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Sample records for ambient vibration measurements

  1. NIF Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  2. Output-Only Modal Identification of a Containment Building from Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo-Yong; Shin, Yung-Moo; Kim, Ha-Yeon [Korea Maritime University, Pusan (Korea, Republic of); Choi, Sang-Hyun; Kim, Dae-Hyuk [Korea National Railroad College, Uiwang (Korea, Republic of); Hyun, Chang-Hun; Kim, Moon-Soo; Kim, Sang-Yun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2008-10-15

    Ensuring and maintaining the structural integrity of the containment building (CB) in nuclear power plants is essential in preserving the nuclear reactor and other safety related systems from man-made as well as natural disasters, and protecting plant workers and publics from hazardous radioactive materials. To date, the structural integrity of the CB has been evaluated periodically via visual inspections, chemical tests, nondestructive strength tests, etc. However, these methods can only provide the local information on the structural condition and require considerable time and cost to estimate overall structural integrity. In this paper, the possibility of monitoring the structural integrity of a CB utilizing ambient vibration measurement (AVM) is explored. The ambient vibration testing has gained attention which can avoid the interruption of normal operation of civil structures. To fulfill the objective, the ambient vibration of the CB of the Ulchin 5th unit was measured, and the modal parameters, resonant frequencies and corresponding mode shapes, were extracted.

  3. The dynamic response of prone-to-fall columns to ambient vibrations: comparison between measurements and numerical modelling

    Science.gov (United States)

    Valentin, J.; Capron, A.; Jongmans, D.; Baillet, L.; Bottelin, P.; Donze, F.; Larose, E.; Mangeney, A.

    2017-02-01

    Seismic noise measurements (ambient vibrations) have been increasingly used in rock slope stability assessment for both investigation and monitoring purposes. Recent studies made on gravitational hazard revealed significant spectral amplification at given frequencies and polarization of the wave-field in the direction of maximum rock slope displacement. Different properties (resonance frequencies, polarization and spectral ratio amplitudes) can be derived from the spectral analysis of the seismic noise to characterize unstable rock masses. The objective here is to identify the dynamic parameters that could be used to gain information on prone-to-fall rock columns' geometry. To do so, the dynamic response of prone-to-fall columns to seismic noise has been studied on two different sites exhibiting cliff-like geometry. Dynamic parameters (main resonance frequency and spectral ratio amplitudes) that could characterize the column decoupling were extracted from seismic noise and their variations were studied taking into account the external environmental parameter fluctuations. Based on this analysis, a two-dimensional numerical model has been set up to assess the influence of the rear vertical fractures identified on both sites on the rock column motion response. Although a simple relation was found between spectral ratio amplitudes and the rock column slenderness, it turned out that the resonance frequency is more stable than the spectral ratio amplitudes to characterize this column decoupling, provided that the elastic properties of the column can be estimated. The study also revealed the effect of additional remote fractures on the dynamic parameters, which in turn could be used for detecting the presence of such discontinuities.

  4. Ambient Vibration Test on Reinforced Concrete Bridges

    Directory of Open Access Journals (Sweden)

    Idris Nurul Shazwin

    2016-01-01

    Full Text Available An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC bridges by using ambient vibration test (AVT. The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS in transverse (North-South, longitudinal (East-West and vertical (Up-Down direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple

  5. Damage localization under ambient vibration using changes in flexibility

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In recent years, Structural Health Monitoring (SHM) has emerged as a new research area in civil engineering. Mostexisting health monitoring methodologies require direct measurement of input excitation for implementation. However, in manycases, there is no easy way to measure these inputs - or alternatively to externally excite the structure. Therefore, SHM methodsbased on ambient vibration have become important in civil engineering. In this paper, an approach is proposed based on the DamageLocation Vector (DLV) method to handle the ambient vibration case. Here, this flexibility-matrix-based damage localization methodis combined with a modal expansion technique to eliminate the need to measure the input excitation. As a by-product of thisapproach, in addition to determining the location of the damage, an estimate of the damage extent also can be determined. Finally, anumerical example analyzing a truss structure with limited sensors and noisy measurement is provided to verify the efficacy of theproposed approach.

  6. Ambient Vibration Test for a Multi-story Residential Building and the Vibration Mitigation Measures%多层住宅环境振动影响测试与减振措施分析

    Institute of Scientific and Technical Information of China (English)

    朱斌; 陈龙珠; 丁力

    2014-01-01

    Brick-concrete buildings have been extensively used in urban and rural areas.However,this type of building,which frequently contains a shallow foundation,demonstrates poor struc-tural integrity and is susceptible to influence from ambient vibrations.This case is especially validfor buildings that were constructed in previous eras.With the development of modern cities andthe increasing demand for an enhanced quality of life,environmental interference caused by ambi-ent vibrations has become a critical issue.In areas with soft soil,traffic is a primary source ofambient vibrations.Vehicle vibrations caused by road surface roughness or speed changes cancause vibrations throughout the foundation of a building.Therefore,the vibration of brick-con-crete buildings is related not only to the excitation source of the vibration but also the soil charac-teristics,the foundation conditions,and the structural style.The human response to the vibra-tions of housing structures is closely correlated with a person's cognitive level and their currentphysical and psychological conditions.Thus,the potential difference in the reactions amongbuilding occupants is significant.Residents in a six-story brick-concrete building,which is located in an area of Shanghai withsoft ground,frequently complained about the intermittent interference from vibrations,particularly residents on the upper two stories.The measures confirmed that the environmental vibra-tions were generated by heavy vehicles traveling on a road that was located approximately 80 mnorth of the building.The frequency and amplitude characteristics of the ambient vibrations andthe human comfort levels for the different stories of the building were analyzed according to the"standard for allowable vibration of building engineering"(GB50868-2013).To comprehensivelyevaluate the impact induced by the transversely horizontal vibrations,which influences humancomfort levels for the three components of building vibration,a numerical finite

  7. Damping Estimation Using Free Decays and Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Magalhães, Filipe; Brincker, Rune; Cunha, Álvaro

    2007-01-01

    The accurate identification of modal damping ratios of Civil Engineering structures is a subject of major importance, as the amplitude of structural vibrations in resonance is inversely proportional to these coefficients. Their experimental identification can be performed either from ambient...... vibration or from free vibration tests. In the last case, the structural response after application of an impulse or after the application of harmonic loads can be used. Ambient vibration tests have the strong advantage of being more practical and economical. However, recent applications of both approaches...

  8. Automated data-based damage localization under ambient vibration using local modal filters and dynamic strain measurements: Experimental applications

    Science.gov (United States)

    Tondreau, Gilles; Deraemaeker, Arnaud

    2014-12-01

    This paper deals with the experimental application of modal filters for automated damage localization using dynamic strain measurements. Previously developed for damage detection, the extension of modal filtering to damage localization consists in splitting a very large network of dynamic strain sensors into several independent local sensor networks. An efficient signal processing coupled to control charts allows a fully automated data-based damage localization once the modal filters are initialized. The method is tested experimentally on a small clamped-free steel plate and a 3.78 m long steel I-beam, both instrumented with a network of cheap piezoelectric patches to measure the dynamic strains. A removable damage is introduced at different positions by means of a small removable damage device. For both applications, the method can successfully detect and locate all damage cases considered, showing the potentiality of the method for field applications.

  9. Damping estimation using free decays and ambient vibration tests

    Science.gov (United States)

    Magalhães, Filipe; Cunha, Álvaro; Caetano, Elsa; Brincker, Rune

    2010-07-01

    This paper studies the quality of modal damping ratios estimates based on ambient and free vibration tests using both numerical simulations and data collected on large Civil Engineering structures where both tests were performed. The simulated data allowed to study the influence of factors like non-proportional damping or proximity of natural frequencies on the quality of the estimates and also to illustrate the influence of the identification algorithms parameters on the accuracy of the results. The analysis of data collected on a cable-stayed bridge, on the suspended roof of a stadium and on a footbridge permitted to compare the results of both testing approaches in real applications where some factors that cannot be realistically included in the numerical simulations can play an important role. The processing of ambient vibration responses is performed with two output-only identification approaches: frequency domain decomposition and stochastic subspace identification methods. The numerically simulated and the measured free decays were analyzed with a simple method based on filters and fitting of exponential decays and also with the use of subspace models.

  10. FEM Updating of Tall Buildings using Ambient Vibration Data

    DEFF Research Database (Denmark)

    Ventura, C. E.; Lord, J. F.; Turek, M.;

    2005-01-01

    to develop reliable finite element models of large civil engineering structures. A fifteen story and a forty-eight story reinforced concrete buildings are used as case studies for this purpose. The dynamic characteristics of interest for this study were the first few lateral and torsional natural frequencies...... and the corresponding mode shapes. The degree of torsional coupling between the modes was also investigated. The modal identification results obtained from ambient vibration measurements of each building were used to update a finite element model of the structure. The starting model of each structure was developed from...... the information provided in the design documentation of the building. Different parameters of the model were then modified using an automated procedure to improve the correlation between measured and calculated modal parameters. Careful attention was placed to the selection of the parameters to be modified...

  11. Identifying damage locations under ambient vibrations utilizing vector autoregressive models and Mahalanobis distances

    Science.gov (United States)

    Mosavi, A. A.; Dickey, D.; Seracino, R.; Rizkalla, S.

    2012-01-01

    This paper presents a study for identifying damage locations in an idealized steel bridge girder using the ambient vibration measurements. A sensitive damage feature is proposed in the context of statistical pattern recognition to address the damage detection problem. The study utilizes an experimental program that consists of a two-span continuous steel beam subjected to ambient vibrations. The vibration responses of the beam are measured along its length under simulated ambient vibrations and different healthy/damage conditions of the beam. The ambient vibration is simulated using a hydraulic actuator, and damages are induced by cutting portions of the flange at two locations. Multivariate vector autoregressive models were fitted to the vibration response time histories measured at the multiple sensor locations. A sensitive damage feature is proposed for identifying the damage location by applying Mahalanobis distances to the coefficients of the vector autoregressive models. A linear discriminant criterion was used to evaluate the amount of variations in the damage features obtained for different sensor locations with respect to the healthy condition of the beam. The analyses indicate that the highest variations in the damage features were coincident with the sensors closely located to the damages. The presented method showed a promising sensitivity to identify the damage location even when the induced damage was very small.

  12. On Modal Parameter Estimates from Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Agneni, A.; Brincker, Rune; Coppotelli, B.

    2004-01-01

    Modal parameter estimates from ambient vibration testing are turning into the preferred technique when one is interested in systems under actual loadings and operational conditions. Moreover, with this approach, expensive devices to excite the structure are not needed, since it can be adequately...

  13. Vibration of a Cantilever Beam in Ambient Fluid

    CERN Document Server

    Metzger, C; Zypman, F

    2016-01-01

    Here we obtain analytical expressions for the frequency response of a cantilever beam in the presence of ambient fluid. The advantage of our approach, besides its simplicity of use, is that it explicitly contains the viscosity and the density of the ambient fluid. Thus, if measuring the frequency spectrum, the expression can be used in the design of viscometers. Conversely, if the ambient fluid is known, the expression can be used in the design of force gauges such as in Atomic Force Microscopy.

  14. Ambient Vibration Testing for Story Stiffness Estimation of a Heritage Timber Building

    Directory of Open Access Journals (Sweden)

    Kyung-Won Min

    2013-01-01

    Full Text Available This paper investigates dynamic characteristics of a historic wooden structure by ambient vibration testing, presenting a novel estimation methodology of story stiffness for the purpose of vibration-based structural health monitoring. As for the ambient vibration testing, measured structural responses are analyzed by two output-only system identification methods (i.e., frequency domain decomposition and stochastic subspace identification to estimate modal parameters. The proposed methodology of story stiffness is estimation based on an eigenvalue problem derived from a vibratory rigid body model. Using the identified natural frequencies, the eigenvalue problem is efficiently solved and uniquely yields story stiffness. It is noteworthy that application of the proposed methodology is not necessarily confined to the wooden structure exampled in the paper.

  15. Ambient vibration testing for story stiffness estimation of a heritage timber building.

    Science.gov (United States)

    Min, Kyung-Won; Kim, Junhee; Park, Sung-Ah; Park, Chan-Soo

    2013-01-01

    This paper investigates dynamic characteristics of a historic wooden structure by ambient vibration testing, presenting a novel estimation methodology of story stiffness for the purpose of vibration-based structural health monitoring. As for the ambient vibration testing, measured structural responses are analyzed by two output-only system identification methods (i.e., frequency domain decomposition and stochastic subspace identification) to estimate modal parameters. The proposed methodology of story stiffness is estimation based on an eigenvalue problem derived from a vibratory rigid body model. Using the identified natural frequencies, the eigenvalue problem is efficiently solved and uniquely yields story stiffness. It is noteworthy that application of the proposed methodology is not necessarily confined to the wooden structure exampled in the paper.

  16. Natural Frequencies and Modal Damping Ratios Identification of Civil Structures from Ambient Vibration Data

    Directory of Open Access Journals (Sweden)

    Minh-Nghi Ta

    2006-01-01

    Full Text Available Damping is a mechanism that dissipates vibration energy in dynamic systems and plays a key role in dynamic response prediction, vibration control as well as in structural health monitoring during service. In this paper a time domain and a time-scale domain approaches are used for damping estimation of engineering structures, using ambient response data only. The use of tests under ambient vibration is increasingly popular today because they allow to measure the structural response in service. In this paper we consider two engineering structures excited by ambient forces. The first structure is the 310 m tall TV tower recently constructed in the city of Nanjing in China. The second example concerns the Jinma cable-stayed bridge that connects Guangzhou and Zhaoqing in China. It is a single tower, double row cable-stayed bridge supported by 112 stay cables. Ambient vibration of each cable is carried out using accelerometers. From output data only, the modal parameter are extracted using a subspace method and the wavelet transform method.

  17. Mechanical Vibrations Modeling and Measurement

    CERN Document Server

    Schmitz, Tony L

    2012-01-01

    Mechanical Vibrations:Modeling and Measurement describes essential concepts in vibration analysis of mechanical systems. It incorporates the required mathematics, experimental techniques, fundamentals of modal analysis, and beam theory into a unified framework that is written to be accessible to undergraduate students,researchers, and practicing engineers. To unify the various concepts, a single experimental platform is used throughout the text to provide experimental data and evaluation. Engineering drawings for the platform are included in an appendix. Additionally, MATLAB programming solutions are integrated into the content throughout the text. This book also: Discusses model development using frequency response function measurements Presents a clear connection between continuous beam models and finite degree of freedom models Includes MATLAB code to support numerical examples that are integrated into the text narrative Uses mathematics to support vibrations theory and emphasizes the practical significanc...

  18. 收集环境振动能微压电悬臂梁的制作工艺与测试%Manufacturing Technique and Measurement of Micro-Piezoelectric Cantilever Beam for Ambient Vibration Energy Collection

    Institute of Scientific and Technical Information of China (English)

    褚金奎; 李涛; 韩冰峰; 熊叶胜

    2011-01-01

    研制长寿稳定电源已经成为微型无线传感网络中亟待解决的关键技术问题,现有的化学电池容量有限,需要不断地逐个更换耗尽的电池,难以满足无线传感网络的实际应用.提出了利用压电材料的机电耦合特性收集环境振动能,设计了一种用来收集环境振动能的压电微悬臂梁结构,介绍了用MEMS工艺制作带质量块的硅基压电悬臂梁微电源的工艺流程.质量块可以降低器件的谐振频率,并提高输出电功率.最后,对制作的微压电悬臂梁进行了固有频率测试以及静态和准静态标定实验.%Long life and stable batteries in the wireless sensors nodes of the micro system are urgently demanded as the chemical batteries are limited in capacity and have to be replaced constantly, which cannot meet the requirement of practical applications. A new type of micro generator which utilizes electric-me-chanical coupling characteristics of piezoelectric materials to collect ambient vibration energy was proposed and a micro piezoelectric cantilever structure was designed to collect ambient vibration energy. The MEMS fabrication process for the micro piezoelectric cantilever beam with the mass block was introduced,which could help decrease the natural frequency of the device and improve the output electric power. Finally, the natural frequency of the manufactured piezoelectric micro-cantilevers was measured and the static and quasi-static calibrations were carried out.

  19. Ambient Vibration Based Damage Diagnosis Using Statistical Modal Filtering and Genetic Algorithm: A Bridge Case Study

    Directory of Open Access Journals (Sweden)

    S. El-Ouafi Bahlous

    2013-01-01

    Full Text Available The authors recently developed a damage identification method which combines ambient vibration measurements and a Statistical Modal Filtering approach to predict the location and degree of damage. The method was then validated experimentally via ambient vibration tests conducted on full-scale reinforced concrete laboratory specimens. The main purpose of this paper is to demonstrate the feasibility of the identification method for a real bridge. An important challenge in this case is to overcome the absence of vibration measurements for the structure in its undamaged state which corresponds ideally to the reference state of the structure. The damage identification method is, therefore, modified to adapt it to the present situation where the intact state was not subjected to measurements. An additional refinement of the method consists of using a genetic algorithm to improve the computational efficiency of the damage localization method. This is particularly suited for a real case study where the number of damage parameters becomes significant. The damage diagnosis predictions suggest that the diagnosed bridge is damaged in four elements among a total of 168 elements with degrees of damage varying from 6% to 18%.

  20. Retrieval of Rayleigh Wave Ellipticity from Ambient Vibration Recordings

    Science.gov (United States)

    Maranò, Stefano; Hobiger, Manuel; Fäh, Donat

    2017-01-01

    The analysis of ambient vibrations is a useful tool in microzonation and geotechnical investigations. Ambient vibrations are composed to a large part of surface waves, both Love and Rayleigh waves. One reason to analyse surface waves is that they carry information about the subsurface. The dispersion curve of Rayleigh waves and Love waves can be retrieved using array processing techniques. The Rayleigh wave ellipticity, including the sense of rotation of the particle motion, can also be retrieved using array techniques. These quantities are used in an inversion procedure aimed at obtaining a structural model of the subsurface. The focus of this work is the retrieval of Rayleigh wave ellipticity. We show applications of the (ML) method presented in Maranó et al. (2012) to a number of sites in Switzerland. The sites examined are chosen to reflect a wide range of soil conditions that are of interest in microzonation studies. Using a synthetic wavefield with known structural model, we compare our results with theoretical ellipticity curves and we show the accuracy of the considered algorithm. The sense of rotation of the particle motion (prograde vs. retrograde) is also estimated. In addition, we show that by modelling the presence of both Love and Rayleigh waves it is possible to mitigate the disruptive influence of Love waves on the estimation of Rayleigh wave ellipticity. Using recordings from several real sites, we show that it is possible to retrieve the ellipticity curve over a broad range of frequencies. Fundamental modes and higher modes are retrieved. Singularities of the ellipticity, corresponding to a change of the sense of rotation from prograde to retrograde (or vice versa), are detected with great accuracy. Knowledge of Rayleigh wave ellipticity, including the sense of rotation, is useful in several ways. The ellipticity angle allows us to pinpoint accurately the frequency of singularities (i.e., peaks and zeros of the H/V representation of the

  1. Identification of aeroelastic forces and static drag coefficients of a twin cable bridge stay from full-scale ambient vibration measurements

    DEFF Research Database (Denmark)

    Acampora, Antonio; Georgakis, Christos T.; Macdonald, J.H.G.;

    2014-01-01

    presents results from full-scale measurements on the special arrangement of twin cables adopted for the Øresund Bridge. The monitoring system records wind and weather conditions, as well as accelerations of certain cables and a few locations on the deck and tower. Using the Eigenvalue Realization Algorithm...

  2. Bayesian characterization of buildings using seismic interferometry on ambient vibrations

    Science.gov (United States)

    Sun, Hao; Mordret, Aurélien; Prieto, Germán A.; Toksöz, M. Nafi; Büyüköztürk, Oral

    2017-02-01

    Continuous monitoring of engineering structures provides a crucial alternative to assess its health condition as well as evaluate its safety throughout the whole service life. To link the field measurements to the characteristics of a building, one option is to characterize and update a model, against the measured data, so that it can best describe the behavior and performance of the structure. In this paper, we present a novel computational strategy for Bayesian probabilistic updating of building models with response functions extracted from ambient noise measurements using seismic interferometry. The intrinsic building impulse response functions (IRFs) can be extracted from ambient excitation by deconvolving the motion recorded at different floors with respect to the measured ambient ground motion. The IRF represents the representative building response to an input delta function at the ground floor. The measurements are firstly divided into multiple windows for deconvolution and the IRFs for each window are then averaged to represent the overall building IRFs. A hierarchical Bayesian framework with Laplace priors is proposed for updating the finite element model. A Markov chain Monte Carlo technique with adaptive random-walk steps is employed to sample the model parameters for uncertainty quantification. An illustrative example is studied to validate the effectiveness of the proposed algorithm for temporal monitoring and probabilistic model updating of buildings. The structure considered in this paper is a 21-storey concrete building instrumented with 36 accelerometers at the MIT campus. The methodology described here allows for continuous temporal health monitoring, robust model updating as well as post-earthquake damage detection of buildings.

  3. Surveying techniques in vibration measurement

    Directory of Open Access Journals (Sweden)

    Kuras Przemyslaw

    2015-01-01

    Full Text Available In order to determine the actual dynamic characteristics of engineering structures, it is necessary to perform direct measurements. The paper focuses on the problem of using various devices to measure vibration, with particular emphasis on surveying instruments. The main tool used in this study is the radar interferometer, which has been compared to: robotic total station, GNSS receivers and sensors (accelerometer and encoder. The results of four dynamic experiments are presented. They were performed on: industrial chimney, drilling tower, railway bridge and pedestrian footbridge. The obtained results have been discussed in terms of the requirements imposed by the standard ISO 4866:2010.

  4. Vibration measurement and modal analysis for tunneller

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; WU Miao; WEI Ren-zhi

    2001-01-01

    In this paper, the method of vibration measurement and modal analysis for AM~50 Tunneller machine is presented. When the machine was used for cutting man-made coal bed and real coal bed, the vibration of the machine was measured and the results of signal analysis show that the vibration characteristics under the two kinds of working situations are similar. The modal model of the machine is established, and then, the intrinsic vibration characteristics of AM50 tunneller are investigated by means of the method of experimental modal analysis. The vibration response simulation under a set of loading spectra measured is carried out by force response simulation software.

  5. The Health Monitoring Method of Concrete Dams Based on Ambient Vibration Testing and Kernel Principle Analysis

    Directory of Open Access Journals (Sweden)

    Lin Cheng

    2015-01-01

    Full Text Available The ambient vibration testing (AVT measurement of concrete dams on full-scale can show the practical dynamic properties of structure in the operation state. For most current researches, the AVT data is generally analyzed to identify the structural vibration characteristics, that is, modal parameters. The identified modal parameters, which can provide the global damage information or the damage location information of structure, can be used as the basis of structure health monitoring. Therefore, in this paper, the health monitoring method of concrete dams based on the AVT is studied. The kernel principle analysis (KPCA based method is adopted to eliminate the effect of environmental variables and monitor the health of dam under varying environments. By taking full advantage of the AVT data obtained from vibration observation system of dam, the identification capabilities and the warning capabilities of structural damage can be improved. With the simulated AVT data of the numerical model of a concrete gravity dam and the measured AVT data of a practical engineering, the performance of the dam health monitoring method proposed in this paper is verified.

  6. Embedding human annoyance rate models in wireless smart sensors for assessing the influence of subway train-induced ambient vibration

    Science.gov (United States)

    Sun, Ke; Zhang, Wei; Ding, Huaping; Kim, Robin E.; Spencer, Billie F., Jr.

    2016-10-01

    The operation of subway trains induces ambient vibrations, which may cause annoyance and other adverse effects on humans, eventually leading to physical, physiological, and psychological problems. In this paper, the human annoyance rate (HAR) models, used to assess the human comfort under the subway train-induced ambient vibrations, were deduced and the calibration curves for 5 typical use circumstances were addressed. An autonomous measurement system, based on the Imote2, wireless smart sensor (WSS) platform, plus the SHM-H, high-sensitivity accelerometer board, was developed for the HAR assessment. The calibration curves were digitized and embedded in the computational core of the WSS unit. Experimental validation was conducted, using the developed system on a large underground reinforced concrete frame structure adjoining the subway station. The ambient acceleration of both basement floors was measured; the embedded computation was implemented and the HAR assessment results were wirelessly transmitted to the central server, all by the WSS unit. The HAR distributions of the testing areas were identified, and the extent to which both basements will be influenced by the close-up subway-train’s operation, in term of the 5 typical use circumstances, were quantitatively assessed. The potential of the WSS-based autonomous system for the fast environment impact assessment of the subway train-induced ambient vibration was well demonstrated.

  7. Ocean Ambient Noise Measurement and Theory

    CERN Document Server

    Carey, William M

    2011-01-01

    This book develops the theory of ocean ambient noise mechanisms and measurements, and also describes general noise characteristics and computational methods.  It concisely summarizes the vast ambient noise literature using theory combined with key representative results.  The air-sea boundary interaction zone is described in terms of non-dimensional variables requisite for future experiments.  Noise field coherency, rare directional measurements, and unique basin scale computations and methods are presented.  The use of satellite measurements in these basin scale models is demonstrated.  Finally, this book provides a series of appendices giving in-depth mathematical treatments.  With its complete and careful discussions of both theory and experimental results, this book will be of the greatest interest to graduate students and active researchers working in fields related to ambient noise in the ocean.

  8. Materials for Damping Ambient Acoustic and Vibration Signals Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-term exposure to even relatively low levels of acoustic and vibration signals has been shown to be potentially harmful to humans. A new class of piezoelectric...

  9. Combined Annoyance Assessment of Subway Train-Induced Structural Vibration and Ambient Noise

    Directory of Open Access Journals (Sweden)

    Ke Sun

    2016-01-01

    Full Text Available The subway train-induced structural vibration and ambient noise may cause annoyance and other negative influences on the human body. Presently, limited models have been developed to execute the quantitative evaluation of the combined annoyance caused by both structural vibration and ambient noise. In this study, a fuzzy membership function and normal distribution function were coupled to describe the fuzziness and randomness of human annoyance responses; a novel annoyance evaluation model was proposed to assess the structural vibration and ambient noise; and the annoyance of human was classified into six grades. Subsequently, we integrated an actual case into this study to calculate and analyze the combined annoyance degree. The applied results were compared with the standard limits, in which the rationality and superiority of the proposed model were verified. The results exhibit the notion that the proposed models perform well and can serve as a reference for spatial planning and development in the nearby subway environment.

  10. Dynamic test and finite element model updating of bridge structures based on ambient vibration

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The dynamic characteristics of bridge structures are the basis of structural dynamic response and seismic analysis,and are also an important target of health condition monitoring.In this paper,a three-dimensional finite-element model is first established for a highway bridge over a railroad on No.312 National Highway.Based on design drawings,the dynamic characteristics of the bridge are studied using finite element analysis and ambient vibration measurements.Thus,a set of data is selected based on sensitivity analysis and optimization theory;the finite element model of the bridge is updated.The numerical and experimental results show that the updated method is more simple and effective,the updated finite element model can reflect the dynamic characteristics of the bridge better,and it can be used to predict the dynamic response under complex external forces.It is also helpful for further damage identification and health condition monitoring.

  11. Optical vibration measurement of mechatronics devices

    Science.gov (United States)

    Yanabe, Shigeo

    1993-09-01

    An optical vibration measuring system which enables to detect both linear and angular displacement of 25 nm and 5 prad was developed. The system is mainly composed of a He-Ne laser, a displacement detecting photo-diode and lenses, and has linear and angular displacement magnification mechanism using two different principles of optical lever. The system was applied to measure vibrational characteristics of magnetic head slider of hard disk drives and to measure stator teeth driving velocities of ultrasonic motor.

  12. Vibration Measurement with PULSE and DSPACE Equipment

    Directory of Open Access Journals (Sweden)

    Radim KLEČKA

    2009-06-01

    Full Text Available This contribution describes techniques and results of measurement with TIRA vibration generator. A method of experimental modal analysis allows next restore of vibration data. The goal is check validity of head expanders and screw connection. This process is based to using ME’scope environment. Another goal is check possibilities of dSPACE platform to vibration measurement. This task includes design of connection between dSPACE system and power amplifier, creating of graphical user interface and analyzing main configuration parameters to improve quality of drive signal.

  13. Performance of Measuring Vibration of MEMS Sensor

    OpenAIRE

    Choe, Jung Seob; Inoue, Eiji; Mitsuoka, Muneshi; Okayasu, Takashi; Hirai, Yasumaru

    2014-01-01

    The purpose of this study is to examine the usefulness of an MEMS sensor for measuring vibration of agricultural vehicle by obtaining serial data of vibration acceleration of agricultural vehicle using an MEMS sensor and translational accelerometer and thereby calculating RMS and PSD for comparison and analysis as a step before construction of measuring system which can identify operating conditions of agricultural packaging machinery at all times. Although there are differences between verti...

  14. Low cost subpixel method for vibration measurement

    Science.gov (United States)

    Ferrer, Belen; Espinosa, Julian; Roig, Ana B.; Perez, Jorge; Acevedo, Pablo; Mas, David

    2014-05-01

    Traditional vibration measurement methods are based on devices that acquire local data by direct contact (accelerometers, GPS) or by laser beams (Doppler vibrometers). Our proposal uses video processing to obtain the vibration frequency directly from the scene, without the need of auxiliary targets or devices. Our video-vibrometer can obtain the vibration frequency at any point in the scene and can be implemented with low-cost devices, such as commercial cameras. Here we present the underlying theory and some experiments that support our technique.

  15. Low cost subpixel method for vibration measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, Belen [Department of Civil Engineering, Univ. Alicante P.O. Box, 99, 03080 Alicante (Spain); Espinosa, Julian; Perez, Jorge; Acevedo, Pablo; Mas, David [Inst. of Physics Applied to the Sciences and Technologies, Univ. Alicante P.O. Box, 99, 03080 Alicante (Spain); Roig, Ana B. [Department of Optics, Univ. Alicante P.O. Box, 99, 03080 Alicante (Spain)

    2014-05-27

    Traditional vibration measurement methods are based on devices that acquire local data by direct contact (accelerometers, GPS) or by laser beams (Doppler vibrometers). Our proposal uses video processing to obtain the vibration frequency directly from the scene, without the need of auxiliary targets or devices. Our video-vibrometer can obtain the vibration frequency at any point in the scene and can be implemented with low-cost devices, such as commercial cameras. Here we present the underlying theory and some experiments that support our technique.

  16. Bevel Gearbox Fault Diagnosis using Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Hartono Dennis

    2016-01-01

    Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

  17. A METHOD OF ONLINE DAMAGE IDENTIFICATION FOR STRUCTURES BASED ON AMBIENT VIBRATION

    Institute of Scientific and Technical Information of China (English)

    YAO Zhi-yuan; WANG Feng-quan; ZHAO Chun-sheng

    2005-01-01

    A method of damage identification for engineering structures based on ambient vibration is put forward, in which output data are used only. Firstly, it was identification of the statistic parameters to associate with the exterior excitation for undamaged structures.Then it was detection and location of the structural damages for damaged structures. The ambient identification method includes a theoretical model and numerical method. The numerical experiment results show the method is precise and effective. This method may be used in health monitoring for bridges and architectures.

  18. Vibration Measurements on the Frejlev Mast

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Hansen, Lars Pilegaard

    The present report presents full-scale measurements on the Frejlev-mast which is a 200 meter hight guyed steel mast located 10 km. from Aalborg. The goal of the research was to investigate various techniques which could be used to estimate cable forces from vibration measurements. The cables...

  19. In Situ Experiment and Modelling of RC-Structure Using Ambient Vibration and Timoshenko Beam

    CERN Document Server

    Michel, Clotaire; Guéguen, Philippe; Boutin, Claude

    2007-01-01

    Recently, several experiments were reported using ambient vibration surveys in buildings to estimate the modal parameters of buildings. Their modal properties are full of relevant information concerning its dynamic behaviour in its elastic domain. The main scope of this paper is to determine relevant, though simple, beam modelling whose validity could be easily checked with experimental data. In this study, we recorded ambient vibrations in 3 buildings in Grenoble selected because of their vertical structural homogeneity. First, a set of recordings was done using a 18 channels digital acquisition system (CityShark) connected to six 3C Lennartz 5s sensors. We used the Frequency Domain Decomposition (FDD) technique to extract the modal parameters of these buildings. Second, it is shown in the following that the experimental quasi-elastic behaviour of such structure can be reduced to the behaviour of a vertical continuous Timoshenko beam. A parametric study of this beam shows that a bijective relation exists bet...

  20. Dynamic Characteristics of a Tall Building Identified from Earthquake and Ambient Vibration Records

    Directory of Open Access Journals (Sweden)

    Andone Cristian

    2015-12-01

    Full Text Available The paper presents the modal characteristics of a tall building in Bucharest (BRD-SG Tower identified from earthquake and ambient vibration records. The building was built in the early 2000’s and has a reinforced concrete structure (inner shear wall tube and perimeter frames with 3 underground stories, ground floor and 18 stories. The seismic instrumentation of the building consists of a seismic station with two triaxial acceleration sensors located at the top of the building (+69.6 m and at the third basement (−9.3 m. The dynamic characteristics of the building are estimated from the seismic records from 23 earthquakes (with moment magnitudes MW between 3.7 and 6.0 that occurred during the period 2004÷2010. The results obtained from the earthquake records are compared with those obtained from 35 ambient vibration records from the period 2003 ÷ 2010.

  1. Ambient Vibration Tests of an Arch Dam with Different Reservoir Water Levels: Experimental Results and Comparison with Finite Element Modelling

    Directory of Open Access Journals (Sweden)

    Sergio Vincenzo Calcina

    2014-01-01

    Full Text Available This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012 and at the end of winter (March 2013, respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.

  2. Optical Measurement of Cable and String Vibration

    Directory of Open Access Journals (Sweden)

    Y. Achkire

    1998-01-01

    Full Text Available This paper describes a non contacting measurement technique for the transverse vibration of small cables and strings using an analog position sensing detector. On the one hand, the sensor is used to monitor the cable vibrations of a small scale mock-up of a cable structure in order to validate the nonlinear cable dynamics model. On the other hand, the optical sensor is used to evaluate the performance of an active tendon control algorithm with guaranteed stability properties. It is demonstrated experimentally, that a force feedback control law based on a collocated force sensor measuring the tension in the cable is feasible and provides active damping in the cable.

  3. A hybrid indoor ambient light and vibration energy harvester for wireless sensor nodes.

    Science.gov (United States)

    Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei

    2014-05-19

    To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%.

  4. A Hybrid Indoor Ambient Light and Vibration Energy Harvester for Wireless Sensor Nodes

    Directory of Open Access Journals (Sweden)

    Hua Yu

    2014-05-01

    Full Text Available To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%.

  5. Force Measurements in Vibration and Acoustic Tests

    Science.gov (United States)

    Scharton, T. D.

    1996-01-01

    The advent of triaxial, piezoelectric force gages and the associated signal processing is a precursor to several dynamics testing innovations. This new technology is applicable to spacecraft programs that JPL manages. An application of force measurement is force limiting (when testing spacecraft in random vibration tests). Base-drive and acoustic modal testing is a potential application.

  6. Seismic waves estimation and wavefield decomposition: application to ambient vibrations

    Science.gov (United States)

    Maranò, Stefano; Reller, Christoph; Loeliger, Hans-Andrea; Fäh, Donat

    2012-10-01

    Passive seismic surveying methods represent a valuable tool in local seismic hazard assessment, oil and gas prospection, and in geotechnical investigations. Array processing techniques are used in order to estimate wavefield properties such as dispersion curves of surface waves and ellipticity of Rayleigh waves. However, techniques presently in use often fail to properly merge information from three-components sensors and do not account for the presence of multiple waves. In this paper, a technique for maximum likelihood estimation of wavefield parameters including direction of propagation, velocity of Love waves and Rayleigh waves, and ellipticity of Rayleigh waves is described. This technique models jointly all the measurements and all the wavefield parameters. Furthermore it is possible to model the simultaneous presence of multiple waves. The performance of this technique is evaluated on a high-fidelity synthetic data set and on real data. It is shown that the joint modelling of all the sensor components, decreases the variance of wavenumber estimates and allows the retrieval of the ellipticity value together with an estimate of the prograde/retrograde motion.

  7. Harvesting Ambient Vibration Energy over a Wide Frequency Range for Self-Powered Electronics.

    Science.gov (United States)

    Wang, Xiaofeng; Niu, Simiao; Yi, Fang; Yin, Yajiang; Hao, Chenglong; Dai, Keren; Zhang, Yue; You, Zheng; Wang, Zhong Lin

    2017-02-28

    Vibration is one of the most common energy sources in ambient environment. Harvesting vibration energy is a promising route to sustainably drive small electronics. This work introduces an approach to scavenge vibrational energy over a wide frequency range as an exclusive power source for continuous operation of electronics. An elastic multiunit triboelectric nanogenerator (TENG) is rationally designed to efficiently harvest low-frequency vibration energy, which can provide a maximum instantaneous output power density of 102 W·m(-3) at as low as 7 Hz and maintain its stable current outputs from 5 to 25 Hz. A self-charging power unit (SCPU) combining the TENG and a 10 mF supercapacitor gives a continuous direct current (DC) power delivery of 1.14 mW at a power management efficiency of 45.6% at 20 Hz. The performance of the SCPU can be further enhanced by a specially designed power management circuit, with a continuous DC power of 2 mW and power management efficiency of 60% at 7 Hz. Electronics such as a thermometer, hygrometer, and speedometer can be sustainably powered solely by the harvested vibration energy from a machine or riding bicycle. This approach has potential applications in self-powered systems for environment monitoring, machine safety, and transportation.

  8. Metrology of vibration measurements by laser techniques

    Science.gov (United States)

    von Martens, Hans-Jürgen

    2008-06-01

    Metrology as the art of careful measurement has been understood as uniform methodology for measurements in natural sciences, covering methods for the consistent assessment of experimental data and a corpus of rules regulating application in technology and in trade and industry. The knowledge, methods and tools available for precision measurements can be exploited for measurements at any level of uncertainty in any field of science and technology. A metrological approach to the preparation, execution and evaluation (including expression of uncertainty) of measurements of translational and rotational motion quantities using laser interferometer methods and techniques will be presented. The realization and dissemination of the SI units of motion quantities (vibration and shock) have been based on laser interferometer methods specified in international documentary standards. New and upgraded ISO standards are reviewed with respect to their suitability for ensuring traceable vibration measurements and calibrations in an extended frequency range of 0.4 Hz to higher than 100 kHz. Using adequate vibration exciters to generate sufficient displacement or velocity amplitudes, the upper frequency limits of the laser interferometer methods specified in ISO 16063-11 for frequencies procedures (i.e. measurement uncertainty 0.05 % at frequencies <= 10 kHz, <= 1 % up to 100 kHz).

  9. Knowledge Discovery from Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Jun Deng

    2014-01-01

    Full Text Available The framework as well as the particular algorithms of pattern recognition process is widely adopted in structural health monitoring (SHM. However, as a part of the overall process of knowledge discovery from data bases (KDD, the results of pattern recognition are only changes and patterns of changes of data features. In this paper, based on the similarity between KDD and SHM and considering the particularity of SHM problems, a four-step framework of SHM is proposed which extends the final goal of SHM from detecting damages to extracting knowledge to facilitate decision making. The purposes and proper methods of each step of this framework are discussed. To demonstrate the proposed SHM framework, a specific SHM method which is composed by the second order structural parameter identification, statistical control chart analysis, and system reliability analysis is then presented. To examine the performance of this SHM method, real sensor data measured from a lab size steel bridge model structure are used. The developed four-step framework of SHM has the potential to clarify the process of SHM to facilitate the further development of SHM techniques.

  10. Knowledge discovery from vibration measurements.

    Science.gov (United States)

    Deng, Jun; Li, Jian; Wang, Daoyao

    2014-01-01

    The framework as well as the particular algorithms of pattern recognition process is widely adopted in structural health monitoring (SHM). However, as a part of the overall process of knowledge discovery from data bases (KDD), the results of pattern recognition are only changes and patterns of changes of data features. In this paper, based on the similarity between KDD and SHM and considering the particularity of SHM problems, a four-step framework of SHM is proposed which extends the final goal of SHM from detecting damages to extracting knowledge to facilitate decision making. The purposes and proper methods of each step of this framework are discussed. To demonstrate the proposed SHM framework, a specific SHM method which is composed by the second order structural parameter identification, statistical control chart analysis, and system reliability analysis is then presented. To examine the performance of this SHM method, real sensor data measured from a lab size steel bridge model structure are used. The developed four-step framework of SHM has the potential to clarify the process of SHM to facilitate the further development of SHM techniques.

  11. Structural Integrity Monitoring by Vibration Measurements

    OpenAIRE

    Yan, Ai-Min; De Boe, Pascal; Golinval, Jean-Claude

    2003-01-01

    This paper presents a comparative study on several approaches of structural dam-age diagnosis based on vibration meas-urements. Stochastic subspace identifica-tion method is used to identify modal pa-rameters and to generate a Kalman predic-tion model, which are taken as damage-sensitive features for structural damage detection. A statistical process control technique based on principal component analysis (PCA) is also presented. An im-provement and enhancement of PCA is proposed. It is assum...

  12. Measurement of small vibration by laser interferometer

    Institute of Scientific and Technical Information of China (English)

    QIAN Menglu; LIU Hewei

    2003-01-01

    The method and experimental results of measuring a small vibrating displacement by laser interferometer are introduced in this paper. The dynamic response of a new kind of tiny piezoelectric driver is detected. Results show that this kind of PZN-PZT tiny driver not only has high voltage-displacement sensitivity, but also its frequency response approaches to 1 kHz.Therefore this kind of piezoelectric driver can be used widely in many fields.

  13. Evaluation of the quality of ambient vibration monitoring data from the Henry Hudson Bridge

    Science.gov (United States)

    Pan, Qin; Grimmelsman, Kirk A.; Prader, John; Aktan, A. E.

    2006-03-01

    The quality of test data is an important consideration in conducting field experiments on civil infrastructure. In addition to possible errors due to the experimental setup, the uncertainties due to incomplete knowledge of a structure's behavior and its interactions with the natural environment greatly affect the reliability of the system identification results. This paper discusses the uncertainties related to ambient vibration testing of a long-span steel arch bridge and possible ways to mitigate them. The consistency of the identified parameters is examined through statistical analyses.

  14. Dynamic Characteristics of a Tall Building Identified from Earthquake and Ambient Vibration Records

    OpenAIRE

    Andone Cristian; Demetriu Sorin; Aldea Alexandru

    2015-01-01

    The paper presents the modal characteristics of a tall building in Bucharest (BRD-SG Tower) identified from earthquake and ambient vibration records. The building was built in the early 2000’s and has a reinforced concrete structure (inner shear wall tube and perimeter frames) with 3 underground stories, ground floor and 18 stories. The seismic instrumentation of the building consists of a seismic station with two triaxial acceleration sensors located at the top of the building (+69.6 m) and ...

  15. Modal identification using the frequency-scale domain decomposition technique of ambient vibration responses

    Science.gov (United States)

    Le, Thien-Phu; Argoul, Pierre

    2016-12-01

    This paper proposes a new modal identification method of ambient vibration responses. The application of the singular value decomposition to continuous wavelet transform of power spectral density matrix gives singular values and singular vectors in frequency-scale domain. Analytical development shows a direct relation between local maxima in frequency-scale representation of singular values and modal parameters. This relation is then carried on for the identification of modal parameters via a complete practical procedure. The main novelties of this work involve the new formulation in frequency-scale domain and the capacity for the identification of modal parameters without the step of ridges extraction in comparison with previous wavelet-based modal identification methods.

  16. Noncontact vibration measurements using magnetoresistive sensing elements

    Science.gov (United States)

    Tomassini, R.; Rossi, G.

    2016-06-01

    Contactless instrumentations is more and more used in turbomachinery testing thanks to the non-intrusive character and the possibility to monitor all the components of the machine at the same time. Performances of blade tip timing (BTT) measurement systems, used for noncontact turbine blade vibration measurements, in terms of uncertainty and resolution are strongly affected by sensor characteristics and processing methods. The sensors used for BTT generate pulses, used for precise measurements of turbine blades time of arrival. Nowadays proximity sensors used in this application are based on optical, capacitive, eddy current and microwave measuring principle. Pressure sensors has been also tried. This paper summarizes the results achieved using a novel instrumentation based on the magnetoresistive sensing elements. The characterization of the novel probe has been already published. The measurement system was validated in test benches and in a real jet-engine comparing different sensor technologies. The whole instrumentation was improved. The work presented in this paper focuses on the current developments. In particular, attention is given to the data processing software and new sensor configurations.

  17. Camera vibration measurement using blinking light-emitting diode array.

    Science.gov (United States)

    Nishi, Kazuki; Matsuda, Yuichi

    2017-01-23

    We present a new method for measuring camera vibrations such as camera shake and shutter shock. This method successfully detects the vibration trajectory and transient waveforms from the camera image itself. We employ a time-varying pattern as the camera test chart over the conventional static pattern. This pattern is implemented using a specially developed blinking light-emitting-diode array. We describe the theoretical framework and pattern analysis of the camera image for measuring camera vibrations. Our verification experiments show that our method has a detection accuracy and sensitivity of 0.1 pixels, and is robust against image distortion. Measurement results of camera vibrations in commercial cameras are also demonstrated.

  18. Effects of vibration measurement error on remote sensing image restoration

    Science.gov (United States)

    Sun, Xuan; Wei, Zhang; Zhi, Xiyang

    2016-10-01

    Satellite vibrations would lead to image motion blur. Since the vibration isolators cannot fully suppress the influence of vibrations, image restoration methods are usually adopted, and the vibration characteristics of imaging system are usually required as algorithm inputs for better restoration results, making the vibration measurement error strongly connected to the final outcome. If the measurement error surpass a certain range, the restoration may not be implemented successfully. Therefore it is important to test the applicable scope of restoration algorithms and control the vibrations within the range, on the other hand, if the algorithm is robust, then the requirements for both vibration isolator and vibration detector can be lowered and thus less financial cost is needed. In this paper, vibration-induced degradation is first analyzed, based on which the effects of measurement error on image restoration are further analyzed. The vibration-induced degradation is simulated using high resolution satellite images and then the applicable working condition of typical restoration algorithms are tested with simulation experiments accordingly. The research carried out in this paper provides a valuable reference for future satellite design which plan to implement restoration algorithms.

  19. Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation

    NARCIS (Netherlands)

    Segerink, F.B.; Korterik, J.P.; Offerhaus, H.L.

    2011-01-01

    This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in

  20. Torsional and Bending Vibration Measurement on Rotors Using Laser Technology

    Science.gov (United States)

    MILES, T. J.; LUCAS, M.; HALLIWELL, N. A.; ROTHBERG, S. J.

    1999-09-01

    Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) was developed for non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. This paper describes comprehensive theory to account for the sensitivity of the LTV's measurements to shaft motion in all degrees of freedom. The optical geometry of the LTV offers inherent immunity to translational motion of the target shaft, either axial or radial. However, its measurements are sensitive to angular lateral vibration of the shaft. The significance of this sensitivity is compared with the instrument noise floor and typical torsional and lateral vibration levels. Optimum alignments of the instrument are then specified to ensure effective immunity to all lateral motion in typical applications. To overcome this problem more reliably, a new technique is proposed permitting unambiguous measurement of pure torsional vibration in situations where use of a single LTV demonstrates unacceptable sensitivity to angular lateral vibrations. Practical application of this technology is demonstrated with torsional vibration measurements from a diesel engine crankshaft. Simultaneously, previously unattained measurements of shaft bending vibration measurements are made. The first bending mode of the crankshaft was identified and its vibration amplitude and damping estimated. This application of laser vibrometry for non-contact measurements of shaft vibration represents a further step forward in the use of this technology for machinery diagnostics.

  1. Global Nonlinear Analysis of Piezoelectric Energy Harvesting from Ambient and Aeroelastic Vibrations

    Science.gov (United States)

    Abdelkefi, Abdessattar

    Converting vibrations to a usable form of energy has been the topic of many recent investigations. The ultimate goal is to convert ambient or aeroelastic vibrations to operate low-power consumption devices, such as microelectromechanical systems, heath monitoring sensors, wireless sensors or replacing small batteries that have a finite life span or would require hard and expensive maintenance. The transduction mechanisms used for transforming vibrations to electric power include: electromagnetic, electrostatic, and piezoelectric mechanisms. Because it can be used to harvest energy over a wide range of frequencies and because of its ease of application, the piezoelectric option has attracted significant interest. In this work, we investigate the performance of different types of piezoelectric energy harvesters. The objective is to design and enhance the performance of these harvesters. To this end, distributed-parameter and phenomenological models of these harvesters are developed. Global analysis of these models is then performed using modern methods of nonlinear dynamics. In the first part of this Dissertation, global nonlinear distributed-parameter models for piezoelectric energy harvesters under direct and parametric excitations are developed. The method of multiple scales is then used to derive nonlinear forms of the governing equations and associated boundary conditions, which are used to evaluate their performance and determine the effects of the nonlinear piezoelectric coefficients on their behavior in terms of softening or hardening. In the second part, we assess the influence of the linear and nonlinear parameters on the dynamic behavior of a wing-based piezoaeroelastic energy harvester. The system is composed of a rigid airfoil that is constrained to pitch and plunge and supported by linear and nonlinear torsional and flexural springs with a piezoelectric coupling attached to the plunge degree of freedom. Linear analysis is performed to determine the

  2. Nondestructive Evaluation of Railway Bridge by System Identification Using Field Vibration Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Duc Duy; Hong, Dong Soo; Kim, Jeong Tae [Pukyong National University, Busan (Korea, Republic of)

    2010-12-15

    This paper presents a nondestructive evaluation approach for system identification (SID) of real railway bridges using field vibration test results. First, a multi-phase SID scheme designed on the basis of eigenvalue sensitivity concept is presented. Next, the proposed multi-phase approach is evaluated from field vibration tests on a real railway bridge (Wondongcheon bridge) located in Yangsan, Korea. On the steel girder bridge, a few natural frequencies and mode shapes are experimentally measured under the ambient vibration condition. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model established for the target bridge. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model-updating procedure. Based on model-updating results, a baseline model and a nondestructive evaluation of test bridge are identified

  3. Optical fiber sensor for membrane submicrometer vibration measurement.

    Science.gov (United States)

    Prokopczuk, Krzysztof; Rozwadowski, Krzysztof; Aleksandra Starzyńska, M D; Domański, Andrzej W

    2014-09-10

    This paper presents an optical fiber sensor for membrane submicrometer vibration measurement. The sensor is designed ultimately for low-cost medical audiometric applications such as determining the mobility of the tympanic membrane stimulated by the tone. The sensing method is minimally invasive, and the sensing head does not contact the surface of the membrane. Measurements were performed on tympanic membrane phantoms. Deflections of a few nanometers were measured, and vibration maps of phantoms were taken.

  4. Effect of vehicle weight on natural frequencies of bridges measured from traffic-induced vibration

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Recently, ambient vibration test (AVT) is widely used to estimate dynamic characteristics of large civil structures. Dynamic characteristics can be affected by various environmental factors such as humidity, intensity of wind, and temperature. Besides these environmental conditions, the mass of vehicles may change the measured values when traffic-induced vibration is used as a source of AVT for bridges. The effect of vehicle mass on dynamic characteristics is investigated through traffic-induced vibration tests on three bridges; (1) three-span suspension bridge (128m+404m+128m), (2) five-span continuous steel box girder bridge (59m+3@95m+59m), (3) simply supported plate girder bridge (46m). Acceleration histories of each measurement location under normal traffic are recorded for 30 minutes at field. These recorded histories are divided into individual vibrations and are combined into two groups according to the level of vibration; one by heavy vehicles such as trucks and buses and the other by light vehicles such as passenger cars. Separate processing of the two groups of signals shows that, for the middle and long-span bridges, the difference can be hardly detected, but, for the short span bridges whose mass is relatively small, the measured natural frequencies can change up to 5.4%.

  5. Vibration measurements of a wire scanner - Experimental setup and models

    Science.gov (United States)

    Herranz, Juan; Barjau, Ana; Dehning, Bernd

    2016-03-01

    In the next years the luminosity of the LHC will be significantly increased. This will require a much higher accuracy of beam profile measurement than actually achievable by the current wire scanner. The new performance demands a wire travelling speed up to 20 m s-1 and a position measurement accuracy of the order of 1 μm. The vibrations of the mechanical parts of the system and particularly the vibrations of the thin carbon wire have been identified as the major error sources of wire position uncertainty. Therefore the understanding of the wire vibrations has been given high priority for the design and operation of the new device. This article presents a new strategy to measure the wire vibrations based on the piezoresistive effect of the wire itself. An electronic readout system based on a Wheatstone bridge is used to measure the variation of the carbon wire resistance, which is directly proportional to the wire elongation caused by the oscillations.

  6. ambiental

    Directory of Open Access Journals (Sweden)

    Roque Leal Salcedo

    2008-01-01

    Full Text Available El derecho internacional ambiental es un conocimiento de carácter transversal, que entre otras consideraciones refleja las preocupaciones de la sociedad por la implementación de un modelo de desarrollo sustentable para el respeto a las reglas del medio natural que garantizan la integridad y renovación de los sistemas naturales. El presente artículo enfoca esta visión a través del análisis de material documental revisado, entre ellos tratados internacionales que permiten distinguir el desarrollo del derecho internacional ambiental y el papel de Organización de las Naciones Unidas (ONU, en el propósito común del derecho individual y colectivo de disfrutar de una vida, un ambiente seguro, sano y ecológicamente equilibrado. En función a estas disertaciones las consideraciones finales exponen parte de la visión que ha estructurado la ONU y que representan un aporte considerable en el fomento de la conciencia mundial sobre la necesidad de establecer vínculos entre las naciones para el continuo desarrollo de esta rama del derecho.

  7. Ambient sesquiterpene concentration and its link to air ion measurements

    Directory of Open Access Journals (Sweden)

    B. Bonn

    2006-12-01

    Full Text Available Ambient air ion size distributions have been measured continuously at the Finnish boreal forest site in Hyytiälä since spring 2003. In general, these measurements show a maximum of air ions below 1.0 nm in diameter. But this physical characterization does not provide any information about the ion's chemical composition, which is one key question regarding the explanation of nucleation events observed. In this study we propose a link of the observed maximum of negative air ions between 0.56 and 0.75 nm to the so-called stabilised Criegee biradical, formed in the reaction of biogenic sesquiterpenes with ozone and predominantly destroyed by its reaction with ambient water vapour. Calculations of the electron and proton affinities of 120 kJ mol−1 (1.24 eV and of 960 kJ mol−1 support this link. Other possible candidates such as sulphuric acid derived clusters are unable to explain the observations made. By using this approach, we are able to calculate the ambient concentration of sesquiterpenes at the air ion instrument inlet with a high time resolution on the daily and seasonal scale. The estimated concentration is found to reveal the same seasonal pattern as emission measurements conducted at shoot level. As expected for biogenic VOCs, the concentration is obtained highest during summer (maximum values of about 100 pptv and smallest during winter (minimum less than 1 pptv. Because of the sesquiterpenes high reactivity and its low ambient concentrations, this approach can be a first step in understanding their emission and their impact on atmospheric chemistry in more detail. The findings presented are highly relevant for emission budgets too, since boreal forests are extended over large areas of the globe.

  8. Ambient sesquiterpene concentration and its link to air ion measurements

    Directory of Open Access Journals (Sweden)

    B. Bonn

    2007-06-01

    Full Text Available Ambient air ion size distributions have been measured continuously at the Finnish boreal forest site in Hyytiälä since spring 2003. In general, these measurements show a maximum of air ions below 1.0 nm in diameter. But this physical characterization does not provide any information about the ion's chemical composition, which is one key question regarding the explanation of nucleation events observed. In this study we propose a link of the observed maximum of negative air ions between 0.56 and 0.75 nm to the so-called stabilised Criegee biradical, formed in the reaction of biogenic sesquiterpenes with ozone and predominantly destroyed by its reaction with ambient water vapour. Calculations of the electron and proton affinities of 120 kJ mol−1 (1.24 eV and of 960 kJ mol−1 support this link. Other possible candidates such as sulphuric acid derived clusters are unable to explain the observations made. By using this approach, we are able to calculate the ambient concentration of sesquiterpenes at the air ion instrument inlet with a high time resolution on the daily and seasonal scale. The estimated concentration is found to reveal the same seasonal pattern as emission measurements conducted at shoot level. As expected for biogenic VOCs, the concentration is obtained highest during summer (maximum values of about 100 pptv and smallest during winter (minimum less than 1 pptv. Because of the sesquiterpenes high reactivity and its low ambient concentrations, this approach can be a first step in understanding their emission and their impact on atmospheric chemistry in more detail. The findings presented are highly relevant for emission budgets too, since boreal forests are extended over large areas of the globe.

  9. Stereovision vibration measurement test of a masonry building model

    Science.gov (United States)

    Shan, Baohua; Gao, Yunli; Shen, Yu

    2016-04-01

    To monitor 3D deformations of structural vibration response, a stereovision-based 3D deformation measurement method is proposed in paper. The world coordinate system is established on structural surface, and 3D displacement equations of structural vibration response are acquired through coordinate transformation. The algorithms of edge detection, center fitting and matching constraint are developed for circular target. A shaking table test of a masonry building model under Taft and El Centro earthquake at different acceleration peak is performed in lab, 3D displacement time histories of the model are acquired by the integrated stereovision measurement system. In-plane displacement curves obtained by two methods show good agreement, this suggests that the proposed method is reliable for monitoring structural vibration response. Out-of-plane displacement curves indicate that the proposed method is feasible and useful for monitoring 3D deformations of vibration response.

  10. Vibration measurement and modal analysis of boom type tunneller

    Energy Technology Data Exchange (ETDEWEB)

    Min, H.; Gong, L.; Miao, W.; Wei, A. [China University of Mining & Technology, Jiangsu (China)

    2003-04-01

    The vibrations of an AM50 boom tunnelling machine have been measured in real time when cutting a man-made and a real coal bed. The vibration characteristics were similar in these working conditions, i.e. the man-made coal bed can be used as a realistic simulation of real cutting conditions. A modal model of the machine was then established and the intrinsic vibration characteristics were investigated by experimental modal analysis. Vibration response simulations under a set of measured load spectra and structural dynamics modification were also carried out using structural analysis software. The results not only facilitate the structural dynamics modification of the AM50 tunneller but also provide a foundation for optimising the design of new types of tunnelling machine.

  11. Two-dimensional optical coherence vibration tomography for low-frequency vibration measurement and response-only modal analysis

    Science.gov (United States)

    Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun

    2016-10-01

    A high-speed camera-based two-dimensional optical coherence vibration tomography (2DOCVT) system with a subnanometre displacement resolution was developed and employed for low-frequency vibration measurement and modal analysis. Experimental results demonstrated the ability of low-frequency absolute displacement measurement of structural line vibrations without scanning. Three-dimensional (3D) surface displacement of a vibrating structure could also be obtained using the developed 2DOCVT by scanning the structure. The scanning 2DOCVT system acted like a 3D optical coherence vibration tomography system. The developed 2DOCVT system could capture structural modal parameters without vibration excitation input information, and therefore, it is a response-only method. The 2DOCVT could be recommended in the application of low-frequency vibration measurement and modal analysis of beam and plate structures, especially when the vibration amplitude is at nanometre or micrometre scale.

  12. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    Energy Technology Data Exchange (ETDEWEB)

    De Greef, Daniël; Dirckx, Joris J. J. [University of Antwerp, Laboratory of BioMedical Physics, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2014-05-27

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without

  13. Heterodyne Angle Deviation Interferometry in Vibration and Bubble Measurements

    Directory of Open Access Journals (Sweden)

    Ming-Hung Chiu

    2016-07-01

    Full Text Available We proposed heterodyne angle deviation interferometry (HADI for angle deviation measurements. The phase shift of an angular sensor (which can be a metal film or a surface plasmon resonance (SPR prism is proportional to the deviation angle of the test beam. The method has been demonstrated in bubble and speaker’s vibration measurements in this paper. In the speaker’s vibration measurement, the voltage from the phase channel of a lock-in amplifier includes the vibration level and frequency. In bubble measurement, we can count the number of bubbles passing through the cross section of the laser beam and measure the bubble size from the phase pulse signal.

