iv translation errors introduced during the translation process. By using this model, we determine the biological quantum channel capacity and compare it against corresponding classical biological channel capacity. We demonstrate that the quantum biological channel capacity is higher than the classical one, for a coherent quantum channel model, suggesting that quantum effects have an important role in biological systems. The proposed model is of crucial importance towards future study of quantum DNA error correction, developing quantum mechanical model of aging, developing the quantum mechanical models for tumors/cancer, and study of intracellular dynamics in general.

  10. Relationship between sound radiation from sound-induced and force-excited vibration: Analysis using an infinite elastic plate model.

    Science.gov (United States)

    Yairi, Motoki; Sakagami, Kimihiro; Nishibara, Kosuke; Okuzono, Takeshi

    2016-07-01

    Although sound radiation from sound-induced vibration and from force-excited vibration of solid structures are similar phenomena in terms of radiating from vibrating structures, the general relationship between them has not been explicitly studied to date. In particular, airborne sound transmission through walls and sound radiation from structurally vibrating surfaces in buildings are treated as different issues in architectural acoustics. In this paper, a fundamental relationship is elucidated through the use of a simple model. The transmission coefficient for random-incidence sound and the radiated sound power under point force excitation of an infinite elastic plate are both analyzed. Exact and approximate solutions are derived for the two problems, and the relationship between them is theoretically discussed. A conversion function that relates the transmission coefficient and radiated sound power is obtained in a simple closed form through the approximate solutions. The exact solutions are also related by the same conversion function. It is composed of the specific impedance and the wavenumber, and is independent of any elastic plate parameters. The sound radiation due to random-incidence sound and point force excitation are similar phenomena, and the only difference is the gradient of those characteristics with respect to the frequency. PMID:27475169

  11. Beyond harmonic sounds in a simple model for birdsong production

    Science.gov (United States)

    Amador, Ana; Mindlin, Gabriel B.

    2008-12-01

    In this work we present an analysis of the dynamics displayed by a simple bidimensional model of labial oscillations during birdsong production. We show that the same model capable of generating tonal sounds can present, for a wide range of parameters, solutions which are spectrally rich. The role of physiologically sensible parameters is discussed in each oscillatory regime, allowing us to interpret previously reported data.

  12. Discrete stochastic modeling of calcium channel dynamics

    CERN Document Server

    Baer, M E; Levine, H; Tsimring, L S; Baer, Markus; Falcke, Martin; Levine, Herbert; Tsimring, Lev S.

    1999-01-01

    We propose a simple discrete stochastic model for calcium dynamics in living cells. Specifically, the calcium concentration distribution is assumed to give rise to a set of probabilities for the opening/closing of channels which release calcium thereby changing those probabilities. We study this model in one dimension, analytically in the mean-field limit of large number of channels per site N, and numerically for small N. As the number of channels per site is increased, the transition from a non-propagating region of activity to a propagating one changes in nature from one described by directed percolation to that of deterministic depinning in a spatially discrete system. Also, for a small number of channels a propagating calcium wave can leave behind a novel fluctuation-driven state, in a parameter range where the limiting deterministic model exhibits only single pulse propagation.

  13. Ormiaochracea as a Model Organism in Sound Localization Experiments and in Inventing Hearing Aids.

    Directory of Open Access Journals (Sweden)

    - -

    1998-09-01

    Full Text Available Hearing aid prescription for patients suffering hearing loss has always been one of the main concerns of the audiologists. Thanks to technology that has provided Hearing aids with digital and computerized systems which has improved the quality of sound heard by hearing aids. Though we can learn from nature in inventing such instruments as in the current article that has been channeled to a kind of fruit fly. Ormiaochracea is a small yellow nocturnal fly, a parasitoid of crickets. It is notable because of its exceptionally acute directional hearing. In the current article we will discuss how it has become a model organism in sound localization experiments and in inventing hearing aids.

  14. Characteristics analyzing and parametric modeling of the arc sound in CO2 GMAW for on-line quality monitoring

    Institute of Scientific and Technical Information of China (English)

    Ma Yuezhou; Ma Wenbin; Qu Min; Chen Jianhong

    2006-01-01

    For on-line monitoring of welding quality, the characteristics of the arc sound signals in short circuit CO2 GMAW were analyzed in the time and frequency domains. The arc sound presents a series of ringing-like oscillations that occur at the end of short circuit i. e. the moment of arc re-ignition, and distributes mainly in the frequency band below 10 kHz. A concept of the arc tone channel and its equivalent electrical model were suggested, which is considered a time-dependent distributed parametric system of which the transmission properties depend upon the geometric and physical characteristics of the arc and surroundings, and is excited by the sound source results from the change of arc energy so that results in arc sound. The linear prediction coding ( LPC) model is an estimation of the tone channel. The radial basis function ( RBF) neural networks were built for on-line pattern recognition of the gas-lack in welding, in which the input vectors were formed with the LPC coefficients. The test results proved that the LPC model of arc sound and the RBF networks are feasible in on-line quality monitoring.

  15. Underwater Sound Propagation Modeling Methods for Predicting Marine Animal Exposure.

    Science.gov (United States)

    Hamm, Craig A; McCammon, Diana F; Taillefer, Martin L

    2016-01-01

    The offshore exploration and production (E&P) industry requires comprehensive and accurate ocean acoustic models for determining the exposure of marine life to the high levels of sound used in seismic surveys and other E&P activities. This paper reviews the types of acoustic models most useful for predicting the propagation of undersea noise sources and describes current exposure models. The severe problems caused by model sensitivity to the uncertainty in the environment are highlighted to support the conclusion that it is vital that risk assessments include transmission loss estimates with statistical measures of confidence.

  16. Discrete Stochastic Modeling of Calcium Channel Dynamics

    International Nuclear Information System (INIS)

    We propose a discrete stochastic model for calcium dynamics in living cells. A set of probabilities for the opening/closing of calcium channels is assumed to depend on the calcium concentration. We study this model in one dimension, analytically in the limit of a large number of channels per site N , and numerically for small N . As the number of channels per site is increased, the transition from a nonpropagating region of activity to a propagating one changes from one described by directed percolation to that of deterministic depinning in a spatially discrete system. Also, for a small number of channels a propagating calcium wave can leave behind a novel fluctuation-driven state. (c) 2000 The American Physical Society

  17. Spectral models for musical sound synthesis: Expression issues

    Science.gov (United States)

    Serra, Xavier

    2002-05-01

    In order to obtain a naturally sounding musical instrument or voice, we require sound models that can both capture the microstructure characteristics of the acoustical source and that at the same time can be controlled by meaningful parameters, in a similar way as the performers do. The issue of how to generate these control parameters is one of the most interesting and open problems in the area of musical sound synthesis. This presentation will focus on the control question in the context of two recently developed synthesizers based on a spectral modeling approach: a singing voice synthesizer and a wind instrument synthesizer. The specific spectral models used in each case will be presented followed by a discussion on the expression controls employed and how they are obtained from actual performances. These controls are mainly at the note and the note-to-note articulation level and affect parameters such as pitch, dynamics, brightness, and vibrato. From actual performances, templates and models of the temporal evolution of these parameters are extracted and then used as the basic controls of the synthesizer on top of which the user interacts in real time.

  18. A Neural Network Model for Prediction of Sound Quality

    DEFF Research Database (Denmark)

    Nielsen,, Lars Bramsløw

    An artificial neural network structure has been specified, implemented and optimized for the purpose of predicting the perceived sound quality for normal-hearing and hearing-impaired subjects. The network was implemented by means of commercially available software and optimized to predict results...... error on the test set. The overall concept proved functional, but further testing with data obtained from a new rating experiment is necessary to better assess the utility of this measure. The weights in the trained neural networks were analyzed to qualitatively interpret the relation between...... obtained in subjective sound quality rating experiments based on input data from an auditory model. Various types of input data and data representations from the auditory model were used as input data for the chosen network structure, which was a three-layer perceptron. This network was trained by means...

  19. Robust Sounds of Activities of Daily Living Classification in Two-Channel Audio-Based Telemonitoring

    Directory of Open Access Journals (Sweden)

    David Maunder

    2013-01-01

    Full Text Available Despite recent advances in the area of home telemonitoring, the challenge of automatically detecting the sound signatures of activities of daily living of an elderly patient using nonintrusive and reliable methods remains. This paper investigates the classification of eight typical sounds of daily life from arbitrarily positioned two-microphone sensors under realistic noisy conditions. In particular, the role of several source separation and sound activity detection methods is considered. Evaluations on a new four-microphone database collected under four realistic noise conditions reveal that effective sound activity detection can produce significant gains in classification accuracy and that further gains can be made using source separation methods based on independent component analysis. Encouragingly, the results show that recognition accuracies in the range 70%–100% can be consistently obtained using different microphone-pair positions, under all but the most severe noise conditions.

  20. Science Education Using a Computer Model-Virtual Puget Sound

    Science.gov (United States)

    Fruland, R.; Winn, W.; Oppenheimer, P.; Stahr, F.; Sarason, C.

    2002-12-01

    We created an interactive learning environment based on an oceanographic computer model of Puget Sound-Virtual Puget Sound (VPS)-as an alternative to traditional teaching methods. Students immersed in this navigable 3-D virtual environment observed tidal movements and salinity changes, and performed tracer and buoyancy experiments. Scientific concepts were embedded in a goal-based scenario to locate a new sewage outfall in Puget Sound. Traditional science teaching methods focus on distilled representations of agreed-upon knowledge removed from real-world context and scientific debate. Our strategy leverages students' natural interest in their environment, provides meaningful context and engages students in scientific debate and knowledge creation. Results show that VPS provides a powerful learning environment, but highlights the need for research on how to most effectively represent concepts and organize interactions to support scientific inquiry and understanding. Research is also needed to ensure that new technologies and visualizations do not foster misconceptions, including the impression that the model represents reality rather than being a useful tool. In this presentation we review results from prior work with VPS and outline new work for a modeling partnership recently formed with funding from the National Ocean Partnership Program (NOPP).

  1. Advanced Concepts for Underwater Acoustic Channel Modeling

    Science.gov (United States)

    Etter, P. C.; Haas, C. H.; Ramani, D. V.

    2014-12-01

    This paper examines nearshore underwater-acoustic channel modeling concepts and compares channel-state information requirements against existing modeling capabilities. This process defines a subset of candidate acoustic models suitable for simulating signal propagation in underwater communications. Underwater-acoustic communications find many practical applications in coastal oceanography, and networking is the enabling technology for these applications. Such networks can be formed by establishing two-way acoustic links between autonomous underwater vehicles and moored oceanographic sensors. These networks can be connected to a surface unit for further data transfer to ships, satellites, or shore stations via a radio-frequency link. This configuration establishes an interactive environment in which researchers can extract real-time data from multiple, but distant, underwater instruments. After evaluating the obtained data, control messages can be sent back to individual instruments to adapt the networks to changing situations. Underwater networks can also be used to increase the operating ranges of autonomous underwater vehicles by hopping the control and data messages through networks that cover large areas. A model of the ocean medium between acoustic sources and receivers is called a channel model. In an oceanic channel, characteristics of the acoustic signals change as they travel from transmitters to receivers. These characteristics depend upon the acoustic frequency, the distances between sources and receivers, the paths followed by the signals, and the prevailing ocean environment in the vicinity of the paths. Properties of the received signals can be derived from those of the transmitted signals using these channel models. This study concludes that ray-theory models are best suited to the simulation of acoustic signal propagation in oceanic channels and identifies 33 such models that are eligible candidates.

  2. Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang; Labiosa, Rochelle G.; Kim, Taeyun

    2010-11-30

    The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions.

  3. Numerical simulation of turbulence transition and sound radiation for flow through a rigid glottal model.

    Science.gov (United States)

    Suh, Jungsoo; Frankel, Steven H

    2007-06-01

    Large eddy simulation (LES)-based computational aeroacoustics techniques were applied to a static model of the human glottis, idealized here as a planar channel with an orifice, to study flow-acoustic interactions related to speech. Rigid models of both converging and diverging glottal passages, each featuring a 20 deg included angle and a minimal glottal diameter of 0.04 cm, with an imposed transglottal pressure of 15 cm H2O, were studied. The Favre-filtered compressible Navier-Stokes equations were integrated for this low-Mach-number flow using an additive semi-implicit Runge-Kutta method and a high-order compact finite-difference scheme with characteristic-based nonreflecting boundary conditions and a multiblock approach. Flow asymmetries related to the Coanda effect and transition to turbulence, as well as the far-field sound, were captured. Acoustic-analogy-based far-field sound predictions were compared with direct simulations and showed that dipole sources, arising from unsteady flow forces exerted on the glottal walls, are primarily responsible for the tonal sound observed in the divergent glottis case. PMID:17552723

  4. Time-shared channel identification for adaptive noise cancellation in breath sound extraction

    Institute of Scientific and Technical Information of China (English)

    Zheng HAN; Hong WANG; Leyi WANG; Gang George YIN

    2004-01-01

    Noise artifacts are one of the key obstacles in applying continuous monitoring and computer-assisted analysis of lung sounds.Traditional adaptive noise cancellation (ANC) methodologies work reasonably well when signal and noise are stationary and independent.Clinical lung sound auscultation encounters an acoustic environment in which breath sounds are not stationary and often correlate with noise.Consequently,capability of ANC becomes significantly compromised.This paper introduces a new methodology for extracting authentic lung sounds from noise-corrupted measurements.Unlike traditional noise cancellation methods that rely on either frequency band separation or signal/noise independence to achieve noise reduction,this methodology combines the traditional noise canceling methods with the unique feature of time-split stages in breathing sounds.By employing a multi-sensor system,the method first employs a high-pass filter to eliminate the off-band noise,and then performs time-shared blind identification and noise cancellation with recursion from breathing cycle to cycle.Since no frequency separation or signal/noise independence is required,this method potentially has a robust and reliable capability of noise reduction,complementing the traditional methods.

  5. A Simplified Model for Generating 3D Realistic Sound in the Multimedia and Virtual Reality Systems

    Institute of Scientific and Technical Information of China (English)

    赵Yu; 何志均; 等

    1996-01-01

    It is a key feature to embed 3D realistic sound effect in the future multimedia and virtual reality systems.Recent research on acoustics and psychoacoustics reveals the important cues for sound localization and sound perception.One promising approach to generate 3D realistic sound effect uses two earphones by simulating the sound waveforms from sound source to eardrum.This paper summarizes two methods for generating 3D realistic sound and points out their inherent drawbacks.To overcome these drawbacks we propose a simplified model to generate 3D realistic sound at any positions in the horizontal plane based on the results of sound perception and localization.Experimental results show that the model is correct and efficient.

  6. Propagation of detonation wave in hydrogen-air mixture in channels with sound-absorbing surfaces

    Science.gov (United States)

    Bivol, G. Yu.; Golovastov, S. V.; Golub, V. V.

    2015-12-01

    The possibility of using sound-absorbing surfaces for attenuating the intensity of detonation waves propagating in hydrogen-air mixtures has been experimentally studied in a cylindrical detonation tube open at one end, with an explosive initiated by spark discharge at the closed end. Sound-absorbing elements were made of an acoustic-grade foamed rubber with density of 0.035 g/cm3 containing open pores with an average diameter of 0.5 mm. The degree of attenuation of the detonation wave front velocity was determined as dependent on the volume fraction of hydrogen in the gas mixture.

  7. Swallowing sound detection using hidden markov modeling of recurrence plot features

    Energy Technology Data Exchange (ETDEWEB)

    Aboofazeli, Mohammad [Faculty of Engineering, Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)], E-mail: umaboofa@cc.umanitoba.ca; Moussavi, Zahra [Faculty of Engineering, Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)], E-mail: mousavi@ee.umanitoba.ca

    2009-01-30

    Automated detection of swallowing sounds in swallowing and breath sound recordings is of importance for monitoring purposes in which the recording durations are long. This paper presents a novel method for swallowing sound detection using hidden Markov modeling of recurrence plot features. Tracheal sound recordings of 15 healthy and nine dysphagic subjects were studied. The multidimensional state space trajectory of each signal was reconstructed using the Taken method of delays. The sequences of three recurrence plot features of the reconstructed trajectories (which have shown discriminating capability between swallowing and breath sounds) were modeled by three hidden Markov models. The Viterbi algorithm was used for swallowing sound detection. The results were validated manually by inspection of the simultaneously recorded airflow signal and spectrogram of the sounds, and also by auditory means. The experimental results suggested that the performance of the proposed method using hidden Markov modeling of recurrence plot features was superior to the previous swallowing sound detection methods.

  8. Modelling the sound transmission through partition walls using a diffusion model

    OpenAIRE

    Billon, A.; Foy, C; VALEAU, V; Picaut, J.; Sakout, A.

    2007-01-01

    The diffusion model has been used successfully to evaluate the acoustic behaviour of a system of coupled rooms connected through a coupling aperture. In this paper, an extension of this model is proposed to deal with the propagation of sound energy through a partition wall. The diffusion model can be considered as a extension of the statistical theory to none diffuse sound fields. Numerical comparisons with the statistical theory are then carried out. The following parameters are varied : its...

  9. NUMERICAL MODELING OF COMPOUND CHANNEL FLOWS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A numerical model capable of predicting flow characteristics in a compound channel was established with the 3-D steady continuity and momentum equations along with the transport equations for turbulence kinetic energy and dissipation rate. Closure was achieved with the aid of algebraic relations for turbulent shear stresses. The above equations were discretized with implicit difference approach and solved with a step method along the flow direction. The computational results showing the lateral distribution of vertical average velocities and the latio of total flow in the compound channel agree well with the available experimental data.

  10. Puget Sound steelhead life cycle model analyses - Population Viability Analysis

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This research was initiated by the Puget Sound Steelhead Technical Recovery Team to develop viability criteria for threatened Puget Sound steelhead and to support...

  11. A new notion of soundness in bare public-key model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yunlei; ZHU Hong

    2003-01-01

    A new notion of soundness in bare public-key (BPK) model is presented. This new notion just lies in between one-time soundness and sequential soundness and its reasonableness is justified in the context of resettable zero-knowledge when resettable zero-knowledge prover is implemented by smart card.

  12. Extended Nonnegative Tensor Factorisation Models for Musical Sound Source Separation

    Directory of Open Access Journals (Sweden)

    Derry FitzGerald

    2008-01-01

    Full Text Available Recently, shift-invariant tensor factorisation algorithms have been proposed for the purposes of sound source separation of pitched musical instruments. However, in practice, existing algorithms require the use of log-frequency spectrograms to allow shift invariance in frequency which causes problems when attempting to resynthesise the separated sources. Further, it is difficult to impose harmonicity constraints on the recovered basis functions. This paper proposes a new additive synthesis-based approach which allows the use of linear-frequency spectrograms as well as imposing strict harmonic constraints, resulting in an improved model. Further, these additional constraints allow the addition of a source filter model to the factorisation framework, and an extended model which is capable of separating mixtures of pitched and percussive instruments simultaneously.

  13. Modelling debris flows down general channels

    Directory of Open Access Journals (Sweden)

    S. P. Pudasaini

    2005-01-01

    Full Text Available This paper is an extension of the single-phase cohesionless dry granular avalanche model over curved and twisted channels proposed by Pudasaini and Hutter (2003. It is a generalisation of the Savage and Hutter (1989, 1991 equations based on simple channel topography to a two-phase fluid-solid mixture of debris material. Important terms emerging from the correct treatment of the kinematic and dynamic boundary condition, and the variable basal topography are systematically taken into account. For vanishing fluid contribution and torsion-free channel topography our new model equations exactly degenerate to the previous Savage-Hutter model equations while such a degeneration was not possible by the Iverson and Denlinger (2001 model, which, in fact, also aimed to extend the Savage and Hutter model. The model equations of this paper have been rigorously derived; they include the effects of the curvature and torsion of the topography, generally for arbitrarily curved and twisted channels of variable channel width. The equations are put into a standard conservative form of partial differential equations. From these one can easily infer the importance and influence of the pore-fluid-pressure distribution in debris flow dynamics. The solid-phase is modelled by applying a Coulomb dry friction law whereas the fluid phase is assumed to be an incompressible Newtonian fluid. Input parameters of the equations are the internal and bed friction angles of the solid particles, the viscosity and volume fraction of the fluid, the total mixture density and the pore pressure distribution of the fluid at the bed. Given the bed topography and initial geometry and the initial velocity profile of the debris mixture, the model equations are able to describe the dynamics of the depth profile and bed parallel depth-averaged velocity distribution from the initial position to the final deposit. A shock capturing, total variation diminishing numerical scheme is implemented to

  14. Lumped parametric model of the human ear for sound transmission.

    Science.gov (United States)

    Feng, Bin; Gan, Rong Z

    2004-09-01

    A lumped parametric model of the human auditoria peripherals consisting of six masses suspended with six springs and ten dashpots was proposed. This model will provide the quantitative basis for the construction of a physical model of the human middle ear. The lumped model parameters were first identified using published anatomical data, and then determined through a parameter optimization process. The transfer function of the middle ear obtained from human temporal bone experiments with laser Doppler interferometers was used for creating the target function during the optimization process. It was found that, among 14 spring and dashpot parameters, there were five parameters which had pronounced effects on the dynamic behaviors of the model. The detailed discussion on the sensitivity of those parameters was provided with appropriate applications for sound transmission in the ear. We expect that the methods for characterizing the lumped model of the human ear and the model parameters will be useful for theoretical modeling of the ear function and construction of the ear physical model.

  15. Lumped parametric model of the human ear for sound transmission.

    Science.gov (United States)

    Feng, Bin; Gan, Rong Z

    2004-09-01

    A lumped parametric model of the human auditoria peripherals consisting of six masses suspended with six springs and ten dashpots was proposed. This model will provide the quantitative basis for the construction of a physical model of the human middle ear. The lumped model parameters were first identified using published anatomical data, and then determined through a parameter optimization process. The transfer function of the middle ear obtained from human temporal bone experiments with laser Doppler interferometers was used for creating the target function during the optimization process. It was found that, among 14 spring and dashpot parameters, there were five parameters which had pronounced effects on the dynamic behaviors of the model. The detailed discussion on the sensitivity of those parameters was provided with appropriate applications for sound transmission in the ear. We expect that the methods for characterizing the lumped model of the human ear and the model parameters will be useful for theoretical modeling of the ear function and construction of the ear physical model. PMID:15300453

  16. The sound manifesto

    Science.gov (United States)

    O'Donnell, Michael J.; Bisnovatyi, Ilia

    2000-11-01

    Computing practice today depends on visual output to drive almost all user interaction. Other senses, such as audition, may be totally neglected, or used tangentially, or used in highly restricted specialized ways. We have excellent audio rendering through D-A conversion, but we lack rich general facilities for modeling and manipulating sound comparable in quality and flexibility to graphics. We need coordinated research in several disciplines to improve the use of sound as an interactive information channel. Incremental and separate improvements in synthesis, analysis, speech processing, audiology, acoustics, music, etc. will not alone produce the radical progress that we seek in sonic practice. We also need to create a new central topic of study in digital audio research. The new topic will assimilate the contributions of different disciplines on a common foundation. The key central concept that we lack is sound as a general-purpose information channel. We must investigate the structure of this information channel, which is driven by the cooperative development of auditory perception and physical sound production. Particular audible encodings, such as speech and music, illuminate sonic information by example, but they are no more sufficient for a characterization than typography is sufficient for characterization of visual information. To develop this new conceptual topic of sonic information structure, we need to integrate insights from a number of different disciplines that deal with sound. In particular, we need to coordinate central and foundational studies of the representational models of sound with specific applications that illuminate the good and bad qualities of these models. Each natural or artificial process that generates informative sound, and each perceptual mechanism that derives information from sound, will teach us something about the right structure to attribute to the sound itself. The new Sound topic will combine the work of computer

  17. Segmentation of heart sound recordings by a duration-dependent hidden Markov model

    International Nuclear Information System (INIS)

    Digital stethoscopes offer new opportunities for computerized analysis of heart sounds. Segmentation of heart sound recordings into periods related to the first and second heart sound (S1 and S2) is fundamental in the analysis process. However, segmentation of heart sounds recorded with handheld stethoscopes in clinical environments is often complicated by background noise. A duration-dependent hidden Markov model (DHMM) is proposed for robust segmentation of heart sounds. The DHMM identifies the most likely sequence of physiological heart sounds, based on duration of the events, the amplitude of the signal envelope and a predefined model structure. The DHMM model was developed and tested with heart sounds recorded bedside with a commercially available handheld stethoscope from a population of patients referred for coronary arterioangiography. The DHMM identified 890 S1 and S2 sounds out of 901 which corresponds to 98.8% (CI: 97.8–99.3%) sensitivity in 73 test patients and 13 misplaced sounds out of 903 identified sounds which corresponds to 98.6% (CI: 97.6–99.1%) positive predictivity. These results indicate that the DHMM is an appropriate model of the heart cycle and suitable for segmentation of clinically recorded heart sounds

  18. Modelling of meander migration in an incised channel

    Institute of Scientific and Technical Information of China (English)

    Jianchun HUANG; Blair P GREIMANN; Timothy J RANDLE

    2014-01-01

    An updated linear computer model for meandering rivers with incision has been developed. The model simulates the bed topography, flow field, and bank erosion rate in an incised meandering channel. In a scenario where the upstream sediment load decreases (e.g., after dam closure or soil conservation), alluvial river experiences cross section deepening and slope flattening. The channel migration rate might be affected in two ways:decreased channel slope and steeped bank height. The proposed numerical model combines the traditional one-dimensional (1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering. A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations. A linear meandering model was used to calculate the channel alignment and bank erosion/accretion, which in turn was used by the 1D sediment transport model. In the 1D sediment transport model, the channel bed elevation and gradations are represented in each channel cross section. In the meandering model, the bed elevation and gradations are stored in two dimensional (2D) cells to represent the channel and terrain properties (elevation and gradation). A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and terrain. The ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end.

  19. Selecting participants for listening tests of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Wickelmaier, Florian Maria; Choisel, Sylvain

    2005-01-01

    spatial hearing, and their verbal production abilities. The listeners displayed large individual differences in their performance. Forty subjects were selected based on the test results. The self-assessed listening habits and experience in the web-questionnaire could not predict the results of the......A selection procedure was devised in order to select listeners for experiments in which their main task will be to judge multichannel reproduced sound. Ninety-one participants filled in a web-based questionnaire. Seventy-eight of them took part in an assessment of their hearing thresholds, their...... selection procedure. Further, the hearing thresholds did not correlate with the spatial-hearing test. This leads to the conclusion that task-specific performance tests might be the preferable means of selecting a listening panel....

  20. THE MODEL FOR DIEGETIC ANALYSIS OF SOUNDS IN SCREEN MEDIA

    OpenAIRE

    Denikin Anton A.

    2013-01-01

    This article includes the analysis of the relationship between representational visual spaces and sounds in screen media. The methodology presented in this paper can be used for the accurate classification and differentiation for screen sounds, as well as for the general analysis of the specific sound of screen media. For this, the concept of «diegesis» is used. It allows us to analyze the spatial specificity of audiovisual images in cinematographic works and the spatial-functional interactiv...

  1. Coupled Modeling of Hydrodynamics and Sound in Coastal Ocean for Renewable Ocean Energy Development

    Energy Technology Data Exchange (ETDEWEB)

    Long, Wen; Jung, Ki Won; Yang, Zhaoqing; Copping, Andrea E.; Deng, Zhiqun

    2016-04-27

    An underwater sound model was developed to simulate sound propagation from marine and hydrokinetic energy (MHK) devices or offshore wind (OSW) energy platforms. Finite difference methods were developed to solve the 3D Helmholtz equation for sound propagation in the coastal environment. A 3D sparse matrix solver with complex coefficients was formed for solving the resulting acoustic pressure field. The Complex Shifted Laplacian Preconditioner (CSLP) method was applied to solve the matrix system iteratively with MPI parallelization using a high performance cluster. The sound model was then coupled with the Finite Volume Community Ocean Model (FVCOM) for simulating sound propagation generated by human activities, such as construction of OSW turbines or tidal stream turbine operations, in a range-dependent setting. As a proof of concept, initial validation of the solver is presented for two coastal wedge problems. This sound model can be useful for evaluating impacts on marine mammals due to deployment of MHK devices and OSW energy platforms.

  2. Central Puget Sound Ecopath/Ecosim model biological parameters - Developing food web models for ecosystem-based management applications in Puget Sound

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project is developing food web models for ecosystem-based management applications in Puget Sound. It is primarily being done by NMFS FTEs and contractors, in...

  3. Learning to Localize Sound with a Lizard Ear Model

    DEFF Research Database (Denmark)

    Shaikh, Danish; Hallam, John; Christensen-Dalsgaard, Jakob

    The peripheral auditory system of a lizard is strongly directional in the azimuth plane due to the acoustical coupling of the animal's two eardrums. This feature by itself is insufficient to accurately localize sound as the extracted directional information cannot be directly mapped to the sound ...

  4. Effects of sounding temperature assimilation on weather forecasting - Model dependence studies

    Science.gov (United States)

    Ghil, M.; Halem, M.; Atlas, R.

    1979-01-01

    In comparing various methods for the assimilation of remote sounding information into numerical weather prediction (NWP) models, the problem of model dependence for the different results obtained becomes important. The paper investigates two aspects of the model dependence question: (1) the effect of increasing horizontal resolution within a given model on the assimilation of sounding data, and (2) the effect of using two entirely different models with the same assimilation method and sounding data. Tentative conclusions reached are: first, that model improvement as exemplified by increased resolution, can act in the same direction as judicious 4-D assimilation of remote sounding information, to improve 2-3 day numerical weather forecasts. Second, that the time continuous 4-D methods developed at GLAS have similar beneficial effects when used in the assimilation of remote sounding information into NWP models with very different numerical and physical characteristics.

  5. Wireless multi-antenna channels modeling and simulation

    CERN Document Server

    Primak, Serguei

    2011-01-01

    This book offers a practical guide on how to use and apply channel models for system evaluation In this book, the authors focus on modeling and simulation of multiple antennas channels, including multiple input multiple output (MIMO) communication channels, and the impact of such models on channel estimation and system performance. Both narrowband and wideband models are addressed. Furthermore, the book covers topics related to modeling of MIMO channel, their numerical simulation, estimation and prediction, as well as applications to receive diversity, capacity and space-time c

  6. Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate Scale Water Quality Model

    Energy Technology Data Exchange (ETDEWEB)

    Khangaonkar, Tarang; Sackmann, Brandon S.; Long, Wen; Mohamedali, Teizeen; Roberts, Mindy

    2012-10-01

    The Salish Sea, including Puget Sound, is a large estuarine system bounded by over seven thousand miles of complex shorelines, consists of several subbasins and many large inlets with distinct properties of their own. Pacific Ocean water enters Puget Sound through the Strait of Juan de Fuca at depth over the Admiralty Inlet sill. Ocean water mixed with freshwater discharges from runoff, rivers, and wastewater outfalls exits Puget Sound through the brackish surface outflow layer. Nutrient pollution is considered one of the largest threats to Puget Sound. There is considerable interest in understanding the effect of nutrient loads on the water quality and ecological health of Puget Sound in particular and the Salish Sea as a whole. The Washington State Department of Ecology (Ecology) contracted with Pacific Northwest National Laboratory (PNNL) to develop a coupled hydrodynamic and water quality model. The water quality model simulates algae growth, dissolved oxygen, (DO) and nutrient dynamics in Puget Sound to inform potential Puget Sound-wide nutrient management strategies. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or control human impacts to DO levels in the sensitive areas. The project did not include any additional data collection but instead relied on currently available information. This report describes model development effort conducted during the period 2009 to 2012 under a U.S. Environmental Protection Agency (EPA) cooperative agreement with PNNL, Ecology, and the University of Washington awarded under the National Estuary Program

  7. Perturbations in dark energy models with evolving speed of sound

    CERN Document Server

    Ansari, Rizwan Ul Haq

    2011-01-01

    The behavior of perturbation in scalar field dark energy and its consequent effect on the cold dark matter (CDM) power spectrum is well understood to be governed by the equation of state (EOS) parameter and the effective speed of sound (ESS) of dark energy. In this paper, we investigate whether dark energy models whose ESS are epoch dependent leaves any distinct imprints on the large scale CDM power spectrum. In particular, we compare the cases where the ESS is decreasing with time with those where it increases. The CDM power spectrum is found to be generically suppressed in these cases as compared to the $\\Lambda$CDM model. The degree of suppression at different length scales can, in principle, reflect the evolving nature of the ESS of dark energy. However, we find that the effect on the CDM power spectrum in cases where the ESS of dark energy is evolving with constant EOS parameter is significantly smaller as compared to the situation where ESS is constant whereas EOS parameter is evolving. Further, it is a...

  8. Radiative characteristics for atmospheric models from lidar sounding and AERONET

    Science.gov (United States)

    Sapunov, Maxim; Kuznetsov, Anatoly; Efremenko, Dmitry; Bochalov, Valentin; Melnikova, Irina; Samulenkov, Dimity; Vasilyev, Alexander; Poberovsky, Anatoly; Frantsuzova, Inna

    2016-04-01

    Optical models of atmospheric aerosols above of St. Petersburg are constraint on the base of the results of lidar sounding. The lidar system of the Resource Center "Observatory of environmental safety" of the St. Petersburg University Research Park is situated the city center, Vasilievsky Island. The measurements of the vertical profile of velocity and wind direction in the center of St. Petersburg for 2014 -2015 are fulfilled in addition. Height of laser sounding of aerosols is up to 25 km and wind up to 12 km. Observations are accomplished in the daytime and at night and mapped to vertical profiles of temperature, humidity, wind speed and pressure obtained from radiosounding in Voeikovo (St. Petersburg suburb). Results of wind observations are compared with those of upper-air measurements of meteorological service in Voeikovo. The distance between the points of observation is 25 km. Statistics of wind directions at different heights are identified. The comparison is based on the assumption of homogeneity of the wind field on such a scale. In most cases, good agreement between the observed vertical profiles of wind, obtained by both methods is appeared. However, there were several cases, when the results differ sharply or at high altitudes, or, on the contrary, in the surface layer. The analysis of the impact of wind, temperature, and humidity profiles in the atmosphere on the properties and dynamics of solid impurities is implemented. Comparison with AOT results from AERONET observations in St. Petersburg suburb Peterhof is done. It is shown that diurnal and seasonal variations of optical and morphological parameters of atmospheric aerosols in the pollution cap over the city to a large extent determined by the variability of meteorological parameters. The results of the comparison are presented and possible explanation of the differences is proposed. Optical models of the atmosphere in day and night time in different seasons are constructed from lidar and AERONET

  9. Is the jet-drive flute model able to produce modulated sounds like Flautas de Chinos ?

    CERN Document Server

    Terrien, Soizic; De La Cuadra, Patricio; Fabre, Benoît

    2014-01-01

    Flautas de chinos - prehispanic chilean flutes played during ritual celebrations in central Chile - are known to produce very particular beating sounds, the so-called sonido rajado. Some previous works have focused on the spectral analysis of these sounds, and on the input impedance of the complex resonator. However, the beating sounds origin remains to be investigated. Throughout this paper, a comparison is provided between the characteristics of both the sound produced by flautas de chinos and a synthesis sound obtained through time-domain simulation of the jet-drive model for flute-like instruments. Jet-drive model appears to be able to produce quasiperiodic sounds similar to sonido rajado. Finally, the analysis of the system dynamics through numerical continuation methods allows to explore the production mechanism of these quasiperiodic regimes.

  10. Baroclinic Channel Model in Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    Kharatti Lal

    2016-02-01

    Full Text Available A complex flow structure is studied using a 2-dimentional baroclinic channel model Unsteady Navier - stokes equation coupled with equation of thermal energy ,salinity and the equation of state are implemented .System closure is achieved through a modified Prandtl, s mixing length formulation of turbulence dissipation The model is applied in a region where the fluid flow is effected by various forcing equation .In this case ,flow is estuarine region affected by diurnal tide and the fresh water inflow in to the estuary and a submerged structure is considered giving possible insight in to stress effects on submerged structure .the result show that in the time evolution of the vertical velocity along downstream edge changes sign from negative to positive .as the dike length increases the primary cell splits and flow becomes turbulent du e to the non-linear effect caused by the dike .these are found to agree favourably with result published in the open literature.

  11. Mathematical Modeling on Open Limestone Channel

    CERN Document Server

    Bandstra, Joel; Wu, Naiyi

    2014-01-01

    Acid mine drainage (AMD) is the outflow of acidic water from metal mines or coal mines. When exposed to air and water, metal sulfides from the deposits of the mines are oxidized and produce acid, metal ions and sulfate, which lower the pH value of the water. An open limestone channel (OLC) is a passive and low cost way to neutralize AMD. The dissolution of calcium into the water increases the pH value of the solution. A differential equation model is numerically solved to predict the variation of concentration of each species in the OLC solution. The diffusion of Calcium due to iron precipitates is modeled by a linear equation. The results give the variation of pH value and the concentration of Calcium.

  12. Modeling of channel erosion downstream spillway dams

    Directory of Open Access Journals (Sweden)

    M.A. Mikhalev

    2013-03-01

    Full Text Available The channel erosion downstream spillway dams in non-cohesive materials has been analyzed from the viewpoint of methods of similarity and dimension theory. The obtained criterion equation connects the maximum depth of the local erosion with its determining parameters: length of concrete lining of bed in the down water of the spillway dam; Froude number at the contracted cross section; Archimedes and Reynolds criterions; submergence factor of hydraulic jump. The problem may be formulated as follows: the geometric size of the structure, kinematics and dynamics of the flows in the model are similar to that in the prototype. Conditions under which the characteristic depth of the local erosion in the model would be recomputed into the prototype, like any geometric size, are being discussed.

  13. A reciprocating twin-channel model for ABC transporters.

    Science.gov (United States)

    Jones, Peter M; George, Anthony M

    2014-08-01

    ABC transporters comprise a large, diverse, and ubiquitous superfamily of membrane active transporters. Their core architecture is a dimer of dimers, comprising two transmembrane (TM) domains that bind substrate, and two ATP-binding cassettes, which use the cell's energy currency to couple substrate translocation to ATP hydrolysis. Despite the availability of over a dozen resolved structures and a wealth of biochemical and biophysical data, this field is bedeviled by controversy and long-standing mechanistic questions remain unresolved. The prevailing paradigm for the ABC transport mechanism is the Switch Model, in which the ATP-binding cassettes dimerize upon binding two ATP molecules, and thence dissociate upon sequential ATP hydrolysis. This cycle of nucleotide-binding domain (NBD) dimerization and dissociation is coupled to a switch between inward- or outward facing conformations of a single TM channel; this alternating access enables substrate binding on one face of the membrane and its release at the other. Notwithstanding widespread acceptance of the Switch Model, there is substantial evidence that the NBDs do not separate very much, if at all, and thus physical separation of the ATP cassettes observed in crystallographic structures may be an artefact. An alternative Constant Contact Model has been proposed, in which ATP hydrolysis occurs alternately at the two ATP-binding sites, with one of the sites remaining closed and containing occluded nucleotide at all times. In this model, the cassettes remain in contact and the active sites swing open in an alternately seesawing motion. Whilst the concept of NBD association/dissociation in the Switch Model is naturally compatible with a single alternating-access channel, the asymmetric functioning proposed by the Constant Contact model suggests an alternating or reciprocating function in the TMDs. Here, a new model for the function of ABC transporters is proposed in which the sequence of ATP binding, hydrolysis, and

  14. EXTRACTION OF SPATIAL PARAMETERS FROM CLASSIFIED LIDAR DATA AND AERIAL PHOTOGRAPH FOR SOUND MODELING

    Directory of Open Access Journals (Sweden)

    S. Biswas

    2012-07-01

    Full Text Available Prediction of outdoor sound levels in 3D space is important for noise management, soundscaping etc. Sound levels at outdoor can be predicted using sound propagation models which need terrain parameters. The existing practices of incorporating terrain parameters into models are often limited due to inadequate data or inability to determine accurate sound transmission paths through a terrain. This leads to poor accuracy in modelling. LIDAR data and Aerial Photograph (or Satellite Images provide opportunity to incorporate high resolution data into sound models. To realize this, identification of building and other objects and their use for extraction of terrain parameters are fundamental. However, development of a suitable technique, to incorporate terrain parameters from classified LIDAR data and Aerial Photograph, for sound modelling is a challenge. Determination of terrain parameters along various transmission paths of sound from sound source to a receiver becomes very complex in an urban environment due to the presence of varied and complex urban features. This paper presents a technique to identify the principal paths through which sound transmits from source to receiver. Further, the identified principal paths are incorporated inside the sound model for sound prediction. Techniques based on plane cutting and line tracing are developed for determining principal paths and terrain parameters, which use various information, e.g., building corner and edges, triangulated ground, tree points and locations of source and receiver. The techniques developed are validated through a field experiment. Finally efficacy of the proposed technique is demonstrated by developing a noise map for a test site.

  15. A Survey of Fading Models for Mobile Radio Channel Characterization

    Directory of Open Access Journals (Sweden)

    L. D. Arya

    2010-02-01

    Full Text Available Future 3G and 4G mobile communication systems will be required to support wide range of data rates and quality of service matrix. For the efficient design of data link and transport protocols system designer needs knowledge of the statistical properties of physicallayer. Studies have shown that without proper characterization of the channel, blind application of existing protocols and transmission policy may results in disastrous performance unless proper measures are not being taken. Channel characterization also helps in llocation of resources, selection of transmission policy andprotocols. A feasible measure is to have an accurate and thoroughly reproducible optimum channel model which can mimic the mobile radio channel in diversities of fading error environments. Objective of channel model is to supply proper outputs for designing of upper layer protocol in such a fashion as if it were running on the actualphysical layer. The model should fit very well to the measured data and should easily handle analytically. Various approaches for characterization of fading mobile channels have appeared in iterature over last five decades. This article surveys the fading channel models for proper characterization of the radio channel andprovides approaches to classify the existing channel models. The paper also presents the contribution made by these channel models with their assumptions, suitability, applications, shortcomingsand further improvement issues. In present environment Markov Models are best suited for characterization of the fading radio channel. Inthese models radio channel is presented in terms of fading states and modeled as stochastic process. A proper constructed channel model may be valuable means to enhance the reliability and capacity of future mobile radio channel.

  16. Modeling of channel patterns in short tidal basins

    NARCIS (Netherlands)

    Marciano, R.; Wang, Z.B.; Hibma, A.; De Vriend, H.J.; Defina, A.

    2005-01-01

    We model branching channel patterns in short tidal basins with two methods. A theoretical stability analysis leads to a relationship between the number of channels and physical parameters of the tidal system. The analysis reveals that width and spacing of the channels should decrease as the slope of

  17. Sound Field Modeling in Architectural Acoustics using a Diffusion Equation Based Model

    OpenAIRE

    Fortin, Nicolas; Picaut, Judicaël; Billon, Alexis; Valeau, Vincent; SAKOUT, Anas

    2009-01-01

    In this paper, an implementation of a model for room-acoustic predictions in COMSOL Multiphysics is presented. The model (called diffusion model) is based on the solving of diffusion equations instead of classical wave equations and allows simulating the sound propagation in complex geometries at high frequency. Instead of using COMSOL Multiplysics to solve directly the problem, a specific tool has been developed. It is composed of a user-friendly interface (I-Simpa) which manipulates all the...

  18. Sound Field Modeling in Architectural Acoustics using a Diffusion Equation Based Model

    OpenAIRE

    Fortin, Nicolas; Picaut, Judicaël; Billon, Alexis; Valeau, Vincent; SAKOUT, Anas

    2009-01-01

    In this paper, an implementation of a model for room-acoustic predictions in COMSOL Multiphysics is presented. The model (called diffusion model) is based on the solving of diffusion equations instead of classical wave equations and allows simulating the sound propagation in complex geometries at high frequency. Instead of using COMSOL Multiplysics to solve directly the problem, a specific tool has been developed. It is composed of a user-friendly interface (I-Simpa) which manipulates a...

  19. Some improvements to the model of discrete sound field nearby multi-propeller aircraft

    Institute of Scientific and Technical Information of China (English)

    王同庆; 李晓东; 周盛

    1995-01-01

    Improvements to the mathematical-physical model of discrete sound field of multi-propeller aircraft have been made by using aeroacoustic analogy method, which considers the effects of fuselage boundary as well as the interference process of the multiple propeller sound field. The calculated results illustrate the effects of fuselage on the propeller sound field, the ’beating noise’ phenomenon and the principle of noise control of synchrophaser system. The model for boundaries with arbitrary shapes can also be used to calculate the effects of rigid boundaries in other harmonic sound fields. Results for sound scattering of a rigid sphere in a planar harmonic wave calculated by using this model are satisfactorily coincident with those by the analytical method.

  20. Channel Modelling for Multiprobe Over-the-Air MIMO Testing

    Directory of Open Access Journals (Sweden)

    Pekka Kyösti

    2012-01-01

    a fading emulator, an anechoic chamber, and multiple probes. Creation of a propagation environment inside an anechoic chamber requires unconventional radio channel modelling, namely, a specific mapping of the original models onto the probe antennas. We introduce two novel methods to generate fading emulator channel coefficients; the prefaded signals synthesis and the plane wave synthesis. To verify both methods we present a set of simulation results. We also show that the geometric description is a prerequisite for the original channel model.

  1. A model for the distribution channels planning process

    NARCIS (Netherlands)

    Neves, M.F.; Zuurbier, P.; Campomar, M.C.

    2001-01-01

    Research of existing literature reveals some models (sequence of steps) for companies that want to plan distribution channels. None of these models uses strong contributions from transaction cost economics, bringing a possibility to elaborate on a "distribution channels planning model", with these c

  2. [Model of the selective calcium channel of characean algae].

    Science.gov (United States)

    Lunevskiĭ, V Z; Zherelova, O M; Aleksandrov, A A; Vinokurov, M G; Berestovskiĭ, G N

    1980-01-01

    The present work was intended to further investigate the selective filter of calcium channel on both a cell membrane and reconstructed channels. For the studies on cell membranes, an inhibitor of chloride channels was chosen (ethacrynic acid) to pass currents only through the calcium channels. On both the cells and reconstructed channels, permeability of ions of different crystal radii and valencies was investigated. The obtained results suggest that the channel represents a wide water pore with a diameter larger than 8 A into which ions go together with the nearest water shell. The values of the maximal currents are given by electrostatic interaction of the ions with the anion center of the channel. A phenomenological two-barrier model of the channel is given which describes the movement of all the ions studied. PMID:6251921

  3. Dividing Streamline Formation Channel Confluences by Physical Modeling

    Directory of Open Access Journals (Sweden)

    Minarni Nur Trilita

    2010-02-01

    Full Text Available Confluence channels are often found in open channel network system and is the most important element. The incoming flow from the branch channel to the main cause various forms and cause vortex flow. Phenomenon can cause erosion of the side wall of the channel, the bed channel scour and sedimentation in the downstream confluence channel. To control these problems needed research into the current width of the branch channel. The incoming flow from the branch channel to the main channel flow bounded by a line distributors (dividing streamline. In this paper, the wide dividing streamline observed in the laboratory using a physical model of two open channels, a square that formed an angle of 30º. Observations were made with a variety of flow coming from each channel. The results obtained in the laboratory observation that the width of dividing streamline flow is influenced by the discharge ratio between the channel branch with the main channel. While the results of a comparison with previous studies showing that the observation in the laboratory is smaller than the results of previous research.

  4. Multi-scale modeling of Puget Sound using an unstructured-grid coastal ocean model: from tide flats to estuaries and coastal waters

    International Nuclear Information System (INIS)

    Water circulation in Puget Sound, a large complex estuary system in the Pacific Northwest coastal ocean of the United States, is governed by multiple spatially and temporally varying forcings from tides, atmosphere (wind, heating/cooling, precipitation/evaporation, pressure), and river inflows. In addition, the hydrodynamic response is affected strongly by geomorphic features, such as fjord-like bathymetry and complex shoreline features, resulting in many distinguishing characteristics in its main and sub-basins. To better understand the details of circulation features in Puget Sound and to assist with proposed nearshore restoration actions for improving water quality and the ecological health of Puget Sound, a high-resolution (around 50 m in estuaries and tide flats) hydrodynamic model for the entire Puget Sound was needed. Here, a threedimensional circulation model of Puget Sound using an unstructured-grid finite volume coastal ocean model is presented. The model was constructed with sufficient resolution in the nearshore region to address the complex coastline, multi-tidal channels, and tide flats. Model open boundaries were extended to the entrance of the Strait of Juan de Fuca and the northern end of the Strait of Georgia to account for the influences of ocean water intrusion from the Strait of Juan de Fuca and the Fraser River plume from the Strait of Georgia, respectively. Comparisons of model results, observed data, and associated error statistics for tidal elevation, velocity, temperature, and salinity indicate that the model is capable of simulating the general circulation patterns on the scale of a large estuarine system as well as detailed hydrodynamics in the nearshore tide flats. Tidal characteristics, temperature/salinity stratification, mean circulation, and river plumes in estuaries with tide flats are discussed.

