WorldWideScience

Sample records for based distributed spectrum

  1. Broadband Cooperative Spectrum Sensing Based on Distributed Modulated Wideband Converter

    Directory of Open Access Journals (Sweden)

    Ziyong Xu

    2016-09-01

    Full Text Available The modulated wideband converter (MWC is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount of sampling channels increases proportionally. Besides, it is very hard to adjust the number of sampling channels when the sparsity changes, because its undersampling board is designed by a given sparsity. Such hardware cost and inconvenience are unacceptable in practical applications. This paper proposes a distributed modulated wideband converter (DMWC scheme innovatively, which regards one sensor node as one sampling channel and combines MWC technology with a broadband cooperative spectrum sensing network perfectly. Being different from the MWC scheme, DMWC takes phase shift and transmission loss into account in the input terminal, which are unavoidable in practical application. Our scheme is not only able to recover the support of broadband sparse signals quickly and accurately, but also reduces the hardware cost of the single node drastically. Theoretical analysis and numerical simulations show that phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent. Nevertheless, we can increase the amount of cooperative nodes and select satisfactory nodes by a different transmission distance to improve the recovery performance. Furthermore, we can adjust the amount of cooperative nodes flexibly when the sparsity changes. It indicates DMWC is extremely effective in the broadband cooperative spectrum sensing network.

  2. Distributed optical fiber vibration sensor based on spectrum analysis of Polarization-OTDR system.

    Science.gov (United States)

    Zhang, Ziyi; Bao, Xiaoyi

    2008-07-07

    A fully distributed optical fiber vibration sensor is demonstrated based on spectrum analysis of Polarization-OTDR system. Without performing any data averaging, vibration disturbances up to 5 kHz is successfully demonstrated in a 1km fiber link with 10m spatial resolution. The FFT is performed at each spatial resolution; the relation of the disturbance at each frequency component versus location allows detection of multiple events simultaneously with different and the same frequency components.

  3. Fiber-distributed Ultra-wideband noise radar with steerable power spectrum and colorless base station.

    Science.gov (United States)

    Zheng, Jianyu; Wang, Hui; Fu, Jianbin; Wei, Li; Pan, Shilong; Wang, Lixian; Liu, Jianguo; Zhu, Ninghua

    2014-03-10

    A fiber-distributed Ultra-wideband (UWB) noise radar was achieved, which consists of a chaotic UWB noise source based on optoelectronic oscillator (OEO), a fiber-distributed transmission link, a colorless base station (BS), and a cross-correlation processing module. Due to a polarization modulation based microwave photonic filter and an electrical UWB pass-band filter embedded in the feedback loop of the OEO, the power spectrum of chaotic UWB signal could be shaped and notch-filtered to avoid the spectrum-overlay-induced interference to the narrow band signals. Meanwhile, the wavelength-reusing could be implemented in the BS by means of the distributed polarization modulation-to-intensity modulation conversion. The experimental comparison for range finding was carried out as the chaotic UWB signal was notch-filtered at 5.2 GHz and 7.8 GHz or not. Measured results indicate that space resolution with cm-level could be realized after 3-km fiber transmission thanks to the excellent self-correlation property of the UWB noise signal provided by the OEO. The performance deterioration of the radar raised by the energy loss of the notch-filtered noise signal was negligible.

  4. A new approach for beam hardening correction based on the local spectrum distributions

    Energy Technology Data Exchange (ETDEWEB)

    Rasoulpour, Naser; Kamali-Asl, Alireza, E-mail: a_kamali@sbu.ac.ir; Hemmati, Hamidreza

    2015-09-11

    Energy dependence of material absorption and polychromatic nature of x-ray beams in the Computed Tomography (CT) causes a phenomenon which called “beam hardening”. The purpose of this study is to provide a novel approach for Beam Hardening (BH) correction. This approach is based on the linear attenuation coefficients of Local Spectrum Distributions (LSDs) in the various depths of a phantom. The proposed method includes two steps. Firstly, the hardened spectra in various depths of the phantom (or LSDs) are estimated based on the Expectation Maximization (EM) algorithm for arbitrary thickness interval of known materials in the phantom. The performance of LSD estimation technique is evaluated by applying random Gaussian noise to transmission data. Then, the linear attenuation coefficients with regarding to the mean energy of LSDs are obtained. Secondly, a correction function based on the calculated attenuation coefficients is derived in order to correct polychromatic raw data. Since a correction function has been used for the conversion of the polychromatic data to the monochromatic data, the effect of BH in proposed reconstruction must be reduced in comparison with polychromatic reconstruction. The proposed approach has been assessed in the phantoms which involve less than two materials, but the correction function has been extended for using in the constructed phantoms with more than two materials. The relative mean energy difference in the LSDs estimations based on the noise-free transmission data was less than 1.5%. Also, it shows an acceptable value when a random Gaussian noise is applied to the transmission data. The amount of cupping artifact in the proposed reconstruction method has been effectively reduced and proposed reconstruction profile is uniform more than polychromatic reconstruction profile. - Highlights: • A novel Beam Hardening (BH) correction approach was described. • A new concept named Local Spectrum Distributions (LSDs) was used to BH

  5. Universal spectrum for DNA base CG frequency distribution in Takifugu rubripes (Puffer fish) genome

    CERN Document Server

    Selvam, A M

    2007-01-01

    The frequency distribution of DNA bases A, C, G, T exhibit fractal fluctuations, namely a zigzag pattern of an increase followed by a decrease of all orders of magnitude along the length of the DNA molecule. Selfsimilar fractal fluctuations are ubiquitous to space-time fluctuations of dynamical systems in nature. The power spectra of fractal fluctuations exhibit inverse power law form signifying long-range space-time correlations such that there is two-way communication between local (small-scale) and global (large-scale) perturbations. In this paper it is shown that DNA base CG frequency distribution in Takifugu rubripes (Puffer fish) Genome Release 4 exhibit universal inverse power law form of the statistical normal distribution consistent with a general systems theory model prediction of quantumlike chaos governing fractal space-time distributions. The model predictions are (i) quasicrystalline Penrose tiling pattern for the nested coiled structure thereby achieving maximum packing efficiency for the DNA m...

  6. Cooperative Distributed Sequential Spectrum Sensing

    CERN Document Server

    S, Jithin K; Gopalarathnam, Raghav

    2010-01-01

    We consider cooperative spectrum sensing for cognitive radios. We develop an energy efficient detector with low detection delay using sequential hypothesis testing. Sequential Probability Ratio Test (SPRT) is used at both the local nodes and the fusion center. We also analyse the performance of this algorithm and compare with the simulations. Modelling uncertainties in the distribution parameters are considered. Slow fading with and without perfect channel state information at the cognitive radios is taken into account.

  7. Dynamic Singularity Spectrum Distribution of Sea Clutter

    Science.gov (United States)

    Xiong, Gang; Yu, Wenxian; Zhang, Shuning

    2015-12-01

    The fractal and multifractal theory have provided new approaches for radar signal processing and target-detecting under the background of ocean. However, the related research mainly focuses on fractal dimension or multifractal spectrum (MFS) of sea clutter. In this paper, a new dynamic singularity analysis method of sea clutter using MFS distribution is developed, based on moving detrending analysis (DMA-MFSD). Theoretically, we introduce the time information by using cyclic auto-correlation of sea clutter. For transient correlation series, the instantaneous singularity spectrum based on multifractal detrending moving analysis (MF-DMA) algorithm is calculated, and the dynamic singularity spectrum distribution of sea clutter is acquired. In addition, we analyze the time-varying singularity exponent ranges and maximum position function in DMA-MFSD of sea clutter. For the real sea clutter data, we analyze the dynamic singularity spectrum distribution of real sea clutter in level III sea state, and conclude that the radar sea clutter has the non-stationary and time-varying scale characteristic and represents the time-varying singularity spectrum distribution based on the proposed DMA-MFSD method. The DMA-MFSD will also provide reference for nonlinear dynamics and multifractal signal processing.

  8. Universal spectrum for DNA base C+G frequency distribution in Human chromosomes 1 to 24

    CERN Document Server

    Selvam, A M

    2007-01-01

    Power spectra of human DNA base C+G frequency distribution in all available contiguous sections exhibit the universal inverse power law form of the statistical normal distribution for the 24 chromosomes. Inverse power law form for power spectra of space-time fluctuations is generic to dynamical systems in nature and indicate long-range space-time correlations. A recently developed general systems theory predicts the observed non-local connections as intrinsic to quantumlike chaos governing space-time fluctuations of dynamical systems. The model predicts the following. (1) The quasiperiodic Penrose tiling pattern for the nested coiled structure of the DNA molecule in the chromosome resulting in maximum packing efficiency. (2) The DNA molecule functions as a unified whole fuzzy logic network with ordered two-way signal transmission between the coding and non-coding regions. Recent studies indicate influence of non-coding regions on functions of coding regions in the DNA molecule.

  9. Generalized eigenvalue based spectrum sensing

    KAUST Repository

    Shakir, Muhammad

    2012-01-01

    Spectrum sensing is one of the fundamental components in cognitive radio networks. In this chapter, a generalized spectrum sensing framework which is referred to as Generalized Mean Detector (GMD) has been introduced. In this context, we generalize the detectors based on the eigenvalues of the received signal covariance matrix and transform the eigenvalue based spectrum sensing detectors namely: (i) the Eigenvalue Ratio Detector (ERD) and two newly proposed detectors which are referred to as (ii) the GEometric Mean Detector (GEMD) and (iii) the ARithmetic Mean Detector (ARMD) into an unified framework of generalize spectrum sensing. The foundation of the proposed framework is based on the calculation of exact analytical moments of the random variables of the decision threshold of the respective detectors. The decision threshold has been calculated in a closed form which is based on the approximation of Cumulative Distribution Functions (CDFs) of the respective test statistics. In this context, we exchange the analytical moments of the two random variables of the respective test statistics with the moments of the Gaussian (or Gamma) distribution function. The performance of the eigenvalue based detectors is compared with the several traditional detectors including the energy detector (ED) to validate the importance of the eigenvalue based detectors and the performance of the GEMD and the ARMD particularly in realistic wireless cognitive radio network. Analytical and simulation results show that the newly proposed detectors yields considerable performance advantage in realistic spectrum sensing scenarios. Moreover, the presented results based on proposed approximation approaches are in perfect agreement with the empirical results. © 2012 Springer Science+Business Media Dordrecht.

  10. Analysis of PL spectrum shape of Si-based materials as a tool for determination of Si crystallites' distribution

    Energy Technology Data Exchange (ETDEWEB)

    Khomenkova, L., E-mail: khomen@isp.kiev.ua

    2014-11-15

    This paper represents the analysis of the shape of photoluminescence spectra of Si-based nano-materials vs. energy of excitation light and temperature of measurements as a tool for the estimation of Si nanocrystallites' distribution. The samples fabricated by electrochemical etching (allowed different termination of Si nanocrystallites to be obtained) were used as modeling material. Bright emission at room temperature was observed for oxygen-terminated Si nanocrytallites, whereas hydrogen-terminated samples emit at low temperatures only. For most samples the photoluminescence spectrum was found to be complex, demonstrating competitive emission from Si crystallites and oxide defects. In latter case to separate the contribution of each recombination channel and to obtain information about crystallite distribution, low-temperature measurements of photoluminescence spectra under different excitation light energy were performed.

  11. Spectrum parameter estimation in Brillouin scattering distributed temperature sensor based on cuckoo search algorithm combined with the improved differential evolution algorithm

    Science.gov (United States)

    Zhang, Yanjun; Yu, Chunjuan; Fu, Xinghu; Liu, Wenzhe; Bi, Weihong

    2015-12-01

    In the distributed optical fiber sensing system based on Brillouin scattering, strain and temperature are the main measuring parameters which can be obtained by analyzing the Brillouin center frequency shift. The novel algorithm which combines the cuckoo search algorithm (CS) with the improved differential evolution (IDE) algorithm is proposed for the Brillouin scattering parameter estimation. The CS-IDE algorithm is compared with CS algorithm and analyzed in different situation. The results show that both the CS and CS-IDE algorithm have very good convergence. The analysis reveals that the CS-IDE algorithm can extract the scattering spectrum features with different linear weight ratio, linewidth combination and SNR. Moreover, the BOTDR temperature measuring system based on electron optical frequency shift is set up to verify the effectiveness of the CS-IDE algorithm. Experimental results show that there is a good linear relationship between the Brillouin center frequency shift and temperature changes.

  12. A Secure Distributed Spectrum Sensing Scheme in Cognitive Radio

    Science.gov (United States)

    Nhan, Nguyen-Thanh; Koo, Insoo

    Distributed spectrum sensing provides an improvement for primary user detection but leads a new security threat into CR system. The spectrum sensing data falsification malicious users can decrease the cooperative sensing performance. In this paper, we propose a distributed scheme in which the presence and absence hypotheses distribution of primary signal is estimated based on past sensing received power data by robust statistics, and the data fusion are performed according to estimated parameters by Dempster-Shafer theory of evidence. Our scheme can achive a powerful capability of malicious user elimination due to the abnormality of the distribution of malicious users compared with that of other legitimate users. In addition, the performance of our data fusion scheme is enhanced by supplemented nodes’ reliability weight.

  13. Distributed opportunistic spectrum sharing in cognitive radio networks

    KAUST Repository

    Hawa, Mohammed

    2016-05-19

    In cases where the licensed radio spectrum is underutilized, cognitive radio technology enables cognitive devices to sense and then dynamically access this scarce resource making the most out of it. In this work, we introduce a simple and intuitive, yet powerful and efficient, technique that allows opportunistic channel access in cognitive radio systems in a completely distributed fashion. Our proposed method achieves very high values of spectrum utilization and throughput. It also minimizes interference between cognitive base stations and the primary users licensed to use the spectrum. The algorithm responds quickly and efficiently to variations in the network parameters and also achieves a high degree of fairness between cognitive base stations. © 2016 John Wiley & Sons, Ltd.

  14. Distributed Spectrum Detection Based on Sequential Markov Chain%基于时序马尔可夫链的分布式频谱检测

    Institute of Scientific and Technical Information of China (English)

    罗银辉; 华漫

    2011-01-01

    针对无线传感网络中的合作谱检测问题,提出一种基于时序马尔可夫链的分布式频谱检测算法.假定单节点对频谱的感知是一个马尔可夫过程,本地序列检测采用序列概率比测试进行频谱探测,得到本地序列检测值.各个感知节点将检测结果发送到数据融合中心,根据设定门限确定最终检测结果.通过Matlab仿真验证了该算法的时序检测性能.%Aiming at the cooperation spectrum detection in Wireless Sensor Network(WSN), this paper presents a distributed spectrum detection based on sequential Markov chain. It assumes the detection of the single node is a Markov process, and the result value of local sequence detection is obtained by the Sequential Probability Ratio Test(SPRT). After the measurements result of each node's own is sent to the data fusion center, the final results can be determined in line with the threshold. Matlab simulation validates the sequential detection performance.

  15. Effects of the Energy Error Distribution of Fluorescence Telescopes on the UHECR energy spectrum

    CERN Document Server

    Carvalho, Washington; de Souza, Vitor; 10.1016/j.astropartphys.2007.04.010

    2008-01-01

    The measurement of the ultra high energy cosmic ray (UHECR) spectrum is strongly affected by uncertainties on the reconstructed energy. The determination of the presence or absence of the GZK cutoff and its position in the energy spectrum depends not only on high statistics but also on the shape of the energy error distribution. Here we determine the energy error distribution for fluorescence telescopes, based on a Monte Carlo simulation. The HiRes and Auger fluorescence telescopes are simulated in detail. We analyze the UHECR spectrum convolved with this energy error distribution. We compare this spectrum with one convolved with a lognormal error distribution as well as with a Gaussian error distribution. We show that the energy error distribution for fluorescence detectors can not be represented by these known distributions. We conclude that the convolved energy spectrum will be smeared but not enough to affect the GZK cutoff detection. This conclusion stands for both HiRes and Auger fluorescence telescopes...

  16. Target tracking based on frequency spectrum amplitude

    Institute of Scientific and Technical Information of China (English)

    Guo Huidong; Zhang Xinhua; Xia Zhijun

    2006-01-01

    The amplitude of frequency spectrum can be integrated with probabilistic data association (PDA) to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The probabilistic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.

  17. Performance analysis of distributed beamforming in a spectrum sharing system

    KAUST Repository

    Yang, Liang

    2012-09-01

    In this paper, we consider a distributed beamforming scheme (DBF) in a spectrum sharing system where multiple secondary users share the spectrum with the licensed primary users under an interference temperature constraint. We assume that DBF is applied at the secondary users. We first consider optimal beamforming and compare it with the user selection scheme in terms of the outage probability and bit-error rate performance. Since perfect feedback is difficult to obtain, we then investigate a limited feedback DBF scheme and develop an outage probability analysis for a random vector quantization (RVQ) design algorithm. Numerical results are provided to illustrate our mathematical formalism and verify our analysis. © 2012 IEEE.

  18. Distributed Cooperative Spectrum Sensing in Mobile Ad Hoc Networks with Cognitive Radios

    CERN Document Server

    Yu, F Richard; Huang, Minyi; Mason, Peter; Li, Zhiqiang

    2011-01-01

    In cognitive radio mobile ad hoc networks (CR-MANETs), secondary users can cooperatively sense the spectrum to detect the presence of primary users. In this chapter, we propose a fully distributed and scalable cooperative spectrum sensing scheme based on recent advances in consensus algorithms. In the proposed scheme, the secondary users can maintain coordination based on only local information exchange without a centralized common receiver. We use the consensus of secondary users to make the final decision. The proposed scheme is essentially based on recent advances in consensus algorithms that have taken inspiration from complex natural phenomena including flocking of birds, schooling of fish, swarming of ants and honeybees. Unlike the existing cooperative spectrum sensing schemes, there is no need for a centralized receiver in the proposed schemes, which make them suitable in distributed CR-MANETs. Simulation results show that the proposed consensus schemes can have significant lower missing detection prob...

  19. Mitigating Entropy Selfishness in Distributed Collaborative Spectrum Sensing

    CERN Document Server

    Li, Shuai; Gao, Zhaoyu; Guan, Xinping

    2011-01-01

    Collaborative spectrum sensing has been recognized as a promising approach to improve the sensing performance via exploiting the spatial diversity of the CR users. Such kind of cooperation, however, might be easily disrupted by the selfish users, especially for the distributed collaborative sensing. In this study, we identify a new kind of selfish behavior in collaborative sensing. Specifically, the selfish user could pretend to be an honest one by claiming a duplicated or slightly modified sensing report from others as a new one. This selfish behavior may significantly reduce the spatial diversity of the sensing reports and thus degrade the performance of collaborative spectrum sensing. We denote such a selfishness issue as Entropy Selfishness. Since it represents a challenge to decide whether a sensing report is a fresh one, entropy selfishness makes the existing incentive schemes designed for conventional wireless networks (e.g., mobile ad hoc networks) unsuitable for Cognitive Radio Networks (CRNs). To th...

  20. Community Based Distribution

    African Journals Online (AJOL)

    Community Based Distribution (CBD) is a relatively new concept. It is a service that reaches ... neration; Resupply systems; Pricing of contraceptives; Mix of services ... tion on how best to design and implement the project and the community in ...

  1. Performance analysis of distributed beamforming in a spectrum sharing system

    KAUST Repository

    Yang, Liang

    2013-05-01

    In this paper, we consider a distributed beamforming scheme (DBF) in a spectrum sharing system where multiple secondary users share the spectrum with some licensed primary users under an interference temperature constraint. We assume that the DBF is applied at the secondary users. We first consider optimal beamforming and compare it with the user selection scheme in terms of the outage probability and bit error rate performance metrics. Since perfect feedback is difficult to obtain, we then investigate a limited feedback DBF scheme and develop an analysis for a random vector quantization design algorithm. Specifically, the approximate statistics functions of the squared inner product between the optimal and quantized vectors are derived. With these statistics, we analyze the outage performance. Furthermore, the effects of channel estimation error and number of primary users on the system performance are investigated. Finally, optimal power adaptation and cochannel interference are considered and analyzed. Numerical and simulation results are provided to illustrate our mathematical formalism and verify our analysis. © 2012 IEEE.

  2. Exact Distributions of Finite Random Matrices and Their Applications to Spectrum Sensing.

    Science.gov (United States)

    Zhang, Wensheng; Wang, Cheng-Xiang; Tao, Xiaofeng; Patcharamaneepakorn, Piya

    2016-07-29

    The exact and simple distributions of finite random matrix theory (FRMT) are critically important for cognitive radio networks (CRNs). In this paper, we unify some existing distributions of the FRMT with the proposed coefficient matrices (vectors) and represent the distributions with the coefficient-based formulations. A coefficient reuse mechanism is studied, i.e., the same coefficient matrices (vectors) can be exploited to formulate different distributions. For instance, the same coefficient matrices can be used by the largest eigenvalue (LE) and the scaled largest eigenvalue (SLE); the same coefficient vectors can be used by the smallest eigenvalue (SE) and the Demmel condition number (DCN). A new and simple cumulative distribution function (CDF) of the DCN is also deduced. In particular, the dimension boundary between the infinite random matrix theory (IRMT) and the FRMT is initially defined. The dimension boundary provides a theoretical way to divide random matrices into infinite random matrices and finite random matrices. The FRMT-based spectrum sensing (SS) schemes are studied for CRNs. The SLE-based scheme can be considered as an asymptotically-optimal SS scheme when the dimension K is larger than two. Moreover, the standard condition number (SCN)-based scheme achieves the same sensing performance as the SLE-based scheme for dual covariance matrix K = 2 . The simulation results verify that the coefficient-based distributions can fit the empirical results very well, and the FRMT-based schemes outperform the IRMT-based schemes and the conventional SS schemes.

  3. Spectrum Sensing in relation to Distributed Antenna System for Coverage Predictions

    DEFF Research Database (Denmark)

    Kumar, Ambuj; Mihovska, Albena D.; Prasad, Ramjee

    2014-01-01

    (BTS)/Nodes at one location known as BTS hotel and the antennas are distributed all over target area by fiber optic network, is discussed. The very concept of splitting Base Station (BS) from its antenna system and putting it at one location (BS Hotel) and distributing antenna as nodes (Remote Unit......Distributed Antenna Systems (DAS) is one of the most promising ways of network deployment now-a-days. Mostly it is used in indoor environment for shopping areas and office locations. Here the Outdoor application of DAS, where multiple service providers can install their Base Transceiver Station...... technology adaptability, efficient energy usage etc. make O-DAS (Outdoor-DAS) network very lucrative. However, for an O-DAS network with large distribution of Remote Units, it is required to have complete knowledge of the spectrum environment at all the locations of remote unit for understanding actual...

  4. Analytical Model Analysis Of Distributed Cooperative Spectrum Sensing Method

    Directory of Open Access Journals (Sweden)

    Ravi Prakash Shukla

    2012-05-01

    Full Text Available Spectrum sensing is a key function of cognitive radio to prevent the harmful interference with licensed users and identify the available spectrum for improving the spectrum’s utilization. Various methods for spectrum sensing control, such as deciding which sensors should perform sensing simultaneously and finding the appropriate trade-off between probability of misdetection and false alarm rate, are described. However, detection performance in practice is often compromised with multipath fading, shadowing and receiver uncertainty issues. To mitigate the impact of these issues, cooperative spectrum sensing has been shown to be an effective method to improve the detection performance by exploiting spatial diversity.

  5. Model-based x-ray energy spectrum estimation algorithm from CT scanning data with spectrum filter

    Science.gov (United States)

    Li, Lei; Wang, Lin-Yuan; Yan, Bin

    2016-10-01

    With the development of technology, the traditional X-ray CT can't meet the modern medical and industry needs for component distinguish and identification. This is due to the inconsistency of X-ray imaging system and reconstruction algorithm. In the current CT systems, X-ray spectrum produced by X-ray source is continuous in energy range determined by tube voltage and energy filter, and the attenuation coefficient of object is varied with the X-ray energy. So the distribution of X-ray energy spectrum plays an important role for beam-hardening correction, dual energy CT image reconstruction or dose calculation. However, due to high ill-condition and ill-posed feature of system equations of transmission measurement data, statistical fluctuations of X ray quantum and noise pollution, it is very hard to get stable and accurate spectrum estimation using existing methods. In this paper, a model-based X-ray energy spectrum estimation method from CT scanning data with energy spectrum filter is proposed. First, transmission measurement data were accurately acquired by CT scan and measurement using phantoms with different energy spectrum filter. Second, a physical meaningful X-ray tube spectrum model was established with weighted gaussian functions and priori information such as continuity of bremsstrahlung and specificity of characteristic emission and estimation information of average attenuation coefficient. The parameter in model was optimized to get the best estimation result for filtered spectrum. Finally, the original energy spectrum was reconstructed from filtered spectrum estimation with filter priori information. Experimental results demonstrate that the stability and accuracy of X ray energy spectrum estimation using the proposed method are improved significantly.

  6. Auditory—Spectrum Quantization Based Speech Recognition

    Institute of Scientific and Technical Information of China (English)

    WuYuanqing; HaoJie; 等

    1997-01-01

    Based on the analysis of the physiological and psychological characteristics of human auditory system[1],we can classify human auditory process into two hearing modes:active one and passive one.A novel approach of robust speech recognition,Auditory-spectrum Quantization Based Speech Recognition(AQBSR),is proposed.In this method,we intend to simulate human active hearing mode and locate the effective areas of speech signals in temporal domain and in frequency domain.Adaptive filter banks are used in place of fixed-band filters to extract feature parameters.The effective speech components and their corresponding frequency areas of each word in the vocabulary can be found out during training.In recognition stage,comparison between the unknown sound and the current template is maintained only in the effective areas of the template word.The control experiments show that the AQ BSR method is more robust than traditional systems.

  7. Dynamic Digital Channelizer Based on Spectrum Sensing.

    Science.gov (United States)

    Hu, Junpeng; Zuo, Zhen; Huang, Zhiping; Dong, Zhi

    2015-01-01

    The ability to efficiently channelize a received signal with dynamic sub-channel bandwidths is a key requirement of software defined radio (SDR) systems. The digital channelizer, which is used to split the received signal into a number of sub-channels, plays an important role in SDR systems. In this paper, a design of dynamic digital channelizer is presented. The proposed method is novel in that it employs a cosine modulated filter bank (CMFB) to divide the received signal into multiple frequency sub-bands and a spectrum sensing technique, which is mostly used in cognitive radio, is introduced to detect the presence of signal of each sub-band. The method of spectrum sensing is carried out based on the eigenvalues of covariance matrix of received signal. The ratio of maximum-minimum eigenvalue of each sub-band is vulnerable to noise fluctuation. This paper suggests an optimized method to calculate the ratio of maximum-minimum eigenvalue. The simulation results imply that the design of digital channelizer can effectively separate the received signal with dynamically changeable sub-channel signals.

  8. Retrieve of Red Tide Distributions from MODIS Data Based on the Characteristics of Water Spectrum%基于水体光谱特性的赤潮分布信息MODIS遥感提取

    Institute of Scientific and Technical Information of China (English)

    丘仲锋; 崔廷伟; 何宜军

    2011-01-01

    赤潮监测对于赤潮治理、预防,减少赤潮危害有着重要作用.通过分析东海赤潮多发区域实测遥感反射率曲线,比较赤潮水体与非赤潮水体的光谱特性差异,发展了一种针对MODIS传感器的赤潮水体分布信息遥感提取方法.应用实测资料对提取方法进行验证,发现在119组实测数据中,只有一组不能正确识别.将算法应用于MODIS卫星资料,对2005年4月4日东海部分海区进行赤潮水体信息提取,得到三个区域总面积约2000 km2的赤潮水体分布信息,赤潮水体提取结果与遥感提取的叶绿素a浓度有很好的对应关系,与实际观测记录对照大体吻合良好.研究表明本文的算法可有效地排除悬浮泥沙水体等干扰影响,确定可能发生赤潮的海区位置及提取海区大范围赤潮水体分布的信息.%After comparing the spectral differences between red tide water and normal water, we developed a method to retrieve red tide distributions from MODIS data based on the characteristics of red tide water spectrum. The authors used the 119 series of in situ observations to validate the method and found that only one observation has not been detected correctly. The authors then applied this method to MODIS data on April 4, 2005. In the research areas three locations of red tide water were apparently detected with the total areas about 2 000 km2. The retrieved red tide distributions are in good agreement with the distributions of high chlorophyll a concentrations. The research suggests that the method is available to eliminating the influence of suspended sediments and can be used to retrieve the locations and areas of red tide water.

  9. Eigenvalue based Spectrum Sensing Algorithms for Cognitive Radio

    CERN Document Server

    Zeng, Yonghong

    2008-01-01

    Spectrum sensing is a fundamental component is a cognitive radio. In this paper, we propose new sensing methods based on the eigenvalues of the covariance matrix of signals received at the secondary users. In particular, two sensing algorithms are suggested, one is based on the ratio of the maximum eigenvalue to minimum eigenvalue; the other is based on the ratio of the average eigenvalue to minimum eigenvalue. Using some latest random matrix theories (RMT), we quantify the distributions of these ratios and derive the probabilities of false alarm and probabilities of detection for the proposed algorithms. We also find the thresholds of the methods for a given probability of false alarm. The proposed methods overcome the noise uncertainty problem, and can even perform better than the ideal energy detection when the signals to be detected are highly correlated. The methods can be used for various signal detection applications without requiring the knowledge of signal, channel and noise power. Simulations based ...

  10. Contract-Based Cooperative Spectrum Sharing

    CERN Document Server

    Duan, Lingjie; Huang, Jianwei

    2011-01-01

    Providing proper economic incentives is essential for the success of dynamic spectrum sharing. Cooperative spectrum sharing is one effective way to achieve this goal. In cooperative spectrum sharing, secondary users (SUs) relay traffics for primary users (PUs), in exchange for dedicated transmission time for the SUs' own communication needs. In this paper, we study the cooperative spectrum sharing under incomplete information, where SUs' types (capturing their heterogeneity in relay channel gains and evaluations of power consumptions) are private information and not known by PUs. Inspired by the contract theory, we model the network as a labor market. The single PU is the employer who offers a contract to the SUs. The contract consists of a set of contract items representing combinations of spectrum accessing time (i.e., reward) and relaying power (i.e., contribution). The SUs are employees, and each of them selects the best contract item to maximize his payoff. We study the optimal contract design for both w...

  11. Spectrum Allocation Based on Game Theory in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Qiufen Ni

    2013-03-01

    Full Text Available As a kind of intelligent communication technology, the characteristic of dynamic spectrum allocation of cognitive radio provides feasible scheme for sharing with the spectrum resources among the primary user and secondary users, which solves the current spectrum resource scarcity problem. In this paper, we comprehensively explored the cognitive radio spectrum allocation models based on game theory from cooperative game and non-cooperative game, which provide detailed overview and analysis on the state of the art of spectrum allocation based on game theory. In order to provide flexible and efficient spectrum allocation in wireless networks, this paper also provides the general framework model based on game theory for cognitive radio spectrum allocation.

  12. Analysis of the Vibration Spectrum Based on the Input Voltage Spectrum

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Jakobsen, Uffe; Rasmussen, Peter Omand;

    2009-01-01

    on the spectrum of the applied voltage. The measurements show that the spectral components are caused mainly by the modulation, which agrees with the results from the analytical solution. A method to determine the dominant frequency components from the radial force spectrum based on current measurements is also...

  13. Spectrum

    DEFF Research Database (Denmark)

    Høgfeldt Hansen, Leif

    2016-01-01

    The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum.......The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum....

  14. Spectrum of L-fuzzy Prime Ideals of a Distributive Lattice

    Institute of Scientific and Technical Information of China (English)

    Y.S.Pawar; S.S.Khopade

    2013-01-01

    A topological space denoted by Fspec(D),called L-fuzzy prime spectrum of a bounded distributive lattice D is introduced.This space Fspec(D) is compact and it contains a subspace homeomorphic with the prime spectrum of D which is dense in it.The correspondence associating D to the topological space Fspec(D) is shown to define a contravarient functor from the category of bounded distributive lattices into the category of compact topological spaces.

  15. Satellite-based RAR performance simulation for measuring directional ocean wave spectrum based on SAR inversion spectrum

    Institute of Scientific and Technical Information of China (English)

    REN Lin; MAO Zhihua; HUANG Haiqing; GONG Fang

    2010-01-01

    Some missions have been carried out to measure wave directional spectrum by synthetic aperture radar (SAR) and airborne real aperture radar (RAR) at a low incidence. Both them have their own advantages and limitations. Scientists hope that SAR and satellite-based RAR can complement each other for the research on wave properties in the future. For this study, the authors aim to simulate the satellite-based RAR system to validate performance for measuring the directional wave spectrum. The principal measurements are introduced and the simulation methods based on the one developed by Hauser are adopted and slightly modified. To enhance the authenticity of input spectrum and the wave spectrum measuring consistency for SAR and satellite-based RAR, the wave height spectrum inversed from Envisat ASAR data by cross spectrum technology is used as the input spectrum of the simulation system. In the process of simulation, the sea surface, backscattering signal, modulation spectrum and the estimated wave height spectrum are simulated in each look direction. Directional wave spectrum are measured based on the simulated observations from 0° to 360~. From the estimated wave spectrum, it has an 180° ambiguity like SAR, but it has no special high wave number cut off in all the direction. Finally, the estimated spectrum is compared with the input one in terms of the dominant wave wavelength, direction and SWH and the results are promising. The simulation shows that satellite-based RAR should be capable of measuring the directional wave properties. Moreover, it indicates satellite-based RAR basically can measure waves that SAR can measure.

  16. HEART-RATE-VARIABILITY SPECTRA BASED ON NONEQUIDISTANT SAMPLING - THE SPECTRUM OF COUNTS AND THE INSTANTANEOUS HEART-RATE SPECTRUM

    NARCIS (Netherlands)

    VANSTEENIS, HG; TULEN, JHM; MULDER, LJM

    1994-01-01

    This paper compares two methods to estimate heart rate variability spectra i.e., the spectrum of counts and the instantaneous heart rate spectrum. Contrary to Fourier techniques based on equidistant sampling of the interbeat intervals, the spectrum of counts of the instantaneous heart rate spectrum

  17. HEART-RATE-VARIABILITY SPECTRA BASED ON NONEQUIDISTANT SAMPLING - THE SPECTRUM OF COUNTS AND THE INSTANTANEOUS HEART-RATE SPECTRUM

    NARCIS (Netherlands)

    VANSTEENIS, HG; TULEN, JHM; MULDER, LJM

    This paper compares two methods to estimate heart rate variability spectra i.e., the spectrum of counts and the instantaneous heart rate spectrum. Contrary to Fourier techniques based on equidistant sampling of the interbeat intervals, the spectrum of counts of the instantaneous heart rate spectrum

  18. Distributed joint power and access control algorithm for secondary spectrum sharing

    Science.gov (United States)

    Li, Hongyan; Chen, Enqing; Fu, Hongliang

    2010-08-01

    Based on interference temperature model, the problem of efficient secondary spectrum sharing is formulated as a power optimization problem with some constraints at physical layer. These constraints and optimization objective limit a feasible power vector set which leads to the need of access control besides power control. In this paper, we consider the decentralized cognitive radio network scenario where short-term data service is required, and the problem of distributed joint power and access control is studied to maximize the total secondary system throughput, subject to Quality of Service (QoS) constraints from individual secondary users and interference temperature limit (ITL) from primary system. Firstly, a pricing-based game model was used to solve distributed power allocation optimization problem in both high and low signal to interference noise ratio (SINR) scenarios. Secondly, when not all the secondary links can be supported with their QoS requirement and ITL, a distributed joint power and access control algorithm was introduced to find the allowable links which results in maximum network throughput with all the constraints satisfied, and the convergence performance is tested by simulations.

  19. Cloud based spectrum manager for future wireless regulatory environment

    CSIR Research Space (South Africa)

    Masonta, MT

    2015-12-01

    Full Text Available and economic manifestation and, thus, a versatile tool would be desirable to deal with technical, economic and socio-economic objectives in various bands. While approaches based on geolocation spectrum databases and radio environment map architecture have...

  20. Herpersvirus strigis: host spectrum and distribution in infected owls.

    Science.gov (United States)

    Burtscher, H; Sibalin, M

    1975-04-01

    Herpesvirus strigis, a new species of the genus Herpesvirus, is a pathogen for several species of owls in the order Srigiformes. Natural infection has been observed in the Eagle Owl (Bubo bubo L.), Long-eared Owl (Asio otus L.) and Snowy Owl (nyctea scandiaca L.) In addition the Little Owl (Athene noctua Scopolic) and Tengmalms Owl (Aegolius funereus L.) was experimentally infected. On the other hand the Tawny Owl (Strix aluco L.) and Barn Owl (Tyto albo Scopoli) proved resistant to a massive experimental infection. Of representatives from nine other orders of birds and mammals, only the Old World Kestrel (Falco tinnunculus L.) was found susceptible to this virus. Distribution of viral antigen in various organs of infected owls, as determined by immunofluorescence and by quantitative virus assay, was in accordance with the occurrence of macroscopic and microscopic lesions.

  1. Let Cognitive Radios Imitate: Imitation-based Spectrum Access for Cognitive Radio Networks

    CERN Document Server

    Iellamo, Stefano; Coupechoux, Marceau

    2011-01-01

    In this paper, we tackle the problem of opportunistic spectrum access in large-scale cognitive radio networks, where the unlicensed Secondary Users (SU) access the frequency channels partially occupied by the licensed Primary Users (PU). Each channel is characterized by an availability probability unknown to the SUs. We apply evolutionary game theory to model the spectrum access problem and develop distributed spectrum access policies based on imitation, a behavior rule widely applied in human societies consisting of imitating successful behavior. We first develop two imitation-based spectrum access policies based on the basic Proportional Imitation (PI) rule and the more advanced Double Imitation (DI) rule given that a SU can imitate any other SUs. We then adapt the proposed policies to a more practical scenario where a SU can only imitate the other SUs operating on the same channel. A systematic theoretical analysis is presented for both scenarios on the induced imitation dynamics and the convergence proper...

  2. Noncolocated Time-Reversal MUSIC: High-SNR Distribution of Null Spectrum

    Science.gov (United States)

    Ciuonzo, Domenico; Rossi, Pierluigi Salvo

    2017-04-01

    We derive the asymptotic distribution of the null spectrum of the well-known Multiple Signal Classification (MUSIC) in its computational Time-Reversal (TR) form. The result pertains to a single-frequency non-colocated multistatic scenario and several TR-MUSIC variants are here investigated. The analysis builds upon the 1st-order perturbation of the singular value decomposition and allows a simple characterization of null-spectrum moments (up to the 2nd order). This enables a comparison in terms of spectrums stability. Finally, a numerical analysis is provided to confirm the theoretical findings.

  3. Amplitude spectrum compensation and phase spectrum correction of seismic data based on the generalized S transform

    Institute of Scientific and Technical Information of China (English)

    Zhou Huai-Lai; Wang Jun; Wang Ming-Chun; Shen Ming-Cheng; Zhang Xin-Kun; Liang Ping

    2014-01-01

    We propose a method for the compensation and phase correction of the ampli-tude spectrum based on the generalized S transform. The compensation of the amplitude spectrum within a reliable frequency range of the seismic record is performed in the S do-main to restore the amplitude spectrum of reflection. We use spectral simulation methods to fit the time-dependent amplitude spectrum and compensate for the amplitude attenuation owing to absorption. We use phase scanning to select the time-, space-, and frequency-dependent phases correction based on the parsimony criterion and eliminate the residual phase effect of the wavelet in the S domain. The method does not directly calculate the Q value;thus, it can be applied to the case of variable Q. The comparison of the theory model and field data verify that the proposed method can recover the amplitude spectrum of the strata reflectivity, while eliminating the effect of the residual phase of the wavelet. Thus, the wavelet approaches the zero-phase wavelet and, the seismic resolution is improved.

  4. Broad spectrum microarray for fingerprint-based bacterial species identification

    Directory of Open Access Journals (Sweden)

    Frey Jürg E

    2010-02-01

    Full Text Available Abstract Background Microarrays are powerful tools for DNA-based molecular diagnostics and identification of pathogens. Most target a limited range of organisms and are based on only one or a very few genes for specific identification. Such microarrays are limited to organisms for which specific probes are available, and often have difficulty discriminating closely related taxa. We have developed an alternative broad-spectrum microarray that employs hybridisation fingerprints generated by high-density anonymous markers distributed over the entire genome for identification based on comparison to a reference database. Results A high-density microarray carrying 95,000 unique 13-mer probes was designed. Optimized methods were developed to deliver reproducible hybridisation patterns that enabled confident discrimination of bacteria at the species, subspecies, and strain levels. High correlation coefficients were achieved between replicates. A sub-selection of 12,071 probes, determined by ANOVA and class prediction analysis, enabled the discrimination of all samples in our panel. Mismatch probe hybridisation was observed but was found to have no effect on the discriminatory capacity of our system. Conclusions These results indicate the potential of our genome chip for reliable identification of a wide range of bacterial taxa at the subspecies level without laborious prior sequencing and probe design. With its high resolution capacity, our proof-of-principle chip demonstrates great potential as a tool for molecular diagnostics of broad taxonomic groups.

  5. Spectrum based feature extraction using spectrum intensity ratio for SSVEP detection.

    Science.gov (United States)

    Itai, Akitoshi; Funase, Arao

    2012-01-01

    Recent years, a Steady-State Visual Evoked Potential (SSVEP) is used as a basis for Brain Computer Interface (BCI)[1]. Various feature extraction and classification techniques are proposed to achieve BCI based on SSVEP. The feature extraction of SSVEP is developed in the frequency domain regardless of the limitation in flickering frequency of visual stimulus caused by hardware architecture. We introduce here the feature extraction using a spectrum intensity ratio. Results show that the detection ratio reaches 84% by using a spectrum intensity ratio with unsupervised classification. It also indicates the SSVEP is enhanced by proposed feature extraction with second harmonic.

  6. Image edge detection based on multi-fractal spectrum analysis

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-yuan; WANG Yao-nan

    2006-01-01

    In this paper,an image edge detection method based on multi-fractal spectrum analysis is presented.The coarse grain H(o)lder exponent of the image pixels is first computed,then,its multi-fractal spectrum is estimated by the kernel estimation method.Finally,the image edge detection is done by means of different multi-fractal spectrum values.Simulation results show that this method is efficient and has better locality compared with the traditional edge detection methods such as the Sobel method.

  7. Universal spectrum for atmospheric aerosol size distribution: comparison with pcasp-b observations of vocals 2008

    CERN Document Server

    Selvam, A M

    2011-01-01

    Atmospheric flows exhibit self-similar fractal space-time fluctuations on all space-time scales in association with inverse power law distribution for power spectra of meteorological parameters such as wind, temperature, etc., and thus implies long-range correlations, identified as self-organized criticality generic to dynamical systems in nature. A general systems theory developed by the author visualizes the fractal fluctuations to result from the coexistence of eddy fluctuations in an eddy continuum, the larger scale eddies being the integrated mean of enclosed smaller scale eddies. The model predicts that the probability distributions of component eddy amplitudes and the corresponding variances (power spectra) are quantified by the same universal inverse power law distribution incorporating the golden mean. Atmospheric particulates are held in suspension by the vertical velocity distribution spectrum. The atmospheric particulate size spectrum is derived in terms of the model predicted universal inverse po...

  8. On the spectrum of a distribution function and on unique factorization

    Directory of Open Access Journals (Sweden)

    T. Pham-Gia

    1982-01-01

    Full Text Available The spectrum of a distribution function is related to the quasi-analyticity of a class of functions {CM(j}, where M(j is a multisequence of positive numbers. For a regular multisequence, a result on the uniqueness of characteristic function decomposition is given.

  9. A Novel Algorithm for Cooperative Distributed Sequential Spectrum Sensing in Cognitive Radio

    CERN Document Server

    S, Jithin K

    2010-01-01

    This paper considers cooperative spectrum sensing in Cognitive Radios. In our previous work we have developed DualSPRT, a distributed algorithm for cooperative spectrum sensing using Sequential Probability Ratio Test (SPRT) at the Cognitive Radios as well as at the fusion center. This algorithm works well, but is not optimal. In this paper we propose an improved algorithm- SPRT-CSPRT, which is motivated from Cumulative Sum Procedures (CUSUM). We analyse it theoretically. We also modify this algorithm to handle uncertainties in SNR's and fading.

  10. Routing and spectrum allocation in multi-ring based data center networks

    Science.gov (United States)

    Zhang, Zitian; Hu, Weisheng; Ye, Tong; Sun, Weiqiang; Zhao, Li; Zhang, Kuo

    2016-02-01

    Recently, we proposed a multi-ring based optical circuit switching (OCS) network following the principle of a Clos network. The network can provide connectivity to a large number of racks which may be distributed across a relatively large geographical space in a data center. However, property of the ring based switch in the central stage of the multi-ring based OCS network introduces a unique routing and spectrum allocation (RSA) problem which is more complex than the routing problem in a classical Clos switching network. In this paper, we extend our work to investigate the RSA problem. For a given set of inter-rack traffic requests, we consider two spectrum allocation schemes, namely fixed spectrum allocation and flexible spectrum allocation. For the fixed case, we show that the RSA problem degenerates into the traditional routing problem of the Clos network. As for the flexible case, property of spectrum division multiplexing technology and bandwidth limitation of the ring based switches should be taken into consideration during allocation of the central module, such that the system throughput can be maximized. This paper presents an integer linear program (ILP) formulation as well as a heuristic algorithm we developed to solve the flexible RSA problem. We evaluate the performance of both the two spectrum allocation schemes under different traffic patterns. Our results demonstrate that, to handle uneven inter-rack traffic pattern in general data center networks, flexible spectrum allocation can lead to an increase of about 120% in system throughput, although its computational complexity is slightly higher than that of the fixed spectrum allocation scheme.

  11. Distributed Spectrum Sharing for Video Streaming in Cognitive Radio Ad Hoc Networks

    Science.gov (United States)

    Ding, Lei; Pudlewski, Scott; Melodia, Tommaso; Batalama, Stella; Matyjas, John D.; Medley, Michael J.

    A distributed joint routing and spectrum sharing algorithm for video streaming applications over cognitive radio ad hoc networks is proposed in this article. The proposed cross-layer control scheme dynamically allocates routes, spectrum and power to maximize the network throughput under the constraints posed by delay-sensitive video applications. The algorithm evaluates the expected delay of competing flows in single-hop and two-hop networks considering the time-varying spectrum condition and occupancy, traffic characteristics, and the condition of queues at intermediate nodes. Simulation results show that the proposed algorithm significantly reduces the packet loss rate and improves the average peak signal-to-noise ratio (PSNR) of the received video streams.

  12. Spectrum Handoffs Based on Preemptive Repeat Priority Queue in Cognitive Radio Networks.

    Science.gov (United States)

    Yang, Xiaolong; Tan, Xuezhi; Ye, Liang; Ma, Lin

    2016-07-20

    Cognitive radio can significantly improve the spectrum efficiency, and spectrum handoff is considered as an important functionality to guarantee the quality of service (QoS) of primary users (PUs) and the continuity of data transmission of secondary users (SUs). In this paper, we propose an analytical framework based on a preemptive repeat identical (PRI) M/G/1 queuing network model to characterize spectrum handoff behaviors with general service time distribution of both primary and secondary connections, multiple interruptions and transmission delay resulting from the appearance of primary connections. Then, we derive the close-expression of the extended data delivery and the system sojourn time in both staying and changing scenarios. In addition, based on analysis of spectrum handoff behaviors resulting from multiple interruptions caused by the appearance of the primary connections, we investigate the traffic-adaptive policy, by which the considered SU will optimally adjust its handoff spectrum policy. Moreover, we investigate the admissible region and provide the reference for designing the admission control rule for the arriving secondary connection requests. Finally, simulation results verify that our proposed analytical framework is reasonable and can provide the reference for executing the optimal spectrum handoff strategy and designing the admission control rule for the SU in cognitive radio networks.

  13. Spectrum-based kernel length estimation for Gaussian process classification.

    Science.gov (United States)

    Wang, Liang; Li, Chuan

    2014-06-01

    Recent studies have shown that Gaussian process (GP) classification, a discriminative supervised learning approach, has achieved competitive performance in real applications compared with most state-of-the-art supervised learning methods. However, the problem of automatic model selection in GP classification, involving the kernel function form and the corresponding parameter values (which are unknown in advance), remains a challenge. To make GP classification a more practical tool, this paper presents a novel spectrum analysis-based approach for model selection by refining the GP kernel function to match the given input data. Specifically, we target the problem of GP kernel length scale estimation. Spectrums are first calculated analytically from the kernel function itself using the autocorrelation theorem as well as being estimated numerically from the training data themselves. Then, the kernel length scale is automatically estimated by equating the two spectrum values, i.e., the kernel function spectrum equals to the estimated training data spectrum. Compared with the classical Bayesian method for kernel length scale estimation via maximizing the marginal likelihood (which is time consuming and could suffer from multiple local optima), extensive experimental results on various data sets show that our proposed method is both efficient and accurate.

  14. A neutron spectrum unfolding code based on iterative procedures

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J. M.; Vega C, H. R., E-mail: morvymm@yahoo.com.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2012-10-15

    In this work, the version 3.0 of the neutron spectrum unfolding code called Neutron Spectrometry and Dosimetry from Universidad Autonoma de Zacatecas (NSDUAZ), is presented. This code was designed in a graphical interface under the LabVIEW programming environment and it is based on the iterative SPUNIT iterative algorithm, using as entrance data, only the rate counts obtained with 7 Bonner spheres based on a {sup 6}Lil(Eu) neutron detector. The main features of the code are: it is intuitive and friendly to the user; it has a programming routine which automatically selects the initial guess spectrum by using a set of neutron spectra compiled by the International Atomic Energy Agency. Besides the neutron spectrum, this code calculates the total flux, the mean energy, H(10), h(10), 15 dosimetric quantities for radiation protection porpoises and 7 survey meter responses, in four energy grids, based on the International Atomic Energy Agency compilation. This code generates a full report in html format with all relevant information. In this work, the neutron spectrum of a {sup 241}AmBe neutron source on air, located at 150 cm from detector, is unfolded. (Author)

  15. Distributed Channel Selection in CRAHNs with Heterogeneous Spectrum Opportunities: A Local Congestion Game Approach

    Science.gov (United States)

    Xu, Yuhua; Wu, Qihui; Wang, Jinlong; Min, Neng; Anpalagan, Alagan

    This letter investigates the problem of distributed channel selection in cognitive radio ad hoc networks (CRAHNs) with heterogeneous spectrum opportunities. Firstly, we formulate this problem as a local congestion game, which is proved to be an exact potential game. Then, we propose a spatial best response dynamic (SBRD) to rapidly achieve Nash equilibrium via local information exchange. Moreover, the potential function of the game reflects the network collision level and can be used to achieve higher throughput.

  16. Calculated power distribution of a thermionic, beryllium oxide reflected, fast-spectrum reactor

    Science.gov (United States)

    Mayo, W.; Lantz, E.

    1973-01-01

    A procedure is developed and used to calculate the detailed power distribution in the fuel elements next to a beryllium oxide reflector of a fast-spectrum, thermionic reactor. The results of the calculations show that, although the average power density in these outer fuel elements is not far from the core average, the power density at the very edge of the fuel closest to the beryllium oxide is about 1.8 times the core avearge.

  17. 基于太阳光谱的FTIR技术监测石油化工区丙烯的浓度分布%Application of Fourier Transform Infrared Spectroscopy Based on Sun Spectrum to Monitor the Distribution of Propylene from Petrochemical Industry

    Institute of Scientific and Technical Information of China (English)

    冯书香; 徐亮; 高闽光; 程巳阳; 金岭; 冯明春; 李相贤

    2012-01-01

    In the paper, a new method is introduced for real-time monitoring the column concentration of propylene from petrochemical industry, which is based on the technique of Fourier Transform Infrared Spectroscopy (FTIR) by using sun spectrum. The retrieval algorithm of the concentrations of polluted gases based on nonlinear least squares is proposed. Continuous measurements surrounding the pre-monitoring contaminated areas are performed with a closed loop by using self-developed vehicular FTIR system to obtain the regional background reference spectrum, measured spectrum ,while application of a simplified gas radiative transmission model to calculate atmospheric transmittance spectrum, and finally using the nonlinear least squares fitting algorithm for atmospheric transmittance spectrum to achieve the column concentration of propylene surrounding polluted areas. Using this method, remote sensing experiment of propylene in Shanghai Gaoqiao petrochemical zone was done. The experimental result shows that the measured column concentration distribution of propylene well reflects the pollutantD emission and dispersion and proves the availability of the vehicular FTIR technology in monitoring regional gas pollution.%介绍了一种基于太阳光谱的傅里叶变换红外光谱( FTIR)技术实时监测石油化工区丙烯浓度分布情况的新方法和非线性最小二乘法反演污染气体浓度的算法.利用自主研发的车载FTIR系统对预监测污染源区域做闭合环路测量获取背景参考谱、测量谱,同时应用气体辐射传输的简化模型计算得到大气透过率谱,最终应用非线性最小二乘拟合算法对大气透过率谱反演得出污染源区域周边污染气体分布的柱浓度信息.运用此方法实际遥测了上海高桥石油化工区丙烯排放的情况,实验结果显示,测量的丙烯柱浓度分布准确地反应了污染物的排放和扩散情况,证明了车载FTIR技术在区域性污染气体监测方面的实用性.

  18. Sheldon spectrum and the plankton paradox: two sides of the same coin-a trait-based plankton size-spectrum model.

    Science.gov (United States)

    Cuesta, José A; Delius, Gustav W; Law, Richard

    2017-05-25

    The Sheldon spectrum describes a remarkable regularity in aquatic ecosystems: the biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. While size-spectrum models have explained this phenomenon for assemblages of multicellular organisms, this paper introduces a species-resolved size-spectrum model to explain the phenomenon in unicellular plankton. A Sheldon spectrum spanning the cell-size range of unicellular plankton necessarily consists of a large number of coexisting species covering a wide range of characteristic sizes. The coexistence of many phytoplankton species feeding on a small number of resources is known as the Paradox of the Plankton. Our model resolves the paradox by showing that coexistence is facilitated by the allometric scaling of four physiological rates. Two of the allometries have empirical support, the remaining two emerge from predator-prey interactions exactly when the abundances follow a Sheldon spectrum. Our plankton model is a scale-invariant trait-based size-spectrum model: it describes the abundance of phyto- and zooplankton cells as a function of both size and species trait (the maximal size before cell division). It incorporates growth due to resource consumption and predation on smaller cells, death due to predation, and a flexible cell division process. We give analytic solutions at steady state for both the within-species size distributions and the relative abundances across species.

  19. Spectrum sharing in cognitive radio networks--an auction-based approach.

    Science.gov (United States)

    Wang, Xinbing; Li, Zheng; Xu, Pengchao; Xu, Youyun; Gao, Xinbo; Chen, Hsiao-Hwa

    2010-06-01

    Cognitive radio is emerging as a promising technique to improve the utilization of the radio frequency spectrum. In this paper, we consider the problem of spectrum sharing among primary (or "licensed") users (PUs) and secondary (or "unlicensed") users (SUs). We formulate the problem based on bandwidth auction, in which each SU makes a bid for the amount of spectrum and each PU may assign the spectrum among the SUs by itself according to the information from the SUs without degrading its own performance. We show that the auction is a noncooperative game and that Nash equilibrium (NE) can be its solution. We first consider a single-PU network to investigate the existence and uniqueness of the NE and further discuss the fairness among the SUs under given conditions. Then, we present a dynamic updating algorithm in which each SU achieves NE in a distributed manner. The stability condition of the dynamic behavior for this spectrum-sharing scheme is studied. The discussion is generalized to the case in which there are multiple PUs in the network, where the properties of the NE are shown under appropriate conditions. Simulations were used to evaluate the system performance and verify the effectiveness of the proposed algorithm.

  20. Angular distribution of high-energy $e^+e^-$ photoproduction close to the end of spectrum

    CERN Document Server

    Di Piazza, A

    2012-01-01

    We consider the differential cross section of electron-positron pair production by a high-energy photon in a strong Coulomb field close to the end of the electron or positron spectrum. When the momentum transfer largely exceeds the electron mass, the cross section is obtained analytically in a compact form. Coulomb corrections essentially modify the cross section even for moderate values of the nuclear charge number $Z$. In the same kinematical region, the angular distribution for bound-free pair production, bremsstrahlung, and photorecombination is also obtained.

  1. CMB lensing beyond the power spectrum: Cosmological constraints from the one-point probability distribution function and peak counts

    Science.gov (United States)

    Liu, Jia; Hill, J. Colin; Sherwin, Blake D.; Petri, Andrea; Böhm, Vanessa; Haiman, Zoltán

    2016-11-01

    Unprecedentedly precise cosmic microwave background (CMB) data are expected from ongoing and near-future CMB stage III and IV surveys, which will yield reconstructed CMB lensing maps with effective resolution approaching several arcminutes. The small-scale CMB lensing fluctuations receive non-negligible contributions from nonlinear structure in the late-time density field. These fluctuations are not fully characterized by traditional two-point statistics, such as the power spectrum. Here, we use N -body ray-tracing simulations of CMB lensing maps to examine two higher-order statistics: the lensing convergence one-point probability distribution function (PDF) and peak counts. We show that these statistics contain significant information not captured by the two-point function and provide specific forecasts for the ongoing stage III Advanced Atacama Cosmology Telescope (AdvACT) experiment. Considering only the temperature-based reconstruction estimator, we forecast 9 σ (PDF) and 6 σ (peaks) detections of these statistics with AdvACT. Our simulation pipeline fully accounts for the non-Gaussianity of the lensing reconstruction noise, which is significant and cannot be neglected. Combining the power spectrum, PDF, and peak counts for AdvACT will tighten cosmological constraints in the Ωm-σ8 plane by ≈30 %, compared to using the power spectrum alone.

  2. Energy spectrum analysis of blast waves based on an improved Hilbert-Huang transform

    Science.gov (United States)

    Li, L.; Wang, F.; Shang, F.; Jia, Y.; Zhao, C.; Kong, D.

    2016-07-01

    Using the improved Hilbert-Huang transform (HHT), this paper investigates the problems of analysis and interpretation of the energy spectrum of a blast wave. It has been previously established that the energy spectrum is an effective feature by which to characterize a blast wave. In fact, the higher the energy spectra in a frequency band of a blast wave, the greater the damage to a target in the same frequency band. However, most current research focuses on analyzing wave signals in the time domain or frequency domain rather than considering the energy spectrum. We propose here an improved HHT method combined with a wavelet packet to extract the energy spectrum feature of a blast wave. When applying the HHT, the signal is first roughly decomposed into a series of intrinsic mode functions (IMFs) by empirical mode decomposition. The wavelet packet method is then performed on each IMF to eliminate noise on the energy spectrum. Second, a coefficient is introduced to remove unrelated IMFs. The energy of each instantaneous frequency can be derived through the Hilbert transform. The energy spectrum can then be obtained by adding up all the components after the wavelet packet filters and screens them through a coefficient to obtain the effective IMFs. The effectiveness of the proposed method is demonstrated by 12 groups of experimental data, and an energy attenuation model is established based on the experimental data. The improved HHT is a precise method for blast wave signal analysis. For other shock wave signals from blasting experiments, an energy frequency time distribution and energy spectrum can also be obtained through this method, allowing for more practical applications.

