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IEEE International Conference on Nonlinear Science and Complexity (NSC)

作者： S. Lenci Department of Civil and Building Engineering and Architecture Polytechnic University of Marche Ancona Italy

A simplified model for the pedestrian-bridge interaction is illustrated. The main advantage of the model is that it permits to computing the number of pedestrians leading to synchronization and unwanted dynamics with ... 详细信息

关键词： Bridges Synchronization Vibrations Oscillators Force Legged locomotion Mathematical model

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Investigations on multi-slope sound energy decays in domed Structures

Investigations on multi-slope sound energy decays in domed S...

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41st International Congress and Exposition on Noise Control engineering 2012, INTER-NOISE 2012

作者： Gul, Zuhre Su Xiang, Ning Caliskan, Mehmet Department of Architecture Middle East Technical University Ankara 06800 Turkey MEZZO Studyo Ankara 06800 Turkey Program in Architectural Acoustics Rensselaer Polytechnic Institute School of Architecture Troy NY 12180 United States Department of Mechanical Engineering Middle East Technical University Ankara 06800 Turkey

ISBN: (纸本)9781627485609

Sound energy decays of coupled volume systems have attracted acousticians for many years. The interesting sound phenomenon is also applied in real cases as concert halls for influencing perception metrics to desired ranges. Theoretical studies of energy exchanges between coupled volumes with help of Bayesian inference aim to estimate parameters associated with multiple slope decays and characterize energy decays of multiple decay process. This study extends the definition of coupled volume system known to be two or more volumes with well defined enclosure limits coupled to each other with a coupling aperture. As specific combinations of different architectural volumes are highly correlated with acoustical coupling, domed structures are found to have a potential for multi slope investigations. Instead of multiple volumes with defined enclosures a single volume with specific geometric attributes is considered to be base for multiple-slope formation. Within this study a room-acoustic model of a multiple dome superstructure is established for multiple-slope decay analysis. Initial results indicate that double, triple or even more slope natures can be identified within the space at specific frequency bands.

关键词： Enclosures

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Locally reinforced laminated timber with glass fiber glued-in between the timber layers

Locally reinforced laminated timber with glass fiber glued-i...

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15th European Conference on Composite Materials: Composites at Venice, ECCM 2012

作者： Pavković, K. Haiman, M. Department of Civil Engineering Polytechnic of Zagreb Av. V. Holjevca 15 10 000 Zagreb Croatia Faculty of Architecture University of Zagreb Kačićeva 26 10 000 Zagreb Croatia

ISBN: (纸本)9788888785332

Research of truss girder joint based on the steel pipe placed in bottom and top cord and steel rods glued-in web member, requires local reinforcing of laminated timber in the zone of steel pipe. In this paper the reinforcing of wooden laminated element at the connection areas will be point out. Tests on 120mm width, 200mm high and 1000mm long specimens loaded perpendicular to the grain through a steel tube 50mm in diameter will be carried out. Experimental results obtained by reinforcing laminated timber will be compared with no reinforcing timber. Parallel with the results of laboratory experiments, results of numerical models will be presented. Numerical models with material and geometric nonlinearities were made with Abaqus /Standard for both series, reinforced and no reinforced timber.

关键词： Numerical models

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Generating of a nonlinear pseudorandom sequence using linear feedback shift register

Generating of a nonlinear pseudorandom sequence using linear...

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International Conference on Information and Communication Technology Convergence (ICTC)

作者： Hong Lv Jun-Chu Fang Jian-Xia Xie Peng Qi Department of Electronic and Information Engineering Anhui Institute of Architecture and Industry Hefei China Department of Electrical Engineering Anhui Polytechnic University Wuhu China

Utilizing m sequence shift register to create pseudorandom sequences is one critical method to construct desired sequences. In this thesis, a new type of nonlinear m subsequence is proposed through the analysis of feedback function of m sequence shift register with three items' primary polynomial. Eigenfunction of m subsequence shift register is presented. A new method to construct feedback function of nonlinear m subsequence based on root function is also presented. Through the feedback functions, the nonlinear maximal length pseudorandom sequences are realized on FPGA. Meanwhile, the corresponding analysis demonstrates that this type of sequence has ideal pseudorandom characteristic and desirable linear complexity.