  5. Degraded neural and behavioral processing of speech sounds in a rat model of Rett syndrome.

    Science.gov (United States)

    Engineer, Crystal T; Rahebi, Kimiya C; Borland, Michael S; Buell, Elizabeth P; Centanni, Tracy M; Fink, Melyssa K; Im, Kwok W; Wilson, Linda G; Kilgard, Michael P

    2015-11-01

    Individuals with Rett syndrome have greatly impaired speech and language abilities. Auditory brainstem responses to sounds are normal, but cortical responses are highly abnormal. In this study, we used the novel rat Mecp2 knockout model of Rett syndrome to document the neural and behavioral processing of speech sounds. We hypothesized that both speech discrimination ability and the neural response to speech sounds would be impaired in Mecp2 rats. We expected that extensive speech training would improve speech discrimination ability and the cortical response to speech sounds. Our results reveal that speech responses across all four auditory cortex fields of Mecp2 rats were hyperexcitable, responded slower, and were less able to follow rapidly presented sounds. While Mecp2 rats could accurately perform consonant and vowel discrimination tasks in quiet, they were significantly impaired at speech sound discrimination in background noise. Extensive speech training improved discrimination ability. Training shifted cortical responses in both Mecp2 and control rats to favor the onset of speech sounds. While training increased the response to low frequency sounds in control rats, the opposite occurred in Mecp2 rats. Although neural coding and plasticity are abnormal in the rat model of Rett syndrome, extensive therapy appears to be effective. These findings may help to explain some aspects of communication deficits in Rett syndrome and suggest that extensive rehabilitation therapy might prove beneficial.

  6. 短波信道探测中多普勒频移的计算%Calculation of Doppler shift in HF channel sounding

    Institute of Scientific and Technical Information of China (English)

    刘月亮; 蒋宇中; 张四起

    2012-01-01

    For the purpose of exact measurement of Doppler shift, based on the pulse compression technique, this paper di the theoretical deduction of the calculation of Doppler shift, in which the signal modulated by Zadoff-Chu sequence was used a the sounding signal and a simplified Watterson model was used as the HF channel. It obtained a calculation formula of Dopple shift, carried out the simulation, of the calculation result of the formula for the case of two paths. The simulation results shoi that the calculation result of the formula is right when the Doppler difference of the two paths is less than ± 0. 3 Hz. On the ba sis of this,made the simulation of Doppler shift* s effect on the pulse compression of Zadoff-Chu sequence. The results shoi that the effect of the Doppler shift which is less than 10 Hz is negligible, which affirms that Zadoff-Chu sequence is an appro priate sequence for HF channel sounding.%为准确获取短波信道探测信号的多普勒频移,把被Zadoff-Chu序列调制的信号作为探测信号,以简化的Watterson模型作为短波信道,采用脉冲压缩技术,对多普勒频移的计算进行了理论推导,得出了一种多普勒频移的计算公式,对两条路径时公式的计算结果进行了仿真.结果表明,在两条路径的多普勒频移相差小于±0.3 Hz时,计算结果较为准确.在此基础上,仿真分析了多普勒频移对Zadoff-Chu序列的脉冲压缩的影响.分析表明,小于10 Hz的多普勒频移对Zadoff-Chu序列的脉冲压缩的影响可以忽略不计,将该序列应用在短波信道探测中比较合适.

  7. Dynamical Properties of Potassium Ion Channels with a Hierarchical Model

    Institute of Scientific and Technical Information of China (English)

    ZHAN Yong; AN Hai-Long; YU Hui; ZHANG Su-Hua; HAN Ying-Rong

    2006-01-01

    @@ It is well known that potassium ion channels have higher permeability than K ions, and the permeable rate of a single K ion channel is about 108 ions per second. We develop a hierarchical model of potassium ion channel permeation involving ab initio quantum calculations and Brownian dynamics simulations, which can consistently explain a range of channel dynamics. The results show that the average velocity of K ions, the mean permeable time of K ions and the permeable rate of single channel are about 0.92nm/ns, 4.35ns and 2.30×108 ions/s,respectively.

  8. A computer simulation model for room sound field considering diffuse reflection

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A multiple random ray-tracing model was developed for predicting the distribution of sound pressure levels in an enclosed space of any shape. This model considered two diffuse factors of a room-diffuse reflection due to room surfaces and scattering due to objects. The surface diffusion was treated by two different methods on the basis of probability analysis, and the scattering was simulated by a multiple random ray-tracing process. Thus the sound pressure level distribution in a diffuse sound filed can be calculate more precisely.

  9. Food web model output - Trophic impacts of bald eagles in the Puget Sound food web

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project is developing models to examine the ecological roles of bald eagles in the Puget Sound region. It is primarily being done by NMFS FTEs, in...

  10. Bioenergetics model output - Trophic impacts of bald eagles in the Puget Sound food web

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project is developing models to examine the ecological roles of bald eagles in the Puget Sound region. It is primarily being done by NMFS FTEs, in...

  11. Modeling the morphogenesis of brine channels in sea ice

    CERN Document Server

    Kutschan, B; gemming, S

    2009-01-01

    Brine channels are formed in sea ice under certain constraints and represent a habitat of different microorganisms. The complex system depends on a number of various quantities as salinity, density, pH-value or temperature. Each quantity governs the process of brine channel formation. There exists a strong link between bulk salinity and the presence of brine drainage channels in growing ice with respect to both the horizontal and vertical planes. We develop a suitable phenomenological model for the formation of brine channels both referring to the Ginzburg-Landau-theory of phase transitions as well as to the chemical basis of morphogenesis according to Turing. It is possible to conclude from the critical wavenumber on the size of the structure and the critical parameters. The theoretically deduced transition rates have the same magnitude as the experimental values. The model creates channels of similar size as observed experimentally. An extension of the model towards channels with different sizes is possible...

  12. A 0-Memory Model for Single Ion Channel

    Institute of Scientific and Technical Information of China (English)

    Zhou Wenqing; Fan Jiqian; Guan Yongyuan

    1998-01-01

    This paper discusses a 0-memory model for a single ion channel. The renewal rates of the open-class and the close-class are proposed to deseribe kinetic properties of a single ion channel. Further more, a procedure to estimate the parameters in the model is suggested and illustrated with examples in pharmacology.

  13. Development of a Hydrodynamic Model of Puget Sound and Northwest Straits

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang P.

    2007-12-10

    The hydrodynamic model used in this study is the Finite Volume Coastal Ocean Model (FVCOM) developed by the University of Massachusetts at Dartmouth. The unstructured grid and finite volume framework, as well as the capability of wetting/drying simulation and baroclinic simulation, makes FVCOM a good fit to the modeling needs for nearshore restoration in Puget Sound. The model domain covers the entire Puget Sound, Strait of Juan de Fuca, San Juan Passages, and Georgia Strait at the United States-Canada Border. The model is driven by tide, freshwater discharge, and surface wind. Preliminary model validation was conducted for tides at various locations in the straits and Puget Sound using National Oceanic and Atmospheric Administration (NOAA) tide data. The hydrodynamic model was successfully linked to the NOAA oil spill model General NOAA Operational Modeling Environment model (GNOME) to predict particle trajectories at various locations in Puget Sound. Model results demonstrated that the Puget Sound GNOME model is a useful tool to obtain first-hand information for emergency response such as oil spill and fish migration pathways.

  14. 77 FR 23119 - Annual Marine Events in the Eighth Coast Guard District, Smoking the Sound; Biloxi Ship Channel...

    Science.gov (United States)

    2012-04-18

    ... SECURITY Coast Guard 33 CFR Part 100 Annual Marine Events in the Eighth Coast Guard District, Smoking the... regulation. SUMMARY: The Coast Guard will enforce Special Local Regulations for the Smoking the Sound boat..., and persons on navigable waters during the Smoking the Sound boat races. During the enforcement...

  15. Extraction of auditory features and elicitation of attributes for the assessment of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Choisel, Sylvain; Wickelmaier, Florian Maria

    2005-01-01

    The identification of relevant auditory attributes is pivotal in sound quality evaluation. Two fundamentally different psychometric methods were employed to uncover perceptually relevant auditory features of multichannel reproduced sound. In the first method, called Repertory Grid Technique (RGT)...... sufficient consistency, a lattice representation-as frequently used in Formal Concept Analysis (FCA)-can be derived to depict the structure of auditory features...

  16. Transport properties in network models with perfectly conducting channels

    International Nuclear Information System (INIS)

    We study the transport properties of disordered electron systems that contain perfectly conducting channels. Two quantum network models that belong to different universality classes, unitary and symplectic, are simulated numerically. The perfectly conducting channel in the unitary class can be realized in zigzag graphene nano-ribbons and that in the symplectic class is known to appear in metallic carbon nanotubes. The existence of a perfectly conducting channel leads to novel conductance distribution functions and a shortening of the conductance decay length.

  17. Transport properties in network models with perfectly conducting channels

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, K; Hirose, K; Ohtsuki, T [Department of Physics, Sophia University, 102-8554 Tokyo (Japan); Obuse, H [Department of Physics, Kyoto University, 606-8501 Kyoto (Japan); Slevin, K [Department of Physics, Osaka University, 560-0043 Osaka (Japan)], E-mail: k-koji@sophia.ac.jp

    2009-02-01

    We study the transport properties of disordered electron systems that contain perfectly conducting channels. Two quantum network models that belong to different universality classes, unitary and symplectic, are simulated numerically. The perfectly conducting channel in the unitary class can be realized in zigzag graphene nano-ribbons and that in the symplectic class is known to appear in metallic carbon nanotubes. The existence of a perfectly conducting channel leads to novel conductance distribution functions and a shortening of the conductance decay length.

  18. Transport properties in network models with perfectly conducting channels

    OpenAIRE

    Kobayashi, Koji; Hirose, Kosuke; Obuse, Hideaki; Ohtsuki, Tomi; Slevin, Keith

    2008-01-01

    We study the transport properties of disordered electron systems that contain perfectly conducting channels. Two quantum network models that belong to different universality classes, unitary and symplectic, are simulated numerically. The perfectly conducting channel in the unitary class can be realized in zigzag graphene nano-ribbons and that in the symplectic class is known to appear in metallic carbon nanotubes. The existence of a perfectly conducting channel leads to novel conductance dist...

  19. Modeling two-phase flow in PEM fuel cell channels

    Science.gov (United States)

    Wang, Yun; Basu, Suman; Wang, Chao-Yang

    2008-05-01

    This paper is concerned with the simultaneous flow of liquid water and gaseous reactants in mini-channels of a proton exchange membrane (PEM) fuel cell. Envisaging the mini-channels as structured and ordered porous media, we develop a continuum model of two-phase channel flow based on two-phase Darcy's law and the M2 formalism, which allow estimate of the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction. Analytical solutions of liquid water saturation and species concentrations along the channel are derived to explore the dependences of these physical variables vital to cell performance on operating parameters such as flow stoichiometric ratio and relative humility. The two-phase channel model is further implemented for three-dimensional numerical simulations of two-phase, multi-component transport in a single fuel-cell channel. Three issues critical to optimizing channel design and mitigating channel flooding in PEM fuel cells are fully discussed: liquid water buildup towards the fuel cell outlet, saturation spike in the vicinity of flow cross-sectional heterogeneity, and two-phase pressure drop. Both the two-phase model and analytical solutions presented in this paper may be applicable to more general two-phase flow phenomena through mini- and micro-channels.

  20. Modeling two-phase flow in PEM fuel cell channels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Basu, Suman; Wang, Chao-Yang [Electrochemical Engine Center (ECEC), and Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2008-05-01

    This paper is concerned with the simultaneous flow of liquid water and gaseous reactants in mini-channels of a proton exchange membrane (PEM) fuel cell. Envisaging the mini-channels as structured and ordered porous media, we develop a continuum model of two-phase channel flow based on two-phase Darcy's law and the M{sup 2} formalism, which allow estimate of the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction. Analytical solutions of liquid water saturation and species concentrations along the channel are derived to explore the dependences of these physical variables vital to cell performance on operating parameters such as flow stoichiometric ratio and relative humility. The two-phase channel model is further implemented for three-dimensional numerical simulations of two-phase, multi-component transport in a single fuel-cell channel. Three issues critical to optimizing channel design and mitigating channel flooding in PEM fuel cells are fully discussed: liquid water buildup towards the fuel cell outlet, saturation spike in the vicinity of flow cross-sectional heterogeneity, and two-phase pressure drop. Both the two-phase model and analytical solutions presented in this paper may be applicable to more general two-phase flow phenomena through mini- and micro-channels. (author)

  1. Sound synchronization of bubble trains in a viscous fluid: experiment and modeling.

    Science.gov (United States)

    Pereira, Felipe Augusto Cardoso; Baptista, Murilo da Silva; Sartorelli, José Carlos

    2014-10-01

    We investigate the dynamics of formation of air bubbles expelled from a nozzle immersed in a viscous fluid under the influence of sound waves. We have obtained bifurcation diagrams by measuring the time between successive bubbles, having the air flow (Q) as a parameter control for many values of the sound wave amplitude (A), the height (H) of the solution above the top of the nozzle, and three values of the sound frequency (fs). Our parameter spaces (Q,A) revealed a scenario for the onset of synchronization dominated by Arnold tongues (frequency locking) which gives place to chaotic phase synchronization for sufficiently large A. The experimental results were accurately reproduced by numerical simulations of a model combining a simple bubble growth model for the bubble train and a coupling term with the sound wave added to the equilibrium pressure.

  2. A new simple model for composite fading channels: Second order statistics and channel capacity

    KAUST Repository

    Yilmaz, Ferkan

    2010-09-01

    In this paper, we introduce the most general composite fading distribution to model the envelope and the power of the received signal in such fading channels as millimeter wave (60 GHz or above) fading channels and free-space optical channels, which we term extended generalized-K (EGK) composite fading distribution. We obtain the second-order statistics of the received signal envelope characterized by the EGK composite fading distribution. Expressions for probability density function, cumulative distribution function, level crossing rate and average fade duration, moments, amount of fading and average capacity are derived. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis. © 2010 IEEE.

  3. A channel-based coordination model for component composition

    NARCIS (Netherlands)

    Arbab, F.

    2002-01-01

    In this paper, we present $P epsilon omega$, a paradigm for composition of software components based on the notion of mobile channels. $P repsilon omega$ is a channel-based exogenous coordination model wherein complex coordinators, called {em connectors are compositionally built out of simpler ones.

  4. Reo: A Channel-based Coordination Model for Component Composition

    NARCIS (Netherlands)

    Arbab, F.

    2004-01-01

    In this paper, we present Reo, which forms a paradigm for composition of software components based on the notion of mobile channels. Reo is a channel-based exogenous coordination model in which complex coordinators, called connectors, are compositionally built out of simpler ones. The simplest conne

  5. Molecular modeling of mechanosensory ion channel structural and functional features.

    Science.gov (United States)

    Gessmann, Renate; Kourtis, Nikos; Petratos, Kyriacos; Tavernarakis, Nektarios

    2010-09-16

    The DEG/ENaC (Degenerin/Epithelial Sodium Channel) protein family comprises related ion channel subunits from all metazoans, including humans. Members of this protein family play roles in several important biological processes such as transduction of mechanical stimuli, sodium re-absorption and blood pressure regulation. Several blocks of amino acid sequence are conserved in DEG/ENaC proteins, but structure/function relations in this channel class are poorly understood. Given the considerable experimental limitations associated with the crystallization of integral membrane proteins, knowledge-based modeling is often the only route towards obtaining reliable structural information. To gain insight into the structural characteristics of DEG/ENaC ion channels, we derived three-dimensional models of MEC-4 and UNC-8, based on the available crystal structures of ASIC1 (Acid Sensing Ion Channel 1). MEC-4 and UNC-8 are two DEG/ENaC family members involved in mechanosensation and proprioception respectively, in the nematode Caenorhabditis elegans. We used these models to examine the structural effects of specific mutations that alter channel function in vivo. The trimeric MEC-4 model provides insight into the mechanism by which gain-of-function mutations cause structural alterations that result in increased channel permeability, which trigger cell degeneration. Our analysis provides an introductory framework to further investigate the multimeric organization of the DEG/ENaC ion channel complex.

  6. Molecular modeling of mechanosensory ion channel structural and functional features.

    Directory of Open Access Journals (Sweden)

    Renate Gessmann

    Full Text Available The DEG/ENaC (Degenerin/Epithelial Sodium Channel protein family comprises related ion channel subunits from all metazoans, including humans. Members of this protein family play roles in several important biological processes such as transduction of mechanical stimuli, sodium re-absorption and blood pressure regulation. Several blocks of amino acid sequence are conserved in DEG/ENaC proteins, but structure/function relations in this channel class are poorly understood. Given the considerable experimental limitations associated with the crystallization of integral membrane proteins, knowledge-based modeling is often the only route towards obtaining reliable structural information. To gain insight into the structural characteristics of DEG/ENaC ion channels, we derived three-dimensional models of MEC-4 and UNC-8, based on the available crystal structures of ASIC1 (Acid Sensing Ion Channel 1. MEC-4 and UNC-8 are two DEG/ENaC family members involved in mechanosensation and proprioception respectively, in the nematode Caenorhabditis elegans. We used these models to examine the structural effects of specific mutations that alter channel function in vivo. The trimeric MEC-4 model provides insight into the mechanism by which gain-of-function mutations cause structural alterations that result in increased channel permeability, which trigger cell degeneration. Our analysis provides an introductory framework to further investigate the multimeric organization of the DEG/ENaC ion channel complex.

  7. Model validation of channel zapping quality

    NARCIS (Netherlands)

    Kooij, R.E.; Nicolai, F.; Ahmed, O.K.; Brunnström, K.

    2009-01-01

    In an earlier paper we showed, that perceived quality of channel zapping is related to the perceived quality of download time of web browsing, as suggested by ITU-T Rec.G.1030. We showed this by performing subjective tests resulting in an excellent fit with a 0.99 correlation. This was what we call

  8. A numerical model for meltwater channel evolution in glaciers

    Directory of Open Access Journals (Sweden)

    A. H. Jarosch

    2011-10-01

    Full Text Available Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are the channel slope and the meltwater temperature loss to the ice. Meltwater flux controls channel width and to a lesser degree incision behaviour. Calculated Nusselt numbers suggest that turbulent forced convection is the main heat transfer mechanism in the studied meltwater channels.

  9. Sensitivity to plant modelling uncertainties in optimal feedback control of sound radiation from a panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1997-01-01

    of a rectangular baffled panel radiating into free field has been constructed. Secondary actuators have been modelled as vibrational inputs acting directly on the panel. A cost function proportional to the averaged radiated sound power and based on knowledge of the modal amplitudes of the panel has been derived...... in terms of a set of radiation filters modelling the radiation dynamics.Linear quadratic feedback control applied to the panel in order to minimise the radiated sound power has then been simulated. The sensitivity of the model based controller to modelling uncertainties when using feedback from actual...

  10. A study on the sound quality evaluation model of mechanical air-cleaners

    DEFF Research Database (Denmark)

    Ih, Jeong-Guon; Jang, Su-Won; Jeong, Cheol-Ho;

    2009-01-01

    of an immediate cleaning of pollutants. In this context, it is important to evaluate and design the air-cleaner noise to satisfy such contradictory expectations from the customers. In this study, a model for evaluating the sound quality of air-cleaners of mechanical type was developed based on objective......In operating the air-cleaner for a long time, people in a quiet enclosed space expect low sound at low operational levels for a routine cleaning of air. However, in the condition of high operational levels of the cleaner, a powerful yet nonannoying sound is desired, which is connected to a feeling...... sounds were conducted by the semantic differential method (SDM) and the method of successive intervals (MSI). SDM tests for seven adjective pairs were conducted to find the relation between subjective feeling and frequency bands. Two major feelings, performance and annoyance, were factored out from...

  11. Environmental Sound Perception: Metadescription and Modeling Based on Independent Primary Studies

    Directory of Open Access Journals (Sweden)

    Stephen McAdams

    2010-01-01

    Full Text Available The aim of the study is to transpose and extend to a set of environmental sounds the notion of sound descriptors usually used for musical sounds. Four separate primary studies dealing with interior car sounds, air-conditioning units, car horns, and closing car doors are considered collectively. The corpus formed by these initial stimuli is submitted to new experimental studies and analyses, both for revealing metacategories and for defining more precisely the limits of each of the resulting categories. In a second step, the new structure is modeled: common and specific dimensions within each category are derived from the initial results and new investigations of audio features are performed. Furthermore, an automatic classifier based on two audio descriptors and a multinomial logistic regression procedure is implemented and validated with the corpus.

  12. NUMERICAL MODELING OF SUSPENDED SEDIMENT TRANSPORT IN CHANNEL BENDS

    Institute of Scientific and Technical Information of China (English)

    HUANG Sui-liang; JIA Y. F.; WANG Sam S. Y.

    2006-01-01

    An algorithm to compute three-dimensional sediment transport effect was proposed in this paper to enhance the capability of depth-averaged numerical models. This algorithm took into account of non-uniform distributions of flow velocities and suspended sediment concentrations along water depth, it significantly enhanced the applicability of 2D models in simulating open channel flows, especially in channel bends. Preliminary numerical experiments in a U-shaped and a sine-generated experimental channel indicate that the proposed method performs quite well in predicting the change of bed-deformation in channel bends due to suspended sediment transport. This method provides an effective alternative for the simulations of channel morphodynamic changes.

  13. Curing the acausal behavior of the sound velocity in an excluded volume hadron resonance gas model

    CERN Document Server

    Kadam, Guru Prakash

    2015-01-01

    We improve the excluded volume hadron resonances gas model (EHRG) to cure the acausal behavior of the sound velocity which is typical of excluded volume models. We achieve this by including temperature (T) and density ({\\mu}) dependent hadron masses in the partition function of EHRG. The temperature and density dependent masses of the constituent quarks (u,d,s) and the light mesons are obtained within Nambu-Jona-Lasinio model while for the heavy hadrons we use linear scaling rule in terms of constituent quarks. With this improvement, we observe that the velocity of sound flattens at high temperature unlike old EHRG models where the sound velocity rises very rapidly at high temperatures which is the indication of its super-luminal behavior.

  14. ENHANCING HYDROLOGICAL SIMULATION PROGRAM - FORTRAN MODEL CHANNEL HYDRAULIC REPRESENTATION

    Science.gov (United States)

    The Hydrological Simulation Program– FORTRAN (HSPF) is a comprehensive watershed model that employs depth-area - volume - flow relationships known as the hydraulic function table (FTABLE) to represent the hydraulic characteristics of stream channel cross-sections and reservoirs. ...

  15. S-Channel Dark Matter Simplified Models and Unitarity

    OpenAIRE

    Englert, Christoph; McCullough, Matthew; Spannowsky, Michael

    2016-01-01

    The ultraviolet structure of $s$-channel mediator dark matter simplified models at hadron colliders is considered. In terms of commonly studied $s$-channel mediator simplified models it is argued that at arbitrarily high energies the perturbative description of dark matter production in high energy scattering at hadron colliders will break down in a number of cases. This is analogous to the well documented breakdown of an EFT description of dark matter collider production. With this in mind, ...

  16. A NEW PUNCHTHROUGH MODEL FOR SHORT CHANNEL MOSFET

    OpenAIRE

    Chen, D.; Li, Zhenyu

    1988-01-01

    After the source-drain punchthrough was considered detailly, a new set of analytical models for punchthrough voltage VP were suggested, which are suitable to NMOSFET with uniformly doped substrate or channel ion-implanted substrate and PMOSFET with buried channel, as well as a high speed numerical simulation method was developed for autosearching of VP. Excellent agreements were shown between the results of numerical simulation and analytical models.

  17. Evaluating a linearized Euler equations model for strong turbulence effects on sound propagation.

    Science.gov (United States)

    Ehrhardt, Loïc; Cheinet, Sylvain; Juvé, Daniel; Blanc-Benon, Philippe

    2013-04-01

    Sound propagation outdoors is strongly affected by atmospheric turbulence. Under strongly perturbed conditions or long propagation paths, the sound fluctuations reach their asymptotic behavior, e.g., the intensity variance progressively saturates. The present study evaluates the ability of a numerical propagation model based on the finite-difference time-domain solving of the linearized Euler equations in quantitatively reproducing the wave statistics under strong and saturated intensity fluctuations. It is the continuation of a previous study where weak intensity fluctuations were considered. The numerical propagation model is presented and tested with two-dimensional harmonic sound propagation over long paths and strong atmospheric perturbations. The results are compared to quantitative theoretical or numerical predictions available on the wave statistics, including the log-amplitude variance and the probability density functions of the complex acoustic pressure. The match is excellent for the evaluated source frequencies and all sound fluctuations strengths. Hence, this model captures these many aspects of strong atmospheric turbulence effects on sound propagation. Finally, the model results for the intensity probability density function are compared with a standard fit by a generalized gamma function.

  18. Channel Modeling for Air-to-Ground Wireless Communication

    Institute of Scientific and Technical Information of China (English)

    Yingcheng Shi; Di He; Bin Li; Jianwu Dou

    2015-01-01

    In this paper, we discuss several large⁃scale fading models for different environments. The COST231⁃Hata model is adapted for air⁃to⁃ground modeling. We propose two criteria for air⁃to⁃ground channel modelling based on test data derived from field testing in Beijing. We develop a new propagation model that is more suitable for air⁃to⁃ground communication that pre⁃vious models. We focus on improving this propagation model using the field test data.

  19. 3D Massive MIMO Systems: Channel Modeling and Performance Analysis

    KAUST Repository

    Nadeem, Qurrat-Ul-Ain

    2015-03-01

    Multiple-input-multiple-output (MIMO) systems of current LTE releases are capable of adaptation in the azimuth only. More recently, the trend is to enhance the system performance by exploiting the channel\\'s degrees of freedom in the elevation through the dynamic adaptation of the vertical antenna beam pattern. This necessitates the derivation and characterization of three-dimensional (3D) channels. Over the years, channel models have evolved to address the challenges of wireless communication technologies. In parallel to theoretical studies on channel modeling, many standardized channel models like COST-based models, 3GPP SCM, WINNER, ITU have emerged that act as references for industries and telecommunication companies to assess system-level and link-level performances of advanced signal processing techniques over real-like channels. Given the existing channels are only two dimensional (2D) in nature; a large effort in channel modeling is needed to study the impact of the channel component in the elevation direction. The first part of this work sheds light on the current 3GPP activity around 3D channel modeling and beamforming, an aspect that to our knowledge has not been extensively covered by a research publication. The standardized MIMO channel model is presented, that incorporates both the propagation effects of the environment and the radio effects of the antennas. In order to facilitate future studies on the use of 3D beamforming, the main features of the proposed 3D channel model are discussed. A brief overview of the future 3GPP 3D channel model being outlined for the next generation of wireless networks is also provided. In the subsequent part of this work, we present an information-theoretic channel model for MIMO systems that supports the elevation dimension. The model is based on the principle of maximum entropy, which enables us to determine the distribution of the channel matrix consistent with the prior information on the angles of departure and

  20. A BEM approach to validate a model for predicting sound propagation over non-flat terrain

    DEFF Research Database (Denmark)

    Quirós Alpera, Susana; Jacobsen, Finn; Juhl, Peter Møller;

    2003-01-01

    . Sound Vibrat. 223 (1999) 355]. The resulting BEM model, which can handle arbitrary combinations of barriers and hollows, has been used for validating a ray model for various difficult configurations, including combinations of valleys and barriers. (C) 2003 Elsevier Science Ltd. All rights reserved....

  1. CHANNEL MORPHOLOGY TOOL (CMT): A GIS-BASED AUTOMATED EXTRACTION MODEL FOR CHANNEL GEOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    JUDI, DAVID [Los Alamos National Laboratory; KALYANAPU, ALFRED [Los Alamos National Laboratory; MCPHERSON, TIMOTHY [Los Alamos National Laboratory; BERSCHEID, ALAN [Los Alamos National Laboratory

    2007-01-17

    This paper describes an automated Channel Morphology Tool (CMT) developed in ArcGIS 9.1 environment. The CMT creates cross-sections along a stream centerline and uses a digital elevation model (DEM) to create station points with elevations along each of the cross-sections. The generated cross-sections may then be exported into a hydraulic model. Along with the rapid cross-section generation the CMT also eliminates any cross-section overlaps that might occur due to the sinuosity of the channels using the Cross-section Overlap Correction Algorithm (COCoA). The CMT was tested by extracting cross-sections from a 5-m DEM for a 50-km channel length in Houston, Texas. The extracted cross-sections were compared directly with surveyed cross-sections in terms of the cross-section area. Results indicated that the CMT-generated cross-sections satisfactorily matched the surveyed data.

  2. MODELING OF VEHICULAR STEERING EFFICIENCY IN TRAFFIC DIRECTION MOTION CHANNEL

    OpenAIRE

    V. A. Ganai; S. A. O. Diab Abdullah

    2011-01-01

    The paper formulates and solves an actual problem pertaining to vehicular steering efficiency in traffic direction motion channel. Models of operator-drivers with low, medium and high rates in motivational perception of road conditions and also a model for controlling a traffic direction motion have been taken into ccount in the paper.  Modeling has been done by using MATLAB.

  3. Development of a GPU-based high-performance radiative transfer model for the Infrared Atmospheric Sounding Interferometer (IASI)

    International Nuclear Information System (INIS)

    Satellite-observed radiance is a nonlinear functional of surface properties and atmospheric temperature and absorbing gas profiles as described by the radiative transfer equation (RTE). In the era of hyperspectral sounders with thousands of high-resolution channels, the computation of the radiative transfer model becomes more time-consuming. The radiative transfer model performance in operational numerical weather prediction systems still limits the number of channels we can use in hyperspectral sounders to only a few hundreds. To take the full advantage of such high-resolution infrared observations, a computationally efficient radiative transfer model is needed to facilitate satellite data assimilation. In recent years the programmable commodity graphics processing unit (GPU) has evolved into a highly parallel, multi-threaded, many-core processor with tremendous computational speed and very high memory bandwidth. The radiative transfer model is very suitable for the GPU implementation to take advantage of the hardware's efficiency and parallelism where radiances of many channels can be calculated in parallel in GPUs. In this paper, we develop a GPU-based high-performance radiative transfer model for the Infrared Atmospheric Sounding Interferometer (IASI) launched in 2006 onboard the first European meteorological polar-orbiting satellites, METOP-A. Each IASI spectrum has 8461 spectral channels. The IASI radiative transfer model consists of three modules. The first module for computing the regression predictors takes less than 0.004% of CPU time, while the second module for transmittance computation and the third module for radiance computation take approximately 92.5% and 7.5%, respectively. Our GPU-based IASI radiative transfer model is developed to run on a low-cost personal supercomputer with four GPUs with total 960 compute cores, delivering near 4 TFlops theoretical peak performance. By massively parallelizing the second and third modules, we reached 364x

  4. FLOOD ROUTING MODELS IN CONFLUENT AND DIVIDING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    范平; 李家春; 刘青泉

    2004-01-01

    By introducing a water depth connecting formula, the hydraulic equations in the dividing channel system were coupled and the relation of discharge distribution between the branches of the dividing channels can be yielded. In this manner, a numerical model for the confluent channels was established to study the variation of backwater effects with the parameters in the channel junction. The meeting of flood peaks in the mainstream and tributary can be analyzed with this model. The flood peak meeting is found to be a major factor for the extremely high water level in the mainstream during the 1998 Yangtze River flood. Subsequently the variations of discharge distribution and water level with channel parameters between each branch in this system were studied as well. As a result, flood evolution caused by Jingjiang River shortcut and sediment deposition in the entrance of dividing channels of the Yangtze River may be qualitatively elucidated. It is suggested to be an effective measure for flood mitigation to enhance regulation capability of reservoirs available upstream of the tributaries and harness branch entrance channels.

  5. Modeling Channelization in Coastal Wetlands with Ecological Feedbacks

    Science.gov (United States)

    Hughes, Z. J.; Mahadevan, A.; Pennings, S.; FitzGerald, D.

    2014-12-01

    In coastal wetlands in Georgia and South Carolina, dendritic channel networks are actively incising headward at the rate of nearly 2 m/yr. The future geomorphic evolution of these marshes remains in question as rates of relative sea-level rise increase. Our objective is to understand the mechanisms that lead to the evolution of these channel networks through field observations and modeling. We model the geomorphological evolution of tidal creeks by viewing the wetland as a permeable medium. The porosity of the medium affects its hydraulic conductivity, which in turn is altered by erosion. Our multiphase model spontaneously generates channelization and branching networks through flow and erosion. In our field studies, we find that crabs play an active role in grazing vegetation and in the bioturbation of sediments. These effects are incorporated in our model based on field and laboratory observations of crab behavior and its effects on the marsh. We find the erosional patterns and channelization are significantly altered by the faunal feedback. Crabs enhance the growth of channels, inducing the headward erosion of creeks where flow-induced stresses are weakest. They are instrumental in generating high rates of creek extension, which channelize the marsh more effectively in response to sea-level rise. This indicates that the evolution of coastal wetlands is responding to interactions between physics and ecology and highlights the importance of the faunal contribution to these feedbacks.

  6. An empirical conceptual gully evolution model for channelled sea cliffs

    Science.gov (United States)

    Leyland, Julian; Darby, Stephen E.

    2008-12-01

    Incised coastal channels are a specific form of incised channel that are found in locations where stream channels flowing to cliffed coasts have the excess energy required to cut down through the cliff to reach the outlet water body. The southern coast of the Isle of Wight, southern England, comprises soft cliffs that vary in height between 15 and 100 m and which are retreating at rates ≤ 1.5 m a - 1 , due to a combination of wave erosion and landslides. In several locations, river channels have cut through the cliffs to create deeply (≤ 45 m) incised gullies, known locally as 'Chines'. The Chines are unusual in that their formation is associated with dynamic shoreline encroachment during a period of rising sea-level, whereas existing models of incised channel evolution emphasise the significance of base level lowering. This paper develops a conceptual model of Chine evolution by applying space for time substitution methods using empirical data gathered from Chine channel surveys and remotely sensed data. The model identifies a sequence of evolutionary stages, which are classified based on a suite of morphometric indices and associated processes. The extent to which individual Chines are in a state of growth or decay is estimated by determining the relative rates of shoreline retreat and knickpoint recession, the former via analysis of historical aerial images and the latter through the use of a stream power erosion model.

  7. A Semi-Deterministic Channel Model for VANETs Simulations

    Directory of Open Access Journals (Sweden)

    Jonathan Ledy

    2012-01-01

    Full Text Available Today's advanced simulators facilitate thorough studies on Vehicular Ad hoc NETworks (VANETs. However the choice of the physical layer model in such simulators is a crucial issue that impacts the results. A solution to this challenge might be found with a hybrid model. In this paper, we propose a semi-deterministic channel propagation model for VANETs called UM-CRT. It is based on CRT (Communication Ray Tracer and SCME—UM (Spatial Channel Model Extended—Urban Micro which are, respectively, a deterministic channel simulator and a statistical channel model. It uses a process which adjusts the statistical model using relevant parameters obtained from the deterministic simulator. To evaluate realistic VANET transmissions, we have integrated our hybrid model in fully compliant 802.11 p and 802.11 n physical layers. This framework is then used with the NS-2 network simulator. Our simulation results show that UM-CRT is adapted for VANETs simulations in urban areas as it gives a good approximation of realistic channel propagation mechanisms while improving significantly simulation time.

  8. Numerical modelling of channel migration with application to laboratory rivers

    Institute of Scientific and Technical Information of China (English)

    Jian SUN; Bin-liang LIN; Hong-wei KUANG

    2015-01-01

    The paper presents the development of a morphological model and its application to experimental model rivers. The model takes into account the key processes of channel migration, including bed deformation, bank failure and wetting and drying. Secondary flows in bends play an important role in lateral sediment transport, which further affects channel migration. A new formula has been derived to predict the near-bed secondary flow speed, in which the magnitude of the speed is linked to the lateral water level gradient. Since only non-cohesive sediment is considered in the current study, the bank failure is modelled based on the concept of submerged angle of repose. The wetting and drying process is modelled using an existing method. Comparisons between the numerical model predictions and experimental observations for various discharges have been made. It is found that the model predicted channel planform and cross-sectional shapes agree generally well with the laboratory observations. A scenario analysis is also carried out to investigate the impact of secondary flow on the channel migration process. It shows that if the effect of secondary flow is ignored, the channel size in the lateral direction will be seriously underestimated.

  9. a Diagnostic System Measuring Orthogonal Factors of Sound Fields in a Scale Model of Auditorium

    Science.gov (United States)

    SAKURAI, M.; AIZAWA, S.; SUZUMURA, Y.; ANDO, Y.

    2000-04-01

    Based on the model of auditory-brain system which consists of the autocorrelation mechanism, the interaural cross-correlation mechanism between both the auditory pathways, and the specialization of human cerebral hemispheres (Y. Ando 1998 Architectural Acoustics, Blending Sound Sources, Sound Fields, and Listeners New York: AIP Press/Springer-Verlag), a new diagnostic system was developed. After obtaining the binaural impulse response, four orthogonal factors including the SPL, the initial time-delay gap between the direct sound and the first reflection, the subsequent reverberation time and the IACC can be analyzed for the calculation of the scale values of both global and individual subjective preferences. In addition, two more factors extracted from the interaural cross-correlation functionτIACC and WIACC, can be figured out. Also, the sound energy,Φ (0), the effective duration, τe, and fine structures of autocorrelation function of sound signals including the magnitude of first maximum, φ1, and its delay time,τ1 , can be analyzed. As an example of the measurement, effects of reflectors' array above the stage in a 1/10 scale model of auditorium at each seat are discussed here.

  10. Dynamic Propagation Channel Characterization and Modeling for Human Body Communication

    OpenAIRE

    Lei Wang; Jingjing Ma; Zhicheng Li; Hong Chen; Zedong Nie

    2012-01-01

    This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC). In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000) were acquired from five volunteers. Various path gains caused by di...

  11. Simulated masking of right whale sounds by shipping noise: incorporating a model of the auditory periphery.

    Science.gov (United States)

    Cunningham, Kane A; Mountain, David C

    2014-03-01

    Many species of large, mysticete whales are known to produce low-frequency communication sounds. These low-frequency sounds are susceptible to communication masking by shipping noise, which also tends to be low frequency in nature. The size of these species makes behavioral assessment of auditory capabilities in controlled, captive environments nearly impossible, and field-based playback experiments are expensive and necessarily limited in scope. Hence, it is desirable to produce a masking model for these species that can aid in determining the potential effects of shipping and other anthropogenic noises on these protected animals. The aim of this study was to build a model that combines a sophisticated representation of the auditory periphery with a spectrogram-based decision stage to predict masking levels. The output of this model can then be combined with a habitat-appropriate propagation model to calculate the potential effects of noise on communication range. For this study, the model was tested on three common North Atlantic right whale communication sounds, both to demonstrate the method and to probe how shipping noise affects the detection of sounds with varying spectral and temporal characteristics. PMID:24606298

  12. Real-Time Conversion of Stereo Audio to 5.1 Channel Audio for Providing Realistic Sounds

    Directory of Open Access Journals (Sweden)

    Chan Jun Chun

    2009-12-01

    Full Text Available In this paper, we address issues associated with the real-time implementation of upmixing stereo audio into 5.1 channel audio in order to improve audio realism. First, we review four different upmixing methods, including a passive surround decoding method, a least-meansquare based upmixing method, a principal component analysis based upmixing method, and an adaptive panning method. After that, we implement a simulator that includes the upmixingmethods and audio controls to play both stereo and upmixed 5.1 channel audio signals. Finally, we carry out a MUSHRA test to compare the quality of the upmixed 5.1 channel audio signals to that of the original stereo audio signal. It is shown from the test that the upmixed 5.1 channel audio signals generated by the four different upmixing methods are preferred to the original stereo audio signals.

  13. Model studies of dense water overflows in the Faroese Channels

    Science.gov (United States)

    Cuthbertson, Alan; Davies, Peter; Stashchuk, Nataliya; Vlasenko, Vasiliy

    2014-01-01

    The overflow of dense water from the Nordic Seas through the Faroese Channel system was investigated through combined laboratory experiments and numerical simulations using the Massachusetts Institute of Technology General Circulation Model. In the experimental study, a scaled, topographic representation of the Faroe-Shetland Channel, Wyville-Thomson Basin and Ridge and Faroe Bank Channel seabed bathymetry was constructed and mounted in a rotating tank. A series of parametric experiments was conducted using dye-tracing and drogue-tracking techniques to investigate deep-water overflow pathways and circulation patterns within the modelled region. In addition, the structure of the outflowing dense bottom water was investigated through density profiling along three cross-channel transects located in the Wyville-Thomson Basin and the converging, up-sloping approach to the Faroe Bank Channel. Results from the dye-tracing studies demonstrate a range of parametric conditions under which dense water overflow across the Wyville-Thomson Ridge is shown to occur, as defined by the Burger number, a non-dimensional length ratio and a dimensionless dense water volume flux parameter specified at the Faroe-Shetland Channel inlet boundary. Drogue-tracking measurements reveal the complex nature of flow paths and circulations generated in the modelled topography, particularly the development of a large anti-cyclonic gyre in the Wyville-Thompson Basin and up-sloping approach to the Faroe Bank Channel, which diverts the dense water outflow from the Faroese shelf towards the Wyville-Thomson Ridge, potentially promoting dense water spillage across the ridge itself. The presence of this circulation is also indicated by associated undulations in density isopycnals across the Wyville-Thomson Basin. Numerical simulations of parametric test cases for the main outflow pathways and density structure in a similarly-scaled Faroese Channels model domain indicate excellent qualitative agreement with

  14. Ferroelectric active models of ion channels in biomembranes.

    Science.gov (United States)

    Bystrov, V S; Lakhno, V D; Molchanov, M

    1994-06-21

    Ferroactive models of ion channels in the theory of biological membranes are presented. The main equations are derived and their possible solutions are shown. The estimates of some experimentally measured parameters are given. Possible physical consequences of the suggested models are listed and the possibility of their experimental finding is discussed. The functioning of the biomembrane's ion channel is qualitatively described on the basis of the suggested ferroactive models. The main directions and prospects for development of the ferroactive approach to the theory of biological membranes and their structures are indicated.

  15. The reconstruction of sound speed in the Marmousi model by the boundary control method

    CERN Document Server

    Ivanov, I B; Semenov, V S

    2016-01-01

    We present the results on numerical testing of the Boundary Control Method in the sound speed determination for the acoustic equation on semiplane. This method for solving multidimensional inverse problems requires no a priory information about the parameters under reconstruction. The application to the realistic Marmousi model demonstrates that the boundary control method is workable in the case of complicated and irregular field of acoustic rays. By the use of the chosen boundary controls, an `averaged' profile of the sound speed is recovered (the relative error is about $10-15\\%$). Such a profile can be further utilized as a starting approximation for high resolution iterative reconstruction methods.

  16. Modelling of horn-type loudspeakers for outdoor sound reinforcement systems

    DEFF Research Database (Denmark)

    Schuhmacher, Andreas; Rasmussen, Karsten Bo

    1999-01-01

    -type loudspeakers is made. The agreement between measured and calculated results is very good provided that a sufficient number of modes is included in the simulation. Simulation models of this kind represent one of the first steps towards a CAD tool for outdoor sound reinforcement systems....

  17. Sound transmission through pipe systems and into plate structures in buildings. A simplified sea model

    NARCIS (Netherlands)

    Bron-van der Jagt, G.S.

    2007-01-01

    In the study presented, it has been investigated whether Statistical Energy Analysis (SEA) could be applied in a simplified way as a framework for a prediction model regarding noise due to service equipment, specifically sound transmission within (plastic wastewater) pipe systems and between these p

  18. A transparency model and its applications for simulation of reflector arrays and sound transmission (A)

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2006-01-01

    The paper describes a new method for simulating the frequency-dependent reflection and transmission of reflector arrays, and the frequency-dependent airborne sound insulation between rooms by means of a room acoustic computer model. The method makes use of a transparency method in the ray-tracing...

  19. Ab initio calculation of the sound velocity of dense hydrogen: implications for models of Jupiter

    NARCIS (Netherlands)

    Alavi, A.; Parrinello, M.; Frenkel, D.

    1995-01-01

    First-principles molecular dynamics simulations were used to calculate the sound velocity of dense hydrogen, and the results were compared with extrapolations of experimental data that currently conflict with either astrophysical models or data obtained from recent global oscillation measurements of

  20. Prince William Sound, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  1. Puget Sound Recreational Shellfish Harvesting Survey - Model Intended Angler Behavior

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collect and analyze survey data from recreational saltwater fishermen in Oregon and Washington. Model trip demand using stated frequency / contingent behavior data....

  2. Monte Carlo Modeling of Crystal Channeling at High Energies

    CERN Document Server

    Schoofs, Philippe; Cerutti, Francesco

    Charged particles entering a crystal close to some preferred direction can be trapped in the electromagnetic potential well existing between consecutive planes or strings of atoms. This channeling effect can be used to extract beam particles if the crystal is bent beforehand. Crystal channeling is becoming a reliable and efficient technique for collimating beams and removing halo particles. At CERN, the installation of silicon crystals in the LHC is under scrutiny by the UA9 collaboration with the goal of investigating if they are a viable option for the collimation system upgrade. This thesis describes a new Monte Carlo model of planar channeling which has been developed from scratch in order to be implemented in the FLUKA code simulating particle transport and interactions. Crystal channels are described through the concept of continuous potential taking into account thermal motion of the lattice atoms and using Moliere screening function. The energy of the particle transverse motion determines whether or n...

  3. Modeling the Noise for Indoor Power Line Channel

    Directory of Open Access Journals (Sweden)

    Syed Samser Ali

    2013-07-01

    Full Text Available Electromagnetic interference, man-made noise, and multipath effects are main causes of bit errors in power-line communication. To design an efficient powerline transmission system, the channel characterization has to be known and this paper deals with a statistical noise model (SNM for the indoor powerline channel in a frequency band from 1 MHz to 30 MHz . The SNM parameters are obtained from large-scale measurements of the noise density spectrum on a real powerline channel. All measurements are between line and neutral at different locations in the same grid. The SNM is used for simulation of the noise density spectrum and offline analysis on the powerline channel

  4. Map-Based Channel Model for Urban Macrocell Propagation Scenarios

    Directory of Open Access Journals (Sweden)

    Jose F. Monserrat

    2015-01-01

    Full Text Available The evolution of LTE towards 5G has started and different research projects and institutions are in the process of verifying new technology components through simulations. Coordination between groups is strongly recommended and, in this sense, a common definition of test cases and simulation models is needed. The scope of this paper is to present a realistic channel model for urban macrocell scenarios. This model is map-based and takes into account the layout of buildings situated in the area under study. A detailed description of the model is given together with a comparison with other widely used channel models. The benchmark includes a measurement campaign in which the proposed model is shown to be much closer to the actual behavior of a cellular system. Particular attention is given to the outdoor component of the model, since it is here where the proposed approach is showing main difference with other previous models.

  5. A channel transmission losses model for different dryland rivers

    Directory of Open Access Journals (Sweden)

    A. C. Costa

    2011-10-01

    Full Text Available Channel transmission losses in drylands take place normally in extensive alluvial channels or streambeds underlain by fractured rocks. They can play an important role in flood prediction, groundwater recharge, freshwater supply and channel-associated ecosystems. We aim to develop a semi-distributed channel transmission losses model, a coupling of formulations which are more suitable for data-scarce dryland environments, applicable for both hydraulically disconnected losing streams and hydraulically connected losing(/gaining streams. Hence, this approach should be able to cover a large variation in climate and hydro-geologic controls, which are typically found in dryland regions of the world. Traditionally, channel transmission losses models have been developed for site specific conditions. Our model was firstly evaluated for a losing/gaining, hydraulically connected 30 km reach of the Jaguaribe River, Ceará, Brazil, which controls a catchment area of 20 000 km2. Secondly, we applied it to a small losing, hydraulically disconnected 1.5 km channel reach in the Walnut Gulch Experimental Watershed (WGEW, Arizona, USA. The model based on the perceptual hydrological models of the reaches was able to predict reliably the stream flow for the both case studies. For the larger river reach, the evaluation of the hypotheses on the dominant hydrological processes was fundamental for reducing structural model uncertainties and improving the stream flow prediction, showing that both lateral stream-aquifer water fluxes and groundwater flow in the underlying alluvium parallel to the river course are necessary to predict stream flow and channel transmission losses, the former process being more relevant than the latter. The sensitivity analysis showed that even if the parameters can "potentially" produce large flow exchanges between model units in the saturated part of the modelling, large flow exchanges do not happen because they are restricted by

  6. An Analytic Model of Subminiature Auditory Sensation System for Sound Source Localization

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-sheng; TA Na; RAO Zhu-shi

    2007-01-01

    Abstract.It is reported that some types of insects have a remarkable ability to detect the direction of an incident sound even though its acoustic sensory organs are in very close proximity each other. Maybe the ears are jointed by a cuticular structure with which the separated motions can be coupled mechanically and thus be magnified. In this paper, a detailed model is setup to describe the principle of this type of localization using a mechanical coupled structure. The transfer functions and the responses of the model in terms of time and frequency are analyzed to describe the mechanism of its ability of directional hearing. This analytical model provides a method to design the experimental model for the predetermined incident sound pressure, and the analysis of this model shows that this structure have the ability to determine the direction of the incident stimulus.