  3. High-energy spectrum and zenith-angle distribution of atmospheric neutrinos

    CERN Document Server

    Sinegovsky, S I; Sinegovskaya, T S

    2011-01-01

    High-energy neutrinos, arising from decays of mesons produced through the collisions of cosmic ray particles with air nuclei, form the background in the astrophysical neutrino detection problem. An ambiguity in high-energy behavior of pion and especially kaon production cross sections for nucleon-nucleus collisions may affect essentially the calculated neutrino flux. We present results of the calculation of the energy spectrum and zenith-angle distribution of the muon and electron atmospheric neutrinos in the energy range 10 GeV to 10 PeV. The calculation was performed with usage of known hadronic models (QGSJET-II-03, SIBYLL 2.1, Kimel & Mokhov) for two of the primary spectrum parametrizations, by Gaisser & Honda and by Zatsepin & Sokolskaya. The comparison of the calculated muon neutrino spectrum with the IceCube40 experiment data make it clear that even at energies above 100 TeV the prompt neutrino contribution is not so apparent because of tangled uncertainties of the strange (kaons) and charm...

  4. On the Impact of User Distribution on Cooperative Spectrum Sensing and Data Transmission with Multiuser Diversity

    KAUST Repository

    Rao, Anlei

    2011-07-01

    In this thesis, we investigate the independent but not identically distributed (i.n.i.d.) situations for spectrum sensing and data transmission. In particular, we derive the false-alarm probability and the detection probability of cooperative spectrum sensing with the scheme of energy fusion over i.n.i.d. Nakagami fading channels. Then, the performance of adaptive modulation with single-cell multiuser scheduling over i.n.i.d. Nakagami fading channels is analyzed. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M- ary quadrature amplitude modulation (M-QAM) schemes. In addition, we study the impact of time delay on the average BER of adaptive M-QAM. From the selected numerical results, we can see that cooperative spectrum sensing and multiuser diversity brings considerably better performance even over i.n.i.d. fading environments.

  5. Collaborative spectrum sensing based on the ratio between largest eigenvalue and Geometric mean of eigenvalues

    KAUST Repository

    Shakir, Muhammad

    2011-12-01

    In this paper, we introduce a new detector referred to as Geometric mean detector (GEMD) which is based on the ratio of the largest eigenvalue to the Geometric mean of the eigenvalues for collaborative spectrum sensing. The decision threshold has been derived by employing Gaussian approximation approach. In this approach, the two random variables, i.e. The largest eigenvalue and the Geometric mean of the eigenvalues are considered as independent Gaussian random variables such that their cumulative distribution functions (CDFs) are approximated by a univariate Gaussian distribution function for any number of cooperating secondary users and received samples. The approximation approach is based on the calculation of exact analytical moments of the largest eigenvalue and the Geometric mean of the eigenvalues of the received covariance matrix. The decision threshold has been calculated by exploiting the CDF of the ratio of two Gaussian distributed random variables. In this context, we exchange the analytical moments of the two random variables with the moments of the Gaussian distribution function. The performance of the detector is compared with the performance of the energy detector and eigenvalue ratio detector. Analytical and simulation results show that our newly proposed detector yields considerable performance advantage in realistic spectrum sensing scenarios. Moreover, our results based on proposed approximation approach are in perfect agreement with the empirical results. © 2011 IEEE.

  6. Variable Voltage Source Inverter with controlled frequency spectrum based on Random Pulse Width Modulation

    Directory of Open Access Journals (Sweden)

    Muhammad Farrukh Yaqub

    2012-01-01

    Full Text Available This paper presents a new method for single phase variable voltage inverter based on Random Pulse Width Modulation. In Random Pulse Width Modulation based inverter, the frequency spectrum of the output current and voltage waveforms becomes continuous because of the randomization of the switching function of the devices controlling the output voltages. This paper establishes a theory that if the distributions of the random numbers generated by the random source are kept within certain limit with respect to the peak value of reference sinusoidal waveform, the frequency spectrum can be controlled. On the basis of the results, a novel drive using variable tap changing transformer (optional and adaptive random number generator, to control the ratio between the numbers generated by the random source and the reference waveform has been suggested that will guarantee a better power quality profile for a broad range of output voltages.

  7. Spectrum shaping of accelerator-based neutron beams for BNCT

    CERN Document Server

    Montagnini, B; Esposito, J; Giusti, V; Mattioda, F; Varone, R

    2002-01-01

    We describe Monte Carlo simulations of three facilities for the production of epithermal neutrons for Boron Neutron Capture Therapy (BNCT) and examine general aspects and problems of designing the spectrum-shaping assemblies to be used with these neutron sources. The first facility is based on an accelerator-driven low-power subcritical reactor, operating as a neutron amplifier. The other two facilities have no amplifier and rely entirely on their primary sources, a D-T fusion reaction device and a conventional 2.5 MeV proton accelerator with a Li target, respectively.

  8. [Galaxy spectrum subtraction of a mixed spectrum based on two class PCA eigen-spectra].

    Science.gov (United States)

    Tu, Liang-Ping; Wu, Fu-Chao; Luo, A-Li; Zhao, Yong-Heng

    2010-06-01

    The authors present a new method called two class PCA for decomposing the mixed spectra, namely, for subtracting the host galaxy contamination from each SN spectrum. The authors improved the quality of reconstructed galaxy spectrum and computational efficiency, and these improvements were realized because we used both the PCA eigen spectra of galaxy templates library and SN templates library to model the mixed spectrum. The method includes mainly three steps described as follows. The first step is calculating two class PCA eigen spectra of galaxy templates and SN templates respectively. The second step is determining all reconstructed coefficients by the SVD matrix decomposition or orthogonal transformation. And the third step is computing a reconstructed galaxy spectrum and subtracting it from each mixed spectrum. Experiments show that this method can obtain an accurate decomposition of a mixed synthetic spectrum, and is a method with low time-consumption to get the reliable SN spectrum without galaxy contamination and can be used for spectral analysis of large amount of spectra. The time consumption using our method is much lower than that using chi2-template fitting for a spectrum.

  9. Cooperative Sequential Spectrum Sensing Based on Level-triggered Sampling

    CERN Document Server

    Yilmaz, Yasin; Wang, Xiaodong

    2011-01-01

    We propose a new framework for cooperative spectrum sensing in cognitive radio networks, that is based on a novel class of non-uniform samplers, called the event-triggered samplers, and sequential detection. In the proposed scheme, each secondary user computes its local sensing decision statistic based on its own channel output; and whenever such decision statistic crosses certain predefined threshold values, the secondary user will send one (or several) bit of information to the fusion center. The fusion center asynchronously receives the bits from different secondary users and updates the global sensing decision statistic to perform a sequential probability ratio test (SPRT), to reach a sensing decision. We provide an asymptotic analysis for the above scheme, and under different conditions, we compare it against the cooperative sensing scheme that is based on traditional uniform sampling and sequential detection. Simulation results show that the proposed scheme, using even 1 bit, can outperform its uniform ...

  10. Queue stability distributed spectrum access algorithm based on Markov model for cognitive radio network%基于Markov模型的分布式队列稳定频谱接入算法

    Institute of Scientific and Technical Information of China (English)

    李晓辉; 张金钊; 黑永强

    2014-01-01

    The queue stability of the secondary users in cognitive network was considered. A Markov chain model for the state of users in the cognitive network was constructed and a distributed CSMA algorithm was proposed. The secondary users adjust the parameters of back-off time due to the arrival and service rate to ensure the queue stability. Upper bound of the capacity of secondary users under the collision constrainting to primary user was derived in closed form. If the ar-rival rate of secondary users is smaller than the upper bound of capacity, queue stability can be ensured by the proposed algorithm. Simulations verified the effectiveness of the algorithm.%针对认知无线电系统中次级用户队列稳定性问题,通过建立发送状态马尔科夫(Markov)模型,提出了一种基于CSMA的自适应分布式频谱接入算法。次级用户根据感知结果自适应地调整退避时长参数,使稳态服务速率逐渐趋近到达速率,最终达到队列稳定。此外,还在满足对主用户碰撞限制的条件下,推导了次级用户的吞吐量上界,并证明当次级用户的数据到达速率小于此上界时,能够通过所提算法保证队列稳定。仿真结果证明了算法的有效性。

  11. Energy-Based Cooperative Spectrum Sensing of SC-FDMA Systems

    Directory of Open Access Journals (Sweden)

    Fucheng Yang

    2014-07-01

    Full Text Available In this paper, we propose a frequency-hopping M-ary frequency-shift keying spectrum sensing network (FH/MFSK SSN for identifying the on/off states of the users supported by a single-carrier frequency-division multiple assess (SC-FDMA primary radio (PR system. Specifically, the spectrums of an uplink interleaved frequency-division multiple access (IFDMA PR system are monitored by a number of cognitive radio sensing nodes (CRSNs. These CRSNs distributedly detect the on/off states of users based on one of the three energy detection schemes. After the local spectrum sensing, the CRSNs transmit their detected states to a fusion centre (FC with the aid of FH/MFSK techniques. At the FC, the on/off states of the users supported the IFDMA PR system are finally classified according to either the conventional equal-gain combining (EGC scheme or the novel erasure-supported EGC (ES-EGC scheme. In this way, the on/off information about the spectrums occupied by an IFDMA PR systemcan be obtained, so that they can be exploited by a cognitive radio (CR system. For local spectrum sensing, in this paper, we consider four synchronisation scenarios concerning the synchronisation between the received IFDMA signals and the CRSNs. The performance of the FH/MFSK SSN associated with various schemes is investigated by simulations. Our studies show that the FH/MFSK SSN constitutes one of the highly reliable spectrum sensing schemes, which are capable of exploiting both the space diversity provided by local CRSNs and the frequency diversity provided by the subcarriers of IFDMA system.

  12. A Stokes drift approximation based on the Phillips spectrum

    CERN Document Server

    Breivik, Øyvind; Janssen, Peter A E M

    2016-01-01

    A new approximation to the Stokes drift velocity pro?le based on the exact solution for the Phillips spectrum is explored. The pro?file is compared with the monochromatic pro?file and the recently proposed exponential integral profi?le. ERA-Interim spectra and spectra from a wave buoy in the central North Sea are used to investigate the behaviour of the profi?le. It is found that the new profi?le has a much stronger gradient near the surface and lower normalized deviation from the pro?le computed from the spectra. Based on estimates from two open-ocean locations, an average value has been estimated for a key parameter of the profi?le. Given this parameter, the profi?le can be computed from the same two parameters as the monochromatic profi?le, namely the transport and the surface Stokes drift velocity.

  13. Energy Efficient Cooperative Spectrum Sensing in Cognitive Radio Networks Using Distributed Dynamic Load Balanced Clustering Scheme

    Directory of Open Access Journals (Sweden)

    Muthukkumar R.

    2016-07-01

    Full Text Available Cognitive Radio (CR is a promising and potential technique to enable secondary users (SUs or unlicenced users to exploit the unused spectrum resources effectively possessed by primary users (PUs or licenced users. The proven clustering approach is used to organize nodes in the network into the logical groups to attain energy efficiency, network scalability, and stability for improving the sensing accuracy in CR through cooperative spectrum sensing (CSS. In this paper, a distributed dynamic load balanced clustering (DDLBC algorithm is proposed. In this algorithm, each member in the cluster is to calculate the cooperative gain, residual energy, distance, and sensing cost from the neighboring clusters to perform the optimal decision. Each member in a cluster participates in selecting a cluster head (CH through cooperative gain, and residual energy that minimises network energy consumption and enhances the channel sensing. First, we form the number of clusters using the Markov decision process (MDP model to reduce the energy consumption in a network. In this algorithm, CR users effectively utilize the PUs reporting time slots of unavailability. The simulation results reveal that the clusters convergence, energy efficiency, and accuracy of channel sensing increased considerably by using the proposed algorithm.

  14. Life distribution of thermal fatigue crack propagation under random temperature fluctuation with wide-band spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, Michiko; Tanaka, Hiroaki [Kyoto Univ. (Japan)

    1995-05-01

    Thermal fatigue crack propagation under random temperature fluctuation is theoretically investigated from a probabilistic view point by the use of a Markov approximation method, under the condition that the temporary variation of the inner surface temperature of plate is modeled as a wide-band stationary Gaussian process. First, a crack growth equation is formulated on the basis of the Paris law under the assumption that the stress intensity factor range {Delta}K can be approximated by the local expectation of a relative maximum of the stress intensity factor K. Next it is extended to a random differential equation, where the randomness in crack propagation resistance is taken into account. The Markov approximation method is then applied to derive a residual life distribution function as well as a probability distribution function of the crack length. Finally, numerical examples are shown to examine the quantitative behavior of the residual life distribution, whose results indicate that the present model is applicable even if the spectrum of temperature is of narrow-band type. (author).

  15. Hadron spectrum in quenched lattice QCD and distribution of zero modes

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, Yoichi (Tsukuba Univ., Sakura, Ibaraki (Japan). Inst. of Physics)

    1989-06-01

    I report the results of the calculation of the hadron spectrum with the standard one-plaquette gauge action on a 16{sup 3}x48 lattice at beta=5.85 in the quenched lattice QCD. The result remarkably agrees with that of quark potential models for the case where the quark mass is equal to or is larger than the strange quark mass, even when one uses the standard one-plaquette gauge action. This is contrary to what is stated in the literature. We clarify the reason of the discrepancy, paying close attention to systematic errors in numerical calculations. Further, I show the distribution of zero modes of quark matrix, both in the cases of a RG improved gauge action and the standard action, and discuss the difference between the two cases. (orig.).

  16. Low-Power Direct-Sequence Spread-Spectrum Modem Architecture for Distributed Wireless Sensor Networks

    Energy Technology Data Exchange (ETDEWEB)

    Chien, C; Elgorriaga, I; McConaghy, C

    2001-07-03

    Emerging CMOS and MEMS technologies enable the implementation of a large number of wireless distributed microsensors that can be easily and rapidly deployed to form highly redundant, self-configuring, and ad hoc sensor networks. To facilitate ease of deployment, these sensors should operate on battery for extended periods of time. A particular challenge in maintaining extended battery lifetime lies in achieving communications with low power. This paper presents a direct-sequence spread-spectrum modem architecture that provides robust communications for wireless sensor networks while dissipating very low power. The modem architecture has been verified in an FPGA implementation that dissipates only 33 mW for both transmission and reception. The implementation can be easily mapped to an ASIC technology, with an estimated power performance of less than 1 mW.

  17. Evaluation of the beta energy spectrum from a distributed uranium mill tailings source.

    Science.gov (United States)

    Reif, R H; Martz, D E; Carlson, D S; Turner, J B

    1993-10-01

    The beta energy spectra from uranium mill tailings, 90Sr with different absorber thicknesses, and a uranium metal slab were measured and compared to select an appropriate beta source for calibrating a personal dosimeter to measure shallow dose equivalent when exposed to uranium mill tailings. The measured beta energy spectrum from the 90Sr source, with a 111 mg cm-2 cover thickness, was selected as a possible calibration source for a personnel dosimeter. The dose equivalent rate to the skin at 1 cm from a distributed tailings source of infinite thickness, with a 226Ra activity of 56 Bq g-1 (1.5 x 10(3) pCi g-1), was measured to be 0.024 mSv h-1 (2.4 mrem h-1).

  18. Performance Optimization based Spectrum Analysis on OFRA and EDFA Devices

    Directory of Open Access Journals (Sweden)

    Liu Liying

    2013-07-01

    Full Text Available As the key devices, erbium doped fiber amplifier (EDFA and optical Raman fiber amplifier (OFRA have been widely applied in the fields of optical communication, sensing and measurement. However, the performance optimization is always one of the hot topics in the study of optical fiber amplifiers, because its output characteristics are hardly dependent to the key designing parameters. In this paper, in order to cope with such problem, we adopt the novel analysis based spectrum to study the output performance of EDFA and OFRA systems, respectively. Through simulating the operation of the two amplifying system, their output characteristics are first demonstrated with the various parameters. And according to the numerical results obtained, the key designing parameters of EDFA and OFRA systems are determinate, and the performance of amplifying systems are improved and optimized obviously in terms of output power, signal noise ratio, and the level of gain flatness.   Keywords: Fiber Raman Amplifier, Erbium Doped Fiber Amplifier, Performance optimization, Spectrum analysis, Simulation.  

  19. Spread spectrum image watermarking based on perceptual quality metric.

    Science.gov (United States)

    Zhang, Fan; Liu, Wenyu; Lin, Weisi; Ngan, King Ngi

    2011-11-01

    Efficient image watermarking calls for full exploitation of the perceptual distortion constraint. Second-order statistics of visual stimuli are regarded as critical features for perception. This paper proposes a second-order statistics (SOS)-based image quality metric, which considers the texture masking effect and the contrast sensitivity in Karhunen-Loève transform domain. Compared with the state-of-the-art metrics, the quality prediction by SOS better correlates with several subjectively rated image databases, in which the images are impaired by the typical coding and watermarking artifacts. With the explicit metric definition, spread spectrum watermarking is posed as an optimization problem: we search for a watermark to minimize the distortion of the watermarked image and to maximize the correlation between the watermark pattern and the spread spectrum carrier. The simple metric guarantees the optimal watermark a closed-form solution and a fast implementation. The experiments show that the proposed watermarking scheme can take full advantage of the distortion constraint and improve the robustness in return.

  20. Price-Based Resource Allocation for Spectrum-Sharing Femtocell Networks: A Stackelberg Game Approach

    CERN Document Server

    Kang, Xin; Motani, Mehul

    2011-01-01

    This paper investigates the price-based resource allocation strategies for the uplink transmission of a spectrum-sharing femtocell network, in which a central macrocell is underlaid with distributed femtocells, all operating over the same frequency band as the macrocell. Assuming that the macrocell base station (MBS) protects itself by pricing the interference from the femtocell users, a Stackelberg game is formulated to study the joint utility maximization of the macrocell and the femtocells subject to a maximum tolerable interference power constraint at the MBS. Especially, two practical femtocell channel models: sparsely deployed scenario for rural areas and densely deployed scenario for urban areas, are investigated. For each scenario, two pricing schemes: uniform pricing and non-uniform pricing, are proposed. Then, the Stackelberg equilibriums for these proposed games are studied, and an effective distributed interference price bargaining algorithm with guaranteed convergence is proposed for the uniform-...

  1. Distribution of extended-spectrum β-lactamase types in a Brazilian tertiary hospital

    Directory of Open Access Journals (Sweden)

    Keite da Silva Nogueira

    2015-04-01

    Full Text Available INTRODUCTION: Epidemiological data on the prevalence of extended-spectrum β-lactamases (ESBLs are scarce in Brazil despite the fact that these data are essential for empirical treatment and control measures. The objective of this study was to evaluate the prevalence of different ESBLs by type and distribution in a tertiary hospital in southern Brazil. METHODS: We evaluated 1,827 enterobacterial isolates between August 2003 and March 2008 isolated from patients at a tertiary hospital. Samples were identified using a Vitek automated system and were confirmed by biochemical testing. The identified ESBL strains were characterized by phenotypic methods, polymerase chain reaction (PCR, and sequencing. Genetic similarities were evaluated by pulsed-field gel electrophoresis. RESULTS: It was 390 (21.3% ESBL-producing strains, which expressed the ESBLs CTX-M (292, SHV (84, CTX and SHV (10, TEM (2, and PER (2. CONCLUSIONS: The prevalence of ESBL-expressing strains was high, especially in Klebsiella pneumoniae and Enterobacter spp. CTX-M was the predominant type of ESBL observed, and its genetic variability indicates a polyclonal distribution.

  2. Auction based spectrum management of cognitive radio networks

    DEFF Research Database (Denmark)

    Chang, H. B.; Chen, K.-C.; Prasad, Ramjee

    2009-01-01

    (PS-MSs), and we therefore construct a cognitive radio network (CRN) consisting of a PRN with multiple CR-MSs. We propose a spectrum management policy framework such that CR-MSs can compete in utilization of the PRN spectrum bands available to opportunistic transmission of CR-MSs by Vickrey auction......Cognitive radio (CR) technology is considered as an effective solution to enhance overall spectrum efficiency, especially primary radio network (PRN) typically having relatively low spectrum utilization. However, to realize CR concept, it is essential to provide enough incentives to PRN and extra...... to the PRN, the overall spectrum utilization, the profit of the service provider, the spectrum access opportunity of the CR-MSs are increased to achieve cowin situation for every party in cognitive radio networks....

  3. Orbital angular momentum complex spectrum analyzer for vortex light based on rotational Doppler Effect

    CERN Document Server

    Zhou, Hailong; Dong, Jianji; Zhang, Pei; Chen, Dongxu; Cai, Xinlun; Li, Fuli; Zhang, Xinliang

    2016-01-01

    The function to measure orbital angular momentum (OAM) distribution of vortex light is essential for OAM applications. Although there are lots of works to measure OAM modes, it is difficult to measure the power distribution of different OAM modes quantitatively and instantaneously, let alone measure the phase distribution among them. In this work, we demonstrate an OAM complex spectrum analyzer, which enables to measure the power and phase distribution of OAM modes simultaneously by employing rotational Doppler Effect. The original OAM mode distribution is mapped to electrical spectrum of beating signals with a photodetector. The power distribution and phase distribution of superimposed OAM beams are successfully retrieved by analyzing the electrical spectrum. We also extend the measurement to other spatial modes, such as linear polarization modes. These results represent a new landmark of spatial mode analysis and show great potentials in optical communication and OAM quantum state tomography.

  4. Fast dictionary-based reconstruction for diffusion spectrum imaging.

    Science.gov (United States)

    Bilgic, Berkin; Chatnuntawech, Itthi; Setsompop, Kawin; Cauley, Stephen F; Yendiki, Anastasia; Wald, Lawrence L; Adalsteinsson, Elfar

    2013-11-01

    Diffusion spectrum imaging reveals detailed local diffusion properties at the expense of substantially long imaging times. It is possible to accelerate acquisition by undersampling in q-space, followed by image reconstruction that exploits prior knowledge on the diffusion probability density functions (pdfs). Previously proposed methods impose this prior in the form of sparsity under wavelet and total variation transforms, or under adaptive dictionaries that are trained on example datasets to maximize the sparsity of the representation. These compressed sensing (CS) methods require full-brain processing times on the order of hours using MATLAB running on a workstation. This work presents two dictionary-based reconstruction techniques that use analytical solutions, and are two orders of magnitude faster than the previously proposed dictionary-based CS approach. The first method generates a dictionary from the training data using principal component analysis (PCA), and performs the reconstruction in the PCA space. The second proposed method applies reconstruction using pseudoinverse with Tikhonov regularization with respect to a dictionary. This dictionary can either be obtained using the K-SVD algorithm, or it can simply be the training dataset of pdfs without any training. All of the proposed methods achieve reconstruction times on the order of seconds per imaging slice, and have reconstruction quality comparable to that of dictionary-based CS algorithm.

  5. Small Amplitude Dynamics of Nonhomogeneous Magnetization Distributions: The Excitation Spectrum of Stripe Domains

    Science.gov (United States)

    Ebels, Ursula; Buda, Liliana D.; Ounadjela, Kamel; Wigen, Phillip E.

    The general purpose of this review is to introduce to the dynamics of small amplitude excitations of nonhomogeneous magnetization distributions. This is in contrast to the dynamics of the magnetization reversal process, which corresponds to large amplitude perturbations, discussed in other contributions of this book. Small amplitude oscillations can be studied by ferromagnetic resonance or Brillouin light scattering. The latter technique isused to investigate the excitation spectrum in laterally constrained structures.This review introduces ferromagnetic resonance and focuses on the role of the pumping field orientation. Upon varying the pumping field orientation, fundamental modes can be selectively excited, giving, in particular, access to regions of varying magnetic orientation. This is demonstrated for the excitation spectrum of magnetic domains and domain walls of the stripe domain structure in metallic thin films. These stripe domains can be considered laterally constrained magnetic units 40-100 nm wide, separated by domain walls.Such experiments provide information on the domain and domain wall structure and in principle yield the internal fields and the coupling fields of the domains, as well as the wall mass and the stabilizing forces of the domain walls. The wall mass itself is a dynamic parameter which intervenes upon wall acceleration but is of less importance when considering steady-state wall propagation in the magnetization reversal process. However, the wall mass depends sensitively on the spin configuration inside the wall, and therefore resonance experiments can provide insight into the structure of the domain wall. The wall structure, on the other hand, plays an important role in spin-polarized transport experiments, investigating the contribution of a domain wall to the resistance [1] or the transfer of momentum from the conduction electrons to the wall [2,3].

  6. Query processing in distributed, taxonomy-based information sources

    CERN Document Server

    Meghini, Carlo; Coltella, Veronica; Analyti, Anastasia

    2011-01-01

    We address the problem of answering queries over a distributed information system, storing objects indexed by terms organized in a taxonomy. The taxonomy consists of subsumption relationships between negation-free DNF formulas on terms and negation-free conjunctions of terms. In the first part of the paper, we consider the centralized case, deriving a hypergraph-based algorithm that is efficient in data complexity. In the second part of the paper, we consider the distributed case, presenting alternative ways implementing the centralized algorithm. These ways descend from two basic criteria: direct vs. query re-writing evaluation, and centralized vs. distributed data or taxonomy allocation. Combinations of these criteria allow to cover a wide spectrum of architectures, ranging from client-server to peer-to-peer. We evaluate the performance of the various architectures by simulation on a network with O(10^4) nodes, and derive final results. An extensive review of the relevant literature is finally included.

  7. New detector for spread-spectrum based image watermarking using underdetermined ICA

    Science.gov (United States)

    Malik, Hafiz; Khokhar, Ashfaq; Ansari, Rashid

    2006-02-01

    This paper presents a novel scheme for detection of watermarks embedded in multimedia signals using spread spectrum (SS) techniques. The detection method is centered on using the model that the embedded watermark and the host signal are mutually independent. The proposed detector assumes that the host signal and the watermark obey non-Gaussian distributions. The proposed blind watermark detector employs underdetermined blind source separation (BSS) based on independent component analysis (ICA) for watermark estimation from the watermarked image. The mean-field theory based undetermined BSS scheme is used for watermark estimation. Analytical results are presented showing that the proposed detector performs significantly better than the existing correlation based blind detectors traditionally used for SS-based image watermarking.

  8. Matched Filter Based Spectrum Sensing on Cognitive Radio for OFDM WLANs

    Directory of Open Access Journals (Sweden)

    R.Saravanan

    2013-02-01

    Full Text Available For the unlicensed users to use the licensed spectrum, unused frequency bands called white spaces need to be detected. Cognitive radio does this task by dynamic spectrum access. This requires intelligent spectrum sensing techniques. In this paper such unused spectrum for OFDM WLAN (IEEE 802.11a is predicted by exploring the signals presence in minimum time using matched filter based detection incorporating optimal threshold selection, thereby increasing the sensing accuracy andinterference reduction of secondary network.

  9. [Continuum based fast Fourier transform processing of infrared spectrum].

    Science.gov (United States)

    Liu, Qing-Jie; Lin, Qi-Zhong; Wang, Qin-Jun; Li, Hui; Li, Shuai

    2009-12-01

    To recognize ground objects with infrared spectrum, high frequency noise removing is one of the most important phases in spectrum feature analysis and extraction. A new method for infrared spectrum preprocessing was given combining spectrum continuum processing and Fast Fourier Transform (CFFT). Continuum was firstly removed from the noise polluted infrared spectrum to standardize hyper-spectra. Then the spectrum was transformed into frequency domain (FD) with fast Fourier transform (FFT), separating noise information from target information After noise eliminating from useful information with a low-pass filter, the filtered FD spectrum was transformed into time domain (TD) with fast Fourier inverse transform. Finally the continuum was recovered to the spectrum, and the filtered infrared spectrum was achieved. Experiment was performed for chlorite spectrum in USGS polluted with two kinds of simulated white noise to validate the filtering ability of CFFT by contrast with cubic function of five point (CFFP) in time domain and traditional FFT in frequency domain. A circle of CFFP has limited filtering effect, so it should work much with more circles and consume more time to achieve better filtering result. As for conventional FFT, Gibbs phenomenon has great effect on preprocessing result at edge bands because of special character of rock or mineral spectra, while works well at middle bands. Mean squared error of CFFT is 0. 000 012 336 with cut-off frequency of 150, while that of FFT and CFFP is 0. 000 061 074 with cut-off frequency of 150 and 0.000 022 963 with 150 working circles respectively. Besides the filtering result of CFFT can be improved by adjusting the filter cut-off frequency, and has little effect on working time. The CFFT method overcomes the Gibbs problem of FFT in spectrum filtering, and can be more convenient, dependable, and effective than traditional TD filter methods.

  10. Sample-Based Vegetation Distribution Information Synthesis.

    Directory of Open Access Journals (Sweden)

    Chanchan Xu

    Full Text Available In constructing and visualizing a virtual three-dimensional forest scene, we must first obtain the vegetation distribution, namely, the location of each plant in the forest. Because the forest contains a large number of plants, the distribution of each plant is difficult to obtain from actual measurement methods. Random approaches are used as common solutions to simulate a forest distribution but fail to reflect the specific biological arrangements among types of plants. Observations show that plants in the forest tend to generate particular distribution patterns due to growth competition and specific habitats. This pattern, which represents a local feature in the distribution and occurs repeatedly in the forest, is in line with the "locality" and "static" characteristics in the "texture data", making it possible to use a sample-based texture synthesis strategy to build the distribution. We propose a vegetation distribution data generation method that uses sample-based vector pattern synthesis. A sample forest stand is obtained first and recorded as a two-dimensional vector-element distribution pattern. Next, the large-scale vegetation distribution pattern is synthesized automatically using the proposed vector pattern synthesis algorithm. The synthesized distribution pattern resembles the sample pattern in the distribution features. The vector pattern synthesis algorithm proposed in this paper adopts a neighborhood comparison technique based on histogram matching, which makes it efficient and easy to implement. Experiments show that the distribution pattern synthesized with this method can sufficiently preserve the features of the sample distribution pattern, making our method meaningful for constructing realistic forest scenes.

  11. Spectrum Sensing for Cognitive Radio Based on Multiple Antennas

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; De Carvalho, Elisabeth; Prasad, Ramjee

    2012-01-01

    Spectrum sensing is a key component for enabling the cognitive radio paradigm. In this paper, we propose a novel totally-blind spectrum sensing technique for cognitive radio device equipped with multiple antennas, namely the Space Frequency Cross Product Sensing (SFCPS) algorithm. Existing...

  12. An indirect transmission measurement-based spectrum estimation method for computed tomography

    CERN Document Server

    Zhao, Wei; Schafer, Sebastian; Royalty, Kevin

    2015-01-01

    The characteristics of an x-ray spectrum can greatly influence imaging and related tasks. In practice, due to the pile-up effect of the detector, it's difficult to directly measure the spectrum of a CT scanner using an energy resolved detector. An alternative solution is to estimate the spectrum using transmission measurements with a step phantom or other CT phantom. In this work, we present a new spectrum estimation method based on indirect transmission measurement and model spectra mixture approach. The estimated x-ray spectrum was expressed as weighted summation of a set of model spectra, which can significantly reduce the degrees of freedom (DOF) of the spectrum estimation problem. Next, an estimated projection can be calculated with the assumed spectrum. By iteratively updating the unknown weights, we minimized the difference between the estimated projection data and the raw projection data. The final spectrum was calculated with these calibrated weights and the model spectra. Both simulation and experim...

  13. Hierarchical Spread Spectrum Fingerprinting Scheme Based on the CDMA Technique

    Directory of Open Access Journals (Sweden)

    Kuribayashi Minoru

    2011-01-01

    Full Text Available Abstract Digital fingerprinting is a method to insert user's own ID into digital contents in order to identify illegal users who distribute unauthorized copies. One of the serious problems in a fingerprinting system is the collusion attack such that several users combine their copies of the same content to modify/delete the embedded fingerprints. In this paper, we propose a collusion-resistant fingerprinting scheme based on the CDMA technique. Our fingerprint sequences are orthogonal sequences of DCT basic vectors modulated by PN sequence. In order to increase the number of users, a hierarchical structure is produced by assigning a pair of the fingerprint sequences to a user. Under the assumption that the frequency components of detected sequences modulated by PN sequence follow Gaussian distribution, the design of thresholds and the weighting of parameters are studied to improve the performance. The robustness against collusion attack and the computational costs required for the detection are estimated in our simulation.

  14. Photoisomerization action spectrum of retinal protonated Schiff base in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Coughlan, N. J. A.; Catani, K. J.; Adamson, B. D.; Wille, U.; Bieske, E. J., E-mail: evanjb@unimelb.edu.au [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia)

    2014-04-28

    The photophysical behaviour of the isolated retinal protonated n-butylamine Schiff base (RPSB) is investigated in the gas phase using a combination of ion mobility spectrometry and laser spectroscopy. The RPSB cations are introduced by electrospray ionisation into an ion mobility mass spectrometer where they are exposed to tunable laser radiation in the region of the S{sub 1} ← S{sub 0} transition (420–680 nm range). Four peaks are observed in the arrival time distribution of the RPSB ions. On the basis of predicted collision cross sections with nitrogen gas, the dominant peak is assigned to the all-trans isomer, whereas the subsidiary peaks are assigned to various single, double and triple cis geometric isomers. RPSB ions that absorb laser radiation undergo photoisomerization, leading to a detectable change in their drift speed. By monitoring the photoisomer signal as a function of laser wavelength an action spectrum, extending from 480 to 660 nm with a clear peak at 615 ± 5 nm, is obtained. The photoisomerization action spectrum is related to the absorption spectrum of isolated retinal RPSB molecules and should help benchmark future electronic structure calculations.

  15. A Distributed Data Base Version of INGRES.

    Science.gov (United States)

    Stonebraker, Michael; Neuhold, Eric

    Extensions are required to the currently operational INGRES data base system for it to manage a data base distributed over multiple machines in a computer network running the UNIX operating system. Three possible user views include: (1) each relation in a unique machine, (2) a user interaction with the data base which can only span relations at a…

  16. Popular Content Distribution in CR-VANETs with Joint Spectrum Sensing and Channel Access using Coalitional Games

    Directory of Open Access Journals (Sweden)

    Tianyu Wang

    2014-07-01

    Full Text Available Driven by both safety concerns and commercial interests, popular content distribution (PCD, as one of the key services offered by vehicular networks, has recently received considerable attention. In this paper, we address the PCD problem in highway scenarios, in which a popular file is distributed to a group of onboard units (OBUs driving through an area of interest (AoI. Due to high speeds of vehicles and deep fading of vehicle-to-roadside (V2R channels, the OBUs may not finish downloading the entire file. Consequently, a peer-to-peer (p2p network should be constructed among the OBUs for completing the file delivery process. Here, we apply the cognitive radio technique for vehicle-to-vehicle communications and propose a cooperative approach based on coalition formation games, which jointly considers the spectrum sensing and channel access performance. Simulation results show that our approach presents a considerable performance improvement compared with the non-cooperative case.

  17. Efficient blind decoders for additive spread spectrum embedding based data hiding

    Science.gov (United States)

    Valizadeh, Amir; Wang, Z. Jane

    2012-12-01

    This article investigates efficient blind watermark decoding approaches for hidden messages embedded into host images, within the framework of additive spread spectrum (SS) embedding based for data hiding. We study SS embedding in both the discrete cosine transform and the discrete Fourier transform (DFT) domains. The contributions of this article are multiple-fold: first, we show that the conventional SS scheme could not be applied directly into the magnitudes of the DFT, and thus we present a modified SS scheme and the optimal maximum likelihood (ML) decoder based on the Weibull distribution is derived. Secondly, we investigate the improved spread spectrum (ISS) embedding, an improved technique of the traditional additive SS, and propose the modified ISS scheme for information hiding in the magnitudes of the DFT coefficients and the optimal ML decoders for ISS embedding are derived. We also provide thorough theoretical error probability analysis for the aforementioned decoders. Thirdly, sub-optimal decoders, including local optimum decoder (LOD), generalized maximum likelihood (GML) decoder, and linear minimum mean square error (LMMSE) decoder, are investigated to reduce the required prior information at the receiver side, and their theoretical decoding performances are derived. Based on decoding performances and the required prior information for decoding, we discuss the preferred host domain and the preferred decoder for additive SS-based data hiding under different situations. Extensive simulations are conducted to illustrate the decoding performances of the presented decoders.

  18. Empirical wind retrieval model based on SAR spectrum measurements

    Science.gov (United States)

    Panfilova, Maria; Karaev, Vladimir; Balandina, Galina; Kanevsky, Mikhail; Portabella, Marcos; Stoffelen, Ad

    The present paper considers polarimetric SAR wind vector applications. Remote-sensing measurements of the near-surface wind over the ocean are of great importance for the understanding of atmosphere-ocean interaction. In recent years investigations for wind vector retrieval using Synthetic Aperture Radar (SAR) data have been performed. In contrast with scatterometers, a SAR has a finer spatial resolution that makes it a more suitable microwave instrument to explore wind conditions in the marginal ice zones, coastal regions and lakes. The wind speed retrieval procedure from scatterometer data matches the measured radar backscattering signal with the geophysical model function (GMF). The GMF determines the radar cross section dependence on the wind speed and direction with respect to the azimuthal angle of the radar beam. Scatterometers provide information on wind speed and direction simultaneously due to the fact that each wind vector cell (WVC) is observed at several azimuth angles. However, SAR is not designed to be used as a high resolution scatterometer. In this case, each WVC is observed at only one single azimuth angle. That is why for wind vector determination additional information such as wind streak orientation over the sea surface is required. It is shown that the wind vector can be obtained using polarimetric SAR without additional information. The main idea is to analyze the spectrum of a homogeneous SAR image area instead of the backscattering normalized radar cross section. Preliminary numerical simulations revealed that SAR image spectral maxima positions depend on the wind vector. Thus the following method for wind speed retrieval is proposed. In the first stage of the algorithm, the SAR spectrum maxima are determined. This procedure is carried out to estimate the wind speed and direction with ambiguities separated by 180 degrees due to the SAR spectrum symmetry. The second stage of the algorithm allows us to select the correct wind direction

  19. Speech enhancement based on multitaper spectrum and psychoacoustical weighting rule

    Institute of Scientific and Technical Information of China (English)

    WU Hongwei; WU Zhenyang; ZHAO Li

    2007-01-01

    Multitaper spectrum has lower variance than the traditional periodogram. The noise spectrum and the noise to noisy signal spectrum ratio (NNSR) were estimated from the multitaper spectrum of the noisy signal; the pre-enhanced speech for calculating the noise masking threshold was obtained by the spectral amplitude subtraction method, whose gain is a function of NNSR; the final enhanced speech was obtained by suppressing the Fourier spectrum of the noisy speech with the psychoacoustical weighting rule incorporating the noise masking threshold. Because of the low variance feature of the multitaper spectrum, a modified offset formula was proposed to calculate the noise masking threshold, thus the reconstructed speech with this modification has an improvement in MBSD (Modified Bark Spectral Distortion).When a maximum limitation less than one to the psychoacoustical weighting rule is further proposed, the higher the input SNR (> 0 dB) is, the more improvement the segmental SNR and the overall SNR have. The informal listening tests show that there is little speech distortion for the enhanced speech processed by the proposed method, the background noise is reduced much and free of musical noise.

  20. [A Brillouin Scattering Spectrum Feature Extraction Based on Flies Optimization Algorithm with Adaptive Mutation and Generalized Regression Neural Network].

    Science.gov (United States)

    Zhang, Yan-jun; Liu, Wen-zhe; Fu, Xing-hu; Bi, Wei-hong

    2015-10-01

    According to the high precision extracting characteristics of scattering spectrum in Brillouin optical time domain reflection optical fiber sensing system, this paper proposes a new algorithm based on flies optimization algorithm with adaptive mutation and generalized regression neural network. The method takes advantages of the generalized regression neural network which has the ability of the approximation ability, learning speed and generalization of the model. Moreover, by using the strong search ability of flies optimization algorithm with adaptive mutation, it can enhance the learning ability of the neural network. Thus the fitting degree of Brillouin scattering spectrum and the extraction accuracy of frequency shift is improved. Model of actual Brillouin spectrum are constructed by Gaussian white noise on theoretical spectrum, whose center frequency is 11.213 GHz and the linewidths are 40-50, 30-60 and 20-70 MHz, respectively. Comparing the algorithm with the Levenberg-Marquardt fitting method based on finite element analysis, hybrid algorithm particle swarm optimization, Levenberg-Marquardt and the least square method, the maximum frequency shift error of the new algorithm is 0.4 MHz, the fitting degree is 0.991 2 and the root mean square error is 0.024 1. The simulation results show that the proposed algorithm has good fitting degree and minimum absolute error. Therefore, the algorithm can be used on distributed optical fiber sensing system based on Brillouin optical time domain reflection, which can improve the fitting of Brillouin scattering spectrum and the precision of frequency shift extraction effectively.

  1. Information distribution in distributed microprocessor based flight control systems

    Science.gov (United States)

    Montgomery, R. C.; Lee, P. S.

    1977-01-01

    This paper presents an optimal control theory that accounts for variable time intervals in the information distribution to control effectors in a distributed microprocessor based flight control system. The theory is developed using a linear process model for the aircraft dynamics and the information distribution process is modeled as a variable time increment process where, at the time that information is supplied to the control effectors, the control effectors know the time of the next information update only in a stochastic sense. An optimal control problem is formulated and solved that provides the control law that minimizes the expected value of a quadratic cost function. An example is presented where the theory is applied to the control of the longitudinal motions of the F8-DFBW aircraft. Theoretical and simulation results indicate that, for the example problem, the optimal cost obtained using a variable time increment Markov information update process where the control effectors know only the past information update intervals and the Markov transition mechanism is almost identical to that obtained using a known uniform information update interval.

  2. Restriction spectrum imaging improves MRI-based prostate cancer detection

    Science.gov (United States)

    McCammack, Kevin C.; Schenker-Ahmed, Natalie M.; White, Nathan S.; Best, Shaun R.; Marks, Robert M.; Heimbigner, Jared; Kane, Christopher J.; Parsons, J. Kellogg; Kuperman, Joshua M.; Bartsch, Hauke; Desikan, Rahul S.; Rakow-Penner, Rebecca A.; Liss, Michael A.; Margolis, Daniel J. A.; Raman, Steven S.; Shabaik, Ahmed; Dale, Anders M.; Karow, David S.

    2017-01-01

    Purpose To compare the diagnostic performance of restriction spectrum imaging (RSI), with that of conventional multi-parametric (MP) magnetic resonance imaging (MRI) for prostate cancer (PCa) detection in a blinded reader-based format. Methods Three readers independently evaluated 100 patients (67 with proven PCa) who underwent MP-MRI and RSI within 6 months of systematic biopsy (N = 67; 23 with targeting performed) or prostatectomy (N = 33). Imaging was performed at 3 Tesla using a phased-array coil. Readers used a five-point scale estimating the likelihood of PCa present in each prostate sextant. Evaluation was performed in two separate sessions, first using conventional MP-MRI alone then immediately with MP-MRI and RSI in the same session. Four weeks later, another scoring session used RSI and T2-weighted imaging (T2WI) without conventional diffusion-weighted or dynamic contrast-enhanced imaging. Reader interpretations were then compared to prostatectomy data or biopsy results. Receiver operating characteristic curves were performed, with area under the curve (AUC) used to compare across groups. Results MP-MRI with RSI achieved higher AUCs compared to MP-MRI alone for identifying high-grade (Gleason score greater than or equal to 4 + 3=7) PCa (0.78 vs. 0.70 at the sextant level; P MRI for high-grade PCa (0.71 vs. 0.70 at the sextant level). With hemigland analysis, high-grade disease results were similar when comparing RSI + T2WI with MP-MRI, although with greater AUCs compared to the sextant analysis (0.80 vs. 0.79). Conclusion Including RSI with MP-MRI improves PCa detection compared to MP-MRI alone, and RSI with T2WI achieves similar PCa detection as MP-MRI. PMID:26910114

  3. Analytical Dielectric Spectrum Formula Based on Representative Frequencies

    Institute of Scientific and Technical Information of China (English)

    Bo Kong; Ke-xiang Fu; Min-hua Shan; Xiang-yuan Li

    2009-01-01

    According to experimental data available for the complex refractive index of particular di-electrics, a dielectric spectrum formula is proposed by the least square fitting technique combined with selected natural frequencies. From the dielectric spectrum formula, the spec-tra of optical and dielectric constants can be obtained in the whole frequency region. Three dielectrics, water, ethanol, and toluene, are taken as examples. In the region where the ex-perimental data are available, the spectra of the optical constants calculated by the formula are in good agreement with the real refractive spectrum obtained by Kramers-Kronig (K-K) transform and the experimental imaginary refractive spectrum. In the region where no ex-perimental data are available, the extrapolation of our formula can make predictions. The merits of the present treatment are that we are able to get the uniform spectrum formula, without splitting into different frequency sections, and the analytical form of the dielectric spectra will be useful in the theoretical description of solvation dynamics.

  4. Compressed Measurements Based Spectrum Sensing for Wideband Cognitive Radio Systems

    Directory of Open Access Journals (Sweden)

    Taha A. Khalaf

    2015-01-01

    Full Text Available Spectrum sensing is the most important component in the cognitive radio (CR technology. Spectrum sensing has considerable technical challenges, especially in wideband systems where higher sampling rates are required which increases the complexity and the power consumption of the hardware circuits. Compressive sensing (CS is successfully deployed to solve this problem. Although CS solves the higher sampling rate problem, it does not reduce complexity to a large extent. Spectrum sensing via CS technique is performed in three steps: sensing compressed measurements, reconstructing the Nyquist rate signal, and performing spectrum sensing on the reconstructed signal. Compressed detectors perform spectrum sensing from the compressed measurements skipping the reconstruction step which is the most complex step in CS. In this paper, we propose a novel compressed detector using energy detection technique on compressed measurements sensed by the discrete cosine transform (DCT matrix. The proposed algorithm not only reduces the computational complexity but also provides a better performance than the traditional energy detector and the traditional compressed detector in terms of the receiver operating characteristics. We also derive closed form expressions for the false alarm and detection probabilities. Numerical results show that the analytical expressions coincide with the exact probabilities obtained from simulations.

  5. An Agent-Based Distributed Manufacturing System

    Institute of Scientific and Technical Information of China (English)

    J.Li; J.Y.H.Fuh; Y.F.Zhang; A.Y.C.Nee

    2006-01-01

    Agent theories have shown their promising capability in solving distributed complex system ever since its development. In this paper, one multi-agent based distributed product design and manufacturing planning system is presented. The objective of the research is to develop a distributed collaborative design environment for supporting cooperation among the existing engineering functions. In the system, the functional agents for design, manufacturability evaluation,process planning and scheduling are efficiently integrated with a facilitator agent. This paper firstly gives an introduction to the system structure, and the definitions for each executive agent are then described and a prototype of the proposed is also included at the end part.

  6. Compressed wideband spectrum sensing based on discrete cosine transform.

    Science.gov (United States)

    Wang, Yulin; Zhang, Gengxin

    2014-01-01

    Discrete cosine transform (DCT) is a special type of transform which is widely used for compression of speech and image. However, its use for spectrum sensing has not yet received widespread attention. This paper aims to alleviate the sampling requirements of wideband spectrum sensing by utilizing the compressive sampling (CS) principle and exploiting the unique sparsity structure in the DCT domain. Compared with discrete Fourier transform (DFT), wideband communication signal has much sparser representation and easier implementation in DCT domain. Simulation result shows that the proposed DCT-CSS scheme outperforms the conventional DFT-CSS scheme in terms of MSE of reconstruction signal, detection probability, and computational complexity.

  7. Compressed Wideband Spectrum Sensing Based on Discrete Cosine Transform

    Directory of Open Access Journals (Sweden)

    Yulin Wang

    2014-01-01

    Full Text Available Discrete cosine transform (DCT is a special type of transform which is widely used for compression of speech and image. However, its use for spectrum sensing has not yet received widespread attention. This paper aims to alleviate the sampling requirements of wideband spectrum sensing by utilizing the compressive sampling (CS principle and exploiting the unique sparsity structure in the DCT domain. Compared with discrete Fourier transform (DFT, wideband communication signal has much sparser representation and easier implementation in DCT domain. Simulation result shows that the proposed DCT-CSS scheme outperforms the conventional DFT-CSS scheme in terms of MSE of reconstruction signal, detection probability, and computational complexity.

  8. Distributed Prognostics based on Structural Model Decomposition

    Science.gov (United States)

    Daigle, Matthew J.; Bregon, Anibal; Roychoudhury, I.

    2014-01-01

    Within systems health management, prognostics focuses on predicting the remaining useful life of a system. In the model-based prognostics paradigm, physics-based models are constructed that describe the operation of a system and how it fails. Such approaches consist of an estimation phase, in which the health state of the system is first identified, and a prediction phase, in which the health state is projected forward in time to determine the end of life. Centralized solutions to these problems are often computationally expensive, do not scale well as the size of the system grows, and introduce a single point of failure. In this paper, we propose a novel distributed model-based prognostics scheme that formally describes how to decompose both the estimation and prediction problems into independent local subproblems whose solutions may be easily composed into a global solution. The decomposition of the prognostics problem is achieved through structural decomposition of the underlying models. The decomposition algorithm creates from the global system model a set of local submodels suitable for prognostics. Independent local estimation and prediction problems are formed based on these local submodels, resulting in a scalable distributed prognostics approach that allows the local subproblems to be solved in parallel, thus offering increases in computational efficiency. Using a centrifugal pump as a case study, we perform a number of simulation-based experiments to demonstrate the distributed approach, compare the performance with a centralized approach, and establish its scalability. Index Terms-model-based prognostics, distributed prognostics, structural model decomposition ABBREVIATIONS

  9. Spread spectrum communications. Citations from the NTIS data base

    Science.gov (United States)

    Reed, W. E.

    1980-04-01

    The bibliography cites Federally-funded research on the techniques, equipment, and applications of spread spectrum communications. Topics include pseudonoise modulation, coding, signal processing, synchronization, antijamming, interference rejection, antennas, and the use of surface acoustic wave technology. Applications include satellite, television, secure communication, multiples, and multiple access system. This updated bibliography contains 124 abstracts, 25 of which are new entries to the previous edition.

  10. Agents-based distributed processes control systems

    Directory of Open Access Journals (Sweden)

    Adrian Gligor

    2011-12-01

    Full Text Available Large industrial distributed systems have revealed a remarkable development in recent years. We may note an increase of their structural and functional complexity, at the same time with those on requirements side. These are some reasons why there are involvednumerous researches, energy and resources to solve problems related to these types of systems. The paper addresses the issue of industrial distributed systems with special attention being given to the distributed industrial processes control systems. A solution for a distributed process control system based on mobile intelligent agents is presented.The main objective of the proposed system is to provide an optimal solution in terms of costs, maintenance, reliability and flexibility. The paper focuses on requirements, architecture, functionality and advantages brought by the proposed solution.

  11. Experimental research on spectrum and imaging of continuous-wave terahertz radiation based on interferometry

    Science.gov (United States)

    Lu, Tie-Lin; Yuan, Hui; Kong, Ling-Qin; Zhao, Yue-Jin; Zhang, Liang-Liang; Zhang, Cun-Lin

    2016-08-01

    A system for measuring terahertz spectrum is proposed based on optical interferometer theory, and is experimentally demonstrated by using a backward-wave oscillator as the terahertz source. A high-resolution, high-precision interferometer is constructed by using a pyroelectric detector and a chopper. The results show that the spectral resolution is better than 1 GHz and the relative error of frequency is less than 3%. The terahertz energy density distribution is calculated by an inverse Fourier transform and tested to verify the feasibility of the interferometric approach. Two kinds of carbon-fiber composites are imaged. The results confirm that the interferometer is useful for transmission imaging of materials with different thickness values. Project supported by the National Natural Science Foundation of China (Grant Nos. 61377109 and 11374007).

  12. A Decentralized Eigenvalue Computation Method for Spectrum Sensing Based on Average Consensus

    Science.gov (United States)

    Mohammadi, Jafar; Limmer, Steffen; Stańczak, Sławomir

    2016-07-01

    This paper considers eigenvalue estimation for the decentralized inference problem for spectrum sensing. We propose a decentralized eigenvalue computation algorithm based on the power method, which is referred to as generalized power method GPM; it is capable of estimating the eigenvalues of a given covariance matrix under certain conditions. Furthermore, we have developed a decentralized implementation of GPM by splitting the iterative operations into local and global computation tasks. The global tasks require data exchange to be performed among the nodes. For this task, we apply an average consensus algorithm to efficiently perform the global computations. As a special case, we consider a structured graph that is a tree with clusters of nodes at its leaves. For an accelerated distributed implementation, we propose to use computation over multiple access channel (CoMAC) as a building block of the algorithm. Numerical simulations are provided to illustrate the performance of the two algorithms.

  13. Evolution of a Directional Wave Spectrum in a 3D Marginal Ice Zone with Random Floe Size Distribution

    Science.gov (United States)

    Montiel, F.; Squire, V. A.

    2013-12-01

    A new ocean wave/sea-ice interaction model is proposed that simulates how a directional wave spectrum evolves as it travels through a realistic marginal ice zone (MIZ), where wave/ice dynamics are entirely governed by coherent conservative wave scattering effects. Field experiments conducted by Wadhams et al. (1986) in the Greenland Sea generated important data on wave attenuation in the MIZ and, particularly, on whether the wave spectrum spreads directionally or collimates with distance from the ice edge. The data suggest that angular isotropy, arising from multiple scattering by ice floes, occurs close to the edge and thenceforth dominates wave propagation throughout the MIZ. Although several attempts have been made to replicate this finding theoretically, including by the use of numerical models, none have confronted this problem in a 3D MIZ with fully randomised floe distribution properties. We construct such a model by subdividing the discontinuous ice cover into adjacent infinite slabs of finite width parallel to the ice edge. Each slab contains an arbitrary (but finite) number of circular ice floes with randomly distributed properties. Ice floes are modeled as thin elastic plates with uniform thickness and finite draught. We consider a directional wave spectrum with harmonic time dependence incident on the MIZ from the open ocean, defined as a continuous superposition of plane waves traveling at different angles. The scattering problem within each slab is then solved using Graf's interaction theory for an arbitrary incident directional plane wave spectrum. Using an appropriate integral representation of the Hankel function of the first kind (see Cincotti et al., 1993), we map the outgoing circular wave field from each floe on the slab boundaries into a directional spectrum of plane waves, which characterizes the slab reflected and transmitted fields. Discretizing the angular spectrum, we can obtain a scattering matrix for each slab. Standard recursive

  14. Security Assessment of Web Based Distributed Applications

    Directory of Open Access Journals (Sweden)

    Catalin BOJA

    2010-01-01

    Full Text Available This paper presents an overview about the evaluation of risks and vulnerabilities in a web based distributed application by emphasizing aspects concerning the process of security assessment with regards to the audit field. In the audit process, an important activity is dedicated to the measurement of the characteristics taken into consideration for evaluation. From this point of view, the quality of the audit process depends on the quality of assessment methods and techniques. By doing a review of the fields involved in the research process, the approach wants to reflect the main concerns that address the web based distributed applications using exploratory research techniques. The results show that many are the aspects which must carefully be worked with, across a distributed system and they can be revealed by doing a depth introspective analyze upon the information flow and internal processes that are part of the system. This paper reveals the limitations of a non-existing unified security risk assessment model that could prevent such risks and vulnerabilities debated. Based on such standardize models, secure web based distributed applications can be easily audited and many vulnerabilities which can appear due to the lack of access to information can be avoided.

  15. A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses

    Institute of Scientific and Technical Information of China (English)

    Jian Ye(叶坚); Zichun Le(乐孜纯); Jingqiu Liang(梁静秋); Kai Liu(刘恺); Bisheng Quan(全必胜); Yali Qin(覃亚丽); Guangxin Zhu(朱广信)

    2004-01-01

    It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Fraunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Fraunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.

  16. Testing of Policy-Based Dynamic Spectrum Access Radios

    Science.gov (United States)

    2010-01-01

    WiFi , WiMax, etc.) and network size. 7) Network Join Time: Network join time characterizes the time for one slave node to join a previously formed DSA...may be achieved through built-in or commercially available GPS simulators, which also allow for the simulation of moving or varying locations...environment, with building obstructions, indoors and outdoors communications, and very dense RF spectrum utilization (due to RF interference or

  17. A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720nm

    CERN Document Server

    Gibson, N P; Barstow, J K; Evans, T M; Fletcher, L N; Irwin, P G J

    2012-01-01

    We report Gemini-South GMOS observations of the exoplanet system WASP-29 during primary transit as a test case for differential spectrophotometry. We use the multi-object spectrograph to observe the target star and a comparison star simultaneously to produce multiple light curves at varying wavelengths. The 'white' light curve and fifteen 'spectral' light curves are analysed to refine the system parameters and produce a transmission spectrum from 515 to 720nm. All light curves exhibit time-correlated noise, which we model using a variety of techniques. These include a simple noise rescaling, a Gaussian process model, and a wavelet based method. These methods all produce consistent results, although with different uncertainties. The precision of the transmission spectrum is improved by subtracting a common signal from all the spectral light curves, reaching a typical precision of ~1x10^-4 in transit depth. The transmission spectrum is free of spectral features, and given the non-detection of a pressure broaden...

  18. Evidence-Based Practice Guidelines for Fetal Alcohol Spectrum Disorder and Literacy and Learning

    Science.gov (United States)

    Mitten, H. Rae

    2013-01-01

    Evidence-based Practice Guidelines for Fetal Alcohol Spectrum Disorder (FASD) and Literacy and Learning are derived from an inductive analysis of qualitative data collected in field research. FASD is the umbrella term for a spectrum of neurocognitive and physical disabilities caused by prenatal exposure to alcohol. Data from a sample of N =150 was…

  19. Goodness-of-fit based secure cooperative spectrum sensing for cognitive radio network.

    Science.gov (United States)

    Vu-Van, Hiep; Koo, Insoo

    2014-01-01

    Cognitive radio (CR) is a promising technology for improving usage of frequency band. Cognitive radio users (CUs) are allowed to use the bands without interference in operation of licensed users. Reliable sensing information about status of licensed band is a prerequirement for CR network. Cooperative spectrum sensing (CSS) is able to offer an improved sensing reliability compared to individual sensing. However, the sensing performance of CSS can be destroyed due to the appearance of some malicious users. In this paper, we propose a goodness-of-fit (GOF) based cooperative spectrum sensing scheme to detect the dissimilarity between sensing information of normal CUs and that of malicious users, and reject their harmful effect to CSS. The empirical CDF will be used in GOF test to determine the measured distance between distributions of observation sample set according to each hypothesis of licensed user signal. Further, the DS theory is used to combine results of multi-GOF tests. The simulation results demonstrate that the proposed scheme can protect the sensing process against the attack from malicious users.

  20. Delay analysis of a point-to-multipoint spectrum sharing network with CSI based power allocation

    KAUST Repository

    Khan, Fahd Ahmed

    2012-10-01

    In this paper, we analyse the delay performance of a point-to-multipoint cognitive radio network which is sharing the spectrum with a point-to-multipoint primary network. The channel is assumed to be independent but not identically distributed and has Nakagami-m fading. A constraint on the peak transmit power of the secondary user transmitter (SU-Tx) is also considered in addition to the peak interference power constraint. Based on the constraints, a power allocation scheme which requires knowledge of the instantaneous channel state information (CSI) of the interference links is derived. The SU-Tx is assumed to be equipped with a buffer and is modelled using the M/G/1 queueing model. Closed form expressions for the probability distribution function (PDF) and cumulative distribution function (CDF) of the packet transmission time is derived. Using the PDF, the expressions for the moments of transmission time are obtained. In addition, using the moments, the expressions for the performance measures such as the total average waiting time of packets and the average number of packets waiting in the buffer of the SU-Tx are also obtained. Numerical simulations corroborate the theoretical results. © 2012 IEEE.

