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Nonstationary pearl pulsations as a signature of magnetospheric disturbances  [PDF]
F. Z. Feygin,N. G. Kleimenova,O. A. Pokhotelov,M. Parrot
Annales Geophysicae (ANGEO) , 2003,
Abstract: We analyse long-lasting (several hours) Pc1 pearl pulsations with decreasing, increasing or constant central frequencies. We show that nonstationary pearl events (those with either decreasing or increasing central frequency) are observed simultaneously with increasing auroral magnetic activity at the nightside magnetosphere while the stationary events (constant central frequency) correspond to quiet magnetic conditions. Events with decreasing central frequency are observed mostly in the late morning and daytime whereas events with increasing central frequency appear either early in the morning or in the afternoon. We explain the diurnal distribution of the nonstationary pearl pulsations in terms of proton drifts depending on magnetic activity, and evaluate the magnetospheric electric field based on the variation of the central frequency of pearl pulsations. Key words: Magnetospheric physics (magnetospheric configuration and dynamics; plasma waves and instabilities)
Asymptotics for general nonstationary fractionally integrated processes without prehistoric influence  [PDF]
Qiying Wang,Yan-Xia Lin,Chandra Gulati
Advances in Decision Sciences , 2002, DOI: 10.1155/s1173912602000184
Abstract: This paper derives a functional limit theorem for general nonstationary fractionally integrated processes having no influence from prehistory. Asymptotic distributions of sample autocovariances and sample autocorrelations based on these processes are also investigated. The problem arises naturally in discussing fractionally integrated processes when the processes starts at a given initial date.
Health Monitoring for a Structure Using Its Nonstationary Vibration  [PDF]
Yoshimutsu Hirata,Mikio Tohyama,Mitsuo Matsumoto,Satoru Gotoh
Advances in Acoustics and Vibration , 2010, DOI: 10.1155/2010/696512
Abstract: The frequency distribution of a short interval period, the SIP distribution, obtained from the vibration of a structure that is excited by the force of non-stationary vibration is available for the robust estimation of the dynamic property of the structure. This paper shows experiments of the health monitoring of a model structure using the SIP distribution. Comparisons of SIP distributions with average DFT spectra are also shown. 1. Introduction One of the major problems after an earthquake, which causes certain changes in the dynamic property of a structure, is the investigation of structural damage. In principle, we can check the change using a shaker to obtain the frequency response of a structure. However, it is difficult and not practical to shake a big structure before and after an earthquake to detect the change. Regardless of size or weight, all structures such as buildings, towers, and bridges are vibrating due to the natural force of winds, ground motions, or both. Information of the dynamic property of a building, for example, is comprised of the forced vibration of a structure. Changes of dynamic property reflect structural changes. Then, the problem is how to extract information from the vibration of structures. It was shown by one of the authors that the frequency distribution of a short-interval period, the SIP distribution, of the forced nonstationary vibration corresponds to the frequency response of a structure [1]. In this paper, experiments of health monitoring of a model structure using its nonstationary vibrations are shown, where SIP distributions are used for detecting the changes of the dynamic property of a structure. 2. SIP Distributions The discrete Fourier transform (DFT) is used in many disciplines to obtain the spectrum or frequency of a signal. The DFT produces reasonable results for a large class of signal processes. However, we do not use the DFT for detecting a short interval period because of its inherent limitation of frequency resolution [2]. The dominant frequency or period of a short-interval sequence can be given by the nonharmonic Fourier analysis [3]. In the process of the analysis, we put where , and obtain Fourier coefficients and for an arbitrary frequency such that Hence, if we put we have the dominant frequency which satisfies It should be noted that we attain a least squares fit of to a sinusoid by . The SIP distribution is given by a number of dominant frequencies (or periods) of short sequences which are fractions of measured data. Thus, the normalized SIP distribution gives the probability of the
An Integrated Real-Time Beamforming and Postfiltering System for Nonstationary Noise Environments  [cached]
Baruch Berdugo,Sharon Gannot,Israel Cohen
EURASIP Journal on Advances in Signal Processing , 2003, DOI: 10.1155/s1687617203305050
Abstract: We present a novel approach for real-time multichannel speech enhancement in environments of nonstationary noise and time-varying acoustical transfer functions (ATFs). The proposed system integrates adaptive beamforming, ATF identification, soft signal detection, and multichannel postfiltering. The noise canceller branch of the beamformer and the ATF identification are adaptively updated online, based on hypothesis test results. The noise canceller is updated only during stationary noise frames, and the ATF identification is carried out only when desired source components have been detected. The hypothesis testing is based on the nonstationarity of the signals and the transient power ratio between the beamformer primary output and its reference noise signals. Following the beamforming and the hypothesis testing, estimates for the signal presence probability and for the noise power spectral density are derived. Subsequently, an optimal spectral gain function that minimizes the mean square error of the log-spectral amplitude (LSA) is applied. Experimental results demonstrate the usefulness of the proposed system in nonstationary noise environments.