  7. Channel Measurements and Modelling for Indoor Power Line Communications

    Directory of Open Access Journals (Sweden)

    Zhang Peiling

    2013-04-01

    Full Text Available In order to obtain power line communications channel transmission characteristics, impulse responses measurements were performed on the basis of PN sequence’s excellent periodic autocorrelation properties. Meanwhile, a compensation method in frequency domain was proposed to improve the measurement precision. Then, the empirical multipath channel model of power line is presented from the measured results. The simulation and experimental measurement results not only have verified the efficiency of the proposed model, but also showed that the measurement method has fast, simple and convenient characteristic. Finally, the statistical characteristics of path amplitude and the delay spread are obtained through the analysis of measured results.

  8. A speech processing study using an acoustic model of a multiple-channel cochlear implant

    Science.gov (United States)

    Xu, Ying

    1998-10-01

    A cochlear implant is an electronic device designed to provide sound information for adults and children who have bilateral profound hearing loss. The task of representing speech signals as electrical stimuli is central to the design and performance of cochlear implants. Studies have shown that the current speech- processing strategies provide significant benefits to cochlear implant users. However, the evaluation and development of speech-processing strategies have been complicated by hardware limitations and large variability in user performance. To alleviate these problems, an acoustic model of a cochlear implant with the SPEAK strategy is implemented in this study, in which a set of acoustic stimuli whose psychophysical characteristics are as close as possible to those produced by a cochlear implant are presented on normal-hearing subjects. To test the effectiveness and feasibility of this acoustic model, a psychophysical experiment was conducted to match the performance of a normal-hearing listener using model- processed signals to that of a cochlear implant user. Good agreement was found between an implanted patient and an age-matched normal-hearing subject in a dynamic signal discrimination experiment, indicating that this acoustic model is a reasonably good approximation of a cochlear implant with the SPEAK strategy. The acoustic model was then used to examine the potential of the SPEAK strategy in terms of its temporal and frequency encoding of speech. It was hypothesized that better temporal and frequency encoding of speech can be accomplished by higher stimulation rates and a larger number of activated channels. Vowel and consonant recognition tests were conducted on normal-hearing subjects using speech tokens processed by the acoustic model, with different combinations of stimulation rate and number of activated channels. The results showed that vowel recognition was best at 600 pps and 8 activated channels, but further increases in stimulation rate and

  9. Speech sound acquisition, coarticulation, and rate effects in a neural network model of speech production.

    Science.gov (United States)

    Guenther, F H

    1995-07-01

    This article describes a neural network model of speech motor skill acquisition and speech production that explains a wide range of data on variability, motor equivalence, coarticulation, and rate effects. Model parameters are learned during a babbling phase. To explain how infants learn language-specific variability limits, speech sound targets take the form of convex regions, rather than points, in orosensory coordinates. Reducing target size for better accuracy during slower speech leads to differential effects for vowels and consonants, as seen in experiments previously used as evidence for separate control processes for the 2 sound types. Anticipatory coarticulation arises when targets are reduced in size on the basis of context; this generalizes the well-known look-ahead model of coarticulation. Computer simulations verify the model's properties. PMID:7624456

  10. Development of a hybrid wave based-transfer matrix model for sound transmission analysis.

    Science.gov (United States)

    Dijckmans, A; Vermeir, G

    2013-04-01

    In this paper, a hybrid wave based-transfer matrix model is presented that allows for the investigation of the sound transmission through finite multilayered structures placed between two reverberant rooms. The multilayered structure may consist of an arbitrary configuration of fluid, elastic, or poro-elastic layers. The field variables (structural displacements and sound pressures) are expanded in terms of structural and acoustic wave functions. The boundary and continuity conditions in the rooms determine the participation factors in the pressure expansions. The displacement of the multilayered structure is determined by the mechanical impedance matrix, which gives a relation between the pressures and transverse displacements at both sides of the structure. The elements of this matrix are calculated with the transfer matrix method. First, the hybrid model is numerically validated. Next a comparison is made with sound transmission loss measurements of a hollow brick wall and a sandwich panel. Finally, numerical simulations show the influence of structural damping, room dimensions and plate dimensions on the sound transmission loss of multilayered structures.

  11. Incorporating Midbrain Adaptation to Mean Sound Level Improves Models of Auditory Cortical Processing

    OpenAIRE

    Harper, NS; Willmore, BDB; Schnupp, JWH; King, AJ; Schoppe, O

    2016-01-01

    Adaptation to stimulus statistics, such as the mean level and contrast of recently- heard sounds, has been demonstrated at various levels of the auditory pathway. It allows the nervous system to operate over the wide range of intensities and contrasts found in the natural world. Yet, current standard models of the response properties of auditory neurons do not incorporate such adaptation. Here, we present a model of neural responses in the ferret auditory cortex (the I...

  12. Radio Channel Sounding Using a Circular Horn Antenna Array in the Horizontal Plane in the 2.3 GHz Band

    DEFF Research Database (Denmark)

    Yamamoto, Atsushi; Sakata, Tsutomu; Ogawa, Koichi;

    2012-01-01

    This paper presents results from an outdoor radio propagation experiment at 2.35 GHz using a channel sounder and a spherical horn antenna array. The propagation test was performed in Aalborg city in Denmark. Comparing the ray-tracing results and the results obtained with the proposed method...

  13. A Mathematical Model of Membrane Gas Separation with Energy Transfer by Molecules of Gas Flowing in a Channel to Molecules Penetrating this Channel from the Adjacent Channel

    Directory of Open Access Journals (Sweden)

    Szwast Maciej

    2015-06-01

    Full Text Available The paper presents the mathematical modelling of selected isothermal separation processes of gaseous mixtures, taking place in plants using membranes, in particular nonporous polymer membranes. The modelling concerns membrane modules consisting of two channels - the feeding and the permeate channels. Different shapes of the channels cross-section were taken into account. Consideration was given to co-current and counter-current flows, for feeding and permeate streams, respectively, flowing together with the inert gas receiving permeate. In the proposed mathematical model it was considered that pressure of gas changes along the length of flow channels was the result of both - the drop of pressure connected with flow resistance, and energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel. The literature on membrane technology takes into account only the drop of pressure connected with flow resistance. Consideration given to energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel constitute the essential novelty in the current study. The paper also presents results of calculations obtained by means of a computer program which used equations of the derived model. Physicochemical data concerning separation of the CO2/CH4 mixture with He as the sweep gas and data concerning properties of the membrane made of PDMS were assumed for calculations.

  14. MODELING OF VEHICULAR STEERING EFFICIENCY IN TRAFFIC DIRECTION MOTION CHANNEL

    Directory of Open Access Journals (Sweden)

    V. A. Ganai

    2011-01-01

    Full Text Available The paper formulates and solves an actual problem pertaining to vehicular steering efficiency in traffic direction motion channel. Models of operator-drivers with low, medium and high rates in motivational perception of road conditions and also a model for controlling a traffic direction motion have been taken into ccount in the paper.  Modeling has been done by using MATLAB.

  15. Sound speed and oscillation frequencies for solar models evolved with Los Alamos ATOMIC opacities

    CERN Document Server

    Guzik, Joyce A; Walczak, P; Wood, S R; Mussack, K; Farag, E

    2016-01-01

    Los Alamos National Laboratory has calculated a new generation of radiative opacities (OPLIB data using the ATOMIC code) for elements with atomic number Z=1-30 with improved physics input, updated atomic data, and finer temperature grid to replace the Los Alamos LEDCOP opacities released in the year 2000. We calculate the evolution of standard solar models including these new opacities, and compare with models evolved using the Lawrence Livermore National Laboratory OPAL (Iglesias and Rogers 1996) opacities. We use the solar abundance mixture of Asplund et al. (2009). The new Los Alamos ATOMIC opacities have steeper opacity derivatives than those of OPAL for temperatures and densities of the solar interior radiative zone. We compare the calculated nonadiabatic solar oscillation frequencies and solar interior sound speed to observed frequencies and helioseismic inferences. The calculated sound-speed profiles are similar for models evolved using either the updated Iben evolution code (see \\cite{Guzik2010}), or ...

  16. Application of Bayesian Hierarchical Prior Modeling to Sparse Channel Estimation

    DEFF Research Database (Denmark)

    Pedersen, Niels Lovmand; Manchón, Carles Navarro; Shutin, Dmitriy;

    2012-01-01

    Existing methods for sparse channel estimation typically provide an estimate computed as the solution maximizing an objective function defined as the sum of the log-likelihood function and a penalization term proportional to the l1-norm of the parameter of interest. However, other penalization...... terms have proven to have strong sparsity-inducing properties. In this work, we design pilot assisted channel estimators for OFDM wireless receivers within the framework of sparse Bayesian learning by defining hierarchical Bayesian prior models that lead to sparsity-inducing penalization terms...

  17. Modelling of the new FLNR magnetic analyzer vacuum channel

    International Nuclear Information System (INIS)

    The quality of any magnetic analyzer directly depends on the area of radial cross section of its volume filled with the ions trajectories. The conception of new magnetic spectrometer vacuum channel is based on computer modelling of the maximum filling of the spectrometer acceptance with given pole pieces width and the gap height of the magnetic dipole together with the maximum transmission of underflected in magnetic field emission from the target at the angle of measurements. The correct correlation of the aperture of the vacuum channel with durability, engineering and ease of handling characteristics combined with ion-optical properties of the spectrometer determines its construction in the whole

  18. Blind channel identication of nonlinear folding mixing model

    Institute of Scientific and Technical Information of China (English)

    Su Yong; Xu Shangzhi; Ye Zhongfu

    2006-01-01

    Signals from multi-sensor systems are often mixtures of (statistically) independent sources by unknown mixing method. Blind source separation(BSS) and independent component analysis(ICA) are the methods to identify/recover the channels and the sources. BSS/ICA of nonlinear mixing models are difficult problems. For instance, the post-nonlinear model has been studied by several authors. It is noticed that in most cases, the proposed models are always with an invertible mixing. According to this fact there is an interesting question: how about the situation of the non-invertible non-linear mixing in BSS or ICA? A new simple non-linear mixing model is proposed with a kind of non-invertible mixing, the folding mixing, and method to identify its channel, blindly.

  19. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    Science.gov (United States)

    Cañete, Francisco J.; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J.; Paris, José F.

    2016-01-01

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression. PMID:26907281

  20. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    Directory of Open Access Journals (Sweden)

    Francisco J. Cañete

    2016-02-01

    Full Text Available Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  1. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications.

    Science.gov (United States)

    Cañete, Francisco J; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J; Paris, José F

    2016-01-01

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  2. The FPGA Implementation of Short—Wave Channel Model

    Institute of Scientific and Technical Information of China (English)

    GANLiangcai; LIYuanyuan

    2003-01-01

    Based on the characteristic of timevariance,short-wave channel can be modeled as a real-time tors of fllter in frequency domain,the model can simulate short-wave channel exactly,such as delay spread,Doppler shift and Doppler spread.In the design,the bandwidth of short-wave channel model is 768kHz,and the frequency interval is 3kHz.A kind of Overlap-Discard algorithm based on the fast Fourier transform (FFT)is utilized to design the real-time FIR filter,and an architectural design structure based on Field Programmable Gate Arrays(FPGA)chip is adopted to implement 512-point FFT.The channel transfer function and the noise and interference function are periodically updated in real-time,which are stored in ROM in advance.The simulation result shows that the hardware implementation is simple and feasible and the wideband short-wave systems,such as frequency-hopping,direct sequence spread spectrum systems.

  3. A Unified Channel Charges Expression for Analytic MOSFET Modeling

    OpenAIRE

    Hugues Murray; Patrick Martin

    2012-01-01

    Based on a 1D Poissons equation resolution, we present an analytic model of inversion charges allowing calculation of the drain current and transconductance in the Metal Oxide Semiconductor Field Effect Transistor. The drain current and transconductance are described by analytical functions including mobility corrections and short channel effects (CLM, DIBL). The comparison with the Pao-Sah integral shows excellent accuracy of the model in all inversion modes from strong to weak inversion in ...

  4. Holographic zero sound at finite temperature in the Sakai-Sugimoto model

    CERN Document Server

    DiNunno, Brandon S; Jokela, Niko; Pedraza, Juan F

    2014-01-01

    In this paper, we study the fate of the holographic zero sound mode at finite temperature and non-zero baryon density in the deconfined phase of the Sakai-Sugimoto model of holographic QCD. We establish the existence of such a mode for a wide range of temperatures and investigate the dispersion relation, quasi-normal modes, and spectral functions of the collective excitations in four different regimes, namely, the collisionless quantum, collisionless thermal, and hydrodynamic regimes, as well as an intermediate crossover between the latter two. For sufficiently high temperatures, the zero sound completely disappears, and the physics is dominated by an emergent diffusive mode. We compare our findings to Landau-Fermi liquid theory and to other holographic models.

  5. Eluding the Physical Constraints in a Nonlinear Interaction Sound Synthesis Model for Gesture Guidance

    Directory of Open Access Journals (Sweden)

    Etienne Thoret

    2016-06-01

    Full Text Available In this paper, a flexible control strategy for a synthesis model dedicated to nonlinear friction phenomena is proposed. This model enables to synthesize different types of sound sources, such as creaky doors, singing glasses, squeaking wet plates or bowed strings. Based on the perceptual stance that a sound is perceived as the result of an action on an object we propose a genuine source/filter synthesis approach that enables to elude physical constraints induced by the coupling between the interacting objects. This approach makes it possible to independently control and freely combine the action and the object. Different implementations and applications related to computer animation, gesture learning for rehabilitation and expert gestures are presented at the end of this paper.

  6. Modeling the ascent of sounding balloons: derivation of the vertical air motion

    Directory of Open Access Journals (Sweden)

    A. Gallice

    2011-06-01

    Full Text Available A new model to describe the ascent of sounding balloons in the troposphere and lower stratosphere (up to ~30–35 km altitude is presented. Contrary to previous models, detailed account is taken of both the variation of the drag coefficient with altitude and the heat imbalance between the balloon and the atmosphere. To compensate for the lack of data on the drag coefficient of sounding balloons, a reference curve for the relationship between drag coefficient and Reynolds number is derived from a dataset of flights launched during the Lindenberg Upper Air Methods Intercomparisons (LUAMI campaign. The transfer of heat from the surrounding air into the balloon is accounted for by solving the radial heat diffusion equation inside the balloon. The potential applications of the model include the forecast of the trajectory of sounding balloons, which can be used to increase the accuracy of the match technique, and the derivation of the air vertical velocity. The latter is obtained by subtracting the ascent rate of the balloon in still air calculated by the model from the actual ascent rate. This technique is shown to provide an approximation for the vertical air motion with an uncertainty error of 0.5 m s−1 in the troposphere and 0.2 m s−1 in the stratosphere. An example of extraction of the air vertical velocity is provided in this paper. We show that the air vertical velocities derived from the balloon soundings in this paper are in general agreement with small-scale atmospheric velocity fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions measured during the SUCCESS campaign (Subsonic Aircraft: Contrail and Cloud Effects Special Study in the orographically unperturbed mid-latitude middle troposphere.

  7. Dynamic Propagation Channel Characterization and Modeling for Human Body Communication

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2012-12-01

    Full Text Available This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC. In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000 were acquired from five volunteers. Various path gains caused by different locations and movements were quantified and the statistical distributions were estimated. In general, for a given reference threshold è = −10 dB, the maximum average level crossing rate of the HBC was approximately 1.99 Hz, the maximum average fade time was 59.4 ms, and the percentage of bad channel duration time was less than 4.16%. The HBC exhibited a fade depth of −4 dB at 90% complementary cumulative probability. The statistical parameters were observed to be centered for each propagation channel. Subsequently a Fritchman model was implemented to estimate the burst characteristics of the on-body fading. It was concluded that the HBC is motion-insensitive, which is sufficient for reliable communication link during motions, and therefore it has great potential for body sensor/area networks.

  8. Explicit Numerical Modeling of Heat Transfer in Glacial Channels

    Science.gov (United States)

    Jarosch, A. H.; Zwinger, T.

    2015-12-01

    Turbulent flow and heat transfer of water in englacial channels is explicitly modelelled and the numerical results are compared to the most commonly used heat transfer parameterization in glaciology, i.e. the Dittus-Boelter equation. The three-dimensional flow is simulated by solving the incompressible Navier-Stokes equations utilizing a variational multiscale method (VMS) turbulence model and the finite-element method (i.e. Elmer-FEM software), which also solves the heat equation. By studying a wide range of key parameters of the system, e.g. channel diameter, Reynolds number, water flux, water temperature and Darcy-Weisbach wall roughness (which is explicitly represented on the wall geometry), it is found that the Dittus-Boelter equation is inadequate for glaciological applications and a new, highly suitable heat transfer parameterization for englacial/subglacial channels will be presented. This new parameterization utilizes a standard combination of dimensionless numbers describing the flow and channel (i.e. Reynolds number, Prandtl number and Darcy-Weisbach roughness) to predict a suitable Nusselt number describing the effective heat transfer and thus can be readily used in existing englacial/subglacial hydrology models.

  9. UWB channel modeling for indoor line-of-sight environment

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation, but for line-of-sight (LOS) case, it is not well defined. In this paper, a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters, the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling smallscale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions(CDFs) for the three key channel impulse response (CIR) statistics.

  10. A Wideband Channel Model for Intravehicular Nomadic Systems

    Directory of Open Access Journals (Sweden)

    François Bellens

    2011-01-01

    Full Text Available The increase in electronic entertainment equipments within vehicles has rendered the idea of replacing the wired links with intra-vehicle personal area networks. Ultra-wideband (UWB seems an appropriate candidate technology to meet the required data rates for interconnecting such devices. In particular, the multiband OFDM (MB-OFDM is able to provide very high transfer rates (up to 480 MBps over relatively short distances and low transmit power. In order to evaluate the performances of UWB systems within vehicles, a reliable channel model is needed. In this paper, a nomadic system where a base station placed in the center of the dashboard wants to communicate with fixed devices placed at the rear seat is investigated. A single-input single-output (SISO channel model for intra-vehicular communication (IVC systems is proposed, based on reverberation chamber theory. The model is based on measurements conducted in real traffic conditions, with a varying number of passengers in the car. Temporal variations of the wireless channels are also characterized and parametrized. The proposed model is validated by comparing model-independent statistics with the measurements.

  11. Modeling the ascent of sounding balloons: derivation of the vertical air motion

    Directory of Open Access Journals (Sweden)

    A. Gallice

    2011-10-01

    Full Text Available A new model to describe the ascent of sounding balloons in the troposphere and lower stratosphere (up to ∼30–35 km altitude is presented. Contrary to previous models, detailed account is taken of both the variation of the drag coefficient with altitude and the heat imbalance between the balloon and the atmosphere. To compensate for the lack of data on the drag coefficient of sounding balloons, a reference curve for the relationship between drag coefficient and Reynolds number is derived from a dataset of flights launched during the Lindenberg Upper Air Methods Intercomparisons (LUAMI campaign. The transfer of heat from the surrounding air into the balloon is accounted for by solving the radial heat diffusion equation inside the balloon. In its present state, the model does not account for solar radiation, i.e. it is only able to describe the ascent of balloons during the night. It could however be adapted to also represent daytime soundings, with solar radiation modeled as a diffusive process. The potential applications of the model include the forecast of the trajectory of sounding balloons, which can be used to increase the accuracy of the match technique, and the derivation of the air vertical velocity. The latter is obtained by subtracting the ascent rate of the balloon in still air calculated by the model from the actual ascent rate. This technique is shown to provide an approximation for the vertical air motion with an uncertainty error of 0.5 m s−1 in the troposphere and 0.2 m s−1 in the stratosphere. An example of extraction of the air vertical velocity is provided in this paper. We show that the air vertical velocities derived from the balloon soundings in this paper are in general agreement with small-scale atmospheric velocity fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions measured during the SUCCESS campaign (Subsonic Aircraft: Contrail and Cloud Effects

  12. The Audible Human Project: Modeling Sound Transmission in the Lungs and Torso

    Science.gov (United States)

    Dai, Zoujun

    Auscultation has been used qualitatively by physicians for hundreds of years to aid in the monitoring and diagnosis of pulmonary diseases. Alterations in the structure and function of the pulmonary system that occur in disease or injury often give rise to measurable changes in lung sound production and transmission. Numerous acoustic measurements have revealed the differences of breath sounds and transmitted sounds in the lung under normal and pathological conditions. Compared to the extensive cataloging of lung sound measurements, the mechanism of sound transmission in the pulmonary system and how it changes with alterations of lung structural and material properties has received less attention. A better understanding of sound transmission and how it is altered by injury and disease might improve interpretation of lung sound measurements, including new lung imaging modalities that are based on an array measurement of the acoustic field on the torso surface via contact sensors or are based on a 3-dimensional measurement of the acoustic field throughout the lungs and torso using magnetic resonance elastography. A long-term goal of the Audible Human Project (AHP ) is to develop a computational acoustic model that would accurately simulate generation, transmission and noninvasive measurement of sound and vibration within the pulmonary system and torso caused by both internal (e.g. respiratory function) and external (e.g. palpation) sources. The goals of this dissertation research, fitting within the scope of the AHP, are to develop specific improved theoretical understandings, computational algorithms and experimental methods aimed at transmission and measurement. The research objectives undertaken in this dissertation are as follows. (1) Improve theoretical modeling and experimental identification of viscoelasticity in soft biological tissues. (2) Develop a poroviscoelastic model for lung tissue vibroacoustics. (3) Improve lung airway acoustics modeling and its

  13. Speech sound discrimination training improves auditory cortex responses in a rat model of autism

    Directory of Open Access Journals (Sweden)

    Crystal T Engineer

    2014-08-01

    Full Text Available Children with autism often have language impairments and degraded cortical responses to speech. Extensive behavioral interventions can improve language outcomes and cortical responses. Prenatal exposure to the antiepileptic drug valproic acid (VPA increases the risk for autism and language impairment. Prenatal exposure to VPA also causes weaker and delayed auditory cortex responses in rats. In this study, we document speech sound discrimination ability in VPA exposed rats and document the effect of extensive speech training on auditory cortex responses. VPA exposed rats were significantly impaired at consonant, but not vowel, discrimination. Extensive speech training resulted in both stronger and faster anterior auditory field responses compared to untrained VPA exposed rats, and restored responses to control levels. This neural response improvement generalized to non-trained sounds. The rodent VPA model of autism may be used to improve the understanding of speech processing in autism and contribute to improving language outcomes.

  14. Designing, Modeling, Constructing, and Testing a Flat Panel Speaker and Sound Diffuser for a Simulator

    Science.gov (United States)

    Dillon, Christina

    2013-01-01

    The goal of this project was to design, model, build, and test a flat panel speaker and frame for a spherical dome structure being made into a simulator. The simulator will be a test bed for evaluating an immersive environment for human interfaces. This project focused on the loud speakers and a sound diffuser for the dome. The rest of the team worked on an Ambisonics 3D sound system, video projection system, and multi-direction treadmill to create the most realistic scene possible. The main programs utilized in this project, were Pro-E and COMSOL. Pro-E was used for creating detailed figures for the fabrication of a frame that held a flat panel loud speaker. The loud speaker was made from a thin sheet of Plexiglas and 4 acoustic exciters. COMSOL, a multiphysics finite analysis simulator, was used to model and evaluate all stages of the loud speaker, frame, and sound diffuser. Acoustical testing measurements were utilized to create polar plots from the working prototype which were then compared to the COMSOL simulations to select the optimal design for the dome. The final goal of the project was to install the flat panel loud speaker design in addition to a sound diffuser on to the wall of the dome. After running tests in COMSOL on various speaker configurations, including a warped Plexiglas version, the optimal speaker design included a flat piece of Plexiglas with a rounded frame to match the curvature of the dome. Eight of these loud speakers will be mounted into an inch and a half of high performance acoustic insulation, or Thinsulate, that will cover the inside of the dome. The following technical paper discusses these projects and explains the engineering processes used, knowledge gained, and the projected future goals of this project

  15. Thermally stratified sodium channel flow: turbulence and modeling

    International Nuclear Information System (INIS)

    Numerical simulation of sodium stratification in open channel flow has been studied with Computational Fluid Dynamics (CFD) employing an Algebraic Heat Flux Model (AHFM) closure for the turbulent heat flux. The results are validated against experimental data and the AHFM is compared with the simplified Reynolds analogy employing a constant turbulent Pr number. Influence of buoyancy on turbulence created in the mixing layer has been evaluated and its influence on the momentum and energy transport in the vertical direction assessed. It has been found that the choice of turbulent heat flux model influences the achieved results for temperature and velocity field which might affect the flow developing and persistence of stratification in the channel. Moreover both experiment and validation show the possibility of creation of a strong stratification also for low Pr number fluids, warning the stratification problem as an existing phenomenon likely to occur in liquid metal nuclear power plants. (author)

  16. Cascaded Network Body Channel Model for Intrabody Communication.

    Science.gov (United States)

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement. PMID:26111404

  17. Cascaded Network Body Channel Model for Intrabody Communication.

    Science.gov (United States)

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement.

  18. Basic equations of channel model for underground coal gasification

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The underground coal gasification has advantages of zero rubbish, nonpollution, low cost and high safety. According to the characteristics of the gasification, the channel model of chemical fluid mechanics is used to set up the fluid equations and chemical equations by some reasonable suppositions in this paper, which lays a theoretical foundation on requirements of fluid movement rules in the process of underground coal gasification.

  19. Modeling magnetosensitive ion channels in viscoelastic environment of living cells

    CERN Document Server

    Goychuk, Igor

    2015-01-01

    We propose and study a model of hypothetical magnetosensitive ionic channels which are long thought to be a possible candidate to explain the influence of weak magnetic fields on living organisms ranging from magnetotactic bacteria to fishes, birds, rats, bats and other mammals including humans. The core of the model is provided by a short chain of magnetosomes serving as a sensor which is coupled by elastic linkers to the gating elements of ion channels forming a small cluster in the cell membrane. The magnetic sensor is fixed by one end on cytoskeleton elements attached to the membrane and is exposed to viscoelastic cytosol. Its free end can reorient stochastically and subdiffusively in viscoelastic cytosol responding to external magnetic field changes and open the gates of coupled ion channels. The sensor dynamics is generally bistable due to bistability of the gates which can be in two states with probabilities which depend on the sensor orientation. For realistic parameters, it is shown that this model c...

  20. Numerical and Physical Modeling of the Response of Resonator Liners to Intense Sound and High Speed Grazing Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative research program is proposed that numerically and physically models the response of resonator liners to intense sound and high speed grazing flow. The...

  1. Differences in directional sound source behavior and perception between assorted computer room models

    DEFF Research Database (Denmark)

    Vigeant, M. C.; Wang, L. M.; Rindel, Jens Holger

    2004-01-01

    . The effect of changing the room's material properties was studied in relation to turning the source around 180 deg and on the range of acoustic parameters from the four- and 13 beams. As the room becomes increasingly diffuse, the importance of the modeled directivity decreases when considering reverberation...... time. However, for the three other parameters evaluated (sound-pressure level, clarity index, and lateral fraction), the changing diffusivity of the room does not diminish the importance of the directivity. The study therefore shows the importance of considering source directivity when using computer...... modeling. [Work supported by the National Science Foundation.]...

  2. Differences in directional sound source behavior and perception between assorted computer room models

    DEFF Research Database (Denmark)

    Vigeant, Michelle C.; Wang, Lily M.; Rindel, Jens Holger

    2004-01-01

    pursued. The effect of changing the room’s material properties was studied in relation to turning the source around 180 degrees and on the range of acoustic parameters from the four and thirteen beams. As the room becomes increasingly diffuse, the importance of the modeled directivity decreases when...... considering reverberation time. However, for the three other parameters evaluated (sound pressure level, clarity index and lateral fraction), the changing diffusivity of the room does not diminish the importance of the directivity. The study therefore shows the importance of considering source directivity...... when using computer modeling. [Work supported by the National Science Foundation.]...

  3. Sketch of a Noisy Channel Model for the Translation Process

    DEFF Research Database (Denmark)

    Carl, Michael

    The paper develops a Noisy Channel Model for the translation process that is based on actual user activity data. It builds on the monitor model and makes a distinction between early, automatic and late, conscious translation processes: while early priming processes are at the basis of a "literal...... default rendering" procedure, later conscious processes are triggered by a monitor who interferes when something goes wrong. An attempt is made to explain monitor activities with relevance theoretic concepts according to which a translator needs to ensure the similarity of explicatures and implicatures of...

  4. A Noisy-Channel Model for Document Compression

    CERN Document Server

    Daumé, Hal

    2009-01-01

    We present a document compression system that uses a hierarchical noisy-channel model of text production. Our compression system first automatically derives the syntactic structure of each sentence and the overall discourse structure of the text given as input. The system then uses a statistical hierarchical model of text production in order to drop non-important syntactic and discourse constituents so as to generate coherent, grammatical document compressions of arbitrary length. The system outperforms both a baseline and a sentence-based compression system that operates by simplifying sequentially all sentences in a text. Our results support the claim that discourse knowledge plays an important role in document summarization.

  5. A Unified Channel Charges Expression for Analytic MOSFET Modeling

    Directory of Open Access Journals (Sweden)

    Hugues Murray

    2012-01-01

    Full Text Available Based on a 1D Poissons equation resolution, we present an analytic model of inversion charges allowing calculation of the drain current and transconductance in the Metal Oxide Semiconductor Field Effect Transistor. The drain current and transconductance are described by analytical functions including mobility corrections and short channel effects (CLM, DIBL. The comparison with the Pao-Sah integral shows excellent accuracy of the model in all inversion modes from strong to weak inversion in submicronics MOSFET. All calculations are encoded with a simple C program and give instantaneous results that provide an efficient tool for microelectronics users.

  6. Self-organized models of selectivity in calcium channels

    International Nuclear Information System (INIS)

    The role of flexibility in the selectivity of calcium channels is studied using a simple model with two parameters that accounts for the selectivity of calcium (and sodium) channels in many ionic solutions of different compositions and concentrations using two parameters with unchanging values. We compare the distribution of side chains (oxygens) and cations (Na+ and Ca2+) and integrated quantities. We compare the occupancies of cations Ca2+/Na+ and linearized conductance of Na+. The distributions show a strong dependence on the locations of fixed side chains and the flexibility of the side chains. Holding the side chains fixed at certain predetermined locations in the selectivity filter distorts the distribution of Ca2+ and Na+ in the selectivity filter. However, integrated quantities—occupancy and normalized conductance—are much less sensitive. Our results show that some flexibility of side chains is necessary to avoid obstruction of the ionic pathway by oxygen ions in 'unfortunate' fixed positions. When oxygen ions are mobile, they adjust 'automatically' and move 'out of the way', so they can accommodate the permeable cations in the selectivity filter. Structure is the computed consequence of the forces in this model. The structures are self-organized, at their free energy minimum. The relationship of ions and side chains varies with an ionic solution. Monte Carlo simulations are particularly well suited to compute induced-fit, self-organized structures because the simulations yield an ensemble of structures near their free energy minimum. The exact location and mobility of oxygen ions has little effect on the selectivity behavior of calcium channels. Seemingly, nature has chosen a robust mechanism to control selectivity in calcium channels: the first-order determinant of selectivity is the density of charge in the selectivity filter. The density is determined by filter volume along with the charge and excluded volume of

  7. Coupled-channel optical model potential for rare earth nuclei

    CERN Document Server

    Herman, M; Palumbo, A; Dietrich, F S; Brown, D; Hoblit, S

    2013-01-01

    Inspired by the recent work by Dietrich et al., substantiating validity of the adiabatic assumption in coupled-channel calculations, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on statically deformed nuclei. The generalization consists in adding the coupling of the ground state rotational band, deforming the potential by introducing appropriate quadrupole and hexadecupole deformation and correcting the OMP radius to preserve volume integral of the spherical OMP. We choose isotopes of three rare-earth elements (W, Ho, Gd), which are known to be nearly perfect rotors, to perform a consistent test of our conjecture on integrated cross sections as well as on angular distributions for elastic and inelastic neutron scattering. When doing this we employ the well-established Koning-Delaroche global spherical potential and experimentally determined deformations without any adjustments. We observe a dramatically improved a...

  8. S-Channel Dark Matter Simplified Models and Unitarity

    CERN Document Server

    Englert, Christoph; Spannowsky, Michael

    2016-01-01

    The ultraviolet structure of $s$-channel mediator dark matter simplified models at hadron colliders is considered. In terms of commonly studied $s$-channel mediator simplified models it is argued that at arbitrarily high energies the perturbative description of dark matter production in high energy scattering at hadron colliders will break down in a number of cases. This is analogous to the well documented breakdown of an EFT description of dark matter collider production. With this in mind, to diagnose whether or not the use of simplified models at the LHC is valid, perturbative unitarity of the scattering amplitude in the processes relevant to LHC dark matter searches is studied. The results are as one would expect: at the LHC and future proton colliders the simplified model descriptions of dark matter production are in general valid. As a result of the general discussion, a simple new class of previously unconsidered `Fermiophobic Scalar' simplified models is proposed, in which a scalar mediator couples to...

  9. A General Model for Analysis of Sound Radiation from Orthogonally Stiffened Laminated Composite Plates

    Institute of Scientific and Technical Information of China (English)

    金叶青; 庞福振; 杨飞; 李光明

    2014-01-01

    A-general-theoretical-model-is-developed-to-investigate-the-sound-radiation-from-an-infinite-orthogonally-stiffened-plate-under-point-excitation-force.-The-plate-can-be-metallic-or-composite,-and-fluid-loading-is-also-considered-in-the-research.-The-first-order-shear-deformation-theory-is-used-to-account-for-the-transverse-shear-deformation.-The-motion-of-the-equally-spaced-stiffeners-is-examined-by-considering-their-bending-vibrations-and-torsional-movements.-Based-on-the-periodic-structure-theory-and-the-concepts-of-the-equivalent-dynamic-flexibility-of-the-plate,-the-generalized-vibro-acoustic-equation-of-the-model-is-obtained-by-applying-the-Fourier-transform-method.-The-generalized-model-that-can-be-solved-numerically-is-validated-by-comparing-model-predictions-with-the-existing-results.-Numerical-calculations-are-performed-to-investigate-the-effects-of-the-location-of-the-excitation,-the-spacing-of-the-stiffeners,-the-plate-thickness,-the-strengthening-form-and-the-fiber-orientation-on-the-sound-radiation-characteristic-of-the-orthogonally-stiffened-plate,-and-some-practical-conclusions-are-drawn-from-these-parameter-studies.

  10. A general model for analysis of sound radiation from orthogonally stiffened laminated composite plates

    Science.gov (United States)

    Jin, Ye-qing; Pang, Fu-zhen; Yang, Fei; Li, Guang-ming

    2014-08-01

    A general theoretical model is developed to investigate the sound radiation from an infinite orthogonally stiffened plate under point excitation force. The plate can be metallic or composite, and fluid loading is also considered in the research. The first order shear deformation theory is used to account for the transverse shear deformation. The motion of the equally spaced stiffeners is examined by considering their bending vibrations and torsional movements. Based on the periodic structure theory and the concepts of the equivalent dynamic flexibility of the plate, the generalized vibro-acoustic equation of the model is obtained by applying the Fourier transform method. The generalized model that can be solved numerically is validated by comparing model predictions with the existing results. Numerical calculations are performed to investigate the effects of the location of the excitation, the spacing of the stiffeners, the plate thickness, the strengthening form and the fiber orientation on the sound radiation characteristic of the orthogonally stiffened plate, and some practical conclusions are drawn from these parameter studies.

  11. CAVITATION INCEPTION WITNESSED BY SOUND PRESSURE LEVEL IN MODEL TEST AND PROTOTYPE OBSERVATION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dong; LIU Zhi-ping; JIN Tai-lai; XIANG Ya-ping

    2004-01-01

    The paper concerns with the relationship between cavitation inception and Sound Pressure Level (SPL).A case study for the Xiaolangdi Hydro-project was taken as a typical example, which demonstrated the standard criterion of SPL indicating cavitation inception. Cavitation inception of an orifice plate used for energy dissipation in a tunnel spillway was witnessed and verified both in model test and prototype observation. A design criterion was proposed for a cavitationfree hydraulic structure which can be served as a reference for designers as well as researchers. Consequently, scale effects were discussed with an aim at suggesting an appropriate factor of safety in design.

  12. A review of radio channel models for body centric communications

    Science.gov (United States)

    Cotton, Simon L.; D'Errico, Raffaele; Oestges, Claude

    2014-06-01

    The human body is an extremely challenging environment for the operation of wireless communications systems, not least because of the complex antenna-body electromagnetic interaction effects which can occur. This is further compounded by the impact of movement and the propagation characteristics of the local environment which all have an effect upon body centric communications channels. As the successful design of body area networks (BANs) and other types of body centric system is inextricably linked to a thorough understanding of these factors, the aim of this paper is to conduct a survey of the current state of the art in relation to propagation and channel models primarily for BANs but also considering other types of body centric communications. We initially discuss some of the standardization efforts performed by the Institute of Electrical and Electronics Engineers 802.15.6 task group before focusing on the two most popular types of technologies currently being considered for BANs, namely narrowband and Ultrawideband (UWB) communications. For narrowband communications the applicability of a generic path loss model is contended, before presenting some of the scenario specific models which have proven successful. The impacts of human body shadowing and small-scale fading are also presented alongside some of the most recent research into the Doppler and time dependencies of BANs. For UWB BAN communications, we again consider the path loss as well as empirical tap delay line models developed from a number of extensive channel measurement campaigns conducted by research institutions around the world. Ongoing efforts within collaborative projects such as Committee on Science and Technology Action IC1004 are also described. Finally, recent years have also seen significant developments in other areas of body centric communications such as off-body and body-to-body communications. We highlight some of the newest relevant research in these areas as well as discussing

  13. Model-based synthesis of aircraft noise to quantify human perception of sound quality and annoyance

    Science.gov (United States)

    Berckmans, D.; Janssens, K.; Van der Auweraer, H.; Sas, P.; Desmet, W.

    2008-04-01

    This paper presents a method to synthesize aircraft noise as perceived on the ground. The developed method gives designers the opportunity to make a quick and economic evaluation concerning sound quality of different design alternatives or improvements on existing aircraft. By presenting several synthesized sounds to a jury, it is possible to evaluate the quality of different aircraft sounds and to construct a sound that can serve as a target for future aircraft designs. The combination of using a sound synthesis method that can perform changes to a recorded aircraft sound together with executing jury tests allows to quantify the human perception of aircraft noise.

  14. Modeling negative ion defect migration through the gramicidin A channel.

    Science.gov (United States)

    Nemukhin, Alexander V; Kaliman, Ilya A; Moskovsky, Alexander A

    2009-08-01

    The results of potential of mean force (PMF) calculations for the distinct stages of proton conduction through the gramicidin A channel, including proton migration, reorientation of the water file and negative ion defect migration, are presented. The negative ion defect migration mechanism was hypothesized in experimental studies but was not considered previously in molecular dynamics simulations. The model system consisted of the peptide chains constructed on the base of the structure PDBID:1JNO, the inner file of nine water molecules and external clusters of water molecules placed at both ends of the channel. Potential energy functions were computed with the CHARMM/PM6/TIP3P parameters. The results obtained for proton migration and water file reorientation are basically consistent with those reported previously by Pómès and Roux (Biophys J 82:2304, 2002) within the similar approach. For the newly considered mechanism of negative ion defect migration from the channel center to the end of the water file we obtain the energy 3.8 kcal mol(-1) which is not considerably different from the activation energy of water reorientation, 5.4 kcal mol(-1). Therefore this mechanism may principally compete for the rate-limiting step in proton conduction in gramicidin. PMID:19198898

  15. Modelling of flow and heat transfer in PV cooling channels

    Energy Technology Data Exchange (ETDEWEB)

    Diarra, D.C.; Harrison, S.J. [Queen' s Univ., Kingston, ON (Canada). Dept. of Mechanical and Materials Engineering Solar Calorimetry Lab; Akuffo, F.O. [Kwame Nkrumah Univ. of Science and Technology, Kumasi (Ghana). Dept. of Mechanical Engineering

    2005-07-01

    Under sunny conditions, the temperature of photovoltaic (PV) modules can be 20 to 30 degrees C above the ambient air temperature. This affects the performance of PV modules, particularly in regions with hot climates. For silicon solar cells, the maximum power decreases between 0.4 and 0.5 per cent for every degree C of temperature increase above a reference value. In an effort to address this issue, this experimental and numerical study examined an active PV panel evaporative cooling scheme that is typically used in hot arid climates. The cooling system circulated cool air behind the PV modules, extracting heat and lowering solar cell temperature. A fluid dynamic and thermal model of the combined system was developed using the EES program in order to study the configuration of the cooling channel and the characteristics of the cooling flow. Heat transfer and flow characteristics in the cooling channel were then calculated along with pressure drop and fan power associated with the air-circulation. The net power output was also calculated. The objective was to design a cost efficient cooling system and to optimize its flow and pressure drop in order to maximize power output. The study demonstrated how the performance of the PV panel is influenced by the geometry of the cooling channel, the inlet air temperature and the air flow rate. 2 refs.

  16. Influence of Wall Surface and Air Modelling in Finite-Element Analysis of Sound Transmission Between Rooms in Lightweight Buildings

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Kirkegaard, Poul Henning; Dickow, Kristoffer Ahrens;

    2012-01-01

    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......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...

  17. 2D numerical modelling of meandering channel formation

    Indian Academy of Sciences (India)

    Y Xiao; G Zhou; F S Yang

    2016-03-01

    A 2D depth-averaged model for hydrodynamic sediment transport and river morphological adjustment was established. The sediment transport submodel takes into account the influence of non-uniform sediment with bed surface armoring and considers the impact of secondary flow in the direction of bed-loadtransport and transverse slope of the river bed. The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution. Comparison of the results obtained by the extended model with experimental and field data, and numericalpredictions validate that the proposed model can simulate grain sorting in river bends and duplicate the characteristics of meandering river and its development. The results illustrate that by using its control factors, the improved numerical model can be applied to simulate channel evolution under differentscenarios and improve understanding of patterning processes.

  18. River channel's predisposition to ice jams: a geospatial model

    Science.gov (United States)

    De Munck, S.; Gauthier, Y.; Bernier, M.; Légaré, S.

    2012-04-01

    When dynamic breakup occurs on rivers, ice moving downstream may eventually stop at an obstacle when the volume of moving ice exceeds the transport capacity of the river, resulting into an ice jam. The suddenness and unpredictability of these ice jams are a constant danger to local population. Therefore forecasting methods are necessary to provide an early warning to these population. Nonetheless the morphological and hydrological factors controlling where and how the ice will jam are numerous and complex. Existing studies which exist on this topic are highly site specific. Therefore, the goal of this work is to develop a simplified geospatial model that would estimate the predisposition of any river channel to ice jams. The question here is not to predict when the ice will break up but rather to know where the released ice would be susceptible to jam. This paper presents the developments and preliminary results of the proposed approach. The initial step was to document the main factors identified in the literature, as potential cause for an ice jam. First, several main factors identified in the literature as potential cause for an ice jam have been selected: presence of an island, narrowing of the channel, sinuosity, presence of a bridge, confluence of rivers and slope break. The second step was to spatially represent, in 2D, the physical characteristics of the channel and to translate these characteristics into potential ice jamming factors. The Chaudiere River, south of Quebec City (Canada), was chosen as a test site. Tools from the GIS-based FRAZIL system have been used to generate these factors from readily available geospatial data and calcutate an "ice jam predisposition index" over regular-spaced segments along the entire channel. The resulting map was validated upon historical observations and local knowledge, collected in relationship with the Minister of Public Security.

  19. A generalized linear model for estimating spectrotemporal receptive fields from responses to natural sounds.

    Directory of Open Access Journals (Sweden)

    Ana Calabrese

    Full Text Available In the auditory system, the stimulus-response properties of single neurons are often described in terms of the spectrotemporal receptive field (STRF, a linear kernel relating the spectrogram of the sound stimulus to the instantaneous firing rate of the neuron. Several algorithms have been used to estimate STRFs from responses to natural stimuli; these algorithms differ in their functional models, cost functions, and regularization methods. Here, we characterize the stimulus-response function of auditory neurons using a generalized linear model (GLM. In this model, each cell's input is described by: 1 a stimulus filter (STRF; and 2 a post-spike filter, which captures dependencies on the neuron's spiking history. The output of the model is given by a series of spike trains rather than instantaneous firing rate, allowing the prediction of spike train responses to novel stimuli. We fit the model by maximum penalized likelihood to the spiking activity of zebra finch auditory midbrain neurons in response to conspecific vocalizations (songs and modulation limited (ml noise. We compare this model to normalized reverse correlation (NRC, the traditional method for STRF estimation, in terms of predictive power and the basic tuning properties of the estimated STRFs. We find that a GLM with a sparse prior predicts novel responses to both stimulus classes significantly better than NRC. Importantly, we find that STRFs from the two models derived from the same responses can differ substantially and that GLM STRFs are more consistent between stimulus classes than NRC STRFs. These results suggest that a GLM with a sparse prior provides a more accurate characterization of spectrotemporal tuning than does the NRC method when responses to complex sounds are studied in these neurons.

  20. Optical wireless communications system and channel modelling with Matlab

    CERN Document Server

    Ghassemlooy, Z

    2012-01-01

    Detailing a systems approach, Optical Wireless Communications: System and Channel Modelling with MATLAB(R), is a self-contained volume that concisely and comprehensively covers the theory and technology of optical wireless communications systems (OWC) in a way that is suitable for undergraduate and graduate-level students, as well as researchers and professional engineers. Incorporating MATLAB(R) throughout, the authors highlight past and current research activities to illustrate optical sources, transmitters, detectors, receivers, and other devices used in optical wireless communications. The

  1. Modeling and measuring sound propagation of hooded crow calls in open field habitats

    DEFF Research Database (Denmark)

    Jensen, Kenneth Kragh; Larsen, Ole Næsbye; Attenborough, Keith

    , an optimal frequency range between approximately 500 Hz and 2 kHz. The hearing system of crows enables the most sensitive detection of signals in noise within this range. From modeling, noise measurements, and hearing data we estimate hooded crow active space to be roughly 1 km, but with great variance...... In a study of territorial communication distance of hooded crows we find an excellent correspondence between model predicted crow call transmission and re-recorded crow calls. Modeling average transmission characteristics within a spatial matrix of sender/receiver distances and heights....... Discussing a number of other factors in hooded crow communication we conclude that they are highly adapted to communication over the distances and terrain of interest. We suggest that turbulence does not attenuate sound signals appreciably as previously assumed. Finally, we advise against using only...

  2. Physics based modelling of short-channel nanowire MOSFET

    Energy Technology Data Exchange (ETDEWEB)

    Boerli, H; Kolberg, S; Fjeldly, T A [Department of Electronics and Telecommunication, Norwegian University of Science and Technology, and UniK, University Graduate Center, N-2021 Kjeller (Norway)], E-mail: hborli@unik.no, E-mail: kolberg@unik.no, E-mail: torfj@unik.no

    2008-03-15

    A modelling framework for short channel nanowire (NW) MOSFETs that covers a wide range of operating conditions is presented. The device electrostatics in the subthreshold regime is dominated by the inter-electrode capacitive coupling, which, in the case of double gate (DG) devices, is analyzed in terms of conformal mapping techniques. Previously, we have shown that these results can also be successfully applied to the NW MOSFET, by performing an appropriate mapping to compensate for the difference in gate control between the two devices. Near and above threshold, the influence of the electronic charge is taken into account in a precise, self-consistent manner by combining suitable model expressions with Poisson's equation. The models are verified by comparison with numerical device simulations.

  3. Processing Complex Sounds Passing through the Rostral Brainstem: The New Early Filter Model

    Science.gov (United States)

    Marsh, John E.; Campbell, Tom A.