  14. Probabilistic seismic safety assessment of a CANDU 6 nuclear power plant including ambient vibration tests: Case study

    Energy Technology Data Exchange (ETDEWEB)

    Nour, Ali [Hydro Québec, Montréal, Québec H2L4P5 (Canada); École Polytechnique de Montréal, Montréal, Québec H3C3A7 (Canada); Cherfaoui, Abdelhalim; Gocevski, Vladimir [Hydro Québec, Montréal, Québec H2L4P5 (Canada); Léger, Pierre [École Polytechnique de Montréal, Montréal, Québec H3C3A7 (Canada)

    2016-08-01

    Highlights: • In this case study, the seismic PSA methodology adopted for a CANDU 6 is presented. • Ambient vibrations testing to calibrate a 3D FEM and to reduce uncertainties is performed. • Procedure for the development of FRS for the RB considering wave incoherency effect is proposed. • Seismic fragility analysis for the RB is presented. - Abstract: Following the 2011 Fukushima Daiichi nuclear accident in Japan there is a worldwide interest in reducing uncertainties in seismic safety assessment of existing nuclear power plant (NPP). Within the scope of a Canadian refurbishment project of a CANDU 6 (NPP) put in service in 1983, structures and equipment must sustain a new seismic demand characterised by the uniform hazard spectrum (UHS) obtained from a site specific study defined for a return period of 1/10,000 years. This UHS exhibits larger spectral ordinates in the high-frequency range than those used in design. To reduce modeling uncertainties as part of a seismic probabilistic safety assessment (PSA), Hydro-Québec developed a procedure using ambient vibrations testing to calibrate a detailed 3D finite element model (FEM) of the containment and reactor building (RB). This calibrated FE model is then used for generating floor response spectra (FRS) based on ground motion time histories compatible with the UHS. Seismic fragility analyses of the reactor building (RB) and structural components are also performed in the context of a case study. Because the RB is founded on a large circular raft, it is possible to consider the effect of the seismic wave incoherency to filter out the high-frequency content, mainly above 10 Hz, using the incoherency transfer function (ITF) method. This allows reducing significantly the non-necessary conservatism in resulting FRS, an important issue for an existing NPP. The proposed case study, and related methodology using ambient vibration testing, is particularly useful to engineers involved in seismic re-evaluation of

  15. MEASUREMENT OF ADHESION FORCES IN AIR WITH THE VIBRATION METHOD

    Institute of Scientific and Technical Information of China (English)

    Siegfried Ripperger; Konrad Hein

    2005-01-01

    The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally altemating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces. rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.

  16. Vortex induced vibrations of pipe in high waves. Field measurements

    Energy Technology Data Exchange (ETDEWEB)

    Hansen Ottesen, N.-E.; Pedersen, B.

    1999-07-01

    Vortex induced vibrations have been measured full scale on an instrumented pipe placed vertically in the crest zone of high and steep waves. The Reynolds numbers were in the range 105 to 106. It was found that the vortex induced vibrations in the wave motion were generated within a reduced velocity range of 4 and 8. The vibrations grew intermittently with the passing waves. The vibrations took place in 2-3 modes simultaneously. One mode, however, dominated over the other. The growths of the VIV using a modal analysis were consistent with a basic correlation length of 3 diameters for a stationary pipe with a linear growth of the correlation length of 10 diameter for each 0.1 diameter amplitude. (au)

  17. Vibration frequency measurement using a local multithreshold technique.

    Science.gov (United States)

    Ferrer, Belen; Espinosa, Julian; Roig, Ana B; Perez, J; Mas, D

    2013-11-01

    In this paper, we demonstrate the use of a video camera for measuring the frequency of small-amplitude vibration movements. The method is based on image acquisition and multilevel thresholding and it only requires a video camera with high enough acquisition rate, not being necessary the use of targets or auxiliary laser beams. Our proposal is accurate and robust. We demonstrate the technique with a pocket camera recording low-resolution videos with AVI-JPEG compression and measuring different objects that vibrate in parallel or perpendicular direction to the optical sensor. Despite the low resolution and the noise, we are able to measure the main vibration modes of a tuning fork, a loudspeaker and a bridge. Results are successfully compared with design parameters and measurements with alternative devices.

  18. Time Synchronized Wireless Sensor Network for Vibration Measurement

    Science.gov (United States)

    Uchimura, Yutaka; Nasu, Tadashi; Takahashi, Motoichi

    Network based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of building or civil engineering structure and it often requires vibration measurement. For the vibration measurement via wireless network, time synchronization is indispensable. In this paper, we introduce a newly developed time synchronized wireless sensor network system. The system employs IEEE 802.11 standard based TSF counter and sends the measured data with the counter value. TSF based synchronization enables consistency on common clock among different wireless nodes. We consider the scale effect on the synchronization accuracy and the effect is evaluated by stochastic analysis and simulation studies. A new wireless sensing system is developed and the hardware and software specifications are shown. The experiments are conducted in a reinforced concrete building and results show good performance enough for vibration measurement purpose.

  19. Measurement of the vibration of structures with a three-component vibration sensor

    Science.gov (United States)

    Yeskov, V. V.; Konevalov, V. S.; Nikiforov, A. S.

    1973-01-01

    The effects of transverse waves and longitudinal displacements on transverse displacements in a plate are studied using a three component vibration sensor. Limitations of using the sensor in such measurements are: (1) sensor connection to the plate leads to changes in transverse displacement points on the plate surface, (2) the sensor has a finite magnitude of selectivity with respect to vibrations in the direction of the different channel axes, (3) longitudinal displacements of plate surface create restrictions on relative sensitivity of sensor to longitudinal-transverse waves, and (4) tranverse displacement of plate surface during longitudinal wave propagation also creates a restriction on sensor sensitivity to transverse waves.

  20. Dynamic tire pressure sensor for measuring ground vibration.

    Science.gov (United States)

    Wang, Qi; McDaniel, James Gregory; Wang, Ming L

    2012-11-07

    This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By measuring dynamic pressure changes inside the tire, ground vibration can be amplified and isolated from environmental noise. In this work, verifications of the DTPS concept of sensing inside the tire have been carried out. In addition, comparisons between a DTPS, ground-mounted accelerometer, and directional microphone are made. A data analysis algorithm has been developed and optimized to reconstruct ground acceleration from DTPS data. Numerical and experimental studies of this DTPS reveal a strong potential for measuring ground vibration caused by a moving vehicle. A calibration of transfer function between dynamic tire pressure change and ground acceleration may be needed for different tire system or for more accurate application.

  1. Improving the shear wave velocity structure beneath Bucharest (Romania) using ambient vibrations

    Science.gov (United States)

    Manea, Elena Florinela; Michel, Clotaire; Poggi, Valerio; Fäh, Donat; Radulian, Mircea; Balan, Florin Stefan

    2016-11-01

    Large earthquakes from the intermediate-depth Vrancea seismic zone are known to produce in Bucharest ground motion characterized by predominant long periods. This phenomenon has been interpreted as the combined effect of both seismic source properties and site response of the large sedimentary basin. The thickness of the unconsolidated Quaternary deposits beneath the city is more than 200 m, the total depth of sediments is more than 1000 m. Complex basin geometry and the low seismic wave velocities of the sediments are primarily responsible for the large amplification and long duration experienced during earthquakes. For a better understanding of the geological structure under Bucharest, a number of investigations using non-invasive methods have been carried out. With the goal to analyse and extract the polarization and dispersion characteristics of the surface waves, ambient vibrations and low-magnitude earthquakes have been investigated using single station and array techniques. Love and Rayleigh dispersion curves (including higher modes), Rayleigh waves ellipticity and SH-wave fundamental frequency of resonance (f0SH) have been inverted simultaneously to estimate the shear wave velocity structure under Bucharest down to a depth of about 8 km. Information from existing borehole logs was used as prior to reduce the non-uniqueness of the inversion and to constrain the shallow part of the velocity model (<300 m). In this study, we use data from a 35-km diameter array (the URS experiment) installed by the National Institute for Earth Physics and by the Karlsruhe Institute of Technology during 10 months in the period 2003-2004. The array consisted of 32 three-component seismological stations, deployed in the urban area of Bucharest and adjacent zones. The large size of the array and the broad-band nature of the available sensors gave us the possibility to characterize the surface wave dispersion at very low frequencies (0.05-1 Hz) using frequency-wavenumber techniques

  2. Chemical ionization mass spectrometer (CIMS for ambient measurements of ammonia

    Directory of Open Access Journals (Sweden)

    D. R. Benson

    2010-03-01

    Full Text Available This study describes a chemical ionization mass spectrometer (CIMS for fast response, in-situ measurements for gas phase ammonia. Protonated ethanol ions were used as the ion-molecule reaction reagent. The CIMS sensitivity was estimated to be between 4–25 Hz/pptv with 30% uncertainty. The instrument background was below 1 ppbv and at lowest was 300 pptv. The uncertainty associated with the instrumental background was less than 30 pptv under the optimized experimental conditions. The time response was less than 30 s, and the detection limit was approximately 60 pptv. This CIMS was used to measure the ambient NH3 in Kent, Ohio, for several weeks throughout three seasons. The measured ammonia mixing ratios were usually at the sub-ppbv level, and higher during the spring (200±120 pptv than in the winter (60±75 pptv and fall (150±80 pptv.

  3. Method for measurement of volatile oxygenated hydrocarbons in ambient air

    Science.gov (United States)

    Leibrock, E.; Slemr, J.

    An automated gas chromatographic method for the quantitative determination of oxygenated (C 2C 5 carbonyls and C 1C 2 alcohols) and some non-oxygenated (C 5C 8) hydrocarbons in ambient air has been developed. The analytical system consists of a gas chromatograph with a cryogenic sampling trap, a precolumn for the separation of water and other interfering compounds, a cryogenic focusing trap and two analytical columns connected in series. Substances are detected either by flame ionization or by a mass spectrometer. Ozone is removed by a potassium iodide scrubber placed upstream the sampling trap. External gas standards generated by a permeation device are used for calibration. The detection limits range between 0.03 and 0.08 ng (depending on the compound), equivalent to 5 to 56 ppt in 1 l of sampled air. The method was tested by an intercomparison with a different gas chromatographic technique for the determination of NMHC. The system has been applied since 1994 for measurements in ambient air. Data obtained during an intensive campaign in summer 1995 at the field station Wank (1778 m a.s.l.) near Garmisch-Partenkirchen, Germany, are reported and compared with NMHC mixing ratios measured simultaneously in the same air masses.

  4. In-situ Vibration Measurements of the CTF2 Quadrupoles

    CERN Document Server

    Coosemans, Williame

    2004-01-01

    The Compact LInear Collider (CLIC), presently under study at the European Organization for Nuclear Research (CERN), aims at colliding high energy â€ワnanobeams” at a luminosity of 1035 cm-2s-1. Vibrations of the lattice elements, if not properly corrected, can result in a loss in performance by creating both unacceptable emittance growth in the linear accelerator and relative beam-beam offsets at the interaction point. Of particular concern are the vibrations induced by the accelerator environment. For example, the circulating water used to cool the lattice quadrupoles will increase magnet vibration levels. In the framework of the CLIC stability study, in-situ measurements of quadrupole vibrations have been performed at the CLIC Test Facility 2 (CTF2) with all accelerator equipment switched on. Since the CTF2 quadrupoles and their alignment support structures are realistic prototypes of those to be used in the CLIC linac, the measurements provide a realistic estimate of the CLIC magnet vibrations in a...

  5. Optical vibration and deviation measurement of rotating machine parts

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV).

  6. Optimization of a vacuum chamber for vibration measurements.

    Science.gov (United States)

    Danyluk, Mike; Dhingra, Anoop

    2011-10-01

    A 200 °C high vacuum chamber has been built to improve vibration measurement sensitivity. The optimized design addresses two significant issues: (i) vibration measurements under high vacuum conditions and (ii) use of design optimization tools to reduce operating costs. A test rig consisting of a cylindrical vessel with one access port has been constructed with a welded-bellows assembly used to seal the vessel and enable vibration measurements in high vacuum that are comparable with measurements in air. The welded-bellows assembly provides a force transmissibility of 0.1 or better at 15 Hz excitation under high vacuum conditions. Numerical results based on design optimization of a larger diameter chamber are presented. The general constraints on the new design include material yield stress, chamber first natural frequency, vibration isolation performance, and forced convection heat transfer capabilities over the exterior of the vessel access ports. Operating costs of the new chamber are reduced by 50% compared to a preexisting chamber of similar size and function.

  7. Frequency and damping ratio assessment of high-rise buildings using an Automatic Model-Based Approach applied to real-world ambient vibration recordings

    Science.gov (United States)

    Nasser, Fatima; Li, Zhongyang; Gueguen, Philippe; Martin, Nadine

    2016-06-01

    This paper deals with the application of the Automatic Model-Based Approach (AMBA) over actual buildings subjected to real-world ambient vibrations. In a previous paper, AMBA was developed with the aim of automating the estimation process of the modal parameters and minimizing the estimation error, especially that of the damping ratio. It is applicable over a single-channel record, has no parameters to be set, and no manual initialization phase. The results presented in this paper should be regarded as further documentation of the approach over real-world ambient vibration signals.

  8. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  9. Optical measurements of long-range protein vibrations

    Science.gov (United States)

    Acbas, Gheorghe; Niessen, Katherine A.; Snell, Edward H.; Markelz, A. G.

    2014-01-01

    Protein biological function depends on structural flexibility and change. From cellular communication through membrane ion channels to oxygen uptake and delivery by haemoglobin, structural changes are critical. It has been suggested that vibrations that extend through the protein play a crucial role in controlling these structural changes. While nature may utilize such long-range vibrations for optimization of biological processes, bench-top characterization of these extended structural motions for engineered biochemistry has been elusive. Here we show the first optical observation of long-range protein vibrational modes. This is achieved by orientation-sensitive terahertz near-field microscopy measurements of chicken egg white lysozyme single crystals. Underdamped modes are found to exist for frequencies >10 cm-1. The existence of these persisting motions indicates that damping and intermode coupling are weaker than previously assumed. The methodology developed permits protein engineering based on dynamical network optimization.

  10. Wash-out of ambient air contaminations for breath measurements.

    Science.gov (United States)

    Maurer, F; Wolf, A; Fink, T; Rittershofer, B; Heim, N; Volk, T; Baumbach, J I; Kreuer, S

    2014-06-01

    In breath analysis, ambient air contaminations are ubiquitous and difficult to eliminate. This study was designed to investigate the reduction of ambient air background by a lung wash-out with synthetic air. The reduction of the initial ambient air volatile organic compound (VOC) intensity was investigated in the breath of 20 volunteers inhaling synthetic air via a sealed full face mask in comparison to inhaling ambient air. Over a period of 30 minutes, breath analysis was conducted using ion mobility spectrometry coupled to a multi-capillary column. A total of 68 VOCs were identified for inhaling ambient air or inhaling synthetic air. By treatment with synthetic air, 39 VOCs decreased in intensity, whereas 29 increased in comparison to inhaling ambient air. In total, seven VOCs were significantly reduced (P-value ambient air contaminations from the airways by a lung wash-out with synthetic air.

  11. Sound Power Estimation by Laser Doppler Vibration Measurement Techniques

    Directory of Open Access Journals (Sweden)

    G.M. Revel

    1998-01-01

    Full Text Available The aim of this paper is to propose simple and quick methods for the determination of the sound power emitted by a vibrating surface, by using non-contact vibration measurement techniques. In order to calculate the acoustic power by vibration data processing, two different approaches are presented. The first is based on the method proposed in the Standard ISO/TR 7849, while the second is based on the superposition theorem. A laser-Doppler scanning vibrometer has been employed for vibration measurements. Laser techniques open up new possibilities in this field because of their high spatial resolution and their non-intrusivity. The technique has been applied here to estimate the acoustic power emitted by a loudspeaker diaphragm. Results have been compared with those from a commercial Boundary Element Method (BEM software and experimentally validated by acoustic intensity measurements. Predicted and experimental results seem to be in agreement (differences lower than 1 dB thus showing that the proposed techniques can be employed as rapid solutions for many practical and industrial applications. Uncertainty sources are addressed and their effect is discussed.

  12. Structural Health Monitoring Using Wireless Technologies: An Ambient Vibration Test on the Adolphe Bridge, Luxembourg City

    Directory of Open Access Journals (Sweden)

    Adrien Oth

    2012-01-01

    Full Text Available Major threats to bridges primarily consist of the aging of the structural elements, earthquake-induced shaking and standing waves generated by windstorms. The necessity of information on the state of health of structures in real-time, allowing for timely warnings in the case of damaging events, requires structural health monitoring (SHM systems that allow the risks of these threats to be mitigated. Here we present the results of a short-duration experiment carried out with low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of a strategic civil infrastructure, the Adolphe Bridge in Luxembourg City. The Adolphe Bridge is a masonry arch construction dating from 1903 and will undergo major renovation works in the upcoming years. Our experiment shows that a network of these wireless sensing units is well suited to monitor the vibration characteristics of such a historical arch bridge and hence represents a low-cost and efficient solution for SHM.

  13. A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

    Directory of Open Access Journals (Sweden)

    D. R. Benson

    2010-08-01

    Full Text Available This study presents a chemical ionization mass spectrometer (CIMS for fast response, in-situ measurements of gas phase ammonia (NH3. The NH3 background level detected with the CIMS ranged between 0.3–1 ppbv, with an uncertainty of 30 pptv under optimized conditions. The instrument sensitivity varied from 4–25 Hz/pptv for >1 MHz of reagent ion signals (protonated ethanol ions, with a 30% uncertainty estimated based on variability in calibration signals. The CIMS detection limit for NH3 was ~60 pptv at a 1 min integration time (3 sigma. The CIMS time response was <30 s. This new NH3-CIMS has been used for ambient measurements in Kent, Ohio, for several weeks throughout three seasons. The measured NH3 mixing ratios were usually at the sub-ppbv level and higher in spring (200 ± 120 pptv than in winter (60 ± 75 pptv and fall (150 ± 80 pptv. High emissions of SO2 from power plants in this region, and thus possible high acidity of aerosol particles, may explain these low NH3 mixing ratios in general.

  14. Study of Three-Component FBG Vibration Sensor for Simultaneous Measurement of Vibration, Temperature, and Verticality

    Directory of Open Access Journals (Sweden)

    Jiang Shan-chao

    2015-01-01

    Full Text Available To achieve simultaneous measurement of measurand vibration, temperature, and verticality, a three-component fiber Brag grating (TVFBG vibration sensor is proposed in this paper. Polymer and metal diaphragm sensitization methods are utilized to improve this sensor measurement sensitivity. Project matrix theory is adopted to analyze this sensor. Theoretically, 9×9 nonsingular measuring coefficient matrix of this TVFBG sensor made up by three 3×3 measurand coefficient matrixes is established. In order to effectively extract measurand, Hilbert-Huang transform (HHT is accepted to process this sensor’s center wavelength signals. Calibration experiments are carried out to verify the performance of this TVFBG sensor. Experiment data confirm that this sensor has excellent frequency response and show good linearity at temperature and verticality measurement. Wrist rotation angle measurement experiment is also implemented to further identify this sensor practical value. Through analyzing by HHT, experiment results show that the angle measurement sensitivities of three fiber Brag gratings which are included in this sensor are separately 25.2 pm/°, 38.2 pm/°, and 38.3 pm/°.

  15. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    Science.gov (United States)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  16. VIBRATION MEASUREMENT OF DOUBLE-ENDED TUNING FORKS RESONATOR

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    To enhance the coherence and reliability of the double-ended tuning fork (DETF) resonator, a measurement system of resonator vibration is presented to check its dynamic characteristics. Laser Doppler techniques are utilized and the relation between DETF vibration velocity and output current of photodetector is obtained. Resonator vibration equation is also analyzed and its driving power only depends on the direct current bias voltage and the amplitude of alternative voltage. Furthermore, a special resonator driving control circuit based on measurement is designed. The amplitude and frequency of circuit is controlled by a computer so that highly stable and strong driving signal can be output. Experiments on driving and measuring double-ended tuning fork have been done. The frequency of driving signal is 8 kHz and the peak-to-peak value of driving voltage is 140 V. Experimental results indicate resonator can be drived stably by driving control circuit and dynamic characteristics of DETF may be measured in real time.

  17. Vibrational and rotational temperature measurements in a shock tube

    Science.gov (United States)

    Sharma, S. P.

    1992-01-01

    Vibrational and rotational temperatures in nitrogen test gas relaxing behind a normal shock are measured using the emission spectra of N2(+)(1-) and N2(2+) band systems in an electric-arc driven shock tube, at a shock velocity of 6.2 km/sec. The results are compared with similar data obtained by AVCO-Everett Research Laboratory during the 1960s. The vibrational and rotational temperatures in the equilibrium region obtained in the present experiment agreed with those of AVCO, but those in the nonequilibrium region are greatly different from the AVCO results. The measured rotational temperature seems to be in nonequilibrium with the translational temperature, contradicting the two-temperature model widely used in CFD. Also, the relaxation rates for both N2(+) and N2 molecules seem to be of the same order.

  18. Effects of helicopter noise and vibration on pilot performance (as measured in a fixed-base flight simulator)

    Science.gov (United States)

    Stave, A. M.

    1973-01-01

    The effects of noise and vibration on pilot performance are described. Pilot subjects were required to fly VTOL commercial IFR schedules using the computer simulation facilities. The routes flown simulated closely metropolitan routes flown currently by a helicopter airline. The duration of simulator flights ranged from 3 to 8 hours. Subjects were exposed to noise sound pressure levels ranging from 74dB (ambient) to 100dB and 17 Hz vibration stimuli ranging from .1 g to .3 g measured at the floor directly beneath the pilot's seat. Despite subject reports of extreme fatigue in these long flights, performance did not degrade. A curve of performance shows a slow improvement for the first three hours of exposure and a slight loss in performance during the remainder of the flight. As environmental stress conditions (noise, vibration, and time in the simulator) increased, subject performance improved. Within the limits of this study, the higher the stress the better the performance.

  19. Customized DSP-based vibration measurement for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    LaWhite, N.E.; Cohn, K.E. [Second Wind Inc., Somerville, MA (United States)

    1996-12-31

    As part of its Advanced Distributed Monitoring System (ADMS) project funded by NREL, Second Wind Inc. is developing a new vibration measurement system for use with wind turbines. The system uses low-cost accelerometers originally designed for automobile airbag crash-detection coupled with new software executed on a Digital Signal Processor (DSP) device. The system is envisioned as a means to monitor the mechanical {open_quotes}health{close_quotes} of the wind turbine over its lifetime. In addition the system holds promise as a customized emergency vibration detector. The two goals are very different and it is expected that different software programs will be executed for each function. While a fast Fourier transform (FFT) signature under given operating conditions can yield much information regarding turbine condition, the sampling period and processing requirements make it inappropriate for emergency condition monitoring. This paper briefly reviews the development of prototype DSP and accelerometer hardware. More importantly, it reviews our work to design prototype vibration alarm filters. Two-axis accelerometer test data from the experimental FloWind vertical axis wind turbine is analyzed and used as a development guide. Two levels of signal processing are considered. The first uses narrow band pre-processing filters at key fundamental frequencies such as the 1P, 2P and 3P. The total vibration energy in each frequency band is calculated and evaluated as a possible alarm trigger. In the second level of signal processing, the total vibration energy in each frequency band is further decomposed using the two-axis directional information. Directional statistics are calculated to differentiate between linear translations and circular translations. After analyzing the acceleration statistics for normal and unusual operating conditions, the acceleration processing system described could be used in automatic early detection of fault conditions. 9 figs.

  20. Full-field laser vibration measurement in NDT techniques

    Science.gov (United States)

    Yue, Kaiduan; Li, Zhongke; Yi, Yaxing; Zhang, Fei

    2008-12-01

    Research of Non Destructive Testing (NDT) methodology has developed rapidly in recent years[1][2]. But it is rarely used for small objects such as Micro-electronic Mechanics System. Due to the small size of the MEMS, the traditional method of contact measurement seriously affects the parameter of the object measured. So a high accuracy non-contact measurement is required for optimization of MEMS designs and improvement of its reliability[3][4]. With recent advances in photonics, electronics, and computer technology, a Non Destructive Testing (NDT) laser time average interferometry is proposed in the paper. Laser interferometry has the advantages of non-contact, high accuracy, full-field and fast speed, so it can be used to detect cracks in MEMS. A time average measurement method of digital speckle pattern interferometry is proposed to measure the vibration mode of the MEMS in the paper. According to the sudden change of amplitude of vibration mode, a crack can be measured. With the speckle average technology, high accuracy phase-shift, continuous phase scanning technology, combined with optical amplification technology, the resolution of the amplitude reaches 1nm, and the resolution of the crack reaches 5μm. The measurement system being full-field, the measuring speed of the measurement system can reach 512*512 points per one minute.

  1. VIBRATION MEASUREMENTS IN A RHIC QUADRUPOLE AT CRYOGENIC TEMPERATURES.

    Energy Technology Data Exchange (ETDEWEB)

    JAIN, A.; AYDIN, S.; HE, P.; ANERELLA, M.; GANETIS, G.; HARRISON, M.; PARKER, B.; PLATE, S.

    2005-10-17

    One of the concerns in using compact superconducting magnets in the final focus region of the ILC is the influence of the cryogen flow on the vibration characteristics. As a first step towards characterizing such motion at nanometer levels, a project was undertaken at BNL to measure the vibrations in a spare RHIC quadrupole under cryogenic conditions. Given the constraints of cryogenic operation, and limited space available, it was decided to use a dual head laser Doppler vibrometer for this work. The performance of the laser vibrometer was tested in a series of room temperature tests and compared with results from Mark L4 geophones. The laser system was then used to measure the vibration of the cold mass of the quadrupole with respect to the outside warm enclosure. These measurements were carried out both with and without the flow of cold helium through the magnet. The results indicate only a minor increase in motion in the horizontal direction (where the cold mass is relatively free to move).

  2. Dense vibration measurement of an arch bridge before and after its seismic retrofit using wireless smart sensors

    Science.gov (United States)

    Nagayama, Tomonori; Urushima, Akihiko; Fujino, Yozo; Miyashita, Takeshi; Yoshioka, Tsutomu; Ieiri, Masataka

    2012-04-01

    Fundamental functionalities of wireless smart sensors to measure full-scale bridge vibration, such as time synchronization, loss-less multihop communication, and capability to capture small ambient vibrations, are maturing; dense vibration measurement of large structures using wireless smart sensors is expected to reveal the detailed condition of existing structures. An arch bridge is chosen as a target bridge and densely instrumented by 48 wireless smart sensors. Traffic induced vibration of the bridge has been measured before and after its seismic retrofit. The differences between the measured dynamic characteristics are considered to represent the effects of seismic retrofit. The dense measurement allows comparison of spatial characteristics such as detailed mode shapes, in addition to comparison of natural frequencies. Comparison of densely measured mode shapes reveals their changes, which are then used to update the finite element model of the bridge. The measurement, data analysis, and model updating indicate a potential use of dense instrumentation of wireless smart sensor network for structural condition assessment.

  3. Measurements of volatile hydrocarbons in ambient air coking plant `Walbrzych`

    Energy Technology Data Exchange (ETDEWEB)

    Michalski, R.; Weglarz, A.; Skrok, R. [Polish Academy of Sciences, Zabrze (Poland). Inst. of Environmental Engineering

    1998-12-31

    The air is a matrix very difficult to handle. In addition, the pollutants are usually present at very low concentrations. Many techniques can be used to collect air samples. The simplest way is to use special containers, but this procedure is expensive and time-consuming. The adsorption of pollutants on adsorbents shows a growing interest, despite the difficulty to choose the appropriate support in order to obtain quantitative yields. To overcome this problem, two or three types of adsorbents may be used in series for collecting a wide range of analytes. In addition, the miniaturization of these techniques (i.e. microtraps and solid-phase microextraction) is also very promising: easy to handle, low cost, no solvent required, detection limits at ppt level when sensitive detectors are used. If we have no money for this modern equipment we must use traditional methods for compounds determination. This paper describes measurements of volatile hydrocarbons (such as benzene, toluene, ethylbenzene, xylene and phenol) in ambient air of coking plant `Walbrzych` Measuring points were at streets: Beethoven 4, Dworcowa 2, Kosteckiego 5 and Zamkowa 1. BTEX were collected on graphitized carbon and phenol on Chromosorb 102. After that samples were extracted by solvents (dichloromethane for BTEX or benzene for phenol). Next step was the analysis by gas chromatography with flame ionization detector without preconcentration. The lower limit of detection was circa 0.01 {mu}g/m{sup 3} for each of the determined compounds. These measurements of hydrocarbons in town of Walbrzych were performed for two years from 1996 to 1998. 2 tabs.

  4. Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, Laura Butler

    2009-09-01

    A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use of nanowires as AFM cantilevers (rather than as tips for AFM cantilevers). Laser Doppler vibrometry is used to measure the vibration spectra of individual cantilevered nanowires, specifically multiwalled carbon nanotubes (MWNTs) and silver gallium nanoneedles. Since the entire vibration spectrum is measured with high frequency resolution (100 Hz for a 10 MHz frequency scan), the resonant frequencies and quality factors of the nanowires are accurately determined. Using Euler-Bernoulli beam theory, the elastic modulus and spring constant can be calculated from the resonance frequencies of the oscillation spectrum and the dimensions of the nanowires, which are obtained from parallel SEM studies. Because the diameters of the nanowires studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate the lower diameter limit for nanowires whose vibration can be measured in this way. The techniques developed in this thesis can be used to measure the vibrational spectra of any suspended nanowire with high frequency resolution Two different nanowires were measured - MWNTs and Ag{sub 2}Ga nanoneedles. Measurements of the thermal vibration spectra of MWNTs under ambient conditions showed that the elastic modulus, E, of plasma-enhanced chemical vapor deposition (PECVD) MWNTs is 37 {+-} 26 GPa, well within the range of E previously reported for CVD-grown MWNTs. Since the Ag{sub 2}Ga nanoneedles have a greater optical scattering efficiency than

  5. Ambient Intelligence Application Based on Environmental Measurements Performed with an Assistant Mobile Robot

    Directory of Open Access Journals (Sweden)

    Dani Martinez

    2014-03-01

    Full Text Available This paper proposes the use of an autonomous assistant mobile robot in order to monitor the environmental conditions of a large indoor area and develop an ambient intelligence application. The mobile robot uses single high performance embedded sensors in order to collect and geo-reference environmental information such as ambient temperature, air velocity and orientation and gas concentration. The data collected with the assistant mobile robot is analyzed in order to detect unusual measurements or discrepancies and develop focused corrective ambient actions. This paper shows an example of the measurements performed in a research facility which have enabled the detection and location of an uncomfortable temperature profile inside an office of the research facility. The ambient intelligent application has been developed by performing some localized ambient measurements that have been analyzed in order to propose some ambient actuations to correct the uncomfortable temperature profile.

  6. Honeybee Colony Vibrational Measurements to Highlight the Brood Cycle.

    Directory of Open Access Journals (Sweden)

    Martin Bencsik

    Full Text Available Insect pollination is of great importance to crop production worldwide and honey bees are amongst its chief facilitators. Because of the decline of managed colonies, the use of sensor technology is growing in popularity and it is of interest to develop new methods which can more accurately and less invasively assess honey bee colony status. Our approach is to use accelerometers to measure vibrations in order to provide information on colony activity and development. The accelerometers provide amplitude and frequency information which is recorded every three minutes and analysed for night time only. Vibrational data were validated by comparison to visual inspection data, particularly the brood development. We show a strong correlation between vibrational amplitude data and the brood cycle in the vicinity of the sensor. We have further explored the minimum data that is required, when frequency information is also included, to accurately predict the current point in the brood cycle. Such a technique should enable beekeepers to reduce the frequency with which visual inspections are required, reducing the stress this places on the colony and saving the beekeeper time.

  7. Ambient vibration monitoring of slender structures by microwave interferometer remote sensing

    Science.gov (United States)

    Gikas, Vassilis

    2012-11-01

    This paper examines the potential of microwave radar interferometry for monitoring the dynamic behaviour of large civil engineering works. It provides an overview of the method, its principles of operation with particular emphasis given on the IBIS-S system. Two areas of application are considered and the results of the analyses are presented and discussed. The first experimental study involves the monitoring of the dynamic response of a tall power plant chimney due to wind load. The second example examines the dynamic behaviour of a long cable-stayed bridge. In this case, the focus is placed on the effects that individual traffic events impose on the vibration response of the main span of the bridge deck and the bridge pylons. Analysis of the results provides detailed displacement time-histories and the dominant frequencies observed at the top of the chimney and along the bridge deck and the top of the towers. Also, cross-comparisons and discussions with the results obtained at the same structures using different sensor configurations are provided.

  8. Non-contact measurement of facial surface vibration patterns during singing by scanning laser Doppler vibrometer.

    Science.gov (United States)

    Kitamura, Tatsuya; Ohtani, Keisuke

    2015-01-01

    This paper presents a method of measuring the vibration patterns on facial surfaces by using a scanning laser Doppler vibrometer (LDV). The surfaces of the face, neck, and body vibrate during phonation and, according to Titze (2001), these vibrations occur when aerodynamic energy is efficiently converted into acoustic energy at the glottis. A vocalist's vibration velocity patterns may therefore indicate his or her phonatory status or singing skills. LDVs enable laser-based non-contact measurement of the vibration velocity and displacement of a certain point on a vibrating object, and scanning LDVs permit multipoint measurements. The benefits of scanning LDVs originate from the facts that they do not affect the vibrations of measured objects and that they can rapidly measure the vibration patterns across planes. A case study is presented herein to demonstrate the method of measuring vibration velocity patterns with a scanning LDV. The objective of the experiment was to measure the vibration velocity differences between the modal and falsetto registers while three professional soprano singers sang sustained vowels at four pitch frequencies. The results suggest that there is a possibility that pitch frequency are correlated with vibration velocity. However, further investigations are necessary to clarify the relationships between vibration velocity patterns and phonation status and singing skills.

  9. Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

    OpenAIRE

    Wenbin, Gu; Jianghai, Chen; Zhenxiong, Wang; Zhihua, Wang; Jianqing, Liu; Ming, Lu

    2015-01-01

    Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater ...

  10. Vibration intensity. Evaluation of a remote measuring system

    Science.gov (United States)

    Carniel, Xavier

    1989-03-01

    Two differential laser vibrometers are compared to more classic vibration measuring instruments. A prototype differential laser vibrometer produced by the Centre Technique des Industries Mechaniques (CETIM) and the Photonetics company is tested. A system made up of two Polytec vibrometers is also tested. The Polytec vibrometer is the most accurate. It is a compact tool and uses fiber optic technology which allows positioning of the receptor heads at two neighboring points at the surface of the liquid studied. This type of differential laser vibrometer is shown to give better results than any inductor capacitor or ultrasound system.

  11. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    Science.gov (United States)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  12. Angular vibration measurement using grating and laser interferometer

    Science.gov (United States)

    Zhang, Li; Peng, Jun

    2006-06-01

    Primary angular acceleration calibration standard is developed by CIMM to generate standard rotational angle, angular velocity and angular acceleration, which are traceable to the International System of Units (SI). It can be used to calibrate angular transducers, i.e. angular accelerometer, angular velocity transducer, and rotational angle transducer to obtain amplitude sensitivity and phase shift by sinusoidal vibration. The measurement systems based on grating and laser interferometers are introduced in this paper. The measurement system based on PXI bus instrument is used to control the angular exciter, measure the output signal of the laser interferometers and the transducer to be calibrated synchronously. The methods for calculating the amplitude and phase of sinusoidal angular movement are investigated and high performance has been achieved. It shows the standard can be used in angular movement calibration in the frequency range from 0.1Hz to 200Hz.

  13. Measurement of vibrationally excited N2(v) in an atmospheric-pressure air pulsed corona discharge using coherent anti-Stokes Raman scattering

    Science.gov (United States)

    Teramoto, Yoshiyuki; Ono, Ryo

    2014-08-01

    Vibrationally excited N2(v = 1, 2) in an atmospheric-pressure air pulsed corona discharge was measured using coherent anti-Stokes Raman scattering (CARS). In a dry air discharge, the vibrational temperature determined from the ratio N2(v = 2)/N2(v = 0), Tv2, was approximately 500 K higher than that determined from N2(v = 1)/N2(v = 0), Tv1, immediately after the discharge pulse. Both vibrational temperatures reached equilibrium within 100 μs after the discharge pulse by the vibration-to-vibration (V-V) process of N2-N2. The translational temperature was also measured using CARS. The rise in the translational temperature due to vibration-to-translation (V-T) energy transfer was not observed for a postdischarge time of 5 μs-1 ms in the dry-air discharge. However, when the air was humidified, a significant V-T energy transfer was observed. It was due to an extremely rapid V-T process of H2O-H2O following the V-V process of N2-H2O. Measurements showed that the humidification of the ambient air accelerated the decrease in the N2 vibrational temperature and increased the translational temperature. N2(v) was generated mostly in the secondary streamer, not in the primary one, according to estimation from the measured N2(v) density.

  14. Radial vibration measurements directly from rotors using laser vibrometry: The effects of surface roughness, instrument misalignments and pseudo-vibration

    Science.gov (United States)

    Rothberg, Steve J.; Halkon, Ben J.; Tirabassi, Mario; Pusey, Chris

    2012-11-01

    Laser Doppler vibrometry (LDV) offers an attractive solution when radial vibration measurement directly from a rotor surface is required. Research to date has demonstrated application on polished-circular rotors and rotors coated with retro-reflective tape. In the latter case, however, a significant cross-sensitivity to the orthogonal radial vibration component occurs and post-processing is required to resolve individual radial vibration components. Until now, the fundamentally different behaviour observed between these cases has stood as an inconsistency in the published literature, symptomatic of the need to understand the effect of surface roughness. This paper offers the first consistent mathematical description of the polished-circular and rough rotor behaviours, combined with an experimental investigation of the relationship between surface roughness and cross-sensitivity. Rotors with surface roughness up to 10 nm satisfy the polished-circular rotor definition if vibration displacement is below 100% beam diameter, for a 90 μm beam, and below 40% beam diameter, for a 520 μm beam. On rotors with roughness between 10 nm and 50 nm, the polished-circular rotor definition is satisfied for vibration displacements up to 25% beam diameter, for a 90 μm beam, and up to 10% beam diameter, for a 520 μm beam. As roughness increases, cross-sensitivity increases but only rotors coated in retro-reflective tape satisfied the rough rotor definition fully. Consequently, when polished-circular surfaces are not available, rotor surfaces must be treated with retro-reflective tape and measurements post-processed to resolve individual vibration components. Through simulations, the value of the resolution and correction algorithms that form the post-processor has been demonstrated quantitatively. Simulations incorporating representative instrument misalignments and measurement noise have enabled quantification of likely error levels in radial vibration measurements. On a polished

  15. Power spectral density function and spatial autocorrelation of the ambient vibration full-wavefield generated by a distribution of spatially correlated surface sources

    Science.gov (United States)

    Lunedei, Enrico; Albarello, Dario

    2016-03-01

    Synthetic dispersion curves are here computed in the frame of an ambient-vibration full-wavefield model, which relies on the description of both ambient-vibration ground displacement and its sources as stochastic fields defined on the Earth's surface, stationary in time and homogeneous in space. In this model, previously developed for computing synthetic Horizontal-to-Vertical Spectral Ratio curves, the power spectral density function and the spatial autocorrelation of the displacement are naturally described as functions of the power spectral density function of the generating forces and of the subsoil properties (via the relevant Green's function), by also accounting for spatial correlation of these forces. Dispersion curves are computed from the displacement power spectral density function and from the spatial autocorrelation according with the well-known f-k and SPAC techniques, respectively. Two examples illustrate the way this new ambient-vibration model works, showing its possible use in better understanding the role of the surface waves in forming the dispersion curves, as well as its capability to capture some remarkable experimental findings.

  16. Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

    Directory of Open Access Journals (Sweden)

    Gu Wenbin

    2015-01-01

    Full Text Available Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater drilling blasting was measured in a field experiment. It shows that the water bottom vibration monitor could collect vibration signals quite effectively in underwater environments. The followed signal analysis shows that the characteristics of water bottom vibration and land ground vibration induced by the same underwater drilling blasting are quite different due to the different geological environments. The amplitude and frequency band of water bottom vibration both exceed those of land ground vibration. Water bottom vibration is mainly in low-frequency band that induced by blasting impact directly acts on rock. Besides the low-frequency component, land vibration contains another higher frequency band component that induced by followed water hammer wave acts on bank slope.

  17. Application of Story-wise Shear Building Identification Method to Actual Ambient Vibration

    Directory of Open Access Journals (Sweden)

    Kohei eFujita

    2015-02-01

    Full Text Available A sophisticated and smart story stiffness System Identification (SI method for a shear building model is applied to a full-scale building frame subjected to micro-tremors. The advantageous and novel feature is that not only the modal parameters, such as natural frequencies and damping ratios, but also the physical model parameters, such as story stiffnesses and damping coefficients, can be identified using micro-tremors. While the building responses to earthquake ground motions are necessary in the previous SI method, it is shown in this paper that the micro-tremor measurements in a full-scale 5 story building frame can be used for identification within the same framework. The SI using micro-tremor measurements leads to the enhanced usability of the previously proposed story-wise shear building identification method. The degree of ARX models and cut-off frequencies of band-pass filter are determined to derive reliable results.

  18. A method to measure internal stray radiation of cryogenic infrared imaging systems under various ambient temperatures

    Science.gov (United States)

    Tian, Qijie; Chang, Songtao; Li, Zhou; He, Fengyun; Qiao, Yanfeng

    2017-03-01

    The suppression level of internal stray radiation is a key criterion for infrared imaging systems, especially for high-precision cryogenic infrared imaging systems. To achieve accurate measurement for internal stray radiation of cryogenic infrared imaging systems under various ambient temperatures, a measurement method, which is based on radiometric calibration, is presented in this paper. First of all, the calibration formula is deduced considering the integration time, and the effect of ambient temperature on internal stray radiation is further analyzed in detail. Then, an approach is proposed to measure the internal stray radiation of cryogenic infrared imaging systems under various ambient temperatures. By calibrating the system under two ambient temperatures, the quantitative relation between the internal stray radiation and the ambient temperature can be acquired, and then the internal stray radiation of the cryogenic infrared imaging system under various ambient temperatures can be calculated. Finally, several experiments are performed in a chamber with controllable inside temperatures to evaluate the effectiveness of the proposed method. Experimental results indicate that the proposed method can be used to measure internal stray radiation with high accuracy at various ambient temperatures and integration times. The proposed method has some advantages, such as simple implementation and the capability of high-precision measurement. The measurement results can be used to guide the stray radiation suppression and to test whether the internal stray radiation suppression performance meets the requirement or not.

  19. Wireless technologies for the monitoring of strategic civil infrastructures: an ambient vibration test of the Faith Bridge, Istanbul, Turkey

    Science.gov (United States)

    Picozzi, M.; Milkereit, C.; Zulfikar, C.; Ditommaso, R.; Erdik, M.; Safak, E.; Fleming, K.; Ozel, O.; Zschau, J.; Apaydin, N.

    2008-12-01

    The monitoring of strategic civil infrastructures to ensure their structural integrity is a task of major importance, especially in earthquake-prone areas. Classical approaches to such monitoring are based on visual inspections and the use of wired systems. While the former has the drawback that the structure is only superficially examined and discontinuously in time, wired systems are relatively expensive and time consuming to install. Today, however, wireless systems represent an advanced, easily installed and operated tool to be used for monitoring purposes, resulting in a wide and interesting range of possible applications. Within the framework of the earthquake early warning projects SAFER (Seismic eArly warning For EuRope) and EDIM (Earthquake Disaster Information systems for the Marmara Sea region, Turkey), new low-cost wireless sensors with the capability to automatically rearrange their communications scheme are being developed. The reduced sensitivity of these sensors, arising from the use of low-cost components, is compensated by the possibility of deploying high-density self-organizing networks performing real-time data acquisition and analysis. Thanks to the developed system's versatility, it has been possible to perform an experimental ambient vibration test with a network of 24 sensors on the Fatih Sultan Mehmet Bridge, Istanbul (Turkey), a gravity-anchored suspension bridge spanning the Bosphorus Strait with distance between its towers of 1090 m. Preliminary analysis of the data has demonstrated that the main modal properties of the bridge can be retrieved, and may therefore be regularly re-evaluated as part of a long-term monitoring program. Using a multi-hop communications technique, data could be exchanged among groups of sensors over distances of a few hundred meters. Thus, the test showed that, although more work is required to optimize the communication parameters, the performance of the network offers encouragement for us to follow this

  20. Statistically Filtering Data for Operational Modal Analysis under Ambient Vibration in Structural Health Monitoring Systems

    Directory of Open Access Journals (Sweden)

    Wang Liang

    2016-01-01

    Full Text Available Operational modal analysis (OMA is prevalent in large structure modal identification for that it asks for output measurements only. To guarantee identification accuracy, theoretically, OMA data need to be a random process of Gaussian white noise (GWN. Although numerous OMA applications are found in practice, few have particularly discussed the data distribution and to what extent it would blur the modal judgement. This paper presents a method to sieve segments mostly obeying the GWN distribution out of a recording. With a windowing technique, the data segments are evaluated by the modified Kurtosis value. The process has been demonstrated on the monitoring data of two case study structures: one is a laboratory truss bridge excited by artificial forces, the other is a real cable-stayed bridge subject to environmental loads. The results show that weak randomness data may result in false peaks that would possibly mislead the non-parametric modal identification, such as using the Frequency Domain Decomposition method. To overcome, cares on selecting the optimal segment shall be exercised. The proposed method is verified effective to find the most suitable data for modal identification of structural health monitoring systems.

  1. Train-induced field vibration measurements of ground and over-track buildings.

    Science.gov (United States)

    Zou, Chao; Wang, Yimin; Moore, James A; Sanayei, Masoud

    2017-01-01

    Transit-oriented development, such as metro depot and over-track building complexes, has expanded rapidly over the last 5years in China. Over-track building construction has the advantage of comprehensive utilization of land resources, ease of commuting to work, and provide funds for subway construction. But the high frequency of subway operations into and out of the depots can generate excessive vibrations that transmit into the over track buildings, radiate noise within the buildings, hamper the operation of vibration sensitive equipment, and adversely affect the living quality of the building occupants. Field measurements of vibration during subway operations were conducted at Shenzhen, China, a city of 10.62 million people in southern China. Considering the metro depot train testing line and throat area train lines were the main vibration sources, vibration data were captured in five measurement setups. The train-induced vibrations were obtained and compared with limitation of FTA criteria. The structure-radiated noise was calculated using measured vibration levels. The vertical vibration energy directly passed through the columns on both sides of track into the platform, amplifying vibration on the platform by up to 6dB greater than ground levels at testing line area. Vibration amplification around the natural frequency in the vertical direction of over-track building made the peak values of indoor floor vibration about 16dB greater than outdoor platform vibration. We recommend to carefully examining design of new over-track buildings within 40m on the platform over the throat area to avoid excessive vertical vibrations and noise. For both buildings, the measured vertical vibrations were less than the FTA limit. However, it is demonstrated that the traffic-induced high-frequency noise has the potential to annoy occupants on the upper floors.

  2. Vibration measurements of high-heat-load monochromators for DESY PETRA III extension

    Energy Technology Data Exchange (ETDEWEB)

    Kristiansen, Paw, E-mail: paw.kristiansen@fmb-oxford.com [FMB Oxford Ltd, Unit 1 Ferry Mills, Oxford OX2 0ES (United Kingdom); Horbach, Jan; Döhrmann, Ralph; Heuer, Joachim [DESY, Deutsches Elektronen-Synchrotron Hamburg, Notkestrasse 85, 22607 Hamburg (Germany)

    2015-05-09

    Vibration measurements of a cryocooled double-crystal monochromator are presented. The origins of the vibrations are identified. The minimum achieved vibration of the relative pitch between the two crystals is 48 nrad RMS and the minimum achieved absolute vibration of the second crystal is 82 nrad RMS. The requirement for vibrational stability of beamline optics continues to evolve rapidly to comply with the demands created by the improved brilliance of the third-generation low-emittance storage rings around the world. The challenge is to quantify the performance of the instrument before it is installed at the beamline. In this article, measurement techniques are presented that directly and accurately measure (i) the relative vibration between the two crystals of a double-crystal monochromator (DCM) and (ii) the absolute vibration of the second-crystal cage of a DCM. Excluding a synchrotron beam, the measurements are conducted under in situ conditions, connected to a liquid-nitrogen cryocooler. The investigated DCM utilizes a direct-drive (no gearing) goniometer for the Bragg rotation. The main causes of the DCM vibration are found to be the servoing of the direct-drive goniometer and the flexibility in the crystal cage motion stages. It is found that the investigated DCM can offer relative pitch vibration down to 48 nrad RMS (capacitive sensors, 0–5 kHz bandwidth) and absolute pitch vibration down to 82 nrad RMS (laser interferometer, 0–50 kHz bandwidth), with the Bragg axis brake engaged.

  3. Measuring Work Functions Of "Dirty" Surfaces With A Vibrating Capacitive Probe

    Science.gov (United States)

    Yost, William T.

    1995-01-01

    Apparatus measures work function of possibly contaminated surface of specimen of metal or other electrically conductive material. Measures work function of specimen indirectly, by vibrating capacitive measurement of contact potential. Work function of specimen affected by microstructure and by contamination.

  4. Vibration-displacement measurement employing phase tracking technique with an optical fiber Michelson interferometer

    Science.gov (United States)

    Ma, Sen; Li, Zhaoying; Xie, Fang

    2011-11-01

    A vibration-displacement measurement system by tracking the phase variation of an optical fiber Michelson interferometer with an electronic feedback loop is presented. The measurement system includes an electronic feedback loop which is used to track the phase variation induced by the measured vibration-displacement and provides a sense of direction of the displacement simultaneously. The measurement system is designed to be capable of measuring vibration-displacement with frequencies up to 200Hz and the measurement resolution can reach 13nm.

  5. Comparative analysis of internal friction and natural frequency measured by free decay and forced vibration.

    Science.gov (United States)

    Wang, Y Z; Ding, X D; Xiong, X M; Zhang, J X

    2007-10-01

    Relations between various values of the internal friction (tgdelta, Q(-1), Q(-1*), and Lambda/pi) measured by free decay and forced vibration are analyzed systemically based on a fundamental mechanical model in this paper. Additionally, relations between various natural frequencies, such as vibration frequency of free decay omega(FD), displacement-resonant frequency of forced vibration omega(d), and velocity-resonant frequency of forced vibration omega(0) are calculated. Moreover, measurement of natural frequencies of a copper specimen of 99.9% purity has been made to demonstrate the relation between the measured natural frequencies of the system by forced vibration and free decay. These results are of importance for not only more accurate measurement of the elastic modulus of materials but also the data conversion between different internal friction measurements.

  6. The current status of measurement standards for acoustics and vibration at Inmetro

    OpenAIRE

    Ripper, Gustavo Palmeira; Hoffmann, Walter Erico

    2002-01-01

    ABSTRACT: The Division of Acoustics and Vibration (DIAVI) of INMETRO establishes, validates and maintains the Brazilian national measurement standards used for the realization of the units of physical quantities related to the field of acoustics and vibration. The basic vibration quantity realized by DIAVI is translational acceleration, from which the other motion quantities, i.e., velocity and displacement can be derived. Acoustical physical quantities include sound pressure and sound power...

  7. Feasibility of coded vibration in a vibro-ultrasound system for tissue elasticity measurement.

    Science.gov (United States)

    Zhao, Jinxin; Wang, Yuanyuan; Yu, Jinhua; Li, Tianjie; Zheng, Yong-Ping

    2016-07-01

    The ability of various methods for elasticity measurement and imaging is hampered by the vibration amplitude on biological tissues. Based on the inference that coded excitation will improve the performance of the cross-correlation function of the tissue displacement waves, the idea of exerting encoded external vibration on tested samples for measuring its elasticity is proposed. It was implemented by integrating a programmable vibration generation function into a customized vibro-ultrasound system to generate Barker coded vibration for elasticity measurement. Experiments were conducted on silicone phantoms and porcine muscles. The results showed that coded excitation of the vibration enhanced the accuracy and robustness of the elasticity measurement especially in low signal-to-noise ratio scenarios. In the phantom study, the measured shear modulus values with coded vibration had an R(2 )= 0.993 linear correlation to that of referenced indentation, while for single-cycle pulse the R(2) decreased to 0.987. In porcine muscle study, the coded vibration also obtained a shear modulus value which is more accurate than the single-cycle pulse by 0.16 kPa and 0.33 kPa at two different depths. These results demonstrated the feasibility and potentiality of the coded vibration for enhancing the quality of elasticity measurement and imaging.

  8. Analysis of In-Flight Vibration Measurements from Helicopter Transmissions

    Science.gov (United States)

    Mosher, Marianne; Huff, Ed; Barszcz

    2004-01-01

    In-flight vibration measurements from the transmission of an OH-58C KIOWA are analyzed. In order to understand the effect of normal flight variation on signal shape, the first gear mesh components of the planetary gear system and bevel gear are studied in detail. Systematic patterns occur in the amplitude and phase of these signal components with implications for making time synchronous averages and interpreting gear metrics in flight. The phase of the signal component increases as the torque increases; limits on the torque range included in a time synchronous average may now be selected to correspond to phase change limits on the underlying signal. For some sensors and components, an increase in phase variation and/or abrupt change in the slope of the phase dependence on torque are observed in regions of very low amplitude of the signal component. A physical mechanism for this deviation is postulated. Time synchronous averages should not be constructed in torque regions with wide phase variation.

  9. Active low-frequency vertical vibration isolation system for precision measurements

    Science.gov (United States)

    Wu, Kang; Li, Gang; Hu, Hua; Wang, Lijun

    2017-01-01

    Low-frequency vertical vibration isolation systems play important roles in precision measurements to reduce seismic and environmental vibration noise. Several types of active vibration isolation systems have been developed. However, few researches focus on how to optimize the test mass install position in order to improve the vibration transmissibility. An active low-frequency vertical vibration isolation system based on an earlier instrument, the Super Spring, is designed and implemented. The system, which is simple and compact, consists of two stages: a parallelogram-shaped linkage to ensure vertical motion, and a simple spring-mass system. The theoretical analysis of the vibration isolation system is presented, including terms erroneously ignored before. By carefully choosing the mechanical parameters according to the above analysis and using feedback control, the resonance frequency of the system is reduced from 2.3 to 0.03 Hz, a reduction by a factor of more than 75. The vibration isolation system is installed as an inertial reference in an absolute gravimeter, where it improved the scatter of the absolute gravity values by a factor of 5. The experimental results verifies the improved performance of the isolation system, making it particularly suitable for precision experiments. The improved vertical vibration isolation system can be used as a prototype for designing high-performance active vertical isolation systems. An improved theoretical model of this active vibration isolation system with beam-pivot configuration is proposed, providing fundamental guidelines for vibration isolator design and assembling.

  10. Measurement of ambient NH{sub 3} over Bay of Bengal during WICARB Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S.K.; Mandal, T.K.; Saxena, M.; Singh, S. [CSIR-National Physical Laboratory, New Delhi (India); Singh, A.K.; Ghosh, S.K.; Raha, S. [Centre for Astroparticle Physics and Space Science, Darjeeling, West Bengal (India). Bose Inst.; Centre for Astroparticle Physics and Space Science, Kolkata, West Bengal (India). Bose Inst.; Saud, T. [CSIR-National Physical Laboratory, New Delhi (India); Guru Govind Singh Indraprastha Univ., New Delhi (India)

    2012-07-01

    Concentrations of ambient NH{sub 3}, NO, NO{sub 2} and SO{sub 2} were measured over Bay of Bengal (BoB) during 28 December 2008 to 25 January 2009 to study their diurnal variation and relationship of NH{sub 3} with other trace gases over BoB. The measurements were done under the winter phase of Integrated Campaign on Aerosols and Radiation Budget (WICARB). For the first time, ambient NH{sub 3} was monitored precisely over BoB based on chemiluminescence method, having estimation efficiency more precise than the chemical trap method. The average concentration of ambient NH{sub 3}, NO, NO{sub 2} and SO{sub 2} were recorded as 4.78{+-}1.68, 1.89{+-}1.26, 0.31{+-}0.14 and 0.80{+-}0.30 {mu}gm{sup -3}, respectively, over BoB. The prominent latitudinal and longitudinal variations of the trace gases were observed over BoB, whereas NH{sub 3} and NO showed the non-significant diurnal variation. Results reveal that the concentration of ambient NH{sub 3} negatively correlated with ambient NO{sub 2} (r{sup 2} =.0.56), SO{sub 2} (r{sup 2} =.0.58) and ambient temperature (r{sup 2} =.0.27) during the study. (orig.)

  11. Calculation of flight vibration levels of the AH-1G helicopter and correlation with existing flight vibration measurements

    Science.gov (United States)

    Sopher, R.; Twomey, W. J.

    1990-01-01

    NASA-Langley is sponsoring a rotorcraft structural dynamics program with the objective to establish in the U.S. a superior capability to utilize finite element analysis models for calculations to support industrial design of helicopter airframe structures. In the initial phase of the program, teams from the major U.S. manufacturers of helicopter airframes will apply extant finite element analysis methods to calculate loads and vibrations of helicopter airframes, and perform correlations between analysis and measurements. The aforementioned rotorcraft structural dynamics program was given the acronym DAMVIBS (Design Analysis Method for Vibrations). Sikorsky's RDYNE Rotorcraft Dynamics Analysis used for the correlation study, the specifics of the application of RDYNE to the AH-1G, and comparisons of the predictions of the method with flight data for loads and vibrations on the AH-1G are described. RDYNE was able to predict trends of variations of loads and vibrations with airspeed, but in some instances magnitudes differed from measured results by factors of two or three to one. Sensitivities were studied of predictions to rotor inflow modeling, effects of torsional modes, number of blade bending modes, fuselage structural damping, and hub modal content.

  12. Measurement of Mechatronic Property of Biological Gel with Micro-Vibrating Electrode at Ultrasonic Frequency

    Directory of Open Access Journals (Sweden)

    Shigehiro Hashimoto

    2008-10-01

    Full Text Available A measurement system has been designed with a micro-vibrating electrode at ultrasonic frequency to measure local impedance of biological gel in vitro. The designed system consists of two electrodes, where one of the electrodes vibrates with a piezoelectric actuator. The component of variation at impedance between two electrodes with vibration of one electrode is analyzed at the corresponding spectrum. The manufactured system was applied to measure impedance of a physiological saline solution, a potassium chloride solution, a dextran aqueous solution, and an egg. The experimental results show that the designed system is effective to measure local mechatronic property of biological gel.

  13. Measurement of ambient ammonia with diffusion tube samplers

    NARCIS (Netherlands)

    Thijsse, T.R.; Duyzer, J.H.; Verhagen, H.L.M.; Wyers, G.P.; Wayers, A.; Möls, J.J.

    1998-01-01

    Results of a study to evaluate the suitability of passive samplers for the measurement of monthly averaged ammonia concentrations are presented. Five different samplers were tested. Four were diffusion tube samplers which differed in length and in the way they were modified to minimize disturbing ef

  14. Taking laser Doppler vibrometry off the tripod: correction of measurements affected by instrument vibration

    Science.gov (United States)

    Halkon, Ben J.; Rothberg, Steve J.

    2017-04-01

    Laser Doppler vibrometers (LDVs) are now well-established as an effective non-contact alternative to traditional contacting transducers. Despite 30 years of successful applications, however, very little attention has been given to sensitivity to vibration of the instrument itself. In this paper, the sensitivity to instrument vibration is confirmed before development theoretically and experimentally of a practical scheme to enable correction of measurements for arbitrary instrument vibration. The scheme requires a pair of correction sensors with appropriate orientation and relative location, while using frequency domain processing to accommodate inter-channel time delay and signal integrations. Error reductions in excess of 30 dB are delivered in laboratory tests with simultaneous instrument and target vibration over a broad frequency range. Ultimately, application to measurement on a vehicle simulator experiencing high levels of vibration demonstrates the practical nature of the correction technique and its robustness in a challenging measurement environment.