  1. Distributed measurement-based quantum computation

    CERN Document Server

    Danos, V; Kashefi, E; Panangaden, P; Danos, Vincent; Hondt, Ellie D'; Kashefi, Elham; Panangaden, Prakash

    2005-01-01

    We develop a formal model for distributed measurement-based quantum computations, adopting an agent-based view, such that computations are described locally where possible. Because the network quantum state is in general entangled, we need to model it as a global structure, reminiscent of global memory in classical agent systems. Local quantum computations are described as measurement patterns. Since measurement-based quantum computation is inherently distributed, this allows us to extend naturally several concepts of the measurement calculus, a formal model for such computations. Our goal is to define an assembly language, i.e. we assume that computations are well-defined and we do not concern ourselves with verification techniques. The operational semantics for systems of agents is given by a probabilistic transition system, and we define operational equivalence in a way that it corresponds to the notion of bisimilarity. With this in place, we prove that teleportation is bisimilar to a direct quantum channe...

  2. Scale-free Universal Spectrum for Atmospheric Aerosol Size Distribution for Davos, Mauna Loa and Izana

    CERN Document Server

    Selvam, A M

    2011-01-01

    Atmospheric flows exhibit fractal fluctuations and inverse power law form for power spectra indicating an eddy continuum structure for the selfsimilar fluctuations. A general systems theory for fractal fluctuations developed by the author is based on the simple visualisation that large eddies form by space-time integration of enclosed turbulent eddies, a concept analogous to Kinetic Theory of Gases in Classical Statistical Physics. The ordered growth of atmospheric eddy continuum is in dynamical equilibrium and is associated with Maximum Entropy Production. The model predicts universal (scale-free) inverse power law form for fractal fluctuations expressed in terms of the golden mean. Atmospheric particulates are held in suspension in the fractal fluctuations of vertical wind velocity. The mass or radius (size) distribution for homogeneous suspended atmospheric particulates is expressed as a universal scale-independent function of the golden mean, the total number concentration and the mean volume radius. Mode...

  3. Mirror system based therapy for autism spectrum disorders

    Institute of Scientific and Technical Information of China (English)

    Wei CHEN; Jing ZHANG; Jun DING

    2008-01-01

    This paper reviews the present theories and empirical research of autisms' cognitive research and mir-ror systems and introduces a new hypothesis about the causes of autism spectrum disorders (ASD): autistic mir-ror neuron dysfunction hypothesis. ASD subjects show obvious lack of the activation of the mirror system during the task of observation or emotional cognition. It is sig-nificant to investigate the mirror system for revealing the causes of autism and it is also helpful for developing new ways to diagnose or treat this disorder.

  4. Generalized Block Sparse Constraint Based Compressive Wideband Spectrum Sensing for Cognitive Radio

    CERN Document Server

    Liu, Yipeng

    2010-01-01

    Wideband spectrum sensing detects the unused spectrum holes for dynamic spectrum access of cognitive radios. However the too high sampling rate is the challenge for application. As the survey shows that the monitoring primary signal has sparse representation in frequency domain, compressive sensing can be used to transfer the sampling burden to the digital signal processor. An analog to information converter can randomly sample the received signal with sub-Nyquist rate to obtain the random measurements. In the spectrum recovery, to match the practical situation, an improved block sparse signal model can be formulated in that the static frequency spectrum allocation of primary radios means the bounds between di?erent primary radios is known. The whole monitoring spectrum is divided sections of di?erent length in accordance with di?erent allocated primary radios. The minimization of the l2 norm can encourage the dense distribution locally, while the l1 norm of the l2 norms can give the sparse distribution of th...

  5. Monitoring Mechanical Motion of Carbon Nanotube based Nanomotor by Optical Absorption Spectrum

    CERN Document Server

    Wang, Baomin; Wang, Zhan; Wang, Yong; Liu, Kaihui

    2016-01-01

    The optical absorption spectrums of nanomotors made from double-wall carbon nanotubes have been calculated with the time-dependent density functional based tight binding method. When the outer short tube of the nanomotor moves along or rotates around the inner long tube, the peaks in the spectrum will gradually evolve and may shift periodically, the amplitude of which can be as large as hundreds of meV. We show that the features and behaviors of the optical absorption spectrum could be used to monitor the mechanical motions of the double-wall carbon nanotube based nanomotor.

  6. Cognitive Radio Spectrum Sensing Algorithms based on Eigenvalue and Covariance methods

    Directory of Open Access Journals (Sweden)

    K.SESHU KUMAR

    2013-04-01

    Full Text Available Spectrum sensing method is the fundamental factor when we are working with cognitive radio systems. Main aim and fundamental problem of cognitive radio is to identify weather primary users in authorized or licensed spectrum is presented or not. Paper deals with a new scheme of sensing based on the eigenvalues concept. It contain signals of covariance matrix received by the secondary users. In this method we are suggested two algorithms of sensing, one algorithm established by the maximum to minimum eigenvalue ratio. Other algorithm focused on average to minimum eigenvalue ratio. These two are done by using random matrix theories (RMT, and also these RMT are latest and also produce some accurate results. Now we calculate the ratios of distributions and probabilities of detection (Pd and derive the probabilities of false alarm (Pfa for the proposed algorithms, and also finding thresholds values for given Pfa. This method will improve the problem of noise uncertainty, and also performance isimproved compare to energy detection when highly correlated signal is available. Paper also deals with another method is and also covariance methods. First one is statistical covariance method, it has different noise and received signal, and it is used for finding the primary users presence where there is only noise. These algorithms implemented by use of small number of received signal samples and processed to calculate the sample covariance matrix. By use of sample covariance matrix we are extracted two test statistics. Finally we compare these results and concluded that signal presence. These are used in many signal detection applications, and also do not need signal information, also noise power and channel. We did the Simulations based on two ways. First one is randomly generated signals. Other one is done by captured DTV signals taken from ATSV committee, these are broadcasting signals. These methods confirm and verifies the efficiency of the proposed

  7. Gravitational Wave Spectrums from Pole-like Inflations based on Generalized Gravity Theories

    CERN Document Server

    Hwang, J

    1998-01-01

    We present a general and unified formulation which can handle the classical evolution and quantum generation processes of the cosmological gravitational wave in a broad class of generalized gravity theories. Applications are made in several inflation models based on the scalar-tensor theory, the induced gravity, and the low energy effective action of string theory. The gravitational wave power spectrums based on the vacuum expectation value of the quantized fluctuating metric during the pole-like inflation stages are derived in analytic forms. Assuming that the gravity theory transits to Einstein one while the relevant scales remain in the superhorizon scale, we derive the consequent power spectrums and the directional fluctuations of the relic radiation produced by the gravitational wave. The spectrums seeded by the vacuum fluctuations in the pole-like inflation models based on the generalized gravity show a distinguished common feature which differs from the scale invariant spectrum generated in an exponent...

  8. Reducing Spectrum Handoffs and Energy Switching Consumption of MADM-Based Decisions in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Rafael Aguilar-Gonzalez

    2016-01-01

    Full Text Available In a cognitive radio network (CRN, the number of spectrum handoffs increases energy consumption of cognitive (or secondary users due to the channel switching process. This might limit the operation of the CRN, especially in scenarios where secondary users terminals are battery-powered. Thus, reducing the number of times a cognitive user involved in a transmission switch to different spectrum holes is required to increase battery life-time. In this regard, available spectrum holes possess different attributes (e.g., bandwidth that can be exploited to satisfy specific secondary users requirements (i.e., connection profile for data transmission while saving energy. Here, three multiple attribute decision-making (MADM algorithms for the spectrum decision functionality are evaluated using real spectrum measurements of TV bands. This is performed by proposing six decision parameters, which are extracted from the spectrum data to characterize its suitability. Then, these are used as inputs of the MADM algorithms to select the most suitable spectrum hole for a cognitive user. Thus, an enhanced MADM-based decision process is proposed to reduce the number of handoffs considering energy consumption due to channel switching (ECCS. Results quantify savings from 30% to 90% in ECCS and spectrum handoffs reductions from 47% to 90%.

  9. The spatial distribution of known predictors of autism spectrum disorders impacts geographic variability in prevalence in central North Carolina

    Directory of Open Access Journals (Sweden)

    Hoffman Kate

    2012-10-01

    Full Text Available Abstract Background The causes of autism spectrum disorders (ASD remain largely unknown and widely debated; however, evidence increasingly points to the importance of environmental exposures. A growing number of studies use geographic variability in ASD prevalence or exposure patterns to investigate the association between environmental factors and ASD. However, differences in the geographic distribution of established risk and predictive factors for ASD, such as maternal education or age, can interfere with investigations of ASD etiology. We evaluated geographic variability in the prevalence of ASD in central North Carolina and the impact of spatial confounding by known risk and predictive factors. Methods Children meeting a standardized case definition for ASD at 8 years of age were identified through records-based surveillance for 8 counties biennially from 2002 to 2008 (n=532. Vital records were used to identify the underlying cohort (15% random sample of children born in the same years as children with an ASD, n=11,034, and to obtain birth addresses. We used generalized additive models (GAMs to estimate the prevalence of ASD across the region by smoothing latitude and longitude. GAMs, unlike methods used in previous spatial analyses of ASD, allow for extensive adjustment of individual-level risk factors (e.g. maternal age and education when evaluating spatial variability of disease prevalence. Results Unadjusted maps revealed geographic variation in surveillance-recognized ASD. Children born in certain regions of the study area were up to 1.27 times as likely to be recognized as having ASD compared to children born in the study area as a whole (prevalence ratio (PR range across the study area 0.57-1.27; global P=0.003. However, geographic gradients of ASD prevalence were attenuated after adjusting for spatial confounders (adjusted PR range 0.72-1.12 across the study area; global P=0.052. Conclusions In these data, spatial variation of ASD

  10. [Research on spectrum technology based on SG-DBR laser].

    Science.gov (United States)

    Shao, Jie; Han, Ye-Xing; Guo, Jie; Wang, Li-Ming; Han, Ying; Ying, Chao-Fu; Wang, Yao

    2014-07-01

    Tunable diode laser absorption spectroscopy (TDLAS) is a highly sensitive, highly selective, noninvasive and real-time trace gas detection technique, which has been widely used in atmospheric monitoring and industrial control. In the present research, a new type of widely tunable SG-DBR diode laser (WTDL) with a tunable range of about 1 520-1 570 nm was use as the light source for tunable diode laser absorption spectroscopy combined with the wavelength modulation (wm) to measure the spectrum of multi-gases. Also the structure, performance and other characteristics of WTDL were introduced. There were 18 channels compiled to the SG-DBR laser, which emitted central wavelength at the optimum absorption transitions of CO, CO2 and H2O by homemade program, of which 14 channels (corresponding to absorption lines of CO and CO2) were investigated by second harmonic detection technique. Meanwhile, the detectabilities in these channel were analyzed which are about 10(-5) at the peak absorbance. The experiment results validate the feasibility of SG-DBR laser used as light source in multi-gases detection using wavelength modulation absorption spectroscopy technique in practical application. That could effectively reduce the cost and complexity of system in the field of TDLAS technique.

  11. Dependence of the neutron monitor count rate and time delay distribution on the rigidity spectrum of primary cosmic rays

    Science.gov (United States)

    Mangeard, P.-S.; Ruffolo, D.; Sáiz, A.; Nuntiyakul, W.; Bieber, J. W.; Clem, J.; Evenson, P.; Pyle, R.; Duldig, M. L.; Humble, J. E.

    2016-12-01

    Neutron monitors are the premier instruments for precisely tracking time variations in the Galactic cosmic ray flux at GeV-range energies above the geomagnetic cutoff at the location of measurement. Recently, a new capability has been developed to record and analyze the neutron time delay distribution (related to neutron multiplicity) to infer variations in the cosmic ray spectrum as well. In particular, from time delay histograms we can determine the leader fraction L, defined as the fraction of neutrons that did not follow a previous neutron detection in the same tube from the same atmospheric secondary particle. Using data taken during 2000-2007 by a shipborne neutron monitor latitude survey, we observe a strong dependence of the count rate and L on the geomagnetic cutoff. We have modeled this dependence using Monte Carlo simulations of cosmic ray interactions in the atmosphere and in the neutron monitor. We present new yield functions for the count rate of a neutron monitor at sea level. The simulation results show a variation of L with geomagnetic cutoff as observed by the latitude survey, confirming that these changes in L can be attributed to changes in the cosmic ray spectrum arriving at Earth's atmosphere. We also observe a variation in L with time at a fixed cutoff, which reflects the evolution of the cosmic ray spectrum with the sunspot cycle, known as solar modulation.

  12. Distributed Monitoring System Based on ICINGA

    CERN Document Server

    Haen, C; Neufeld, N

    2011-01-01

    The LHCb online system relies on a large and heterogeneous I.T. infrastructure : it comprises more than 2000 servers and embedded systems and more than 200 network devices. While for the control and monitoring of detectors, PLCs, and readout boards an industry standard SCADA system PVSSII has been put in production, we use a low level monitoring system to monitor the control infrastructure itself. While our previous system was based on a single central NAGIOS server, our current system uses a distributed ICINGA infrastructure.

  13. Node-based analysis of species distributions

    DEFF Research Database (Denmark)

    Borregaard, Michael Krabbe; Rahbek, Carsten; Fjeldså, Jon;

    2014-01-01

    The integration of species distributions and evolutionary relationships is one of the most rapidly moving research fields today and has led to considerable advances in our understanding of the processes underlying biogeographical patterns. Here, we develop a set of metrics, the specific overrepre......The integration of species distributions and evolutionary relationships is one of the most rapidly moving research fields today and has led to considerable advances in our understanding of the processes underlying biogeographical patterns. Here, we develop a set of metrics, the specific...... with case studies on two groups with well-described biogeographical histories: a local-scale community data set of hummingbirds in the North Andes, and a large-scale data set of the distribution of all species of New World flycatchers. The node-based analysis of these two groups generates a set...... of intuitively interpretable patterns that are consistent with current biogeographical knowledge.Importantly, the results are statistically tractable, opening many possibilities for their use in analyses of evolutionary, historical and spatial patterns of species diversity. The method is implemented...

  14. Value-based distribution feeder automation planning

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Jen-Hao [Department of Electrical Engineering, I-Shou University, No. 1, Section 1, Syuecheng Road, Dashu Township, Kaohsiung 840, Taiwan (Taiwan); Lu, Chan-Nan [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (Taiwan)

    2006-03-15

    In a competitive electric energy market, service quality and reliability are two of the essential issues of the business. Distribution automation has been chosen by many utilities around the world as one of the most reliable measures for reducing outage time in their distribution networks. Considering network reliability data and the customer interruption costs, a value-based planning method is proposed in this paper to find the optimal numbers and locations of switches in feeder automation systems. The proposed method takes reliability costs, maintenance and investment costs into account to obtain a feeder automation plan that has a maximum benefit and a proper system reliability requirement. Three stages are involved in the search for optimal solution. Using minimum feeder data and assume equally distributed feeder loads, stage 1 gives initial estimates of reliability indices and costs, and benefit/cost ratios of different feeder automation options. To gain the maximum benefits from feeder automation with reasonable costs, results of stage 1 are used to select feeders with highest priorities for automations. Stage 2 determines the optimum locations of switches that minimize feeder outage costs, and in stage 3, the best locations for tie switches in the automated network are determined. Numerical processing procedure is described and the solution efficiency and results are compared with those obtained from a genetic algorithm. (author)

  15. Distributing Knight. Using Type-Based Publish/Subscribe for Building Distributed Collaboration Tools

    DEFF Research Database (Denmark)

    Damm, Christian Heide; Hansen, Klaus Marius

    2002-01-01

    Distributed applications are hard to understand, build, and evolve. The need for decoupling, flexibility, and heterogeneity in distributed collaboration tools present particular problems; for such applications, having the right abstractions and primitives for distributed communication becomes even...... more important. We present Distributed Knight, an extension to the Knight tool, for distributed, collaborative, and gesture-based object-oriented modelling. Distributed Knight was built using the type-based publish/subscribe paradigm. Based on this case, we argue that type-based publish....../subscribe provides a natural and effective abstraction for developing distributed collaboration tools....

  16. Reconstruction of halo power spectrum from redshift-space galaxy distribution: cylinder-grouping method and halo exclusion effect

    CERN Document Server

    Okumura, Teppei; More, Surhud; Masaki, Shogo

    2016-01-01

    The peculiar velocity field measured by redshift-space distortions (RSD) in galaxy surveys provides a unique probe of the growth of large-scale structure. However, systematic effects arise when including satellite galaxies in the clustering analysis. Since satellite galaxies tend to reside in massive halos with a greater halo bias, the inclusion boosts the clustering power. In addition, virial motions of the satellite galaxies cause a significant suppression of the clustering power due to nonlinear RSD effects. We develop a novel method to recover the redshift-space power spectrum of halos from the observed galaxy distribution by minimizing the contamination of satellite galaxies. The cylinder grouping method (CGM) we study effectively excludes satellite galaxies from a galaxy sample. However, we find that this technique produces apparent anisotropies in the reconstructed halo distribution over all the scales which mimic RSD. On small scales, the apparent anisotropic clustering is caused by exclusion of halos...

  17. Application of egs4 computer code for determination of gamma ray spectrum and dose rate distribution in gammacell 220

    Science.gov (United States)

    Raisali, G. R.; Sohrabpour, M.

    1993-10-01

    The EGS4 a Monte Carlo electron-photon transport simulation package together with a locally developed computer program "GCELL" has been used to simulate the transport of the gamma rays in Gammacell 220. An additional lead attenuator has been inserted in the chamber, has been included for those cases where lower dose rates were required. For three cases of 0, 1.35 and 4.0 cm thickness of added lead attenuators, the gamma spectrum, and dose rate distribution inside the chamber have been determined. For the case of no attenuator present, the main shield around the source cage has been included in the simulation program and its albedo effects have been investigated. The calculated dose rate distribution in the Gammacell chamber has been compared against measurements carried out with Fricke, PMMA and Gafchromic film dosimeters.

  18. Mimo radar waveform design for spectrum sharing with cellular systems a Matlab based approach

    CERN Document Server

    Khawar, Awais; Clancy, T Charles

    2016-01-01

    This book discusses spectrum sharing between cellular systems and radars. The book addresses a novel way to design radar waveforms that can enable spectrum sharing between radars and communication systems, without causing interference to communication systems, and at the same time achieving radar objectives of target detection, estimation, and tracking. The book includes a MATLAB-based approach, which provides reader with a way to learn, experiment, compare, and build on top of existing algorithms.

  19. Nonlinear propagation of focused ultrasound in layered biological tissues based on angular spectrum approach

    Institute of Scientific and Technical Information of China (English)

    Zhu Xiao-Feng; Zhou Lin; Zhang Dong; Gong Xiu-Fen

    2005-01-01

    Nonlinear propagation of focused ultrasound in layered biological tissues is theoretically studied by using the angular spectrum approach (ASA), in which an acoustic wave is decomposed into its angular spectrum, and the distribution of nonlinear acoustic fields is calculated in arbitrary planes normal to the acoustic axis. Several biological tissues are used as specimens inserted into the focusing region illuminated by a focused piston source. The second harmonic components within or beyond the biological specimens are numerically calculated. Validity of the theoretical model is examined by measurements. This approach employing the fast Fourier transformation gives a clear visualization of the focused ultrasound, which is helpful for nonlinear ultrasonic imaging.

  20. Chip-based quantum key distribution

    Science.gov (United States)

    Sibson, P.; Erven, C.; Godfrey, M.; Miki, S.; Yamashita, T.; Fujiwara, M.; Sasaki, M.; Terai, H.; Tanner, M. G.; Natarajan, C. M.; Hadfield, R. H.; O'Brien, J. L.; Thompson, M. G.

    2017-02-01

    Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip--monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols--BB84, Coherent One Way and Differential Phase Shift--with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.

  1. Chip-based quantum key distribution

    Science.gov (United States)

    Sibson, P.; Erven, C.; Godfrey, M.; Miki, S.; Yamashita, T.; Fujiwara, M.; Sasaki, M.; Terai, H.; Tanner, M. G.; Natarajan, C. M.; Hadfield, R. H.; O'Brien, J. L.; Thompson, M. G.

    2017-01-01

    Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip—monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols—BB84, Coherent One Way and Differential Phase Shift—with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks. PMID:28181489

  2. Novel water-based antiseptic lotion demonstrates rapid, broad-spectrum kill compared with alcohol antiseptic.

    Science.gov (United States)

    Czerwinski, Steven E; Cozean, Jesse; Cozean, Colette

    2014-01-01

    A novel alcohol-based antiseptic and a novel water-based antiseptic lotion, both with a synergistic combination of antimicrobial ingredients containing 0.2% benzethonium chloride, were evaluated using the standard time-kill method against 25 FDA-specified challenge microorganisms. The purpose of the testing was to determine whether a non-alcohol product could have equivalent rapid and broad-spectrum kill to a traditional alcohol sanitizer. Both the alcohol- and water-based products showed rapid and broad-spectrum antimicrobial activity. The average 15-s kill was 99.999% of the challenge organism for the alcohol-based antiseptic and 99.971% for the water-based antiseptic. The alcohol-based product demonstrated 100% of peak efficacy (60s) within the first 15s, whereas the water-based product showed 99.97%. The novel alcohol-based antiseptic reduced concentrations of 100% of organisms by 99.999%, whereas the water-based antiseptic lotion showed the same reduction for 96% of organisms. A novel water-based antiseptic product demonstrated equivalent rapid, broad-spectrum antimicrobial activity to an alcohol-based sanitizer and provided additional benefits of reduced irritation, persistent effect, and greater efficacy against common viruses. The combination of rapid, broad-spectrum immediate kill and persistent efficacy against pathogens may have significant clinical benefit in limiting the spread of disease.

  3. The visibility based Tapered Gridded Estimator (TGE) for the redshifted 21-cm power spectrum

    CERN Document Server

    Choudhuri, Samir; Chatterjee, Suman; Ali, Sk Saiyad; Roy, Nirupam; Ghosh, Abhik

    2016-01-01

    We present the improved visibility based Tapered Gridded Estimator (TGE) for the power spectrum of the diffuse sky signal. The visibilities are gridded to reduce the computation, and tapered through a convolution to suppress the contribution from the outer regions of the telescope's field of view. The TGE also internally estimates the noise bias, and subtracts this out to give an unbiased estimate of the power spectrum. An earlier version of the 2D TGE for the angular power spectrum $C_{\\ell}$ is improved and then extended to obtain the 3D TGE for the power spectrum $P({\\bf k})$ of the 21-cm brightness temperature fluctuations. Analytic formulas are also presented for predicting the variance of the binned power spectrum. The estimator and its variance predictions are validated using simulations of $150 \\, {\\rm MHz}$ GMRT observations. We find that the estimator accurately recovers the input model for the 1D Spherical Power Spectrum $P(k)$ and the 2D Cylindrical Power Spectrum $P(k_\\perp,k_\\parallel)$, and the...

  4. Distributed Spectrum Sensing with Sequential Ordered Transmissions to a Cognitive Fusion Center

    CERN Document Server

    Hesham, Laila; Nafie, Mohammed

    2011-01-01

    Cooperative spectrum sensing is a robust strategy that enhances the detection probability of primary licensed users. However, a large number of detectors reporting to a fusion center for a final decision causes significant delay and also presumes the availability of unreasonable communication resources at the disposal of a network searching for spectral opportunities. In this work, we employ the idea of sequential detection to obtain a quick, yet reliable, decision regarding primary activity. Local detectors take measurements, and only a few of them transmit the log likelihood ratios (LLR) to a fusion center in descending order of LLR magnitude. The fusion center runs a sequential test with a maximum imposed on the number of sensors that can report their LLR measurements. We calculate the detection thresholds using two methods. The first achieves the same probability of error as the optimal block detector. In the second, an objective function is constructed and decision thresholds are obtained via backward in...

  5. A Study on the Distributed Antenna Based Heterogeneous Cognitive Wireless Network Synchronous MAC Protocol

    Directory of Open Access Journals (Sweden)

    Lian-Fen Huang

    2015-01-01

    Full Text Available This paper introduces distributed antennas into a cognitive radio network and presents a heterogeneous network. The best contribution of this paper is that it designs a synchronous cognitive MAC protocol (DAHCWNS-MAC protocol: distributed antenna based heterogeneous cognitive wireless network synchronous MAC protocol. The novel protocol aims at combining the advantages of cognitive radio and distributed antennas to fully utilize the licensed spectrum, broaden the communication range, and improve throughput. This paper carries out the mathematical modeling and performance simulation to demonstrate its superiority in improving the network throughput at the cost of increasing antenna hardware costs.

  6. Research of Adaptive Resolution Spectrum Sensing Method Based on Discrete Wavelet Packet Transform

    Directory of Open Access Journals (Sweden)

    Wei Naiqi

    2013-09-01

    Full Text Available Spectrum sensing is the precondition of the realization of cognitive radio. In order to achieve efficient multi-resolution spectrum sensing, and find the available spectrum hole quickly, it proposes a variable resolution adaptive frequency spectrum energy sensing method based on discrete wavelet packet transform (DWPT. The method applied hierarchical decomposition and threshold denoising characteristic of wavelet packet transform, and solved the problem of subband sort disorder in wavelet packet decomposition process; it can eliminate the influence of uncertainty noise on detection performance, effectively. It also can reduce the computational complexity according to demand of selection resolution and perception band. The simulation results and its analysis show that the proposed method has advantages of high precision, simple arithmetic and fine flexibility, etc. The method is adapted to fast sensing in the cognitive radio environment.  

  7. Cluster-based spectrum sensing for cognitive radios with imperfect channel to cluster-head

    KAUST Repository

    Ben Ghorbel, Mahdi

    2012-04-01

    Spectrum sensing is considered as the first and main step for cognitive radio systems to achieve an efficient use of spectrum. Cooperation and clustering among cognitive radio users are two techniques that can be employed with spectrum sensing in order to improve the sensing performance by reducing miss-detection and false alarm. In this paper, within the framework of a clustering-based cooperative spectrum sensing scheme, we study the effect of errors in transmitting the local decisions from the secondary users to the cluster heads (or the fusion center), while considering non-identical channel conditions between the secondary users. Closed-form expressions for the global probabilities of detection and false alarm at the cluster head are derived. © 2012 IEEE.

  8. Total Variation Minimization Based Compressive Wideband Spectrum Sensing for Cognitive Radios

    CERN Document Server

    Liu, Yipeng

    2011-01-01

    Wideband spectrum sensing is a critical component of a functioning cognitive radio system. Its major challenge is the too high sampling rate requirement. Compressive sensing (CS) promises to be able to deal with it. Nearly all the current CS based compressive wideband spectrum sensing methods exploit only the frequency sparsity to perform. Motivated by the achievement of a fast and robust detection of the wideband spectrum change, total variation mnimization is incorporated to exploit the temporal and frequency structure information to enhance the sparse level. As a sparser vector is obtained, the spectrum sensing period would be shorten and sensing accuracy would be enhanced. Both theoretical evaluation and numerical experiments can demonstrate the performance improvement.

  9. Spectrum reconstruction method based on the detector response model calibrated by x-ray fluorescence

    Science.gov (United States)

    Li, Ruizhe; Li, Liang; Chen, Zhiqiang

    2017-02-01

    Accurate estimation of distortion-free spectra is important but difficult in various applications, especially for spectral computed tomography. Two key problems must be solved to reconstruct the incident spectrum. One is the acquisition of the detector energy response. It can be calculated by Monte Carlo simulation, which requires detailed modeling of the detector system and a high computational power. It can also be acquired by establishing a parametric response model and be calibrated using monochromatic x-ray sources, such as synchrotron sources or radioactive isotopes. However, these monochromatic sources are difficult to obtain. Inspired by x-ray fluorescence (XRF) spectrum modeling, we propose a feasible method to obtain the detector energy response based on an optimized parametric model for CdZnTe or CdTe detectors. The other key problem is the reconstruction of the incident spectrum with the detector response. Directly obtaining an accurate solution from noisy data is difficult because the reconstruction problem is severely ill-posed. Different from the existing spectrum stripping method, a maximum likelihood-expectation maximization iterative algorithm is developed based on the Poisson noise model of the system. Simulation and experiment results show that our method is effective for spectrum reconstruction and markedly increases the accuracy of XRF spectra compared with the spectrum stripping method. The applicability of the proposed method is discussed, and promising results are presented.

  10. Compressive spectrum sensing of radar pulses based on photonic techniques.

    Science.gov (United States)

    Guo, Qiang; Liang, Yunhua; Chen, Minghua; Chen, Hongwei; Xie, Shizhong

    2015-02-23

    We present a photonic-assisted compressive sampling (CS) system which can acquire about 10(6) radar pulses per second spanning from 500 MHz to 5 GHz with a 520-MHz analog-to-digital converter (ADC). A rectangular pulse, a linear frequency modulated (LFM) pulse and a pulse stream is respectively reconstructed faithfully through this system with a sliding window-based recovery algorithm, demonstrating the feasibility of the proposed photonic-assisted CS system in spectral estimation for radar pulses.

  11. Spectrum sensing algorithm based on autocorrelation energy in cognitive radio networks

    Science.gov (United States)

    Ren, Shengwei; Zhang, Li; Zhang, Shibing

    2016-10-01

    Cognitive radio networks have wide applications in the smart home, personal communications and other wireless communication. Spectrum sensing is the main challenge in cognitive radios. This paper proposes a new spectrum sensing algorithm which is based on the autocorrelation energy of signal received. By taking the autocorrelation energy of the received signal as the statistics of spectrum sensing, the effect of the channel noise on the detection performance is reduced. Simulation results show that the algorithm is effective and performs well in low signal-to-noise ratio. Compared with the maximum generalized eigenvalue detection (MGED) algorithm, function of covariance matrix based detection (FMD) algorithm and autocorrelation-based detection (AD) algorithm, the proposed algorithm has 2 11 dB advantage.

  12. Strength-Based Educational Programming for Students with Autism Spectrum Disorders: A Case for Video Self-Modeling

    Science.gov (United States)

    Bellini, Scott; McConnell, Luke L.

    2010-01-01

    Video-self modeling (VSM) is an effective but underused instructional strategy for youth on the autism spectrum. The authors present VSM in the context of strength-based educational programming for youth on the autism spectrum. The authors summarize research studies investigating VSM with youth on the autism spectrum in school settings and discuss…

  13. Spectrum Sharing Based on a Bertrand Game in Cognitive Radio Sensor Networks

    Science.gov (United States)

    Zeng, Biqing; Zhang, Chi; Hu, Pianpian; Wang, Shengyu

    2017-01-01

    In the study of power control and allocation based on pricing, the utility of secondary users is usually studied from the perspective of the signal to noise ratio. The study of secondary user utility from the perspective of communication demand can not only promote the secondary users to meet the maximum communication needs, but also to maximize the utilization of spectrum resources, however, research in this area is lacking, so from the viewpoint of meeting the demand of network communication, this paper designs a two stage model to solve spectrum leasing and allocation problem in cognitive radio sensor networks (CRSNs). In the first stage, the secondary base station collects the secondary network communication requirements, and rents spectrum resources from several primary base stations using the Bertrand game to model the transaction behavior of the primary base station and secondary base station. The second stage, the subcarriers and power allocation problem of secondary base stations is defined as a nonlinear programming problem to be solved based on Nash bargaining. The simulation results show that the proposed model can satisfy the communication requirements of each user in a fair and efficient way compared to other spectrum sharing schemes. PMID:28067850

  14. Spectrum Sharing Based on a Bertrand Game in Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Biqing Zeng

    2017-01-01

    Full Text Available In the study of power control and allocation based on pricing, the utility of secondary users is usually studied from the perspective of the signal to noise ratio. The study of secondary user utility from the perspective of communication demand can not only promote the secondary users to meet the maximum communication needs, but also to maximize the utilization of spectrum resources, however, research in this area is lacking, so from the viewpoint of meeting the demand of network communication, this paper designs a two stage model to solve spectrum leasing and allocation problem in cognitive radio sensor networks (CRSNs. In the first stage, the secondary base station collects the secondary network communication requirements, and rents spectrum resources from several primary base stations using the Bertrand game to model the transaction behavior of the primary base station and secondary base station. The second stage, the subcarriers and power allocation problem of secondary base stations is defined as a nonlinear programming problem to be solved based on Nash bargaining. The simulation results show that the proposed model can satisfy the communication requirements of each user in a fair and efficient way compared to other spectrum sharing schemes.

  15. A Modified Energy Detection Based Spectrum Sensing Algorithm for Green Cognitive Radio Communication

    Directory of Open Access Journals (Sweden)

    Sidra Rajput

    2015-10-01

    Full Text Available Spectrum Sensing is the first and fundamental function of Cognitive Cycle which plays a vital role in the success of CRs (Cognitive Radios. Spectrum Sensing indicate the presence and absence of PUs (Primary Users in RF (Radio Frequency spectrum occupancy measurements. In order to correctly determine the presence and absence of Primary Users, the algorithms in practice include complex mathematics which increases the computational complexity of the algorithm, thus shifted the CRs to operate as ?green? communication systems. In this paper, an energy efficient and computationally less complex, energy detection based Spectrum Sensing algorithm have been proposed. The design goals of the proposed algorithm are to save the processing and sensing energies. At first, by using less MAC (Multiply and Accumulate operation, it saves the processing energy needed to determine the presence and absence of PUs. Secondly, it saves the sensing energy by providing a way to find lowest possible sensing time at which spectrum is to be sensed. Two scenarios have been defined for testing the proposed algorithm i.e. simulate detection capability of Primary Users in ideal and noisy scenarios. Detection of PUs in both of these scenarios have been compared to obtain the probability of detection. Energy Efficiency of the proposed algorithm has been proved by making performance comparison between the proposed (less complex algorithm and the legacy energy detection algorithm. With reduced complexity, the proposed spectrum sensing algorithm can be considered under the paradigm of Green Cognitive Radio Communication

  16. Optimal Entropy-Based Cooperative Spectrum Sensing for Maritime Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Waleed Ejaz

    2013-11-01

    Full Text Available Maritime cognitive radio networks (MCRNs have recently been proposed for opportunistic utilization of the licensed band. Spectrum sensing is one of the key issues for the successful deployment of the MCRNs. The maritime environment is unique in terms of radio wave propagation over water, surface reflection and wave occlusions. In order to deal with the challenging maritime environment, we proposed an optimal entropy-based cooperative spectrum sensing. As the results of spectrum sensing are sensitive to the number of samples in an entropy-based local detection scheme, we first calculated the optimal number of samples. Next, a cooperative spectrum sensing scheme considering the conditions of the sea environment is proposed. Finally, the throughput optimization of the m-out-of-n rule is considered. Results revealed that although the existing schemes work well for the lower sea states, they fail to perform at higher sea states. Moreover, simulation results also indicated the robustness of the entropy-based scheme and the proposed cooperative spectrum sensing scheme at higher sea states in comparison with the traditional energy detector.

  17. DENOISING METHOD BASED ON SINGULAR SPECTRUM ANALYSIS AND ITS APPLICATIONS IN CALCULATION OF MAXIMAL LIAPUNOV EXPONENT

    Institute of Scientific and Technical Information of China (English)

    LIU Yuan-feng; ZHAO Mei

    2005-01-01

    An algorithm based on the data-adaptive filtering characteristics of singular spectrum analysis (SSA) is proposed to denoise chaotic data. Firstly, the empirical orthogonal functions ( EOFs ) and principal components ( PCs ) of the signal were calculated, reconstruct the signal using the EOFs and PCs, and choose the optimal reconstructing order based on sigular spectrum to obtain the denoised signal. The noise of the signal can influence the calculating precision of maximal Liapunov exponents. The proposed denoising algorithm was applied to the maximal Liapunov exponents calculations of two chaotic system, Henon map and Logistic map. Some numerical results show that this denoising algorithm could improve the calculating precision of maximal Liapunov exponent.

  18. Opportunistic spectrum access in cognitive radio based on channel switching

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-01-01

    This paper investigates the performance of a cognitive radio transceiver that can monitor multiple channels and opportunistically use any one of them should it be available. In our work, we propose and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. Two switching strategies, namely the switch and examine and the switch and stay strategies, are proposed. For these proposed access schemes, we investigate their performance by deriving the analytical expression of the novel metric of the average access duration and the average waiting time and based on these two metrics a time average SU throughput formula is proposed to predict the performance of the secondary cognitive system. © 2012 ICST.

  19. LPI Radar Waveform Recognition Based on Time-Frequency Distribution.

    Science.gov (United States)

    Zhang, Ming; Liu, Lutao; Diao, Ming

    2016-10-12

    In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI) radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM), BPSK (Barker code modulation), Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4). The classifier is Elman neural network (ENN), and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA), image binarization algorithm and Pseudo-Zernike moments, etc., the features are extracted from the Choi-Williams time-frequency distribution (CWD) image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR) is 94.7% at signal-to-noise ratio (SNR) of -2 dB.

  20. LPI Radar Waveform Recognition Based on Time-Frequency Distribution

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2016-10-01

    Full Text Available In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM, BPSK (Barker code modulation, Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4. The classifier is Elman neural network (ENN, and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA, image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR is 94.7% at signal-to-noise ratio (SNR of −2 dB.

  1. Prognostic for hydraulic pump based upon DCT-composite spectrum and the modified echo state network.

    Science.gov (United States)

    Sun, Jian; Li, Hongru; Xu, Baohua

    2016-01-01

    Prognostic is a key step of the condition-based maintenance (CBM). In order to improve the predicting performance, a novel method for prognostic for the hydraulic pump is proposed in this paper. Based on the improvement of the traditional composite spectrum, the DCT-composite spectrum (DCS) fusion algorithm is initially presented to make fusion of multi-channel vibration signals. The DCS composite spectrum entropy is extracted as the feature. Furthermore, the modified echo state networks (ESN) model is established for prognostic using the extracted feature. The reservoir is updated and the elements of the neighboring matrix are redefined for improving predicting accuracy. Analysis of the application in the hydraulic pump degradation experiment demonstrates that the proposed algorithm is feasible and is meaningful for CBM.

  2. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Salim, Shelly; Moh, Sangman

    2016-06-30

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  3. De-noising of Raman spectrum signal based on stationary wavelet transform

    Institute of Scientific and Technical Information of China (English)

    Qingwei Gao(高清维); Zhaoqi Sun(孙兆奇); Zhuoliang Cao(曹卓良); Pu Cheng(程蒲)

    2004-01-01

    @@ In this paper,the Raman spectrum signal de-noising based on stationary wavelet transform is discussed.Haar wavelet is selected to decompose the Raman spectrum signal for several levels based on stationarywavelet transform.The noise mean square σj is estimated by the wavelet details at every level,and thewavelet details toward 0 by a threshold σj √2lnn,where n is length of the detail,then recovery signalis reconstructed.Experimental results show this method not only suppresses noise effectively,but alsopreserves as many target characteristics of original signal as possible.This de-noising method offers a veryattractive alternative to Raman spectrum signal noise suppress.

  4. Design of a broad spectrum multichannel optical filter based on FBG

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-tao; PAN Wei; YAN Lian-shan; LUO Bin; WEN Kun-hua; FENG Xian-gui

    2009-01-01

    To increase the channel number in the optic filter, the multiple-phase-shift (MPS) technology is adoped based on the multiple-reflection-spectrum-envelopes-concatenation (MRSEC) model which has a broadband flatness. The reflection spectra of the MPS digital concatenated sample gratings are simulated with transfer matrix method, the results show that wave band of the reflection spectrum is widened and the channel number is multiplied. What's more, the spectrum flatness is improved with the increasing of refraction index change. Moreover, to improve the extinction ratio and peak value when MPS is adopted in concatenated SFBG, an available designing method based on the cascaded unit is put forward and the optimized results are obtained.

  5. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Shelly Salim

    2016-06-01

    Full Text Available A cognitive radio sensor network (CRSN is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  6. Physiology-based face recognition in the thermal infrared spectrum.

    Science.gov (United States)

    Buddharaju, Pradeep; Pavlidis, Ioannis T; Tsiamyrtzis, Panagiotis; Bazakos, Mike

    2007-04-01

    The current dominant approaches to face recognition rely on facial characteristics that are on or over the skin. Some of these characteristics have low permanency can be altered, and their phenomenology varies significantly with environmental factors (e.g., lighting). Many methodologies have been developed to address these problems to various degrees. However, the current framework of face recognition research has a potential weakness due to its very nature. We present a novel framework for face recognition based on physiological information. The motivation behind this effort is to capitalize on the permanency of innate characteristics that are under the skin. To establish feasibility, we propose a specific methodology to capture facial physiological patterns using the bioheat information contained in thermal imagery. First, the algorithm delineates the human face from the background using the Bayesian framework. Then, it localizes the superficial blood vessel network using image morphology. The extracted vascular network produces contour shapes that are characteristic to each individual. The branching points of the skeletonized vascular network are referred to as Thermal Minutia Points (TMPs) and constitute the feature database. To render the method robust to facial pose variations, we collect for each subject to be stored in the database five different pose images (center, midleft profile, left profile, midright profile, and right profile). During the classification stage, the algorithm first estimates the pose of the test image. Then, it matches the local and global TMP structures extracted from the test image with those of the corresponding pose images in the database. We have conducted experiments on a multipose database of thermal facial images collected in our laboratory, as well as on the time-gap database of the University of Notre Dame. The good experimental results show that the proposed methodology has merit, especially with respect to the problem of

  7. A Novel Dynamic Spectrum Access Framework Based on Reinforcement Learning for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Lin, Yun; Wang, Chao; Wang, Jiaxing; Dou, Zheng

    2016-10-12

    Cognitive radio sensor networks are one of the kinds of application where cognitive techniques can be adopted and have many potential applications, challenges and future research trends. According to the research surveys, dynamic spectrum access is an important and necessary technology for future cognitive sensor networks. Traditional methods of dynamic spectrum access are based on spectrum holes and they have some drawbacks, such as low accessibility and high interruptibility, which negatively affect the transmission performance of the sensor networks. To address this problem, in this paper a new initialization mechanism is proposed to establish a communication link and set up a sensor network without adopting spectrum holes to convey control information. Specifically, firstly a transmission channel model for analyzing the maximum accessible capacity for three different polices in a fading environment is discussed. Secondly, a hybrid spectrum access algorithm based on a reinforcement learning model is proposed for the power allocation problem of both the transmission channel and the control channel. Finally, extensive simulations have been conducted and simulation results show that this new algorithm provides a significant improvement in terms of the tradeoff between the control channel reliability and the efficiency of the transmission channel.

  8. A Novel Dynamic Spectrum Access Framework Based on Reinforcement Learning for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yun Lin

    2016-10-01

    Full Text Available Cognitive radio sensor networks are one of the kinds of application where cognitive techniques can be adopted and have many potential applications, challenges and future research trends. According to the research surveys, dynamic spectrum access is an important and necessary technology for future cognitive sensor networks. Traditional methods of dynamic spectrum access are based on spectrum holes and they have some drawbacks, such as low accessibility and high interruptibility, which negatively affect the transmission performance of the sensor networks. To address this problem, in this paper a new initialization mechanism is proposed to establish a communication link and set up a sensor network without adopting spectrum holes to convey control information. Specifically, firstly a transmission channel model for analyzing the maximum accessible capacity for three different polices in a fading environment is discussed. Secondly, a hybrid spectrum access algorithm based on a reinforcement learning model is proposed for the power allocation problem of both the transmission channel and the control channel. Finally, extensive simulations have been conducted and simulation results show that this new algorithm provides a significant improvement in terms of the tradeoff between the control channel reliability and the efficiency of the transmission channel.

  9. Relationship Status among Parents of Children with Autism Spectrum Disorders: A Population-Based Study

    Science.gov (United States)

    Freedman, Brian H.; Kalb, Luther G.; Zablotsky, Benjamin; Stuart, Elizabeth A.

    2012-01-01

    Despite speculation about an 80% divorce rate among parents of children with an Autism Spectrum Disorder (ASD), very little empirical and no epidemiological research has addressed the issue of separation and divorce among this population. Data for this study was taken from the 2007 National Survey of Children's Health, a population-based,…

  10. Medicaid 1915(c) Home- and Community-Based Services Waivers for Children with Autism Spectrum Disorder

    Science.gov (United States)

    Velott, Diana L.; Agbese, Edeanya; Mandell, David; Stein, Bradley D.; Dick, Andrew W.; Yu, Hao; Leslie, Douglas L.

    2016-01-01

    This research aims to describe the characteristics of 1915(c) Home- and Community-Based Services waivers for children with autism spectrum disorder across states and over time. While increasingly popular, little is known about these Medicaid waivers. Understanding the characteristics of these programs is important to clinicians and policymakers in…

  11. Incorporating Video Modeling into a School-Based Intervention for Students with Autism Spectrum Disorders

    Science.gov (United States)

    Wilson, Kaitlyn P.

    2013-01-01

    Purpose: Video modeling is an intervention strategy that has been shown to be effective in improving the social and communication skills of students with autism spectrum disorders, or ASDs. The purpose of this tutorial is to outline empirically supported, step-by-step instructions for the use of video modeling by school-based speech-language…

  12. Innovative Technology-Based Interventions for Autism Spectrum Disorders: A Meta-Analysis

    Science.gov (United States)

    Grynszpan, Ouriel; Weiss, Patrice L.; Perez-Diaz, Fernando; Gal, Eynat

    2014-01-01

    This article reports the results of a meta-analysis of technology-based intervention studies for children with autism spectrum disorders. We conducted a systematic review of research that used a pre-post design to assess innovative technology interventions, including computer programs, virtual reality, and robotics. The selected studies provided…

  13. National Study of School Psychologists' Use of Evidence-Based Assessment in Autism Spectrum Disorder

    Science.gov (United States)

    Aiello, Rachel; Ruble, Lisa; Esler, Amy

    2017-01-01

    This study aimed to better understand predictors of evidence-based assessment practices for autism spectrum disorder (ASD). Nationwide, 402 school psychologists were surveyed for their knowledge of and training and experience with ASD on assessment practices, including reported areas of training needs. The majority of school psychologists reported…

  14. Epilepsy Among Children and Adolescents with Autism Spectrum Disorders: A Population-Based Study

    Science.gov (United States)

    Jokiranta, Elina; Sourander, Andre; Suominen, Auli; Timonen-Soivio, Laura; Brown, Alan S.; Sillanpää, Matti

    2014-01-01

    The present population-based study examines associations between epilepsy and autism spectrum disorders (ASD). The cohort includes register data of 4,705 children born between 1987 and 2005 and diagnosed as cases of childhood autism, Asperger's syndrome or pervasive developmental disorders--not otherwise specified. Each case was matched to four…

  15. Mindfulness-Based Therapy in Adults with an Autism Spectrum Disorder: A Randomized Controlled Trial

    Science.gov (United States)

    Spek, Annelies A.; van Ham, Nadia C.; Nyklicek, Ivan

    2013-01-01

    Research shows that depression and anxiety disorders are the most common psychiatric concern in autism spectrum disorders (ASD). Mindfulness-based therapy (MBT) has been found effective in reducing anxiety and depression symptoms, however research in autism is limited. Therefore, we examined the effects of a modified MBT protocol (MBT-AS) in…

  16. Epilepsy Among Children and Adolescents with Autism Spectrum Disorders: A Population-Based Study

    Science.gov (United States)

    Jokiranta, Elina; Sourander, Andre; Suominen, Auli; Timonen-Soivio, Laura; Brown, Alan S.; Sillanpää, Matti

    2014-01-01

    The present population-based study examines associations between epilepsy and autism spectrum disorders (ASD). The cohort includes register data of 4,705 children born between 1987 and 2005 and diagnosed as cases of childhood autism, Asperger's syndrome or pervasive developmental disorders--not otherwise specified. Each case was matched to four…

  17. Prediction of speech intelligibility based on a correlation metric in the envelope power spectrum domain

    DEFF Research Database (Denmark)

    Relano-Iborra, Helia; May, Tobias; Zaar, Johannes

    -based Envelope Power Spectrum Model (mr-sEPSM) [2], combined with the correlation back-end of the Short-Time Objective Intelligibility measure (STOI) [3]. The sEPSMcorr can accurately predict NH data for a broad range of listening conditions, e.g., additive noise, phase jitter and ideal binary mask processing....

  18. Incorporating Video Modeling into a School-Based Intervention for Students with Autism Spectrum Disorders

    Science.gov (United States)

    Wilson, Kaitlyn P.

    2013-01-01

    Purpose: Video modeling is an intervention strategy that has been shown to be effective in improving the social and communication skills of students with autism spectrum disorders, or ASDs. The purpose of this tutorial is to outline empirically supported, step-by-step instructions for the use of video modeling by school-based speech-language…

  19. Video Modeling: A Visually Based Intervention for Children with Autism Spectrum Disorder

    Science.gov (United States)

    Ganz, Jennifer B.; Earles-Vollrath, Theresa L.; Cook, Katherine E.

    2011-01-01

    Visually based interventions such as video modeling have been demonstrated to be effective with students with autism spectrum disorder (ASD). This approach has wide utility, is appropriate for use with students of a range of ages and abilities, promotes independent functioning, and can be used to address numerous learner objectives, including…

  20. Epilepsy Among Children and Adolescents with Autism Spectrum Disorders: A Population-Based Study

    Science.gov (United States)

    Jokiranta, Elina; Sourander, Andre; Suominen, Auli; Timonen-Soivio, Laura; Brown, Alan S.; Sillanpää, Matti

    2014-01-01

    The present population-based study examines associations between epilepsy and autism spectrum disorders (ASD). The cohort includes register data of 4,705 children born between 1987 and 2005 and diagnosed as cases of childhood autism, Asperger's syndrome or pervasive developmental disorders--not otherwise specified. Each case was matched to…

  1. Mindfulness-Based Therapy in Adults with an Autism Spectrum Disorder: A Randomized Controlled Trial

    Science.gov (United States)

    Spek, Annelies A.; van Ham, Nadia C.; Nyklicek, Ivan

    2013-01-01

    Research shows that depression and anxiety disorders are the most common psychiatric concern in autism spectrum disorders (ASD). Mindfulness-based therapy (MBT) has been found effective in reducing anxiety and depression symptoms, however research in autism is limited. Therefore, we examined the effects of a modified MBT protocol (MBT-AS) in…

  2. A Community-Based Early Intervention Program for Toddlers with Autism Spectrum Disorders

    Science.gov (United States)

    Rollins, Pamela Rosenthal; Campbell, Michelle; Hoffman, Renee Thibodeau; Self, Kayli

    2016-01-01

    This study examined Pathways Early Autism Intervention, a community-based, parent-mediated, intensive behavioral and developmental intervention program for children with autism spectrum disorders that could be used as a model for state-funded early intervention programs. A single-subject, multiple-baseline, across-participants design was used.…

  3. Enhancing the Motor Skills of Children with Autism Spectrum Disorders: A Pool-Based Approach

    Science.gov (United States)

    Lee, Jihyun; Porretta, David L.

    2013-01-01

    Children with autism spectrum disorders (ASDs) often experience difficulties with motor skill learning and performance. The pool is a unique learning environment that can help children with ASDs learn or improve aquatic skills, fitness, and social skills. A pool-based approach is also aligned with the elements of dynamic systems theory, which…

  4. Morphometric Analysis of Recognized Genes for Autism Spectrum Disorders and Obesity in Relationship to the Distribution of Protein-Coding Genes on Human Chromosomes

    Directory of Open Access Journals (Sweden)

    Austen B. McGuire

    2016-05-01

    Full Text Available Mammalian chromosomes are comprised of complex chromatin architecture with the specific assembly and configuration of each chromosome influencing gene expression and function in yet undefined ways by varying degrees of heterochromatinization that result in Giemsa (G negative euchromatic (light bands and G-positive heterochromatic (dark bands. We carried out morphometric measurements of high-resolution chromosome ideograms for the first time to characterize the total euchromatic and heterochromatic chromosome band length, distribution and localization of 20,145 known protein-coding genes, 790 recognized autism spectrum disorder (ASD genes and 365 obesity genes. The individual lengths of G-negative euchromatin and G-positive heterochromatin chromosome bands were measured in millimeters and recorded from scaled and stacked digital images of 850-band high-resolution ideograms supplied by the International Society of Chromosome Nomenclature (ISCN 2013. Our overall measurements followed established banding patterns based on chromosome size. G-negative euchromatic band regions contained 60% of protein-coding genes while the remaining 40% were distributed across the four heterochromatic dark band sub-types. ASD genes were disproportionately overrepresented in the darker heterochromatic sub-bands, while the obesity gene distribution pattern did not significantly differ from protein-coding genes. Our study supports recent trends implicating genes located in heterochromatin regions playing a role in biological processes including neurodevelopment and function, specifically genes associated with ASD.

  5. Morphometric Analysis of Recognized Genes for Autism Spectrum Disorders and Obesity in Relationship to the Distribution of Protein-Coding Genes on Human Chromosomes.

    Science.gov (United States)

    McGuire, Austen B; Rafi, Syed K; Manzardo, Ann M; Butler, Merlin G

    2016-05-05

    Mammalian chromosomes are comprised of complex chromatin architecture with the specific assembly and configuration of each chromosome influencing gene expression and function in yet undefined ways by varying degrees of heterochromatinization that result in Giemsa (G) negative euchromatic (light) bands and G-positive heterochromatic (dark) bands. We carried out morphometric measurements of high-resolution chromosome ideograms for the first time to characterize the total euchromatic and heterochromatic chromosome band length, distribution and localization of 20,145 known protein-coding genes, 790 recognized autism spectrum disorder (ASD) genes and 365 obesity genes. The individual lengths of G-negative euchromatin and G-positive heterochromatin chromosome bands were measured in millimeters and recorded from scaled and stacked digital images of 850-band high-resolution ideograms supplied by the International Society of Chromosome Nomenclature (ISCN) 2013. Our overall measurements followed established banding patterns based on chromosome size. G-negative euchromatic band regions contained 60% of protein-coding genes while the remaining 40% were distributed across the four heterochromatic dark band sub-types. ASD genes were disproportionately overrepresented in the darker heterochromatic sub-bands, while the obesity gene distribution pattern did not significantly differ from protein-coding genes. Our study supports recent trends implicating genes located in heterochromatin regions playing a role in biological processes including neurodevelopment and function, specifically genes associated with ASD.

  6. Experimental validation of a distributed algorithm for dynamic spectrum access in local area networks

    DEFF Research Database (Denmark)

    Tonelli, Oscar; Berardinelli, Gilberto; Tavares, Fernando Menezes Leitão;

    2013-01-01

    Next generation wireless networks aim at a significant improvement of the spectral efficiency in order to meet the dramatic increase in data service demand. In local area scenarios user-deployed base stations are expected to take place, thus making the centralized planning of frequency resources...

  7. Schemes of Repeater Optimizing Distribution based on the MLC Application and CBLRD Simulation

    Directory of Open Access Journals (Sweden)

    Qian Qiuye

    2013-07-01

    Full Text Available The widely use of repeaters raises concern about their coordination among the public. Since repeaters may suffer interaction and limitation bearing capacity, designing a reasonable repeaters coordination method is of great significance. This study address the problem if repeater coordination in a circular flat area with minimal number of repeaters with seamless coverage theory, system simulation method. With 1,000 users, this study model the coverage, getting the minimal number of repeaters of different coverage radius based on extensive used regular hexagon coverage theory. A numerical example was given in this case. When the number of users increases to 10,000, this study simulate to get the signal density across the area according to the consideration of repeaters and the different distribution of users, which are divided into uniform distribution, linear distribution, normal distribution and lognormal distribution. Then, Multi-Layer Coverage (MLC and Coverage by Link Rate Density (CBLRD are created as the distribution scheme on the area where repeat service demand is large. Moreover, for solution on the distribution of the repeaters with barriers, distribution schemes are given considering the transmission of VHF spectrums and the distribution of users around the barrier. Additionally, Spring Comfortable Degree (SCD is used for evaluation of the results and the developing tends are given to improve the model. Due to the reasonable assumption, the solution of repeater distribution is of pivotal reference value based on the reasonable results.

  8. Material grain size characterization method based on energy attenuation coefficient spectrum and support vector regression.

    Science.gov (United States)

    Li, Min; Zhou, Tong; Song, Yanan

    2016-07-01

    A grain size characterization method based on energy attenuation coefficient spectrum and support vector regression (SVR) is proposed. First, the spectra of the first and second back-wall echoes are cut into several frequency bands to calculate the energy attenuation coefficient spectrum. Second, the frequency band that is sensitive to grain size variation is determined. Finally, a statistical model between the energy attenuation coefficient in the sensitive frequency band and average grain size is established through SVR. Experimental verification is conducted on austenitic stainless steel. The average relative error of the predicted grain size is 5.65%, which is better than that of conventional methods.

  9. A demodulation method of Temperature-Spectrum width based on Chirped fiber grating

    Directory of Open Access Journals (Sweden)

    Chen Si

    2016-01-01

    Full Text Available Based on spectral reflection characteristics of chirped FBGs, a demodulation method for complex temperature fields is proposed in this paper. Relationships between the reflective spectrums and the temperatures are investigated through theoretical analyses. Testing results are acquired from a FBG sensing model which is designed according to the newly-developed method. A simulation to get the relationships between reflective spectrums and temperatures is set which shows that this demodulation method is feasible and its demodulation precision is beyond +/−1°C. The method provides a new method for analyzing complex temperature fields.

  10. High Performance Power Spectrum Analysis Using a FPGA Based Reconfigurable Computing Platform

    CERN Document Server

    Abhyankar, Yogindra; Agarwal, Yogesh; Subrahmanya, C R; Prasad, Peeyush; 10.1109/RECONF.2006.307786

    2011-01-01

    Power-spectrum analysis is an important tool providing critical information about a signal. The range of applications includes communication-systems to DNA-sequencing. If there is interference present on a transmitted signal, it could be due to a natural cause or superimposed forcefully. In the latter case, its early detection and analysis becomes important. In such situations having a small observation window, a quick look at power-spectrum can reveal a great deal of information, including frequency and source of interference. In this paper, we present our design of a FPGA based reconfigurable platform for high performance power-spectrum analysis. This allows for the real-time data-acquisition and processing of samples of the incoming signal in a small time frame. The processing consists of computation of power, its average and peak, over a set of input values. This platform sustains simultaneous data streams on each of the four input channels.

  11. Diagnostic technique of pine wood nematode disease based on THz spectrum

    Science.gov (United States)

    Liu, Yunfei; Tan, Jiajin; Jiang, Liang; Shi, Shengcai; Jin, Biaobing; Ma, Jinlong

    2008-12-01

    Pine wood nematode disease, namely pine wilt disease, is caused by the invasion of Bursaphelenchus xylophilus (Bx) into pines. Once susceptible pines are infected by the nematode, the disease develops rapidly, the infected pines cease to exude oleoresin and die quickly. Hence it is called pine cancer. Given the fact that there are still no good methods in diagnosing the disease, here we propose to study the spectroscopic characteristics of pine wood nematode and diseased pine wood in the THz regime in order to look for a rapid spectroscopic discrimination method for the disease. Firstly, we measure the transmittances of a Bx sample, a B. mucronatus (Bm) sample, a healthy Pinus massoniana wood sample and a diseased P. massoniana wood sample by a superconducting heterodyne mixer at 500 GHz. And their characteristics are compared. Secondly, we measure the transmission characteristics of a Bx sample and a Bm sample by terahertz time domain spectroscopy (THz-TDS). The measured time domain spectrums and corresponding frequency domain spectrums are compared to distinguish them from their absorption characteristics. Thirdly, we measure the transmission characteristics of a healthy P. massoniana wood sample and a diseased P. massoniana wood sample by THz TDS and compare their difference in THz absorption spectrum and diffraction dispersive spectrum to confirm the effect of Bx on P. massoniana by the absorption coefficient and refractive index. Some discussions are given for future development of the diagnostic technique of pine wood nematode disease based on THz spectrum.