    2016-01-01

    The rostral brainstem receives both “bottom-up” input from the ascending auditory system and “top-down” descending corticofugal connections. Speech information passing through the inferior colliculus of elderly listeners reflects the periodicity envelope of a speech syllable. This information arguably also reflects a composite of temporal-fine-structure (TFS) information from the higher frequency vowel harmonics of that repeated syllable. The amplitude of those higher frequency harmonics, bearing even higher frequency TFS information, correlates positively with the word recognition ability of elderly listeners under reverberatory conditions. Also relevant is that working memory capacity (WMC), which is subject to age-related decline, constrains the processing of sounds at the level of the brainstem. Turning to the effects of a visually presented sensory or memory load on auditory processes, there is a load-dependent reduction of that processing, as manifest in the auditory brainstem responses (ABR) evoked by to-be-ignored clicks. Wave V decreases in amplitude with increases in the visually presented memory load. A visually presented sensory load also produces a load-dependent reduction of a slightly different sort: The sensory load of visually presented information limits the disruptive effects of background sound upon working memory performance. A new early filter model is thus advanced whereby systems within the frontal lobe (affected by sensory or memory load) cholinergically influence top-down corticofugal connections. Those corticofugal connections constrain the processing of complex sounds such as speech at the level of the brainstem. Selective attention thereby limits the distracting effects of background sound entering the higher auditory system via the inferior colliculus. Processing TFS in the brainstem relates to perception of speech under adverse conditions. Attentional selectivity is crucial when the signal heard is degraded or masked: e

  4. Processing Complex Sounds Passing through the Rostral Brainstem: The New Early Filter Model.

    Science.gov (United States)

    Marsh, John E; Campbell, Tom A

    2016-01-01

    The rostral brainstem receives both "bottom-up" input from the ascending auditory system and "top-down" descending corticofugal connections. Speech information passing through the inferior colliculus of elderly listeners reflects the periodicity envelope of a speech syllable. This information arguably also reflects a composite of temporal-fine-structure (TFS) information from the higher frequency vowel harmonics of that repeated syllable. The amplitude of those higher frequency harmonics, bearing even higher frequency TFS information, correlates positively with the word recognition ability of elderly listeners under reverberatory conditions. Also relevant is that working memory capacity (WMC), which is subject to age-related decline, constrains the processing of sounds at the level of the brainstem. Turning to the effects of a visually presented sensory or memory load on auditory processes, there is a load-dependent reduction of that processing, as manifest in the auditory brainstem responses (ABR) evoked by to-be-ignored clicks. Wave V decreases in amplitude with increases in the visually presented memory load. A visually presented sensory load also produces a load-dependent reduction of a slightly different sort: The sensory load of visually presented information limits the disruptive effects of background sound upon working memory performance. A new early filter model is thus advanced whereby systems within the frontal lobe (affected by sensory or memory load) cholinergically influence top-down corticofugal connections. Those corticofugal connections constrain the processing of complex sounds such as speech at the level of the brainstem. Selective attention thereby limits the distracting effects of background sound entering the higher auditory system via the inferior colliculus. Processing TFS in the brainstem relates to perception of speech under adverse conditions. Attentional selectivity is crucial when the signal heard is degraded or masked: e.g., speech in

  5. SAR Observation and Modeling of Gap Winds in the Prince William Sound of Alaska

    Directory of Open Access Journals (Sweden)

    Karl Volz

    2008-08-01

    Full Text Available Alaska’s Prince William Sound (PWS is a unique locale tending to have strong gap winds, especially in the winter season. To characterize and understand these strong surface winds, which have great impacts on the local marine and aviation activities, the surface wind retrieval from the Synthetic Aperture Radar data (SAR-wind is combined with a numerical mesoscale model. Helped with the SAR-wind observations, the mesoscale model is used to study cases of strong winds and relatively weak winds to depict the nature of these winds, including the area of extent and possible causes of the wind regimes. The gap winds from the Wells Passage and the Valdez Arm are the most dominant gap winds in PWS. Though the Valdez Arm is north-south trending and Wells Passage is east-west oriented, gap winds often develop simultaneously in these two places when a low pressure system is present in the Northern Gulf of Alaska. These two gap winds often converge at the center of PWS and extend further out of the Sound through the Hinchinbrook Entrance. The pressure gradients imposed over these areas are the main driving forces for these gap winds. Additionally, the drainage from the upper stream glaciers and the blocking effect of the banks of the Valdez Arm probably play an important role in enhancing the gap wind.

  6. A model for calculating specular and diffuse reflections in outdoor sound propagation

    NARCIS (Netherlands)

    Salomons, E.M.

    2006-01-01

    In many practical outdoor situations, the direct sound path between a noise source and a receiver is screened by an obstacle. In these situations indirect sound paths become important, in particular reflections of sound waves. Reflections may occur at objects such as a vertical wall, but also at the

  7. Assessment of long-term channel changes in the Mekong River using remote sensing and a channel-evolution model

    Science.gov (United States)

    Miyazawa, N.

    2011-12-01

    River-channel changes are a key factor affecting physical, ecological and management issues in the fluvial environment. In this study, long-term channel changes in the Mekong River were assessed using remote sensing and a channel-evolution model. A channel-evolution model for calculating long-term channel changes of a measndering river was developed using a previous fluid-dynamic model [Zolezzi and Seminara, 2001], and was applied in order to quantify channel changes of two meandering reaches in the Mekong River. Quite few attempts have been made so far to combine remote sensing observation of meandering planform change with the application of channel evolution models within relatively small-scale gravel-bed systems in humid temperate regions. The novel point of the present work is to link state-of-art meandering planform evolution model with observed morphological changes within large-scale sand-bed rivers with higher bank height in tropical monsoonal climate regions, which are the highly dynamic system, and assess the performance. Unstable extents of the reaches could be historically identified using remote-sensing technique. The instability caused i) bank erosion and accretion of meander bends and ii) movement or development of bars and changes in the flow around the bars. The remote sensing measurements indicate that maximum erosion occurred downstream of the maximum curvature of the river-center line in both reaches. The model simulations indicates that under the mean annual peak discharge the maximum of excess longitudinal velocity near the banks occurs downstream of the maximum curvature in both reaches. The channel migration coefficients of the reaches were calibrated by comparing remote-sensing measurements and model simulations. The diffrence in the migration coefficients between both reaches depends on the diffrence in bank height rather than the geotechnical properties of floodplain sediments. Possible eroded floodplain areas and accreted floodplain

  8. Over-sampling basis expansion model aided channel estimation for OFDM systems with ICI

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The rapid variation of channel can induce the intercarrier interference in orthogonal frequency-division multiplexing (OFDM) systems. Intercarrier interference will significantly increase the difficulty of OFDM channel estimation because too many channel coefficients need be estimated. In this article, a novel channel estimator is proposed to resolve the above problem. This estimator consists of two parts: the channel parameter estimation unit (CPEU), which is used to estimate the number of channel taps and the multipath time delays, and the channel coefficient estimation unit (CCEU), which is used to estimate the channel coefficients by using the estimated channel parameters provided by CPEU. In CCEU, the over-sampling basis expansion model is resorted to solve the problem that a large number of channel coefficients need to be estimated. Finally, simulation results are given to scale the performance of the proposed scheme.

  9. Sound shell model for acoustic gravitational wave production at a first-order phase transition in the early Universe

    CERN Document Server

    Hindmarsh, Mark

    2016-01-01

    A model for the acoustic production of gravitational waves at a first order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that the sound waves are linear and that their power spectrum is determined by the characteristic form of the sound shell around the expanding bubble. The predicted power spectrum has two length scales, the average bubble separation and the sound shell width when the bubbles collide. The peak of the power spectrum is at wavenumbers set by the sound shell width. For higher wavenumber $k$, the power spectrum decreases as $k^{-3}$. At wavenumbers below the inverse bubble separation, the power spectrum goes as $k^5$. For bubble wall speeds near the speed of sound where these two length scales are distinguished, there is an intermediate $k^{1}$ power law. The detailed dependence of the power spectrum on the wall speed and the other parameters of the phase transition rais...

  10. Channel selection in e-commerce age: a strategic analysis of co-op advertising models

    OpenAIRE

    Yongmei Liu; Yuhua Sun; Junhua Hu

    2013-01-01

    Purpose: The purpose of this paper is to develop and compare two co-op advertising models: advertising model under traditional channel and co-op advertising model under dual channel, to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer.Design/methodology/approach: Stackelberg game theoretical is used to develop two co-op advertising models: co-op advertising model under traditional channe...

  11. Modeling of optical wireless scattering communication channels over broad spectra.

    Science.gov (United States)

    Liu, Weihao; Zou, Difan; Xu, Zhengyuan

    2015-03-01

    The air molecules and suspended aerosols help to build non-line-of-sight (NLOS) optical scattering communication links using carriers from near infrared to visible light and ultraviolet bands. This paper proposes channel models over such broad spectra. Wavelength dependent Rayleigh and Mie scattering and absorption coefficients of particles are analytically obtained first. They are applied to the ray tracing based Monte Carlo method, which models the photon scattering angle from the scatterer and propagation distance between two consecutive scatterers. Communication link path loss is studied under different operation conditions, including visibility, particle density, wavelength, and communication range. It is observed that optimum communication performances exist across the wavelength under specific atmospheric conditions. Infrared, visible light and ultraviolet bands show their respective features as conditions vary. PMID:26366662

  12. Channel Measurement and Modeling for 5G Urban Microcellular Scenarios

    Directory of Open Access Journals (Sweden)

    Michael Peter

    2016-08-01

    Full Text Available In order to support the development of channel models for higher frequency bands, multiple urban microcellular measurement campaigns have been carried out in Berlin, Germany, at 60 and 10 GHz. In this paper, the collected data is uniformly analyzed with focus on the path loss (PL and the delay spread (DS. It reveals that the ground reflection has a dominant impact on the fading behavior. For line-of-sight conditions, the PL exponents are close to free space propagation at 60 GHz, but slightly smaller (1.62 for the street canyon at 10 GHz. The DS shows a clear dependence on the scenario (median values between 16 and 38 ns and a strong distance dependence for the open square and the wide street canyon. The dependence is less distinct for the narrow street canyon with residential buildings. This behavior is consistent with complementary ray tracing simulations, though the simplified model tends to overestimate the DS.

  13. Fermionic Dark Matter in a simple $t$-channel model

    CERN Document Server

    Goyal, Ashok

    2016-01-01

    We consider a fermionic dark matter (DM) particle in renormalizable Standard Model (SM) gauge interactions in a simple $t$-channel model. The DM particle interactions with SM fermions is through the exchange of scalar and vector mediators which carry colour or lepton number. In the case of coloured mediators considered in this study, we find that if the DM is thermally produced and accounts for the observed relic density almost the entire parameter space is ruled out by the direct detection observations. The bounds from the monojet plus missing energy searches at the Large Hadron Collider are less stringent in this case. In contrast for the case of Majorana DM, we obtain strong bounds from the monojet searches which rule out DM particles of mass less than about a few hundred GeV for both the scalar and vector mediators.

  14. Channel Measurement and Modeling for 5G Urban Microcellular Scenarios.

    Science.gov (United States)

    Peter, Michael; Weiler, Richard J; Göktepe, Barış; Keusgen, Wilhelm; Sakaguchi, Kei

    2016-01-01

    In order to support the development of channel models for higher frequency bands, multiple urban microcellular measurement campaigns have been carried out in Berlin, Germany, at 60 and 10 GHz. In this paper, the collected data is uniformly analyzed with focus on the path loss (PL) and the delay spread (DS). It reveals that the ground reflection has a dominant impact on the fading behavior. For line-of-sight conditions, the PL exponents are close to free space propagation at 60 GHz, but slightly smaller (1.62) for the street canyon at 10 GHz. The DS shows a clear dependence on the scenario (median values between 16 and 38 ns) and a strong distance dependence for the open square and the wide street canyon. The dependence is less distinct for the narrow street canyon with residential buildings. This behavior is consistent with complementary ray tracing simulations, though the simplified model tends to overestimate the DS. PMID:27556462

  15. Investigation of the ocean acoustic signatures from strong explosions at a long distance in the ocean sound channel by computer simulation

    International Nuclear Information System (INIS)

    The identification and location of ocean acoustic signatures are the principal objectives of a program to discourage clandestine testing of nuclear explosives. Difficulties arise primarily from variations in the water column. In turn, these variations affect acoustic propagation in the SOFAR channel. In this study, the path effects on the signals generated by strong explosions (1 and 10 kn) are investigated. The goal is to make a quantitative correlation between the initial source description and the final acoustical signatures received at a great distance under various conditions. The study is performed entirely by computer simulations applying two computer programs in succession. First, the explosions are simulated by a 2-D hydrodynamic computer program, CALE, which was originally developed to calculate astrophysical problems. The computed signals have reached more than 700 m deep approaching the SOFAR channel. At this point, the CALE output is linked to a hydro-acoustic computer program, the NPE code, by which wave propagation in the SOFAR channel is modeled. The NPE code was developed at the Naval Research Laboratory to study ocean acoustics. [Work supported by the U. S. Department of Energy under Contract No. W-7405-ENG-48.

  16. MoCha, a model for distributed mobile channels

    OpenAIRE

    Guillen Scholten, Juan

    2004-01-01

    A mobile channel is a link that provides an asynchronous and anonymous means of communication between components in a distributed system. A channel is called mobile if either of its (channel-)ends can be moved from one component to another without the knowledge of the component at its other end. Such mobility allows dynamic reconfiguration of channel connections among the components in a system, a property that is very useful and even crucial in systems where the components themselves are mob...

  17. Modelling customer behaviour in multi-channel service distribution

    NARCIS (Netherlands)

    D. Heinhuis; E.J. de Vries

    2008-01-01

    Financial service providers are innovating their distribution strategy into multi-channel strategies. The success of a multi-channel approach and the high investments made in information systems and enterprise architectures depends on the adoption and multi-channel usage behaviour of consumers. We b

  18. Analytical models of calcium binding in a calcium channel

    International Nuclear Information System (INIS)

    The anomalous mole fraction effect of L-type calcium channels is analyzed using a Fermi like distribution with the experimental data of Almers and McCleskey [J. Physiol. 353, 585 (1984)] and the atomic resolution model of Lipkind and Fozzard [Biochemistry 40, 6786 (2001)] of the selectivity filter of the channel. Much of the analysis is algebraic, independent of differential equations. The Fermi distribution is derived from the configuration entropy of ions and water molecules with different sizes, different valences, and interstitial voids between particles. It allows us to calculate potentials and distances (between the binding ion and the oxygen ions of the glutamate side chains) directly from the experimental data using algebraic formulas. The spatial resolution of these results is comparable with those of molecular models, but of course the accuracy is no better than that implied by the experimental data. The glutamate side chains in our model are flexible enough to accommodate different types of binding ions in different bath conditions. The binding curves of Na+ and Ca2+ for [CaCl2] ranging from 10−8 to 10−2 M with a fixed 32 mM background [NaCl] are shown to agree with published Monte Carlo simulations. The Poisson-Fermi differential equation—that includes both steric and correlation effects—is then used to obtain the spatial profiles of energy, concentration, and dielectric coefficient from the solvent region to the filter. The energy profiles of ions are shown to depend sensitively on the steric energy that is not taken into account in the classical rate theory. We improve the rate theory by introducing a steric energy that lumps the effects of excluded volumes of all ions and water molecules and empty spaces between particles created by Lennard-Jones type and electrostatic forces. We show that the energy landscape varies significantly with bath concentrations. The energy landscape is not constant

  19. Sound propagation in forests: A comparison of experimental results and values predicted by the Nord 2000 model

    DEFF Research Database (Denmark)

    Tarrero, A.I.; Martín, M.A.; González, J.;

    2008-01-01

    to predict scattering effects when sound propagates in outdoor spaces with obstacles. The comparison of experimental results and predictions shows that the Nord 2000 model predicts the ground effect dip in forests with acceptable accuracy in about 60% of the cases if the flow resistivity of the ground......The purpose of the work described in this paper is twofold: (i) to present the results of an experimental investigation of the sound attenuation in different types of forest, and (ii) to validate a part of the Nord 2000 model. A number of measurements have been carried out in regular and irregular...... forests with trees with deciduous and evergreen leaves, different tree density, different trunk diameter, etc. The experimental results indicate that trees have a noticeable effect on sound propagation at medium and high frequencies at distances longer than 40m. The Nord 2000 model uses a simple algorithm...

  20. A Model for the Sounding Rocket Measurement on an Ionospheric E-F Valley at the Hainan Low Latitude Station

    International Nuclear Information System (INIS)

    To understand the physics of an ionospheric E-F valley, a new overlapping three-Chapman-layer model is developed to interpret the sounding rocket measurement in the morning (sunrise) on May 7, 2011 at the Hainan low latitude ionospheric observation station (19.5°N, 109.1°E). From our model, the valley width, depth and height are 43.0 km, 62.9% and 121.0 km, respectively. From the sounding rocket observation, the valley width, depth and height are 42.2 km, 47.0% and 123.5 km, respectively. The model results are well consistent with the sounding rocket observation. The observed E-F valley at Hainan station is very wide and deep, and rapid development of the photochemical process in the ionosphere should be the underlying reason. (astrophysics and space plasma)

  1. A Model for the Sounding Rocket Measurement on an Ionospheric E-F Valley at the Hainan Low Latitude Station

    Science.gov (United States)

    Wang, Zheng; Shi, Jiankui; Guan, Yibing; Liu, Chao; Zhu, Guangwu; Klaus, Torkar; Martin, Fredrich

    2014-04-01

    To understand the physics of an ionospheric E-F valley, a new overlapping three-Chapman-layer model is developed to interpret the sounding rocket measurement in the morning (sunrise) on May 7, 2011 at the Hainan low latitude ionospheric observation station (19.5°N, 109.1°E). From our model, the valley width, depth and height are 43.0 km, 62.9% and 121.0 km, respectively. From the sounding rocket observation, the valley width, depth and height are 42.2 km, 47.0% and 123.5 km, respectively. The model results are well consistent with the sounding rocket observation. The observed E-F valley at Hainan station is very wide and deep, and rapid development of the photochemical process in the ionosphere should be the underlying reason.

  2. The Constant-Sound-Speed parameterization for NJL models of quark matter in hybrid stars

    CERN Document Server

    Ranea-Sandoval, Ignacio F; Orsaria, Milva G; Contrera, Gustavo A; Weber, Fridolin; Alford, Mark G

    2016-01-01

    The discovery of pulsars as heavy as 2 solar masses has led astrophysicists to rethink the core compositions of neutron stars, ruling out many models for the nuclear equations of state (EoS). We explore the hybrid stars that occur when hadronic matter is treated in a relativistic mean-field approximation and quark matter is modeled by three-flavor local and non-local Nambu Jona-Lasinio (NJL) models with repulsive vector interactions. The NJL models typically yield equations of state that feature a first order transition to quark matter. Assuming that the quark-hadron surface tension is high enough to disfavour mixed phases, and restricting to EoSes that allow stars to reach 2 solar masses, we find that the appearance of the quark matter core either destabilizes the star immediately (this is typical for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (this is typical for local NJL models). Using the Constant-Sound-Speed parametrization we can see that the reason fo...

  3. EFFECT OF MULTIPATH CHANNEL MODELS TO THE RECOVERY ALGORITHMS ON COMPRESSED SENSING IN UWB CHANNEL ESTIMATION

    Institute of Scientific and Technical Information of China (English)

    Nguyen ThanhSon; Guo Shuxu; Chen Haipeng

    2013-01-01

    Multipath arrivals in an Ultra-WideBand (UWB) channel have a long time intervals between clusters and rays where the signal takes on zero or negligible values.It is precisely the signal sparsity of the impulse response of the UWB channel that is exploited in this work aiming at UWB channel estimation based on Compressed Sensing (CS).However,these multipath arrivals mainly depend on the channel environments that generate different sparse levels (low-sparse or high-sparse) of the UWB channels.According to this basis,we have analyzed the two most basic recovery algorithms,one based on linear programming Basis Pursuit (BP),another using greedy method Orthogonal Matching Pursuit (OMP),and chosen the best recovery algorithm which are suitable to the sparse level for each type of channel environment.Besides,the results of this work is an open topic for further research aimed at creating a optimal algorithm specially for application of CS based UWB systems.

  4. Discrete channel modelling based on genetic algorithm and simulated annealing for training hidden Markov model

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhi-Jin; Zheng Shi-Lian; Xu Chun-Yun; Kong Xian-Zheng

    2007-01-01

    Hidden Markov models (HMMs) have been used to model burst error sources of wireless channels. This paper proposes a hybrid method of using genetic algorithm (GA) and simulated annealing (SA) to train HMM for discrete channel modelling. The proposed method is compared with pure GA, and experimental results show that the HMMs trained by the hybrid method can better describe the error sequences due to SA's ability of facilitating hill-climbing at the later stage of the search. The burst error statistics of the HMMs trained by the proposed method and the corresponding error sequences are also presented to validate the proposed method.

  5. Psychoacoustic Evaluation Model on the Luxury of Sound Quality in Vehicle Interior Noise

    Directory of Open Access Journals (Sweden)

    Fang Li

    2013-05-01

    Full Text Available This paper studied the comprehensive evaluation index of sensory luxury of Sound Quality in Vehicle interior noise. The relationship between it and psychoacoustic parameters under different conditions was studied. Four types of vehicle real-time noises were recorded at several running speeds and later were subjectively evaluated in the testing room by semantic subdivided method. According to the subjective test and evaluation, the psychoacoustic objective quantificational model was built using correlation analysis and multi-dimensional linear regression analysis. The results indicated that: the luxury of vehicle interior noise showed good correlation with loudness and sharpness. The luxury increased as loudness or sharpness decreased, but it decreased as speed increased.

  6. Modeling potentiometric measurements in topological insulators including parallel channels

    Science.gov (United States)

    Hong, Seokmin; Diep, Vinh; Datta, Supriyo; Chen, Yong P.

    2012-08-01

    The discovery of spin-polarized states at the surface of three-dimensional topological insulators (TI) like Bi2Te3 and Bi2Se3 motivates intense interests in possible electrical measurements demonstrating unique signatures of these unusual states. Here we show that a three-terminal potentiometric set-up can be used to probe them by measuring the voltage change of a detecting magnet upon reversing its magnetization. We present numerical results using a nonequilibrium Green's function (NEGF)-based model to show the corresponding signal quantitatively in various transport regimes. We then provide an analytical expression for the resistance (the measured voltage difference divided by an applied current) that agrees with NEGF results well in both ballistic and diffusive limits. This expression is applicable to TI surface states, two-dimensional electrons with Rashba spin-split bands, and any combination of multiple channels, including bulk parallel states in TI, which makes it useful in analyzing experimental results.

  7. Speeds of sound and isothermal compressibility of ternary liquid systems: Application of Flory's statistical theory and hard sphere models

    Indian Academy of Sciences (India)

    Vimla Vyas

    2008-04-01

    Speeds of sound and densities of three ternary liquid systems namely, toluene + -heptane + -hexane (I), cyclohexane + -heptane + -hexane (II) and -hexane + - heptane + -decane (III) have been measured as a function of the composition at 298.15 K at atmospheric pressure. The experimental isothermal compressibility has been evaluated from measured values of speeds of sound and density. The isothermal compressibility of these mixtures has also been computed theoretically using different models for hard sphere equations of state and Flory's statistical theory. Computed values of isothermal compressibility have been compared with experimental findings. A satisfactory agreement has been observed. The superiority of Flory's statistical theory has been established quite reasonably over hard sphere models.

  8. Modeling healthcare data using multiple-channel latent Dirichlet allocation.

    Science.gov (United States)

    Lu, Hsin-Min; Wei, Chih-Ping; Hsiao, Fei-Yuan

    2016-04-01

    Information and communications technologies have enabled healthcare institutions to accumulate large amounts of healthcare data that include diagnoses, medications, and additional contextual information such as patient demographics. To gain a better understanding of big healthcare data and to develop better data-driven clinical decision support systems, we propose a novel multiple-channel latent Dirichlet allocation (MCLDA) approach for modeling diagnoses, medications, and contextual information in healthcare data. The proposed MCLDA model assumes that a latent health status group structure is responsible for the observed co-occurrences among diagnoses, medications, and contextual information. Using a real-world research testbed that includes one million healthcare insurance claim records, we investigate the utility of MCLDA. Our empirical evaluation results suggest that MCLDA is capable of capturing the comorbidity structures and linking them with the distribution of medications. Moreover, MCLDA is able to identify the pairing between diagnoses and medications in a record based on the assigned latent groups. MCLDA can also be employed to predict missing medications or diagnoses given partial records. Our evaluation results also show that, in most cases, MCLDA outperforms alternative methods such as logistic regressions and the k-nearest-neighbor (KNN) model for two prediction tasks, i.e., medication and diagnosis prediction. Thus, MCLDA represents a promising approach to modeling healthcare data for clinical decision support.

  9. Modeling healthcare data using multiple-channel latent Dirichlet allocation.

    Science.gov (United States)

    Lu, Hsin-Min; Wei, Chih-Ping; Hsiao, Fei-Yuan

    2016-04-01

    Information and communications technologies have enabled healthcare institutions to accumulate large amounts of healthcare data that include diagnoses, medications, and additional contextual information such as patient demographics. To gain a better understanding of big healthcare data and to develop better data-driven clinical decision support systems, we propose a novel multiple-channel latent Dirichlet allocation (MCLDA) approach for modeling diagnoses, medications, and contextual information in healthcare data. The proposed MCLDA model assumes that a latent health status group structure is responsible for the observed co-occurrences among diagnoses, medications, and contextual information. Using a real-world research testbed that includes one million healthcare insurance claim records, we investigate the utility of MCLDA. Our empirical evaluation results suggest that MCLDA is capable of capturing the comorbidity structures and linking them with the distribution of medications. Moreover, MCLDA is able to identify the pairing between diagnoses and medications in a record based on the assigned latent groups. MCLDA can also be employed to predict missing medications or diagnoses given partial records. Our evaluation results also show that, in most cases, MCLDA outperforms alternative methods such as logistic regressions and the k-nearest-neighbor (KNN) model for two prediction tasks, i.e., medication and diagnosis prediction. Thus, MCLDA represents a promising approach to modeling healthcare data for clinical decision support. PMID:26898516

  10. Sound transmission through lined, composite panel structures: Transversely isotropic poro-elastic model

    Science.gov (United States)

    Kim, Jeong-Woo

    A joint experimental and analytical investigation of the sound transmission loss (STL) and two-dimensional free wave propagation in composite sandwich panels is presented here. An existing panel, a Nomex honeycomb sandwich panel, was studied in detail. For the purpose of understanding the typical behavior of sandwich panels, a composite structure comprising two aluminum sheets with a relatively soft, poro-elastic foam core was also constructed and studied. The cores of both panels were modeled using an anisotropic (transversely isotropic) poro-elastic material theory. Several estimation methods were used to obtain the material properties of the honeycomb core and the skin plates to be used in the numerical calculations. Appropriate values selected from among the estimates were used in the STL and free wave propagation models. The prediction model was then verified in two ways: first, the calculated wave speeds and STL of a single poro-elastic layer were numerically verified by comparison with the predictions of a previously developed isotropic model. Secondly, to physically validate the transversely isotropic model, the measured STL and the phase speeds of the sandwich panels were compared with their predicted values. To analyze the actual treatment of a fuselage structure, multi-layered configurations, including a honeycomb panel and several layers such as air gaps, acoustic blankets and membrane partitions, were formulated. Then, to find the optimal solution for improving the sound barrier performance of an actual fuselage system, air layer depth and glass fiber lining effects were investigated by using these multi-layer models. By using the free wave propagation model, the first anti-symmetric and symmetric modes of the sandwich panels were characterized to allow the identification of the coincidence frequencies of the sandwich panel. The behavior of the STL could then be clearly explained by comparison with the free wave propagation solutions. By performing a

  11. An analytical model for Doppler frequency variations of ionospheric HF sounding caused by SSC

    Science.gov (United States)

    Pilipenko, V.; Fedorov, E.; Yumoto, K.; Ikeda, A.; Sun, T. R.

    2010-10-01

    A theoretical model to interpret the deviations of the Doppler sounding radio frequency during the SSC is proposed. The Doppler response is composed from long-period deviation with time scale ˜10 min and short-lived (˜1 min) positive spike. For the interpretation of this spike, the variations of Doppler velocity induced by compressional and Alfvén waves are theoretically estimated on the basis of the thin ionosphere approximation. The analytical model developed goes beyond the older numerical model which has been in use thus far to explain certain facets of the correlation between geomagnetic variations and HF Doppler shifts. This new model provides the possibility to easily estimate the Doppler frequency response to either Alfvén or compresssional modes for extraordinary and ordinary radio waves. A theoretical estimate indicates that, for the same amplitude of the ground magnetic disturbances, a large-scale compressional mode produces a larger ionospheric response than an Alfvén mode. The plasma vertical displacement caused by the ULF inductive electric field is shown to be the dominating effect. The magnitudes and waveforms of the simultaneously detected ionospheric and magnetic responses on SSC at a low-latitude site in Japan fit the considered model.

  12. Study and Analysis Capacity of MIMO Systems for AWGN Channel Model Scenarios

    Directory of Open Access Journals (Sweden)

    Hussain Bohra

    2014-10-01

    Full Text Available Future wireless communication systems can utilize the spatial properties of the wireless channel to enhance the spectral efficiency and therefore increases its channel capacity. This can be designed by deploying multiple antennas at both the transmitter side and receiver side. The basic measure of performance is the capacity of a channel; the maximum rate of communication for which arbitrarily small error probability can be achieved. The AWGN (additive white Gaussian noise channel introduces the notion of capacity through a heuristic argument. The AWGN channel is then used as a basic building block to check the capacity of wireless fading channels in contrast to the AWGN channel. There is no single definition of capacity for fading channels that is applicable in all situations. Several notions of capacity are developed, and together they form a systematic study of performance limits of fading channels. The various capacity measures allow us to observe clearly the various types of resources available in fading channels: degrees of freedom, power and diversity. The MIMO systems capacity can be enhanced linearly with large the number of antennas. This paper elaborates the study of MIMO system capacity using the AWGN Channel Model, Channel Capacity, Channel Fast Fading, Spatial Autocorrelation and Power delay profile for various channel environments.

  13. Simple illustrations of range-dependence and 3-D effects by normal-mode sound propagation modelling

    CERN Document Server

    Ivansson, Sven

    2016-01-01

    As is well known, the sound-speed profile has significant effects on underwater acoustic sound propagation. These effects can be quantified by normal-mode models, for example. The basic case is a laterally homogeneous medium, for which the sound speed and the density depend on depth only and not on horizontal position. Effects of horizontal medium-parameter variation can be quantified by coupled-mode models, with coupling between mode expansions for laterally homogeneous parts of the medium. In the present paper, these effects are illustrated for media with a particularly simple horizontal parameter variation such that mode shapes do not vary with horizontal position. The modal wavenumbers depend on horizontal position, however. At a vertical interface between regions with laterally homogeneous medium parameters, each mode is reflected as well as transmitted. For the media considered, reflection and transmission coefficients can be computed separately for each mode without mode coupling, and this is done recu...

  14. An empirical movement model for sixgill sharks in Puget Sound: Combining observed and unobserved behavior

    Institute of Scientific and Technical Information of China (English)

    Phillip S. LEVIN; Peter HORNE; Kelly S. ANDREWS; Greg WILLIAMS

    2012-01-01

    Understanding the movement of animals is fundamental to population and community ecology.Historically,it has been difficult to quantify movement patterns of most fishes,but technological advances in acoustic telemetry have increased our abilities to monitor their movement.In this study,we combined small-scale active acoustic tracking with large-scale passive acoustic monitoring to develop an empirical movement model for sixgill sharks in Puget Sound,WA,USA.We began by testing whether a correlated random walk model described the daily movement of sixgills; however,the model failed to capture home-ranging behavior.We added this behavior and used the resultant model (a biased random walk model) to determine whether daily movement patterns are able to explain large-scale seasonal movement.The daily model did not explain the larger-scale patterns of movement observed in the passive monitoring data.In order to create the large-scale patterns,sixgills must have performed behaviors (large,fast directed movements) that were unobserved during small-scale active tracking.In addition,seasonal shifts in location were not captured by the daily model.We added these ‘unobserved' behaviors to the model and were able to capture large-scale seasonal movement of sixgill sharks over 150 days.The development of empirical models of movement allows researchers to develop hypotheses and test mechanisms responsible for a species movement behavior and spatial distribution.This knowledge will increase our ability to successfully manage species of concern [Current Zoology 58 (1):103-115,2012].

  15. Quantum Model for the Selectivity Filter in K$^{+}$ Ion Channel

    CERN Document Server

    Cifuentes, A A

    2013-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field which changes the free energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K$^+$ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone and this increases noise. Moreover, we also show that, for a wide range of driving frequencie...

  16. Pricing Model for Dual Sales Channel with Promotion Effect Consideration

    OpenAIRE

    Chuiri Zhou

    2016-01-01

    We focus on the pricing strategy of a dual sales channel member when his/her online retailer faces an upcoming overloaded express delivery service due to the sales peak of online shopping, especially referring to the occurring affairs in China. We characterize the pricing problem of the dual selling channel system as a two-period game. When the price discount is only provided by the online seller, we find that the prices of the traditional channel and the online channel in the two periods are...

  17. ModFossa: A library for modeling ion channels using Python.

    Science.gov (United States)

    Ferneyhough, Gareth B; Thibealut, Corey M; Dascalu, Sergiu M; Harris, Frederick C

    2016-06-01

    The creation and simulation of ion channel models using continuous-time Markov processes is a powerful and well-used tool in the field of electrophysiology and ion channel research. While several software packages exist for the purpose of ion channel modeling, most are GUI based, and none are available as a Python library. In an attempt to provide an easy-to-use, yet powerful Markov model-based ion channel simulator, we have developed ModFossa, a Python library supporting easy model creation and stimulus definition, complete with a fast numerical solver, and attractive vector graphics plotting. PMID:26932271

  18. Application and validation of a meteorological-acoustical model for outdoor sound propagation

    NARCIS (Netherlands)

    Eerden, F.J.M. van der; Berg, F. van den; Randrianoelina, A.

    2009-01-01

    The Dutch project “Geluid in Beeld” (A view on sound), investigates the impact of industrial sound from the Europort/Maasvlakte area towards the city of Oostvoorne. The reason for this project are unexpected noise complaints, see 1. The project was initiated by The Port of Rotterdam, DCMR, EMO and E

  19. Sound propagation in areas with a complex meteorology: a meteorological-acoustical model

    NARCIS (Netherlands)

    Eerden, F.J.M. van der; Berg, F. van den

    2008-01-01

    Long range sound propagation is largely affected by the vertical wind and temperature gradients. In areas where the meteorology can be complex, such as coastal areas, islands, and lake districts, the gradients usually vary as a function of the horizontal distance. As a result the sound propagation i

  20. Note: Sound velocity of a soft sphere model near the fluid-solid phase transition.

    Science.gov (United States)

    Khrapak, Sergey A

    2016-03-28

    The quasilocalized charge approximation is applied to estimate the sound velocity of simple soft sphere fluid with the repulsive inverse-power-law interaction. The obtained results are discussed in the context of the sound velocity of the hard-sphere system and of liquid metals at the melting temperature. PMID:27036483

  1. Improving the channeler ant model for lung CT analysis

    Science.gov (United States)

    Cerello, Piergiorgio; Lopez Torres, Ernesto; Fiorina, Elisa; Oppedisano, Chiara; Peroni, Cristiana; Arteche Diaz, Raul; Bellotti, Roberto; Bosco, Paolo; Camarlinghi, Niccolo; Massafra, Andrea

    2011-03-01

    The Channeler Ant Model (CAM) is an algorithm based on virtual ant colonies, conceived for the segmentation of complex structures with different shapes and intensity in a 3D environment. It exploits the natural capabilities of virtual ant colonies to modify the environment and communicate with each other by pheromone deposition. When applied to lung CTs, the CAM can be turned into a Computer Aided Detection (CAD) method for the identification of pulmonary nodules and the support to radiologists in the identification of early-stage pathological objects. The CAM has been validated with the segmentation of 3D artificial objects and it has already been successfully applied to the lung nodules detection in Computed Tomography images within the ANODE09 challenge. The model improvements for the segmentation of nodules attached to the pleura and to the vessel tree are discussed, as well as a method to enhance the detection of low-intensity nodules. The results on five datasets annotated with different criteria show that the analytical modules (i.e. up to the filtering stage) provide a sensitivity in the 80 - 90% range with a number of FP/scan of the order of 20. The classification module, although not yet optimised, keeps the sensitivity in the 70 - 85% range at about 10 FP/scan, in spite of the fact that the annotation criteria for the training and the validation samples are different.

  2. Multi-reaction-channel fitting calculations in a coupled-channel model: Photoinduced strangeness production

    Indian Academy of Sciences (India)

    O Scholten; A Usov

    2010-08-01

    To describe photo- and meson-induced reactions on the nucleon, one is faced with a rather extensive coupled-channel problem. Ignoring the effects of channel coupling, as one would do in describing a certain reaction at the tree level, invariably creates a large inconsistency between the different reactions that are described. In addition, the imaginary parts of the amplitude, which are related through the optical theorem, to total cross-sections, are directly reflected in certain polarization observables. Performing a full coupled-channel calculation thus offers the possibility to implement the maximum number of constraints. The drawback one is faced with is to arrive at a simultaneous fit of a large number of reaction channels. While some of the parameters are common to many reactions, one is still faced with the challenge to optimize a large number of parameters in a highly non-linear calculation. Here we show that such an approach is possible and present some results for photoinduced strangeness production.

  3. Sound velocity of hcp-Fe at high pressure: experimental constraints, extrapolations and comparison with seismic models

    Science.gov (United States)

    Antonangeli, Daniele; Ohtani, Eiji

    2015-12-01

    Determining the sound velocity of iron under extreme thermodynamic conditions is essential for a proper interpretation of seismic observations of the Earth's core but is experimentally challenging. Here, we review techniques and methodologies used to measure sound velocities in metals at megabar pressures, with specific focus on the compressional sound velocity of hexagonal close-packed iron. A critical comparison of literature results, coherently analyzed using consistent metrology (pressure scale, equation of state), allows us to propose reference relations for the pressure and density dependence of the compressional velocity of hexagonal close-packed iron at ambient temperature. This provides a key base line upon which to add complexity, including high-temperature effects, pre-melting effects, effects of nickel and/or light element incorporation, necessary for an accurate comparison with seismic models, and ultimately to constrain Earth's inner core composition.

  4. Use of slow sound to design perfect and broadband passive sound absorbing materials.

    Science.gov (United States)

    Groby, J-P; Pommier, R; Aurégan, Y

    2016-04-01

    Perfect (100%) absorption by thin structures consisting of a periodic arrangement of rectangular quarter-wavelength channels with side detuned quarter-wavelength resonators is demonstrated. The thickness of these structures is 13-17 times thinner than the acoustic wavelength. This low frequency absorption is due to a slow sound wave propagating in the main rectangular channel. A theoretical model is proposed to predict the complex wavenumber in this channel. It is shown that the speed of sound in the channel is much lower than in the air, almost independent of the frequency in the low frequency range, and it is dispersive inside the induced transparency band which is observed. The perfect absorption condition is found to be caused by a critical coupling between the rectangular channel (sub-wavelength resonators) and the incoming wave. It is shown that the width of a large absorption peak in the frequency spectrum can be broadened if several rectangular channels in the unit cell are detuned. The detuning is achieved by varying the length of the side resonators for each channel. The predicted absorption coefficients are validated experimentally. Two resonant cells were produced with stereolithography which enabled the authors to incorporate curved side resonators. PMID:27106313

  5. Puget Sound ocean acidification model outputs - Modeling the impacts of ocean acidification on ecosystems and populations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NWFSC OA team will model the effects of ocean acidification on regional marine species and ecosystems using food web models, life-cycle models, and bioenvelope...

  6. Abdominal sounds

    Science.gov (United States)

    ... during sleep. They also occur normally for a short time after the use of certain medicines and after abdominal surgery. Decreased or absent bowel sounds often indicate constipation. Increased ( hyperactive ) bowel sounds ...

  7. Simulation and performance Analysis of a Novel Model for Short Range Underwater Acoustic communication Channel Using Ray Tracing Method in Turbulent Shallow Water Regions of the Persian Gulf

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Dargahi

    2011-01-01

    Full Text Available High data rate acoustic transmission is required for diverse underwater operations such as the retrieval of large amounts of data from bottom packages and real time transmission of signals from underwater sensors. The major obstacle to underwater acoustic communication is the interference of multipath signals due to surface and bottom reflections. High speed acoustic transmission over a shallow water channel characterized by small grazing angles presents formidable difficulties. The reflection losses associated with such small angles are low, causing large amplitudes in multi-path signals. In this paper, based on the results obtained from practical measurements in the Persian Gulf and available data about sound speed variations in different depths, we propose a simple but effective model for shallow water short-range multipath acoustic channel. Based on the Ray theory, mathematical modeling of multipath effects is carried out. Also in channel modeling, the attenuation due to the wave scatterings at the surface and its bottom reflections for deferent grazing angles and bottom types is considered. In addition, we consider the attenuations due to the absorption of different materials and ambient noises such as see-state noise, shipping noise, thermal noise and turbulences. We use a three-dimensional hydrodynamic model (COHERENS in a fully prognostic mode to study the circulation and water mass properties of the Persian Gulf - a large inverse estuary. Maximum sound speed occurs during the summer in the Persian Gulf which decreases gradually moving from the Strait of Hormuz to the north western part of the Gulf. A gradual decrease in sound speed profiles with depth was commonly observed in almost all parts of the Gulf. However, an exception occurred in the Strait of Hormuz during the winter. The results of the model are in very good agreement with our observations.

  8. Foley Sounds vs Real Sounds

    DEFF Research Database (Denmark)

    Trento, Stefano; Götzen, Amalia De

    2011-01-01

    This paper is an initial attempt to study the world of sound effects for motion pictures, also known as Foley sounds. Throughout several audio and audio-video tests we have compared both Foley and real sounds originated by an identical action. The main purpose was to evaluate if sound effects...... are always better than real sounds [1]. Once this aspect is cleared up, the next step will be to understand how Foley effects exaggerate important acoustic features. These are the basis for being able to create a database of expressive sounds, such as audio caricatures, that will be used in different...

  9. Modeling channel interference in an orbital angular momentum-multiplexed laser link

    Science.gov (United States)

    Anguita, Jaime A.; Neifeld, Mark A.; Vasic, Bane V.

    2009-08-01

    We study the effects of optical turbulence on the energy crosstalk among constituent orbital angular momentum (OAM) states in a vortex-based multi-channel laser communication link and determine channel interference in terms of turbulence strength and OAM state separation. We characterize the channel interference as a function of C2n and transmit OAM state, and propose probability models to predict the random fluctuations in the received signals for such architecture. Simulations indicate that turbulence-induced channel interference is mutually correlated across receive channels.

  10. Tools and methods for evaluating and refining alternative futures for coastal ecosystem management—the Puget Sound Ecosystem Portfolio Model

    Science.gov (United States)

    Byrd, Kristin B.; Kreitler, Jason R.; Labiosa, William B.

    2011-01-01

    The U.S. Geological Survey Puget Sound Ecosystem Portfolio Model (PSEPM) is a decision-support tool that uses scenarios to evaluate where, when, and to what extent future population growth, urban growth, and shoreline development may threaten the Puget Sound nearshore environment. This tool was designed to be used iteratively in a workshop setting in which experts, stakeholders, and decisionmakers discuss consequences to the Puget Sound nearshore within an alternative-futures framework. The PSEPM presents three possible futures of the nearshore by analyzing three growth scenarios developed out to 2060: Status Quo—continuation of current trends; Managed Growth—adoption of an aggressive set of land-use management policies; and Unconstrained Growth—relaxation of land-use restrictions. The PSEPM focuses on nearshore environments associated with barrier and bluff-backed beaches—the most dominant shoreforms in Puget Sound—which represent 50 percent of Puget Sound shorelines by length. This report provides detailed methodologies for development of three submodels within the PSEPM—the Shellfish Pollution Model, the Beach Armoring Index, and the Recreation Visits Model. Results from the PSEPM identify where and when future changes to nearshore ecosystems and ecosystem services will likely occur within the three growth scenarios. Model outputs include maps that highlight shoreline sections where nearshore resources may be at greater risk from upland land-use changes. The background discussed in this report serves to document and supplement model results displayed on the PSEPM Web site located at http://geography.wr.usgs.gov/pugetSound/.

  11. RFI channels

    Science.gov (United States)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  12. Sensitivity of a hydraulic model to changes in channel erosion during extreme flooding

    OpenAIRE

    Wong, Jefferson S.; Freer, Jim E; Bates, Paul D.; Stephens, Elisabeth M.

    2014-01-01

    Recent research into flood modelling has primarily concentrated on the simulation of inundation flow without considering the influences of channel morphology. River channels are often represented by a simplified geometry that is implicitly assumed to remain unchanged during flood simulations. However, field evidence demonstrates that significant morphological changes can occur during floods to mobilise the boundary sediments. Despite this, the effect of channel morphology on model results has...

  13. Observationally constrained modeling of sound in curved ocean internal waves: examination of deep ducting and surface ducting at short range.

    Science.gov (United States)

    Duda, Timothy F; Lin, Ying-Tsong; Reeder, D Benjamin

    2011-09-01

    A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the shelf of the South China Sea northeast of Tung-Sha Island. Construction of the time-varying three-dimensional sound-speed fields used in the modeling simulations was guided by environmental data collected concurrently with the acoustic data. Computed three-dimensional propagation results compare well with field observations. The simulations allow identification of time-dependent sound forward scattering and ducting processes within the curved internal gravity waves. Strong acoustic intensity enhancement was observed during passage of high-amplitude nonlinear waves over the source/receiver paths, and is replicated in the model. The waves were typical of the region (35 m vertical displacement). Two types of ducting are found in the model, which occur asynchronously. One type is three-dimensional modal trapping in deep ducts within the wave crests (shallow thermocline zones). The second type is surface ducting within the wave troughs (deep thermocline zones).

  14. Development of the software tool for generation and visualization of the finite element head model with bone conduction sounds

    Science.gov (United States)

    Nikolić, Dalibor; Milošević, Žarko; Saveljić, Igor; Filipović, Nenad

    2015-12-01

    Vibration of the skull causes a hearing sensation. We call it Bone Conduction (BC) sound. There are several investigations about transmission properties of bone conducted sound. The aim of this study was to develop a software tool for easy generation of the finite element (FE) model of the human head with different materials based on human head anatomy and to calculate sound conduction through the head. Developed software tool generates a model in a few steps. The first step is to do segmentation of CT medical images (DICOM) and to generate a surface mesh files (STL). Each STL file presents a different layer of human head with different material properties (brain, CSF, different layers of the skull bone, skin, etc.). The next steps are to make tetrahedral mesh from obtained STL files, to define FE model boundary conditions and to solve FE equations. This tool uses PAK solver, which is the open source software implemented in SIFEM FP7 project, for calculations of the head vibration. Purpose of this tool is to show impact of the bone conduction sound of the head on the hearing system and to estimate matching of obtained results with experimental measurements.

  15. Imagining Sound

    DEFF Research Database (Denmark)

    Grimshaw, Mark; Garner, Tom Alexander

    2014-01-01

    We make the case in this essay that sound that is imagined is both a perception and as much a sound as that perceived through external stimulation. To argue this, we look at the evidence from auditory science, neuroscience, and philosophy, briefly present some new conceptual thinking on sound...

  16. Attacking and Defending Covert Channels and Behavioral Models

    CERN Document Server

    Crespi, Valentino; Giani, Annarita

    2011-01-01

    In this paper we present methods for attacking and defending $k$-gram statistical analysis techniques that are used, for example, in network traffic analysis and covert channel detection. The main new result is our demonstration of how to use a behavior's or process' $k$-order statistics to build a stochastic process that has those same $k$-order stationary statistics but possesses different, deliberately designed, $(k+1)$-order statistics if desired. Such a model realizes a "complexification" of the process or behavior which a defender can use to monitor whether an attacker is shaping the behavior. By deliberately introducing designed $(k+1)$-order behaviors, the defender can check to see if those behaviors are present in the data. We also develop constructs for source codes that respect the $k$-order statistics of a process while encoding covert information. One fundamental consequence of these results is that certain types of behavior analyses techniques come down to an {\\em arms race} in the sense that th...

  17. Processing of sounds by population spikes in a model of primary auditory cortex

    Directory of Open Access Journals (Sweden)

    Alex Loebel

    2007-10-01

    Full Text Available We propose a model of the primary auditory cortex (A1, in which each iso-frequency column is represented by a recurrent neural network with short-term synaptic depression. Such networks can emit Population Spikes, in which most of the neurons fire synchronously for a short time period. Different columns are interconnected in a way that reflects the tonotopic map in A1, and population spikes can propagate along the map from one column to the next, in a temporally precise manner that depends on the specific input presented to the network. The network, therefore, processes incoming sounds by precise sequences of population spikes that are embedded in a continuous asynchronous activity, with both of these response components carrying information about the inputs and interacting with each other. With these basic characteristics, the model can account for a wide range of experimental findings. We reproduce neuronal frequency tuning curves, whose width depends on the strength of the intracortical inhibitory and excitatory connections. Non-simultaneous two-tone stimuli show forward masking depending on their temporal separation, as well as on the duration of the first stimulus. The model also exhibits non-linear suppressive interactions between sub-threshold tones and broad-band noise inputs, similar to the hypersensitive locking suppression recently demonstrated in auditory cortex.We derive several predictions from the model. In particular, we predict that spontaneous activity in primary auditory cortex gates the temporally locked responses of A1 neurons to auditory stimuli. Spontaneous activity could, therefore, be a mechanism for rapid and reversible modulation of cortical processing.

  18. Sound generation by turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Dowling, A.P.; Hynes, T.P. [Cambridge Univ., Dept. of Engineering (United Kingdom)

    2004-06-01

    Sound is a weak by-product of a subsonic turbulent flow. The main convective elements of the turbulence are silent and it is only spectral components with supersonic phase speeds that couple to the far-field sound. This paper reviews recent work on sound generation by turbulence. Just as there is a hierarchy of numerical models for turbulence (scaling, RANS, LES and DNS), there are different approaches for relating the near-field turbulence to the far-field sound. Kirchhoff approaches give the far-field sound in a straightforward way, but provide little insight into the sources of sound. Acoustic analogies can be used with different base flows to describe the propagation effects and to highlight the major noise producing regions. (authors)

  19. Use of multidimensional modeling to evaluate a channel restoration design for the Kootenai River, Idaho

    Science.gov (United States)

    Logan, B.L.; McDonald, R.R.; Nelson, J.M.; Kinzel, P.J.; Barton, G.J.