Forest Biodiversity Assessment in Relic Ecosystem: Monitoring and Management Practice Implications  [PDF]
Elsa Sattout,Peter D. S. Caligari
Diversity , 2011, DOI: 10.3390/d3030531
Abstract: The remnants of old-growth cedar forests in Lebanon are currently protected since they are taken to represent relic ecosystems sheltering many endemic, rare and endangered species. However, it is not always obvious how “natural” these forest relics are, and how the past use, conservation and management history have affected their current structural properties and species community composition. Even though Integrated Monitoring Programs have been initiated and developed, they are not being implemented effectively. The present research studied the effect of forest stand structure and the impacts of the anthropogenic activities effects on forest composition and floristic richness in four cedar forests in Lebanon. Horizontal and vertical structure was assessed by relying on the measurement of the physical characteristics and status of cedar trees including diversity and similarity indices. Two hundred and seventeen flora species were identified, among which 51 species were found to have biogeographical specificity and peculiar traits. The species composition seems not to be correlated with stand age structure; however, the occurrence of multiple age cedar stands favors floristic richness and variability in species composition as observed in one of the stands where the variation in diversity indices was high. In conclusion; to conserve biodiversity across landscapes, it is necessary to maintain a collection of stands of different vertical structure; an effect produced both by natural and anthropogenic disturbances since they both create a mosaic of different aged succession stands.
Design of an Automatic Power Quality Monitoring System by Using Integrated Approach
H.K. Siu,T.S. Chung
International Journal of Electrical and Power Engineering , 2012,
Abstract: The quality of electricity has been gaining more emphasis among utilities, service sectors and consumers. Good quality of electricity has to be maintained by strategic measures in coping with all sort of disturbances generated intrinsically in modern power electronic equipments and large commercial buildings. A means of improving electric power quality starts by a systematic identification of the power system disturbances which is posed to be a big challenge. The conventional approach based on Fourier Transform principles has its main drawback of losing the time-domain feature after transformation. In this context the technique of using wavelet transform appears to be more promising with its strength on handling signals on short time intervals for high frequency components and long time intervals for low frequency components. This study will propose a new approach called integrated approach by integrating the advantages of both Fourier and wavelet transforms. The wavelet transform is used to extract the required time-domain information from the high frequency components while the Fourier transform is used to provide the accurate measurement from the low frequency components. An automatic power quality monitoring system based on the integrated approach is then developed. Neural network classifier and adaptive neuro-fuzzy classifier are selected to implement the proposed approach of which its training and validation are performed via simulated data set and some real disturbance waveforms, respectively.
Integrated Monitoring System for Durability Assessment of Concrete Bridges  [PDF]
Cristian-Claudiu Comisu
Bulletin of the Polytechnic Institute of Jassy, Constructions, Architechture Section , 2005,
Abstract: An ageing and deteriorating bridge stock presents the bridge owners with the growing challenge of maintaining the structures at a satisfactory level of safety, performance and aesthetic appearance within the allocated budgets. This task calls for optimized bridge management based on efficient methods of selecting technical and economical optimal maintenance and rehabilitation strategies. One of the crucial points in the assessment of the current condition and future development and performance. Selecting the optimal maintenance and rehabilitation strategy within the actual budget is a key point in bridge management for which an accurate assessment of performance and deterioration rate is necessary. For this assessment, the use of integrated monitoring system has several advantages compared to the traditional approach of scattered visual inspections combined with occasional on site testing with portable equipment and laboratory testing of collected samples. For this reason, attention is more focusing on the development of permanent integrated monitoring system for durability assessment of concrete bridges. It is estimated that with the implementation of such integrated monitoring systems, it should be possible to reduce the operating costs of inspections and maintenance by 25% and the operator of the structures will be able to take protective actions before damaging processes start. This paper indentifies the main bridge owner requirements to integrated monitoring systems and outlines how monitoring systems may be used for performance and deterioration rate assessment to establish a better basis for selecting the optimal maintenance and rehabilitation strategy.