  12. A Robust FLOM Based Spectrum Sensing Scheme under Middleton Class A Noise in IoT

    Directory of Open Access Journals (Sweden)

    Enwei Xu

    2017-01-01

    Full Text Available Accessibility to remote users in dynamic environment, high spectrum utilization, and no spectrum purchase make Cognitive Radio (CR a feasible solution of wireless communications in the Internet of Things (IoT. Reliable spectrum sensing becomes the prerequisite for the establishment of communication between IoT-capable objects. Considering the application environment, spectrum sensing not only has to cope with man-made impulsive noises but also needs to overcome noise fluctuations. In this paper, we study the Fractional Lower Order Moments (FLOM based spectrum sensing method under Middleton Class A noise and incorporate a Noise Power Estimation (NPE module into the sensing system to deal with the issue of noise uncertainty. Moreover, the NPE process does not need noise-only samples. The analytical expressions of the probabilities of detection and the probability of false alarm are derived. The impact on sensing performance of the parameters of the NPE module is also analyzed. The theoretical analysis and simulation results show that our proposed sensing method achieves a satisfactory performance at low SNR.

  13. A ground-based optical transmission spectrum of WASP-6b

    Energy Technology Data Exchange (ETDEWEB)

    Jordán, Andrés; Espinoza, Néstor; Rabus, Markus [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile); Eyheramendy, Susana [Departmento de Estadística, Facultad de Matemáticas, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile); Sing, David K. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Désert, Jean-Michel [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Bakos, Gáspár Á. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); López-Morales, Mercedes; Szentgyorgyi, Andrew [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Maxted, Pierre F. L. [Astrophysics Group, Keele University, Staffordshire ST5 5BG (United Kingdom); Triaud, Amaury H. M. J. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-12-01

    We present a ground-based optical transmission spectrum of the inflated sub-Jupiter-mass planet WASP-6b. The spectrum was measured in 20 spectral channels from 480 nm to 860 nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the Inamori-Magellan Areal Camera and Spectrograph on the Baade Telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured transmission spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensates in the atmosphere of WASP-6b. WASP-6b therefore appears to be yet another massive exoplanet with evidence for a mostly featureless transmission spectrum, underscoring the importance that hazes and condensates can have in determining the transmission spectra of exoplanets.

  14. Wireless Technology Recognition Based on RSSI Distribution at Sub-Nyquist Sampling Rate for Constrained Devices.

    Science.gov (United States)

    Liu, Wei; Kulin, Merima; Kazaz, Tarik; Shahid, Adnan; Moerman, Ingrid; De Poorter, Eli

    2017-09-12

    Driven by the fast growth of wireless communication, the trend of sharing spectrum among heterogeneous technologies becomes increasingly dominant. Identifying concurrent technologies is an important step towards efficient spectrum sharing. However, due to the complexity of recognition algorithms and the strict condition of sampling speed, communication systems capable of recognizing signals other than their own type are extremely rare. This work proves that multi-model distribution of the received signal strength indicator (RSSI) is related to the signals' modulation schemes and medium access mechanisms, and RSSI from different technologies may exhibit highly distinctive features. A distinction is made between technologies with a streaming or a non-streaming property, and appropriate feature spaces can be established either by deriving parameters such as packet duration from RSSI or directly using RSSI's probability distribution. An experimental study shows that even RSSI acquired at a sub-Nyquist sampling rate is able to provide sufficient features to differentiate technologies such as Wi-Fi, Long Term Evolution (LTE), Digital Video Broadcasting-Terrestrial (DVB-T) and Bluetooth. The usage of the RSSI distribution-based feature space is illustrated via a sample algorithm. Experimental evaluation indicates that more than 92% accuracy is achieved with the appropriate configuration. As the analysis of RSSI distribution is straightforward and less demanding in terms of system requirements, we believe it is highly valuable for recognition of wideband technologies on constrained devices in the context of dynamic spectrum access.

  15. Atmospheric correction of remote sensing imagery based on the surface spectrum's vector space

    Institute of Scientific and Technical Information of China (English)

    CHEN Chun; LIU ChengYu; ZHANG ShuQing

    2012-01-01

    Due to the atmosphere effect,the qualities of images decrease conspicuously,practically in the visible bands,in the processing of earth observation by the satellite-borne sensors.Thus,removing the atmosphere effects has become a key step to improve the qualities of images and to retrieve the actual reflectivity of surface features.An atmospheric correction approach,called ACVSS (Atmospheric Correction based Vector Space of Spectrum),is proposed here based on the vector space of the features'spectrum.The reflectance image of each band is retrieved first according to the radiative transfer equation,then the spectrum's vector space is constructed using the infrared bands,and finally the residual errors of the reflectance images in the visible bands are corrected based on the pixel position in the spectrum's vector space.The proposed methodology is verified through atmospheric correction on Landsat-7 ETM+ imagery.The experimental results show that our method is more accurate and the corrected image is more distinct,compared with those offered by current popular atmospheric correction software.

  16. A Spectrum Handoff Scheme for Optimal Network Selection in NEMO Based Cognitive Radio Vehicular Networks

    Directory of Open Access Journals (Sweden)

    Krishan Kumar

    2017-01-01

    Full Text Available When a mobile network changes its point of attachments in Cognitive Radio (CR vehicular networks, the Mobile Router (MR requires spectrum handoff. Network Mobility (NEMO in CR vehicular networks is concerned with the management of this movement. In future NEMO based CR vehicular networks deployment, multiple radio access networks may coexist in the overlapping areas having different characteristics in terms of multiple attributes. The CR vehicular node may have the capability to make call for two or more types of nonsafety services such as voice, video, and best effort simultaneously. Hence, it becomes difficult for MR to select optimal network for the spectrum handoff. This can be done by performing spectrum handoff using Multiple Attributes Decision Making (MADM methods which is the objective of the paper. The MADM methods such as grey relational analysis and cost based methods are used. The application of MADM methods provides wider and optimum choice among the available networks with quality of service. Numerical results reveal that the proposed scheme is effective for spectrum handoff decision for optimal network selection with reduced complexity in NEMO based CR vehicular networks.

  17. Instantaneous spectrum estimation of earthquake ground motions based on unscented Kalman filter method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Representing earthquake ground motion as time varying ARMA model, the instantaneous spectrum can only be determined by the time varying coefficients of the corresponding ARMA model. In this paper, unscented Kalman filter is applied to estimate the time varying coefficients. The comparison between the estimation results of unscented Kalman filter and Kalman filter methods shows that unscented Kalman filter can more precisely represent the distribution of the spectral peaks in time-frequency plane than Kalman filter, and its time and frequency resolution is finer which ensures its better ability to track the local properties of earthquake ground motions and to identify the systems with nonlinearity or abruptness. Moreover, the estimation results of ARMA models with different orders indicate that the theoretical frequency resolving power ofARMA model which was usually ignored in former studies has great effect on the estimation precision of instantaneous spectrum and it should be taken as one of the key factors in order selection of ARMA model.

  18. Integrated Power Flow and Short Circuit Calculation Method for Distribution Network with Inverter Based Distributed Generation

    Directory of Open Access Journals (Sweden)

    Shan Yang

    2016-01-01

    Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.

  19. Distribution Network Design--literature study based

    OpenAIRE

    Li, Ang

    2012-01-01

    The focus of this research is companies' outbound distribution network design in supply chain management. Within the present competitive market, it is a fundamental importance for companies to achieve high level business performance with an effective supply chain. Outbound distribution network design as an important part in supply chain management, to a large extent decides whether companies can fulfill customers' requirement or not. Therefore, such a study is important for manufacturers and ...

  20. Spectrum synthesis for a spectrally tunable light source based on a DMD-convex grating Offner configuration

    Science.gov (United States)

    Ma, Suodong; Pan, Qiao; Shen, Weimin

    2016-09-01

    As one kind of light source simulation devices, spectrally tunable light sources are able to generate specific spectral shape and radiant intensity outputs according to different application requirements, which have urgent demands in many fields of the national economy and the national defense industry. Compared with the LED-type spectrally tunable light source, the one based on a DMD-convex grating Offner configuration has advantages of high spectral resolution, strong digital controllability, high spectrum synthesis accuracy, etc. As a key link of the above type light source to achieve target spectrum outputs, spectrum synthesis algorithm based on spectrum matching is therefore very important. An improved spectrum synthesis algorithm based on linear least square initialization and Levenberg-Marquardt iterative optimization is proposed in this paper on the basis of in-depth study of the spectrum matching principle. The effectiveness of the proposed method is verified by a series of simulations and experimental works.

  1. Chapter 17: Web-based Tools - Spectrum and Filter Services for the VO

    Science.gov (United States)

    Dobos, L.; Budavari, T.

    We present the Filter and Spectrum Services consisting of easy-to-use web applications and web services for searching, plotting and managing large collections of spectral energy distribution data and filter profiles as well as for performing various scientific operations on spectra in a unified framework. The services provide keyword search, advanced query forms and SQL query possibilities for selecting spectra or bandpass curves which may be retrieved in a variety of file formats including XML, VOTable and ASCII. All SDSS DR1-DR5 spectra had been loaded into a database as well as the entire 2dF catalog that adds up to more than 2.5 million SEDs of about a million spatial objects, but registered users can upload their own data making it available for the rest of the community and are free to modify or delete them at any time. Theoretical catalogs, such as the Bruzual-Charlot stochastic burst model spectrum library (100k spectra) and the BaSeL stellar library are also available. Scientific services allow building rest-frame composite spectra out of selected spectra; calculating synthetic magnitudes by convolving spectra with an arbitrary set of bandpass curves of optical instrument filters to generate simulated photometric catalogs on-thefly; galactic extinction correction, fitting of the continuum using different set of templates (Bruzual-Charlot '03 templates, SDSS eigenspectra), line fitting. All scientific functionality is available from the web user interface and via the SOAP web services for programmers. MySpectrum is a cross-platform version of the spectrum web service for setting up your own spectrum repository. It integrates into the main service allowing easy access to your data for the whole VO community. The main idea behind our web services is to move scientific functionality physically close to the database in order to spare network bandwidth. This way scientists may do research without setting up expensive hardware, downloading large datasets for days

  2. The Fault Feature Extraction of Rolling Bearing Based on EMD and Difference Spectrum of Singular Value

    Directory of Open Access Journals (Sweden)

    Te Han

    2016-01-01

    Full Text Available Nowadays, the fault diagnosis of rolling bearing in aeroengines is based on the vibration signal measured on casing, instead of bearing block. However, the vibration signal of the bearing is often covered by a series of complex components caused by other structures (rotor, gears. Therefore, when bearings cause failure, it is still not certain that the fault feature can be extracted from the vibration signal on casing. In order to solve this problem, a novel fault feature extraction method for rolling bearing based on empirical mode decomposition (EMD and the difference spectrum of singular value is proposed in this paper. Firstly, the vibration signal is decomposed by EMD. Next, the difference spectrum of singular value method is applied. The study finds that each peak on the difference spectrum corresponds to each component in the original signal. According to the peaks on the difference spectrum, the component signal of the bearing fault can be reconstructed. To validate the proposed method, the bearing fault data collected on the casing are analyzed. The results indicate that the proposed rolling bearing diagnosis method can accurately extract the fault feature that is submerged in other component signals and noise.

  3. The high-resolution extraterrestrial solar spectrum (QASUMEFTS determined from ground-based solar irradiance measurements

    Directory of Open Access Journals (Sweden)

    J. Gröbner

    2017-09-01

    Full Text Available A high-resolution extraterrestrial solar spectrum has been determined from ground-based measurements of direct solar spectral irradiance (SSI over the wavelength range from 300 to 500 nm using the Langley-plot technique. The measurements were obtained at the Izaña Atmospheric Research Centre from the Agencia Estatal de Meteorología, Tenerife, Spain, during the period 12 to 24 September 2016. This solar spectrum (QASUMEFTS was combined from medium-resolution (bandpass of 0.86 nm measurements of the QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe spectroradiometer in the wavelength range from 300 to 500 nm and high-resolution measurements (0.025 nm from a Fourier transform spectroradiometer (FTS over the wavelength range from 305 to 380 nm. The Kitt Peak solar flux atlas was used to extend this high-resolution solar spectrum to 500 nm. The expanded uncertainties of this solar spectrum are 2 % between 310 and 500 nm and 4 % at 300 nm. The comparison of this solar spectrum with solar spectra measured in space (top of the atmosphere gave very good agreements in some cases, while in some other cases discrepancies of up to 5 % were observed. The QASUMEFTS solar spectrum represents a benchmark dataset with uncertainties lower than anything previously published. The metrological traceability of the measurements to the International System of Units (SI is assured by an unbroken chain of calibrations leading to the primary spectral irradiance standard of the Physikalisch-Technische Bundesanstalt in Germany.

  4. Code Synchronization Algorithm Based on Segment Correlation in Spread Spectrum Communication

    Directory of Open Access Journals (Sweden)

    Aohan Li

    2015-10-01

    Full Text Available Spread Spectrum (SPSP Communication is the theoretical basis of Direct Sequence Spread Spectrum (DSSS transceiver technology. Spreading code, modulation, demodulation, carrier synchronization and code synchronization in SPSP communications are the core parts of DSSS transceivers. This paper focuses on the code synchronization problem in SPSP communications. A novel code synchronization algorithm based on segment correlation is proposed. The proposed algorithm can effectively deal with the informational misjudgment caused by the unreasonable data acquisition times. This misjudgment may lead to an inability of DSSS receivers to restore transmitted signals. Simulation results show the feasibility of a DSSS transceiver design based on the proposed code synchronization algorithm. Finally, the communication functions of the DSSS transceiver based on the proposed code synchronization algorithm are implemented on Field Programmable Gate Array (FPGA.

  5. Shape-based hand recognition approach using the morphological pattern spectrum

    Science.gov (United States)

    Ramirez-Cortes, Juan Manuel; Gomez-Gil, Pilar; Sanchez-Perez, Gabriel; Prieto-Castro, Cesar

    2009-01-01

    We propose the use of the morphological pattern spectrum, or pecstrum, as the base of a biometric shape-based hand recognition system. The system receives an image of the right hand of a subject in an unconstrained pose, which is captured with a commercial flatbed scanner. According to pecstrum property of invariance to translation and rotation, the system does not require the use of pegs for a fixed hand position, which simplifies the image acquisition process. This novel feature-extraction method is tested using a Euclidean distance classifier for identification and verification cases, obtaining 97% correct identification, and an equal error rate (EER) of 0.0285 (2.85%) for the verification mode. The obtained results indicate that the pattern spectrum represents a good feature-extraction alternative for low- and medium-level hand-shape-based biometric applications.

  6. Optimal allocation of solar based distributed generators in distribution system using Bat algorithm

    Directory of Open Access Journals (Sweden)

    Suresh Kumar Sudabattula

    2016-09-01

    Full Text Available With increased demand of electrical energy, limited availability of fossil fuels and environmental concerns, it is necessary to consider renewable energy based generation in a power system network. Optimal allocation of renewable based distributed generators in the distribution system is a challenging task in the recent years. In this paper an effective technique is proposed for optimal allocation of solar based distributed generators in the distribution network using a Bat algorithm (BA is presented. The objective is to minimize power loss of radial distribution system. Different operating constraints related to the distribution network are considered. The stochastic nature of solar irradiance is modeled by using suitable probability distribution function (PDF. The proposed method is tested and validated on IEEE 33 bus test system.

  7. Different Random Distributions Research on Logistic-Based Sample Assumption

    Directory of Open Access Journals (Sweden)

    Jing Pan

    2014-01-01

    Full Text Available Logistic-based sample assumption is proposed in this paper, with a research on different random distributions through this system. It provides an assumption system of logistic-based sample, including its sample space structure. Moreover, the influence of different random distributions for inputs has been studied through this logistic-based sample assumption system. In this paper, three different random distributions (normal distribution, uniform distribution, and beta distribution are used for test. The experimental simulations illustrate the relationship between inputs and outputs under different random distributions. Thereafter, numerical analysis infers that the distribution of outputs depends on that of inputs to some extent, and this assumption system is not independent increment process, but it is quasistationary.

  8. Real-time Distributed Economic Dispatch forDistributed Generation Based on Multi-Agent System

    DEFF Research Database (Denmark)

    Luo, Kui; Wu, Qiuwei; Nielsen, Arne Hejde

    2015-01-01

    The distributed economic dispatch for distributed generation is formulated as a optimization problem with equality and inequality constraints. An effective distributed approach based on multi-agent system is proposed for solving the economic dispatch problem in this paper. The proposed approach...... distributed manner with local computation and communication among neighboring agent. The feasibility and effectiveness of this approach is demonstrated by a numerical test system....

  9. Web Based Distributed Coastal Image Analysis System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project develops Web based distributed image analysis system processing the Moderate Resolution Imaging Spectroradiometer (MODIS) data to provide decision...

  10. Cognitive Radio Engine Model Utilizing Soft Fusion Based Genetic Algorithm for Cooperative Spectrum Optimization

    Directory of Open Access Journals (Sweden)

    Kamal Hossain

    2013-04-01

    Full Text Available Cognitive radio (CR is to detect the presence of primary users (PUs reliably in order to reduce theinterference to licensed communications. Genetic algorithms (GAs are well suited for CR optimizationproblems to increase efficiency of bandwidth utilization by manipulating its unused portions of theapparent spectrum. In this paper, a binary genetic algorithm (BGA-based soft fusion (SF scheme forcooperative spectrum sensing in cognitive radio network is proposed to improve detection performance andbandwidth utilization. The BGA-based optimization method is implemented at the fusion centre of a linearSF scheme to optimize the weighting coefficients vector to maximize global probability of detectionperformance. Simulation results and analyses confirm that the proposed scheme meets real timerequirements of cognitive radio spectrum sensing and it outperforms conventional natural deflectioncoefficient- (NDC-, modified deflection coefficient- (MDC-, maximal ratio combining- (MRC- and equalgain combining- (EGC- based SDF schemes as well as the OR-rule based hard decision fusion (HDF. Thepropose BGA scheme also converges fast and achieves the optimum performance, which means that BGAbasedmethod is efficient and quite stable also.

  11. Access Control for Agent-based Computing: A Distributed Approach.

    Science.gov (United States)

    Antonopoulos, Nick; Koukoumpetsos, Kyriakos; Shafarenko, Alex

    2001-01-01

    Discusses the mobile software agent paradigm that provides a foundation for the development of high performance distributed applications and presents a simple, distributed access control architecture based on the concept of distributed, active authorization entities (lock cells), any combination of which can be referenced by an agent to provide…

  12. A Ground-based Optical Transmission Spectrum of WASP-6b

    CERN Document Server

    Jordán, Andrés; Rabus, Markus; Eyheramendy, Susana; Sing, David K; Désert, Jean-Michel; Bakos, Gáspár Á; Fortney, Jonathan J; López-Morales, Mercedes; Maxted, Pierre F L; Triaud, Amaury H M J; Szentgyorgyi, Andrew

    2013-01-01

    We present a ground based optical transmission spectrum of the inflated sub-Jupiter mass planet WASP-6b. The spectrum was measured in twenty spectral channels from 480 nm to 860nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the IMACS spectrograph on the Baade telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars, and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured transmission spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensat...

  13. A real-time spectrum acquisition system design based on quantum dots-quantum well detector

    Science.gov (United States)

    Zhang, S. H.; Guo, F. M.

    2016-01-01

    In this paper, we studied the structure characteristics of quantum dots-quantum well photodetector with response wavelength range from 400 nm to 1000 nm. It has the characteristics of high sensitivity, low dark current and the high conductance gain. According to the properties of the quantum dots-quantum well photodetectors, we designed a new type of capacitive transimpedence amplifier (CTIA) readout circuit structure with the advantages of adjustable gain, wide bandwidth and high driving ability. We have implemented the chip packaging between CTIA-CDS structure readout circuit and quantum dots detector and tested the readout response characteristics. According to the timing signals requirements of our readout circuit, we designed a real-time spectral data acquisition system based on FPGA and ARM. Parallel processing mode of programmable devices makes the system has high sensitivity and high transmission rate. In addition, we realized blind pixel compensation and smoothing filter algorithm processing to the real time spectrum data by using C++. Through the fluorescence spectrum measurement of carbon quantum dots and the signal acquisition system and computer software system to realize the collection of the spectrum signal processing and analysis, we verified the excellent characteristics of detector. It meets the design requirements of quantum dot spectrum acquisition system with the characteristics of short integration time, real-time and portability.

  14. [Study on spectrum analysis of X-ray based on rotational mass effect in special relativity].

    Science.gov (United States)

    Yu, Zhi-Qiang; Xie, Quan; Xiao, Qing-Quan

    2010-04-01

    Based on special relativity, the formation mechanism of characteristic X-ray has been studied, and the influence of rotational mass effect on X-ray spectrum has been given. A calculation formula of the X-ray wavelength based upon special relativity was derived. Error analysis was carried out systematically for the calculation values of characteristic wavelength, and the rules of relative error were obtained. It is shown that the values of the calculation are very close to the experimental values, and the effect of rotational mass effect on the characteristic wavelength becomes more evident as the atomic number increases. The result of the study has some reference meaning for the spectrum analysis of characteristic X-ray in application.

  15. The Diagnosis of Components Information Distribution of Wheat Seedlings Based on the Hyperspectral Imaging

    Directory of Open Access Journals (Sweden)

    Qiong Wu

    2012-08-01

    Full Text Available It is adopted mostly of the non-imaging spectrometer in current crop seedling monitoring, this method is greatly interfered by the soil background, makes it difficult to analyze the partial area nutritional status of the seedlings. In this study, we took advantage of merging the image with spectrum of the imaging spectrometer, to analyze the canopy, individuals, different size of leaves, characteristics of different regions of the wheat seedlings under the condition of salt stress, to diagnose the distribution of its chlorophyll composition information. We collected the imaging spectrum of 126 wheat samples in the wavelength range of 400 ~1000 nm, selected the average spectrum, exerted Correlation Analysis on the spectrum of wheat seedlings with the SPAD value, It could be seen that the biggest absolute value of the correlation coefficient was at 693 nm, which was considered as the characteristics wavelength of wheat seedlings. To establish the linear regression model using this wavelength and substituted 1the reflectance data of each point into the model, then we got the SPAD value of each point, to form the relative content distribution map of chlorophyll, whereby to diagnose the distribution of seedlings component. The results showed that: Hyper spectral imaging could reflect the reflectance differences of wheat seedlings under different salt stress treatments, through extracting the spectral reflectance curve leaves of single wheat seedlings in different parts of the different leaves and single leaf base, the midst of leaves and tip in the plant, from the results of filling map we could intuitively see the leaves’ chlorophyll distribution in different parts. It indicated that hyper spectral imaging can characterize the seedlings situation of different plants, also could characterize the characteristics of different district of leaves. The results indicated that hyper spectral imaging were suitable for the non-invasive detection of

  16. Dental care protocol based on visual supports for children with autism spectrum disorders

    OpenAIRE

    2015-01-01

    Background Subjects with Autism Spectrum Disorders (ASDs) have often difficulties to accept dental treatments. The aim of this study is to propose a dental care protocol based on visual supports to facilitate children with ASDs to undergo to oral examination and treatments. Material and Methods 83 children (age range 6-12 years) with a signed consent form were enrolled; intellectual level, verbal fluency and cooperation grade were evaluated. Children were introduced into a four stages path in...

  17. Distributed Prognostics Based on Structural Model Decomposition

    Data.gov (United States)

    National Aeronautics and Space Administration — Within systems health management, prognostics focuses on predicting the remaining useful life of a system. In the model-based prognostics paradigm, physics-based...

  18. Energy-Based Collaborative Spectrum Sensing for Cognitive UWB Impulse Radio

    Institute of Scientific and Technical Information of China (English)

    Wei-Chiang Wu; Chun-Te Wu

    2015-01-01

    This paper focuses on the issue of collaborative spectrum sensing in cognitive ultra wideband (CUWB) impulse radio. We employ energy-based signal detection method and apply the Neyman-Pearson (NP) decision rule to determine the optimum threshold. Two cooperative spectrum sensing schemes are developed in this paper. The decision fusion scheme is based on hard decision, in which each cooperating cognitive user (CU) sends its own local decision to the fusion center (FC). The FC then makes a final decision according to the majority voting rule. Alternatively, the data fusion scheme is based on soft decision, in which each local CU sends its observed value directly to the FC. The FC combines these values, compares to a threshold and then makes the final decision. The performances of both schemes are studied by using analytical tools and computer simulations. The receiver operating characteristics (ROC), which reveal the probability of detection versus false-alarm curve, are employed to evaluate the system performance under different scenarios.Simulation results demonstrate that the data fusion scheme outperforms the decision fusion scheme and verify that the collaborative spectrum sensing has practical importance in CUWB networks.

  19. Asymptotic distributions in the projection pursuit based canonical correlation analysis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, associations between two sets of random variables based on the projection pursuit (PP) method are studied. The asymptotic normal distributions of estimators of the PP based canonical correlations and weighting vectors are derived.

  20. 认知无线电网络中分布式频谱分配策略的研究%Study of Distributed Spectrum Allocation Strategy in Cognitive Radio Network

    Institute of Scientific and Technical Information of China (English)

    胡小辉; 许力; 黄川

    2013-01-01

    It is of great significance for improving spectrum resources utilization rate to study the distributed strategy of spectrum re sources allocation in Cognitive Radio Network (CRN). Based on the dynamic bargaining game model, benefits model is built for the primary user and secondary user in CRN. And a kind of effectively bargaining game based distributed spectrum allocation strategy (BG-DSAS) is proposed based on the benefits model. The strategies are analyzed when two users and N users, and the algorithm process of BG-DSAS is provided. The simulation experiment verifies the rationality and efficiency of the policy from several aspects.%研究认知无线电网络中的分布式频谱资源分配策略对提高频谱资源利用率具有重要的意义.基于动态议价博弈模型并结合最佳单位带宽定价,对认知无线电网络中主用户和认知用户的收益进行建模,在此基础上提出一种高效的基于议价博弈的分布式频谱分配策略(Bargaining Game-Distributed Spectrum Allocation Strategy,BG-DSAS).分别分析了两用户和N用户条件下的策略方案,并给出了实现BG-DSAS频谱分配策略的算法流程.仿真实验从多个角度分析了策略的合理性和有效性.

  1. Robust Ultrasonic Waveguide Based Distributed Temperature Sensing

    Science.gov (United States)

    Periyannan, S.; Rajagopal, P.; Balasubramaniam, K.

    This is a novel technique for distributed temperature measurements, using single robust ultrasonic wire or strip-like waveguides, special embodiments in the form of Helical or Spiral configurations that can cover large area/volume in enclosed regions. Such distributed temperature sensing has low cost applications in the long term monitoring critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks, buildings for fire, etc. The range of temperatures that can be measured are from very low to elevated temperatures. The transduction is performed using Piezo-electric crystals that are bonded to one end of the waveguide which acts as both transmitter and receivers. The wires will have periodic reflector embodiments (bends, gratings, etc.) that allow reflections of an input ultrasonic wave, in a pulse echo mode, back to the crystal. Using the time of fight (TOF) variations at the multiple predefined reflector locations, the measured temperatures are mapped with multiple thermocouples. Using either the L(0,1) or the T(0,1)modes, or simultaneously, measurements other than temperature may also be included. This paper will describe the demonstration of this technology using a 0.5 MHz longitudinal piezo-crystal for transmitting and receiving the L (0, 1) mode through the special form of waveguide at various temperatures zones.

  2. RF Spectrum Sensing Based on an Overdamped Nonlinear Oscillator Ring for Cognitive Radios

    Science.gov (United States)

    Tang, Zhi-Ling; Li, Si-Min; Yu, Li-Juan

    2016-01-01

    Existing spectrum-sensing techniques for cognitive radios require an analog-to-digital converter (ADC) to work at high dynamic range and a high sampling rate, resulting in high cost. Therefore, in this paper, a spectrum-sensing method based on a unidirectionally coupled, overdamped nonlinear oscillator ring is proposed. First, the numerical model of such a system is established based on the circuit of the nonlinear oscillator. Through numerical analysis of the model, the critical condition of the system’s starting oscillation is determined, and the simulation results of the system’s response to Gaussian white noise and periodic signal are presented. The results show that once the radio signal is input into the system, it starts oscillating when in the critical region, and the oscillating frequency of each element is fo/N, where fo is the frequency of the radio signal and N is the number of elements in the ring. The oscillation indicates that the spectrum resources at fo are occupied. At the same time, the sampling rate required for an ADC is reduced to the original value, 1/N. A prototypical circuit to verify the functionality of the system is designed, and the sensing bandwidth of the system is measured. PMID:27294928

  3. A distributed data base management system. [for Deep Space Network

    Science.gov (United States)

    Bryan, A. I.

    1975-01-01

    Major system design features of a distributed data management system for the NASA Deep Space Network (DSN) designed for continuous two-way deep space communications are described. The reasons for which the distributed data base utilizing third-generation minicomputers is selected as the optimum approach for the DSN are threefold: (1) with a distributed master data base, valid data is available in real-time to support DSN management activities at each location; (2) data base integrity is the responsibility of local management; and (3) the data acquisition/distribution and processing power of a third-generation computer enables the computer to function successfully as a data handler or as an on-line process controller. The concept of the distributed data base is discussed along with the software, data base integrity, and hardware used. The data analysis/update constraint is examined.

  4. Load balancing in distributed framework for frequency based thread pools

    Directory of Open Access Journals (Sweden)

    Sheraz Ahmad

    2016-12-01

    Full Text Available The consequence of load balancing algorithms on a thread pool framework name is distributed load balancing frequency based optimization scheme (LDFBOS to increase its execution. Load balancing in distributed frequency based thread pool scheme is residential towards the ground of synchronizing overhead crude named LDFBOS in Java that slows down its execution due to framework exchange and synchronizing overhead in nodes, we are demonstrating the contrive and execution of load balancing in distributed frequency based thread pool LDFBOS to does usage from distributed in frequency based thread pool (DFBOS, synchronizing primitives that propose benefits of significant scalable moreover, dynamism. We have got resembled the execution of some schemes by Thread Pool Tester which is a Java application simulator and the consequence have demonstrated that load balancing in distributed frequency based thread pool LDFBOS exceeds preceding DFBOS scheme.

  5. A distributed data base management system. [for Deep Space Network

    Science.gov (United States)

    Bryan, A. I.

    1975-01-01

    Major system design features of a distributed data management system for the NASA Deep Space Network (DSN) designed for continuous two-way deep space communications are described. The reasons for which the distributed data base utilizing third-generation minicomputers is selected as the optimum approach for the DSN are threefold: (1) with a distributed master data base, valid data is available in real-time to support DSN management activities at each location; (2) data base integrity is the responsibility of local management; and (3) the data acquisition/distribution and processing power of a third-generation computer enables the computer to function successfully as a data handler or as an on-line process controller. The concept of the distributed data base is discussed along with the software, data base integrity, and hardware used. The data analysis/update constraint is examined.

  6. Automatic DGD and GVD compensation at 640 Gb/s based on scalar radio-frequency spectrum measurement

    DEFF Research Database (Denmark)

    Paquot, Yvan; Schröder, Jochen; Palushani, Evarist;

    2013-01-01

    of separate GVD and DGD compensators using an impairment monitor based on an integrated all-optical radio-frequency (RF) spectrum analyzer. We show that low-bandwidth measurement of only a single tone in the RF spectrum is sufficient for automatic compensation for multiple degrees of freedom using...

  7. Multi-agent based controller for islanding operation of active distribution networks with distributed generation

    DEFF Research Database (Denmark)

    Cha, Seung-Tae; Wu, Qiuwei; Østergaard, Jacob

    2011-01-01

    are important, and the overall network synchronism must be ensured in the islanded distribution system. In this paper, a multi-agent based controller has been proposed to stabilize the frequency and voltages of an active distribution system after it enters into the islanding operation mode. The modified IEEE 9......-bus system was used to investigate the dynamic and steady state performance of the active distribution system during islanding operation. Case studies have been carried out using the Real-Time Digital Simulator (RTDS) based simulation platform. Case study results show that the proposed multi-agent......The increasing amount of distributed generation (DG) in today’s highly complex restructured power networks gives more options for distribution system operators (DSOs) under contingency conditions. A low voltage distribution network with a large amount of DG can be operated as an islanded system...

  8. Vehicle Unpaved Road Response Spectrum Acquisition Based on Accelerometer and GPS Data

    Directory of Open Access Journals (Sweden)

    Yao Guo

    2012-07-01

    Full Text Available This paper describes a response acquisition system composed of some spindle accelerometers and a time synchronized on-board GPS receiver developed in order to collect the dynamic response of vehicle riding on an unpaved road. A method of time-space conversion for calculating the response spectrum is proposed to eliminate the adverse effect of time-varying speed, based on the transform from the equitime sampled spindle acceleration responses to equidistance sampling. By using two groups of independent distance histories acquired from GPS, a method called long-range error correction is proposed to improve the accuracy of the vehicle’s distance information, which is critical for the time-space conversion. The accuracy and limitations of the system have been analyzed, and its validity has been verified by implementing the system on a wheel loader for road response spectrum measuring. This paper offers a practical approach to obtaining unpaved road response spectra for durability road simulation.

  9. Analytical and Learning-Based Spectrum Sensing Time Optimization in Cognitive Radio Systems

    CERN Document Server

    Ghadikolaei, Hossein Shokri; Nasiri-Kenari, Masoumeh

    2011-01-01

    Powerful spectrum sensing schemes enable cognitive radios (CRs) to find transmission opportunities in spectral resources allocated exclusively to the primary users. In this paper, maximizing the average throughput of a secondary user by optimizing its spectrum sensing time is formulated assuming that a prior knowledge of the presence and absence probabilities of the primary users is available. The energy consumed for finding a transmission opportunity is evaluated and a discussion on the impact of the number of the primary users on the secondary user throughput and consumed energy is presented. In order to avoid the challenges associated with the analytical method, as a second solution, a systematic neural network-based sensing time optimization approach is also proposed in this paper. The proposed adaptive scheme is able to find the optimum value of the channel sensing time without any prior knowledge or assumption about the wireless environment. The structure, performance, and cooperation of the artificial ...

  10. Transit Time Distribution based on the ECCO-JPL Ocean Data Assimilation

    Science.gov (United States)

    Ito, Takamitsu; Wang, Ou

    2017-03-01

    Oceanic water mass is a mixture of waters with varying ages, and the Transit Time Distribution (TTD) measures its age spectrum. We construct a model-based TTD using the data-constrained circulation fields from the ECCO-JPL Ocean Data Assimilation, and test it against the observed and directly simulated distribution of pCFC-11 from the Pacific and Atlantic basins. The ECCO-JPL circulation provides overall reliable estimates of the upper ocean ventilation rates suitable for biogeochemical studies. Observed distributions of pCFC-11 in the upper ocean thermocline are well reproduced by the convolution integral of the model-based TTD (mean bias 0.87) but there are significant regional biases in particular near the base of the thermocline and in the deep water formation regions. The model underestimates the deep pCFC-11 (> 2000 m) in the North Atlantic and in the Southern Ocean. The ratio between the mean and the spread of the age spectrum (Γ/Δ) is close to unity (mean = 1.04, median = 0.99) in the ventilated thermocline of the Pacific basin but there are significant regional variations of the ratio.

  11. Magnetic Tunnel Junction-Based On-Chip Microwave Phase and Spectrum Analyzer

    Science.gov (United States)

    Fan, Xin; Chen, Yunpeng; Xie, Yunsong; Kolodzey, James; Wilson, Jeffrey D.; Simons, Rainee N.; Xiao, John Q.

    2014-01-01

    A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance, the frequency of an incident microwave is directly determined. In addition, by integrating a mixer circuit, the MTJ-based microwave detector can also determine the relative phase between two microwave signals. Thus, the MTJbased microwave detector can be used as an on-chip microwave phase and spectrum analyzer.

  12. Distribution and antimicrobial susceptibility profile of extended-spectrum β-lactamase-producing Proteus mirabilis strains recently isolated in Japan.

    Science.gov (United States)

    Kanayama, Akiko; Kobayashi, Intetsu; Shibuya, Kazutoshi

    2015-02-01

    Here we report on the prevalence of extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis from a nationwide antimicrobial resistance survey in different geographical regions of Japan. A total of 799 P. mirabilis isolates recovered between July 2009 and June 2010 from 314 healthcare facilities were characterised according to ESBL production, source, location and antimicrobial susceptibility pattern. ESBL production was found in 364 (45.6%) of the isolates, among which 354 (97.3%) produced CTX-M-2 group β-lactamases. Of the 349 ESBL-producing isolates in which the inpatient or outpatient status of the source was known, 324 (92.8%) were from inpatients and 25 (7.2%) were from outpatients (PESBL-producers generated a distribution of PFGE patterns into 21 groups. Genetic relatedness was seen among isolates within a region, which is consistent with horizontal transmission. With respect to the frequency of ESBL-producers by specimen source, 12/14 (85.7%) central venous catheter specimens yielded ESBL-producing P. mirabilis compared with 159/405 (39.3%), 119/209 (56.9%), 42/77 (54.5%) and 20/49 (40.8%), respectively, for isolates from urine, sputum, decubitus ulcer and wound specimens. Among the ESBL-producers, non-susceptibility to ciprofloxacin was found in 74.2% of the ESBL-producing isolates compared with 17.7% of the ESBL-non-producing isolates. These results show that approximately one-half of the P. mirabilis isolates from clinical specimens in Japan are ESBL-producers and that the potential for concomitant fluoroquinolone resistance must also be considered.

  13. Distributed Maximality based CTL Model Checking

    Directory of Open Access Journals (Sweden)

    Djamel Eddine Saidouni

    2010-05-01

    Full Text Available In this paper we investigate an approach to perform a distributed CTL Model checker algorithm on a network of workstations using Kleen three value logic, the state spaces is partitioned among the network nodes, We represent the incomplete state spaces as a Maximality labeled Transition System MLTS which are able to express true concurrency. we execute in parallel the same algorithm in each node, for a certain property on an incomplete MLTS , this last compute the set of states which satisfy or which if they fail are assigned the value .The third value mean unknown whether true or false because the partial state space lacks sufficient information needed for a precise answer concerning the complete state space .To solve this problem each node exchange the information needed to conclude the result about the complete state space. The experimental version of the algorithm is currently being implemented using the functional programming language Erlang.

  14. Next Generation Multimedia Distributed Data Base Systems

    Science.gov (United States)

    Pendleton, Stuart E.

    1997-01-01

    The paradigm of client/server computing is changing. The model of a server running a monolithic application and supporting clients at the desktop is giving way to a different model that blurs the line between client and server. We are on the verge of plunging into the next generation of computing technology--distributed object-oriented computing. This is not only a change in requirements but a change in opportunities, and requires a new way of thinking for Information System (IS) developers. The information system demands caused by global competition are requiring even more access to decision making tools. Simply, object-oriented technology has been developed to supersede the current design process of information systems which is not capable of handling next generation multimedia.

  15. Reliability Distribution of Numerical Control Lathe Based on Correlation Analysis

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Qi; Guixiang Shen; Yingzhi Zhang; Shuguang Sun; Bingkun Chen

    2016-01-01

    Combined Reliability distribution with correlation analysis, a new method has been proposed to make Reliability distribution where considering the elements about structure correlation and failure correlation of subsystems. Firstly, we make a sequence for subsystems by means of TOPSIS which comprehends the considerations of Reliability allocation, and introducing a Copula connecting function to set up a distribution model based on structure correlation, failure correlation and target correlation, and then acquiring reliability target area of all subsystems by Matlab. In this method, not only the traditional distribution considerations are concerned, but also correlation influences are involved, to achieve supplementing information and optimizing distribution.

  16. Parameter estimation of stable distribution based on zero - order statistics

    Science.gov (United States)

    Chen, Jian; Chen, Hong; Cai, Xiaoxia; Weng, Pengfei; Nie, Hao

    2017-08-01

    With the increasing complexity of the channel, there are many impulse noise signals in the real channel. The statistical properties of such processes are significantly deviated from the Gaussian distribution, and the Alpha stable distribution provides a very useful theoretical tool for this process. This paper focuses on the parameter estimation method of the Alpha stable distribution. First, the basic theory of Alpha stable distribution is introduced. Then, the concept of logarithmic moment and geometric power are proposed. Finally, the parameter estimation of Alpha stable distribution is realized based on zero order statistic (ZOS). This method has better toughness and precision.

  17. Traffic Flow Density Distribution Based on FEM

    Science.gov (United States)

    Ma, Jing; Cui, Jianming

    In analysis of normal traffic flow, it usually uses the static or dynamic model to numerical analyze based on fluid mechanics. However, in such handling process, the problem of massive modeling and data handling exist, and the accuracy is not high. Finite Element Method (FEM) is a production which is developed from the combination of a modern mathematics, mathematics and computer technology, and it has been widely applied in various domain such as engineering. Based on existing theory of traffic flow, ITS and the development of FEM, a simulation theory of the FEM that solves the problems existing in traffic flow is put forward. Based on this theory, using the existing Finite Element Analysis (FEA) software, the traffic flow is simulated analyzed with fluid mechanics and the dynamics. Massive data processing problem of manually modeling and numerical analysis is solved, and the authenticity of simulation is enhanced.

  18. Clinical Spectrum, Risk Factors, and Behavioral Abnormalities among Dementia Subtypes in a North Indian Population: A Hospital-Based Study

    Directory of Open Access Journals (Sweden)

    Suman Kushwaha

    2017-07-01

    Full Text Available Background: As variability in the clinical profile of dementia subtypes had been reported with regional differences across the world, we conducted a retrospective hospital-based study in a North Indian population. Methods: We retrieved patient records from 2007 to 2014 for details of clinical evaluation, diagnosis, neuroimaging, biochemical investigations, and follow-up of 1,876 patients with dementia (PwD, and the data were analyzed using descriptive statistics. Results: Of the total PwD, Alzheimer disease (AD accounted for 30% followed by vascular dementia (VaD 26%, mixed dementia (MD 21%, Parkinson-related dementia 11%, frontotemporal dementia (FTD 7%, and infective dementia 5%. Of all PwD excluding the infective group (n = 1,777, 63% were men, 39% were from rural areas, 87% had behavioral abnormalities along with cognitive deficits, and 73% had impaired ADLs. Among dementia subtypes, a positive family history, cardiovascular and metabolic risk factors, and behavioral abnormalities were found to be distributed. However, there existed a predominance of specific behavioral pattern in each subtype. The mean duration of follow-up varied from 2.9 ± 2.3 (VaD to 3.6 ± 2.1 (AD and greater than 30% were found to be stable on treatment (except in dementia with Lewy body. Conclusions: This large hospital-based study provides a distribution pattern and clinical spectrum of dementia subtypes in a North Indian population.

  19. A ground-based transmission spectrum of the super-Earth exoplanet GJ 1214b.

    Science.gov (United States)

    Bean, Jacob L; Kempton, Eliza Miller-Ricci; Homeier, Derek

    2010-12-02

    In contrast to planets with masses similar to that of Jupiter and higher, the bulk compositions of planets in the so-called super-Earth regime (masses 2-10 times that of the Earth) cannot be uniquely determined from a measurement of mass and radius alone. For these planets, there is a degeneracy between the mass and composition of both the interior and a possible atmosphere in theoretical models. The recently discovered transiting super-Earth exoplanet GJ 1214b is one example of this problem. Three distinct models for the planet that are consistent with its mass and radius have been suggested. Breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition. Here we report a ground-based measurement of the transmission spectrum of GJ 1214b between wavelengths of 780 and 1,000 nm. The lack of features in this spectrum rules out (at 4.9σ confidence) cloud-free atmospheres composed primarily of hydrogen. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at the observed wavelengths at pressures less than 200 mbar. Alternatively, the featureless transmission spectrum is also consistent with the presence of a dense, water vapour atmosphere.

  20. Band selection method based on spectrum difference in targets of interest in hyperspectral imagery

    Science.gov (United States)

    Zhang, Xiaohan; Yang, Guang; Yang, Yongbo; Huang, Junhua

    2016-10-01

    While hyperspectral data shares rich spectrum information, it has numbers of bands with high correlation coefficients, causing great data redundancy. A reasonable band selection is important for subsequent processing. Bands with large amount of information and low correlation should be selected. On this basis, according to the needs of target detection applications, the spectral characteristics of the objects of interest are taken into consideration in this paper, and a new method based on spectrum difference is proposed. Firstly, according to the spectrum differences of targets of interest, a difference matrix which represents the different spectral reflectance of different targets in different bands is structured. By setting a threshold, the bands satisfying the conditions would be left, constituting a subset of bands. Then, the correlation coefficients between bands are calculated and correlation matrix is given. According to the size of the correlation coefficient, the bands can be set into several groups. At last, the conception of normalized variance is used on behalf of the information content of each band. The bands are sorted by the value of its normalized variance. Set needing number of bands, and the optimum band combination solution can be get by these three steps. This method retains the greatest degree of difference between the target of interest and is easy to achieve by computer automatically. Besides, false color image synthesis experiment is carried out using the bands selected by this method as well as other 3 methods to show the performance of method in this paper.

  1. Assessment of Foetal Exposure to the Homogeneous Magnetic Field Harmonic Spectrum Generated by Electricity Transmission and Distribution Networks

    Directory of Open Access Journals (Sweden)

    Serena Fiocchi

    2015-04-01

    Full Text Available During the last decades studies addressing the effects of exposure to Extremely Low Frequency Electromagnetic Fields (ELF-EMF have pointed out a possible link between those fields emitted by power lines and childhood leukaemia. They have also stressed the importance of also including in the assessment the contribution of frequency components, namely harmonics, other than the fundamental one. Based on the spectrum of supply voltage networks allowed by the European standard for electricity quality assessment, in this study the exposure of high-resolution three-dimensional models of foetuses to the whole harmonic content of a uniform magnetic field with a fundamental frequency of 50 Hz, was assessed. The results show that the main contribution in terms of induced electric fields to the foetal exposure is given by the fundamental frequency component. The harmonic components add some contributions to the overall level of electric fields, however, due to the extremely low permitted amplitude of the harmonic components with respect to the fundamental, their amplitudes are low. The level of the induced electric field is also much lower than the limits suggested by the guidelines for general public exposure, when the amplitude of the incident magnetic field is set at the maximum permitted level.

  2. Assessment of foetal exposure to the homogeneous magnetic field harmonic spectrum generated by electricity transmission and distribution networks.

    Science.gov (United States)

    Fiocchi, Serena; Liorni, Ilaria; Parazzini, Marta; Ravazzani, Paolo

    2015-04-01

    During the last decades studies addressing the effects of exposure to Extremely Low Frequency Electromagnetic Fields (ELF-EMF) have pointed out a possible link between those fields emitted by power lines and childhood leukaemia. They have also stressed the importance of also including in the assessment the contribution of frequency components, namely harmonics, other than the fundamental one. Based on the spectrum of supply voltage networks allowed by the European standard for electricity quality assessment, in this study the exposure of high-resolution three-dimensional models of foetuses to the whole harmonic content of a uniform magnetic field with a fundamental frequency of 50 Hz, was assessed. The results show that the main contribution in terms of induced electric fields to the foetal exposure is given by the fundamental frequency component. The harmonic components add some contributions to the overall level of electric fields, however, due to the extremely low permitted amplitude of the harmonic components with respect to the fundamental, their amplitudes are low. The level of the induced electric field is also much lower than the limits suggested by the guidelines for general public exposure, when the amplitude of the incident magnetic field is set at the maximum permitted level.

  3. Oligomers Based on a Weak Hydrogen Bond Network: the Rotational Spectrum of the Tetramer of Difluoromethane

    Science.gov (United States)

    Feng, Gang; Evangelisti, Luca; Caminati, Walther; Cacelli, Ivo; Carbonaro, Laura; Prampolini, Giacomo

    2013-06-01

    Following the investigation of the rotational spectra of three conformers (so-called ``book'', ``prism'' and ``cage'') of the water hexamer, and of some other water oligomers, we report here the rotational spectrum of the tetramer of a freon molecule. The pulse jet Fourier transform microwave (pj-FTMW) spectrum of an isomer of the difluoromethane tetramer has been assigned. This molecular system is made of units of a relatively heavy asymmetric rotor, held together by a network of weak hydrogen bonds. The search of the rotational spectrum has been based on a high-level reference method, the CCSD(T)/CBS protocol. It is interesting to outline that the rotational spectrum of the water tetramer was not observed, probably because the minimum energy structures of this oligomer is effectively nonpolar in its ground states, or because of high energy tunnelling splittings. The rotational spectra of the monomer, dimer, trimer and tetramer of difluoromethane have been assigned in 1952, 1999, 2007, and 2013 (present work), with a decreasing time spacing between the various steps, looking then promising for a continuous and rapid extension of the size limits of molecular systems accessible to MW spectroscopy. C. Pérez, M. T. Muckle, D. P. Zaleski, N. A. Seifert, B. Temelso, G. C. Shields, Z. Kisiel, B. H. Pate, Science {336} (2012) 897. D. R. Lide, Jr., J. Am. Chem. Soc. {74} (1952) 3548. W. Caminati, S. Melandri, P. Moreschini, P. G. Favero, Angew. Chem. Int. Ed. {38} (1999) 2924. S. Blanco, S. Melandri, P. Ottaviani, W. Caminati, J. Am. Chem. Soc. {129} (2007) 2700.

  4. Spectrum Trading for Efficient Spectrum Utilization

    Directory of Open Access Journals (Sweden)

    Cong Xiong

    2014-04-01

    Full Text Available The conventional command and control based spectrum management has led to substantial underutilization of some spectrum bands while severely crowding others due to the uneven and dynamic needs that vary over time and at different locations. Spectrum trading has emerged as a promising management approach to substantially improve spectrum utilization and user experience in wireless communications by taking advantage of market-based mechanisms. This article presents an overview of spectrum trading, including the fundamental characteristics of spectrum trading markets, the state-of-the-art techniques for modeling and resolving various spectrum trading issues, and trading based dynamic spectrum sharing and access. Moreover, some open issues in spectrum trading are identified for future research in this area.

  5. A low complexity based spectrum management algorithm for ‘Near–Far’ problem in VDSL environment

    Directory of Open Access Journals (Sweden)

    Sunil Sharma

    2015-10-01

    Full Text Available In digital subscriber line (DSL system, crosstalk created by electromagnetic interference among twisted pairs degrades the system performance. Very high bit rate DSL (VDSL, utilizes higher bandwidth of copper cable for data transmission. During upstream transmission, a ‘Near–Far’ problem occurs in VDSL system. In this problem the far end crosstalk (FEXT is produced from near end user degrades the data rate achieved at the far end user. The effect of FEXT can be reduced by properly managing power spectral densities (PSD of transmitters of near and far users. This kind of power allocation is called dynamic spectrum management (DSM. In this paper, a new distributed DSM algorithm is proposed in which power from only those sub channels of near end user are reduced which create interference to far end user. This power back off strategy takes place with the help of power spectral density (PSD masks at interference creating sub channels of near end user. The simulation results of the proposed algorithm show an improvement in terms of data rate and approaches near to that of optimal spectrum balancing (OSB algorithm.

  6. Novel ensemble learning based on multiple section distribution in distributed environment

    Institute of Scientific and Technical Information of China (English)

    Fang Min

    2008-01-01

    Because most ensemble learning algorithms use the centralized model, and the training instances must be centralized on a single station, it is difficult to centralize the training data on a station. A distributed ensemble learning algorithm is proposed which has two kinds of weight genes of instances that denote the global distribution and the local distribution. Instead of the repeated sampling method in the standard ensemble learning,non-balance sampling from each station is used to train the base classifier set of each station. The concept of the effective nearby region for local integration classifier is proposed, and is used for the dynamic integration method of multiple classifiers in distributed environment. The experiments show that the ensemble learning algorithm in distributed environment proposed could reduce the time of training the base classifiers effectively, and ensure the classify performance is as same as the centralized learning method.

  7. Cloud-Based Distributed Control of Unmanned Systems

    Science.gov (United States)

    2015-04-01

    visualization of live data streams (i.e. video), but not on the storage and distribution mechanisms for the collected data. SSC Pacific’s UxV to the Cloud via...capable of storing and distributing the unmanned-vehicle collected data, cloud technologies (e.g. Accumulo) is chosen as the underlying data storage ...infrastructure. 3.1 Accumulo The cloud infrastructure is implemented using Accumulo, which is a distributed key-value based data storage and

  8. Arcade: A Web-Java Based Framework for Distributed Computing

    Science.gov (United States)

    Chen, Zhikai; Maly, Kurt; Mehrotra, Piyush; Zubair, Mohammad; Bushnell, Dennis M. (Technical Monitor)

    2000-01-01

    Distributed heterogeneous environments are being increasingly used to execute a variety of large size simulations and computational problems. We are developing Arcade, a web-based environment to design, execute, monitor, and control distributed applications. These targeted applications consist of independent heterogeneous modules which can be executed on a distributed heterogeneous environment. In this paper we describe the overall design of the system and discuss the prototype implementation of the core functionalities required to support such a framework.

  9. Routing Optimization Based on Taboo Search Algorithm for Logistic Distribution

    OpenAIRE

    Hongxue Yang; Lingling Xuan

    2014-01-01

    Along with the widespread application of the electronic commerce in the modern business, the logistic distribution has become increasingly important. More and more enterprises recognize that the logistic distribution plays an important role in the process of production and sales. A good routing for logistic distribution can cut down transport cost and improve efficiency. In order to cut down transport cost and improve efficiency, a routing optimization based on taboo search for logistic distr...

  10. Viewing the Web as a distributed knowledge base

    OpenAIRE

    Abiteboul, Serge; Antoine, Émilien; Stoyanovich, Julia

    2012-01-01

    International audience; This papers addresses the challenges faced by everyday Web users, who interact with inherently heterogeneous and distributed information. Managing such data is currently beyond the skills of casual users. We describe ongoing work that has as its goal the development of foundations for declarative distributed data management. In this approach, we see the Web as a knowledge base consisting of distributed logical facts and rules. Our objective is to enable automated reaso...

  11. A Logistics Distribution Plan Based on Cloud Computing

    OpenAIRE

    2013-01-01

    Aiming at the problems of lowing informatization level and degree of specialization, high consumption and low efficiency in logistics and distribution industry, this paper analyzes the characteristics of cloud computing and the actual needs of enterprise logistics. On this basis, depth study of the logistics and distribution needs of the cloud computing architecture, depth study of the cloud computing architecture in the logistics and distribution needs, and then propose a cloud-based modern ...

  12. Brief Report: Self-Based and Mechanical-Based Future Thinking in Children with Autism Spectrum Disorder.

    Science.gov (United States)

    Marini, A; Ferretti, F; Chiera, A; Magni, R; Adornetti, I; Nicchiarelli, S; Vicari, S; Valeri, G

    2016-10-01

    This brief report is a partial replication of the study by Jackson and Atance (J Dev Disabil 14:40-45, 2008) assessing nonverbal Self-based and Mechanical-based future thinking (FT) in children with Autism Spectrum Disorder (ASD). In a first step, these tasks were administered to 30 children with ASD. The two Self-based tasks were then modified as a verbal component could not be completely ruled out. Consequently, 77 children with ASD and 77 children with typical development received the modified Self-based FT tasks and the Mechanical-based FT tasks. We partially replicated the previous findings. Participants with ASD had impaired FT in both kinds of tasks and both groups performed better on tasks assessing Mechanical-based FT than Self-based FT. These results suggest that impairments of FT in ASD are not limited to Self-Projection.

  13. Nonlinear Time-Frequency Distributions of Spectrum Energy Operator in Large Vocabulary Mandarin Speaker Independent Speech Recognition System

    Institute of Scientific and Technical Information of China (English)

    Fadhil H. T. Al-dulaimy; WANG Zuoying(王作英)

    2003-01-01

    This work demonstrates the use of the nonlinear time-frequency distribution (NLTFD) of a discrete time energy operator (DTEO) based on amplitude modulation-frequency modulation demodulation techniques as a feature in speech recognition. The duration distribution based hidden Markov module in a speaker independent large vocabulary mandarin speech recognition system was reconstructed from the feature vectors in the front-end detection stage. The goal was to improve the performance of the existing system by combining new features to the baseline feature vector. This paper also deals with errors associated with using a pre-emphasis filter in the front end processing of the present scheme, which causes an increase in the noise energy at high frequencies above 4 kHz and in some cases degrades the recognition accuracy. The experimental results show that eliminating the pre-emphasis filters from the pre-processing stage and using NLTFD with compensated DTEO combined with Mel frequency cepstrum components give a 21.95% reduction in the relative error rate compared to the conventional technique with 25 candidates used in the test.

  14. Response of base isolation system excited by spectrum compatible ground motions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Han; Kim, Min Kyu; Choi, In Kil [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Structures in a nuclear power system are designed to be elastic even under an earthquake excitation. However a structural component such as an isolator shows inelastic behavior inherently. For the seismic assessment of nonlinear structures, the response history analysis should be performed. Especially for the performance based design, where the failure probability of a system needs to be evaluated, the variation of response should be evaluated. In this study, the spectrum compatible ground motions, the artificial ground motion and the modified ground motion, were generated. Using these ground motions, the variations of seismic responses of a simplified isolation system were evaluated.

  15. Filter-Bank-Based Narrowband Interference Detection and Suppression in Spread Spectrum Systems

    Directory of Open Access Journals (Sweden)

    Tobias Hidalgo Stitz

    2004-07-01

    Full Text Available A filter-bank-based narrowband interference detection and suppression method is developed and its performance is studied in a spread spectrum system. The use of an efficient, complex, critically decimated perfect reconstruction filter bank with a highly selective subband filter prototype, in combination with a newly developed excision algorithm, offers a solution with efficient implementation and performance close to the theoretical limit derived as a function of the filter bank stopband attenuation. Also methods to cope with the transient effects in case of frequency hopping interference are developed and the resulting performance shows only minor degradation in comparison to the stationary case.

  16. Automatic classification of thermal patterns in diabetic foot based on morphological pattern spectrum

    Science.gov (United States)

    Hernandez-Contreras, D.; Peregrina-Barreto, H.; Rangel-Magdaleno, J.; Ramirez-Cortes, J.; Renero-Carrillo, F.

    2015-11-01

    This paper presents a novel approach to characterize and identify patterns of temperature in thermographic images of the human foot plant in support of early diagnosis and follow-up of diabetic patients. Composed feature vectors based on 3D morphological pattern spectrum (pecstrum) and relative position, allow the system to quantitatively characterize and discriminate non-diabetic (control) and diabetic (DM) groups. Non-linear classification using neural networks is used for that purpose. A classification rate of 94.33% in average was obtained with the composed feature extraction process proposed in this paper. Performance evaluation and obtained results are presented.

  17. Mixture gas component concentration analysis based on support vector machine and infrared spectrum

    Institute of Scientific and Technical Information of China (English)

    Peng Bai; Junhua Liu

    2006-01-01

    @@ A novel quantitative analysis method of multi-component mixture gas concentration based on support vector machine (SVM) and spectroscopy is proposed. Through transformation of the kernel function, the seriously overlapped and nonlinear spectrum data are transformed in high-dimensional space, but the highdimensional data can be processed in the original space. Some factors, such as kernel function, range of the wavelength, and penalty coefficient, are discussed. This method is applied to the quantitative analysis of natural gas components concentration, and the component concentration maximal deviation is 2.28%.

  18. Modulation Transfer Function of a Gaussian Beam Based on the Generalized Modified Atmospheric Spectrum

    Directory of Open Access Journals (Sweden)

    Chao Gao

    2016-01-01

    Full Text Available This paper investigates the modulation transfer function of a Gaussian beam propagating through a horizontal path in weak-fluctuation non-Kolmogorov turbulence. Mathematical expressions are obtained based on the generalized modified atmospheric spectrum, which includes the spectral power law value of non-Kolmogorov turbulence, the finite inner and outer scales of turbulence, and other optical parameters of the Gaussian beam. The numerical results indicate that the atmospheric turbulence would produce less negative effects on the wireless optical communication system with an increase in the inner scale of turbulence. Additionally, the increased outer scale of turbulence makes a Gaussian beam influenced more seriously by the atmospheric turbulence.