  15. Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

    Science.gov (United States)

    Platt, Michael; Jagodnik, John

    2011-01-01

    A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

  16. Vibration-displacement measurements based on the phase tracking of an optical fiber Michelson interferometer

    Science.gov (United States)

    Xie, Fang; Chen, Zhimin; Ren, Junyu; Feng, Qibo

    2009-04-01

    A vibration-displacement measurement system based on tracking the phase variation of an optical fiber Michelson interferometer with electronic feedback loops is presented. The measurement system includes two sets of electronic feedback loops. One electronic feedback loop is used to compensate for the low frequency drifts in the phase of the interferometric signal that results from environmental disturbances, while the other one is used to track the phase variation induced by the measured vibration displacement, and thus realize the measurement of the vibration displacement and provide a sense of direction of the displacement simultaneously. The measurement system is designed to be capable of measuring vibration displacement with frequencies ranging from 1.5 to 200 Hz, with measurement resolution reaching 13 nm.

  17. Vibration measurement based on the optical cross-correlation technique with femtosecond pulsed laser

    Science.gov (United States)

    Han, Jibo; Wu, Tengfei; Zhao, Chunbo; Li, Shuyi

    2016-10-01

    Two vibration measurement methods with femtosecond pulsed laser based on the optical cross-correlation technique are presented independently in this paper. The balanced optical cross-correlation technique can reflect the time jitter between the reference pluses and measurement pluses by detecting second harmonic signals using type II phase-matched nonlinear crystal and balanced amplified photo-detectors. In the first method, with the purpose of attaining the vibration displacement, the time difference of the reference pulses relative to the measurement pluses can be measured using single femtosecond pulsed laser. In the second method, there are a couple of femtosecond pulsed lasers with high pulse repetition frequency. Vibration displacement associated with cavity length can be calculated by means of precisely measuring the pulse repetition frequency. The results show that the range of measurement attains ±150μm for a 500fs pulse. These methods will be suited for vibration displacement measurement, including laboratory use, field testing and industrial application.

  18. Estimation of Eastern Denmark’s Electromechanical Modes from Ambient Phasor Measurement Data

    DEFF Research Database (Denmark)

    Vanfretti, Luigi; Garcia-Valle, Rodrigo; Uhlen, Kjetil;

    2010-01-01

    on the Danish power grid and its interconnections, and describe the features of an experimental phasor measurement unit designed by DTU which is used to provide the measurements used in this investigation. Parametric and non-parametric block processing techniques are applied to 48 hours of ambient data recorded...

  19. Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria

    Science.gov (United States)

    Titze, Ingo R.; Hunter, Eric J.

    2015-01-01

    Purpose: School-teachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method: Vibration dosimetry is reformulated with the inclusion of collision stress.…

  20. Phase error analysis and compensation considering ambient light for phase measuring profilometry

    Science.gov (United States)

    Zhou, Ping; Liu, Xinran; He, Yi; Zhu, Tongjing

    2014-04-01

    The accuracy of phase measuring profilometry (PMP) system based on phase-shifting method is susceptible to gamma non-linearity of the projector-camera pair and uncertain ambient light inevitably. Although many researches on gamma model and phase error compensation methods have been implemented, the effect of ambient light is not explicit all along. In this paper, we perform theoretical analysis and experiments of phase error compensation taking account of both gamma non-linearity and uncertain ambient light. First of all, a mathematical phase error model is proposed to illustrate the reason of phase error generation in detail. We propose that the phase error is related not only to the gamma non-linearity of the projector-camera pair, but also to the ratio of intensity modulation to average intensity in the fringe patterns captured by the camera which is affected by the ambient light. Subsequently, an accurate phase error compensation algorithm is proposed based on the mathematical model, where the relationship between phase error and ambient light is illustrated. Experimental results with four-step phase-shifting PMP system show that the proposed algorithm can alleviate the phase error effectively even though the ambient light is considered.

  1. Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Jaars, K.; Beukes, J. P.; van Zyl, P. G.; Venter, A. D.; Josipovic, M.; Pienaar, J. J.; Vakkari, Ville; Aaltonen, H.; Laakso, H.; Kulmala, M.; Tiitta, P.; Guenther, Alex B.; Hellen, H.; Laakso, L.; Hakola, H.

    2014-07-11

    Aromatic hydrocarbons are associated with direct adverse human health effects and can have negative impacts on ecosystems due to their toxicity, as well as indirect negative effects through the formation of tropospheric ozone and secondary organic aerosol that affect human health, crop production and regional climate. Measurements were conducted at the Welgegund measurement station (South Africa) that is considered to be a regionally representative background site. However, the site is occasionally impacted by plumes from major anthropogenic source regions in the interior of South Africa, which include the western Bushveld Igneous Complex (e.g. platinum, base metal and ferrochrome smelters), the eastern Bushveld Igneous Complex (platinum and ferrochrome smelters), the Johannesburg-Pretoria metropolitan conurbation (>10 million people), the Vaal Triangle (e.g. petrochemical and industries), the Mpumalanga Highveld (e.g. coal-fired power plants and petrochemical industry) and also a region of anti-cyclonic recirculation of air mass over the interior of South Africa. The aromatic hydrocarbon measurements were conducted with an automated sampler on Tenax-TA and Carbopack-B adsorbent tubes with heated inlet for one year. Samples were collected twice a week for two hours during daytime and two hours 1 during night-time. A thermal desorption unit, connected to a gas chromatograph and a mass 2 selective detector was used for sample preparation and analysis. Results indicated that the 3 monthly median total aromatic hydrocarbon concentrations ranged between 0.01 to 3.1 ppb. 4 Benzene levels did not exceed local air quality standards. Toluene was the most abundant 5 species, with an annual median concentration of 0.63 ppb. No statistically significant 6 differences in the concentrations measured during daytime and night-time were found and no distinct seasonal patterns were observed. Air mass back trajectory analysis proved that the lack of seasonal cycles could be

  2. Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

    Directory of Open Access Journals (Sweden)

    K. Jaars

    2014-02-01

    Full Text Available Aromatic hydrocarbons are associated with direct adverse human health effects and can have negative impacts on ecosystems due to their toxicity, as well as indirect negative effects through the formation of tropospheric ozone and secondary organic aerosol that affect human health, crop production and regional climate. Measurements were conducted at the Welgegund measurement station (South Africa that is considered to be a regionally representative background site. However, the site is occasionally impacted by plumes from major anthropogenic source regions in the interior of South Africa, which include the western Bushveld Igneous Complex (e.g. platinum, base metal and ferrochrome smelters, the eastern Bushveld Igneous Complex (platinum and ferrochrome smelters, the Johannesburg–Pretoria metropolitan conurbation (>10 million people, the Vaal Triangle (e.g. petrochemical and pyrometallurgical industries, the Mpumalanga Highveld (e.g. coal-fired power plants and petrochemical industry and also a region of anti-cyclonic recirculation of air mass over the interior of South Africa. The aromatic hydrocarbon measurements were conducted with an automated sampler on Tenax-TA and Carbopack-B adsorbent tubes with heated inlet for one year. Samples were collected twice a week for two hours during daytime and two hours during night-time. A thermal desorption unit, connected to a gas chromatograph and a mass selective detector was used for sample preparation and analysis. Results indicated that the monthly median total aromatic hydrocarbon concentrations ranged between 0.01 to 3.1 ppb. Benzene levels did not exceed local air quality standards. Toluene was the most abundant species, with an annual median concentration of 0.63 ppb. No statistically significant differences in the concentrations measured during daytime and night-time were found and no distinct seasonal patterns were observed. Air mass back trajectory analysis proved that the lack of seasonal

  3. Health monitoring of aeronautical structures based on vibrations measurements

    Science.gov (United States)

    Bovio, Igor; Lecce, Leonardo

    2006-03-01

    Purpose of the paper is to present an innovative application inside the Non Destructive Testing field based on vibrations measurements, developed by the authors during the last three years, and already tested for analysing damage of many structural elements. The proposed new method is based on the acquisition and comparison of Frequency Response Functions (FRFs) of the monitored structure before and after an occurred damage. Structural damage modify the dynamical behaviour of the structure such as mass, stiffened and damping, and consequently the FRFs of the damaged structure in comparison with the FRFs of the sound structure, making possible to identify, to localize and quantify a structural damage. The activities, presented in the paper, mostly focused on a new FRFs processing technique based on the determining of a representative "Damage Index" for identifying and analysing damage both on real scale aeronautical structural components, like large-scale fuselage reinforced panels, and on aeronautical composite panels. Besides it has been carried out a dedicated neural network algorithm aiming at obtaining a "recognition-based learning"; this kind of learning methodology permits to train the neural network in order to let it recognises only "positive" examples discarding as a consequence the "negative" ones. Within the structural NDT a "positive" example means "healthy" state of the analysed structural component and, obviously, a "negative" one means a "damaged" or perturbed state. From an architectural point of view piezoceramic patches have been tested as actuators and sensors. Besides it has been used a laser-scanning vibrometer system to validate the behaviour of the piezoceramic patches.

  4. Measurement of Micro Vibration of Car by Piezoelectric Ceramics

    Science.gov (United States)

    Kurihara, Yosuke; Masuyama, Kosuke; Nakamura, Testuo; Bamba, Takeshi; Watanabe, Kajiro

    Recently, there are various accidents and crimes related to the car. In some cases, the accidents and the crimes can be prevented if it is possible to detect a human who is in the car. For example, we can prevent a baby who is left in a car under the hot weather from dehydration or death occurred by heat inside disease. In another case, it is estimated that the United States currently has as many as 12 million illegal immigrants. In order to prevent further influx of illegal immigrants, the police are physically searching incoming vehicles at national boundaries aiming at finding those who are hiding inside. However, the physical inspections require much manpower cost and time. An inspection method to see inside the vehicles through X-ray images has also been used for this end. But the cost and the installation places are the problems of the large-scale X-ray system. Proposed in this paper is a piezoelectric ceramic system to handily measure the micro vibrations of motor vehicles. And applying the algorithm of Support Vector Machine (SVM), the existence of human body inside vehicles can be detected. The experiment was carried out using four types of vehicles: a mini car; an auto mobile; a van; and a truck weighing 1.5 tons. As the results, the correct determination ratio was 91.2% for the experiment with the piezoelectric ceramic under the front wheels and 97.0% under the rear wheels, when the vehicle used for the examination had also been used together with other three types of vehicles to obtain SVM training data. When the vehicle used for the examination had not been used together with the other three to obtain SVM training data, on the other hand, the correct determination ratio was 93.7% for the experiment with the piezoelectric ceramic under the front wheels and 95.7% under the rear wheels.

  5. Estimating Personal Exposures from Ambient Air Pollution Measures - Using Meta-Analysis to Assess Measurement Error

    Science.gov (United States)

    Although ambient concentrations of particulate matter ≤ 10μm (PM10) are often used as proxies for total personal exposure, correlation (r) between ambient and personal PM10 concentrations varies. Factors underlying this variation and its effect on he...

  6. Measurement of gas flow velocity: anemometer with a vibrating hot wire.

    Science.gov (United States)

    Kiełbasa, Jan

    2010-01-01

    I propose a new method to measure velocity of a gas flow, which utilizes the time derivative of the voltage observed on a vibrating hot-wire sensor. The wire vibrates with an amplitude a and a frequency f, and is kept perpendicular to the gas flow direction in the plane containing the flow velocity vector v(g). When the parameters of vibrations are tuned, the number of zeros per vibration period of the hot-wire voltage function changes. I demonstrate that at the point of change, the unknown gas velocity is directly expressed by the parameters of vibrations v(g)=2pifa. Therefore, the velocity can be measured without any prior calibration of the hot-wire speed-voltage curve and the method can be used for gases of slowly changing temperature or composition.

  7. Field measurements and analyses of environmental vibrations induced by high-speed Maglev.

    Science.gov (United States)

    Li, Guo-Qiang; Wang, Zhi-Lu; Chen, Suwen; Xu, You-Lin

    2016-10-15

    Maglev, offers competitive journey-times compared to the railway and subway systems in markets for which distance between the stations is 100-1600km owing to its high acceleration and speed; however, such systems may have excessive vibration. Field measurements of Maglev train-induced vibrations were therefore performed on the world's first commercial Maglev line in Shanghai, China. Seven test sections along the line were selected according to the operating conditions, covering speeds from 150 to 430km/h. Acceleration responses of bridge pier and nearby ground were measured in three directions and analyzed in both the time and frequency domain. The effects of Maglev train speed on vibrations of the bridge pier and ground were studied in terms of their peak accelerations. Attenuation of ground vibration was investigated up to 30m from the track centerline. Effects of guideway configuration were also analyzed based on the measurements through two different test sections with same train speed of 300km/h. The results showed that peak accelerations exhibited a strong correlation with both train speed and distance off the track. Guideway configuration had a significant effect on transverse vibration, but a weak impact on vertical and longitudinal vibrations of both bridge pier and ground. Statistics indicated that, contrary to the commonly accepted theory and experience, vertical vibration is not always dominant: transverse and longitudinal vibrations should also be considered, particularly near turns in the track. Moreover, measurements of ground vibration induced by traditional high-speed railway train were carried out with the same testing devices in Bengbu in the Anhui Province. Results showed that the Maglev train generates significantly different vibration signatures as compared to the traditional high-speed train. The results obtained from this paper can provide good insights on the impact of Maglev system on the urban environment and the quality of human life

  8. Quantitative measurements of vibration amplitude using a contact-mode freestanding triboelectric nanogenerator.

    Science.gov (United States)

    Wang, Sihong; Niu, Simiao; Yang, Jin; Lin, Long; Wang, Zhong Lin

    2014-12-23

    A vibration sensor is usually designed to measure the vibration frequency but disregard the vibration amplitude, which is rather challenging to be quantified due to the requirement of linear response. Here, we show the application of triboelectric nanogenerator (TENG) as a self-powered tool for quantitative measurement of vibration amplitude based on an operation mode, the contact-mode freestanding triboelectric nanogenerator (CF-TENG). In this mode, the triboelectrically charged resonator can be agitated to vibrate between two stacked stationary electrodes. Under the working principle with a constant capacitance between two electrodes, the amplitudes of the electric signals are proportional to the vibration amplitude of the resonator (provided that the resonator plate is charged to saturation), which has been illuminated both theoretically and experimentally. Together with its capability in monitoring the vibration frequency, the CF-TENG appears as the triboelectrification-based active sensor that can give full quantitative information about a vibration. In addition, the CF-TENG is also demonstrated as a power source for electronic devices.

  9. Simultaneous Static Strain, Temperature and Vibration Measurement Using an Integrated FBG/EFPI Sensor

    Institute of Scientific and Technical Information of China (English)

    曾祥楷; 饶云江

    2001-01-01

    A novel technique for simultaneous measurement of static strain, temperature and vibration in health monitoring of structures is demonstrated using an integrated in-fibre Bragg grating (FBG)/extrinsic Fabry-Pérot interferometer (EFPI) sensor. The EFPI sensor provides static strain and vibration information simultaneously by using the channel-spectrum method and the low-coherence interferometric technique, respectively. The FBG sensor is used for temperature measurement. The experimental results show that a static-strain accuracy of l20με, a temperature accuracy of +l℃ and a vibration resolution of 1 nm have been achieved with a good repeatability.

  10. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    Science.gov (United States)

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  11. Transverse Beam Halo Measurements at High Intensity Neutrino Source (HINS) using Vibrating Wire Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, M.; Hanna, B.; Scarpine, V.; Shiltsev, V.; Steimel, J.; Artinian, S.; Arutunian, S.

    2015-02-26

    The measurement and control of beam halos will be critical for the applications of future high-intensity hadron linacs. In particular, beam profile monitors require a very high dynamic range when used for the transverse beam halo measurements. In this study, the Vibrating Wire Monitor (VWM) with aperture 60 mm was installed at the High Intensity Neutrino Source (HINS) front-end to measure the transverse beam halo. A vibrating wire is excited at its resonance frequency with the help of a magnetic feedback loop, and the vibrating and sensitive wires are connected through a balanced arm. The sensitive wire is moved into the beam halo region by a stepper motor controlled translational stage. We study the feasibility of the vibrating wire for the transverse beam halo measurements in the low-energy front-end of the proton linac.

  12. Composite-Light-Source Interferometer for Real-Time Micro-Vibration Measurements

    Institute of Scientific and Technical Information of China (English)

    Dailin Li; Xiangzhao Wang

    2003-01-01

    A novel interferometer using a composite light source for real time measurements of micro-vibrations is proposed.The experimental results make it clear that it is insensitive to external disturbances and intensity fluctuations of the source light.

  13. Composite-Light-Source Interferometer for Real-Time Micro-Vibration Measurements

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel interferometer using a composite light source for real time measurements of micro-vibrations is proposed. The experimental results make it clear that it is insensitive to external disturbances and intensity fluctuations of the source light.

  14. Measurement of the Resonant Characteristics of a Single Bubble Vibration by Using a Laser Doppler Vibrometer

    Science.gov (United States)

    Yoshikawa, Taisuke; Kotera, Hironori; Yoshida, Kenji; Koyama, Daisuke; Nakamura, Kentaro; Watanabe, Yoshiaki

    2011-07-01

    We constructed the experimental system with a laser Doppler vibrometer (LDV) for measuring the vibration of a single microbubble. It was demonstrated that the system enabled the capture of the vibration with an amplitude of nanometer order. We attempted to experimentally measure the resonant characteristics of a bubble attached to a wall by using the system. As a result, we succeeded in measuring the characteristics and evaluating the Q factor and the resonant radius at a driving frequency of 27.8 kHz, although these values are different from those predicted on the basis of the theory for a single free bubble. The LDV measurement system is expected to an effective tool for evaluating bubble vibrations with very small displacement amplitudes, such as the vibration of a microcapsule.

  15. Blade Vibration Measurement System for Characterization of Closely Spaced Modes and Mistuning Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There are several ongoing challenges in non-contacting blade vibration and stress measurement systems that can address closely spaced modes and blade-to-blade...

  16. On measuring surface wave phase velocity from station–station cross-correlation of ambient signal

    DEFF Research Database (Denmark)

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

    2012-01-01

    We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one met...

  17. Sub-bottom profiling with ambient noise measured on a drifting vertical array

    NARCIS (Netherlands)

    Harrison, C.H.; Schippers, P.; Snellen, M.; Weterings, A.

    2005-01-01

    The angle and frequency dependent reflective properties of the seabed can be determined from beam-steered ambient noise measurements on a vertical array of hydrophones. From the up-to-down ratio the beam-smeared modulus square of the plane wave reflection coefficient is obtained. Geo-acoustic parame

  18. Nuclear magnetic resonance measurements of velocity distributions in an ultrasonically vibrated granular bed.

    Science.gov (United States)

    Huntley, J M; Tarvaz, T; Mantle, M D; Sederman, A J; Gladden, L F; Sheikh, N A; Wildman, R D

    2014-05-13

    We report the results of nuclear magnetic resonance imaging experiments on granular beds of mustard grains fluidized by vertical vibration at ultrasonic frequencies. The variation of both granular temperature and packing fraction with height was measured within the three-dimensional cell for a range of vibration frequencies, amplitudes and numbers of grains. Small increases in vibration frequency were found--contrary to the predictions of classical 'hard-sphere' expressions for the energy flux through a vibrating boundary--to result in dramatic reductions in granular temperature. Numerical simulations of the grain-wall interactions, using experimentally determined Hertzian contact stiffness coefficients, showed that energy flux drops significantly as the vibration period approaches the grain-wall contact time. The experiments thus demonstrate the need for new models for 'soft-sphere' boundary conditions at ultrasonic frequencies.

  19. Measuring noise and vibration in the cockpit of the Mi-8 helicopter

    OpenAIRE

    STOJANOVIC IVICA S.

    2016-01-01

    Noise and vibration are among the main negative elements of the working environment. The aim of this study was to determine the measurement of the size of their effect on helicopter pilots and crew members. The results were compared with the warning and limit values determined by the existing Directives of the European Commission in the field of noise and vibration. The comparison of the results has led to the conclusion that the measured values are unacceptable in terms of safety and health ...

  20. Impact of ambient temperature on spring-based relative gravimeter measurements

    Science.gov (United States)

    Fores, B.; Champollion, C.; Moigne, N. Le; Chery, J.

    2016-10-01

    In this paper, we investigate the impact of ambient temperature changes on the gravity reading of spring-based relative gravimeters. Controlled heating experiments using two Scintrex CG5 gravimeters allowed us to determine a linear correlation (R 2> 0.9) between ambient temperature and gravity variations. The relation is stable and constant for the two CG5 we used: -5 nm/s2/° C. A linear relation is also seen between gravity and residual sensor temperature variations (R 2> 0.75), but contrary to ambient temperature, this relation is neither constant over time nor similar between the two instruments. The linear correction of ambient temperature on the controlled heating time series reduced the standard deviation at least by a factor of 2, to less than 10 nm/s2 . The laboratory results allowed for reprocessing the data gathered on a field survey that originally aimed to characterize local hydrological heterogeneities on a karstic area. The correction of two years of monthly CG5 measurements from ambient temperature variations halved the standard deviation (from 62 to 32 nm/s2 ) and led us to a better hydrological interpretation. Although the origin of this effect is uncertain, we suggest that an imperfect control of the sensor temperature may be involved, as well as a change of the properties of an electronic component.

  1. In vitro measurement of ambient pressure changes using a realistic clinical setup

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2008-01-01

    cosine tapered pulse with a center frequency of 4 MHz and an acoustic pressure of 485 kPa was used for excitation. 64 elements were used in receive and the RF data was filtered and beamformed before further processing. To compensate for variations in bubble response and to make the estimates more robust...... have indicated that the amplitude of the subharmonic response from contrast agents is sensitive to the ambient pressure. This paper presents results from a new experimental setup for measuring the subharmonic response of a contrast agent when subjected to ambient over pressure. The setup is very...... flexible offering completely arbitrary excitation and data acquisition, fast and accurate ambient pressure control, and precise timing. More importantly, it resembles a realistic clinical setup using a single array transducer for transmit and receive. The standard signal processing steps usually seen...

  2. Measuring and analysing vibration motors in insoles via accelerometers

    OpenAIRE

    2014-01-01

    Purpose: Falling is a major public health concern among elderly people, and they often cause serious injuries1,2. They most frequently occur during walking and are associated with the chronic deterioration in the neuromuscular and sensory systems, as well as with ankle muscle weakness and lower endurance of these muscles to fatigue1,3. Vibrating insoles, providing a subsensory mechanical noise signal to the plantar side of the feet, may improve balance in healthy young and older people and in...

  3. A distributed optical fiber sensing system for synchronous vibration and loss measurement

    Science.gov (United States)

    Zhang, Xu-ping; Qiao, Wei-yan; Sun, Zhen-hong; Shan, Yuan-yuan; Zeng, Jie; Zhang, Yi-xin

    2016-09-01

    We propose a fully distributed fusion system combining phase-sensitive optical time-domain reflectometry (Φ-OTDR) and OTDR for synchronous vibration and loss measurement by setting an ingenious frequency sweep rate ( FSR) of the optical source. The relationships between FSR, probe pulse width and repeat period are given to balance the amplitude fluctuation of OTDR traces, the dead zone probability and the measurable frequency range of vibration events. In the experiment, we achieve synchronous vibration and loss measurement with FSR of 40 MHz/s, the proble pulse width of 100 ns and repeat rate of 0.4 ms. The fluctuation of OTDR trace is less than 0.45 dB when the signal-to-noise ratio ( SNR) is over 12 dB for a captured vibration event located at 9.1 km. The proposed method can be used for not only detection but also early warning of damage events in optical communication networks.

  4. Vibration-Induced Conductivity Fluctuation Measurement for Soil Bulk Density Analysis

    CERN Document Server

    Kishne, Andrea Sz; Chang, Hung-Chih; Kish, Laszlo B

    2007-01-01

    Soil bulk density affects water storage, water and nutrient movement, and plant root activity in the soil profile. Its measurement is difficult in field conditions. Vibration-induced conductivity fluctuation was investigated to quantify soil bulk density with possible field applications in the future. The AC electrical conductivity of soil was measured using a pair of blade-like electrodes while exposing the soil to periodic vibration. The blades were positioned longitudinally and transversally to the direction of the induced vibration to enable the calculation of a normalized index. The normalized index was expected to provide data independent from the vibration strength and to reduce the effect of soil salinity and water content. The experiment was conducted on natural and salinized fine sand at two moisture conditions and four bulk densities. The blade-shaped electrodes improved electrode-soil contact compared to cylindrical electrodes, and thereby, reduced measurement noise. Simulations on a simplified re...

  5. Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

    Science.gov (United States)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2016-06-01

    A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

  6. A New Approach for Reliability Life Prediction of Rail Vehicle Axle by Considering Vibration Measurement

    Directory of Open Access Journals (Sweden)

    Meral Bayraktar

    2014-01-01

    Full Text Available The effect of vibration on the axle has been considered. Vibration measurements at different speeds have been performed on the axle of a running rail vehicle to figure out displacement, acceleration, time, and frequency response. Based on the experimental works, equivalent stress has been used to find out life of the axles for 90% and 10% reliability. Calculated life values of the rail vehicle axle have been compared with the real life data and it is found that the life of a vehicle axle taking into account the vibration effects is in good agreement with the real life of the axle.

  7. Investigation of three-dimensional vibration measurement by a single scanning laser Doppler vibrometer

    Science.gov (United States)

    Chen, Da-Ming; Zhu, W. D.

    2017-01-01

    A scanning laser Doppler vibrometer (SLDV) has been widely used in non-contact vibration measurement. This paper presents a novel investigation of three-dimensional (3D) vibration measurement by a single SLDV sequentially placed at three different positions, where 3D vibration is defined as three vibration components along axes of a specified measurement coordinate system (MCS), which can give more precise knowledge of structural dynamic characteristics. A geometric model of the SLDV is proposed and a vibrometer coordinate system (VCS) based on the geometric model is defined and fixed on the SLDV. The pose of a SLDV with respect to a MCS is expressed in the form of a translation vector and a direction cosine matrix from the VCS to the MCS, which can be calculated by four or more target points with known coordinates in both the MCS and the VCS. An improved method based on the least squares method and singular value decomposition is proposed to obtain the pose of the SLDV. Compared with an inverse method, the proposed method can yield an orthogonal direction cosine matrix and be applicable to a two-dimensional structure. Effects of the number of target points on the accuracy and stability of the proposed method are investigated. With three direction cosine matrices of three different positions obtained by the proposed method, measured vibration velocities along laser line-of-sight directions can be transformed to vibration components along axes of the MCS. An experiment was conducted to measure 3D vibration of a target point on a beam under sinusoidal excitation by a single SLDV sequentially placed at three different positions. Vibration components along axes of the MCS obtained by the single SLDV were in good agreement with those from a commercial Polytec 3D scanning laser vibrometer PSV-500-3D.

  8. Extension of Measurable Region of Object Vibration Phasor in Phase-Modulated TV Holographic Interferometry: Experiment

    Science.gov (United States)

    Kojima, Kentaro; Miyazaki, Takeshi; Nojima, Ken; Yamamoto, Hirotaka; Sasaki, Yasuhito

    2004-03-01

    In this paper, we present an experiment based on the previously reported theory concerning the extension of the measurable region of object vibration phasor in phase-modulated TV holographic interferometry. This theory is based on the following facts: (1) the modulation of speckle interference image is proportional to the Bessel function, (2) its argument indicates the distance between the phasors of phase modulation and object vibration in the complex plane, and (3) the modulation increases as the Bessel function argument approaches zero. The phase modulation phasor is scanned, and at each pixel, one seeks the phase modulation phasor producing the maximum modulation. From the modulations produced by four phase modulation phasors adjacent to the sought phase modulation phasor, the object vibration phasor can be calculated. We analyzed the vibration of a phosphor-bronze rectangular plate with free sides, which were vibrated at the center by a piezoelectric transducer (PZT). Twenty-one phase modulation phasors were employed. The results of measurement were presented, and it was confirmed that the object vibration phasor can be measured in the wider region based on the theory concerning the extension of the measurable region.

  9. Laser interferometric vibration measurements of the middle ear in healthy humans

    Science.gov (United States)

    Jorge, J. Rodriguez; Hemmert, Werner; Burkhardt, Claus; Zenner, Hans-Peter; Gummer, Anthony W.

    1996-01-01

    The use of spontaneous and evoked otacoustic emissions is now a standard clinical tool for diagnosis of the function of the inner ear. However, it is not possible to extract this information over the entire, functionally relevant frequency range because of imperfect coupling of: (1) stapedial to ear-drum vibrations through the ossicular chain of the middle ear and (2) ear-drum vibrations to air in the external auditory meatus. The problem could be circumvented if it were possible to measure the vibration of the stapes and ear drum. The ear drum can be visualized non-invasively, whereas the stapes is only accessible intra-operatively. Therefore, we designed a laser-interferometric system to non-invasively measure the vibration of the human ear drum. Vibrations were measured with a laser Doppler velocimeter (Polytec OFV-302) coupled into the side arm of an operating microscope (Zeiss OPMI MDM). The wavelength was 633 nm and emitted power was less than 1 mW. Direct coupling through the optics of the operating microscope, instead of through glass fibers, enabled a larger signal-to- noise ratio (20 - 30 dB) due to collection of more reflected light. This coupling scheme avoids the problems associated with having to place a reflecting material on the ear drum. The developed vibration measurement system allows non-invasive, fast and reproducible characterization of the dynamics of the human ear drum and as such can be used for clinical diagnostics.

  10. Site responses based on ambient vibrations and earthquake data: a case study from the meizoseismal area of the 2001 Bhuj earthquake

    Science.gov (United States)

    Natarajan, Thulasiraman; Rajendran, Kusala

    2016-08-01

    The 2001 Mw 7.6 earthquake sourced in the Kachchh rift of northwest India led to extensive damage in the city of Bhuj, located ~70 km southwest of its epicenter. The building stock of this densely populated city was a mix of modern, single, and multistoried structures as well as traditional and non-engineered abodes, most of which were not designed to withstand severe shaking effects. Although there was extensive liquefaction and ground failure in the meizoseismal area, they were not observed in Bhuj, but the damage was severe here. In this study, we apply horizontal to vertical spectral ratio method to ambient vibrations (HVSR-AV) to obtain fundamental resonance frequency (f0) and H/V peak amplitude (A0) to examine if site response had any significant role in the observed damage. The patterns of H/V curves as well as spatial distributions of f0 (0.6-1.4 Hz) and A0 (1.5-4.4) suggest absence of any strong impedance contrast within the subsurface. Similar results obtained for ambient vibrations and earthquake signals suggest the efficacy of the HVSR-AV method as most useful for regions of low-level seismicity. The weathered sandstone that is generally exposed in the city represents the resonating layer whose thickness is approximately estimated as ~66-155 m, based on 1D assumption. The current set of available data precludes any quantitative modeling, but our preliminary inference is that site effects were not significant during the 2001 earthquake damage observed in Bhuj.

  11. The Shock and Vibration Bulletin. Part 2. Measurement Techniques and Data Analysis, Dynamic Measurements, Vibration and Acoustics

    Science.gov (United States)

    1980-09-01

    DAMPING M. M. Wallace and C. W. Bert, The University of Oklahoma, Norman, OK CONTRIBUTIONS TO THE DYNAMIC ANALYSIS OF MAGLEV VEHICLES ON ELEVATED GUIDEWAYS...state transmitted and/oT reflected sound pressure for a coated, submerged flat plate, subject to a train of normally incident harmonic waves...simply make the length of the train of waves as long as you please. It is in 3i07 Main, I, G , Vibrations and Waves in the low frequency problems

  12. Examining ambient noise using colocated measurements of rotational and translational motion

    Science.gov (United States)

    Hadziioannou, Celine; Gaebler, Peter; Schreiber, Ulrich; Wassermann, Joachim; Igel, Heiner

    2012-10-01

    In the past decade, a number of studies have reported the observation of rotational motion associated with seismic events. We report a first observation of rotational motion in the microseismic ambient noise band. A striking feature of rotational motion measurements is that the information about the seismic phase velocity and source back azimuth is contained in the amplitude ratio of a point measurement of rotation rate and transverse acceleration. We investigate the possibility of applying this method to ambient noise measured with a ring laser and a broadband seismometer at the Wettzell Geodetic Observatory in Germany. Using data in the secondary microseismic band, we recover local phase velocities as well as the back azimuth of the strongest noise source for two different time periods. In order to confirm these findings, we additionally compare the results with classical array processing techniques of the Gräfenberg array located nearby.

  13. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    CERN Document Server

    Karhu, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\

  14. Compound cavity theory of resonant phase modulation in laser self-mixing ultrasonic vibration measurement

    Science.gov (United States)

    Tao, Yufeng; Wang, Ming; Guo, Dongmei

    2016-07-01

    The theoretical basis of self-mixing interference (SMI) employing a resonant phase modulator is explored to prove its tempting advantages. The adopted method induces a pure phase carrier without increasing system complexity. A simple time-domain signal process is used to estimate modulation depth and precisely track vibrating trail, which promises the flexibility of measuring ultrasonic vibration regardless of the constraint of the Bessel functions. The broad bandwidth, low speckle noise, compact, safe, and easy operating SMI system obtains the best resolution of a poor reflection environment. Numerical simulation discusses the spectrum broadening and errors due to multiple reflections. Experimental results agree with theory coherently and are compared with laser Doppler vibration meter showing a dynamical error better than 20 nm in ultrasonic vibration measurement.

  15. Blind source separation of internal combustion engine piston slap from other measured vibration signals

    Science.gov (United States)

    Liu, Xianhua; Randall, R. B.

    2005-11-01

    Internal combustion engines have several vibration sources, such as combustion, fuel injection, piston slap and valve operation. For machine condition monitoring or design improvement purposes, it is necessary to separate the vibration signals caused by different sources and then analyse each of them individually. However, traditional frequency analysis techniques are not very useful due to overlap of the different sources over a wide frequency range. This paper attempts to separate the vibration sources, especially piston slap, by using blind source separation techniques with the intention of revealing the potential of the new technique for solving mechanical vibration problems. The BSS method and the Blind least mean square algorithm using Gray's variable norm as a measure of non-Gaussianity of the sources is briefly described and separation results for both simulated and measured data are presented and discussed.

  16. Vibration-displacement measurements with a highly stabilised optical fiber Michelson interferometer system

    Science.gov (United States)

    Xie, Fang; Ren, Junyu; Chen, Zhimin; Feng, Qibo

    2010-02-01

    A highly stabilised vibration-displacement measurement system, which employs fiber Bragg gratings (FBGs) to interleave two fiber Michelson interferometers that share the common-interferometric-optical path, is presented. The phase change in the interferometric signals of the two fiber Michelson interferometers have been tracked, respectively, with two electronic feedback loops. One of the fiber interferometers is used to stabilise the system by the use of an electronic feedback loop to compensate the environmental disturbances. The second fiber interferometer is used to perform the measurement task and employs another electronic feedback loop to track the phase change in the interferometric signal. The measurement system is able to measure vibration-displacement and provide the sense of direction of the displacement. The frequency range of the measured vibration-displacement is from 0.1 to 200 Hz and the measurement resolution is 10 nm.

  17. Vibration Sensitivity of a Wide-Temperature Electronically Scanned Pressure Measurement (ESP) Module

    Science.gov (United States)

    Zuckerwar, Allan J.; Garza, Frederico R.

    2001-01-01

    A vibration sensitivity test was conducted on a Wide-Temperature ESP module. The test object was Module "M4," a 16-channel, 4 psi unit scheduled for installation in the Arc Sector of NTF. The module was installed on a vibration exciter and loaded to positive then negative full-scale pressures (+/-2.5 psid). Test variables were the following: Vibration frequencies: 20, 55, 75 Hz. Vibration level: 1 g. Vibration axes: X, Y, Z. The pressure response was measured on each channel, first without and then with the vibration turned on, and the difference analyzed by means of the statistical t-test. The results show that the vibration sensitivity does not exceed 0.01% Full Scale Output per g (with the exception of one channel on one axis) to a 95 percent confidence level. This specification, limited by the resolution of the pressure source, lies well below the total uncertainty specification of 0.1 percent Full Scale Output.

  18. Time-frequency characteristics of blasting vibration signals measured in milliseconds

    Institute of Scientific and Technical Information of China (English)

    Zhao Mingsheng; Zhang Jianhua; Yi Changping

    2011-01-01

    In order to study the time-frequency characteristics of blasting vibration signals,measured in milliseconds,we carried out site blasting vibration tests at an open pit of the Jinduicheng Mine.Based on recorded field data and applying a combination of RSPWVD and wavelet,.we analyzed the time-frequency characteristics of recorded field data.summarized the time-frequency characteristics of blasting vibration signals in different frequency bands and present detailed information of blasting vibration signals in milliseconds of high time-frequency resolutions.Because RSPWVD can be seen as of definite physical significance to signal energy distribution in time and frequency domains,we studied the energy distribution of blasting vibration signals for various milliseconds intervals from a perspective of energy distribution.The results indicate that the effect of milliseconds intervals on time-frequency characteristics of blasting vibration signals is significant:the length of delay time directly affects the energy distribution of blasting vibration signals as well as the duration of energy in frequency bands.

  19. Measurement Of Flow Induced Vibration Of Reactor Component

    Science.gov (United States)

    Dharmaraju, N.; Meher, K. K.; Rao, A. Rama

    The effect of flow-induced vibration on class I components in the reactor is a very important design factor for its qualifications worthy of loading inside the core. In this regard, a clear definition of the flow excitation and the dynamic characteristics of the component are the two primary inputs required to make an estimation of vibration severity. Though there are general guidelines available, more often it has been seen that they only help in arriving at a first approximation. There are many instances wherein a component has failed to perform as per design in spite of sufficient margin provided in the calculations. There are also instances wherein some components have failed even after successful testing under close to simulated flow condition. The paper deals with qualification procedure followed to flow test an in core component in an out of pile facility. The adopted procedure is considered to be a best approach especially in this field where in there are many gray areas.

  20. Characteristics of Ambient Volatile Organic Compounds (VOCs Measured in Shanghai, China

    Directory of Open Access Journals (Sweden)

    Guang-Qiang Zhou

    2010-08-01

    Full Text Available To better understand the characteristics of ambient abundance of volatile organic compounds (VOCs in Shanghai, one of the biggest metropolis of China, VOCs were measured with a gas chromatography system equipped with a mass-selective detector (GC/MSD from July 2006 to February 2010. An intensive measurement campaign was conducted (eight samples per day with a 3 hour interval during May 2009. The comparison of ambient VOCs collected in different regions of Shanghai shows that the concentrations are slightly higher in the busy commercial area (28.9 ppbv at Xujiaui than in the urban administrative area (24.3 ppbv at Pudong. However, during the intensive measurement period, the concentrations in the large steel industrial area (28.7 ppbv at Baoshan were much higher than in the urban administrative area (18 ppbv at Pudong, especially for alkanes, alkenes, and toluene. The seasonal variations of ambient VOC concentrations measured at the Xujiahui sampling site indicate that the VOC concentrations are significantly affected by meteorological conditions (such as wind direction and precipitation. In addition, although alkanes are the most abundant VOCs at the Xujiahui measurement site, the most important VOCs contributing to ozone formation potential (OFP are aromatics, accounting for 57% of the total OFP. The diurnal variations of VOC concentrations show that VOC concentrations are higher on weekdays than in weekends at the Xujiahui sampling site, suggesting that traffic condition and human activities have important impacts on VOC emissions in Shanghai. The evidence also shows that the major sources of isoprene are mainly resulted from gasoline evaporation at a particular time (06:00–09:00 in the busy commercial area. The results gained from this study provide useful information for better understanding the characteristics of ambient VOCs and the sources of VOCs in Shanghai.

  1. A metrological approach to improve accuracy and reliability of ammonia measurements in ambient air

    Science.gov (United States)

    Pogány, Andrea; Balslev-Harder, David; Braban, Christine F.; Cassidy, Nathan; Ebert, Volker; Ferracci, Valerio; Hieta, Tuomas; Leuenberger, Daiana; Martin, Nicholas A.; Pascale, Céline; Peltola, Jari; Persijn, Stefan; Tiebe, Carlo; Twigg, Marsailidh M.; Vaittinen, Olavi; van Wijk, Janneke; Wirtz, Klaus; Niederhauser, Bernhard

    2016-11-01

    The environmental impacts of ammonia (NH3) in ambient air have become more evident in the recent decades, leading to intensifying research in this field. A number of novel analytical techniques and monitoring instruments have been developed, and the quality and availability of reference gas mixtures used for the calibration of measuring instruments has also increased significantly. However, recent inter-comparison measurements show significant discrepancies, indicating that the majority of the newly developed devices and reference materials require further thorough validation. There is a clear need for more intensive metrological research focusing on quality assurance, intercomparability and validations. MetNH3 (Metrology for ammonia in ambient air) is a three-year project within the framework of the European Metrology Research Programme (EMRP), which aims to bring metrological traceability to ambient ammonia measurements in the 0.5-500 nmol mol-1 amount fraction range. This is addressed by working in three areas: (1) improving accuracy and stability of static and dynamic reference gas mixtures, (2) developing an optical transfer standard and (3) establishing the link between high-accuracy metrological standards and field measurements. In this article we describe the concept, aims and first results of the project.

  2. Comparison of the measurement techniques employed for evaluation of ambient air odor quality

    Science.gov (United States)

    Wojnowski, Wojciech; Majchrzak, Tomasz; Gebicki, Jacek; Dymerski, Tomasz; Namieśnik, Jacek

    2016-11-01

    The paper presents the results of investigation on ambient air odor quality in a vicinity of the industrial sewage treatment plant being a part of the crude oil processing plant. The investigation was performed during spring-winter season using a prototype of electronic nose and the Nasal Ranger field olfactometers. The prototype was equipped with a set of six semiconductor sensors by FIGARO Co. and one PID-type sensor. The field olfactometers were used to determine mean concentration of odorants, which amounted from 2.2 to 20.2 ou/m3 depending on the place of measurement. In case of the investigation with the electronic nose prototype a classification of the ambient air samples with respect to the place of sampling was performed utilizing the kNN (where k=3) algorithm supported with a cross-validation method. Correct classification of the ambient air samples was at the level of 47.9%. Performed investigation revealed that evaluation of the ambient air samples with respect to odor was possible using the electronic nose instrument.

  3. Measurement, evaluation, and assessment of peripheral neurological disorders caused by hand-transmitted vibration.

    Science.gov (United States)

    Griffin, Michael J

    2008-04-01

    Regular exposure to hand-transmitted vibration can result in symptoms and signs of peripheral vascular, neurological and other disorders collectively known as the hand-arm vibration syndrome. The measurement of the effects of hand-transmitted vibration involves converting the evidence of disorder (symptoms and signs) into information that can be stored. Evaluation requires the use of scales on which to indicate the severity of the various symptoms and signs. Assessment involves a judgement of severity relative to a criterion, usually for a specific purpose (e.g. to decide on removal from work or compensation). The measurement and evaluation of symptoms and signs is necessary when monitoring patient health and when performing epidemiological studies for research. The assessment of the severity of the hand-arm vibration syndrome is currently performed with staging systems, but the criteria are not clear and not related to defined methods for measuring or evaluating the symptoms and signs. Recognizing that similar symptoms can occur without injury from occupational exposures to hand-transmitted vibration, this paper attempts to define significant peripheral neurological symptoms caused by hand-transmitted vibration (i.e. 'unusual symptoms') and how these symptoms and related signs may be measured. Scales for evaluating the symptoms (e.g. their extent) and the related signs (e.g. their probability relative to the probability of the sign being present in persons not exposed to vibration) are defined. A method of relating unusual symptoms to both the signs of disorder and the pattern of vibration exposure is illustrated. Assessments of severity will vary according to the reasons for assessing the health effects of vibration, and will depend on local practice and convenience, but a way of combining evaluations of symptoms and signs is demonstrated in a staging system. Although inherently complex, the methods may assist the collection of data required to improve

  4. A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping.

    Science.gov (United States)

    Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu

    2014-02-01

    In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

  5. Measurement of ground and nearby building vibration and noise induced by trains in a metro depot.

    Science.gov (United States)

    Zou, Chao; Wang, Yimin; Wang, Peng; Guo, Jixing

    2015-12-01

    Metro depots are where subway trains are parked and where maintenance is carried out. They usually occupy the largest ground areas in metro projects. Due to land utilization problems, Chinese cities have begun to develop over-track buildings above metro depots for people's life and work. The frequently moving trains, when going into and out of metro depots, can cause excessive vibration and noise to over-track buildings and adversely affect the living quality of the building occupants. Considering the current need of reliable experimental data for the construction of metro depots, field measurements of vibration and noise on the ground and inside a nearby 3-story building subjected to moving subway trains were conducted in a metro depot at Guangzhou, China. The amplitudes and frequency contents of velocity levels were quantified and compared. The composite A-weighted equivalent sound levels and maximum sound levels were captured. The predicted models for vibration and noise of metro depot were proposed based on existing models and verified. It was found that the vertical vibrations were significantly greater than the horizontal vibrations on the ground and inside the building near the testing line. While at the throat area, the horizontal vibrations near the curved track were remarkably greater than the vertical vibrations. The attenuation of the vibrations with frequencies above 50 Hz was larger than the ones below 50 Hz, and the frequencies of vibration transmitting to adjacent buildings were mainly within 10-50 Hz. The largest equivalent sound level generated in the throat area was smaller than the testing line one, but the instantaneous maximum sound level induced by wheels squeal, contact between wheels and rail joints as well as turnout was close to or even greater than the testing line one. The predicted models gave a first estimation for design and assessment of newly built metro depots.

  6. 1-D and 2-D resonances in an Alpine valley identified from ambient noise measurements and 3-D modelling

    Science.gov (United States)

    Le Roux, Olivier; Cornou, Cécile; Jongmans, Denis; Schwartz, Stéphane

    2012-09-01

    H/V spectral ratios are regularly used for estimating the bedrock depth in 1-D like basins exhibiting smooth lateral variations. In the case of 2-D or 3-D pronounced geometries, observational and numerical studies have shown that H/V curves exhibit peculiar shapes and that the H/V frequency generally overestimates 1-D theoretical resonance frequency. To investigate the capabilities of the H/V method in complex structures, a detailed comparison between measured and 3-D-simulated ambient vibrations was performed in the small-size lower Romanche valley (French Alps), which shows significant variations in geometry, downstream and upstream the Séchilienne basin. Analysing the H/V curve characteristics, two different wave propagation modes were identified along the valley. Relying on previous geophysical investigation, a power-law relationship was derived between the bedrock depth and the H/V peak frequency, which was used for building a 3-D model of the valley geometry. Simulated and experimental H/V curves were found to exhibit quite similar features in terms of curve shape and peak frequency values, validating the 3-D structure. This good agreement also evidenced two different propagation modes in the valley: 2-D resonance in the Séchilienne basin and 1-D resonance in the external parts. This study underlines the interest of H/V curves for investigating complex basin structures.

  7. Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating

    Institute of Scientific and Technical Information of China (English)

    Xiaojin Guo(郭晓金); Zongmin Yin(殷宗敏); Ning Song(宋宁)

    2004-01-01

    A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum.Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated.

  8. Measurements of bridges' vibration characteristics using a mobile phone

    Directory of Open Access Journals (Sweden)

    Z. M. C. Pravia

    Full Text Available ABSTRACTThis research presents an alternative way to perform a bridge inspection, which considers the dynamics parameters from the structure. It shows an experimental phase with use of a mobile phone to extract the accelerations answers from two concrete bridges, from those records is feasible to obtain natural frequencies using the Fast Fourier Transform (FFT.Numerical models with uses finite element model (FEM allow to determine the natural frequencies from the two concrete bridges and compare with the experimental phase of each one. The final results shows it's possible to use mobiles phones to extract vibration answers from concrete bridges and define the structural behavior of bridges from natural frequencies, this procedure could be used to evaluate bridges with lower costs.

  9. High-speed 3D digital image correlation vibration measurement: Recent advancements and noted limitations

    Science.gov (United States)

    Beberniss, Timothy J.; Ehrhardt, David A.

    2017-03-01

    A review of the extensive studies on the feasibility and practicality of utilizing high-speed 3 dimensional digital image correlation (3D-DIC) for various random vibration measurement applications is presented. Demonstrated capabilities include finite element model updating utilizing full-field 3D-DIC static displacements, modal survey natural frequencies, damping, and mode shape results from 3D-DIC are baselined against laser Doppler vibrometry (LDV), a comparison between foil strain gage and 3D-DIC strain, and finally the unique application to a high-speed wind tunnel fluid-structure interaction study. Results show good agreement between 3D-DIC and more traditional vibration measurement techniques. Unfortunately, 3D-DIC vibration measurement is not without its limitations, which are also identified and explored in this study. The out-of-plane sensitivity required for vibration measurement for 3D-DIC is orders of magnitude less than LDV making higher frequency displacements difficult to sense. Furthermore, the digital cameras used to capture the DIC images have no filter to eliminate temporal aliasing of the digitized signal. Ultimately DIC is demonstrated as a valid alternative means to measure structural vibrations while one unique application achieves success where more traditional methods would fail.

  10. Vibration Measurements to Study the Effect of Cryogen Flow in Superconducting Quadrupole.

    Energy Technology Data Exchange (ETDEWEB)

    He,P.; Anerella, M.; aydin, S.; Ganetis, G. Harrison, M.; Jain, A.; Parker, B.

    2007-06-25

    The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations in a spare RHIC quadrupole magnet under cryogenic conditions. Some preliminary results of these studies were limited in resolution due to a rather large motion of the laser head as well as the magnet. As a first step towards improving the measurement quality, a new set up was used that reduces the motion of the laser holder. The improved setup is described, and vibration spectra measured at cryogenic temperatures, both with and without helium flow, are presented.

  11. Measurements of Acoustic Properties of Porous and Granular Materials and Application to Vibration Control

    Science.gov (United States)

    Park, Junhong; Palumbo, Daniel L.

    2004-01-01

    For application of porous and granular materials to vibro-acoustic controls, a finite dynamic strength of the solid component (frame) is an important design factor. The primary goal of this study was to investigate structural vibration damping through this frame wave propagation for various poroelastic materials. A measurement method to investigate the vibration characteristics of the frame was proposed. The measured properties were found to follow closely the characteristics of the viscoelastic materials - the dynamic modulus increased with frequency and the degree of the frequency dependence was determined by its loss factor. The dynamic stiffness of hollow cylindrical beams containing porous and granular materials as damping treatment was measured also. The data were used to extract the damping materials characteristics using the Rayleigh-Ritz method. The results suggested that the acoustic structure interaction between the frame and the structure enhances the dissipation of the vibration energy significantly.

  12. Evaluation of a novel integrated sensor system for synchronous measurement of cardiac vibrations and cardiac potentials.

    Science.gov (United States)

    Chuo, Yindar; Tavakolian, Kouhyar; Kaminska, Bozena

    2011-08-01

    The measurement of human body vibrations as a result of heart beating, simultaneously with cardiac potentials have been demonstrated in past studies to bring additional value to diagnostic cardiology through the detection of irregularities in the mechanical movement of the heart. The equipment currently available to the medical community is either large and bulky or difficult to synchronize. To address this problem, a novel integrated sensor system has been developed to record cardiac vibration and cardiac potential simultaneously and synchronously from a single compact site on the chest. The developed sensor system is lightweight, small in size, and suitable for mounting on active moving patients. The sensor is evaluated for its adequacy in measuring cardiac vibrations and potentials. In this evaluation, 45 independent signal recording are studied from 15 volunteers, and the morphology of the recorded signals are analyzed qualitatively (by visual inspection) and quantitatively (by computational methods) against larger devices used in established cardiac vibration studies (reference devices). It is found that the cardiac vibration signals acquired by the integrated sensor has 92.37% and 81.76% identically identifiable systolic and diastolic cardiac complexes, respectively, when compared to the cardiac vibration signals recorded simultaneously from the reference device. Further, the cardiac potential signals acquired by the integrated sensor show a high correlation coefficient of 0.8912 and a high estimated signal-to-noise-ratio of 22.00 dB when compared to the reference electrocardiograph (non-standard leads) acquired through a common clinical machine. The results suggest that the tiny, wearable, integrated sensor system that synchronously measures cardiac vibrations and cardiac potentials may be practical for use as an alternative or assistive cardiac diagnostic tool.

  13. Measuring MEMS vibration with novel quasi-heterodyned laser interferometry

    Science.gov (United States)

    Styk, Adam; Lambelet, Patrick; Paris, Roman; Kujawińska, Małgorzata

    2012-06-01

    The paper presents novel interferometric measurement technique applied for MEMS dynamic properties measurements. The method was developed especially for multi-channel interferometer developed under SMARTIEHS EU project. The method employs sinusoidal modulation of light and novel smart-pixel camera detector. The measurement results obtained with developed measurement system and commercial Polytec system, obtained while measuring reference objects, are in good correspondence showing usefulness of proposed method.

  14. The Comparative Reactivity Method ─ a new tool to measure total OH Reactivity in ambient air

    Directory of Open Access Journals (Sweden)

    J. Lelieveld

    2008-04-01

    Full Text Available Hydroxyl (OH radicals play a vital role in maintaining the oxidizing capacity of the atmosphere. To understand variations in OH radicals both source and sink terms must be understood. Currently the overall sink term, or the total atmospheric reactivity to OH, is poorly constrained. Here, we present a new on-line method to directly measure the total OH reactivity (i.e.~total loss rate of OH radicals in a sampled air mass. In this method, a reactive molecule (X, not normally present in air, is passed through a glass reactor and its concentration is monitored with a suitable detector. OH radicals are then introduced in the glass reactor at a constant rate to react with X, first in the presence of zero air and then in the presence of ambient air containing VOCs and other OH reactive species. Comparing the amount of X exiting the reactor with and without the ambient air allows the air reactivity to be determined. In our existing set up, X is pyrrole and the detector used is a proton transfer reaction mass spectrometer. The present dynamic range for ambient air reactivity is about 6 to 300 s−1, with an overall maximum uncertainty of 25% above 8 s−1 and up to 50% between 6–8 s−1. The system has been tested and calibrated with different single and mixed hydrocarbon standards showing excellent linearity and accountability with the reactivity of the standards. Potential interferences such as high NO in ambient air, varying relative humidity and photolysis of pyrrole within the setup have also been investigated. While interferences due changing humidity and photolysis of pyrrole are easily overcome by ensuring that humidity in the set up does not change drastically and the photolytic loss of pyrrole is measured and taken into account, respectively, NO>10 ppb in ambient air remains a significant interference for the current configuration of the instrument. Field tests in the tropical rainforest of Suriname (~53 s and the urban atmosphere of Mainz

  15. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under th

  16. Estimation of ambient PM2.5 concentrations in Maryland and verification by measured values.

    Science.gov (United States)

    Walsh, Kenneth; Sherwell, John

    2002-10-01

    In 1997, Maryland had no available ambient Federal Reference Method data on particulate matter less than 2.5 microm in aerodynamic diameter (PM23), but did have annual ambient data for PM smaller than 10 microm (PM10) at 24 sites. The PM10 data were analyzed in conjunction with local annual and seasonal zip-code-level emission inventories and with speciated PM2.5 data from four nearby monitors in the IMPROVE network (located in the national parks, wildlife refuges, and wilderness areas) in an effort to estimate annual average and seasonal high PM2.5 concentrations at the 24 PM10 monitor sites operating from 1992 to 1996. All seasonal high concentrations were estimated to be below the 24-hr PM2.5 National Ambient Air Quality Standards (NAAQS) at the sites operating in Maryland between 1992 and 1996. The estimates also indicated that 12 monitor sites might exceed the 3-year annual average PM2.5 NAAQS of 15 microg/m3, but Maryland's air quality shows signs that it has been improving since 1992. The estimates also were compared with actual measurements after the PM2.5 monitor network was installed. The estimates were adequate for describing the chemical composition of the PM2.5, forecasting compliance status with the 24-hr and annual standards, and determining the spatial variations in PM2.5 across central Maryland.

  17. Simulation of vibration-induced effect on plasma current measurement using a fiber optic current sensor.

    Science.gov (United States)

    Descamps, Frédéric; Aerssens, Matthieu; Gusarov, Andrei; Mégret, Patrice; Massaut, Vincent; Wuilpart, Marc

    2014-06-16

    An accurate measurement of the plasma current is of paramount importance for controlling the plasma magnetic equilibrium in tokamaks. Fiber optic current sensor (FOCS) technology is expected to be implemented to perform this task in ITER. However, during ITER operation, the vessel and the sensing fiber will be subject to vibrations and thus to time-dependent parasitic birefringence, which may significantly compromise the FOCS performance. In this paper we investigate the effects of vibrations on the plasma current measurement accuracy under ITER-relevant conditions. The simulation results show that in the case of a FOCS reflection scheme including a spun fiber and a Faraday mirror, the error induced by the vibrations is acceptable regarding the ITER current diagnostics requirements.

  18. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    Science.gov (United States)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsälä, M.; Hoekstra, S.; Halonen, L.

    2016-06-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν4 1 + ν5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) × 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.

  19. Remote vibration measurement: a wireless passive surface acoustic wave resonator fast probing strategy.

    Science.gov (United States)

    Friedt, J-M; Droit, C; Ballandras, S; Alzuaga, S; Martin, G; Sandoz, P

    2012-05-01

    Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/π periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

  20. Direct measurement of time dependent diffusion for Ag and Au under ambient conditions

    Science.gov (United States)

    Yoo, Pil Sun; Jo, Han Yeol; Kim, Taekyeong

    2014-12-01

    Time-dependent diffusion for Ag and Au metal atoms was measured using the scanning tunneling microscope break-junction technique in ambient conditions. We observed that Ag contacts do not form long single-atomic chains compared to Au contacts during the elongation of each metal electrode, and Ag atoms diffuse more quickly than Au atoms after metal contact rupture. This is consistent with previous results of molecular dynamic simulations. Further, we found a correlation between diffusion length and the evolution time on an atomic scale to reveal the time-dependent diffusion for Ag and Au metal atoms.

  1. Measurements and analysis of vibrations at Virilla Bridge, national route N° 1

    Directory of Open Access Journals (Sweden)

    Francisco Navarro-Henríquez

    2015-06-01

    The measurements allowed quantifying the vibration magnitudes and deformation in various sections of the bridge, on condition of vehicular traffic service (environmental performance. The experimental results are compared with computational analytical modeling of the structure and also with national and international standards.

  2. Bias Errors in Measurement of Vibratory Power and Implication for Active Control of Structural Vibration

    DEFF Research Database (Denmark)

    Ohlrich, Mogens; Henriksen, Eigil; Laugesen, Søren

    1997-01-01

    control of vibratory power transmission into structures. This is demonstrated by computer simulations using a theoretical model of a beam structure which is driven by one primary source and two control sources. These simulations reveal the influence of residual errors on power measurements......, and the limitations imposed in active control of structural vibration based upon a strategy of power minimisation....

  3. Torsional vibration measurements on rotating shaft system using laser doppler vibrometer

    Science.gov (United States)

    Xiang, Ling; Yang, Shixi; Gan, Chunbiao

    2012-11-01

    In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics.

  4. Selection of optimal threshold to construct recurrence plot for structural operational vibration measurements

    Science.gov (United States)

    Yang, Dong; Ren, Wei-Xin; Hu, Yi-Ding; Li, Dan

    2015-08-01

    The structural health monitoring (SHM) involves the sampled operational vibration measurements over time so that the structural features can be extracted accordingly. The recurrence plot (RP) and corresponding recurrence quantification analysis (RQA) have become a useful tool in various fields due to its efficiency. The threshold selection is one of key issues to make sure that the constructed recurrence plot contains enough recurrence points. Different signals have in nature different threshold values. This paper is aiming at presenting an approach to determine the optimal threshold for the operational vibration measurements of civil engineering structures. The surrogate technique and Taguchi loss function are proposed to generate reliable data and to achieve the optimal discrimination power point where the threshold is optimum. The impact of selecting recurrence thresholds on different signals is discussed. It is demonstrated that the proposed method to identify the optimal threshold is applicable to the operational vibration measurements. The proposed method provides a way to find the optimal threshold for the best RP construction of structural vibration measurements under operational conditions.

  5. THE MEASUREMENT AND STUDY OF BLASTING VIBRATION AFFECTING IN SITU CAST CONCRETE LINING OF VERTICAL SHAFT

    Institute of Scientific and Technical Information of China (English)

    黄琦; 李玉民

    1997-01-01

    Vertical shaft is main form of drivage in deep mineral depoist. They also serve as the entrance into and the exit from the underground mine. The main problems in shaft and tunnel engineering is to solve the contradiction between drivage and lining. The measurement of blasting vibration affecting concrete lining strength of vertical shaft is carried out in experiment and theory in this paper.