Approaches to integrated monitoring for environmental health impact assessment
Hai-Ying Liu, Alena Bartonova, Mathilde Pascal, Roel Smolders, Erik Skjetne, Maria Dusinska
Environmental Health , 2012, DOI: 10.1186/1476-069x-11-88
Abstract: Integrated Environmental Health Monitoring (IEHM) is essential for identifying key stressors on the environment, to assess the state of the environment, and to evaluate the health impact of environmental changes [1]. Currently, there is no agreed definition of IEHM. The European Union (EU) funded project INTARESE (Integrated Assessment of Health Risks of Environmental Stressors in Europe) explored ways of linking and integrating various information sources and technologies to provide a more unified approach to IEHM.The aim of IEHM is to provide unbiased data of appropriate quality and quantity for IEHIA (Integrated environmental health impact assessment), defined as ‘an inclusive and, as far as feasible, comprehensive assessment of the risks to, and impacts on, human health as a result either of exposures to a defined set of environmental hazards or of the effects of policies or other interventions that operate via the ambient or living environment’ [2,3]. Accordingly, information is required about the nature, the causes, and the inter-linkages between existing environmental health risks. In the past, research studies and policy actions often addressed single-pollutant and single-effect relationships, and there was no integration of data on exposure and impact of environmental changes on human health [4]. Recently however, efforts to understand the links between multiple stressors and multiple health effects are rapidly increasing. Experience has shown that integrated studies are often limited by the lack of data, or by the fact that different data collection systems have different goals and are, therefore, not easily combined.The key issue for IEHM is to consider monitoring as a tool to measure, analyse and interpret the impact of environmental changes on human health, to support more effective decision-making. Ideally, a systematic, iterative process based on the knowledge of the cause-effect chain is needed to describe the interconnected environment and health (E
Integrated Monitoring of Multi-Domain Backbone Connections  [PDF]
Patricia Marcu,David Schmitz,Wolfgang Fritz,Mark Yampolskiy
International Journal of Computer Networks & Communications , 2011,
Abstract: Novel large scale research projects often require cooperation between various different project partnersthat are spread among the entire world. They do not only need huge computing resources, but also areliable network to operate on. The Large Hadron Collider (LHC) at CERN is a representative examplefor such a project. Its experiments result in a vast amount of data, which is interesting for researchersaround the world. For transporting the data from CERN to 11 data processing and storage sites, anoptical private network (OPN) has been constructed. As the experiment data is highly valuable, LHCdefines very high requirements to the underlying network infrastructure. In order to fulfil thoserequirements, the connections have to be managed and monitored permanently. In this paper, we presentthe integrated monitoring solution developed for the LHCOPN. We first outline the requirements andshow how they are met on the single network layers. After that, we describe, how those singlemeasurements can be combined into an integrated view. We cover design concepts as well as toolimplementation highlights.
Advances in Integrated Vehicle Health Monitoring Systems
Debopam Acharya,Hyo-Joo Han
International Journal of Interactive Mobile Technologies (iJIM) , 2011, DOI: 10.3991/ijim.v5i3.1671
Abstract: One of the fastest growing fields of study in defense market currently is Integrated Vehicle Health Monitoring (IVHM). These systems perform collection and analysis of data concerning operating parameters and damage information of vehicles in real-time and periodically send them to the base station for appropriate action. Recent advances in materials and sensor networks and technologies promise development of such systems for land, water, and aerial vehicles. These IVHM systems are of immense use in defense services which require their vehicles and systems to operate normally even under hostile and harsh environments. This work will discuss various issues related to IVHMs and prominent sensor technologies available to build such systems. It will also include the structure of a general purpose IVHM of a vehicle which can be used to monitor its inner operating parameters and damage information of its components.
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