  19. Principal component cluster analysis of ECG time series based on Lyapunov exponent spectrum

    Institute of Scientific and Technical Information of China (English)

    WANG Nai; RUAN Jiong

    2004-01-01

    In this paper we propose an approach of principal component cluster analysis based on Lyapunov exponent spectrum (LES) to analyze the ECG time series. Analysis results of 22 sample-files of ECG from the MIT-BIH database confirmed the validity of our approach. Another technique named improved teacher selecting student (TSS) algorithm is presented to analyze unknown samples by means of some known ones, which is of better accuracy. This technique combines the advantages of both statistical and nonlinear dynamical methods and is shown to be significant to the analysis of nonlinear ECG time series.

  20. Predicting speech intelligibility in adverse conditions: evaluation of the speech-based envelope power spectrum model

    DEFF Research Database (Denmark)

    2011-01-01

    The speech-based envelope power spectrum model (sEPSM) [Jørgensen and Dau (2011). J. Acoust. Soc. Am., 130 (3), 1475–1487] estimates the envelope signal-to-noise ratio (SNRenv) of distorted speech and accurately describes the speech recognition thresholds (SRT) for normal-hearing listeners...... conditions by comparing predictions to measured data from [Kjems et al. (2009). J. Acoust. Soc. Am. 126 (3), 1415-1426] where speech is mixed with four different interferers, including speech-shaped noise, bottle noise, car noise, and cafe noise. The model accounts well for the differences in intelligibility...

  1. An Applet-based Anonymous Distributed Computing System.

    Science.gov (United States)

    Finkel, David; Wills, Craig E.; Ciaraldi, Michael J.; Amorin, Kevin; Covati, Adam; Lee, Michael

    2001-01-01

    Defines anonymous distributed computing systems and focuses on the specifics of a Java, applet-based approach for large-scale, anonymous, distributed computing on the Internet. Explains the possibility of a large number of computers participating in a single computation and describes a test of the functionality of the system. (Author/LRW)

  2. Management of Globally Distributed Component-Based Software Development Projects

    NARCIS (Netherlands)

    J. Kotlarsky (Julia)

    2005-01-01

    textabstractGlobally Distributed Component-Based Development (GD CBD) is expected to become a promising area, as increasing numbers of companies are setting up software development in a globally distributed environment and at the same time are adopting CBD methodologies. Being an emerging area, the

  3. A Wireless Distributed Condition Monitoring System Based on Bluetooth Technology

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the discussion of bluetooth and network technology, this paper proposed an entire framework of a wireless distributed monitoring system by combining the characteristics of industry application. The feasibility of putting this kind of system in practice is discussed. The wireless distributed monitoring system can enhance the performance of condition monitoring more than the traditional one used now.

  4. FIPA agent based network distributed control system

    CERN Document Server

    Gyurjyan, V; Heyes, G; Jastrzembski, E; Timmer, C; Wolin, E

    2003-01-01

    A control system with the capabilities to combine heteregeneous control systems or processes into a uniform homogeneous environment is discussed. This dynamically extensible system is an example of the software system at the agent level of abstraction. This level of abstraction considers agents as atomic entities that communicate to implement the functionality of the control system. Agents engineering aspects are addressed by adopting the domain independent software standard, formulated by FIPA. Jade core Java classes are used as a FIPA specification implementation. A special, lightweight, XML RDFS based, control oriented, ontology markup language is developed to standardize the description of the arbitrary control system data processor. Control processes, described in this language, are integrated into the global system at runtime, without actual programming. Fault tolerance and recovery issues are also addressed.

  5. FIPA agent based network distributed control system

    Energy Technology Data Exchange (ETDEWEB)

    D. Abbott; V. Gyurjyan; G. Heyes; E. Jastrzembski; C. Timmer; E. Wolin

    2003-03-01

    A control system with the capabilities to combine heterogeneous control systems or processes into a uniform homogeneous environment is discussed. This dynamically extensible system is an example of the software system at the agent level of abstraction. This level of abstraction considers agents as atomic entities that communicate to implement the functionality of the control system. Agents' engineering aspects are addressed by adopting the domain independent software standard, formulated by FIPA. Jade core Java classes are used as a FIPA specification implementation. A special, lightweight, XML RDFS based, control oriented, ontology markup language is developed to standardize the description of the arbitrary control system data processor. Control processes, described in this language, are integrated into the global system at runtime, without actual programming. Fault tolerance and recovery issues are also addressed.

  6. A New Mechanism of Dynamic Spectrum Access Based on Restless Bandit Allocation Indices

    Directory of Open Access Journals (Sweden)

    Zhu Jiang

    2015-10-01

    Full Text Available Based on the theory of Restless Multi-Armed Bandit model, a novel mechanism of dynamic spectrum access was proposed for the problem that how to coordinate multi-user access multi-channel which were idle. Firstly, take care of the sensing error must be exist in the practical network, the Whittle index policy which can deal with sensing error effectively was derived, in this policy, the users achieved one belief value for every channel based on the historical experience accumulation and chose the channels, which was need to sense and access, by considering the reward of immediate and future based on the belief values. Secondly, this paper used the multi-bid auction algorithm to deal with the collision among secondary users when they select the channels to improve the spectrum utilization. The simulation results demonstrate that, in the same environment, the cognitive users with the proposed mechanism have higher throughtput than the mechanism without dealing with sensing error or without multi-bid.

  7. Parallel Harmony Search Based Distributed Energy Resource Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Ceylan, Oguzhan [ORNL; Liu, Guodong [ORNL; Tomsovic, Kevin [University of Tennessee, Knoxville (UTK)

    2015-01-01

    This paper presents a harmony search based parallel optimization algorithm to minimize voltage deviations in three phase unbalanced electrical distribution systems and to maximize active power outputs of distributed energy resources (DR). The main contribution is to reduce the adverse impacts on voltage profile during a day as photovoltaics (PVs) output or electrical vehicles (EVs) charging changes throughout a day. The IEEE 123- bus distribution test system is modified by adding DRs and EVs under different load profiles. The simulation results show that by using parallel computing techniques, heuristic methods may be used as an alternative optimization tool in electrical power distribution systems operation.

  8. Is video-based instruction effective in the rehabilitation of children with autism spectrum disorders?

    Science.gov (United States)

    Kagohara, Debora M

    2010-01-01

    To review intervention studies on the use of video-based instruction for teaching adaptive behaviours to children with autism spectrum disorders (ASD). Electronic and hand searches were conducted to identify intervention studies that focus on using video-based instruction to teach adaptive behaviours to children with ASD. Studies that met the inclusion criteria were summarized in terms of: (a) participants, (b) setting, (c) model type, (d) target skills, (e) intervention type, (f) design and (g) outcomes. Forty-four studies encompassing 49 experiments met the inclusion criteria. The studies targeted a range of adaptive behaviours and academic skills. Most studies reported positive results, but the certainty of evidence was not strong for all of the studies due to reliance on pre-experimental designs. The results from this review support the use of video-based instruction in the rehabilitation of children with ASD.

  9. A Danish population-based twin study on autism spectrum disorders

    DEFF Research Database (Denmark)

    Nordenbaek, Claudia; Jorgensen, Meta; Kyvik, Kirsten Ohm

    2014-01-01

    Genetic epidemiological studies of Autism Spectrum Disorders (ASDs) based on twin pairs ascertained from the population and thoroughly assessed to obtain a high degree of diagnostic validity are few. All twin pairs aged 3-14 years in the nationwide Danish Twin Registry were approached. A three...... based on 36 pairs. The probandwise concordance rate for ASD was 95.2 % in monozygotic (MZ) twins (n = 13 pairs) and 4.3 % in dizygotic (DZ) twins (n = 23 pairs). The high MZ and low DZ concordance rate support a genetic aetiology to ASDs....... standard" diagnostic research procedures including diagnostic interview, observation and cognitive examination. Classification was based on DSM-IV-TR criteria. The initial sample included 7,296 same-sexed twin pairs and, after two phases of screening and clinical assessment, the final calculations were...

  10. Magnetic Tunnel Junction-Based On-Chip Microwave Phase and Spectrum Analyzer

    Science.gov (United States)

    Fan, Xin; Chen, Yunpeng; Xie, Yunsong; Kolodzey, James; Wilson, Jeffrey D.; Simons, Rainee N.; Xiao, John Q.

    2014-01-01

    A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance, the frequency of an incident microwave is directly determined. In addition, by integrating a mixer circuit, the MTJ-based microwave detector can also determine the relative phase between two microwave signals. Thus, the MTJ-based microwave detector can be used as an on-chip microwave phase and spectrum analyzer.

  11. An Auction-Based Spectrum Leasing Mechanism for Mobile Macro-Femtocell Networks of IoT

    Science.gov (United States)

    Chen, Xin; Xing, Lei; Qiu, Tie; Li, Zhuo

    2017-01-01

    The Internet of Things (IoT) is a vision of the upcoming society. It can provide pervasive communication between two or more entities using 4G-LTE (Long Term Evolution) communication technology. In 4G-LTE networks, there are two important problems: helping manage the spectrum demands of IoT devices and achieving much more revenue with the limited resource. This paper proposes a pricing framework to investigate the spectrum leasing in mobile heterogeneous networks with single macrocell and multiple femtocells. We modeled the leasing procedure between the macrocell service provider (MSP) and femtocell holders (FHs) as an auction to motivate the MSP to lease its spectrum resource. All FHs act as the bidders, and the monopolist MSP acts as the auctioneer. In the auction, FHs submit their bids to rent the spectrum resource so that they can make a profit by selling it to their subscribers. The MSP determines the spectrum leasing amount and chooses the winning FHs by solving the dynamic programming-based 0–1 knapsack problem. In our proposed framework, we focus on the spectrum pricing strategy and revenue maximization of the MSP. The simulation results show that the proposed scheme provides effective motivation for the MSP to lease the spectrum to FHs, and both the MSP and FHs can benefit from spectrum leasing. PMID:28212317

  12. An Auction-Based Spectrum Leasing Mechanism for Mobile Macro-Femtocell Networks of IoT.

    Science.gov (United States)

    Chen, Xin; Xing, Lei; Qiu, Tie; Li, Zhuo

    2017-02-16

    The Internet of Things (IoT) is a vision of the upcoming society. It can provide pervasive communication between two or more entities using 4G-LTE (Long Term Evolution) communication technology. In 4G-LTE networks, there are two important problems: helping manage the spectrum demands of IoT devices and achieving much more revenue with the limited resource. This paper proposes a pricing framework to investigate the spectrum leasing in mobile heterogeneous networks with single macrocell and multiple femtocells. We modeled the leasing procedure between the macrocell service provider (MSP) and femtocell holders (FHs) as an auction to motivate the MSP to lease its spectrum resource. All FHs act as the bidders, and the monopolist MSP acts as the auctioneer. In the auction, FHs submit their bids to rent the spectrum resource so that they can make a profit by selling it to their subscribers. The MSP determines the spectrum leasing amount and chooses the winning FHs by solving the dynamic programming-based 0-1 knapsack problem. In our proposed framework, we focus on the spectrum pricing strategy and revenue maximization of the MSP. The simulation results show that the proposed scheme provides effective motivation for the MSP to lease the spectrum to FHs, and both the MSP and FHs can benefit from spectrum leasing.

  13. An Auction-Based Spectrum Leasing Mechanism for Mobile Macro-Femtocell Networks of IoT

    Directory of Open Access Journals (Sweden)

    Xin Chen

    2017-02-01

    Full Text Available The Internet of Things (IoT is a vision of the upcoming society. It can provide pervasive communication between two or more entities using 4G-LTE (Long Term Evolution communication technology. In 4G-LTE networks, there are two important problems: helping manage the spectrum demands of IoT devices and achieving much more revenue with the limited resource. This paper proposes a pricing framework to investigate the spectrum leasing in mobile heterogeneous networks with single macrocell and multiple femtocells. We modeled the leasing procedure between the macrocell service provider (MSP and femtocell holders (FHs as an auction to motivate the MSP to lease its spectrum resource. All FHs act as the bidders, and the monopolist MSP acts as the auctioneer. In the auction, FHs submit their bids to rent the spectrum resource so that they can make a profit by selling it to their subscribers. The MSP determines the spectrum leasing amount and chooses the winning FHs by solving the dynamic programming-based 0–1 knapsack problem. In our proposed framework, we focus on the spectrum pricing strategy and revenue maximization of the MSP. The simulation results show that the proposed scheme provides effective motivation for the MSP to lease the spectrum to FHs, and both the MSP and FHs can benefit from spectrum leasing.

  14. A distributed software architecture design framework based on attributed grammar

    Institute of Scientific and Technical Information of China (English)

    JIA Xiao-lin; QIN Zheng; HE Jian; YU Fan

    2005-01-01

    Software architectures shift the focus of developers from lines-of-code to coarser-grained architectural elements and their overall interconnection structure. There are, however, many features of the distributed software that make the developing methods of distributed software quite different from the traditional ways. Furthermore, the traditional centralized ways with fixed interfaces cannot adapt to the flexible requirements of distributed software. In this paper, the attributed grammar (AG) is extended to refine the characters of distributed software, and a distributed software architecture description language (DSADL) based on attributed grammar is introduced, and then a model of integrated environment for software architecture design is proposed. It can be demonstrated by the practice that DSADL can help the programmers to analyze and design distributed software effectively, so the efficiency of the development can be improved greatly.

  15. Population Distribution and Influencing Factors Based on ESDA

    Institute of Scientific and Technical Information of China (English)

    Lv Chen; Fan Jie; Sun Wei

    2012-01-01

    Based on the exploratory spatial data analysis (ESDA) technique and geographic information system (GIS) platform, with statistic data of counties in 2005, this paper confirms that there is a large population density gap between counties in 2005 because the Gini coefficient is 0.55. Population distribution does not change a lot during the past decades, and the southeast China is still much more densely populated than the northwest China. The global spa- tial autoeorrelation of population distribution is obvious because Moran's I scores 0.42 and local spatial autocorrelation is partly significant. Climate and elevation are still the main natural influ- encing factors. Meanwhile industrial structure and transportation significantly influence population distribution. Different combinations of natural factors have different effects on population distribution. For a long term, climate and terrain factor stability affect population distribution. But its influence will be weakened by progress of technology. Economic development is the main factor that changes population distribution for a short term.

  16. Optimization design of hybrid Fresnel-based concentrator for generating uniformity irradiance with the broad solar spectrum

    Science.gov (United States)

    Zhuang, Zhenfeng; Yu, Feihong

    2014-08-01

    This paper presents a novel hybrid Fresnel-based concentrator with improved uniformity irradiance distribution on the solar cell without using secondary optical element (SOE) in the concentrator photovoltaic (CPV) system to overcome the Fresnel loss and to increase the solar cell conversion efficiency. The designed hybrid Fresnel-based concentrator is composed of two parts, the inner part and the outer part. The inner part is the conventional Fresnel lens, while the outer part is double total internal reflection (DTIR) lens. According to the simple geometrical relation, the profile of the proposed hybrid Fresnel-based concentrator is calculated as an initial design profile. To obtain good irradiance uniformity on the solar cell, optimal prism displacements are optimized by using a simplex algorithm for collimated incident sunlight based on different prism focus on different position principles. In addition, a Monte-Carlo ray-tracing simulation approach is utilized to verify the optical performance for the hybrid Fresnel-based concentrator. Results indicate that the hybrid Fresnel-based concentrator designed using this method can achieve spatial non-uniformity less than 16.2%, f-number less than 0.59 (focal length to entry aperture diameter ratio), geometrical concentrator ratio 1759.8×, and acceptance angle ±0.23°. Compared to the conventional Fresnel-based lens and the traditional hybrid Fresnel-based lens, the optimized concentrator yields a significant improvement in irradiance uniformity on the solar cell with a wide solar spectrum range. It also has good tolerance to the incident sunlight.

  17. Distributed data base systems with special emphasis toward POREL

    Science.gov (United States)

    Neuhold, E. J.

    1984-01-01

    In the last few years a number of research and advanced development projects have resulted in distributed data base management prototypes. POREL, developed at the University of Stuttgart, is a multiuser, distributed, relational system developed for wide and local area networks of minicomputers and advanced micros. The general objectives of such data base systems and the architecture of POREL are discussed. In addition a comparison of some of the the existing distributed DMBS is included to provide the reader with information about the current state of the art.

  18. Distributed data base systems with special emphasis toward POREL

    Science.gov (United States)

    Neuhold, E. J.

    1984-01-01

    In the last few years a number of research and advanced development projects have resulted in distributed data base management prototypes. POREL, developed at the University of Stuttgart, is a multiuser, distributed, relational system developed for wide and local area networks of minicomputers and advanced micros. The general objectives of such data base systems and the architecture of POREL are discussed. In addition a comparison of some of the the existing distributed DMBS is included to provide the reader with information about the current state of the art.

  19. DC-DC switching converter based power distribution vs serial power distribution EMC strategies

    CERN Document Server

    Arteche, F; Iglesias, M; Rivetta, C; Arcega, F G; Vila, I

    2009-01-01

    This paper presents a detailed and comparative analysis from the electromagnetic compatibility point of view of the proposed power distributions for the SLHC tracker up-grade. The main idea is to identify and quantify the noise sources, noise distribution at the system level and the sensitive areas in the front-end electronics corresponding to both proposed topologies: The DC-DC converter based power distribution and the serial power distribution. These studies will be used to define critical points on both systems to be studied and prototyped to ensure the correct integration of the system taking critically into account the electromagnetic compatibility. This analysis at the system level is crucial to ensure the final performance of the detector using non conventional power distributions, avoiding interference problems and excessive losses that can lead to catastrophic failures or expensive and un-practical solutions.

  20. Energy-Based Analysis of Mechanisms of Earthquake-Induced Landslide Using Hilbert-Huang Transform and Marginal Spectrum

    Science.gov (United States)

    Fan, Gang; Zhang, Li-Min; Zhang, Jian-Jing; Ouyang, Fang

    2017-09-01

    Based on the Hilbert-Huang Transform and its marginal spectrum, an energy-based method is proposed to analyse the dynamics of earthquake-induced landslides and a case study is presented to illustrate the proposed method. The results show that the seismic Hilbert energy in the sliding mass of a landslide is larger than that in the sliding bed when subjected to seismic excitations, causing different dynamic responses between the sliding mass and the sliding bed. The seismic Hilbert energy transits from the high-frequency components to the low-frequency components when the seismic waves propagate through the weak zone, causing a nonuniform seismic Hilbert energy distribution in the frequency domain. Shear failure develops first at the crest and toe of the sliding mass due to resonance effects. Meanwhile, the seismic Hilbert energy in the frequency components of 3-5 Hz, which is close to the natural frequency of the slope, is largely dissipated in the initiation and failure processes of the landslide. With the development of dynamic failure, the peak energy transmission ratios in the weak zone decrease gradually. This study offers an energy-based interpretation for the initiation and progression of earthquake-induced landslides with the shattering-sliding failure type.

  1. Secondary access based on sensing and primary ARQ feedback in spectrum sharing systems

    KAUST Repository

    Hamza, Doha R.

    2012-04-01

    In the context of primary/secondary spectrum sharing, we propose a randomized secondary access strategy with access probabilities that are a function of both the primary automatic repeat request (ARQ) feedback and the spectrum sensing outcome. The primary terminal operates in a time slotted fashion and is active only when it has a packet to send. The primary receiver can send a positive acknowledgment (ACK) when the received packet is decoded correctly. Lack of ARQ feedback is interpreted as erroneous reception or inactivity. We call this the explicit ACK scheme. The primary receiver may also send a negative acknowledgment (NACK) when the packet is received in error. Lack of ARQ feedback is interpreted as an ACK or no-transmission. This is called the explicit NACK scheme. Under both schemes, when the primary feedback is interpreted as a NACK, the secondary user assumes that there will be retransmission in the next slot and accesses the channel with a certain probability. When the primary feedback is interpreted as an ACK, the secondary user accesses the channel with either one of two probabilities based on the sensing outcome. Under these settings, we find the three optimal access probabilities via maximizing the secondary throughput given a constraint on the primary throughput. We compare the performance of the explicit ACK and explicit NACK schemes and contrast them with schemes based on either sensing or primary ARQ feedback only. © 2012 IEEE.

  2. Performance analysis of switch-based multiuser scheduling schemes with adaptive modulation in spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2014-04-01

    This paper focuses on the development of multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, two scheduling schemes are proposed for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme focuses on optimizing the average spectral efficiency by selecting the user that reports the best channel quality. In order to alleviate the relatively high feedback required by the first scheme, a second scheme based on the concept of switched diversity is proposed, where the base station (BS) scans the secondary users in a sequential manner until a user whose channel quality is above an acceptable predetermined threshold is found. We develop expressions for the statistics of the signal-to-interference and noise ratio as well as the average spectral efficiency, average feedback load, and the delay at the secondary BS. We then present numerical results for the effect of the number of users and the interference constraint on the optimal switching threshold and the system performance and show that our analysis results are in perfect agreement with the numerical results. © 2014 John Wiley & Sons, Ltd.

  3. A Chaos-Based Secure Direct-Sequence/Spread-Spectrum Communication System

    Directory of Open Access Journals (Sweden)

    Nguyen Xuan Quyen

    2013-01-01

    Full Text Available This paper proposes a chaos-based secure direct-sequence/spread-spectrum (DS/SS communication system which is based on a novel combination of the conventional DS/SS and chaos techniques. In the proposed system, bit duration is varied according to a chaotic behavior but is always equal to a multiple of the fixed chip duration in the communication process. Data bits with variable duration are spectrum-spread by multiplying directly with a pseudonoise (PN sequence and then modulated onto a sinusoidal carrier by means of binary phase-shift keying (BPSK. To recover exactly the data bits, the receiver needs an identical regeneration of not only the PN sequence but also the chaotic behavior, and hence data security is improved significantly. Structure and operation of the proposed system are analyzed in detail. Theoretical evaluation of bit-error rate (BER performance in presence of additive white Gaussian noise (AWGN is provided. Parameter choice for different cases of simulation is also considered. Simulation and theoretical results are shown to verify the reliability and feasibility of the proposed system. Security of the proposed system is also discussed.

  4. 基于软件无线电平台的频谱感知实验设计%Design of Spectrum Sensing Experiment Based on SDR Platform

    Institute of Scientific and Technical Information of China (English)

    王洪; 陈祝明; 郭睿刚

    2016-01-01

    频谱感知是感知无线电、动态频谱分配和电子侦听的核心,具有通用性的频谱感知实验可应用于相关的多门课程,在软件无线电平台上设计的频谱感知实验可编程重构,适用于较宽频段和多种信号。该文介绍了USRP与GNU Radio结合的软件无线电平台,讨论了频谱感知的基本原理,设计了基于能量检测的频谱感知实验,并以城市调频广播为例演示了频谱感知实验的过程和结果。%Spectrum sensing is the core of cognitive radio,dynamic spectrum distribution and electronic reconnaissance.Univer-sal experiment of spectrum sensing can be used in many relevant courses.Spectrum sensing experiment can be reconstructed by pro-gramming and be applicable to wide frequency range and signal diversity.This paper introduces the software platform with USRP and GNU Radio first.Then basic theory of spectrum sensing is discussed.We design experiments based on energy detection.Finally,fre-quency modulation broadcasting in city is chosen as an example to show the procedure and results of spectrum sensing.

  5. Optimization of the wavelength shifter ratio in a polystyrene based plastic scintillator through energy spectrum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ye Won; Kim, Myung Soo; Yoo, Hyun Jun; Lee, Dae Hee; Cho, Gyu Seong [Dept. of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of); Moon, Myung Kook [Neutron Instrumentation Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    The scintillation efficiency of the polystyrene based plastic scintillator depends on the ratio of the wavelength shifters, organic fluors (PPO and POPOP). Thus, 24 samples of the plastic scintillator were fabricated in order to find out the optimum ratio of the wavelength shifters in the plastic scintillator. The fabricated plastic scintillators were trimmed through a cutting and polishing process. They were used in gamma energy spectrum measurement with the {sup 137}Cs emitting monoenergy photon with 662 keV for the comparison of the scintillation efficiency. As a result, it was found out that the scintillator sample with 1.00 g of PPO (2,5-Diphenyloxazole) and 0.50 g of POPOP (1,4-Bis(5-phnyl-2oxidazolyl)benzene) dissolved in 100 g of styrene solution has the optimum ratio in terms of the light yield of the polystyrene based plastic scintillator.

  6. A Cooperative Spectrum Sensing Scheme Based on Trust and Fuzzy Logic for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yonghua Wang

    2013-01-01

    Full Text Available This paper proposes a cooperative spectrum sensing scheme based on trust and fuzzy logic for Cognitive Radio Sensor Networks (CRSN. The CRSN nodes use the T-S fuzzy logic to make local decisions on the presence or absence of the primary users (PU signal, and then use a censoring method to only allow the relatively reliable decisions sent to the fusion center. Utilizing a trust evaluation scheme based on the factors such as local sensing difference, sensing location factors, and sensing channel conditions for each node. Combing the majority rule and the trust values of the nodes, the fusion center makes the final decision. Simulation results show that the proposed scheme could improve the detect probability effectively.

  7. Microwave spectrum sensing based on photonic time stretch and compressive sampling.

    Science.gov (United States)

    Chi, Hao; Chen, Ying; Mei, Yuan; Jin, Xiaofeng; Zheng, Shilie; Zhang, Xianmin

    2013-01-15

    An approach to realizing microwave spectrum sensing based on photonic time stretch and compressive sampling is proposed. The time stretch system is used to slow down the input high-speed signal and the compressive sampling based on random demodulation can further decrease the sampling rate. A spectrally sparse signal in a wide bandwidth can be captured with a sampling rate far lower than the Nyquist rate thanks to both time stretch and compressive sampling. It is demonstrated that a system with a time stretch factor 5 and a compression factor 8 can be used to capture a signal with multiple tones in a 50 GHz bandwidth, which means a sampling rate 40 times lower than the Nyquist rate. In addition, the time stretch of the microwave signal largely decreases the data rate of random data sequence and therefore the speed of the mixer in the random demodulator.

  8. Time domain averaging and correlation-based improved spectrum sensing method for cognitive radio

    Science.gov (United States)

    Li, Shenghong; Bi, Guoan

    2014-12-01

    Based on the combination of time domain averaging and correlation, we propose an effective time domain averaging and correlation-based spectrum sensing (TDA-C-SS) method used in very low signal-to-noise ratio (SNR) environments. With the assumption that the received signals from the primary users are deterministic, the proposed TDA-C-SS method processes the received samples by a time averaging operation to improve the SNR. Correlation operation is then performed with a correlation matrix to determine the existence of the primary signal in the received samples. The TDA-C-SS method does not need any prior information on the received samples and the associated noise power to achieve improved sensing performance. Simulation results are presented to show the effectiveness of the proposed TDA-C-SS method.

  9. Spectrum Sensing Based on Censored Observations in Time-Varying Channels using AR-1 Model

    Directory of Open Access Journals (Sweden)

    Dhaval K Patel

    2015-01-01

    Full Text Available Non-parametric sensing algorithms are preferred in cognitive radio. In this paper, spectrum sensing method based on censored observations is proposed. We evaluate the performance of Censored Anderson-Darling (CAD sensing method in time-varying and flat-fading channel using Monte Carlo simulations. We have shown the performance of the CAD sensing in terms of receiver operating characteristic (ROC. The considered channel is modeled by Gaussian variables and characterized by a first ordered autoregressive process ($AR1$. It is shown that the proposed method outperforms prevailing techniques such as the Energy detection (ED sensing and  Order-statistic (OS based sensing in time-varying channel at lower signal to noise ratio.

  10. Evidence-Based Social Communication Interventions for Children with Autism Spectrum Disorder.

    Science.gov (United States)

    Watkins, Laci; Kuhn, Michelle; Ledbetter-Cho, Katherine; Gevarter, Cindy; O'Reilly, Mark

    2017-01-01

    Impairments in social communication skills are a core feature of autism spectrum disorder (ASD) and include deficits in social-emotional reciprocity, non-verbal communicative behaviors used for social interaction, and developing, maintaining, and understanding relationships. In order to improve outcomes for children with ASD, much research has been focused on developing effective interventions to treat these social communication deficits. The purpose of this paper is to highlight the evidence-based practices found within the intervention literature that specifically targets social communication impairments and provide an overview of these strategies. Four relevant themes regarding evidence-based social communication interventions are considered and discussed: (a) social communication outcomes and practices relevant to different stages of development, (b) practices that both reduce interfering behaviors and improve social communication skills, (c) practices that utilize an eclectic combination of intervention strategies, and (d) considerations for practice and research.

  11. Stand diameter distribution modelling and prediction based on Richards function.

    Directory of Open Access Journals (Sweden)

    Ai-guo Duan

    Full Text Available The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM or maximum likelihood estimates method (MLEM were applied to estimate the parameters of models, and the parameter prediction method (PPM and parameter recovery method (PRM were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1 R distribution presented a more accurate simulation than three-parametric Weibull function; (2 the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3 the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4 the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.

  12. Stand diameter distribution modelling and prediction based on Richards function.

    Science.gov (United States)

    Duan, Ai-guo; Zhang, Jian-guo; Zhang, Xiong-qing; He, Cai-yun

    2013-01-01

    The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata) plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM) or maximum likelihood estimates method (MLEM) were applied to estimate the parameters of models, and the parameter prediction method (PPM) and parameter recovery method (PRM) were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1) R distribution presented a more accurate simulation than three-parametric Weibull function; (2) the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3) the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4) the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.

  13. Digital reconstruction based on angular spectrum diffraction with the ridge of wavelet transform in holographic phase-contrast microscopy.

    Science.gov (United States)

    Weng, Jiawen; Zhong, Jiangang; Hu, Cuiying

    2008-12-22

    A numerical reconstruction technique of digital holography based on angular spectrum diffraction by means of the ridge of Gabor wavelet transform (GWT) is presented. Appling the GWT, the object wave can be reconstructed by calculating the wavelet coefficients of the hologram at the ridge of the GWT automatically even if the spectrum of the virtual image is disturbed by the other spectrum. It provides a way to eliminate the effect of the zero-order and the twin-image terms without the spatial filtering. In particular, based on the angular spectrum theory, GWT is applied to the digital holographic phase-contrast microscopy on biological specimens. The theory, the results of a simulation and an experiment of an onion specimen are shown.

  14. Multi-Touch Collaborative Gesture Recognition Based User Interfaces as Behavioral Interventions for Children with Autistic Spectrum Disorder: A Review

    Directory of Open Access Journals (Sweden)

    AHMED HASSAN

    2016-10-01

    Full Text Available This paper addresses UI (User Interface designing based on multi-touch collaborative gesture recognition meant for ASD (Autism Spectrum Disorder - affected children. The present user interfaces (in the context of behavioral interventions for Autism Spectrum disorder are investigated in detail. Thorough comparison has been made among various groups of these UIs. Advantages and limitations of these interfaces are discussed and future directions for the design of such interfaces are suggested.

  15. Fault Feature Extraction of Rolling Bearing Based on an Improved Cyclical Spectrum Density Method

    Institute of Scientific and Technical Information of China (English)

    LI Min; YANG Jianhong; WANG Xiaojing

    2015-01-01

    The traditional cyclical spectrum density(CSD) method is widely used to analyze the fault signals of rolling bearing. All modulation frequencies are demodulated in the cyclic frequency spectrum. Consequently, recognizing bearing fault type is difficult. Therefore, a new CSD method based on kurtosis(CSDK) is proposed. The kurtosis value of each cyclic frequency is used to measure the modulation capability of cyclic frequency. When the kurtosis value is large, the modulation capability is strong. Thus, the kurtosis value is regarded as the weight coefficient to accumulate all cyclic frequencies to extract fault features. Compared with the traditional method, CSDK can reduce the interference of harmonic frequency in fault frequency, which makes fault characteristics distinct from background noise. To validate the effectiveness of the method,experiments are performed on the simulation signal, the fault signal of the bearing outer race in the test bed, and the signal gathered from the bearing of the blast furnace belt cylinder. Experimental results show that the CSDK is better than the resonance demodulation method and the CSD in extracting fault features and recognizing degradation trends. The proposed method provides a new solution to fault diagnosis in bearings.

  16. Spectrum-based method to generate good decoy libraries for spectral library searching in peptide identifications.

    Science.gov (United States)

    Cheng, Chia-Ying; Tsai, Chia-Feng; Chen, Yu-Ju; Sung, Ting-Yi; Hsu, Wen-Lian

    2013-05-01

    As spectral library searching has received increasing attention for peptide identification, constructing good decoy spectra from the target spectra is the key to correctly estimating the false discovery rate in searching against the concatenated target-decoy spectral library. Several methods have been proposed to construct decoy spectral libraries. Most of them construct decoy peptide sequences and then generate theoretical spectra accordingly. In this paper, we propose a method, called precursor-swap, which directly constructs decoy spectral libraries directly at the "spectrum level" without generating decoy peptide sequences by swapping the precursors of two spectra selected according to a very simple rule. Our spectrum-based method does not require additional efforts to deal with ion types (e.g., a, b or c ions), fragment mechanism (e.g., CID, or ETD), or unannotated peaks, but preserves many spectral properties. The precursor-swap method is evaluated on different spectral libraries and the results of obtained decoy ratios show that it is comparable to other methods. Notably, it is efficient in time and memory usage for constructing decoy libraries. A software tool called Precursor-Swap-Decoy-Generation (PSDG) is publicly available for download at http://ms.iis.sinica.edu.tw/PSDG/.

  17. A multimodal wave spectrum-based approach for statistical downscaling of local wave climate

    Science.gov (United States)

    Hegermiller, Christie; Antolinez, Jose A A; Rueda, Ana C; Camus, Paula; Perez, Jorge; Erikson, Li; Barnard, Patrick; Mendez, Fernando J.

    2017-01-01

    Characterization of wave climate by bulk wave parameters is insufficient for many coastal studies, including those focused on assessing coastal hazards and long-term wave climate influences on coastal evolution. This issue is particularly relevant for studies using statistical downscaling of atmospheric fields to local wave conditions, which are often multimodal in large ocean basins (e.g. the Pacific). Swell may be generated in vastly different wave generation regions, yielding complex wave spectra that are inadequately represented by a single set of bulk wave parameters. Furthermore, the relationship between atmospheric systems and local wave conditions is complicated by variations in arrival time of wave groups from different parts of the basin. Here, we address these two challenges by improving upon the spatiotemporal definition of the atmospheric predictor used in statistical downscaling of local wave climate. The improved methodology separates the local wave spectrum into “wave families,” defined by spectral peaks and discrete generation regions, and relates atmospheric conditions in distant regions of the ocean basin to local wave conditions by incorporating travel times computed from effective energy flux across the ocean basin. When applied to locations with multimodal wave spectra, including Southern California and Trujillo, Peru, the new methodology improves the ability of the statistical model to project significant wave height, peak period, and direction for each wave family, retaining more information from the full wave spectrum. This work is the base of statistical downscaling by weather types, which has recently been applied to coastal flooding and morphodynamic applications.

  18. Signal Construction-Based Dispersion Compensation of Lamb Waves Considering Signal Waveform and Amplitude Spectrum Preservation

    Directory of Open Access Journals (Sweden)

    Jian Cai

    2016-12-01

    Full Text Available The results of Lamb wave identification for the aerospace structures could be easily affected by the nonlinear-dispersion characteristics. In this paper, dispersion compensation of Lamb waves is of particular concern. Compared with the similar research works on the traditional signal domain transform methods, this study is based on signal construction from the viewpoint of nonlinear wavenumber linearization. Two compensation methods of linearly-dispersive signal construction (LDSC and non-dispersive signal construction (NDSC are proposed. Furthermore, to improve the compensation effect, the influence of the signal construction process on the other crucial signal properties, including the signal waveform and amplitude spectrum, is considered during the investigation. The linear-dispersion and non-dispersion effects are firstly analyzed. Then, after the basic signal construction principle is explored, the numerical realization of LDSC and NDSC is discussed, in which the signal waveform and amplitude spectrum preservation is especially regarded. Subsequently, associated with the delay-and-sum algorithm, LDSC or NDSC is employed for high spatial resolution damage imaging, so that the adjacent multi-damage or quantitative imaging capacity of Lamb waves can be strengthened. To verify the proposed signal construction and damage imaging methods, the experimental and numerical validation is finally arranged on the aluminum plates.

  19. A ground-based transmission spectrum of the super-Earth exoplanet GJ1214b

    CERN Document Server

    Bean, Jacob L; Homeier, Derek

    2010-01-01

    In contrast to planets with masses similar to that of Jupiter and higher, the bulk compositions of planets in the so-called super-Earth regime cannot be uniquely determined from a mass and radius measurement alone. For these planets, there is a degeneracy between the mass and composition of the interior and a possible atmosphere in theoretical models. The recently discovered transiting super-Earth GJ1214b is one example of this problem. Three distinct models for the planet that are consistent with its mass and radius have been suggested, and breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition. Here we report a ground-based measurement of the transmission spectrum of GJ1214b between 780 and 1000 nm. The lack of features in this spectrum rules out cloud-free atmospheres composed primarily of hydrogen at 4.9 sigma confidence. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at the observ...

  20. Signal Construction-Based Dispersion Compensation of Lamb Waves Considering Signal Waveform and Amplitude Spectrum Preservation.

    Science.gov (United States)

    Cai, Jian; Yuan, Shenfang; Wang, Tongguang

    2016-12-23

    The results of Lamb wave identification for the aerospace structures could be easily affected by the nonlinear-dispersion characteristics. In this paper, dispersion compensation of Lamb waves is of particular concern. Compared with the similar research works on the traditional signal domain transform methods, this study is based on signal construction from the viewpoint of nonlinear wavenumber linearization. Two compensation methods of linearly-dispersive signal construction (LDSC) and non-dispersive signal construction (NDSC) are proposed. Furthermore, to improve the compensation effect, the influence of the signal construction process on the other crucial signal properties, including the signal waveform and amplitude spectrum, is considered during the investigation. The linear-dispersion and non-dispersion effects are firstly analyzed. Then, after the basic signal construction principle is explored, the numerical realization of LDSC and NDSC is discussed, in which the signal waveform and amplitude spectrum preservation is especially regarded. Subsequently, associated with the delay-and-sum algorithm, LDSC or NDSC is employed for high spatial resolution damage imaging, so that the adjacent multi-damage or quantitative imaging capacity of Lamb waves can be strengthened. To verify the proposed signal construction and damage imaging methods, the experimental and numerical validation is finally arranged on the aluminum plates.

  1. [A quick algorithm of dynamic spectrum photoelectric pulse wave detection based on LabVIEW].

    Science.gov (United States)

    Lin, Ling; Li, Na; Li, Gang

    2010-02-01

    Dynamic spectrum (DS) detection is attractive among the numerous noninvasive blood component detection methods because of the elimination of the main interference of the individual discrepancy and measure conditions. DS is a kind of spectrum extracted from the photoelectric pulse wave and closely relative to the artery blood. It can be used in a noninvasive blood component concentration examination. The key issues in DS detection are high detection precision and high operation speed. The precision of measure can be advanced by making use of over-sampling and lock-in amplifying on the pick-up of photoelectric pulse wave in DS detection. In the present paper, the theory expression formula of the over-sampling and lock-in amplifying method was deduced firstly. Then in order to overcome the problems of great data and excessive operation brought on by this technology, a quick algorithm based on LabVIEW and a method of using external C code applied in the pick-up of photoelectric pulse wave were presented. Experimental verification was conducted in the environment of LabVIEW. The results show that by the method pres ented, the speed of operation was promoted rapidly and the data memory was reduced largely.

  2. Optical System Monitoring Based on Reflection Spectrum of Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Mastang Tanra

    2012-01-01

    Full Text Available Problem statement: This study presents fiber fault monitoring approaches for Fiber-to-the Home (FTTH with a Passive Optical Network (PON. Current fiber fault monitoring approaches are difficult to be implemented due to its complexity and high loss as the amount of branches increase. Approach: A fiber fault monitoring scheme is proposed whereas Fiber Bragg Grating (FBG is placed on each branch of the Optical Network Unit (ONU. The advantages of the scheme are that it is simple, low cost and efficient in monitoring fiber fault in ONU. FTTH based network design is simulated using Optisystemtem 8.0 in order to investigate the feasibility of the proposed scheme. Results: The reflection spectrum of Fiber Bragg Gratings (FBGs with different spectrum shape, frequencies and amplitude is used to differentiate each optical network. The simulation result shows that the unique characteristic of fiber Bragg grating is able to distinguish each optical network for a 20 km Passive Optical Network (PON system. Conclusion: This study suggests the implementation of Fiber Bragg Grating that is placed in each network instead of using Optical Time Domain Reflectometer (OTDR for fiber fault monitoring.

  3. Distributed Expert-Based Information Systems: An Interdisciplinary Approach.

    Science.gov (United States)

    Belkin, Nicholas J.; And Others

    1987-01-01

    Based on an international workshop held at Rutgers University, this article discusses problems and issues in the design, research, and implementation of distributed expert-based information systems (DEBIS). Information needs of end users are stressed, architectures for expert information retrieval systems are explored, and prototype models are…

  4. Towards an MDA-based development methodology for distributed applications

    NARCIS (Netherlands)

    Gavras, A.; Belaunde, M.; Ferreira Pires, L.; Andrade Almeida, J.P.; van Sinderen, M.J.; Ferreira Pires, L.

    2004-01-01

    This paper proposes a development methodology for distributed applications based on the principles and concepts of the Model-Driven Architecture (MDA). The paper identifies phases and activities of an MDA-based development trajectory, and defines the roles and products of each activity in accordance

  5. Virtual Portfolios for Collaboration in Distributed Web-Based Learning.

    Science.gov (United States)

    Sorensen, Elsebeth Korsgaard; Tolsby, Haakon; Dirckinck-Holmfeld, Lone

    This paper addresses the problems of collaboration in distributed Web-based learning. It reviews, treats and discusses these problems from the learning theoretical perspective of "communities of practice" as presented by Etienne Wenger (1998), with reference to past and future Web-based designs. The paper suggests the concept and design of virtual…

  6. Towards an MDA-based development methodology for distributed applications

    NARCIS (Netherlands)

    van Sinderen, Marten J.; Gavras, A.; Belaunde, M.; Ferreira Pires, Luis; Andrade Almeida, João

    2004-01-01

    This paper proposes a development methodology for distributed applications based on the principles and concepts of the Model-Driven Architecture (MDA). The paper identifies phases and activities of an MDA-based development trajectory, and defines the roles and products of each activity in accordance

  7. Routing Optimization Based on Taboo Search Algorithm for Logistic Distribution

    Directory of Open Access Journals (Sweden)

    Hongxue Yang

    2014-04-01

    Full Text Available Along with the widespread application of the electronic commerce in the modern business, the logistic distribution has become increasingly important. More and more enterprises recognize that the logistic distribution plays an important role in the process of production and sales. A good routing for logistic distribution can cut down transport cost and improve efficiency. In order to cut down transport cost and improve efficiency, a routing optimization based on taboo search for logistic distribution is proposed in this paper. Taboo search is a metaheuristic search method to perform local search used for logistic optimization. The taboo search is employed to accelerate convergence and the aspiration criterion is combined with the heuristics algorithm to solve routing optimization. Simulation experimental results demonstrate that the optimal routing in the logistic distribution can be quickly obtained by the taboo search algorithm

  8. A Harmony Search Based Algorithm for Detecting Distributed Predicates

    Directory of Open Access Journals (Sweden)

    Eslam Al Maghayreh

    2012-10-01

    Full Text Available Detection of distributed predicates (also referred to as runtime verification can be used to verify that a particular run of a given distributed program satisfies certain properties (represented as predicates. Consequently, distributed predicates detection techniques can be used to effectively improve the dependability of a given distributed application. Due to concurrency, the detection of distributed predicates can incur significant overhead. Most of the effective techniques developed to solve this problem work efficiently for certain classes of predicates, like conjunctive predicates. In this paper, we have presented a technique based on harmony search to efficiently detect the satisfaction of a predicate under the possibly modality. We have implemented the proposed technique and we have conducted several experiments to demonstrate its effectiveness.

  9. Multiple concurrent sources localization based on a two-node distributed acoustic sensor network

    Science.gov (United States)

    Xu, Jiaxin; Zhao, Zhao; Chen, Chunzeng; Xu, Zhiyong

    2017-01-01

    In this work, we propose a new approach to localize multiple concurrent sources using a distributed acoustic sensor network. Only two node-arrays are required in this sensor network, and each node-array consists of only two widely spaced sensors. Firstly, direction-of-arrivals (DOAs) of multiple sources are estimated at each node-array by utilizing a new pooled angular spectrum proposed in this paper, which can implement the spatial aliasing suppression effectively. Based on minimum variance distortionless response (MVDR) beamforming and the DOA estimates of the sources, the time-frequency spectra containing the corresponding energy distribution features associated with those sources are reconstructed in each node-array. Then, scale invariant feature transform (SIFT) is employed to solve the DOA association problem. Performance evaluation is conducted with field recordings and experimental results prove the effectivity and feasibility of the proposed method.

  10. Agent Based Control of Electric Power Systems with Distributed Generation

    DEFF Research Database (Denmark)

    Saleem, Arshad

    . Situation in Denmark is even more interesting, with a current 20% penetration of wind energy it is moving towards an ambitious goal of 50% penetration by the year 2050. Realization of these concepts requires that power systems should be of distributed nature { consisting of autonomous components...... agents. It suggests a multiagent based exible control architecture (subgrid control) suitable for the implementation of the innovative control concepts. This subgrid control architecture is tested on a novel distributed software platform which has been developed to design, test and evaluate distributed...... control strategies. The results have been discussed from case studies of multiagent based distributed control scenarios in electric power systems. The main contribution of this work is a proposal for system design methodology for application of intelligent agent technology in power systems...

  11. An RTM based Distributed Simulation System for Guide Robot

    Directory of Open Access Journals (Sweden)

    Chen Peihua

    2013-10-01

    Full Text Available In order to enhance the robot system integration and development for guide robot, a distributed simulation system was developed in this study using RTM (Robot Technology Middleware technology, which is an open software platform for robot systems. The RT (robot technology system of an adapter, a controller and the robot, together with other CORBA objects, was developed to connect the graphical programing interface with 3D simulator to set up an RTM based distributed simulation system. Simultaneously, the application of the distributed simulation system also confirms the controlling of the real robot utilizing the RT system. The proposed distributed simulation system based on RTM can obviously accelerate the software component development as well as the system integration for guide robot, which will certainly lower the cost of the development of new robot application systems.

  12. A Model of the Fatigue Life Distribution of Composite Laminates Based on Their Static Strength Distribution

    Institute of Scientific and Technical Information of China (English)

    Wu Fuqiang; Yao Weixing

    2008-01-01

    The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article.It is concluded that the inner original defects,which derived from the manufacturing process of composite laminates,are the common and major reason of causing the random distributions of the static strength and the fatigue life.And there is a correlative relation between the two distributions.With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material,the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained.And then the model which is used to describe the distributions of fatigue life of composites,based on their distributions of static strength,is set up.This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates.The experimental data of three kinds of composite laminates are employed to verify this model,and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well.

  13. Laser Sensing of Vegetation Based on Dual Spectrum Measurements of Reflection Coefficients

    Directory of Open Access Journals (Sweden)

    M. L. Belov

    2017-01-01

    Full Text Available Currently, a promising trend in remote sensing of environment is to monitor the vegetative cover: evaluate the productivity of agricultural crops; evaluate the moisture content of soils and the state of ecosystems; provide mapping the sites of bogging, desertification, drought, etc.; control the phases of vegetation of crops, etc.Development of monitoring systems for remote detection of vegetation sites being under unfavorable conditions (low or high temperature, excess or lack of water, soil salinity, disease, etc. is of relevance. Optical methods are the most effective for this task. These methods are based on the physical features of reflection spectra in the visible and near infrared spectral range for vegetation under unfavorable conditions and vegetation under normal conditions.One of the options of optoelectronic equipment for monitoring vegetation condition is laser equipment that allows remote sensing of vegetation from the aircraft and mapping of vegetation sites with abnormal (inactive periods of vegetation reflection spectra with a high degree of spatial resolution.The paper deals with development of a promising dual-spectrum method for laser remote sensing of vegetation. Using the experimentally measured reflection spectra of different vegetation types, mathematical modeling of probability for appropriate detection and false alarms to solve a problem of detecting the vegetation under unfavorable conditions (with abnormal reflection spectra is performed based on the results of dual-spectrum measurements of the reflection coefficient.In mathematical modeling, the lidar system was supposed to provide sensing at wavelengths of 0.532 μm and 0.85 μm. The noise of the measurement was supposed to be normal with zero mean value and mean-square value of 1% -10%.It is shown that the method of laser sensing of vegetation condition based on the results of dual-spectrum measurement of the reflection coefficient at wavelengths of 0.532 μm and 0

  14. Spectrum-tunable Distribution and Spectral Matching for Integrating Sphere Light Source Based on Bromine Tungsten Lamps and LEDs%基于溴钨灯和LED积分球光源的可调谐光谱分布及光谱匹配

    Institute of Scientific and Technical Information of China (English)

    刘洪兴; 任建伟; 李葆勇; 李宪圣; 万志; 赵文才

    2011-01-01

    The mixed-lamps of bromine tungsten lamps and LEDs were proposed to serve as integrating sphere inner source and LEDs were driven by constant current. Simulated Annealing (SA) algorithm was introduced to study the spectral matching technique of spectrum-tunable integrating sphere light source ( STIS ). The simulation experiment indicated that mixed-lamps could not only mimic CIE-D65 and equi-energy spectra successfully, but also improve the performance of STIS. The numbers of LEDs reducing 79. 8% and 82. 9% , respec- tively, and the average-relative error reducing 10% and 40.5% , comparied with LEDs simulation results. A feasible mixed-lamps scheme for Φ0.5 m integrating sphere, whose maximal radiance between 380 nm and 900 nm is no less than 50 W/(m2 · sr). The validating experiment indicated that the SA algorithm and constant current drive mode would be feasible in STIS' engineering practice.%采用溴钨灯和恒流驱动的LED混合作为积分球内部光源,提出了模拟退火算法作为光谱匹配算法,研究了光谱分布可调谐积分球光源的光谱匹配技术.仿真实验表明,该混合光源完全能够定量地模拟CIE-D65和等能光谱分布,且在辐射功率优于LED模拟结果的前提下,LED的数量分别减少79.8%和82.9%,平均相对误差分别减小10%和40.5%.给出了380~900 nm波段最大输出辐亮度不低于50W/(m2·sr)的直径为0.5m的光谱分布可调谐积分球光源的混光方案.实验表明,模拟退火算法和恒流驱动方案可应用于光谱分布可调谐积分球光源的工程实践.

  15. Research on Distributed Software Testing Platform Based on Cloud Resource

    Directory of Open Access Journals (Sweden)

    Shi Hengliang, Zhao Changwei

    2013-05-01

    Full Text Available In order to solvethe low efficiency problem oflarge-scale distributed software testing , CBDSTP(Cloud-Based Distributed Software Testing Platformisput forward.Thisplatform can provide continousintegration and automation of testingforlarge software systems,which can make fulluse of resources onthe cloud clients, achieving testing result sin the real environment and reasonable allocatingtestingjobs,to resolve the Web application software configuration test, compatibility test and distributed test problems,toreduce costs, improve efficiency.Through makingMySQL testing onthisprototype system,theverificationis made forplatform architectureandjoballocation effectiveness.

  16. A Logistics Distribution Plan Based on Cloud Computing

    Directory of Open Access Journals (Sweden)

    Zhou Feng

    2013-12-01

    Full Text Available Aiming at the problems of lowing informatization level and degree of specialization, high consumption and low efficiency in logistics and distribution industry, this paper analyzes the characteristics of cloud computing and the actual needs of enterprise logistics. On this basis, depth study of the logistics and distribution needs of the cloud computing architecture, depth study of the cloud computing architecture in the logistics and distribution needs, and then propose a cloud-based modern logistics solutions, for the development of modern logistics provides a new operating mode

  17. Combinatory Spread—Spectrum Multiple—Access Based on Residue Number System:System and Performance

    Institute of Scientific and Technical Information of China (English)

    YangLieliang; LiChengshu

    1995-01-01

    A combinatory direct-sequence based on residue number system(RNS),spread spec-trum multiple-access communication system model is presented.Under this communication envi-ronment,each user is assigned a set of∑i=1lmi(when i≠j,gcd(mi,mj)=1)othogonal sequences;Each receiver has ∑i=1l micorrelators used for despread,log2(пi=1lmi) information bits can be trans-mitted in a symbol period.We obtain approximations for the multiuser probability of error when the channel noise is a combination of additive white Gaussian noise (AWGN)and multiple-access interference .In section4,we compare the performance such as transmission capability,system structure,and the probability of error with the system proposed by P.K.Enge.

  18. Wide-Spectrum Microscope with a Long Working Distance Aspherical Objective Based on Obscuration Constraint

    Directory of Open Access Journals (Sweden)

    Weibo Wang

    2016-11-01

    Full Text Available We present an approach for an initial configuration design based on obscuration constraint and on-axis Taylor series expansion to realize the design of long working distance microscope (numerical aperture (NA = 0.13 and working distance (WD = 525 mm with a low obscuration aspherical Schwarzschild objective in wide-spectrum imaging (λ = 400–900 nm. Experiments of the testing on the resolution target and inspection on United States Air Force (USAF resolution chart and a line charge-coupled device (CCD (pixel size of 14 μm × 56 μm with different wavelength light sources (λ = 480 nm, 550 nm, 660 nm, 850 nm were implemented to verify the validity of the proposed method.

  19. A novel acquisition method of nuclear spectrum based on pulse area analysis

    CERN Document Server

    Dongcang, Li; Lei, Yang; Zhong, Qi; Xiangting, Meng; Bitao, Hu

    2014-01-01

    A novel method based on pulse area analysis(PAA) was presented for acquisition nuclear spectrum by the digitizer. PAA method can be used as a substitute for the traditional method of pulse height analysis (PHA). In the PAA method a commercial digitizer was employed to sample and sum in the pulse, and the area of pulse is proportional to the energy of the detected radiation. The results of simulation and experiment indicate the great advantages of PAA method, especially when the count rate is high and shaping time constant is small. When shaping time constant is 0.5us, the energy resolution of PAA is about 66% better than that of PHA.

  20. [The noise filtering and baseline correction for harmonic spectrum based on wavelet transform].

    Science.gov (United States)

    Guo, Yuan; Zhao, Xue-Hong; Zhang, Rui; Hu, Ya-Jun; Wang, Yan

    2013-08-01

    The problem of noise and baseline drift is a hot topic in infrared spectral harmonic detection system. This paper presents a new algorithm based on wavelet transform Mallet decomposition to solve the problem of eliminating a variety of complex noise and baseline drift in the harmonic detection. In the algorithm, the appropriate wavelet function and decomposition level were selected to decomposed the noise, baseline drift and useful signal in the harmonic curve into different frequency bands. the bands' information was analysed and a detecting band was set, then the information in useful frequency was reserved by zeroing method of treatment and the coefficient of the threshold. We can just use once transform and reconstruction to remove interference noise and baseline from double-harmonic signal by applying the wavelet transform technique to the harmonic detection spectrum pretreatment. Experiments show that the wavelet transform method can be used to different harmonic detection systems and has universal applicability.

  1. A phase deviation based split-spectrum processing algorithm for ultrasonic flaw detection

    Institute of Scientific and Technical Information of China (English)

    LIU Zhenqing

    2002-01-01

    The Split Spectrum Processing (SSP) technique has proved its ability in reduction of interference noise in ultrasonic nondestructive testing for coarse grained materials. However,the results of SSP algorithms are not sufficiently stable since they are sensitive to the filter bank and filter parameters. And the mechanism of the technique to fully explore the signals is not clear. The statistical phase response characteristic of filter outputs for ultrasonic testing is discussed. Thus, a new SSP algorithm based on phase standard deviation is proposed. The performance is examined for both computer simulated and experimental data, and compared to commonly used minimum algorithm. The phase standard deviation algorithm is proved its superior effect and is less sensitive on the number of filters.

  2. A universal, easy-to-apply light-quality index based on natural light spectrum resemblance

    Science.gov (United States)

    Jou, Jwo-Huei; Chou, Kun-Yi; Yang, Fu-Chin; Agrawal, Abhishek; Chen, Sun-Zen; Tseng, Jing-Ru; Lin, Ching-Chiao; Chen, Po-Wei; Wong, Ken-Tsung; Chi, Yun

    2014-05-01

    Light-quality is extremely crucial for any light source to be used for illumination. However, a proper light-quality index is still missing although numerous electricity-driven lighting measures have been introduced since past 150 yr. We present in this communication a universal and easy-to-apply index for quantifying the quality of any given lighting source, which is based on direct comparison of its lumen spectrum with the natural light counterpart having the same color temperature. A general principle for creating high quality pseudo-natural light is accordingly derived. By using organic light-emitting diode technology, for example, daylight-style emission with a 96% natural light resemblance is obtained as a high number of organic emitters with diffused colors spanning throughout the entire visible range are employed. The same principle can be extended to other lighting technology such as light-emitting diode to generate natural light-style emission.

  3. Educational evidence based interventions for adults with autism spectrum disorders: experimental evidence

    Directory of Open Access Journals (Sweden)

    Saverio Fontani

    2017-01-01

    Full Text Available The educational interventions for adults with autism spectrum disorders are a relatively unexplored topic, in the face of numerous studies on the educational intervention models for the child population. In this paper the results of major studies and meta-analysis on the topic are presented and their implications for educational intervention are discussed.Interventi educativi evidence based per adulti con disturbi dello spettro autistico: evidenze sperimentaliGli interventi educativi per adulti con Disturbi dello Spettro Autistico rappresentano un’area relativamente poco esplorata, a fronte di numerosi studi dedicati ai modelli di intervento educativo rivolti alla popolazione infantile. In questo articolo sono presentati i risultati dei principali studi e delle meta-analisi sul tema e vengono discusse le loro implicazioni per l’intervento educativo.

  4. Routing and spectrum assignment based on ant colony optimization of minimum consecutiveness loss in elastic optical networks

    Science.gov (United States)

    Wang, Fu; Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Tian, Qinghua; Zhang, Qi; Rao, Lan; Tian, Feng; Luo, Biao; Liu, Yingjun; Tang, Bao

    2016-10-01

    Elastic Optical Networks are considered to be a promising technology for future high-speed network. In this paper, we propose a RSA algorithm based on the ant colony optimization of minimum consecutiveness loss (ACO-MCL). Based on the effect of the spectrum consecutiveness loss on the pheromone in the ant colony optimization, the path and spectrum of the minimal impact on the network are selected for the service request. When an ant arrives at the destination node from the source node along a path, we assume that this path is selected for the request. We calculate the consecutiveness loss of candidate-neighbor link pairs along this path after the routing and spectrum assignment. Then, the networks update the pheromone according to the value of the consecutiveness loss. We save the path with the smallest value. After multiple iterations of the ant colony optimization, the final selection of the path is assigned for the request. The algorithms are simulated in different networks. The results show that ACO-MCL algorithm performs better in blocking probability and spectrum efficiency than other algorithms. Moreover, the ACO-MCL algorithm can effectively decrease spectrum fragmentation and enhance available spectrum consecutiveness. Compared with other algorithms, the ACO-MCL algorithm can reduce the blocking rate by at least 5.9% in heavy load.