  6. On-line Measurement of Water-Soluble Ions in Ambient Particles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO42-,NO-3, NO-2, Cl- and F- is below 0.3 μg m-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

  7. Measurement of ambient aerosol hydration state at Great Smoky Mountains National Park in the southeastern United States

    Directory of Open Access Journals (Sweden)

    N. F. Taylor

    2011-12-01

    Full Text Available We present results from two field deployments of a unique tandem differential mobility analyzer (TDMA configuration with two primary capabilities: identifying alternative stable or meta-stable ambient aerosol hydration states associated with hysteresis in aerosol hydration behavior and determining the actual Ambient hydration State (AS-TDMA. This data set is the first to fully classify the ambient hydration state of aerosols despite recognition that hydration state significantly impacts the roles of aerosols in climate, visibility and heterogeneous chemistry. The AS-TDMA was installed at a site in eastern Tennessee on the border of Great Smoky Mountains National Park for projects during the summer of 2006 and winter of 2007–2008. During the summer, 12% of the aerosols sampled in continuous AS-TDMA measurements were found to posses two possible hydration states under ambient conditions. In every case, the more hydrated of the possible states was occupied. The remaining 88% did not posses multiple possible states. In continuous measurements during the winter, 49% of the aerosols sampled possessed two possible ambient hydration states; the remainder possessed only one. Of those aerosols with multiple possible ambient hydration states, 65% occupied the more hydrated state; 35% occupied the less hydrated state. This seasonal contrast is supported by differences in the fine particulate (PM2.5 composition and ambient RH as measured during the two study periods. In addition to seasonal summaries, this work includes case studies depicting the variation of hydration state with changing atmospheric conditions.

  8. Influence of vibration disturbance during polarization coupling measurement of polarization-maintaining fiber.

    Science.gov (United States)

    Guo, Zhenwu; Zhang, Hongxia; Chen, Xinwei; Jia, Dagong; Liu, Tiegen

    2011-07-10

    The principle of the mode cross coupling in polarization-maintaining fiber based on white-light interferometry was analyzed. The method of measuring the polarization mode coupling with a spatial Michelson interferometer was presented. Analysis and emulation were carried out for the vibration disturbance signal caused by the mechanical scanning and the influence the vibration imposed on the judgment of coupling intensity. The interference signal envelope is extracted by a Hilbert transform and fitted by a Gaussian least-squares method under the different scanning speed. It is indicated that the detection accuracy varies with the vibration amplitude, which varies with scanning speed. The best scanning speed of the system should be from 0.7 mm/s to 0.9 mm/s to achieve the minimum detection error.

  9. Quantitative measurement of radiation pressure on a microcantilever in ambient environment

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dakang; Munday, Jeremy N., E-mail: jnmunday@umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Garrett, Joseph L. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

    2015-03-02

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Micro/nano-mechanical transducers have become sensitive enough that radiation pressure can influence these systems. However, photothermal effects often accompany and overwhelm the radiation pressure, complicating its measurement. In this letter, we investigate the radiation force on an uncoated silicon nitride microcantilever in ambient conditions. We identify and separate the radiation pressure and photothermal forces through an analysis of the cantilever's frequency response. Further, by working in a regime where radiation pressure is dominant, we are able to accurately measure the radiation pressure. Experimental results are compared to theory and found to agree within the measured and calculated uncertainties.

  10. Quantification of the influence of external vibrations on the measurement error of a Coriolis mass-flow meter

    NARCIS (Netherlands)

    Ridder, van de L.; Hakvoort, W.B.J.; Dijk, van J.; Lötters, J.C.; Boer, de A.

    2014-01-01

    In this paper the influence of external vibrations on the measurement value of a Coriolis mass-flow meter (CMFM) for low flows is investigated and quantified. Model results are compared with experimental results to improve the knowledge on how external vibrations affect the mass-flow measurement val

  11. Vibrational measurement for commissioning SRF Accelerator Test Facility at Fermilab

    CERN Document Server

    McGee, M W; Martinez, A; Pischalnikov, Y; Schappert, W

    2012-01-01

    The commissioning of two cryomodule components is underway at Fermilab's Superconducting Radio Frequency (SRF) Accelerator Test Facility. The research at this facility supports the next generation high intensity linear accelerators such as the International Linear Collider (ILC), a new high intensity injector (Project X) and other future machines. These components, Cryomodule #1 (CM1) and Capture Cavity II (CC2), which contain 1.3 GHz cavities are connected in series in the beamline and through cryogenic plumbing. Studies regarding characterization of ground motion, technical and cultural noise continue. Mechanical transfer functions between the foundation and critical beamline components have been measured and overall system displacement characterized. Baseline motion measurements given initial operation of cryogenic, vacuum systems and other utilities are considered.

  12. Vibrational measurement for commissioning SRF Accelerator Test Facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, M.W.; Leibfritz, J.; Martinez, A.; Pischalnikov, Y.; Schappert, W.; /Fermilab

    2011-03-01

    The commissioning of two cryomodule components is underway at Fermilab's Superconducting Radio Frequency (SRF) Accelerator Test Facility. The research at this facility supports the next generation high intensity linear accelerators such as the International Linear Collider (ILC), a new high intensity injector (Project X) and other future machines. These components, Cryomodule No.1 (CM1) and Capture Cavity II (CC2), which contain 1.3 GHz cavities are connected in series in the beamline and through cryogenic plumbing. Studies regarding characterization of ground motion, technical and cultural noise continue. Mechanical transfer functions between the foundation and critical beamline components have been measured and overall system displacement characterized. Baseline motion measurements given initial operation of cryogenic, vacuum systems and other utilities are considered.

  13. The relationship between ambient ultraviolet radiation (UVR) and objectively measured personal UVR exposure dose is modified by season and latitude.

    Science.gov (United States)

    Sun, J; Lucas, R M; Harrison, S; van der Mei, I; Armstrong, B K; Nowak, M; Brodie, A; Kimlin, M G

    2014-12-01

    Despite the widespread use of ambient ultraviolet radiation (UVR) as a proxy measure of personal exposure to UVR, the relationship between the two is not well-defined. This paper examines the effects of season and latitude on the relationship between ambient UVR and personal UVR exposure. We used data from the AusD Study, a multi-centre cross-sectional study among Australian adults (18-75 years), where personal UVR exposure was objectively measured using polysulphone dosimeters. Data were analysed for 991 participants from 4 Australian cities of different latitude: Townsville (19.3°S), Brisbane (27.5°S), Canberra (35.3°S) and Hobart (42.8°S). Daily personal UVR exposure varied from 0.01 to 21 Standard Erythemal Doses (median = 1.1, IQR: 0.5-2.1), on average accounting for 5% of the total available ambient dose. There was an overall positive correlation between ambient UVR and personal UVR exposure (r = 0.23, p exposure fraction of total available ambient dose was highest in winter (7%) and amongst Hobart participants (7%) and lowest in summer (1%) and in Townsville (4%). These results suggest season and latitude modify the relationship between ambient UVR and personal UVR exposure. Ambient UVR may not be a good indicator for personal exposure dose under some circumstances.

  14. MODELLING AND VIBRATION ANALYSIS OF A ROAD PROFILE MEASURING SYSTEM

    Directory of Open Access Journals (Sweden)

    C. B. Patel

    2010-06-01

    Full Text Available During a vehicle development program, load data representing severe customer usage is required. The dilemma faced by a design engineer during the design process is that during the initial stage, only predicted loads estimated from historical targets are available, whereas the actual loads are available only at the fag end of the process. At the same time, changes required, if any, are easier and inexpensive during the initial stages of the design process whereas they are extremely costly in the latter stages of the process. The use of road profiles and vehicle models to predict the load acting on the whole vehicle is currently being researched. This work hinges on the ability to accurately measure road profiles. The objective of the work is to develop an algorithm, using MATLAB Simulink software, to convert the input signals into measured road profile. The algorithm is checked by the MATLAB Simulink 4 degrees of freedom half car model. To make the whole Simulink model more realistic, accelerometer and laser sensor properties are introduced. The present work contains the simulation of the mentioned algorithm with a half car model and studies the results in distance, time, and the frequency domain.

  15. Vibration characteristics measurement of beam-like structures using infrared thermography

    Science.gov (United States)

    Talai, S. M.; Desai, D. A.; Heyns, P. S.

    2016-11-01

    Infrared thermography (IRT) has matured and is now widely accepted as a condition monitoring tool where temperature is measured in a non-contact way. Since the late 1970s, it has been extensively used in vibrothermography (Sonic IR) non-destructive technique for the evaluation of surface cracks through the observation of thermal imaging of the vibration-induced crack heat generation. However, it has not received research attention on prediction of structural vibration behaviour, hence; the concept to date is not understood. Therefore, this paper explores its ability to fill the existing knowledge gap. To achieve this, two cantilever beam-like structures couple with a friction rod subjected to a forced excitations while infrared cameras capturing the thermal images on the friction interfaces. The analysed frictional temperature evolution using the Matlab Fast Fourier Transform (FFT) algorithm and the use of the heat conduction equation in conjunction with a finite difference approach successfully identifies the structural vibration characteristics; with maximum error of 0.28% and 20.71% for frequencies and displacements, respectively. These findings are particularly useful in overcoming many limitations inherent in some of the current vibration measuring techniques applied in structural integrity management such as strain gauge failures due to fatigue.

  16. Influence of ambient temperature on whole body and segmental bioimpedance spectroscopy measurements

    Science.gov (United States)

    Medrano, G.; Bausch, R.; Ismail, A. H.; Cordes, A.; Pikkemaat, R.; Leonhardt, S.

    2010-04-01

    Bioimpedance spectroscopy (BIS) measurements are easy to implement and could be used for continuous monitoring. However, several factors (e.g. environment temperature) influence the measurements limiting the accuracy of the technology. Changes in skin temperature produced by changes in ambient temperature are related with changes in skin blood flow and skin impedance. It is assumed that skin impedance change is responsible for the error observed in whole body and segmental measurements. Measurements including body parts more distant from the torso seem to be more affected. In the present article skin and segment impedance have been performed on healthy subjects under extreme changes in environment temperature (13-39 °C). A commercial BIS device with a range between 5 kHz and 1 MHz has been used for the measurements. The results indicate that not only skin impedance, but also impedance of deeper tissue (e.g. muscle) may be responsible for the influence of environment temperature on BIS measurements. Segmental (knee-to-knee) BIS measurements show a relative change of only 2 %, while forearm and whole body impedance changed 14 % and 8 % respectively.

  17. Measuring the resonant vibration of a sessile droplet using MEMS based cantilevers

    Science.gov (United States)

    Nguyen, Thanh-Vinh; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-11-01

    We directly measure the normal force distribution on the contact area during the 1st mode resonant vibration of a droplet using an array of MEMS based cantilever. The measurement result shows that the normal force change is the largest at the periphery of the contact area. The ratio between the amplitude of the normal force change at the periphery of the contact area over that at the center of the contact area was approximately 20 times, in the case of 1.8 μL water droplet whose equilibrium contact angle is 140 degrees. We also demonstrate a method to estimate viscosity based on the measurement of the droplet vibration using MEMS cantilevers. The proposed method is able to estimate viscosity using less than 3 μL sample and has a simple operating principle. We believe that this method is suitable for point-of-care testing and characterization of chemical and biological solutions.

  18. Analysis of classical guitars' vibrational behavior based on scanning laser vibrometer measurements

    Science.gov (United States)

    Czajkowska, Marzena

    2012-06-01

    One of the main goals in musical acoustics research is to link measurable, physical properties of a musical instrument with subjective assessments of its tone quality. The aim of the research discussed in this paper was to observe the structural vibrations of different class classical guitars in relation to their quality. This work focuses on mid-low-and low-class classical (nylon-stringed) guitars. The main source of guitar body vibrations come from top and back plate vibrations therefore these were the objects of structural mode measurements and analysis. Sixteen classical guitars have been investigated, nine with cedar and seven with spruce top plate. Structural modes of top and back plates have been measured with the aid of a scanning laser vibrometer and the instruments were excited with a chirp signal transferred by bone vibrator. The issues related to excitor selection have been discussed. Correlation and descriptive statistics of top and back plates measurement results have been investigated in relation to guitar quality. The frequency range of 300 Hz to 5 kHz as well as selected narrowed frequency bands have been analyzed for cedar and spruce guitars. Furthermore, the influence of top plate wood type on vibration characteristics have been observed on three pairs of guitars. The instruments were of the same model but different top plate material. Determination and visualization of both guitar plates' modal patterns in relation to frequency are a significant attainment of the research. Scanning laser vibrometer measurements allow particular mode observation and therefore mode identification, as opposed to sound pressure response measurements. When correlating vibration characteristics of top and back plates it appears that Pearson productmoment correlation coefficient is not a parameter that associates with guitar quality. However, for best instruments with cedar top, top-back correlation coefficient has relatively greater value in 1-2 kHz band and lower in

  19. A nanogenerator as a self-powered sensor for measuring the vibration spectrum of a drum membrane.

    Science.gov (United States)

    Yu, Aifang; Zhao, Yong; Jiang, Peng; Wang, Zhong Lin

    2013-02-08

    A nanogenerator (NG) is a device that converts vibration energy into electricity. Here, a flexible, small size and lightweight NG is successfully demonstrated as an active sensor for detecting the vibration spectrum of a drum membrane without the use of an external power source. The output current/voltage signal of the NG is a direct measure of the strain of the local vibrating drum membrane that contains rich informational content, such as, notably, the vibration frequency, vibration speed and vibration amplitude. In comparison to the laser vibrometer, which is excessively complex and expensive, this kind of small and low cost sensor based on an NG is also capable of detecting the local vibration frequency of a drum membrane accurately. A spatial arrangement of the NGs on the membrane can provide position-dependent vibration information on the surface. The measured frequency spectrum can be understood on the basis of the theoretically calculated vibration modes. This work expands the application of NGs and reveals the potential for developing sound wave detection, environmental/infrastructure monitoring and many more applications.

  20. Quantitative estimation of the influence of external vibrations on the measurement error of a coriolis mass-flow meter

    NARCIS (Netherlands)

    Ridder, van de L.; Hakvoort, W.B.J.; Dijk, van J.; Lötters, J.C.; Boer, de A.; Dimitrovova, Z.; Almeida, de J.R.

    2013-01-01

    In this paper the quantitative influence of external vibrations on the measurement value of a Coriolis Mass-Flow Meter for low flows is investigated, with the eventual goal to reduce the influence of vibrations. Model results are compared with experimental results to improve the knowledge on how ext

  1. IEEE 802.11-Based Wireless Sensor System for Vibration Measurement

    Directory of Open Access Journals (Sweden)

    Yutaka Uchimura

    2010-01-01

    Full Text Available Network-based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of building or civil engineering structure and it often requires vibration measurement. For the vibration measurement via wireless network, time synchronization is indispensable. In this paper, we introduce a newly developed time synchronized wireless sensor network system. The system employs IEEE 802.11 standard-based TSF-counter and sends the measured data with the counter value. TSF based synchronization enables consistency on common clock among different wireless nodes. We consider the scale effect on synchronization accuracy and evaluated the effect by taking beacon collisions into account. The scalability issue by numerical simulations is also studied. This paper also introduces a newly developed wireless sensing system and the hardware and software specifications are introduced. The experiments were conducted in a reinforced concrete building to evaluate synchronization accuracy. The developed system was also applied for a vibration measurement of a 22-story steel structured high rise building. The experimental results showed that the system performed more than sufficiently.

  2. A MEMS Resonant Sensor to Measure Fluid Density and Viscosity under Flexural and Torsional Vibrating Modes.

    Science.gov (United States)

    Zhao, Libo; Hu, Yingjie; Wang, Tongdong; Ding, Jianjun; Liu, Xixiang; Zhao, Yulong; Jiang, Zhuangde

    2016-01-01

    Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS) technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m³ to 900 kg/m³ and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.

  3. Application of Blind Source Separation Algorithms and Ambient Vibration Testing to the Health Monitoring of Concrete Dams

    Directory of Open Access Journals (Sweden)

    Lin Cheng

    2016-01-01

    Full Text Available In this work, using AVT data, a health monitoring method for concrete dams based on two different blind source separation (BSS methods, that is, second-order blind identification (SOBI and independent component analysis (ICA, is proposed. A modal identification procedure, which integrates the SOBI algorithm and modal contribution, is first adopted to extract structural modal features using AVT data. The method to calculate the modal contribution index for SOBI-based modal identification methods is studied, and the calculated modal contribution index is used to determine the system order. The selected modes are then used to calculate modal features and are analysed using ICA to extract some independent components (ICs. The square prediction error (SPE index and its control limits are then calculated to construct a control chart for the structural dynamic features. For new AVT data of a dam in an unknown health state, the newly calculated SPE is compared with the control limits to judge whether the dam is normal. With the simulated AVT data of the numerical model for a concrete gravity dam and the measured AVT data of a practical engineering project, the performance of the dam health monitoring method proposed in this paper is validated.

  4. Vibration measurement through high speed vision system in a civil structure under impact loading

    Science.gov (United States)

    Ferrer, Belén; García, Juan I.; Roig, Ana B.; Mas, David

    2014-05-01

    The method presented in this work is a simple, cheap and non-contact method. It is based on image processing using a circular target. It has subpixel accuracy and it only needs a low cost high-speed camera and a tripod. In the work presented in this paper, a Casio Exilim camera was used to measure the vibration of a pedestrian bridge. An impact load was applied on the bridge through one person jumping in the middle of the bridge. Tracking of the circle border give the center trajectory and therefore the displacement and frequency of the movement. Some accelerometers were used as a contrast device for the frequency. The displacement obtained by our procedure was previously checked in laboratory using a micrometric bench. The results show that this method is suitable for measuring successfully the vibration of civil structures.

  5. Hybrid predictions of railway induced ground vibration using a combination of experimental measurements and numerical modelling

    Science.gov (United States)

    Kuo, K. A.; Verbraken, H.; Degrande, G.; Lombaert, G.

    2016-07-01

    Along with the rapid expansion of urban rail networks comes the need for accurate predictions of railway induced vibration levels at grade and in buildings. Current computational methods for making predictions of railway induced ground vibration rely on simplifying modelling assumptions and require detailed parameter inputs, which lead to high levels of uncertainty. It is possible to mitigate against these issues using a combination of field measurements and state-of-the-art numerical methods, known as a hybrid model. In this paper, two hybrid models are developed, based on the use of separate source and propagation terms that are quantified using in situ measurements or modelling results. These models are implemented using term definitions proposed by the Federal Railroad Administration and assessed using the specific illustration of a surface railway. It is shown that the limitations of numerical and empirical methods can be addressed in a hybrid procedure without compromising prediction accuracy.

  6. Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

    Institute of Scientific and Technical Information of China (English)

    Jinghua Zhang; Xueguang Qiao; Manli Hu; Zhongyao Feng; Hong Gao; Yang Yang; Rui Zhou

    2011-01-01

    @@ The intelligent structural health monitoring method,which uses a fiber Bragg grating(FBG)sensor,is a new approach in the field of civil engineering.However,it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements.In this letter,a flextensional FBG-based accelerometer is proposed and demonstrated.The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz,with a high sensitivity of 410.7 pm/g.In addition,it has a broad and flat response over low frequencies ranging from 1 to 10 Hz.The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications.Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer.These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.%The intelligent structural health monitoring method, which uses a fiber Bragg grating {FBG} sensor, ie a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.

  7. Non-contact skin emissivity: measurement from reflectance using step change in ambient radiation temperature.

    Science.gov (United States)

    Togawa, T

    1989-02-01

    A method of estimating skin emissivity based on reflectance measurement upon transient stepwise change in the ambient radiation temperature was proposed. To effect this change, two shades at different temperatures were switched mechanically, and the change in radiation from the skin surface was recorded through an aperture for each shade by a high-resolution, fast-response radiometer having a sensitivity within the 8-14 microns range. Measurements were made on the forehead, forearm, palm and back of the hand in 10 male and 10 female subjects. No significant differences in emissivity were observed among sites and between sexes. The overall average of the skin emissivity obtained was 0.971 +/- 0.005 (SD). This result is inconsistent with most reported skin emissivity values. However, as the former studies had many inherent inadequacies, both theoretical and experimental, it is considered that most of these reported skin emissivities are unacceptable. The method proposed in this study has the following advantages: (1) relative calibration between instruments is unnecessary, (2) non-contact measurement can be achieved, and (3) each measurement can be made within one minute.

  8. Cryogen free automated gas chromatography for the measurement of ambient volatile organic compounds.

    Science.gov (United States)

    Wang, J L; Chen, W L; Lin, Y H; Tsai, C H

    2000-10-27

    An automated gas chromatographic system was constructed for measuring ambient volatile organic compounds (VOCs). Preconcentration of the VOCs was performed by using two separated sorbent traps of different combinations with each designated for either low or high boiling VOCs. Both traps and their associated valve systems were integrated as a complete system sharing a common sample inlet. Precise temperature controls for desorption relied on the use of a process controller with proportional-integral-derivative algorithm to throttle the current supply. No additional cryo-focusing stage prior to the column was needed owing to the flash heating capability for desorption. Other than the cryogen free preconcentration and focusing, the separation of VOCs of large volatility difference was also performed without cryogen. The system employed an Al2O3/KCl porous-layer open tubular column for separating C3-C7 compounds; and a DB-1 column for C6-C12. This automated GC system has been deployed in a Taiwan Environmental Protection Agency urban air quality monitoring station of Taiwan for continuous measuring C3-C7 ozone precursors. Excellent correlation between the car exhaust type of compounds measured by our GC system and carbon monoxide measured by a non-dispersive infrared spectrometer was observed, suggesting the automated GC system was robust and reliable.

  9. LDV measurement of bird ear vibrations to determine inner ear impedance and middle ear power flow

    Science.gov (United States)

    Muyshondt, Pieter G. G.; Pires, Felipe; Dirckx, Joris J. J.

    2016-06-01

    The mechanical behavior of the middle ear structures in birds and mammals is affected by the fluids in the inner ear (IE) that are present behind the oval window. In this study, the aim was to gather knowledge of the acoustic impedance of the IE in the ostrich, to be able to determine the effect on vibrations and power flow in the single-ossicle bird middle ear for future studies. To determine the IE impedance, vibrations of the ossicle were measured for both the quasi-static and acoustic stimulus frequencies. In the acoustic regime, vibrations were measured with a laser Doppler vibrometer and electromagnetic stimulation of the ossicle. The impedance of the inner ear could be determined by means of a simple RLC model in series, which resulted in a stiffness reactance of KIE = 0.20.1012 Pa/m3, an inertial impedance of MIE = 0.652.106 Pa s2/m3, and a resistance of RIE = 1.57.109 Pa s/m. The measured impedance is found to be considerably smaller than what is found for the human IE.

  10. Optical multi-frequency swept sensing for wide-field vibration measurement of interior surfaces in biological tissue

    Science.gov (United States)

    Choi, S.; Nin, F.; Hibino, H.; Suzuki, T.

    2015-12-01

    Multifrequency sensing technique adopting the wide field heterodyne detection technique is demonstrated for interior surface vibration measurements in thick biological tissue. These arrangements allow obtaining not only 3D tomographic images but also various vibration parameters such as spatial amplitude, phase, and frequency, with high temporal and transverse resolutions over a wide field. The axial resolution and the accuracy of vibration amplitude measurement were estimated to be 2.5 μm and 3 nm, respectively. This wide-field tomographic sensing method can be applied for measuring microdynamics of a variety of biological samples, thus contributing to the progress in life sciences research.

  11. High frequent total station measurements for the monitoring of bridge vibrations

    Science.gov (United States)

    Lienhart, Werner; Ehrhart, Matthias; Grick, Magdalena

    2017-03-01

    Robotic total stations (RTS) are frequently used for the measurement of temperature induced bridge deformations or during load testing of bridges. In experimental setups, total stations have also been used for the measurement of dynamic bridge deformations. However, with standard configurations the measurement rate is not constant and on average an update rate of 7-10Hz can be achieved. This is not sufficient for the vibration monitoring of bridges considering their natural frequencies which are also in the same range. In this paper, we present different approaches to overcome these problems. In the first two approaches we demonstrate how the measurement rate to prisms can be increased to 20Hz to determine vertical deformations of bridges. Critical aspects like the measurement resolution of the automated target tracking and the correct sequence of steering commands are discussed. In another approach we demonstrate how vertical bridge vibrations can be measured using an image assisted total station (IATS) and corresponding processing techniques. The advantage of image-based methods is that structural features of a bridge like bolts can be used as targets. Therefore, no expensive prisms have to be mounted and access to the bridge is not required. All approaches are verified by laboratory investigations and their suitability is proven in a field experiment on a 74m long footbridge. In this field experiment the natural frequencies derived from the total station measurements are compared to the results of accelerometer measurements.

  12. Study on the Method for Collecting Vibration Signals from Mill Shell Based on Measuring the Fill Level of Ball Mill

    Directory of Open Access Journals (Sweden)

    Peng Huang

    2014-01-01

    Full Text Available At present the method for measuring the fill level which used the vibration signal of mill shell shows its advantage compared with other methods. However, this method is developed late, and the technique for collecting the vibration signal from mill shell is immature. In this paper, a novel method for collecting the vibration data from mill shell is proposed. Firstly, the layout scheme of vibration sensors on mill shell is given by analyzing the axial and circumferential movement of coal powder in roller. And a special data acquisition system is developed, which can acquire vibration data from different axial and circumferential positions on mill shell. Then the sampling frequency is obtained based on impact model and hierarchical model of steel balls. At the same time, the impact region on mill shell caused by steel balls is considered as the collecting region of vibration signals. Experimental result shows that vibration signals collected by the method proposed in this paper present a high sensitivity to the changes on fill level compared with vibration data of mill bearing, which provides a reliable basis for accurate measurement of the fill level.

  13. Measurement of mechanical quality factors of polymers in flexural vibration for high-power ultrasonic application.

    Science.gov (United States)

    Wu, Jiang; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2016-07-01

    A method for measuring the mechanical quality factor (Q factor) of materials in large-amplitude flexural vibrations was devised on the basis of the original definition of the Q factor. The Q factor, the ratio of the reactive energy to the dissipated energy, was calculated from the vibration velocity distribution. The bar thickness was selected considering the effect of the thickness on the estimation error. In the experimental setup, a 1-mm-thick polymer-based bar was used as a sample and fixed on the top of a longitudinal transducer. Using transducers of different lengths, flexural waves in the frequency range of 20-90kHz were generated on the bar. The vibration strain in the experiment reached 0.06%. According to the Bernoulli-Euler model, the reactive energy and dissipated energy were estimated from the vertical velocity distribution on the bar, and the Q factors were measured as the driving frequency and strain were varied. The experimental results showed that the Q factors decrease as the driving frequencies and strains increase. At a frequency of 28.30kHz, the Q factor of poly(phenylene sulfide) (PPS) reached approximately 460 when the strain was smaller than 0.005%. PPS exhibited a much higher Q factor than the other tested polymers, which implies that it is a potentially applicable material as the elastomer for high-power ultrasonic devices.

  14. Determining the location of buried plastic water pipes from measurements of ground surface vibration

    Science.gov (United States)

    Muggleton, J. M.; Brennan, M. J.; Gao, Y.

    2011-09-01

    ‘Mapping the Underworld' is a UK-based project, which aims to create a multi-sensor device that combines complementary technologies for remote buried utility service detection and location. One of the technologies to be incorporated in the device is low-frequency vibro-acoustics, and techniques for detecting buried infrastructure, in particular plastic water pipes, are being investigated. One of the proposed techniques involves excitation of the pipe at some known location with concurrent vibrational mapping of the ground surface in order to infer the location of the remainder of the pipe. In this paper, measurements made on a dedicated pipe rig are reported. Frequency response measurements relating vibrational velocity on the ground to the input excitation were acquired. Contour plots of the unwrapped phase revealed the location of the pipe to within 0.1-0.2 m. Magnitude contour plots revealed the excitation point and also the location of the pipe end. By examining the unwrapped phase gradients along a line above the pipe, it was possible to identify the wave-type within the pipe responsible for the ground surface vibration. Furthermore, changes in the ground surface phase speed computed using this method enabled the location of the end of the pipe to be confirmed.

  15. Geared induction motor fault diagnosis by current, noise and vibration considering measurement environment

    Directory of Open Access Journals (Sweden)

    Ki-Seok Kim

    2017-01-01

    Full Text Available Lots of motors have been being used in industry. Therefore many studies have been carried out about the failure diagnosis of motors. In this paper, a diagnosis of gear fault connected to a motor shaft is studied. The fault diagnosis is executed through the comparison of normal gear and abnormal gear. In the abnormal gearbox, a tooth of the intermediate gear is damaged. The measured FFT data are compared with the normal data and analyzed for q-axis current, noise and vibration. Fault gear was found by comparing the FFT with normal FFT. From these, the difference between the normal and abnormal states can be seen by the frequency characteristic analysis for the current as well as noise and vibration.

  16. Application of Numerical Simulation and Vibration Measurements for Seismic Damage Assessment of Railway Structures

    Science.gov (United States)

    Uehan, Fumiaki; Meguro, Kimiro

    In this study, the authors discuss methods to assess the future/actual damage to RC structures by using numerical simulations and vibration measurements. First, the applicability of the Applied Element Method (AEM) is examined as an assessment tool for the seismic performance of RC structures with/without retrofit. Cyclic loading tests and seismic response of RC structures are simulated. Next, a method to improve the accuracy of vibration diagnoses of earthquake damaged RC structures is discussed by using damage assessment criteria calculated with the AEM. The AEM could simulate the damage behavior of RC columns, jacketed RC columns and an actual railway viaduct. The change of natural frequencies due to damage to RC columns and an actual railway viaduct with steel jacket were also correctly estimated. Seismic performance check of structures and development of assessment criteria for damage inspection can be effectively done by the AEM.

  17. Development of a hand- transmitted vibration measurement instrument to perform tests in medical equipment according to the international standard IEC 60601-1-2005 Ed.3

    Science.gov (United States)

    de Lima, F. F.; Moriya, H. T.; Moraes, J. C. T. B.

    2016-07-01

    According to the sub clause 9.6.3 of the international standard IEC 60601-1-2005, medical electrical equipment must provide means of protection against hazardous hand- transmitted vibrations. Compliance of this sub clause is checked by using a vibration measurement instrument in accordance with ISO 5349-1-2001 standard. The present article describes the development of a vibration measurement instrument to perform vibration measurements tests in medical equipments.

  18. Comparing AFM cantilever stiffness measured using the thermal vibration and the improved thermal vibration methods with that of an SI traceable method based on MEMS

    Science.gov (United States)

    Brand, Uwe; Gao, Sai; Engl, Wolfgang; Sulzbach, Thomas; Stahl, Stefan W.; Milles, Lukas F.; Nesterov, Vladimir; Li, Zhi

    2017-03-01

    PTB has developed a new contact based method for the traceable calibration of the normal stiffness of AFM cantilevers in the range from 0.03 N m‑1 to 300 N m‑1 to the SI units based on micro-electro-mechanical system (MEMS) actuators. This method is evaluated by comparing the measured cantilever stiffness with that measured by PTB’s new primary nanonewton force facility and by PTB’s microforce measuring device. The MEMS system was used to calibrate the stiffness of cantilevers in two case studies. One set of cantilevers for applications in biophysics was calibrated using the well-known thermal vibration method and the second set of cantilevers was calibrated by a cantilever manufacturer who applied an improved thermal vibration method based on calibrated reference cantilevers for the cantilever stiffness calibration. The comparison revealed a stiffness deviation of  +7.7% for the cantilevers calibrated using the thermal vibration method and a deviation of  +6.9% for the stiffnesses of the cantilevers calibrated using the improved thermal vibration method.

  19. Analysis, Design and Testing of a Novel Quasi-Zero-Stiffness based Sensor System for Measurement of Absolute Vibration Motion

    CERN Document Server

    Wang, Yu

    2015-01-01

    This study presents the analysis and design of a novel quasi-zero-stiffness (QZS) based vibration sensor system for measuring absolute displacement of vibrating platforms/objects. The sensor system is constructed by using positive and negative-stiffness springs, which makes it possible to achieve an equivalent QZS and consequently to create a broadband vibration-free point for absolute displacement measurement in vibrating platforms. Theoretic analysis is conducted for the analysis and design of the influence of structure parameters on system measurement performance. A prototype is designed which can avoid the drawback of instability in existing QZS systems with negative stiffness, and the corresponding data-processing software is developed to fulfill time domain and frequency domain measurements simultaneously. Both simulation and experiment results verify the effectiveness of this novel sensor system.

  20. Smartphones as experimental tools to measure acoustical and mechanical properties of vibrating rods

    Science.gov (United States)

    González, Manuel Á.; González, Miguel Á.

    2016-07-01

    Modern smartphones have calculation and sensor capabilities that make them suitable for use as versatile and reliable measurement devices in simple teaching experiments. In this work a smartphone is used, together with low cost materials, in an experiment to measure the frequencies emitted by vibrating rods of different materials, shapes and lengths. The results obtained with the smartphone have been compared with theoretical calculations and the agreement is good. Alternatively, physics students can perform the experiment described here and use their results to determine the dependencies of the obtained frequencies on the rod characteristics. In this way they will also practice research methods that they will probably use in their professional life.

  1. Vibration parameter measurement using the temporal digital hologram sequence and windowed Fourier transform

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Real time digital recording and numerical reconstruction of a temporal digital hologram sequence have become feasible in recent years.They provide a new measurement method which enjoys the valuable advantages of being full-field,noncontact and high precision.In this paper,a combined method of temporal digital hologram sequence and windowed Fourier transform is proposed to measure the kinematic parameters of random vibration.A series of holograms are recorded by CCD camera and the original phase can be recon...

  2. Performance of a low-cost methane sensor for ambient concentration measurements in preliminary studies

    Science.gov (United States)

    Eugster, W.; Kling, G. W.

    2012-08-01

    Methane is the second most important greenhouse gas after CO2 and contributes to global warming. Its sources are not uniformly distributed across terrestrial and aquatic ecosystems, and most of the methane flux is expected to stem from hotspots which often occupy a very small fraction of the total landscape area. Continuous time-series measurements of CH4 concentrations can help identify and locate these methane hotspots. Newer, low-cost trace gas sensors such as the Figaro TGS 2600 can detect CH4 even at ambient concentrations. Hence, in this paper we tested this sensor under real-world conditions over Toolik Lake, Alaska, to determine its suitability for preliminary studies before placing more expensive and service-intensive equipment at a given locality. A reasonably good agreement with parallel measurements made using a Los Gatos Research FMA 100 methane analyzer was found after removal of the strong sensitivities for temperature and relative humidity. Correcting for this sensitivity increased the absolute accuracy required for in-depth studies, and the reproducibility between two TGS 2600 sensors run in parallel is very good. We conclude that the relative CH4 concentrations derived from such sensors are sufficient for preliminary investigations in the search of potential methane hotspots.

  3. Measurement of the ambient organic aerosol volatility distribution: application during the Finokalia Aerosol Measurement Experiment (FAME-2008

    Directory of Open Access Journals (Sweden)

    B. H. Lee

    2010-12-01

    Full Text Available A variable residence time thermodenuder (TD was combined with an Aerodyne Aerosol Mass Spectrometer (AMS and a Scanning Mobility Particle Sizer (SMPS to measure the volatility distribution of aged organic aerosol in the Eastern Mediterranean during the Finokalia Aerosol Measurement Experiment in May of 2008 (FAME-2008. A new method for the quantification of the organic aerosol volatility distribution was developed combining measurements of all three instruments together with an aerosol dynamics model.

    Challenges in the interpretation of ambient thermodenuder-AMS measurements include the potential resistances to mass transfer during particle evaporation, the effects of particle size on the evaporated mass fraction, the changes in the AMS collection efficiency and particle density as the particles evaporate partially in the TD, and finally potential losses inside the TD. Our proposed measurement and data analysis method accounts for all of these problems combining the AMS and SMPS measurements.

    The AMS collection efficiency of the aerosol that passed through the TD was found to be approximately 10% lower than the collection efficiency of the aerosol that passed through the bypass. The organic aerosol measured at Finokalia is approximately 2 or more orders of magnitude less volatile than fresh laboratory-generated monoterpene (α-pinene, β-pinene and limonene under low NOx conditions secondary organic aerosol. This low volatility is consistent with its highly oxygenated AMS mass spectrum. The results are found to be highly sensitive to the mass accommodation coefficient of the evaporating species. This analysis is based on the assumption that there were no significant reactions taking place inside the thermodenuder.

  4. Treatment of losses of ultrafine aerosol particles in long sampling tubes during ambient measurements

    Science.gov (United States)

    Kumar, Prashant; Fennell, Paul; Symonds, Jonathan; Britter, Rex

    Long sampling tubes are often required for particle measurements in street canyons. This may lead to significant losses of the number of ultrafine (those below 100 nm) particles within the sampling tubes. Inappropriate treatment of these losses may significantly change the measured particle number distributions (PND), because most of the ambient particles, by number, exist in the ultrafine size range. Based on the Reynolds number (Re) in the sampling tubes, most studies treat the particle losses using the Gormley and Kennedy laminar flow model (Gormley, P.G., Kennedy, M., 1949. Diffusion from a stream following through a cylinderical tube. Proceedings of Royal Irish Academy 52, 163-169.) or the Wells and Chamberlain turbulent flow model (Wells, A.C., Chamberlain, A.C., 1967. Transport of small particles to vertical surfaces. British Journal of Applied Physics 18, 1793-1799.). Our experiments used a particle spectrometer with various lengths (1.00, 5.47, 5.55, 8.90 and 13.40 m) of sampling tube to measure the PNDs in the 5-2738 nm range. Experiments were performed under different operating conditions to measure the particle losses through silicone rubber tubes of circular cross-section (7.85 mm internal diameter). Sources of particles included emissions from an idling diesel engine car in a street canyon, emissions from a burning candle and those from the generation of salt aerosols using a nebuliser in the laboratory. Results showed that losses for particles below ≈20 nm were important and were largest for the smallest size range (5-10 nm), but were modest for particles above ≈20 nm. In our experiments the laminar flow model did not reflect the observations for small Re. This may be due to the sampling tubes not being kept straight or other complications. In situ calibration or comparison appears to be required.

  5. Influence of ambient meteorology on the accuracy of radiation measurements: insights from field and laboratory experiments

    Science.gov (United States)

    Oswald, Sandro M.; Pietsch, Helga; Baumgartner, Dietmar J.; Rieder, Harald E.

    2016-04-01

    A precise knowledge of the surface energy budget, which includes the solar and terrestrial radiation fluxes, is needed to accurately characterize the global energy balance which is largely determining Earth's climate. To this aim national and global monitoring networks for surface radiative fluxes have been established in recent decades. The most prominent among these networks is the so-called Baseline Surface Radiation Network (BSRN) operating under the auspices of the World Climate Research Programme (WCRP) (Ohmura et al., 1998). National monitoring networks such as the Austrian RADiation Monitoring Network (ARAD), which has been established in 2010 by a consortium of the Central Agency of Meteorology and Geodynamics (ZAMG), the University of Graz, the University of Innsbruck, and the University of Natural Resources and Applied Sciences, Vienna (BOKU), orient themselves on BSRN standards (McArthur, 2005). ARAD comprises to date five sites (Wien Hohe Warte, Graz/University, Innsbruck/University, Kanzelhöhe Observatory and Sonnblick (which is also a BSRN site)) and aims to provide long-term monitoring of radiation budget components at highest accuracy and to capture the spatial patterns of radiation climate in Austria (Olefs et al., 2015). Given the accuracy requirement for the local monitoring of radiative fluxes instrument offsets, triggered by meteorological factors and/or instrumentation, pose a major challenge in radiation monitoring. Within this study we investigate effects of ambient meteorology on the accuracy of radiation measurements performed with pyranometers contained in various heating/ventilation systems (HV-systems), all of which used in regular operation within the ARAD network. We focus particularly on instrument offsets observed following precipitation events. To quantify pyranometer responses to precipitation we performed a series of controlled laboratory experiments as well as targeted field campaigns in 2015 and 2016. Our results indicate

  6. Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

    Directory of Open Access Journals (Sweden)

    R. C. Moffet

    2007-05-01

    Full Text Available Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS were carried out in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area – 2006 campaign (MCMA-2006 between 7–27 March, 2006. Biomass and organic carbon (OC particle types were found to dominate the accumulation mode both day and night. The concentrations of both organic carbon and biomass particles were roughly equal early in the morning, but biomass became the largest contributor to the accumulation mode mass from the late morning until early evening. The diurnal pattern can be attributed to aging and/or a change in meteorology. Fresh elemental carbon (EC particles were observed during rush hour. The majority of the EC particles were mixed with nitrate, sulfate, organic carbon and potassium. Submicron particles from industrial sources in the northeast were composed of an internal mixture of Pb, Zn, EC and Cl and peaked early in the morning. A unique nitrogen-containing organic (NOC particle type was observed, and is hypothesized to be from industrial emissions based on the temporal profile and back trajectory analysis. This study provides unique insights into the real-time changes in single particle mixing state as a function of size and time for aerosols in Mexico City. These new findings indicate that biomass burning and industrial operations make significant contributions to particles in Mexico City. These sources have received relatively little attention in previous intensive field campaigns.

  7. Measuring segmented primary mirror WFE in the presence of vibration and thermal drift on the light-weighted JWST

    Science.gov (United States)

    Whitman, Tony L.; Dziak, Kenneth J.; Wells, Conrad; Olczak, Gene

    2012-09-01

    The light-weighted design of the Optical Telescope Element (OTE) of the James Webb Telescope (JWST) leads to additional sensitivity to vibration from the ground - an important consideration to the measurement uncertainty of the wavefront error (WFE) in the primary mirror. Furthermore, segmentation of the primary mirror leads to rigid-body movements of segment areas in the WFE. The ground vibrations are minimized with modifications to the test facility, and by the architecture of the equipment supporting the load. Additional special test equipment (including strategically placed isolators, tunable mass dampers, and cryogenic magnetic dampers) mitigates the vibration and the response sensitivity before reaching the telescope. A multi-wavelength interferometer is designed and operated to accommodate the predicted residual vibration. Thermal drift also adds to the measurement variation. Test results of test equipment components, measurement theory, and finite element analysis combine to predict the test uncertainty in the future measurement of the primary mirror. The vibration input to the finite element model comes from accelerometer measurements of the facility with the environmental control pumps operating. One of the isolators have been built and tested to validate the dynamic performance. A preliminary model of the load support equipment and the OTE with the Integrated Science Instrument Module (ISIM) is complete. The performance of the add-on dampers have been established in previous applications. And operation of the multi-wavelength interferometer was demonstrated on a scaled hardware version of the JWST in an environment with vibration and thermal drift.

  8. Full-scale field measurements of wave kinematics and vortex shedding induced vibrations in slender structures

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, J.R.; Pedersen, B. [LIC Engineering (Denmark); Nielsen, K.G.; Bryndum, M.B. [Dansk Hydraulisk Inst., (Denmark)

    1999-07-01

    Vortex induced vibrations of pipes generated by high and steep waves in the crest zone have been investigated by full-scale field testing, An instrumented cylinder has been suspended from a platform bridge in the North Sea. Adjacent to it a newly developed acoustic system capable of measuring the three dimensional wave kinematics was placed. The kinematics were measured all the way up to the instantaneous water surface elevation, i.e. it included the wave crest. The paper presents time series of measured water surface elevations and orbital velocities at the instantaneous water surface together with the response of the instrumented pipe in a storm. The sea state was measured to H{sub s} {approx_equal} 6.4 m and T{sub z} = 8.4 sec. It was clearly seen that vortex shedding locking-on takes place in some of the rather high modes at the passage of large waves. Intermittent cross flow vortex induced vibrations of between 0.3 diameters up to 0.8 diameters were found in the 8th and the 4th mode respectively. The Reynolds numbers and KC numbers were up to 5 . 10{sup 5} and KC {approx} 250 respectively. (au)

  9. Full-field Measurement of Deformation and Vibration using Digital Image Correlation

    Directory of Open Access Journals (Sweden)

    Liang-Chih Chen

    2015-05-01

    Full Text Available The main intention of this study was to investigate the full-field measurement of de-formation and vibration using a program we developed for digital image correlation. Digital image correlation is a measuring method that can calculate the displacement of each point on an object by using recorded images. By capturing continuous images of the object in deformation or in motion, the displacements of feature points on the object can be tracked and used in calculations to determine the full-field deformation, strain and vibration of the object. We used the fast and simple algorithm in our program as the core, and conducted non-contact full-field displacement measurement by tracking feature points from images taken after motion. The measuring accuracy can be up to 0.1 pixel. Our experimental results show the technique to be very accurate and useful. We also applied this technique under conditions where an ordinary sensor could not be used.

  10. Water and organic nitrate detection in an AMS. Laboratory characterization and application to ambient measurements

    Energy Technology Data Exchange (ETDEWEB)

    Mensah, Amewu A.

    2011-08-12

    Atmospheric aerosols were studied by three different means. Laboratory experiments determined the relative ionization efficiency of water (RIE{sub H2O}) in an Aerodyne Aerosol Mass Spectrometers (AMS), simulation chamber experiments gave insight to the reaction products of biogenic volatile organic compounds (BVOC) oxidation products, and the findings were applied to two field campaign measurements at Cabauw, NL, in May 2008 and February 2009. Knowing the liquid water content of aerosol particles is vital for the assessment of their climate forcing potential. A value of 2 for RIE{sub H2O} was determined by studying oxalate salts with different amounts of crystal water. BVOCs contribute much more to the global budget of VOCs than anthropogenic ones but oxidation products in terms of secondary organic aerosol often correlate to anthropogenic tracers such as NO{sub x} from fossil fuel burning. In atmospheric simulation chamber experiments, organic nitrates from BVOC-NO{sub 3} oxidation showed higher vapor pressures than pure organic compounds produced in the same reactions. Organic nitrates comprised up to approx. 41 % of the particulate phase. A specific fragmentation ratio of nitrate (NO{sub 2}{sup +}/NO{sup +}) of 0.1 was found by high resolution AMS analysis differing strongly from the value of 0.4 known for the most abundant ambient NO{sub 3} specie (NH{sub 4}NO{sub 3}). Ambient average particulate mass loadings were 9.72 {mu}g/m{sup 3} dominated by organics (40 %) in 2008 and 5.62 {mu}g/m{sup 3} dominated by nitrate (42 %) in 2009. Data comparison to collocated instruments showed good agreement. Positive Matrix Factorization analysis of the particulate organic fraction distinguished semi and low volatile oxygenated organic aerosol (OOA) as well as hydrocarbon like organic aerosol (HOA) in both campaigns. An additional highly oxygenated OA with a mass spectrum very similar to fulvic acid was found in 2008. The average contribution of organic nitrate to the

  11. Analysis and measurement of cryocooler vibration%低温制冷机振动测试与分析

    Institute of Scientific and Technical Information of China (English)

    马坤全; 梅鲁生; 刘元琼; 王凯; 林伟; 黎军; 谢端; 雷海乐

    2013-01-01

    A method is proposed to measure the cryocooler vibration via the Doppler effect. Both axial and radial vibration of a typical G-M RDK-408S cryocooler is measured on the experimental setup. The experimental results indicate that the cryocooler has a working frequency of about 1 Hz. Compared with other directions, the axial direction vibration is the largest, which is about 30 μm, while the radial direction also has pulse vibration, equivalent to that of the axial vibration. The experimental results are much larger than the vibration requirements in inertial confinement fusion research and therefore vibration reduction methods must be adopted.%提出采用激光多普勒效应测量GM低温制冷机振动,并搭建实验台测试了RDK-408S型GM制冷机各方向的振动大小.实验结果表明,型号为RDK-408S的GM制冷机振动频率约为1 Hz,轴线方向的振动最大,约为30μm,x方向也存在脉冲振动,达到30 μm,都远远大于激光约束聚变研究中所需要的振动要求,必须采取具体措施进行减振或隔振.

  12. Laboratory Measurement of CO2(ν2) + O Temperature-Dependent Vibrational Energy Transfer

    Science.gov (United States)

    Dodd, J. A.; Hwang, E. S.; Simione, M.; Castle, K. J.

    2007-12-01

    The latest results from ongoing CO2(ν2)- O vibrational energy transfer measurements will be presented. The O + CO2 → O + CO2(ν2) vibrational uppumping process is a key contributor to 15-μm earthlimb emission and to upper atmospheric cooling in the 75-120 km altitude range. Model predictions of upper atmospheric density and temperature are sensitive to the assumed rate coefficient kO(ν2) for the relaxation of CO2(ν2) by O. Accurate accounting of kO(ν2) is necessary to derive the kinetic temperature and IR cooling rates from NASA TIMED/SABER radiometric data. In the present experiment, a 266-nm laser pulse photolyzes O3, producing O atoms and initiating a temperature jump, while transient diode laser absorption spectroscopy is used to monitor the time-dependent CO2(ν2) population. A vacuum-jacketed, liquid-nitrogen cooled reaction cell permits low-temperature measurements down to approximately 140 K. A second cell is used for high-temperature measurements up to about 550 K, spanning the range typically found in the mesosphere-lower thermosphere region. The results will be compared to the ab initio results of de Lara-Castells and coworkers, including the prediction that the O(3PJ=2) spin sublevel dominates the relaxation process.

  13. Condition Identification Based on Vibration Measurements for Free Spanning Submarine Pipelines

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Free spanning pipelines are suspended between two points on an uneven seafloor. The variations of structural conditions, such as the changes in soil property, flow velocity, axial force and span length etc., directly affect working performance of the whole submarine pipeline system. But until now few researches have focused on condition identification for free span (CIFS). A method to identify the operational conditions of free spanning submarine pipelines based on vibration measurements is proposed in this paper. Firstly, the ill-posedness of CIFS is analyzed in detail. Secondly, the framework for CIFS based on the nonlinear kernel discriminant analysis (KDA) is established. Thirdly, the internal structural characteristics of natural frequencies, normalized frequencies and frequency change ratios are studied. And then the condition feature vector for CIFS is extracted by use of the vibration measurements. Finally, the validity of the proposed approach is evaluated by a case study. The results demonstrate that the proposed approach can effectively identify each condition of free span when condition variation occurs even if under measurement noise. It is concluded that the proposed method is a promising tool for CIFS in real applications.

  14. Optical Tracking Measurement on Vortex Induced Vibration of Flexible Riser with Short-Length Buoyance Module

    Science.gov (United States)

    Fan, Dixia; Du, Honglin; Triantafyllou, Michael

    2016-11-01

    We address experimentally the vortex induced vibrations (VIV) of long flexible cylinders. We employ optical tracking, using an array of high speed cameras. Compared to strain gauges and accelerometers, this non-intrusive approach, allows direct measurement of the flexible cylinder displacement with far denser spatial distribution. The measurements reveal essential features of flexible cylinder VIV, including complex geometries such as cylinders containing short-length buoyancy modules, with module to cylinder diameter ratio of 1:3.2 and module to bare cylinder length ratio of 1:1. The experiments are conducted with aspect ratio of 170 and 3 different coverage ratios, of 100%, 50% and 20%. The measurements demonstrate bi-frequency response due to excitation from both buoyancy module and bare cylinder, at low Strouhal number, down to values of 0.08, and the generation of traveling wave patterns.

  15. High-speed system for FBG-based measurements of vibration and sound

    Science.gov (United States)

    Karabacak, Devrez M.; Ibrahim, Selwan K.; Koumans, Yorick; Meulblok, Bastiaan; Knoppers, Rik

    2016-05-01

    Fiber Bragg Gratings (FBGs) allow for optical detection of localized physical effects without the need to couple the light out and back into a fiber, enabling robust and multiplexed sensor systems. The need of combining wide bandwidth and high resolution for dynamic sensing applications, like acoustics and vibrations, has presented significant challenges for FBG-based solutions. Here, we present a novel FBG-based measurement system enabled by using high-speed and highprecision tunable laser-based optical interrogation scheme. Multiple levels of integrated wavelength referencing coupled with low-noise high-speed electronics allow for spectral feature tracking at a resolution of flat-sensitivity down to static pressures are demonstrated. The sensors are demonstrated to be customizable to application-specific requirements, and designed to be scalable to large quantity reproducible manufacturing. In contrast to interferometry-based solutions, the tunable swept-laser detection scheme in combination with strain-based FBG sensors provides a cost-effective system that allows for easy scaling of sensor counts per fiber with multiple fibers being simultaneously recorded. Finally, the integrated high accuracy triggering and hybrid measurement capabilities present the potential to monitor sounds and vibrations in a wide range of applications from seismic surveys to machine and structural monitoring applications in harsh environments.

  16. RISK ASSESSMENT BY STRUCTURAL ANALYSIS AND VIBRATION MEASUREMENT EQUIPMENT OPERATING AT OIL FACILITIES

    Directory of Open Access Journals (Sweden)

    Marius STAN

    2013-05-01

    Full Text Available Vibration analysis applications in operation is one of the diagnostic methods ofoperation of the facility. Analysis of these types of failures indicated the existence of specificfeatures prints and related equipment vibration spectra. Modeling and identification of theseparticular aspects in the spectrum of vibration machines help to control the operation of oilfacilities built safely.

  17. Design of a quasi-zero-stiffness based sensor system for the measurement of absolute vibration displacement of moving platforms

    Science.gov (United States)

    Jing, Xingjian; Wang, Yu; Li, Quankun; Sun, Xiuting

    2016-09-01

    This study presents the analysis and design of a novel sensor system for measuring the absolute vibration displacement of moving platforms based on the concept of quasi-zero-stiffness (QZS). The sensor system is constructed using positive- and negative-stiffness springs, which make it possible to achieve an equivalent QZS and consequently to create a broadband vibration-free point for absolute vibration displacement measurement in moving platforms. Theoretical analysis is conducted for the analysis and design of the influence of structure parameters on system measurement performance. A prototype is designed which can avoid the drawback of instability in existing QZS systems with negative stiffness, and corresponding data-processing software is developed to fulfill time domain measurements. Both the simulation and experimental results verify the effectiveness of this novel sensor system.

  18. Novel approach for non-invasive glucose sensing using vibrational contrast CD absorption measurements (Conference Presentation)

    Science.gov (United States)

    Yakovlev, Vladislav V.; Tovar, Carlos; Hokr, Brett; Petrov, Georgi I.

    2016-03-01

    Noninvasive glucose sensing is a Holy Grail of diabetes mellitus management. Unfortunately, despite a number of innovative concepts and a long history of continuous instrumental improvements, the problem remains largely unsolved. Here we propose and experimentally demonstrate the first successful implementation of a novel strategy based on vibrational overtone circular dichroism absorption measurements. Such an approach uses a short-wavelength infrared excitation (1000-2000 nm), which takes the advantage of lower light scattering and intrinsic chemical contrast provided by the chemical structure of D-glucose molecule. We model the propagation of circular polarized light in scattering medium using Monte Carlo simulations to show the feasibility of such approach in turbid medium and demonstrate the proof of principle using optical detection. We also investigate the possibility of using ultrasound detection through circular dichroism absorption measurements to achieve simple and sensitive glucose monitoring.

  19. Non-probabilistic stability reliability measure for active vibration control system with interval parameters

    Science.gov (United States)

    Li, Yunlong; Wang, Xiaojun; Wang, Lei; Fan, Weichao; Qiu, Zhiping

    2017-01-01

    A systematic non-probabilistic reliability analysis procedure for structural vibration active control system with unknown-but-bounded parameters is proposed. The state-space representation of active vibration control system with uncertain parameters is presented. Compared with the robust control theory, which is always over-conservative, the reliability-based analysis method is more suitable to deal with uncertain problem. Stability is the core of the closed-loop feedback control system design, so stability criterion is adopted to act as the limited state function for reliability analysis. The uncertain parameters without enough samples are modeled as interval variables. Interval perturbation method is employed to estimate the interval bounds of eigenvalues, which can be used to characterize the stability of the closed-loop active control system. Formulation of defining the reliability of active control system based on stability is discussed. A novel non-probabilistic reliability measurement index is discussed and used to determine the probability of the stability based on the area ratio. The feasibility and efficiency of the proposed method are demonstrated by two numerical examples.

  20. Fault Diagnosis for Rotating Machinery Using Vibration Measurement Deep Statistical Feature Learning.

    Science.gov (United States)

    Li, Chuan; Sánchez, René-Vinicio; Zurita, Grover; Cerrada, Mariela; Cabrera, Diego

    2016-06-17

    Fault diagnosis is important for the maintenance of rotating machinery. The detection of faults and fault patterns is a challenging part of machinery fault diagnosis. To tackle this problem, a model for deep statistical feature learning from vibration measurements of rotating machinery is presented in this paper. Vibration sensor signals collected from rotating mechanical systems are represented in the time, frequency, and time-frequency domains, each of which is then used to produce a statistical feature set. For learning statistical features, real-value Gaussian-Bernoulli restricted Boltzmann machines (GRBMs) are stacked to develop a Gaussian-Bernoulli deep Boltzmann machine (GDBM). The suggested approach is applied as a deep statistical feature learning tool for both gearbox and bearing systems. The fault classification performances in experiments using this approach are 95.17% for the gearbox, and 91.75% for the bearing system. The proposed approach is compared to such standard methods as a support vector machine, GRBM and a combination model. In experiments, the best fault classification rate was detected using the proposed model. The results show that deep learning with statistical feature extraction has an essential improvement potential for diagnosing rotating machinery faults.

  1. Integrating Oil Debris and Vibration Measurements for Intelligent Machine Health Monitoring. Degree awarded by Toledo Univ., May 2002

    Science.gov (United States)

    Dempsey, Paula J.

    2003-01-01

    A diagnostic tool for detecting damage to gears was developed. Two different measurement technologies, oil debris analysis and vibration were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. This diagnostic tool was developed and evaluated experimentally by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig. An oil debris sensor and the two vibration algorithms were adapted as the diagnostic tools. An inductance type oil debris sensor was selected for the oil analysis measurement technology. Gear damage data for this type of sensor was limited to data collected in the NASA Glenn test rigs. For this reason, this analysis included development of a parameter for detecting gear pitting damage using this type of sensor. The vibration data was used to calculate two previously available gear vibration diagnostic algorithms. The two vibration algorithms were selected based on their maturity and published success in detecting damage to gears. Oil debris and vibration features were then developed using fuzzy logic analysis techniques, then input into a multi sensor data fusion process. Results show combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spur gears. As a result of this research, this new diagnostic tool has significantly improved detection of gear damage in the NASA Glenn Spur Gear Fatigue Rigs. This research also resulted in several other findings that will improve the development of future health monitoring systems. Oil debris analysis was found to be more reliable than vibration analysis for detecting pitting fatigue failure of gears and is capable of indicating damage progression. Also, some vibration algorithms are as sensitive to operational effects as they

  2. Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

    Directory of Open Access Journals (Sweden)

    R. C. Moffet

    2008-08-01

    Full Text Available Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS were made in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area-2006 campaign (MCMA-2006. Results are presented for the period of 15–27 March 2006. The submicron size mode contained both fresh and aged biomass burning, aged organic carbon (OC mixed with nitrate and sulfate, elemental carbon (EC, nitrogen-organic carbon, industrial metal, and inorganic NaK inorganic particles. Overall, biomass burning and aged OC particle types comprised 40% and 31%, respectively, of the submicron mode. In contrast, the supermicron mode was dominated by inorganic NaK particle types (42% which represented a mixture of dry lake bed dust and industrial NaK emissions mixed with soot. Additionally, aluminosilicate dust, transition metals, OC, and biomass burning contributed to the supermicron particles. Early morning periods (2–6 a.m. showed high fractions of inorganic particles from industrial sources in the northeast, composed of internal mixtures of Pb, Zn, EC and Cl, representing up to 73% of the particles in the 0.2–3μm size range. A unique nitrogen-containing organic carbon (NOC particle type, peaking in the early morning hours, was hypothesized to be amines from local industrial emissions based on the time series profile and back trajectory analysis. A strong dependence on wind speed and direction was observed in the single particle types that were present during different times of the day. The early morning (3:30–10 a.m. showed the greatest contributions from industrial emissions. During mid to late mornings (7–11 a.m., weak northerly winds were observed along with the most highly aged particles. Stronger winds from the south picked up in the late morning (after 11 a.m., resulting in a decrease in the concentrations of the major aged particle types and an increase in the number fraction of fresh

  3. Laser vibrometry vibration measurements on vehicle cabins in running conditions: helicopter mock-up application

    Science.gov (United States)

    Revel, Gian Marco; Castellini, Paolo; Chiariotti, Paolo; Tomasini, Enrico Primo; Cenedese, Fausto; Perazzolo, Alessandro

    2011-10-01

    The present work deals with the analysis of problems and potentials of laser vibrometer measurements inside vehicle cabins in running conditions, with particular reference to helicopters where interior vibro-acoustic issues are very important. This paper describes the results of a systematic measurement campaign performed on an Agusta A109MKII mock-up. The aim is to evaluate the applicability of scanning laser Doppler vibrometer (SLDV) for tests in simulated flying conditions and to understand how performances of the technique are affected when the laser head is placed inside the cabin, thus being subjected to interfering inputs. First a brief description of the performed test cases and the used measuring set-ups are given. Comparative tests between the SLDV and accelerometers are presented, analyzing the achievable performances for the specific application. Results obtained measuring with the SLDV placed inside the helicopter cabin during operative excitation conditions are compared with those performed with the laser lying outside the mock-up, these last being considered as ``reference measurements.'' Finally, in order to give an estimate of the uncertainty level on measured signals, a study linking the admitted percentage of noise content on vibrometer signals due to laser head vibration levels will be introduced.