关键词： Shift registers Transforms Random sequences Eigenvalues and eigenfunctions Complexity theory Correlation Feedback circuits

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An automotive application of real-time adaptive Wiener filter for non-stationary noise cancellation in a car environment

An automotive application of real-time adaptive Wiener filte...

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IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC)

作者： Yen-Hsiang Chen Shanq-Jang Ruan Tom Qi Department of Electronic Engineering National Taiwan University of Science and Technology Taiwan School of Architecture Building and Engineering Otago Polytechnic New Zealand

Wiener filter is one of the most fundamental noise-reduction approaches among numerous techniques. The speech recognition in an in-vehicle environment needs a non-stationary noise cancellation to eliminate the background noise. However, few efforts have been reported to show the effectiveness of Wiener filter. Not much has been evaluated how the Wiener filter really works for reducing the non-stationary noise in real-time. In this paper, a real-time adaptive Wiener filter with two microphones is implemented to reduce noisy speech when noise signals and desired speech are incoming simultaneously. Furthermore, in order to build a real-time noise canceller, this paper also gives an analysis of different matrix sizes of the Wiener filter so as to enable the possibility of real-time implementation. The performance of the proposed design is measured by as much as 20dB noise reduction, and the proposed adaptive Wiener matrix update speed achieves a 28.6 ms/frame, with a matrix size of 200.

关键词： Speech Microphones Real-time systems Noise cancellation Signal to noise ratio Noise measurement

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Experimental investigation of the acoustic attenuation by monolithic polyurea aerogels

Experimental investigation of the acoustic attenuation by mo...

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41st International Congress and Exposition on Noise Control engineering 2012, INTER-NOISE 2012

作者： Fackler, Cameron Xiang, Ning Churu, Gitogo Mohite, Dhairyashil P. Leventis, Nicholas Sotiriou-Leventis, Chariklia Lu, Hongbing Program in Architectural Acoustics Rensselaer Polytechnic Institute School of Architecture Troy NY 12180 United States Department of Mechanical Engineering University of Texas at Dallas Richardson TX 75080 United States Department of Chemistry Missouri University of Science and Technology Rolla MO 65409 United States

ISBN: (纸本)9781627485609

Aerogels are lightweight, porous nanostructured materials with exceptional thermal insulation properties. The most widely studied aerogel variety is based on silica;however, recent advances in all-polymer aerogels have resolved fragility issues and render them viable alternatives. In particular, polyurea aerogels can be synthesized in a single environmentally friendly step from inexpensive triisocyanates and water over a wide range of densities. Reasoning that the nanoporous characteristics of polyurea aerogels could be accompanied by high, structure-dependent acoustic attenuation, this work investigates the acoustic properties of polyurea aerogels with emphasis on their acoustic attenuation. Conventional materials with high acoustic damping capabilities typically have relatively high densities or are bulky. In applications where weight and volume are at a premium, polyurea aerogels may potentially provide a solution where traditional materials fail. Using a three-microphone impedance tube method, this work experimentally investigates the propagation coefficient of several monolithic polyurea aerogels at different densities. In contrast to traditional porous materials, polyurea aerogels demonstrate very high acoustic attenuation and therefore show promise for a wide range of applications. This paper discusses experimental results and addresses challenges in the measurement of acoustic properties with high attenuation materials.

关键词： Aerogels

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Nonlinear dynamics of a MEMS resonator: Theoretical and experimental investigation

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AIP Conference Proceedings 2012年第1期1493卷 822-829页

作者： Laura Ruzziconi Ahmad M. Bataineh Mohammad I. Younis Weili Cui Stefano Lenci Department of Civil and Building Engineering and Architecture Polytechnic University of Marche via Brecce Bianche 60131 Ancona Italy Department of Mechanical Engineering State University of New York at Binghamton Binghamton 13902 NY USA