    2011-01-01

    River channel construction projects aimed at restoring or improving degraded waterways have become common but have been variously successful. In this report a methodology is proposed to evaluate channel designs before channels are built by using multidimensional modeling and analysis. This approach allows detailed analysis of water-surface profiles, sediment transport, and aquatic habitat that may result if the design is implemented. The method presented here addresses the need to model a range of potential stream-discharge and channel-roughness conditions to best assess the function of the design channel for a suite of possible conditions. This methodology is demonstrated by using a preliminary channel-restoration design proposed for a part of the Kootenai River in northern Idaho designated as critical habitat for the endangered white sturgeon (Acipenser transmontanus) and evaluating the design on the basis of simulations with the Flow and Sediment Transport with Morphologic Evolution of Channels (FaSTMECH) model. This evaluation indicated substantial problems with the preliminary design because boundary conditions used in the design were inconsistent with best estimates of future conditions. As a result, simulated water-surface levels did not meet target levels that corresponded to the designed bankfull surfaces; therefore, the flood plain would not function as intended. Sediment-transport analyses indicated that both the current channel of the Kootenai River and the design channel are largely unable to move the bed material through the reach at bankfull discharge. Therefore, sediment delivered to the design channel would likely be deposited within the reach instead of passing through it as planned. Consequently, the design channel geometry would adjust through time. Despite these issues, the design channel would provide more aquatic habitat suitable for spawning white sturgeon (Acipenser transmontanus) at lower discharges than is currently available in the

  20. Impact of the chosen turbulent flow empirical model on the prediction of sound radiation and vibration by aircraft panels

    Science.gov (United States)

    Rocha, Joana

    2016-07-01

    A precise definition of the turbulent boundary layer excitation is required to accurately predict the sound radiation and surface vibration levels, produced by an aircraft panel excited turbulent flow during flight. Hence, any existing inaccuracy on turbulent boundary layer excitation models leads to an inaccurate prediction of the panel response. A number of empirical models have been developed over the years to provide the turbulent boundary layer wall pressure spectral density. However, different empirical models provide dissimilar predictions for the wall pressure spectral density. The objective of the present study is to investigate and quantify the impact of the chosen empirical model on the predicted radiated sound power, and on the predicted panel surface acceleration levels. This study provides a novel approach and a detailed analysis on the use of different turbulent boundary layer wall pressure empirical models, and impact on mathematical predictions. Closed-form mathematical relationships are developed, and recommendations are provided for the level of deviation and uncertainty associated to different models, in relation to a baseline model, both for panel surface acceleration and radiated sound power.

  1. Modelling of diffuse sound field in architectural acoustic using transport theory

    OpenAIRE

    LE POLLES, T; Picaut, J.; BERENGIER, M

    2001-01-01

    A general formalism to predict the repartition of diffuse sound field energy, in rooms and urban areas including scattering effects, is presented. We propose an exact analytical description of the spatial and temporal evolution of the diffuse sound field energy by the use of a transport equation. Boundary conditions are described in a probabilistic way and are expressed in terms of façade or wall reflection laws including absorption and scattering effects. Applications to room acoustics are t...

  2. Fog forecasting: ``old fashioned'' semi-empirical methods from radio sounding observations versus ``modern'' numerical models

    Science.gov (United States)

    Holtslag, M. C.; Steeneveld, G. J.; Holtslag, A. A. M.

    2010-07-01

    Fog forecasting is a very challenging task due to the local and small-scale nature of the relevant physical processes and land surface heterogeneities. Despite the many research efforts, numerical models remain to have difficulties with fog forecasting, and forecast skill from direct model output is relatively poor. In order to put the progress of fog forecasting in the last decades into a historical perspective, we compare the fog forecasting skill of a semi-empirical method based on radio sounding observations (developed in the 60s and 70s) with the forecasting skill of a state-of-the-art numerical weather prediction model (MM5) for The Netherlands. The semi-empirical method under investigation, the Fog Stability Index, depends solely on the temperature difference between the surface and 850 hPa, the surface dew point depression and the wind speed at 850 hPa, and a threshold value to indicate the probability of fog in the coming hours. Using the critical success index (CSI) as a criterion for forecast quality, we find that the Fog Stability Index is a rather successful predictor for fog, with similar performance as MM5. The FSI could even been optimized for different observational stations in the Netherlands. Also, it appears that adding the 10 m wind as a predictor did not increase the CSI score for all stations. The results of the current study clearly indicate that the current state of knowledge requires improvement of the physical insight in different physical processes in order to beat simple semi-empirical methods.

  3. Binaural model for artificial spatial sound localization based on interaural time delays and movements of the interaural axis.

    Science.gov (United States)

    Kneip, Laurent; Baumann, Claude

    2008-11-01

    This paper presents a mathematical model for sound localization in space using two-microphone devices that possess at least two degrees of freedom. It proves a series of theorems and lemmas that are based on time difference of arrival measurements and movements of the interaural axis, forming a powerful instrument for practical robot applications. For instance, it shows that a single determined rotation of the interaural axis is sufficient to exactly yield the azimuth or the elevation of an immobile sound source in the far field, independently of microphone spacing and the speed of sound and hence of the surrounding medium. It proves that at any moment the knowledge of one value determines the magnitude of the other, with the restriction that the sign of the second value is undefined, which means that, depending on the rotation, either the back-front or the up-down ambiguity is kept unsolved. This paper also shows that parallax motion unlocks essential information about the distance and the Cartesian coordinates of the sound source. Shifting the microphone system sideways fixes the distance and the coordinate on the interaural axis. Combining rotation and translation movements completely solves the localization problem. In order to illustrate the efficacy of the model, this paper presents experiments with a low cost robot developer kit during which the azimuth, the elevation, and the distance of continuous sound sources are determined at a precision of 10 degrees and 0.5 m, respectively. Achieving this performance with low power material demonstrates how easily the model can be implemented into any robotic system.

  4. Pricing Model for Dual Sales Channel with Promotion Effect Consideration

    Directory of Open Access Journals (Sweden)

    Chuiri Zhou

    2016-01-01

    Full Text Available We focus on the pricing strategy of a dual sales channel member when his/her online retailer faces an upcoming overloaded express delivery service due to the sales peak of online shopping, especially referring to the occurring affairs in China. We characterize the pricing problem of the dual selling channel system as a two-period game. When the price discount is only provided by the online seller, we find that the prices of the traditional channel and the online channel in the two periods are higher while the overloaded degree of express delivery is lower and the overloaded delivery services can decrease the profits of both channels. When the price discounts are provided by both traditional and online sellers, we find that the derived Nash price equilibrium of both channels includes five possible combinations of prices. Both traditional and online sellers will choose their price strategies, respectively, according to their cost advantages which are affected by the overloaded degree of express delivery.

  5. Evaluation of Internet channels and their impacts on Irish mobile operators' business models

    OpenAIRE

    Ademowo, Adewale

    2013-01-01

    Ademowo, Adewale Adebayo Evaluation of Internet Channels and their impacts on Irish Mobile Operators' Business Models Jyväskylä: University of Jyväskylä, 2013, 108 p. Mobile Technology and Business (Major in Information Systems Science), Master's Thesis Supervisor: Luoma, Eetu This study finds the impacts of the Internet channels on mobile operators’ business models with Ireland as a case. It reflects on the business model concepts, business models of mobile telecom indust...

  6. A conceptual model of channel choice: measuring online and offline shopping value perceptions

    OpenAIRE

    Broekhuizen, Thijs L.J.; Jager, Wander

    2004-01-01

    This study tries to understand how consumers evaluate channels for their purchasing. Specifically, it develops a conceptual model that addresses consumer value perceptions of using the Internet versus the traditional (physical) channel. Previous research showed that perceptions of price, product quality, service quality and risk strongly influence perceived value and purchase intentions in the offline and online channel. Perceptions of online and offline buyers can be analyzed to see how valu...

  7. Cantonese English as a Second Language Learners' Perceived Relations between "Similar" L1 and L2 Speech Sounds: A Test of the Speech Learning Model

    Science.gov (United States)

    Chan, Alice Y. W.

    2012-01-01

    This article reports on the results of a research study that investigated Cantonese English as a second language (ESL) learners' perception of English speech sounds, their perceived relations between "similar" English and Cantonese sounds, as well as the applicability of the claims of the Speech Learning Model (SLM) to second language (L2)…

  8. Uncertainty analysis of channel capacity assumptions in large scale hydraulic modelling

    Science.gov (United States)

    Walsh, Alexander; Stroud, Rebecca; Willis, Thomas

    2015-04-01

    Flood modelling on national or even global scales is of great interest to re/insurers, governments and other agencies. Channel bathymetry data is not available over large areas which is a major limitation to this scale of modelling. It requires expensive channel surveying and the majority of remotely sensed data cannot see through water. Furthermore, channels represented as 1D models, or as an explicit feature in the model domain is computationally demanding, and so it is often necessary to find ways to reduce computational costs. A more efficient methodology is to make assumptions concerning the capacity of the channel, and then to remove this volume from inflow hydrographs. Previous research have shown that natural channels generally conform to carry flow for a 1-in-2 year return period (QMED). This assumption is widely used in large scale modelling studies across the world. However, channels flowing through high-risk areas, such as urban environments, are often modified to increase their capacity and thus reduce flood risk. Simulated flood outlines are potentially very sensitive to assumptions made regarding these capacities. For example, under the 1-in-2 year assumption, the flooding associated with smaller events might be overestimated, with too much flow being modelled as out of bank. There are requirements to; i) quantify the impact of uncertainty in assumed channel capacity on simulated flooded areas, and ii) to develop more optimal capacity assumptions, depending on specific reach characteristics, so that the effects of channel modification can be better represented in future studies. This work will demonstrate findings from a preliminary uncertainty analysis that seeks to address the former requirement. A set of benchmark tests, using 2D hydraulic models, were undertaken where different estimated return period flows in contrasting catchments are modelled with varying channel capacity parameters. The depth and extent for each benchmark model output were

  9. A communication channel model of the software process

    Science.gov (United States)

    Tausworthe, Robert C.

    1988-01-01

    Beginning research into a noisy communication channel analogy of software development process productivity, in order to establish quantifiable behavior and theoretical bounds is discussed. The analogy leads to a fundamental mathematical relationship between human productivity and the amount of information supplied by the developers, the capacity of the human channel for processing and transmitting information, the software product yield (object size) the work effort, requirements efficiency, tool and process efficiency, and programming environment advantage. An upper bound to productivity is derived that shows that software reuse is the only means that can lead to unbounded productivity growth; practical considerations of size and cost of reusable components may reduce this to a finite bound.

  10. $a_0(980)$ photoproduction in the coupled channel model

    CERN Document Server

    Bibrzycki, Ł

    2016-01-01

    We calculated the coupled channel photoproduction amplitudes of the scalar isovector resononace $a_0(980)$, which include the $\\pi\\eta$, $K^+K^-$ and $K^0\\overline{K^0}$ intermediate states. Based on them we obtained the mass distribution in the $\\pi\\eta$ channel at photon energy $E_\\gamma$=7 GeV, corresponding to energy accissible in new JLab experiments CLAS12 and GlueX. We also analyzed the shape of mass distribution as a function of the phase of the background amplitude.

  11. Development of defueling device for CANDU fuel channel (modeling)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. Y.; Yu, K. H.; Yang, J. S.; Lee, H. S.; Chang, K. J.; Kim, Y. J. [CNEC Technical Office, Taejon (Korea, Republic of); Lee, S. K. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    2004-07-01

    Commercial CANDU reactors use D{sub 2}O for moderator and heat transfer material and also have Fueling Machines(F/M) and related system equipment in order to assist on-power refueling operation. A Defuelling Device(DFD) is developed for the proper defuelling of all fuels in all fuel channels during shutdown condition of plant. This device is considered more efficient in defuelling compared to the existing Fuel Grapple System for its use of existing D{sub 2}O flow in the fuel channel. In this study, computational fluid dynamic software is used for optimize and evaluation of the design for its applicability.

  12. The sound of oscillating air jets: Physics, modeling and simulation in flute-like instruments

    Science.gov (United States)

    de La Cuadra, Patricio

    Flute-like instruments share a common mechanism that consists of blowing across one open end of a resonator to produce an air jet that is directed towards a sharp edge. Analysis of its operation involves various research fields including fluid dynamics, aero-acoustics, and physics. An effort has been made in this study to extend this description from instruments with fixed geometry like recorders and organ pipes to flutes played by the lips. An analysis of the jet's response to a periodic excitation is the focus of this study, as are the parameters under the player's control in forming the jet. The jet is excited with a controlled excitation consisting of two loudspeakers in opposite phase. A Schlieren system is used to visualize the jet, and image detection algorithms are developed to extract quantitative information from the images. In order to study the behavior of jets observed in different flute-like instruments, several geometries of the excitation and jet shapes are studied. The obtained data is used to propose analytical models that correctly fit the observed measurements and can be used for simulations. The control exerted by the performer on the instrument is of crucial importance in the quality of the sound produced for a number of flute-like instruments. The case of the transverse flute is experimentally studied. An ensemble of control parameters are measured and visualized in order to describe some aspects of the subtle control attained by an experienced flautist. Contrasting data from a novice flautist are compared. As a result, typical values for several non-dimensional parameters that characterize the normal operation of the instrument have been measured, and data to feed simulations has been collected. The information obtained through experimentation is combined with research developed over the last decades to put together a time-domain simulation. The model proposed is one-dimensional and driven by a single physical input. All the variables in the

  13. Risk mapping for sensitive species to underwater anthropogenic sound emissions: model development and validation in two Mediterranean areas.

    Science.gov (United States)

    Azzellino, A; Lanfredi, C; D'Amico, A; Pavan, G; Podestà, M; Haun, J

    2011-01-01

    Recent observations of cetacean mass strandings, coincident with anthropogenic sounds emissions, have raised concerns on the potential environmental impact of underwater noise. Cuvier's beaked whale (Ziphius cavirostris) was reported in all the cited stranding events. Within the NATO Marine Mammal Risk Mitigation project (MMRM), multiple interdisciplinary sea trials have been conducted in the Mediterranean Sea with the objective of developing tools and procedures to mitigate the impact of underwater sound emissions. During these cruises, visual observations, passive acoustic detections and environmental data were collected. The aim of this study was to evaluate "a priori" predictions of Cuvier's beaked whale presence in the Alboran Sea, using models developed in the Ligurian Sea that employ bathymetric and chlorophyll features as predictors. The accuracy of these predictions was found adequate and elements are given to account for the uncertainties associated to the use of models developed in areas different from their calibration site.

  14. Risk mapping for sensitive species to underwater anthropogenic sound emissions: model development and validation in two Mediterranean areas.

    Science.gov (United States)

    Azzellino, A; Lanfredi, C; D'Amico, A; Pavan, G; Podestà, M; Haun, J

    2011-01-01

    Recent observations of cetacean mass strandings, coincident with anthropogenic sounds emissions, have raised concerns on the potential environmental impact of underwater noise. Cuvier's beaked whale (Ziphius cavirostris) was reported in all the cited stranding events. Within the NATO Marine Mammal Risk Mitigation project (MMRM), multiple interdisciplinary sea trials have been conducted in the Mediterranean Sea with the objective of developing tools and procedures to mitigate the impact of underwater sound emissions. During these cruises, visual observations, passive acoustic detections and environmental data were collected. The aim of this study was to evaluate "a priori" predictions of Cuvier's beaked whale presence in the Alboran Sea, using models developed in the Ligurian Sea that employ bathymetric and chlorophyll features as predictors. The accuracy of these predictions was found adequate and elements are given to account for the uncertainties associated to the use of models developed in areas different from their calibration site. PMID:21349554

  15. Channel selection in e-commerce age: A strategic analysis of co-op advertising models

    Directory of Open Access Journals (Sweden)

    Yongmei Liu

    2013-03-01

    Full Text Available Purpose: The purpose of this paper is to develop and compare two co-op advertising models: advertising model under traditional channel and co-op advertising model under dual channel, to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer.Design/methodology/approach: Stackelberg game theoretical is used to develop two co-op advertising models: co-op advertising model under traditional channel and co-op advertising model under dual channel. Then we compare the two models to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer. Furthermore, we analyze the impact of product web-fit on these optimal strategies and illustrate by some numeral examples. Based on our results, we provide some significant theories and managerial insights, and derive some probable paths of future research.Findings: We provide a framework for researching optimal co-op advertising strategies in a two-level supply chain considering different marketing channel structures. First, we discuss the traditional channel co-op adverting model and the dual channel co-op advertising model based on Stackelberg game theoretical, and we derive optimal co-op advertising strategies. Next, comparisons of these two channel structures are discussed and we find that the manufacturer always benefits from dual channel. But the retailer not always benefits from dual channel structure, and dual channel structure is better than retail channel with certain conditions. Also, the optimal co-op advertising strategies for the manufacturer and the retailer are obtained.Research limitations/implications: First, we focus on the aforementioned two channel structures; a further comparison with other channel structures can be investigated. Second, we ignore some factors that influence the demand of product

  16. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  17. Sound intensity radiated by Gaohu

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Gaohu is one of the main bowed stringed instruments used in Guangdong music and Chinese native Orchestra. However its sound intensity has never been carefully measured. In this paper the sound power measurements of Gaohu were performed in a reverberation chamber according to the Chinese national standard. Two qualified musicians performed on their own instruments. The mean sound power levels and the dynamic ranges of Gaohu were investigated by four channel acoustic measuring equipments when single notes, music scale and melodies were performed under pp, mp, f and ff dynamics. Great differences were found when Gaohu performed single notes, while the sound power levels were quite close when music scale were performed under f dynamic to those when melodies were performed under normal dynamic mark, the sound power levels of Gaohu when music scale was performed under f dynamics were suggested as the typical and representative value of the sound intensities of Gaohu instrument.

  18. Investigation of the Sound Pressure Level (SPL) of earphones during music listening with the use of physical ear canal models

    Science.gov (United States)

    Aying, K. P.; Otadoy, R. E.; Violanda, R.

    2015-06-01

    This study investigates on the sound pressure level (SPL) of insert-type earphones that are commonly used for music listening of the general populace. Measurements of SPL from earphones of different respondents were measured by plugging the earphone to a physical ear canal model. Durations of the earphone used for music listening were also gathered through short interviews. Results show that 21% of the respondents exceed the standard loudness/duration relation recommended by the World Health Organization (WHO).

  19. Autopoiesis and sonic immersion:Modelling sound-based player relationships as a self-organizing system

    OpenAIRE

    Grimshaw, Mark Nicholas

    2008-01-01

    In previous work I have provided a conceptual framework for the design and analysis of sound in First-Person Shooter games and have suggested that the relationship between player and soundscape in such games can be modeled as an acoustic ecology. This paper develops these ideas further in the context of multiplayer First-Person Shooter games. I suggest that individual acoustic ecologies within the game combine to create a virtual acoustic ecology, of which no player is wholly aware, and that ...

  20. Emulating Spherical Wave Channel Models in Multi-probe Anechoic Chamber Setups

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum;

    2015-01-01

    Spherical wave channel modeling has attracted huge research attention for massive multiple-input multiple-output (MIMO) and short-distance MIMO systems. Current research work in multi-probe anechoic chamber systems is limited to reproduce radio channels assuming planar wavefronts. There is a need...

  1. A conceptual model of channel choice : measuring online and offline shopping value perceptions

    NARCIS (Netherlands)

    Broekhuizen, Thijs L.J.; Jager, Wander

    2004-01-01

    This study tries to understand how consumers evaluate channels for their purchasing. Specifically, it develops a conceptual model that addresses consumer value perceptions of using the Internet versus the traditional (physical) channel. Previous research showed that perceptions of price, product qua

  2. Multiple Thresholds Arise in a Model System of Noisy Ion Channels

    CERN Document Server

    Barber, M J; Barber, Michael J.; Ristig, Manfred L.

    2006-01-01

    Voltage-activated ion channels vary randomly between a conducting or open state and a nonconducting or closed state in response to thermal fluctuations, with this variation influenced by the membrane potential and a broad assortment of other factors. We show that signal transduction is enhanced by a non-zero level of noise in a simple model of ion channels. The enhancement is restricted to a finite range of signals, but this range can be extended using populations of channels. The range increases more rapidly in heterogeneous populations of channels having various thresholds than in homogeneous populations of channels with a single threshold. The diversity of cellular ion channels may thus be present as an economical information-processing strategy, reducing the metabolic cost of handling a broad class of electrochemical signals with simple processing elements.

  3. Analysis and evaluation of channel models : Simulations of alamethicin

    NARCIS (Netherlands)

    Tieleman, DP; Hess, B; Sansom, MSP

    2002-01-01

    Alamethicin is an antimicrobial peptide that forms stable channels with well-defined conductance levels. We have used extended molecular dynamics simulations of alamethicin bundles consisting of 4, 5, 6, 7, and 8 helices in a palmitoyl-oleolyl-phosphatidylcholine bilayer to evaluate and analyze chan

  4. Model 516 LSI-11: six-channel scaler

    Energy Technology Data Exchange (ETDEWEB)

    Bourret, S.; Crane, T.W.; Eccleston, G.W.; Johnson, S.; Slice, R.

    1981-12-01

    The LSI-11 scaler module has six separate counting channels, each with a 24-bit capacity. The scaler is located in the backplane of the computer and operated using software programs. This report describes the scaler, shows how to operate and test it, and provides listings of the scaler software control programs.

  5. Design of Wideband MIMO Car-to-Car Channel Models Based on the Geometrical Street Scattering Model

    Directory of Open Access Journals (Sweden)

    Nurilla Avazov

    2012-01-01

    Full Text Available We propose a wideband multiple-input multiple-output (MIMO car-to-car (C2C channel model based on the geometrical street scattering model. Starting from the geometrical model, a MIMO reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS and non-LOS (NLOS propagation environments. The proposed channel model assumes an infinite number of scatterers, which are uniformly distributed in two rectangular areas located on both sides of the street. Analytical solutions are presented for the space-time-frequency cross-correlation function (STF-CCF, the two-dimensional (2D space CCF, the time-frequency CCF (TF-CCF, the temporal autocorrelation function (ACF, and the frequency correlation function (FCF. An efficient sum-of-cisoids (SOCs channel simulator is derived from the reference model. It is shown that the temporal ACF and the FCF of the SOC channel simulator fit very well to the corresponding correlation functions of the reference model. To validate the proposed channel model, the mean Doppler shift and the Doppler spread of the reference model have been matched to real-world measurement data. The comparison results demonstrate an excellent agreement between theory and measurements, which confirms the validity of the derived reference model. The proposed geometry-based channel simulator allows us to study the effect of nearby street scatterers on the performance of C2C communication systems.

  6. Evaluation of RANS turbulence models for the simulation of channel flow

    OpenAIRE

    Hedlund, André

    2014-01-01

    The objective of this report is to investigate how RANS models perform on fully developed channel flow, for Re = 13 350, and the simulations are made with the open source software OpenFOAM. The velocity and turbulent kinetic energy profiles are compared with previously published DNS results. A short introduction to turbulence modelling is presented with focus on channel flow and the boundary layer. In total eleven models are evaluated, and the results are of varying quality. A convergence stu...

  7. Experimental analysis of the flow structure in the laboratory model of SOFC fuel cell channels

    International Nuclear Information System (INIS)

    In the presented paper a flow structure in the gas channel of planar SOFC fuel cell is presented. The model taken for analysis was constructed based on the channel geometry manufactured by SOFC Power company. The shape of a channel was rectangular filled with large number of obstacles which role is to divide the flow into segments with possibly homogenous velocity distribution. The model itself was constructed from Plexiglas and the reactant gases flow was modelled by water motion. To investigate and visualize the flow structures a PIV technique was applied. Three different flow rates were taken for investigations and the flow uniformity and time dependence was studied.

  8. Bayesian Statistical Inference in Ion-Channel Models with Exact Missed Event Correction.

    Science.gov (United States)

    Epstein, Michael; Calderhead, Ben; Girolami, Mark A; Sivilotti, Lucia G

    2016-07-26

    The stochastic behavior of single ion channels is most often described as an aggregated continuous-time Markov process with discrete states. For ligand-gated channels each state can represent a different conformation of the channel protein or a different number of bound ligands. Single-channel recordings show only whether the channel is open or shut: states of equal conductance are aggregated, so transitions between them have to be inferred indirectly. The requirement to filter noise from the raw signal further complicates the modeling process, as it limits the time resolution of the data. The consequence of the reduced bandwidth is that openings or shuttings that are shorter than the resolution cannot be observed; these are known as missed events. Postulated models fitted using filtered data must therefore explicitly account for missed events to avoid bias in the estimation of rate parameters and therefore assess parameter identifiability accurately. In this article, we present the first, to our knowledge, Bayesian modeling of ion-channels with exact missed events correction. Bayesian analysis represents uncertain knowledge of the true value of model parameters by considering these parameters as random variables. This allows us to gain a full appreciation of parameter identifiability and uncertainty when estimating values for model parameters. However, Bayesian inference is particularly challenging in this context as the correction for missed events increases the computational complexity of the model likelihood. Nonetheless, we successfully implemented a two-step Markov chain Monte Carlo method that we called "BICME", which performs Bayesian inference in models of realistic complexity. The method is demonstrated on synthetic and real single-channel data from muscle nicotinic acetylcholine channels. We show that parameter uncertainty can be characterized more accurately than with maximum-likelihood methods. Our code for performing inference in these ion channel

  9. Design, modeling, and analysis of multi-channel demultiplexer/demodulator

    Science.gov (United States)

    Lee, David D.; Woo, K. T.

    1991-01-01

    Traditionally, satellites have performed the function of a simple repeater. Newer data distribution satellite architectures, however, require demodulation of many frequency division multiplexed uplink channels by a single demultiplexer/demodulator unit, baseband processing and routing of individual voice/data circuits, and remodulation into time division multiplexed (TDM) downlink carriers. The TRW MCDD (Multichannel Demultiplexer/Multirate Demodulator) operates on a 37.4 MHz composite input signal. Individual channel data rates are either 64 Kbps or 2.048 Mbps. The wideband demultiplexer divides the input signal into 1.44 MHz segments containing either a single 2.048 Mbps channel or thirty two 64 Kbps channels. In the latter case, the narrowband demultiplexer further divides the single 1.44 MHz wideband channel into thirty two 45 KHz narrowband channels. With this approach the time domain Fast Fourier Transformation (FFT) channelizer processing capacity is matched well to the bandwidth and number of channels to be demultiplexed. By using a multirate demodulator fewer demodulators are required while achieving greater flexibility. Each demodulator can process a wideband channel or thirty two narrowband channels. Either all wideband channels, a mixture of wideband and narrowband channels, or all narrowband channels can be demodulated. The multirate demodulator approach also has lower nonrecurring costs since only one design and development effort is needed. TRW has developed a proof of concept (POC) model which fully demonstrates the signal processing fuctions of MCDD. It is capable of processing either three 2.048 Mbps channels or two 2.048 Mbps channels and thirty two 64 Kbps channels. An overview of important MCDD system engineering issues is presented as well as discussion on some of the Block Oriented System Simulation analyses performed for design verification and selection of operational parameters of the POC model. Systems engineering analysis of the POC

  10. Sound speed based patient-specific biomechanical modeling for registration of USCT volumes with X-ray mammograms

    Science.gov (United States)

    Hopp, T.; Stromboni, A.; Duric, N.; Zapf, M.; Gemmeke, H.; Ruiter, N. V.

    2013-03-01

    Ultrasound Computer Tomography is an upcoming imaging modality for early breast cancer detection. For evaluation of the method, comparison with the standard method X-ray mammography is of strongest interest. To overcome the significant differences in dimensionality and compression state of the breast, in earlier work a registration method based on biomechanical modeling of the breast was proposed. However only homogeneous models could be applied, i.e. inner structures of the breast were neglected. In this work we extend the biomechanical modeling of the breast by estimating patient-specific tissue parameters automatically from the speed of sound volume. Two heterogeneous models are proposed modeling a quadratic and an exponential relationship between speed of sound and tissue stiffness. The models were evaluated using phantom images and clinical data. The size of all lesions is better preserved using heterogeneous models, especially using an exponential relationship. The presented approach yields promising results and gives a physical justification to our registration method. It can be considered as a first step towards a realistic modeling of the breast.

  11. Modeling within- and across-channel processes in comodulation masking release

    DEFF Research Database (Denmark)

    Dau, Torsten; Piechowiak, Tobias; Ewert, Stephan D

    2013-01-01

    The relative contributions of within-channel and across-channel processes to perceptual comodulation masking release (CMR) were investigated in the framework of an auditory processing model. A generalized version of the computational auditory signal processing and perception model [CASP; Jepsen et...... al., J. Acoust. Soc. Am. 124, 422-438 (2008)] was used and extended by an across-channel modulation processing stage according to Piechowiak et al. [J. Acoust. Soc. Am. 121, 2111-2126 (2007)]. Five experimental paradigms were considered: CMR with a broadband noise masker as a function of the masker...... different mechanisms contribute to overall CMR in the considered conditions: (1) a within-channel process based on changes in the envelope characteristic due to the addition of the signal to the masker; (2) a within-channel process based on nonlinear peripheral processing of the OFB's envelope caused...

  12. A 3D Geometry-based Stochastic Model for 5G Massive MIMO Channels

    Directory of Open Access Journals (Sweden)

    Yi Xie

    2015-09-01

    Full Text Available Massive MIMO is one of the most promising technologies for the fifth generation (5G mobile communication systems. In order to better assess the system performance, it is essential to build a corresponding channel model accurately. In this paper, a three-dimension (3D two-cylinder regular-shaped geometry-based stochastic model (GBSM for non-isotropic scattering massive MIMO channels is proposed. Based on geometric method, all the scatters are distributed on the surface of a cylinder as equivalent scatters. Non-stationary property is that one antenna has its own visible area of scatters by using a virtual sphere. The proposed channel model is evaluated by comparing with the 3GPP 3D channel model [1]. The statistical properties are investigated. Simulation results show that close agreements are achieved between the characteristics of the proposed channel model and those of the 3GPP channel model, which justify the correctness of the proposed model. The model has advantages such as good applicability.

  13. Modeling and Eigenfrequency Analysis of Sound-Structure Interaction in a Rectangular Enclosure with Finite Element Method

    Directory of Open Access Journals (Sweden)

    Samira Mohamady

    2009-01-01

    Full Text Available Vibration of structures due to external sound is one of the main causes of interior noise in cavities like automobile, aircraft, and rotorcraft, which disturb the comfort of passengers. Accurate modelling of such phenomena is required in eigenfrequency analysis and in designing an active noise control system to reduce the interior noise. In this paper, the effect of periodic noise travelling into a rectangular enclosure is investigated with finite element method (FEM using COMSOL Multiphysics software. The periodic acoustic wave is generated by a point source outside the enclosure and propagated through the enclosure wall and excites an aluminium flexible panel clamped onto the enclosure. The behaviour of the transmission of sound into the cavity is investigated by computing the modal characteristics and the natural frequencies of the cavity. The simulation results are compared with previous analytical and experimental works for validation and an acceptable match between them were obtained.

  14. On Perturbation of Eigenvalues Embedded at Thresholds in a Two Channel Model

    Indian Academy of Sciences (India)

    Arne Jensen

    2002-02-01

    We present some results on the perturbation of eigenvalues embedded at thresholds in a two channel model Hamiltonian with a small off-diagonal perturbation. Examples are given of the various types of behavior of the eigenvalue under perturbation.

  15. On perturbation of eigenvalues embedded at thresholds in a two channel model

    DEFF Research Database (Denmark)

    Jensen, Arne

    2002-01-01

    We present some results on the perturbation of eigenvalues embedded at thresholds in a two channel model Hamiltonian with a small off-diagonal perturbation. Examples are given of the various types of behavior of the eigenvalue under perturbation....

  16. Hydraulic model with roughness coefficient updating method based on Kalman filter for channel flood forecast

    Directory of Open Access Journals (Sweden)

    Hong-jun BAO

    2011-03-01

    Full Text Available A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning’s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning’s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning’s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.

  17. Modeling delta growth and channel geometry on Wax Lake Delta, Louisiana. Preliminary results

    Science.gov (United States)

    Viparelli, E.; Czapiga, M. J.; Li, C.; Shaw, J. B.; Parker, G.

    2013-12-01

    A numerical model of delta growth, in which the distributary channels are assumed to have self-constructed their cross sections, is validated on Wax Lake Delta, Louisiana. As in previous laterally averaged models of delta growth, the delta is divided in a low slope delta top, a steep delta front and a low slope basement. The flow on the delta top is assumed steady, and a backwater formulation is implemented. Since one or more channels can actively transport water and sediment on the delta top during floods, we simplify the problem by assuming that the bed material is transported in one rectangular channel, with width and depth roughly equal to the sum of the active channel widths, and to the average depth of the active channels. The problem is characterized by one equation (i.e. the backwater equation) in two unknowns, the channel width and depth. Another equation is thus needed to close the problem. Under the assumptions that 1) the system is at bankfull flow, and 2) the Shields number in the channels is equal to its channel formative value, our closure relation is a channel-formative criterion. In particular, a recently derived relation to estimate the formative (bankfull) Shields number as a function of the friction slope is implemented. Recent field work on Wax Lake Delta shows that the distributary channels are incising into a relatively stiff basement. In our model we do not attempt to directly model channel incision, but we implicitly account for it with a modified formulation to compute the shoreline migration rate. In this formulation the bed material at the shoreline is trapped in the non-channelized portion of the delta front only. Measured and numerical shoreline migration rates, longitudinal profiles of delta elevation, and channel geometry, i.e. width and depth, are compared. In the relatively near future we plan to 1) use our model to estimate land-building potential of engineered diversions of the Mississippi River, and 2) couple the present model

  18. Non-Michaelis-Menten kinetics model for conductance of low-conductance potassium ion channels.

    Science.gov (United States)

    Tolokh, Igor S; Tolokh, Illya I; Cho, Hee Cheol; D'Avanzo, Nazzareno; Backx, Peter H; Goldman, Saul; Gray, C G

    2005-02-01

    A reduced kinetics model is proposed for ion permeation in low-conductance potassium ion channels with zero net electrical charge in the selectivity filter region. The selectivity filter is assumed to be the only conductance-determining part of the channel. Ion entry and exit rate constants depend on the occupancy of the filter due to ion-ion interactions. The corresponding rates are assumed slow relative to the rates of ion motion between binding sites inside the filter, allowing a reduction of the kinetics model of the filter by averaging the entry and exit rate constants over the states with a particular occupancy number. The reduced kinetics model for low-conductance channels is described by only three states and two sets of effective rate constants characterizing transitions between these states. An explicit expression for the channel conductance as a function of symmetrical external ion concentration is derived under the assumption that the average electrical mobility of ions in the selectivity filter region in a limited range of ion concentrations does not depend on these concentrations. The simplified conductance model is shown to provide a good description of the experimentally observed conductance-concentration curve for the low-conductance potassium channel Kir2.1, and also predicts the mean occupancy of the selectivity filter of this channel. We find that at physiological external ion concentrations this occupancy is much lower than the value of two ions observed for one of the high-conductance potassium channels, KcsA.

  19. Channel modelling and performance analysis of V2I communication systems in blind bend scattering environments

    KAUST Repository

    Chelli, Ali

    2014-01-01

    In this paper, we derive a new geometrical blind bend scattering model for vehicle-to- infrastructure (V2I) communications. The proposed model takes into account single-bounce and double- bounce scattering stemming from fixed scatterers located on both sides of a curved street. Starting from the geometrical blind bend model, the exact expression of the angle of departure (AOD) is derived. Based on this expression, the probability density function (PDF) of the AOD and the Doppler power spectrum are determined. Analytical expressions for the channel gain and the temporal autocorrelation function (ACF) are provided under non-line-of-sight (NLOS) conditions. Additionally, we investigate the impact of the position of transmitting vehicle relatively to the receiving road-side unit on the channel statistics. Moreover, we study the performance of different digital modulations over a sum of singly and doubly scattered (SSDS) channel. Note that the proposed V2I channel model falls under the umbrella of SSDS channels since the transmitted signal undergoes a combination of single-bounce and double-bounce scattering. We study some characteristic quantities of SSDS channels and derive expressions for the average symbol error probability of several modulation schemes over SSDS channels with and without diversity combining. The validity of these analytical expressions is confirmed by computer-based simulations.

  20. Morphology of Rain Water Channeling in Systematically Varied Model Sandy Soils

    Science.gov (United States)

    Wei, Yuli; Cejas, Cesare M.; Barrois, Rémi; Dreyfus, Rémi; Durian, Douglas J.

    2014-10-01

    We visualize the formation of fingered flow in dry model sandy soils under different rain conditions using a quasi-2D experimental setup and systematically determine the impact of the soil grain diameter and surface wetting properties on the water channeling phenomenon. The model sandy soils we use are random closely packed glass beads with varied diameters and surface treatments. For hydrophilic sandy soils, our experiments show that rain water infiltrates a shallow top layer of soil and creates a horizontal water wetting front that grows downward homogeneously until instabilities occur to form fingered flows. For hydrophobic sandy soils, in contrast, we observe that rain water ponds on the top of the soil surface until the hydraulic pressure is strong enough to overcome the capillary repellency of soil and create narrow water channels that penetrate the soil packing. Varying the raindrop impinging speed has little influence on water channel formation. However, varying the rain rate causes significant changes in the water infiltration depth, water channel width, and water channel separation. At a fixed rain condition, we combine the effects of the grain diameter and surface hydrophobicity into a single parameter and determine its influence on the water infiltration depth, water channel width, and water channel separation. We also demonstrate the efficiency of several soil water improvement methods that relate to the rain water channeling phenomenon, including prewetting sandy soils at different levels before rainfall, modifying soil surface flatness, and applying superabsorbent hydrogel particles as soil modifiers.

  1. RESEARCH ON SYSTEM DYNAMICS MODEL OF CONVEYANCE CAPACITY IN SYMMETRIC COMPOUND CHANNELS

    Institute of Scientific and Technical Information of China (English)

    YANG Ke-jun; CAO Shu-you; LIU Xing-nian

    2005-01-01

    Stage-discharge curves are particularly important in river basin management. For a compound channel, the stage-discharge curve is often difficult to be extrapolated to yield estimates of level for a given frequency of flow. By analyzing a large number of experimental data from Science and Engineering Research Council Flood Channel Facility (SERC-FCF) and applying system dynamics method, the authors established system dynamics model of conveyance capacity when rivers flow in an overbank mode, spilling onto the adjoining flood plain. The model was applied to a compound channel. And the corresponding simulated results are shown to attain high accurcy.

  2. Trends and Challenges in Wireless Channel Modeling for an Evolving Radio Access

    OpenAIRE

    Ferrand, Paul; Amara, Mustapha; Guillaud, Maxime; Valentin, Stefan

    2016-01-01

    With the advent of 5G, standardization and research are currently defining the next generation of the radio access. Considering the high constraints imposed by the future standards, disruptive technologies such as Massive MIMO and mmWave are being proposed. At the heart of this process are wireless channel models that now need to cover a massive increase in design parameters, a large variety of frequency bands, and heterogeneous deployments. This tutorial describes how channel models address ...

  3. A MATHEMATICAL MODEL OF NOISE IN THE MEASURING CHANNELS OF INTELLIGENT SYSTEMS

    OpenAIRE

    Volovich, G.; Solomin, E.; Topolskaya, I.; Topolsky, D.

    2014-01-01

    We propose a mathematical model describing quantization frequency selection in the measuring channels of intelligent systems depending on the parameters of noise. We consider internal and external sources of noise, seek the reasons for noise generation, justify the necessity of recording noise in the analog lines of measuring channels of intelligent systems. The parameters of our mathematical model of noise are: stationary white noise with normal distribution, an anti-aliasing bandwidth filte...

  4. A mathematical model of noise in the measuring channels of intelligent systems

    OpenAIRE

    Volovich, G. I.; SOLOMIN E.V.; TOPOLSKAYA I.G.; TOPOLSKY D.V.; Волович, Г. И.; Соломин, Е. В.; Топольская, И. Г.; Топольский, Д. В.

    2014-01-01

    We propose a mathematical model describing quantization frequency selection in the measuring channels of intelligent systems depending on the parameters of noise.We consider internal and external sources of noise, seek the reasons for noise generation, justify the necessity of recording noise in the analog lines of measuring channels of intelligent systems. The parameters of our mathematical model of noise are: stationary white noise with normal distribution, an anti-aliasing bandwidth lter,...

  5. Estuarine Bathymetric Digital Elevation Models (30 meter and 3 arc second resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Bathymetric Digital Elevation Models (DEM) were generated from original point soundings collected during hydrographic surveys conducted by the National Ocean...

  6. 声波层析成像在特大涌水地质区域探测中的应用%THE APPLICATION OF SOUND WAVE COMPUTERIZED TOMOGRAPHY TO THE GEOLOGICAL REGIONAL DETECTION IN AN EXTRA LARGE WATER GUSHING CHANNEL

    Institute of Scientific and Technical Information of China (English)

    陈宗刚; 李平宏; 张建成; 林孝城; 薛有平

    2013-01-01

    This authors introduce the basic principle,data acquisition and processing method of sound wave computerized tomography (sound wave CT) ,and then makes a detailed discussion on the applied effect of sound wave CT in geological regional detection of an extra large water gushing channel in a certain hydropower station diversion tunnel. Practice shows that sound wave CT can effectively remedy the limitation of single-hole sound wave test, and the result images of sound wave CT describe vividly the position and scale of the gushing channel of ground water. Thus, sound wave CT can successfully detect similar geological problems and provide scientific basis for the follow-up construction design.%介绍了声波层析成像(声波CT)的基本原理、数据采集与处理方法,并结合工程实例对声波CT在某水电站涌水通道探测的应用效果作了较为深入的探讨.实践表明,声波CT能够有效弥补单孔声波检测工作的局限性,成果图像形象地描述了地下水的涌水通道位置及规模,可较好地探测该类地质问题,为后续施工设计提供科学依据.

  7. Entrance channel effect with stable and radioactive beams using dynamical cluster decay model

    International Nuclear Information System (INIS)

    The decay of hot and rotating 172Yb*, formed in two entrance channels 124Sn + 48Ca and 132Sn + 40Ca, is studied using the dynamical cluster-decay model. The effect of entrance channel, deformations (up to β2), barrier modification and fusion enhancement are addressed. The decay pattern of compound system, formed in different channels at comparable energy around the barrier, shows change in magnitude with structure remains almost same. There is an increase in the fusion probability with decrease in barrier modification, which leads to fusion enhancement at low energies. The higher ℓ values are contributing for 132Sn + 40Ca channel at lower energies as compare to 124Sn + 48Ca. It is inferred that with the use of stable and radioactive beam, forming same compound nucleus, the entrance channel dependence changes with the excitation energy

  8. Entrance channel effect with stable and radioactive beams using dynamical cluster decay model

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Raj, E-mail: rajkumarfzr@gmail.com [Dipartimento di Fisica “Galileo Galilei” and INFN, University of Padova, Padova-35131 (Italy); Jain, Deepika [School of Physics and Material Science, Thapar University, Patiala-147004 (India)

    2014-09-15

    The decay of hot and rotating {sup 172}Yb*, formed in two entrance channels {sup 124}Sn + {sup 48}Ca and {sup 132}Sn + {sup 40}Ca, is studied using the dynamical cluster-decay model. The effect of entrance channel, deformations (up to β{sub 2}), barrier modification and fusion enhancement are addressed. The decay pattern of compound system, formed in different channels at comparable energy around the barrier, shows change in magnitude with structure remains almost same. There is an increase in the fusion probability with decrease in barrier modification, which leads to fusion enhancement at low energies. The higher ℓ values are contributing for {sup 132}Sn + {sup 40}Ca channel at lower energies as compare to {sup 124}Sn + {sup 48}Ca. It is inferred that with the use of stable and radioactive beam, forming same compound nucleus, the entrance channel dependence changes with the excitation energy.

  9. A Novel Statistical Channel Model for Turbulence-Induced Fading in Free-Space Optical Systems

    CERN Document Server

    Aminikashani, Mohammadreza; Kavehrad, Mohsen

    2015-01-01

    In this paper, we propose a new probability distribution function which accurately describes turbulence-induced fading under a wide range of turbulence conditions. The proposed model, termed Double Generalized Gamma (Double GG), is based on a doubly stochastic theory of scintillation and developed via the product of two Generalized Gamma (GG) distributions. The proposed Double GG distribution generalizes many existing turbulence channel models and provides an excellent fit to the published plane and spherical waves simulation data. Using this new statistical channel model, we derive closed form expressions for the outage probability and the average bit error as well as corresponding asymptotic expressions of free-space optical communication systems over turbulence channels. We demonstrate that our derived expressions cover many existing results in the literature earlier reported for Gamma-Gamma, Double-Weibull and K channels as special cases.

  10. HF channel modeling for real-time packet transmission

    Science.gov (United States)

    Rostami, Mehdi; Angeja, Joao; Tavares, Joao; Navarro, Antonio

    2003-07-01

    The recent rapid growth of multimedia communications has efficiently allowed delivering different services, formats and contents over an enormous variety of digital networks with IP acting as an integration protocol. The main objective of this research work is to evaluate the performance of an high frequency (HF) wireless network for transporting multimedia services according to UDP/IP protocol stack. Besides, allowing civil/amateur communications, HF bands are also used for long distance wireless military communications. Therefore, our work is based on NATO Link and Physical layer standards, STANAG 5066 and STANAG 4539, respectively. A typical transmission bandwidth is about 3 kHz resulting in a varying bit rate in the range between 75 and 12800 bps. This very low bit rate by itself imposes serious challenges for reliable real time multimedia communications. This paper discusses optimal combinations of channel coders, modulators and packet sizes in order to achieve the greatest throughput in function of the signal-to-noise ratio and HF channel conditions.

  11. Practical and Simple Wireless Channel Models for Use in Multipolarized Antenna Systems

    Directory of Open Access Journals (Sweden)

    KwangHyun Jeon

    2014-01-01

    Full Text Available The next-generation wireless systems are expected to support data rates of more than 100 Mbps in outdoor environments. In order to support such large payloads, a polarized antenna may be employed as one of the candidate technologies. Recently, the third generation partnership standards bodies (3GPP/3GPP2 have defined a cross-polarized channel model in SCM-E for MIMO systems; however, this model is quite complex since it considers a great many channel-related parameters. Furthermore, the SCM-E channel model combines the channel coefficients of all the polarization links into one complex output, making it impossible to exploit the MIMO spatial multiplexing or diversity gains in the case of employing polarized antenna at transmitter and receiver side. In this paper, we present practical and simple 2D and 3D multipolarized multipath channel models, which take into account both the cross-polarization discrimination (XPD and the Rician factor. After verifying the proposed channel models, the BER and PER performances and throughput using the EGC and MRC combining techniques are evaluated in multipolarized antenna systems.

  12. The Sounds of Sentences: Differentiating the Influence of Physical Sound, Sound Imagery, and Linguistically Implied Sounds on Physical Sound Processing.

    Science.gov (United States)

    Dudschig, Carolin; Mackenzie, Ian Grant; Strozyk, Jessica; Kaup, Barbara; Leuthold, Hartmut

    2016-10-01

    Both the imagery literature and grounded models of language comprehension emphasize the tight coupling of high-level cognitive processes, such as forming a mental image of something or language understanding, and low-level sensorimotor processes in the brain. In an electrophysiological study, imagery and language processes were directly compared and the sensory associations of processing linguistically implied sounds or imagined sounds were investigated. Participants read sentences describing auditory events (e.g., "The dog barks"), heard a physical (environmental) sound, or had to imagine such a sound. We examined the influence of the 3 sound conditions (linguistic, physical, imagery) on subsequent physical sound processing. Event-related potential (ERP) difference waveforms indicated that in all 3 conditions, prime compatibility influenced physical sound processing. The earliest compatibility effect was observed in the physical condition, starting in the 80-110 ms time interval with a negative maximum over occipital electrode sites. In contrast, the linguistic and the imagery condition elicited compatibility effects starting in the 180-220 ms time window with a maximum over central electrode sites. In line with the ERPs, the analysis of the oscillatory activity showed that compatibility influenced early theta and alpha band power changes in the physical, but not in the linguistic and imagery, condition. These dissociations were further confirmed by dipole localization results showing a clear separation between the source of the compatibility effect in the physical sound condition (superior temporal area) and the source of the compatibility effect triggered by the linguistically implied sounds or the imagined sounds (inferior temporal area). Implications for grounded models of language understanding are discussed.

  13. The Sounds of Sentences: Differentiating the Influence of Physical Sound, Sound Imagery, and Linguistically Implied Sounds on Physical Sound Processing.