  4. Measurements of the impact of atmospheric aging on physical and optical properties of ambient black carbon particles in Los Angeles

    Science.gov (United States)

    Krasowsky, Trevor S.; McMeeking, Gavin R.; Wang, Dongbin; Sioutas, Constantinos; Ban-Weiss, George A.

    2016-10-01

    Understanding how physical and optical properties of atmospheric black carbon (BC) particles vary in time and space is critical for reducing uncertainty in climate forcing estimates from ambient BC. In this study, ambient BC was measured in Rubidoux, California, approximately 90 km (55 miles) downwind of downtown Los Angeles. Collocated NOx and NOy measurements were used to estimate the photochemical age of the sampled air. Sampling was conducted throughout entire days between February 3, 2015 and March 12, 2015 to capture diurnal and daily variations in ambient BC. Both ambient and thermally-denuded air was sampled in 15-min cycles to compare the physical and optical properties of coated versus uncoated BC particles. Physical properties of individual BC particles including mass and coating thickness were measured using a Single-Particle Soot Photometer (SP2), and BC optical properties were measured using a Photoacoustic Extinctiometer (PAX) at 870 nm. The mean BC mass concentration (±standard deviation) for the campaign was 0.12 ± 0.08 μg m-3. BC mass concentrations were higher on weekdays than weekends, though only differences between 11:00 and 17:00 h were statistically distinguishable. The fraction of total BC particles that were thickly-coated (f) was found to be relatively low, with a mean of 0.05 ± 0.02 over the campaign. Values for f peaked in the afternoon when photochemical pollutant concentrations are also generally at a maximum. Further, f at 15:00-16:00 h was found to be statistically higher on weekends than weekdays, potentially due to a higher relative amount of ambient SOA to BC on weekends versus weekdays, which would enhance SOA coating of primary BC particles as they age during transport from the western Los Angeles basin to our sampling site on weekends. Differences at other hours during the photochemically active period of the day (10:00-14:00 h) were not statistically different although the weekend values were systematically higher

  5. Soot measurements for diesel and biodiesel spray combustion under high temperature highly diluted ambient conditions

    KAUST Repository

    Zhang, Ji

    2014-11-01

    This paper presents the soot temperature and KL factor for biodiesel, namely fatty acid methyl ester (FAME) and diesel fuel combustion in a constant volume chamber using a two-color technique. The KL factor is a parameter for soot concentration, where K is an absorption coefficient and proportional to the number density of soot particles, L is the geometric thickness of the flame along the optical detection axis, and KL factor is proportional to soot volume fraction. The main objective is to explore a combustion regime called high-temperature and highly-diluted combustion (HTHDC) and compare it with the conventional and low-temperature combustion (LTC) modes. The three different combustion regimes are implemented under different ambient temperatures (800 K, 1000 K, and 1400 K) and ambient oxygen concentrations (10%, 15%, and 21%). Results are presented in terms of soot temperature and KL factor images, time-resolved pixel-averaged soot temperature, KL factor, and spatially integrated KL factor over the soot area. The time-averaged results for these three regimes are compared for both diesel and biodiesel fuels. Results show complex combined effects of the ambient temperature and oxygen concentration, and that two-color temperature for the HTHDC mode at the 10% oxygen level can actually be lower than the conventional mode. Increasing ambient oxygen and temperature increases soot temperature. Diesel fuel results in higher soot temperature than biodiesel for all three regimes. Results also show that diesel and biodiesel fuels have very different burning and sooting behavior under the three different combustion regimes. For diesel fuel, the HTHDC regime offers better results in terms of lower soot than the conventional and LTC regimes, and the 10% O2, 1400 K ambient condition shows the lowest soot concentration while maintaining a moderate two-color temperature. For biodiesel, the 15% O2, 800 K ambient condition shows some advantages in terms of reducing soot

  6. Two-receiver measurements of phase velocity: cross-validation of ambient-noise and earthquake-based observations

    Science.gov (United States)

    Kästle, Emanuel D.; Soomro, Riaz; Weemstra, Cornelis; Boschi, Lapo; Meier, Thomas

    2016-12-01

    Phase velocities derived from ambient-noise cross-correlation are compared with phase velocities calculated from cross-correlations of waveform recordings of teleseismic earthquakes whose epicentres are approximately on the station-station great circle. The comparison is conducted both for Rayleigh and Love waves using over 1000 station pairs in central Europe. We describe in detail our signal-processing method which allows for automated processing of large amounts of data. Ambient-noise data are collected in the 5-80 s period range, whereas teleseismic data are available between about 8 and 250 s, resulting in a broad common period range between 8 and 80 s. At intermediate periods around 30 s and for shorter interstation distances, phase velocities measured from ambient noise are on average between 0.5 per cent and 1.5 per cent lower than those observed via the earthquake-based method. This discrepancy is small compared to typical phase-velocity heterogeneities (10 per cent peak-to-peak or more) observed in this period range.We nevertheless conduct a suite of synthetic tests to evaluate whether known biases in ambient-noise cross-correlation measurements could account for this discrepancy; we specifically evaluate the effects of heterogeneities in source distribution, of azimuthal anisotropy in surface-wave velocity and of the presence of near-field, rather than far-field only, sources of seismic noise. We find that these effects can be quite important comparing individual station pairs. The systematic discrepancy is presumably due to a combination of factors, related to differences in sensitivity of earthquake versus noise data to lateral heterogeneity. The data sets from both methods are used to create some preliminary tomographic maps that are characterized by velocity heterogeneities of similar amplitude and pattern, confirming the overall agreement between the two measurement methods.

  7. Utilization of old vibro-acoustic measuring equipment to grasp basic concepts of vibration measurements

    DEFF Research Database (Denmark)

    Darula, Radoslav

    2013-01-01

    The aim of the paper is to show that even old vibro-acoustic (analog) equipment can be used as a very suitable teaching equipment to grasp basic principles of measurements in an era, when measurement equipments are more-or-less treated as ‘black-boxes’, i.e. the user cannot see directly how...

  8. Low-cost optical data acquisition system for blade vibration measurement

    Science.gov (United States)

    Posta, Stephen J.

    1988-01-01

    A low cost optical data acquisition system was designed to measure deflection of vibrating rotor blade tips. The basic principle of the new design is to record raw data, which is a set of blade arrival times, in memory and to perform all processing by software following a run. This approach yields a simple and inexpensive system with the least possible hardware. Functional elements of the system were breadboarded and operated satisfactorily during rotor simulations on the bench, and during a data collection run with a two-bladed rotor in the Lewis Research Center Spin Rig. Software was written to demonstrate the sorting and processing of data stored in the system control computer, after retrieval from the data acquisition system. The demonstration produced an accurate graphical display of deflection versus time.

  9. A low-cost optical data acquisition system for vibration measurement

    Science.gov (United States)

    Posta, S. J.; Brown, G. V.

    1986-01-01

    A low cost optical data acquisition system was designed to measure deflection of vibrating rotor blade tips. The basic principle of the new design is to record raw data, which is a set of blade arrival times, in memory and to perform all processing by software following a run. This approach yields a simple and inexpensive system with the least possible hardware. Functional elements of the system were breadboarded and operated satisfactorily during rotor simulations on the bench, and during a data collection run with a two-bladed rotor in the Lewis Research Center Spin Rig. Software was written to demonstrate the sorting and processing of data stored in the system control computer, after retrieval from the data acquisition system. The demonstration produced an accurate graphical display of deflection versus time.

  10. Comparison of DIC and LDV for practical vibration and modal measurements

    Science.gov (United States)

    Reu, Phillip L.; Rohe, Daniel P.; Jacobs, Laura D.

    2017-03-01

    We compare laser Doppler vibrometry (LDV) and digital image correlation (DIC) for use in full-field vibration and modal testing. This was done using a simultaneously measured 3D displacement field on a flat 7-in. corner-supported metal plate using pseudorandom excitation via a shaker. We complete a detailed comparison between the techniques and discuss the pros and cons of each. The results show that either technique can be used for quantifying the modal information with the LDV providing better out-of-plane displacement resolution and equivalent in-plane resolution. The strain calculation is considered better in the DIC approach due to the direct tie to the surface displacements. While the LDV does not lose its place as the gold standard for modal testing, DIC has introduced a new and competitive approach that will have significant advantages in certain testing regimes.

  11. Basic Study on Estimating Water Stress of a Plant Using Vibration Measurement of Leaf

    Science.gov (United States)

    Sano, Motoaki; Sugimoto, Tsuneyoshi; Hosoya, Hiroshi; Ohaba, Motoyoshi; Shibusawa, Sakae

    2013-07-01

    A new noninvasive method for estimating the water stress of a plant was proposed. In order to investigate this method, we first examined the characteristic frequency of an individual leaf picked from the plant, and obtained the result that its characteristic frequency decreased in proportion to the reduction in the water content of the leaf. Next, we applied this method to a leaf on a branch and confirmed the same tendency when the water stress was increased by stopping the water supply of a plant cultured in water. From these results, it was suggested that the water stress of the plant could be estimated from the vibration measurement of the leaf. Lastly, the relationship between the water potential of the leaf and its elastic constant was discussed with the soil-plant-atmosphere-continuum model (SPAC model), and Young's modulus of a tomato leaf was roughly estimated.

  12. Detailed characterization of a Comparative Reactivity Method (CRM) instrument for ambient OH reactivity measurements: experiments vs. modeling

    Science.gov (United States)

    Michoud, Vincent; Locoge, Nadine; Dusanter, Sébastien

    2015-04-01

    The Hydroxyl radical (OH) is the main daytime oxidant in the troposphere, leading to the oxidation of Volatile Organic Compounds (VOCs) and the formation of harmful pollutants such as ozone (O3) and Secondary Organic Aerosols (SOA). While OH plays a key role in tropospheric chemistry, recent studies have highlighted that there are still uncertainties associated with the OH budget, i.e the identification of sources and sinks and the quantification of production and loss rates of this radical. It has been demonstrated that ambient measurements of the total OH loss rate (also called total OH reactivity) can be used to identify and reduce these uncertainties. In this context, the Comparative Reactivity Method (CRM), developed by Sinha et al. (ACP, 2008), is a promising technique to measure total OH reactivity in ambient air and has already been used during several field campaigns. This technique relies on monitoring competitive reactions of OH with ambient trace gases and a reference compound (pyrrole) in a sampling reactor to derive ambient OH reactivity. However, this technique requires a complex data processing chain that has yet to be carefully investigated in the laboratory. In this study, we present a detailed characterization of a CRM instrument developed at Mines Douai, France. Experiments have been performed to investigate the dependence of the CRM response on humidity, ambient NOx levels, and the pyrrole-to-OH ratio inside the sampling reactor. Box modelling of the chemistry occurring in the reactor has also been performed to assess our theoretical understanding of the CRM measurement. This work shows that the CRM response is sensitive to both humidity and NOx, which can be accounted for during data processing using parameterizations depending on the pyrrole-to-OH ratio. The agreement observed between laboratory studies and model results suggests a good understanding of the chemistry occurring in the sampling reactor and gives confidence in the CRM

  13. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2015-03-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

  14. Application of Ambient Analysis Techniques for the Estimation of Electromechanical Oscillations from Measured PMU Data in Four Different Power Systems

    DEFF Research Database (Denmark)

    Vanfretti, Luigi; Dosiek, Luke; Pierre, John W.

    2011-01-01

    The application of advanced signal processing techniques to power system measurement data for the estimation of dynamic properties has been a research subject for over two decades. Several techniques have been applied to transient (or ringdown) data, ambient data, and to probing data. Some...... of these methodologies have been included in off-line analysis software, and are now being incorporated into software tools used in control rooms for monitoring the near real-time behavior of power system dynamics. In this paper we illustrate the practical application of some ambient analysis methods......-synchronized Frequency Disturbance Recorder (FDR) data from Nigeria. It is shown that available signal processing tools are readily applicable for analysis of different power systems, regardless of their specific dynamic characteristics. The discussions and results in this paper are of value to power system operators...

  15. Ice berg cracking events as identified from underwater ambient noise measurements in the shallow waters of Ny-Alesund, Arctic

    Science.gov (United States)

    Ashokan, M.; Latha, G.; Thirunavukkarasu, A.; Raguraman, G.; Venkatesan, R.

    2016-06-01

    This paper presents the work carried out on the analysis of preliminary underwater ambient noise measurements in the shallow waters of Kongsfjorden fjord, Arctic in the summer season, in which the ice berg cracking noise is identified. In the summer period, the melting of ice cover is fast and hence the ice bergs are free to move and float in the ocean. Underwater ambient noise has been acquired in the Kongsfjorden fjord, Arctic sea on 19th July 2015 at 5 m water depth, where the ocean depth is 50 m. Due to the tensile cracks at the surface of the sea ice by thermal expansion, ice berg calving and bobbing occurred near the experiment site. Analysis of power spectra shows that ice berg calving noise falls in the frequency band 100 Hz-500 Hz and the ice berg bobbing noise falls in the frequency band 200 Hz-400 Hz.

  16. Effect Of Vibration On Occupant Driving Performances Measured By Simulated Driving

    Directory of Open Access Journals (Sweden)

    Amzar Azizan

    2015-08-01

    Full Text Available Although the performance of vehicle driver has been well investigated in many types of environments however drowsy driving caused by vibration has received far less attention. Experiment procedures comprised of two 10-minutes simulated driving sessions in no-vibration condition and with-vibration condition. In with-vibration condition volunteers were exposed to a Gaussian random vibration with 1-15 Hz frequency bandwidth at 0.2 ms-2 r.m.s. for 30-minutes. A deviation in lane position and vehicle speed were recorded and analyzed. Volunteers have also rated their subjective drowsiness by giving score using Karolinska Sleepiness Scale KSS every 5-minutes interval. Strong evidence of driving impairment following 30-minutes exposure to vibration were found significant in all volunteers p 0.05.

  17. Vibrational relaxation of the bending mode of shock-heated CO2 by laser-absorption measurements.

    Science.gov (United States)

    Eckstrom, D. J.; Bershader, D.

    1972-01-01

    Study of the vibrational relaxation characteristics of shock-heated CO2 using a tuned CO2 laser absorption technique. Absorption-coefficient histories were obtained for a single rotational state in each of the -10 0- and -02 0- levels over the temperature range from 500 to 2000 K, and for 21 rotational states of the -10 0- level at 1000 K. These histories have been combined with translational-rotational temperature histories based on interferometer measurements to calculate vibrational relaxation times for the bending mode. The results verify the mutual equilibrium of the bending and symmetric-stretch modes due to Fermi resonance. The bending mode relaxation times are approximately 10% shorter than predicted from interferometer results using the ratio of specific heats. Furthermore, relaxation times based on measurements of different rotational states at 1000 K show a variation with quantum number J, indicating a possible rotational nonequilibrium during the vibration relaxation process.

  18. A vibrating wire susceptometer with a special electronic control for fast measurements at high temperatures

    Science.gov (United States)

    Asti, G.; Solzi, M.; Podini, P.; Pellicelli, R.; Morbarigazzi, M.

    2002-04-01

    The measurement of the temperature behaviour of initial magnetic susceptibility is a powerful method for the thermomagnetic analysis of ferromagnetic materials. However, its application to nanostructured materials with technical relevance, particularly in the case of metastable systems, is made difficult by several conflicting conditions: the necessity to employ low magnetic fields, the required high sensitivity and the need for rapid scans in the high-temperature range. The vibrating wire susceptometer, an instrument belonging to the class of alternating gradient force magnetometers, has, in theory, the right characteristics to make such measurements. However, management of the instrument when carrying out rapid scans is intrinsically complex and requires a special electronic controller described here in detail. A combination of two phase-locked loop blocks is needed to provide the correct phase shift to ensure the locking of the resonance frequency while the instrument is working. A new measurement procedure that keeps the oscillation amplitude constant has also been implemented and it has proved to be very useful for rapid overview of the sample magnetic properties. The limitations of the controller performance due to the presence of noise are discussed. Extensive test measurements were carried out and analysed.

  19. Evaluation of the use of bioethanol fuelled buses based on ambient air pollution screening and on-road measurements.

    Science.gov (United States)

    López-Aparicio, S; Hak, C

    2013-05-01

    Mitigation measures to reduce greenhouse gas emissions may have adverse effects on urban air quality and human exposure to harmful pollutants. The use of bioethanol fuelled vehicles is increasing worldwide and may create new undesired pollution effects. Different measurement campaigns were performed in a pilot study to contribute to the understanding of the consequences associated with the use of bioethanol blended fuel (E95) on a series of pollutants. Ambient screening measurements of NO2, O3, acetic acid, formaldehyde and acetaldehyde were performed at different urban locations, exposed and not exposed to the circulation of bioethanol buses. In addition, volatile organic compounds were measured at the exhaust pipe of a bioethanol fuelled bus, both under idling conditions (carbonyls; DNPH cartridge) and under on-road driving conditions applying online monitoring (PTR-TOF). Higher ambient acetaldehyde values were measured at locations exposed to bioethanol fuelled buses than at locations not exposed, and very high acetaldehyde and acetic acid values were measured from the exhaust pipe during driving conditions (acetaldehyde>150 ppm; acetic acid ≈ 20-30 ppm) and modelled at close distance to the bioethanol bus. Human exposure to high concentration of acetaldehyde is expected, and it may involve a significantly increased chance in developing cancer. The high concentration of acetic acid will involve odour annoyance and significant material degradation or corrosion.

  20. Prevalence of Hand-transmitted Vibration Exposure among Grass-cutting Workers using Objective and Subjective Measures

    Science.gov (United States)

    Azmir, N. A.; Yahya, M. N.

    2017-01-01

    Extended exposure to hand-transmitted vibration from vibrating machine is associated with an increased occurrence of symptoms of occupational disease related to hand disorder. The present case study is to determine the prevalence and correlation of significant subjective as well as objective variables that induce to hand arm vibration syndrome (HAVS) among hand-held grass-cutting workers in Malaysia. Thus, recommendations are made for grass-cutting workers and grass maintenance service management based on findings. A cross sectional study using adopted subjective Hand Arm Vibration Exposure Risk Assessment (HAVERA) questionnaire from Vibration Injury Network on hand disorder signs and symptoms was distributed to a sample of one hundred and sixty eight male workers from grass and turf maintenance industry that use vibrating machine as part of their work. For objective measure, hand-transmitted vibration measurement was collected on site during operation by the following ISO 5349-1, 2001. Two groups were identified in this research comprising of high exposure group and low-moderate exposure group. Workers also gave information about their personal identification, social history, workers’ health, occupational history and machine safety inspection. There was positive HAVS symptoms relationship between the low-moderate exposure group and high exposure group among hand-held grass-cutting workers. The prevalence ratio (PR) was considered high for experiencing white colour change at fingers and fingers go numb which are 3.63 (1.41 to 9.39) and 4.24 (2.18 to 8.27), respectively. The estimated daily vibration exposure, A(8) differs between 2.1 to 20.7 ms-2 for right hand while 2.7 to 29.1 ms-2 for left hand. The subjects claimed that the feel of numbness at left hand is much stronger compared to right hand. The results suggest that HAVS is diagnosed in Malaysia especially in agriculture sector. The A(8) indicates that the exposure value is more than exposure limit value

  1. Characterisation of an inlet pre-injector laser induced fluorescence instrument for the measurement of ambient hydroxyl radicals

    Directory of Open Access Journals (Sweden)

    A. Novelli

    2014-01-01

    Full Text Available Ambient measurements of hydroxyl radicals (OH are challenging due to a high reactivity and consequently low concentration. The importance of OH as an atmospheric oxidant has resulted in a sustained effort leading to the development of a number of analytical techniques. Recent work has indicated that the laser-induced fluorescence of the OH molecules method based on the fluorescence assay by gas expansion technique (LIF-FAGE for the measurement of atmospheric OH in some environments may be influenced by artificial OH generated within the instrument, and a chemical method to remove this interference was implemented in a LIF-FAGE system by Mao et al. (2012. We have applied this method to our LIF-FAGE HORUS (HydrOxyl Radical Measurement Unit based on fluorescence Spectroscopy system, and developed and deployed an inlet pre-injector (IPI to determine the chemical zero level in the instrument via scavenging the ambient OH radical. We describe and characterise this technique in addition to its application at field sites in forested locations in Finland, Spain, and Germany. Ambient measurements show that OH generated within the HORUS instrument is a non-negligible fraction of the total OH signal, which can comprise 30% to 80% during the day and 60% to 100% during the night. The contribution of the background OH varied greatly between measurement sites and was likely related to the type and concentration of volatile organic compounds (VOCs present at each particular location. Two inter-comparisons in contrasting environments between the HORUS instrument and two different chemical ionisation mass spectrometers (CIMS are described to demonstrate the efficacy of the inlet-pre-injector and the necessity of the chemical zeroing method in such environments.

  2. Group and phase velocities from deterministic and ambient sources measured during the AlpArray-EASI experiment

    Science.gov (United States)

    Kolínský, Petr; Zigone, Dimitri; Fuchs, Florian; Bianchi, Irene; Qorbani, Ehsan; Apoloner, Maria-Theresia; Bokelmann, Götz; AlpArray-EASI Working Group

    2016-04-01

    The Eastern Alpine Seismic Investigation (EASI) was a complementary experiment to the AlpArray project. EASI was composed of 55 broadband seismic stations deployed in a winding swath of 540 km length along longitude 13.350 E from the Czech-German border to the Adriatic Sea. Average north-south inter-station distance was 10 km, the distance of each station to either side of the central line was 6 km. Such a dense linear network allows for surface wave dispersion measurements by both deterministic and ambient noise sources along the same paths. During the experiment (July 2014 - August 2015), three earthquakes ML = 2.6, 2.9 and 4.2 occurred in Austria and Northern Italy only several kilometers off the swath. We measure Rayleigh and Love wave group velocities between the source and a single station for the recorded earthquakes, as well as phase velocities between selected pairs of stations using the standard two-station method. We also calculate cross-correlations of ambient noise between selected pairs of stations and we determine the corresponding group velocity dispersion curves. We propose a comparison of phase velocities between two stations measured from earthquakes with group velocities obtained from cross-correlations for the same station pairs. We also compare group velocities measured at single station using earthquakes, which occurred along the swath, with group velocities measured from cross-correlations. That way we analyze velocities of both deterministic and ambient noise reconstructed surface waves propagating along the same path. We invert the resulting dispersion curves for 1D shear wave velocity profiles with depth and we compile a quasi-2D velocity model along the EASI swath.

  3. EMRP JRP MetNH3: Towards a Consistent Metrological Infrastructure for Ammonia Measurements in Ambient Air

    Science.gov (United States)

    Leuenberger, Daiana; Balslev-Harder, David; Braban, Christine F.; Ebert, Volker; Ferracci, Valerio; Gieseking, Bjoern; Hieta, Tuomas; Martin, Nicholas A.; Pascale, Céline; Pogány, Andrea; Tiebe, Carlo; Twigg, Marsailidh M.; Vaittinen, Olavi; van Wijk, Janneke; Wirtz, Klaus; Niederhauser, Bernhard

    2016-04-01

    Measuring ammonia in ambient air is a sensitive and priority issue due to its harmful effects on human health and ecosystems. In addition to its acidifying effect on natural waters and soils and to the additional nitrogen input to ecosystems, ammonia is an important precursor for secondary aerosol formation in the atmosphere. The European Directive 2001/81/EC on "National Emission Ceilings for Certain Atmospheric Pollutants (NEC)" regulates ammonia emissions in the member states. However, there is a lack of regulation regarding certified reference material (CRM), applicable analytical methods, measurement uncertainty, quality assurance and quality control (QC/QA) procedures as well as in the infrastructure to attain metrological traceability. As shown in a key comparison in 2007, there are even discrepancies between reference materials provided by European National Metrology Institutes (NMIs) at amount fraction levels up to three orders of magnitude higher than ambient air levels. MetNH3 (Metrology for ammonia in ambient air), a three-year project that started in June 2014 in the framework of the European Metrology Research Programme (EMRP), aims to reduce the gap between requirements set by the European emission regulations and state-of-the-art of analytical methods and reference materials. The overarching objective of the JRP is to achieve metrological traceability for ammonia measurements in ambient air from primary certified reference material CRM and instrumental standards to the field level. This requires the successful completion of the three main goals, which have been assigned to three technical work packages: To develop improved reference gas mixtures by static and dynamic gravimetric generation methods Realisation and characterisation of traceable preparative calibration standards (in pressurised cylinders as well as mobile generators) of ammonia amount fractions similar to those in ambient air based on existing methods for other reactive analytes. The

  4. Solvation Reaction Field at the Interface Measured by Vibrational Sum Frequency Generation Spectroscopy.

    Science.gov (United States)

    Sorenson, Shayne A; Patrow, Joel G; Dawlaty, Jahan M

    2017-02-15

    Interfacial electric fields are important in several areas of chemistry, materials sciences, and device physics. However, they are poorly understood, partly because they are difficult to measure directly and model accurately. We present both a spectroscopic experimental investigation and a theoretical model for the interfacial field at the junction of a conductor and a dielectric. First, we present vibrational sum frequency generation (VSFG) results of the nitrile (CN) stretch of 4-mercaptobenzonitrile (4-MBN) covalently attached to a gold surface and in contact with a variety of liquid dielectrics. It is found that the CN stretch frequency red-shifts with increasing dielectric constant. Second, we build a model in direct analogy to the well-known Onsager reaction field theory, which has been successful in predicting vibrational frequency shifts in bulk dielectric media. Clearly, due to the asymmetric environment, with metal on one side and a dielectric on the other, the bulk Onsager model is not applicable at the interface. To address this, we apply the Onsager model to the interface accounting for the asymmetry. The model successfully explains the red-shift of the CN stretch as a function of the dielectric constant and is used to estimate the reaction field near the interface. We show the similarities and differences between the conventional bulk Onsager model and the interfacial reaction field model. In particular, the model emphasizes the importance of the metal as part of the solvation environment of the tethered molecules. We anticipate that our work will be of fundamental value to understand the crucial and often elusive electric fields at interfaces.

  5. A Novel Vibrating Finger Viscometer for High-Temperature Measurements in Liquid Metals and Alloys

    Science.gov (United States)

    Dubberstein, T.; Schürmann, M.; Chaves, H.; Heller, H.-P.; Aneziris, C. G.

    2016-10-01

    A novel vibrating finger viscometer for high-temperature measurement in liquid metals and alloys up to 1823 K was constructed. The dynamic viscosity (η ) of the liquid fluid is measured as a product of (ρ \\cdot η )^{0.5} and the relative change of the field coil input for a constant amplitude recording at the resonant frequency of the oscillator. The viscometer was calibrated at 298 K using reference silicon oils with varying kinematic viscosities (ν ), (0.79 to 200)× 10^{-6} m2\\cdot s^{-1}. In the present study, the viscosity of liquid gold (99.99 % Au), silver (99.9 % Ag), and tin (99.9 % Sn) was measured. The viscosities expressed as an Arrhenius function of temperature are: {for Au:}quad quad ln η= & {} -0.1990+2669/T {for Ag:} quad quad ln η= & {} -0.4631+2089/T {for Sn:} quad quad ln η= & {} -0.5472+671/T The viscosity values are consistent within the range of available literature data.

  6. Direct measurement of additional Ar-H2O vibration-rotation-tunneling bands in the millimeter-submillimeter range

    Science.gov (United States)

    Zou, Luyao; Widicus Weaver, Susanna L.

    2016-06-01

    Three new weak bands of the Ar-H2O vibration-rotation-tunneling spectrum have been measured in the millimeter wavelength range. These bands were predicted from combination differences based on previously measured bands in the submillimeter region. Two previously reported submillimeter bands were also remeasured with higher frequency resolution. These new measurements allow us to obtain accurate information on the Coriolis interaction between the 101 and 110 states. Here we report these results and the associated improved molecular constants.

  7. Effects of ambient air pollution on functional status in patients with chronic congestive heart failure: a repeated-measures study

    Directory of Open Access Journals (Sweden)

    Phillips Russell S

    2007-09-01

    Full Text Available Abstract Background Studies using administrative data report a positive association between ambient air pollution and the risk of hospitalization for congestive heart failure (HF. Circulating levels of B-type natriuretic peptide (BNP are directly associated with cardiac hemodynamics and symptom severity in patients with HF and, therefore, serves as a marker of functional status. We tested the hypothesis that BNP levels would be positively associated with short-term changes in ambient pollution levels among 28 patients with chronic stable HF and impaired systolic function. Methods BNP was measured in whole blood at 0, 6, and 12 weeks. We used linear mixed models to evaluate the association between fine particulate matter (PM2.5, carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, and black carbon and log(BNP. Lags of 0 to 3 days were considered in separate models. We calculated the intraclass correlation coefficient and within-subject coefficient of variation as measures of reproducibility. Results We found no association between any pollutant and measures of BNP at any lag. For example, a 10 μg/m3 increase in PM2.5 was associated with a 0.8% (95% CI: -16.4, 21.5; p = 0.94 increase in BNP on the same day. The within-subject coefficient of variation was 45% on the natural scale and 9% on the log scale. Conclusion These results suggest that serial BNP measurements are unlikely to be useful in a longitudinal study of air pollution-related acute health effects. The magnitude of expected ambient air pollution health effects appears small in relation to the considerable within-person variability in BNP levels in this population.

  8. 振动测量误差影响因素探析%Vibration Measurement Error Inlfuence Factors Analysis

    Institute of Scientific and Technical Information of China (English)

    鲍耀翔; 陈武

    2016-01-01

    随着科学技术的进步,在具体的操作中,对于振动测量误差的重视度也在逐渐提升,为了满足振动测量的精度要求,避免误差的出现,本文通过振动测量方法对振动测量误差的影响因素以及改进的方式进行分析,希望能够避免误差,提高精度。%Along with the progress of science and technology, in the concrete operation, the vibration stress measurement error are also gradually improve, in order to satisfy the requirement of the vibration measuring precision, avoid the occurrence of error. So, in this article, through the pen name of vibration measurement method, the vibration measurement error analysis of the influencing factors and improve way hoped to avoid error, improve accuracy.

  9. Infrared transient grating measurements of the dynamics of hydrogen local mode vibrations in amorphous silicon-germanium

    NARCIS (Netherlands)

    Jobson, K.W.; Wells, J.P.R.; Schropp, R.E.I.; Vinh, N.Q.; Dijkhuis, J.I.

    2008-01-01

    We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si–H and Ge–H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe:H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to th

  10. Infrared transient grating measurements of the dynamics of hydrogen local mode vibrations in amorphous silicon-germanium

    NARCIS (Netherlands)

    Jobson, K. W.; Wells, J. P. R.; Schropp, R. E. I.; Vinh, N. Q.; Dijkhuis, J. I.

    2008-01-01

    We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si-H and Ge-H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe: H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to t

  11. Vibration perception and thermoperception as quantitative measurements in the monitoring of cisplatin induced neurotoxicity

    NARCIS (Netherlands)

    Gispen, W.H.; Elderson, Arthur; Gerritsen van der Hoop, R.; Haanstra, W.; Neijt, J.P.; Jennekens, F.G.I.

    1989-01-01

    In 20 ovarian cancer patients treated by cisplatin-based chemotherapy quantitative investigations of the vibration and the thermoperception were performed. Following the administration of cisplatin of 300 mg/m2 and more the vibration perception threshold (VPT) was shown to be significantly elevated

  12. Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

    Science.gov (United States)

    Kel, Oksana; Tamimi, Amr; Fayer, Michael D.

    2014-01-01

    The ultrafast structural dynamics inside the bilayers of dilauroylphosphatidylcholine (DLPC) and dipalmitoylphosphatidylcholine vesicles with 70, 90, and 125 nm diameters were directly measured with 2D IR vibrational echo spectroscopy. The antisymmetric CO stretch of tungsten hexacarbonyl was used as a vibrational probe and provided information on spectral diffusion (structural dynamics) in the alkyl region of the bilayers. Although the CO stretch absorption spectra remain the same, the interior structural dynamics become faster as the size of the vesicles decrease, with the size dependence greater for dipalmitoylphosphatidylcholine than for DLPC. As DLPC vesicles become larger, the interior dynamics approach those of the planar bilayer. PMID:24395796

  13. Vibration harvesting in traffic tunnels to power wireless sensor nodes

    Science.gov (United States)

    Wischke, M.; Masur, M.; Kröner, M.; Woias, P.

    2011-08-01

    Monitoring the traffic and the structural health of traffic tunnels requires numerous sensors. Powering these remote and partially embedded sensors from ambient energies will reduce maintenance costs, and improve the sensor network performance. This work reports on vibration levels detected in railway and road tunnels as a potential energy source for embedded sensors. The measurement results showed that the vibrations at any location in the road tunnel and at the wall in the railway tunnel are too small for useful vibration harvesting. In contrast, the railway sleeper features usable vibrations and sufficient mounting space. For this application site, a robust piezoelectric vibration harvester was designed and equipped with a power interface circuit. Within the field test, it is demonstrated that sufficient energy is harvested to supply a microcontroller with a radio frequency (RF) interface.

  14. The application of a cavity ring-down spectrometer to measurements of ambient ammonia using traceable primary standard gas mixtures

    Science.gov (United States)

    Martin, Nicholas A.; Ferracci, Valerio; Cassidy, Nathan; Hoffnagle, John A.

    2016-08-01

    A correction for the undesirable effects of direct and indirect cross-interference from water vapour on ammonia (NH3) measurements was developed using an optical laser sensor based on cavity ring-down spectroscopy. This correction relied on new measurements of the collisional broadening due to water vapour of two NH3 spectral lines in the near infra-red (6548.6 and 6548.8 cm-1), and on the development of novel stable primary standard gas mixtures (PSMs) of ammonia prepared by gravimetry in passivated gas cylinders at 100 μmol mol-1. The PSMs were diluted dynamically to provide calibration mixtures of dry and humidified ammonia atmospheres of known composition in the nmol mol-1 range and were employed as part of establishing a metrological traceability chain to improve the reliability and accuracy of ambient ammonia measurements. The successful implementation of this correction will allow the extension of this rapid on-line spectroscopic technique to exposure chamber validation tests under controlled conditions and ambient monitoring in the field.

  15. Measurement of polycyclic aromatic hydrocarbons in ambient air by fluorescence spectroscopic techniques

    OpenAIRE

    Elcoroaristizabal Martin, Saioa

    2015-01-01

    250 p. + anexos Este proyecto de Tesis Doctoral se inició en marzo de 2011 gracias a la becapredoctoral otorgada por la Universidad del País Vasco (UPV/EHU), a través delprograma de ¿Formación de Personal Investigador¿, para trabajar en el Grupo deInvestigación Atmosférica (GIA) del Departamento de Ingeniería Química y del MedioAmbiente de la Escuela Técnica Superior de Ingeniería de Bilbao (Universidad delPaís Vasco, UPV/EHU). Asimismo, parte de este trabajo de investigación se hadesarrol...

  16. Review of measured vibration and noise environments experienced by passengers in aircraft and in ground transportation systems

    Science.gov (United States)

    Stephens, D. G.

    1975-01-01

    Measured vibration and interior noise data are presented for a number of air and surface vehicles. Consideration is given to the importance of direction effects; of vehicle operations such as take-off, cruise, and landing; and of measurement location on the level and frequency of the measurements. Various physical measurement units or descriptors are used to quantify and compare the data. Results suggest the range of vibration and noise associated with a particular mode of transportation and illustrate the comparative levels in terms of each of the descriptors. Collectively, the results form a data base which may be useful in assessing the ride of existing or future systems relative to vehicles in current operation.

  17. Ambient observations of hygroscopic growth factor and f(RH) below 1: Case studies from surface and airborne measurements

    Science.gov (United States)

    Shingler, Taylor; Sorooshian, Armin; Ortega, Amber; Crosbie, Ewan; Wonaschütz, Anna; Perring, Anne E.; Beyersdorf, Andreas; Ziemba, Luke; Jimenez, Jose L.; Campuzano-Jost, Pedro; Mikoviny, Tomas; Wisthaler, Armin; Russell, Lynn M.

    2016-11-01

    This study reports a detailed set of ambient observations of optical/physical shrinking of particles from exposure to water vapor with consistency across different instruments and regions. Data have been utilized from (i) a shipboard humidified tandem differential mobility analyzer during the Eastern Pacific Emitted Aerosol Cloud Experiment in 2011, (ii) multiple instruments on the NASA DC-8 research aircraft during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys in 2013, and (iii) the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe during ambient measurements in Tucson, Arizona, during summer 2014 and winter 2015. Hygroscopic growth factor (ratio of humidified-to-dry diameter, GF = Dp,wet/Dp,dry) and f(RH) (ratio of humidified-to-dry scattering coefficients) values below 1 were observed across the range of relative humidity (RH) investigated (75-95%). A commonality of observations of GF and f(RH) below 1 in these experiments was the presence of particles enriched with carbonaceous matter, especially from biomass burning. Evidence of externally mixed aerosol, and thus multiple GFs with at least one GF < 1, was observed concurrently with f(RH) < 1 during smoke periods. Possible mechanisms responsible for observed shrinkage are discussed and include particle restructuring, volatilization effects, and refractive index modifications due to aqueous processing resulting in optical size modification. To further investigate ambient observations of GFs and f(RH) values less than 1, it is recommended to add an optional prehumidification bypass module to hygroscopicity instruments, to preemptively collapse particles prior to controlled RH measurements.

  18. Measurement of torsional vibration to detect angular misalignment through the modulated square wave of an encoder

    Science.gov (United States)

    Meroño, P. A.; Gómez, F. C.; Marín, F.; Zaghar, L.

    2017-02-01

    One of the widely used processes to measure torsional vibration focuses on the analysis of a square signal from a device set in the machine shaft. The tools used for this purpose usually consist of a toothed wheel connected to an appropriate transducer, of an electromagnetic or optic type, which provides a square wave signal. If the rotation velocity is constant, the signal pulses are the same width, but when the velocity changes, the width of the pulses changes too, lengthening or shortening its width, resulting in a frequency modulated signal. When the shafts of the machines are misaligned angularly, the average speed changes due to variable torque action, so that spectral features of modulated signal show frequency components that are explained by the Bessel Functions. This work shows that these components are caused by a carrying (constant average speed) and a modulator signal (variable turning speed) between the harmonics surrounding the central frequency. Besides, it may also test their relationship with the presence of angular misalignment in the coupled-machine shafts. In addition, an iterative method is applied to construct the frequency spectral diagram of the induced square signal, once the appropriate modulation indices of the Bessel functions have been calculated. To compare and validate the method, different bench tests have been performed using pulse signal and laser interferometry.

  19. Vibration sensors

    Science.gov (United States)

    Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

    2003-10-01

    Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

  20. Polyfluorinated compounds in ambient air from ship- and land-based measurements in northern Germany

    Science.gov (United States)

    Dreyer, Annekatrin; Ebinghaus, Ralf

    Neutral volatile and semi-volatile polyfluorinated organic compounds (PFC) and ionic perfluorinated compounds were determined in air samples collected at two sites in the vicinity of Hamburg, Germany, and onboard the German research vessel Atair during a cruise in the German Bight, North Sea, in early November 2007. PUF/XAD-2/PUF cartridges and glass fiber filters as sampling media were applied to collect several fluorotelomer alcohols (FTOH), fluorotelomer acrylates (FTA), perfluoroalkyl sulfonamides (FASA), and perfluoroalkyl sulfonamido ethanols (FASE) in the gas- and particle-phase as well as a set of perfluorinated carboxylates (PFCA) and sulfonates (PFSA) in the particle-phase. This study presents the distribution of PFC in ambient air of the German North Sea and in the vicinity of Hamburg for the first time. Average total PFC concentrations in and around Hamburg (180 pg m -3) were higher than those observed in the German Bight (80 pg m -3). In the German Bight, minimum-maximum gas-phase concentrations of 17-82 pg m -3 for ΣFTOH, 2.6-10 pg m -3 for ΣFTA, 10-15 pg m -3 for ΣFASA, and 2-4.4 pg m -3 for ΣFASE were determined. In the vicinity of Hamburg, minimum-maximum gas-phase concentrations of 32-204 pg m -3 for ΣFTOH, 3-26 pg m -3 for ΣFTA, 3-18 pg m -3 for ΣFASA, and 2-15 pg m -3 for ΣFASE were detected. Concentrations of perfluorinated acids were in the range of 1-11 pg m -3. FTOH clearly dominated the substance spectrum; 8:2 FTOH occurred in maximum proportions. Air mass back trajectories, cluster, and correlation analyses revealed that the air mass origin and thus medium to long range atmospheric transport was the governing parameter for the amount of PFC in ambient air. Southwesterly located source regions seemed to be responsible for elevated PFC concentrations, local sources appeared to be of minor importance.

  1. Measuring airborne components of seismic body vibrations in a Middle-Asian sand-dwelling Insectivora species, the piebald shrew (Diplomesodon pulchellum).

    Science.gov (United States)

    Volodin, Ilya A; Zaytseva, Alexandra S; Ilchenko, Olga G; Volodina, Elena V; Chebotareva, Anastasia L

    2012-08-15

    Self-produced seismic vibrations have been found for some subterranean rodents but have not been reported for any Insectivora species, although seismic sensitivity has been confirmed for blind sand-dwelling chrysochlorid golden moles. Studying the vocal behaviour of captive piebald shrews, Diplomesodon pulchellum, we documented vibrations, apparently generated by the whole-body wall muscles, from 11 (5 male, 6 female) of 19 animals, placed singly on a drum membrane. The airborne waves of the vibratory drumming were digitally recorded and then analysed spectrographically. The mean frequency of vibration was 160.5 Hz. This frequency matched the periodicity of the deep sinusoidal frequency modulation (159.4 Hz) found in loud screech calls of the same subjects. The body vibration was not related to thermoregulation, hunger-related depletion of energy resources or fear, as it was produced by well-fed, calm animals, at warm ambient temperatures. We hypothesize that in the solitary, nocturnal, digging desert piebald shrew, body vibrations may be used for seismic exploration of substrate density, to avoid energy-costly digging of packed sand for burrowing and foraging. At the same time, the piercing quality of screech calls due to the deep sinusoidal frequency modulation, matching the periodicity of body vibration, may be important for agonistic communication in this species.

  2. Ambient in-situ immersion freezing measurements - findings from the ZAMBIS 2014 field campaign for three ice nucleation techniques

    Science.gov (United States)

    Kohn, Monika; Atkinson, James D.; Lohmann, Ulrike; Kanji, Zamin A.

    2015-04-01

    To estimate the influence of clouds on the Earth's radiation budget, it is crucial to understand cloud formation processes in the atmosphere. A key process, which significantly affects cloud microphysical properties and the initiation of precipitation thus contributing to the hydrological cycle, is the prevailing type of ice nucleation mechanism. In mixed-phase clouds immersion freezing is the dominant ice crystal forming mechanism, whereby ice nucleating particles (INP) first act as cloud condensation nuclei (CCN) and are activated to cloud droplets followed by freezing upon supercooling. There are a number of experimental methods and techniques to investigate the ice nucleating ability in the immersion mode, however most techniques are offline for field sampling or only suitable for laboratory measurements. In-situ atmospheric studies are needed to understand the ice formation processes of 'real world' particles. Laboratory experiments simulate conditions of atmospheric processes like ageing or coating but are still idealized. Our method is able to measure ambient in-situ immersion freezing on single immersed aerosol particles. The instrumental setup consists of the recently developed portable immersion mode cooling chamber (PIMCA) as a vertical extension to the portable ice nucleation chamber (PINC, [1]), where the frozen fraction of activated aerosol particles are detected by the ice optical depolarization detector (IODE, [2]). Two additional immersion freezing techniques based on a droplet freezing array [3,4] are used to sample ambient aerosol particles either in a suspension (fraction larger ~0.6 μm) or on PM10-filters to compare different ice nucleation techniques. Here, we present ambient in-situ measurements at an urban forest site in Zurich, Switzerland held during the Zurich ambient immersion freezing study (ZAMBIS) in spring 2014. We investigated the ice nucleating ability of natural atmospheric aerosol with the PIMCA/PINC immersion freezing setup as

  3. Speciated mercury measurements in ambient air from 2009 to 2011 at a Central European rural background monitoring site

    Directory of Open Access Journals (Sweden)

    Weigelt A.

    2013-04-01

    Full Text Available Since January 2009 highly time-resolved mercury speciation measurements in ambient air are carried out at the Central European German EMEP monitoring station and measurement site of the German Federal Environment Agency “Waldhof“, providing the longest Central European dataset for mercury species. First statistical analyses do not indicate long term trends for the concentrations of gaseous elemental mercury (GEM and particle bound mercury (TPM. A potential increasing trend for reactive gaseous mercury (RGM will have to be verified in the coming years and should be regarded as indicative only at present. A seasonal cycle for TPM could be observed with higher concentrations during winter time. Furthermore a diurnal cycle for RGM is apparent with highest concentrations in the early afternoon.

  4. Experimental Investigation of Wave-Induced Ship Hydroelastic Vibrations by Large-Scale Model Measurement in Coastal Waves

    Directory of Open Access Journals (Sweden)

    Jialong Jiao

    2016-01-01

    Full Text Available Ship hydroelastic vibration is an issue involving mutual interactions among inertial, hydrodynamic, and elastic forces. The conventional laboratory tests for wave-induced hydroelastic vibrations of ships are performed in tank conditions. An alternative approach to the conventional laboratory basin measurement, proposed in this paper, is to perform tests by large-scale model measurement in real sea waves. In order to perform this kind of novel experimental measurement, a large-scale free running model and the experiment scheme are proposed and introduced. The proposed testing methodology is quite general and applicable to a wide range of ship hydrodynamic experimental research. The testing procedure is presented by illustrating a 5-hour voyage trial of the large-scale model carried out at Huludao harbor of China in August 2015. Hammer tests were performed to identify the natural frequencies of the ship model at the beginning of the tests. Then a series of tests under different sailing conditions were carried out to investigate the vibrational characteristics of the model. As a postvoyage analysis, load, pressure, acceleration, and motion responses of the model are studied with respect to different time durations based on the measured data.

  5. Measurements and source apportionment of particle-associated polycyclic aromatic hydrocarbons in ambient air in Riyadh, Saudi Arabia

    Science.gov (United States)

    Bian, Qijing; Alharbi, Badr; Collett, Jeffrey; Kreidenweis, Sonia; Pasha, Mohammad J.

    2016-07-01

    Ambient air samples were obtained in Riyadh, the capital and largest city of Saudi Arabia, during two measurement campaigns spanning September 2011 to September 2012. Sixteen particle-phase polycyclic aromatic hydrocarbons (PAH) were quantified in 167 samples. Pyrene and fluoranthene were the most abundant PAH, with average of 3.37 ± 14.01 ng m-3 and 8.00 ± 44.09 ng m-3, respectively. A dominant contribution from low molecular weight (LMW) PAH (MW < 228) suggested a large influence of industrial emissions on PAH concentrations. Monte Carlo source apportionment using diagnostic ratios showed that 80 ± 10% of the average LMW PAH concentrations were contributed by petroleum vapor emissions, while 53 ± 19% of high molecular weight (HMW) PAH were from solid fuel combustion emissions. The positive matrix factorization model estimated that oil combustion emissions dominated total PAH concentrations, accounting for on average 96%, likely due to widespread use of oil fuels in energy production (power plants and industries). Our results demonstrate the significant influence of petroleum product production and consumption on particulate-phase PAH concentrations in Riyadh, but also point to the importance of traffic and solid fuel burning, including coke burning and seasonal biomass burning, especially as they contribute to the ambient levels of HMW PAH.

  6. Flow measurement and thrust estimation of a vibrating ionic polymer metal composite

    Science.gov (United States)

    Chae, Woojin; Cha, Youngsu; Peterson, Sean D.; Porfiri, Maurizio

    2015-09-01

    Ionic polymer metal composites (IPMCs) are an emerging class of soft active materials that are finding growing application as underwater propulsors for miniature biomimetic swimmers. Understanding the hydrodynamics generated by an IPMC vibrating under water is central to the design of such biomimetic swimmers. In this paper, we propose the use of time-resolved particle image velocimetry to detail the fluid kinematics and kinetics in the vicinity of an IPMC vibrating along its fundamental structural mode. The reconstructed pressure field is ultimately used to estimate the thrust produced by the IPMC. The vibration frequency is systematically varied to elucidate the role of the Reynolds number on the flow physics and the thrust production. Experimental results indicate the formation and shedding of vortical structures from the IPMC tip during its vibration. Vorticity shedding is sustained by the pressure gradients along each side of the IPMC, which are most severe in the vicinity of the tip. The mean thrust is found to robustly increase with the Reynolds number, closely following a power law that has been derived from direct three-dimensional numerical simulations. A reduced order distributed model is proposed to describe IPMC underwater vibration and estimate thrust production, offering insight into the physics of underwater propulsion and aiding in the design of IPMC-based propulsors.

  7. Image-based tracking system for vibration measurement of a rotating object using a laser scanning vibrometer

    Science.gov (United States)

    Kim, Dongkyu; Khalil, Hossam; Jo, Youngjoon; Park, Kyihwan

    2016-06-01

    An image-based tracking system using laser scanning vibrometer is developed for vibration measurement of a rotating object. The proposed system unlike a conventional one can be used where the position or velocity sensor such as an encoder cannot be attached to an object. An image processing algorithm is introduced to detect a landmark and laser beam based on their colors. Then, through using feedback control system, the laser beam can track a rotating object.

  8. Calibrating MMS Electron Drift Instrument (EDI) Ambient Electron Flux Measurements and Characterizing 3D Electric Field Signatures of Magnetic Reconnection

    Science.gov (United States)

    Shuster, J. R.; Torbert, R. B.; Vaith, H.; Argall, M. R.; Li, G.; Chen, L. J.; Ergun, R. E.; Lindqvist, P. A.; Marklund, G. T.; Khotyaintsev, Y. V.; Russell, C. T.; Magnes, W.; Le Contel, O.; Pollock, C. J.; Giles, B. L.

    2015-12-01

    The electron drift instruments (EDIs) onboard each MMS spacecraft are designed with large geometric factors (~0.01cm2 str) to facilitate detection of weak (~100 nA) electron beams fired and received by the two gun-detector units (GDUs) when EDI is in its "electric field mode" to determine the local electric and magnetic fields. A consequence of the large geometric factor is that "ambient mode" electron flux measurements (500 eV electrons having 0°, 90°, or 180° pitch angle) can vary depending on the orientation of the EDI instrument with respect to the magnetic field, a nonphysical effect that requires a correction. Here, we present determinations of the θ- and ø-dependent correction factors for the eight EDI GDUs, where θ (ø) is the polar (azimuthal) angle between the GDU symmetry axis and the local magnetic field direction, and compare the corrected fluxes with those measured by the fast plasma instrument (FPI). Using these corrected, high time resolution (~1,000 samples per second) ambient electron fluxes, combined with the unprecedentedly high resolution 3D electric field measurements taken by the spin-plane and axial double probes (SDP and ADP), we are equipped to accurately detect electron-scale current layers and electric field waves associated with the non-Maxwellian (anisotropic and agyrotropic) particle distribution functions predicted to exist in the reconnection diffusion region. We compare initial observations of the diffusion region with distributions and wave analysis from PIC simulations of asymmetric reconnection applicable for modeling reconnection at the Earth's magnetopause, where MMS will begin Science Phase 1 as of September 1, 2015.

  9. Hot-wire measurements with automatic compensation of ambient temperature changes

    Directory of Open Access Journals (Sweden)

    Miheev Nikolay I.

    2015-01-01

    Full Text Available A single sensor hot-wire device with automatic temperature compensation for velocity measurements is developed. Experience in measuring the velocity and temperature in a flow with variable temperature using self-made hot-wire equipment and probes is discussed. Results of the corresponding methodical experiments are presented.

  10. Hot-wire measurements with automatic compensation of ambient temperature changes

    OpenAIRE

    Miheev Nikolay I.; Molochnikov Valeriy M.; Kratirov Dmitriy V.; Hayrnasov Konstantin R.; Zanko Philipp S.

    2015-01-01

    A single sensor hot-wire device with automatic temperature compensation for velocity measurements is developed. Experience in measuring the velocity and temperature in a flow with variable temperature using self-made hot-wire equipment and probes is discussed. Results of the corresponding methodical experiments are presented.

  11. Camera-based measurement for transverse vibrations of moving catenaries in mine hoists using digital image processing techniques

    Science.gov (United States)

    Yao, Jiannan; Xiao, Xingming; Liu, Yao

    2016-03-01

    This paper proposes a novel, non-contact, sensing method to measure the transverse vibrations of hoisting catenaries in mine hoists. Hoisting catenaries are typically moving cables and it is not feasible to use traditional methods to measure their transverse vibrations. In order to obtain the transverse displacements of an arbitrary point in a moving catenary, by superposing a mask image having the predefined reference line perpendicular to the hoisting catenaries on each frame of the processed image sequence, the dynamic intersecting points with a grey value of 0 in the image sequence could be identified. Subsequently, by traversing the coordinates of the pixel with a grey value of 0 and calculating the distance between the identified dynamic points from the reference, the transverse displacements of the selected arbitrary point in the hoisting catenary can be obtained. Furthermore, based on a theoretical model, the reasonability and applicability of the proposed camera-based method were confirmed. Additionally, a laboratory experiment was also carried out, which then validated the accuracy of the proposed method. The research results indicate that the proposed camera-based method is suitable for the measurement of the transverse vibrations of moving cables.

  12. Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects.

    Science.gov (United States)

    Moshourab, Rabih; Frenzel, Henning; Lechner, Stefan; Haseleu, Julia; Bégay, Valérie; Omerbašić, Damir; Lewin, Gary R

    2016-09-01

    Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about mechanosensory function that are relevant for clinical diagnosis as well as for basic research. Here, we describe two psychophysical tests designed to determine the vibration detection threshold (automated system) and tactile spatial acuity (handheld device). Both procedures implement a two-interval forced-choice and a transformed-rule up and down experimental paradigm. These tests have been used to obtain mechanosensory profiles for individuals from distinct human cohorts such as twins or people with sensorineural deafness.

  13. Adaptive Model-Based Mine Detection/Localization using Noisy Laser Doppler Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, E J; Xiang, N; Candy, J V

    2009-04-06

    The acoustic detection of buried mines is hampered by the fact that at the frequencies required for obtaining useful penetration, the energy is quickly absorbed by the ground. A recent approach which avoids this problem, is to excite the ground with a high-level low frequency sound, which excites low frequency resonances in the mine. These resonances cause a low-level vibration on the surface which can be detected by a Laser Doppler Vibrometer. This paper presents a method of quickly and efficiently detecting these vibrations by sensing a change in the statistics of the signal when the mine is present. Results based on real data are shown.

  14. Vibration control in accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Montag, C.

    2011-01-01

    In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.

  15. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

    Science.gov (United States)

    Subhash, Hrebesh M.; Choudhury, Niloy; Jacques, Steven L.; Wang, Ruikang K.; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.

    2012-01-01

    Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from each of the delay-encoded vibration images with a noise floor of ~0.3nm at 200Hz.

  16. A novel vibration-based fault diagnostic algorithm for gearboxes under speed fluctuations without rotational speed measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Liu; Qu, Yongzhi; Dhupia, Jaspreet Singh; Sheng, Shuangwen; Tan, Yuegang; Zhou, Zude

    2017-02-27

    The localized failures of gears introduce cyclic-transient impulses in the measured gearbox vibration signals. These impulses are usually identified from the sidebands around gear-mesh harmonics through the spectral analysis of cyclo-stationary signals. However, in practice, several high-powered applications of gearboxes like wind turbines are intrinsically characterized by nonstationary processes that blur the measured vibration spectra of a gearbox and deteriorate the efficacy of spectral diagnostic methods. Although order-tracking techniques have been proposed to improve the performance of spectral diagnosis for nonstationary signals measured in such applications, the required hardware for the measurement of rotational speed of these machines is often unavailable in industrial settings. Moreover, existing tacho-less order-tracking approaches are usually limited by the high time-frequency resolution requirement, which is a prerequisite for the precise estimation of the instantaneous frequency. To address such issues, a novel fault-signature enhancement algorithm is proposed that can alleviate the spectral smearing without the need of rotational speed measurement. This proposed tacho-less diagnostic technique resamples the measured acceleration signal of the gearbox based on the optimal warping path evaluated from the fast dynamic time-warping algorithm, which aligns a filtered shaft rotational harmonic signal with respect to a reference signal assuming a constant shaft rotational speed estimated from the approximation of operational speed. The effectiveness of this method is validated using both simulated signals from a fixed-axis gear pair under nonstationary conditions and experimental measurements from a 750-kW planetary wind turbine gearbox on a dynamometer test rig. The results demonstrate that the proposed algorithm can identify fault information from typical gearbox vibration measurements carried out in a resource-constrained industrial environment.

  17. Volatile organic compounds in urban atmospheres: Long-term measurements of ambient air concentrations in differently loaded regions of Leipzig

    Energy Technology Data Exchange (ETDEWEB)

    Knobloch, T.; Asperger, A.; Engewald, W. [University of Leipzig, Institute of Analytical Chemistry, Leipzig (Germany)

    1997-09-01

    For the comprehensive characterization of ambient air concentrations of a broad spectrum of volatile organic compounds (VOCs) an analytical method is described, consisting of adsorptive enrichment, thermal desorption without cryofocusing, and capillary gas chromatographic separation. The method was applied during two-week measuring campaigns in winter and summer 1995, and in the winter of 1996. Long-term sampling was carried out at sampling points in residential areas in the suburbs and near the city center of Leipzig. About 70 VOCs - mainly hydrocarbons from propene to hexadecane - were identified both by GC-MS and chromatographic retention data and quantified after external calibration. Mean values of VOC concentrations obtained during the sampling periods are reported and discussed with regard to the topographical location of the sampling points in the Leipzig area, seasonal variations, and possible emission sources. (orig.) With 7 figs., 3 tabs., 18 refs.