  5. The Spectrum Sharing in Cognitive Radio Networks Based on Competitive Price Game

    Directory of Open Access Journals (Sweden)

    Y. B. Li

    2012-09-01

    Full Text Available The competitive price game model is used to analyze the spectrum sharing problem in the cognitive radio networks, and the spectrum sharing problem with the constraints of available spectrum resource from primary users is further discussed in this paper. The Rockafeller multiplier method is applied to deal with the constraints of available licensed spectrum resource, and the improved profits function is achieved, which can be used to measure the impact of shared spectrum price strategies on the system profit. However, in the competitive spectrum sharing problem of practical cognitive radio network, primary users have to determine price of the shared spectrum without the acknowledgement of the other primary user’s price strategies. Thus a fast gradient iterative calculation method of equilibrium price is proposed, only with acknowledgement of the price strategies of shared spectrum during last cycle. Through the adaptive iteration at the direction with largest gradient of improved profit function, the equilibrium price strategies can be achieved rapidly. It can also avoid the predefinition of adjustment factor according to the parameters of communication system in conventional linear iteration method. Simulation results show that the proposed competitive price spectrum sharing model can be applied in the cognitive radio networks with constraints of available licensed spectrum, and it has better convergence performance.

  6. Brief Report: Prevalence of Self-Injurious Behaviors among Children with Autism Spectrum Disorder--A Population-Based Study

    Science.gov (United States)

    Soke, Gnakub N.; Rosenberg, Steven A.; Hamman, Richard F.; Fingerlin, Tasha; Robinson, Cordelia; Carpenter, Laura; Giarelli, Ellen; Lee, Li-Ching; Wiggins, Lisa D.; Durkin, Maureen S.; DiGuiseppi, Carolyn

    2016-01-01

    Self-injurious behaviors (SIB) have been reported in more than 30% of children with an autism spectrum disorder (ASD) in clinic-based studies. This study estimated the prevalence of SIB in a large population-based sample of children with ASD in the United States. A total of 8,065 children who met the surveillance case definition for ASD in the…

  7. Principles And Design Of Multibeam Interference Devices: A Microelectromechanical-Systems Segment-Deformable-Mirror-Based Adaptive Spectrum Attenuator

    OpenAIRE

    Huang, Z.Y.; Zhu, Y. Z.; Wang, Anbo

    2005-01-01

    Fourier analysis of multibeam interference shows that the total electric field and relative time delay of the beams form a Fourier-transform pair. Fourier-analysis-based multibeam interference analysis and device design is discussed in detail. The principle of the proposed segment-deformable-mirror-based adaptive spectrum attenuator is illustrated. (c) 2005 Optical Society of America.

  8. Parents' Experiences of Applied Behaviour Analysis (ABA)-Based Interventions for Children Diagnosed with Autistic Spectrum Disorder

    Science.gov (United States)

    McPhilemy, Catherine; Dillenburger, Karola

    2013-01-01

    Applied behaviour analysis (ABA)-based programmes are endorsed as the gold standard for treatment of children with autistic spectrum disorder (ASD) in most of North America. This is not the case in most of Europe, where instead a non-specified "eclectic" approach is adopted. We explored the social validity of ABA-based interventions with…

  9. BP-Neural-Network-Based Tool Wear Monitoring by Using Wavelet Decomposition of the Power Spectrum

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jian-ming; XI Chang-qing; LI Yan; XIAO Ji-ming

    2004-01-01

    In a drilling process, the power spectrum of the drilling force is related to the tool wear and is widely applied in the monitoring of tool wear. But the feature extraction and identification of the power spectrum have always been an unresolved difficult problem. This paper solves it through decomposition of the power spectrum in multilayers using wavelet transform and extraction of the low frequency decomposition coefficient us the envelope information of the power spectrum. Intelligent identification of the tool wear status is achieved in the drilling process through fusing the wavelet decomposition coefficient of the power spectrum by using a BP ( Back Propagation) neural network. The experimental results show that the features of the power spectrum can be extracted efficiently through this method, and the trained neural networks show high identification precision and the ability of extension.

  10. A fast computation method for MUSIC spectrum function based on circular arrays

    Science.gov (United States)

    Du, Zhengdong; Wei, Ping

    2015-02-01

    The large computation amount of multiple signal classification (MUSIC) spectrum function seriously affects the timeliness of direction finding system using MUSIC algorithm, especially in the two-dimensional directions of arrival (DOA) estimation of azimuth and elevation with a large antenna array. This paper proposes a fast computation method for MUSIC spectrum. It is suitable for any circular array. First, the circular array is transformed into a virtual uniform circular array, in the process of calculating MUSIC spectrum, for the cyclic characteristics of steering vector, the inner product in the calculation of spatial spectrum is realised by cyclic convolution. The computational amount of MUSIC spectrum is obviously less than that of the conventional method. It is a very practical way for MUSIC spectrum computation in circular arrays.

  11. UOBPRM: A uniformly distributed obstacle-based PRM

    KAUST Repository

    Yeh, Hsin-Yi

    2012-10-01

    This paper presents a new sampling method for motion planning that can generate configurations more uniformly distributed on C-obstacle surfaces than prior approaches. Here, roadmap nodes are generated from the intersections between C-obstacles and a set of uniformly distributed fixed-length segments in C-space. The results show that this new sampling method yields samples that are more uniformly distributed than previous obstacle-based methods such as OBPRM, Gaussian sampling, and Bridge test sampling. UOBPRM is shown to have nodes more uniformly distributed near C-obstacle surfaces and also requires the fewest nodes and edges to solve challenging motion planning problems with varying narrow passages. © 2012 IEEE.

  12. Distributed intrusion detection system based on fuzzy rules

    Science.gov (United States)

    Qiao, Peili; Su, Jie; Liu, Yahui

    2006-04-01

    Computational Intelligence is the theory and method solving problems by simulating the intelligence of human using computer and it is the development of Artificial Intelligence. Fuzzy Technique is one of the most important theories of computational Intelligence. Genetic Fuzzy Technique and Neuro-Fuzzy Technique are the combination of Fuzzy Technique and novel techniques. This paper gives a distributed intrusion detection system based on fuzzy rules that has the characters of distributed parallel processing, self-organization, self-learning and self-adaptation by the using of Neuro-Fuzzy Technique and Genetic Fuzzy Technique. Specially, fuzzy decision technique can be used to reduce false detection. The results of the simulation experiment show that this intrusion detection system model has the characteristics of distributed, error tolerance, dynamic learning, and adaptation. It solves the problem of low identifying rate to new attacks and hidden attacks. The false detection rate is low. This approach is efficient to the distributed intrusion detection.

  13. Distributed Parallel Endmember Extraction of Hyperspectral Data Based on Spark

    Directory of Open Access Journals (Sweden)

    Zebin Wu

    2016-01-01

    Full Text Available Due to the increasing dimensionality and volume of remotely sensed hyperspectral data, the development of acceleration techniques for massive hyperspectral image analysis approaches is a very important challenge. Cloud computing offers many possibilities of distributed processing of hyperspectral datasets. This paper proposes a novel distributed parallel endmember extraction method based on iterative error analysis that utilizes cloud computing principles to efficiently process massive hyperspectral data. The proposed method takes advantage of technologies including MapReduce programming model, Hadoop Distributed File System (HDFS, and Apache Spark to realize distributed parallel implementation for hyperspectral endmember extraction, which significantly accelerates the computation of hyperspectral processing and provides high throughput access to large hyperspectral data. The experimental results, which are obtained by extracting endmembers of hyperspectral datasets on a cloud computing platform built on a cluster, demonstrate the effectiveness and computational efficiency of the proposed method.

  14. PRIVACY-PRESERVING RANDOM PROJECTION-BASED RECOMMENDATIONS BASED ON DISTRIBUTED DATA

    OpenAIRE

    2013-01-01

    Providing recommendations based on distributed data has received an increasing amount of attention because it offers several advantages. Online vendors who face problems caused by a limited amount of available data want to offer predictions based on distributed data collaboratively because they can surmount problems such as cold start, limited coverage, and unsatisfactory accuracy through partnerships. It is relatively easy to produce referrals based on distributed data when privacy is not a ...

  15. Differential energy spectrum and angular distribution of hadrons at mountain altitudes at energies E gt 10 sup 3 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Avakyan, V.V.; Mamidzhanyan, E.A.; Ovsepyan, G.G.; Ter-Antonyan, S.V. (Erevan Physics Institute (SU))

    1989-07-01

    The absolute differential energy spectrum and angular distribution of hadrons is presented for altitude 3250 meters above sea level. Experimental data obtained with high statistical accuracy are compared with a Monte Carlo calculation of the passage of the primary cosmic radiation through the atmosphere. The theoretical and statistical analysis is carried out of the influence of the selection of events on the basis of the shower accompaniment on the measured physical characteristics of the flux of hadrons. The dependence of the cross section for inelastic interaction of nucleons with air nuclei on energy is determined.

  16. Universal spectrum for DNA base C+G concentration variability in Human chromosome Y

    CERN Document Server

    Selvam, A M

    2004-01-01

    The spatial distribution of DNA base sequence A, C, G and T exhibit selfsimilar fractal fluctuations and the corresponding power spectra follow inverse power law form, which implies the following: (1) A scale invariant eddy continuum, namely, the amplitudes of component eddies are related to each other by a scale factor alone. In general, the scale factor is different for different scale ranges and indicates a multifractal structure for the spatial distribution of DNA base sequence. (2) Long-range spatial correlations of the eddy fluctuations. Multifractal structure to space-time fluctuations and the associated inverse power law form for power spectra is generic to spatially extended dynamical systems in nature and is a signature of self-organized criticality. The exact physical mechanism for the observed self-organized criticality is not yet identified. The author has developed a general systems theory where quantum mechanical laws emerge as self-consistent explanations for the observed long-range space-time...

  17. [The new method monitoring crop water content based on NIR-Red spectrum feature space].

    Science.gov (United States)

    Cheng, Xiao-juan; Xu, Xin-gang; Chen, Tian-en; Yang, Gui-jun; Li, Zhen-hai

    2014-06-01

    Moisture content is an important index of crop water stress condition, timely and effective monitoring of crop water content is of great significance for evaluating crop water deficit balance and guiding agriculture irrigation. The present paper was trying to build a new crop water index for winter wheat vegetation water content based on NIR-Red spectral space. Firstly, canopy spectrums of winter wheat with narrow-band were resampled according to relative spectral response function of HJ-CCD and ZY-3. Then, a new index (PWI) was set up to estimate vegetation water content of winter wheat by improveing PDI (perpendicular drought index) and PVI (perpendicular vegetation index) based on NIR-Red spectral feature space. The results showed that the relationship between PWI and VWC (vegetation water content) was stable based on simulation of wide-band multispectral data HJ-CCD and ZY-3 with R2 being 0.684 and 0.683, respectively. And then VWC was estimated by using PWI with the R2 and RMSE being 0.764 and 0.764, 3.837% and 3.840%, respectively. The results indicated that PWI has certain feasibility to estimate crop water content. At the same time, it provides a new method for monitoring crop water content using remote sensing data HJ-CCD and ZY-3.

  18. A ground-based near-infrared emission spectrum of the exoplanet HD 189733b.

    Science.gov (United States)

    Swain, Mark R; Deroo, Pieter; Griffith, Caitlin A; Tinetti, Giovanna; Thatte, Azam; Vasisht, Gautam; Chen, Pin; Bouwman, Jeroen; Crossfield, Ian J; Angerhausen, Daniel; Afonso, Cristina; Henning, Thomas

    2010-02-01

    Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H(2)O), methane (CH(4)), carbon dioxide (CO(2)), and carbon monoxide (CO) have been detected in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4-5.2 microm spectral region. Here we report ground-based observations of the dayside emission spectrum for HD 189733b between 2.0-2.4 microm and 3.1-4.1 microm, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements. A feature at approximately 3.25 microm is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1 bar to 1 x 10(-6) bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH(4), similar to what is seen in the atmospheres of planets in our own Solar System. These results suggest that non-LTE effects may need to be considered when interpreting measurements of strongly irradiated exoplanets.

  19. Photonic-chip-based radio-frequency spectrum analyser with terahertz bandwidth

    Science.gov (United States)

    Pelusi, Mark; Luan, Feng; Vo, Trung D.; Lamont, Michael R. E.; Madden, Steven J.; Bulla, Douglas A.; Choi, Duk-Yong; Luther-Davies, Barry; Eggleton, Benjamin J.

    2009-03-01

    Signal processing at terahertz speeds calls for an enormous leap in bandwidth beyond the current capabilities of electronics, for which practical operation is currently limited to tens of gigahertz. This can be achieved through all-optical schemes making use of the ultrafast response of χ(3) nonlinear waveguides. Towards this objective, we have developed compact planar rib waveguides based on As2S3 glass, providing a virtual `lumped' high nonlinearity in a monolithic platform capable of integrating multiple functions. Here, we apply it to demonstrate, for the first time, a photonic-chip-based, all-optical, radio-frequency spectrum analyser with the performance advantages of distortion-free, broad measurement bandwidth (>2.5 THz) and flexible wavelength operation (that is, colourless). The key to this is the waveguide's high optical nonlinearity and dispersion-shifted design. Using the device, we characterize high-bit-rate (320 Gb s-1) optical signals impaired by various distortions. The demonstrated ultrafast, broadband capability highlights the potential for integrated chip-based signal processing at bit rates approaching and beyond Tb s-1.

  20. A soft-hard combination-based cooperative spectrum sensing scheme for cognitive radio networks.

    Science.gov (United States)

    Do, Nhu Tri; An, Beongku

    2015-02-13

    In this paper we propose a soft-hard combination scheme, called SHC scheme, for cooperative spectrum sensing in cognitive radio networks. The SHC scheme deploys a cluster based network in which Likelihood Ratio Test (LRT)-based soft combination is applied at each cluster, and weighted decision fusion rule-based hard combination is utilized at the fusion center. The novelties of the SHC scheme are as follows: the structure of the SHC scheme reduces the complexity of cooperative detection which is an inherent limitation of soft combination schemes. By using the LRT, we can detect primary signals in a low signal-to-noise ratio regime (around an average of -15 dB). In addition, the computational complexity of the LRT is reduced since we derive the closed-form expression of the probability density function of LRT value. The SHC scheme also takes into account the different effects of large scale fading on different users in the wide area network. The simulation results show that the SHC scheme not only provides the better sensing performance compared to the conventional hard combination schemes, but also reduces sensing overhead in terms of reporting time compared to the conventional soft combination scheme using the LRT.

  1. A ground-based near-infrared emission spectrum of the exoplanet HD 189733b

    CERN Document Server

    Swain, Mark R; Griffith, Caitlin A; Tinetti, Giovanna; Thatte, Azam; Vasisht, Gautam; Chen, Pin; Bouwman, Jeroen; Crossfield, Ian J; Angerhausen, Daniel; Afonso, Cristina; Henning, Thomas

    2010-01-01

    Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H2O), methane (CH4), carbon dioxide (CO2), and carbon monoxide (CO) have been detected in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4 - 5.2 micron spectral region. Here we report ground-based observations of the dayside emission spectrum for HD 189733b between 2.0-2.4 micron and 3.1-4.1 micron, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements. A feature at ~3.25 micron is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1 bar to 1 x 10-6 bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH4, similar to what is seen in the atmospheres o...

  2. Distributions of personal VOC exposures: a population-based analysis.

    Science.gov (United States)

    Jia, Chunrong; D'Souza, Jennifer; Batterman, Stuart

    2008-10-01

    Information regarding the distribution of volatile organic compound (VOC) concentrations and exposures is scarce, and there have been few, if any, studies using population-based samples from which representative estimates can be derived. This study characterizes distributions of personal exposures to ten different VOCs in the U.S. measured in the 1999--2000 National Health and Nutrition Examination Survey (NHANES). Personal VOC exposures were collected for 669 individuals over 2-3 days, and measurements were weighted to derive national-level statistics. Four common exposure sources were identified using factor analyses: gasoline vapor and vehicle exhaust, methyl tert-butyl ether (MBTE) as a gasoline additive, tap water disinfection products, and household cleaning products. Benzene, toluene, ethyl benzene, xylenes chloroform, and tetrachloroethene were fit to log-normal distributions with reasonably good agreement to observations. 1,4-Dichlorobenzene and trichloroethene were fit to Pareto distributions, and MTBE to Weibull distribution, but agreement was poor. However, distributions that attempt to match all of the VOC exposure data can lead to incorrect conclusions regarding the level and frequency of the higher exposures. Maximum Gumbel distributions gave generally good fits to extrema, however, they could not fully represent the highest exposures of the NHANES measurements. The analysis suggests that complete models for the distribution of VOC exposures require an approach that combines standard and extreme value distributions, and that carefully identifies outliers. This is the first study to provide national-level and representative statistics regarding the VOC exposures, and its results have important implications for risk assessment and probabilistic analyses.

  3. Novel algorithm for distributed replicas management based on dynamic programming

    Institute of Scientific and Technical Information of China (English)

    Wang Tao; Lu Xianliang; Hou Mengshu

    2006-01-01

    Replicas can improve the data reliability in distributed system. However, the traditional algorithms for replica management are based on the assumption that all replicas have the uniform reliability, which is inaccurate in some actual systems. To address such problem, a novel algorithm is proposed based on dynamic programming to manage the number and distribution of replicas in different nodes. By using Markov model, replicas management is organized as a multi-phase process, and the recursion equations are provided. In this algorithm, the heterogeneity of nodes, the expense for maintaining replicas and the engaged space have been considered. Under these restricted conditions, this algorithm realizes high data reliability in a distributed system. The results of case analysis prove the feasibility of the algorithm.

  4. Network Capacity Assessment of CHP-based Distributed Generation on Urban Energy Distribution Networks

    Science.gov (United States)

    Zhang, Xianjun

    The combined heat and power (CHP)-based distributed generation (DG) or dis-tributed energy resources (DERs) are mature options available in the present energy market, considered to be an effective solution to promote energy efficiency. In the urban environment, the electricity, water and natural gas distribution networks are becoming increasingly interconnected with the growing penetration of the CHP-based DG. Subsequently, this emerging interdependence leads to new topics meriting serious consideration: how much of the CHP-based DG can be accommodated and where to locate these DERs, and given preexisting constraints, how to quantify the mutual impacts on operation performances between these urban energy distribution networks and the CHP-based DG. The early research work was conducted to investigate the feasibility and design methods for one residential microgrid system based on existing electricity, water and gas infrastructures of a residential community, mainly focusing on the economic planning. However, this proposed design method cannot determine the optimal DG sizing and siting for a larger test bed with the given information of energy infrastructures. In this context, a more systematic as well as generalized approach should be developed to solve these problems. In the later study, the model architecture that integrates urban electricity, water and gas distribution networks, and the CHP-based DG system was developed. The proposed approach addressed the challenge of identifying the optimal sizing and siting of the CHP-based DG on these urban energy networks and the mutual impacts on operation performances were also quantified. For this study, the overall objective is to maximize the electrical output and recovered thermal output of the CHP-based DG units. The electricity, gas, and water system models were developed individually and coupled by the developed CHP-based DG system model. The resultant integrated system model is used to constrain the DG's electrical

  5. ASCA View of the Supernova Remnant Gamma Cygni (G78.2+2.1) Bremsstrahlung X-ray Spectrum from Loss-flattened Electron Distribution

    CERN Document Server

    Uchiyama, Y; Aharonian, F A; Mattox, J R; Uchiyama, Yasunobu; Takahashi, Tadayuki; Aharonian, Felix; Mattox, John

    2002-01-01

    We perform X-ray studies of the shell-type supernova remnant (SNR) gamma-Cygni associated with the brightest EGRET unidentified source 3EG J2020+4017. In addition to the thermal emissions with characteristic temperature of kT = 0.5-0.9 keV, we found an extremely hard X-ray component from several clumps localized in the northern part of the remnant. This component is described by a power-law with a photon index of 0.8-1.5. Both the absolute flux and the spectral shape of the nonthermal X-rays cannot be explained by the synchrotron or inverse-Compton mechanisms. We argue that the unusually hard X-ray spectrum can be naturally interpreted in terms of nonthermal bremsstrahlung from Coulomb-loss-flattened electron distribution in dense environs with the gas density about 10 to 100 cm^-3 . For given spectrum of the electron population, the ratio of the bremsstrahlung X- and gamma-ray fluxes depends on the position of the ``Coulomb break'' in the electron spectrum. The bulk of gamma-rays detected by EGRET would come...

  6. Quantum key distribution using card, base station and trusted authority

    Science.gov (United States)

    Nordholt, Jane Elizabeth; Hughes, Richard John; Newell, Raymond Thorson; Peterson, Charles Glen; Rosenberg, Danna; McCabe, Kevin Peter; Tyagi, Kush T; Dallman, Nicholas

    2015-04-07

    Techniques and tools for quantum key distribution ("QKD") between a quantum communication ("QC") card, base station and trusted authority are described herein. In example implementations, a QC card contains a miniaturized QC transmitter and couples with a base station. The base station provides a network connection with the trusted authority and can also provide electric power to the QC card. When coupled to the base station, after authentication by the trusted authority, the QC card acquires keys through QKD with a trusted authority. The keys can be used to set up secure communication, for authentication, for access control, or for other purposes. The QC card can be implemented as part of a smart phone or other mobile computing device, or the QC card can be used as a fillgun for distribution of the keys.

  7. NHPP-Based Software Reliability Models Using Equilibrium Distribution

    Science.gov (United States)

    Xiao, Xiao; Okamura, Hiroyuki; Dohi, Tadashi

    Non-homogeneous Poisson processes (NHPPs) have gained much popularity in actual software testing phases to estimate the software reliability, the number of remaining faults in software and the software release timing. In this paper, we propose a new modeling approach for the NHPP-based software reliability models (SRMs) to describe the stochastic behavior of software fault-detection processes. The fundamental idea is to apply the equilibrium distribution to the fault-detection time distribution in NHPP-based modeling. We also develop efficient parameter estimation procedures for the proposed NHPP-based SRMs. Through numerical experiments, it can be concluded that the proposed NHPP-based SRMs outperform the existing ones in many data sets from the perspective of goodness-of-fit and prediction performance.

  8. Quantum key distribution using card, base station and trusted authority

    Energy Technology Data Exchange (ETDEWEB)

    Nordholt, Jane E.; Hughes, Richard John; Newell, Raymond Thorson; Peterson, Charles Glen; Rosenberg, Danna; McCabe, Kevin Peter; Tyagi, Kush T.; Dallmann, Nicholas

    2017-06-14

    Techniques and tools for quantum key distribution ("QKD") between a quantum communication ("QC") card, base station and trusted authority are described herein. In example implementations, a QC card contains a miniaturized QC transmitter and couples with a base station. The base station provides a network connection with the trusted authority and can also provide electric power to the QC card. When coupled to the base station, after authentication by the trusted authority, the QC card acquires keys through QKD with a trust authority. The keys can be used to set up secure communication, for authentication, for access control, or for other purposes. The QC card can be implemented as part of a smart phone or other mobile computing device, or the QC card can be used as a fillgun for distribution of the keys.

  9. MR-based assessment of body fat distribution and characteristics.

    Science.gov (United States)

    Baum, Thomas; Cordes, Christian; Dieckmeyer, Michael; Ruschke, Stefan; Franz, Daniela; Hauner, Hans; Kirschke, Jan S; Karampinos, Dimitrios C

    2016-08-01

    The assessment of body fat distribution and characteristics using magnetic resonance (MR) methods has recently gained significant attention as it further extends our pathophysiological understanding of diseases including obesity, metabolic syndrome, or type 2 diabetes mellitus, and allows more detailed insights into treatment response and effects of lifestyle interventions. Therefore, the purpose of this study was to review the current literature on MR-based assessment of body fat distribution and characteristics. PubMed search was performed to identify relevant studies on the assessment of body fat distribution and characteristics using MR methods. T1-, T2-weighted MR Imaging (MRI), Magnetic Resonance Spectroscopy (MRS), and chemical shift-encoding based water-fat MRI have been successfully used for the assessment of body fat distribution and characteristics. The relationship of insulin resistance and serum lipids with abdominal adipose tissue (i.e. subcutaneous and visceral adipose tissue), liver, muscle, and bone marrow fat content have been extensively investigated and may help to understand the underlying pathophysiological mechanisms and the multifaceted obese phenotype. MR methods have also been used to monitor changes of body fat distribution and characteristics after interventions (e.g. diet or physical activity) and revealed distinct, adipose tissue-specific properties. Lastly, chemical shift-encoding based water-fat MRI can detect brown adipose tissue which is currently the focus of intense research as a potential treatment target for obesity. In conclusion, MR methods reliably allow the assessment of body fat distribution and characteristics. Irrespective of the promising findings based on these MR methods the clinical usefulness remains to be established.

  10. Systematic review of the prevalence of bipolar disorder and bipolar spectrum disorders in population-based studies

    Directory of Open Access Journals (Sweden)

    José Caetano Dell'Aglio Jr.

    2013-01-01

    Full Text Available This paper describes the findings of a systematic literature review aimed at providing an overview of the lifetime prevalence of bipolar disorder and bipolar spectrum disorders in population-based studies. Databases MEDLINE, ProQuest, Psychnet, and Web of Science were browsed for papers published in English between 1999 and May 2012 using the following search string: bipolar disorders OR bipolar spectrum disorders AND prevalence OR cross-sectional OR epidemiology AND population-based OR non-clinical OR community based. The search yielded a total of 434 papers, but only those published in peer-reviewed journals and with samples aged ≥ 18 years were included, resulting in a final sample of 18 papers. Results revealed rather heterogeneous findings concerning the prevalence of bipolar disorders and bipolar spectrum disorders. Lifetime prevalence of bipolar disorder ranged from 0.1 to 7.5%, whereas lifetime prevalence of bipolar spectrum disorders ranged from 2.4 to 15.1%. Differences in the rates of bipolar disorder and bipolar spectrum disorders may be related to the consideration of subthreshold criteria upon diagnosis. Differences in the prevalence of different subtypes of the disorder are discussed in light of diagnostic criteria and instruments applied.

  11. Aquaporin-4 autoantibodies in neuromyelitis optica spectrum disorders: comparison between tissue-based and cell-based indirect immunofluorescence assays

    Directory of Open Access Journals (Sweden)

    Chan Koon H

    2010-09-01

    Full Text Available Abstract Background Neuromyelitis optica spectrum disorders (NMOSD are severe central nervous system inflammatory demyelinating disorders (CNS IDD characterized by monophasic or relapsing, longitudinally extensive transverse myelitis (LETM and/or optic neuritis (ON. A significant proportion of NMOSD patients are seropositive for aquaporin-4 (AQP4 autoantibodies. We compared the AQP4 autoantibody detection rates of tissue-based indirect immunofluorescence assay (IIFA and cell-based IIFA. Methods Serum of Chinese CNS IDD patients were assayed for AQP4 autoantibodies by tissue-based IIFA using monkey cerebellum and cell-based IIFA using transfected HEK293 cells which express human AQP4 on their cell membranes. Results In total, 128 CNS IDD patients were studied. We found that 78% of NMO patients were seropositive for AQP4 autoantibodies by cell-based IIFA versus 61% by tissue-based IFA (p = 0.250, 75% of patients having relapsing myelitis (RM with LETM were seropositive by cell-based IIFA versus 50% by tissue-based IIFA (p = 0.250, and 33% of relapsing ON patients were seropositive by cell-based IIFA versus 22% by tissue-based IIFA (p = 1.000; however the differences were not statistically significant. All patients seropositive by tissue-based IIFA were also seropositive for AQP4 autoantibodies by cell-based IIFA. Among 29 NMOSD patients seropositive for AQP4 autoantibodies by cell-based IIFA, 20 (69% were seropositive by tissue-based IIFA. The 9 patients seropositive by cell-based IIFA while seronegative by tissue-based IIFA had NMO (3, RM with LETM (3, a single attack of LETM (1, relapsing ON (1 and a single ON attack (1. Among 23 NMO or RM patients seropositive for AQP4 autoantibodies by cell-based IIFA, comparison between those seropositive (n = 17 and seronegative (n = 6 by tissue-based IIFA revealed no differences in clinical and neuroradiological characteristics between the two groups. Conclusion Cell-based IIFA is slightly more sensitive

  12. Quantum Key Distribution Network Based on Differential Phase Shift

    Institute of Scientific and Technical Information of China (English)

    WANG Wan-Ying; WANG Chuan; WEN Kai; LONG Gui-Lu

    2007-01-01

    Using a series of quantum correlated photon pairs, we propose a theoretical scheme for any-to-any multi-user quantum key distribution network based on differential phase shift. The differential phase shift and the different detection time slots ensure the security of our scheme against eavesdropping. We discuss the security under the intercept-resend attack and the source replacement attack.

  13. Ceramic design concepts based on stress distribution analysis.

    Science.gov (United States)

    Esquivel-Upshaw, J F; Anusavice, K J

    2000-08-01

    This article discusses general design concepts involved in fabricating ceramic and metal-ceramic restorations based on scientific stress distribution data. These include the effects of ceramic layer thickness, modulus of elasticity of supporting substrates, direction of applied loads, intraoral stress, and crown geometry on the susceptibility of certain restoration designs to fracture.

  14. Security of EPR-based Quantum Key Distribution

    CERN Document Server

    Inamori, H

    2000-01-01

    We propose a proof of the security of EPR-based quantum key distribution against enemies with unlimited computational power. The proof holds for a protocol using interactive error-reconciliation scheme. We assume in this paper that the legitimate parties receive a given number of single photon signals and that their measurement devices are perfect.

  15. Performance study on Gossip-based group key distribution protocal

    Institute of Scientific and Technical Information of China (English)

    Yao Yan; Ma Jiaqing; Zhong Yiping; Zhang Shiyong

    2006-01-01

    Group key distribution is faced with two important problems, i.e. reliability and scalability, to support security multicast for large and dynamic groups. With group member increasing, traditional reliable multicast protocol can not deal with them fully. Gossip-based group key distribution idea for wide-area dissemination was provided. It is based on an gossip-based loss recovery control mechanism. It can provide a probabilistic reliable guarantee for a information dissemination to reach every group member, which can achieve scalability and reliability. To achieve full reliability, three layers protocol model in group key distribution was provided. One is best effect layer, which provides unreliable dissemination. Other is gossip-based loss recovery layer, which provides probabilistic reliable guarantee. Last is vsync-based layer, which provide deterministic loss recovery. We integrate probabilistic loss recovery method with deterministic one. The model possess scalability that probabilistic method has and full reliability prosthesis by vsync-based. To evaluate the effectiveness of gossip technique in scalable and reliable multicast protocols. We have compared gossip protocol with other reliable multicast protocols. Experimental result shows that gossip protocol has better scalability than other.

  16. School-Based Social Skills Training for Preschool-Age Children with Autism Spectrum Disorder

    Science.gov (United States)

    Radley, Keith C.; Hanglein, Jeanine; Arak, Marisa

    2016-01-01

    Individuals with autism spectrum disorder display impairments in social interactions and communication that appear at early ages and result in short- and long-term negative outcomes. As such, there is a need for effective social skills training programs for young children with autism spectrum disorder--particularly interventions capable of being…

  17. mizer: an R package for multispecies, trait-based and community size spectrum ecological modelling

    DEFF Research Database (Denmark)

    Scott, Finlay; Blanchard, Julia L.; Andersen, Ken Haste

    2014-01-01

    1. Size spectrum ecological models are representations of a community of individuals which grow and change trophic level. A key emergent feature of these models is the size spectrum; the total abundance of all individuals that scales negatively with size. The models we focus on are designed...

  18. Remote heartbeat signal detection from visible spectrum recordings based on blind deconvolution

    Science.gov (United States)

    Kaur, Balvinder; Moses, Sophia; Luthra, Megha; Ikonomidou, Vasiliki N.

    2016-05-01

    While recent advances have shown that it is possible to acquire a signal equivalent to the heartbeat from visual spectrum video recordings of the human skin, extracting the heartbeat's exact timing information from it, for the purpose of heart rate variability analysis, remains a challenge. In this paper, we explore two novel methods to estimate the remote cardiac signal peak positions, aiming at a close representation of the R-peaks of the ECG signal. The first method is based on curve fitting (CF) using a modified filtered least mean square (LMS) optimization and the second method is based on system estimation using blind deconvolution (BDC). To prove the efficacy of the developed algorithms, we compared results obtained with the ground truth (ECG) signal. Both methods achieved a low relative error between the peaks of the two signals. This work, performed under an IRB approved protocol, provides initial proof that blind deconvolution techniques can be used to estimate timing information of the cardiac signal closely correlated to the one obtained by traditional ECG. The results show promise for further development of a remote sensing of cardiac signals for the purpose of remote vital sign and stress detection for medical, security, military and civilian applications.

  19. An Effective Strategy to Build Up a Balanced Test Suite for Spectrum-Based Fault Localization

    Directory of Open Access Journals (Sweden)

    Ning Li

    2016-01-01

    Full Text Available During past decades, many automated software faults diagnosis techniques including Spectrum-Based Fault Localization (SBFL have been proposed to improve the efficiency of software debugging activity. In the field of SBFL, suspiciousness calculation is closely related to the number of failed and passed test cases. Studies have shown that the ratio of the number of failed and passed test case has more significant impact on the accuracy of SBFL than the total number of test cases, and a balanced test suite is more beneficial to improving the accuracy of SBFL. Based on theoretical analysis, we proposed an PNF (Passed test cases, Not execute Faulty statement strategy to reduce test suite and build up a more balanced one for SBFL, which can be used in regression testing. We evaluated the strategy making experiments using the Siemens program and Space program. Experiments indicated that our PNF strategy can be used to construct a new test suite effectively. Compared with the original test suite, the new one has smaller size (average 90% test case was reduced in experiments and more balanced ratio of failed test cases to passed test cases, while it has the same statement coverage and fault localization accuracy.

  20. Image and Video based double watermark extraction spread spectrum watermarking in low variance region

    Directory of Open Access Journals (Sweden)

    Mriganka Gogoi

    2013-07-01

    Full Text Available Digital watermarking plays a very important role in copyright protection. It is one of the techniques which are used for safeguarding the origins of the image, audio and video by protecting it against Piracy. This paper proposes a low variance based spread spectrum watermarking for image and video in which the watermark is obtained twice in the receiver. The watermark to be added is a binary image of comparatively smaller size than the Cover Image. Cover Image is divided into number of 8x8 blocks and transform into frequency domain using Discrete Cosine Transform. A gold sequence is added as well as subtracted in each block for each watermark bit. In most cases, researchers has generally used algorithms for extracting single watermark and also it is seen that finding the location of the distorted bit of the watermark due to some attacks is one of the most challenging task. However, in this paper the same watermark is embedded as well as extracted twice with gold code without much distortion of the image and comparing these two watermarks will help in finding the distorted bit. Another feature is that as this algorithm is based on embedding of watermark in low variance region, therefore proper extraction of the watermark is obtained at a lesser modulating factor. The proposed algorithm is very much useful in applications like real-time broad casting, image and video authentication and secure camera system. The experimental results show that the watermarking technique is robust against various attacks.

  1. AN ADAPTIVE MEASUREMENT SCHEME BASED ON COMPRESSED SENSING FOR WIDEBAND SPECTRUM DETECTION IN COGNITIVE WSN

    Institute of Scientific and Technical Information of China (English)

    Xu Xiaorong; Zhang Jianwu; Huang Aiping; Jiang Bin

    2012-01-01

    An Adaptive Measurement Scheme (AMS) is investigated with Compressed Sensing (CS)theory in Cognitive Wireless Sensor Network (C-WSN).Local sensing information is collected via energy detection with Analog-to-Information Converter (AIC) at massive cognitive sensors,and sparse representation is considered with the exploration of spatial temporal correlation structure of detected signals.Adaptive measurement matrix is designed in AMS,which is based on maximum energy subset selection.Energy subset is calculated with sparse transformation of sensing information,and maximum energy subset is selected as the row vector of adaptive measurement matrix.In addition,the measurement matrix is constructed by orthogonalization of those selected row vectors,which also satisfies the Restricted Isometry Property (RIP) in CS theory.Orthogonal Matching Pursuit (OMP) reconstruction algorithm is implemented at sink node to recover original information.Simulation results are performed with the comparison of Random Measurement Scheme (RMS).It is revealed that,signal reconstruction effect based on AMS is superior to conventional RMS Gaussian measurement.Moreover,AMS has better detection performance than RMS at lower compression rate region,and it is suitable for large-scale C-WSN wideband spectrum sensing.

  2. A Putative Blood-Based Biomarker for Autism Spectrum Disorder-Associated Ileocolitis

    Science.gov (United States)

    Walker, Stephen J.; Beavers, Daniel P.; Fortunato, John; Krigsman, Arthur

    2016-01-01

    Gastrointestinal symptoms are common in children with autism spectrum disorder (ASD). A significant proportion of children with ASD and gastrointestinal symptoms have histologic evidence of ileocolitis (inflammation of the terminal ileum and/or colon). We previously reported the molecular characterization of gastrointestinal biopsy tissue from ASD children with ileocolitis (ASDIC+) compared to anatomically similar inflamed tissue from typically developing children with inflammatory bowel disease (IBD; i.e. Crohn’s disease or ulcerative colitis) and typically developing children with gastrointestinal symptoms but no evidence of gastrointestinal mucosal inflammation (TDIC−). ASDIC+ children had a gene expression profile that, while primarily overlapping with known IBD, had distinctive differences. The present study confirms these findings and replicates this molecular characterization in a second cohort of cases (ASDIC+) and controls (TDIC−). In these two separate case/control mucosal-based cohorts, we have demonstrated overlap of 59 differentially expressed transcripts (DETs) unique to inflamed ileocolonic tissue from symptomatic ASDIC+ children. We now report that 9 of these 59 transcripts are also differentially expressed in the peripheral blood of the second cohort of ASDIC+ children. This set of transcripts represents a putative blood-based biomarker for ASD-associated ileocolonic inflammation. PMID:27767057

  3. Convolution power spectrum analysis for FMRI data based on prior image signal.

    Science.gov (United States)

    Zhang, Jiang; Chen, Huafu; Fang, Fang; Liao, Wei

    2010-02-01

    Functional MRI (fMRI) data-processing methods based on changes in the time domain involve, among other things, correlation analysis and use of the general linear model with statistical parametric mapping (SPM). Unlike conventional fMRI data analysis methods, which aim to model the blood-oxygen-level-dependent (BOLD) response of voxels as a function of time, the theory of power spectrum (PS) analysis focuses completely on understanding the dynamic energy change of interacting systems. We propose a new convolution PS (CPS) analysis of fMRI data, based on the theory of matched filtering, to detect brain functional activation for fMRI data. First, convolution signals are computed between the measured fMRI signals and the image signal of prior experimental pattern to suppress noise in the fMRI data. Then, the PS density analysis of the convolution signal is specified as the quantitative analysis energy index of BOLD signal change. The data from simulation studies and in vivo fMRI studies, including block-design experiments, reveal that the CPS method enables a more effective detection of some aspects of brain functional activation, as compared with the canonical PS SPM and the support vector machine methods. Our results demonstrate that the CPS method is useful as a complementary analysis in revealing brain functional information regarding the complex nature of fMRI time series.

  4. Active Probing Feedback based Self Configurable Intelligent Distributed Antenna System

    DEFF Research Database (Denmark)

    Kumar, Ambuj

    challenge through a viable solution that is based on injecting intelligence and services in parallel layers through a Distributed Antenna Systems (DAS) network. This approach would enable the remote sites to acquire intelligence and a resource pool at the same time, thereby managing the network dynamics...... as Self Configurable Distributed Antenna System (SCIDAS)....... collectively as Place Time Coverage & Capacity (PTC2). The dissertation proves through the concept of the PTC2 that the network performance can severely be degraded by the excessive and unrealistic site demands, the network management inefficiency, and the consequence of the accumulation of subscribers...

  5. Scalable video on demand adaptive Internet-based distribution

    CERN Document Server

    Zink, Michael

    2013-01-01

    In recent years, the proliferation of available video content and the popularity of the Internet have encouraged service providers to develop new ways of distributing content to clients. Increasing video scaling ratios and advanced digital signal processing techniques have led to Internet Video-on-Demand applications, but these currently lack efficiency and quality. Scalable Video on Demand: Adaptive Internet-based Distribution examines how current video compression and streaming can be used to deliver high-quality applications over the Internet. In addition to analysing the problems

  6. Verifiable Distribution of Material Goods Based on Cryptology

    Directory of Open Access Journals (Sweden)

    Radomír Palovský

    2015-12-01

    Full Text Available Counterfeiting of material goods is a general problem. In this paper an architecture for verifiable distribution of material goods is presented. This distribution is based on printing such a QR code on goods, which would contain digitally signed serial number of the product, and validity of this digital signature could be verifiable by a customer. Extension consisting of adding digital signatures to revenue stamps used for state-controlled goods is also presented. Discussion on possibilities in making copies leads to conclusion that cryptographic security needs to be completed by technical difficulties of copying.

  7. Distributed collaborative CAD system based on Web Service

    Institute of Scientific and Technical Information of China (English)

    欧阳应秀; 唐敏; 林军呈; 董金祥

    2004-01-01

    This paper presents a novel Web Service based distributed collaborative CAD system employing feature as its collaborative design element and uses XML to define feature operations and communication protocol between the server and the client. To reduce network load and increase response ability of the system, the feature information is updated incrementally on the client. The system supports collaborative designing on heterogeneous platforms. Its framework and communication protocols are analyzed in detail. The experimental results from the developed prototype system showed that it can effectively support collaborative design under the distributed environment.

  8. Location Refinement and Power Coverage Analysis Based on Distributed Antenna

    Institute of Scientific and Technical Information of China (English)

    赵晓楠; 侯春萍; 汪清; 陈华; 浦亮洲

    2016-01-01

    To establish wireless channel suitable for the cabin environment, the power coverage was investigated with distributed antenna system and centralized antenna system based on the actual measurement of channel im-pulse response. The results indicated that the distributed antenna system has more uniform power coverage than the centralized antenna system. The average relative errors of receiving power of both antennas were calculated. The optimal position of the centralized antenna was obtained by Gaussian function refinement, making the system achieve a better transmission power with the same coverage effect, and providing a reference for antenna location in the future real communication in the cabin.

  9. DisBlue+: A distributed annotation-based C# compiler

    Directory of Open Access Journals (Sweden)

    Samir E. AbdelRahman

    2010-06-01

    Full Text Available Many programming languages utilize annotations to add useful information to the program but they still result in more tokens to be compiled and hence slower compilation time. Any current distributed compiler breaks the program into scattered disjoint pieces to speed up the compilation. However, these pieces cooperate synchronously and depend highly on each other. This causes massive overhead since messages, symbols, or codes must be roamed throughout the network. This paper presents two promising compilers named annotation-based C# (Blue+ and distributed annotation-based C# (DisBlue+. The proposed Blue+ annotation is based on axiomatic semantics to replace the if/loop constructs. As the developer tends to use many (complex conditions and repeat them in the program, such annotations reduce the compilation scanning time and increases the whole code readability. Built on the top of Blue+, DisBlue+ presents its proposed distributed concept which is to divide each program class to its prototype and definition, as disjoint distributed pieces, such that each class definition is compiled with only its related compiled prototypes (interfaces. Such concept reduces the amount of code transferred over the network, minimizes the dependencies among the disjoint pieces, and removes any possible synchronization between them. To test their efficiencies, Blue+ and DisBlue+ were verified with large-size codes against some existing compilers namely Javac, DJavac, and CDjava.

  10. Software-Based Challenges of Developing the Future Distribution Grid

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Emma; Kiliccote, Sila; McParland, Charles

    2014-06-01

    distribution grid modeling, and measured data sources are a key missing element . Modeling tools need to be calibrated based on measured grid data to validate their output in varied conditions such as high renewables penetration and rapidly changing topology. In addition, establishing a standardized data modeling format would enable users to transfer data among tools to take advantage of different analysis features. ?

  11. Visible spectrum-based non-contact HRV and dPTT for stress detection

    Science.gov (United States)

    Kaur, Balvinder; Hutchinson, J. Andrew; Ikonomidou, Vasiliki N.

    2017-05-01

    Stress is a major health concern that not only compromises our quality of life, but also affects our physical health and well-being. Despite its importance, our ability to objectively detect and quantify it in a real-time, non-invasive manner is very limited. This capability would have a wide variety of medical, military, and security applications. We have developed a pipeline of image and signal processing algorithms to make such a system practical, which includes remote cardiac pulse detection based on visible spectrum videos and physiological stress detection based on the variability in the remotely detected cardiac signals. First, to determine a reliable cardiac pulse, principal component analysis (PCA) was applied for noise reduction and independent component analysis (ICA) was applied for source selection. To determine accurate cardiac timing for heart rate variability (HRV) analysis, a blind source separation method based least squares (LS) estimate was used to determine signal peaks that were closely related to R-peaks of the electrocardiogram (ECG) signal. A new metric, differential pulse transit time (dPTT), defined as the difference in arrival time of the remotely acquired cardiac signal at two separate distal locations, was derived. It was demonstrated that the remotely acquired metrics, HRV and dPTT, have potential for remote stress detection. The developed algorithms were tested against human subject data collected under two physiological conditions using the modified Trier Social Stress Test (TSST) and the Affective Stress Response Test (ASRT). This research provides evidence that the variability in remotely-acquired blood wave (BW) signals can be used for stress (high and mild) detection, and as a guide for further development of a real-time remote stress detection system based on remote HRV and dPTT.

  12. Transformation of an empirical distribution to normal distribution by the use of Johnson system of translation and symmetrical quantile method

    OpenAIRE

    Ludvík Friebel; Jana Friebelová

    2006-01-01

    This article deals with approximation of empirical distribution to standard normal distribution using Johnson transformation. This transformation enables us to approximate wide spectrum of continuous distributions with a normal distribution. The estimation of parameters of transformation formulas is based on percentiles of empirical distribution. There are derived theoretical probability distribution functions of random variable obtained on the base of backward transformation standard normal ...

  13. Population-based study of genetic variation in individuals with autism spectrum disorders from Croatia

    Directory of Open Access Journals (Sweden)

    Gidaya Nicole

    2010-09-01

    Full Text Available Abstract Background Genome-wide studies on autism spectrum disorders (ASDs have mostly focused on large-scale population samples, but examination of rare variations in isolated populations may provide additional insights into the disease pathogenesis. Methods As a first step in the genetic analysis of ASD in Croatia, we characterized genetic variation in a sample of 103 subjects with ASD and 203 control individuals, who were genotyped using the Illumina HumanHap550 BeadChip. We analyzed the genetic diversity of the Croatian population and its relationship to other populations, the degree of relatedness via Runs of Homozygosity (ROHs, and the distribution of large (>500 Kb copy number variations. Results Combining the Croatian cohort with several previously published populations in the FastME analysis (an alternative to Neighbor Joining revealed that Croatian subjects cluster, as expected, with Southern Europeans; in addition, individuals from the same geographic region within Europe cluster together. Whereas Croatian subjects could be separated from a sample of healthy control subjects of European origin from North America, Croatian ASD cases and controls are well mixed. A comparison of runs of homozygosity indicated that the number and the median length of regions of homozygosity are higher for ASD subjects than for controls (p = 6 × 10-3. Furthermore, analysis of copy number variants found a higher frequency of large chromosomal rearrangements (>2 Mb in ASD cases (5/103 than in ethnically matched control subjects (1/197, p = 0.019. Conclusions Our findings illustrate the remarkable utility of high-density genotype data for subjects from a limited geographic area in dissecting genetic heterogeneity with respect to population and disease related variation.

  14. Higher-dimensional orbital-angular-momentum-based quantum key distribution with mutually unbiased bases

    CSIR Research Space (South Africa)

    Mafu, M

    2013-09-01

    Full Text Available We present an experimental study of higher-dimensional quantum key distribution protocols based on mutually unbiased bases, implemented by means of photons carrying orbital angular momentum. We perform (d + 1) mutually unbiased measurements in a...

  15. An improved TES algorithm based on the corrected ALPHA difference spectrum

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Different from visible signals, thermal infrared radiances depend on both temperature and emissivity. It is a key problem for us to separate temperature and emissivity in thermal infrared remote sensing re- search. Another difficulty encountered in the retrieval of surface temperature is the correction of downwelling sky irradiance, because it is closely related to surface emissivity. When emissivity is un- known, the downwelling sky irradiance is difficult to be removed. In this paper, we introduce a correc- tion term of downwelling sky irradiance developed by Li and Becker into Wien’s approximation, to de- rive an improved ALPHA difference spectrum which is independent of temperature, and furthermore develop a correction term to remove the error of Wien’s approximation. Under the support of the above work, attractive features of Alpha derived emissivity method and ASTER TES algorithm are combined together to acquire a new Improved TES algorithm based on Corrected ALPHA Difference Spectrum (ICADS TES). Because a multi-band inversion technique is applied, and the operations of band ratios and differences are included in the algorithm, it can partly remove the influence of atmosphere and noises. Numerical simulation experiments show that for various combinations of atmosphere, land covers and surface temperatures, the algorithm is applicable and stable. Its accuracy for temperature is 0―1.5 K, and that for emissivity is 0―0.015. Compared with current TES algorithms, our method has clear physical meaning, is easy to be implemented, and is applicable for a wide temperature range and surface types. The results are not influenced by the directional characteristic of emissivity. Because ICADS TES does not need the support of a priori information of surface types, it is also not influenced by the accuracy of classification and the problem of mixture pixels. Compared with our former TES algorithm based on corrected Alpha difference spectra (CADS TES), the new

  16. An improved TES algorithm based on the corrected ALPHA difference spectrum

    Institute of Scientific and Technical Information of China (English)

    TANG ShiHao; LI XiaoWen; WANG JinDi; ZHU QiJiang; ZHANG LiHua

    2007-01-01

    Different from visible signals, thermal infrared radiances depend on both temperature and emissivity. It is a key problem for us to separate temperature and emissivity in thermal infrared remote sensing research. Another difficulty encountered in the retrieval of surface temperature is the correction of downwelling sky irradiance, because it is closely related to surface emissivity. When emissivity is unknown, the downwelling sky irradiance is difficult to be removed. In this paper, we introduce a correction term of downwelling sky irradiance developed by Li and Becker into Wien's approximation, to derive an improved ALPHA difference spectrum which is independent of temperature, and furthermore develop a correction term to remove the error of Wien's approximation. Under the support of the above work, attractive features of Alpha derived emissivity method and ASTER TES algorithm are combined together to acquire a new Improved TES algorithm based on Corrected ALPHA Difference Spectrum (ICADS TES). Because a multi-band inversion technique is applied, and the operations of band ratios and differences are included in the algorithm, it can partly remove the influence of atmosphere and noises. Numerical simulation experiments show that for various combinations of atmosphere, land covers and surface temperatures, the algorithm is applicable and stable. Its accuracy for temperature is 0―1.5 K, and that for emissivity is 0―0.015. Compared with current TES algorithms, our method has clear physical meaning, is easy to be implemented, and is applicable for a wide temperature range and surface types. The results are not influenced by the directional characteristic of emissivity. Because ICADS TES does not need the support of a priori information of surface types, it is also not influenced by the accuracy of classification and the problem of mixture pixels. Compared with our former TES algorithm based on corrected Alpha difference spectra (CADS TES), the new algorithm takes

  17. Size measurement of gold and silver nanostructures based on their extinction spectrum: limitations and extensions

    Directory of Open Access Journals (Sweden)

    A A Ashkarran

    2013-09-01

    Full Text Available  This paper reports on physical principles and the relations between extinction cross section and geometrical properties of silver and gold nanostructures. We introduce some simple relations for determining geometrical properties of silver and gold nanospheres based on the situation of their plasmonic peak. We also applied, investigated and compared the accuracy of these relations using other published works in order to make clear the effects of shape, size distribution and refractive index of particles’ embedding medium. Finally, we extended the equations to non-spherical particles and investigated their accuracy. We found that modified forms of the equations may lead to more exact results for non-spherical metal particles, but for better results, modified equations should depend on shape and size distribution of particles. It seems that these equations are not applicable to particles with corners sharper than cubes' corners i.e. nanostructures with spatial angles less than π/2 sr.

  18. A Distributed Agent—based Architecture for Dynamic Services

    Institute of Scientific and Technical Information of China (English)

    HarveyB.Newman; IosifC.Legrand; 等

    2001-01-01

    Aprototype system for agent-based distributed dynamic services that will be applied to the development of Data Grids for high-energy physics is presented.The agent-based systems we are designing and develogping gather,disseminate and coordinate configuration ,time-dependent state and other information in the Grid system as a whole.These systems are being developed as an enabling technology for workflow-management and other forms of end-to-end Grid system monitoring and management.This prototype is being developed in Java and is based on the JINI,Mobile Agents,Self-Organizing Neural Networks.

  19. AN IMAGE RETRIEVAL METHOD BASED ON SPATIAL DISTRIBUTION OF COLOR

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Color histogram is now widely used in image retrieval. Color histogram-based image retrieval methods are simple and efficient but without considering the spatial distribution information of the color. To overcome the shortcoming of conventional color histogram-based image retrieval methods, an image retrieval method based on Radon Transform (RT) is proposed. In order to reduce the computational complexity,wavelet decomposition is used to compress image data. Firstly, images are decomposed by Mallat algorithm.The low-frequency components are then projected by RT to generate the spatial color feature. Finally the moment feature matrices which are saved along with original images are obtained. Experimental results show that the RT based retrieval is more accurate and efficient than traditional color histogram-based method in case that there are obvious objects in images. Further more, RT based retrieval runs significantly faster than the traditional color histogram methods.

  20. Distribution network planning algorithm based on Hopfield neural network

    Institute of Scientific and Technical Information of China (English)

    GAO Wei-xin; LUO Xian-jue

    2005-01-01

    This paper presents a new algorithm based on Hopfield neural network to find the optimal solution for an electric distribution network. This algorithm transforms the distribution power network-planning problem into a directed graph-planning problem. The Hopfield neural network is designed to decide the in-degree of each node and is in combined application with an energy function. The new algorithm doesn't need to code city streets and normalize data, so the program is easier to be realized. A case study applying the method to a district of 29 street proved that an optimal solution for the planning of such a power system could be obtained by only 26 iterations. The energy function and algorithm developed in this work have the following advantages over many existing algorithms for electric distribution network planning: fast convergence and unnecessary to code all possible lines.

  1. GIS-based poverty and population distribution analysis in China

    Science.gov (United States)

    Cui, Jing; Wang, Yingjie; Yan, Hong

    2009-07-01

    Geographically, poverty status is not only related with social-economic factors but also strongly affected by geographical environment. In the paper, GIS-based poverty and population distribution analysis method is introduced for revealing their regional differences. More than 100000 poor villages and 592 national key poor counties are chosen for the analysis. The results show that poverty distribution tends to concentrate in most of west China and mountainous rural areas of mid China. Furthermore, the fifth census data are overlaid to those poor areas in order to gain its internal diversity of social-economic characteristics. By overlaying poverty related social-economic parameters, such as sex ratio, illiteracy, education level, percentage of ethnic minorities, family composition, finding shows that poverty distribution is strongly correlated with high illiteracy rate, high percentage minorities, and larger family member.

  2. Exploring Urban Taxi Drivers’ Activity Distribution Based on GPS Data

    Directory of Open Access Journals (Sweden)

    Xiaowei Hu

    2014-01-01

    Full Text Available With the rapid development of information communication technology and data mining technology, we can obtain taxi vehicle’s real time operation status through the large-scale taxi GPS trajectories data and explore the drivers’ activity distribution characteristics. Based on the 204 continuous hours of 3198 taxi vehicles’ operation data of Shenzhen, China, this paper analyzed the urban taxi driver’s activity distribution characteristics from different temporal and spatial levels. In the time level, we identified the difference with taxi daily operation pattern (weekday versus weekends, continuous time in one day, passengers in vehicle time, and taxi drivers’ operation frequency; in the space level, we explored the taxi driver’s searching pattern, including searching activity space distribution and the relationship between the pick-up locations and the drop-off locations. This research can be helpful for urban taxi drivers’ operation and behavior pattern identification, as well as the contribution to the geographical activity space analysis.

  3. Cluster-based distributed face tracking in camera networks.

    Science.gov (United States)

    Yoder, Josiah; Medeiros, Henry; Park, Johnny; Kak, Avinash C

    2010-10-01

    In this paper, we present a distributed multicamera face tracking system suitable for large wired camera networks. Unlike previous multicamera face tracking systems, our system does not require a central server to coordinate the entire tracking effort. Instead, an efficient camera clustering protocol is used to dynamically form groups of cameras for in-network tracking of individual faces. The clustering protocol includes cluster propagation mechanisms that allow the computational load of face tracking to be transferred to different cameras as the target objects move. Furthermore, the dynamic election of cluster leaders provides robustness against system failures. Our experimental results show that our cluster-based distributed face tracker is capable of accurately tracking multiple faces in real-time. The overall performance of the distributed system is comparable to that of a centralized face tracker, while presenting the advantages of scalability and robustness.

  4. Distributed Frequency Control of Prosumer-Based Electric Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, MH; Costello, Z; Feizollahi, MJ; Grijalva, S; Egerstedt, M

    2014-11-01

    In this paper, we propose a distributed frequency regulation framework for prosumer-based electric energy systems, where a prosumer (producer-consumer) is defined as an intelligent agentwhich can produce, consume, and/or store electricity. Despite the frequency regulators being distributed, stability can be ensured while avoiding inter-area oscillations using a limited control effort. To achieve this, a fully distributed one-step model-predictive control protocol is proposed and analyzed, whereby each prosumer communicates solely with its neighbors in the network. The efficacy of the proposed frequency regulation framework is shown through simulations on two real-world electric energy systems of different scale and complexity. We show that prosumers can indeed bring frequency and power deviations to their desired values after small perturbations.

  5. Performance Recognition for Sulphur Flotation Process Based on Froth Texture Unit Distribution

    Directory of Open Access Journals (Sweden)

    Mingfang He

    2013-01-01

    Full Text Available As an important indicator of flotation performance, froth texture is believed to be related to operational condition in sulphur flotation process. A novel fault detection method based on froth texture unit distribution (TUD is proposed to recognize the fault condition of sulphur flotation in real time. The froth texture unit number is calculated based on texture spectrum, and the probability density function (PDF of froth texture unit number is defined as texture unit distribution, which can describe the actual textual feature more accurately than the grey level dependence matrix approach. As the type of the froth TUD is unknown, a nonparametric kernel estimation method based on the fixed kernel basis is proposed, which can overcome the difficulty when comparing different TUDs under various conditions is impossible using the traditional varying kernel basis. Through transforming nonparametric description into dynamic kernel weight vectors, a principle component analysis (PCA model is established to reduce the dimensionality of the vectors. Then a threshold criterion determined by the TQ statistic based on the PCA model is proposed to realize the performance recognition. The industrial application results show that the accurate performance recognition of froth flotation can be achieved by using the proposed method.

  6. A precise clock distribution network for MRPC-based experiments

    Science.gov (United States)

    Wang, S.; Cao, P.; Shang, L.; An, Q.

    2016-06-01

    In high energy physics experiments, the MRPC (Multi-Gap Resistive Plate Chamber) detectors are widely used recently which can provide higher-resolution measurement for particle identification. However, the application of MRPC detectors leads to a series of challenges in electronics design with large number of front-end electronic channels, especially for distributing clock precisely. To deal with these challenges, this paper presents a universal scheme of clock transmission network for MRPC-based experiments with advantages of both precise clock distribution and global command synchronization. For precise clock distributing, the clock network is designed into a tree architecture with two stages: the first one has a point-to-multipoint long range bidirectional distribution with optical channels and the second one has a fan-out structure with copper link inside readout crates. To guarantee the precision of clock frequency or phase, the r-PTP (reduced Precision Time Protocol) and the DDMTD (digital Dual Mixer Time Difference) methods are used for frequency synthesis, phase measurement and adjustment, which is implemented by FPGA (Field Programmable Gate Array) in real-time. In addition, to synchronize global command execution, based upon this clock distribution network, synchronous signals are coded with clock for transmission. With technique of encoding/decoding and clock data recovery, signals such as global triggers or system control commands, can be distributed to all front-end channels synchronously, which greatly simplifies the system design. The experimental results show that both the clock jitter (RMS) and the clock skew can be less than 100 ps.