    Science.gov (United States)

    Dudschig, Carolin; Mackenzie, Ian Grant; Strozyk, Jessica; Kaup, Barbara; Leuthold, Hartmut

    2016-10-01

    Both the imagery literature and grounded models of language comprehension emphasize the tight coupling of high-level cognitive processes, such as forming a mental image of something or language understanding, and low-level sensorimotor processes in the brain. In an electrophysiological study, imagery and language processes were directly compared and the sensory associations of processing linguistically implied sounds or imagined sounds were investigated. Participants read sentences describing auditory events (e.g., "The dog barks"), heard a physical (environmental) sound, or had to imagine such a sound. We examined the influence of the 3 sound conditions (linguistic, physical, imagery) on subsequent physical sound processing. Event-related potential (ERP) difference waveforms indicated that in all 3 conditions, prime compatibility influenced physical sound processing. The earliest compatibility effect was observed in the physical condition, starting in the 80-110 ms time interval with a negative maximum over occipital electrode sites. In contrast, the linguistic and the imagery condition elicited compatibility effects starting in the 180-220 ms time window with a maximum over central electrode sites. In line with the ERPs, the analysis of the oscillatory activity showed that compatibility influenced early theta and alpha band power changes in the physical, but not in the linguistic and imagery, condition. These dissociations were further confirmed by dipole localization results showing a clear separation between the source of the compatibility effect in the physical sound condition (superior temporal area) and the source of the compatibility effect triggered by the linguistically implied sounds or the imagined sounds (inferior temporal area). Implications for grounded models of language understanding are discussed. PMID:27473463

  14. Modeling and Simulation of MIMO Mobile-to-Mobile Wireless Fading Channels

    Directory of Open Access Journals (Sweden)

    Gholamreza Bakhshi

    2012-01-01

    Full Text Available Analysis and design of multielement antenna systems in mobile fading channels require a model for the space-time cross-correlation among the links of the underlying multipleinput multiple-output (MIMO Mobile-to-Mobile (M-to-M communication channels. In this paper, we propose the modified geometrical two-ring model, a MIMO channel reference model for M-to-M communication systems. This model is based on the extension of single-bounce two-ring scattering model for flat fading channel under the assumption that the transmitter and the receiver are moving. Assuming single-bounce scattering model in both isotropic and nonisotropic environment, a closed-form expression for the space-time cross-correlation function (CCF between any two subchannels is derived. The proposed model provides an important framework in M-to-M system design, where includes many existing correlation models as special cases. Also, two realizable statistical simulation models are proposed for simulating both isotropic and nonisotropic reference model. The realizable simulation models are based on Sum-of-Sinusoids (SoS simulation model. Finally, the correctness of the proposed simulation models is shown via different simulation scenarios.

  15. Breath sounds

    Science.gov (United States)

    Causes of abnormal breath sounds may include: Acute bronchitis Asthma Bronchiectasis Chronic bronchitis Congestive heart failure Emphysema Interstitial lung disease Foreign body obstruction of the airway Pneumonia Pulmonary edema Tracheobronchitis

  16. An automated method for generating analogic signals that embody the Markov kinetics of model ionic channels.

    Science.gov (United States)

    Luchian, Tudor

    2005-08-30

    In this work we present an automated method for generating electrical signals which reflect the kinetics of ionic channels that have custom-tailored intermediate sub-states and intermediate reaction constants. The concept of our virtual single-channel waveform generator makes use of two software platforms, one for the numerical generation of single channel traces stemming from a pre-defined model and another for the digital-to-analog conversion of such numerical generated single channel traces. This technique of continuous generation and recording of the activity of a model ionic channel provides an efficient protocol to teach neophytes in the field of single-channel electrophysiology about its major phenomenological facets. Random analogic signals generated by using our technique can be successfully employed in a number of applications, such us: assisted learning of the single-molecule kinetic investigation via electrical recordings, impedance spectroscopy, the evaluation of linear frequency response of neurons and the study of stochastic resonance of ion channels. PMID:16054511

  17. Analysis of the stochastic channel model by Saleh & Valenzuela via the theory of point processes

    DEFF Research Database (Denmark)

    Jakobsen, Morten Lomholt; Pedersen, Troels; Fleury, Bernard Henri

    2012-01-01

    In this paper we revisit the classical channel model by Saleh & Valenzuela via the theory of spatial point processes. By reformulating this model as a particular point process and by repeated application of Campbell’s Theorem we provide concise and elegant access to its overall structure and unde......In this paper we revisit the classical channel model by Saleh & Valenzuela via the theory of spatial point processes. By reformulating this model as a particular point process and by repeated application of Campbell’s Theorem we provide concise and elegant access to its overall structure...

  18. Integrated Modeling and Decision-Support System for Water Management in the Puget Sound Basin: Snow Caps to White Caps

    Energy Technology Data Exchange (ETDEWEB)

    Copping, Andrea E.; Yang, Zhaoqing; Voisin, Nathalie; Richey, Jeff; Wang, Taiping; Taira, Randal Y.; Constans, Michael; Wigmosta, Mark S.; Van Cleve, Frances B.; Tesfa, Teklu K.

    2013-12-31

    Final Report for the EPA-sponsored project Snow Caps to White Caps that provides data products and insight for water resource managers to support their predictions and management actions to address future changes in water resources (fresh and marine) in the Puget Sound basin. This report details the efforts of a team of scientists and engineers from Pacific Northwest National Laboratory (PNNL) and the University of Washington (UW) to examine the movement of water in the Snohomish Basin, within the watershed and the estuary, under present and future conditions, using a set of linked numerical models.

  19. Pitch Based Sound Classification

    OpenAIRE

    Nielsen, Andreas Brinch; Hansen, Lars Kai; Kjems, U.

    2006-01-01

    A sound classification model is presented that can classify signals into music, noise and speech. The model extracts the pitch of the signal using the harmonic product spectrum. Based on the pitch estimate and a pitch error measure, features are created and used in a probabilistic model with soft-max output function. Both linear and quadratic inputs are used. The model is trained on 2 hours of sound and tested on publicly available data. A test classification error below 0.05 with 1 s classif...

  20. EPS models of AM-FM vocoder output for new sounds generations

    OpenAIRE

    Timoney, Joseph; Lysaght, Thomas

    2001-01-01

    The Phase Vocoder [1] was originally introduced as an alternative approach to speech coding but has won much greater acceptance among the music community as a tool both for sound analysis and composition [2]. Although dormant for some time, there has been a resurgence of interest in AM-FM speech signal descriptions in the last ten years [3], [4]. With the intention of building on some of the new ideas proffered, the aim of this work is to first consider their application to musical signals...

  1. Correlated voltage probe model of relaxation in two Coulomb-coupled edge channels

    Science.gov (United States)

    Nigg, Simon E.

    2016-01-01

    A phenomenological correlated voltage probe model is introduced to mimic the effects of inelastic scattering between particles in different conduction channels of a phase coherent conductor. As an illustration, the non-equilibrium distribution functions of two noisy co-propagating chiral edge channels of the integer quantum Hall effect are calculated and compared with recent experiments. The method is further applied to calculate the linear response current noise through an interacting Mach-Zehnder interferometer.

  2. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

    OpenAIRE

    Javier Cervera; Antonio Alcaraz; Salvador Mafe

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) th...

  3. Reprint of : Correlated voltage probe model of relaxation in two Coulomb-coupled edge channels

    Science.gov (United States)

    Nigg, Simon E.

    2016-08-01

    A phenomenological correlated voltage probe model is introduced to mimic the effects of inelastic scattering between particles in different conduction channels of a phase coherent conductor. As an illustration, the non-equilibrium distribution functions of two noisy co-propagating chiral edge channels of the integer quantum Hall effect are calculated and compared with recent experiments. The method is further applied to calculate the linear response current noise through an interacting Mach-Zehnder interferometer.

  4. DEPTH-INTEGRATED MODELING FOR AGGRADING/DEGRADING MOBILE CHANNELS I: MODEL DEVELOPMENT

    Institute of Scientific and Technical Information of China (English)

    En-Tian LIN; Chih-Tsung HSU; Keh-Chia YEH

    2006-01-01

    A depth-integrated model has been developed to simulate the alluvial process of channel bed under overloading and under-loading sediment discharge conditions. The hydrodynamic sub-model based on the explicit-finite-analytic method is used to obtain the flow field. Then the sediment transport modes, including the bed-load and suspended load, are modeled with the aid of the empirically auxiliary relations. In the depth-integrated model, the sediment exchange rate is treated as a source term specified at the reference level, rather than a boundary condition as usually adopted in vertical 2-D or 3-D models. The deposition or erosion rate of the bed is then determined by comparing the flow-laden suspended-sediment concentration profile against the equilibrium concentration profile, and their difference is used to compute the sediment exchange rate for a given time interval. Assessment of the good accuracy of the proposed model is demonstrated by using van Rijn's (1981) experiment for the case of clear water passing a movable bed. In the companion paper, the verification and the field application of the proposed model are presented.

  5. Investigation of Channel Modeling and Simulation of OFDM Based Communication Near Northern Regions of Arabian Sea

    Directory of Open Access Journals (Sweden)

    Rehan Khan

    2013-02-01

    Full Text Available Wideband nature of oceanic channel when dealing with multicarrier acoustic subcarriers introduces severe Doppler shifts, little variations may cause overlapping of subcarriers such that entire signal can get completely distorted. Therefore, one of the major problems in OFDM based underwater acoustic communication is the sensitive nature of wideband acoustic subcarriers. In this study, Bellhop beam tracing is used to model two regions in the north of Arabian Sea and the two-step receiver algorithm is used over these channel models. Multipath with delay channel model is obtained using the Bellhop ray tracing algorithm while random Doppler shift is induced in MATLAB on each block and also in the complete OFDM packet. In the first step, resembling converts a wideband problem in to narrowband problem and in the second step; high resolution Carrier Offset Frequency (CFO tracking compensates the residual Doppler. Cyclic Prefix (CP OFDM scheme based on block-by-block processing is deliberated here for fast varying channel. In the proposed algorithm, null subcarriers are facilitated for Doppler removal while pilot bits are used for Least Square (LS channel estimation. Simulation on MATLAB is carried out on both channels, i.e., near Gawadar Coast and Karachi Harbor; satisfactory results are achieved in terms Low Bit Error Rates (BER even in high relative speed between transmitter and receiver. These results further suggested and make convinced for the experimental test/ trials, specifically in the region of north Arabian Sea.

  6. Unidentified Sounds

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob

    2015-01-01

    This article investigates how urban spaces and its noises are approached by radio reporters in the first decades of public radio production in Denmark. Focussing on the period before reel tape was incorporated in production by late 1940es, I ask how urban space and urban sounds are heard, context......This article investigates how urban spaces and its noises are approached by radio reporters in the first decades of public radio production in Denmark. Focussing on the period before reel tape was incorporated in production by late 1940es, I ask how urban space and urban sounds are heard......, contextualised and conceptualised in an era of transmission. Observing that urban sounds until late 1930es are rarely heard in Danish radio compared to German and English broadcasting, I argue that an urban and auditory aesthetics incorporating noise, heterogeneity and unpredictability did not really develop in...... the parasite I analyse such techniques as ways of distinguishing between noise and meaningful sounds, and ultimately show how such ventures constituted auditory responses to modernity and let organised sound enter the public sphere....

  7. An Efficient Channel Model for OFDM and Time Domain Single Carrier Transmission Using Impulse Responses

    Directory of Open Access Journals (Sweden)

    Tariq Jamil Saifullah Khanzada

    2012-01-01

    Full Text Available The OFDM (Orthogonal Frequency Division Multiplexing is well-known, most utilized wideband communication technique of the current era. SCT (Single Carrier Transmission provides equivalent performance in time domain while decision equalizer is implemented in frequency domain. SCT annihilates the ICT (Inter Carrier Interference and the PAPR (Peak to Average Power Ratio which is inherent to OFDM and degrades its performance in time varying channels. An efficient channel model is presented in this contribution, to implement OFDM and SCT in time domain using impulse responses. Both OFDM and SCT models are derived dialectically to model the channel impulse responses. Our model enhances the performance of time domain SCT compared with OFDM and subsides the PAPR and ICI problems of OFDM. SCT is implemented at symbol level contained in blocks. Simulation results implementing Digital Radio Monadiale (DRM assert the performance gain of SCT over OFDM.

  8. A two-dimensional analytical model for short channel junctionless double-gate MOSFETs

    Science.gov (United States)

    Jiang, Chunsheng; Liang, Renrong; Wang, Jing; Xu, Jun

    2015-05-01

    A physics-based analytical model of electrostatic potential for short-channel junctionless double-gate MOSFETs (JLDGMTs) operated in the subthreshold regime is proposed, in which the full two-dimensional (2-D) Poisson's equation is solved in channel region by a method of series expansion similar to Green's function. The expression of the proposed electrostatic potential is completely rigorous and explicit. Based on this expression, analytical models of threshold voltage, subthreshold swing, and subthreshold drain current for JLDGMTs were derived. Subthreshold behavior was studied in detail by changing different device parameters and bias conditions, including doping concentration, channel thickness, gate length, gate oxide thickness, drain voltage, and gate voltage. Results predicted by all the analytical models agree well with numerical solutions from the 2-D simulator. These analytical models can be used to investigate the operating mechanisms of nanoscale JLDGMTs and to optimize their device performance.

  9. A vehicle-to-infrastructure channel model for blind corner scattering environments

    KAUST Repository

    Chelli, Ali

    2013-09-01

    In this paper, we derive a new geometrical blind corner scattering model for vehicle-to-infrastructure (V2I) communications. The proposed model takes into account single-bounce and double-bounce scattering stemming from fixed scatterers located on both sides of the curved street. Starting from the geometrical blind corner model, the exact expression of the angle of departure (AOD) is derived. Based on this expression, the probability density function (PDF) of the AOD and the Doppler power spectrum are determined. Analytical expressions for the channel gain and the temporal autocorrelation function (ACF) are provided under non-line-of-sight (NLOS) conditions. Moreover, we investigate the impact of the position of transmitting vehicle relatively to the receiving road-side unit on the channel statistics. The proposed channel model is useful for the design and analysis of future V2I communication systems. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.

  10. Modeling the Effects of Connecting Side Channels to the Long Tom River, Oregon

    Science.gov (United States)

    Appleby, C.; McDowell, P. F.

    2015-12-01

    The lower Long Tom River is a heavily managed, highly modified stream in the southwestern Willamette Valley with many opportunities for habitat improvements and river restoration. In the 1940s and 1950s, the US Army Corps of Engineers dramatically altered this river system by constructing the Fern Ridge Dam and three, large drop structures, converting the River from a highly sinuous channel to a straight, channelized stream that is interrupted by these grade control structures, and removed the majority of the riparian vegetation. As a result, juvenile spring Chinook salmon are no longer found in the Watershed and the local population of coastal cutthroat trout face limited aquatic habitat. When the river was channelized, long sections of the historical channel were left abandoned on the floodplain. Reconnecting these historical channels as side channels may improve the quality and quantity of aquatic habitat and could allow fish passage around current barriers. However, such construction may also lead to undesirable threats to infrastructure and farmland. This study uses multiple HEC-RAS models to determine the impact of reconnecting two historical channels to the lower Long Tom River by quantifying the change in area of flood inundation and identifying infrastructure in jeapordy given current and post-restoration conditions for 1.5, 5, 10, and 25-year flood discharges. Bathymetric data from ADCP and RTK-GPS surveys has been combined with LiDAR-derived topographic data to create continuous elevation models. Several types of side channel connections are modeled in order to determine which type of connection will result in both the greatest quantity of accessible habitat and the fewest threats to public and private property. In the future, this study will also consider the change in the quantity of physical salmonid habitat and map the areas prone to sedimentation and erosion using CEASAR and PHABSIM tools.

  11. $2\\pi$ production in the Giessen coupled-channel model

    CERN Document Server

    Shklyar, V; Mosel, U

    2014-01-01

    We present a coupled-channel Lagrangian approach (GiM) to describe the $\\pi N \\to \\pi N$, $2\\pi N$ scattering in the resonance energy region. The $2\\pi N$ production has been significantly improved by using the isobar approximation with $\\sigma N$ and $\\pi \\DDelta$ in the intermediate state. The three-body unitarity is maintained up to interference pattern between the isobar subchannels. The scattering amplitudes are obtained as a solution of the Bethe-Salpeter equation in the $K$ matrix approximation. As a first application we perform a partial wave analysis of the $\\pi N \\to \\pi N$, $\\pi^0\\pi^0 N$ reactions in the Roper resonance region. We obtain $R_{\\sigma N}(1440)=27^{+4}_{-9}$\\,\\% and $R_{\\sigma N}(1440)=12^{+5}_{-3}$\\,\\% for the $\\sigma N$ and $\\pi \\DDelta$ decay branching ratios of $\\NN(1440)$ respectively. The extracted $\\pi N$ inelasticities and reaction amplitudes are consistent with the results from other groups.

  12. On the crucial features of a single-file transport model for ion channels

    CERN Document Server

    Liang, Kuo Kan

    2013-01-01

    It has long been accepted that the multiple-ion single-file transport model is appropriate for many kinds of ion channels. However, most of the purely theoretical works in this field did not capture all of the important features of the realistic systems. Nowadays, large-scale atomic-level simulations are more feasible. Discrepancy between theories, simulations and experiments are getting obvious, enabling people to carefully examine the missing parts of the theoretical models and methods. In this work, it is attempted to find out the essential features that such kind of models should possess, in order that the physical properties of an ion channel be adequately reflected.

  13. Discrete-Time Block Models for Transmission Line Channels: Static and Doubly Selective Cases

    CERN Document Server

    Galli, Stefano

    2011-01-01

    Most methodologies for modeling Transmission Line (TL) based channels define the input-output relationship in the frequency domain (FD) and handle the TL resorting to a two-port network (2PN) formalism. These techniques have not yet been formally mapped into a discrete-time (DT) block model, which is useful to simulate and estimate the channel response as well as to design optimal precoding strategies. TL methods also fall short when they are applied to Time Varying (TV) systems, such as the power line channel. The objective of this paper is to establish if and how one can introduce a DT block model for the Power Line Channel. We prove that it is possible to use Lifting and Trailing Zeros (L&TZ) techniques to derive a DT block model that maps the TL-based input-output description directly in the time domain (TD) block channel model. More specifically, we find an interesting relationship between the elements of an ABCD matrix, defined in the FD, and filtering kernels that allow an elegant representation of...

  14. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    CERN Document Server

    Czegledi, Cristian B; Agrell, Erik; Johannisson, Pontus

    2015-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts. The model is described in the Jones, Stokes and real 4-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future optical systems, which to a higher and higher degree rely on transmission and detection on both polarizations jointly using sophisticated digital signal processing. Such analysis cannot be carried out using the more rudimentary polarization drift models in use today, which only account for deterministic effects. The proposed polarization drift model is the first of its kind and will likely be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.

  15. A mixed 3D-Shell analytical model for the prediction of sound transmission through sandwich cylinders

    Science.gov (United States)

    Magniez, Julien; Chazot, Jean-Daniel; Hamdi, Mohamed Ali; Troclet, Bernard

    2014-09-01

    The sound transmission through an infinite multilayer cylinder composed of orthotropic skins and an isotropic polymer core is calculated analytically. The motions of the two thin orthotropic skins are described with the first-order shear deformation theory while the isotropic core is modeled with the three-dimensional elasticity theory. The polymer core transfer matrix relating the displacements and the stresses at the two common interfaces between the core and the skins is first calculated. The coupling of the two skins is then made using the modal transfer matrix of the core, leading to the global dynamic equilibrium of the multilayer cylinder. The sound Transmission Loss (TL) of the cylinder excited by an acoustic plane wave is finally calculated. Our results are compared with results published recently in the literature. Excellent agreement is observed for thin cores where the three layers vibrate in phase in the radial direction. The usefulness of the three-dimensional model is demonstrated for a thick and soft core in the higher frequency domain where the skins are vibrating out of phase with a relative displacement in the radial direction. Finally, a parametric study is conducted to demonstrate the influence of the damping of each layer and some observations are made on the shear and compressional strain energies of each layer.

  16. A field experiment and numerical modeling of a tracer at a gravel beach in Prince William Sound, Alaska

    Science.gov (United States)

    Guo, Qiaona; Li, Hailong; Boufadel, Michel C.; Liu, Jin

    2014-12-01

    Oil from the 1989 Exxon Valdez oil spill persists in many gravel beaches in Prince William Sound (Alaska, USA), despite great remedial efforts. A tracer study using lithium at a gravel beach on Knight Island, Prince William Sound, during the summer of 2008 is reported. The tracer injection and transport along a transect were simulated using the two-dimensional numerical model MARUN. Model results successfully reproduced the tracer concentrations observed at wells along the transect. A sensitivity analysis revealed that the estimated parameters are well determined. The simulated spatial distribution of tracer indicated that nutrients applied along the transect for bioremediation purposes would be washed to the sea very quickly (within a semi-diurnal tidal cycle) by virtue of the combination of the two-layered beach structure, the tidal fluctuation and the freshwater flow from inland. Thus, pore-water samples in the transect were found to be clean due to factors other than bioremediation. This may explain why the oil did not persist within the transect.

  17. Modeling water droplet condensation and evaporation in DNS of turbulent channel flow

    NARCIS (Netherlands)

    Russo, E.; Kuerten, J.G.M.; Geld, van der C.W.M.; Geurts, B.J.

    2011-01-01

    In this paper a point particle model for two-way coupling in water droplet-laden incompressible turbulent flow of air is proposed. The model is based on conservation laws and semi-empirical correlations. It has been implemented and tested in a DNS code based for turbulent channel flow with an Euleri

  18. THREE-DIMENSIONAL NUMERICAL MODELLING OF SUBMERGED DIKE ALIGNMENT IN CURVED ESTUARINE CHANNEL

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jin-hai; LIU Ying-qi; YAN Yi-xin; ZHU Yu-liang

    2005-01-01

    Submerged dikes were frequently built in curved estuarine channels to improve navigational conditions. A three-dimensional numerical model of tidal motions was developed to simulate flows through the submerged dike alignment in curved estuarine reach of complex bathymetry on the basis of satisfactory calibrations. Through the analysis of the morphological characteristics of the curved channel of the Huangpu River mouth in the Yangtze River Delta, a submerged dike alignment project was examined. The effect of the navigation channel improvement project and its influence on the flow regimes, the navigational conditions, the flood control and the operating conditions of harbours within the adjacent water area were evaluated, and the technical feasibility of the navigation channel improvement scheme was demonstrated.

  19. Survey of Channel and Radio Propagation Models for Wireless MIMO Systems

    Directory of Open Access Journals (Sweden)

    A. Burr

    2007-02-01

    Full Text Available This paper provides an overview of the state-of-the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models.

  20. Survey of Channel and Radio Propagation Models for Wireless MIMO Systems

    Directory of Open Access Journals (Sweden)

    Kyösti P

    2007-01-01

    Full Text Available This paper provides an overview of the state-of-the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models.

  1. Computing characterizations of drugs for ion channels and receptors using Markov models

    CERN Document Server

    Tveito, Aslak

    2016-01-01

    Flow of ions through voltage gated channels can be represented theoretically using stochastic differential equations where the gating mechanism is represented by a Markov model. The flow through a channel can be manipulated using various drugs, and the effect of a given drug can be reflected by changing the Markov model. These lecture notes provide an accessible introduction to the mathematical methods needed to deal with these models. They emphasize the use of numerical methods and provide sufficient details for the reader to implement the models and thereby study the effect of various drugs. Examples in the text include stochastic calcium release from internal storage systems in cells, as well as stochastic models of the transmembrane potential. Well known Markov models are studied and a systematic approach to including the effect of mutations is presented. Lastly, the book shows how to derive the optimal properties of a theoretical model of a drug for a given mutation defined in terms of a Markov model.

  2. A view on sound: investigating noise problems from the Rotterdam Port area using a meteorological-acoustical model

    NARCIS (Netherlands)

    Berg, F.H.A. van den; Eerden, F.J.M. van der

    2009-01-01

    The impact of industrial sound from the Europort/Maasvlakte area towards the city of Oostvoorne was investigated. This project “Geluid in Beeld” (A View on Sound) was initiated by The Port of Rotterdam, DCMR, EMO and ECT. This paper presents the comparison of the calculated sound propagation results

  3. Sound Settlements

    DEFF Research Database (Denmark)

    Mortensen, Peder Duelund; Hornyanszky, Elisabeth Dalholm; Larsen, Jacob Norvig;

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice......Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  4. Application of a simple space-time averaged porous media model to flow in densely vegetated channels

    NARCIS (Netherlands)

    Hoffmann, M.R.

    2004-01-01

    Traditional flow modeling in open channels uses time-averaged turbulence models. These models are valid in clear fluid, but not if dense obstructions are present in the flow field. In this article we show that newly developed flow models can describe open channel flow as flow in a porous medium. Cle

  5. Comparison of Channel Segregation Formation in Model Alloys and Steels via Numerical Simulations

    Science.gov (United States)

    Cao, Y. F.; Chen, Y.; Li, D. Z.; Liu, H. W.; Fu, P. X.

    2016-06-01

    In the current study, the evolutions of channel segregations in several alloy systems, such as the typically used model alloys ( e.g., Ga-In, Sn-Pb, Sn-Bi, Al-Cu, and Ni-based superalloy) and some special steels, are numerically simulated in a cavity solidified unidirectionally. The simulations are based on a modified continuum macrosegregation model with an extension to the multicomponent systems. The results of model alloys and steels indicate that when the thermosolutal convection is strong enough, flow instability occurs, which in turn destabilizes the mushy zone. Subsequently, the channel segregation forms with the continuous interaction between solidification and flow. The formation behavior and severity of channel segregations in various systems are different owing to their distinct melt convection strengths and solidification natures. In the current simulations, channels are apparent for model alloys with high content of solutes, whereas they are slight in some special steels, such as 27SiMn steel, and totally disappear in carbon steels. These occurrence features of channel segregation in simulations of steels are consistent with the analyses by a modified Rayleigh number associated with alloying elements, and both outcomes are well supported by the fully sectioned steel ingots in experiments.

  6. Simulation of Cognitive Radio System Applying Different Wireless Channel Models

    Directory of Open Access Journals (Sweden)

    Mohamed Shalaby

    2013-04-01

    Full Text Available Cognitive radio is an emerging technology, which aims to upgrade the spectrum utilization by allowing thesecondary users to operate at the spectrum bands vacated by the primary users. A cognitive radio systemmodel was simulated and the performance of the energy detector was evaluated by using different wirelesschannel models. These models include Additive White Gaussian Noise (AWGN model, Rayleigh fadingmodel, and Rician fading model. The simulation results show that by increasing the signal to noise ratio,the detection capability of the energy detector can be improved and the false alarm probability and themissed detection probability can be reduced. Moreover, the line of sight path strength of the Rician fadinghas a great effect on the energy detector performance. It was observed that, the line of sight path strength(k of 20 can save the signal power by 40 dB over a single path transmission and 25 dB over a multipathtransmission.

  7. Two-dimensional numerical modeling of the longitudinal and lateral channel deformations in alluvial rivers

    Institute of Scientific and Technical Information of China (English)

    XIA Junqiang; WANG Guangqian; WU Baosheng

    2004-01-01

    Two kinds of bank erosion mechanisms were analyzed, including fluvial and non-fluvial controlled mechanisms, and mechanical methods of simulating the erosion processes of cohesive, non-cohesive and composite riverbanks were improved. Then a two-dimensional numerical model of the channel deformation was developed, consisting of a 2D flow and sediment transport submodel and bank-erosion submodels of different soil riverbanks. In the model, a new technique for updating the bank geometry during the bed evolution was presented, which combines closely two kinds of submodels. The proposed model is capable of not only predicting the processes of flood routing and longitudinal channel deformation in natural rivers, but also simulating the processes of lateral channel deformation, especially the processes of lateral erosion and failure of cohesive, non-cohesive and composite riverbanks.

  8. Error Probability Analysis of Free-Space Optical Links with Different Channel Model under Turbulent Condition

    CERN Document Server

    Barua, Bobby; Islam, Md Rezwan

    2012-01-01

    Free space optics (FSO) is a promising solution for the need to very high data rate point-to point communication. FSO communication technology became popular due to its large bandwidth potential, unlicensed spectrum, excellent security and quick and inexpensive setup. Unfortunately, atmospheric turbulence-induced fading is one of the main impairments affecting FSO communications. To design a high performance communication link for the atmospheric FSO channel, it is of great importance to characterize the channel with proper model. In this paper, the modulation format is Q-ary PPM across lasers, with intensity modulation and ideal photodetectors are assumed to investigate the most efficient PDF models for FSO communication under turbulent condition. The performance results are evaluated in terms of symbol error probability (SEP) for different type of channel model and the simulation results confirm the analytical findings.

  9. NB-PLC channel modelling with cyclostationary noise addition & OFDM implementation for smart grid

    Science.gov (United States)

    Thomas, Togis; Gupta, K. K.

    2016-03-01

    Power line communication (PLC) technology can be a viable solution for the future ubiquitous networks because it provides a cheaper alternative to other wired technology currently being used for communication. In smart grid Power Line Communication (PLC) is used to support communication with low rate on low voltage (LV) distribution network. In this paper, we propose the channel modelling of narrowband (NB) PLC in the frequency range 5 KHz to 500 KHz by using ABCD parameter with cyclostationary noise addition. Behaviour of the channel was studied by the addition of 11KV/230V transformer, by varying load location and load. Bit error rate (BER) Vs signal to noise ratio SNR) was plotted for the proposed model by employing OFDM. Our simulation results based on the proposed channel model show an acceptable performance in terms of bit error rate versus signal to noise ratio, which enables communication required for smart grid applications.

  10. MODELING OF THE DIVERSION CHANNEL CLOSURE FOR THE THIRD STAGE OF THE THREE GORGES PROJECT

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Baosheng WU; Junqiang XIA

    2004-01-01

    The closure of third stage diversion channel for the Three Gorges Dam is characterized by large closure discharge, large drop in water surface, and high gap velocity. 1D and 2D flow mathematical models were used in this paper to simulate the hydraulic conditions during the closure. The variation of discharge in the diversion channel and the drops in water surface shared by the upstream and downstream cofferdams were computed using the 1D model, and the detailed hydraulic patterns in the diversion channel were simulated using the 2D model. The computed results indicate that the designed closure scheme for discharge of 9,010 m3/s was feasible for construction, while the designed closure scheme for discharge of 12,200 m3/s was inapplicable.

  11. Impact of Clustering in Indoor MIMO Propagation Using a Hybrid Channel Model

    Directory of Open Access Journals (Sweden)

    Tang Zhongwei

    2005-01-01

    Full Text Available The clustering of propagating signals in indoor environments can influence the performance of multiple-input multiple-output (MIMO systems that employ multiple-element antennas at the transmitter and receiver. In order to clarify the effect of clustering propagation on the performance of indoor MIMO systems, we propose a simple and efficient indoor MIMO channel model. The proposed model, which is validated with on-site measurements, combines the statistical characteristics of signal clusters with deterministic ray tracing approach. Using the proposed model, the effect of signal clusters and the presence of the line-of-sight component in indoor Ricean channels are studied. Simulation results on channel efficiency and the angular sensitivity for different antenna array topologies inside a specified indoor scenario are also provided. Our investigations confirm that the clustering of signals significantly affects the spatial correlation, and hence, the achievable indoor MIMO capacity.

  12. Quantum Communications Made Easy: Deterministic Models of Bosonic Channels

    OpenAIRE

    Smith, Graeme; Smolin, John A.

    2012-01-01

    Information theory establishes the ultimate limits on performance for noisy communication systems [Shannon48]. An accurate model of a physical communication device must include quantum effects, but typically including these makes the theory intractable. As a result communication capacities are not known, even for transmission between two users connected by an electromagnetic waveguide subject to gaussian noise. Here we present an exactly solvable model of communications with a fully quantum e...

  13. Unsound Sound

    DEFF Research Database (Denmark)

    Knakkergaard, Martin

    2016-01-01

    This article discusses the change in premise that digitally produced sound brings about and how digital technologies more generally have changed our relationship to the musical artifact, not simply in degree but in kind. It demonstrates how our acoustical conceptions are thoroughly challenged...

  14. Modeling of Mutiscale Electromagnetic Magnetosphere-Ionosphere Interactions near Discrete Auroral Arcs Observed by the MICA Sounding Rocket

    Science.gov (United States)

    Streltsov, A. V.; Lynch, K. A.; Fernandes, P. A.; Miceli, R.; Hampton, D. L.; Michell, R. G.; Samara, M.

    2012-12-01

    The MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) sounding rocket was launched from Poker Flat on February 19, 2012. The rocket was aimed into the system of discrete auroral arcs and during its flight it detected small-scale electromagnetic disturbances with characteristic features of dispersive Alfvén waves. We report results from numerical modeling of these observations. Our simulations are based on a two-fluid MHD model describing multi-scale interactions between magnetic field-aligned currents carried by shear Alfven waves and the ionosphere. The results from our simulations suggest that the small-scale electromagnetic structures measured by MICA indeed can be interpreted as dispersive Alfvén waves generated by the active ionospheric response (ionopspheric feedback instability) inside the large-scale downward magnetic field-aligned current interacting with the ionosphere.

  15. Modeling of high frequency radio wave absorption on oblique soundings during a solar X-ray flare

    Science.gov (United States)

    Rogov, D. D.; Moskaleva, E. V.; Zaalov, N. Y.

    2015-01-01

    High frequency radio wave absorption induced by Solar Ultra-Violet (UV) and X-ray flux is investigated. The influence of the solar flare observed on 11 April 2013 on the structure of oblique sounding ionograms in the Arctic region of Russia is considered. An adjustable model of the ionosphere developed for high frequency (HF) propagation problems was employed for this purpose. The simulation algorithm has been designed to accept a large variety of ionospheric conditions. On the basis of the SWPC D-region Absorption model the absorption effects in the ionosphere at sub-auroral latitudes of the Earth were calculated. This approach does not require knowledge of the electron density and electron collision frequency profiles of the D-region ionosphere. The oblique ionograms simulated with the absorption effect and ionograms provided by Russian network of ionospheric observations deployed in Arctic region exhibit quite a good resemblance.

  16. Model of the Long Island Sound outflow: Comparison with year-long HF radar and Doppler current observations

    Science.gov (United States)

    Mau, Jenq-Chi; Wang, Dong-Ping; Ullman, David S.; Codiga, Daniel L.

    2008-08-01

    A three-dimensional primitive-equation model is used to simulate the Long Island Sound (LIS) outflow for a 1-year (2001) period. The model domain includes LIS and New York Bight (NYB). Tidal and wind forcing are included, and seasonal salinity and temperature variations are assimilated. The model results are validated with the HF radar, moored acoustic Doppler current profiler (ADCP), and ferry-based ADCP observations. The agreement between simulated and observed flow patterns generally is very good. The difference in seasonal mean currents between the model and moored ADCP is about 0.01 m/s; the correlation of dominant velocity fluctuations between the model and HF radar is 0.83; and the difference in mean LIS transport between the model and shipboard ADCP is about 5%. However, the model predicts a prominent tidally generated headland eddy not supported by the HF radar observation. The model sensitivity study indicates that the tides, winds, and ambient coastal front all have important impact on the buoyant outflow. The tides and winds cause stronger vertical mixing, which reduces the surface plume strength. The ambient coastal front, on the other hand, tends to enhance the plume.

  17. Sound propagation in dilute suspensions of spheres: Analytical comparison between coupled phase model and multiple scattering theory.

    Science.gov (United States)

    Valier-Brasier, Tony; Conoir, Jean-Marc; Coulouvrat, François; Thomas, Jean-Louis

    2015-10-01

    Sound propagation in dilute suspensions of small spheres is studied using two models: a hydrodynamic model based on the coupled phase equations and an acoustic model based on the ECAH (ECAH: Epstein-Carhart-Allegra-Hawley) multiple scattering theory. The aim is to compare both models through the study of three fundamental kinds of particles: rigid particles, elastic spheres, and viscous droplets. The hydrodynamic model is based on a Rayleigh-Plesset-like equation generalized to elastic spheres and viscous droplets. The hydrodynamic forces for elastic spheres are introduced by analogy with those of droplets. The ECAH theory is also modified in order to take into account the velocity of rigid particles. Analytical calculations performed for long wavelength, low dilution, and weak absorption in the ambient fluid show that both models are strictly equivalent for the three kinds of particles studied. The analytical calculations show that dilatational and translational mechanisms are modeled in the same way by both models. The effective parameters of dilute suspensions are also calculated. PMID:26520342

  18. Modeling magnetosensitive ion channels in the viscoelastic environment of living cells.

    Science.gov (United States)

    Goychuk, Igor

    2015-10-01

    We propose and study a model of hypothetical magnetosensitive ionic channels which are long thought to be a possible candidate to explain the influence of weak magnetic fields on living organisms ranging from magnetotactic bacteria to fishes, birds, rats, bats, and other mammals including humans. The core of the model is provided by a short chain of magnetosomes serving as a sensor, which is coupled by elastic linkers to the gating elements of ion channels forming a small cluster in the cell membrane. The magnetic sensor is fixed by one end on cytoskeleton elements attached to the membrane and is exposed to viscoelastic cytosol. Its free end can reorient stochastically and subdiffusively in viscoelastic cytosol responding to external magnetic field changes and can open the gates of coupled ion channels. The sensor dynamics is generally bistable due to bistability of the gates which can be in two states with probabilities which depend on the sensor orientation. For realistic parameters, it is shown that this model channel can operate in the magnetic field of Earth for a small number (five to seven) of single-domain magnetosomes constituting the sensor rod, each of which has a typical size found in magnetotactic bacteria and other organisms or even just one sufficiently large nanoparticle of a characteristic size also found in nature. It is shown that, due to the viscoelasticity of the medium, the bistable gating dynamics generally exhibits power law and stretched exponential distributions of the residence times of the channels in their open and closed states. This provides a generic physical mechanism for the explanation of the origin of such anomalous kinetics for other ionic channels whose sensors move in a viscoelastic environment provided by either cytosol or biological membrane, in a quite general context, beyond the fascinating hypothesis of magnetosensitive ionic channels we explore. PMID:26565276

  19. Modeling magnetosensitive ion channels in the viscoelastic environment of living cells

    Science.gov (United States)

    Goychuk, Igor

    2015-10-01

    We propose and study a model of hypothetical magnetosensitive ionic channels which are long thought to be a possible candidate to explain the influence of weak magnetic fields on living organisms ranging from magnetotactic bacteria to fishes, birds, rats, bats, and other mammals including humans. The core of the model is provided by a short chain of magnetosomes serving as a sensor, which is coupled by elastic linkers to the gating elements of ion channels forming a small cluster in the cell membrane. The magnetic sensor is fixed by one end on cytoskeleton elements attached to the membrane and is exposed to viscoelastic cytosol. Its free end can reorient stochastically and subdiffusively in viscoelastic cytosol responding to external magnetic field changes and can open the gates of coupled ion channels. The sensor dynamics is generally bistable due to bistability of the gates which can be in two states with probabilities which depend on the sensor orientation. For realistic parameters, it is shown that this model channel can operate in the magnetic field of Earth for a small number (five to seven) of single-domain magnetosomes constituting the sensor rod, each of which has a typical size found in magnetotactic bacteria and other organisms or even just one sufficiently large nanoparticle of a characteristic size also found in nature. It is shown that, due to the viscoelasticity of the medium, the bistable gating dynamics generally exhibits power law and stretched exponential distributions of the residence times of the channels in their open and closed states. This provides a generic physical mechanism for the explanation of the origin of such anomalous kinetics for other ionic channels whose sensors move in a viscoelastic environment provided by either cytosol or biological membrane, in a quite general context, beyond the fascinating hypothesis of magnetosensitive ionic channels we explore.

  20. Synthetic Aperture Radiometry Evaluated by a Two-Channel Demonstration Model

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1998-01-01

    radiometer systems, especially at low frequencies. The TUD SARad demonstration model consists of a two-channel Ku-band correlation radiometer with two horn antennas and an antenna mounting structure enabling the horns to be mounted in relevant positions within a certain aperture. A total aperture synthesis......The Technical University of Denmark (TUD) Synthetic Aperture Radiometer (SARad) is a two-channel demonstration model that can simulate a two-dimensional (2D) thinned array radiometer having an unfilled aperture populated with several small antenna elements. Aperture synthesis obtained by...

  1. Analysis and modelling of non-steady flow in pipe and channel networks

    CERN Document Server

    Jovic, Vinko

    2013-01-01

    Analysis and Modelling of Non-Steady Flow in Pipe and Channel Networks deals with flows in pipes and channel networks from the standpoints of hydraulics and modelling techniques and methods. These engineering problems occur in the course of the design and construction of hydroenergy plants, water-supply and other systems. In this book, the author presents his experience in solving these problems from the early 1970s to the present day. During this period new methods of solving hydraulic problems have evolved, due to the development of computers and numerical methods. This book

  2. LTE-advanced and next generation wireless networks channel modelling and propagation

    CERN Document Server

    de la Roche, Guillaume; Allen, Ben

    2012-01-01

    LTE- A and Next Generation Wireless Networks: Channel Modeling and Performance describes recent advances in propagation and channel modeling necessary for simulating next generation wireless systems. Due to the radio spectrum scarcity, two fundamental changes are anticipated compared to the current status. Firstly, the strict reservation of a specific band for a unique standard could evolve toward a priority policy allowing the co-existence of secondary users in a band allocated to a primary system. Secondly, a huge increase of the number of cells is expected by combining outdoor base station

  3. MIMO capacity for deterministic channel models: sublinear growth

    DEFF Research Database (Denmark)

    Bentosela, Francois; Cornean, Horia; Marchetti, Nicola

    2013-01-01

    This is the second paper by the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. In our previous paper, we started from the Maxwell equations and described the generic structure of such a deterministic transfer matrix...... some generic assumptions, we prove that the capacity grows much more slowly than linearly with the number of antennas. These results reinforce previous heuristic results obtained from statistical models of the transfer matrix, which also predict a sublinear behavior....

  4. Performance Analysis of Wavelet Channel Coding in COST207-based Channel Models on Simulated Radio-over-Fiber Systems at the W-Band

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira; Silveira, Luiz F. Q.; Rommel, Simon;

    2016-01-01

    , such systems use diversity schemes in combination with digital signal processing (DSP) techniques to overcome effects such as fading and inter-symbol interference (ISI). Wavelet Channel Coding (WCC) has emerged as a technique to minimize the fading effects of wireless channels, which is a mayor challenge...... in systems operating in the millimeter wave regime. This work takes the WCC one step beyond by performance evaluation in terms of bit error probability, over time-varying, frequency-selective multipath Rayleigh fading channels. The adopted propagation model follows the COST207 norm, the main international...

  5. Ray tracing in a turbulent, shallow-water channel

    DEFF Research Database (Denmark)

    Bjerrum-Niese, Christian; Lützen, René; Jensen, Leif Bjørnø

    1998-01-01

    –1069 (1994) and Flatté et al., Sound transmission through a fluctuating ocean (1979)]. Amplitude and phase fluctuations of every ray are realized as samples of a random process. The results for the dynamic channel show a smoother and easier interpretable transmission loss behavior than for the static channel......A ray tracing model can be used to simulate sound (10–100 kHz) transmitted through shallow water. The phase of the ray arrivals, primarily given by travel time, may be mutually independent in such a multipath transmission. Consequently, the transmission loss in a receiving point is randomly valued...

  6. Markov chain models of coupled calcium channels: Kronecker representations and iterative solution methods

    International Nuclear Information System (INIS)

    Mathematical models of calcium release sites derived from Markov chain models of intracellular calcium channels exhibit collective gating reminiscent of the experimentally observed phenomenon of stochastic calcium excitability (i.e., calcium puffs and sparks). Calcium release site models are stochastic automata networks that involve many functional transitions, that is, the transition probabilities of each channel depend on the local calcium concentration and thus the state of the other channels. We present a Kronecker-structured representation for calcium release site models and perform benchmark stationary distribution calculations using both exact and approximate iterative numerical solution techniques that leverage this structure. When it is possible to obtain an exact solution, response measures such as the number of channels in a particular state converge more quickly using the iterative numerical methods than occupation measures calculated via Monte Carlo simulation. In particular, multi-level methods provide excellent convergence with modest additional memory requirements for the Kronecker representation of calcium release site models. When an exact solution is not feasible, iterative approximate methods based on the power method may be used, with performance similar to Monte Carlo estimates. This suggests approximate methods with multi-level iterative engines as a promising avenue of future research for large-scale calcium release site models

  7. Coupled Model of channels in parallel and neutron kinetics in two dimensions

    International Nuclear Information System (INIS)

    In this work an arrangement of thermohydraulic channels is presented that represent those four quadrants of a nucleus of reactor type BWR. The channels are coupled to a model of neutronic in two dimensions that allow to generate the radial profile of power of the reactor. Nevertheless that the neutronic pattern is of two dimensions, it is supplemented with axial additional information when considering the axial profiles of power for each thermo hydraulic channel. The stationary state is obtained the one it imposes as frontier condition the same pressure drop for all the channels. This condition is satisfied to iterating on the flow of coolant in each channel to equal the pressure drop in all the channels. This stationary state is perturbed later on when modifying the values for the effective sections corresponding to an it assembles. The calculation in parallel of the neutronic and the thermo hydraulic is carried out with Vpm (Virtual parallel machine) by means of an outline teacher-slave in a local net of computers. (Author)

  8. A permeation theory for single-file ion channels: One- and two-step models

    Science.gov (United States)

    Nelson, Peter Hugo

    2011-04-01

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  9. MIMO capacity for deterministic channel models: sublinear growth

    CERN Document Server

    Bentosela, Francois; Marchetti, Nicola

    2012-01-01

    This is the second paper of the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. Starting from the Maxwell equations, we have described in \\cite{BCFM} the generic structure of such a deterministic transfer matrix. In the current paper we apply the results of \\cite{BCFM} in order to study the (Shannon-Foschini) capacity behavior of a MIMO system as a function of the deterministic spread function of the environment, and the number of transmitting and receiving antennas. The antennas are assumed to fill in a given, fixed volume. Under some generic assumptions, we prove that the capacity grows much more slowly than linearly with the number of antennas. These results reinforce previous heuristic results obtained from statistical models of the transfer matrix, which also predict a sublinear behavior.

  10. Modelling of Current Percolation Channels in Emerging Resistive Switching Elements

    OpenAIRE

    Shihong, Marcus Wu; Prodromakis, Themistoklis; Salaoru, Iulia; Toumazou, Christofer

    2012-01-01

    Metallic oxides encased within Metal-Insulator-Metal (MIM) structures can demonstrate both unipolar and bipolar switching mechanisms, rendering them the capability to exhibit a multitude of resistive states and ultimately function as memory elements. Identifying the vital physical mechanisms behind resistive switching can enable these devices to be utilized more efficiently, reliably and in the long-term. In this paper, we present a new approach for analysing resistive switching by modelling ...

  11. Preliminary results on 3D channel modeling: From theory to standardization

    KAUST Repository

    Kammoun, Abla

    2014-06-01

    Three dimensional (3D) beamforming (also elevation beamforming) is now gaining interest among researchers in wireless communication. The reason can be attributed to its potential for enabling a variety of strategies such as sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently being made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and full dimensional (FD) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP study item \\'study on 3D-channel model for elevation beamforming and FD-MIMO studies for LTE\\' and positioning it with respect to previous standardization works. © 2014 IEEE.

  12. Hybrid Model For Reverberant Indoor Radio Channels Using Rays and Graphs

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Gan, Mingming; Meissner, Paul;

    2016-01-01

    Ray-tracing tools allow for deterministic simulation of the channel impulse response. Studies show that these tools work well when the impulse response consists only of a few distinct components. However, measurements of the channel impulse response in indoor environments show a diffuse tail. This...... diffuse tail is difficult to include in ray-tracing due to the computational complexity. We propose a hybrid model to include deterministic components and the diffuse tail by combining ray-tracing with a propagation graph. The recursive structure of the propagation graph allows for a computationally...... efficient calculation of the channel transfer function considering infinitely many components. We use ray-tracing and the theory of room electromagnetics to obtain the parameter settings for the propagation graph. Thus the proposed hybrid model does not require new or additional parameters in comparison to...

  13. Multi-ion conduction bands in a simple model of calcium ion channels

    International Nuclear Information System (INIS)

    We report self-consistent Brownian dynamics simulations of a simple electrostatic model of the selectivity filters (SF) of calcium ion channels. They reveal regular structure in the conductance and selectivity as functions of the fixed negative charge Qf at the SF. With increasing Qf, there are distinct regions of high conductance (conduction bands) M0, M1, M2 separated by regions of almost zero-conductance (stop-bands). Two of these conduction bands, M1 and M2, are related to the saturated calcium occupancies of P = 1 and P = 2, respectively and demonstrate self-sustained conductivity. Despite the model's limitations, its M1 and M2 bands show high calcium selectivity and prominent anomalous mole fraction effects and can be identified with the L-type and RyR calcium channels. The non-selective band M0 can be identified with a non-selective cation channel, or with OmpF porin. (paper)

  14. Modeling water droplet condensation and evaporation in DNS of turbulent channel flow

    International Nuclear Information System (INIS)

    In this paper a point particle model for two-way coupling in water droplet-laden incompressible turbulent flow of air is proposed. The model is based on conservation laws and semi-empirical correlations. It has been implemented and tested in a DNS code based for turbulent channel flow with an Eulerian-Lagrangian approach. The two-way coupling is investigated in terms of the effects of mass and heat transfer on the droplets distributions along the channel wall-normal direction and by comparison of the droplet temperature statistics with respect to the case without evaporation and condensation. A remarkable conclusion is that the presence of evaporating and condensing droplets results in an increase in the non-dimensional heat transfer coefficient of the channel flow represented by the Nusselt number.