  18. Evaluation of protection measurements for rural environments; Avaliacao de medidas de protecao para ambientes rurais

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Diogo N.G.; Silva, Fernanda L.; Conti, Luiz F., E-mail: dneves@ird.gov.b, E-mail: lfcconti@ird.gov.b, E-mail: fleite@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Wasserman, Maria Angelica V., E-mail: maria.wasserman@pq.cnpq.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Rochedo, Elaine R.R., E-mail: erochedo@cnen.gov.b [Comissao Nacional de Energia Nuclear (CODIN/CNEN), Rio de Janeiro, RJ (Brazil). Coord. de Instalacoes Nucleares

    2011-10-26

    Among the planning activities of actuation in nuclear/radiological emergences, it is included the efficiency evaluation of protection and remediation measurements. From the development of a data base on such measurements for the agricultural areas, the program SIEM was used for effectuation the simulations involving the {sup 137}Cs, {sup 131}I and {sup 90}Sr radionuclides, in scenery previously established for simulation those areas of a 50 km surrounding the Admiral Alvaro Alberto nuclear power plant. The obtained results indicate that the scenery is determinant of efficiency measurements involving various specific factors of each place, such as: agricultural and cattle breeding products, consumption habits of population and the grade of subsistence by the diet items, making not practical the elaboration of predefined generic sceneries. The great dependence on seasoning related to the moment of accident makes inadequate any previous evaluation what soever for evaluation of efficiency of protection and remediation measurements. Therefore, previous decisions are not recommended about the relevance of protection measurements for rural areas. Two classification criteria were defined: (i) the efficiency in reduction the doses in the firs year; and, (i i) efficiency in reduction the dose at long term

  19. Evaluation of protection measurements for urban environments; Avaliacao de medidas de protecao para ambientes urbanos

    Energy Technology Data Exchange (ETDEWEB)

    Rochedo, Elaine R.R., E-mail: erochedo@cnen.gov.b [Comissao Nacional de Energia Nuclear (CODIN/CNEN), Rio de Janeiro, RJ (Brazil). Coord. de Instalacoes Nucleares; Silva, Diogo N.G.; Nascimento, Udilma; Conti, Luiz F., E-mail: dneves@ird.gov.b, E-mail: lfcconti@ird.gov.b, E-mail: udilma@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Wasserman, Maria Angelica V., E-mail: maria.wasserman@pq.cnpq.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-10-26

    Radioactive accidents has shown the necessity of a previous evaluation planning of exposure and directives for implementation of protection measurements. The description or measurements in the literature usually is associated to reduction of concentrations in the medium where they are applied. For verification the efficiency in dose reduction, it is necessary to proceed simulations. Through the development of data base on protection measurements, it was established basic sceneries, typically tropical as far the building type is concerned and the construction material. The program SIEM was used for simulation of contamination with {sup 137}Cs. The results indicates that generic solutions persuade not to and the decision make processes should be effectuated according to the real conditions of contamination and the use of affected area. For affected areas, two classification criteria were defined: (1) efficiency in reducing the dose in the first year; and (2) efficiency in dose reducing at long term

  20. The Shock and Vibration Bulletin. Part 4. Underwater Problems, Environments and Measurements

    Science.gov (United States)

    1974-08-01

    on the source impedance, and ascertain the origin of its stiffness-damper aspect. i^fe The Navy large Floating Shock Platfora rtu -l 1; ilysical...Vibration Pickups,S2.2-1959,(Section S, Calibration by Comparison with Calibrated Pickup). 3. Instrument Society of America, 22nd Annual ISA

  1. Acoustic determination of cracks in welded joints. [by resonant structural vibration measurements

    Science.gov (United States)

    Baltanoiu, M.; Criciotoiu, E.

    1974-01-01

    The acoustic analysis method permits detection of any cracks that might take place and their manner of propagation. The study deals with the cracks produced in experiments to determine the welding technology for a welded gray cast iron workpiece by using piezoelectric transducers to determine vibration acceleration.

  2. Damage detection in bridge structures under moving loads with phase trajectory change of multi-type vibration measurements

    Science.gov (United States)

    Zhang, Weiwei; Li, Jun; Hao, Hong; Ma, Hongwei

    2017-03-01

    This paper presents a non-model based damage detection approach for bridge structures under moving loads based on the phase trajectory change of multi-type vibration measurements. A brief theoretical background on the vibration of a simply-supported bridge with a crack under moving load is described. The phase trajectories of multi-type dynamic responses are obtained and a damage index is defined as the separated distance between the trajectories of undamaged and damaged structures to indicate the damage location. Numerical studies on a simply-supported beam structure are conducted to investigate the sensitivity and robustness of the proposed approach to accurately identify the damage location. Experimental studies demonstrate that the proposed approach can be used to successfully identify the shear connection failure in a composite bridge model subjected to moving loads.

  3. Methane and nitrous oxide emissions in The Netherlands : ambient measurements support the national inventories

    NARCIS (Netherlands)

    van der Laan, S.; Neubert, R. E. M.; Meijer, H. A. J.; Hofzumahaus, A.

    2009-01-01

    We present net emission estimates of CH(4) and N(2)O of The Netherlands based on measurements conducted during the period of May 2006 to April 2009 at station Lutjewad, The Netherlands (6 degrees 21' E, 53 degrees 24' N, 1 m a.s.l.). (222)Radon mixing ratios were applied as an indicator for vertical

  4. Ambient concentrations of aldehydes in relation to Beijing Olympic air pollution control measures

    Directory of Open Access Journals (Sweden)

    J. C. Gong

    2010-08-01

    Full Text Available Aldehydes are ubiquitous constituents of the atmosphere. Their concentrations are elevated in polluted urban atmospheres. The present study was carried out to characterize three aldehydes of most health concern (formaldehyde, acetaldehyde, and acrolein in a central Beijing site in the summer and early fall of 2008 (from June to October. Measurements were made before, during, and after the Beijing Olympics to examine whether the air pollution control measures implemented to improve Beijing's air quality during the Olympics had any impact on concentrations of the three aldehydes. Average concentrations of formaldehyde, acetaldehyde and acrolein were 29.34 ± 15.12 μg/m3, 27.09 ± 15.74 μg/m3 and 2.32 ± 0.95 μg/m3, respectively, for the entire period of measurements, all being the highest among the levels measured in cities around the world in photochemical smog seasons. Among the three measured aldehydes, only acetaldehyde had a substantially reduced mean concentration during the Olympic air pollution control period compared to the pre-Olympic period. Formaldehyde and acrolein followed the changing pattern of temperature and were each significantly correlated with ozone (a secondary product of photochemical reactions. In contrast, acetaldehyde was significantly correlated with several pollutants emitted mainly from local emission sources (e.g., NO2, CO, and PM2.5. These findings suggest that local direct emissions had a larger impact on acetaldehyde than formaldehyde and acrolein.

  5. Vibration measurements based on demodulating the phase of a fiber 3dB-coupler Michelson interferometer

    Science.gov (United States)

    Li, Min; Xie, Fang; Ren, Junyu

    2009-11-01

    A fiber interferometric vibration measurement system which is based on demodulating the phase of a fiber Michelson interferometer which is made with a fiber 3dB-coupler is presented. In the work, the system employed the characteristics of fiber Brag gratings (FBGs) to interleave two fiber Michelson interferometers which share almost the same part of the main optical path. One of the fiber interferometers is used to stabilize the system, employing an electronic feedback loop to drive a piezoelectric actuator to tune the optical path of the reference beam in order to keep the interferometer in quadrature state. By this way, the low frequency drifts in the phase of the interferometric signals which are resulted from environmental disturbances are compensated for. The other one is used to perform the measurement task. By employing the characteristics of 3dB-coupler, the interferometric signals from the two outputs of the 3dB-couper are 180º out of phase. The two interferometric signals are input into an electronic processor and convert into currents, which are linear to the power of the optical interferometric light. The signals are collected by NI USB-5132 acquisition card and processed by a program in a personal computer. The measurement system is configured with fiber and fiber components which are integrated together. As the cutoff frequency of the feedback loop is 1.5Hz, the measurement system is capable of measuring vibration with frequencies bigger than 1.5Hz and the amplitude of the measured vibration is not limited.

  6. High voltage surface potential measurements in ambient conditions: Application to organic thin-film transistor injection and transport characterization

    Science.gov (United States)

    de Tournadre, Grégoire; Reisdorffer, Frédéric; Rödel, Reinhold; Simonetti, Olivier; Klauk, Hagen; Giraudet, Louis

    2016-03-01

    A scanning surface potential measurement technique suited for thin-film devices operating under high voltages is reported. A commercial atomic force microscope has been customized to enable a feedback-controlled and secure surface potential measurement based on phase-shift detection under ambient conditions. Measurements of the local potential profile along the channel of bottom-gate organic thin-film transistors (TFTs) are shown to be useful to disentangle the contributions from the channel and contacts to the device performance. Intrinsic contact current-voltage characteristics have been measured on bottom-gate, top-contact (staggered) TFTs based on the small-molecule semiconductor dinaphtho[2,3-b:2',3-f]thieno[3,2-b]thiophene (DNTT) and on bottom-gate, bottom-contact (coplanar) TFTs based on the semiconducting polymer polytriarylamine (PTAA). Injection has been found to be linear in the staggered DNTT TFTs and nonlinear in the coplanar PTAA TFTs. In both types of TFT, the injection efficiency has been found to improve with increasing gate bias in the accumulation regime. Contact resistances as low as 130 Ω cm have been measured in the DNTT TFTs. A method that eliminates the influence of bias-stress-induced threshold-voltage shifts when measuring the local charge-carrier mobility in the channel is also introduced, and intrinsic channel mobilities of 1.5 cm2 V-1 s-1 and 1.1 × 10-3 cm2 V-1 s-1 have been determined for DNTT and PTAA. In both semiconductors, the mobility has been found to be constant with respect to the gate bias. Despite its simplicity, the Kelvin probe force microscopy method reported here provides robust and accurate surface potential measurements on thin-film devices under operation and thus paves the way towards more extensive studies of particular interest in emerging fields of solid-state electronics.

  7. Ambient Space and Ambient Sensation

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central...... aspect of the aesthetization of modern culture in general, from architecture, transport and urbanized lifeforms to film, sound art, installation art and digital environments. This presentation will discuss the key aspects of ambient aesthetization, including issues such as objectlessness...

  8. Measurement of intravenously administered γ-Fe2O3 particle amount in mice tissues using vibrating sample magnetometer.

    Science.gov (United States)

    Kishimoto, Mikio; Miyamoto, Ryoichi; Oda, Tatsuya; Ohara, Yusuke; Yanagihara, Hideto; Ohkohchi, Nobuhiro; Kita, Eiji

    2014-12-01

    Dispersions of platelet γ-Fe2O3 particles 30-50nm in size were intravenously administered to mice and the amount of particles accumulated in each tissue was obtained by magnetization measurement using a vibrating sample magnetometer. Background noise was greatly reduced by measuring dried tissues under a magnetic field of 500 Oe so that the effect of diamagnetism was slight. Remarkable particle accumulation was observed in the liver and spleen. Considerable particle accumulation was observed in the lung when a large quantity of γ-Fe2 O3 particles was administered. There was no significant particle accumulation in the kidney and heart.

  9. Ambient Aerosol in Southeast Asia: High Resolution Aerosol Mass Spectrometer Measurements Over Oil Palm (Elaeis guineensis)

    Science.gov (United States)

    Phillips, G.; Dimarco, C.; Misztal, P.; Nemitz, E.; Farmer, D.; Kimmel, J.; Jimenez, J.

    2008-12-01

    The emission of organic compounds in the troposphere is important factor in the formation of secondary organic aerosol (SOA). A very large proportion of organic material emitted globally is estimated to arise from biogenic sources, with almost half coming from tropical and sub-tropical forests. Preliminary analyses of leave cuvette emission studies suggest that oil palm (Elaeis guineensis) is a significantly larger source of isoprene than tropical forest. Much larger sources of isoprene over oil palm allied with a larger anthropogenic component of local emissions contrast greatly with the remote tropical forest environment and therefore the character of SOA formed may differ significantly. These issues, allied with the high price of palm oil on international markets leading to increased use of land for oil palm production, could give rise to rapidly changing chemical and aerosol regimes in the tropics. It is therefore important to understand the current emissions and composition of organic aerosol over all important land-uses in the tropical environment. This in turn will lead to a greater understanding of the present, and to an improvement in predictive capacity for the future system. To help address these issues, a high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) was deployed in the Sabahmas (PPB OIL) oil palm plantation near Lahad Datu, in Eastern Sabah, as part of the field component of the Aerosol Coupling in the Earth System (ACES) project, part of the UK NERC APPRAISE program. This project was allied closely with measurements made of similar chemical species and aerosol components at a forest site in the Danum Valley as part of the UK Oxidant and Particle Photochemical Processes above a Southeast Asian tropical rainforest (OP3) project. Measurements of submicron non- refractory aerosol composition are presented along with some preliminary analysis of chemically resolved aerosol fluxes made with a new eddy covariance system, based on the

  10. Hydrocarbon gas standards at the pmol/mol level to support ambient atmospheric measurements.

    Science.gov (United States)

    Rhoderick, George C; Duewer, David L; Ning, Li; DeSirant, Kathryn

    2010-02-01

    Studies of climate change increasingly recognize the diverse influences exerted by hydrocarbons in the atmosphere, including roles in particulates and ozone formation. Measurements of key non-methane hydrocarbons (NMHCs) suggest atmospheric concentrations ranging from low pmol/mol to nmol/mol, depending on location and compound. To accurately establish concentration trends and to relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. Several of the world's National Metrology Institutes (NMIs) are developing primary and secondary reference gas standards at the nmol/mol level. While the U.S. NMI, the National Institute of Standards and Technology (NIST), has developed pmol/mol standards for halocarbons and some volatile organics, the feasibility of preparing well-characterized, stable standards for NMHCs at the pmol/mol level is not yet established. NIST recently developed a suite of primary standards by gravimetric dilution that contains 18 NMHCs covering the concentration range of 60 pmol/mol to 230 pmol/mol. Taking into account the small but chemically significant contribution of NMHCs in the high-purity diluent nitrogen used in their preparation, the relative concentrations and short-term stability (2 to 3 months) of these NMHCs in the primary standards have been confirmed by chromatographic analysis. The gravimetric values assigned from the methods used to prepare the materials and the analytical concentrations determined from chromatographic analysis generally agree to within +/-2 pmol/mol. However, anomalous results for several of the compounds reflect the difficulties inherent in avoiding contamination and making accurate measurements at these very low levels.

  11. Methane and nitrous oxide emissions in The Netherlands: ambient measurements support the national inventories

    Directory of Open Access Journals (Sweden)

    R. E. M. Neubert

    2009-12-01

    Full Text Available We present net emission estimates of CH4 and N2O of The Netherlands based on measurements conducted during the period of May 2006 to April 2009 at station Lutjewad, The Netherlands (6°21' E, 53°24' N, 1 m a.s.l.. 222Radon mixing ratios were applied as an indicator for vertical mixing and long-range air mass transport and used to calculate the net surface fluxes from atmospheric mixing ratios of CH4 and N2O. Our study shows that our measurement site Lutjewad is well-suited to measure emissions from The Netherlands and validation of the national inventories using the 222Radon flux method. Since this study is purely observation-based it is independent from inventories or atmospheric models. Our results are compared to the national inventories as reported to the UNFCCC. We found net emissions of: (15.2±5.3 t km−2 a−1 for CH4 and (0.9±0.3 t km−2 a−1 for N2O. These values are lower than the inventory-based emissions (2006-2008 averages of (18.3±3.3 t km−2 a−1 for CH4, and (1.3±0.6 t km−2 a−1 for N2O, but the differences are insignificant.

  12. Methane and nitrous oxide emissions in The Netherlands: ambient measurements support the national inventories

    Directory of Open Access Journals (Sweden)

    S. van der Laan

    2009-09-01

    Full Text Available We present net emission estimates of CH4 and N2O of The Netherlands based on measurements conducted during the period of May 2006 to April 2009 at station Lutjewad, The Netherlands (6° 21' E, 53° 24' N, 1 m a.s.l.. 222Radon mixing ratios were applied as an indicator for vertical mixing and long-range air mass transport and used to calculate the net surface fluxes from atmospheric mixing ratios of CH4 and N2O. Our study shows that our measurement site Lutjewad is well-suited to measure emissions from The Netherlands and validation of the national inventories using the 222Radon flux method. Since this study is purely observation-based it is independent from inventories or atmospheric models. Our results are compared to the national inventories as reported to the UNFCCC. We found net emissions of: (15.2±5.3 t km-2 a-1 for CH4 and (0.9±0.3 t km-2 a-1 for N2O. These values are lower than the inventory-based emissions (2006–2008 averages of (18.3±3.3 t km-2 a-1 for CH4, and (1.3±0.6 t km-2 a-1 for N2O, but the differences are insignificant.

  13. Station for spatially distributed measurements of soil moisture and ambient temperature

    Science.gov (United States)

    Jankovec, Jakub; Šanda, Martin; Haase, Tomáš; Sněhota, Michal; Wild, Jan

    2013-04-01

    Third generation of combined thermal and soil moisture standalone field station coded TMS3 with wireless communication is presented. The device combines three thermometers (MAXIM/DALLAS Semiconductor DS7505U with -55 to +125°C range and 0.0625°C resolution, 0.5°C precision in 0 to +70°C range and 2°C precision out of this range). Soil moisture measurement is performed based on time domain transmission (TDT) principle for the full range of soil moisture with 0.025% resolution within the full possible soil moisture span for the most typical conditions of dry to saturated soils with safe margins to enable measurements in freezing, hot or saline soils. Principal compact version is designed for temperature measurements approximately at heights -10, 0 and +15 cm relative to soil surface when installed vertically and soil moisture measurements between 0 and 12 cm below surface. Set of buriable/subsurface stations each with 2.2 meter extension cord with soil and surface temperature measurement provides possibility to scan vertical soil profile for soil moisture and temperature at desired depths. USB equipped station is designed for streamed direct data acquisition in laboratory use in 1s interval. Station is also equipped with the shock sensor indicating the manipulation. Presented version incorporates life time permanent data storage (0.5 million logs). Current sensor design aims towards improved durability in harsh outdoor environment with reliable functioning in wet conditions withstanding mechanical or electric shock destruction. Insertion into the soil is possible by pressing with the use of a simple plastic cover. Data are retrieved by contact portable pocket collector (second generation) or by RFID wireless communication for hundreds meter distance (third generation) in either star pattern of GSM hub to stations or lined up GSM to station to another station both in comprised data packets. This option will allow online data harvesting and real time process

  14. EPISTEMOLOGIA AMBIENTAL

    OpenAIRE

    2012-01-01

    O livro Epistemologia Ambiental traz uma rica discussão sobre a questão ambiental, abordando teorias relevantes para o entendimento e interpretação da crise atual, orientando para a construção de novas racionalidades e a constituição de um saber ambiental. A obra vem compartimentada em cinco capítulos distribuídos em 240 páginas. 

  15. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: elemental carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2015-06-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as Thermal-Optical Reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier Transform Infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure tested and developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FTIR spectra are divided into calibration and test sets. Two calibrations are developed, one which is developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a~uniform distribution of low EC mass samples (EC TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of variation (R2; 0.96), no bias (0.00 μg m-3, concentration value based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.03 μg m-3) and reasonable normalized error (21 %). These performance metrics can be achieved with various degrees of spectral pretreatment

  16. Magnetic-field sensing coil embedded in ceramic for measuring ambient magnetic field

    Science.gov (United States)

    Takahashi, Hironori

    2004-02-10

    A magnetic pick-up coil for measuring magnetic field with high specific sensitivity, optionally with an electrostatic shield (24), having coupling elements (22) with high winding packing ratio, oriented in multiple directions, and embedded in ceramic material for structural support and electrical insulation. Elements of the coil are constructed from green ceramic sheets (200) and metallic ink deposited on surfaces and in via holes of the ceramic sheets. The ceramic sheets and the metallic ink are co-fired to create a monolithic hard ceramic body (20) with metallized traces embedded in, and placed on exterior surfaces of, the hard ceramic body. The compact and rugged coil can be used in a variety of environments, including hostile conditions involving ultra-high vacuum, high temperatures, nuclear and optical radiation, chemical reactions, and physically demanding surroundings, occurring either individually or in combinations.

  17. Measurement of Apparent Thermal Conductivity of JSC-1A Under Ambient Pressure

    Science.gov (United States)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    The apparent thermal conductivity of JSC-1A lunar regolith simulant was measured experimentally using a cylindrical apparatus. Eleven thermocouples were embedded in the simulant bed to obtain the steady state temperature distribution at various radial, axial, and azimuthal locations. The high aspect ratio of a cylindrical geometry was proven to provide a one-dimensional, axisymmetric temperature field. A test series was performed at atmospheric pressure with varying heat fluxes. The radial temperature distribution in each test fit a logarithmic function, indicating a constant thermal conductivity throughout the soil bed. However, thermal conductivity was not constant between tests at different heat fluxes. This variation is attributed to stresses created by thermal expansion of the simulant particles against the rigid chamber wall. Under stress-free conditions (20 deg C), the data suggest a temperature independent apparent conductivity of 0.1961 +/- 0.0070 W/m/ deg C

  18. A New Vibration Measurement Procedure for On-Line Quality Control of Electronic Devices

    Directory of Open Access Journals (Sweden)

    Gian Marco Revel

    2002-01-01

    Full Text Available In this paper the problem of experimentally testing the mechanical reliability of electronic components for quality control is approached. In general, many tests are performed on electronic devices (personal computers, power supply units, lamps, etc., according to the relevant international standards (IEC, in order to verify their resistance to shock and vibrations, but these are mainly “go no-go” experiments, performed on few samples taken from the production batches.

  19. The Design of a Four Square Gear Tester for Noise and Vibration Measurements.

    Science.gov (United States)

    1986-12-01

    Point of Contact Contact Figure 1.2 Dynamic Force on Tooth Pair During Engagement ( Shigley , 1963) 6 from the compression of the air and oil mixture...Vibration Reduction, June 1974. 3. Shigley , J. E. Mechanical Engineering Design, McGraw-Hill, 1963. 4. Rosen, M. W. "The Noises of Two Spur Gear...Design, Vol. 56, No. 15, June 28, 1984. 23. Dayco Technical Center. Personal Correspondence, 1986. 24. Shigley , J. E. and L. D. Mitchell. Mechanical

  20. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2014-11-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the

  1. Vision-based measurement system for structural vibration monitoring using non-projection quasi-interferogram fringe density enhanced by spectrum correction method

    Science.gov (United States)

    Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Zhuang, Yizhou; Lu, Huancai; Fu, Xinbin

    2017-01-01

    A non-projection fringe vision measurement system suitable for vibration monitoring was proposed by using the concept of a 2D optical coherence vibration tomography (2D-OCVT) technique. An artificial quasi-interferogram fringe pattern (QIFP), similar to the interferogram of the 2D-OCVT system, was pasted onto the surface of a vibrating structure as a sensor. Image sequences of the QIFP were captured by a high-speed CMOS camera that worked as a detector. It was possible to obtain both the in-plane and out-of-plane vibration simultaneously. The in-plane vibration was obtained by tracking the center of the imaged QIFP using an image cross-correlation method, whilst the out-of-plane vibration was obtained from the changes in period density of the imaged QIFP. The influence of the noise sources from the CMOS image sensor, together with the effect of the imaging distance, the period density of the QIFP and also the key parameters of the fringe density enhanced by the spectrum correction method on the accuracy of the displacement measurement, were investigated by numerical simulations and experiments. Compared with the results from a conventional accelerometer-based measurement system, the proposed method was demonstrated to be an effective and accurate technique for measuring structural vibration without introducing any extra mass from the accelerometer. The significant advantages of this method include its simple installation and real-time dynamic response measurement capability, making the measurement system ideal for the low- and high-frequency vibration monitoring of engineering structures.

  2. Viscoelastic material properties’ identification using high speed full field measurements on vibrating plates

    Directory of Open Access Journals (Sweden)

    Pierron F.

    2010-06-01

    Full Text Available The paper presents an experimental application of a method leading to the identification of the elastic and damping material properties of isotropic vibrating plates. The theory assumes that the searched parameters can be extracted from curvature and deflection fields measured on the whole surface of the plate at two particular instants of the vibrating motion. The experimental application consists in an original excitation fixture, a particular adaptation of an optical full-field measurement technique, a data preprocessing giving the curvature and deflection fields and finally in the identification process using the Virtual Fields Method (VFM. The principle of the deflectometry technique used for the measurements is presented. First results of identification on an acrylic plate are presented and compared to reference values. Details about a new experimental arrangement, currently in progress, is presented. It uses a high speed digital camera to over sample the full-field measurements.

  3. Det ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Om begrebet "det ambiente", der beskriver, hvad der sker, når vi fornemmer baggrundsmusikkens diskrete beats, betragter udsigten gennem panoramavinduet eller tager 3D-brillerne på og læner os tilbage i biografsædet. Bogen analyserer, hvorfan ambiente oplevelser skabes, og hvilke konsekvenser det...

  4. Derecho Ambiental

    OpenAIRE

    2014-01-01

    Es indudable la relevancia para la vida del planeta proteger el ambiente. De ahí que a lo largo de las últimas decadas el derecho ambiental se ha consolidado como una nueva y vital rama del derecho público.

  5. Molecular order at polymer interfaces measured by broad-bandwidth vibrationally-resolved sum frequency generation spectroscopy.

    Science.gov (United States)

    Wilson, Philip T.; Briggman, Kimberly A.; Stephenson, John C.; Wallace, William E.; Richter, Lee J.

    2001-03-01

    Broad-bandwidth vibrationally-resolved sum frequency generation (VR-SFG)spectroscopy has been used to measure the molecular orientation distribution at polymer/dielectric interfaces. A novel three layer microcavity structure of polystyrene (i.e.,PS)/spin-on hydrogen silsesquioxane dielectric (i.e.,spin-on glass)/Au has been developed in which manipulation of Fresnel factors through the variation of dielectric thickness allows unique spectroscopic study of either the free or buried polymer interface. Chemically specific VR-SFG spectroscopy of the phenyl groups of PS reveals opposite absolute orientations of these groups for the two interfaces, each directed away from the bulk of the PS film.

  6. Obtaining and Estimating Low Noise Floors in Vibration Sensors

    DEFF Research Database (Denmark)

    Brincker, Rune; Larsen, Jesper Abildgaard

    2007-01-01

    For some applications like seismic applications and measuring ambient vibrations in structures, it is essential that the noise floors of the sensors and other system components are low and known to the user. Some of the most important noise sources are reviewed and it is discussed how the sensor...... can be designed in order to obtain a low noise floor. Techniques to estimate the noise floors for sensors are reviewed and are demonstrated on a commercial commonly used sensor for vibration testing. It is illustrated how the noise floor can be calculated using the coherence between simultaneous...

  7. Blind identification of full-field vibration modes of output-only structures from uniformly-sampled, possibly temporally-aliased (sub-Nyquist), video measurements

    Science.gov (United States)

    Yang, Yongchao; Dorn, Charles; Mancini, Tyler; Talken, Zachary; Nagarajaiah, Satish; Kenyon, Garrett; Farrar, Charles; Mascareñas, David

    2017-03-01

    Enhancing the spatial and temporal resolution of vibration measurements and modal analysis could significantly benefit dynamic modelling, analysis, and health monitoring of structures. For example, spatially high-density mode shapes are critical for accurate vibration-based damage localization. In experimental or operational modal analysis, higher (frequency) modes, which may be outside the frequency range of the measurement, contain local structural features that can improve damage localization as well as the construction and updating of the modal-based dynamic model of the structure. In general, the resolution of vibration measurements can be increased by enhanced hardware. Traditional vibration measurement sensors such as accelerometers have high-frequency sampling capacity; however, they are discrete point-wise sensors only providing sparse, low spatial sensing resolution measurements, while dense deployment to achieve high spatial resolution is expensive and results in the mass-loading effect and modification of structure's surface. Non-contact measurement methods such as scanning laser vibrometers provide high spatial and temporal resolution sensing capacity; however, they make measurements sequentially that requires considerable acquisition time. As an alternative non-contact method, digital video cameras are relatively low-cost, agile, and provide high spatial resolution, simultaneous, measurements. Combined with vision based algorithms (e.g., image correlation or template matching, optical flow, etc.), video camera based measurements have been successfully used for experimental and operational vibration measurement and subsequent modal analysis. However, the sampling frequency of most affordable digital cameras is limited to 30-60 Hz, while high-speed cameras for higher frequency vibration measurements are extremely costly. This work develops a computational algorithm capable of performing vibration measurement at a uniform sampling frequency lower than

  8. Vibration studies of a lightweight three-sided membrane suitable for space application

    Science.gov (United States)

    Sewell, J. L.; Miserentino, R.; Pappa, R. S.

    1983-01-01

    Vibration studies carried out in a vacuum chamber are reported for a three-sided membrane with inwardly curved edges. Uniform tension was transmitted by thin steel cables encased in the edges. Variation of ambient air pressure from atmospheric to near vacuum resulted in increased response frequencies and amplitudes. The first few vibration modes measured in a near vacuum are shown to be predictable by a finite element structural analysis over a range of applied tension loads. The complicated vibration mode behavior observed during tests at various air pressures is studied analytically with a nonstructural effective air-mass approximation. The membrane structure is a candidate for reflective surfaces in space antennas.

  9. A liquid nitrogen-free preconcentration unit for measurements of ambient N2O isotopomers by QCLAS

    Directory of Open Access Journals (Sweden)

    L. Emmenegger

    2009-12-01

    Full Text Available Important information about the biogeochemical cycle of nitrous oxide (N2O can be obtained by measuring its three main isotopomers, 14N15N16O, 15N14N16O, and 14N14N16O, and the respective site-specific isotope ratios δ15Nα and δ15Nβ. Absorption laser spectroscopy in the mid-infrared is a direct method for N2O isotopomer analysis, yet not sensitive enough for atmospheric N2O concentrations (320 ppb. To enable a fully-automated high precision N2O isotopomer analysis at ambient concentrations, we built and optimized a liquid nitrogen-free preconcentration unit to be coupled to a quantum cascade laser (QCL based spectrometer. Rigorous tests were conducted, using FTIR and quantum cascade laser absorption spectroscopy (QCLAS, to investigate recovery rates, conservation of isotopic signatures and spectral interferences after preconcentration. We achieve quantitative N2O recovery of >99% with only minor, statistically not significant isotopic fractionation and no relevant spectral interferences from other atmospheric constituents. The developed preconcentration unit also has the potential to be applied to other trace gases and their isotopic composition.

  10. Measuring Ambient Densities and Lorentz Factors of Gamma-Ray Bursts from GeV and Optical Observations

    CERN Document Server

    Hascoët, Romain; Beloborodov, Andrei M

    2015-01-01

    Fermi satellite discovered that cosmological gamma-ray bursts (GRBs) are accompanied by long GeV flashes. In two GRBs, an optical counterpart of the GeV flash has been detected. Recent work suggests that the GeV+optical flash is emitted by the external blast wave from the explosion in a medium loaded with copious $e^\\pm$ pairs. The full light curve of the flash is predicted by a first-principle radiative transfer simulation and can be tested against observations. Here we examine a sample of 7 bursts with best GeV+optical data and test the model. We find that the observed light curves are in agreement with the theoretical predictions and allow us to measure three parameters for each burst: the Lorentz factor of the explosion, its isotropic kinetic energy, and the external density. With one possible exception of GRB 090510 (which is the only short burst in the sample) the ambient medium is consistent with a wind from a Wolf-Rayet progenitor. The wind density parameter $A=\\rho r^2$ varies in the sample around $1...

  11. An Experimental Measurement on Laminar Burning Velocities and Markstein Length of Iso-Butane-Air Mixtures at Ambient Conditions

    Directory of Open Access Journals (Sweden)

    Yousif Alaeldeen Altag

    2016-01-01

    Full Text Available In the present work, experimental investigation on laminar combustion of iso-butane-air mixtures was conducted in constant volume explosion vessel. The experiments were conducted at wide range of equivalence ratios ranging between Ф = 0.6 and 1.4 and atmospheric pressure of 0.1 MPa and ambient temperature of 303K. Using spherically expanding flame method, flame parameters including stretched, unstretched flame propagation speeds, laminar burning velocities and Markstein length were calculated. For laminar burning velocities the method of error bars of 95% confidence level was applied. In addition, values of Markstein lengths were measured in wide range of equivalence ratios to study the influence of stretch rate on flame instability and burning velocity. It was found that the stretched flame speed and laminar burning velocities increased with equivalence ratios and the peak value was obtained at equivalence ratio of Ф = 1.1. The Markstein length decreased with the increases in equivalence ratios, which indicates that the diffusion thermal flame instability increased at high equivalence ratios in richer mixture side. However, the total deviations in the laminar burning velocities have discrepancies of 1.2-2.9% for all investigated mixtures.

  12. Ambient particulate air pollution and circulating antioxidant enzymes: A repeated-measure study in healthy adults in Beijing, China.

    Science.gov (United States)

    Wu, Shaowei; Wang, Bin; Yang, Di; Wei, Hongying; Li, Hongyu; Pan, Lu; Huang, Jing; Wang, Xin; Qin, Yu; Zheng, Chanjuan; Shima, Masayuki; Deng, Furong; Guo, Xinbiao

    2016-01-01

    The association of systemic antioxidant activity with ambient air pollution has been unclear. A panel of 40 healthy college students underwent repeated blood collection for 12 occasions under three exposure scenarios before and after relocating from a suburban area to an urban area in Beijing, China in 2010-2011. We measured various air pollutants including fine particles (PM2.5) and determined circulating levels of antioxidant enzymes extracellular superoxide dismutase (EC-SOD) and glutathione peroxidase 1 (GPX1) in the laboratory. An interquartile range increase of 63.4 μg/m(3) at 3-d PM2.5 moving average was associated with a 6.3% (95% CI: 0.6, 12.4) increase in EC-SOD and a 5.5% (95% CI: 1.3, 9.8) increase in GPX1. Several PM2.5 chemical constituents, including negative ions (nitrate and chloride) and metals (e.g., iron and strontium), were consistently associated with increases in EC-SOD and GPX1. Our results support activation of circulating antioxidant enzymes following exposure to particulate air pollution.

  13. Five-year measurements of ambient ammonia and its relationships with other trace gases at an urban site of Delhi, India

    Science.gov (United States)

    Saraswati; Sharma, S. K.; Mandal, T. K.

    2017-02-01

    In this study, we present the 5-year measurements of ambient ammonia (NH3), oxides of nitrogen (NO and NO2) and carbon monoxide (CO) along with the meteorological parameters at an urban site of Delhi, India from January 2011 to December 2015. The average mixing ratios of ambient NH3, NO, NO2 and CO over the entire period of observations were recorded as 19.3 ± 4.4 (ppb), 20.1 ± 5.9 (ppb), 18.6 ± 4.6 (ppb) and 1.8 ± 0.5 (ppm), respectively. The mixing ratios of NH3, NO, NO2 and CO were recorded highest during winter season, followed by summer and monsoon season. In the present case, a substantial seasonal variation of NH3 was observed during all the seasons except NO, NO2 and CO. The results emphasized that the traffic could be one of the significant sources of ambient NH3 at the urban site of Delhi as illustrated by positive correlations of NH3 with traffic related pollutants (NO x and CO). Surface wind as well as back trajectory analysis also supports the road side traffic and agricultural activities at the nearby area indicating possible major sources of ambient NH3 at observational site. Trajectory analysis, potential source contribution function and concentration weighted trajectory analysis indicated the surrounding nearby areas (NCR, Haryana, Punjab, Rajasthan and Uttar Pradesh) as a significant source region of ambient NH3 at the observational site of Delhi.

  14. 地铁列车振动和噪声源分析及减振降噪措施%Subway Train Vibration and Noise Source Analysis and Vibration and Noise Reduction Measures

    Institute of Scientific and Technical Information of China (English)

    吴刚

    2014-01-01

    地铁列车的振动与噪声涉及到多个学科,是一个整体的系统工程。研究列车振动和噪声控制首先需要了解噪声产生机理和噪声单元的声贡献,从而了解所有振动和噪声的特性,进而加强地铁机车的噪声控制和预测,减小地铁列车噪声污染。阐述了地铁列车振动和噪声源的产生原理,列举了现如今地铁列车噪声预测的方法、列车噪声的测量技术和减振降噪技术。%The vibration and noise subway train involves multiple disciplines, is a whole system works. Train vibration and noise control research first need to understand the mechanism of noise and noise sound unit contribution to understand the characteristics of all the vibration and noise, noise control and predict further strengthen metro locomotives, subway trains to reduce noise pollution. Describes the generation principle subway train vibration and noise sources, is now listed subway train noise prediction methods, measurement techniques and train noise vibration and noise reduction technology.

  15. 3D synthetic aperture PIV measurements from artificial vibrating vocal folds

    CERN Document Server

    Daily, Jesse; Belden, Jesse; Thomson, Scott; Truscott, Tadd

    2011-01-01

    During speech, air from the lungs is forced past the vocal folds which vibrate, producing sound. A pulsatile jet of air is formed downstream of the vibrating folds which interacts with the various structures in the airway. Currently, it is postulated that the way this jet interacts with the downstream structures in the airway directly affects the quality of human speech. In order to better understand this jet, it is desirable to visualize the jet in three dimensions. We present the results of a method that reconstructs the three dimensional velocity field using Synthetic aperture PIV (SAPIV) \\cite{Belden:2010}. SAPIV uses an array of high-speed cameras to artificially create a single camera with a variable focal length. This is accomplished by overlapping the images from the array to create a "focal stack". As the images are increasingly overlapped, more distant image planes come into focus. 3D PIV is then performed on the "refocused" focal stack to reconstruct the flow field in three dimensions. SAPIV has th...

  16. Det Ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Det ambiente er iscenesættelsen af en karakteristisk sanseoplevelse, der er kendetegnet ved fornemmelsen af at være omgivet. I dag bliver begrebet om det ambiente mest anvendt i forbindelse med musikgenren ’ambient musik’. Det ambiente er dog ikke essentielt knyttet til det musikalske, men må...... forstås som et betydeligt bredere fænomen i den moderne æstetiske kultur, der spiller en væsentlig rolle i oplevelsen af moderne transportformer, arkitektur, film, lydkunst, installationskunst og digitale multimedieiscenesættelser. En forståelse af det ambiente er derfor centralt for forståelsen af en...... moderne æstetiseret oplevelseskultur i almindelighed. Da det ambiente ikke hidtil har været gjort til genstand for en mere indgående teoretisk behandling, er der dog stor usikkerhed omkring, hvad fænomenet overhovedet indebærer. Hovedformålet med Det ambiente – Sansning, medialisering, omgivelse er derfor...

  17. Comparison of road traffic emission factors and testing by comparison of modelled and measured ambient air quality data.

    Science.gov (United States)

    Peace, H; Owen, B; Raper, D W

    2004-12-01

    This paper describes a comparison of three different sets of road traffic emission factors released by the UK government for use in air quality review and assessment. The air quality management process of review and assessment began in 1997 in the UK. During this period of ongoing review and assessment, a number of changes have been made to the emission factors provided by the government. The use of different sets of emission factors during the assessment process has lead to some inconsistencies between results from neighbouring local authorities and also between different modelling exercises undertaken by the same local authorities. One purpose of this study has been to compare three different sets of emission factors, including the most recent set, and to some degree highlight the uncertainty associated with the use of factors, such as the shift of emphasis in terms of emissions from cars to heavy goods vehicles. The most recently released emission factors are the most comprehensive to date, and theoretically more accurate than previous sets due to the larger database of emission measurements that they have been based on. Therefore, the most recent set of emission factors have been additionally used in a validation exercise between modelled and monitored data. Comparison has been undertaken with monitoring data at a variety of urban background, urban centre and roadside sites. This work has shown some differences between the predicted trends in emission factors and measured trends in ambient air pollution levels, especially at roadside sites, indicating an under-prediction of the air pollution contribution from road traffic.

  18. Investigation of multilayer printed circuit board (PCB) film warpage using viscoelastic properties measured by a vibration test

    Science.gov (United States)

    Joo, Sung-Jun; Park, Buhm; Kim, Do-Hyoung; Kwak, Dong-Ok; Song, In-Sang; Park, Junhong; Kim, Hak-Sung

    2015-03-01

    Woven glass fabric/BT (bismaleimide triazine) composite laminate (BT core), copper (Cu), and photoimageable solder resist (PSR) are the most widely used materials for semiconductors in electronic devices. Among these materials, BT core and PSR contain polymeric materials that exhibit viscoelastic behavior. For this reason, these materials are considered to have time- and temperature-dependent moduli during warpage analysis. However, the thin geometry of multilayer printed circuit board (PCB) film makes it difficult to identify viscoelastic characteristics. In this work, a vibration test method was proposed for measuring the viscoelastic properties of a multilayer PCB film at different temperatures. The beam-shaped specimens, composed of a BT core, Cu laminated on a BT core, and PSR and Cu laminated on a BT core, were used in the vibration test. The frequency-dependent variation of the complex bending stiffness was determined using a transfer function method. The storage modulus (E‧) of the BT core, Cu, and PSR as a function of temperature and frequency were obtained, and their temperature-dependent variation was identified. The obtained properties were fitted using a viscoelastic model for the BT core and the PSR, and a linear elastic model for the Cu. Warpage of a line pattern specimen due to temperature variation was measured using a shadow Moiré analysis and compared to predictions using a finite element model. The results provide information on the mechanism of warpage, especially warpage due to temperature-dependent variation in viscoelastic properties.

  19. Blind identification of full-field vibration modes from video measurements with phase-based video motion magnification

    Science.gov (United States)

    Yang, Yongchao; Dorn, Charles; Mancini, Tyler; Talken, Zachary; Kenyon, Garrett; Farrar, Charles; Mascareñas, David

    2017-02-01

    Experimental or operational modal analysis traditionally requires physically-attached wired or wireless sensors for vibration measurement of structures. This instrumentation can result in mass-loading on lightweight structures, and is costly and time-consuming to install and maintain on large civil structures, especially for long-term applications (e.g., structural health monitoring) that require significant maintenance for cabling (wired sensors) or periodic replacement of the energy supply (wireless sensors). Moreover, these sensors are typically placed at a limited number of discrete locations, providing low spatial sensing resolution that is hardly sufficient for modal-based damage localization, or model correlation and updating for larger-scale structures. Non-contact measurement methods such as scanning laser vibrometers provide high-resolution sensing capacity without the mass-loading effect; however, they make sequential measurements that require considerable acquisition time. As an alternative non-contact method, digital video cameras are relatively low-cost, agile, and provide high spatial resolution, simultaneous, measurements. Combined with vision based algorithms (e.g., image correlation, optical flow), video camera based measurements have been successfully used for vibration measurements and subsequent modal analysis, based on techniques such as the digital image correlation (DIC) and the point-tracking. However, they typically require speckle pattern or high-contrast markers to be placed on the surface of structures, which poses challenges when the measurement area is large or inaccessible. This work explores advanced computer vision and video processing algorithms to develop a novel video measurement and vision-based operational (output-only) modal analysis method that alleviate the need of structural surface preparation associated with existing vision-based methods and can be implemented in a relatively efficient and autonomous manner with little

  20. Electrostatic interaction between Interball-2 and the ambient plasma. 2. Influence on the low energy ion measurements with Hyperboloid

    Directory of Open Access Journals (Sweden)

    M. Hamelin

    Full Text Available The measurement of the thermal ion distributions in space is always strongly influenced by the ion motion through the complex 3D electrostatic potential structure built around a charged spacecraft. In this work, we study the related aberrations of the ion distribution detected on board, with special application to the case of the Hyperboloid instrument borne by the Interball-2 auroral satellite. Most of the time, the Interball-2 high altitude auroral satellite is charged at some non-negligible positive potential with respect to the ambient plasma, as shown in part 1; in consequence, the measurement of magnetospheric low energy ions (< 80 eV with the Hyperboloid instrument can be disturbed by the complex electric potential environment of the satellite. In the case of positive charging, as in previous experiments, a negative bias is applied to the Hyperboloid structure in order to reduce this effect and to keep as much as possible the opportunity to detect very low energy ions. Then, the ions reaching the Hyperboloid entrance windows would have travelled across a continuous huge electrostatic lens involving various spatial scales from ~ 10 cm (detector radius to ~ 10 m (satellite antennas. Neglecting space charge effects, we have computed the ion trajectories that are able to reach the Hyperboloid windows within their acceptance angles. There are three main results: (i for given values of the satellite potential, and for each direction of arrival (each window, we deduced the related energy cutoff; (ii we found that all ions in the energy channel, including the cutoff, can come from a large range of directions in the unperturbed plasma, especially when the solar panels or antennas act as electrostatic mirrors; (iii for higher energy channels, the disturbances are reduced to small angular shifts. Biasing of the aperture is not very effective with the Hyperboloid instrument (as on previous missions with instruments installed close to the spacecraft

  1. Seasonal Variation of Fungal Spores in Size-fractionated Ambient Particulate Matter in Beijing, China, Based on Molecular Tracer Measurements

    Science.gov (United States)

    Liang, L.; Engling, G.; He, K.

    2015-12-01

    Fungal aerosols were found to be the dominant fraction of biological aerosol components in the coarse mode in the atmosphere, influencing human health, the biosphere, atmospheric chemistry and climate. However, the total abundance of fungal spores in the atmosphere is rather uncertain and likely underestimated to a large extent by traditional Colony Forming Units (CFU) assays. Flow cytometry (FCM) was utilized in combination with fluorescent stains for the rapid counting of ambient fungal spores in this study. And, the sugar alcohols, mannitol and arabitol, proposed as molecular tracers for fungal aerosol were measured in PM2.5 and PM10 at an urban site in Beijing, China. The annual average concentrations of arabitol in PM2.5 and PM10 at the urban site were 7.4±9.4 ng m-3 and 21.0±20.4 ng m-3, and the respective mannitol concentrations were 10.3±9.5 ng m-3 and 31.9±26.9 ng m-3. Compared to PM2.5, the seasonal average concentrations of arabitol and mannitol in PM10 were varied more significantly. During summer and autumn higher arabitol and mannitol levels than during spring and winter were observed in coarse particles. Statistics analysis was further grouped into typical dry season (December 2010 to March 2011) and typical wet season (July 2011 to September 2011), revealed the different variation of fungal spores in different seasons. Moreover, the FCM results had significant positive correlation with the concentrations of the fungal tracers (R2 was 0.75 and 0.70 for arabitol and mannitol, respectively), supporting the utility of these sugar alcohols as effective fungal tracers.

  2. An Evaluation of Uncertainty Associated to Analytical Measurements of Selected Polycyclic Aromatic Compounds in Ambient Air; Estudio sobre las Incertidumbres Asociadas al Metodo de Determinacion de PAC's Seleccionados en Muestras de Aire Ambiente

    Energy Technology Data Exchange (ETDEWEB)

    Barrado, A. I.; Garcia, S.; Perez, R. M.

    2013-06-01

    This paper presents an evaluation of uncertainty associated to analytical measurement of eighteen polycyclic aromatic compounds (PACs) in ambient air by liquid chromatography with fluorescence detection (HPLC/FD). The study was focused on analyses of PM{sub 1}0, PM{sub 2}.5 and gas phase fractions. Main analytical uncertainty was estimated for eleven polycyclic aromatic hydrocarbons (PAHs), four nitro polycyclic aromatic hydrocarbons (nitro-PAHs) and two hydroxy polycyclic aromatic hydrocarbons (OH-PAHs) based on the analytical determination, reference material analysis and extraction step. Main contributions reached 15-30% and came from extraction process of real ambient samples, being those for nitro- PAHs the highest (20-30%). Range and mean concentration of PAC mass concentrations measured in gas phase and PM{sub 1}0/PM{sub 2}.5 particle fractions during a full year are also presented. Concentrations of OH-PAHs were about 2-4 orders of magnitude lower than their parent PAHs and comparable to those sparsely reported in literature. (Author) 7 refs.

  3. Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

    Science.gov (United States)

    Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Fridberger, Anders; Ren, Tianying; Wang, Ruikang; Jacques, Steven L.; Nuttall, Alfred L.

    2015-02-01

    In this study, we measure the in vivo apical-turn vibrations of the guinea pig organ of Corti in both axial and radial directions using phase-sensitive Fourier domain optical coherence tomography. The apical turn in guinea pig cochlea has best frequencies around 100 - 500 Hz which are relevant for human speech. Prior measurements of vibrations in the guinea pig apex involved opening the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here this limitation is overcome by measuring the vibrations through bone without opening the otic capsule. Furthermore, we have significantly reduced the surgery needed to access the guinea pig apex in the axial direction by introducing a miniature mirror inside the bulla. The method and preliminary data are discussed in this article.

  4. Quantitative measurement of the vibrational amplitude and phase in photorefractive time-average interferometry: A comparison with electronic speckle pattern interferometry

    DEFF Research Database (Denmark)

    Rohleder, Henrik; Petersen, Paul Michael; Marrakchi, A.

    1994-01-01

    and amplitude of the vibrating structure are demonstrated in photorefractive time average interferometry. The photorefractive interferometer is compared with the performance of a commercial electronic speckle pattern interferometer (ESPI). It is shown that the dynamic photorefractive holographic interferometer......Time-average interferometry is dealt with using four-wave mixing in photorefractive Bi12SiO20. By introducing a proper sinusoidal phase shift in the forward pump beam it is possible to measure the amplitude and phase everywhere on a vibrating object. Quantitative measurements of the phase...... improves the image quality considerably and is able to extend the measurable range for the acoustic vibration amplitude and frequency compared to what is obtainable with the ESPI equipment. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  5. 气体钻井钻柱振动特性及控制措施%Vibrating characteristics of drill string in gas drilling and its control measures

    Institute of Scientific and Technical Information of China (English)

    祝效华; 贾彦杰; 童华

    2012-01-01

    为解决气体钻井钻柱频繁失效的实际问题,综合考虑钻柱纵横扭耦合振动,根据气体钻井全井段钻柱系统动力学模型分析了气体钻井钻柱的振动特性,并从减振抑振角度提出了空气锤钻井工艺和采用减振减阻工具两种振动控制措施.以川西某实钻井气体钻进段为例,在利用美国ESSO公司现场数据验证全井段钻柱系统三向耦合振动力学模型可行性与结果可靠性的基础上,量化评价了常规气体钻井和采用振动控制措施气体钻井工艺的钻柱振动特性.对比分析表明,这两种工艺措施的减振抑振效果明显,不仅能够有效减弱气体钻井中下部钻柱的振动强度,而且使上部钻柱的动态应力也大大降低.%To solve an engineering problem of severe vibration and frequent failure of drill string in gas drilling, we analyzed vibrating behaviors of drill string during gas drilling based on a dynamic model for the whole-interval drill string in gas drilling, and presented two control measures against vibration in terms of anti-vibration and anti-drag, namely a well-drilling technique of air hammer and the adoption of anti-vibration and anti-drag tools. Taking a gas drilling section of a field well in west Sichuan as an example, we quantitatively evaluated vibrating characteristics of drill string both in conventional gas drilling and in drilling with vibration control measures, on condition that the feasibility and reliability of the triaxial coupling vibration mechanics model for the whole-interval drill string system were validated with the field data provided by the ESSO Production Co. A comparison indicates that these two technologic measures are of clear effectiveness in anti-vibration and anti-drag, they can not only effectively weaken the vibration intensity of the lower drill string in gas drilling but also remarkably reduce the dynamic stress of the upper drill string.

  6. Modal Parameters Estimation of Building Structures from Vibration Test Data Using Observability Measurement

    Directory of Open Access Journals (Sweden)

    Jae-Seung Hwang

    2015-01-01

    Full Text Available The load distribution to each mode of a structure under seismic loading depends on the modal participation factors and mode shapes and thus the exact estimation of modal participation factors and mode shapes is essential to analyze the seismic response of a structure. In this study, an identification procedure for modal participation factors and mode shapes from a vibration test is proposed. The modal participation factors and mode shapes are obtained from the relationship between observability matrices realized from the system identification. Using the observability matrices, it is possible to transform an arbitrarily identified state space model obtained from the experimental data into a state space model which is defined in a domain with physical meaning. Then, the modal participation factor can be estimated based on the transformation matrix between two state space models. The numerical simulation is performed to evaluate the proposed procedure, and the results show that the modal participation factor and mode shapes are estimated from the structural responses accurately. The procedure is also applied to the experimental data obtained from the shaking table test of a three-story shear building model.

  7. Prediction and Measurement of the Vibration and Acoustic Radiation of Panels Subjected to Acoustic Loading

    Science.gov (United States)

    Turner, Travis L.; Rizzi, Stephen A.

    1995-01-01

    Interior noise and sonic fatigue are important issues in the development and design of advanced subsonic and supersonic aircraft. Conventional aircraft typically employ passive treatments, such as constrained layer damping and acoustic absorption materials, to reduce the structural response and resulting acoustic levels in the aircraft interior. These techniques require significant addition of mass and only attenuate relatively high frequency noise transmitted through the fuselage. Although structural acoustic coupling is in general very important in the study of aircraft fuselage interior noise, analysis of noise transmission through a panel supported in an infinite rigid baffle (separating two semi-infinite acoustic domains) can be useful in evaluating the effects of active/adaptive materials, complex loading, etc. Recent work has been aimed at developing adaptive and/or active methods of controlling the structural acoustic response of panels to reduce the transmitted noise1. A finite element formulation was recently developed to study the dynamic response of shape memory alloy (SMA) hybrid composite panels (conventional composite panel with embedded SMA fibers) subject to combined acoustic and thermal loads2. Further analysis has been performed to predict the far-field acoustic radiation using the finite element dynamic panel response prediction3. The purpose of the present work is to validate the panel vibration and acoustic radiation prediction methods with baseline experimental results obtained from an isotropic panel, without the effect of SMA.

  8. 5t电液自由锻锤隔振基础及其振动测试%Vibration-isolated foundation of a 50kN electro-hydraulic free forging hammer and its vibration measurement

    Institute of Scientific and Technical Information of China (English)

    杨雪春; 杨国泰; 何成宏; 揭小平

    2001-01-01

    介绍了国产5t电液自由锻锤的隔振装置结构,对其基础振动进行了现场测试。测试结果表明,这种稳定性好、砧座水平可调节的板簧悬吊式砧下直接隔振装置,可使基础振动位移和振动加速度分别降至GB50040-96允许值的15%和3%以下,隔振效果显著。%The 1st home made suspended vibration-isolating installation with an anvil directly supported by leaf springs of a 5t electro-hydraulic free forging hammer has been introduced and measured resulting in that the installation will be satisfactory to stability and easy to horizontal alignment so that the vibration amplitude and vibration acceleration would be decreased to less than 15% and 3% respectively in permissible value according to GB50040-96 hence remarkable effectiveness in vibration isolation.

  9. Fault feature extraction of gearbox by using overcomplete rational dilation discrete wavelet transform on signals measured from vibration sensors

    Science.gov (United States)

    Chen, Binqiang; Zhang, Zhousuo; Sun, Chuang; Li, Bing; Zi, Yanyang; He, Zhengjia

    2012-11-01

    Gearbox fault diagnosis is very important for preventing catastrophic accidents. Vibration signals of gearboxes measured by sensors are useful and dependable as they carry key information related to the mechanical faults in gearboxes. Effective signal processing techniques are in necessary demands to extract the fault features contained in the collected gearbox vibration signals. Overcomplete rational dilation discrete wavelet transform (ORDWT) enjoys attractive properties such as better shift-invariance, adjustable time-frequency distributions and flexible wavelet atoms of tunable oscillation in comparison with classical dyadic wavelet transform (DWT). Due to these advantages, ORDWT is presented as a versatile tool that can be adapted to analysis of gearbox fault features of different types, especially in analyzing the non-stationary and transient characteristics of the signals. Aiming to extract the various types of fault features confronted in gearbox fault diagnosis, a fault feature extraction technique based on ORDWT is proposed in this paper. In the routine of the proposed technique, ORDWT is used as the pre-processing decomposition tool, and a corresponding post-processing method is combined with ORDWT to extract the fault feature of a specific type. For extracting periodical impulses in the signal, an impulse matching algorithm is presented. In this algorithm, ORDWT bases of varied time-frequency distributions and varied oscillatory natures are adopted, moreover an improved signal impulsiveness measure derived from kurtosis is developed for choosing optimal ORDWT bases that perfectly match the hidden periodical impulses. For demodulation purpose, an improved instantaneous time-frequency spectrum (ITFS), based on the combination of ORDWT and Hilbert transform, is presented. For signal denoising applications, ORDWT is enhanced by neighboring coefficient shrinkage strategy as well as subband selection step to reveal the buried transient vibration contents. The

  10. Measurement of dynamic patterns of an elastic membrane at bi-modal vibration using high speed electronic speckle pattern interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Preciado, Jorge Sanchez; Lopez, Carlos Perez; Santoyo, Fernando Mendoza [Grupo de Metrología Optica, Centro de Investigaciones en Óptica, A. C. Loma del Bosque 115, Col. Lomas del Campestre, León, Guanajuato, 37150 (Mexico)

    2014-05-27

    Implementing a hybrid arrangement of Laser Doppler Vibrometry (LDV) and high speed Electronic Speckle Pattern Interferometry (ESPI) we were able to measure the dynamic patterns of a flat rectangular elastic membrane clamped at its edges stimulated with the sum of two resonance frequencies. ESPI is a versatile technique to analyze in real-time the deformation of a membrane since its low computational cost and easy implementation of the optical setup. Elastic membranes present nonlinear behaviors when stimulated with low amplitude signals. The elastic membrane under test, with several non rational related vibrating modals below the 200 Hz, was stimulated with two consecutives resonant frequencies. The ESPI patterns, acquired at high speed rates, shown a similar behavior for the dual frequency stimulation as in the case of patterns formed with the entrainment frequency. We think this may be related to the effects observed in the application of dual frequency stimulation in ultrasound.

  11. Decay Rate Measurement of the First Vibrationally Excited State of MgH+ in a Cryogenic Paul Trap

    DEFF Research Database (Denmark)

    Versolato, O.O.; Schwarz, M.; Hansen, A.K.

    2013-01-01

    We present a method to measure the decay rate of the first excited vibrational state of polar molecular ions that are part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the |ν=1,J=1⟩X towards the |ν=0,J=0⟩X level in MgH+ by saturated laser...... excitation of the |ν=0,J=2⟩X-|ν=1,J=1⟩X transition followed by state selective resonance enhanced two-photon dissociation out of the |ν=0,J=2⟩X level. The experimentally observed rate of 6.32(0.69)  s-1 is in excellent agreement with the theory value of 6.13(0.03)  s-1 (this Letter). The technique enables...

  12. Vibrational properties of uracil

    Institute of Scientific and Technical Information of China (English)

    WANG Zhiping; ZHANG Fengshou; ZENG Xianghua; ZHOU Hongyu; GU Bin; CHENG Wei

    2006-01-01

    A semiempirical molecular dynamics model is developed to study the vibrational frequencies of uracil at very low kinetic temperature by using the Fourier transform of velocity autocorrelation function of trajectories of molecular dynamics simulations. The finite difference harmonic method is used to assign the vibrational frequency of each mode. The calculated frequencies are found to be in good agreement with experimental measurements. Moreover, we make up for the lost vibrational modes in experiments self-consistently. A total of 30 vibrational modes and their corresponding frequencies are reported.

  13. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    Directory of Open Access Journals (Sweden)

    D. A. Healy

    2014-02-01

    Full Text Available Primary biological aerosol particles (PBAP can contribute significantly to the coarse particle burden in many environments, may thus influence climate and precipitation systems as cloud nuclei, and can spread disease to humans, animals, and plants. Measurements of PBAP in natural environments taken at high time- and size- resolution are, however, sparse and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in south western Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of the waveband integrated bioaerosol sensor (WIBS-4 with the ultraviolet aerodynamic particle sizer (UV-APS and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behaviour, with increased fluorescent bioparticle concentrations at night when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each were correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.. The WIBS FL1 channel exhibited variable multi-modal distributions turning into a broad featureless single mode after averaging and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent

  14. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    Science.gov (United States)

    Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

    2014-08-01

    Primary biological aerosol particles (PBAPs) can contribute significantly to the coarse particle burden in many environments. PBAPs can thus influence climate and precipitation systems as cloud nuclei and can spread disease to humans, animals, and plants. Measurement data and techniques for PBAPs in natural environments at high time- and size resolution are, however, sparse, and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in southwestern Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of a waveband integrated bioaerosol sensor (WIBS-4) with a ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behavior, with increased fluorescent bioparticle concentrations at night, when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each was correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multimodal distributions turning into a broad featureless single mode after averaging, and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent

  15. Vibrationally-Fluidized Granular Flows: Impact and Bulk Velocity Measurements Compared with Discrete Element and Continuum Models

    Science.gov (United States)

    Hashemnia, Kamyar

    A new laser displacement probe was developed to measure the impact velocities of particles within vibrationally-fluidized beds. The sensor output was also used to measure bulk flow velocity along the probe window and to provide a measure of the media packing. The displacement signals from the laser sensors were analyzed to obtain the probability distribution functions of the impact velocity of the particles. The impact velocity was affected by the orientation of the laser probe relative to the bulk flow velocity, and the density and elastic properties of the granular media. The impact velocities of the particles were largely independent of their bulk flow speed and packing density. Both the local impact and bulk flow velocities within a tub vibratory finisher were predicted using discrete element modelling (DEM) and compared to the measured values for spherical steel media. It was observed that the impact and bulk flow velocities were relatively insensitive to uncertainties in the contact coefficients of friction and restitution. It was concluded that the predicted impact and bulk flow velocities were dependent on the number of layers in the model. Consequently, the final DE model mimicked the key aspects of the experimental setup, including the submerged laser sensor. The DE method predictions of both impact velocity and bulk flow velocity were in reasonable agreement with the experimental measurements, with maximum differences of 20% and 30%, respectively. Discrete element modeling of granular flows is effective, but requires large numerical models. In an effort to reduce computational effort, this work presents a finite element (FE) continuum model of a vibrationally-fluidized granular flow. The constitutive equations governing the continuum model were calibrated using the discrete element method (DEM). The bulk flow behavior of the equivalent continuum media was then studied using both Lagrangian and Eulerian FE formulations. The bulk flow velocities predicted

  16. Vibrational Spectroscopy of Biomembranes

    Science.gov (United States)

    Schultz, Zachary D.; Levin, Ira W.