  7. Inhomogeneity Based Characterization of Distribution Patterns on the Plasma Membrane.

    Directory of Open Access Journals (Sweden)

    Laura Paparelli

    2016-09-01

    Full Text Available Cell surface protein and lipid molecules are organized in various patterns: randomly, along gradients, or clustered when segregated into discrete micro- and nano-domains. Their distribution is tightly coupled to events such as polarization, endocytosis, and intracellular signaling, but challenging to quantify using traditional techniques. Here we present a novel approach to quantify the distribution of plasma membrane proteins and lipids. This approach describes spatial patterns in degrees of inhomogeneity and incorporates an intensity-based correction to analyze images with a wide range of resolutions; we have termed it Quantitative Analysis of the Spatial distributions in Images using Mosaic segmentation and Dual parameter Optimization in Histograms (QuASIMoDOH. We tested its applicability using simulated microscopy images and images acquired by widefield microscopy, total internal reflection microscopy, structured illumination microscopy, and photoactivated localization microscopy. We validated QuASIMoDOH, successfully quantifying the distribution of protein and lipid molecules detected with several labeling techniques, in different cell model systems. We also used this method to characterize the reorganization of cell surface lipids in response to disrupted endosomal trafficking and to detect dynamic changes in the global and local organization of epidermal growth factor receptors across the cell surface. Our findings demonstrate that QuASIMoDOH can be used to assess protein and lipid patterns, quantifying distribution changes and spatial reorganization at the cell surface. An ImageJ/Fiji plugin of this analysis tool is provided.

  8. Inhomogeneity Based Characterization of Distribution Patterns on the Plasma Membrane.

    Science.gov (United States)

    Paparelli, Laura; Corthout, Nikky; Pavie, Benjamin; Wakefield, Devin L; Sannerud, Ragna; Jovanovic-Talisman, Tijana; Annaert, Wim; Munck, Sebastian

    2016-09-01

    Cell surface protein and lipid molecules are organized in various patterns: randomly, along gradients, or clustered when segregated into discrete micro- and nano-domains. Their distribution is tightly coupled to events such as polarization, endocytosis, and intracellular signaling, but challenging to quantify using traditional techniques. Here we present a novel approach to quantify the distribution of plasma membrane proteins and lipids. This approach describes spatial patterns in degrees of inhomogeneity and incorporates an intensity-based correction to analyze images with a wide range of resolutions; we have termed it Quantitative Analysis of the Spatial distributions in Images using Mosaic segmentation and Dual parameter Optimization in Histograms (QuASIMoDOH). We tested its applicability using simulated microscopy images and images acquired by widefield microscopy, total internal reflection microscopy, structured illumination microscopy, and photoactivated localization microscopy. We validated QuASIMoDOH, successfully quantifying the distribution of protein and lipid molecules detected with several labeling techniques, in different cell model systems. We also used this method to characterize the reorganization of cell surface lipids in response to disrupted endosomal trafficking and to detect dynamic changes in the global and local organization of epidermal growth factor receptors across the cell surface. Our findings demonstrate that QuASIMoDOH can be used to assess protein and lipid patterns, quantifying distribution changes and spatial reorganization at the cell surface. An ImageJ/Fiji plugin of this analysis tool is provided.

  9. Aging based maintenance and reinvestment scheduling of electric distribution

    Energy Technology Data Exchange (ETDEWEB)

    Korpijarvi, J.

    2012-07-01

    The maintenance of electric distribution network is a topical question for distribution system operators because of increasing significance of failure costs. In this dissertation the maintenance practices of the distribution system operators are analyzed and a theory for scheduling maintenance activities and reinvestment of distribution components is created. The scheduling is based on the deterioration of components and the increasing failure rates due to aging. The dynamic programming algorithm is used as a solving method to maintenance problem which is caused by the increasing failure rates of the network. The other impacts of network maintenance like environmental and regulation reasons are not included to the scope of this thesis. Further the tree trimming of the corridors and the major disturbance of the network are not included to the problem optimized in this thesis. For optimizing, four dynamic programming models are presented and the models are tested. Programming is made in VBA-language to the computer. For testing two different kinds of test networks are used. Because electric distribution system operators want to operate with bigger component groups, optimal timing for component groups is also analyzed. A maintenance software package is created to apply the presented theories in practice. An overview of the program is presented (orig.)

  10. Sensitivity-Based Model of Low Voltage Distribution Systems with Distributed Energy Resources

    Directory of Open Access Journals (Sweden)

    Anna Rita Di Fazio

    2016-10-01

    Full Text Available A key issue in Low Voltage(LV distribution systems is to identify strategies for the optimal management and control in the presence of Distributed Energy Resources (DERs. To reduce the number of variables to be monitored and controlled, virtual levels of aggregation, called Virtual Microgrids (VMs, are introduced and identified by using new models of the distribution system. To this aim, this paper, revisiting and improving the approach outlined in a conference paper, presents a sensitivity-based model of an LV distribution system, supplied by a Medium/Low Voltage (MV/LV substation and composed by several feeders, which is suitable for the optimal management and control of the grid and for VM definition. The main features of the proposed method are: it evaluates the sensitivity coefficients in a closed form; it provides an overview of the sensitivity of the network to the variations of each DER connected to the grid; and it presents a limited computational burden. A comparison of the proposed method with both the exact load flow solutions and a perturb-and-observe method is discussed in a case study. Finally, the method is used to evaluate the impact of the DERs on the nodal voltages of the network.

  11. Neural activity based biofeedback therapy for Autism spectrum disorder through wearable wireless textile EEG monitoring system

    Science.gov (United States)

    Sahi, Ahna; Rai, Pratyush; Oh, Sechang; Ramasamy, Mouli; Harbaugh, Robert E.; Varadan, Vijay K.

    2014-04-01

    Mu waves, also known as mu rhythms, comb or wicket rhythms are synchronized patterns of electrical activity involving large numbers of neurons, in the part of the brain that controls voluntary functions. Controlling, manipulating, or gaining greater awareness of these functions can be done through the process of Biofeedback. Biofeedback is a process that enables an individual to learn how to change voluntary movements for purposes of improving health and performance through the means of instruments such as EEG which rapidly and accurately 'feedback' information to the user. Biofeedback is used for therapeutic purpose for Autism Spectrum Disorder (ASD) by focusing on Mu waves for detecting anomalies in brain wave patterns of mirror neurons. Conventional EEG measurement systems use gel based gold cup electrodes, attached to the scalp with adhesive. It is obtrusive and wires sticking out of the electrodes to signal acquisition system make them impractical for use in sensitive subjects like infants and children with ASD. To remedy this, sensors can be incorporated with skull cap and baseball cap that are commonly used for infants and children. Feasibility of Textile based Sensor system has been investigated here. Textile based multi-electrode EEG, EOG and EMG monitoring system with embedded electronics for data acquisition and wireless transmission has been seamlessly integrated into fabric of these items for continuous detection of Mu waves. Textile electrodes were placed on positions C3, CZ, C4 according to 10-20 international system and their capability to detect Mu waves was tested. The system is ergonomic and can potentially be used for early diagnosis in infants and planning therapy for ASD patients.

  12. Developmental Regression in Children with an Autism Spectrum Disorder Identified by a Population-Based Surveillance System

    Science.gov (United States)

    Wiggins, Lisa D.; Rice, Catherine E.; Baio, Jon

    2009-01-01

    This study evaluated the phenomenon of autistic regression using population-based data. The sample comprised 285 children who met the autism spectrum disorder (ASD) case definition within an ongoing surveillance program. Results indicated that children with a previously documented ASD diagnosis had higher rates of autistic regression than children…

  13. Use of Computer-Based Interventions to Teach Communication Skills to Children with Autism Spectrum Disorders: A Systematic Review

    Science.gov (United States)

    Ramdoss, Sathiyaprakash; Lang, Russell; Mulloy, Austin; Franco, Jessica; O'Reilly, Mark; Didden, Robert; Lancioni, Giulio

    2011-01-01

    The purpose of this review is to provide a systematic analysis of studies involving the use of computer-based interventions (CBI) to teach communication skills to children with autism spectrum disorders (ASD). This review evaluates intervention outcomes, appraises the certainty of evidence, and describes software and system requirements for each…

  14. Use of Computer-Based Interventions to Improve Literacy Skills in Students with Autism Spectrum Disorders: A Systematic Review

    Science.gov (United States)

    Ramdoss, Sathiyaprakash; Mulloy, Austin; Lang, Russell; O'Reilly, Mark; Sigafoos, Jeff; Lancioni, Giulio; Didden, Robert; El Zein, Farah

    2011-01-01

    The purpose of this review is to provide a systematic analysis of studies investigating computer-based interventions (CBI) to improve literacy skills (e.g., reading, writing, and vocabulary) in students with autism spectrum disorders (ASD). This review synthesizes intervention outcomes, appraises the certainty of evidence, and describes software…

  15. Use of computer-based interventions to teach communication skills to individuals with autism spectrum disorders: A systematic review

    NARCIS (Netherlands)

    Ramdoss, S.; Lang, R.; Mulloy, A.; Franco, J.; O'Reilly, M.F.; Didden, H.C.M.; Lancioni, G.E.

    2011-01-01

    The purpose of this review is to provide a systematic analysis of studies involving the use of computer-based interventions (CBI) to teach communication skills to children with autism spectrum disorders (ASD). This review evaluates intervention outcomes, appraises the certainty of evidence, and desc

  16. School-Based Interventions Targeting Challenging Behaviors Exhibited by Young Children with Autism Spectrum Disorder: A Systematic Literature Review

    Science.gov (United States)

    Martinez, Jose R.; Werch, Brittany L.; Conroy, Maureen A.

    2016-01-01

    The purpose of this review was to critically examine and summarize the impact of school-based interventions designed to decrease challenging behaviors in young children with Autism Spectrum Disorder (ASD). Reviewed studies employed a single-case experimental design, targeted challenging behaviors, included children 3-8 years old with ASD, and took…

  17. Use of computer-based interventions to improve literacy skills in students with autism spectrum disorders: A systematic review

    NARCIS (Netherlands)

    Ramdoss, S.; Mulloy, A.; Lang, R.; O'Reilly, M.F.; Sigafoos, J.; Lancioni, G.E.; Didden, H.C.M.; El Zein, F.

    2011-01-01

    The purpose of this review is to provide a systematic analysis of studies investigating computer-based interventions (CBI) to improve literacy skills (e.g., reading, writing, and vocabulary) in students with autism spectrum disorders (ASD). This review synthesizes intervention outcomes, appraises th

  18. Changes in Anxiety Following a Randomized Control Trial of a Theatre-Based Intervention for Youth with Autism Spectrum Disorder

    Science.gov (United States)

    Corbett, Blythe A.; Blain, Scott D.; Ioannou, Sara; Balser, Maddie

    2017-01-01

    Increased anxiety and stress are frequently found in children with autism spectrum disorder and are associated with social challenges. Recently, we reported changes in social competence following peer-mediated, theatre-based intervention. The purpose of this study was to examine the impact of the intervention on reducing anxiety and stress.…

  19. Evaluation of a Web-Based Professional Development Program (Project ACE) for Teachers of Children with Autism Spectrum Disorders

    Science.gov (United States)

    Rakap, Salih; Jones, Hazel A.; Emery, Alice Kaye

    2015-01-01

    This article describes the development, implementation, and second-year evaluation of Project Autism Competencies for Endorsement (ACE), a web-based professional development (PD) program that is designed to train teachers currently working in the field to meet the unique and diverse needs of children with autism spectrum disorders (ASDs). A…

  20. Increased Risk for Substance Use-Related Problems in Autism Spectrum Disorders: A Population-Based Cohort Study

    Science.gov (United States)

    Butwicka, Agnieszka; Långström, Niklas; Larsson, Henrik; Lundström, Sebastian; Serlachius, Eva; Almqvist, Catarina; Frisén, Louise; Lichtenstein, Paul

    2017-01-01

    Despite limited and ambiguous empirical data, substance use-related problems have been assumed to be rare among patients with autism spectrum disorders (ASD). Using Swedish population-based registers we identified 26,986 individuals diagnosed with ASD during 1973-2009, and their 96,557 non-ASD relatives. ASD, without diagnosed comorbidity of…

  1. Low but Increasing Prevalence of Autism Spectrum Disorders in a French Area from Register-Based Data

    Science.gov (United States)

    van Bakel, Marit Maria; Delobel-Ayoub, Malika; Cans, Christine; Assouline, Brigitte; Jouk, Pierre-Simon; Raynaud, Jean-Philippe; Arnaud, Catherine

    2015-01-01

    Register-based prevalence rates of childhood autism (CA), Asperger's syndrome (AS) and other autism spectrum disorders (ASD) were calculated among children aged 7 years old of the 1997-2003 birth cohorts, living in four counties in France. The proportion of children presenting comorbidities was reported. 1123 children with ASD were recorded (M/F…

  2. Teaching Advanced Operation of an iPod-Based Speech-Generating Device to Two Students with Autism Spectrum Disorders

    Science.gov (United States)

    Achmadi, Donna; Kagohara, Debora M.; van der Meer, Larah; O'Reilly, Mark F.; Lancioni, Giulio E.; Sutherland, Dean; Lang, Russell; Marschik, Peter B.; Green, Vanessa A.; Sigafoos, Jeff

    2012-01-01

    We evaluated a program for teaching two adolescents with autism spectrum disorders (ASD) to perform more advanced operations on an iPod-based speech-generating device (SGD). The effects of the teaching program were evaluated in a multiprobe multiple baseline across participants design that included two intervention phases. The first intervention…

  3. Training Teachers in Evidence-Based Practice for Individuals with Autism Spectrum Disorder: A Review of the Literature

    Science.gov (United States)

    Alexander, Jennifer L.; Ayres, Kevin M.; Smith, Katie A.

    2015-01-01

    In this review, the authors include 23 studies where researchers experimentally evaluated training for teachers of students with Autism Spectrum Disorder (ASD). Authors summarized qualitative information on study and participant characteristics. Next, variables related to teacher practice and student learning targets were categorized based on…

  4. ABA-Based Programs for Children Diagnosed with Autism Spectrum Disorder: Parental and Professional Experiences at School and at Home

    Science.gov (United States)

    Dillenburger, Karola; Keenan, Mickey; Doherty, Alvin; Byrne, Tony; Gallagher, Stephen

    2012-01-01

    Having a child diagnosed with Autism Spectrum Disorder (ASD) poses a range of challenges to families, many of which can be addressed through appropriate intervention. A study of parental (n = 95) and professional (n = 67) experiences was carried out in relation to two settings: (a) schools that provided intensive interventions based on the science…

  5. The Power Card Strategy: Strength-Based Intervention to Increase Direction Following of Children with Autism Spectrum Disorder

    Science.gov (United States)

    Campbell, Abbi; Tincani, Matt

    2011-01-01

    The Power Card strategy is a strength-based intervention to promote social skills of children with autism spectrum disorders (ASD) by capitalizing on their special interests. Although preliminary studies have shown that the Power Card strategy is a promising approach to teach social skills, additional research is needed. The purpose of this study…

  6. Detecting Abnormal Word Utterances in Children With Autism Spectrum Disorders: Machine-Learning-Based Voice Analysis Versus Speech Therapists.

    Science.gov (United States)

    Nakai, Yasushi; Takiguchi, Tetsuya; Matsui, Gakuyo; Yamaoka, Noriko; Takada, Satoshi

    2017-10-01

    Abnormal prosody is often evident in the voice intonations of individuals with autism spectrum disorders. We compared a machine-learning-based voice analysis with human hearing judgments made by 10 speech therapists for classifying children with autism spectrum disorders ( n = 30) and typical development ( n = 51). Using stimuli limited to single-word utterances, machine-learning-based voice analysis was superior to speech therapist judgments. There was a significantly higher true-positive than false-negative rate for machine-learning-based voice analysis but not for speech therapists. Results are discussed in terms of some artificiality of clinician judgments based on single-word utterances, and the objectivity machine-learning-based voice analysis adds to judging abnormal prosody.

  7. Steady shear flow thermodynamics based on a canonical distribution approach.

    Science.gov (United States)

    Taniguchi, Tooru; Morriss, Gary P

    2004-11-01

    A nonequilibrium steady-state thermodynamics to describe shear flow is developed using a canonical distribution approach. We construct a canonical distribution for shear flow based on the energy in the moving frame using the Lagrangian formalism of the classical mechanics. From this distribution, we derive the Evans-Hanley shear flow thermodynamics, which is characterized by the first law of thermodynamics dE=TdS-Qdgamma relating infinitesimal changes in energy E, entropy S, and shear rate gamma with kinetic temperature T. Our central result is that the coefficient Q is given by Helfand's moment for viscosity. This approach leads to thermodynamic stability conditions for shear flow, one of which is equivalent to the positivity of the correlation function for Q. We show the consistency of this approach with the Kawasaki distribution function for shear flow, from which a response formula for viscosity is derived in the form of a correlation function for the time-derivative of Q. We emphasize the role of the external work required to sustain the steady shear flow in this approach, and show theoretically that the ensemble average of its power W must be non-negative. A nonequilibrium entropy, increasing in time, is introduced, so that the amount of heat based on this entropy is equal to the average of W. Numerical results from nonequilibrium molecular-dynamics simulation of two-dimensional many-particle systems with soft-core interactions are presented which support our interpretation.

  8. Metadata based management and sharing of distributed biomedical data

    Science.gov (United States)

    Vergara-Niedermayr, Cristobal; Liu, Peiya

    2014-01-01

    Biomedical research data sharing is becoming increasingly important for researchers to reuse experiments, pool expertise and validate approaches. However, there are many hurdles for data sharing, including the unwillingness to share, lack of flexible data model for providing context information, difficulty to share syntactically and semantically consistent data across distributed institutions, and high cost to provide tools to share the data. SciPort is a web-based collaborative biomedical data sharing platform to support data sharing across distributed organisations. SciPort provides a generic metadata model to flexibly customise and organise the data. To enable convenient data sharing, SciPort provides a central server based data sharing architecture with a one-click data sharing from a local server. To enable consistency, SciPort provides collaborative distributed schema management across distributed sites. To enable semantic consistency, SciPort provides semantic tagging through controlled vocabularies. SciPort is lightweight and can be easily deployed for building data sharing communities. PMID:24834105

  9. Distributed Sparse Spectrum Detection in Multihop Cognitive Underwater Acoustict Communication Networks%多跳认知水声通信中的分布式稀疏频谱检测算法

    Institute of Scientific and Technical Information of China (English)

    左加阔; 陶文凤; 包永强; 方世良; 赵力; 邹采荣

    2013-01-01

    水声信道常表现为严重的频率选择性衰落、低的声波传播速度和严重的多径效应等。这些特性使得认知水声通信中的频谱检测变得非常困难。除此之外,水声通信网络通常为自组织网络,缺少融合中心,而基于融合中心的频谱检测算法需要将各个认知用户的感知数据传送到融合中心,因此该方法在认知水声通信中是不可行的。与认知无线电类似,由于低的频谱使用率,认知水声通信中的频谱也是稀疏的。考虑到水声信道的特殊性,基于压缩感知理论,该文对认知无线电中的压缩频谱检测算法进行了改进,提出了两种不同情况下(已知水声信道状态信息和未知水声信道状态信息)的适用于认知水声通信的分布式稀疏频谱检测算法。通过近邻认知用户之间的合作,这两种算法利用空间分集增益和联合稀疏特性来提高算法的频谱检测性能。通过分布式计算和局部优化,新算法使得认知用户与其近邻认知用户之间只需进行少量的数据交互。仿真实验结果证明了该文提出的算法在检测认知水声通信系统中频谱空洞的有效性。%Since the underwater acoustic channel suffers often severe frequency-dependent attenuation, low speed of wave propagation and excessive multipath delay spread, the implementation of spectrum detection in Cognitive Underwater Acoustic Communication (CUAC) becomes very difficult. Beside, there is no fusion center in Ad hoc underwater acoustic communication networks. Therefore, the centralized spectrum detection methods in CUAC are not available. Similar to Cognitive Radio (CR), since the spectrum utility in CUAC is also low, the spectrum is sparse. Based on compressed sensing and considering the specificity of underwater acoustic, compressed spectrum detection algorithm for cognitive radio is improved, and then two distributed cooperative spectrum detection methods

  10. [The new method monitoring agricultural drought based on SWIR-Red spectrum feature space].

    Science.gov (United States)

    Feng, Hai-Xia; Qin, Qi-Ming; Li, Bin-Yong; Liu, Fang; Jiang, Hong-Bo; Dong, Heng; Wang, Jin-Liang; Liu, Ming-Chao; Zhang, Ning

    2011-11-01

    Drought was a chronic, natural disaster, and Remote sensing drought monitoring had become a potential research field. In the present, short-wave infrared and red bands which sensitive to moisture variation were selected to monitor farmland drought conditions by analyzing the spectral characteristics of vegetation and soil. The goal of this paper was to provide a new method of drought monitoring--normalized drought monitoring index (NPDI), based on new constructed spectrum feature space by the difference of SWIR and Red and the sum of SWIR and Red. Field surveyed soil moisture verified NPDI model, and the result showed that NDPI and MPDI model could effectively monitor agricultural drought, and that had high correlation with soil moisture. The R2 was 0.583 and 0.438 with soil water of 10 cm. The monitoring effect of NPDI model was better than the MPDL. This model was further improvement to PDI and MPDI, and it could monitor the drought condition of different vegetation coverage and whole growing season. It has high application potential and popularization value.

  11. Characterization of the interface roughness of coatings based on ultrasonic reflection coefficient amplitude spectrum

    Science.gov (United States)

    Ma, Zhiyuan; Zhang, Wei; Gao, Jianying; Lin, Li; Krishnaswamy, Sridhar

    2017-02-01

    In order to nondestructively characterize the interface roughness of coatings effectively, the ultrasonic reflection coefficient amplitude spectrum (URCAS) involving interface roughness was derived based on the phase-screen approximation theory. The interface roughness was determined by a two-parameter inversion combined with a cross-correlation algorithm. For homogeneous coatings, the effects of ultrasonic wavelength λ, beam coverage, and shape variations of the coating on the roughness measurements were analyzed through numerical calculation. A series of simulations indicated that measurement errors were less than 10% when the relationship between interface roughness and wavelength satisfied Rq=1.5%λ˜11%λ approximately. Ultrasonic experiments were carried out on standard roughness specimens utilizing water immersion, flat transducers. The roughness Rq of the standard roughness specimens were 8.5 µm, 14.2 µm, and 28.6 µm measured by confocal laser scanning microscope (CLSM), respectively. Experimental results show that the roughness of standard roughness specimens obtained by the proposed ultrasonic measurement are in good agreement with the CLSM observations, and the relative errors are less than 8.5%.

  12. Energy Harvesting-based Spectrum Access with Incremental Cooperation, Relay Selection and Hardware Noises

    Directory of Open Access Journals (Sweden)

    T. N. Nguyen

    2017-04-01

    Full Text Available In this paper, we propose an energy harvesting (EH-based spectrum access model in cognitive radio (CR network. In the proposed scheme, one of available secondary transmitters (STs helps a primary transmitter (PT forward primary signals to a primary receiver (PR. Via the cooperation, the selected ST finds opportunities to access licensed bands to transmit secondary signals to its intended secondary receiver (SR. Secondary users are assumed to be mobile, hence, optimization of energy consumption for these users is interested. The EH STs have to harvest energy from the PT's radio-frequency (RF signals to serve the PT-PR communication as well as to transmit their signals. The proposed scheme employs incremental relaying technique in which the PR only requires the assistance from the STs when the transmission between PT and PR is not successful. Moreover, we also investigate impact of hardware impairments on performance of the primary and secondary networks. For performance evaluation, we derive exact and lower-bound expressions of outage probability (OP over Rayleigh fading channel. Monte-Carlo simulations are performed to verify the theoretical results. The results present that the outage performance of both networks can be enhanced by increasing the number of the ST-SR pairs. In addition, it is also shown that fraction of time used for EH, positions of the secondary users and the hardware-impairment level significantly impact on the system performance.

  13. Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and First Results

    CERN Document Server

    Wang, Yuming; Zhang, Jie; Liu, Kai; Liu, Rui; Shen, Chenglong; Chamberlin, Phillip C

    2015-01-01

    SDO/EVE provide rich information of the thermodynamic processes of solar activities, particularly of solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. Reading from the charts, we are able to easily recognize if there is a late phase following a main phase of a flare, and able to learn the begin, peak and end times of the flare as well as the drift of the temperature, i.e., the cooling rate, of the heated plasma during the flare. Through four M-class flares of different types, we illustrate which thermodynamic information can be revealed from the TDS charts. Further, we investigate the TDS charts of all the flares greater than M5.0, and some interesting results are achieved. First, there are two distinct drift patterns, called Type I and Type II. For Type I flares, the enhanced emission drifts from high to low temperture, whereas for Type II flares, the drift is somewhat reversed, suggesting a more violent and durable heating during Type I...

  14. Spectrum of pediatric cancers in Mozambique: an analysis of hospital and population-based data.

    Science.gov (United States)

    Carreira, Helena; Lorenzoni, Cesaltina; Carrilho, Carla; Ferro, Josefo; Sultane, Thebora; Garcia, Carlos; Amod, Faizana; Augusto, Orvalho; Silva-Matos, Carla; La Vecchia, Carlo; Lunet, Nuno

    2014-09-01

    The existing data provide little detail about the epidemiology of pediatric cancers in Mozambique. We aimed at characterizing the spectrum of pediatric cancers (0-14 years) diagnosed in Mozambique in two different calendar periods. Data were obtained from the Pathology Department of the Maputo Central Hospital (DP-HCM) (1999-2000 and 2009-2010), which receives virtually all samples for histopathological diagnosis in Maputo, with the exception of leukemia, and from the population-based Cancer Registry of Beira (2009-2010). In 1999-2000, the DP-HCM diagnosed 61 cancers. Burkitt lymphoma, malignant bone tumors, and rhabdomyosarcomas accounted for 24.6%, 11.5%, and 9.8% of all cases, respectively. In 2009-2010, the number of cancers increased to 150, reflecting a two- to threefold increase in the proportion of Kaposi sarcomas, non-Hodgkin lymphomas, nephroblastomas, and neuroblastomas. In 2009-2010, the Cancer Registry of Beira registered 34 cases, corresponding to an incidence rate of 9.7/100,000 inhabitants in this age group; Kaposi sarcomas, lymphomas, retinoblastomas, and nephroblastomas accounted for 29.4%, 23.5%, 8.8%, and 8.8% of all cases, respectively. These data show that pediatric cancers account for an appreciable burden in Mozambique, probably reflecting a high frequency of HIV-associated cancers and improved access to diagnosis, and highlight the potential for improving surveillance in this low resource setting.

  15. Diesel engine noise source identification based on EEMD, coherent power spectrum analysis and improved AHP

    Science.gov (United States)

    Zhang, Junhong; Wang, Jian; Lin, Jiewei; Bi, Fengrong; Guo, Qian; Chen, Kongwu; Ma, Liang

    2015-09-01

    As the essential foundation of noise reduction, many noise source identification methods have been developed and applied to engineering practice. To identify the noise source in the board-band frequency of different engine parts at various typical speeds, this paper presents an integrated noise source identification method based on the ensemble empirical mode decomposition (EEMD), the coherent power spectrum analysis, and the improved analytic hierarchy process (AHP). The measured noise is decomposed into several IMFs with physical meaning, which ensures the coherence analysis of the IMFs and the vibration signals are meaningful. An improved AHP is developed by introducing an objective weighting function to replace the traditional subjective evaluation, which makes the results no longer dependent on the subject performances and provides a better consistency in the meantime. The proposed noise identification model is applied to identifying a diesel engine surface radiated noise. As a result, the frequency-dependent contributions of different engine parts to different test points at different speeds are obtained, and an overall weight order is obtained as oil pan  >  left body  >  valve chamber cover  >  gear chamber casing  >  right body  >  flywheel housing, which provides an effectual guidance for the noise reduction.

  16. Predicting Autism Spectrum Disorder Using Blood-based Gene Expression Signatures and Machine Learning

    Science.gov (United States)

    Oh, Dong Hoon; Kim, Il Bin; Kim, Seok Hyeon; Ahn, Dong Hyun

    2017-01-01

    Objective The aim of this study was to identify a transcriptomic signature that could be used to classify subjects with autism spectrum disorder (ASD) compared to controls on the basis of blood gene expression profiles. The gene expression profiles could ultimately be used as diagnostic biomarkers for ASD. Methods We used the published microarray data (GSE26415) from the Gene Expression Omnibus database, which included 21 young adults with ASD and 21 age- and sex-matched unaffected controls. Nineteen differentially expressed probes were identified from a training dataset (n=26, 13 ASD cases and 13 controls) using the limma package in R language (adjusted p value <0.05) and were further analyzed in a test dataset (n=16, 8 ASD cases and 8 controls) using machine learning algorithms. Results Hierarchical cluster analysis showed that subjects with ASD were relatively well-discriminated from controls. Based on the support vector machine and K-nearest neighbors analysis, validation of 19-DE probes with a test dataset resulted in an overall class prediction accuracy of 93.8% as well as a sensitivity and specificity of 100% and 87.5%, respectively. Conclusion The results of our exploratory study suggest that the gene expression profiles identified from the peripheral blood samples of young adults with ASD can be used to identify a biological signature for ASD. Further study using a larger cohort and more homogeneous datasets is required to improve the diagnostic accuracy. PMID:28138110

  17. Frequency spectrum method-based stress analysis for oil pipelines in earthquake disaster areas.

    Directory of Open Access Journals (Sweden)

    Xiaonan Wu

    Full Text Available When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure. To date, researchers have performed limited safety analyses of oil pipelines in earthquake disaster areas that include stress analysis. Therefore, using the spectrum method and theory of one-dimensional beam units, CAESAR II is used to perform a dynamic earthquake analysis for an oil pipeline in the XX earthquake disaster area. This software is used to determine if the displacement and stress of the pipeline meet the standards when subjected to a strong earthquake. After performing the numerical analysis, the primary seismic action axial, longitudinal and horizontal displacement directions and the critical section of the pipeline can be located. Feasible project enhancement suggestions based on the analysis results are proposed. The designer is able to utilize this stress analysis method to perform an ultimate design for an oil pipeline in earthquake disaster areas; therefore, improving the safe operation of the pipeline.

  18. Characteristics of SiC neutron sensor spectrum unfolding process based on Bayesian inference

    Energy Technology Data Exchange (ETDEWEB)

    Cetnar, Jerzy; Krolikowski, Igor [Faculty of Energy and Fuels AGH - University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Ottaviani, L. [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231 -13397 Marseille Cedex 20 (France); Lyoussi, A. [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France)

    2015-07-01

    This paper deals with SiC detector signal interpretation in neutron radiation measurements in mixed neutron gamma radiation fields, which is called the detector inverse problem or the spectrum unfolding, and it aims in finding a representation of the primary radiation, based on the measured detector signals. In our novel methodology we resort to Bayesian inference approach. In the developed procedure the resultant spectra is unfolded form detector channels reading, where the estimated neutron fluence in a group structure is obtained with its statistical characteristic comprising of standard deviation and correlation matrix. In the paper we present results of unfolding process for case of D-T neutron source in neutron moderating environment. Discussions of statistical properties of obtained results are presented as well as of the physical meaning of obtained correlation matrix of estimated group fluence. The presented works has been carried out within the I-SMART project, which is part of the KIC InnoEnergy R and D program. (authors)

  19. Correlation Coefficient Based DVB-T Continual Pilot Detection to Identify Spectrum Hole for CR Application

    Directory of Open Access Journals (Sweden)

    Mohammad Mizanur RAHMAN

    2016-06-01

    Full Text Available Digital terrestrial television (DTV covers an area with radius as large as 60 km. Federal Communications Commission (FCC and Office of Communications (Ofcom suggests detection of DTV signal at signal strength of as low as -114 dBm and -120 dBm respectively. Thus, detection of DTV signals in low signal-to-noise ratio (SNR is vital. Continual pilot (CP positions in all the DTV signals are fixed. Digital Video Broadcasting Terrestrial (DVB-T, a DTV standard, is followed by most of the countries of the world. In this paper we propose a correlation based CP detection which can detect a DVB-T signal at low SNR. One CP carrier was generated at the receiver which was correlated with the received orthogonal frequency division multiplexing (OFDM signal sequence. The correlation coefficient was then compared with a threshold correlation coefficient to identify the existence of the CP to detect the presence of a DVB-T signal and thereby spectrum hole. It was found from the simulation study for additive white Gaussian noise (AWGN channel that signal detection at low SNR is possible compared to the time domain symbol cross-correlation (TDSC method.

  20. Structural and functional bases for broad-spectrum neutralization of avian and human influenza A viruses.

    Science.gov (United States)

    Sui, Jianhua; Hwang, William C; Perez, Sandra; Wei, Ge; Aird, Daniel; Chen, Li-mei; Santelli, Eugenio; Stec, Boguslaw; Cadwell, Greg; Ali, Maryam; Wan, Hongquan; Murakami, Akikazu; Yammanuru, Anuradha; Han, Thomas; Cox, Nancy J; Bankston, Laurie A; Donis, Ruben O; Liddington, Robert C; Marasco, Wayne A

    2009-03-01

    Influenza virus remains a serious health threat, owing to its ability to evade immune surveillance through rapid genetic drift and reassortment. Here we used a human non-immune antibody phage-display library and the H5 hemagglutinin ectodomain to select ten neutralizing antibodies (nAbs) that were effective against all group 1 influenza viruses tested, including H5N1 'bird flu' and the H1N1 'Spanish flu'. The crystal structure of one such nAb bound to H5 shows that it blocks infection by inserting its heavy chain into a conserved pocket in the stem region, thus preventing membrane fusion. Nine of the nAbs employ the germline gene VH1-69, and all seem to use the same neutralizing mechanism. Our data further suggest that this region is recalcitrant to neutralization escape and that nAb-based immunotherapy is a promising strategy for broad-spectrum protection against seasonal and pandemic influenza viruses.

  1. Evaluation of regression in autism spectrum disorder based on parental reports

    Directory of Open Access Journals (Sweden)

    Janet K Kern

    2014-01-01

    Full Text Available Background: Research indicates that some children with autism spectrum disorder (ASD experience a developmental regression. Aims: The study examined the percentage of children with autism, pervasive developmental disorder (PDD, ASD, and Asperger syndrome (AS who were considered to be delayed (D, regressed (R, or delayed and later regressed (DR and examined any relationship with autism severity, time of onset, factors associated with onset, gastrointestinal (GI symptoms, race, age, and gender. Materials and Methods: The study reviewed developmental and medical information based on parental reports of 135 children with a diagnosis of autism, PDD, ASD, or AS. Results: The number of children in the D group was 53 (39.2% with 19 (14.1% in the DR group and 63 (46.7% in the R group. Thus, 82 children (60.7% were reported to have R. In regard to onset of symptoms, there was a significant difference between the D and R groups as well as between the DR and R groups. The analyses showed that there was no significant relationship between age, gender, race, severity, or GI symptoms and membership in any group; D, DR, or R. The majority of parents reported that the regression was preceded by or was associated with vaccinations (57.3% or another medically related event (11.0%. Conclusions: The findings are consistent with previous research and reinforce our understanding of regression in those children with an ASD diagnosis.

  2. Spectrum warping based on sub-glottal resonances in speaker-independent speech recognition

    Institute of Scientific and Technical Information of China (English)

    HOU Limin; HUANG Zhenhua; XIE Juanmin

    2011-01-01

    To reduce degradation in speech recognition due to varied characteristics of different speakers, a method of perceptual frequency warping based on subglottal resonances for speaker normalization is proposed. The warping factor is extracted from the second subglottal resonance using acoustic coupling between subglottis and vocal tract. The second subglottal resonance is independent of the speech content, which reflects the speaker characteristics more than the third formant. The perceptual minimum variation distortionless response (PMVDR) coefficient is normalized, which is more robust and has better anti-noise capability than MFCC. The normalized coefficients are used in the speech-mode training and speech recognition. Experiments show that the word error rate, as compared with MFCC and the spectrum warping by the third formant, decreases by 4% and 3% respectively in clean speech recognition, and by 9% and 5% respectively in a noisy environment. The results indicate that the proposed method can improve the word recognition accuracy in a speaker-independent recognition system.

  3. Spread Spectrum Based Energy Efficient Collaborative Communication in Wireless Sensor Networks.

    Science.gov (United States)

    Ghani, Anwar; Naqvi, Husnain; Sher, Muhammad; Khan, Muazzam Ali; Khan, Imran; Irshad, Azeem

    2016-01-01

    Wireless sensor networks consist of resource limited devices. Most crucial of these resources is battery life, as in most applications like battle field or volcanic area monitoring, it is often impossible to replace or recharge the power source. This article presents an energy efficient collaborative communication system based on spread spectrum to achieve energy efficiency as well as immunity against jamming, natural interference, noise suppression and universal frequency reuse. Performance of the proposed system is evaluated using the received signal power, bit error rate (BER) and energy consumption. The results show a direct proportionality between the power gain and the number of collaborative nodes as well as BER and signal-to-noise ratio (Eb/N0). The analytical and simulation results of the proposed system are compared with SISO system. The comparison reveals that SISO perform better than collaborative communication in case of small distances whereas collaborative communication performs better than SISO in case of long distances. On the basis of these results it is safe to conclude that collaborative communication in wireless sensor networks using wideband systems improves the life time of nodes in the networks thereby prolonging the network's life time.

  4. A Songbird Animal Model for Dissecting the Genetic Bases of Autism Spectrum Disorder

    Directory of Open Access Journals (Sweden)

    S. Carmen Panaitof

    2012-01-01

    Full Text Available The neural and genetic bases of human language development and associated neurodevelopmental disorders, including autism spectrum disorder (ASD, in which language impairment represents a core deficit, are poorly understood. Given that no single animal model can fully capture the behavioral and genetic complexity of ASD, work in songbird, an experimentally tractable animal model of vocal learning, can complement the valuable tool of rodent genetic models and contribute important insights to our understanding of the communication deficits observed in ASD. Like humans, but unlike traditional laboratory animals such as rodents or non-human primates, songbirds exhibit the capacity of vocal learning, a key subcomponent of language. Human speech and birdsong reveal important parallels, highlighting similar developmental critical periods, a homologous cortico-basal ganglia-thalamic circuitry, and a critical role for social influences in the learning of vocalizations. Here I highlight recent advances in using the songbird model to probe the cellular and molecular mechanisms underlying the formation and function of neural circuitry for birdsong and, by analogy, human language, with the ultimate goal of identifying any shared or human unique biological pathways underscoring language development and its disruption in ASD.

  5. Identifying children with autism spectrum disorder based on their face processing abnormality: A machine learning framework.

    Science.gov (United States)

    Liu, Wenbo; Li, Ming; Yi, Li

    2016-08-01

    The atypical face scanning patterns in individuals with Autism Spectrum Disorder (ASD) has been repeatedly discovered by previous research. The present study examined whether their face scanning patterns could be potentially useful to identify children with ASD by adopting the machine learning algorithm for the classification purpose. Particularly, we applied the machine learning method to analyze an eye movement dataset from a face recognition task [Yi et al., 2016], to classify children with and without ASD. We evaluated the performance of our model in terms of its accuracy, sensitivity, and specificity of classifying ASD. Results indicated promising evidence for applying the machine learning algorithm based on the face scanning patterns to identify children with ASD, with a maximum classification accuracy of 88.51%. Nevertheless, our study is still preliminary with some constraints that may apply in the clinical practice. Future research should shed light on further valuation of our method and contribute to the development of a multitask and multimodel approach to aid the process of early detection and diagnosis of ASD. Autism Res 2016, 9: 888-898. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

  6. Spectrum Assignment with Non-Deterministic Bandwidth of Spectrum Holein Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Huang Jie

    2016-01-01

    Full Text Available The spectrum allocation for cognitive radio networks (CRNs has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes is time-varied due to primary user/secondary user (PU/SU activity and mobility, which result in non-determinacy. This paper studies the spectrum allocation for CRNs with non-deterministic bandwidth of spectrum holes. We present a novel probability density function (PDF model through order statistic to describe the non-deterministic bandwidth of spectrum holes and provide a bound to approximate it. After that, a statistical spectrum allocation model based on stochastic multiple knapsack problem (MKP is established for spectrum allocation with non-deterministic bandwidth of spectrum holes. To reduce the computational complexity, we transform this stochastic programming probleminto a constant MKP though exploiting the properties of cumulative distribution function (CDF, which can be solved via MTHG algorithm by using auxiliary variable. Simulation results illustrate that the proposed statistical spectrum allocation algorithm can achieve better performances compared to the existing algorithms when the bandwidth of spectrum holes istime-varied.

  7. Unravelling the myotonic dystrophy type 1 clinical spectrum: A systematic registry-based study with implications for disease classification.

    Science.gov (United States)

    De Antonio, M; Dogan, C; Hamroun, D; Mati, M; Zerrouki, S; Eymard, B; Katsahian, S; Bassez, G

    2016-10-01

    The broad clinical spectrum of myotonic dystrophy type 1 (DM1) creates particular challenges for both medical care and design of clinical trials. Clinical onset spans a continuum from birth to late adulthood, with symptoms that are highly variable in both severity and nature of the affected organ systems. In the literature, this complex phenotype is divided into three grades (mild, classic, and severe) and four or five main clinical categories (congenital, infantile/juvenile, adult-onset and late-onset forms), according to symptom severity and age of onset, respectively. However, these classifications are still under discussion with no consensus thus far. While some specific clinical features have been primarily reported in some forms of the disease, there are no clear distinctions. As a consequence, no modifications in the management of healthcare or the design of clinical studies have been proposed based on the clinical form of DM1. The present study has used the DM-Scope registry to assess, in a large cohort of DM1 patients, the robustness of a classification divided into five clinical forms. Our main aim was to describe the disease spectrum and investigate features of each clinical form. The five subtypes were compared by distribution of CTG expansion size, and the occurrence and onset of the main symptoms of DM1. Analyses validated the relevance of a five-grade model for DM1 classification. Patients were classified as: congenital (n=93, 4.5%); infantile (n=303, 14.8%); juvenile (n=628, 30.7%); adult (n=694, 34.0%); and late-onset (n=326, 15.9%). Our data show that the assumption of a continuum from congenital to the late-onset form is valid, and also highlights disease features specific to individual clinical forms of DM1 in terms of symptom occurrence and chronology throughout the disease course. These results support the use of the five-grade model for disease classification, and the distinct clinical profiles suggest that age of onset and clinical form may

  8. Performance Evaluation of Joint Path and Spectrum Diversity Based Routing Protocol in Cognitive Radio Ad Hoc Networks under Critical Conditions

    Directory of Open Access Journals (Sweden)

    Zamree Che-Aron

    2015-06-01

    Full Text Available Cognitive Radio (CR technology has been introduced to solve the problems of spectrum underutilization and spectrum scarcity caused by improper spectrum management policies. The main concept of Cognitive Radio Ad Hoc Network (CRAHN is that, in a wireless ad hoc network, the unlicensed users (or Secondary Users (SUs are allowed to access the temporally unused licensed spectrum bands for data communications without harmful interference to the licensed users (or Primary Users (PUs. In CRAHNs, the mobile SUs communicate with each other without the use of any centralized network infrastructure. Routing in CRAHNs is an important task and faces various challenges including PU interference, frequent network topology changes, energy constraint, volatile bandwidth and fragile connectivity. In this study, an attempt is made to evaluate the performance of the Dual Diversity Cognitive Ad-hoc Routing Protocol (D2CARP in CRAHNs under critical conditions, i.e., high node mobility rate and number of PUs. The D2CARP protocol is a joint path and spectrum diversity based routing protocol for CRAHNs. The performance evaluation is conducted through simulation using NS-2 simulator. The performance metrics to be considered include average throughput, percentage of packet loss, average end-to-end delay and average jitter. The simulation results prove that the protocol performance is significantly affected in the networks with high number of PUs and mobility rate, leading to high path failure rate and severe service outages.

  9. Chaotic-Laser-Based True Random Sequence Generation for Spread-Spectrum Communications

    Institute of Scientific and Technical Information of China (English)

    张朝霞; 周俊杰; 张东泽; 傅正; 张建忠

    2012-01-01

    We propose a scheme for spread-spectrum communications using true random sequences generated by chaotic semiconductor lasers as spreading codes. These sequences can eliminate the inherent periodicity of pseudorandom sequences,enlarge the capacity of spread-spectrum codes,improve communication security,and increase the number ot users of the system.When a true random sequence with an appropriate length is used as thespread-spectrum code and the information speed is maintained constant,the system acquires a greater spreadspectrum gain and a lower bit-error ratio (BER) than the traditional spread-spectrum system.The communication security is also enhanced.The BER smoothly increases with the number of users,which indicates the good multipleaccess capability of the system.

  10. SENSORING DROPLET SPRAY TRANSFER IN MIG WELDING BASED ON ARC SPECTRUM SIGNAL

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The method to detect droplet transfer by means of arc spectrum, while the experiment sets, testing principle and data processing procedure, are presented. The experiment and analysis results show that arc spectrum signal can be utilized to detect and measure the transfer procedure, the transfer modes and the transfer parameters. The arc spectrum signal enjoys excellent quality with high signal amplitude. Each transfer mode has its specific typical signal mode, and the pulse outline corresponds to an integrated transferring procedure of one droplet. All these features of arc spectrum signal can be easily applied in the control of transfer procedure,the identification and stabilization of transfer mode and the measurement of transfer parameters.

  11. Energy and spectrum efficiency in rural areas based on cognitive radio technology

    CSIR Research Space (South Africa)

    Masonta, MT

    2009-09-01

    Full Text Available The rapid growth and development observed in wireless communications has resulted in the overcrowding of the radio spectrum used as a communication medium in wireless networks. In many countries, governmental agencies regulate the use of the radio...

  12. System optimization of a long-range Brillouin-loss-based distributed fiber sensor.

    Science.gov (United States)

    Dong, Yongkang; Chen, Liang; Bao, Xiaoyi

    2010-09-20

    We report a high-performance 25 km Brillouin-loss-based distributed fiber sensor through optimizing system parameters. First, the Brillouin spectrum distortion and measurement error induced by the excess amplification on probe pulse are investigated, and the results indicate that a low continuous-wave pump power is essential to decrease the measurement error. Then an optimal pulse pair is determined through the differential Brillouin gain evolution along the entire sensing fiber in a differential pulse-width pair Brillouin optical time domain analysis. Using dispersion-shifted fiber to allow a high-power probe pulse, we realize a 25 km sensing range with a spatial resolution of 30 cm and a strain accuracy of ±20 με, which we believe is the best performance in such a length, to the best of our knowledge.

  13. Design of a distributed CORBA based image processing server.

    Science.gov (United States)

    Giess, C; Evers, H; Heid, V; Meinzer, H P

    2000-01-01

    This paper presents the design and implementation of a distributed image processing server based on CORBA. Existing image processing tools were encapsulated in a common way with this server. Data exchange and conversion is done automatically inside the server, hiding these tasks from the user. The different image processing tools are visible as one large collection of algorithms and due to the use of CORBA are accessible via intra-/internet.

  14. Greening radio access networks using distributed base station architectures

    DEFF Research Database (Denmark)

    Kardaras, Georgios; Soler, José; Dittmann, Lars

    2010-01-01

    . However besides this, increasing energy efficiency represents a key factor for reducing operating expenses and deploying cost effective mobile networks. This paper presents how distributed base station architectures can contribute in greening radio access networks. More specifically, the advantages...... of introducing remote radio head modules are discussed. Substantial flexibility is provided in terms of power consumption, as a result of combining efficient hardware with intelligent software. Additionally, it is underlined that designing eco-sustainable systems needs to follow a holistic approach towards...

  15. Model based code generation for distributed embedded systems

    OpenAIRE

    Raghav, Gopal; Gopalswamy, Swaminathan; Radhakrishnan, Karthikeyan; Hugues, Jérôme; Delange, Julien

    2010-01-01

    Embedded systems are becoming increasingly complex and more distributed. Cost and quality requirements necessitate reuse of the functional software components for multiple deployment architectures. An important step is the allocation of software components to hardware. During this process the differences between the hardware and application software architectures must be reconciled. In this paper we discuss an architecture driven approach involving model-based techniques to resolve these diff...

  16. Securing Consensus-Based Cooperative Spectrum Sensing Against Spectrum Sensing Data Falsification Attacks%抗SSDF攻击的一致性协作频谱感知方案

    Institute of Scientific and Technical Information of China (English)

    刘全; 高俊; 郭云玮; 刘思洋

    2011-01-01

    在分布式认知无线电网络中,一般很难找到合适的融合中心能够收集所有协作用户的感知信息,而且协作过程极可能遭到篡改感知数据(Spectrum Sensing Data Falsification,SSDF)攻击.鉴于此,该文提出了一种改进的一致性协作频谱感知方案.利用Metropolis迭代规则,各次用户仅依靠邻接点之间的局部信息交互即可实现感知协作,且无需网络的任何先验知识.为了抵抗潜在的三种SSDF攻击,该方案中引入了相应的抗攻击策略,使合法次用户能及时检测并拒绝恶意用户接入网络.仿真结果表明,改进方案能保证绝大多数合法次用户最终趋于状态一致,并分别做出正确决策;与现有的一致性方案相比,该方案能使协作感知在各种攻击场景中的稳健性明显增强.%In distributed cognitive radio networks (CRNs), a common fusion centre is always not available to collect the sensing results from all cooperative users,and the sensing cooperation is likely to be disrupted by spectrum sensing data falsification (SSDF) attacks. Allowing for these factors, this paper proposes a modified consensus-based scheme for decentralized cooperative spectrum sensing(CSS) .Utilizing the iteration rule based on Metropolis weight matrix,each secondary user (SU) can maintain cooperation with others only through the local information exchange in the neighborhood, without requiring any a priori knowledge of the whole network. To counter three potential attack models of SSDF, some anti-attack strategies are also introduced,by which the authentic Sus can identify and reject the malicious users quickly. As represented by the extensive simulation results, the proposed scheme can generally guarantee most authentic Sus to reach a consensus and make right decisions individually; also,it is proved to be much more robust against all potential SSDF attacks,compared with the existing consensus-based scheme.

  17. Reduced functional integration and segregation of distributed neural systems underlying social and emotional information processing in autism spectrum disorders.

    Science.gov (United States)

    Rudie, Jeffrey D; Shehzad, Zarrar; Hernandez, Leanna M; Colich, Natalie L; Bookheimer, Susan Y; Iacoboni, Marco; Dapretto, Mirella

    2012-05-01

    A growing body of evidence suggests that autism spectrum disorders (ASDs) are related to altered communication between brain regions. Here, we present findings showing that ASD is characterized by a pattern of reduced functional integration as well as reduced segregation of large-scale brain networks. Twenty-three children with ASD and 25 typically developing matched controls underwent functional magnetic resonance imaging while passively viewing emotional face expressions. We examined whole-brain functional connectivity of two brain structures previously implicated in emotional face processing in autism: the amygdala bilaterally and the right pars opercularis of the inferior frontal gyrus (rIFGpo). In the ASD group, we observed reduced functional integration (i.e., less long-range connectivity) between amygdala and secondary visual areas, as well as reduced segregation between amygdala and dorsolateral prefrontal cortex. For the rIFGpo seed, we observed reduced functional integration with parietal cortex and increased integration with right frontal cortex as well as right nucleus accumbens. Finally, we observed reduced segregation between rIFGpo and the ventromedial prefrontal cortex. We propose that a systems-level approach-whereby the integration and segregation of large-scale brain networks in ASD is examined in relation to typical development-may provide a more detailed characterization of the neural basis of ASD.

  18. Ultra Steep Spectrum radio sources in the Lockman Hole: SERVS identifications and redshift distribution at the faintest radio fluxes

    CERN Document Server

    Afonso, J; Ibar, E; Grossi, M; Simpson, C; Chapman, S; Jarvis, M J; Rottgering, H; Norris, R P; Dunlop, J; Ivison, R J; Messias, H; Pforr, J; Vaccari, M; Seymour, N; Best, P; González-Solares, E; Farrah, D; Fernandes, C A C; Huang, J -S; Lacy, M; Marastron, C; Marchetti, L; Mauduit, J -C; Oliver, S; Rigopoulou, D; Stanford, S A; Surace, J; Zeimann, G

    2011-01-01

    Ultra Steep Spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z>~2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610 MHz integrated fluxes above 100 microJy, is assembled. Deep infrared data at 3.6 and 4.5 micron from the Spitzer Extragalactic Representative Volume Survey (SERVS) is used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6](AB)=19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of...

  19. Neural Spike-Train Analyses of the Speech-Based Envelope Power Spectrum Model

    Directory of Open Access Journals (Sweden)

    Varsha H. Rallapalli

    2016-10-01

    Full Text Available Diagnosing and treating hearing impairment is challenging because people with similar degrees of sensorineural hearing loss (SNHL often have different speech-recognition abilities. The speech-based envelope power spectrum model (sEPSM has demonstrated that the signal-to-noise ratio (SNRENV from a modulation filter bank provides a robust speech-intelligibility measure across a wider range of degraded conditions than many long-standing models. In the sEPSM, noise (N is assumed to: (a reduce S + N envelope power by filling in dips within clean speech (S and (b introduce an envelope noise floor from intrinsic fluctuations in the noise itself. While the promise of SNRENV has been demonstrated for normal-hearing listeners, it has not been thoroughly extended to hearing-impaired listeners because of limited physiological knowledge of how SNHL affects speech-in-noise envelope coding relative to noise alone. Here, envelope coding to speech-in-noise stimuli was quantified from auditory-nerve model spike trains using shuffled correlograms, which were analyzed in the modulation-frequency domain to compute modulation-band estimates of neural SNRENV. Preliminary spike-train analyses show strong similarities to the sEPSM, demonstrating feasibility of neural SNRENV computations. Results suggest that individual differences can occur based on differential degrees of outer- and inner-hair-cell dysfunction in listeners currently diagnosed into the single audiological SNHL category. The predicted acoustic-SNR dependence in individual differences suggests that the SNR-dependent rate of susceptibility could be an important metric in diagnosing individual differences. Future measurements of the neural SNRENV in animal studies with various forms of SNHL will provide valuable insight for understanding individual differences in speech-in-noise intelligibility.

  20. On the spatial distribution of neutral hydrogen in the Universe: bias and shot-noise of the HI Power Spectrum

    CERN Document Server

    Castorina, Emanuele

    2016-01-01

    The spatial distribution of neutral hydrogen (HI) in the Universe contains a wealth of cosmological information. The 21 cm emission line can be used to map the HI up to very high redshift and therefore reveal us something about the evolution of the large scale structures in the Universe. However little is known about the abundance and clustering properties of the HI over cosmic time. Motivated by this, we build an analytic framework where the relevant parameters that govern how the HI is distributed among dark matter halos can be fixed using observations. At the same time we provide tools to study the column density distribution function of the HI absorbers together with their clustering properties. Our formalism is the first one able to account for all observations at a single redshift, $z = 2.3$. The linear bias of the HI and the mean number density of HI sources, two main ingredients in the calculation of the signal-to-noise ratio of a cosmological survey, are then discussed in detail, also extrapolating t...

  1. Implementation of Web-based Information Systems in Distributed Organizations

    DEFF Research Database (Denmark)

    Bødker, Keld; Pors, Jens Kaaber; Simonsen, Jesper

    2004-01-01

    This article presents results elicited from studies conducted in relation to implementing a web-based information system throughout a large distributed organization. We demonstrate the kind of expectations and conditions for change that management face in relation to open-ended, configurable......, and context specific web-based information systems like Lotus QuickPlace. Our synthesis from the empirical findings is related to two recent models, the improvisational change management model suggested by Orlikowski and Hofman (1997), and Gallivan's (2001) model for organizational adoption and assimilation...

  2. On the decision threshold of eigenvalue ratio detector based on moments of joint and marginal distributions of extreme eigenvalues

    KAUST Repository

    Shakir, Muhammad Zeeshan

    2013-03-01

    Eigenvalue Ratio (ER) detector based on the two extreme eigenvalues of the received signal covariance matrix is currently one of the most effective solution for spectrum sensing. However, the analytical results of such scheme often depend on asymptotic assumptions since the distribution of the ratio of two extreme eigenvalues is exceptionally complex to compute. In this paper, a non-asymptotic spectrum sensing approach for ER detector is introduced to approximate the marginal and joint distributions of the two extreme eigenvalues. The two extreme eigenvalues are considered as dependent Gaussian random variables such that their joint probability density function (PDF) is approximated by a bivariate Gaussian distribution function for any number of cooperating secondary users and received samples. The PDF approximation approach is based on the moment matching method where we calculate the exact analytical moments of joint and marginal distributions of the two extreme eigenvalues. The decision threshold is calculated by exploiting the statistical mean and the variance of each of the two extreme eigenvalues and the correlation coefficient between them. The performance analysis of our newly proposed approximation approach is compared with the already published asymptotic Tracy-Widom approximation approach. It has been shown that our results are in perfect agreement with the simulation results for any number of secondary users and received samples. © 2002-2012 IEEE.

  3. A Distributed IP-Based Telecommunication System using SIP

    Directory of Open Access Journals (Sweden)

    Carlton Andre Thompson

    2013-11-01

    Full Text Available Voice over Internet Protocol (VoIP technologies are integral to modern telecommunications because oftheir advanced features, flexibility, and economicbenefits. Internet Service Providers initially promotedthese technologies by providing low cost local andinternational calling. At present, there is also agreatdeal of interest in using IP-based technologies toreplace traditional small and large office telephonesystems that use traditional PBX’s (Private BrancheXchange. Unfortunately, the large majority of theemerging VoIP based office telephone systems have followed the centralized design of traditional publicand private telephone systems in which all the intelligence in the system is at the core, with quite expensivehardware and software components and appropriate redundancy for adequate levels of reliability. In thispaper, it is argued that a centralized model for anIP-based telecommunications system fails to exploit thefull capabilities of Internet-inspired communications and that, very simple, inexpensive, elegant andflexible solutions are possible by deliberately avoiding the centralized approach. This paper describes thedesign, philosophy and implementation of a prototype for a fully distributed IP-based TelecommunicationSystem (IPTS that provides the essential feature set for office and home telecommunications, including IP-based long-distance and local calling, and with thesupport for video as well as data and text. Theprototype system was implemented with an Internet-inspired distributed design using open source software,with appropriate customizations and configurations.

  4. Autism Spectrum Disorder in a Community-based Sample with Neurodevelopmental Problems in Lagos, Nigeria

    Science.gov (United States)

    Olagunju, Andrew T.; Oyelohunnu, Motunrayo. A.; Campbell, Elizabeth A.; Umeh, Charles S.; Aina, Olatunji F.; Oyibo, Wellington; Lesi, Folusho E.A.; Adeyemi, Joseph D.