  15. Extension of ITU IMT-A Channel Models for Elevation Domains and Line-of-Sight Scenarios

    CERN Document Server

    Zhong, Zhimeng; Li, Xin; Li, Xue

    2013-01-01

    In this contribution, the 3-dimensional (3D) channel characteristics, particularly in the elevation domains, are extracted through measurements in typical urban macro and micro environments in Xi'an China. Stochastic channel model parameters are obtained based on the high-resolution multi-path parameter estimates. In addition, a modified spatial channel model (SCM) for the line-of-sight (LoS) scenario is proposed where the LoS polarization matrix is parameterized in accordance with the reality. Measurement results justify the reasonability of the proposed model. These works significantly improve the applicability of the ITU SCM models in realistic 3D channel simulations.

  16. Applying marketing channel theory to food marketing in developing countries: A vertical disintegration model for horticultural marketing channels in Kenya

    NARCIS (Netherlands)

    Dijkstra, T.; Meulenberg, M.T.G.; Tilburg, van A.

    2001-01-01

    This article shows that marketing channel theory, which has been extensively applied in developed countries, can also be of great value to the developing world. Notably, the channel approach makes it possible to explain the number of trade levels observed in food marketing systems. We propose here a

  17. Channel and active component abstractions for WSN programming - a language model with operating system support

    OpenAIRE

    P. Harvey; Dearle, A.; Lewis, J.; Sventek, J.

    2012-01-01

    To support the programming of Wireless Sensor Networks, a number of unconventional programming models have evolved, in particular the event-based model. These models are non-intuitive to programmers due to the introduction of unnecessary, non-intrinsic complexity. Component-based languages like Insense can eliminate much of this unnecessary complexity via the use of active components and synchronous channels. However, simply layering an Insense implementation over an existing event-based syst...

  18. A free surface model for incompressible pipe and open channel flow.

    OpenAIRE

    Ersoy, Mehmet

    2013-01-01

    We present the full derivation of a free surface pipe or open channel model including friction, changes of section and changes of slope/topography. This 1D free surface model (also named \\textbf{FS}-model) is obtained from the incompressible 3D Navier-Stokes equation under shallow water assumptions with well-suited boundary conditions. It was introduced in the general framework of unsteady mixed flows in closed water pipes and is largely used by the engineers community.

  19. A GRAPH BASED MODEL FOR THE DETECTION OF TIDAL CHANNELS USING MARKED POINT PROCESSES

    Directory of Open Access Journals (Sweden)

    A. Schmidt

    2015-08-01

    Full Text Available In this paper we propose a new method for the automatic extraction of tidal channels in digital terrain models (DTM using a sampling approach based on marked point processes. In our model, the tidal channel system is represented by an undirected, acyclic graph. The graph is iteratively generated and fitted to the data using stochastic optimization based on a Reversible Jump Markov Chain Monte Carlo (RJMCMC sampler and simulated annealing. The nodes of the graph represent junction points of the channel system and the edges straight line segments with a certain width in between. In each sampling step, the current configuration of nodes and edges is modified. The changes are accepted or rejected depending on the probability density function for the configuration which evaluates the conformity of the current status with a pre-defined model for tidal channels. In this model we favour high DTM gradient magnitudes at the edge borders and penalize a graph configuration consisting of non-connected components, overlapping segments and edges with atypical intersection angles. We present the method of our graph based model and show results for lidar data, which serve of a proof of concept of our approach.

  20. Extension of an Ice Shelf Water plume model beneath sea ice with application in McMurdo Sound, Antarctica

    Science.gov (United States)

    Hughes, K. G.; Langhorne, P. J.; Leonard, G. H.; Stevens, C. L.

    2014-12-01

    A one-dimensional, frazil-laden plume model predicts the properties of Ice Shelf Water (ISW) as it evolves beneath sea ice beyond the ice shelf edge. An idealized background ocean circulation, which moves parallel to the plume, imitates forcings other than the plume's own buoyancy. The size distribution and concentration of the plume's suspended frazil ice crystals are affected by the background circulation velocity, the root-mean square tidal velocity, the drag coefficient, and the efficiency of secondary nucleation. Consequently, these variables are the key physical controls on the survival of supercooled water with distance from the ice shelf, which is predicted using several realistic parameter choices. Starting at 65 m thick, the in situ supercooled layer thins to 11 ± 5 and 4 ± 3 m at distances of 50 and 100 km, respectively. We apply the extended model in McMurdo Sound, Antarctica, along the expected path of the coldest water. Three late-winter oceanographic stations along this path, in conjunction with historical data, provide initial conditions and evaluation of the simulations. Near the ice shelf in the western Sound, the water column consisted entirely of ISW, and the subice platelet layer thickness exceeded 5 m with platelet crystals dominating the sea ice structure suggesting that ISW persisted throughout winter. Presuming a constant ISW flux, the model predicts that the plume increases thermodynamic growth of sea ice by approximately 0.1 m yr-1 (˜5% of the average growth rate) even as far as 100 km beyond the ice shelf edge.

  1. MD300测深系统在河道地形测绘中的应用%Application of MD300 sounding system to the topographic mapping of river channels

    Institute of Scientific and Technical Information of China (English)

    肖华; 唐从胜; 田次平

    2001-01-01

    In recent years,the global positioning system(GPS) technique is rapidly developing,since it is characterized by continuity,real-time,all-weather operation with high accuracy,this technique has found extensive application in survey,positioning,navigation.MD300 sounding system is a new topograpbic survey system especially for water areas supported by GPS.In combination with the development and application of the sounding system carried out by the Jingjiang Investigation Bureau of Hydrology and Water Resources of Changjiang Water Resources Commission,the structural function and system configuration and the implementation methods of the system are presented.From the viewpoint of its practical effect of application,this sounding system has characteristics of accurate positioning,accurate water depth acquisition and high automation procedure,compared with conventional metheds.The system is an ideal river channel mapping system.%近年来,全球定位系统(GPS)技术迅猛发展,由于它具有连续、实时、高精度、全天候的特点,使其在诸如测量、定位、导航中得到广泛应用。MD300测深系统是在GPS支持下的一种全新的水域地形测量系统。结合长江委荆江水文水资源局对该系统的开发、应用,介绍了其结构功能、系统配置及实现方法,从实际运用效果看,与常规测量方法相比,该系统具有定位精确、水深采集准确、自动化程度高等特点,是理想的河道测绘系统。

  2. A fast nonlinear variable structure equivalent magnetic circuit modeling for dual-channel switched reluctance machine

    International Nuclear Information System (INIS)

    Switched reluctance machines (SRMs) are normally designed and applied as 6/4 or 8/6 single-channel SRMs, recent efforts with 12/8 dual-channel SRM (DCSRM) have spurred interest. The DCSRM is driven by two independent sets of power electronic circuits with dual control channels and a fault tolerated operation mode can be used in this system for high reliability. In this paper, a fast nonlinear variable structure equivalent magnetic circuit (VSEMC) modeling method is developed for DCSRM. This method is used to calculate the static self and mutual flux linkage of phase winding for DCSRM by the formulas of airgap permeances, the stator and rotor pole and yoke permeances, in which the mutual effects as well as the magnetic saturation are taken into account. Then, a series of experimental tests are performed to obtain the static magnetic characteristics of a 12/8 DCSRM including self and mutual flux linkages under different rotor positions for varying exciting current conditions. The effectiveness of this proposed VSEMC method is verified by comparing with the FEM analysis and experimental results. Finally, details of simulation model for DCSRM under single channel operation mode and dual channel operation mode and comparison with experimental waveforms along with their implications for performances prediction are presented.

  3. Exploring the Inert Doublet Model through the dijet plus missing transverse energy channel at the LHC

    CERN Document Server

    Poulose, P; Sridhar, K

    2016-01-01

    In this study of the Inert Doublet Model (IDM), we propose that the dijet + missing transverse energy channel at the Large Hadron Collider will be an effective way of searching for the scalar particles of the IDM. This channel receives contributions from gauge boson fusion, and $t-$channel production, along with contributions from $H^+$ associated production. We find that, for $\\sqrt{s} =13$ TeV with moderate luminosity, this channel has the potential to probe the IDM in the mass range of up to about 150 GeV, complementing other leptonic channel searches. We perform the analysis including study of the Standard Model (SM) background, and optimise the selection criteria employing suitable cuts on the kinematic variables to maximise the signal significance. In a scenario with light dark matter of mass about 65 GeV, charged Higgs in the intermediate mass range of around 150 GeV could be probed with a luminosity of about 500 fb$^{-1}$, whereas higher masses around 200 and 300 GeV require about 1 and 2 ab$^{-1}$ lu...

  4. Impact of SLA assimilation in the Sicily Channel Regional Model: model skills and mesoscale features

    Directory of Open Access Journals (Sweden)

    A. Olita

    2012-07-01

    Full Text Available The impact of the assimilation of MyOcean sea level anomalies along-track data on the analyses of the Sicily Channel Regional Model was studied. The numerical model has a resolution of 1/32° degrees and is capable to reproduce mesoscale and sub-mesoscale features. The impact of the SLA assimilation is studied by comparing a simulation (SIM, which does not assimilate data with an analysis (AN assimilating SLA along-track multi-mission data produced in the framework of MyOcean project. The quality of the analysis was evaluated by computing RMSE of the misfits between analysis background and observations (sea level before assimilation. A qualitative evaluation of the ability of the analyses to reproduce mesoscale structures is accomplished by comparing model results with ocean colour and SST satellite data, able to detect such features on the ocean surface. CTD profiles allowed to evaluate the impact of the SLA assimilation along the water column. We found a significant improvement for AN solution in terms of SLA RMSE with respect to SIM (the averaged RMSE of AN SLA misfits over 2 years is about 0.5 cm smaller than SIM. Comparison with CTD data shows a questionable improvement produced by the assimilation process in terms of vertical features: AN is better in temperature while for salinity it gets worse than SIM at the surface. This suggests that a better a-priori description of the vertical error covariances would be desirable. The qualitative comparison of simulation and analyses with synoptic satellite independent data proves that SLA assimilation allows to correctly reproduce some dynamical features (above all the circulation in the Ionian portion of the domain and mesoscale structures otherwise misplaced or neglected by SIM. Such mesoscale changes also infer that the eddy momentum fluxes (i.e. Reynolds stresses show major changes in the Ionian area. Changes in Reynolds stresses reflect a different pumping of eastward momentum from the eddy to

  5. Physiological role of Kv1.3 channel in T lymphocyte cell investigated quantitatively by kinetic modeling.

    Directory of Open Access Journals (Sweden)

    Panpan Hou

    Full Text Available Kv1.3 channel is a delayed rectifier channel abundant in human T lymphocytes. Chronic inflammatory and autoimmune disorders lead to the over-expression of Kv1.3 in T cells. To quantitatively study the regulatory mechanism and physiological function of Kv1.3 in T cells, it is necessary to have a precise kinetic model of Kv1.3. In this study, we firstly established a kinetic model capable to precisely replicate all the kinetic features for Kv1.3 channels, and then constructed a T-cell model composed of ion channels including Ca2+-release activated calcium (CRAC channel, intermediate K+ (IK channel, TASK channel and Kv1.3 channel for quantitatively simulating the changes in membrane potentials and local Ca2+ signaling messengers during activation of T cells. Based on the experimental data from current-clamp recordings, we successfully demonstrated that Kv1.3 dominated the membrane potential of T cells to manipulate the Ca2+ influx via CRAC channel. Our results revealed that the deficient expression of Kv1.3 channel would cause the less Ca2+ signal, leading to the less efficiency in secretion. This was the first successful attempt to simulate membrane potential in non-excitable cells, which laid a solid basis for quantitatively studying the regulatory mechanism and physiological role of channels in non-excitable cells.

  6. From channelization to restoration: Sociohydrologic modeling with changing community preferences in the Kissimmee River Basin, Florida

    Science.gov (United States)

    Chen, Xi; Wang, Dingbao; Tian, Fuqiang; Sivapalan, Murugesu

    2016-02-01

    The Kissimmee River Basin (Florida, USA) underwent river channelization in the 1960s and subsequent restoration in the 1990s, revealing a shift in management emphasis from flood protection to wetland health. In this paper, this shift is hypothesized to result from changing human values and preferences, and a power differential between the more numerous and affluent upstream urban residents (who prioritize wetland restoration) and downstream rural residents (who prioritize flood protection). We develop a conceptual sociohydrologic model to simulate the interactions between community interests and hydrology. The modeling results show that flood intensity decreased after channelization, which reduced concern about flooding. However, channelization also led to a decrease in wetland storage, which caused an increase of wetland concern, especially among the urban residents. Eventually, the community sensitivity switched from favoring flood protection to favoring wetlands, and subsequent management strategies switched from channelization to restoration. Using the model, we project that the wetlands will be recovering for the next 20 years and community sensitivity will slowly go back to a neutral state. However, possible rainfall intensification in the future could return the community sensitivity to favoring flood protection again. The preferential increase of upstream population growth will raise the community's concern about wetlands and the preferential increase of downstream population growth will magnify concern about flooding. This study provides insight into the driving forces behind human-water interactions in the Kissimmee River Basin while simultaneously demonstrating the potential of sociohydrologic modeling to describe complex human-water coupled systems with simple concepts and equations.

  7. Ear-to-Ear On-Body Channel Model for Hearing Aid Applications

    DEFF Research Database (Denmark)

    Kvist, Søren Helstrup; Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2015-01-01

    The deterministic ear-to-ear on-body channel is modeled by the use of a number of elliptically shaped paths. The semi-major axes of the elliptica lly shaped paths are adjusted such that they trace the outline of the head. The path gain converges when the number of paths is increased, su ch that t...

  8. PHYSIOLOGICALLY-BASED TOXICOKINETIC MODELING OF THREE WATERBORNE CHLOROETHANES IN CHANNEL CATFISH, ICTALURUS PUNCTATUS

    Science.gov (United States)

    A physiologically-based toxicokinetic model for fish was used to describe the uptake and disposition of three chlorinated ethanes in channel catfish (Ictalurus punctatus). atfish were simultaneously exposed to 1,1,2,2-tetrachloroethane (TCE), pentachloroethane (PCE), and hexachlo...

  9. Conversations around Design Sketches: Use of Communication Channels for Sharing Mental Models during Concept Generation

    Science.gov (United States)

    Ariff, Nik Shahman Nik Ahmad; Badke-Schaub, Petra; Eris, Ozgur

    2012-01-01

    In this paper, we present an exploratory protocol study on the use of different communication channels during design sketching. We focus on how individual designers share their mental models with other designers in a group, and analyse their use of graphical, textual, and verbal communications during concept generation. Our findings suggest that…

  10. Conversations around design sketches: use of communication channels for sharing mental models during concept generation

    NARCIS (Netherlands)

    Nik Ahmad Ariff, N.S.; Badke-Schaub, P.G.; Eris, O.

    2012-01-01

    In this paper, we present an exploratory protocol study on the use of different communication channels during design sketching. We focus on how individual designers share their mental models with other designers in a group, and analyze their use of graphical, textual, and verbal communications durin

  11. D1.3 -- Short Report on the First Draft Multi-link Channel Model

    DEFF Research Database (Denmark)

    Pedersen, Troels; Raulefs, Ronald; Steinboeck, Gerhard;

    This deliverable is a preliminary report on the activities towards multi-link channel models. It summarizes the activities and achievements of investigations of WP1 Task 1.2 in the first year of the project. In this deliverable work focuses on the characterization of the crosscorrelation of multi...

  12. CATHENA Models for Wolsong 1 Channels O6 and B10

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.H.; Lee, K.H.; Choi, H. [Korea Electric Power Research Institute, Taejon (Korea)

    2002-07-01

    This document includes CATHENA model development of slave channel O6 and B10 for Wolsong 1 trip coverage analysis in the project of ''Development of Assessment Technologies for CANDU Reactor Power and Trip Effectivness''. (author). 11 refs., 2 tabs.

  13. Modeling biofilm dynamics and hydraulic properties in variably saturated soils using a channel network model

    Science.gov (United States)

    Rosenzweig, Ravid; Furman, Alex; Dosoretz, Carlos; Shavit, Uri

    2014-07-01

    Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge, and bioremediation processes make understanding how biofilms affect flow highly important. In the current work, we present a channel-network model that incorporates water flow, substrate transport, and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatiotemporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.

  14. A Theoretical Model for Calculating Voltage Sensitivity of Ion Channels and the Application on Kv1.2 Potassium Channel

    Science.gov (United States)

    Yang, Huaiyu; Gao, Zhaobing; Li, Ping; Yu, Kunqian; Yu, Ye; Xu, Tian-Le; Li, Min; Jiang, Hualiang

    2012-01-01

    Voltage sensing confers conversion of a change in membrane potential to signaling activities underlying the physiological processes. For an ion channel, voltage sensitivity is usually experimentally measured by fitting electrophysiological data to Boltzmann distributions. In our study, a two-state model of the ion channel and equilibrium statistical mechanics principle were used to test the hypothesis of empirically calculating the overall voltage sensitivity of an ion channel on the basis of its closed and open conformations, and determine the contribution of individual residues to the voltage sensing. We examined the theoretical paradigm by performing experimental measurements with Kv1.2 channel and a series of mutants. The correlation between the calculated values and the experimental values is at respective level, R2 = 0.73. Our report therefore provides in silico prediction of key conformations and has identified additional residues critical for voltage sensing. PMID:22768937

  15. Coupling urban growth scenarios with nearshore biophysical change models to inform coastal restoration planning in Puget Sound, Washington

    Science.gov (United States)

    Byrd, K. B.; Kreitler, J.; Labiosa, W.

    2010-12-01

    A scenario represents an account of a plausible future given logical assumptions about how conditions change over discrete bounds of space and time. Development of multiple scenarios provides a means to identify alternative directions of urban growth that account for a range of uncertainty in human behavior. Interactions between human and natural processes may be studied by coupling urban growth scenario outputs with biophysical change models; if growth scenarios encompass a sufficient range of alternative futures, scenario assumptions serve to constrain the uncertainty of biophysical models. Spatially explicit urban growth models (map-based) produce output such as distributions and densities of residential or commercial development in a GIS format that can serve as input to other models. Successful fusion of growth model outputs with other model inputs requires that both models strategically address questions of interest, incorporate ecological feedbacks, and minimize error. The U.S. Geological Survey (USGS) Puget Sound Ecosystem Portfolio Model (PSEPM) is a decision-support tool that supports land use and restoration planning in Puget Sound, Washington, a 35,500 sq. km region. The PSEPM couples future scenarios of urban growth with statistical, process-based and rule-based models of nearshore biophysical changes and ecosystem services. By using a multi-criteria approach, the PSEPM identifies cross-system and cumulative threats to the nearshore environment plus opportunities for conservation and restoration. Sub-models that predict changes in nearshore biophysical condition were developed and existing models were integrated to evaluate three growth scenarios: 1) Status Quo, 2) Managed Growth, and 3) Unconstrained Growth. These decadal scenarios were developed and projected out to 2060 at Oregon State University using the GIS-based ENVISION model. Given land management decisions and policies under each growth scenario, the sub-models predicted changes in 1) fecal

  16. Multi-ion conduction bands in a simple model of calcium ion channels

    CERN Document Server

    Kaufman, I; Tindjong, R; McClintock, P V E; Eisenberg, R S

    2012-01-01

    We report self-consistent Brownian dynamics simulations of a simple electrostatic model of the selectivity filters (SF) of calcium ion channels. They reveal regular structure in the conductance and selectivity as functions of the fixed negative charge Qf at the SF. This structure comprises distinct regions of high conductance (conduction bands) M0, M1, M2 separated by regions of zero-conductance (stop-bands). Two of these conduction bands, M1 and M2, demonstrate high calcium selectivity and prominent anomalous mole fraction effects and can be identified with the L-type and RyR calcium channels.

  17. 3GPP Channel Model Emulation with Analysis of MIMO-LTE Performances in Reverberation Chamber

    Directory of Open Access Journals (Sweden)

    Nabil Arsalane

    2012-01-01

    Full Text Available Emulation methodology of multiple clusters channels for evaluating wireless communication devices over-the-air (OTA performance is investigated. This methodology has been used along with the implementation of the SIMO LTE standard. It consists of evaluating effective diversity gain (EDG level of SIMO LTE-OFDM system for different channel models according to the received power by establishing an active link between the transmitter and the receiver. The measurement process is set up in a Reverberation Chamber (RC. The obtained results are compared to the reference case of single input-single output (SISO in order to evaluate the real improvement attained by the implemented system.

  18. Modelling some characteristics of electrical networks used as channels for providing telecommunications

    Directory of Open Access Journals (Sweden)

    Henry Arturo Bastidas Mora

    2010-07-01

    Full Text Available This article describes the topology of the existent electric nets in different parts of the world, included the Colombian nets, and there performance when used as telecommunications channels. The transfer function is analyzed for low tension nets and radiation originated by PLC (Power Line Communications technology is also considered. Since the radiation originated by PLC cannot be avoided completely the effect electromagnetic interference will be described with radio frequency communications. Modeling of the PLC channel is proposed and at the end conclusions are presented.

  19. The use of kernel local Fisher discriminant analysis for the channelization of the Hotelling model observer

    Science.gov (United States)

    Wen, Gezheng; Markey, Mia K.

    2015-03-01

    It is resource-intensive to conduct human studies for task-based assessment of medical image quality and system optimization. Thus, numerical model observers have been developed as a surrogate for human observers. The Hotelling observer (HO) is the optimal linear observer for signal-detection tasks, but the high dimensionality of imaging data results in a heavy computational burden. Channelization is often used to approximate the HO through a dimensionality reduction step, but how to produce channelized images without losing significant image information remains a key challenge. Kernel local Fisher discriminant analysis (KLFDA) uses kernel techniques to perform supervised dimensionality reduction, which finds an embedding transformation that maximizes betweenclass separability and preserves within-class local structure in the low-dimensional manifold. It is powerful for classification tasks, especially when the distribution of a class is multimodal. Such multimodality could be observed in many practical clinical tasks. For example, primary and metastatic lesions may both appear in medical imaging studies, but the distributions of their typical characteristics (e.g., size) may be very different. In this study, we propose to use KLFDA as a novel channelization method. The dimension of the embedded manifold (i.e., the result of KLFDA) is a counterpart to the number of channels in the state-of-art linear channelization. We present a simulation study to demonstrate the potential usefulness of KLFDA for building the channelized HOs (CHOs) and generating reliable decision statistics for clinical tasks. We show that the performance of the CHO with KLFDA channels is comparable to that of the benchmark CHOs.

  20. A homology model of the pore domain of a voltage-gated calcium channel is consistent with available SCAM data

    OpenAIRE

    Bruhova, Iva; Zhorov, Boris S.

    2010-01-01

    In the absence of x-ray structures of calcium channels, their homology models are used to rationalize experimental data and design new experiments. The modeling relies on sequence alignments between calcium and potassium channels. Zhen et al. (2005. J. Gen. Physiol. doi:10.1085/jgp.200509292) used the substituted cysteine accessibility method (SCAM) to identify pore-lining residues in the Cav2.1 channel and concluded that their data are inconsistent with the symmetric architecture of the pore...

  1. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Hobe Sound NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Hobe...

  2. STUDY AND APPLICATION OF STEADY FLOW AND UNSTEADY FLOW MATHEMATICAL MODEL FOR CHANNEL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the Preissmann implicit scheme for the one-dimensional Saint-Venant equation, the mathematical model for one-dimensional river networks and canal networks was developed and the key issues on the model were expatiated particularly in this article. This model applies the method of three-steps solution for channel-junction-channel to simulate the river networks, and the Gauss elimination method was used to calculate the sparse matrix. This model was applied to simulate the tree-type irrigation canal networks, complex looped channel networks and the Lower Columbia Slough networks. The results of water level and discharge agree with the data from the Adlul and field data. The model is proved to be robust for simulating unsteady flows in river networks with various degrees of complex structure. The calculated results show that this model is useful for engineering applications in complicated river networks. Future research was recommended to focus on setting up ecological numerical model of water quality in river networks and canal networks.

  3. The Model of Communication Channel in the 802.11b Standard Wireless Network

    Directory of Open Access Journals (Sweden)

    Zdenek Silar

    2008-01-01

    Full Text Available The paper deals with software modelling of a communication channel in the 802.11b standard wireless network physical layer. A computer model of signal processing was created to verify possibility of the proposal of localisation system. Functionality of the signal generation and processing model was verified by the Spectrum Analyzer. Simulations run inSimulink/Matlab SW. The Simulink is used for the signal processor model and a pure Matlab software is used for mathematical evaluations of data processor model and for determination of initial conditions.

  4. Communication channel modeling of human forearm with muscle fiber tissue characteristics.

    Science.gov (United States)

    Zhang, Shuang; Pun, Sio Hang; Mak, Peng Un; Qin, Yu-Ping; Liu, Yi-He; Vai, Mang I

    2016-09-14

    Human-Body Communication (HBC) is a wireless communication method using the human body tissue as a transmission medium for signals. This paper on the basis of human muscle fiber tissues' characteristics, it is first proposed to establish the analytical model of galvanic coupling human-body communication channel. In this model, the parallel and the transverse electrical characteristics of muscular tissue are fully considered, and the model accurately presents the transmission mechanism of galvanic coupling human-body communication signals in the channel. At last, through compare with the experimental results and calculation results, the maximum error of the model is 22.4% and the average error is 14.2% within the frequency range.

  5. The Large Office Environment - Measurement and Modeling of the Wideband Radio Channel

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Nielsen, Jesper Ødum; Bauch, Gerhard;

    2006-01-01

    In a future 4G or WLAN wideband application we can imagine multiple users in a large office environment con-sisting of a single room with partitions. Up to now, indoor radio channel measurement and modelling has mainly concentrated on scenarios with several office rooms and corridors. We present...... here measurements at 5.8GHz for 100 MHz bandwidth and a novel modelling approach for the wideband radio channel in a large office room envi-ronment. An acoustic like reverberation theory is pro-posed that allows to specify a tapped delay line model just from the room dimensions and an average...... absorption co-efficient of the delimiting walls. The proposed model agrees amazingly well with the measurements, showing that the diffuse part is uniformly spread over the room with a constant energy level and a constant temporal de-cay slope. Furthermore, we analyze fading statistics and capacities...

  6. Underwater Acoustic Networks: Channel Models and Network Coding based Lower Bound to Transmission Power for Multicast

    CERN Document Server

    Lucani, Daniel E; Stojanovic, Milica

    2008-01-01

    The goal of this paper is two-fold. First, to establish a tractable model for the underwater acoustic channel useful for network optimization in terms of convexity. Second, to propose a network coding based lower bound for transmission power in underwater acoustic networks, and compare this bound to the performance of several network layer schemes. The underwater acoustic channel is characterized by a path loss that depends strongly on transmission distance and signal frequency. The exact relationship among power, transmission band, distance and capacity for the Gaussian noise scenario is a complicated one. We provide a closed-form approximate model for 1) transmission power and 2) optimal frequency band to use, as functions of distance and capacity. The model is obtained through numerical evaluation of analytical results that take into account physical models of acoustic propagation loss and ambient noise. Network coding is applied to determine a lower bound to transmission power for a multicast scenario, fo...

  7. Modelling and performance analysis of dual-channel switched reluctance motor

    Directory of Open Access Journals (Sweden)

    Bogusz Piotr

    2015-03-01

    Full Text Available The paper is a presentation of an analysis concerning performance of a 12/8 dual-channel switched reluctance motor (DCSRM. Formulas constituting a base for a non-linear mathematical model of DCSRM are presented. Simulation and laboratory tests were carried out for the motor operating in the dual-channel and single-channel mode. The results of the field theory-based calculations are presented in the form of fluxes in individual phases expressed as functions of currents and a rotor position angle. The results of the computer simulations are shown as the static characteristics of fluxes and the torque as well as voltage, current, and torque waveforms. The results of the laboratory tests are also presented.

  8. Modelling the water mass exchange through navigational channels connecting adjacent coastal basins - application to the Channel of Potidea (North Aegean Sea

    Directory of Open Access Journals (Sweden)

    Y. G. Savvidis

    2005-02-01

    Full Text Available The research objective is the detection of the mechanism of the water mass exchange through a navigational channel connecting two adjacent coastal basins. The research involves the application of a mathematical model in parallel to in-situ measurements. The hydrodynamic circulation in the greater area of the NW Aegean Sea is modeled by means of a barotropic circulation model. Wind, Coriolis and Tide are the main forcings taken into account. The flow through the channel is resolved at a subgrid scale by means of a local open channel flow model. The comparison between field measurements, recorded during a limited period, and the model results supports the model verification. The study is integrated by an operational application of the model under various realistic forcings. The results help to gain a better understanding of the mechanisms regulating the water mass exchange and the consequent interaction between two adjacent connected coastal basins. From the case study of the Potidea channel it is revealed that the water mass exchange under mean wind forcing is of the same order as the one induced by the tidal forcing.

  9. SoleSound

    DEFF Research Database (Denmark)

    Zanotto, Damiano; Turchet, Luca; Boggs, Emily Marie;

    2014-01-01

    This paper introduces the design of SoleSound, a wearable system designed to deliver ecological, audio-tactile, underfoot feedback. The device, which primarily targets clinical applications, uses an audio-tactile footstep synthesis engine informed by the readings of pressure and inertial sensors...... embedded in the footwear to integrate enhanced feedback modalities into the authors' previously developed instrumented footwear. The synthesis models currently implemented in the SoleSound simulate different ground surface interactions. Unlike similar devices, the system presented here is fully portable...

  10. Hydrogen production in a zigzag and straight catalytic wall coated micro channel reactor by CFD modeling

    Energy Technology Data Exchange (ETDEWEB)

    Fazeli, Ali; Behnam, Mohsen [Gas Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-137, Tehran (Iran)

    2010-09-15

    Hydrogen production from steam reforming of methanol for fuel cell application was modeled in a wall coated micro channel reactor by CFD approach. Heat of steam reforming (SR) was supplied from catalytic total oxidation (TOX) of methanol on Cu/ZnO/Al{sub 2}O{sub 3} catalyst and Heat conducts from TOX to SR zone through Steel divider wall between two channels. Heat integration was compared in zigzag and straight geometry of microreactor by CFD modeling. The model is two dimensional, steady state and containing five zones: TOX fluid, TOX catalyst layer, steel wall of the channel, SR catalyst layer and SR fluid. Set of partial differential equations (PDEs) including x and y momentum balance, continuity, partial mass balances and energy balance was solved by finite volume method. Stiff reaction rates were considered for methanol total oxidation (TOX), methanol steam reforming (SR), water gas shift (WGS) and methanol decomposition (MD) reactions. The results show that zigzag geometry is better than straight one because heat and mass transfer in zigzag reactor are more than straight. Conversion of methanol in zigzag geometry is greater than straight one. In the outlet of zigzag micro channels, carbon monoxide selectivity is less and hydrogen mole fraction is more than straight one. (author)

  11. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

    Science.gov (United States)

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

  12. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics.

    Science.gov (United States)

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

  13. Velocity of sound in hadron matter

    Energy Technology Data Exchange (ETDEWEB)

    Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Roulet, E.

    1987-09-01

    The velocity of sound in hadron matter, in both the confined and deconfined phases, is studied. This velocity of sound appears to be an important tool to distinguish among different bag-model-based thermodynamical descriptions of hadronic matter.

  14. Design of Transmitter for CDM Based 2×2 Multiple Input Multiple Output Channel Sounder for Multipath Delay Measurement

    Directory of Open Access Journals (Sweden)

    M. H. Ullah

    2012-01-01

    Full Text Available Problem statement: Multiple Input Multiple Output (MIMO wireless communication system is an innovative solution to improve the bandwidth efficiency by exploiting multipath-richness of the propagation environment. The degree of multipath-richness of the channel will determine the capacity gain attainable by MIMO deployment. Approach: Therefore, it is very important to have accurate knowledge of the propagation environment/radio channel before MIMO implement. The radio channel behavior can be anticipated by channel measurement or channel sounding. Code Division Multiplexing (CDM is one of the channel sounding techniques that allow accurate measurement at the cost of hardware complexity. CDM based channel sounder, requires code with excellent auto-correlation and cross-correlation properties which generally difficult to be achieved simultaneously. Results: In this study, an efficient transmitter for CDM-based 2×2 MIMO channel sounding technique with Loosely Synchronous (LS codes is designed. Simulation results shows that the channel sounding scheme using LS codes gives very good performance for measuring 2×2 MIMO channel behavior. The BPSK transmitter is designed using MATLAB, Verilog and Xilinx system generator blocks. Conclusion: The whole design is simulated as a single ISE project by using ModelSim simulation tool and compiled using ISE 9.2. However the proposed design of transmitter using LS code of length 8190 bits can measure multipath delay of minimum 0.13 μs and maximum 520 μs.

  15. Dynamical Coupled-Channel Model of Meson Production Reactions in the Nucleon Resonance Region

    Energy Technology Data Exchange (ETDEWEB)

    T.-S. H. Lee; A. Matsuyama; T. Sato

    2006-11-15

    A dynamical coupled-channel model is presented for investigating the nucleon resonances (N*) in the meson production reactions induced by pions and photons. Our objective is to extract the N* parameters and to investigate the meson production reaction mechanisms for mapping out the quark-gluon substructure of N* from the data. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method.

  16. Identification of Characteristic Protein Folding Channels in a Coarse-Grained Hydrophobic-Polar Peptide Model

    OpenAIRE

    Schnabel, Stefan; Bachmann, Michael; Janke, Wolfhard

    2007-01-01

    Folding channels and free-energy landscapes of hydrophobic-polar heteropolymers are discussed on the basis of a minimalistic off-lattice coarse-grained model. We investigate how rearrangements of hydrophobic and polar monomers in a heteropolymer sequence lead to completely different folding behaviors. Studying three exemplified sequences with the same content of hydrophobic and polar residues, we can reproduce within this simple model two-state folding, folding through intermediates, as well ...

  17. Coupled-channel cavity QED model and Semi-classical solution

    Institute of Scientific and Technical Information of China (English)

    WEN Ling-hua; KONG Ling-bo; LIU Min; ZHAN Ming-sheng

    2004-01-01

    A semi-classical scheme is presented to solve the coupled-channel cavity QED (CQED) model. Such model exhibits remarkable characteristics as shown by numerical calculations. A relation between the swing or angular velocity of the detuning and the motion of the atoms is discussed. With the augmentation of the optical field intensity or frequency, the atoms are trapped firstly and then they move stochastically and finally chaos sets in.

  18. Improved virtual channel noise model for transform domain Wyner-Ziv video coding

    DEFF Research Database (Denmark)

    Huang, Xin; Forchhammer, Søren

    2009-01-01

    Distributed video coding (DVC) has been proposed as a new video coding paradigm to deal with lossy source coding using side information to exploit the statistics at the decoder to reduce computational demands at the encoder. A virtual channel noise model is utilized at the decoder to estimate the...... coding is proposed, which utilizes cross-band correlation to estimate the Laplacian parameters more accurately. Experimental results show that the proposed noise model can improve the rate-distortion (RD) performance....

  19. A Model for the Handover Traffic and Channel Occupancy Time in LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    WangJingyu; YaoYongyang

    1995-01-01

    This paper presents a method to determine the parameters of the traffic model for the LEO satellite networks-the handover traffic and the mean channel occupancy time.The main idea is that the handover traffic is mainly due to the movement of the satellites and the velocity of the mobile terminals and earth rotation is ignored.The performance level can be calculated accord-ing to different handover queuing model.

  20. Morphology of rain water channelization in systematically varied model sandy soils

    OpenAIRE

    Wei, Y.; Cejas, C. M.; Barrois, R.; Dreyfus, R.; Durian, D. J.

    2014-01-01

    We visualize the formation of fingered flow in dry model sandy soils under different raining conditions using a quasi-2d experimental set-up, and systematically determine the impact of soil grain diameter and surface wetting property on water channelization phenomenon. The model sandy soils we use are random closely-packed glass beads with varied diameters and surface treatments. For hydrophilic sandy soils, our experiments show that rain water infiltrates into a shallow top layer of soil and...

  1. Predictive modeling of subsurface shoreline oil encounter probability from the Exxon Valdez oil spill in Prince William Sound, Alaska.

    Science.gov (United States)

    Nixon, Zachary; Michel, Jacqueline

    2015-04-01

    To better understand the distribution of remaining lingering subsurface oil residues from the Exxon Valdez oil spill (EVOS) along the shorelines of Prince William Sound (PWS), AK, we revised previous modeling efforts to allow spatially explicit predictions of the distribution of subsurface oil. We used a set of pooled field data and predictor variables stored as Geographic Information Systems (GIS) data to generate calibrated boosted tree models predicting the encounter probability of different categories of subsurface oil. The models demonstrated excellent predictive performance as evaluated by cross-validated performance statistics. While the average encounter probabilities at most shoreline locations are low across western PWS, clusters of shoreline locations with elevated encounter probabilities remain in the northern parts of the PWS, as well as more isolated locations. These results can be applied to estimate the location and amount of remaining oil, evaluate potential ongoing impacts, and guide remediation. This is the first application of quantitative machine-learning based modeling techniques in estimating the likelihood of ongoing, long-term shoreline oil persistence after a major oil spill.

  2. Asymptotic limits of some models for sound propagation in porous media and the assignment of the pore characteristic lengths.

    Science.gov (United States)

    Horoshenkov, Kirill V; Groby, Jean-Philippe; Dazel, Olivier

    2016-05-01

    Modeling of sound propagation in porous media requires the knowledge of several intrinsic material parameters, some of which are difficult or impossible to measure directly, particularly in the case of a porous medium which is composed of pores with a wide range of scales and random interconnections. Four particular parameters which are rarely measured non-acoustically, but used extensively in a number of acoustical models, are the viscous and thermal characteristic lengths, thermal permeability, and Pride parameter. The main purpose of this work is to show how these parameters relate to the pore size distribution which is a routine characteristic measured non-acoustically. This is achieved through the analysis of the asymptotic behavior of four analytical models which have been developed previously to predict the dynamic density and/or compressibility of the equivalent fluid in a porous medium. In this work the models proposed by Johnson, Koplik, and Dashn [J. Fluid Mech. 176, 379-402 (1987)], Champoux and Allard [J. Appl. Phys. 70(4), 1975-1979 (1991)], Pride, Morgan, and Gangi [Phys. Rev. B 47, 4964-4978 (1993)], and Horoshenkov, Attenborough, and Chandler-Wilde [J. Acoust. Soc. Am. 104, 1198-1209 (1998)] are compared. The findings are then used to compare the behavior of the complex dynamic density and compressibility of the fluid in a material pore with uniform and variable cross-sections. PMID:27250142

  3. Sound quality prediction of vehicle interior noise and mathematical modeling using a back propagation neural network (BPNN) based on particle swarm optimization (PSO)

    International Nuclear Information System (INIS)

    To better solve the complex non-linear problem between the subjective sound quality evaluation results and objective psychoacoustics parameters, a method for the prediction of the sound quality is put forward by using a back propagation neural network (BPNN) based on particle swarm optimization (PSO), which is optimizing the initial weights and thresholds of BP network neurons through the PSO. In order to verify the effectiveness and accuracy of this approach, the noise signals of the B-Class vehicles from the idle speed to 120 km h−1 measured by the artificial head, are taken as a target. In addition, this paper describes a subjective evaluation experiment on the sound quality annoyance inside the vehicles through a grade evaluation method, by which the annoyance of each sample is obtained. With the use of Artemis software, the main objective psychoacoustic parameters of each noise sample are calculated. These parameters include loudness, sharpness, roughness, fluctuation, tonality, articulation index (AI) and A-weighted sound pressure level. Furthermore, three evaluation models with the same artificial neural network (ANN) structure are built: the standard BPNN model, the genetic algorithm-back-propagation neural network (GA-BPNN) model and the PSO-back-propagation neural network (PSO-BPNN) model. After the network training and the evaluation prediction on the three models’ network based on experimental data, it proves that the PSO-BPNN method can achieve convergence more quickly and improve the prediction accuracy of sound quality, which can further lay a foundation for the control of the sound quality inside vehicles. (paper)

  4. Sound quality prediction of vehicle interior noise and mathematical modeling using a back propagation neural network (BPNN) based on particle swarm optimization (PSO)

    Science.gov (United States)

    Zhang, Enlai; Hou, Liang; Shen, Chao; Shi, Yingliang; Zhang, Yaxiang

    2016-01-01

    To better solve the complex non-linear problem between the subjective sound quality evaluation results and objective psychoacoustics parameters, a method for the prediction of the sound quality is put forward by using a back propagation neural network (BPNN) based on particle swarm optimization (PSO), which is optimizing the initial weights and thresholds of BP network neurons through the PSO. In order to verify the effectiveness and accuracy of this approach, the noise signals of the B-Class vehicles from the idle speed to 120 km h-1 measured by the artificial head, are taken as a target. In addition, this paper describes a subjective evaluation experiment on the sound quality annoyance inside the vehicles through a grade evaluation method, by which the annoyance of each sample is obtained. With the use of Artemis software, the main objective psychoacoustic parameters of each noise sample are calculated. These parameters include loudness, sharpness, roughness, fluctuation, tonality, articulation index (AI) and A-weighted sound pressure level. Furthermore, three evaluation models with the same artificial neural network (ANN) structure are built: the standard BPNN model, the genetic algorithm-back-propagation neural network (GA-BPNN) model and the PSO-back-propagation neural network (PSO-BPNN) model. After the network training and the evaluation prediction on the three models’ network based on experimental data, it proves that the PSO-BPNN method can achieve convergence more quickly and improve the prediction accuracy of sound quality, which can further lay a foundation for the control of the sound quality inside vehicles.

  5. Evaluation of Arroyo Channel Restoration Efforts using Hydrological Modeling: Rancho San Bernardino, Sonora, MX

    Science.gov (United States)

    Jemison, N. E.; DeLong, S.; Henderson, W. M.; Adams, J.

    2012-12-01

    In the drylands of the southwestern U.S. and northwestern Mexico, historical river channel incision (arroyo cutting) has led to the destruction of riparian ecological systems and cieñega wetlands in many locations. Along Silver Creek on the Arizona-Sonora border, the Cuenca Los Ojos Foundation has been installing rock gabions and concrete and earthen berms with a goal of slowing flash floods, raising groundwater levels, and refilling arroyo channels with sediment in an area that changed from a broad, perennially wet cieñega to a narrow sand- and gravel-dominated arroyo channel with an average depth of ~6 m. The engineering efforts hope to restore desert wetlands, regrow riparian vegetation, and promote sediment deposition along the arroyo floor. Hydrological modeling allows us to predict how rare flood events interact with the restoration efforts and may guide future approaches to dryland ecological restoration. This modeling is complemented by detailed topographic surveying and use of streamflow sensors to monitor hydrological processes in the restoration project. We evaluate the inundation associated with model 10-, 50-, 100-, 500-, and 1,000-year floods through the study area using FLO-2D and HEC-RAS modeling environments in order to evaluate the possibility of returning surface inundation to the former cieñega surface. According to HEC-RAS model predictions, given current channel configuration, it would require a 500-year flood to overtop the channel banks and reinundate the cieñega (now terrace) surface, though the 100-year flood may lead to limited terrace surface inundation. Based on our models, 10-year floods were ~2 m from overtopping the arroyo walls, 50-year floods came ~1.5 m from overtopping the arroyos, 100-year floods were ~1.2 m from overtopping, and 500- and 1,000-year floods at least partially inundated the cieñega surface. The current topography of Silver Creek does not allow for frequent flooding of the former cieñega; model predictions

  6. A cell model study of calcium influx mechanism regulated by calcium-dependent potassium channels in Purkinje cell dendrites.

    Science.gov (United States)

    Chono, Koji; Takagi, Hiroshi; Koyama, Shozo; Suzuki, Hideo; Ito, Etsuro

    2003-10-30

    The present study was designed to elucidate the roles of dendritic voltage-gated K+ channels in Ca2+ influx mechanism of a rat Purkinje cell using a computer simulation program. First, we improved the channel descriptions and the maximum conductance in the Purkinje cell model to mimic both the kinetics of ion channels and the Ca2+ spikes, which had failed in previous studies. Our cell model is, therefore, much more authentic than those in previous studies. Second, synaptic inputs that mimic stimulation of parallel fibers and induce sub-threshold excitability were simultaneously applied to the spiny dendrites. As a result, transient Ca2+ responses were observed in the stimulation points and they decreased with the faster decay rate in the cell model including high-threshold Ca2+-dependent K+ channels than in those excluding these channels. Third, when a single synaptic input was applied into a spiny dendrite, Ca2+-dependent K+ channels suppressed Ca2+ increases at stimulation and recording points. Finally, Ca2+-dependent K+ channels were also found to suppress the time to peak Ca2+ values in the recording points. These results suggest that the opening of Ca2+-dependent K+ channels by Ca2+ influx through voltage-gated Ca2+ channels hyperpolarizes the membrane potentials and deactivates these Ca2+ channels in a negative feedback manner, resulting in local, weak Ca2+ responses in spiny dendrites of Purkinje cells.

  7. Cybernetically sound organizational structures II: Relating de Sitter's design theory to Beer's viable system model

    NARCIS (Netherlands)

    Achterbergh, J.M.I.M.; Vriens, D.J.

    2011-01-01

    - Purpose – The purpose of this paper is to show how the viable system model (VSM) and de Sitter's design theory can complement each other in the context of the diagnosis and design of viable organizations. - Design/methodology/approach – Key concepts from Beer's model and de Sitter's design theory

  8. Words in Puddles of Sound: Modelling Psycholinguistic Effects in Speech Segmentation

    Science.gov (United States)

    Monaghan, Padraic; Christiansen, Morten H.

    2010-01-01

    There are numerous models of how speech segmentation may proceed in infants acquiring their first language. We present a framework for considering the relative merits and limitations of these various approaches. We then present a model of speech segmentation that aims to reveal important sources of information for speech segmentation, and to…

  9. A study of online plant modelling methods for active control of sound and vibration

    DEFF Research Database (Denmark)

    Laugesen, Søren

    1996-01-01

    for online plant modelling are compared by simulation. One approach yields convincing results in terms of converge, but sometimes the steady state performance can be suboptimal, because the plant models are erroneous. Another approach gives results close to the theoretically optimal for a broadband random...

  10. An Atlantic herring ( Clupea harengus ) size selection model for experimental gill nets used in the Sound (ICES Subdivision 23)

    DEFF Research Database (Denmark)

    Poulsen, S.; Nielsen, J. Rasmus; Holst, René;

    2000-01-01

    Size selection investigations were performed in the Sound with experimental, multipanel gill nets equipped with a broad range of mesh sizes targeting Atlantic herring (Clupea harengus). Each of the 20 experimental fishery surveys covered the central Sound from Helsingor-Helsingborg (north) to Dro...