    2011-07-01

    Vibrational spectroscopy, commonly associated with IR absorption and Raman scattering, has provided a powerful approach for investigating interactions between biomolecules that make up cellular membranes. Because the IR and Raman signals arise from the intrinsic properties of these molecules, vibrational spectroscopy probes the delicate interactions that regulate biomembranes with minimal perturbation. Numerous innovative measurements, including nonlinear optical processes and confined bilayer assemblies, have provided new insights into membrane behavior. In this review, we highlight the use of vibrational spectroscopy to study lipid-lipid interactions. We also examine recent work in which vibrational measurements have been used to investigate the incorporation of peptides and proteins into lipid bilayers, and we discuss the interactions of small molecules and drugs with membrane structures. Emerging techniques and measurements on intact cellular membranes provide a prospective on the future of vibrational spectroscopic studies of biomembranes.

  17. Ambient intelligence

    OpenAIRE

    Sanders, David; Gegov, Alexander

    2006-01-01

    This paper considers some history and the state of the art of Ambient Intelligence and from that seeks to identify new topics and future work. Ubiquitous computing, communications, human-centric computer interaction, embedded systems, context awareness, adaptive systems and distributed device networks are considered.

  18. Application of DALYs in Measuring Health Effect of Ambient Air Pollution: A Case Study in Shanghai, China

    Institute of Scientific and Technical Information of China (English)

    YUN-HUI ZHANG; CHANG-HONG CHEN; GUO-HAI CHEN; GUI-XIANG SONG; BING-HENG CHEN; QING-YAN FU; HAI-DONG KAN

    2006-01-01

    To investigate the effect of ambient air pollution on human health and the subsequent disability-adjusted life years (DALYs) lost in Shanghai. Methods We used epidemiology-based exposure-response functions to calculate the attributable number of cases due to air pollution in Shanghai in 2000, and then we estimated the corresponding DALYs lost in Shanghai based on unit DALYs values of the health consequences. Results Ambient air pollution caused 103 064 DALYs lost in Shanghai in 2000. Among all the health endpoints, premature deaths and chronic bronchitis predominated in the value of total DALYs lost. Conclusion The air pollution levels have an adverse effect on the general population health and strengthen the rationale for limiting the levels of air pollution in outdoor air in Shanghai.

  19. GPR measurements and estimation for road subgrade damage caused by neighboring train vibration load

    Science.gov (United States)

    Zhao, Yonghui; Lu, Gang; Ge, Shuangcheng

    2015-04-01

    Generally, road can be simplified as a three-layer structure, including subgrade, subbase and pavement. Subgrade is the native material underneath a constructed road. It is commonly compacted before the road construction, and sometimes stabilized by the addition of asphalt, lime or other modifiers. As the mainly supporting structure, subgrade damage would lead in pavement settlement, displacement and crack. Assessment and monitoring of the subgrade condition currently involves trial pitting and subgrade sampling. However there is a practical limit on spatial density at which trail pits and cores can be taken. Ground penetrating radar (GPR) has been widely used to characterize highway pavement profiling, concrete structure inspection and railroad track ballast estimation. GPR can improve the economics of road maintenance. Long-term train vibration load might seriously influence the stability of the subgrade of neighboring road. Pavement settlement and obvious cracks have been found at a municipal road cross-under a railway with culvert box method. GPR test was conducted to estimate the subgrade and soil within 2.0 m depth for the further road maintenance. Two survey lines were designed in each lane, and total 12 GPR sections have been implemented. Considering both the penetrating range and the resolution, a antenna with a 500 MHz central frequency was chosen for on-site GPR data collection. For data acquisition, we used the default operating environment and scanning parameters for the RAMAC system: 60kHz transmission rate, 50 ns time window, 1024 samples per scan and 0.1 m step-size. Continuous operation was used; the antenna was placed on the road surface and slowly moved along the road. The strong surrounding disturbance related to railroad and attachments, might decrease the reliability of interpretation results. Some routine process methods (including the background removing, filtering) have been applied to suppress the background noise. Additionally, attribute

  20. Under the Cover of Darkness: Using Daylight Saving Time to Measure How Ambient Light Influences Criminal Behavior

    OpenAIRE

    Jennifer L. Doleac; Nicholas J. Sanders

    2012-01-01

    We use data from the National Incidence-Based Reporting System (NIBRS) to examine how the probability of getting caught when committing a crime, proxied by ambient daylight, impacts criminal activity. We exploit the existence of daylight saving time (DST) to provide within-hour exogenous shock to daylight, using both the discontinuous nature of DST as well as the 2007 extension of DST as sources of variation. Further, we consider both crimes where darkness is likely to play a role in avoiding...

  1. Measurement of 3-D Vibrational Motion by Dynamic Photogrammetry Using Least-Square Image Matching for Sub-Pixel Targeting to Improve Accuracy.

    Science.gov (United States)

    Lee, Hyoseong; Rhee, Huinam; Oh, Jae Hong; Park, Jin Ho

    2016-03-11

    This paper deals with an improved methodology to measure three-dimensional dynamic displacements of a structure by digital close-range photogrammetry. A series of stereo images of a vibrating structure installed with targets are taken at specified intervals by using two daily-use cameras. A new methodology is proposed to accurately trace the spatial displacement of each target in three-dimensional space. This method combines the correlation and the least-square image matching so that the sub-pixel targeting can be obtained to increase the measurement accuracy. Collinearity and space resection theory are used to determine the interior and exterior orientation parameters. To verify the proposed method, experiments have been performed to measure displacements of a cantilevered beam excited by an electrodynamic shaker, which is vibrating in a complex configuration with mixed bending and torsional motions simultaneously with multiple frequencies. The results by the present method showed good agreement with the measurement by two laser displacement sensors. The proposed methodology only requires inexpensive daily-use cameras, and can remotely detect the dynamic displacement of a structure vibrating in a complex three-dimensional defection shape up to sub-pixel accuracy. It has abundant potential applications to various fields, e.g., remote vibration monitoring of an inaccessible or dangerous facility.

  2. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, Edward L.; Ziemba, L. D.

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  3. Spectral Aerosol Extinction (SpEx: a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    Directory of Open Access Journals (Sweden)

    C. E. Jordan

    2015-06-01

    Full Text Available We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300–700 nm wavelength range, the Spectral Aerosol Extinction (SpEx instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström Exponents. Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  4. Blade Vibration Measurement System for Characterization of Closely Spaced Modes and Mistuning Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I project successfully demonstrated that the advanced non-contacting stress measurement system (NSMS) was able to address closely spaced modes and...

  5. Theoretical and experimental limitations of accelerometric measurements of vibrational intensity in beams

    Science.gov (United States)

    Carniel, Xavier

    1988-06-01

    Error sources and their influence on the precision of bending wave measurements of beams are reviewed. Optimal transducer spacings for various wavelengths and structure geometries are presented. It is found that the accuracy of the transducers is limited primarily by phase mismatch, particularly in low-frequency regions where phase gradients are weak. Problems in the phase calibration of accelerometers are pointed out. The results allow spatial and frequency parameters to be determined for a given structure and required measurement precision.

  6. Natural vibration dynamics of Rainbow Bridge, Utah

    Science.gov (United States)

    Moore, J. R.; Thorne, M. S.; Wood, J. R.; Doyle, S.; Stanfield, E.; White, B.

    2015-12-01

    We measured resonant frequencies of Rainbow Bridge, Utah, one of the world's longest rock spans, during a field experiment recording ambient vibration data. Measurements were generated over 20 hours on March 23-24, 2015 using two broadband three-component seismometers placed on the bridge, and compared to concurrent data from nearby reference stations 20 and 220 m distant. We identified seven distinct modes of vibration for Rainbow Bridge between 1 and 6 Hz. Data for each resonant frequency was then analyzed to determine the frequency-dependent polarization vector in an attempt to clarify mode shapes; e.g. the fundamental mode represents out-of-plane horizontal flexure. We compared experimental data to results of 3D numerical modal analysis, using a new photogrammetric model of Rainbow Bridge generated in this study imported into COMSOL Multiphysics. Results compare well with measured data for seven of the first eight modeled modes, matching vibrational frequencies and polarization orientations generally within 10%. Only predicted mode 6 was not explicitly apparent in our experimental data. Large site-to-reference spectral ratios resolved from experimental data indicate high amplification on the bridge as compared to nearby bedrock.

  7. Vibration measurements of the Daniel K. Inouye Solar Telescope mount, Coudé rotator, and enclosure assemblies

    Science.gov (United States)

    McBride, William R.; McBride, Daniel R.

    2016-08-01

    The Daniel K. Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world, with a 4-meter off-axis primary mirror and 16 meter rotating Coudé laboratory within the telescope pier. The off-axis design requires a mount similar to an 8-meter on-axis telescope. Both the telescope mount and the Coudé laboratory utilize a roller bearing technology in place of the more commonly used hydrostatic bearings. The telescope enclosure utilizes a crawler mechanism for the altitude axis. As these mechanisms have not previously been used in a telescope, understanding the vibration characteristics and the potential impact on the telescope image is important. This paper presents the methodology used to perform jitter measurements of the enclosure and the mount bearings and servo system in a high-noise environment utilizing seismic accelerometers and high dynamic-range data acquisition equipment, along with digital signal processing (DSP) techniques. Data acquisition and signal processing were implemented in MATLAB. In the factory acceptance testing of the telescope mount, multiple accelerometers were strategically located to capture the six axes-of-motion of the primary and secondary mirror dummies. The optical sensitivity analysis was used to map these mirror mount displacements and rotations into units of image motion on the focal plane. Similarly, tests were done with the Coudé rotator, treating the entire rotating instrument lab as a rigid body. Testing was performed by recording accelerometer data while the telescope control system performed tracking operations typical of various observing scenarios. The analysis of the accelerometer data utilized noise-averaging fast Fourier transform (FFT) routines, spectrograms, and periodograms. To achieve adequate dynamic range at frequencies as low as 3Hz, the use of special filters and advanced windowing functions were necessary. Numerous identical automated tests were compared to identify and select the data sets

  8. Merenje torzionih oscilacija pomoću mernih traka / Measurement of torsional vibrations by using strain gages

    Directory of Open Access Journals (Sweden)

    Dragan Trifković

    2005-05-01

    Full Text Available U ovom radu prikazan je metod merenja torzionih oscilacija mehaničkih sistema na osnovu merenja torzionog napona pomoću mernih traka. Ovaj metod naročito je pogodan za proveru nivoa naprezanja elemenata sistema, koji prenose promenljive obrtne momente i torziono osciluju. Osim toga, mogu se određivati i kritične brzine obrtanja elemenata sistema, pri kojima se javljaju rezonantna naprezanja i otkazi sistema, kao što su: pojačana buka, trošenje zupčanika, zamor materijala, oštećenja i lomovi vratila, spojnica i si. Predložen je merni lanac u kojem centralno mesto zauzima suvremeni mobilni merni sistem Spider 8, koji omogućava merenje, obradu i prikaz rezultata pomoću računara. / In this work the measuring method of torsion vibrations is presented according to the measurement of torsion stress using strain gages. This method is particularly suitable in checking the system elements strain level that transfers changeable torsion moments and oscillate torsionally. Besides that, the system elements critical velocity rotation can be estimated, folio-wed by the resonant strain and problems in the function of that system such as: amplified noise, -wearing-out of gears, fatigue crack, damage and break of shafts and junctions etc. The measuring chain is proposed in -which the central part is a contemporary mobile system Spider 8, -which enables measurement, processing and displays measured results on a computer.

  9. Vibrational power flow and structural intensity: Measurements and limitations at low frequencies

    DEFF Research Database (Denmark)

    Ohlrich, Mogens

    1991-01-01

    The cross-spectral methods and their sensitivity to phase errors are investigated for the two and four-accelerometer arrays. From experiments on a beam structure it is attempted to verify the influence of phase errors and to determine the usable frequency ranges of the two methods. Measurements a...

  10. A new high transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

    Science.gov (United States)

    Franchin, A.; Downard, A. J.; Kangasluoma, J.; Nieminen, T.; Lehtipalo, K.; Steiner, G.; Manninen, H. E.; Petäjä, T.; Flagan, R. C.; Kulmala, M.

    2015-06-01

    Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all DMAs have an unfavorable potential gradient at the outlet (e.g. long column, Vienna type) or at the inlet (nano-radial DMA). This feature prevents them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in mobility equivalent diameter (corresponding to 1.2 × 10-4 m2 V-1 s-1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a Particle Size Magnifier (PSM) and a booster Condensation Particle Counter (CPC) as a counter. With this setup, we were able to measure size distributions of ions between 1.3 and 6 nm, corresponding to a mobility range from 1.2 × 10-4 to 5.8 × 10-6 m2 V-1 s-1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD 7 measurement campaign at CERN. We achieved a higher size resolution than techniques currently used in field measurements, and maintained a good transmission efficiency at moderate inlet and sheath air flows (2.5 and 30 LPM, respectively). In this paper, by measuring size distribution at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 μm.

  11. Vibration Propagation in Spider Webs

    Science.gov (United States)

    Hatton, Ross; Otto, Andrew; Elias, Damian

    Due to their poor eyesight, spiders rely on web vibrations for situational awareness. Web-borne vibrations are used to determine the location of prey, predators, and potential mates. The influence of web geometry and composition on web vibrations is important for understanding spider's behavior and ecology. Past studies on web vibrations have experimentally measured the frequency response of web geometries by removing threads from existing webs. The full influence of web structure and tension distribution on vibration transmission; however, has not been addressed in prior work. We have constructed physical artificial webs and computer models to better understand the effect of web structure on vibration transmission. These models provide insight into the propagation of vibrations through the webs, the frequency response of the bare web, and the influence of the spider's mass and stiffness on the vibration transmission patterns. Funded by NSF-1504428.

  12. [Research of working condition monitoring and analyzing system for rotating anode X-ray tube based on the vibration measurement].

    Science.gov (United States)

    Wu, Hao; Wang, Weidong; Yan, Yong; Zhang, Shuai; Zu, Hefei; Chen, Weibin

    2011-01-01

    A non-invasive detecting and analyzing method which used to monitor the working condition of rotating anode X-ray was proposed. Based on the NI development environment, accelerometer, 24-bit high resolution data acquisition card and personal computer were connected to construct the system for collecting the vibration signal of X-ray tube. Results demonstrate that the system could acquire and store the vibration data of X-ray tube quickly and efficiently. The characteristics of vibration, were extracted and processed, which proposed a new approach to detect the malfunction of rotating anode X-ray early and effectively.

  13. A new high transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

    Directory of Open Access Journals (Sweden)

    A. Franchin

    2015-06-01

    from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high transmission inlet for the Caltech nano-radial DMA (nRDMA that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in mobility equivalent diameter (corresponding to 1.2 × 10−4 m2 V−1 s−1 in electrical mobility. We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a Particle Size Magnifier (PSM and a booster Condensation Particle Counter (CPC as a counter. With this setup, we were able to measure size distributions of ions between 1.3 and 6 nm, corresponding to a mobility range from 1.2 × 10−4 to 5.8 × 10−6 m2 V−1 s−1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD 7 measurement campaign at CERN. We achieved a higher size resolution than techniques currently used in field measurements, and maintained a good transmission efficiency at moderate inlet and sheath air flows (2.5 and 30 LPM, respectively. In this paper, by measuring size distribution at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 μm.

  14. Noiseless Quantum Measurement and Squeezing of Microwave Fields Utilizing Mechanical Vibrations.

    Science.gov (United States)

    Ockeloen-Korppi, C F; Damskägg, E; Pirkkalainen, J-M; Heikkilä, T T; Massel, F; Sillanpää, M A

    2017-03-10

    A process which strongly amplifies both quadrature amplitudes of an oscillatory signal necessarily adds noise. Alternatively, if the information in one quadrature is lost in phase-sensitive amplification, it is possible to completely reconstruct the other quadrature. Here we demonstrate such a nearly perfect phase-sensitive measurement using a cavity optomechanical scheme, characterized by an extremely small noise less than 0.2 quanta. The device also strongly squeezes microwave radiation by 8 dB below vacuum. A source of bright squeezed microwaves opens up applications in manipulations of quantum systems, and noiseless amplification can be used even at modest cryogenic temperatures.

  15. Gear Damage Detection Integrating Oil Debris and Vibration Measurement Technologies Developed

    Science.gov (United States)

    Gyekeyeski, Andrew L.; Sawicki, Jerzy T.

    2001-01-01

    The development of highly reliable health-monitoring systems is one technology area recommended for reducing the number of helicopter accidents. Helicopter transmission diagnostics are an important part of a helicopter health-monitoring system because helicopters depend on the power train for propulsion, lift, and flight maneuvering. One technique currently being tested for increasing the reliability and decreasing the false alarm rate of current transmission diagnostic tools is the replacement of simple single-sensor limits with multisensor systems integrating different measurement technologies.

  16. 光学系统受迫振动的激光测量方法%Laser measurement method of forced vibration in optical systems

    Institute of Scientific and Technical Information of China (English)

    王大辉; 赵学庆; 张永生; 孙昱薇; 胡云; 易爱平; 赵军

    2012-01-01

    将激光信号与高帧频CCD结合,解决了光学系统中振动信号和激光信号之间的转换问题,不仅能够测量振动对系统光束指向稳定性的影响,而且能够得到振动信号本身的频率特性.利用该方法对振源为150 Hz和200 Hz两种条件下的光学系统受迫振动进行测量,得到了与输入信号相吻合的振动信号属性.通过实验与分析得知:时域振幅测量精度为6.25 μm,频域分辨力为2 Hz,方法简便高效,测量结果准确,已应用于角多路准分子激光主振荡功率放大器系统打靶试验平台光束指向稳定性的研究中.%A forced vibration measurement method by laser combining the laser signal and high frequency CCD in optical systems is introduced. The method solves the conversion problem between the vibration signal and laser signal in optical systems, which can not only measure the impact of vibration on the beam stability, but also acquire the frequency characteristics of vibration signals. Forced vibration in an optical system is measured when the frequencies of vibration signals are 150 Hz and 200 Hz by using the method and the attributes of the vibration signals obtained fits those of the input signals. Test and analysis results demonstrate that the method has a time amplitude uncertainty of 6. 25 μm and frequency resolution of 2 Hz. The handy and efficient method, whose measurement is precise, has been applied to the beam pointing stability study of the multiplexing excimer MOP A laser targeting test platform accordingly.

  17. Air Pollution and Preterm Birth in the U.S. State of Georgia (2002–2006): Associations with Concentrations of 11 Ambient Air Pollutants Estimated by Combining Community Multiscale Air Quality Model (CMAQ) Simulations with Stationary Monitor Measurements

    Science.gov (United States)

    Hao, Hua; Chang, Howard H.; Holmes, Heather A.; Mulholland, James A.; Klein, Mitch; Darrow, Lyndsey A.; Strickland, Matthew J.

    2015-01-01

    Background: Previous epidemiologic studies suggest associations between preterm birth and ambient air pollution. Objective: We investigated associations between 11 ambient air pollutants, estimated by combining Community Multiscale Air Quality model (CMAQ) simulations with measurements from stationary monitors, and risk of preterm birth (Darrow LA, Strickland MJ. 2016. Air pollution and preterm birth in the U.S. state of Georgia (2002–2006): associations with concentrations of 11 ambient air pollutants estimated by combining Community Multiscale Air Quality Model (CMAQ) simulations with stationary monitor measurements. Environ Health Perspect 124:875–880; http://dx.doi.org/10.1289/ehp.1409651 PMID:26485731

  18. Some analytical expressions to measure the accuracy of the “equivalent von Mises stress” in vibration multiaxial fatigue

    Science.gov (United States)

    Benasciutti, D.

    2014-09-01

    The “equivalent von Mises stress” (EVMS) was first proposed in 1994 by Preumont and co-workers as a frequency domain reformulation of von Mises stress, for the fatigue analysis of vibrating structures under multiaxial random stresses. The EVMS criterion is a simple, but very powerful tool to estimate fatigue damage with time domain analysis of simulated stress histories, or frequency domain evaluation by spectral methods. Despite its simplicity, the EVMS criterion is based on some inherent assumptions, which may lead to inaccurate damage estimations in some particular conditions (e.g. materials with very different axial/bending and torsion S-N curves). This paper aims to derive some analytical expressions to measure the accuracy of EVMS criterion for various combinations of material fatigue properties and loading conditions (e.g. combined axial/bending and torsion loadings). These expressions constitute an original contribution, as similar analytical approaches have not been proposed in literature. The accuracy of EVMS approach is then tested with typical material fatigue properties from literature. The range of applicability of EVMS criterion is then be identified for specified intervals and combinations of S-N parameters.

  19. Historical Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Historical Ambient Air Quality Data Inventory contains measured and estimated data on ambient air pollution for use in assessing air quality, assisting in...

  20. Research on the Vibration Serviceability of a Cable-stayed Footbridge Based on Field Measurement%基于实测响应的斜拉人行桥人致振动舒适度研究

    Institute of Scientific and Technical Information of China (English)

    陈波; 王鑫; 刘浩; 胡健; 张文龙; 黄雨田

    2013-01-01

    The vibration serviceability of a large span cable-stayed footbridge was actively investigated.The basic information of a real large span cable-stayed footbridge was firstly introduced.The analytical model of the footbridge was established based on finite element method and the dynamic properties are computed.The dynamic properties of the footbridge were measured subjected to ambient excitation.In addition,the dynamic responses of the footbridge under humaninduced loading were also tested.The vibration serviceability of the cable-stayed footbridge was evaluated in line with the British Standard BS5400.The made observations indicate that the dynamic responses of the footbridge is obvious and discomfort feeling can be observed to some extent.%研究了大跨轻柔斜拉人行桥人致振动舒适度问题.基于有限元方法建立了某大跨度斜拉人行桥的分析模型并进行了动力特性分析;进行了该桥在环境脉动激励作用下的动力特性实测和不同人行荷载作用下的动力响应测试;依据英国规范BS5400评价了该桥的振动舒适度状况.结果表明,该桥在人行荷载作用下存在较为显著的振动响应和一定程度的振动舒适度问题.

  1. Validation and application of cavity-enhanced, near-infrared tunable diode laser absorption spectrometry for measurements of methane carbon isotopes at ambient concentrations.

    Science.gov (United States)

    Mortazavi, Behzad; Wilson, Benjamin J; Dong, Feng; Gupta, Manish; Baer, Doug

    2013-10-15

    Methane is an effective greenhouse gas but has a short residence time in the atmosphere, and therefore, reductions in emissions can alleviate its greenhouse gas warming effect within a decadal time frame. Continuous and high temporal resolution measurements of methane concentrations and carbon isotopic ratios (δ(13)CH4) can inform on mechanisms of formation, provide constraints on emissions sources, and guide future mitigation efforts. We describe the development, validation, and deployment of a cavity-enhanced, near-infrared tunable diode laser absorption spectrometry system capable of quantifying δ(13)CH4 at ambient methane concentrations. Laboratory validation and testing show that the instrument is capable of operating over a wide dynamic range of methane concentration and provides a measurement precision for δ(13)CH4 of better than ± 0.5 ‰ (1σ) over 1000 s of data averaging at ambient methane concentrations. The analyzer is accurate to better than ± 0.5 ‰, as demonstrated by measurements of characterized methane/air samples with minimal dependence (methane concentration. Deployment of the instrument at a marsh over multiple days demonstrated how methane fluxes varied by an order of magnitude over 2 day deployment periods, and showed a 17 ‰ variability in δ(13)CH4 of the emitted methane during the growing season.

  2. Vibrating wire alignment technique

    CERN Document Server

    Xiao-Long, Wang; lei, Wu; Chun-Hua, Li

    2013-01-01

    Vibrating wire alignment technique is a kind of method which through measuring the spatial distribution of magnetic field to do the alignment and it can achieve very high alignment accuracy. Vibrating wire alignment technique can be applied for magnet fiducialization and accelerator straight section components alignment, it is a necessary supplement for conventional alignment method. This article will systematically expound the international research achievements of vibrating wire alignment technique, including vibrating wire model analysis, system frequency calculation, wire sag calculation and the relation between wire amplitude and magnetic induction intensity. On the basis of model analysis this article will introduce the alignment method which based on magnetic field measurement and the alignment method which based on amplitude and phase measurement. Finally, some basic questions will be discussed and the solutions will be given.

  3. Vibration Analysis of a Residential Building

    Directory of Open Access Journals (Sweden)

    Sampaio Regina Augusta

    2015-01-01

    Full Text Available The aim of this paper is to present the results of a study regarding vibration problems in a 17 storey residential building during pile driving in its vicinity. The structural design of the building was checked according to the Brazilian standards NBR6118 and NBR6123, and using commercial finite element software. An experimental analysis was also carried out using low frequency piezo-accelerometers attached to the building structure. Structure vibrations were recorded under ambient conditions. Four monitoring tests were performed on different days. The objective of the first monitoring test was an experimental modal analysis. To obtain de modal parameters, data was processed in the commercial software ARTEMIS employing two methods: the Stochastic Subspace Identification and the Frequency Domain Decomposition. Human comfort was investigated considering the International Standard ISO 2631. The Portuguese standard, NP2074, was also used as a reference, since it aims to limit the adverse effects of vibrations in structures caused by pile driving in the vicinity of the structure. The carried out experimental tests have shown that, according to ISO2301, the measure vibration levels are above the acceptance limits. However, velocity peaks are below the limits established by NP2074. It was concluded that, although the structure has adequate capacity to resist internal forces according to normative criteria, it has low horizontal stiffness, which could be verified by observing the vibration frequencies and mode shapes obtained with the finite element models, and its similarity with the experimental results. Thus, the analyses indicate the occurrence of discomfort by the residents.

  4. Detection of the local sliding in the tyre-road contact by measuring vibrations on the inner liner of the tyre

    Science.gov (United States)

    Niskanen, Arto J.; Tuononen, Ari J.

    2017-04-01

    Intelligent tyres can provide vital information from the tyre-road contact, especially for autonomous cars and intelligent infrastructure. In this paper, the acceleration measured on the inner liner of a tyre is used to detect the local sliding in the tyre-road contact. The Hilbert–Huang transform is utilized to extract the relevant vibration components and localize them in the wheel rotation angle domain. The energy of the vibration in the trailing part of the contact is shown to increase in low-friction conditions which can be related to the sliding of the tread part as a result of the shear stresses exceeding the local friction limit. To separate the effect of the surface roughness and the friction, different road surfaces were used in the measurements. In addition, the effects of different driving manoeuvres on the measured accelerations and the propagation of the sliding zone in the contact patch during braking are illustrated.

  5. Ambient measurements of aromatic and oxidized VOCs by PTR-MS and GC-MS: intercomparison between four instruments in a boreal forest in Finland

    Directory of Open Access Journals (Sweden)

    M. K. Kajos

    2015-04-01

    Full Text Available Proton transfer reaction mass spectrometry (PTR-MS and gas chromatography mass spectrometry GC-MS allow real-time measurements of various atmospheric volatile organic compounds (VOC. By taking parallel measurements in ambient conditions, two PTR-MSs and two GC-MSs were studied for their ability to measure methanol, acetaldehyde, acetone, benzene and toluene. The measurements were conducted at a rural boreal forest site in southern Finland between 13 April and 14 May 2012. This paper presents correlations and possible biases between the concentrations measured using the four instruments. This paper presents correlations and possible biases between the concentrations measured using the four instruments. A very good correlation was found for benzene and acetone measurements between all instruments (the mean R value was 0.88 for both compounds, while for acetaldehyde and toluene the correlation was weaker (with a mean R value of 0.50 and 0.62, respectively. For some compounds, notably for methane, there were considerable systematic differences in the mixing ratios measured by the different instruments, despite the very good correlation between the instruments (mean R = 0.90. The systematic difference arises as a difference in the linear regression slope between measurements conducted between instruments, rather than as an offset. This mismatch indicates that the systematic uncertainty in the sensitivity of a given instrument can lead to an uncertainty of 50–100% in the methanol emissions measured by commonly used methods.

  6. The effects of vibration-reducing gloves on finger vibration.

    Science.gov (United States)

    Welcome, Daniel E; Dong, Ren G; Xu, Xueyan S; Warren, Christopher; McDowell, Thomas W

    2014-01-01

    Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed.

  7. Intérvalo unitario de tiempo de medición para ruido ambiental Unit timing for environmental noise measurements

    Directory of Open Access Journals (Sweden)

    William A. Giraldo A.

    2011-01-01

    Full Text Available En las entidades ambientales, los encargados de las mediciones de ruido ambiental y en general todas las personas que de una u otra forma han trabajado en esta temática, en algún momento se han puesto a pensar sobre la representatividad del tiempo unitario de muestreo y la forma de realizar evaluaciones para dar cumplimiento con dicho tiempo, sin que se aumenten considerablemente los costos de medición. En este artículo se plantea una metodología para determinar cómo un intervalo de cierta duración -en este caso, quince (15 minutos- para el muestreo del nivel de presión sonora es representativo para el período de una (1 hora, logrando de esta manera optimizar el uso de los sonómetros "fijos" y proponiendo una estrategia para reducir los costos en las mediciones de ruido ambiental y en general la elaboración de mapas de ruido.The managers of environmental noise measurements in environmental control agencies, or in general every person that work in this subject, have to think on the representativity of the unit measurement time interval, and how to evaluate it in order to get good quality results regarding the unit measurement time without increasing the measurement costs. A methodology for deciding if a certain measuring time interval -in this case, fifteen (15 minutes- is representative of noise pressure levels occurring during one hour, is proposed in this paper. This methodology allows to optimize the use of stationary sound level meters and to propose a strategy for reducing the costs of environmental noise measurements and of the designing of noise maps in general.

  8. Water adsorption isotherms on CH3-, OH-, and COOH-terminated organic surfaces at ambient conditions measured with PM-RAIRS.

    Science.gov (United States)

    Tu, Aimee; Kwag, Hye Rin; Barnette, Anna L; Kim, Seong H

    2012-10-30

    The water adsorption isotherms on methyl (CH(3))-, hydroxyl (OH)-, and carboxylic acid (COOH)-terminated alkylthiol self-assembled monolayers (SAMs) on Au were studied at room temperature and ambient pressure with polarization modulation reflection-absorption infrared spectroscopy (PM-RAIRS). PM-RAIRS analysis showed that water does not adsorb at all on the CH(3)-SAM/Au at subsaturation humidity conditions. In a dry Ar environment, the OH-SAM/Au holds at least 2 layer thick strongly bound water molecules which exhibit a broad O-H stretch vibration peak centered at ∼3360 cm(-1). The peak position implies that the strongly bound water layer on the OH SAM is more like a liquid than an ice. The additional uptake of water in humid environments is relatively weak, and the peak position changes very little. Unlike the OH-SAM/Au, the COOH-SAM/Au does not have strongly bound water layer. This seems to be due to the strong hydrogen bonding between terminal COOH groups in dry conditions. The weak interactions between water and carboxyl groups at low relative humidity (RH) and the solvation of dissociated carboxylic groups in high RH lead to a type III isotherm behavior, based on the BET categories, for water adsorption on the COOH-SAM/Au. The water spectra on the COOH-SAM at RH > 45% are centered at ∼3430 cm(-1) and very broad, indicating that the hydrogen-bonding network of water on the COOH-SAM is much different from that on the OH-SAM.

  9. Theoretical analysis based on fundamental functions of thin plate and experimental measurement for vibration characteristics of a plate coupled with liquid

    Science.gov (United States)

    Liao, Chan-Yi; Wu, Yi-Chuang; Chang, Ching-Yuan; Ma, Chien-Ching

    2017-04-01

    This study combined theoretical, experimental, and numerical analysis to investigate the vibration characteristics of a thin rectangular plate positioned horizontally at the bottom of a rectangular container filled with liquid. Flow field pressure was derived using an equation governing the behavior of incompressible fluids. Analytic solutions to vibrations in a thin plate in air served as the fundamental function of the thin plate coupled with liquid. We then used liquid pressure, and the out-of-plane deflection of the thin plate for the construction of frequency response functions for the analysis of vibration characteristics in the liquid-plate coupling system. Two experimental methods were employed to measure the vibration characteristics of the thin plate immersed in water. The first involved using sensors of polyvinylidene difluoride (PVDF) to measure transient signals of fluid-plate system subjected an impact at the thin plate. These were then converted to the frequency domain in order to obtain the resonant frequencies of the fluid-plate coupling system. The second method was amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), which was used to measure the dynamic characteristics of the thin plate in the flow field. This method was paired with the image processing techniques, temporal speckle pattern interferometry (TSPI) and temporal standard deviation (TSTD), to obtain clear mode shapes of the thin plate and resonant frequencies. Comparison of the results from theoretical analysis, finite element method, and experimental measurements confirmed the accuracy of our theoretical analysis, which was superior to the conventional approach based on beam mode shape functions. The experimental methods proposed in this study can be used to measure the resonant frequencies of underwater thin plates, and clear mode shapes can be obtained using AF-ESPI. Our results indicate that the resonant frequencies of thin plates underwater are lower than

  10. Evaluation of innovative air-monitoring technologies for the measurement of ambient concentrations of ozone and its precursors at the 1996 Summer Olympics

    Science.gov (United States)

    Gamiles, Donald S.; Rodgers, Michael; Meeker, Charles; Olive, Brent S.; Simpson, Orman A.

    1997-05-01

    An open path Fourier transform IR spectrometer and an ultra- violet differential optical absorption spectrometer were used during the 1996 Atlanta Olympics games to monitor for ambient ozone and its precursors near the Olympic Village. Both systems were operated continuously before, during, and after the increase in Atlanta's population associated with the Summer games. The study utilized the massive changes in population patterns to observe and measure changes in local air quality due to an increased local population. A second goal of the program was to evaluate both open path instruments in continuous field use over a period of several weeks. The evaluation included the following criteria: instrumentation operability, system precision and accuracy, detection capability, and over-all ease of use. Both open path systems selected and measured ambient levels of ozone. A limited number of ozone precursors were detected. The study was sponsored by the Georgia Institute of Technology's Air Quality Laboratory, the US Department of Energy, and the US Environmental Protection Agency.

  11. Measurement of overall uptake coefficients for HO2 radicals by aerosol particles sampled from ambient air at Mts. Tai and Mang, China

    Directory of Open Access Journals (Sweden)

    H. Akimoto

    2012-06-01

    Full Text Available HO2 uptake coefficients for ambient aerosol particles, collected on quartz filter using a high-volume air sampler in China, were measured using an aerosol flow tube coupled with a chemical conversion/laser-induced fluorescence technique at 760 Torr and 298 K, with a relative humidity of 75%. Aerosol particles were regenerated with an atomizer using the water extracts from the aerosol particles. Over 10 samples, the measured HO2 uptake coefficients for the aerosol particles at the Mt. Tai site were ranged from 0.13 to 0.34, while those at the Mt. Mang site were in the range of 0.09–0.40. These values are generally larger than those previously reported for single-component particles, suggesting that the minor components such as metal ions and organics in the particle could contribute to the HO2 uptake. A box model calculation suggested that the heterogeneous loss of HO2 by ambient particles could significantly affect the HOx concentrations and chemistry.

  12. Measurement of overall uptake coefficients for HO2 radicals by aerosol particles sampled from ambient air at Mts. Tai and Mang (China

    Directory of Open Access Journals (Sweden)

    H. Akimoto

    2012-12-01

    Full Text Available HO2 uptake coefficients for ambient aerosol particles, collected on quartz fiber filter using a high-volume air sampler in China, were measured using an aerosol flow tube coupled with a chemical conversion/laser-induced fluorescence technique at 760 Torr and 298 K, with a relative humidity of 75%. Aerosol particles were regenerated with an atomizer using the water extracts from the aerosol particles. Over 10 samples, the measured HO2 uptake coefficients for the aerosol particles at the Mt. Tai site were ranged from 0.13 to 0.34, while those at the Mt. Mang site were in the range of 0.09–0.40. These values are generally larger than those previously reported for single-component particles, suggesting that reactions with the minor components such as metal ions and organics in the particle could contribute to the HO2 uptake. A box model calculation suggested that the heterogeneous loss of HO2 by ambient particles could significantly affect atmospheric HOx concentrations and chemistry.

  13. A comparison of sulfur-free and ambient air enclosure techniques for measuring the exchange of reduced sulfur gases between soils and the atmosphere

    Science.gov (United States)

    Castro, Mark S.; Galloway, James N.

    1991-08-01

    The exchange of reduced sulfur gases between the atmosphere and forest soils in the Shaver Hollow watershed (Shenandoah National Park, Virginia) were measured with sulfur-free and ambient air enclosures at least twice a month from March through November 1989. Soils within sulfur-free enslosures were sources of carbonyl sulfide (COS) and carbon disulfide (CS2). Atmospheric fluxes of COS and CS2 ranged from 0.77 to 13.03 ng COS-S/sq m-min and from 2.04 to 15.74 ng CS2-S/sq m-min. In contrast, soils within ambient air enclosures were sinks for COS and CS2. Uptake rates of COS and CS2 ranged from 2.78 to 16.20 ng COS-S/sq m-min and from 3.42 to 26.62 ng CS2-S/sq m-min. The discrepancy in the direction of these fluxes was caused by the flux-measurement techniques.

  14. Acoustic and Vibration Environment for Crew Launch Vehicle Mobile Launcher

    Science.gov (United States)

    Vu, Bruce T.

    2007-01-01

    A launch-induced acoustic environment represents a dynamic load on the exposed facilities and ground support equipment (GSE) in the form of random pressures fluctuating around the ambient atmospheric pressure. In response to these fluctuating pressures, structural vibrations are generated and transmitted throughout the structure and to the equipment items supported by the structure. Certain equipment items are also excited by the direct acoustic input as well as by the vibration transmitted through the supporting structure. This paper presents the predicted acoustic and vibration environments induced by the launch of the Crew Launch Vehicle (CLV) from Launch Complex (LC) 39. The predicted acoustic environment depicted in this paper was calculated by scaling the statistically processed measured data available from Saturn V launches to the anticipated environment of the CLV launch. The scaling was accomplished by using the 5-segment Solid Rocket Booster (SRB) engine parameters. Derivation of vibration environment for various Mobile Launcher (ML) structures throughout the base and tower was accomplished by scaling the Saturn V vibration environment.

  15. Absolute vibration measurement method using magnetic levitation ball as oscillator%磁悬浮振子绝对式振动测量方法

    Institute of Scientific and Technical Information of China (English)

    江东

    2013-01-01

    Abstract:The non-contact type absolute vibration measurement method using magnetic levitation ball as oscillator is proposed.The dynamic equation of magnetic levitation ball is deduced.The equation shows that the magnetic levitation ball dynamic equation is the same as that of a mass-spring system,they are both constant coefficient second order differential equation.The feasibility of using magnetic levitation ball as oscillator is proved theoretically.The sensitivity and maximum acceleration technical specifications are given.The frequency characteristics and error analysis of the magnetic levitation oscillator vibration sensor are studied.Experiment results indicate that the displacement waveforms of the magnetic levitation oscillator vibration sensor are the same as the vibration waveforms of the external exciter.Using magnetic levitation oscillator vibration sensor to test vibration belongs to non-contact absolute vibration measurement method.This method overcomes the mechanical friction and mechanical gap errors,and the displacement signal can be outputted directly.The damping is achieved with an electronic circuit,and the damping parameters can be adjusted easily.The method features high sensitivity,wide frequency response range;and multi-dimensional vibration measurement can be implemented easily.The proposed method provides a new measurement method for absolute vibration measurement.%提出了用磁悬浮球作为振子实现非接触绝对式振动测量方法,推导了磁悬浮球的动力学方程,方程表明磁悬浮球的运动方程与质量-弹簧系统一致,均为常系数二阶微分方程,从理论上证实将磁悬浮球作为振子是可行的.给出了灵敏度和最大加速度指标,研究了磁悬浮振子振动传感器的频率特性并进行了误差分析.实验结果表明,磁悬浮振子振动传感器的输出波形与外加激振器的波形一致.磁悬浮振子振动传感器属于非接触绝对式振动测量方法,克服了

  16. Measurements of nanoparticle size distribution produced by laser ablation of tungsten and boron-carbide in N 2 ambient

    Science.gov (United States)

    Bereznai, Miklós; Heszler, Péter; Tóth, Zsolt; Wilhelmsson, Ola; Boman, Mats

    2006-04-01

    Nanoparticles (NPs) were produced by ablating tungsten and boron-carbide (B 4C) target materials in atmospheric pressure nitrogen ambient using ArF excimer laser pulses. The size distributions of the NPs formed during the ablation were monitored—within a 7-133 nm size window—by a condensation particle counter connected to a differential mobility analyzer. The laser repetition rate was varied between 1-50 Hz, and the fluence was systematically changed in the range of 0.5-15 J/cm 2, for both materials, allowing a comparative study in an extended laser parameter regime. The multishot ablation threshold ( Φth) of B 4C was determined to be ˜1.9 J/cm 2 for the laser used (ArF excimer, λ = 193 nm). Similarly to earlier studies, it was shown that the size distributions consist of mainly small nanoparticles (<˜20 nm) attributed to a non-thermal ablation mechanism below Φth. An additional broad peak appears (between 20 and 40 nm) above Φth as a consequence of the thermally induced macroscopic ablation. Chemical composition of deposited polydisperse nanoparticles was studied by X-ray photoelectron spectroscopy showing nitrogen incorporation into the boron-carbide.

  17. CCN activation of ambient and "synthetic ambient" urban aerosol

    Science.gov (United States)

    Burkart, Julia; Reischl, Georg; Steiner, Gerhard; Bauer, Heidi; Leder, Klaus; Kistler, Magda; Puxbaum, Hans; Hitzenberger, R.

    2013-05-01

    In this study, the Cloud Condensation Nuclei (CCN) activation properties of the urban aerosol in Vienna, Austria, were investigated in a long term (11 month) field study. Filter samples of the aerosol below 100 nm were taken in parallel to these measurements, and later used to generate "synthetic ambient" aerosols. Activation parameters of this "synthetic ambient" aerosol were also obtained. Hygroscopicity parameters κ [1] were calculated both for the urban and the "synthetic ambient" aerosol and also from the chemical composition. Average κ for the "synthetic ambient" aerosol ranged from 0.20 to 0.30 with an average value of 0.24, while the κ from the chemical composition of this "synthetic ambient" aerosol was significantly higher (average 0.43). The full results of the study are given elsewhere [2,3].

  18. Plan, execute, and discuss vibration measurements and correlations to evaluate a NASTRAN finite element model of the AH-64 helicopter airframe

    Science.gov (United States)

    Ferg, D.; Foote, L.; Korkosz, G.; Straub, F.; Toossi, M.; Weisenburger, R.

    1990-01-01

    A ground vibration test was performed on the AH-64 (Apache) helicopter to determine the frequency response of the airframe. The structure was excited at both the main and tail rotor hubs, separately, and response measurements were taken at 102 locations throughout the fuselage structure. Frequency responses were compared and correlated with results from a NASTRAN finite element model of AH-64. In addition, natural frequencies and mode shapes were estimated from the frequency response data and were correlated with analytical results.

  19. Obtaining and Estimating Low Noise Floors in Vibration Sensors

    DEFF Research Database (Denmark)

    Brincker, Rune; Larsen, Jesper Abildgaard

    2007-01-01

    For some applications like seismic applications and measuring ambient vibrations in structures, it is essential that the noise floors of the sensors and other system components are low and known to the user. Some of the most important noise sources are reviewed and it is discussed how the sensor...... can be designed in order to obtain a low noise floor. Techniques to estimate the noise floors for sensors are reviewed and are demonstrated on a commercial commonly used sensor for vibration testing. It is illustrated how the noise floor can be calculated using the coherence between simultaneous...... measurements on two channels, and it is illustrated how the singular values decomposition can be used for estimating noise floors and signals in multi-channel applications....

  20. Correlation of finite-element structural dynamic analysis with measured free vibration characteristics for a full-scale helicopter fuselage

    Science.gov (United States)

    Kenigsberg, I. J.; Dean, M. W.; Malatino, R.

    1974-01-01

    The correlation achieved with each program provides the material for a discussion of modeling techniques developed for general application to finite-element dynamic analyses of helicopter airframes. Included are the selection of static and dynamic degrees of freedom, cockpit structural modeling, and the extent of flexible-frame modeling in the transmission support region and in the vicinity of large cut-outs. The sensitivity of predicted results to these modeling assumptions are discussed. Both the Sikorsky Finite-Element Airframe Vibration analysis Program (FRAN/Vibration Analysis) and the NASA Structural Analysis Program (NASTRAN) have been correlated with data taken in full-scale vibration tests of a modified CH-53A helicopter.

  1. 新型振动样品磁强计测量材料磁性%Material magnetic properties measured by new vibrating sample magnetometer

    Institute of Scientific and Technical Information of China (English)

    郇维亮; 高峰; 徐小龙

    2012-01-01

    简述新型振动样品磁强计测量原理,介绍自制的采用电动机驱动的振动样品磁强计,并通过用已知饱和磁矩的镍球对仪器进行定标,分别测量了铁氧体多晶小球和普通小钢球的磁化曲线,取得理想的实验结果.自制新型振动样品磁强计具有测量信号大和能判定磁矩方向的特点,该仪器可应用于高校近代物理实 验的教学.%This paper introduceds the measuring principle of a new type vibrating sample magnetometer and the home-made motor-driven vibrating sample magnetometer, and the magnetometer has been calibrated by the known saturation magnetic moment nickel ball and measured the magnetization curves of polycrystalline ferrite small ball and ordinary one respectively, and ideal experimental results are obtained. The home-made vibrating sample magnetometer with the characteristics of large measurement signal can detect the direction of magnetic moment, and the instrument can be used to modern physics experiments teaching in colleges and universities.

  2. Animal Communications Through Seismic Vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Peggy (University of Tulsa)

    2001-05-02

    Substrate vibration has been important to animals as a channel of communication for millions of years, but our literature on vibration in this context of biologically relevant information is only decades old. The jaw mechanism of the earliest land vertebrates allowed them to perceive substrate vibrations as their heads lay on the ground long before airborne sounds could be heard. Although the exact mechanism of vibration production and the precise nature of the wave produced are not always understood, recent development of affordable instrumentation to detect and measure vibrations has allowed researchers to answer increasingly sophisticated questions about how animals send and receive vibration signals. We now know that vibration provides information used in predator defense, prey detection, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions in a variety of insect orders, spiders, crabs, scorpions, chameleons, frogs, golden moles, mole rats, kangaroos rats, wallabies, elephants and bison.

  3. Ambient air/near-field measurements of methane and Volatile Organic Compounds (VOCs) from a natural gas facility in Northern Europe

    Science.gov (United States)

    Baudic, Alexia; Gros, Valérie; Bonsang, Bernard; Baisnee, Dominique; Vogel, Félix; Yver Kwok, Camille; Ars, Sébastien; Finlayson, Andrew; Innocenti, Fabrizio; Robinson, Rod

    2015-04-01

    Since the 1970's, the natural gas consumption saw a rapid growth in large urban centers, thus becoming an important energy resource to meet continuous needs of factories and inhabitants. Nevertheless, it can be a substantial source of methane (CH4) and pollutants in urban areas. For instance, we have determined that about 20% of Volatile Organic Compounds (VOCs) in downtown Paris are originating from this emission source (Baudic, Gros et al., in preparation). Within the framework of the "Fugitive Methane Emissions" (FuME) project (Climate-KIC, EIT); 2-weeks gas measurements were conducted at a gas compressor station in Northern Europe. Continuous ambient air measurements of methane and VOCs concentrations were performed using a cavity ring-down spectrometer (model G2201, Picarro Inc., Santa Clara, USA) and two portable GC-FID (Chromatotec, Saint-Antoine, France), respectively. On-site near-field samplings were also carried out at the source of two pipelines using stainless steel flasks (later analyzed with a laboratory GC-FID). The objective of this study aims to use VOCs as additional tracers in order to better characterize the fugitive methane emissions in a complex environment, which can be affected by several urban sources (road-traffic, others industries, etc.). Moreover, these measurements have allowed determining the chemical composition of this specific source. Our results revealed that the variability of methane and some VOCs was (rather) well correlated, especially for alkanes (ethane, propane, etc.). An analysis of selected events with strong concentrations enhancement was performed using ambient air measurements; thus allowing the preliminary identification of different emission sources. In addition, some flasks were also sampled in Paris to determine the local natural gas composition. A comparison between both was then performed. Preliminary results from these experiments will be presented here.

  4. A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

    Science.gov (United States)

    Franchin, Alessandro; Downard, Andy; Kangasluoma, Juha; Nieminen, Tuomo; Lehtipalo, Katrianne; Steiner, Gerhard; Manninen, Hanna E.; Petäjä, Tuukka; Flagan, Richard C.; Kulmala, Markku

    2016-06-01

    Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all differential mobility analyzers (DMAs) have an unfavorable potential gradient at the outlet (e.g., long column, Vienna type) or at the inlet (nano-radial DMA), preventing them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high-transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in Millikan-Fuchs mobility equivalent diameter, Dp (corresponding to 1.2 × 10-4 m2 V-1 s-1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a particle size magnifier (PSM) and as a booster a condensation particle counter (CPC). With this setup, we were able to measure size distributions of ions within a mobility range from 1.2 × 10-4 to 5.8 × 10-6 m2 V-1 s-1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD (Cosmics Leaving Outdoor Droplets) 7 measurement campaign at CERN. We achieved a higher size resolution (R = 5.5 at Dp = 1.47 nm) than techniques currently used in field measurements (e.g., Neutral cluster and Air Ion Spectrometer (NAIS), which has a R ˜ 2 at largest sizes, and R ˜ 1.8 at Dp = 1.5 nm) and maintained a good total transmission efficiency (6.3 % at Dp = 1.5 nm) at moderate inlet and sheath airflows (2.5 and 30 L min-1, respectively). In this paper, by measuring size distributions at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible

  5. Waves & vibrations

    OpenAIRE

    Nicolas, Maxime

    2016-01-01

    Engineering school; This course is designed for students of Polytech Marseille, engineering school. It covers first the physics of vibration of the harmonic oscillator with damping and forcing, coupled oscillators. After a presentation of the wave equation, the vibration of strings, beams and membranes are studied.

  6. lnstantaneous Torsional Vibration of Gear Transmission System by Direct Measurement Tests%齿轮传动系统瞬时扭振直接测量实验

    Institute of Scientific and Technical Information of China (English)

    冯浩; 赵浩; 朱耀东; 吴晓阳

    2016-01-01

    A new structure of magnet - electric induction torsional vibration measurement device is designed,which can directly convert the instantaneous torsional vibration of gear transmission system into the corresponding electrical signal. The mechanical structure and operation principle of this device is introduced,and the output characteristic is induced. The instantaneous torsional vibration of gear transmission system under no load、rated load and variable voltage speed control is measured directly by this device,and the operation principle of this device is verified through the experiments. The measurement results are analyzed by spectrum,the results show that the amplitude of main components of instantaneous torsional vibration is decreasing with the decreasing of power voltage.%设计了一种新结构磁电感应式扭振测量装置,可以直接将被测齿轮传动系统的瞬时扭振转化成相应的电信号输出。详细介绍了测量装置的机械结构和测量原理,并推导了其输出特性。对实际的齿轮传动系统在空载、额定载荷以及调压调速多种工况下的瞬时扭振进行了直接测量实验,验证了测量装置工作原理的正确性。对瞬时扭振测量结果进行了频谱特征分析,结果表明在动力源调压调速工况下,瞬时扭振主要分量的幅值随着电压的减小而减小。

  7. Uma medida de sustentabilidade ambiental: pegada hídrica A measure of environmental sustainability: water footprint

    Directory of Open Access Journals (Sweden)

    Vicente de P. R. da Silva

    2013-01-01

    Full Text Available Recentemente, o conceito da pegada hídrica foi introduzido como um indicador importante de consumo de água para a humanidade. A pegada hídrica é definida como o volume total de água utilizado durante a produção de bens e serviços, bem como o consumo direto de água pelos seres humanos. A água não é consumida só diretamente mas também indiretamente, nos processos de produção. Portanto, o cálculo da pegada hídrica permite quantificar o total de água consumida ao longo da cadeia de fornecimento global. Esta revisão de literatura analisa o estado da arte da pegada hídrica desde a sua criação, no encontro internacional de especialista em comércio de água virtual realizado em dezembro de 2002 na Holanda, até os dias atuais. Os principais resultados encontrados na literatura consultada indicam consenso de que a pegada hídrica é capaz de monitorar o impacto humano sobre o meio ambiente. Além do mais, esta metodologia tem uma vasta gama de aplicações que pode ser empregada em escalas que vão desde um único produto, um processo, setor, individuo, cidades, até mesmo nações e todo o planeta.The concept of the water footprint has been recently introduced as an important indicator for human induced water consumption. The water footprint is defined as the total volume of water used during production and consumption of goods and services as well as direct water consumption by human beings. Water is not only consumed directly but also indirectly in production processes. Therefore, calculating the water footprint enables to quantify total water consumed along the whole global supply chain. This review surveys the state of the art on water footprint since the International Expert Meeting on Virtual Water Trade, held in Delft, The Netherlands, in December 2002, until current days. The major findings linked to the consulted literature indicated that the water footprint is suitable for monitoring the human impact on the environment

  8. Transepidermal water loss in newborn infants. I. Relation to ambient humidity and site of measurement and estimation of total transepidermal water loss.

    Science.gov (United States)

    Hammarl-nd, K; Nilsson, G E; Oberg, P A; Sedin, G

    1977-09-01

    Insensible water loss (IWL) is an important factor in the thermoregulation and water balance of the newborn infant. A method for direct measurement of the rate of evaporation from the skin surface has been developed. The method, which is based on determination of the vapour pressure gradient close to the skin surface, allows free evaporation. From measurements performed on 19 newborns placed in incubators, a linear relation was found between the evaporation rate (ER) and the humidity of the environment at a constant ambient temperature. A 40% lower ER was recorded at a high relative humidity (60%) than at a low one (20%) in the incubator. At measurements on different sites of the body, a high ER was observed on the face and peripheral parts of the extremities, while ER at other sites was relatively low. By determining ER from different parts of the body and calculating the areas of the corresponding surfaces, the total cutaneous insensible water loss for the infant in question could be obtained. The transepidermal water loss (TEWL) for the whole body surface area was calculated to be 8.1 g/m2h. On the basis of measurements performed it was found that the total cutaneous insensible water loss can be estimated with a reasonable degree of accuracy by recording ER from only three easily accessible measurement points.

  9. Model Study of the Influence of Ambient Temperature and Installation Types on Surface Temperature Measurement by Using a Fiber Bragg Grating Sensor.

    Science.gov (United States)

    Liu, Yi; Zhang, Jun

    2016-07-01

    Surface temperature is an important parameter in clinical diagnosis, equipment state control, and environmental monitoring fields. The Fiber Bragg Grating (FBG) temperature sensor possesses numerous significant advantages over conventional electrical sensors, thus it is an ideal choice to achieve high-accuracy surface temperature measurements. However, the effects of the ambient temperature and installation types on the measurement of surface temperature are often overlooked. A theoretical analysis is implemented and a thermal transfer model of a surface FBG sensor is established. The theoretical and simulated analysis shows that both substrate strain and the temperature difference between the fiber core and hot surface are the most important factors which affect measurement accuracy. A surface-type temperature standard setup is proposed to study the measurement error of the FBG temperature sensor. Experimental results show that there are two effects influencing measurement results. One is the "gradient effect". This results in a positive linear error with increasing surface temperature. Another is the "substrate effect". This results in a negative non-linear error with increasing surface temperature. The measurement error of the FBG sensor with single-ended fixation are determined by the gradient effect and is a linear error. It is not influenced by substrate expansion. Thus, it can be compensated easily. The measurement errors of the FBG sensor with double-ended fixation are determined by the two effects and the substrate effect is dominant. The measurement error change trend of the FBG sensor with fully-adhered fixation is similar to that with double-ended fixation. The adhesive layer can reduce the two effects and measurement error. The fully-adhered fixation has lower error, however, it is easily affected by substrate strain. Due to its linear error and strain-resistant characteristics, the single-ended fixation will play an important role in the FBG sensor

  10. Development of a phase-sensitive Fourier domain optical coherence tomography system to measure mouse organ of Corti vibrations in two cochlear turns

    Energy Technology Data Exchange (ETDEWEB)

    Ramamoorthy, Sripriya [Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon (United States); Zhang, Yuan; Jacques, Steven [Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon (United States); Petrie, Tracy; Wang, Ruikang [Department of Bioengineering, University of Washington, Seattle, Washington (United States); Nuttall, Alfred L. [Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon (United States); Kresge Hearing Research Institute, The University of Michigan, Ann Arbor, Michigan (United States)

    2015-12-31

    In this study, we have developed a phase-sensitive Fourier-domain optical coherence tomography system to simultaneously measure the in vivo inner ear vibrations in the hook area and second turn of the mouse cochlea. This technical development will enable measurement of intra-cochlear distortion products at ideal locations such as the distortion product generation site and reflection site. This information is necessary to un-mix the complex mixture of intra-cochlear waves comprising the DPOAE and thus leads to the non-invasive identification of the local region of cochlear damage.

  11. Development of a phase-sensitive Fourier domain optical coherence tomography system to measure mouse organ of Corti vibrations in two cochlear turns

    Science.gov (United States)

    Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Jacques, Steven; Wang, Ruikang; Nuttall, Alfred L.

    2015-12-01

    In this study, we have developed a phase-sensitive Fourier-domain optical coherence tomography system to simultaneously measure the in vivo inner ear vibrations in the hook area and second turn of the mouse cochlea. This technical development will enable measurement of intra-cochlear distortion products at ideal locations such as the distortion product generation site and reflection site. This information is necessary to un-mix the complex mixture of intra-cochlear waves comprising the DPOAE and thus leads to the non-invasive identification of the local region of cochlear damage.

  12. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  13. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    Energy Technology Data Exchange (ETDEWEB)

    Carl, W. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-30

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  14. Diode laser cavity ring-down spectroscopy for in situ measurement of NO3 radical in ambient air

    Science.gov (United States)

    Wang, Dan; Hu, Renzhi; Xie, Pinhua; Liu, Jianguo; Liu, Wenqing; Qin, Min; Ling, Liuyi; Zeng, Yi; Chen, Hao; Xing, XingBiao; Zhu, Guoliang; Wu, Jun; Duan, Jun; Lu, Xue; Shen, Lanlan

    2015-11-01

    A cavity ring-down spectroscopy (CRDS) instrument for measuring atmospheric NO3 radical developed in our laboratory is presented in detail. Light from a red laser diode (661.85 nm) is coupled on-axis into an optical cavity formed by a pair of high-reflectivity mirrors (R≥99.9985%) to achieve an effective absorption path length of approximately 20 km. The detection limit of the NO3 radical determined by Allan variance for the field observation with high particles is approximately 3.2 pptv (2σ, 10 s). The transmission efficiency of the NO3 radical in the system is calibrated, including the filter loss and surface loss. Moreover, measurable interferences from NO2, O3 and water vapor are also discussed. Considering the influence of inlet transmission efficiency and other factors, the instrument accuracy for NO3 radical measurement is approximately ±8% (1σ). The measurement of NO3 radical was performed at a suburb site in Beijing under the situation of high particles concentration (PM2.5 approximately several tens to 150 μg/m3) from October 26 to November 11, 2014. The NO3 radical concentration during the period is relatively low with the maximum value of 38 pptv. The observation results on October 29, combining NO2, O3 and NO data, are briefly analyzed. The experimental results demonstrate that this compact CRDS instrument has the potential for NO3 radical measurements in the field with high particles.

  15. Vibration Compensation for Scanning Tunneling Microscope

    Institute of Scientific and Technical Information of China (English)

    LI Meng-chao; FU Xing; WEI Xiao-lei; HU Xiao-tang

    2003-01-01

    The influence of vibration is already one of main obstacles for improving the nano measuring accuracy.The techniques of anti-vibration,vibration isolation and vibration compensation become an important branch in nano measuring field.Starting with the research of sensitivity to vibration of scanning tunneling microscope(STM),the theory,techniques and realization methods of nano vibration sensor based on tunnel effect are initially investigated,followed by developing the experimental devices.The experiments of the vibration detection and vibration compensation are carried out.The experimental results show that vibration sensor based on tunnel effect is characterized by high sensitivity,good frequency characteristic and the same vibratory response characteristic consistent with STM.