In this study we present a theoretical and experimental investigation of a microelectromechanical system (MEMS). The device is constituted of a clamped-clamped polysilicon microbeam electrostatically and electrodynamically actuated. The microbeam has a slightly curled up configuration, which is an imperfection commonly encountered as a consequence of the microfabrication process. Using a laser Doppler vibrometer, many experimental frequency sweeps are conducted in a neighborhood of the first symmetric natural frequency. To simulate the dynamics, we derive a single-mode reduced-order model. Extensive numerical investigations are performed, based on frequency response diagrams and behavior charts. The overall scenario of the response is explored, when both the frequency and the electrodynamic voltage are varying. This analysis is able to provide a very good matching with the experiments. Nevertheless, the theoretical predictions are not completely fulfilled in some aspects. In particular, the range of existence of each attractor is smaller in practice than in the simulations. This is because the theoretical curves represent the ideal limit case where disturbances are absent, which never occurs in experiments and practice. To overcome this drawback and extend the results to the practical case where disturbances exist, we develop a dynamical integrity analysis. After introducing dynamical integrity concepts, we perform integrity profiles and integrity charts. They are able to describe if each attractor is robust enough to tolerate the disturbances. They detect the parameter range where each branch can be reliably observed in practice and where, instead, becomes vulnerable, i.e., depending on the expected disturbances, they provide valuable information to operate the device in safe conditions according to the desired outcome.

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Global dynamics and complexity:a modern perspective for the analysis,design and control of mechanical/structural systems

Global dynamics and complexity:a modern perspective for the ...

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23rd International Congress of Theoretical and Applied Mechanics

作者： Stefano Lenci Rega Giuseppe Department of Civil and Building Engineering and ArchitecturePolytechnic University of Marchevia Brecce BiancheAnconaItaly Department of Structural and Geotechnical Engineering Sapienza University of RomeRomeItaly

The classical concept of local stability is reconsidered with the aim of reducing the gap between the theoretical predictions and the critical instability thresholds observed in practice or in experiments. The key ide... 详细信息

关键词： Global dynamics and complexity:a modern perspective for the analysis,design and control of mechanical/structural systems

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Assessment of Risk to Human Health from Landfill Gas at Sharra Landfill, Tirana--Albania

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Journal of Environmental Science and engineering(B) 2012年第11期1卷 1239-1244页

作者： Konalsi Gjoka Teida Shehi Florian Nepravishta Department of Environmental Engineering Faculty of Civil Engineering Polytechnic University of Tirana ST Muhamet GjolleshaNr.54 Tirana Albania Institute for Habitat Development ST "Bylis "' Nr. 12 Tirana Albania Department of Architecture and Urban Planning Polytechnic University of Tirana ST Muhamet Gjollesha Nr. 54 Tirana Albania

Urban waste management and particularly dumpsites represents one of the most significant problems tot the long term protection of public health and environment in Albania. All waste management options, including landfilling, involve an element of risk to human health. This article addresses the question, if sources of emissions from Sharra landfill lead theoretically to public exposures exceeding health criteria？ This question is approached using an exposure pathway analysis framework, which link a source of one or more harmful pollutants at a site with a human receptor that inhales the pollutant. The risk posed to human health from HCHO （formaldehyde） and dioxin is estimated for on-site and off-site receptors in Sharra landfill. For on-site receptors, the average risk to get harm through the inhalation pathway from HCHO is in the range of 20 times to 300 times greater than allowed risk value, while for off-site receptors the average risk is in the range of 10 times to 180 times greater. While for dioxin the risk is in the range from 50 to 600 for on-site receptors and 10 to 35 for off-site receptors, times greater than often allowed risk.

关键词： Solid waste risk assessment impact to human health landfill gas.

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A hybrid algorithm for computation of rectangular conductor internal impedance

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Tehnicki Vjesnik 2012年第2期19卷 341-346页

作者： Boras, Vedran Vujević, Slavko Lovrić, Dino University of Split Faculty of Natural Sciences and Mathematics Department for Polytechnic Teslina 12 21 000 Split Croatia University of Split Faculty of Electrical Engineering Mechanical Engineering and Naval Architecture Rudera Boškovića 32 21 000 Split Croatia

A hybrid algorithm for the computation of rectangular conductor per unit length internal impedance is developed. Up to a switching frequency, the internal impedance is computed using a two dimensional analytical formula developed by Giacoletto. For these frequencies, 150 terms of Giacoletto infinite sum give a sufficiently good approximation. For higher frequencies, it is shown that the rectangular conductor can be quite accurately approximated by a cylindrical conductor. The proposed hybrid algorithm, for higher frequencies, features improved accuracy and speed when compared to the Giacoletto formula truncated after a small number of terms.

关键词： Cylindrical conductor Exponential approximation Internal impedance Rectangular conductor

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