    2017-01-01

    Autism Spectrum Disorder (ASD) is a globally prevalent neurodevelopmental disorder for which early diagnosis and intervention is the mainstay of management. In the African continent, limited data is available regarding the non-clinic based samples. Lack of information available to caregivers and inadequate skilled manpower often limit early detection and access to the few available though under resourced services in the community. Community based screening can be an important drive to create awareness and improve information dissemination regarding services available for those living with this disorder. This is a descriptive cross-sectional study utilizing data obtained from participants of a community-based autism screening exercise. The surveillance exercise was part of the annual Orange Ribbon initiative for autism awareness and screening held in 2014. Data was obtained from 85 participants involved in the Autism Surveillance screening exercise within the Lagos community. Community public service radio announcements state wide and word of mouth were used to invite and enroll eligible participants to the screening and consultation exercise. A second stage screening and a brief sociodemographic questionnaire followed by a third stage clinical interview and evaluation using the Diagnostic and Statistical Manual of Mental Disorders - 5 Edition (DSM 5) were used. Appropriate consultation and referrals to services in the community were given. Participants had a mean age of 7.53 years (SD 4.35). Twenty-nine (34.5%) met the diagnosis of ASD. Other diagnosis included attention deficit hyperactivity disorder (ADHD), language and speech disorder, intellectual disability (8.3%) and learning disorders (9.5%). Main health concerns to caregivers were poor language development in all (100%), of which 11 (40.7%) were non-verbal; gaze avoidance was seen in 14 (48.3%) and challenging behavior in 12 (42.9%). Comorbidities included seizure disorders (3.4%) and ADHD (6.9%). Persons

  5. Autism spectrum disorder in a community-based sample with neurodevelopmental problems in Lagos, Nigeria

    Directory of Open Access Journals (Sweden)

    Yewande O. Oshodi

    2017-01-01

    Full Text Available Autism Spectrum Disorder (ASD is a globally prevalent neurodevelopmental disorder for which early diagnosis and intervention is the mainstay of management. In the African continent, limited data is available regarding the non-clinic based samples. Lack of information available to caregivers and inadequate skilled manpower often limit early detection and access to the few available though under resourced services in the community. Community based screening can be an important drive to create awareness and improve information dissemination regarding services available for those living with this disorder. This is a descriptive cross-sectional study utilizing data obtained from participants of a community-based autism screening exercise. The surveillance exercise was part of the annual Orange Ribbon initiative for autism awareness and screening held in 2014. Data was obtained from 85 participants involved in the Autism Surveillance screening exercise within the Lagos community. Community public service radio announcements state wide and word of mouth were used to invite and enroll eligible participants to the screening and consultation exercise. A second stage screening and a brief sociodemographic questionnaire followed by a third stage clinical interview and evaluation using the Diagnostic and Statistical Manual of Mental Disorders - 5 Edition (DSM 5 were used. Appropriate consultation and referrals to services in the community were given. Participants had a mean age of 7.53 years (SD 4.35. Twenty-nine (34.5% met the diagnosis of ASD. Other diagnosis included attention deficit hyperactivity disorder (ADHD, language and speech disorder, intellectual disability (8.3% and learning disorders (9.5%. Main health concerns to caregivers were poor language development in all (100%, of which 11 (40.7% were non-verbal; gaze avoidance was seen in 14 (48.3% and challenging behavior in 12 (42.9%. Comorbidities included seizure disorders (3.4% and ADHD (6

  6. Price Based Local Power Distribution Management System (Local Power Distribution Manager) v1.0

    Energy Technology Data Exchange (ETDEWEB)

    2016-11-28

    A trans-active energy micro-grid controller is implemented in the VOLTTRON distributed control platform. The system uses the price of electricity as the mechanism for conducting transactions that are used to manage energy use and to balance supply and demand. In order to allow testing and analysis of the control system, the implementation is designed to run completely as a software simulation, while allowing the inclusion of selected hardware that physically manages power. Equipment to be integrated with the micro-grid controller must have an IP (Internet Protocol)-based network connection and a software "driver" must exist to translate data communications between the device and the controller.

  7. The application analyses for primary spectrum pyrometer

    Institute of Scientific and Technical Information of China (English)

    FU; TaiRan

    2007-01-01

    In the applications of primary spectrum pyrometry, based on the dynamic range and the minimum sensibility of the sensor, the application issues, such as the measurement range and the measurement partition, were investigated through theoretical analyses. For a developed primary spectrum pyrometer, the theoretical predictions of measurement range and the distributions of measurement partition were presented through numerical simulations. And the measurement experiments of high-temperature blackbody and standard temperature lamp were processed to further verify the above theoretical analyses and numerical results. Therefore the research in the paper provides the helpful supports for the applications of primary spectrum pyrometer and other radiation pyrometers.……

  8. Evaluating the performance of two neutron spectrum unfolding codes based on iterative procedures and artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Rodriguez, J. M.; Reyes Alfaro, A.; Reyes Haro, A.; Solis Sanches, L. O.; Miranda, R. Castaneda; Cervantes Viramontes, J. M. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica. Av. Ramon Lopez Velarde 801. Col. Centro Zacatecas, Zac (Mexico); Vega-Carrillo, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica. Av. Ramon Lopez Velarde 801. Col. Centro Zacatecas, Zac., Mexico. and Unidad Academica de Estudios Nucleares. C. Cip (Mexico)

    2013-07-03

    In this work the performance of two neutron spectrum unfolding codes based on iterative procedures and artificial neural networks is evaluated. The first one code based on traditional iterative procedures and called Neutron spectrometry and dosimetry from the Universidad Autonoma de Zacatecas (NSDUAZ) use the SPUNIT iterative algorithm and was designed to unfold neutron spectrum and calculate 15 dosimetric quantities and 7 IAEA survey meters. The main feature of this code is the automated selection of the initial guess spectrum trough a compendium of neutron spectrum compiled by the IAEA. The second one code known as Neutron spectrometry and dosimetry with artificial neural networks (NDSann) is a code designed using neural nets technology. The artificial intelligence approach of neural net does not solve mathematical equations. By using the knowledge stored at synaptic weights on a neural net properly trained, the code is capable to unfold neutron spectrum and to simultaneously calculate 15 dosimetric quantities, needing as entrance data, only the rate counts measured with a Bonner spheres system. Similarities of both NSDUAZ and NSDann codes are: they follow the same easy and intuitive user's philosophy and were designed in a graphical interface under the LabVIEW programming environment. Both codes unfold the neutron spectrum expressed in 60 energy bins, calculate 15 dosimetric quantities and generate a full report in HTML format. Differences of these codes are: NSDUAZ code was designed using classical iterative approaches and needs an initial guess spectrum in order to initiate the iterative procedure. In NSDUAZ, a programming routine was designed to calculate 7 IAEA instrument survey meters using the fluence-dose conversion coefficients. NSDann code use artificial neural networks for solving the ill-conditioned equation system of neutron spectrometry problem through synaptic weights of a properly trained neural network. Contrary to iterative procedures, in

  9. Experimental detailed power distribution in a fast spectrum thermionic reactor fuel element at the core/BeO reflector interface region

    Science.gov (United States)

    Klann, P. G.; Lantz, E.

    1973-01-01

    A zero-power critical assembly was designed, constructed, and operated for the prupose of conducting a series of benchmark experiments dealing with the physics characteristics of a UN-fueled, Li-7-cooled, Mo-reflected, drum-controlled compact fast reactor for use with a space-power conversion system. The critical assembly was modified to simulate a fast spectrum advanced thermionics reactor by: (1) using BeO as a reflector in place of some of the existing molybdenum, (2) substituting Nb-1Zr tubing for some of the existing Ta tubing, and (3) inserting four full-scale mockups of thermionic type fuel elements near the core and BeO reflector boundary. These mockups were surrounded with a buffer zone having the equivalent thermionic core composition. In addition to measuring the critical mass of this thermionic configuration, a detailed power distribution in one of the thermionic element stages in the mixed spectrum region was measured. A power peak to average ratio of two was observed for this fuel stage at the midplane of the core and adjacent to the reflector. Also, the power on the outer surface adjacent to the BeO was slightly more than a factor of two larger than the power on the inside surface of a 5.08 cm (2.0 in.) high annular fuel segment with a 2.52 cm (0.993 in. ) o.d. and a 1.86 cm (0.731 in.) i.d.

  10. On the spatial distribution of neutral hydrogen in the Universe: bias and shot-noise of the H I power spectrum

    Science.gov (United States)

    Castorina, Emanuele; Villaescusa-Navarro, Francisco

    2017-10-01

    The spatial distribution of neutral hydrogen (H i) in the Universe contains a wealth of cosmological information. The 21-cm emission line can be used to map the H I up to very high redshift and therefore reveal us something about the evolution of the large-scale structures in the Universe. However, little is known about the abundance and clustering properties of the H I over cosmic time. Motivated by this, we build an analytic framework where the relevant parameters that govern how the H I is distributed among dark matter haloes can be fixed using observations. At the same time, we provide tools to study the column density distribution function of the H I absorbers together with their clustering properties. Our formalism is the first one able to account for all observations at a single redshift, z = 2.3. The linear bias of the H I and the mean number density of H I sources, two main ingredients in the calculation of the signal-to-noise ratio of a cosmological survey, are then discussed in detail, also extrapolating the results to low and high redshift. We find that H I bias is relatively higher than the value reported in similar studies, but the shot noise level is always sub-dominant, making the H I power spectrum always a high signal-to-noise measurement up to z ≃ 5 in the limit of no instrumental noise and foreground contamination.

  11. Protection of Location Privacy Based on Distributed Collaborative Recommendations

    Science.gov (United States)

    Wang, Peng; Yang, Jing; Zhang, Jian-Pei

    2016-01-01

    In the existing centralized location services system structure, the server is easily attracted and be the communication bottleneck. It caused the disclosure of users’ location. For this, we presented a new distributed collaborative recommendation strategy that is based on the distributed system. In this strategy, each node establishes profiles of their own location information. When requests for location services appear, the user can obtain the corresponding location services according to the recommendation of the neighboring users’ location information profiles. If no suitable recommended location service results are obtained, then the user can send a service request to the server according to the construction of a k-anonymous data set with a centroid position of the neighbors. In this strategy, we designed a new model of distributed collaborative recommendation location service based on the users’ location information profiles and used generalization and encryption to ensure the safety of the user’s location information privacy. Finally, we used the real location data set to make theoretical and experimental analysis. And the results show that the strategy proposed in this paper is capable of reducing the frequency of access to the location server, providing better location services and protecting better the user’s location privacy. PMID:27649308

  12. Protection of Location Privacy Based on Distributed Collaborative Recommendations.

    Science.gov (United States)

    Wang, Peng; Yang, Jing; Zhang, Jian-Pei

    2016-01-01

    In the existing centralized location services system structure, the server is easily attracted and be the communication bottleneck. It caused the disclosure of users' location. For this, we presented a new distributed collaborative recommendation strategy that is based on the distributed system. In this strategy, each node establishes profiles of their own location information. When requests for location services appear, the user can obtain the corresponding location services according to the recommendation of the neighboring users' location information profiles. If no suitable recommended location service results are obtained, then the user can send a service request to the server according to the construction of a k-anonymous data set with a centroid position of the neighbors. In this strategy, we designed a new model of distributed collaborative recommendation location service based on the users' location information profiles and used generalization and encryption to ensure the safety of the user's location information privacy. Finally, we used the real location data set to make theoretical and experimental analysis. And the results show that the strategy proposed in this paper is capable of reducing the frequency of access to the location server, providing better location services and protecting better the user's location privacy.

  13. Sheldon Spectrum and the Plankton Paradox: Two Sides of the Same Coin. A trait-based plankton size-spectrum model

    CERN Document Server

    Cuesta, José A; Law, Richard

    2016-01-01

    The Sheldon spectrum describes a remarkable regularity in aquatic ecosystems: the biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. While size-spectrum models have explained this phenomenon for assemblages of multicellular organisms, this paper introduces a species-resolved size-spectrum model to explain the phenomenon in unicellular plankton. A Sheldon spectrum spanning the cell-size range of unicellular plankton necessarily consists of a large number of coexisting species covering a wide range of characteristic sizes. The coexistence of many phytoplankton species feeding on a small number of resources is known as the Paradox of the Plankton. Our model resolves the paradox by showing that coexistence is facilitated by the allometric scaling of four physiological rates. Two of the allometries have empirical support, the remaining two emerge from predator-prey interactions exactly when the abundances follow a Sheldon spectrum. Our plankton model is ...

  14. A Novel Approach to Wideband Spectrum Compressive Sensing Based on DST for Frequency Availability in LEO Mobile Satellite Systems

    Directory of Open Access Journals (Sweden)

    Feilong Li

    2016-01-01

    Full Text Available In LEO mobile satellite network, the L/S frequency availability is an essential task for global communication but entails several major technical challenges: high sampling rate required for wideband sensing, limited power and computing resources for processing load, and frequency-selective wireless fading. This paper investigates the issue of frequency availability in LEO mobile satellite system, and a novel wideband spectrum compressed signal detection approach is proposed to obtain active primary users (PUs subbands and their locations that should be avoided during frequency allocation. We define the novel wideband spectrum compressed sensing method based on discrete sine transform (DST-WSCS, which significantly improves the performance of spectrum detection and recovery accuracy compared with conventional discrete Fourier transform based wideband spectrum compressed sensing scheme (DFT-WSCS. Additionally, with the help of intersatellite links (ISL, the scheme of multiple satellites cooperative sensing according to OR and MAJ decision fusion rules is presented to achieve spatial diversity against wireless fading. Finally, in-depth numerical simulations are performed to demonstrate the performance of the proposed scheme in aspect of signal detection probability, reconstruction precision, processing time, and so forth.

  15. MULTIPROCESSOR AND DISTRIBUTED PROCESSING BIBLIOGRAPHIC DATA BASE SOFTWARE SYSTEM

    Science.gov (United States)

    Miya, E. N.

    1994-01-01

    Multiprocessors and distributed processing are undergoing increased scientific scrutiny for many reasons. It is more and more difficult to keep track of the existing research in these fields. This package consists of a large machine-readable bibliographic data base which, in addition to the usual keyword searches, can be used for producing citations, indexes, and cross-references. The data base is compiled from smaller existing multiprocessing bibliographies, and tables of contents from journals and significant conferences. There are approximately 4,000 entries covering topics such as parallel and vector processing, networks, supercomputers, fault-tolerant computers, and cellular automata. Each entry is represented by 21 fields including keywords, author, referencing book or journal title, volume and page number, and date and city of publication. The data base contains UNIX 'refer' formatted ASCII data and can be implemented on any computer running under the UNIX operating system. The data base requires approximately one megabyte of secondary storage. The documentation for this program is included with the distribution tape, although it can be purchased for the price below. This bibliography was compiled in 1985 and updated in 1988.

  16. Absorption spectrum analysis based on singular value decomposition for photoisomerization and photodegradation in organic dyes

    Science.gov (United States)

    Kawabe, Yutaka; Yoshikawa, Toshio; Chida, Toshifumi; Tada, Kazuhiro; Kawamoto, Masuki; Fujihara, Takashi; Sassa, Takafumi; Tsutsumi, Naoto

    2015-10-01

    In order to analyze the spectra of inseparable chemical mixtures, many mathematical methods have been developed to decompose them into the components relevant to species from series of spectral data obtained under different conditions. We formulated a method based on singular value decomposition (SVD) of linear algebra, and applied it to two example systems of organic dyes, being successful in reproducing absorption spectra assignable to cis/trans azocarbazole dyes from the spectral data after photoisomerization and to monomer/dimer of cyanine dyes from those during photodegaradation process. For the example of photoisomerization, polymer films containing the azocarbazole dyes were prepared, which have showed updatable holographic stereogram for real images with high performance. We made continuous monitoring of absorption spectrum after optical excitation and found that their spectral shapes varied slightly after the excitation and during recovery process, of which fact suggested the contribution from a generated photoisomer. Application of the method was successful to identify two spectral components due to trans and cis forms of azocarbazoles. Temporal evolution of their weight factors suggested important roles of long lifetimed cis states in azocarbazole derivatives. We also applied the method to the photodegradation of cyanine dyes doped in DNA-lipid complexes which have shown efficient and durable optical amplification and/or lasing under optical pumping. The same SVD method was successful in the extraction of two spectral components presumably due to monomer and H-type dimer. During the photodegradation process, absorption magnitude gradually decreased due to decomposition of molecules and their decaying rates strongly depended on the spectral components, suggesting that the long persistency of the dyes in DNA-complex related to weak tendency of aggregate formation.

  17. Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and First Results

    Science.gov (United States)

    Wang, Yuming; Zhou, Zhenjun; Zhang, Jie; Liu, Kai; Liu, Rui; Shen, Chenglong; Chamberlin, Phillip C.

    2016-01-01

    The Solar Dynamics Observatory (SDO)/EUV Variability Experiment (EVE) provides rich information on the thermodynamic processes of solar activities, particularly on solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. This tool could potentially be useful for extreme ultraviolet (EUV) astronomy to learn about the eruptive activities on distant astronomical objects. Through several cases, we illustrate what we can learn from the TDS charts. Furthermore, we apply the TDS method to 74 flares equal to or greater than the M5.0 class, and reach the following statistical results. First, EUV peaks are always behind the soft X-ray (SXR) peaks and stronger flares tend to have faster cooling rates. There is a power-law correlation between the peak delay times and the cooling rates, suggesting a coherent cooling process of flares from SXR to EUV emissions. Second, there are two distinct temperature drift patterns, called Type I and Type II. For Type I flares, the enhanced emission drifts from high to low temperature like a quadrilateral, whereas for Type II flares the drift pattern looks like a triangle. Statistical analysis suggests that Type II flares are more impulsive than Type I flares. Third, for late-phase flares, the peak intensity ratio of the late phase to the main phase is roughly correlated with the flare class, and the flares with a strong late phase are all confined. We believe that the re-deposition of the energy carried by a flux rope, which unsuccessfully erupts out, into thermal emissions is responsible for the strong late phase found in a confined flare. Furthermore, we show the signatures of the flare thermodynamic process in the chromosphere and transition region in the TDS charts. These results provide new clues to advance our understanding of the thermodynamic processes of solar flares and associated solar eruptions, e.g., coronal mass ejections.

  18. Autism spectrum disorder symptoms in children with ADHD: A community-based study.

    Science.gov (United States)

    Green, Jessica Leigh; Rinehart, Nicole; Anderson, Vicki; Nicholson, Jan M; Jongeling, Brad; Sciberras, Emma

    2015-12-01

    This study examined the prevalence of autism spectrum disorder (ASD) symptoms in a community-based sample of children with attention-deficit/hyperactivity disorder (ADHD) and non-ADHD controls. We also examined the relationship between ASD symptoms and ADHD subtype, ADHD symptom severity and child gender. Participants were 6-10-year-old children (164 ADHD; 198 non-ADHD control) attending 43 schools in Melbourne, Australia, who were participating in the Children's Attention Project. ADHD was assessed in two stages using the parent and teacher Conners' 3 ADHD index and the Diagnostic Interview Schedule for Children IV (DISC-IV). ASD symptoms were identified using the Social Communication Questionnaire (SCQ). Unadjusted and adjusted linear and logistic regression examined continuous and categorical outcomes, respectively. Children with ADHD had more ASD symptoms than non-ADHD controls (adjusted mean difference=4.0, 95% confidence interval (CI) 2.8; 5.3, p<0.001, effect size=0.7). Boys with ADHD had greater ASD symptom severity than girls with ADHD (adjusted mean difference=2.9, 95% CI 0.8; 5.2, p=0.01, effect size=0.4). Greater ADHD symptom severity was associated with greater ASD symptom severity (regression co-efficient=1.6, 95% CI 1.2; 2.0, p<0.001). No differences were observed by ADHD subtype. Greater hyperactive/impulsive symptoms were associated with greater ASD symptoms (regression coefficient=1.0; 95% CI 0.0; 2.0, p=0.04) however, this finding attenuated in adjusted analyses (p=0.45). ASD symptoms are common in children with ADHD. It is important for clinicians to assess for ASD symptoms to ensure appropriate intervention. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Air pollution and newly diagnostic autism spectrum disorders: a population-based cohort study in Taiwan.

    Directory of Open Access Journals (Sweden)

    Chau-Ren Jung

    Full Text Available There is limited evidence that long-term exposure to ambient air pollution increases the risk of childhood autism spectrum disorder (ASD. The objective of the study was to investigate the associations between long-term exposure to air pollution and newly diagnostic ASD in Taiwan. We conducted a population-based cohort of 49,073 children age less than 3 years in 2000 that were retrieved from Taiwan National Insurance Research Database and followed up from 2000 through 2010. Inverse distance weighting method was used to form exposure parameter for ozone (O3, carbon monoxide (CO, nitrogen dioxide (NO2, sulfur dioxide (SO2, and particles with aerodynamic diameter less than 10 µm (PM10. Time-dependent Cox proportional hazards (PH model was performed to evaluate the relationship between yearly average exposure air pollutants of preceding years and newly diagnostic ASD. The risk of newly diagnostic ASD increased according to increasing O3, CO, NO2, and SO2 levels. The effect estimate indicating an approximately 59% risk increase per 10 ppb increase in O3 level (95% CI 1.42-1.79, 37% risk increase per 10 ppb in CO (95% CI 1.31-1.44, 340% risk increase per 10 ppb increase in NO2 level (95% CI 3.31-5.85, and 17% risk increase per 1 ppb in SO2 level (95% CI 1.09-1.27 was stable with different combinations of air pollutants in the multi-pollutant models. Our results provide evident that children exposure to O3, CO, NO2, and SO2 in the preceding 1 year to 4 years may increase the risk of ASD diagnosis.

  20. Air pollution and newly diagnostic autism spectrum disorders: a population-based cohort study in Taiwan.

    Science.gov (United States)

    Jung, Chau-Ren; Lin, Yu-Ting; Hwang, Bing-Fang

    2013-01-01

    There is limited evidence that long-term exposure to ambient air pollution increases the risk of childhood autism spectrum disorder (ASD). The objective of the study was to investigate the associations between long-term exposure to air pollution and newly diagnostic ASD in Taiwan. We conducted a population-based cohort of 49,073 children age less than 3 years in 2000 that were retrieved from Taiwan National Insurance Research Database and followed up from 2000 through 2010. Inverse distance weighting method was used to form exposure parameter for ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particles with aerodynamic diameter less than 10 µm (PM10). Time-dependent Cox proportional hazards (PH) model was performed to evaluate the relationship between yearly average exposure air pollutants of preceding years and newly diagnostic ASD. The risk of newly diagnostic ASD increased according to increasing O3, CO, NO2, and SO2 levels. The effect estimate indicating an approximately 59% risk increase per 10 ppb increase in O3 level (95% CI 1.42-1.79), 37% risk increase per 10 ppb in CO (95% CI 1.31-1.44), 340% risk increase per 10 ppb increase in NO2 level (95% CI 3.31-5.85), and 17% risk increase per 1 ppb in SO2 level (95% CI 1.09-1.27) was stable with different combinations of air pollutants in the multi-pollutant models. Our results provide evident that children exposure to O3, CO, NO2, and SO2 in the preceding 1 year to 4 years may increase the risk of ASD diagnosis.

  1. Novel Maximum-based Timing Acquisition for Spread-Spectrum Communications

    Energy Technology Data Exchange (ETDEWEB)

    Sibbetty, Taylor; Moradiz, Hussein; Farhang-Boroujeny, Behrouz

    2016-12-01

    This paper proposes and analyzes a new packet detection and timing acquisition method for spread spectrum systems. The proposed method provides an enhancement over the typical thresholding techniques that have been proposed for direct sequence spread spectrum (DS-SS). The effective implementation of thresholding methods typically require accurate knowledge of the received signal-to-noise ratio (SNR), which is particularly difficult to estimate in spread spectrum systems. Instead, we propose a method which utilizes a consistency metric of the location of maximum samples at the output of a filter matched to the spread spectrum waveform to achieve acquisition, and does not require knowledge of the received SNR. Through theoretical study, we show that the proposed method offers a low probability of missed detection over a large range of SNR with a corresponding probability of false alarm far lower than other methods. Computer simulations that corroborate our theoretical results are also presented. Although our work here has been motivated by our previous study of a filter bank multicarrier spread-spectrum (FB-MC-SS) system, the proposed method is applicable to DS-SS systems as well.

  2. Power-law distributions based on exponential distributions: Latent scaling, spurious Zipf's law, and fractal rabbits

    CERN Document Server

    Chen, Yanguang

    2013-01-01

    The different between the inverse power function and the negative exponential function is significant. The former suggests a complex distribution, while the latter indicates a simple distribution. However, the association of the power-law distribution with the exponential distribution has been seldom researched. Using mathematical derivation and numerical experiments, I reveal that a power-law distribution can be created through averaging an exponential distribution. For the distributions defined in a 1-dimension space, the scaling exponent is 1; while for those defined in a 2-dimension space, the scaling exponent is 2. The findings of this study are as follows. First, the exponential distributions suggest a hidden scaling, but the scaling exponents suggest a Euclidean dimension. Second, special power-law distributions can be derived from exponential distributions, but they differ from the typical power-law distribution. Third, it is the real power-law distribution that can be related with fractal dimension. ...

  3. Middleware Based Model of Heterogeneous Systems for SCADA Distributed Applications

    Directory of Open Access Journals (Sweden)

    UNGUREAN, I.

    2010-05-01

    Full Text Available Infrastructure underlying the distributed information systems is heterogeneous and very complex. Middleware allows the development of distributed information systems, without knowing the functioning details of an infrastructure, by its abstracting. An essential issue on designing such systems is represented by choosing the middleware technologies. An architectural model of a SCADA system based on middleware is proposed in this paper. This system is formed of servers that centralize data and clients, which receive information from a server, thus allowing the chart displaying of such information. All these components own a specific functionality and can exchange information, by means of a middleware bus. A middleware bus signifies a software bus, where more middleware technologies can coexist.

  4. Building Distributed Web GIS: A Mobile-Agent Based Approach

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The diversity of GISs and the wide-spread availability of WWWhave l e d to an increasing amount of research on integrating a variety of heterogeneous and autonomous GISs in a cooperative environment to construct a new generation o f GIS characterizing in open architecture, distributed computation, interoperabi lity, and extensibility. Our on-going research project MADGI S (Mobile Agent based Distributed Geographic Information System) is reported, in which we pro pose the architecture of MADGIS to meet the requirements of integrating distribu ted GIS applications under Internet environment. We first describe the architect ure of MADGIS, and detailed discussions focusing on the structure of client site , server site and mobile agent in MADGIS. Then we explore key techniques for MAD GIS implementation.

  5. Incentive-Based Voltage Regulation in Distribution Networks

    Energy Technology Data Exchange (ETDEWEB)

    Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Baker, Kyri A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhou, Xinyang [University of Colorado; Chen, Lijun [University of Colorado

    2017-07-03

    This paper considers distribution networks fea- turing distributed energy resources, and designs incentive-based mechanisms that allow the network operator and end-customers to pursue given operational and economic objectives, while concurrently ensuring that voltages are within prescribed limits. Two different network-customer coordination mechanisms that require different amounts of information shared between the network operator and end-customers are developed to identify a solution of a well-defined social-welfare maximization prob- lem. Notably, the signals broadcast by the network operator assume the connotation of prices/incentives that induce the end- customers to adjust the generated/consumed powers in order to avoid the violation of the voltage constraints. Stability of the proposed schemes is analytically established and numerically corroborated.

  6. Distributed heterogeneous inspecting system and its middleware-based solution

    Institute of Scientific and Technical Information of China (English)

    黄理灿; 吴朝晖; 潘云鹤

    2003-01-01

    There are many cases when an organization needs to monitor the data and operations of its super-vised departments, especially those departments which are not owned by this organization and are managed by their own information systems. Distributed Heterogeneous Inspecting System (DHIS) is the system an organization uses to monitor its supervised departments by inspecting their information systems. In DHIS, the inspected systems are generally distributed, heterogeneous, and constructed by different companies. DHIS has three key processes-abstracting core data sets and core operation sets, collecting these sets, and inspecting these collected sets. In this paper, we present the concept and mathematical definition of DHIS, a metadata method for solving the interoperability, a security strategy for data transferring, and a middleware-based solution of DHIS. We also describe an example of the inspecting system at WENZHOU custom.

  7. Distributed heterogeneous inspecting system and its middleware-based solution

    Institute of Scientific and Technical Information of China (English)

    黄理灿; 吴朝晖; 潘云鹤

    2003-01-01

    There are many cases when an organization needs to monitor the data and operations of its supervised departments, especially those departments which are not owned by this organization and are managed by their own information systems. Distributed Heterogeneous Inspecting System (DHIS) is the system an organization uses to monitor its supervised departments by inspecting their information systems. In DHIS, the inspected systems are generally distributed, heterogeneous, and constructed by different companies. DHIS has three key processes-abstracting core data sets and core operation sets, collecting these sets, and inspecting these collected sets. In this paper, we present the concept and mathematical definition of DHIS, a metadata method for solving the interoperability, a security strategy for data transferring, and a middleware-based solution of DHIS. We also describe an example of the inspecting system at WENZHOU custom.

  8. Agent-based distributed hierarchical control of dc microgrid systems

    DEFF Research Database (Denmark)

    Meng, Lexuan; Vasquez, Juan Carlos; Guerrero, Josep M.

    2014-01-01

    In order to enable distributed control and management for microgrids, this paper explores the application of information consensus and local decisionmaking methods formulating an agent based distributed hierarchical control system. A droop controlled paralleled DC/DC converter system is taken...... as a case study. The objective is to enhance the system efficiency by finding the optimal sharing ratio of load current. Virtual resistances in local control systems are taken as decision variables. Consensus algorithms are applied for global information discovery and local control systems coordination....... Standard genetic algorithm is applied in each local control system in order to search for a global optimum. Hardware-in-Loop simulation results are shown to demonstrate the effectiveness of the method....

  9. Distributed query processing in flash-based sensor networks

    Institute of Scientific and Technical Information of China (English)

    Jianliang XU; Xueyan TANG; Wang-Chien LEE

    2008-01-01

    Wireless sensor networks are used in a large array of applications to capture,collect,and analyze physical environmental data.Many existing sensor systems instruct sensor nodes to report their measurements to central repositories outside the network,which is expensive in energy cost.Recent technological advances in flash memory have given rise to the development of storagecentric sensor networks,where sensor nodes are equipped with high-capacity flash memory storage such that sensor data can b.e stored and managed inside the network to reduce expensive communication.This novel architecture calls for new data management techniques to fully exploit distributed in-network data storage.This paper describes some of our research on distributed query processing in such flash-based sensor networks.Of particular interests are the issues that arise in the design of storage management and indexing structures combining sensor system workload and read/write/erase characteristics of flash memory.

  10. Distributed heterogeneous inspecting system and its middleware-based solution.

    Science.gov (United States)

    Huang, Li-can; Wu, Zhao-hui; Pan, Yun-he

    2003-01-01

    There are many cases when an organization needs to monitor the data and operations of its supervised departments, especially those departments which are not owned by this organization and are managed by their own information systems. Distributed Heterogeneous Inspecting System (DHIS) is the system an organization uses to monitor its supervised departments by inspecting their information systems. In DHIS, the inspected systems are generally distributed, heterogeneous, and constructed by different companies. DHIS has three key processes-abstracting core data sets and core operation sets, collecting these sets, and inspecting these collected sets. In this paper, we present the concept and mathematical definition of DHIS, a metadata method for solving the interoperability, a security strategy for data transferring, and a middleware-based solution of DHIS. We also describe an example of the inspecting system at WENZHOU custom.

  11. Efficient Model for Distributed Computing based on Smart Embedded Agent

    Directory of Open Access Journals (Sweden)

    Hassna Bensag

    2017-02-01

    Full Text Available Technological advances of embedded computing exposed humans to an increasing intrusion of computing in their day-to-day life (e.g. smart devices. Cooperation, autonomy, and mobility made the agent a promising mechanism for embedded devices. The work aims to present a new model of an embedded agent designed to be implemented in smart devices in order to achieve parallel tasks in a distribute environment. To validate the proposed model, a case study was developed for medical image segmentation using Cardiac Magnetic Resonance Image (MRI. In the first part of this paper, we focus on implementing the parallel algorithm of classification using C-means method in embedded systems. We propose then a new concept of distributed classification using multi-agent systems based on JADE and Raspberry PI 2 devices.

  12. Network Packet Length Covert Channel Based on Empirical Distribution Function

    Directory of Open Access Journals (Sweden)

    Lihua Zhang

    2014-06-01

    Full Text Available Network packet length covert channel modulates secret message bits onto the packet lengths to transmit secret messages. In this paper, a novel network packet length covert channel is proposed. The proposed scheme is based on the empirical distribution function of packet length series of legitimate traffic. Different from the existing schemes, the lengths of packets which are generated by the covert sender follow the distribution of normal traffic more closely in our scheme. To validate the security of the proposed scheme, the state-of-the-art packet length covert channel detection algorithm is adopted. The experimental results show that the packet length covert channel provides a significant performance improvement in detection resistance meanings

  13. Incentive-Based Voltage Regulation in Distribution Networks: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xinyang; Chen, Lijun; Dall' Anese, Emiliano; Baker, Kyri

    2017-03-03

    This paper considers distribution networks fea- turing distributed energy resources, and designs incentive-based mechanisms that allow the network operator and end-customers to pursue given operational and economic objectives, while concurrently ensuring that voltages are within prescribed limits. Two different network-customer coordination mechanisms that require different amounts of information shared between the network operator and end-customers are developed to identify a solution of a well-defined social-welfare maximization prob- lem. Notably, the signals broadcast by the network operator assume the connotation of prices/incentives that induce the end- customers to adjust the generated/consumed powers in order to avoid the violation of the voltage constraints. Stability of the proposed schemes is analytically established and numerically corroborated.

  14. Differential Protection for Distributed Micro-Grid Based on Agent

    Directory of Open Access Journals (Sweden)

    ZHOU Bin

    2013-05-01

    Full Text Available The Micro-grid, even though not a replacement of the conventional centralized power transmission grid, plays a very important role in the success of rapid development of renewable energy resources technologies. Due to the facts of decentralization, independence and dynamic of sources within a Micro-grid, a high level automation of protection is a must. Multi-Agent system as a approach to handle distributed system issues has been developed. This paper presents an MAS based differential protection method for distributed micro-grid. The nodes within a micro-grid are divided into primary and backup protection zones. The agents follow predefined rules to take actions to protect the system and isolate the fault when it happens. Furthermore, an algorithm is proposed to achieve high availability in case of Agent itself malfunction. The method is using Matlab for simulation and shows it satisfies relay protection in terms of the selectivity, sensitivity, rapidity and reliability requirements.

  15. A Semantics-Based Information Distribution Framework for Large Web-Based Course Forum System

    Science.gov (United States)

    Chim, Hung; Deng, Xiaotie

    2008-01-01

    We propose a novel data distribution framework for developing a large Web-based course forum system. In the distributed architectural design, each forum server is fully equipped with the ability to support some course forums independently. The forum servers collaborating with each other constitute the whole forum system. Therefore, the workload of…

  16. ULTRA STEEP SPECTRUM RADIO SOURCES IN THE LOCKMAN HOLE: SERVS IDENTIFICATIONS AND REDSHIFT DISTRIBUTION AT THE FAINTEST RADIO FLUXES

    Energy Technology Data Exchange (ETDEWEB)

    Afonso, J.; Bizzocchi, L.; Grossi, M.; Messias, H.; Fernandes, C. A. C. [Observatorio Astronomico de Lisboa, Faculdade de Ciencias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal); Ibar, E.; Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Simpson, C. [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom); Chapman, S.; Gonzalez-Solares, E. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Jarvis, M. J. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Rottgering, H. [Leiden Observatory, Leiden University, Oort Gebouw, P.O. Box 9513, 2300 RA Leiden (Netherlands); Norris, R. P. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Dunlop, J.; Best, P. [SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Pforr, J. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Vaccari, M. [Department of Astronomy, University of Padova, vicolo Osservatorio 3, 35122 Padova (Italy); Seymour, N. [Mullard Space Science Laboratory, UCL, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Farrah, D. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Huang, J.-S., E-mail: jafonso@oal.ul.pt [Department of Astrophysics, Oxford University, Keble Road, Oxford OX1 3RH (United Kingdom); and others

    2011-12-20

    Ultra steep spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z {approx}> 2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610 MHz integrated fluxes above 100 {mu}Jy, is assembled. Deep infrared data at 3.6 and 4.5 {mu}m from the Spitzer Extragalactic Representative Volume Survey (SERVS) are used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6]{sub AB} = 19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of the deep SERVS data, for a further 19 objects, show redshifts ranging from z = 0.1 to z = 2.8, peaking at z {approx} 0.6 and tailing off at high redshifts. The remaining 25 USS sources, with no redshift estimate, include the faintest [3.6] magnitudes, with 10 sources undetected at 3.6 and 4.5 {mu}m (typically [3.6] {approx}> 22-23 mag from local measurements), which suggests the likely existence of higher redshifts among the sub-mJy USS population. The comparison with the Square Kilometre Array Design Studies Simulated Skies models indicates that Fanaroff-Riley type I radio sources and radio-quiet active galactic nuclei may constitute the bulk of the faintest USS population, and raises the possibility that the high efficiency of the USS technique for the selection of high-redshift sources remains even at the sub-mJy level.

  17. Joint Resource Allocation of Spectrum Sensing and Energy Harvesting in an Energy-Harvesting-Based Cognitive Sensor Network.

    Science.gov (United States)

    Liu, Xin; Lu, Weidang; Ye, Liang; Li, Feng; Zou, Deyue

    2017-03-16

    The cognitive sensor (CS) can transmit data to the control center in the same spectrum that is licensed to the primary user (PU) when the absence of the PU is detected by spectrum sensing. However, the battery energy of the CS is limited due to its small size, deployment in atrocious environments and long-term working. In this paper, an energy-harvesting-based CS is described, which senses the PU together with collecting the radio frequency energy to supply data transmission. In order to improve the transmission performance of the CS, we have proposed the joint resource allocation of spectrum sensing and energy harvesting in the cases of a single energy-harvesting-based CS and an energy-harvesting-based cognitive sensor network (CSN), respectively. Based on the proposed frame structure, we have formulated the resource allocation as a class of joint optimization problems, which seek to maximize the transmission rate of the CS by jointly optimizing sensing time, harvesting time and the numbers of sensing nodes and harvesting nodes. Using the half searching method and the alternating direction optimization, we have achieved the sub-optimal solution by converting the joint optimization problem into several convex sub-optimization problems. The simulation results have indicated the predominance of the proposed energy-harvesting-based CS and CSN models.

  18. Properties of the Intensity Distribution and the Angular Spectrum of a Gaussian Beam with Local Phase Modulation%高斯光束经局域相位调制后的光强分布和角谱特性

    Institute of Scientific and Technical Information of China (English)

    苏倩倩; 张国文; 陶华; 蒲继雄

    2011-01-01

    光学元件上不可避免地存在的“缺陷”会对传输光束产生局域振幅和相位调制.基于菲涅耳衍射积分,建立了高斯光束经局域相位调制后的传输模型,得到了高斯光束经有限多个小尺寸局域相位调制后的光强分布和角谱解析式,详细研究了相位调制尺寸与调制深度对光束光强分布和角谱的影响.结果表明,不同调制尺寸、调制深度对高斯光束在传输过程中的影响相似.且调制深度越大,产生的最大光强越大.相位“缺陷”尺寸越大产生的最大光强的位置离“缺陷”越远,随着调制深度、尺寸的增大和调制位置距光轴距离越近,低频区的角谱越小,中高频区的角谱越大.%The unavoidable defects exists in the optical component will modulate the phase and the amplitude of the beam propagate in the system. Based on the Fresnel diffraction integral, the propagation mode of the Gaussian beam modulated by the local phase is built and the analytical expressions for the intensity distribution and angular spectrum of a Gaussian beam modulated by finite phase modulated defects has been derived. The impact of the modulation depth and the size of the defects on the intensity distribution and angular spectrum of the beam modulated by phase modulated defects is studied. It shows that in the process of transmission the evolution of the light intensity is the same for different modulation depths and sizes of the defects. The deeper of the modulation depth of defects that modulated the beam, the higher of the intensity produced along the propagation process. The larger of the defect, the nearer of the proposition where produced the highest intensity from the defects location. The angular spectrum in the low frequency area become smaller and the angular spectrum in the high frequency area become greater with the increase of modulation depth and the size of the defect as well as the defect getting closer to the middle of the beam.

  19. Investigation on full distribution CNC system based on SERCOS bus

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A full distribution CNC system based on SERCOS bus is studied in accordance with the limitations of traditional PC-based motion card.The conventional PC-based motion control card is dispersed into several autonomous intelligent servo-control units with the function of servo driver.The autonomous intelligent servocontrol units realize the loop control of position,velocity and current.Interpolation computation is completed in PC and the computational results are transferred to every autonomous intelligent servo-control unit by high speed SERCOS bus.Software or hardware synchronization technology is used to ensure all servomotors are successive and synchronously running.The communication and synchronization technology of SERCOS are also researched and the autonomous intelligent servo-control card is developed byself.Finally,the experiment of circle contour process on a prototype system proves the feasibility.

  20. Task Scheduling problem in distributed systems considering communication cost and precedence by population-based ACO

    Directory of Open Access Journals (Sweden)

    Hossein Erfani

    2012-09-01

    Full Text Available With regard to the fact of the rapid growth of distributed systems and their large spectrum of usage of proposing and representing controlling solutions and optimization of task execution procedures is one of the most important issues. Task scheduling in distributed systems has determining role in improving efficiency in applications such as communication, routing, production plans and project management. The most important issues of good schedule are minimizing makespan and average of waiting time. However, the recent and previous effort usually focused on minimizing makespan. This article presents and analyze a new method based on Ant Colony Optimization (ACO algorithm with considerations to precedence and communication cost for task scheduling problem. In the mentioned method in addition to optimization of finish time, average of waiting time and number of needed processors are also optimized. In this method, by using of a new heuristic list, an algorithm based on ant colony is proposed. The results obtained in comparison with the latest similar models of random search algorithms, proves the higher efficiency of algorithm.

  1. The spectral theorem for quaternionic unbounded normal operators based on the S-spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Alpay, Daniel, E-mail: dany@math.bgu.ac.il; Kimsey, David P., E-mail: dpkimsey@gmail.com [Department of Mathematics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Colombo, Fabrizio, E-mail: fabrizio.colombo@polimi.it [Politecnico di Milano, Dipartimento di Matematica, Via E. Bonardi, 9, 20133 Milano (Italy)

    2016-02-15

    In this paper we prove the spectral theorem for quaternionic unbounded normal operators using the notion of S-spectrum. The proof technique consists of first establishing a spectral theorem for quaternionic bounded normal operators and then using a transformation which maps a quaternionic unbounded normal operator to a quaternionic bounded normal operator. With this paper we complete the foundation of spectral analysis of quaternionic operators. The S-spectrum has been introduced to define the quaternionic functional calculus but it turns out to be the correct object also for the spectral theorem for quaternionic normal operators. The lack of a suitable notion of spectrum was a major obstruction to fully understand the spectral theorem for quaternionic normal operators. A prime motivation for studying the spectral theorem for quaternionic unbounded normal operators is given by the subclass of unbounded anti-self adjoint quaternionic operators which play a crucial role in the quaternionic quantum mechanics.

  2. Hard Decision Fusion based Cooperative Spectrum Sensing in Cognitive Radio System

    Directory of Open Access Journals (Sweden)

    N. Armi N.M. Saad

    2013-09-01

    Full Text Available Cooperative spectrum sensing was proposed to combat fading, noise uncertainty, shadowing, and even hidden node problem due to primary users (PUs activity that is not spatially localized. It improves the probability of detection by collaborating to detect PUs signal in cognitive radio (CR system as well. This paper studies cooperative spectrum sensing and signal detection in CR system by implementing hard decision combining in data fusion centre. Through computer simulation, we evaluate the performances of cooperative spectrum sensing and signal detection by employing OR and AND rules as decision combining. Energy detector is used to observe the presence of primary user (PU signal. Those results are compared to non-cooperative signal detection for evaluation. They show that cooperative technique has better performance than non-cooperative. Moreover, signal to noise ratio (SNR with greater than or equal 10 dB and 15 collaborated users in CR system has optimal value for probability of detection.

  3. The spectrum and spatial distribution of cyanogen in comet Hale-Bopp (C/1995 O1) at large heliocentric distance.

    Science.gov (United States)

    Wagner, R M; Schleicher, D G

    1997-03-28

    Optical spectra of comet Hale-Bopp (C/1995 O1) at a heliocentric distance of 6.45 astronomical units showed emission from cyanogen gas. The spatial distribution of cyanogen was considerably more diffuse and extended compared to the spatial profile of the dust or grains which were sharply peaked near the center. This behavior is consistent with comets at smaller heliocentric distances suggesting the same or a similar formation mechanism. A cyanogen gas production rate of (1.2 +/- 0.3) x10(26) molecules per second was derived. A model band profile derived from fluorescence equilibrium calculations for the comet's heliocentric velocity and distance agrees with the observed band profile.

  4. The Simulation of Direct Spread Spectrum System based on Transmitted Reference Signal

    Directory of Open Access Journals (Sweden)

    Wu Guoqiang

    2013-01-01

    Full Text Available Code synchronization is indispensable in the direct spread spectrum system because it can influence the incepting capacity directly. Transmitted reference is proposed in this paper to predigest the code synchronization circuit of the incepting machine in order to reduce the cost of time, energy and money for the development of the code synchronization technology. The software named Systemview is employed to simulate the transmitted reference direct spread spectrum system. The simulation results were presented with the condition of gauss noise and temperature. It demonstrates that the proposed simulation has significant effect and benefit in engineering.

  5. Performance-based placement of manufactured viscoelastic dampers for design response spectrum

    Directory of Open Access Journals (Sweden)

    Yutaka eNakamura

    2016-05-01

    Full Text Available In this study, a viscoelastic damper (VED is developed by using a VE material with low temperature dependence, and a performance-based placement-design procedure of VEDs is developed for finding the storywise distribution of VEDs in a building such that each peak interstory drift coincides with the prescribed value. The mechanical properties of the employed VED’s dependence on amplitude and frequency of the excitation as well as material temperature are taken into account and a mechanical nonlinear four-element model that comprises two dashpot elements and two spring elements is proposed for the VED. The developed performance-based design procedure utilizes equivalent linearization of the VED and the expanded complete quadratic combination (CQC method, which involves modal analysis with complex eigenvalue analysis. An equivalent linear Voigt model of the VED is determined by the prescribed peak interstory drift and the fundamental natural period of the structure for which the VEDs are installed. Seismic response analyses are carried out for high-rise building models installed with the necessary number of wall-type VEDs, with the results demonstrating the effectiveness and validity of the proposed performance-based placement-design procedure.

  6. A Multi-Agent System Based Protection and Control Scheme for Distribution System with Distributed Generation Integration

    DEFF Research Database (Denmark)

    Liu, Z.; Su, Chi; Hoidalen, Hans

    2017-01-01

    In this paper, a multi agent system (MAS) based protection and control scheme is proposed to deal with diverse operation conditions in distribution system due to distributed generation (DG) integration. Based on cooperation between DG controller and relays, an adaptive protection and control...... of system topology and DG status. The proposed scheme is tested and validated on a test distribution system in a hardware-in-the-loop real time testing platform....

  7. PLC BASED RATIO CONTROLLER AND MATERIAL DISTRIBUTION SYSTEM

    Directory of Open Access Journals (Sweden)

    V. M. Badwaik Prof. V. M. Umale

    2012-04-01

    Full Text Available Automation in an industry using programmable logic controller (PLC can be enumerated by optimizing the use of process control equipment, decreases the response time for process and equipment contingencies, provides information about process status, manages process logic at the plant floor level and increases overall productivity and plant efficiency. The primary reason for designing such a system is to eliminate large cost involved in replacing complicated relay based machine control system & to reduce process time. Ratio control system is feed forward system where one variable is controlled in ratio to another to satisfy some higher level objectives. Two difference chemicals are supplied from different tanks in proper ratio by maintaining the flow of quantity. Then desired mixture is obtained &checks the ratio of composition if any unbalanced, controlled by controlled values of supply tanks. Then this mixture is distributed as per requirements. In Industries for ten machines, total cycle time with existing PLC based system is 75 sec. But our modified PLC based system total cycle time is improved as 45 sec. Hence total reach time of distribution system is improved.

  8. Inspection-Repair based Availability Optimization of Distribution Systems using Teaching Learning based Optimization

    Science.gov (United States)

    Tiwary, Aditya; Arya, L. D.; Arya, Rajesh; Choube, S. C.

    2016-09-01

    This paper describes a technique for optimizing inspection and repair based availability of distribution systems. Optimum duration between two inspections has been obtained for each feeder section with respect to cost function and subject to satisfaction of availability at each load point. Teaching learning based optimization has been used for availability optimization. The developed algorithm has been implemented on radial and meshed distribution systems. The result obtained has been compared with those obtained with differential evolution.

  9. BrainBrowser: distributed, web-based neurological data visualization.

    Science.gov (United States)

    Sherif, Tarek; Kassis, Nicolas; Rousseau, Marc-Étienne; Adalat, Reza; Evans, Alan C

    2014-01-01

    Recent years have seen massive, distributed datasets become the norm in neuroimaging research, and the methodologies used to analyze them have, in response, become more collaborative and exploratory. Tools and infrastructure are continuously being developed and deployed to facilitate research in this context: grid computation platforms to process the data, distributed data stores to house and share them, high-speed networks to move them around and collaborative, often web-based, platforms to provide access to and sometimes manage the entire system. BrainBrowser is a lightweight, high-performance JavaScript visualization library built to provide easy-to-use, powerful, on-demand visualization of remote datasets in this new research environment. BrainBrowser leverages modern web technologies, such as WebGL, HTML5 and Web Workers, to visualize 3D surface and volumetric neuroimaging data in any modern web browser without requiring any browser plugins. It is thus trivial to integrate BrainBrowser into any web-based platform. BrainBrowser is simple enough to produce a basic web-based visualization in a few lines of code, while at the same time being robust enough to create full-featured visualization applications. BrainBrowser can dynamically load the data required for a given visualization, so no network bandwidth needs to be waisted on data that will not be used. BrainBrowser's integration into the standardized web platform also allows users to consider using 3D data visualization in novel ways, such as for data distribution, data sharing and dynamic online publications. BrainBrowser is already being used in two major online platforms, CBRAIN and LORIS, and has been used to make the 1TB MACACC dataset openly accessible.

  10. BrainBrowser: distributed, web-based neurological data visualization

    Directory of Open Access Journals (Sweden)

    Tarek eSherif

    2015-01-01

    Full Text Available Recent years have seen massive, distributed datasets become the norm in neuroimaging research, and the methodologies used analyze them have, in response, become more collaborative and exploratory. Tools and infrastructure are continuously being developed and deployed to facilitate research in this context: grid computation platforms to process the data, distributed data stores to house and share them, high-speed networks to move them around and collaborative, often web-based, platforms to provide access to and sometimes manage the entire system. BrainBrowser is a lightweight, high-performance JavaScript visualization library built to provide easy-to-use, powerful, on-demand visualization of remote datasets in this new research environment. BrainBrowser leverages modern Web technologies, such as WebGL, HTML5 and Web Workers, to visualize 3D surface and volumetric neuroimaging data in any modern web browser without requiring any browser plugins. It is thus trivial to integrate BrainBrowser into any web-based platform. BrainBrowser is simple enough to produce a basic web-based visualization in a few lines of code, while at the same time being robust enough to create full-featured visualization applications. BrainBrowser can dynamically load the data required for a given visualization, so no network bandwidth needs to be waisted on data that will not be used. BrainBrowser's integration into the standardized web platform also allows users to consider using 3D data visualization in novel ways, such as for data distribution, data sharing and dynamic online publications. BrainBrowser is already being used in two major online platforms, CBRAIN and LORIS, and has been used to make the 1TB MACACC dataset openly accessible.

  11. BrainBrowser: distributed, web-based neurological data visualization

    Science.gov (United States)

    Sherif, Tarek; Kassis, Nicolas; Rousseau, Marc-Étienne; Adalat, Reza; Evans, Alan C.

    2015-01-01

    Recent years have seen massive, distributed datasets become the norm in neuroimaging research, and the methodologies used to analyze them have, in response, become more collaborative and exploratory. Tools and infrastructure are continuously being developed and deployed to facilitate research in this context: grid computation platforms to process the data, distributed data stores to house and share them, high-speed networks to move them around and collaborative, often web-based, platforms to provide access to and sometimes manage the entire system. BrainBrowser is a lightweight, high-performance JavaScript visualization library built to provide easy-to-use, powerful, on-demand visualization of remote datasets in this new research environment. BrainBrowser leverages modern web technologies, such as WebGL, HTML5 and Web Workers, to visualize 3D surface and volumetric neuroimaging data in any modern web browser without requiring any browser plugins. It is thus trivial to integrate BrainBrowser into any web-based platform. BrainBrowser is simple enough to produce a basic web-based visualization in a few lines of code, while at the same time being robust enough to create full-featured visualization applications. BrainBrowser can dynamically load the data required for a given visualization, so no network bandwidth needs to be waisted on data that will not be used. BrainBrowser's integration into the standardized web platform also allows users to consider using 3D data visualization in novel ways, such as for data distribution, data sharing and dynamic online publications. BrainBrowser is already being used in two major online platforms, CBRAIN and LORIS, and has been used to make the 1TB MACACC dataset openly accessible. PMID:25628562

  12. The Distributed Seismological Observatory: A Web Based Seismological Data Analysis and Distribution Toolkit

    Science.gov (United States)

    Govoni, A.; Lomax, A.; Michelini, A.

    The Web now provides a single, universal infrastructure for developing client/server data access applications and the seismology community can greatly benefit of this situation both for the routine observatory data analysis and for research purposes. The Web has reduced the myriad of platforms and technologies used to handle and exchange data to a single user interface (HTML), a single client platform (the Web browser), a single network protocol (HTTP), and a single server platform (the Web server). In this context we have designed a system that taking advantage of the latest devel- opment in the client/server data access technologies based on JAVA, JAVA RMI and XML may solve the most common problems in the data access and manipulation com- monly experienced in the seismological community. Key concepts in this design are thin client approach, minimum standards for data exchange and distributed computing. Thin client means that any PC with a JAVA enabled Web browser can interact with a set of remote data servers distributed in the world computer network querying for data and for services. Minimum standards relates to the language needed for client/server interaction that must be abstract enough to avoid that everybody know all the details of the transaction and this is solved by XML. Distribution means that a set of servers is able to provide to the client not only a data object (the actual data and the methods to work on it) but also the computing power to perform a particular task (a remote method in the JAVA RMI context) and limits the exchange of data to the results. This allows for client interaction also in very limited communication bandwidth situations. We describe in detail also the implementation of the main modules of the toolkit. A data eater module that gathers/archives seismological data from a variety of sources ranging from portable digitizers data to real-time network data. A picking/location server that allows for multi user Web based analysis of

  13. Model-based segmentation of medical imagery by matching distributions.

    Science.gov (United States)

    Freedman, Daniel; Radke, Richard J; Zhang, Tao; Jeong, Yongwon; Lovelock, D Michael; Chen, George T Y

    2005-03-01

    The segmentation of deformable objects from three-dimensional (3-D) images is an important and challenging problem, especially in the context of medical imagery. We present a new segmentation algorithm based on matching probability distributions of photometric variables that incorporates learned shape and appearance models for the objects of interest. The main innovation over similar approaches is that there is no need to compute a pixelwise correspondence between the model and the image. This allows for a fast, principled algorithm. We present promising results on difficult imagery for 3-D computed tomography images of the male pelvis for the purpose of image-guided radiotherapy of the prostate.

  14. An Ethernet LAN based distributed generation system load shedding strategy

    DEFF Research Database (Denmark)

    Wei, Mu; Chen, Zhe

    2011-01-01

    This paper firstly analyzes and compares various communication technologies, and proposes a communication system for a distributed generation system (DGS) with wind turbines. Then the paper presents a novel simulation method of considering the interactions between the communication system and power...... system, by using two software platforms: OPNET and EMTDC/PSCAD. A control method based on the communication technique has been designed to stabilize the DG system during power system disturbances. A case study is presented to demonstrate the effectiveness of the proposed communication system, simulation...... method and control strategy....

  15. Agent-based Algorithm for Spatial Distribution of Objects

    KAUST Repository

    Collier, Nathan

    2012-06-02

    In this paper we present an agent-based algorithm for the spatial distribution of objects. The algorithm is a generalization of the bubble mesh algorithm, initially created for the point insertion stage of the meshing process of the finite element method. The bubble mesh algorithm treats objects in space as bubbles, which repel and attract each other. The dynamics of each bubble are approximated by solving a series of ordinary differential equations. We present numerical results for a meshing application as well as a graph visualization application.

  16. Room Acoustical Simulation Algorithm Based on the Free Path Distribution

    Science.gov (United States)

    VORLÄNDER, M.

    2000-04-01

    A new algorithm is presented which provides estimates of impulse responses in rooms. It is applicable to arbitrary shaped rooms, thus including non-diffuse spaces like workrooms or offices. In the latter cases, for instance, sound propagation curves are of interest to be applied in noise control. In the case of concert halls and opera houses, the method enables very fast predictions of room acoustical criteria like reverberation time, strength or clarity. The method is based on a low-resolved ray tracing and recording of the free paths. Estimates of impulse responses are derived from evaluation of the free path distribution and of the free path transition probabilities.

  17. Quantum key distribution based on phase encoding and polarization measurement

    CERN Document Server

    Ma, H Q; Zhao, J L; Ma, Hai-Qiang; Wu, Ling-An; Zhao, Jian-Ling

    2007-01-01

    A one-way quantum key distribution scheme based on intrinsically stable Faraday-mirror type Michelson interferometers with four-port polarizing beampslitters has been demonstrated which can compensate for birefringence effects automatically. The encoding is performed with phase modulators, but decoding is accomplished through measurement of the polarization state of Bob's photons. An extinction ratio of about 30dB was maintained for several hours over 50km of fiber at 1310nm without any adjustment to the setup, which shows its good potential for practical systems

  18. Distributed optical fiber dynamic magnetic field sensor based on magnetostriction.

    Science.gov (United States)

    Masoudi, Ali; Newson, Trevor P

    2014-05-01

    A distributed optical fiber sensor is introduced which is capable of quantifying multiple magnetic fields along a 1 km sensing fiber with a spatial resolution of 1 m. The operation of the proposed sensor is based on measuring the magnetorestrictive induced strain of a nickel wire attached to an optical fiber. The strain coupled to the optical fiber was detected by measuring the strain-induced phase variation between the backscattered Rayleigh light from two segments of the sensing fiber. A magnetic field intensity resolution of 0.3 G over a bandwidth of 50-5000 Hz was demonstrated.

  19. Polarimetric Edge Detector Based on the Complex Wishart Distribution

    DEFF Research Database (Denmark)

    Skriver, Henning; Schou, Jesper; Nielsen, Allan Aasbjerg

    2001-01-01

    A new edge detector for polarimetric SAR data has been developed. The edge detector is based on a newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic. The new...... polarimetric edge detector provides a constant false alarm rate and it utilizes the full polarimetric information. The edge detector has been applied to polarimetric SAR data from the Danish dual-frequency, airborne polarimetric SAR, EMISAR. The results show clearly an improved edge detection performance...

  20. Quantum election scheme based on anonymous quantum key distribution

    Institute of Scientific and Technical Information of China (English)

    Zhou Rui-Rui; Yang Li

    2012-01-01

    An unconditionally secure authority-certified anonymous quantum key distribution scheme using conjugate coding is presented,based on which we construct a quantum election scheme without the help of an entanglement state.We show that this election scheme ensures the completeness,soundness,privacy,eligibility,unreusability,fairness,and verifiability of a large-scale election in which the administrator and counter are semi-honest.This election scheme can work even if there exist loss and errors in quantum channels.In addition,any irregularity in this scheme is sensible.