  16. Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

    Directory of Open Access Journals (Sweden)

    M. Zavala

    2009-03-01

    Full Text Available Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions.

    We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI underprediction of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be under predicted by factors of 3 for HCHO and 2 for CH3CHO. Our on-road measurement based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4 of PM2.5 mobile emissions in the inventory.

    Analyses of ambient CO, NOx and CO/NOx concentration trends in the MCMA indicate that the early morning ambient CO

  17. First Measurements of Ambient Total Gaseous Mercury (TGM at the EvK2CNR Pyramid Observatory in Nepal

    Directory of Open Access Journals (Sweden)

    Gratz L. E.

    2013-04-01

    Full Text Available As part of the Global Mercury Observation System (GMOS project, a global-scale network of ground-based atmospheric monitoring sites is being developed with the objective of expanding the global coverage of atmospheric mercury (Hg measurements and improving our understanding of global atmospheric Hg transport. An important addition to the GMOS monitorng network has been the high altitude EvK2CNR Pyramid Observatory, located at an elevation of 5,050 meters a.s.l. in the eastern Himalaya Mountains of Nepal. Monitoring of total gaseous mercury (TGM using the Tekran 2537A Mercury Vapor Analyzer began at the EvK2CNR Pyramid Observatory in November 2011. From 17 November 2011 to 23 April 2012, the mean concentration of TGM at the Pyramid was 1.2 ng m−3. A range of concentrations from 0.7 to 2.6 ng m−3 has been observed. These are the first reported measurements of atmospheric Hg in Nepal, and currently this is the highest altitude monitoring station for atmospheric Hg in the world. It is anticipated that these high quality measurements, in combination with the other continuous atmospheric measurments being collected at the Pyramid station, will help to further our understanding of Hg concentrations in the free troposphere and the transport of atmospheric Hg on the global scale.

  18. Setting up of a theoretical-experimental approach for the measurement of the vibrational impact on cultural heritages due to vehicular traffic

    Directory of Open Access Journals (Sweden)

    Salvatore Barbaro

    2006-02-01

    Full Text Available During the last years, the constant increase of the request for transport by road and by rail, connected to the economic and social development process, has provoked the birth of the phenomenon of the vibrations induced by the means of transports, with the result of stimulating the resident population's curiosity and the technical personnel's interest. Into the historic centres of the towns, it is possible to trace a series of concomitant factors that tend further to increase this process: the road superstructure mostly used in the historical centres are often stony, and their usage is due mainly to aesthetic reasons; the no-measurement or the lack of maintenance are often the causes of high levels of roughness; the buildings set into the historical centres have got a historical-art value of primary importance and some part of them (such as mosaics, pictures, etc. are very sensitive to vibrations, being sticking to the outside walls; According to what said above, the noisy and vibrations provoked by the road traffic are becoming even more one of the main cause of the environmental damage.

  19. Vibrational Stability of SRF Accelerator Test Facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, M.W.; Volk, J.T.; /Fermilab

    2009-05-01

    Recently developed, the Superconducting Radio Frequency (SRF) Accelerator Test Facilities at Fermilab support the International Linear Collider (ILC), High Intensity Neutrino Source (HINS), a new high intensity injector (Project X) and other future machines. These facilities; Meson Detector Building (MDB) and New Muon Lab (NML) have very different foundations, structures, relative elevations with respect to grade level and surrounding soil composition. Also, there are differences in the operating equipment and their proximity to the primary machine. All the future machines have stringent operational stability requirements. The present study examines both near-field and ambient vibration in order to develop an understanding of the potential contribution of near-field sources (e.g. compressors, ultra-high and standard vacuum equipment, klystrons, modulators, utility fans and pumps) and distant noise sources to the overall system displacements. Facility vibration measurement results and methods of possible isolation from noise sources are presented and discussed.

  20. Precision measurements and test of molecular theory in highly excited vibrational states of H2 ( v = 11)

    Science.gov (United States)

    Trivikram, T. Madhu; Niu, M. L.; Wcisło, P.; Ubachs, W.; Salumbides, E. J.

    2016-12-01

    Accurate EF^1Σ^+_g{-}X^1Σ^+_g transition energies in molecular hydrogen were determined for transitions originating from levels with highly excited vibrational quantum number, v = 11, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited H_2^*, produced via the photodissociation of H2S, yielding transition frequencies with accuracies of 45 MHz or 0.0015 cm-1. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing 7pπ electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known EF level energies, the level energies of X( v = 11, J = 1, 3-5) states are derived with accuracies of typically 0.002 cm-1. These experimental values are in excellent agreement with and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.

  1. An automated online instrument to quantify aerosol-bound reactive oxygen species (ROS) for ambient measurement and health-relevant aerosol studies

    Science.gov (United States)

    Wragg, Francis P. H.; Fuller, Stephen J.; Freshwater, Ray; Green, David C.; Kelly, Frank J.; Kalberer, Markus

    2016-10-01

    The adverse health effects associated with ambient aerosol particles have been well documented, but it is still unclear which aerosol properties are most important for their negative health impact. Some studies suggest the oxidative effects of particle-bound reactive oxygen species (ROS) are potential major contributors to the toxicity of particles. Traditional ROS measurement techniques are labour-intensive, give poor temporal resolution and generally have significant delays between aerosol sampling and ROS analysis. However, many oxidising particle components are reactive and thus potentially short-lived. Thus, a technique to quantify particle-bound ROS online would be beneficial to quantify also the short-lived ROS components. We introduce a new portable instrument to allow online, continuous measurement of particle-bound ROS using a chemical assay of 2'7'-dichlorofluorescein (DCFH) with horseradish peroxidase (HRP), via fluorescence spectroscopy. All components of the new instrument are attached to a containing shell, resulting in a compact system capable of automated continuous field deployment over many hours or days. From laboratory measurements, the instrument was found to have a detection limit of ˜ 4 nmol [H2O2] equivalents per cubic metre (m3) air, a dynamic range up to at least ˜ 2000 nmol [H2O2] equivalents per m3 air and a time resolution of ≤ 12 min. The instrument allows for ˜ 16 h automated measurement if unattended and shows a fast response to changes in concentrations of laboratory-generated oxidised organic aerosol. The instrument was deployed at an urban site in London, and particulate ROS levels of up to 24 nmol [H2O2] equivalents per m3 air were detected with PM2.5 concentrations up to 28 µg m-3. The new and portable Online Particle-bound ROS Instrument (OPROSI) allows fast-response quantification; this is important due to the potentially short-lived nature of particle-bound ROS as well as fast-changing atmospheric conditions

  2. Good Vibrations

    OpenAIRE

    Panesar, Lucy

    2007-01-01

    Good Vibrations was a market research exercise conducted by Felicity (my alter-ego) and assistants to help develop marketing and packaging for an electro-therapeutic device (vibrator) used to treat hysteria and other female stress related disorders. It was a live art work commissioned by The Live Art Development Agency for East End Collaborations on 6th May 2007 and the South London Gallery for Bonkersfest on 2nd June 2007.

  3. Ambient formaldehyde measurements made at a remote marine boundary layer site during the NAMBLEX campaign – a comparison of data from chromatographic and modified Hantzsch techniques

    Directory of Open Access Journals (Sweden)

    T. J. Still

    2006-01-01

    Full Text Available Ambient formaldehyde concentrations are reported from the North Atlantic Marine Boundary Layer Experiment (NAMBLEX campaign at Mace Head on the west coast of Eire during August 2002. The results from two techniques, using direct determination via gas chromatography and the Hantzsch technique, show similar trends but a significant off set in concentrations. For westerly air flows characteristic of the marine boundary layer, formaldehyde concentrations from the gas chromatographic and Hantzsch technique ranged from 0.78–1.15 ppb and 0.13–0.43 ppb, respectively. Possible reasons for the discrepancy have been investigated and are discussed, however, no satisfactory explanation has yet been found. In a subsequent laboratory intercomparison the two techniques were in good agreement. The observed concentrations have been compared with previous formaldehyde measurements in the North Atlantic marine boundary layer and with other measurements from the NAMBLEX campaign. The measurements from the Hantzsch technique and the GC results lie at the lower and upper ends respectively of previous measurements. In contrast to some previous measurements, both techniques show distinct diurnal profiles with day maxima and with an amplitude of approximately 0.15 ppb. Strong correlations were observed with ethanal concentrations measured during NAMBLEX and the ratio of ethanal to formaldehyde determined by the gas chromatographic technique is in good agreement with previous measurements. Some simple box modelling has been undertaken to investigate possible sources of formaldehyde. Such models are not able to predict absolute formaldehyde concentrations as they do not include transport processes, but the results show that oxygenated VOCs such as ethanal and methanol are very significant sources of formaldehyde in the air masses reaching Mace Head.

  4. Laboratory Measurements of Vortex-and Wake-Induced Vibrations of A Tandem Arrangement of Two Flexible Risers

    Institute of Scientific and Technical Information of China (English)

    刘怀增; 王飞; 蒋国盛; 郭海燕; 李效民

    2016-01-01

    The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3-12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s (the Reynolds number was 18000) and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration (VIV) had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration (WIV). The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.

  5. Thermal conductivity of silver loaded conductive epoxy from cryogenic to ambient temperature and its application for precision cryogenic noise measurements

    Science.gov (United States)

    Amils, Ricardo I.; Gallego, Juan Daniel; Sebastián, José Luis; Muñoz, Sagrario; Martín, Agustín; Leuther, Arnulf

    2016-06-01

    The pressure to increase the sensitivity of instrumentation has pushed the use of cryogenic Low Noise Amplifier (LNA) technology into a growing number of fields. These areas range from radio astronomy and deep space communications to fundamental physics. In this context manufacturing for cryogenic environments requires a proper thermal knowledge of the materials to be able to achieve adequate design behavior. In this work, we present experimental measurements of the thermal conductivity of a silver filled conductive epoxy (EPO-TEK H20E) which is widely used in cryogenic electronics applications. The characterization has been made using a sample preparation which mimics the practical use of this adhesive in the fabrication of cryogenic devices. We apply the data obtained to a detailed analysis of the effects of the conductive epoxy in a monolithic thermal noise source used for high accuracy cryogenic microwave noise measurements. In this application the epoxy plays a fundamental role since its limited thermal conductivity allows heating the chip with relatively low power. To our knowledge, the cryogenic thermal conductivity data of this epoxy has not been reported before in the literature in the 4-300 K temperature range. A second non-conductive epoxy (Gray Scotch-Weld 2216 B/A), also widely used in cryogenic applications, has been measured in order to validate the method by comparing with previous published data.

  6. Studies of Heterogeneously Catalyzed Liquid-Phase Alcohol Oxidation on Platinum bySum-frequency Generation Vibrational Spectroscopy and Reaction Rate Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Christopher [Univ. of California, Berkeley, CA (United States)

    2014-05-15

    Compared to many branches of chemistry, the molecular level study of catalytically active surfaces is young. Only with the invention of ultrahigh vacuum technology in the past half century has it been possible to carry out experiments that yield useful molecular information about the reactive occurrences at a surface. The reason is two-fold: low pressure is necessary to keep a surface clean for an amount of time long enough to perform an experiment, and most atomic scale techniques that are surface speci c (x-ray photoelectron spectroscopy, electron energy loss spectroscopy, Auger electron spectroscopy, etc.) cannot be used at ambient pressures, because electrons, which act as chemical probes in these techniques, are easily scattered by molecules. Sum-frequency generation (SFG) vibrational spectroscopy is one technique that can provide molecular level information from the surface without the necessity for high vacuum. Since the advent of SFG as a surface spectroscopic tool it has proved its worth in the studies of surface catalyzed reactions in the gas phase, with numerous reactions in the gas phase having been investigated on a multitude of surfaces. However, in situ SFG characterization of catalysis at the solid-liquid interface has yet to be thoroughly pursued despite the broad interest in the use of heterogeneous catalysts in the liquid phase as replacements for homogeneous counterparts. This work describes an attempt to move in that direction, applying SFG to study the solid-liquid interface under conditions of catalytic alcohol oxidation on platinum.

  7. PCDD/PCDF and dl-PCB in the ambient air of a tropical Andean city: passive and active sampling measurements near industrial and vehicular pollution sources.

    Science.gov (United States)

    Cortés, J; González, C M; Morales, L; Abalos, M; Abad, E; Aristizábal, B H

    2014-09-01

    Concentration gradients were observed in gas and particulate phases of PCDD/F originating from industrial and vehicular sources in the densely populated tropical Andean city of Manizales, using passive and active air samplers. Preliminary results suggest greater concentrations of dl-PCB in the mostly gaseous fraction (using quarterly passive samplers) and greater concentrations of PCDD/F in the mostly particle fraction (using daily active samplers). Dioxin-like PCB predominance was associated with the semi-volatility property, which depends on ambient temperature. Slight variations of ambient temperature in Manizales during the sampling period (15°C-27°C) may have triggered higher concentrations in all passive samples. This was the first passive air sampling monitoring of PCDD/F conducted in an urban area of Colombia. Passive sampling revealed that PCDD/F in combination with dioxin-like PCB ranged from 16 WHO-TEQ2005/m(3) near industrial sources to 7 WHO-TEQ2005/m(3) in an intermediate zone-a reduction of 56% over 2.8 km. Active sampling of particulate phase PCDD/F and dl-PCB were analyzed in PM10 samples. PCDD/F combined with dl-PCB ranged from 46 WHO-TEQ2005/m(3) near vehicular sources to 8 WHO-TEQ2005/m(3) in the same intermediate zone, a reduction of 83% over 2.6 km. Toxic equivalent quantities in both PCDD/F and dl-PCB decreased toward an intermediate zone of the city. Variations in congener profiles were consistent with variations expected from nearby sources, such as a secondary metallurgy plant, areas of concentrated vehicular emissions and a municipal solid waste incinerator (MSWI). These variations in congener profile measurements of dioxins and dl-PCBs in passive and active samples can be partly explained by congener variations expected from the various sources.

  8. Assessing combined exposures of whole-body vibration and awkward posture--further results from application of a simultaneous field measurement methodology.

    Science.gov (United States)

    Raffler, Nastaran; Hermanns, Ingo; Sayn, Detlef; Göres, Benno; Ellegast, Rolf; Rissler, Jörg

    2010-01-01

    The drivers of ten vehicles (tram, helicopter, saloon car, van, forklift, two mobile excavators, wheel loader, tractor, elevating platform truck) were studied with regard to the combined exposures of whole-body vibration and awkward posture during occupational tasks. Seven degrees of freedom (DOFs), or body angles, were recorded as a function of time by means of the CUELA measuring system (Computer-assisted registration and long-term analysis of musculoskeletal workloads) for the purpose of posture assessment. The vibrational exposure is expressed as the vector sum of the frequency-weighted accelerations in the three Cartesian coordinates; these were recorded simultaneously with the posture measurement. Based upon the percentage of working time spent under different workloads, a scheme is proposed for classification of the two exposures into three categories. In addition, a risk of adverse health effects classified as low, possible or high can be assigned to the combination of the two exposures. With regard to posture, the most severe exposure was measured for the drivers of the wheel loader and for the tractor driver, whereas the lowest exposure was measured for the helicopter pilots and van drivers. With regard to the combination of whole-body and posture exposures, the tractor driver and the elevating platform truck driver exhibited the highest workloads.

  9. Frequency adjustable MEMS vibration energy harvester

    Science.gov (United States)

    Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

    2016-10-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

  10. Environmental radioactivity measurements in the autonomous community of Aragon; Medidas de la radiactividad ambiental en la comunidad autonoma de Aragon

    Energy Technology Data Exchange (ETDEWEB)

    Calvete, H.; Carrion, A.; Gale, C.; Garcia, E.; Nunez-Lagos, R.; Perez, C.; Puimedon, J.; Rodriguez, S.; Sanchez, P.; Sarsa, M. L.; Villar, J. A.

    2011-07-01

    To know the level of environmental radioactivity in the Autonomous Community of Aragon thermoluminescent dosimeters used to measure the cumulative dose over a period of time in each of its 33 counties. The project, funded by the Government of Aragon and La Caixa to carry a map of environmental radioactivity with the collaboration of Secondary Schools and public schools for the renovation and shipment of dosimeters. The selection of the different locations was carried out taking into account the points of interest in the project reflected Marna, by ENUSA and the CSN, on natural gamma radiation. The work program began in 2009 and to date working with 43 centers distributed throughout the community tried to cover a wide surface area of Aragon. (Author)

  11. Analysis of algorithms for detection of resonance frequencies in vibration measurements on super heater tubes; Analys av algoritmer foer detektering av resonansfrekvenser i vibrationsmaetningar paa oeverhettartuber

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Daniel

    2010-07-01

    Combustion of fuel in thermal power plants emits particles which creates coatings on the super heater tubes. The coatings isolate the tubes and impairs the efficiency of the heat transfer. Cleaning the tubes occurs while the power plant is running but without any knowledge of the actual coating. A change in frequency corresponds to a change in mass of the coatings. This thesis has been focusing in estimating resonance frequencies in vibration measurements made by strain gauges on the tubes. To improve the estimations a target tracking algorithm had been added. The results indicates that it is possible to estimate the resonance frequencies but the algorithms need to be verified on more signals.

  12. Rezultati merenja torzionih oscilacija u sistemu propulzije brodskog dizel motora / The results of torsional vibrations measurement in the system of diesel engine propulsion

    Directory of Open Access Journals (Sweden)

    Dragan Trifković

    2005-11-01

    Full Text Available U ovom radu prikazan je postupak merenja, kao i rezultati dobijeni merenjem nivoa torzionih oscilacija u sistemu prenosa snage sa brodskog dizel motora na propeler. Primenjen je princip merenja torzionog napona u funkciji broja obrtaja brodskog motora upotrebom savremene merne opreme. Proveren je položaj kritičnih brojeva obrtaja i nivo naprezanja propelerskih vratila, i na osnovu toga data ocena tehničkog stanja sistema sa aspekta naprezanja usled torzionih oscilacija. / The measuring treatment, as well as the results of torsional vibrations in the transfer from the ship diesel engine to the propeller are shown in this work. The measuring principle of torsional stress according to the function of rotation number of ship engine is applied by using of modern measurement equipment. The position of critical rotation numbers and the level of propeller shafts stress have been checked, and on the basis of these indices the evaluation of technical condition of the system has been estimated from the aspect of torsional vibrations strain.

  13. Analysis of multi-band pyrometry for emissivity and temperature measurements of gray surfaces at ambient temperature

    Science.gov (United States)

    Araújo, António

    2016-05-01

    A multi-band pyrometry model is developed to evaluate the potential of measuring temperature and emissivity of assumably gray target surfaces at 300 K. Twelve wavelength bands between 2 and 60 μm are selected to define the spectral characteristics of the pyrometers. The pyrometers are surrounded by an enclosure with known background temperature. Multi-band pyrometry modeling results in an overdetermined system of equations, in which the solution for temperature and emissivity is obtained through an optimization procedure that minimizes the sum of the squared residuals of each system equation. The Monte Carlo technique is applied to estimate the uncertainties of temperature and emissivity, resulting from the propagation of the uncertainties of the pyrometers. Maximum reduction in temperature uncertainty is obtained from dual-band to tri-band systems, a small reduction is obtained from tri-band to quad-band, with a negligible reduction above quad-band systems (a reduction between 6.5% and 12.9% is obtained from dual-band to quad-band systems). However, increasing the number of bands does not always reduce uncertainty, and uncertainty reduction depends on the specific band arrangement, indicating the importance of choosing the most appropriate multi-band spectral arrangement if uncertainty is to be reduced. A reduction in emissivity uncertainty is achieved when the number of spectral bands is increased (a reduction between 6.3% and 12.1% is obtained from dual-band to penta-band systems). Besides, emissivity uncertainty increases for pyrometers with high wavelength spectral arrangements. Temperature and emissivity uncertainties are strongly dependent on the difference between target and background temperatures: uncertainties are low when the background temperature is far from the target temperature, tending to very high values as the background temperature approaches the target temperature.

  14. 49 CFR 325.35 - Ambient conditions; highway operations.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Ambient conditions; highway operations. 325.35... Ambient conditions; highway operations. (a)(1) Sound. The ambient A-weighted sound level at the microphone... § 325.23. (2) The measured ambient level must be 10 dB(A) or more below that level specified in §...

  15. An intercomparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    Directory of Open Access Journals (Sweden)

    J. L. Ambrose

    2010-01-01

    Full Text Available Toluene was measured using both a gas chromatographic system (GC, with a flame ionization detector (FID, and a proton transfer reaction-mass spectrometer (PTR-MS at the AIRMAP atmospheric monitoring station Thompson Farm (THF in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including α- and β-pinene, camphene, Δ3-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of ~2 and ~30, respectively. A detailed intercomparison among the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O2+ and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of ~0.5 ppbv. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube; however, the improvement was minor. Interferences in the PTR-MS measurements from fragmentation of the monoterpene oxidation products pinonaldehyde, caronaldehyde and α-pinene oxide were also likely negligible. The results from THF suggest that toluene can be reliably quantified by PTR-MS using our operating conditions under the ambient

  16. A Novel Self-Powered Wireless Sensor Node Based on Energy Harvesting for Mechanical Vibration Monitoring

    Directory of Open Access Journals (Sweden)

    Xihai Zhang

    2014-01-01

    Full Text Available Wireless sensor networks (WSNs have been expected to improve the capability of capturing mechanical vibration dynamic behaviors and evaluating the current health status of equipment. While the expectation for mechanical vibration monitoring using WSNs has been high, one of the key limitations is the limited lifetime of batteries for sensor node. The energy harvesting technologies have been recently proposed. One of them shares the same main idea, that is, energy harvesting from ambient vibration can be converted into electric power. Employing the vibration energy harvesting, a novel self-powered wireless sensor node has been developed to measure mechanical vibration in this paper. The overall architecture of node is proposed. The wireless sensor node is described into four main components: the energy harvesting unit, the microprocessor unit, the radio transceiver unit, and accelerometer. Moreover, the software used to control the operation of wireless node is also suggested. At last, in order to achieve continuous self-powered for nodes, two operation modes including the charging mode and discharging mode are proposed. This design can effectively solve the problem of continuous supply power of sensor node for mechanical vibration monitoring.

  17. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

    In   this   paper   we   describe   a   field   study   conducted   with   a   wearable   vibration   belt   where   we   test   to   determine   the   vibration   intensity   sensitivity   ranges   on   a   large   diverse   group   of   participants   with   evenly   distributed  ages  and......   lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  18. Precision measurements and test of molecular theory in highly-excited vibrational states of H$_2$ $(v=11)$

    CERN Document Server

    Trivikram, T Madhu; Wcisło, P; Ubachs, W; Salumbides, E J

    2016-01-01

    Accurate $EF{}^1\\Sigma^+_g-X{}^1\\Sigma^+_g$ transition energies in molecular hydrogen were determined for transitions originating from levels with highly-excited vibrational quantum number, $v=11$, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited H$_2^*$, produced via the photodissociation of H$_2$S, yielding transition frequencies with accuracies of $45$ MHz or $0.0015$ cm$^{-1}$. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing $7p\\pi$ electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known $EF$ level energies, the level energies of $X(v=11, J=1,3-5)$ states are derived with accuracies of typically 0.002 cm$^{-1}$. These experimental values are in excellent agreement with, and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.

  19. Characteristics of Vibration Induced by Cavitation

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-yu; TAO Lei; LIU Shu-yan; QIAN Jian-jun

    2005-01-01

    Cavitation-induced vibration characteristics and the relations between the vibration and cavitation are studied. Cavitation vibrations are measured around a model hollow-jet valve by an accelerometer under cavitating and non-cavitating conditions. The measurement data is analyzed by FFT method. The corresponding cavitating flow patterns are photographed by a high-speed camera with an xenon flash lamp. The frequency band of the vibration induced by cavitation is determined. To compare the vibration intensities under different cavitation conditions, a definition of vibration acceleration level is introduced based on power spectral density of the vibration. By the analysis of vibration, the definitions of characteristic cavitation number are suggested. According to these cavitation numbers, the cavitation process is divided into three stages, that is, incipient cavitation, subcavitation and supercavitation.

  20. Vibrational spectroscopy of resveratrol

    Science.gov (United States)

    Billes, Ferenc; Mohammed-Ziegler, Ildikó; Mikosch, Hans; Tyihák, Ernő

    2007-11-01

    In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy- trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.

  1. 架空输电线路微风振动防治措施介绍及瞻望%Measures of Introduction and Look Forward to Prevent Breeze Vibration of Overhead Power Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    李阔; 成印健; 成志

    2013-01-01

    随着输电线路大量兴建,输电线路微风振动问题也越来越引起线路工作人员的重视。为了防止线路因微风振动引起的破坏,在线路设计时要加强措施来防止振动破坏。采用自阻尼导线和防振线夹来防振是一种通过改变线路自身组成部分特性来防振的措施,采用护线条、阻尼线、防振锤、阻尼弹簧间隔棒这些消振装置来防振是另外一种有效的防振措施,两种方法可根据具体情况来选择采用。同时,在超高压乃至特高压迅速发展的今天,利用阻尼线与防振锤混合消振装置以及阻尼弹簧间隔棒来防止微风振动已经越来越受到电力工作者的青睐,成为了一种趋势。%Along with the power transmission lines of construction ,the problem to prevent breeze vibration has caused line workers' atten-tion more and more. To prevent lines for vibration caused by the breeze destruction,in the line design people must strengthen the measures to pre-vent the vibration damage. Adopting the damping wires and vibration- proof line clip to prevent vibration is an effective way by which changing the line itself component characteristics. Adopting Armor Rod, Damping Line, Vibration- proof Hammer,damping spring spacer these vibrating de-vices to prevent vibration is another kind of effective vibration control measures . The two methods can be adopted according to the specific condi-tions. At the same time when the extra high voltage system and even ultra high voltage system is on the development, Using damping line and vi-bration- proof hammer mixed vibrating device class and damping spring spacer to prevent breeze vibration has got the favour of power workers more and more.

  2. A comparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    Directory of Open Access Journals (Sweden)

    J. L. Ambrose

    2010-07-01

    correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube; however, the improvement was minor (<10%. Interferences in the PTR-MS measurements from fragmentation of the monoterpene oxidation products pinonaldehyde, caronaldehyde and α-pinene oxide were also likely negligible. A relatively large and variable toluene background in the PTR-MS instrument likely drove the measurement bias; however, the precise contribution was difficult to accurately quantify and thus was not corrected for in this analysis. The results from THF suggest that toluene can be reliably quantified by PTR-MS using our operating conditions (drift tube pressure, temperature and voltage of 2.0 mbar, 45 °C and 600 V, respectively under the ambient compositions probed. This work extends the range of field conditions under which PTR-MS validation studies have been conducted.

  3. Seasonal variations and sources of ambient fossil and biogenic-derived carbonaceous aerosols based on 14C measurements in Lhasa, Tibet

    Science.gov (United States)

    Huang, Jie; Kang, Shichang; Shen, Chengde; Cong, Zhiyuan; Liu, Kexin; Wang, Wei; Liu, Lichao

    2010-06-01

    A total of 30 samples of total suspended particles were collected at an urban site in Lhasa, Tibet from August 2006 to July 2007 for investigating carbonaceous aerosol features. The fractions of contemporary carbon ( fc) in total carbon (TC) of ambient aerosols are presented using radiocarbon ( 14C) measurements. The value of fc represents the biogenic contribution to TC, as the biosphere releases organic compounds with the present 14C/ 12C level ( fc = 1), whereas 14C has become extinct in anthropogenic emissions of fossil carbon ( fc = 0). The fc values in Lhasa ranging from 0.357 to 0.702, are higher than Beijing and Tokyo, but clearly lower than the rural region of Launceston, which indicates a major biogenic influence in Lhasa. Seasonal variations of fc values corresponded well with variations of pollutants concentrations (e.g. NO 2). Higher fc values appeared in winter indicating carbonaceous aerosol is more dominated by wood burning and incineration of agricultural wastes within this season. The lower fc values in summer and autumn may be caused by increased diesel and petroleum emissions related to tourism in Lhasa. δ13C values ranged from - 26.40‰ to - 25.10‰, with relative higher values in spring and summer, reflecting the increment of fossil carbon emissions.

  4. Ambient noise near the sea-route

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

  5. Ambient noise near the sea-route

    Institute of Scientific and Technical Information of China (English)

    HE Li; LI ZhengLin; PENG ZhaoHui

    2009-01-01

    Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shal-low water near the sea-route.

  6. Vibrating minds

    CERN Multimedia

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  7. 往复式压缩机出口管道振动原理及解决措施%Vibration Principles and Measures of Discharge Piping in Reciprocating Compressor

    Institute of Scientific and Technical Information of China (English)

    李力

    2015-01-01

    往复式压缩机在化工装置中应用非常广泛,但其出口管道如果设计不当,则很容易引起振动,从而对装置的安全造成威胁. 本文剖析了往复式压缩机出口管道的振动原理,论述了往复式压缩机出口管道的防振设计,并提出了消减振动的措施.%Reciprocating compressor is widely used in chemical plants.If its discharge piping is not designed properly, it will result in vibrating and threatening the safety of the plant.This article analyzes the vibration principles of reciprocating compressor discharge piping, expounds its vibration-proof design, and puts forward measures to reduce vibration.

  8. Measured elemental carbon by thermo-optical transmittance analysis in water-soluble extracts from diesel exhaust, woodsmoke, and ambient particulate samples.

    Science.gov (United States)

    Wallén, Anna; Lidén, Göran; Hansson, Hans-Christen

    2010-01-01

    Elemental carbon has been proposed as a marker of diesel particulate matter. The objective of this study was to investigate if water-soluble carbonaceous compounds could be responsible for positive bias of elemental carbon using NIOSH Method 5040 with a thermo-optical carbon transmittance analyzer. Filter samples from eight different aerosol environments were used: pure diesel exhaust fume with a high content of elemental carbon, pure diesel exhaust fume with a low content of elemental carbon, pure biodiesel exhaust fume, pure woodsmoke, an urban road tunnel, an urban street canyon, an urban background site, and residential woodburning in an urban area. Part of each filter sample was analyzed directly with a thermo-optical carbon analyzer, and another part was extracted with water. This water-soluble extract was filtered to remove particles, spiked onto filter punches, and analyzed with a thermo-optical transmittance carbon analyzer. The ratio of elemental carbon in the water-soluble extract to the particulate sample measurement was 18, 12, and 7%, respectively, for the samples of pure woodsmoke, residential woodburning, and urban background. Samples with diesel particulate matter and ambient samples with motor exhaust detected no elemental carbon in the water-soluble extract. Since no particles were present in the filtered water-soluble extract, part of the water-soluble organic carbon species, existing or created during analysis, are misclassified as elemental carbon with this analysis. The conclusion is that in measuring elemental carbon in particulate aerosol samples with thermo-optical transmittance analysis, woodsmoke, and biomass combustion samples show a positive bias of elemental carbon. The water-soluble EC could be used as a simple method to indicate other sources, such as wood or other biomass combustion aerosol particles.

  9. Modal Parameter Identification of Offshore Platforms under Ambient Excitation

    Institute of Scientific and Technical Information of China (English)

    Yang Hezhen(杨和振); Li Huajun

    2004-01-01

    This paper intends to identify the modal parameters of an offshore platform under ambient excitation, and to compare the identified results with theoretical solutions. Using ambient sources of excitation to determine the modal characteristics of large civil engineering structures is desirable for several reasons. The forced vibration testing of such structures generally requires a large amount of specialized equipment and makes the tests quite expensive. Also, an automated health monitoring system for a large civil structure will most likely use ambient excitation. The Eigensystem Realization Algorithm (ERA) is applied in conjunctied acceleration information. Finally, offshore platform numerical model gets output response data under ambient excitation. Simulated data from numerical model of an offshore platform under ambient excitation is used for the identification of the system. According to the comparison results, the proposed method is shown to be effective for modal parameter identification under ambient excitation.

  10. Intellectual productivity under task ambient lighting

    OpenAIRE

    2016-01-01

    A subjective experiment was conducted to evaluate intellectual productivity in three lighting conditions: (a) conventional ambient lighting, (b) task ambient lighting with normal colour temperature (5000 K), and (c) task ambient lighting with high colour temperature (6200 K). In the experiment, cognitive tasks were given to 24 participants. The concentration time ratio, which is a quantitative and objective evaluation index of the degree of concentration, was measured. The results showed that...

  11. The origins of vibration theory

    Science.gov (United States)

    Dimarogonas, A. D.

    1990-07-01

    The Ionian School of natural philosophy introduced the scientific method of dealing with natural phenomena and the rigorous proofs for abstract propositions. Vibration theory was initiated by the Pythagoreans in the fifth century BC, in association with the theory of music and the theory of acoustics. They observed the natural frequency of vibrating systems and proved that it is a system property and that it does not depend on the excitation. Pythagoreans determined the fundamental natural frequencies of several simple systems, such as vibrating strings, pipes, vessels and circular plates. Aristoteles and the Peripatetic School founded mechanics and developed a fundamental understanding of statics and dynamics. In Alexandrian times there were substantial engineering developments in the field of vibration. The pendulum as a vibration, and probably time, measuring device was known in antiquity, and was further developed by the end of the first millennium AD.

  12. Measurement of the membrane dipole electric field in DMPC vesicles using vibrational shifts of p-cyanophenylalanine and molecular dynamics simulations.

    Science.gov (United States)

    Shrestha, Rebika; Cardenas, Alfredo E; Elber, Ron; Webb, Lauren J

    2015-02-19

    The magnitude of the membrane dipole field was measured using vibrational Stark effect (VSE) shifts of nitrile oscillators placed on the unnatural amino acid p-cyanophenylalanine (p-CN-Phe) added to a peptide sequence at four unique positions. These peptides, which were based on a repeating alanine-leucine motif, intercalated into small unilamellar DMPC vesicles which formed an α-helix as confirmed by circular dichroic (CD) spectroscopy. Molecular dynamics simulations of the membrane-intercalated helix containing two of the nitrile probes, one near the headgroup region of the lipid (αLAX(25)) and one buried in the interior of the bilayer (αLAX(16)), were used to examine the structure of the nitrile with respect to the membrane normal, the assumed direction of the dipole field, by quantifying both a small tilt of the helix in the bilayer and conformational rotation of the p-CN-Phe side chain at steady state. Vibrational absorption energies of the nitrile oscillator at each position showed a systematic blue shift as the nitrile was stepped toward the membrane interior; for several different concentrations of peptide, the absorption energy of the nitrile located in the middle of the bilayer was ∼3 cm(-1) greater than that of the nitrile closest to the surface of the membrane. Taken together, the measured VSE shifts and nitrile orientations within the membrane resulted in an absolute magnitude of 8-11 MV/cm for the dipole field, at the high end of the range of possible values that have been accumulated from a variety of indirect measurements. Implications for this are discussed.

  13. Putting a damper on drilling's bad vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, S. (Sedco forex, Montrouge (France)); Malone, D. (Anadrill, Sugar Land, TX (United States)); Sheppard, M. (Schlumberger Cambridge Research, Cambridge (United Kingdom))

    1994-01-01

    Harmful drilling vibrations are costing the industry dearly. Three main vibration types (axial, torsional and transverse) are explained and its causes discussed. Technology exists to eliminate most vibrations, but requires more systematic deployment than is usual. Hardware that eliminates vibrations is reviewed, including downhole shock measurement, torque feedback shock guards and antiwhirl bits. 9 figs., 11 refs.

  14. Psicologia do Ambiente

    OpenAIRE

    Antunes, Dalila; Bernardo, Fátima; Palma-Oliveira, José-Manuel

    2011-01-01

    Na aplicação da Psicologia à área do AMBIENTE importa em primeiro lugar definir o que se entende, neste contexto, por ambiente. O conceito é entendido como toda a envolvente que rodeia o ser humano. Referimo-nos pois ao espaço físico e aos estímulos que nele existem (som, ar, paisagem…), dirigindo-se a Psicologia do Ambiente ao estudo e intervenção sobre a forma como o ambiente influencia o indivíduo ou grupos, e sobre o modo como o comportamento dos indivíduos e grupos influenciam o ambiente...

  15. Novel SiO2-deposited CaF2 substrate for vibrational sum-frequency generation (SFG) measurements of chemisorbed monolayers in an aqueous environment.

    Science.gov (United States)

    Padermshoke, Adchara; Konishi, Shouta; Ara, Masato; Tada, Hirokazu; Ishibashi, Taka-Aki

    2012-06-01

    A novel SiO(2)-deposited CaF(2) (SiO(2)/CaF(2)) substrate for measuring vibrational sum-frequency generation (SFG) spectra of silane-based chemisorbed monolayers in aqueous media has been developed. The substrate is suitable for silanization and transparent over a broad range of the infrared (IR) probe. The present work demonstrates the practical application of the SiO(2)/CaF(2) substrate and, to our knowledge, the first SFG spectrum at the solid/water interface of a silanized monolayer observed over the IR fingerprint region (1780-1400 cm(-1)) using a back-side probing geometry. This new substrate can be very useful for SFG studies of various chemisorbed organic molecules, particularly biological compounds, in aqueous environments.

  16. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  17. Ultrasonic Rotary Motors Using Complex Transverse and Torsional Vibration Rods and Multiple Longitudinal Vibration Transducers

    Science.gov (United States)

    Suzuki, Atsuyuki; Kihara, Masaki; Katsumata, Yasuhiro; Ishii, Keisuke; Tsujino, Jiromaru

    2005-06-01

    The vibration and load characteristics of ultrasonic motors having (a) a torsional vibration cylinder with three bolt-clamped Langevin piezoelectric ceramic (PZT) longitudinal vibration transducers (BLTs) installed in the tangential direction and (b) a longitudinal vibration disk with three BLT transducers installed around a circular disk were studied. The center rod vibrates longitudinally and affects the load characteristics of the ultrasonic motor. Vibration distributions along a center rod were measured using a laser Doppler vibrometer. Revolution, electric input power, mechanical output power and efficiency were measured under various rotating torques. Maximum torque, revolution and efficiency of the ultrasonic motor with (a) a torsional vibration cylinder (a) were 0.75 Nm, 205 rpm and 1.68%, respectively, and (b) 0.32 Nm, 84 rpm and 1.68%, respectively, with a circular longitudinal vibration disk.

  18. From emissions to ambient mixing ratios: on-line seasonal field measurements of volatile organic compounds over a Norway spruce dominated forest in central Germany

    Science.gov (United States)

    Bourtsoukidis, E.; Williams, J.; Kesselmeier, J.; Jacobi, S.; Bonn, B.

    2013-11-01

    Biogenic volatile organic compounds (BVOC) are substantial contributors to atmospheric chemistry and physics and demonstrate the close relationship between biosphere and atmosphere. Their emission rates are highly sensitive to meteorological and environmental changes with concomitant impacts on atmospheric chemistry. We have investigated seasonal isoprenoid and oxygenated VOC (oxVOC) fluxes from a Norway spruce (Picea abies) tree in Central Germany and explored the emission responses under various atmospheric conditions. Emission rates were quantified by using dynamic branch enclosure and Proton Transfer Reaction-Mass Spectrometry (PTR-MS) techniques. Additionally, ambient mixing ratios were derived through application of a new box model treatment on the dynamic chamber measurements. These are compared in terms of abundance and origin with the corresponding emissions. Isoprenoids govern the BVOC emissions from Norway spruce, with monoterpenes and sesquiterpenes accounting for 50.8 ± 7.2% and 19.8 ± 8.1% respectively of the total emissions. Normalizing the VOC emission rates, we have observed a trend of reduction of carbon containing emissions from April to November, with an enhancement of oxVOC. Highest emission rates were observed in June for all measured species, with the exception of sesquiterpenes that were emitted most strongly in April. We exploit the wide range of conditions experienced at the site to filter the dataset with a combination of temperature, ozone and absolute humidity values in order to derive the emission potential and temperature dependency development for the major chemical species investigated. A profound reduction of monoterpene emission potential (E30) and temperature dependency (β) was found under low temperature regimes, combined with low ozone levels (E30MT, LTLO3=56 ± 9.1 ng g(dw)-1 h-1, βMT,LTLO3=0.03±0.01 K-1) while a combination of both stresses was found to alter their emissions responses with respect to temperature

  19. 基于磁悬浮效应的三维振动测量%Three-dimensional vibration measurement based on magnetic levitation effect

    Institute of Scientific and Technical Information of China (English)

    江东; 杨嘉祥

    2011-01-01

    设计了磁悬浮球系统模型,测量一定电流下磁悬浮球位移与受力得到磁悬浮球的电磁力表达式,推导了磁悬浮球运动的动力学方程.实测中磁悬浮球模型壳体与被测振动体刚性连接,通过光电传感器测出磁悬浮球与壳体的相对位移得到三维被测振动信号.通过标准振动台实测验证,小于120 Hz的最大绝对误差为±0.3 Hz,相对误差为±1.5%~±0.25%,120 Hz~5 kHz的最大绝对误差为±1Hz,相对误差为±0.83%-±0.02%.由于磁悬浮球悬浮于空中,灵敏度高,具有良好的频率响应特性,磁悬浮球运动各向同性,不存在因粘贴传感元件带来的极间耦合问题,与传统多维振动测量方法相比较该方法具有独特的优势.%A magnetic levitation ball system model was designed. The magnetic force that magnetic levitation ball bears was measured under fixed current and changing displacement. The dynamic equation of magnetic levitation ball movement is deduced. The shell of magnetic levitation ball system model joins up with the vibrating object under test rigidly in the test experiment. A photo-electric sensor is used to measure the relative displacement between the shell of the system model and the magnetic levitation ball, and three-dimensional vibration signals are obtained. Standard vibrator test verifies that the maximum absolute error is ±0.3 Hz and relative error is between ±1.5% and ±0.25%for frequency below 120 Hz, the maximum absolute error is ±1 Hz and relative error is between ±0.83% and ±0.02%for frequency between 120 Hz~5 kHz. Because magnetic levitation ball suspends in the air and the system does not have any pasted sensor, the effects from other directions do not exist. The system has excellent frequency feature and the features at different directions are the same. The system sensitivity is high. This method has better characteristics than traditional vibration measurement methods.

  20. Pickin’ up good vibrations

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins.   A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...

  1. 量度及預測隧道鑽機的土傳噪音及震動%Measurement and prediction of groundborne noise and vibration from a tunnel boring machine

    Institute of Scientific and Technical Information of China (English)

    何偉麟

    2006-01-01

    在市區進行夜間隧道鑽挖工程所産生的土傳噪音及震動,容易引起投訴.現時的技術難以準確預測噪音及震動的級數,而隧道工程的進度也常因進行隧道鑽挖工程時產生過大的土傳噪音及震動而延誤.本文所提述的新技術,可以更準確地量度及預測鑽機震動强度及土壤傳震的特性.這個技術包括測量單位衝擊力及隧道鑽機摩擦力所産生的震動級數.其實早於80於代,美國政府運輸部門(U.S.Dept of Transportation Federal Transit Administrative)已研發相關的技術,並將該技術應用於鐵路土傳噪音量度及預測上.本文報告隧道鑽機所產生的土傳噪音及震動級數1/3倍频帶數值的量度及預測.比較地面震動峰值速度(PPV)、最高(Lmax)噪聲和振動級數按快速和緩慢的時間常數和整體百分比(Percentile)數值列出.%A new empirical method for prediction of groundborne noise and vibration (GBN&V) induced by tunnel boring machine (TBM) has been developed. The method is based on empirical determination of ground vibration transmissibility and TBM vibration source strength. The method includes measurements of ground vibration levels caused by unit force impacts and TBM operation at various setbacks. With these measured data, the ground vibration transfer mobility and TBM vibration source strength are determined separately. Prediction of TBM-induced GBN&V is performed by combining the determined TBM vibration source strength and the further measurement data of ground vibration transfer mobility by impacting in boreholes along the proposed tunnel alignment. Predicted GBN&V levels are presented in 1/3 octave spectrum at various setbacks from the tunnel alignment.Comparisons are given in predicted peak particle velocity (PPV), maximum noise and vibration levels in fast and slow time constant and overall percentile values (cumulative probability distributions).

  2. Vibration measurement and analysis of tracked-whole feeding rice combine harvester%履带式全喂入水稻联合收获机振动测试与分析

    Institute of Scientific and Technical Information of China (English)

    徐立章; 李耀明; 孙朋朋; 庞靖

    2014-01-01

    针对国产履带式全喂入水稻联合收获机整机振动大、无故障工作时间短、可靠性差等问题,以沃得巨龙280型联合收获机为研究对象,在发动机空载、整机空载和田间收获等5种工况下,采用DH5902动态信号分析系统对整机多点振动情况进行了测试与分析,得到了8个测点的时域特性和频谱特性的分布规律。试验结果表明:发动机的上下振动、振动筛的前后运动和切割器的左右运动是形成水稻联合收获机整机振动的主要原因,而输送槽、风机和脱粒滚筒等部件的回转运动为次要原因。整机全油门空载工况下发动机引起的振动频率为71.78 Hz,振动筛、切割器、风机、脱粒滚筒I和脱粒滚筒II引起的激振频率分别为6.35、8.79、19.04、12.70和23.44 Hz,驾驶座椅的减振结构需进一步优化。研究结果为改善履带式全喂入水稻联合收获机的驾驶舒适性,提高其工作可靠性提供参考。%In order to solve the problems of violent vibration, short time between failures and poor reliability existing in the crawler-type rice combine in China, experiments were conducted to analyze the characteristic of vibration source on combine World Dragon 280. 8 measuring points of engine support, cutter drive shaft support, vibrating sieve drive shaft support, drum support I, drum support II, chute driving wheel support, fan shaft support, and seat support were marked on the combine. Time-domain signals and frequency spectral characteristics of 8 measuring points were measured and analyzed by 5902 dynamic signal analytical systems in 5 different conditions such as no-load mode of engine, no-load mode of the whole machine and field harvesting. The result shows that up-and-down vibration of the engine, before-and-after vibration of the vibrating screen and left-and-right vibration of the sickle are the main causes of whole machine vibration, and Rotary motions of conveying

  3. Vibrational spectroscopy at electrified interfaces

    CERN Document Server

    Wieckowski, Andrzej; Braunschweig, Björn

    2013-01-01

    Reviews the latest theory, techniques, and applications Surface vibrational spectroscopy techniques probe the structure and composition of interfaces at the molecular level. Their versatility, coupled with their non-destructive nature, enables in-situ measurements of operating devices and the monitoring of interface-controlled processes under reactive conditions. Vibrational Spectroscopy at Electrified Interfaces explores new and emerging applications of Raman, infrared, and non-linear optical spectroscopy for the study of charged interfaces. The book draws from hu

  4. Analysis of real-time vibration data

    Science.gov (United States)

    Safak, E.

    2005-01-01

    In recent years, a few structures have been instrumented to provide continuous vibration data in real time, recording not only large-amplitude motions generated by extreme loads, but also small-amplitude motions generated by ambient loads. The main objective in continuous recording is to track any changes in structural characteristics, and to detect damage after an extreme event, such as an earthquake or explosion. The Fourier-based spectral analysis methods have been the primary tool to analyze vibration data from structures. In general, such methods do not work well for real-time data, because real-time data are mainly composed of ambient vibrations with very low amplitudes and signal-to-noise ratios. The long duration, linearity, and the stationarity of ambient data, however, allow us to utilize statistical signal processing tools, which can compensate for the adverse effects of low amplitudes and high noise. The analysis of real-time data requires tools and techniques that can be applied in real-time; i.e., data are processed and analyzed while being acquired. This paper presents some of the basic tools and techniques for processing and analyzing real-time vibration data. The topics discussed include utilization of running time windows, tracking mean and mean-square values, filtering, system identification, and damage detection.

  5. Raman spectroscopy measurements of the vibrational properties of uv-polymerized C60 thin film and C60 powder compressed in a diamond anvil cell

    Science.gov (United States)

    Li, Y.; Singh, D.; Sharma, S. C.

    2002-03-01

    We present results from a series of experiments designed to further study the effects of pressure on the vibrational properties of C60 compressed under high pressures (10 GPa) in a diamond anvil cell. The Raman scattering measurements were made by using a high resolution optical spectrometer that consists of a 1.25 m, f/11 monochromator, 2400 g/mm, ion-etched blazed holographic diffraction grating, 2048x512 pixel back illuminated liquid nitrogen cooled CCD camera, Super-Notch-Plus filter, argon-ion laser operating at 514.5 nm, and SpectraMax for Windows software. The Raman scattering measurements on C60 thin films show a large ( 10 cm-1) and characteristic red shift in the pentagonal pinch mode Ag(2) of pristine C60 upon irradiation by 21.2 eV photons. Upon heating this film under 10(-3) Torr vacuum at 413 and 473 K, the Raman spectra shift towards the pentagonal pinch mode of pristine C60. These results are in agreement with previously published data (1,2) and they show that the film is polymerized because of uv irradiation. We have also measured spectra for C60 powder compressed under high pressures in a diamond anvil cell. We present results for several frequencies of the Raman active modes of C60. 1. A. M. Rao et al, Science 259, 955 (1993); 2. S. C. Sharma et al, Mat. Res. Symp. Proc. 695, L3.10 (2002)

  6. DERECHO AMBIENTAL EN ARGENTINA

    OpenAIRE

    2014-01-01

    El objetivo de la presente publicación es brindar un panorama general, introductorio y actualizado del derecho ambiental argentino. Entendiendo que el derecho ambiental es un signo de nuestra era y que por la dinamicidad de la cuestión ambiental requiere de permanente actualización regularoria. La autora desarrolla en forma objetiva su postura en relación con la necesidad de hacer sostenible al derecho ambiental. Para luego analizar brevemente la situación actual del derecho vigente en Argent...

  7. Elimination of flow-induced pulsations and vibrations in a process installation: a combination of on site measurements, calculations and scale modeling

    NARCIS (Netherlands)

    Bokhorst, E. van; Peters, M.C.A.M.

    2008-01-01

    The aim of the work described in this paper was to trace and eliminate vibration sources in a low pressure system with high flow velocities. Considerable vibration on the pipe system between a flashing vessel (6.5 m diameter) and heat-exchangers resulted in fatigue failure, leakage and subsequent sh

  8. Method of Measuring the Vapor Pressure and Concentration of Fluids using VLE and Vibrating Tube Densitometer Apparatuses

    OpenAIRE

    Abdalla, Momin Elhadi; Pannir, Siddharth

    2016-01-01

    This work presents the vapor pressure and concentration measurement of newly discovered environmentally friendly refrigerants 1, 1-difluoroethane (R152a) and 1,1,1,3,3-Pentafluorbutane (R365mfc), besides their mixture. The experimental procedure used in this work was a VLE recirculation type apparatus in which the liquid phase is circulating around the equilibrium cell. Special attention was given to enable a highly accurate vapor pressure measurement up to maximum pressure of 25 bar. The li...

  9. Effects of ambient versus reduced UV-B radiation on high arctic Salix arctica assessed by measurements and calculations of chlorophyll-a fluorescence parameters from fluorescence transients

    DEFF Research Database (Denmark)

    Albert, Kristian Rost

    2005-01-01

    cross-section of leaf sample, the number of active PSII reaction centres (RC/ CSM) and electron transport rate (ETM/CSM) and all performance indexes (PIABS, PICSo and PICSm) were increased in reduced UV-B. The total soluble flavonoid content was highest in ambient UV-B. The treatment effects......A UV-B exclusion-experiment was conducted in the high arctic Zackenberg, NE Greenland, in which Salix arctica leaves during most of the growing season were fixed perpendicular to the solar zenith angle, thereby receiving maximal solar radiation. Covered with Teflon and Mylar foil, the leaves...... received approximately 90 and 40% of the ambient UV-B irradiance, respectively. The effects were examined through recordings of chlorophyll a fluorescence transients, determination of biomass and analysis of total carbon and nitrogen content and amount of soluble flavonoids in the leaves. The processing...

  10. Long-term monitoring and seasonal analysis of polycyclic aromatic hydrocarbons (PAHs) measured over a decade in the ambient air of Porto, Portugal.

    Science.gov (United States)

    Albuquerque, M; Coutinho, M; Borrego, C

    2016-02-01

    The present paper reports the analytical results of PAHs concentrations in ambient air obtained in the PM10 and gas-phase, from 2004 to 2014, in Porto, Portugal. As part of a monitoring programme conducted by IDAD - Institute of Environment and Development and supported by the regional municipal solid waste (MSW) management authorities, an extensive database of PAH concentrations in ambient air was collected in Porto's metropolitan area. During this period a total of 201 samples were collected in two sites classified as suburban. Analytical results showed a clear decreasing trend of total PAHs (∑PAH) and benzo[a]pyrene (BaP) levels during the period of study, especially in the first years of monitoring. The average annual concentrations of BaP were, throughout the monitoring period, lower than the target value for the annual average (1 ng m(-3)) defined in the European legislation. PAHs levels showed a strong seasonality, with higher concentrations values during the colder months. The winter/summer ratio of ∑PAH for the eleven years of study was 5, revealing the seasonal variation of PAHs in the studied area. The estimated toxic equivalency factors (TEFs) used to assess the contribution of the carcinogenic potential, confirmed a significant presence of the moderately active carcinogenic BaP and dibenz[ah]anthracene (DahA) in the samples collected in Porto. The ratio values of individual PAHs concentrations were used as diagnostic tool to identify the possible origin of PAH in the ambient air of Porto. Based on diagnostic ratios, it may be concluded that automobile traffic emissions, mainly related to diesel vehicles, were the major contribution of PAH levels in the ambient air, although some others contributions, such as coal and wood combustion, were identified.

  11. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  12. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    1998-01-01

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  13. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  14. Radiactividad y medio ambiente

    OpenAIRE

    Sánchez León, José Guillermo

    1993-01-01

    En los medios de comunicación frecuentemente aparecen noticias que hacen referencia a la radiactividad y al medio ambiente y, sin embargo, lo que es la radiactividad y como influye ésta sobre el medio ambiente suele ser poco conocido, incluso por personas de formación científica.

  15. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    Science.gov (United States)

    Ortega, Amber M.; Hayes, Patrick L.; Peng, Zhe; Palm, Brett B.; Hu, Weiwei; Day, Douglas A.; Li, Rui; Cubison, Michael J.; Brune, William H.; Graus, Martin; Warneke, Carsten; Gilman, Jessica B.; Kuster, William C.; de Gouw, Joost; Gutiérrez-Montes, Cándido; Jimenez, Jose L.

    2016-06-01

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient and reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days-6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8-6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ˜ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ˜ -0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ˜ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and also extends to

  16. 49 CFR 325.55 - Ambient conditions; stationary test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Ambient conditions; stationary test. 325.55... MOTOR CARRIER NOISE EMISSION STANDARDS Measurement of Noise Emissions; Stationary Test § 325.55 Ambient conditions; stationary test. (a)(1) Sound. The ambient A-weighted sound level at the microphone...

  17. DERECHO AMBIENTAL EN ARGENTINA

    Directory of Open Access Journals (Sweden)

    Silvia Nonna

    2014-05-01

    Full Text Available El objetivo de la presente publicación es brindar un panorama general, introductorio y actualizado del derecho ambiental argentino. Entendiendo que el derecho ambiental es un signo de nuestra era y que por la dinamicidad de la cuestión ambiental requiere de permanente actualización regulatoria. La autora desarrolla en forma objetiva su postura en relación con la necesidad de hacer sostenible al derecho ambiental. Para luego analizar brevemente la situación actual del derecho vigente en Argentina, haciendo un rápido y resumido recorrido desde la última reforma de la Constitución Nacional hasta la consideración especial de cada una de las nuevas normas de presupuestos mínimos de protección ambiental.

  18. Micro energy harvesting from ambient motion : modeling, simulation and design

    Energy Technology Data Exchange (ETDEWEB)

    Blystad, Lars-Cyril

    2012-07-01

    Vibration energy harvesting is the process of converting available ambient kinetic energy into useful electrical energy. It can be done on large scale with e.g. a wind-driven turbine. This thesis deals with small scale energy harvesters that are suitable for fabrication in Micro electromechanical Systems (MEMS) technologies. Such MEMS energy harvesters have the potential to supply power for micro power devices. Modeling, simulation and design of MEMS vibration energy harvesters are the foci of this thesis. Transduction mechanisms that are covered are electrostatic and piezoelectric. Electric equivalent circuits are obtained for the use in electromechanical simulations with the circuit simulator SPICE. The feasibility of simulating both narrow- and broadband vibrations, to model different external driving forces, in a standard circuit simulator is demonstrated. Comparisons of the har- vesters performance for different excitations are presented. A selection of passive and active power conditioning circuits is investigated and their performances compared. The active nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical end stops are in effect. The active switching circuits give higher electromechanical damping, and thus can be driven at higher acceleration amplitudes before end stops are engaged. Mechanical end stops have to be present in all MEMS vibrational energy harvesters. Either due to space limitations, reliability issues, Simliberate introduction of nonlinearities or a combination of these. ulations in the thesis include mechanical end stops and thus include the corresponding nonlinearities introduced in the system. When the mechanical end stops are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present. The end stops increase the effective bandwidth at large acceleration amplitudes. End stops limit the output power for sinusoidal

  19. 偏振耦合测试及其振动干扰信号分析%Measurement of Polarization Coupling and Analysis of Vibration Disturbance Signal

    Institute of Scientific and Technical Information of China (English)

    郭振武; 张红霞; 贾大功; 陈信伟; 刘铁根

    2011-01-01

    The principle of the mode coupling in polarization maintaining fiber (PMF) is analyzed. The measurement method of polarization coupling based on white-light interferometry with Michelson-interferometer is presented. The optical path difference (OPD) between the two arms of Michelson interferometer, changed by the movement of the scanning arm reflector driven by a step motor, compensates the OPD of the two orthogonal beams resulting from polarization coupling to realize the measurement of polarization coupling intensity and the spatial distribution along the PMF. Analysis and emulation are carried out for the disturbance signal of the mechanical scanning vibration and the influence of the vibration imposed on the output signal. The coupling intensity is calculated from the envelope of the output signal which is extracted by Hilbert transform and least squares Gaussian fitting under different scanning speeds. It's indicated that the vibration amplitude and frequency which affect the detection accuracy are related to the scanning speed. And the detection error reaches the minimum when the scanning speed of the system is from 0. 7 to 0.9 mm/s.%理论分析了偏振模式耦合的原理,给出了基于白光干涉的偏振耦合检测方法.通过步进电机控制迈克耳孙干涉仪扫描臂的反射镜移动,改变干涉仪两臂之间的光程差(OPD),补偿了由于偏振耦合而形成的两偏振光从保偏光纤(PMF)出射时的光程差,实现了对保偏光纤的偏振耦合强度和位置的测试.扫描过程中扫描臂反射镜的振动会对输出信号产生不良影响,对此振动信号进行了仿真及实验研究,分析了它对输出信号的影响.在不同的扫描速度下,采用Hilbert变换和最小二乘高斯非线性回归分析提取白光干涉包络,求解耦合强度,验证了振动信号的幅度和频率与扫描速度有关,以及它对耦合强度检测精度的影响.结果表明该测试系统动镜的扫描速度在0.7-0.9mm/s

  20. STRUCTURAL PHASE TRANSITION OF ALIPHATIC NYLONS VIEWED FROM THE WAXD/SAXS AND VIBRATIONAL SPECTRAL MEASUREMENTS AND MOLECULAR DYNAMICS CALCULATION

    Institute of Scientific and Technical Information of China (English)

    Kohji Tashiro

    2007-01-01

    The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the molecular dynamics calculation. An interpretation of infrared spectra taken for a series of nylon samples and the corresponding model compounds was successfully made, allowing us to assign the infrared bands of the planar-zigzag methylene segments reasonably. As a result the methylene segmental parts of molecular chains were found to experience an order-to-disorder transition in the Brill transition region, where the intermolecular hydrogen bonds are kept alive although the bond strength becomes weaker at higher temperature. The small-angle X-ray scattering data revealed a slight change in lamellar stacking mode in the transition region. The crystal structure has been found to change more remarkably in the temperature region immediately below the melting point, where the conformationally disordered chains experienced drastic rotational and translational motions without any constraints by hydrogen bonds, and the lamellar thickness increased largely along the chain axis. These experimental results were reasonably reproduced by the molecular dynamics calculation performed at the various temperatures.