  11. 单侧声带振动的远场声压研究%Research on the far-field sound pressure model of unilateral vocal cord vibration

    Institute of Scientific and Technical Information of China (English)

    赵晓; 曹辉; 徐晨

    2013-01-01

    Based on the physical structure and the vibration characteristics of the unilateral vocal cords, this paper pro-posed a unilateral vocal cold vibration model. The far-field sound pressure distribution of the unilateral vocal cord vi-bration model was calculated on the usage of acoustic theory and Rayleigh Integral. The sound pressure distribution pattern was calculated by numerical simulation, which was compared with the sound pressure distribution of the normal vocal cold model in the radiated sound field. The results showed that the sound pressure ratio almost does not change with the change of the direction angle when the vocal cord gap width is identical in the audio frequency range. When the direction angle remains unchanged, the sound pressure ratio decreases linearly with the increase of pores.%根据单侧声带的生理结构和振动特性,提出单侧声带振动模型。运用声学基本理论,采用瑞利积分,计算了此单侧声带模型振动的远场声压分布,仿真数值计算了声压分布规律,并与正常声带模型辐射声场的声压进行比较。结果表明,在音频范围内,在声带空隙宽度相同的条件下,声压比值几乎不随方向角的改变而改变。而在方向角相同情况下,声压比值随着孔隙的增加呈线性下降。

  12. Simulation of annual biogeochemical cycles of nutrient balance, phytoplankton bloom(s), and DO in Puget Sound using an unstructured grid model

    Energy Technology Data Exchange (ETDEWEB)

    Khangaonkar, Tarang; Sackmann, Brandon; Long, Wen; Mohamedali, Teizeen; Roberts, Mindy

    2012-08-14

    Nutrient pollution from rivers, nonpoint source runoff, and nearly 100 wastewater discharges is a potential threat to the ecological health of Puget Sound with evidence of hypoxia in some basins. However, the relative contributions of loads entering Puget Sound from natural and anthropogenic sources, and the effects of exchange flow from the Pacific Ocean are not well understood. Development of a quantitative model of Puget Sound is thus presented to help improve our understanding of the annual biogeochemical cycles in this system using the unstructured grid Finite-Volume Coastal Ocean Model framework and the Integrated Compartment Model (CE-QUAL-ICM) water quality kinetics. Results based on 2006 data show that phytoplankton growth and die-off, succession between two species of algae, nutrient dynamics, and dissolved oxygen in Puget Sound are strongly tied to seasonal variation of temperature, solar radiation, and the annual exchange and flushing induced by upwelled Pacific Ocean waters. Concentrations in the mixed outflow surface layer occupying approximately 5–20 m of the upper water column show strong effects of eutrophication from natural and anthropogenic sources, spring and summer algae blooms, accompanied by depleted nutrients but high dissolved oxygen levels. The bottom layer reflects dissolved oxygen and nutrient concentrations of upwelled Pacific Ocean water modulated by mixing with biologically active surface outflow in the Strait of Juan de Fuca prior to entering Puget Sound over the Admiralty Inlet. The effect of reflux mixing at the Admiralty Inlet sill resulting in lower nutrient and higher dissolved oxygen levels in bottom waters of Puget Sound than the incoming upwelled Pacific Ocean water is reproduced. Finally, by late winter, with the reduction in algal activity, water column constituents of interest, were renewed and the system appeared to reset with cooler temperature, higher nutrient, and higher dissolved oxygen waters from the Pacific

  13. Modeling-independent elucidation of inactivation pathways in recombinant and native A-type Kv channels.

    Science.gov (United States)

    Fineberg, Jeffrey D; Ritter, David M; Covarrubias, Manuel

    2012-11-01

    A-type voltage-gated K(+) (Kv) channels self-regulate their activity by inactivating directly from the open state (open-state inactivation [OSI]) or by inactivating before they open (closed-state inactivation [CSI]). To determine the inactivation pathways, it is often necessary to apply several pulse protocols, pore blockers, single-channel recording, and kinetic modeling. However, intrinsic hurdles may preclude the standardized application of these methods. Here, we implemented a simple method inspired by earlier studies of Na(+) channels to analyze macroscopic inactivation and conclusively deduce the pathways of inactivation of recombinant and native A-type Kv channels. We investigated two distinct A-type Kv channels expressed heterologously (Kv3.4 and Kv4.2 with accessory subunits) and their native counterparts in dorsal root ganglion and cerebellar granule neurons. This approach applies two conventional pulse protocols to examine inactivation induced by (a) a simple step (single-pulse inactivation) and (b) a conditioning step (double-pulse inactivation). Consistent with OSI, the rate of Kv3.4 inactivation (i.e., the negative first derivative of double-pulse inactivation) precisely superimposes on the profile of the Kv3.4 current evoked by a single pulse because the channels must open to inactivate. In contrast, the rate of Kv4.2 inactivation is asynchronous, already changing at earlier times relative to the profile of the Kv4.2 current evoked by a single pulse. Thus, Kv4.2 inactivation occurs uncoupled from channel opening, indicating CSI. Furthermore, the inactivation time constant versus voltage relation of Kv3.4 decreases monotonically with depolarization and levels off, whereas that of Kv4.2 exhibits a J-shape profile. We also manipulated the inactivation phenotype by changing the subunit composition and show how CSI and CSI combined with OSI might affect spiking properties in a full computational model of the hippocampal CA1 neuron. This work unambiguously

  14. Modeling of concentration polarization in a reverse osmosis channel with parabolic crossflow.

    Science.gov (United States)

    Liu, Cui; Morse, Audra; Rainwater, Ken; Song, Lianfa

    2014-01-01

    Concentration polarization in narrow reverse osmosis channels with parabolic crossflow was numerically simulated with finite different equations related to permeate velocity, crossflow velocity, average salt concentration, and wall salt concentration. A significant new theoretical development was the determination of two correction functions, F2 and F3, in the governing equation for average salt concentration. Simulations of concentration polarization under various conditions were then presented to describe the features of the new model as well as discussions about the differences of concentration polarizations of the more realistic parabolic flow with those when plug flow or shear flow was assumed. The situations in which the simpler models based on shear or plug flow can be used were indicated. Concentration polarization was also simulated for various conditions to show the applicability of the model and general features of concentration polarization in a narrow, long reverse osmosis channel.

  15. Effects of subfilter velocity modelling on dispersed phase in LES of heated channel flow

    International Nuclear Information System (INIS)

    A non-isothermal turbulent flow with the dispersed phase is modelled using the Large Eddy Simulation (LES) approach for fluid, one-way coupled with the equations of point-particle evolution. The channel is heated at both walls and isoflux boundary conditions are applied for fluid. Particle velocity and thermal statistics are computed. Of particular interest are the r.m.s. profiles and the probability density function of particle temperature in the near-wall region. We compare our findings with available reference data for particle-laden, heated channel flow. Moreover, an open issue in LES is the influence of non-resolved (residual) scales of fluid velocity and temperature fields on particles. In the present contribution, we apply a stochastic model for subfilter fluid velocity at the particle positions that aims at reconstructing the effects of the smallest scales of turbulence on particle dynamics. We analyse the impact of this model on particle thermal statistics.

  16. REAL-TIME FLOOD FORECASTING MODELING OF 1D UNSTEADY CHANNEL FLOW AND KALMAN FILTER

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The model of 1D unsteady channel flow combined with the Kalmanfilter for real-time channel flood forecasting was attempted in this study. The suitable upstream and downstream boundary conditions were suggested. The system equation was given by the linearization of the finitedifference equations of the mass conservation and momentum equations as well as the boundary conditions. In the Kalman filter updating model, because the number of measurement variable is less then that of state-space variables, the measurement error covariance matrix could be estimated in real time through the innovation sequence, and the system error covariance matrix needs to be estimated preliminarily. A real example of flood forecasting in the Huaihe River was given to explain how the method works. The results show that the model is reasonable and effective.

  17. Effects of subfilter velocity modelling on dispersed phase in LES of heated channel flow

    Science.gov (United States)

    Pozorski, Jacek; Knorps, Maria; Łuniewski, Mirosław

    2011-12-01

    A non-isothermal turbulent flow with the dispersed phase is modelled using the Large Eddy Simulation (LES) approach for fluid, one-way coupled with the equations of point-particle evolution. The channel is heated at both walls and isoflux boundary conditions are applied for fluid. Particle velocity and thermal statistics are computed. Of particular interest are the r.m.s. profiles and the probability density function of particle temperature in the near-wall region. We compare our findings with available reference data for particle-laden, heated channel flow. Moreover, an open issue in LES is the influence of non-resolved (residual) scales of fluid velocity and temperature fields on particles. In the present contribution, we apply a stochastic model for subfilter fluid velocity at the particle positions that aims at reconstructing the effects of the smallest scales of turbulence on particle dynamics. We analyse the impact of this model on particle thermal statistics.

  18. The Flatworm Macrostomum lignano Is a Powerful Model Organism for Ion Channel and Stem Cell Research

    Directory of Open Access Journals (Sweden)

    Daniil Simanov

    2012-01-01

    Full Text Available Bioelectrical signals generated by ion channels play crucial roles in many cellular processes in both excitable and nonexcitable cells. Some ion channels are directly implemented in chemical signaling pathways, the others are involved in regulation of cytoplasmic or vesicular ion concentrations, pH, cell volume, and membrane potentials. Together with ion transporters and gap junction complexes, ion channels form steady-state voltage gradients across the cell membranes in nonexcitable cells. These membrane potentials are involved in regulation of such processes as migration guidance, cell proliferation, and body axis patterning during development and regeneration. While the importance of membrane potential in stem cell maintenance, proliferation, and differentiation is evident, the mechanisms of this bioelectric control of stem cell activity are still not well understood, and the role of specific ion channels in these processes remains unclear. Here we introduce the flatworm Macrostomum lignano as a versatile model organism for addressing these topics. We discuss biological and experimental properties of M. lignano, provide an overview of the recently developed experimental tools for this animal model, and demonstrate how manipulation of membrane potential influences regeneration in M. lignano.

  19. Size graded sediment dynamics: from the processes characterization to the transport modelling in the English Channel

    International Nuclear Information System (INIS)

    The purpose of this work is the implementation of a sediment transport model in the English Channel. The design of such a model requires the identification of the physical processes, their modelling and their in-situ validation. Because of the sedimentary particularities of the study area, modelling of the mechanical behaviour of a non uniform mixture of sediments and particularly of the fine grains within a coarse matrix is required. This study focused on the characterization of the relevant processes by acquisition of experimental and in-situ data. Data acquired in hydro-sedimentary conditions comparable to those found in the English Channel are scarce. A new instrument and image processing technique were specifically conceived and implemented in-situ to observe and measure, with a high temporal resolution, the dynamics of a strongly heterogeneous mixture of particles in a grain-size scale. The data collected compared well with several existing formulations. One of these formulations was chosen to be adapted. The transfer dynamics of fine grains in coarse sediments and their depth of penetration were acquired from stratigraphic samples. The sediment transport model deals with multi-size grains and multi sedimentary layers, it is forced by swell and currents, and accounts for bead load and suspended load transports. It was applied to realistic scenarios for the English Channel. (author)

  20. Sequence-Based Pronunciation Variation Modeling for Spontaneous ASR Using a Noisy Channel Approach

    Science.gov (United States)

    Hofmann, Hansjörg; Sakti, Sakriani; Hori, Chiori; Kashioka, Hideki; Nakamura, Satoshi; Minker, Wolfgang

    The performance of English automatic speech recognition systems decreases when recognizing spontaneous speech mainly due to multiple pronunciation variants in the utterances. Previous approaches address this problem by modeling the alteration of the pronunciation on a phoneme to phoneme level. However, the phonetic transformation effects induced by the pronunciation of the whole sentence have not yet been considered. In this article, the sequence-based pronunciation variation is modeled using a noisy channel approach where the spontaneous phoneme sequence is considered as a “noisy” string and the goal is to recover the “clean” string of the word sequence. Hereby, the whole word sequence and its effect on the alternation of the phonemes will be taken into consideration. Moreover, the system not only learns the phoneme transformation but also the mapping from the phoneme to the word directly. In this study, first the phonemes will be recognized with the present recognition system and afterwards the pronunciation variation model based on the noisy channel approach will map from the phoneme to the word level. Two well-known natural language processing approaches are adopted and derived from the noisy channel model theory: Joint-sequence models and statistical machine translation. Both of them are applied and various experiments are conducted using microphone and telephone of spontaneous speech.

  1. One-dimensional pressure transfer models for acoustic-electric transmission channels

    Science.gov (United States)

    Wilt, K. R.; Lawry, T. J.; Scarton, H. A.; Saulnier, G. J.

    2015-09-01

    A method for modeling piezoelectric-based ultrasonic acoustic-electric power and data transmission channels is presented. These channels employ piezoelectric disk transducers to convey signals across a series of physical layers using ultrasonic waves. This model decomposes the mechanical pathway of the signal into individual ultrasonic propagation layers which are generally independent of the layer's adjacent domains. Each layer is represented by a two-by-two traveling pressure wave transfer matrix which relates the forward and reverse pressure waves on one side of the layer to the pressure waves on the opposite face, where each face is assumed to be in contact with a domain of arbitrary reference acoustic impedance. A rigorous implementation of ultrasonic beam spreading is introduced and implemented within applicable domains. Compatible pressure-wave models for piezoelectric transducers are given, which relate the electric voltage and current interface of the transducer to the pressure waves on one mechanical interface while also allowing for passive acoustic loading of the secondary mechanical interface. It is also shown that the piezoelectric model's electrical interface is compatible with transmission line parameters (ABCD-parameters), allowing for connection of electronic components and networks. The model is shown to be capable of reproducing the behavior of realistic physical channels.

  2. Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model

    Directory of Open Access Journals (Sweden)

    R. Larsson

    2015-10-01

    Full Text Available We present a comparison of a reference and a fast radiative transfer model using numerical weather prediction profiles for the Zeeman-affected high altitude Special Sensor Microwave Imager/Sounder channels 19–22. We find that the models agree well for channels 21 and 22 compared to the channels' system noise temperatures (1.9 and 1.3 K, respectively and the expected profile errors at the affected altitudes (estimated to be around 5 K. For channel 22 there is a 0.5 K average difference between the models, with a standard deviation of 0.24 K for the full set of atmospheric profiles. Same channel, there is 1.2 K in average between the fast model and the sensor measurement, with 1.4 K standard deviation. For channel 21 there is a 0.9 K average difference between the models, with a standard deviation of 0.56 K. Same channel, there is 1.3 K in average between the fast model and the sensor measurement, with 2.4 K standard deviation. We consider the relatively small model differences as a validation of the fast Zeeman effect scheme for these channels. Both channels 19 and 20 have smaller average differences between the models (at below 0.2 K and smaller standard deviations (at below 0.4 K when both models use a two-dimensional magnetic field profile. However, when the reference model is switched to using a full three-dimensional magnetic field profile, the standard deviation to the fast model is increased to almost 2 K due to viewing geometry dependencies causing up to ± 7 K differences near the equator. The average differences between the two models remain small despite changing magnetic field configurations. We are unable to compare channels 19 and 20 to sensor measurements due to limited altitude range of the numerical weather prediction profiles. We recommended that numerical weather prediction software using the fast model takes the available fast Zeeman scheme into account for data assimilation of the affected sensor channels to better

  3. Linear Modeling and Regulation Quality Analysis for Hydro-Turbine Governing System with an Open Tailrace Channel

    Directory of Open Access Journals (Sweden)

    Jiandong Yang

    2015-10-01

    Full Text Available On the basis of the state–space method (SSM, a novel linear mathematical model of the unsteady flow for the tailrace system with an open channel is proposed. This novel model is an elastic linearized model of water hammer. The validity of the model has been verified by several examples of numerical simulation, which are based on a finite difference technique. Then, the complete mathematical model for the hydro-turbine governing system of hydropower station with an open tailrace channel, which is used for simulating the transient process of the hydro-turbine governing system under load disturbance, is established by combining the models of hydro-turbine, generator, governor and open tailrace channel. Finally, according to the complete model, the regulation quality for hydro-turbine governing system with an open tailrace channel under load disturbance is studied, and the effects of open tailrace channel and tailrace surge tank on regulation quality are analyzed. The results indicate that: The open tailrace channel has a strong influence on the regulation quality by observing the water level fluctuations in tailrace surge tank. The surge shows a piecewise periodical change along with the variation in the length of an open channel. The open tailrace channel can be used to improve the regulation quality of hydro-turbine governing system.

  4. Physical Hydraulic Model of Side-Channel Spillway of Lambuk DAM, Bali

    Science.gov (United States)

    Harifa, A. C.; Sholichin, M.; Othman, F. B.

    2013-12-01

    The spillway is among the most important structures of a dam project. A spillway is designed to prevent overtopping of a dam at a place that is not designed for overtopping. Side-channel spillways are commonly used to release water flow from a reservoir in places where the sides are steep and have a considerable height above the dam. Experimental results were collected with a hydraulic model of the side-channel spillway for releasing the peak overflow of Lambuk Dam. This dam is, located on the Lambuk River, which is a tributary of the Yeh Hoo River ~ 34.6 km north of Denpasar on the island of Bali. The bituminous geomembrane faced dam is 24 m in height, with a 35-m wide spillway. The length of the side channel is 35 m long, with 58 m of transition channel, 67.37 m of chuteway channel and 22.71 m of stilling basin. The capacity of the spillway is 231.91 m3/s and the outlet works capacity is 165.28 m3/s. The reservoir is designed for irrigation and water supply. The purpose of this study was to optimize the designed of the structure and to ensure its safe operation. In hydraulic model may help the decision-makers to visualize the flow field before selecting a ';suitable' design. The hydraulic model study was performed to ensure passage of the maximum discharge at maximum reservoir capacity; to study the spillway approach conditions, water surface profiles, and flow patterns in the chuteway; and to reveal potential demerits of the proposed hydraulic design of various structures and explore solutions. The model was constructed at 1 : 40 scale, Reservoir topography was modeled using concrete, the river bed using sand and some gravel, the river berm using concrete, and the spillway and channel using Plexiglas. Water was measured using Rectangular contracted weir. Design floods (with return period in year) were Q2 = 111.40 m3/s, Q5 = 136.84 m3/s, Q10 = 159.32 m3/s, Q25 = 174.61 m3/s, Q50 = 185.13 m3/s, Q100 = 198.08 m3/s, Q200 = 210.55 m3/s, Q1000 = 231.91 m3/s and the

  5. M2 Proton Channel: Toward a Model of a Primitive Proton Pump

    Science.gov (United States)

    Wei, Chenyu; Pohorille, Andrew

    2015-06-01

    Transmembrane proton transfer was essential to early cellular systems in order to transduce energy for metabolic functions. The reliable, efficient and controlled generation of proton gradients became possible only with the emergence of active proton pumps. On the basis of features shared by most modern proton pumps we identify the essential mechanistic steps in active proton transport. Further, we discuss the mechanism of action of a small, transmembrane M2 proton channel from influenza A virus as a model for proton transport in protocells. The M2 channel is a 94-residue long, α-helical tetramer that is activated at low pH and exhibits high selectivity and directionality. A shorter construct, built of transmembrane fragments that are only 24 amino acids in length, exhibits very similar proton transport properties. Molecular dynamics simulations on the microsecond time-scale carried out for the M2 channel provided atomic level details on the activation of the channel in response to protonation of the histidine residue, His37. The pathway of proton conduction is mediated by His37, which accepts and donates protons at different interconverting conformation states when pH is lower than 6.5. The Val27 and Trp41 gates and the salt bridge between Asp44 and Arg45 further enhance the directionality of proton transport. It is argued that the architecture and the mechanism of action similar to that found in the M2 channel might have been the perfect starting point for evolution towards the earliest proton pumps, indicating that active proton transport could have readily emerged from simple, passive proton channels.

  6. Puget Sound 1/3 arc-second MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  7. Puget Sound 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  8. A Generic 1D Forward Modeling and Inversion Algorithm for TEM Sounding with an Arbitrary Horizontal Loop

    Science.gov (United States)

    Li, Zhanhui; Huang, Qinghua; Xie, Xingbing; Tang, Xingong; Chang, Liao

    2016-08-01

    We present a generic 1D forward modeling and inversion algorithm for transient electromagnetic (TEM) data with an arbitrary horizontal transmitting loop and receivers at any depth in a layered earth. Both the Hankel and sine transforms required in the forward algorithm are calculated using the filter method. The adjoint-equation method is used to derive the formulation of data sensitivity at any depth in non-permeable media. The inversion algorithm based on this forward modeling algorithm and sensitivity formulation is developed using the Gauss-Newton iteration method combined with the Tikhonov regularization. We propose a new data-weighting method to minimize the initial model dependence that enhances the convergence stability. On a laptop with a CPU of i7-5700HQ@3.5 GHz, the inversion iteration of a 200 layered input model with a single receiver takes only 0.34 s, while it increases to only 0.53 s for the data from four receivers at a same depth. For the case of four receivers at different depths, the inversion iteration runtime increases to 1.3 s. Modeling the data with an irregular loop and an equal-area square loop indicates that the effect of the loop geometry is significant at early times and vanishes gradually along the diffusion of TEM field. For a stratified earth, inversion of data from more than one receiver is useful in noise reducing to get a more credible layered earth. However, for a resistive layer shielded below a conductive layer, increasing the number of receivers on the ground does not have significant improvement in recovering the resistive layer. Even with a down-hole TEM sounding, the shielded resistive layer cannot be recovered if all receivers are above the shielded resistive layer. However, our modeling demonstrates remarkable improvement in detecting the resistive layer with receivers in or under this layer.

  9. Pitch Based Sound Classification

    DEFF Research Database (Denmark)

    Nielsen, Andreas Brinch; Hansen, Lars Kai; Kjems, U

    2006-01-01

    A sound classification model is presented that can classify signals into music, noise and speech. The model extracts the pitch of the signal using the harmonic product spectrum. Based on the pitch estimate and a pitch error measure, features are created and used in a probabilistic model with soft......-max output function. Both linear and quadratic inputs are used. The model is trained on 2 hours of sound and tested on publicly available data. A test classification error below 0.05 with 1 s classification windows is achieved. Further more it is shown that linear input performs as well as a quadratic......, and that even though classification gets marginally better, not much is achieved by increasing the window size beyond 1 s....

  10. Linear stability analysis of flow instabilities with a nodalized reduced order model in heated channel

    International Nuclear Information System (INIS)

    The prime objective of the presented work is to develop a Nodalized Reduced Order Model (NROM) to carry linear stability analysis of flow instabilities in a two-phase flow system. The model is developed by dividing the single phase and two-phase region of a uniformly heated channel into N number of nodes followed by time dependent spatial linear approximations for single phase enthalpy and two-phase quality between the consecutive nodes. Moving boundary scheme has been adopted in the model, where all the node boundaries vary with time due to the variation of boiling boundary inside the heated channel. Using a state space approach, the instability thresholds are delineated by stability maps plotted in parameter planes of phase change number (Npch) and subcooling number (Nsub). The prime feature of the present model is that, though the model equations are simpler due to presence of linear-linear approximations for single phase enthalpy and two-phase quality, yet the results are in good agreement with the existing models (Karve [33]; Dokhane [34]) where the model equations run for several pages and experimental data (Solberg [41]). Unlike the existing ROMs, different two-phase friction factor multiplier correlations have been incorporated in the model. The applicability of various two-phase friction factor multipliers and their effects on stability behaviour have been depicted by carrying a comparative study. It is also observed that the Friedel model for friction factor calculations produces the most accurate results with respect to the available experimental data. (authors)

  11. Poisson-Nernst-Planck-Fermi theory for modeling biological ion channels.

    Science.gov (United States)

    Liu, Jinn-Liang; Eisenberg, Bob

    2014-12-14

    A Poisson-Nernst-Planck-Fermi (PNPF) theory is developed for studying ionic transport through biological ion channels. Our goal is to deal with the finite size of particle using a Fermi like distribution without calculating the forces between the particles, because they are both expensive and tricky to compute. We include the steric effect of ions and water molecules with nonuniform sizes and interstitial voids, the correlation effect of crowded ions with different valences, and the screening effect of water molecules in an inhomogeneous aqueous electrolyte. Including the finite volume of water and the voids between particles is an important new part of the theory presented here. Fermi like distributions of all particle species are derived from the volume exclusion of classical particles. Volume exclusion and the resulting saturation phenomena are especially important to describe the binding and permeation mechanisms of ions in a narrow channel pore. The Gibbs free energy of the Fermi distribution reduces to that of a Boltzmann distribution when these effects are not considered. The classical Gibbs entropy is extended to a new entropy form - called Gibbs-Fermi entropy - that describes mixing configurations of all finite size particles and voids in a thermodynamic system where microstates do not have equal probabilities. The PNPF model describes the dynamic flow of ions, water molecules, as well as voids with electric fields and protein charges. The model also provides a quantitative mean-field description of the charge/space competition mechanism of particles within the highly charged and crowded channel pore. The PNPF results are in good accord with experimental currents recorded in a 10(8)-fold range of Ca(2+) concentrations. The results illustrate the anomalous mole fraction effect, a signature of L-type calcium channels. Moreover, numerical results concerning water density, dielectric permittivity, void volume, and steric energy provide useful details to study

  12. From sounds to words: a neurocomputational model of adaptation, inhibition and memory processes in auditory change detection.

    Science.gov (United States)

    Garagnani, Max; Pulvermüller, Friedemann

    2011-01-01

    Most animals detect sudden changes in trains of repeated stimuli but only some can learn a wide range of sensory patterns and recognise them later, a skill crucial for the evolutionary success of higher mammals. Here we use a neural model mimicking the cortical anatomy of sensory and motor areas and their connections to explain brain activity indexing auditory change and memory access. Our simulations indicate that while neuronal adaptation and local inhibition of cortical activity can explain aspects of change detection as observed when a repeated unfamiliar sound changes in frequency, the brain dynamics elicited by auditory stimulation with well-known patterns (such as meaningful words) cannot be accounted for on the basis of adaptation and inhibition alone. Specifically, we show that the stronger brain responses observed to familiar stimuli in passive oddball tasks are best explained in terms of activation of memory circuits that emerged in the cortex during the learning of these stimuli. Such memory circuits, and the activation enhancement they entail, are absent for unfamiliar stimuli. The model illustrates how basic neurobiological mechanisms, including neuronal adaptation, lateral inhibition, and Hebbian learning, underlie neuronal assembly formation and dynamics, and differentially contribute to the brain's major change detection response, the mismatch negativity. PMID:20728545

  13. Amplitude and frequency modulation control of sound production in a mechanical model of the avian syrinx

    DEFF Research Database (Denmark)

    Elemans, Coen; Muller, Mees; Larsen, Ole Næsbye;

    2009-01-01

    resembles the ‘starling resistor', a collapsible tube model, and consists of a tube with a single membrane in its casing, suspended in an external pressure chamber and driven by various pressure patterns. With this design, we can separately control ‘bronchial' pressure and tension in the oscillating...

  14. Analytic model of a two wire thermal sensor for flow and sound measurements

    NARCIS (Netherlands)

    Honschoten, van J.W.; Krijnen, G.J.M.; Svetovoy, V.B.; Bree, de H.E.; Elwenspoek, M.C.

    2004-01-01

    The Microflown is an acoustic sensor that measures particle velocity instead of pressure, as conventional microphones do. This paper presents an analytical model describing the physical processes that govern the behaviour of the sensor and determine its sensitivity. Forced convection by an acoustic

  15. Geostatistical modeling of sound propagation: Principles and a field application experiment

    NARCIS (Netherlands)

    Baume, O.P.; Gauvreau, B.; Berengier, M.; Junker, F.; Wackernagel, H.; Chiles, J.P.

    2009-01-01

    The assessment of noise sources for environmental purposes requires reliable methods for mapping. Numerical models are well adapted for sophisticated simulations and sensitivity analyses; however, real-time mapping of large frequency bands must be based on fast and acceptable computations and honor

  16. Channel Modeling of Human Somatosensory Nanonetwork: Body Discriminative Touch and Proprioception Perspective

    Directory of Open Access Journals (Sweden)

    Partha Pratim Ray

    2013-10-01

    Full Text Available Nanonetwork design and analysis has become a very interesting topic in recent years. Though this area of research is in its formative stage, it definitely posses a strong integrity in finding out numerous applications in medical and allied sciences. Nanonetworking is indeed a nature built foundation which comprises human intra body communications. Somatosensory system is the one of the critical and must have systems of human body. This literature concentrates on the body discriminative touch and proprioception mechanism of somatosensory system. This particular system is well architecture by medial lemniscal pathway, in human body for transduction of touch and proprioceptive information. This paper seeks out the novel communication channel model of somatosensory system. The working principle of the channel model is established by an equivalent Moore machine. A novel algorithm MLP is proposed after its name, medial lemniscal pathway. A novel naomachine and appropriate processing unit are also devised, based on the automaton.

  17. A theoretical model of turbulent fiber suspension and its application to the channel flow

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of fibers.In order to close the above equations,the equation of probability distribution function for mean fiber orientation is also derived.The theoretical model is applied to the turbulent channel flow and the corresponding equations are solved numerically.The numerical results are verified by comparisons with the experimental ones.The effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are analyzed.Based on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

  18. Accurate Simulation of 802.11 Indoor Links: A "Bursty" Channel Model Based on Real Measurements

    Directory of Open Access Journals (Sweden)

    Agüero Ramón

    2010-01-01

    Full Text Available We propose a novel channel model to be used for simulating indoor wireless propagation environments. An extensive measurement campaign was carried out to assess the performance of different transport protocols over 802.11 links. This enabled us to better adjust our approach, which is based on an autoregressive filter. One of the main advantages of this proposal lies in its ability to reflect the "bursty" behavior which characterizes indoor wireless scenarios, having a great impact on the behavior of upper layer protocols. We compare this channel model, integrated within the Network Simulator (ns-2 platform, with other traditional approaches, showing that it is able to better reflect the real behavior which was empirically assessed.

  19. Silent Expectations: Dynamic Causal Modeling of Cortical Prediction and Attention to Sounds That Weren't

    Science.gov (United States)

    Noreika, Valdas; Gueorguiev, David; Shtyrov, Yury; Bekinschtein, Tristan A.; Henson, Richard

    2016-01-01

    There is increasing evidence that human perception is realized by a hierarchy of neural processes in which predictions sent backward from higher levels result in prediction errors that are fed forward from lower levels, to update the current model of the environment. Moreover, the precision of prediction errors is thought to be modulated by attention. Much of this evidence comes from paradigms in which a stimulus differs from that predicted by the recent history of other stimuli (generating a so-called “mismatch response”). There is less evidence from situations where a prediction is not fulfilled by any sensory input (an “omission” response). This situation arguably provides a more direct measure of “top-down” predictions in the absence of confounding “bottom-up” input. We applied Dynamic Causal Modeling of evoked electromagnetic responses recorded by EEG and MEG to an auditory paradigm in which we factorially crossed the presence versus absence of “bottom-up” stimuli with the presence versus absence of “top-down” attention. Model comparison revealed that both mismatch and omission responses were mediated by increased forward and backward connections, differing primarily in the driving input. In both responses, modeling results suggested that the presence of attention selectively modulated backward “prediction” connections. Our results provide new model-driven evidence of the pure top-down prediction signal posited in theories of hierarchical perception, and highlight the role of attentional precision in strengthening this prediction. SIGNIFICANCE STATEMENT Human auditory perception is thought to be realized by a network of neurons that maintain a model of and predict future stimuli. Much of the evidence for this comes from experiments where a stimulus unexpectedly differs from previous ones, which generates a well-known “mismatch response.” But what happens when a stimulus is unexpectedly omitted altogether? By measuring the brain

  20. Modeling hysteresis observed in the human erythrocyte voltage-dependent cation channel

    DEFF Research Database (Denmark)

    Flyvbjerg, Henrik; Gudowska-Nowak, Ewa; Christophersen, Palle;

    2012-01-01

    The non-selective voltage-activated cation channel from human red cells, which is activated at depolarizing potentials, has been shown to exhibit counter-clockwise gating hysteresis. Here, we analyze this phenomenon with the simplest possible phenomenological models. Specifically, the hysteresis...... cycle, including its direction, is reproduced by a model with 2×2 discrete states: the normal open/closed states and two different states of "gate tension". Rates of transitions between the two branches of the hysteresis curve are modeled with single-barrier kinetics by introducing a real...

  1. Isovector channel of quark-meson-coupling model and its effect on symmetry energy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.B. [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Qi, C. [KTH (Royal Institute of Technology), Alba Nova University Center, SE-10691 Stockholm (Sweden); Xu, F.R., E-mail: frxu@pku.edu.cn [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Center for Theoretical Nuclear Physics, National Laboratory for Heavy Ion Physics, Lanzhou 730000 (China)

    2011-08-15

    The non-relativistic approximation of the quark-meson-coupling model has been discussed and compared with the Skyrme-Hartree-Fock model which includes spin exchanges. Calculations show that the spin-exchange interaction has important effect on the descriptions of finite nuclei and nuclear matter through the Fock exchange. Also in the quark-meson-coupling model, it is the Fock exchange that leads to a nonlinear density-dependent isovector channel and changes the density-dependent behavior of the symmetry energy.

  2. Choline Modulation of the Aβ P1-40 Channel Reconstituted into a Model Lipid Membrane

    Directory of Open Access Journals (Sweden)

    Daniela Meleleo

    2010-01-01

    Full Text Available Nicotinic acetylcholine receptors (AChRs, implicated in memory and learning, in subjects affected by Alzheimer's disease result altered. Stimulation of α7-nAChRs inhibits amyloid plaques and increases ACh release. β-amyloid peptide (AβP forms ion channels in the cell and model phospholipid membranes that are retained responsible in Alzheimer disease. We tested if choline, precursor of ACh, could affect the AβP1-40 channels in oxidized cholesterol (OxCh and in palmitoyl-oleoyl-phosphatidylcholine (POPC:Ch lipid bilayers. Choline concentrations of 5 × 10−11 M–1.5 × 10−8 M added to the cis- or trans-side of membrane quickly increased AβP1-40 ion channel frequency (events/min and ion conductance in OxCh membranes, but not in POPC:Ch membranes. Circular Dichroism (CD spectroscopy shows that after 24 and 48 hours of incubation with AβP1-40, choline stabilizes the random coil conformation of the peptide, making it less prone to fibrillate. These actions seem to be specific in that ACh is ineffective either in solution or on AβP1-40 channel incorporated into PLMs.

  3. A mixed "Biot-Shell" analytical model for the prediction of sound transmission through a sandwich cylinder with a poroelastic core

    Science.gov (United States)

    Magniez, Julien; Hamdi, Mohamed Ali; Chazot, Jean-Daniel; Troclet, Bernard

    2016-01-01

    A mixed "Biot-Shell" analytical model dedicated to the calculation of sound transmission through an infinite sandwich cylinder composed of orthotropic skins and a poroelastic core is proposed in this paper. The motion of the two thin orthotropic skins is described with the first-order shear deformation theory while the poroelastic core is modeled with the full 3D Biot's theory. The main advantage of this mixed model is that it takes into account the elasticity effects related to the skeleton of the poroelastic material. First, an analytical expression of the displacement and stress fields of the solid and fluid phases in the poroelastic layer is presented in cylindrical coordinates. Then, the poroelastic core transfer matrix relating the displacements and the stresses at the two common interfaces between the core and the skins is calculated. The coupling of the two skins is then made using the modal transfer matrix of the core, leading to the global dynamic equilibrium of the sandwich cylinder. The proposed model is finally used to calculate the sound Transmission Loss (TL) of infinite cylinders excited by an incident plane wave. Excellent agreement is observed in comparison with a finite element model. The usefulness of Biot's model in this type of problem is demonstrated by comparing the results with those obtained with equivalent fluid models. The mixed "Biot-Shell" analytical model is finally used to demonstrate the influence of the structural damping of each layer and to study the sound transmission in different configurations.

  4. Distributed hydrological modeling with channel network flow of a forestry drained peatland site

    Science.gov (United States)

    Haahti, Kersti; Warsta, Lassi; Kokkonen, Teemu; Younis, Bassam A.; Koivusalo, Harri

    2016-01-01

    Peatland drainage has been an important component of forestry management in the boreal zone and the resulting ditch networks are maintained regularly to sustain forest productivity. In Finland, this is recognized as the most detrimental forestry practice increasing diffuse loads of suspended solids. Alongside forestry management on peatlands, interest in peatland restoration has grown lately. Distributed hydrological modeling has the potential to address these matters by recognizing relevant physical mechanisms and identifying most suitable strategies for mitigating undesired outcomes. This study investigates the utility of such a modeling approach in a drained peatland forest environment. To provide a suitable tool for this purpose, we coupled channel network flow to the three-dimensional distributed hydrological model FLUSH. The resulting model was applied to a 5.2 ha drained peatland forest catchment in Eastern Finland. The model was calibrated and validated using field measurements obtained over frost-free periods of five months. The application showed that distributed modeling can disentangle the importance of spatial factors on local soil moisture conditions, which is significant as peatland drainage aims to control these conditions. In our application, we limited the spatial aspect to the topography and the drainage network, and found that the drainage configuration had a clear effect on the spatial soil moisture patterns but that the effect was less pronounced during the wetter summer. Future applications of distributed modeling in this field comprises investigating the impacts of other spatial factors, modeling channel erosion and solid transport to address strategies for their mitigation, and evaluating restoration schemes.

  5. Cysteine Mutagenesis and Computer Modeling of the S6 Region of an Intermediate Conductance IKCa Channel

    OpenAIRE

    Simoes, Manuel; Garneau, Line; Klein, Hélène; Banderali, Umberto; Hobeila, Fadi; Roux, Benoit; Parent, Lucie; Sauvé, Rémy

    2002-01-01

    Cysteine-scanning mutagenesis (SCAM) and computer-based modeling were used to investigate key structural features of the S6 transmembrane segment of the calcium-activated K+ channel of intermediate conductance IKCa. Our SCAM results show that the interaction of [2-(trimethylammonium)ethyl] methanethiosulfonate bromide (MTSET) with cysteines engineered at positions 275, 278, and 282 leads to current inhibition. This effect was state dependent as MTSET appeared less effective at inhibiting IKCa...

  6. A software platform for continuum modeling of ion channels based on unstructured mesh

    International Nuclear Information System (INIS)

    Most traditional continuum molecular modeling adopted finite difference or finite volume methods which were based on a structured mesh (grid). Unstructured meshes were only occasionally used, but an increased number of applications emerge in molecular simulations. To facilitate the continuum modeling of biomolecular systems based on unstructured meshes, we are developing a software platform with tools which are particularly beneficial to those approaches. This work describes the software system specifically for the simulation of a typical, complex molecular procedure: ion transport through a three-dimensional channel system that consists of a protein and a membrane. The platform contains three parts: a meshing tool chain for ion channel systems, a parallel finite element solver for the Poisson–Nernst–Planck equations describing the electrodiffusion process of ion transport, and a visualization program for continuum molecular modeling. The meshing tool chain in the platform, which consists of a set of mesh generation tools, is able to generate high-quality surface and volume meshes for ion channel systems. The parallel finite element solver in our platform is based on the parallel adaptive finite element package PHG which wass developed by one of the authors [1]. As a featured component of the platform, a new visualization program, VCMM, has specifically been developed for continuum molecular modeling with an emphasis on providing useful facilities for unstructured mesh-based methods and for their output analysis and visualization. VCMM provides a graphic user interface and consists of three modules: a molecular module, a meshing module and a numerical module. A demonstration of the platform is provided with a study of two real proteins, the connexin 26 and hemolysin ion channels. (paper)

  7. PLUGM: a coupled thermal-hydraulic computer model for freezing melt flow in a channel

    International Nuclear Information System (INIS)

    PLUGM is a coupled thermal-hydraulic computer model for freezing liquid flow and plugging in a cold channel. PLUGM is being developed at Sandia National Laboratories for applications in Sandia's ex-vessel Core Retention Concept Assessment Program and in Sandia's LMFBR Transition Phase Program. The purpose of this paper is to introduce PLUGM and demonstrate how it can be used in the analysis of two of the core retention concepts under investigation at Sandia: refractory brick crucibles and particle beds

  8. Governing factors to determine types of submarine fans: Consideration from the model of equilibrium profile of submarine channels

    Science.gov (United States)

    Naruse, H.

    2015-12-01

    It has been known that submarine fans are diverse in constitutive architectural elements. Leveed channels are common architectural elements of submarine fans but some of submarine fans lack such self-constructive channels. Also, frontal splays that develops at the end of channels cannot be observed in all of submarine fans. Several researches suggested that this diversity of submarine fans is originated from attributes of sediment supply such as ratio between sand and mud. However, quantitative investigation of these phase changes in types of submarine fans has not been explored yet. Here, this study aims to consider deterministic parameters that govern types of submarine fans, using a theoretical model that assumes submarine channel are in equilibrium condition. The model is based on the 4 equation model of turbidity currents that considers conservation of turbulent kinetic energy. The equilibrium profile is here defined as profiles where turbidity currents are bypassing or depositing uniformly. 1D momentum conservation is considered, and grain-size distribution is approximated to two size classes: channel-forming sands and levee-forming muddy sediments. Widths of channel and levees are calculated from empirical hydraulic geometry. The model predicts length of leveed channels in the equilibrium condition and hydraulic conditions at downstream end of the channels. As a result, depending on boundary condition at upstream end of channels, three possible cases were recognized: (A) submarine channels in which levee-forming muddy sediments are run out at the end of channel, (B) submarine channels in which sandy sediments are run out, and (C) no possible equilibrium profiles that satisfy empirical hydraulic geometry for given boundary conditions. It can be interpreted that these types of results correspond to submarine channels with/without frontal splays and submarine fans without leveed channels. Essentially three parameters are significant to determine types of

  9. Sound knowledge

    DEFF Research Database (Denmark)

    Kauffmann, Lene Teglhus

    of anthropological debates and theories about knowledge. This provides a perspective from which to look critically at ‘evidence’ and identify its multiple meanings and uses in policymaking. The analysis also leads to a refinement of anthropological concepts of knowledge. ‘Evidence’ is purported to be the objective...... and ideologies explicit. Furthermore, in relation to an anthropology of knowledge, sound knowledge also offers a reconsideration of the way anthropologists study knowledge, as it specifies that studying knowledge for anthropologists means studying what people consider as knowledge, in what circumstances......The thesis is about the conceptualisation of knowledge associated with ‘evidence’. In the Danish society, there is a proliferating demand for ‘evidence’, which started as the basis of practices in medicine and has spread into social work, education and most policymaking arenas. The aim...

  10. An integrated 3D sound intensity sensor using four-wire particle velocity sensors: II. Modelling

    International Nuclear Information System (INIS)

    The sensitivity of a micromachined acoustic sensor consisting of four hot-wire particle velocity sensors is analysed theoretically and experimentally. The device and its fabrication have been presented in part 1 of this paper (Yntema et al 2010 J. Micromech. Microeng. 20 015042). A relatively straightforward analytical model is presented that describes both the air flow around the probe and the temperature profile around the heated wires. The presence of the chip surface near the heated wires influences the fluid flow around the wires, while it also affects the temperature distribution in the probe by altering the direction of heat transport. Both effects result into a modified angular dependence of the sensor sensitivity with respect to the normal 'figure-of-eight' figure of the response. By means of finite elements software, the thermal and the acoustic flow behaviour of the sensor are also investigated numerically, both effects together and each apart, and the results are compared to the analytical model. Comparison with the experimental data is presented, showing that the model is appropriate to describe the angular dependence and the magnitude of the sensor response. It is concluded that the perturbed air flow due to the chip surface is the dominant reason for the observed angular sensitivity

  11. A granular-continuum model of channelization in sedimentary layers by sub-surface flow

    Science.gov (United States)

    Yadav, Vikrant; Kudrolli, Arshad

    2014-03-01

    We discuss experiments where channels form in a quasi-two dimensional bed of consolidated granular particles by fluid flow. A continuum three phase model was developed recently [A. Mahadevan, A.V. Orpe, A. Kudrolli, and L. Mahadevan, EPL, 2012] which shows that channels can develop from small differences in packing in an otherwise homogeneous medium which leads to increased porosity and nonlinear feedback. To build on this model, an erodible porous medium composed of millimeter scale grains and Bentonite clay was prepared in a Hele-Shaw cell. The cohesive strength between the grains is directly proportional to the amount of clay binder. When water is pumped through this porous medium, the binder dissolves and loose beads are advected out of the erodible medium, and an initially uniform flow of water through the porous medium gets localized into channels over time. We will discuss the measured integrated rates of erosion as well as the statistical development of heterogeneity and comparison with the three-phase model as a function of binding strength and consolidation of the medium. Supported by DOE Grant No. DE-FG02-13ER16401.

  12. The Time Division Multi-Channel Communication Model and the Correlative Protocol Based on Quantum Time Division Multi-Channel Communication

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Hui; PEI Chang-Xing; NIE Min

    2010-01-01

    @@ Based on the classical time division multi-channel communication theory,we present a scheme of quantum time-division multi-channel communication(QTDMC).Moreover,the model of quantum time division switch(QTDS)and correlative protocol of QTDMC are proposed.The quantum bit error rate(QBER)is analyzed and the QBER simulation test is performed.The scheme shows that the QTDS can carry out multi-user communication through quantum channel,the QBER can also reach the reliability requirement of communication,and the protocol of QTDMC has high practicability and transplantable.The scheme of QTDS may play an important role in the establishment of quantum communication in a large scale in the future.

  13. Experimental high pressure speed of sound and density of (tetralin + n-decane) and (tetralin + n-hexadecane) systems and thermodynamic modeling

    International Nuclear Information System (INIS)

    Highlights: • High pressure speed of sound and density for C10H12, n-C10H22, n-C16H34 mixtures. • High pressure density and excess properties provided. • PFP model better than SAFT but misled pressure effect on speed of sound. • PFP model correlates well excess properties. - Abstract: In this work, speed of sound for n-decane, n-hexadecane and tetralin, as well as for binary mixtures involving these hydrocarbons, were determined at pressures of (0.1, 5, 10, 15, 20 and 25) MPa at temperatures of (313.15, 323.15 and 333.15) K at different compositions. Density data at atmospheric pressure for these same systems were measured experimentally at temperatures of (313.15, 323.15 and 333.15) K. From these results and thermodynamic definitions, the following properties were calculated: density at high pressures, excess molar volume and excess isentropic compressibility. Tetralin, n-decane and n-hexadecane are chemicals asymmetrical in shape, length and chemical nature that can be found in naphtha and kerosene fractions. The influence of these differences on the physical properties of these mixtures was then evaluated. Density and speed of sound data were correlated with Prigogine–Flory–Patterson (PFP) equation of state. The PFP model correlated well experimental densities for pure components but did not correlate so well the speed of sound dependency with pressure. The model calculated well excess properties, with correct signs, magnitudes, and the qualitative effect of pressure and temperature on these properties

  14. A Simple Analytical Model of Coupled Single Flow Channel over Porous Electrode in Vanadium Redox Flow Battery with Serpentine Flow Channel

    CERN Document Server

    Ke, Xinyou; Prahl, Joseph M; Savinell, Robert F

    2016-01-01

    A simple analytical model of a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer) is proposed. This analytical model is derived from Navier-Stokes motion in the flow channel and Darcy-Brinkman model in the porous layer. The continuities of flow velocity and normal stress are applied at the interface between the flow channel and the porous layer. The effects of the inlet volumetric flow rate, thickness of the flow channel and thickness of a typical carbon fiber paper porous layer on the volumetric flow rate within this porous layer are studied. The maximum current density based on the electrolyte volumetric flow rate is predicted, and found to be consistent with reported numerical simulation. It is found that, for a mean inlet flow velocity of 33.3 cm s-1, the analytical maximum current density is estimated to be 377 mA cm-2, which compares favorably with experimental result reported by others of ~400 mA cm-2.

  15. A simple analytical model of coupled single flow channel over porous electrode in vanadium redox flow battery with serpentine flow channel

    Science.gov (United States)

    Ke, Xinyou; Alexander, J. Iwan D.; Prahl, Joseph M.; Savinell, Robert F.

    2015-08-01

    A simple analytical model of a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer) is proposed. This analytical model is derived from Navier-Stokes motion in the flow channel and Darcy-Brinkman model in the porous layer. The continuities of flow velocity and normal stress are applied at the interface between the flow channel and the porous layer. The effects of the inlet volumetric flow rate, thickness of the flow channel and thickness of a typical carbon fiber paper porous layer on the volumetric flow rate within this porous layer are studied. The maximum current density based on the electrolyte volumetric flow rate is predicted, and found to be consistent with reported numerical simulation. It is found that, for a mean inlet flow velocity of 33.3 cm s-1, the analytical maximum current density is estimated to be 377 mA cm-2, which compares favorably with experimental result reported by others of ∼400 mA cm-2.

  16. Non-planar and Non-linear Second Sound Waves in He Ⅱ

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; KIMURA Seiji; MURAKAMI Masahide; WANG Ru-zhu

    2000-01-01

    Non-planar and non-linear second sound wave are experimentally investigated in an open He Ⅱ bath. It is found that second sound wave characterized by a negative tail part in an open He Ⅱ bath is different from that propagating through a channel, and the shape of the negative tail part of second sound wave varies at different location in an open He Ⅱ bath. Theoretical consideration is also carried out based on two-fluid model and vortex evolution equation. It is found that experimental and theoretical results agree rather well with each other. Second sound wave may develop into the thermal shock wave provided that the heat flux is large.

  17. 3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

    Institute of Scientific and Technical Information of China (English)

    Jie ZHOU; Cheng ZENG

    2009-01-01

    The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage.To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows,a hybrid LES-RANS model,which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model,is proposed in the present study.The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel,as well as the downstream region of a branch channel.The LES model was used to simulate the channel diversion region,where turbulent flow characteristics ate complicated.Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence.A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations.This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions.Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.

  18. 3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

    Directory of Open Access Journals (Sweden)

    Jie ZHOU

    2009-09-01

    Full Text Available The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage. To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows, a hybrid LES-RANS model, which combines the large eddy simulation (LES model with the Reynolds-averaged Navier-Stokes (RANS model, is proposed in the present study. The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel, as well as the downstream region of a branch channel. The LES model was used to simulate the channel diversion region, where turbulent flow characteristics are complicated. Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence. A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations. This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions. Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.

  19. An effective Euler-Lagrange model for suspended sediment transport by open channel flows

    Institute of Scientific and Technical Information of China (English)

    Huabin Shi; Xiping Yu n

    2015-01-01

    An Euler–Lagrange two-phase flow model is developed to study suspended sediment transport by open-channel flows with an Eddy Interaction Model (EIM) applied to consider the effect of fluid turbulence on sediment diffusion. For the continuous phase, the mean fluid velocity, the turbulent kinetic energy and its dissipation rate are directly estimated by well-established empirical formulas. For the dispersed phase, sediment particles are tracked by solving the equation of motion. The EIM is applied to compute the particle fluctuation velocity. Neglecting the effect of particles on flow turbulence as usually suggested for dilute cases in the literature, the Euler–Lagrange model is applied to simulate suspended sediment transport in open channels. Although the numerical results agree well with those by the well-known random walk particle tracking model (RWM) and with the laboratory data for fine sediment cases, it is clearly shown that such an Euler–Lagrange model underestimates the sediment concentration for the medium-sized and coarse sediment cases. To improve the model, a formula is proposed to consider the local fluid turbulence enhancement around a particle due to vortex shedding in the wake. Numerical results of the modified model then agree very well with laboratory data for not only the fine but also the coarse sediment cases.

  20. Sound Search Engine Concept

    DEFF Research Database (Denmark)

    2006-01-01

    Sound search is provided by the major search engines, however, indexing is text based, not sound based. We will establish a dedicated sound search services with based on sound feature indexing. The current demo shows the concept of the sound search engine. The first engine will be realased June...